review article environmental impact on dna methylation in

Review ArticleEnvironmental Impact on DNA Methylation in the GermlineState of the Art and Gaps of Knowledge

Francesca Pacchierotti and Marcello Spanograve

Laboratory of Toxicology Technical Unit of Radiation Biology and Human Health CR Casaccia ENEAVia Anguillarese 301 00123 Rome Italy

Correspondence should be addressed to Francesca Pacchierotti francescapacchierottieneait

Received 14 January 2015 Accepted 3 May 2015

Academic Editor Heide Schatten

Copyright copy 2015 F Pacchierotti and M SpanoThis is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in anymedium provided the originalwork is properly cited

The epigenome consists of chemical changes in DNA and chromatin that without modifying the DNA sequence modulate geneexpression and cellular phenotype The epigenome is highly plastic and reacts to changing external conditions with modificationsthat can be inherited to daughter cells and across generations Whereas this innate plasticity allows for adaptation to a changingenvironment it also implies the potential of epigenetic derailment leading to so-called epimutations DNA methylation is themost studied epigenetic mark DNA methylation changes have been associated with cancer infertility cardiovascular respiratorymetabolic immunologic and neurodegenerative pathologies Experiments in rodents demonstrate that exposure to a variety ofchemical stressors occurring during the prenatal or the adult life may induce DNAmethylation changes in germ cells which maybe transmitted across generations with phenotypic consequences An increasing number of human biomonitoring studies showenvironmentally related DNA methylation changes mainly in blood leukocytes whereas very few data have been so far collectedon possible epigenetic changes induced in the germline even by the analysis of easily accessible sperm In this paper we review thestate of the art on factors impinging on DNA methylation in the germline highlight gaps of knowledge and propose priorities forfuture studies

1 Introduction

Epigenetics formally refers to heritable changes in geneexpression and in phenotype occurring without changesin the underlying DNA sequence Alterations in epigeneticmarks have been involved in the etiology of complex syn-dromes and diseases including cancer infertility cardiovas-cular respiratory metabolic immunologic and neurodegen-erative pathologies [1ndash3] The main epigenetic mechanismsresponsible for these alterations are represented by DNAmethylation posttranslational histone modifications andregulation by noncoding microRNAs [4] In particular DNAmethylation themost studied epigeneticmark so far involvesthe enzymatically mediated covalent addition of a methylgroup to the C5 position of cytosine forming 5-methylcytosine (5-mC) Cytosine methylation primarily happensin CpG dinucleotides in CpG-rich sequences dubbed asCpG islands often occurring near or in the gene promoter

regions DNA methylation operated by a family of DNAmethyltransferases [5] is implicated in many life-essentialcellular and developmental processes such as embryonicreprogramming cellular differentiation silencing of genesand transposons parental imprinting X chromosome inac-tivation and genomic stability [6ndash8]

It is largely accepted that exposure to a variety of environ-mental toxicants has a negative impact on human health andcontributes to the development of a large array of diseasesThe epigenome is more plastic and flexible than the genomeChanges of epigenetic marks such as DNA methylationcan affect the chromatin structure and modify binding oftranscription factors and gene expression The theoreticalframework of a changing environment and a modifiableepigenome might offer unexplored and unsuspected ways tounderstand gene-environment interactions and potentiallymitigate the impact of environmental toxicants on humanhealth [9 10]

Hindawi Publishing CorporationBioMed Research InternationalVolume 2015 Article ID 123484 23 pageshttpdxdoiorg1011552015123484

2 BioMed Research International

A rapidly growing number of epidemiological studieshave been carried out throughout the world in whichenvironmental exposure and lifestyle (an umbrella termincluding diet behavior stress physical activity workinghabits voluntary alcohol and tobacco consumption etc)meshed with the genetic background have been associatedwith epigenetic changes mostly DNAmethylation (reviewedin [11ndash18]) The trend in the field appears to shift fromthe introduction of a novel ldquoproof-of-principlerdquo approach intoxicology to a more systematic scientific specialty [19 20]

Environmental epidemiology research is addressing epi-genetic mechanisms as mediators of environmental exposureon disease risk or just as biosensors of exposure even ifnot mechanistically relevant Because stable methylationmarks at differentially methylated regions (DMRs) regulatingimprinted genes are acquired before gastrulation they mayserve as archives of early exposure with the potential toimprove our understanding of developmental origin of adultdiseases

DNA methylation has been by far the most extensivelymeasured epigenetic mark because of its obviously funda-mental biological interest its mitotic stability the availabilityof methods for its quantification globally or in targetedregions its stability during the DNA extraction and purifi-cation procedures and its durability in archival biologicalmaterials By and large the strategy consists of comparativelyassessing the methylation differences at CpG islands in genepromoters or DMRs between control and exposed groups

The information on DNAmethylation status and changesin association with environmental exposure and lifestylehas been mostly collected from peripheral blood leukocytes(PBL) which can be sampled by a minimally invasiveapproach However tissue specificity together with purityof cells for DNA methylation determination represents arelevant issue in epigenetic studies as each tissue and within atissue probably each cell type have its own epigenetic profile

During our lifetime the genome undergoes two mainepigenomic reprogramming periods each of which involveswaves ofDNAdemethylation andde novomethylationTheseprecise and coordinated genome-wide reprogramming stepsare associated with pivotal developmental stages like theestablishment of cell totipotency and the differentiation of thegerm cell lineages [21 22]The first wave occurs with notabledifferences between sexes in all cells of the preimplantationembryo The second wave occurs in primordial germ cells(PGCs) only this time the demethylation events are moreradical and involve imprinted genes whose allelic-specificmethylation is first erased and then reset according to thesex of the germline [23] Conceivably these phases of mam-malian development are especially sensitive to environmentalstressors which can impact epigenetic plasticity with poten-tial enduring effects on metabolic pathways and disease sus-ceptibility Indeed such scenario would be in agreement withthe theory of the fetal basis of adult onset disease [24ndash26]

The early fetal period of life is particularly criticalfor gonadal development and many common reproductivedisorders of the adult male such as infertility and testiscancer have been proposed to have a fetal origin [27] Inaddition prenatal exposure to environmental contaminants

especially those belonging to the variegated and heteroge-neous class of compounds collectively defined as endocrinedisruptors (EDs) has been linked to the increased incidenceof male reproductive pathologies [28ndash32] The interferencewith developmental epigenetic processes has been evoked asone of the potential mechanisms of EDs action affecting theintegrity of the male reproductive system [33] Recent evi-dence that unbalanced one carbon metabolism may impactmale reproductive health [34] and that a variety of epigeneticmarkers including global or gene-specific DNAmethylationcan be altered in infertility patients [35 36] is in agreementwith this hypothesis

In spite of the extensive DNA demethylation occurringin preimplantation embryonic cells there are sequencescorresponding primarily but not exclusively to parentallyimprinted genes that escape global demethylation [37 38]This means that changes of DNA methylation induced byenvironmental stressors in germ cells could not only haveconsequences for the reproductive health of the exposedindividual but also might be potentially heritable from onegeneration to another and might cause transgenerationaladverse effects by a nongenetic mechanism of inheritance

Notwithstanding the knowledge about epigenetic reg-ulation of gonadal development and the evidence aboutepigenetic changes induced in rodent germline by severalchemicals or dietary conditions the number of studies aimedat testing possible effects of lifestyle or chemical exposureon human sperm DNA methylation is extremely limited incomparison to the number of studies carried out on bloodcells Sperm can be obtained by a similarly noninvasiveprocedure they represent the target cell formale reproductiveeffects and not merely a surrogate of it their ultimate DNAmethylation pattern is acquired by amultistep process startedin PGCs and completed during the spermatogonia andspermatocyte differentiation phases [39 40] which mighttherefore be repeatedly exposed to environmental insultsFor all these reasons it would be very valuable to extendthe analysis of sperm epigenetics beyond infertility clinicalinvestigation to environmental biomonitoring studies

Focus of this literature review will be on data linkingvarious exogenous factors from specific chemical exposureto psychological stress to DNA methylation changes inthe germline and their consequences in the offspring Wehave taken into consideration both experimental rodent andhuman studies In addition due to the very limited amountof data from human biomonitoring investigations we havedecided to include a survey of papers reporting human popu-lation studies which have shown an environmental impact onDNAmethylation of somatic cells to highlight those sourcesof exposure that would be worth further germline-orientedinvestigations and the present gaps of knowledge

2 Human Studies on EnvironmentallyLinked DNA Methylation Changes inSomatic and Germ Cells

Several recent and excellent reviews [12 13 15 17 41 42]have been published on this subject Here we try to offer an

BioMed Research International 3

original aggregation pattern of the data which are mostlyvery recent but often incomplete and methodologicallyheterogeneous to highlight research trends and gaps ofknowledge also in relation to experimental rodent studiesThe epidemiological studies specifically reporting the effectsof environmental chemicals on DNA methylation aresummarized in Table 1

21 Metals Arsenic Chromium Cadmium Lead Mercuryand Selenium Environmental toxic metals have been asso-ciated with important human pathologies like cancer cardio-vascular and autoimmune diseases and neurological disor-ders and recently their impact on the epigenome has startedto be explored [43]

Inorganic arsenic is a carcinogenic metal Several mil-lions of people around the world are exposed to arsenicconcentrations in their drinking water that exceed theWorldHealth Organizationrsquos recommended limit of 10 ppb Themechanism(s) of arsenic toxicity and carcinogenicity arenot fully clarified recently epigenetic alterations have beenproposed to play a role and have been explored in cohort andcase-control studies especially in Asian populations living inhighly contaminated areas (reviewed in [44]) Exposure gen-erally assessed by the metal concentration in drinking waterandor in biological fluids or tissues has been associatedwith dose-dependent global DNA hypermethylation [45ndash47]and with hypermethylation of specific oncosuppressor genes[48ndash52] Genome-wide comparisons of DNA methylationpatterns frompeople who developed skin lesion and a controlgroup in Bangladesh have evidenced 6CpG sites with greatestchanges of DNA methylation among cases one of whichbelongs to the RHBDF1 gene previously reported to behypermethylated in arsenic-exposed cases [53] Similarly byusing high throughput approaches specificDNAmethylationchanges in particular genes were detected between arsenic-induced and non-arsenic-induced urothelial carcinomas inTaiwan [54]

The epigenetic effects of in utero arsenic exposure wereinvestigated in umbilical cord blood to find out amechanisticbasis for possible arsenic-induced alterations of fetal develop-mental programming Hypermethylation of the transposonicrepeatLINE-1 p16 promoter and other specific sequenceswasassociated with arsenic concentration in maternal drinkingwater [55 56] Other studies also showed some effects ofarsenic maternal exposure on cord blood DNA methylation[57 58] although the involved sequences were not alwaysconsistent

The newborn blood DNA methylation pattern seems tobe affected also by in utero exposure to low concentrationsas shown by the results of a prospective American birthcohort study using high throughput arrays [59] In anotherlarge Mexican cohort a total of 2705 genes in cord bloodleukocytes showed differences in DNAmethylation that wereassociated with maternal exposure to arsenic in drinkingwater The gene set was highly enriched in binding sites ofthe early growth response and CTCF transcription factorsFurthermore DNAmethylation levels of seven of these geneswere associated with differences in birth outcomes includinggestational age placental weight and head circumference

[60] These results strongly point to the need for long-termfollow-ups to determinewhether the observedDNAmethyla-tion changesmay be associatedwith specific health outcomes

Chromium VI [61] mercury [62 63] lead [64 65]cadmium [62 66] and selenium [67] are other metals forwhich association studies between human exposure andDNA methylation changes mainly in peripheral blood cellshave been conducted Cadmium can cross the placentalbarrier and its potential as a developmental toxicant has beenstudied in an American survey by comparing maternal bloodcadmium levels during pregnancy and genome-wide DNAmethylation in leukocyte DNA collected from cord bloodcells [68] A variety of genes showed methylation changesassociated with maternal cadmium concentrations The setwas enriched in genes involved in transcriptional regulationcontrol and apoptosis ConservedDNAmotifs with sequencesimilarity to specific transcription factor binding sites wereidentified within the CpG islands of the gene set Altogetherthe results pointed to a possible functional impact of cad-mium on fetal DNA methylation

Overall the number of studies on the epigenetic impact ofenvironmental metal exposure is limited The study designsthe number of people enrolled the genomic sequences inves-tigated and the methods used to assess methylation changes(locus-specific global locus-independent epigenome-wide)are quite heterogeneous Widely different exposure levelshave been evaluated in occupational studies and in studieson the general population Therefore any attempt to drawgeneral conclusions is still premature However the expecteddecrease of costs of epigenome-wide analytical methods willlikely allow acquiring a wealth of data in the near futureIn addition to such unsupervised studies more focusedinvestigations on global hypomethylation and downregu-lation of the methylation machinery hypomethylation inregions controlling transposons or oncogene expression orhypermethylation at oncosuppressor genes could offer thebest contribution to unravel epigenetic mechanisms under-lying environmental cancer and to develop novel predictivebiomarkers

22 Air Pollution (Particulate Matter Polycyclic AromaticHydrocarbons Benzene and Volatile Organic Compounds)Exposure to air pollution is a side-product of urbaniza-tion and industrialization representing a dramatic healthproblem associated with childhood asthma wheeze andincreased cardiovascular morbidity and mortality It is gen-erally assessed by measuring the levels of particulate matterwith aerodynamic diameter le25 (PM25) or le10 120583m (PM10)together with the levels of other air pollutants like blackcarbon ozone polycyclic aromatic hydrocarbons (PAHs)sulfur and nitrogen dioxide There have been several studiescarried out across the globe which have considered possibleimpacts of air pollution on DNAmethylation with sometimecontrasting results [69]

In a recent European study on a cohort of young non-smoking subjects the exposure to ambient concentrationsof NO

2 PM10 PM25 and O

3and traffic parameters were

associated with a decreased global DNA methylation level inblood cells [70]


Table1Selected

epidem

iologicalstudies

onthee

ffectso

fenviro

nmentalchemicalexpo

sureso

nhu

man

DNAmethylation

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Metals

Arsenic(A

s)

294adults

India

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[45]

64adults

India

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[46]

320adults

Bang

ladesh

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[47]

96adults

India

PBL

p16p53

Bisulfitemethylspecific

PCR

Hypermethylatio

n[48]

202wom

enA

rgentin

aPB

Lp16MLH

1andLINE-1

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natp16and

MLH

1[51]

163patientsw

itharseniasisand

110controls

China

PBL

p16


PCR

Hypermethylatio

n[49]

16individu

also

fwhich

8were

with

arsenicosis

Mexico

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

npatte

rns

[50]

10individu

alsw

ithskin

lesio

nsand10

controls

Bang

ladesh

PBL

Epigenom

e-wide

Arrays

6differentially

methylated

sites

inclu

ding

RHBD

F1[53]

38patie

ntsw

ithurothelial

carcinom

aTaiwan

Tumor

biop

sies

DAP

KBisulfitePC

Rsequ

encing

Hypermethylatio

n[52]

28patie

ntsw

ithurothelial

carcinom

aTaiwan

Tumor

biop

sies

Epigenom

e-wide

Arrays

Hypermethylatio

nin

CTNNA

2KL

K7N

PY2R

ZN

F132and

KCNK17

[54]

113mother-child

pairs

Ba

ngladesh

PBL(m

aternaland

umbilicalcord

samples)

p16p53LINE-1andAlu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natp16and

LINE-1

[55]

113mother-child

pairs

Ba

ngladesh

PBL(m

aternaland

umbilicalcord

samples)

Global

LINE-1Alu

Methylincorpo

ratio

nassay

bisulfitePC

Rpyrosequ

encing

LU

MA(Lum

inom

etric

Methylatio

nAs

say)

Hypermethylatio

n(sex-dependent)

[57]

71newbo

rnsTh

ailand

PBL(cordbloo

d)Global

LINE-1

p53

Globaltotal5-m

Cby

HPL

C-MS

LINE-1CO

BRA

p53methylation-specific

restric

tionendo

nucle

ase

digestion

Hypermethylatio

natp53

[58]

44newbo

rnsBa

ngladesh

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin

thou

sand

sofsites

[56]

134infantsUSA

PBL

Epigenom

e-wide

Arrays

Hypermethylatio

natseveral

loci

[59]

newbo

rnsMexico

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin

thou

sand

sofsites

[60]

Chromium

(Cr)

115workers

and60

controls

China

PBL

Global

ELISA

Hypom

ethylatio

n[61]

Mercury

(Hg)

131d

entalprofessionals

USA

Buccalmucosa

LINE-1DNMT1SEP

W1

andSE

PP1

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natSE

PP1in

males

[63]

Lead

(Pb)

517eld

erlymenU

SAPB

LLINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[64]

9expo

sedindividu

als

PBL

p16

Methylatio

n-specificP

CRand

thermaldenaturatio

nHypermethylatio

n[65]

Cadm

ium

(Cd)

202wom

enA

rgentin

aPB

LLINE-1p16andMLH

1BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[66]

17mother-child

pairs

USA

PBL(m

aternaland

newbo

rn)

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat

subsetso

fgenes

[68]

Selenium

(Se)

286adults

Bang

ladesh

PBL

Global

Methylacceptancea

ssay

Hypom

ethylatio

n[67]

HgPb

and

Cd

43wom

enun

dergoing

IVFUSA

PBL

Epigenom

e-wide

Arrays

Hghyperm

ethylatio

nat

GSTM

1Pb

hypom

ethylatio

natCO

L1A2

[62]


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Airpo

llutio

n(in

cluding

PMandPA

H)

48adultn

onsm

okersBe

lgium

PBL

Global

HPL

CHypom

ethylatio

n[70]

718eld

erlyindividu

alsUSA

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[71]

706eld

erlyindividu

alsUSA

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylation

[72]

777elderly

individu

alsUSA

PBL

F3IFN

-120574IL-6TL

R-2and

ICAM

-1BisulfitePC

Rpyrosequ

encing

F3ICA

M-1

andTL

R-2

hypo

methylatio

nIFN-120574

and

IL-6

hyperm

ethylatio

n[73]

776eld

erlyindividu

alsUSA

PBL

F3ICA

M-1

IFN-120574IL-6

TLR-2CR

ATG

CRiNOS

andOGG

1BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

nat

TLR2

GCR

TLR

2F3and

IL6

[74]

63ste

elworkersItaly

PBL

LINE-1AluiNOS

p16 p53hT

ERT

andAP

CRA

SSF1A

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natiNOS

p53andRA

SSF1A

hyperm

ethylatio

natAP

Cp16

[81ndash83]

49no

nsmok

ingcoke-oven

workersand43

controls

Poland

PBL

p16p53IL-6H

IC1

LINE-1andAlu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natLINE-1

AluandIL-6

hypo

methylatio

natp53

[84]

60truckdriversa

nd60

controls

China

PBL

Tand

emrepeatsS

at120572

NBL

2andD4Z

4BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natSat120572

and

NBL

2[85]

120malew

orkersItalyand

China

PBL

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[87]

67indu

stria

lworkers65

resid

ents

and45

ruralcon

trols

Thailand

PBL

LINE-1Alup16p53HIC1

andIL-6

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natp53IL-6

andLINE-1

[88]

78gasolin

efilling

attend

ants77

urbantraffi

cofficers57control

office

workersItaly

PBL

LINE-1Alu

p15andMAG

E1BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natLINE-1

AluandMAG

E1

hyperm

ethylatio

natp15

[89]

78gasolin

efilling

attend

ants58

controloffice

workerIta

lyPB

LGlobal

High-resolutio

nGC-

MS

Hypom

ethylatio

n[90]

158petro

chem

icalworkersand

50controloffice

workers

Bulgaria

PBL

LINE-1Alup15and

MAG

E1BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natLINE-1

andp15

[91]

141a

sthm

aticchild

renand70

controls

USA

Treg

cells

from

PBL

Foxp3

Hypermethylatio

n[75]

940child

ren

USA

Buccalcells

NOS1N

OS2A

andNOS3

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

nat

NOS2AandNOS3

[ 76]

56mother-child

pairs

USA

PBL(cordbloo

d)AC

SL3

Methylatio

n-specificP

CRHypermethylatio

n[79]

164mother-child

pairs

USA

PBL(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[78]

53mother-child

pairs

USA

PBL(cordbloo

d)IFN120574andIL-4

BisulfitePC

Rsequ

encing

Hypermethylatio

natIFN120574

[80]

POPs

70Inuits

Greenland

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[92]

86adultsSou

thKo

rea

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[93]

358mother-child

pairs

USA

PBL(cordbloo

dandat9

years)

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[98]

Bispheno

lA43

wom

enun

dergoing

IVFUSA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natthe

TSP5

0[62]

46preado

lescentg

irlsEg

ypt

Saliva

Epigenom

e-wide

Arrays

Hypom

ethylatio

natseveral

loci

[94]


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

PFASs

685adults

USA

PBL

LINE-1

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[95]

262fertile

men

Greenland

PolandUkraine

Sperm

GlobalLINE-1Aluand

119878119886119905120572

Flow

cytometry

immun

odetectio

nof

5-mC

bisulfitePC

Rpyrosequ

encing

Noconsistentchanges

[96]

30mother-child

pairsU

SAPB

L(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[97]

EDs

192mother-child

pairs

Spain

Placenta

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

AluY

b8hypo

methylatio

nin

boys

[99]

Tobaccosm

oke

177adults

Germany

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3[103]

374adults

Italy

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3AH

RRand

otherloci

[105]

261a

dultsItaly

PBL

AHRR

6p21

(1locus)

2q37

(2loci)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[111]

3588adults

Germany

PBL

F2RL

3MALD

I-TOFMS

Hypom

ethylatio

n[106]

399African

American

youths

USA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[109]

107African

American

youn

gmenU

SAPB

LEp

igenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[110]

111a

dultAfrican

American

wom

enU

SAPB

LEp

igenom

e-wide

Arrays

Differentia

lmethylatio

nat910

locihypom

ethylationat

AHRR

andGP

R15

[112]

348mother-child

pairs

USA

Child

buccalcells

LINE-1AluY

b8BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAluY

b8[113]

272mother-child

pairs

USA

Child

buccalcells

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin

8genesHypermethylatio

nat

AXLandPT

PRO

[113]

173mother-child

pairs

USA

Child

buccalcells

AXL

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[114]

527mother-asthmaticchild

pairs

USA

Child

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat19

loci

[115]

36mother-child

pairs

(18

nonsmokersa

nd18

smokers)

USA

Placenta

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat

severalloci

[117]

1062

mother-child

pairs

Norway

PBL(cordbloo

d)Ep

igenom

e-wide

Arrays

Differentia

lmethylatio

nin

10genesincluding

AHRR

CY

P1A1

and

GFI1

[118]

418mother-child

pairs

USA

PBL(cordbloo

d)DMRs

ofIG

F2andH19

BisulfitePC

Rpyrosequ

encing

IGF2

DMRdifferential

methylatio

n[119]

380mother-child

pairs

USA

PBL(cordbloo

d)LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natAluY

b8[120]

206mother-child

pairs

USA

Placenta

Epigenom

e-wide

Arrays

Hypermethylatio

natRU

NX3

[121]

132mother-child

pairs

Canada

PBL(ado

lescents)

Epigenom

e-wide

Arrays

Hypermethylatio

natMYO

1G

hypo

methylatio

nat

CNTN

AP2

[122]


Numerous studies focused on the vulnerable subpopula-tion of elderly people [71ndash74] Hypomethylation of repeatedsequences (LINE-1 and in some cases alsoAlu) was reportedto be associated with increased pollutant concentrationsIn addition methylation changes of specific genes involvedin inflammatory and immune response pathways wereobserved whichwere regarded asmodifiers of the associationbetween air pollutants and reduced lung function [74]

Other studies investigated effects of air pollution onDNAmethylation in children showing changes in genes involvedin asthma morbidity [75] or nitric oxide metabolism inairways [76 77]

Lower global DNA methylation [78] and hypermethyla-tion of specific genes [79 80] in umbilical cord white bloodcells were shown to be associated with maternal exposure toairborne PAHs pointing to a possible prenatal environmentalepigenetic origin of childhood diseases

Workers of different job sectors exposed to particulatematter PAHs and benzene have been also monitored forpossible DNA methylation changes in peripheral blood cells[81ndash91] In general DNA repetitive elements such as LINE-1 Alu and HERV have been analyzed in addition tospecific genes including p53 p15 p16 APC RASSF1A HIC1iNOS hTERT and IL-6 Each specific gene and subfamily ofrepetitive sequences seem to respond independently to theexposure and no set of sequences has yet emerged as an idealreporting system of epigenetic effects In addition exposureconditions and methods of assessment were quite heteroge-neous making any overall conclusion impossibleThese stud-ies support the notion that epigenetic biomonitoring is still anew area of environmental health studies that necessitates ofinternational coordination methodological harmonizationand mechanistically sound interpretation of results

23 Persistent Organic Pollutants (POPs) and EndocrineDisruptors (EDs) This heterogeneous class of chemicals isstrongly suspected to interfere with the human hormonalhomeostasis and to hamper reproductive integrity especiallywhen exposure occurs during the pre- and perinatallife stages In a cohort of Greenland Inuits in DNAextracted from blood samples Alu sequences showedsignificant hypomethylation as a function of increasingblood concentration of pp1015840-DDT [111-trichloro-22-bis(p-chlorophenyl)ethane] its main metabolites pp1015840-DDE[11-dichloro-22-bis(p-chlorophenyl)ethylene] 120573-HCH(hexachlorocyclohexane) oxy- and 120572-chlordane mirex sumof PCBs (polychlorinated biphenyls) and sum of POPsthe methylation level of LINE-1 sequences showed a similarinverse trend with the exposure albeit not statisticallysignificant [92] In agreement with these data the bloodconcentrations of various organochlorine pesticides in acohort of healthy Koreans were inversely associated with themethylation level of Alu but not of LINE-1 sequences [93]

Another widely debated chemical is the ubiquitousbisphenol A (BPA) a monomer used in epoxy resinsand polycarbonate plastics Exposure to BPA and possi-ble methylation alterations were studied with genome-wideapproaches Significant hypomethylation of the TSP50 gene

promoter in blood cells was associated with BPA exposurein a cohort of women undergoing in vitro fertilization(IVF) [62] In a survey of prepubescent Egyptian girls [94]higher urinary BPA concentrations were associated withlower genomic methylation and interestingly many affectedgenes were among those whose expression changes had beenpreviously associated with BPA exposure

Another class of emerging POPs is represented by per-fluoroalkyl substances (PFASs) which include a variety ofcompounds widely used in many industrial processes andproducts Cross-sectional associations between serum PFASsand LINE-1DNAmethylationwere evaluated in anAmericanpopulation highly exposed via contaminated drinking water[95] A significant association was found for some but notall specific PFASs To explore the possible effects on malereproduction global methylation and LINE-1 Alu and Sat120572methylation levels were directly assessed in sperm DNAfrom fertile men from Greenland Poland and Ukrainecharacterized by a wide contrast to PFASs plasma levels Nostrong consistent associations between PFASs exposure andany of the sperm methylation biomarkers could be detected[96]

Three studies explored the influence of maternal POPsserum concentrations onDNAmethylation of umbilical cordblood cells Global DNA hypomethylation appeared to beassociated with the serum level of specific PFASs [97] Inter-estingly two studies examining the effects on various familiesof repeated DNA sequences [98 99] showed that the asso-ciation between serum xenoestrogen contamination and Aluhypomethylation in cord blood was influenced by the babygender in agreement with the hypothesis of a differentialgender-dependent susceptibility to prenatal EDs exposure

24 Antibiotics Low birth weight (LBW) has been associatedwith common adult-onset chronic diseases Its etiology ismultifactorial and exposure to antibiotics has been reportedto increase LBW risk Among possible mechanisms underly-ing this association epigenetic changes have been proposed

In the US Newborn Epigenetics Study (NEST) themethylation status of the DMRs of a variety of growth reg-ulatory imprinted genes (IGF2 H19 MEST PEG3 PLAGL1SGCEPEG10 NNAT andMEG3) was analyzed in umbilicalcord blood cells in relation to the infant birth weight andmaternal (self-reported) antibiotic use Methylation at IGF2H19 PLAGL1MEG3 and PEG3was associatedwithmaternalantibiotic use although only methylation at the PLAGL1DMR was also associated with birth weight [100]

25 Tobacco Smoke The potential epigenetic links betweencurrent and prenatal smoking and smoking-related diseasesare extensively discussed in recent review papers [101 102]Smokers and nonsmokers have been compared by highthroughput methods in several cohorts of adult and youngpeople with some consistent alterations detected involvingDNA methylation differences at specific positions in theF2RL3 [103ndash107] in the AHRR [108ndash112] and in GPR15genes [112] which emerged as strong candidates to pre-dict smoking-related negative health outcomes Epigenetic


changes in the offspring of mothers smoking during preg-nancy have been characterized by genome wide approachesto contribute unraveling the mechanistic pathways of somewell-known prenatal smoking-related adverse effects Accu-mulating data indicate that prenatal exposure to tobaccosmoke is associated with reproducible epigenetic changes at aglobal and gene-specific level that persist well in childhoodand adolescence [97 113ndash122] Changes have been foundamong others in genes involved in transcription in oxidativestress and detoxification pathways and in repetitive elementseven though the biological significance of a variety of alteredloci remains to be understood

26 Parental Influence

261 Paternal Effects In humans there is sparse evidencelinking lifestyle paternal factors with the offspring epigenome[123] Paternal obesity has been associated with hypomethy-lation at the IGF2 [124] and MEST PEG3 and NNAT [125]DMRs in the offspring cord blood cells independently ofmaternal obesity and other potential confounders

It is noteworthy that global sperm DNA methylationhas been shown to increase on average by 176 per year[126] and an in-depth analysis of the methylome in twosperm samples collected 9ndash19 years apart from 17 fertileAmerican men has shown several age-related changes [127]One hundred and thirty-nine regions were significantly andconsistently hypomethylated and 8 regions were significantlyhypermethylated with age 117 genes were associated withthese regions of methylation alterations (promoter or genebody) with a portion of them surprisingly located at genespreviously associated with schizophrenia and bipolar disor-der In the same samples LINE-1 showed global hyperme-thylation with age while another study aimed at relatingnumerous variables with sperm DNA methylation [128]did not show age-dependent changes in LINE-1 Alu andSat120572 methylation level probably because of the narrow agecontrast of studied populations In the latter study personalcharacteristics and habits body mass index (BMI) semenquality parameters sperm chromatin integrity biomarkers ofaccessory gland function and the plasma concentration ofreproductive hormones were related to sperm DNA methy-lation in a cohort of 224 men of proven fertility living inthree European regions Greenland Warsaw and KharkivThe geographical location emerged as the main determinantof the methylation level in repetitive sequences and no otherconsistent associations betweenmethylationmarkers and theassessed variables were identified across countries [128]

Until now only three human biomonitoring studiesaddressed the impact of environmental factors on spermDNA methylation One is the already cited investigation onthe possible effects of PFASs exposure on LINE-1 Alu andSat120572 methylation level [96] which did not show consistentPFASs-associated alterations The other two studiesfocused on occupational radiation exposure and alcoholconsumption An increase of hypermethylated spermatozoawas shown in radiation-exposed workers [129] Some yearsago alcohol had been shown to reduce the methyltransferasemRNA levels in sperm of chronically treated rats with

potential consequences on paternal imprinting [130]Notably a trend of increased demethylation with alcoholconsumption was shown in sperm of male volunteers at theH19 and IG DMRs with a significant difference observed atthe IG-DMR between the nondrinkers and heavy alcoholconsumers [131]

262 Maternal Effects Newborn methylomes contain mole-cular memory of the individual in utero experience [132]In the above chapters we have discussed various exampleslinking maternal environmental exposure to newborn DNAmethylation as assessed through cord blood cell analysisHowever the maternal impact appears to extend beyond thatof specific chemical contaminants as also metabolism nutri-tion and stress seem to influence the offspring methylome

In an American black mother-child cohort studygenome-wide analysis of cord blood cells showed that about20 CpG sites in cancer and cardiovascular disease relevantgenes were highly significantly associated with maternal BMI[133]

The epigenetic consequences of prenatal famine andcaloric restriction have been evaluated in a cohort of peopleconceived in the winter 1944-45 during a severe famine at theend of World War II (Dutch Hunger Winter Families Study)These people appear to bear the consequences of prenatalstress later in life including an adverse metabolic profile(suboptimal glucose handling higher BMI and elevatedtotal and low-density lipoprotein cholesterol) and increasedrisk of schizophrenia While the overall global methylationlevels in their blood cells appear to be unaffected [134]significant DNA methylation changes have been shown atseveral specific loci corresponding to imprinted genes or togenes implicated in growth andmetabolic diseases includingIGF2 IL-10 LEP ABCA1 GNASAS and MEG3 [135ndash139]A genome-scale analysis has demonstrated that differentialDNA methylation preferentially occurs at regulatory regionsandmaps to genes enriched for differential expression duringearly development [140] Changes have been also shownto depend on the sex of the exposed individual and thegestational timing of the exposure [137]

Folate plays an essential role in one-carbon metabolisminvolving remethylation of homocysteine to methioninewhich is a precursor of S-adenosylmethionine the primarymethyl group donor formost biologicalmethylations includ-ingDNAmethylation A few pilot studies considered possibleeffects of maternal intake of methyl-donor compounds ontheir infant DNA methylation Compared to infants bornto women reporting no folic acid intake before or duringpregnancy methylation levels at the H19 DMR in umbilicalcord blood leukocytes decreased with increasing folic acidintake the decrease most pronounced in the male offspring[141] In another study [142] increased methylation at thematernally IGF2 imprinted gene and decreased methylationat the maternally imprinted gene PEG3 and at the repetitivetransposonic sequence LINE-1were associated with folic acidsupplementation after the 12th week of gestation but notduring the first trimester or before conception Finally a thirdstudy [143] did not detect any major association betweenintake of methyl donor nutrients (vitamin B12 betaine


choline folate Cd Zn and Fe) during pregnancy and LINE-1DNAmethylation

The results of a human epidemiological study conductedin rural populations in Gambia experiencing pronouncedseasonal fluctuations in nutritional status and diet supporta role for periconceptional maternal plasma concentrationof key micronutrients involved in one-carbon metabolismon infant DNA methylation [144 145] The study focusedon the analysis of human candidate metastable epiallelic loci[25 146] Metastable epialleles are genomic regions whereepigenetic patterning occurs before gastrulation in a stochas-tic fashion leading to systematic interindividual variationwithin one species Their existence is well documented inthe mouse since the pioneering studies on the agouti viableyellow (119860V119910) locus and in this model maternal diet has beenshown tomodulate the establishment of the epigenetic marks(reviewed in [38]) The human survey has shown that DNAmethylation at metastable epialleles in lymphocytes and hairfollicle cells of infants conceived during the rainy (ldquohungryrdquo)season is significantly different from that of infants conceivedin the dry (ldquoharvestrdquo) season providing first evidences of alasting and systemic effect of periconceptional environmenton human epigenotype

Maternal depression has been associated with a higherrisk of LBW and hypermethylation at the MEG3 DMR ofinfants [147] Furthermore LBW infants had lower methy-lation at the IGF2 DMR while high birth weight infantshad higher methylation at the PLAGL1 DMR comparedwith normal birth weight infants Thus imprinted geneplasticity may play a role in the observed association betweendepressive mood in pregnancy and LBW

Preliminary human studies are providing first evidencesupporting the conclusion that traumatic experiences canresult in lasting broad and functionally organized DNAmethylation signature in several tissues in offspring ACanadian study (Project Ice Storm) was set up some monthsafter the 1998 Quebec ice storm by recruiting women whohad been pregnant during the disaster scoring their degreesof objective hardship and subjective distress Thirteen yearslater genome-wide DNA methylation profiling in T cellsobtained from 36 of the children was assessed Prenatalmaternal objective hardship (but not maternal subjectivedistress) was correlated with DNA methylation levels in1675 CpGs affiliated with 957 genes predominantly related toimmune function [148]

3 Rodent Experimental Studies onthe Induction of Epigenetic Changesin the Germline

In the last few years experiments in rodents started to testthe hypothesis that exogenous exposure to some measur-able factor during a controlled time window could induceepigenetic changes in the germline The large majority ofthese experiments investigated changes of DNA methylationat a global gene-specific or genome-wide level and will bediscussed in this section A few considered also other typesof epigenetic changes such as the sperm microRNA content

[149ndash151] but due to their still very small number they willnot be further addressed

These studies were prompted by the observations of heri-table traits unexplained by Mendelian inheritance Howeveronly a subset of studies showing epigenetic transgenera-tional effects also provided evidence of potentially heritableepigenetic changes in the exposed gametes In this reviewonly those studies that analysed possible DNA methylationchanges in the male or female germline of exposed animalshave been considered

Overall 24 papers were reviewed 19 reporting studiesin mice and 5 in rats Studies on the possible induction ofepigenetic alterations in germ cells were grouped accordingto the exposure time window either prenatally during thecritical period of germline differentiation (10 studies) orpostnatally in prepuberal or adult male (12 studies) or female(5 studies) animals One of the 5 studies on exposure of thefemale germline was carried out in vitro (Table 2)

From the emerging overview the research objectivesstill appear rather sparse a group of studies evaluated theimpact ofmetabolic changes due to undernourishment [152]low-protein [153] folate-deficient [154] zinc-deficient [155]obesogenic andor diabetogenic diets [149 156ndash158] Otherstudies investigated the effects of specific compounds manyof which belong to the class of so-called endocrine disruptersincluding vinclozolin [159ndash161] methoxychlor [162] dioxin[163] and bisphenol A [164ndash166] The remaining studiesdeal with a heterogeneous group of potentially epigeneticsdisrupting agents particulate air pollution [167] ethanol[168 169] tamoxifen [170 171] fenvalerate [172] and sodiumfluoride [173]

Regarding the genomic targets several studies focusedon a few loci either maternally (Mest Snrpn Igf2r andPeg3) or paternally (H19 Meg3 and Rasgrf1) imprinted(methylated) Other studies evaluated changes of methyla-tion in metabolism-related genes such as the LPLase thePpar120572 or the Lep gene One paper included the analysis ofmethylation of Line-1 repeated sequences [173] A few studiesassessed possible changes of total DNAmethylation whereasthe most recent papers report analyses at a genome-widelevel With a few exceptions [153 160 163 170 173] thestudies showed some kind of exposure-related effect Bothincrease and decrease of methylation levels were reportedAs pointed out before the studies are too scattered and tooheterogeneous in the analytical methods to allow drawinggeneral conclusions however some hints are emerging likeincreasedmethylation ofmaternally imprinted and decreasedmethylation of paternally imprinted genes in the exposedmale germline Interestingly the few studies on oocyteexposure show an opposite effect of treatment on the samematernally imprinted genes which seem to respond with adecreased methylation level

In some studies the impact of exposure on germ cells hasbeen compared with the impact on somatic cells Dependingon the type and time of exposure some studies showed thatthe methylation control mechanisms were more robust inthe somatic than in the germ cells as in the case of prenataltreatment with ethanol [168] or methoxychlor [162] buta reversed sensitivity was also observed as in the case of


Table2Syno

psisofpapersrepo

rtinge

ffectso

fexp

erim

entaltreatmentson

DNAmethylationofrodent

maleo

rfem

aleg

erm

cells

(whenadditio

naltissuesw

erea

nalyzedthey

arespecified)

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Flutam

ide

Rats

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

sperm

ofadult

anim

als

LPLa

seBisulfitePC

Rsequ

encing

NodetectableDNAmethylatio

nchanges

[160]

Procym

idon

eRa

tsIn

uteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

Multip

leun

specified

Methylatio

n-specific

restr

ictio

nEn

donu

clease

digestion

Alteredmethylatio

ndetected

atmultip

lesequ

encesinvolving

both

hypo

-and

hyperm

ethylatio

nevents

[159]

Vinclozolin

Mice

Inuteroexpo

sure

ipinjectio

nof

50mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Inspermhighlysig

nificantH

19andMeg3

hypo

methylatio

nandMestSnrpnandPeg3

hyperm

ethylation

lessevidenteffectsinsomatic

tissues

[161]

Dioxin

Mice

Inuteroexpo

sure

ipinjectio

nof

2or

10ng

kgday

betweenday9andday19

ofgesta

tion

Spermplusliver

andskele

tal

muscle

cells

inadultanimals

SnrpnPeg3and

Igf2r

BisulfitePC

Rpyrosequ

encing


nchangesin

sperminliver

andmuscle

cells

significant

increaseso

fmethylationin

Igf2r

[163]

Metho

xychlor

Mice

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign

ificantlydecreasedmethylatio

nof

H19

and

Meg3andsig

nificantly

increasedmethylatio

nof

MestSnrpnandPeg3

inspermn

oeffectin

somatictissues

[162]

Ethano

lMice

Inuteroexpo

sure

poadministratio

nof

05g

kgday

betweenday10

andday18

ofgesta

tion

Spermplustail

liverskeletal

muscle

and

brain

cells

inadult

anim

als

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Highlysig

nificant3decrease

inthen

umbero

fmethylatedCp

Gso

fH19noeffectintheo

ther

genesa

ndin

somatictissues

[168]

Folate-deficient

diet

Mice

Inuteroexpo

sure

treatmento

fdam

swith

folate-deficient

dietfro

mtwoweeks

before

mating

throug

hout

gesta

tionandlactation

Sperm

Epigenom

e-wide

Arrays

57geno

micregion

shad

alteredmethylatio

nprofi

lesinsperm

from

males

expo

sedto

folate-deficient

dietbothhypo

-and

hyperm

ethylatio

nwereo

bservedmethylatio

ndifferences

observed

inprom

oter

region

sofgenes

implicated

indevelopm

entand

with

functio

nsin

thec

entralnervou

ssystemkidneyspleen

digestive

tractandmuscle

tissueandof

genes

associated

with

diabetesautoimmun

edise

ases

neurologicaldiseasesautism

schizop

hreniaand

cancer

[154]

Und

erno

urish

ment

Mice

Inuteroexpo

surenutritionalrestrictio

nbetweenday125andday185of

gesta

tion

Sperm

Global

epigenom

e-wide

Massspectrometryarrays

166differentially

methylatedregion

sof

which

111

wereh

ypom

ethylatedand55

hyperm

ethylatedin

undernou

rishedrelativ

etocontrolm

icethe

bisulfitepyrosequ

encing

valid

ationconfi

rmed

1724hypo

methylated

and08hyperm

ethylated

region

s

[152]

Metho

xychlor

Mice

Adultexp

osure

ipinjectio

nof

10mgkgday

for8

consecutived

ays

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

Meg3and

significantly

increasedmethylationofMestSnrpn

andPeg3

inspermn

oeffectinsomatictissues

[162]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Ethano

lMice

Adultexp

osure

poadministratio

nof

59g

kgdayfor2

9days

over

aperiodof

5weeks

Sperm

H19R

asgrf1

BisulfitePC

Rpyrosequ

encing


nchanges

[169]

Fenvalerate

Mice

Adultexp

osure

poadministratio

nof

10mgkgday

for

30days

Sperm

Epigenom

e-wide

Arrays

Sign

ificant

Hap1h

ypom

ethylatio

nsig

nificantA

ce

Foxo3aN

r3c2P

mlandPtgfrn

hyperm

ethylatio

n[172]

Sodium

fluoride

Mice

Adultexp

osure

poadministratio

nof

100m

gLin

drinking

water

for3

5days

Spermplusliver

cells

inadult

anim

als

H19R

asgrf1

Peg3

andLine-1

glob

alBisulfitePC

Rsequ

encing

EL

ISA


nchanges

[173]

Tamoxifen

Rats

Adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Igf2-H

19global

BisulfitePC

Rsequ

encing

flo

wcytometry

after

immun

ostainingwith

5-methylcytosine

antib

ody

Sign

ificantlyredu

cedmethylationatIgf2-H

19

glob

almethylatio

nlevelu

naffected

[171]

Tamoxifen

Rats

adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Dlk1Plagl1

Peg5

Peg3Igf2rG

rb10

Kcnq

1Ascl2

and

Cdkn1c

BisulfitePC

Rsequ

encing


nchanges

[170]

Bispheno

lARa

tsNeonatalexp

osure

5daily

subcutaneous

injections

of04m

gkgday

BPAsta

rtingon

eday

after

birth

Sperm

Igf2-H

19BisulfitePC

Rsequ

encing

Sign

ificant

hypo

methylationattheH

19ICR

[166]

Particulatea

irpo

llutio

nMice

Adultexp

osure

3or

10weeks

ofexpo

sure

toam

bientair

inpo

llutedsites

Sperm

samplingeither

immediatelyor

6weeks

after

thee

ndof

10-w

eekexpo

sure

Sperm

Global

Cytosin

eextensio

nassay

andmethylacceptance

assay

Sign

ificantlyincreasedglob

almethylationin

10-w

eekexpo

sedsamplesw

hich

persisted

after

expo

sure

interrup

tion

methylationchanges

abolish

edby

useo

fairfilters

[167]

High-fatd

iet

Mice

Adultexp

osure

10-w

eekexpo

sure

tohigh

-fatd

ietfrom

5weeks

ofage

Testisc

ells

elong

ated

spermatids

Global

ELISAsem

iquantitativ

eim

mun

ohistochemistry

oftestissectio

nswith

anti-5-mCantib

ody

Abou

t25

redu

ctionin

glob

almethylationin

both

who

letesticularc

ellsandspermatids

[149]

High-fatd

ietp

lus

streptozotocin

subd

iabetogenic

treatment

Mice

Adultexp

osure

13-w

eekexpo

sure

tohigh

-fatd

ietfro

m3weeks

ofageplus

streptozotocinip

injectionat12

weeks

ofage

Sperm

Epigenom

e-wide

Arrays

Paternalprediabetesa

lteredoverallm

ethylome

patte

rnsinspermw

ithalarge

portionof

differentially

methylated

geneso

verla

ppingwith

thatof

pancreaticisletsinoff

sprin

g[156]

Low-protein

diet

Mice

Adultexp

osure

9-weekexpo

sure

tolow-protein

diet

from

3weeks

ofage

Sperm

119875119901119886119903120572

epigenom

e-wide

BisulfitePC

Rsequ

encing

arrays

Noeffectsof

dieton119875119901119886119903120572methylatio

nin

sperm

overallsperm

cytosin

emethylationpatte

rnsw

ere

largely

conservedun

derv

arious

dietaryregimes

[153]

Olfactoryfear

cond

ition

ing

Mice

Adultexp

osuretoacetop

heno

neSperm

Olfr151

BisulfitePC

Rsequ

encing

Hypom

ethylation

[175]

Streptozotocin

diabetogenic

treatment

Mice

Adultexp

osure

singleipinjectio

nof

230m

gkg

streptozotocin

1525or

35days

before

oocytecollectionaft

ersuperovulation

Oocytes

H19Peg3and

Snrpn

COBR

A

Evidentd

emethylationwas

observed

inthe

methylatio

npatte

rnof

Peg3

DMRon

day35

after

treatmentthem

ethylatio

npatte

rnso

fH19

and

SnrpnDMRs

weren

otsig

nificantly

alteredby

maternald

iabetes

[157]

High-fatd

iet

Mice

Adultexp

osure

12weeks

offeedingwith

high

-fatd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

H19M

estPeg3

Igf2rSnrpnPp

ar120572

andLep

COBR

A

DNAmethylationof

imprintedgenesw

asno

talteredtheP

par120572

methylatio

nlevelw

assig

nificantly

decreasedandtheL

epmethylatio

nlevelw

assig

nificantly

increasedin

high

-fatd

iet

fedmicec

omparedwith

controlm

ice

[158]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Zinc-deficientd

iet

Mice

Adultexp

osure

5days

offeedingwith

zinc-deficientd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

Global

Immun

ocytochemistry

with

anti-5-mCantib

ody

DNAmethylatio

nwas

redu

cedto

abou

t60

ofcontrollevelsinzinc-deficiento

ocytes

[155]

Bispheno

lAMice

Neonatalexp

osure

20or

40120583gkg

bw

either

bydaily

hypo

derm

alinjections

from

postn

atal

day7to

postn

atalday14

orby

intraperito

nealinjections

administered

each

fifthdaybetweenpo

stnataldays

5and20prio

rtocollectionof

ovarian

oocytes

Oocytes

H19Igf2rand

Peg3

BisulfitePC

Rsequ

encing

Sign

ificant

dose-dependent

redu

ctionof

methylatio

nin

Igf2rPeg3

genesno

effecto

nH19

[164

]

Bispheno

lAMice

Invitro

expo

sure

to3or

300n

Mdu

ring

12days

offollicle

cultu

refro

mpreantral

toantralsta

geOocytes

H19M

estIgf2r

andSnrpn

BisulfitePC

Rpyrosequ

encing

Sign


natthelow

but

notatthe

high

BPA

doseinMestIgf2rand

Snrpngenesno

effecto

nH19

[165]


prenatal exposure to dioxin [163] It is conceivable that eachtissue might respond accordingly to its specific developmen-tal program therefore studies of exposure during the periodof prenatal germline differentiation are especially importantfor assessing any environmental epigenetic impact on thegermline

The evaluation of an epigenetic impact of exogenousfactors on the germline is still in its infancy A critical issuethat has not yet been thoroughly addressed is if and howmuch theDNAmethylation changes have a functional impacton the gene expression level and have any causal role on themale germ cell toxicity that is sometimes induced as afterprenatal vinclozolin [161] or ethanol [168] exposure

A group of studies aimed mainly to evaluate possibletransgenerational consequences of epigenetic alterations inthe germline The simplest hypothesis was that methylationchanges in gametes could resist zygotic reprogrammingand have functional consequences in the offspring sired byexposed animals

Indeed in mice ethanol exposure in utero was shown toinduce H19 demethylation in sperm of adults as well as inthe brain cells of their offspring with a good concordancebetween the CpG demethylation patterns across cell typesand generations [168] In another study testing possibletransgenerational effects of tamoxifen in rats [171 174] theoffspring sired by tamoxifen-treated animals showed anincreased incidence of embryonic resorptions and resorbedembryos (but not normal ones) carried methylation errorssimilar to those detected in the sperm of exposed fathersIn male mice a prediabetic condition closely resemblingthe metabolic abnormalities of human prediabetes can beinduced by high-fat diet and chemical treatment these micetransmit to their offspring glucose intolerance and insulinresistance [156] Epigenomic profiling in offspring pancreaticislets identified changes in cytosine methylation at severalinsulin signaling genes and these changes correlated with theexpression of these genes The analysis of cytosine methyla-tion profiles in sperm of prediabetic fathers showed severalalterations and a large proportion of differentially methylatedgenes overlapped with that of the offspring pancreatic isletsBisulfite sequencing of some of these genes in blastocystsshowed that they resisted global postfertilization demethyla-tion and largely inherited cytosine methylation from spermsuggesting that theremight be intergenerational transmissionof methylation profiles

However other studies demonstrated that epigeneticinheritance via the gametes can be more complex than thedirect transmission of DNA methylation alterations and acrosstalk might exist between different levels of epigeneticregulation across generations

A genome-wide analysis ofmethylation changes in spermof mice exposed to a folate-deficient diet showed alteredmethylation profiles in genes implicated in developmentchronic diseases such as cancer diabetes autism andschizophrenia [154] In the same study a twofold greaterresorption rate and an increased frequency of developmentalabnormalities were observed in pregnancies sired by exposedmalesMoreover significant changes in the expression of over300 genes were detected in the placenta of exposed-animals

sired offspring However differentially expressed genes inthe placenta did not match differentially methylated genes insperm suggesting that mechanisms other than DNA methy-lation might be involved in the transgenerational transmis-sion of epigeneticmessages like spermhistonemodifications

Similarly in utero undernourishment induced hypome-thylation of several genes in sperm as well as changes ofexpression of metabolic genes in the brain and liver of lategestation fetuses sired by the exposed animals interestinglythe genes whose expression was altered in the fetusesmappedclose to differentially methylated regions in sperm althoughdifferential methylation was not transgenerationally retained[152] The authors concluded that ldquo it is unlikely thatthese expression changes are directly mediated by alteredmethylation rather the cumulative effects of dysregulatedepigenetic patterns earlier in development may yield sus-tained alterations in chromatin architecture transcriptionalregulatory networks cell type or tissue structurerdquo

Postweaning growth delay and decreased methylationat the H19 ICR CTCF binding sites were observed in theoffspring of adult mice treated with ethanol although nodecrease of H19 DNA methylation was detectable in thesperm DNA [169] Methylation was significantly increasedin Peg3 and significantly decreased in H19 8-cell embryossired by male mice treated with sodium fluoride while nochange of methylation was detected in sperm [173] Increasedmethylation of a number of imprinted genes associated withdownregulation of transcription was detected in the resorb-ing embryos sired by tamoxifen-treated male rats in spiteof the fact that their sperm did not show DNA methylationchanges in any of the 9 analyzed imprinted genes [170]

The complexity of the interplay between environmen-tally sensitive epigenetic markers in sperm and epigeneticmodulation of development in the following generation isfurther illustrated by a recently published report on thetransgenerational consequence of paternal exposure to aconditioning olfactory experience [175] The F1 progeny ofconditioned mice reacted just like the fathers with enhancedresponse in spite of never being conditioned themselvesThe F1 neuroanatomywas also affected Behavioral sensitivityand neuroanatomical alterations in the nervous system werepresent also in the IVF-derived F1 generation and persisteduntil at least the F2 generation Hypomethylation in specificCpG islands of theOlfr151 gene encoding for the specific odorreceptor was detected in sperm of exposed mice These find-ings led the authors ldquoto hypothesize that relative hypomethy-lation of Olfr151 in F0 sperm may lead to inheritance ofthe hypomethylated Olfr151 in F1 Main Olfactory Epithelium(MOE) and F1 sperm creating an inheritance cascaderdquoHowever the epigeneticmark was found in the sperm but notin the MOE of F1 mice Noting that DNA methylation andhistone modifications are known to be dependent on eachother the authors suggested that changes in the methylationpattern in sperm DNA might have resulted in histonemodifications around the olfactory gene in MOE DNA

The literature on effects of experimental exposure uponDNA methylation in rodent oocytes is less abundant com-pared with that on effects induced in sperm Two papersreport undermethylation of maternally imprinted genes in


oocytes exposed to bisphenol-A either in vivo [164] or inculture [165] In addition to the challenge posed by workingwith a little number of cells experimental studies on female-mediated epigenetic inheritance also face the difficulty ofstrictly distinguishing a mechanism of epigenetic inheritancevia the gametes from other mechanisms of epigenetic inheri-tance such as those based on adverse uterine environment orlactation-mediated effects This issue emerged for examplein a recent paper [158] showing functional alterations ofmethylation patterns in the Lep and Ppar120572 metabolic genesin oocytes of mice treated for 12 weeks with a high-fat diet aswell as in the liver cells of their offspring

4 Discussion

DNA methylation is a life-essential process that modulatesgene expression and drives cell differentiation inmulticellularorganisms Synergistically with other epigeneticmechanismsit allows cells and organisms to adapt to external changes in atimely way thatmutationalmechanisms could nevermeet AssuchDNAmethylation is unsurprisingly sensitive to externalstimuli At the same time and in contrast to mutationsDNA methylation changes are reversible This duality posesa challenge to researchers who aim to establish possible linksbetween environmental exposure and epigenetic changes thatmay have a long-lasting impact on cell function and ulti-mately on health Cancer in all its forms is the most typicalexample of a disease associated with aberrant epigeneticswhich may be triggered by environmental exposure [2 176]but ample evidence exists where erroneous epigenetic marksalso play prominent roles in neurological disorders such asAlzheimerrsquos disease autoimmune diseases such as rheuma-toid arthritis and cardiovascular diseases among others [2]Thepath of environmental epigenetics will necessarily have tomove from initially sparse association studies towards causalrelationships supported by biological plausibility

The plasticity of the human epigenome and the difficultyto sort out major environmental effects from ldquobackgroundnoiserdquo can be appreciated from the studies showing a sea-sonality and weather influence on some DNA methylationbiomarkers analyzed in recent human biomonitoring studies[177 178] or the findings of genome-wide analyses thatshowed an influence of long-term shiftwork on DNAmethy-lation at several loci [179ndash182]These latter studies promptedby the evidence of an association between exposure to lightat night circadian rhythms and cancer risk demonstratedindeed methylation changes in many cancer-relevant genesand pathways but they need to be confirmed by independentreplication in larger samples and supported by fundamentalmechanistic research before any firm conclusion can bedrawn

In addition the fact that interindividual variation inmethylation may also be a consequence of DNA sequencepolymorphisms that result in methylation quantitative traitloci should not be overlooked Teh and coworkers [183]have investigated the genotypes and DNA methylomes of237 neonates and found some 1500 punctuate regions ofthe methylome highly variable across individuals termedvariably methylated regions (VMRs) against a homogeneous

background The best explanation for 75 of VMRs was theinteraction of genotype with different in utero environmentsincluding maternal smoking maternal depression maternalBMI infant birth weight gestational age and birth orderA prevalence of genetic over environmental determinantsof interindividual variation of CpGs methylation has beenrecently reported in large Scottish and Australian cohorts[184]

Finally age is expected to be amajor variable affecting theDNA methylation profiles in different tissues In fact recentstudies aimed at exploring the importance of epigeneticchanges to the ageing process highlighted age-signatures ofDNA methylation [185ndash187]

One of the problems in drawing an overall patternfrom published literature on environmental epigenetic effectsis due to the heterogeneity of detection methods andapproaches Several different methods have been developedforDNAmethylation analysis and their advantages anddraw-backs are discussed in excellent recent reviews [188ndash191] Wehave witnessed in a short time the passage from the analysisrestricted to single specific regions to a global and genome-wide scale Even if on purely theoretical considerations theideal choice would point at a technique able to measurethe entire methylome at a single-base-pair resolution in aparticular cell system researchers have to face other issuesrelated to time- and cost-effectiveness and make reasonablecompromises with their own scientific questions and thetechnology available By and large cost-affordable technolo-gies are limited in their sensitivity to DNA methylationdetection like those relying on the global immunostainingof the 5-mCs or like pyrosequencing that analyzes only alimited amount of informative cytosines [192 193] On theother hand technologies based on high-resolution methy-lation arrays [194] are able to measure countless sequencesacross the genome but are costly and demand sophisticatedbioinformatics The methylation analysis at targeted geneslike those imprinted involved in some metabolic pathwayor supposedly metastable andor in repetitive elements(transposonic or not) is a frequently used approach inenvironmental epigenetics Interestingly it is emerging thatrepetitive elements such as Alu and LINE-1 which wereinitially chosen simply as a proxy of the global methylationlevel due to their abundance throughout the genome respondto environmental stress in a sequence-specific manner andhave to be considered as separate entities [96 98 120195] An international methodological standardization andharmonization effort would contribute to reaching moresolid evidence on the epigenetic impact of environmentalstressors It certainly represents a Herculean task as thehuman haploid DNA methylome contains approximately 30million CpGs that exist in a methylated hydroxymethylatedor unmethylated state

Notwithstanding such difficulties environmental epige-netics may become a potent concept to fully assess the impactof the exposome on human health [196] In particular thenotion that in mammals tissue differentiation is mainlyestablished during prenatal life and fundamental DNAmethylation changes occur in preimplantation embryo andduring gonadal differentiation may support the hypothesis


of prenatal origin of adult-onset diseases To push scienceforward epidemiological mother-child cohort studies andmaternal exposure assessment will be instrumental

Also the bases of reproductive health are founded duringprenatal life with primordial germ cell differentiation andgonad development although the process of gametogenesiswill only be completed after pubertyThismeans thatmultipleexposure windows must be considered to assess possibleenvironmental effects on the gamete genetic and epigeneticintegrity

The results of the studies in rodents that we havedescribed in the previous section show thatDNAmethylationin germ cells can be altered by many different kinds ofexposure during the fetal as well as the adult life Still thesestudies suffer of some limitations more data are available onthe male than on the female germline and only few of themcarried out the analyses at themost informative genome scaleaddressed the functional impact of epigenetic changes on thegene expression level and related cell pathways and took intoconsideration dose-effect relationships Nevertheless theirresults are very important because they establish proof ofprinciple demonstration that a variety of exogenous stressorsmay alter DNA methylation at developmentally importantimprinted or metabolic genes

As a target of environmental exposure the germlinemeets a double risk of compromising the reproductioncapacity of the exposed individual and transmitting possibledamage to the following generation Some of the studies inrats and mice indeed showed that treatment induced notonly DNAmethylation changes in sperm but also phenotypealterations in the sired offspring These observations areconsistent with the notion that DNA methylation profiles ofthe gametes are not completely reset after fertilization butcan be partly transmitted across generations Actually fewexperiments tested this notion in the specific conditionswith some showing apparent inheritance of gamete methy-lation [156 168] while others not showing the same result[152] Nevertheless several authors agree in pointing outthat direct transmission of methylation changes is not theonly mechanism through which altered sperm methylationmight affect the offspring phenotype and that sustainedalterations of transcriptional regulatory networks early indevelopment may likely result from a complex interplaybetween DNA methylation changes chromatin modifica-tions and other epigenetic mechanisms One implication ofepigenetic inheritance systems is that they provide a potentialmechanism by which parents could transfer information totheir offspring about the environment they experienced Inother words mechanisms exist that could allow organismsto ldquoinformrdquo their progeny about prevailing environmentalconditions

In some of the experimental studies [162 163 168 169]changes of DNA methylation in the germline and somaticcells of exposed animals were compared On the basis of thefew available data it is not possible to draw any general con-clusion but much more than for induced genetic changes itis conceivable that each cell type with its own transcriptionalprogram would be specifically affected at an epigenetic levelThis consideration poses a problem when data on induced

epigenetic changes in the germline of experimental rodentswant to be related with human biomonitoring data

In fact as previously shown whereas the database onenvironmental factors impinging on DNA methylation inhuman leukocytes is already abundant very few data existon the variables affecting DNA methylation in human germcells even in the most easily accessible sperm Acknowl-edging the limitation of a comparison between two largebut independent studies carried out in different cohortsthe increase of LINE-1 methylation reported in blood cellsin association with perfluorooctane sulfonate (PFOS) serumlevel [95] and the lack of an association between PFOS serumlevel and LINE-1 methylation in sperm [96] exemplifies thedifficulty of any extrapolation between somatic and germlineenvironmental epigenetics

Much more fruitful has been until now the field of malereproductive clinical epigenetics [35 36] The review of datashowing DNA methylation and other epigenetic changesin the sperm of subfertile patients was out of the scopeof this paper However these data are important also forreproductive environmental epigenetics because they seemto indicate a functional significance of DNA methylationchanges in themale germline At the same time they evidencethe need to conduct specific epigenetic analyses on thesperm of men exposed to reproductive toxicants with theawareness that their PBLs could not surrogate the relevanttarget cells Recently the entire methylome of human spermhas been analyzed at high resolution thanks to the mostadvanced technologies [127 197 198] While this datasetwill be consolidated by repeated analyses and the degreeof interindividual variation will be assessed it will providean essential reference for future studies on the impact ofenvironmental stressors

From an overall assessment of the current database onhuman somatic environmental epigenetics rodent germlineepigenetic toxicological studies and the most environmen-tally relevant human reprotoxic agents a priority list of envi-ronmental stressors on which directing future human spermepigenetic biomonitoring studies might be proposed dys-metabolism as a consequence of environmental and geneticfactors including their possible interactions endocrine dis-rupting compounds andmajor lifestyle toxicants like tobaccosmoke and alcohol In addition emphasis should be onprenatal exposure and mother child cohorts should bestudied more actively Finally prospective long-term multi-generation follow-up surveys should be possibly set up to takeinto account grandparental effects

Abbreviations

ABCA1 ATP-binding cassette subfamily A(ABC1) member 1

ACE Angiotensin I-converting enzymeACSL3 Acyl-CoA synthetase long-chain family

member 3AHRR Aryl hydrocarbon receptor repressorAPC Adenomatous polyposis coliASCL2 Achaete-scute family bHLH

transcription factor 2


AXL AXL receptor tyrosine kinaseBMI Body mass indexCDKN1C Cyclin-dependent kinase inhibitor 1CCNTNAP2 Contactin associated protein-like 2COBRA Combined bisulfite restriction analysisCOL1A2 Collagen type I alpha 2CRAT Carnitine O-acetyltransferaseCTCF CCCTC-binding factor (zinc finger protein)CTNNA2 Catenin (cadherin-associated protein) alpha

2CYP1A1 Cytochrome P450 family 1 subfamily A

polypeptide 1DAPK Death-associated protein kinaseDLK1 Delta-like 1 homologDMR Differentially methylated regionDNMT1 DNA (cytosine-5-)-methyl transferase 1EDs Endocrine disruptorsELISA Enzyme linked immunosorbent assayF2RL3 Coagulation factor II (thrombin)

receptor-like 3F3 Coagulation factor IIIFOXO3A Forkhead box O3FOXP3 Forkhead box transcription factor 3GC-MS Gas chromatography-mass spectroscopyGCR Glucocorticoid receptorGFI1 Growth factor independent 1 transcription

repressorGNASAS GNAS antisense RNAGPR15 G protein-coupled receptor 15GRB10 Growth factor receptor-bound protein 10GSTM1 Glutathione S-transferase mu 1H19 Imprinted maternally expressed transcript

(nonprotein coding)HAP1 Huntingtin-associated protein 1HERV Human endogenous retrovirusHIC1 Hypermethylated in cancer 1HPLC-MS High performance liquid

chromatography-mass spectrometryhTERT Human telomerase reverse transcriptaseICAM-1 Intercellular adhesion molecule 1ICR Imprinting control centerIFN120574 Interferon gammaIGF2 Insulin-like growth factor 2IGF2R Insulin-like growth factor 2 receptorIL-4 Interleukin-4IL-6 Interleukin-6IL-10 Interleukin-10iNOS Inducible nitric oxide synthaseIVF In vitro fertilizationKCNK17 Potassium channel subfamily K member 17KCNQ1 Potassium voltage-gated channel KQT like

subfamily member 1KLK7 Kallikrein-related peptidase 7LBW Low birth weightLEP LeptinLINE-1 Long interspersed nuclear element 1

retrotransposable element 1LPLASE Lysophospholipase5-mC 5-methyl cytosine 5-methyl deoxycytidine

MAGE1 Melanoma antigen family A 1MALDI-TOF MS Matrix-assisted laser desorption

ionization time-of-flight massspectrometry

MEG3 Maternally expressed 3 (nonproteincoding)

MEST Mesoderm specific transcriptMLH1 MutL homolog 1MYO1G Myosin IGNNAT NeuronatinNOS1 Nitric oxide synthase 1NOS2A Nitric oxide synthase 2ANOS3 Nitric oxide synthase 3NPY2R Neuropeptide Y receptor Y2NR3C2 Nuclear receptor subfamily 3 group C

member 2OGG1 8-Oxoguanine DNA glycosylase 1OLFR151 Olfactory receptor 151p15 Cyclin-dependent kinase inhibitor 2Bp16 Cyclin-dependent kinase inhibitor 2Ap53 Tumor protein p53PAHs Polycyclic aromatic hydrocarbonsPBL Peripheral blood lymphocytesPCBs Polychlorinated biphenylsPCR Polymerase chain reactionPEG3 Paternally expressed 3PEG5 Paternally expressed 3 (alias NNAT

neuronatin)PEG10 Paternally expressed 10PFASs Perfluoroalkyl substancesPGC Primordial germ cellPLAGL1 Pleomorphic adenoma gene-like 1PM Particulate matterPOPs Persistent organic pollutantsPPAR120572 Peroxisome proliferator-activated

receptor alphaPTGFRN Prostaglandin F2 receptor negative

regulatorPTPRO Protein tyrosine phosphatase receptor

type ORASGRF1 Ras protein-specific guanine

nucleotide-releasing factor 1RASSF1A Ras association (RalGDSAF-6) domain

family member 1RHBDF1 Rhomboid family member 1RUNX3 Runt-related transcription factor 3SEPP1 Selenoprotein P plasma 1SEPW1 Selenoprotein W 1SGCE Sarcoglycan epsilonSNRPN Small nuclear ribonucleoprotein

polypeptide NTLR-2 Toll-like receptor 2TSP50 Testes-specific protease 50ZNF132 Zinc finger protein 132

Conflict of Interests

The authors declare that there is no conflict of interests


Acknowledgment

The authors wish to apologize to those authors whosecontribution wasmissed by our collections or was not quotedbecause of space limitations

References

[1] C B Santos-Reboucas and M M G Pimentel ldquoImplicationof abnormal epigenetic patterns for human diseasesrdquo EuropeanJournal of Human Genetics vol 15 no 1 pp 10ndash17 2007

[2] A Portela and M Esteller ldquoEpigenetic modifications andhuman diseaserdquo Nature Biotechnology vol 28 no 10 pp 1057ndash1068 2010

[3] H Heyn and M Esteller ldquoDNA methylation profiling in theclinic applications and challengesrdquo Nature Reviews Geneticsvol 13 no 10 pp 679ndash692 2012

[4] S Feng S E Jacobsen and W Reik ldquoEpigenetic reprogram-ming in plant and animal developmentrdquo Science vol 330 no6004 pp 622ndash627 2010

[5] H Denis M N Ndlovu and F Fuks ldquoRegulation of mam-malian DNA methyltransferases a route to new mechanismsrdquoEMBO Reports vol 12 no 7 pp 647ndash656 2011

[6] J A Hackett and M A Surani ldquoDNA methylation dynamicsduring the mammalian life cyclerdquo Philosophical Transactions ofthe Royal Society of London Series B Biological sciences vol 368no 1609 Article ID 20110328 2013

[7] S Seisenberger J R Peat T A Hore F SantosW Dean andWReik ldquoReprogramming DNA methylation in the mammalianlife cycle building and breaking epigenetic barriersrdquo Philo-sophical transactions of the Royal Society of London Series BBiological sciences vol 368 no 1609 Article ID 20110330 2013

[8] Z D Smith and A Meissner ldquoDNA methylation roles inmammalian developmentrdquoNature Reviews Genetics vol 14 no3 pp 204ndash220 2013

[9] M Szyf ldquoThe implications of DNA methylation for toxicologytoward toxicomethylomics the toxicology of DNA methyla-tionrdquo Toxicological Sciences vol 120 no 2 pp 235ndash255 2011

[10] J R McCarrey ldquoThe epigenome as a target for heritableenvironmental disruptions of cellular functionrdquoMolecular andCellular Endocrinology vol 354 no 1-2 pp 9ndash15 2012

[11] V Bollati andA Baccarelli ldquoEnvironmental epigeneticsrdquoHered-ity vol 105 no 1 pp 105ndash112 2010

[12] J A Alegrıa-Torres A Baccarelli and V Bollati ldquoEpigeneticsand lifestylerdquo Epigenomics vol 3 no 3 pp 267ndash277 2011

[13] B C Christensen and C J Marsit ldquoEpigenomics in environ-mental healthrdquo Frontiers in Genetics vol 2 article 84 2011

[14] M B Terry L Delgado-Cruzata N Vin-RavivH CWu andRM Santella ldquoDNAmethylation in white blood cells associationwith risk factors in epidemiologic studiesrdquo Epigenetics vol 6no 7 pp 828ndash837 2011

[15] V K Cortessis D CThomas A J Levine et al ldquoEnvironmentalepigenetics prospects for studying epigenetic mediation ofexposure-response relationshipsrdquo Human Genetics vol 131 no10 pp 1565ndash1589 2012

[16] R Feil and M F Fraga ldquoEpigenetics and the environmentemerging patterns and implicationsrdquo Nature Reviews Geneticsvol 13 no 2 pp 97ndash109 2012

[17] L Hou X Zhang D Wang and A Baccarelli ldquoEnvironmentalchemical exposures and human epigeneticsrdquo International Jour-nal of Epidemiology vol 41 no 1 pp 79ndash105 2012

[18] U Lim and M-A Song ldquoDietary and lifestyle factors of DNAmethylationrdquo Methods in Molecular Biology vol 863 pp 359ndash376 2012

[19] K M Bakulski and M D Fallin ldquoEpigenetic epidemiologypromises for public health researchrdquo Environmental and Molec-ular Mutagenesis vol 55 no 3 pp 171ndash183 2014

[20] H H Burris and A A Baccarelli ldquoEnvironmental epigeneticsfrom novelty to scientific disciplinerdquo Journal of Applied Toxicol-ogy vol 34 no 2 pp 113ndash116 2014

[21] I Cantone and A G Fisher ldquoEpigenetic programming andreprogramming during developmentrdquo Nature Structural andMolecular Biology vol 20 no 3 pp 282ndash289 2013

[22] S Seisenberger J R Peat and W Reik ldquoConceptual linksbetweenDNAmethylation reprogramming in the early embryoand primordial germ cellsrdquo Current Opinion in Cell Biology vol25 no 3 pp 281ndash288 2013

[23] G Kelsey and R Feil ldquoNew insights into establishment andmaintenance of DNA methylation imprints in mammalsrdquoPhilosophical Transactions of the Royal Society of London SeriesB Biological Sciences vol 368 no 1609 Article ID 201103362013

[24] D J P Barker PDGluckman KMGodfrey J EHarding J AOwens and J S Robinson ldquoFetal nutrition and cardiovasculardisease in adult liferdquoThe Lancet vol 341 no 8850 pp 938ndash9411993

[25] P Dominguez-Salas S E Cox A M Prentice B J Hennigand S E Moore ldquoMaternal nutritional status C

1metabolism

and offspring DNA methylation a review of current evidencein human subjectsrdquo Proceedings of the Nutrition Society vol 71no 1 pp 154ndash165 2012

[26] M Pembrey R Saffery L O Bygren andNetwork in EpigeneticEpidemiology ldquoHuman transgenerational responses to early-life experience potential impact on development health andbiomedical researchrdquo Journal of Medical Genetics vol 51 no 9pp 563ndash572 2014

[27] A Juul K Almstrup A M Andersson et al ldquoPossible fetaldeterminants ofmale infertilityrdquoNature Reviews Endocrinologyvol 10 no 9 pp 553ndash562 2014

[28] R M Sharpe ldquoEnvironmentallifestyle effects on spermatogen-esisrdquo Philosophical Transactions of the Royal Society B BiologicalSciences vol 365 no 1546 pp 1697ndash1712 2010

[29] J D Meeker ldquoExposure to environmental endocrine disruptingcompounds andmenrsquos healthrdquoMaturitas vol 66 no 3 pp 236ndash241 2010

[30] A Giwercman and Y L Giwercman ldquoEnvironmental factorsand testicular functionrdquo Best Practice and Research ClinicalEndocrinology and Metabolism vol 25 no 2 pp 391ndash402 2011

[31] J P Bonde and A Giwercman ldquoEnvironmental xenobiotics andmale reproductive healthrdquo Asian Journal of Andrology vol 16no 1 pp 3ndash4 2014

[32] A Vested A Giwercman J P Bonde and G Toft ldquoPersistentorganic pollutants andmale reproductive healthrdquoAsian Journalof Andrology vol 16 no 1 pp 71ndash80 2014

[33] J Del Mazo M A Brieno-Enrıquez J Garcıa-Lopez L ALopez-Fernandez and M De Felici ldquoEndocrine disruptorsgene deregulation and male germ cell tumorsrdquo InternationalJournal of Developmental Biology vol 57 no 2-4 pp 225ndash2392013

[34] K Singh andD Jaiswal ldquoOne-carbonmetabolism spermatoge-nesis and male infertilityrdquo Reproductive Sciences vol 20 no 6pp 622ndash630 2013


[35] C C Boissonnas P Jouannet and H Jammes ldquoEpigeneticdisorders and male subfertilityrdquo Fertility and Sterility vol 99no 3 pp 624ndash631 2013

[36] R Klaver and J Gromoll ldquoBringing epigenetics into the diag-nostics of the andrology laboratory challenges and perspec-tivesrdquo Asian Journal of Andrology vol 16 no 5 pp 669ndash6742014

[37] J Borgel S Guibert Y Li et al ldquoTargets and dynamics ofpromoter DNAmethylation during early mouse developmentrdquoNature Genetics vol 42 no 12 pp 1093ndash1100 2010

[38] L Daxinger and E Whitelaw ldquoUnderstanding transgenera-tional epigenetic inheritance via the gametes in mammalsrdquoNature Reviews Genetics vol 13 no 2 pp 153ndash162 2012

[39] J M Trasler ldquoEpigenetics in spermatogenesisrdquo Molecular andCellular Endocrinology vol 306 no 1-2 pp 33ndash36 2009

[40] D T Carrell ldquoEpigenetics of the male gameterdquo Fertility andSterility vol 97 no 2 pp 267ndash274 2012

[41] R Guerrero-Preston J Herbstman and L R Goldman ldquoEpige-nomic biomonitors global DNA hypomethylation as a bio-dosimeter of life-long environmental exposuresrdquo Epigenomicsvol 3 no 1 pp 1ndash5 2011

[42] R R Kanherkar N Bhatia-Dey and A B Csoka ldquoEpigeneticsacross the human lifespanrdquo Frontiers in Cell and DevelopmentalBiology vol 2 article 49 2014

[43] P D Ray A Yosim and R C Fry ldquoIncorporating epigeneticdata into the risk assessment process for the toxic metalsarsenic cadmium chromium lead andmercury strategies andchallengesrdquo Frontiers in Genetics vol 5 article 201 2014

[44] K A Bailey and R C Fry ldquoArsenic-associated changes to theepigenome what are the functional consequencesrdquo CurrentEnvironmental Health Reports vol 1 no 1 pp 22ndash34 2014

[45] J R Pilsner X Liu H Ahsan et al ldquoGenomic methylationof peripheral blood leukocyte DNA influences of arsenic andfolate in Bangladeshi adultsrdquo The American Journal of ClinicalNutrition vol 86 no 4 pp 1179ndash1186 2007

[46] S Majumdar S Chanda B Ganguli D N G Mazumder SLahiri and U B Dasgupta ldquoArsenic exposure induces genomichypermethylationrdquo Environmental Toxicology vol 25 no 3 pp315ndash318 2010

[47] M M Niedzwiecki M N Hall X Liu et al ldquoA dose-responsestudy of arsenic exposure and global methylation of peripheralblood mononuclear cell DNA in Bangladeshi adultsrdquo Environ-mentalHealth Perspectives vol 121 no 11-12 pp 1306ndash1312 2013

[48] S Chanda U B Dasgupta D Guhamazumder et al ldquoDNAhypermethylation of promoter of gene p53 and p16 in arsenic-exposed people with and without malignancyrdquo ToxicologicalSciences vol 89 no 2 pp 431ndash437 2006

[49] A-H Zhang H-H Bin X-L Pan and X-G Xi ldquoAnalysis ofp16 gene mutation deletion and methylation in patients witharseniasis produced by indoor unventilated-stove coal usagein Guizhou Chinardquo Journal of Toxicology and EnvironmentalHealth Part A vol 70 no 11 pp 970ndash975 2007

[50] L Smeester J E Rager K A Bailey et al ldquoEpigenetic changes inindividuals with arsenicosisrdquo Chemical Research in Toxicologyvol 24 no 2 pp 165ndash167 2011

[51] M B Hossain M Vahter G Concha and K Broberg ldquoEnvi-ronmental arsenic exposure andDNAmethylation of the tumorsuppressor gene p16 and the DNA repair gene MLH1 effect ofarsenic metabolism and genotyperdquo Metallomics vol 4 no 11pp 1167ndash1175 2012

[52] W-T Chen W-C Hung W-Y Kang Y-C Huang and C-YChai ldquoUrothelial carcinomas arising in arsenic-contaminatedareas are associated with hypermethylation of the gene pro-moter of the death-associated protein kinaserdquo Histopathologyvol 51 no 6 pp 785ndash792 2007

[53] W J Seow M L Kile A A Baccarelli et al ldquoEpigenome-wide DNA methylation changes with development of arsenic-induced skin lesions in Bangladesh a case-control follow-upstudyrdquo Environmental and Molecular Mutagenesis vol 55 no6 pp 449ndash456 2014

[54] T-Y Yang L-I Hsu AW Chiu et al ldquoComparison of genome-wide DNA methylation in urothelial carcinomas of patientswith and without arsenic exposurerdquo Environmental Researchvol 128 pp 57ndash63 2014

[55] M L Kile A Baccarelli E Hoffman et al ldquoPrenatal arsenicexposure andDNAmethylation inmaternal and umbilical cordblood leukocytesrdquo Environmental Health Perspectives vol 120no 7 pp 1061ndash1066 2012

[56] M L Kile E A Houseman A A Baccarelli et al ldquoEffect ofprenatal arsenic exposure on DNA methylation and leukocytesubpopulations in cord bloodrdquo Epigenetics vol 9 no 5 pp 774ndash782 2014

[57] J R Pilsner M N Hall X Liu et al ldquoInfluence of prenatalarsenic exposure and newborn sex on global methylation ofcord blood DNArdquo PLoS ONE vol 7 no 5 Article ID e371472012

[58] P Intarasunanont P Navasumrit SWaraprasit et al ldquoEffects ofarsenic exposure on DNA methylation in cord blood samplesfrom newborn babies and in a human lymphoblast cell linerdquoEnvironmental Health A Global Access Science Source vol 11no 1 article 31 2012

[59] D C Koestler M Avissar-Whiting E A Houseman M RKaragas and C J Marsit ldquoDifferential DNA methylation inumbilical cord blood of infants exposed to low levels of arsenicin uterordquo Environmental Health Perspectives vol 121 no 8 pp971ndash977 2013

[60] D Rojas J E Rager L Smeester et al ldquoPrenatal arsenic expo-sure and the epigenome identifying sites of 5-methylcytosinealterations that predict functional changes in gene expressionin newborn cord blood and subsequent birth outcomesrdquo Toxi-cological Sciences vol 143 no 1 pp 97ndash106 2015

[61] T-C Wang Y-S Song H Wang et al ldquoOxidative DNAdamage and global DNA hypomethylation are related to folatedeficiency in chromate manufacturing workersrdquo Journal ofHazardous Materials vol 213-214 pp 440ndash446 2012

[62] C W Hanna M S Bloom W P Robinson et al ldquoDNAmethylation changes in whole blood is associated with exposureto the environmental contaminants mercury lead cadmiumand bisphenol A in women undergoing ovarian stimulation forIVFrdquo Human Reproduction vol 27 no 5 pp 1401ndash1410 2012

[63] JM Goodrich N Basu A Franzblau andD C Dolinoy ldquoMer-cury biomarkers andDNAmethylation amongmichigan dentalprofessionalsrdquo Environmental and Molecular Mutagenesis vol54 no 3 pp 195ndash203 2013

[64] R O Wright J Schwartz R J Wright et al ldquoBiomarkers oflead exposure and DNA methylation within retrotransposonsrdquoEnvironmental Health Perspectives vol 118 no 6 pp 790ndash7952010

[65] L Kovatsi E Georgiou A Ioannou et al ldquoP16 promotermethylation in Pb2+-exposed individualsrdquo Clinical Toxicologyvol 48 no 2 pp 124ndash128 2010


[66] M B Hossain M Vahter G Concha and K Broberg ldquoLow-level environmental cadmium exposure is associated withDNA hypomethylation in Argentinean womenrdquo EnvironmentalHealth Perspectives vol 120 no 6 pp 879ndash884 2012

[67] J R Pilsner M N Hall X Liu et al ldquoAssociations of plasmaselenium with arsenic and genomic methylation of leukocyteDNA in bangladeshrdquo Environmental Health Perspectives vol119 no 1 pp 113ndash118 2011

[68] A P Sanders L Smeester D Rojas et al ldquoCadmium exposureand the epigenome exposure-associated patterns of DNAmethylation in leukocytes frommother-baby pairsrdquoEpigeneticsvol 9 no 2 pp 212ndash221 2014

[69] H Ji and G K Khurana Hershey ldquoGenetic and epigeneticinfluence on the response to environmental particulate matterrdquoJournal of Allergy and Clinical Immunology vol 129 no 1 pp33ndash41 2012

[70] S De Prins G Koppen G Jacobs et al ldquoInfluence of ambientair pollution on global DNA methylation in healthy adults aseasonal follow-uprdquo Environment International vol 59 pp 418ndash424 2013

[71] A Baccarelli R O Wright V Bollati et al ldquoRapid DNAmethylation changes after exposure to traffic particlesrdquo TheAmerican Journal of Respiratory and Critical Care Medicine vol179 no 7 pp 572ndash578 2009

[72] J Madrigano A Baccarelli M A Mittleman et al ldquoProlongedexposure to particulate pollution genes associated with glu-tathione pathways and DNA methylation in a cohort of oldermenrdquo Environmental Health Perspectives vol 119 no 7 pp 977ndash982 2011

[73] M A Bind J Lepeule A Zanobetti et al ldquoAir pollutionand gene-specific methylation in the Normative Aging Studyassociation effect modification and mediation analysisrdquo Epige-netics vol 9 no 3 pp 448ndash458 2014

[74] J Lepeule M-A C Bind A A Baccarelli et al ldquoEpigeneticinfluences on associations between air pollutants and lung func-tion in elderly men the normative aging studyrdquo EnvironmentalHealth Perspectives vol 122 no 6 pp 566ndash572 2014

[75] K Nadeau C McDonald-Hyman E M Noth et al ldquoAmbientair pollution impairs regulatory T-cell function in asthmardquoJournal of Allergy and Clinical Immunology vol 126 no 4 pp845e10ndash852e10 2010

[76] C V Breton M T Salam X Wang H-M Byun K D Sieg-mund and F D Gilliland ldquoParticulate matter DNA methyla-tion in nitric oxide synthase and childhood respiratory diseaserdquoEnvironmental Health Perspectives vol 120 no 9 pp 1320ndash13262012

[77] M T Salam H M Byun F Lurmann et al ldquoGenetic andepigenetic variations in inducible nitric oxide synthase pro-moter particulate pollution and exhaled nitric oxide levels inchildrenrdquo Journal of Allergy and Clinical Immunology vol 129no 1 pp 232e7ndash239e7 2012

[78] J B Herbstman D Tang D Zhu et al ldquoPrenatal exposureto polycyclic aromatic hydrocarbons benzo[a]pyrene-DNAadducts and genomic DNA methylation in cord bloodrdquo Envi-ronmental Health Perspectives vol 120 no 5 pp 733ndash738 2012

[79] F Perera W-Y Tang J Herbstman et al ldquoRelation of DNAmethylation of 51015840-CpG island of ACSL3 to transplacentalexposure to airborne polycyclic aromatic hydrocarbons andchildhood asthmardquo PLoS ONE vol 4 no 2 Article ID e44882009

[80] W-Y Tang L Levin G Talaska et al ldquoMaternal exposure topolycyclic aromatic hydrocarbons and 51015840-CpG methylation of

interferon-120574 in cord white blood cellsrdquo Environmental HealthPerspectives vol 120 no 8 pp 1195ndash1200 2012

[81] L Tarantini M Bonzini P Apostoli et al ldquoEffects of partic-ulate matter on genomic DNA methylation content and iNOSpromoter methylationrdquo Environmental Health Perspectives vol117 no 2 pp 217ndash222 2009

[82] L Hou X Zhang L Tarantini et al ldquoAmbient PM exposure andDNA methylation in tumor suppressor genes a cross-sectionalstudyrdquo Particle and Fibre Toxicology vol 8 article 25 2011

[83] L Dioni M Hoxha F Nordio et al ldquoEffects of short-termexposure to inhalable particulate matter on telomere lengthtelomerase expression and telomerase methylation in steelworkersrdquo Environmental Health Perspectives vol 119 no 5 pp622ndash627 2011

[84] S Pavanello V Bollati A C Pesatori et al ldquoGlobal andgene-specific promoter methylation changes are related toanti-B[a]PDE-DNA adduct levels and influence micronucleilevels in polycyclic aromatic hydrocarbon-exposed individualsrdquoInternational Journal of Cancer vol 125 no 7 pp 1692ndash16972009

[85] L Guo H-M Byun J Zhong et al ldquoEffects of short-termexposure to inhalable particulate matter on DNA methylationof tandem repeatsrdquo Environmental and Molecular Mutagenesisvol 55 no 4 pp 322ndash335 2014

[86] L Hou X Zhang Y Zheng et al ldquoAltered methylation intandem repeat element and elemental component levels ininhalable air particlesrdquo Environmental and Molecular Mutage-nesis vol 55 no 3 pp 256ndash265 2014

[87] H-M ByunVMotta T Panni et al ldquoEvolutionary age of repet-itive element subfamilies and sensitivity of DNAmethylation toairborne pollutantsrdquo Particle and Fibre Toxicology vol 10 no 1article 28 2013

[88] M Peluso V Bollati A Munnia et al ldquoDNA methylationdifferences in exposed workers and nearby residents of theMa Ta phut industrial estate rayong Thailandrdquo InternationalJournal of Epidemiology vol 41 no 6 pp 1753ndash1760 2012

[89] V Bollati A Baccarelli L Hou et al ldquoChanges in DNAmethylation patterns in subjects exposed to low-dose benzenerdquoCancer Research vol 67 no 3 pp 876ndash880 2007

[90] S Fustinoni F Rossella E Polledri et al ldquoGlobal DNAmethylation and low-level exposure to benzenerdquo La Medicinadel Lavoro vol 103 no 2 pp 84ndash95 2012

[91] W J Seow A C Pesatori E Dimont et al ldquoUrinary benzenebiomarkers and DNA methylation in Bulgarian petrochemicalworkers study findings and comparison of linear and betaregression modelsrdquo PLoS ONE vol 7 no 12 Article ID e504712012

[92] J A Rusiecki A Baccarelli V Bollati L Tarantini L E Mooreand E C Bonefeld-Jorgensen ldquoGlobal DNA hypomethylationis associated with high serum-persistent organic pollutants inGreenlandic inuitrdquo Environmental Health Perspectives vol 116no 11 pp 1547ndash1552 2008

[93] K-Y Kim D-S Kim S-K Lee et al ldquoAssociation of low-dose exposure to persistent organic pollutants with global DNAhypomethylation in healthy Koreansrdquo Environmental HealthPerspectives vol 118 no 3 pp 370ndash374 2010

[94] J H Kim L S Rozek A S Soliman et al ldquoBisphenol A-associated epigenomic changes in prepubescent girls a cross-sectional study in Gharbiah Egyptrdquo Environmental Health AGlobal Access Science Source vol 12 article 33 2013


[95] D J Watkins G A Wellenius R A Butler S M Bartell TFletcher and K T Kelsey ldquoAssociations between serum per-fluoroalkyl acids and LINE-1 DNA methylationrdquo EnvironmentInternational vol 63 pp 71ndash76 2014

[96] G Leter C Consales P Eleuteri et al ldquoExposure to perflu-oroalkyl substances and sperm DNA global methylation inarctic and european populationsrdquo Environmental andMolecularMutagenesis vol 55 no 7 pp 591ndash600 2014

[97] R Guerrero-Preston L R Goldman P Brebi-Mieville et alldquoGlobal DNA hypomethylation is associated with in uteroexposure to cotinine and perfluorinated alkyl compoundsrdquoEpigenetics vol 5 no 6 pp 539ndash546 2010

[98] K Huen P Yousefi A Bradman et al ldquoEffects of age sex andpersistent organic pollutants on DNAmethylation in childrenrdquoEnvironmental and Molecular Mutagenesis vol 55 no 3 pp209ndash222 2014

[99] N VilahurM Bustamante H Byun et al ldquoPrenatal exposure tomixtures of xenoestrogens and repetitive element DNAmethy-lation changes in human placentardquo Environment Internationalvol 71 pp 81ndash87 2014

[100] A C Vidal S K Murphy A P Murtha et al ldquoAssociationsbetween antibiotic exposure during pregnancy birth weightand aberrant methylation at imprinted genes among offspringrdquoInternational Journal of Obesity vol 37 no 7 pp 907ndash913 2013

[101] V S Knopik M A MaCcani S Francazio and J E McGearyldquoThe epigenetics of maternal cigarette smoking during preg-nancy and effects on child developmentrdquo Development andPsychopathology vol 24 no 4 pp 1377ndash1390 2012

[102] K W K Lee and Z Pausova ldquoCigarette smoking and DNAmethylationrdquo Frontiers in Genetics vol 4 article 132 2013

[103] L P Breitling R Yang B Korn B Burwinkel and H BrennerldquoTobacco-smoking-related differential DNA methylation 27Kdiscovery and replicationrdquo American Journal of Human Genet-ics vol 88 no 4 pp 450ndash457 2011

[104] L P Breitling K Salzmann D Rothenbacher B Burwinkeland H Brenner ldquoSmoking F2RL3 methylation and prognosisin stable coronary heart diseaserdquo European Heart Journal vol33 no 22 pp 2841ndash2848 2012

[105] N S Shenker S Polidoro K van Veldhoven et al ldquoEpigenome-wide association study in the European Prospective Inves-tigation into Cancer and Nutrition (EPIC-Turin) identifiesnovel genetic loci associated with smokingrdquo Human MolecularGenetics vol 22 no 5 pp 843ndash851 2013

[106] Y Zhang R Yang B Burwinkel L P Breitling and H BrennerldquoF2RL3 methylation as a biomarker of current and lifetimesmoking exposuresrdquo Environmental Health Perspectives vol122 no 2 pp 131ndash137 2014

[107] Y Zhang R Yang B Burwinkel et al ldquoF2RL3 methylation inblood DNA is a strong predictor of mortalityrdquo InternationalJournal of Epidemiology vol 43 no 4 pp 1215ndash1225 2014

[108] M M Monick S R H Beach J Plume et al ldquoCoordinatedchanges in AHRRmethylation in lymphoblasts and pulmonarymacrophages from smokersrdquo American Journal of MedicalGenetics Part B Neuropsychiatric Genetics vol 159 no 2 pp141ndash151 2012

[109] R A Philibert S R H Beach andGH Brody ldquoDemethylationof the aryl hydrocarbon receptor repressor as a biomarker fornascent smokersrdquo Epigenetics vol 7 no 11 pp 1331ndash1338 2012

[110] R A Philibert S R H Beach M-K Lei and G H BrodyldquoChanges in DNAmethylation at the aryl hydrocarbon receptorrepressor may be a new biomarker for smokingrdquo ClinicalEpigenetics vol 5 no 1 article 19 2013

[111] N S Shenker PMUeland S Polidoro et al ldquoDNAmethylationas a long-term biomarker of exposure to tobacco smokerdquoEpidemiology vol 24 no 5 pp 712ndash716 2013

[112] MVDogan B Shields C Cutrona et al ldquoThe effect of smokingon DNA methylation of peripheral blood mononuclear cellsfrom African American womenrdquo BMC Genomics vol 15 no 1article 151 2014

[113] C V Breton H-M Byun M Wenten F Pan A Yang and FD Gilliland ldquoPrenatal tobacco smoke exposure affects globaland gene-specific DNA methylationrdquo The American Journal ofRespiratory and Critical Care Medicine vol 180 no 5 pp 462ndash467 2009

[114] C V Breton M T Salam and F D Gilliland ldquoHeritability androle for the environment in DNA methylation in AXL receptortyrosine kinaserdquo Epigenetics vol 6 no 7 pp 895ndash898 2011

[115] C V Breton K D Siegmund B R Joubert et al ldquoPrenataltobacco smoke exposure is associated with childhood DNACpG methylationrdquo PLoS ONE vol 9 no 6 Article ID e997162014

[116] M Suter A Abramovici L Showalter et al ldquoIn utero tobaccoexposure epigenetically modifies placental CYP1A1 expressionrdquoMetabolism vol 59 no 10 pp 1481ndash1490 2010

[117] M Suter J Ma A Harris et al ldquoMaternal tobacco use modestlyalters correlated epigenome-wide placental DNA methylationand gene expressionrdquo Epigenetics vol 6 no 11 pp 1284ndash12942011

[118] B R Joubert S E Haberg R M Nilsen et al ldquo450Kepigenome-wide scan identifies differential DNA methylationin newborns related to maternal smoking during pregnancyrdquoEnvironmental Health Perspectives vol 120 no 10 pp 1425ndash1431 2012

[119] S K Murphy A Adigun Z Huang et al ldquoGender-specificmethylation differences in relation to prenatal exposure tocigarette smokerdquo Gene vol 494 no 1 pp 36ndash43 2012

[120] C S Wilhelm-Benartzi E A Houseman M A Maccani etal ldquoIn utero exposures infant growth and DNA methylationof repetitive elements and developmentally related genes inhuman placentardquo Environmental Health Perspectives vol 120no 2 pp 296ndash302 2012

[121] J Z JMaccani D C Koestler E AHouseman C JMarsit andK T Kelsey ldquoPlacental DNAmethylation alterations associatedwith maternal tobacco smoking at the RUNX3 gene are alsoassociated with gestational agerdquo Epigenomics vol 5 no 6 pp619ndash630 2013

[122] K W Lee R Richmond P Hu et al ldquoPrenatal exposure tomaternal cigarette smoking and DNAmethylation epigenome-wide association in a discovery sample of adolescents andreplication in an independent cohort at birth through 17 yearsof agerdquo Environmental Health Perspectives vol 123 no 2 pp193ndash199 2015

[123] A Soubry C Hoyo R L Jirtle and S K Murphy ldquoA pater-nal environmental legacy evidence for epigenetic inheritancethrough the male germ linerdquo BioEssays vol 36 no 4 pp 359ndash371 2014

[124] A Soubry J M Schildkraut A Murtha et al ldquoPaternal obesityis associated with IGF2 hypomethylation in newborns resultsfrom a Newborn Epigenetics Study (NEST) cohortrdquo BMCMedicine vol 11 no 1 article 29 2013

[125] A Soubry S K Murphy F Wang et al ldquoNewborns of obeseparents have altered DNA methylation patterns at imprintedgenesrdquo International Journal of Obesity vol 39 pp 650ndash6572015


[126] T G Jenkins K I Aston B R Cairns and D T CarrellldquoPaternal aging and associated intraindividual alterations ofglobal sperm 5-methylcytosine and 5-hydroxymethylcytosinelevelsrdquo Fertility and Sterility vol 100 no 4 pp 945ndash951 2013

[127] T G Jenkins K I Aston C Pflueger B R Cairns D T Carrelland J M Greally ldquoAge-associated sperm DNA methylationalterations possible implications in offspring disease suscepti-bilityrdquo PLoS Genetics vol 10 no 7 Article ID e1004458 2014

[128] C Consales G Leter J P Bonde et al ldquoIndices of methyla-tion in sperm DNA from fertile men differ between distinctgeographical regionsrdquo Human Reproduction vol 29 no 9 pp2065ndash2072 2014

[129] D Kumar S R Salian G Kalthur et al ldquoSemen abnormalitiessperm DNA damage and global hypermethylation in healthworkers occupationally exposed to ionizing radiationrdquo PLoSONE vol 8 no 7 Article ID e69927 2013

[130] D M Bielawski F M Zaher D M Svinarich and E LAbel ldquoPaternal alcohol exposure affects sperm cytosinemethyl-transferase messenger RNA levelsrdquo Alcoholism Clinical andExperimental Research vol 26 no 3 pp 347ndash351 2002

[131] L A Ouko K Shantikumar J Knezovich P Haycock D JSchnugh and M Ramsay ldquoEffect of alcohol consumption onCpGmethylation in the differentiallymethylated regions ofH19and IG-DMR in male gametesmdashimplications for fetal alcoholspectrum disordersrdquo Alcoholism Clinical and ExperimentalResearch vol 33 no 9 pp 1615ndash1627 2009

[132] M Lane R L Robker and S A Robertson ldquoParenting frombefore conceptionrdquo Science vol 345 no 6198 pp 756ndash7602014

[133] X Liu Q Chen H-J Tsai et al ldquoMaternal preconceptionbody mass index and offspring cord blood DNA methylationexploration of early life origins of diseaserdquo Environmental andMolecular Mutagenesis vol 55 no 3 pp 223ndash230 2014

[134] L H Lumey M B Terry L Delgado-Cruzata et al ldquoAdultglobal DNA methylation in relation to pre-natal nutritionrdquoInternational Journal of Epidemiology vol 41 no 1 pp 116ndash1232012

[135] B T Heijmans E W Tobi A D Stein et al ldquoPersistentepigenetic differences associated with prenatal exposure tofamine in humansrdquo Proceedings of the National Academy ofSciences of the United States of America vol 105 no 44 pp17046ndash17049 2008

[136] B T Heijmans E W Tobi L H Lumey and P E SlagboomldquoThe epigenome archive of the prenatal environmentrdquo Epige-netics vol 4 no 8 pp 526ndash531 2009

[137] E W Tobi L H Lumey R P Talens et al ldquoDNA methylationdifferences after exposure to prenatal famine are common andtiming- and sex-specificrdquo Human Molecular Genetics vol 18no 21 pp 4046ndash4053 2009

[138] E W Tobi B T Heijmans D Kremer et al ldquoDNAmethylationof IGF2 GNASAS INSIGF and LEP and being born small forgestational agerdquo Epigenetics vol 6 no 2 pp 171ndash176 2011

[139] E W Tobi P E Slagboom J van Dongen et al ldquoPrenatalfamine and genetic variation are independently and additivelyassociated with dna methylation at regulatory loci withinIGF2H19rdquo PLoS ONE vol 7 no 5 Article ID e37933 2012

[140] E W Tobi J J Goeman R Monajemi et al ldquoDNA methyla-tion signatures link prenatal famine exposure to growth andmetabolismrdquo Nature Communications vol 5 article 5592 2014

[141] C Hoyo A P Murtha J M Schildkraut et al ldquoMethylationvariation at IGF2 differentiallymethylated regions andmaternal

folic acid use before and during pregnancyrdquo Epigenetics vol 6no 7 pp 928ndash936 2011

[142] P Haggarty G Hoad D M Campbell G W Horgan C Piy-athilake and G McNeill ldquoFolate in pregnancy and imprintedgene and repeat element methylation in the offspringrdquo Ameri-can Journal of Clinical Nutrition vol 97 no 1 pp 94ndash99 2013

[143] C E Boeke A Baccarelli K P Kleinman et al ldquoGestationalintake of methyl donors and global LINE-1 DNA methylationin maternal and cord blood prospective results from a folate-replete populationrdquo Epigenetics vol 7 no 3 pp 253ndash260 2012

[144] R A Waterland R Kellermayer E Laritsky et al ldquoSeason ofconception in rural gambia affects DNAmethylation at putativehuman metastable epiallelesrdquo PLoS Genetics vol 6 no 12Article ID e1001252 2010

[145] P Dominguez-Salas S E Moore M S Baker et al ldquoMaternalnutrition at conception modulates DNAmethylation of humanmetastable epiallelesrdquo Nature Communications vol 5 article3746 2014

[146] R A Harris D Nagy-Szakal and R Kellermayer ldquoHumanmetastable epiallele candidates link to common disordersrdquoEpigenetics vol 8 no 2 pp 157ndash163 2013

[147] Y Liu S K Murphy A P Murtha et al ldquoDepression inpregnancy infant birthweight andDNAmethylation of imprintregulatory elementsrdquo Epigenetics vol 7 no 7 pp 735ndash746 2012

[148] L Cao-Lei RMassartM J Suderman et al ldquoDNAmethylationsignatures triggered by prenatal maternal stress exposure to anatural disaster project ice stormrdquo PLoS ONE vol 9 no 9Article ID e107653 2014

[149] T Fullston E M C O Teague N O Palmer et al ldquoPaternalobesity initiates metabolic disturbances in two generations ofmice with incomplete penetrance to the F2 generation andalters the transcriptional profile of testis and sperm microRNAcontentrdquoTheFASEB Journal vol 27 no 10 pp 4226ndash4243 2013

[150] A B Rodgers C P Morgan S L Bronson S Revello andT L Bale ldquoPaternal stress exposure alters sperm MicroRNAcontent and reprograms offspring HPA stress axis regulationrdquoThe Journal of Neuroscience vol 33 no 21 pp 9003ndash9012 2013

[151] K Gapp A Jawaid P Sarkies et al ldquoImplication of spermRNAsin transgenerational inheritance of the effects of early trauma inmicerdquo Nature Neuroscience vol 17 no 5 pp 667ndash669 2014

[152] E J Radford M Ito H Shi et al ldquoIn utero undernourishmentperturbs the adult sperm methylome and intergenerationalmetabolismrdquo Science vol 345 no 6198 Article ID 12559032014

[153] B R Carone L Fauquier N Habib et al ldquoPaternally inducedtransgenerational environmental reprogramming of metabolicgene expression inmammalsrdquoCell vol 143 no 7 pp 1084ndash10962010

[154] R Lambrot C Xu S Saint-Phar et al ldquoLow paternal dietaryfolate alters the mouse sperm epigenome and is associated withnegative pregnancy outcomesrdquo Nature Communications vol 4article 2889 2013

[155] X Tian and F J Diaz ldquoAcute dietary zinc deficiency beforeconception compromises oocyte epigenetic programming anddisrupts embryonic developmentrdquo Developmental Biology vol376 no 1 pp 51ndash61 2013

[156] Y Wei C-R Yang Y-P Wei et al ldquoPaternally inducedtransgenerational inheritance of susceptibility to diabetes inmammalsrdquo Proceedings of the National Academy of Sciences ofthe United States of America vol 111 no 5 pp 1873ndash1878 2014


[157] Z-J Ge X-W Liang L Guo et al ldquoMaternal diabetes causesalterations of DNA methylation statuses of some imprintedgenes in murine oocytesrdquo Biology of Reproduction vol 88 no5 article 117 9 pages 2013

[158] Z J Ge S M Luo F Lin et al ldquoDNA methylation in oocytesand liver of female mice and their offspring Effects of high-fat-diet-induced obesityrdquo Environmental Health Perspectives vol122 no 2 pp 159ndash164 2014

[159] M D Anway A S Cupp N Uzumcu and M K SkinnerldquoToxicology epigenetic transgenerational actions of endocrinedisruptors and male fertilityrdquo Science vol 308 no 5727 pp1466ndash1469 2005

[160] K Inawaka M Kawabe S Takahashi et al ldquoMaternal exposureto anti-androgenic compounds vinclozolin flutamide andprocymidone has no effects on spermatogenesis and DNAmethylation in male rats of subsequent generationsrdquo Toxicologyand Applied Pharmacology vol 237 no 2 pp 178ndash187 2009

[161] C Stouder and A Paoloni-Giacobino ldquoTransgenerationaleffects of the endocrine disruptor vinclozolin on the methyla-tion pattern of imprinted genes in the mouse spermrdquo Reproduc-tion vol 139 no 2 pp 373ndash379 2010

[162] C Stouder and A Paoloni-Giacobino ldquoSpecific transgenera-tional imprinting effects of the endocrine disruptor methoxy-chlor on male gametesrdquo Reproduction vol 141 no 2 pp 207ndash216 2011

[163] E Somm C Stouder and A Paoloni-Giacobino ldquoEffect ofdevelopmental dioxin exposure on methylation and expressionof specific imprinted genes in micerdquo Reproductive Toxicologyvol 35 no 1 pp 150ndash155 2013

[164] H-H Chao X-F Zhang B Chen et al ldquoBisphenol A exposuremodifies methylation of imprinted genes in mouse oocytes viathe estrogen receptor signaling pathwayrdquo Histochemistry andCell Biology vol 137 no 2 pp 249ndash259 2012

[165] T Trapphoff M Heiligentag N El Hajj T Haaf and UEichenlaub-Ritter ldquoChronic exposure to a low concentration ofbisphenol A during follicle culture affects the epigenetic statusof germinal vesicles and metaphase II oocytesrdquo Fertility andSterility vol 100 no 6 pp 1758e1ndash1767e1 2013

[166] T Doshi C DrsquoSouza and G Vanage ldquoAberrant DNA methyla-tion at Igf2-H19 imprinting control region in spermatozoa uponneonatal exposure to bisphenol A and its association with postimplantation lossrdquoMolecular Biology Reports vol 40 no 8 pp4747ndash4757 2013

[167] C Yauk A Polyzos A Rowan-Carroll et al ldquoGerm-linemutations DNA damage and global hypermethylation in miceexposed to particulate air pollution in an urbanindustriallocationrdquo Proceedings of the National Academy of Sciences of theUnited States of America vol 105 no 2 pp 605ndash610 2008

[168] C Stouder E Somm and A Paoloni-Giacobino ldquoPrenatalexposure to ethanol a specific effect on the H19 gene in spermrdquoReproductive Toxicology vol 31 no 4 pp 507ndash512 2011

[169] J G Knezovich and M Ramsay ldquoThe effect of preconceptionpaternal alcohol exposure on epigenetic remodeling of the H19and Rasgrf1 imprinting control regions in mouse offspringrdquoFrontiers in Genetics vol 3 article 10 2012

[170] N A Kedia-Mokashi L KadamM Ankolkar K Dumasia andN H Balasinor ldquoAberrant methylation of multiple imprintedgenes in embryos of tamoxifen-treatedmale ratsrdquoReproductionvol 146 no 2 pp 155ndash168 2013

[171] S Pathak N Kedia-Mokashi M Saxena et al ldquoEffect oftamoxifen treatment on global and insulin-like growth factor

2-H19 locus-specific DNA methylation in rat spermatozoa andits association with embryo lossrdquo Fertility and Sterility vol 91no 5 supplement pp 2253ndash2263 2009

[172] D Xia N Parvizi Y Zhou et al ldquoPaternal fenvalerate exposureinfluences reproductive functions in the offspringrdquo Reproduc-tive Sciences vol 20 no 11 pp 1308ndash1315 2013

[173] J-Q Zhu Y-J Si L-Y Cheng et al ldquoSodium fluoride disruptsDNA methylation of H19 and Peg3 imprinted genes during theearly development of mouse embryordquo Archives of Toxicologyvol 88 no 2 pp 241ndash248 2014

[174] S Pathak M Saxena R DrsquoSouza and N H Balasinor ldquoDis-rupted imprinting status at the H19 differentially methylatedregion is associated with the resorbed embryo phenotype inratsrdquo Reproduction Fertility and Development vol 22 no 6 pp939ndash948 2010

[175] B G Dias andK J Ressler ldquoParental olfactory experience influ-ences behavior and neural structure in subsequent generationsrdquoNature Neuroscience vol 17 no 1 pp 89ndash96 2014

[176] C P Wild ldquoEnvironmental exposure measurement in cancerepidemiologyrdquoMutagenesis vol 24 no 2 pp 117ndash125 2009

[177] F Ricceri M Trevisan V Fiano et al ldquoSeasonality modifiesmethylation profiles in healthy peoplerdquo PLoS ONE vol 9 no9 Article ID e106846 2014

[178] M-A Bind A Zanobetti A Gasparrini et al ldquoEffects oftemperature and relative humidity on DNA methylationrdquo Epi-demiology vol 25 no 4 pp 561ndash569 2014

[179] V Bollati A Baccarelli S Sartori et al ldquoEpigenetic effects ofshiftwork on blood DNA methylationrdquo Chronobiology Interna-tional vol 27 no 5 pp 1093ndash1104 2010

[180] Y Zhu R G Stevens A E Hoffman et al ldquoEpigeneticimpact of long-term shiftwork pilot evidence from circadiangenes and whole-genome methylation analysisrdquo ChronobiologyInternational vol 28 no 10 pp 852ndash861 2011

[181] F Shi X Chen A Fu et al ldquoAberrant DNAmethylation ofmiR-219 promoter in long-term night shiftworkersrdquo Environmentaland Molecular Mutagenesis vol 54 no 6 pp 406ndash413 2013

[182] D I Jacobs J Hansen A Fu et al ldquoMethylation alterationsat imprinted genes detected among long-term shiftworkersrdquoEnvironmental and Molecular Mutagenesis vol 54 no 2 pp141ndash146 2013

[183] A L Teh H Pan L Chen et al ldquoThe effect of genotype andin utero environment on interindividual variation in neonateDNA methylomesrdquo Genome Research vol 24 no 7 pp 1064ndash1074 2014

[184] S Shah A F McRae R E Marioni et al ldquoGenetic andenvironmental exposures constrain epigenetic drift over thehuman life courserdquo Genome Research vol 24 no 11 pp 1725ndash1733 2014

[185] J Kim K Kim H Kim G Yoon and K Lee ldquoCharacterizationof age signatures of DNA methylation in normal and cancertissues from multiple studiesrdquo BMC Genomics vol 15 no 1 p997 2014

[186] LM Reynolds J R Taylor J Ding et al ldquoAge-related variationsin the methylome associated with gene expression in humanmonocytes and T cellsrdquoNature Communications vol 5 p 53662014

[187] J L Mcclay K A Aberg S L Clark et al ldquoA methylome-wide study of aging using massively parallel sequencing of themethyl-CpG-enriched genomic fraction fromblood in over 700subjectsrdquo Human Molecular Genetics vol 23 no 5 pp 1175ndash1185 2014


[188] S D Fouse R P Nagarajan and J F Costello ldquoGenome-scaleDNA methylation analysisrdquo Epigenomics vol 2 no 1 pp 105ndash117 2010

[189] P W Laird ldquoPrinciples and challenges of genome-wide DNAmethylation analysisrdquoNature Reviews Genetics vol 11 no 3 pp191ndash203 2010

[190] E Meaburn and R Schulz ldquoNext generation sequencing inepigenetics insights and challengesrdquo Seminars in Cell andDevelopmental Biology vol 23 no 2 pp 192ndash199 2012

[191] K Mensaert S Denil G Trooskens W van Criekinge OThas and T de Meyer ldquoNext-generation technologies anddata analytical approaches for epigenomicsrdquo Environmental andMolecular Mutagenesis vol 55 no 3 pp 155ndash170 2014

[192] A S Yang M R H Estecio K Doshi Y Kondo E H Tajaraand J-P J Issa ldquoA simple method for estimating global DNAmethylation using bisulfite PCR of repetitive DNA elementsrdquoNucleic Acids Research vol 32 no 3 article e38 2004

[193] J Tost and I G Gut ldquoDNA methylation analysis by pyrose-quencingrdquo Nature Protocols vol 2 no 9 pp 2265ndash2275 2007

[194] M Bibikova B Barnes C Tsan et al ldquoHigh density DNAmethylation array with single CpG site resolutionrdquo Genomicsvol 98 no 4 pp 288ndash295 2011

[195] E M Price A M Cotton M S Penaherrera D E McFaddenM S Kobor and W P Robinson ldquoDifferent measures oflsquogenome-widersquo DNA methylation exhibit unique properties inplacental and somatic tissuesrdquo Epigenetics vol 7 no 6 pp 652ndash663 2012

[196] T Mikeska and J M Craig ldquoDNA methylation biomarkerscancer and beyondrdquo Genes vol 5 no 3 pp 821ndash864 2014

[197] A Molaro E Hodges F Fang et al ldquoSperm methylationprofiles reveal features of epigenetic inheritance and evolutionin primatesrdquo Cell vol 146 no 6 pp 1029ndash1041 2011

[198] C Krausz J Sandoval S Sayols et al ldquoNovel insights into DNAmethylation features in spermatozoa stability and peculiari-tiesrdquo PLoS ONE vol 7 no 10 Article ID e44479 2012

Submit your manuscripts athttpwwwhindawicom

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Anesthesiology Research and Practice

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Journal of


Pharmaceutics


MEDIATORSINFLAMMATION

of


A rapidly growing number of epidemiological studieshave been carried out throughout the world in whichenvironmental exposure and lifestyle (an umbrella termincluding diet behavior stress physical activity workinghabits voluntary alcohol and tobacco consumption etc)meshed with the genetic background have been associatedwith epigenetic changes mostly DNAmethylation (reviewedin [11ndash18]) The trend in the field appears to shift fromthe introduction of a novel ldquoproof-of-principlerdquo approach intoxicology to a more systematic scientific specialty [19 20]

Environmental epidemiology research is addressing epi-genetic mechanisms as mediators of environmental exposureon disease risk or just as biosensors of exposure even ifnot mechanistically relevant Because stable methylationmarks at differentially methylated regions (DMRs) regulatingimprinted genes are acquired before gastrulation they mayserve as archives of early exposure with the potential toimprove our understanding of developmental origin of adultdiseases

DNA methylation has been by far the most extensivelymeasured epigenetic mark because of its obviously funda-mental biological interest its mitotic stability the availabilityof methods for its quantification globally or in targetedregions its stability during the DNA extraction and purifi-cation procedures and its durability in archival biologicalmaterials By and large the strategy consists of comparativelyassessing the methylation differences at CpG islands in genepromoters or DMRs between control and exposed groups

The information on DNAmethylation status and changesin association with environmental exposure and lifestylehas been mostly collected from peripheral blood leukocytes(PBL) which can be sampled by a minimally invasiveapproach However tissue specificity together with purityof cells for DNA methylation determination represents arelevant issue in epigenetic studies as each tissue and within atissue probably each cell type have its own epigenetic profile

During our lifetime the genome undergoes two mainepigenomic reprogramming periods each of which involveswaves ofDNAdemethylation andde novomethylationTheseprecise and coordinated genome-wide reprogramming stepsare associated with pivotal developmental stages like theestablishment of cell totipotency and the differentiation of thegerm cell lineages [21 22]The first wave occurs with notabledifferences between sexes in all cells of the preimplantationembryo The second wave occurs in primordial germ cells(PGCs) only this time the demethylation events are moreradical and involve imprinted genes whose allelic-specificmethylation is first erased and then reset according to thesex of the germline [23] Conceivably these phases of mam-malian development are especially sensitive to environmentalstressors which can impact epigenetic plasticity with poten-tial enduring effects on metabolic pathways and disease sus-ceptibility Indeed such scenario would be in agreement withthe theory of the fetal basis of adult onset disease [24ndash26]

The early fetal period of life is particularly criticalfor gonadal development and many common reproductivedisorders of the adult male such as infertility and testiscancer have been proposed to have a fetal origin [27] Inaddition prenatal exposure to environmental contaminants

especially those belonging to the variegated and heteroge-neous class of compounds collectively defined as endocrinedisruptors (EDs) has been linked to the increased incidenceof male reproductive pathologies [28ndash32] The interferencewith developmental epigenetic processes has been evoked asone of the potential mechanisms of EDs action affecting theintegrity of the male reproductive system [33] Recent evi-dence that unbalanced one carbon metabolism may impactmale reproductive health [34] and that a variety of epigeneticmarkers including global or gene-specific DNAmethylationcan be altered in infertility patients [35 36] is in agreementwith this hypothesis

In spite of the extensive DNA demethylation occurringin preimplantation embryonic cells there are sequencescorresponding primarily but not exclusively to parentallyimprinted genes that escape global demethylation [37 38]This means that changes of DNA methylation induced byenvironmental stressors in germ cells could not only haveconsequences for the reproductive health of the exposedindividual but also might be potentially heritable from onegeneration to another and might cause transgenerationaladverse effects by a nongenetic mechanism of inheritance

Notwithstanding the knowledge about epigenetic reg-ulation of gonadal development and the evidence aboutepigenetic changes induced in rodent germline by severalchemicals or dietary conditions the number of studies aimedat testing possible effects of lifestyle or chemical exposureon human sperm DNA methylation is extremely limited incomparison to the number of studies carried out on bloodcells Sperm can be obtained by a similarly noninvasiveprocedure they represent the target cell formale reproductiveeffects and not merely a surrogate of it their ultimate DNAmethylation pattern is acquired by amultistep process startedin PGCs and completed during the spermatogonia andspermatocyte differentiation phases [39 40] which mighttherefore be repeatedly exposed to environmental insultsFor all these reasons it would be very valuable to extendthe analysis of sperm epigenetics beyond infertility clinicalinvestigation to environmental biomonitoring studies

Focus of this literature review will be on data linkingvarious exogenous factors from specific chemical exposureto psychological stress to DNA methylation changes inthe germline and their consequences in the offspring Wehave taken into consideration both experimental rodent andhuman studies In addition due to the very limited amountof data from human biomonitoring investigations we havedecided to include a survey of papers reporting human popu-lation studies which have shown an environmental impact onDNAmethylation of somatic cells to highlight those sourcesof exposure that would be worth further germline-orientedinvestigations and the present gaps of knowledge

2 Human Studies on EnvironmentallyLinked DNA Methylation Changes inSomatic and Germ Cells

Several recent and excellent reviews [12 13 15 17 41 42]have been published on this subject Here we try to offer an












2 PM10 PM25 and O




Table1Selected

epidem

iologicalstudies

onthee

ffectso

fenviro

nmentalchemicalexpo

sureso

nhu

man

DNAmethylation

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Metals

Arsenic(A

s)

294adults

India

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[45]

64adults

India

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[46]

320adults

Bang

ladesh

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[47]

96adults

India

PBL

p16p53


PCR

Hypermethylatio

n[48]

202wom

enA

rgentin

aPB

Lp16MLH

1andLINE-1

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natp16and

MLH

1[51]

163patientsw

itharseniasisand

110controls

China

PBL

p16


PCR

Hypermethylatio

n[49]

16individu

also

fwhich

8were

with

arsenicosis

Mexico

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

npatte

rns

[50]

10individu

alsw

ithskin

lesio

nsand10

controls

Bang

ladesh

PBL

Epigenom

e-wide

Arrays

6differentially

methylated

sites

inclu

ding

RHBD

F1[53]

38patie

ntsw

ithurothelial

carcinom

aTaiwan

Tumor

biop

sies

DAP

KBisulfitePC

Rsequ

encing

Hypermethylatio

n[52]

28patie

ntsw

ithurothelial

carcinom

aTaiwan

Tumor

biop

sies

Epigenom

e-wide

Arrays

Hypermethylatio

nin

CTNNA

2KL

K7N

PY2R

ZN

F132and

KCNK17

[54]

113mother-child

pairs

Ba

ngladesh

PBL(m

aternaland

umbilicalcord

samples)

p16p53LINE-1andAlu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natp16and

LINE-1

[55]

113mother-child

pairs

Ba

ngladesh

PBL(m

aternaland

umbilicalcord

samples)

Global

LINE-1Alu

Methylincorpo

ratio

nassay

bisulfitePC

Rpyrosequ

encing

LU

MA(Lum

inom

etric

Methylatio

nAs

say)

Hypermethylatio

n(sex-dependent)

[57]

71newbo

rnsTh

ailand

PBL(cordbloo

d)Global

LINE-1

p53

Globaltotal5-m

Cby

HPL

C-MS

LINE-1CO

BRA


restric

tionendo

nucle

ase

digestion

Hypermethylatio

natp53

[58]

44newbo

rnsBa

ngladesh

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin

thou

sand

sofsites

[56]

134infantsUSA

PBL

Epigenom

e-wide

Arrays

Hypermethylatio

natseveral

loci

[59]

newbo

rnsMexico

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin

thou

sand

sofsites

[60]

Chromium

(Cr)

115workers

and60

controls

China

PBL

Global

ELISA

Hypom

ethylatio

n[61]

Mercury

(Hg)

131d

entalprofessionals

USA

Buccalmucosa

LINE-1DNMT1SEP

W1

andSE

PP1

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natSE

PP1in

males

[63]

Lead

(Pb)

517eld

erlymenU

SAPB

LLINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[64]

9expo

sedindividu

als

PBL

p16

Methylatio

n-specificP

CRand

thermaldenaturatio

nHypermethylatio

n[65]

Cadm

ium

(Cd)

202wom

enA

rgentin

aPB

LLINE-1p16andMLH

1BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[66]

17mother-child

pairs

USA

PBL(m

aternaland

newbo

rn)

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat

subsetso

fgenes

[68]

Selenium

(Se)

286adults

Bang

ladesh

PBL

Global

Methylacceptancea

ssay

Hypom

ethylatio

n[67]

HgPb

and

Cd

43wom

enun

dergoing

IVFUSA

PBL

Epigenom

e-wide

Arrays

Hghyperm

ethylatio

nat

GSTM

1Pb

hypom

ethylatio

natCO

L1A2

[62]


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Airpo

llutio

n(in

cluding

PMandPA

H)

48adultn

onsm

okersBe

lgium

PBL

Global

HPL

CHypom

ethylatio

n[70]

718eld

erlyindividu

alsUSA

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[71]

706eld

erlyindividu

alsUSA

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylation

[72]

777elderly

individu

alsUSA

PBL

F3IFN

-120574IL-6TL

R-2and

ICAM

-1BisulfitePC

Rpyrosequ

encing

F3ICA

M-1

andTL

R-2

hypo

methylatio

nIFN-120574

and

IL-6

hyperm

ethylatio

n[73]

776eld

erlyindividu

alsUSA

PBL

F3ICA

M-1

IFN-120574IL-6

TLR-2CR

ATG

CRiNOS

andOGG

1BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

nat

TLR2

GCR

TLR

2F3and

IL6

[74]

63ste

elworkersItaly

PBL

LINE-1AluiNOS

p16 p53hT

ERT

andAP

CRA

SSF1A

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natiNOS

p53andRA

SSF1A

hyperm

ethylatio

natAP

Cp16

[81ndash83]

49no

nsmok

ingcoke-oven

workersand43

controls

Poland

PBL

p16p53IL-6H

IC1

LINE-1andAlu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natLINE-1

AluandIL-6

hypo

methylatio

natp53

[84]

60truckdriversa

nd60

controls

China

PBL

Tand

emrepeatsS

at120572

NBL

2andD4Z

4BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natSat120572

and

NBL

2[85]

120malew

orkersItalyand

China

PBL

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[87]

67indu

stria

lworkers65

resid

ents

and45

ruralcon

trols

Thailand

PBL

LINE-1Alup16p53HIC1

andIL-6

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natp53IL-6

andLINE-1

[88]

78gasolin

efilling

attend

ants77

urbantraffi

cofficers57control

office

workersItaly

PBL

LINE-1Alu

p15andMAG

E1BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natLINE-1

AluandMAG

E1

hyperm

ethylatio

natp15

[89]

78gasolin

efilling

attend

ants58

controloffice

workerIta

lyPB

LGlobal

High-resolutio

nGC-

MS

Hypom

ethylatio

n[90]

158petro

chem

icalworkersand

50controloffice

workers

Bulgaria

PBL

LINE-1Alup15and

MAG

E1BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natLINE-1

andp15

[91]

141a

sthm

aticchild

renand70

controls

USA

Treg

cells

from

PBL

Foxp3

Hypermethylatio

n[75]

940child

ren

USA

Buccalcells

NOS1N

OS2A

andNOS3

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

nat

NOS2AandNOS3

[ 76]

56mother-child

pairs

USA

PBL(cordbloo

d)AC

SL3

Methylatio

n-specificP

CRHypermethylatio

n[79]

164mother-child

pairs

USA

PBL(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[78]

53mother-child

pairs

USA

PBL(cordbloo

d)IFN120574andIL-4

BisulfitePC

Rsequ

encing

Hypermethylatio

natIFN120574

[80]

POPs

70Inuits

Greenland

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[92]

86adultsSou

thKo

rea

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[93]

358mother-child

pairs

USA

PBL(cordbloo

dandat9

years)

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[98]

Bispheno

lA43

wom

enun

dergoing

IVFUSA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natthe

TSP5

0[62]

46preado

lescentg

irlsEg

ypt

Saliva

Epigenom

e-wide

Arrays

Hypom

ethylatio

natseveral

loci

[94]


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

PFASs

685adults

USA

PBL

LINE-1

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[95]

262fertile

men

Greenland

PolandUkraine

Sperm

GlobalLINE-1Aluand

119878119886119905120572

Flow

cytometry

immun

odetectio

nof

5-mC

bisulfitePC

Rpyrosequ

encing

Noconsistentchanges

[96]

30mother-child

pairsU

SAPB

L(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[97]

EDs

192mother-child

pairs

Spain

Placenta

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

AluY

b8hypo

methylatio

nin

boys

[99]

Tobaccosm

oke

177adults

Germany

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3[103]

374adults

Italy

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3AH

RRand

otherloci

[105]

261a

dultsItaly

PBL

AHRR

6p21

(1locus)

2q37

(2loci)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[111]

3588adults

Germany

PBL

F2RL

3MALD

I-TOFMS

Hypom

ethylatio

n[106]

399African

American

youths

USA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[109]

107African

American

youn

gmenU

SAPB

LEp

igenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[110]

111a

dultAfrican

American

wom

enU

SAPB

LEp

igenom

e-wide

Arrays

Differentia

lmethylatio

nat910

locihypom

ethylationat

AHRR

andGP

R15

[112]

348mother-child

pairs

USA

Child

buccalcells

LINE-1AluY

b8BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAluY

b8[113]

272mother-child

pairs

USA

Child

buccalcells

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin


nat

AXLandPT

PRO

[113]

173mother-child

pairs

USA

Child

buccalcells

AXL

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[114]


pairs

USA

Child

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat19

loci

[115]

36mother-child

pairs

(18

nonsmokersa

nd18

smokers)

USA

Placenta

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat

severalloci

[117]

1062

mother-child

pairs

Norway

PBL(cordbloo

d)Ep

igenom

e-wide

Arrays

Differentia

lmethylatio

nin

10genesincluding

AHRR

CY

P1A1

and

GFI1

[118]

418mother-child

pairs

USA

PBL(cordbloo

d)DMRs

ofIG

F2andH19

BisulfitePC

Rpyrosequ

encing

IGF2

DMRdifferential

methylatio

n[119]

380mother-child

pairs

USA

PBL(cordbloo

d)LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natAluY

b8[120]

206mother-child

pairs

USA

Placenta

Epigenom

e-wide

Arrays

Hypermethylatio

natRU

NX3

[121]

132mother-child

pairs

Canada

PBL(ado

lescents)

Epigenom

e-wide

Arrays

Hypermethylatio

natMYO

1G

hypo

methylatio

nat

CNTN

AP2

[122]







































Table2Syno

psisofpapersrepo

rtinge

ffectso

fexp

erim

entaltreatmentson


maleo

rfem

aleg

erm

cells

(whenadditio

naltissuesw

erea

nalyzedthey

arespecified)

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Flutam

ide

Rats

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

sperm

ofadult

anim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Procym

idon

eRa

tsIn

uteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

Multip

leun

specified

Methylatio

n-specific

restr

ictio

nEn

donu

clease

digestion

Alteredmethylatio

ndetected

atmultip

lesequ

encesinvolving

both

hypo

-and

hyperm

ethylatio

nevents

[159]

Vinclozolin

Mice

Inuteroexpo

sure

ipinjectio

nof

50mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Inspermhighlysig

nificantH

19andMeg3

hypo

methylatio


hyperm

ethylation


tissues

[161]

Dioxin

Mice

Inuteroexpo

sure

ipinjectio

nof

2or

10ng

kgday

betweenday9andday19

ofgesta

tion

Spermplusliver

andskele

tal

muscle

cells

inadultanimals

SnrpnPeg3and

Igf2r

BisulfitePC

Rpyrosequ

encing


nchangesin

sperminliver

andmuscle

cells

significant

increaseso

fmethylationin

Igf2r

[163]

Metho

xychlor

Mice

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

H19

and

Meg3andsig

nificantly

increasedmethylatio

nof

MestSnrpnandPeg3

inspermn

oeffectin

somatictissues

[162]

Ethano

lMice

Inuteroexpo

sure

poadministratio

nof

05g

kgday

betweenday10

andday18

ofgesta

tion

Spermplustail

liverskeletal

muscle

and

brain

cells

inadult

anim

als

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Highlysig

nificant3decrease

inthen

umbero

fmethylatedCp

Gso

fH19noeffectintheo

ther

genesa

ndin

somatictissues

[168]

Folate-deficient

diet

Mice

Inuteroexpo

sure

treatmento

fdam

swith

folate-deficient

dietfro

mtwoweeks

before

mating

throug

hout

gesta

tionandlactation

Sperm

Epigenom

e-wide

Arrays

57geno

micregion

shad

alteredmethylatio

nprofi

lesinsperm

from

males

expo

sedto

folate-deficient

dietbothhypo

-and

hyperm

ethylatio

nwereo

bservedmethylatio

ndifferences

observed

inprom

oter

region

sofgenes

implicated

indevelopm

entand

with

functio

nsin

thec

entralnervou

ssystemkidneyspleen

digestive

tractandmuscle

tissueandof

genes

associated

with

diabetesautoimmun

edise

ases


schizop

hreniaand

cancer

[154]

Und

erno

urish

ment

Mice

Inuteroexpo



gesta

tion

Sperm

Global

epigenom

e-wide


166differentially

methylatedregion

sof

which

111

wereh

ypom

ethylatedand55

hyperm

ethylatedin

undernou

rishedrelativ

etocontrolm

icethe

bisulfitepyrosequ

encing

valid

ationconfi

rmed

1724hypo

methylated

and08hyperm

ethylated

region

s

[152]

Metho

xychlor

Mice

Adultexp

osure

ipinjectio

nof

10mgkgday

for8

consecutived

ays

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

Meg3and

significantly


andPeg3

inspermn


[162]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Ethano

lMice

Adultexp

osure

poadministratio

nof

59g

kgdayfor2

9days

over

aperiodof

5weeks

Sperm

H19R

asgrf1

BisulfitePC

Rpyrosequ

encing


nchanges

[169]

Fenvalerate

Mice

Adultexp

osure

poadministratio

nof

10mgkgday

for

30days

Sperm

Epigenom

e-wide

Arrays

Sign

ificant

Hap1h

ypom

ethylatio

nsig

nificantA

ce

Foxo3aN

r3c2P

mlandPtgfrn

hyperm

ethylatio

n[172]

Sodium

fluoride

Mice

Adultexp

osure

poadministratio

nof

100m

gLin

drinking

water

for3

5days

Spermplusliver

cells

inadult

anim

als

H19R

asgrf1

Peg3

andLine-1

glob

alBisulfitePC

Rsequ

encing

EL

ISA


nchanges

[173]

Tamoxifen

Rats

Adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Igf2-H

19global

BisulfitePC

Rsequ

encing

flo

wcytometry

after

immun

ostainingwith

5-methylcytosine

antib

ody

Sign

ificantlyredu


19

glob

almethylatio

nlevelu

naffected

[171]

Tamoxifen

Rats

adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Dlk1Plagl1

Peg5

Peg3Igf2rG

rb10

Kcnq

1Ascl2

and

Cdkn1c

BisulfitePC

Rsequ

encing


nchanges

[170]

Bispheno

lARa

tsNeonatalexp

osure

5daily

subcutaneous

injections

of04m

gkgday

BPAsta

rtingon

eday

after

birth

Sperm

Igf2-H

19BisulfitePC

Rsequ

encing

Sign

ificant

hypo

methylationattheH

19ICR

[166]

Particulatea

irpo

llutio

nMice

Adultexp

osure

3or

10weeks

ofexpo

sure

toam

bientair

inpo

llutedsites

Sperm

samplingeither

immediatelyor

6weeks

after

thee

ndof

10-w

eekexpo

sure

Sperm

Global

Cytosin

eextensio

nassay

andmethylacceptance

assay

Sign


almethylationin

10-w

eekexpo

sedsamplesw

hich

persisted

after

expo

sure

interrup

tion

methylationchanges

abolish

edby

useo

fairfilters

[167]

High-fatd

iet

Mice

Adultexp

osure

10-w

eekexpo

sure

tohigh

-fatd

ietfrom

5weeks

ofage

Testisc

ells

elong

ated

spermatids

Global

ELISAsem

iquantitativ

eim

mun

ohistochemistry

oftestissectio

nswith

anti-5-mCantib

ody

Abou

t25

redu

ctionin

glob

almethylationin

both

who

letesticularc

ellsandspermatids

[149]

High-fatd

ietp

lus

streptozotocin

subd

iabetogenic

treatment

Mice

Adultexp

osure

13-w

eekexpo

sure

tohigh

-fatd

ietfro

m3weeks

ofageplus

streptozotocinip

injectionat12

weeks

ofage

Sperm

Epigenom

e-wide

Arrays


lteredoverallm

ethylome

patte

rnsinspermw

ithalarge

portionof

differentially

methylated

geneso

verla

ppingwith

thatof


sprin

g[156]

Low-protein

diet

Mice

Adultexp

osure

9-weekexpo

sure

tolow-protein

diet

from

3weeks

ofage

Sperm

119875119901119886119903120572

epigenom

e-wide

BisulfitePC

Rsequ

encing

arrays

Noeffectsof


nin

sperm

overallsperm

cytosin

emethylationpatte

rnsw

ere

largely

conservedun

derv

arious

dietaryregimes

[153]

Olfactoryfear

cond

ition

ing

Mice

Adultexp

osuretoacetop

heno

neSperm

Olfr151

BisulfitePC

Rsequ

encing

Hypom

ethylation

[175]

Streptozotocin

diabetogenic

treatment

Mice

Adultexp

osure

singleipinjectio

nof

230m

gkg

streptozotocin

1525or

35days

before

oocytecollectionaft

ersuperovulation

Oocytes

H19Peg3and

Snrpn

COBR

A

Evidentd

emethylationwas

observed

inthe

methylatio

npatte

rnof

Peg3

DMRon

day35

after

treatmentthem

ethylatio

npatte

rnso

fH19

and

SnrpnDMRs

weren

otsig

nificantly

alteredby

maternald

iabetes

[157]

High-fatd

iet

Mice

Adultexp

osure

12weeks

offeedingwith

high

-fatd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

H19M

estPeg3

Igf2rSnrpnPp

ar120572

andLep

COBR

A

DNAmethylationof

imprintedgenesw

asno

talteredtheP

par120572

methylatio

nlevelw

assig

nificantly

decreasedandtheL

epmethylatio

nlevelw

assig

nificantly

increasedin

high

-fatd

iet

fedmicec

omparedwith

controlm

ice

[158]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Zinc-deficientd

iet

Mice

Adultexp

osure

5days

offeedingwith

zinc-deficientd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

Global

Immun

ocytochemistry

with

anti-5-mCantib

ody

DNAmethylatio

nwas

redu

cedto

abou

t60


ocytes

[155]

Bispheno

lAMice

Neonatalexp

osure

20or

40120583gkg

bw

either

bydaily

hypo

derm

alinjections

from

postn

atal

day7to

postn

atalday14

orby

intraperito

nealinjections

administered

each

fifthdaybetweenpo

stnataldays

5and20prio

rtocollectionof

ovarian

oocytes

Oocytes

H19Igf2rand

Peg3

BisulfitePC

Rsequ

encing

Sign

ificant

dose-dependent

redu

ctionof

methylatio

nin

Igf2rPeg3

genesno

effecto

nH19

[164

]

Bispheno

lAMice

Invitro

expo

sure

to3or

300n

Mdu

ring

12days

offollicle

cultu

refro

mpreantral

toantralsta

geOocytes

H19M

estIgf2r

andSnrpn

BisulfitePC

Rpyrosequ

encing

Sign


natthelow

but

notatthe

high

BPA

doseinMestIgf2rand

Snrpngenesno

effecto

nH19

[165]















4 Discussion


















Abbreviations






























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of












2 PM10 PM25 and O




Table1Selected

epidem

iologicalstudies

onthee

ffectso

fenviro

nmentalchemicalexpo

sureso

nhu

man

DNAmethylation

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Metals

Arsenic(A

s)

294adults

India

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[45]

64adults

India

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[46]

320adults

Bang

ladesh

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[47]

96adults

India

PBL

p16p53


PCR

Hypermethylatio

n[48]

202wom

enA

rgentin

aPB

Lp16MLH

1andLINE-1

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natp16and

MLH

1[51]

163patientsw

itharseniasisand

110controls

China

PBL

p16


PCR

Hypermethylatio

n[49]

16individu

also

fwhich

8were

with

arsenicosis

Mexico

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

npatte

rns

[50]

10individu

alsw

ithskin

lesio

nsand10

controls

Bang

ladesh

PBL

Epigenom

e-wide

Arrays

6differentially

methylated

sites

inclu

ding

RHBD

F1[53]

38patie

ntsw

ithurothelial

carcinom

aTaiwan

Tumor

biop

sies

DAP

KBisulfitePC

Rsequ

encing

Hypermethylatio

n[52]

28patie

ntsw

ithurothelial

carcinom

aTaiwan

Tumor

biop

sies

Epigenom

e-wide

Arrays

Hypermethylatio

nin

CTNNA

2KL

K7N

PY2R

ZN

F132and

KCNK17

[54]

113mother-child

pairs

Ba

ngladesh

PBL(m

aternaland

umbilicalcord

samples)

p16p53LINE-1andAlu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natp16and

LINE-1

[55]

113mother-child

pairs

Ba

ngladesh

PBL(m

aternaland

umbilicalcord

samples)

Global

LINE-1Alu

Methylincorpo

ratio

nassay

bisulfitePC

Rpyrosequ

encing

LU

MA(Lum

inom

etric

Methylatio

nAs

say)

Hypermethylatio

n(sex-dependent)

[57]

71newbo

rnsTh

ailand

PBL(cordbloo

d)Global

LINE-1

p53

Globaltotal5-m

Cby

HPL

C-MS

LINE-1CO

BRA


restric

tionendo

nucle

ase

digestion

Hypermethylatio

natp53

[58]

44newbo

rnsBa

ngladesh

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin

thou

sand

sofsites

[56]

134infantsUSA

PBL

Epigenom

e-wide

Arrays

Hypermethylatio

natseveral

loci

[59]

newbo

rnsMexico

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin

thou

sand

sofsites

[60]

Chromium

(Cr)

115workers

and60

controls

China

PBL

Global

ELISA

Hypom

ethylatio

n[61]

Mercury

(Hg)

131d

entalprofessionals

USA

Buccalmucosa

LINE-1DNMT1SEP

W1

andSE

PP1

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natSE

PP1in

males

[63]

Lead

(Pb)

517eld

erlymenU

SAPB

LLINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[64]

9expo

sedindividu

als

PBL

p16

Methylatio

n-specificP

CRand

thermaldenaturatio

nHypermethylatio

n[65]

Cadm

ium

(Cd)

202wom

enA

rgentin

aPB

LLINE-1p16andMLH

1BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[66]

17mother-child

pairs

USA

PBL(m

aternaland

newbo

rn)

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat

subsetso

fgenes

[68]

Selenium

(Se)

286adults

Bang

ladesh

PBL

Global

Methylacceptancea

ssay

Hypom

ethylatio

n[67]

HgPb

and

Cd

43wom

enun

dergoing

IVFUSA

PBL

Epigenom

e-wide

Arrays

Hghyperm

ethylatio

nat

GSTM

1Pb

hypom

ethylatio

natCO

L1A2

[62]


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Airpo

llutio

n(in

cluding

PMandPA

H)

48adultn

onsm

okersBe

lgium

PBL

Global

HPL

CHypom

ethylatio

n[70]

718eld

erlyindividu

alsUSA

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[71]

706eld

erlyindividu

alsUSA

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylation

[72]

777elderly

individu

alsUSA

PBL

F3IFN

-120574IL-6TL

R-2and

ICAM

-1BisulfitePC

Rpyrosequ

encing

F3ICA

M-1

andTL

R-2

hypo

methylatio

nIFN-120574

and

IL-6

hyperm

ethylatio

n[73]

776eld

erlyindividu

alsUSA

PBL

F3ICA

M-1

IFN-120574IL-6

TLR-2CR

ATG

CRiNOS

andOGG

1BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

nat

TLR2

GCR

TLR

2F3and

IL6

[74]

63ste

elworkersItaly

PBL

LINE-1AluiNOS

p16 p53hT

ERT

andAP

CRA

SSF1A

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natiNOS

p53andRA

SSF1A

hyperm

ethylatio

natAP

Cp16

[81ndash83]

49no

nsmok

ingcoke-oven

workersand43

controls

Poland

PBL

p16p53IL-6H

IC1

LINE-1andAlu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natLINE-1

AluandIL-6

hypo

methylatio

natp53

[84]

60truckdriversa

nd60

controls

China

PBL

Tand

emrepeatsS

at120572

NBL

2andD4Z

4BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natSat120572

and

NBL

2[85]

120malew

orkersItalyand

China

PBL

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[87]

67indu

stria

lworkers65

resid

ents

and45

ruralcon

trols

Thailand

PBL

LINE-1Alup16p53HIC1

andIL-6

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natp53IL-6

andLINE-1

[88]

78gasolin

efilling

attend

ants77

urbantraffi

cofficers57control

office

workersItaly

PBL

LINE-1Alu

p15andMAG

E1BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natLINE-1

AluandMAG

E1

hyperm

ethylatio

natp15

[89]

78gasolin

efilling

attend

ants58

controloffice

workerIta

lyPB

LGlobal

High-resolutio

nGC-

MS

Hypom

ethylatio

n[90]

158petro

chem

icalworkersand

50controloffice

workers

Bulgaria

PBL

LINE-1Alup15and

MAG

E1BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natLINE-1

andp15

[91]

141a

sthm

aticchild

renand70

controls

USA

Treg

cells

from

PBL

Foxp3

Hypermethylatio

n[75]

940child

ren

USA

Buccalcells

NOS1N

OS2A

andNOS3

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

nat

NOS2AandNOS3

[ 76]

56mother-child

pairs

USA

PBL(cordbloo

d)AC

SL3

Methylatio

n-specificP

CRHypermethylatio

n[79]

164mother-child

pairs

USA

PBL(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[78]

53mother-child

pairs

USA

PBL(cordbloo

d)IFN120574andIL-4

BisulfitePC

Rsequ

encing

Hypermethylatio

natIFN120574

[80]

POPs

70Inuits

Greenland

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[92]

86adultsSou

thKo

rea

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[93]

358mother-child

pairs

USA

PBL(cordbloo

dandat9

years)

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[98]

Bispheno

lA43

wom

enun

dergoing

IVFUSA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natthe

TSP5

0[62]

46preado

lescentg

irlsEg

ypt

Saliva

Epigenom

e-wide

Arrays

Hypom

ethylatio

natseveral

loci

[94]


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

PFASs

685adults

USA

PBL

LINE-1

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[95]

262fertile

men

Greenland

PolandUkraine

Sperm

GlobalLINE-1Aluand

119878119886119905120572

Flow

cytometry

immun

odetectio

nof

5-mC

bisulfitePC

Rpyrosequ

encing

Noconsistentchanges

[96]

30mother-child

pairsU

SAPB

L(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[97]

EDs

192mother-child

pairs

Spain

Placenta

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

AluY

b8hypo

methylatio

nin

boys

[99]

Tobaccosm

oke

177adults

Germany

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3[103]

374adults

Italy

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3AH

RRand

otherloci

[105]

261a

dultsItaly

PBL

AHRR

6p21

(1locus)

2q37

(2loci)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[111]

3588adults

Germany

PBL

F2RL

3MALD

I-TOFMS

Hypom

ethylatio

n[106]

399African

American

youths

USA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[109]

107African

American

youn

gmenU

SAPB

LEp

igenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[110]

111a

dultAfrican

American

wom

enU

SAPB

LEp

igenom

e-wide

Arrays

Differentia

lmethylatio

nat910

locihypom

ethylationat

AHRR

andGP

R15

[112]

348mother-child

pairs

USA

Child

buccalcells

LINE-1AluY

b8BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAluY

b8[113]

272mother-child

pairs

USA

Child

buccalcells

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin


nat

AXLandPT

PRO

[113]

173mother-child

pairs

USA

Child

buccalcells

AXL

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[114]


pairs

USA

Child

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat19

loci

[115]

36mother-child

pairs

(18

nonsmokersa

nd18

smokers)

USA

Placenta

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat

severalloci

[117]

1062

mother-child

pairs

Norway

PBL(cordbloo

d)Ep

igenom

e-wide

Arrays

Differentia

lmethylatio

nin

10genesincluding

AHRR

CY

P1A1

and

GFI1

[118]

418mother-child

pairs

USA

PBL(cordbloo

d)DMRs

ofIG

F2andH19

BisulfitePC

Rpyrosequ

encing

IGF2

DMRdifferential

methylatio

n[119]

380mother-child

pairs

USA

PBL(cordbloo

d)LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natAluY

b8[120]

206mother-child

pairs

USA

Placenta

Epigenom

e-wide

Arrays

Hypermethylatio

natRU

NX3

[121]

132mother-child

pairs

Canada

PBL(ado

lescents)

Epigenom

e-wide

Arrays

Hypermethylatio

natMYO

1G

hypo

methylatio

nat

CNTN

AP2

[122]







































Table2Syno

psisofpapersrepo

rtinge

ffectso

fexp

erim

entaltreatmentson


maleo

rfem

aleg

erm

cells

(whenadditio

naltissuesw

erea

nalyzedthey

arespecified)

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Flutam

ide

Rats

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

sperm

ofadult

anim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Procym

idon

eRa

tsIn

uteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

Multip

leun

specified

Methylatio

n-specific

restr

ictio

nEn

donu

clease

digestion

Alteredmethylatio

ndetected

atmultip

lesequ

encesinvolving

both

hypo

-and

hyperm

ethylatio

nevents

[159]

Vinclozolin

Mice

Inuteroexpo

sure

ipinjectio

nof

50mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Inspermhighlysig

nificantH

19andMeg3

hypo

methylatio


hyperm

ethylation


tissues

[161]

Dioxin

Mice

Inuteroexpo

sure

ipinjectio

nof

2or

10ng

kgday

betweenday9andday19

ofgesta

tion

Spermplusliver

andskele

tal

muscle

cells

inadultanimals

SnrpnPeg3and

Igf2r

BisulfitePC

Rpyrosequ

encing


nchangesin

sperminliver

andmuscle

cells

significant

increaseso

fmethylationin

Igf2r

[163]

Metho

xychlor

Mice

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

H19

and

Meg3andsig

nificantly

increasedmethylatio

nof

MestSnrpnandPeg3

inspermn

oeffectin

somatictissues

[162]

Ethano

lMice

Inuteroexpo

sure

poadministratio

nof

05g

kgday

betweenday10

andday18

ofgesta

tion

Spermplustail

liverskeletal

muscle

and

brain

cells

inadult

anim

als

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Highlysig

nificant3decrease

inthen

umbero

fmethylatedCp

Gso

fH19noeffectintheo

ther

genesa

ndin

somatictissues

[168]

Folate-deficient

diet

Mice

Inuteroexpo

sure

treatmento

fdam

swith

folate-deficient

dietfro

mtwoweeks

before

mating

throug

hout

gesta

tionandlactation

Sperm

Epigenom

e-wide

Arrays

57geno

micregion

shad

alteredmethylatio

nprofi

lesinsperm

from

males

expo

sedto

folate-deficient

dietbothhypo

-and

hyperm

ethylatio

nwereo

bservedmethylatio

ndifferences

observed

inprom

oter

region

sofgenes

implicated

indevelopm

entand

with

functio

nsin

thec

entralnervou

ssystemkidneyspleen

digestive

tractandmuscle

tissueandof

genes

associated

with

diabetesautoimmun

edise

ases


schizop

hreniaand

cancer

[154]

Und

erno

urish

ment

Mice

Inuteroexpo



gesta

tion

Sperm

Global

epigenom

e-wide


166differentially

methylatedregion

sof

which

111

wereh

ypom

ethylatedand55

hyperm

ethylatedin

undernou

rishedrelativ

etocontrolm

icethe

bisulfitepyrosequ

encing

valid

ationconfi

rmed

1724hypo

methylated

and08hyperm

ethylated

region

s

[152]

Metho

xychlor

Mice

Adultexp

osure

ipinjectio

nof

10mgkgday

for8

consecutived

ays

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

Meg3and

significantly


andPeg3

inspermn


[162]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Ethano

lMice

Adultexp

osure

poadministratio

nof

59g

kgdayfor2

9days

over

aperiodof

5weeks

Sperm

H19R

asgrf1

BisulfitePC

Rpyrosequ

encing


nchanges

[169]

Fenvalerate

Mice

Adultexp

osure

poadministratio

nof

10mgkgday

for

30days

Sperm

Epigenom

e-wide

Arrays

Sign

ificant

Hap1h

ypom

ethylatio

nsig

nificantA

ce

Foxo3aN

r3c2P

mlandPtgfrn

hyperm

ethylatio

n[172]

Sodium

fluoride

Mice

Adultexp

osure

poadministratio

nof

100m

gLin

drinking

water

for3

5days

Spermplusliver

cells

inadult

anim

als

H19R

asgrf1

Peg3

andLine-1

glob

alBisulfitePC

Rsequ

encing

EL

ISA


nchanges

[173]

Tamoxifen

Rats

Adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Igf2-H

19global

BisulfitePC

Rsequ

encing

flo

wcytometry

after

immun

ostainingwith

5-methylcytosine

antib

ody

Sign

ificantlyredu


19

glob

almethylatio

nlevelu

naffected

[171]

Tamoxifen

Rats

adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Dlk1Plagl1

Peg5

Peg3Igf2rG

rb10

Kcnq

1Ascl2

and

Cdkn1c

BisulfitePC

Rsequ

encing


nchanges

[170]

Bispheno

lARa

tsNeonatalexp

osure

5daily

subcutaneous

injections

of04m

gkgday

BPAsta

rtingon

eday

after

birth

Sperm

Igf2-H

19BisulfitePC

Rsequ

encing

Sign

ificant

hypo

methylationattheH

19ICR

[166]

Particulatea

irpo

llutio

nMice

Adultexp

osure

3or

10weeks

ofexpo

sure

toam

bientair

inpo

llutedsites

Sperm

samplingeither

immediatelyor

6weeks

after

thee

ndof

10-w

eekexpo

sure

Sperm

Global

Cytosin

eextensio

nassay

andmethylacceptance

assay

Sign


almethylationin

10-w

eekexpo

sedsamplesw

hich

persisted

after

expo

sure

interrup

tion

methylationchanges

abolish

edby

useo

fairfilters

[167]

High-fatd

iet

Mice

Adultexp

osure

10-w

eekexpo

sure

tohigh

-fatd

ietfrom

5weeks

ofage

Testisc

ells

elong

ated

spermatids

Global

ELISAsem

iquantitativ

eim

mun

ohistochemistry

oftestissectio

nswith

anti-5-mCantib

ody

Abou

t25

redu

ctionin

glob

almethylationin

both

who

letesticularc

ellsandspermatids

[149]

High-fatd

ietp

lus

streptozotocin

subd

iabetogenic

treatment

Mice

Adultexp

osure

13-w

eekexpo

sure

tohigh

-fatd

ietfro

m3weeks

ofageplus

streptozotocinip

injectionat12

weeks

ofage

Sperm

Epigenom

e-wide

Arrays


lteredoverallm

ethylome

patte

rnsinspermw

ithalarge

portionof

differentially

methylated

geneso

verla

ppingwith

thatof


sprin

g[156]

Low-protein

diet

Mice

Adultexp

osure

9-weekexpo

sure

tolow-protein

diet

from

3weeks

ofage

Sperm

119875119901119886119903120572

epigenom

e-wide

BisulfitePC

Rsequ

encing

arrays

Noeffectsof


nin

sperm

overallsperm

cytosin

emethylationpatte

rnsw

ere

largely

conservedun

derv

arious

dietaryregimes

[153]

Olfactoryfear

cond

ition

ing

Mice

Adultexp

osuretoacetop

heno

neSperm

Olfr151

BisulfitePC

Rsequ

encing

Hypom

ethylation

[175]

Streptozotocin

diabetogenic

treatment

Mice

Adultexp

osure

singleipinjectio

nof

230m

gkg

streptozotocin

1525or

35days

before

oocytecollectionaft

ersuperovulation

Oocytes

H19Peg3and

Snrpn

COBR

A

Evidentd

emethylationwas

observed

inthe

methylatio

npatte

rnof

Peg3

DMRon

day35

after

treatmentthem

ethylatio

npatte

rnso

fH19

and

SnrpnDMRs

weren

otsig

nificantly

alteredby

maternald

iabetes

[157]

High-fatd

iet

Mice

Adultexp

osure

12weeks

offeedingwith

high

-fatd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

H19M

estPeg3

Igf2rSnrpnPp

ar120572

andLep

COBR

A

DNAmethylationof

imprintedgenesw

asno

talteredtheP

par120572

methylatio

nlevelw

assig

nificantly

decreasedandtheL

epmethylatio

nlevelw

assig

nificantly

increasedin

high

-fatd

iet

fedmicec

omparedwith

controlm

ice

[158]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Zinc-deficientd

iet

Mice

Adultexp

osure

5days

offeedingwith

zinc-deficientd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

Global

Immun

ocytochemistry

with

anti-5-mCantib

ody

DNAmethylatio

nwas

redu

cedto

abou

t60


ocytes

[155]

Bispheno

lAMice

Neonatalexp

osure

20or

40120583gkg

bw

either

bydaily

hypo

derm

alinjections

from

postn

atal

day7to

postn

atalday14

orby

intraperito

nealinjections

administered

each

fifthdaybetweenpo

stnataldays

5and20prio

rtocollectionof

ovarian

oocytes

Oocytes

H19Igf2rand

Peg3

BisulfitePC

Rsequ

encing

Sign

ificant

dose-dependent

redu

ctionof

methylatio

nin

Igf2rPeg3

genesno

effecto

nH19

[164

]

Bispheno

lAMice

Invitro

expo

sure

to3or

300n

Mdu

ring

12days

offollicle

cultu

refro

mpreantral

toantralsta

geOocytes

H19M

estIgf2r

andSnrpn

BisulfitePC

Rpyrosequ

encing

Sign


natthelow

but

notatthe

high

BPA

doseinMestIgf2rand

Snrpngenesno

effecto

nH19

[165]















4 Discussion


















Abbreviations






























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


Table1Selected

epidem

iologicalstudies

onthee

ffectso

fenviro

nmentalchemicalexpo

sureso

nhu

man

DNAmethylation

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Metals

Arsenic(A

s)

294adults

India

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[45]

64adults

India

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[46]

320adults

Bang

ladesh

PBL

Global

Methylacceptancea

ssay

Hypermethylation

[47]

96adults

India

PBL

p16p53


PCR

Hypermethylatio

n[48]

202wom

enA

rgentin

aPB

Lp16MLH

1andLINE-1

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natp16and

MLH

1[51]

163patientsw

itharseniasisand

110controls

China

PBL

p16


PCR

Hypermethylatio

n[49]

16individu

also

fwhich

8were

with

arsenicosis

Mexico

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

npatte

rns

[50]

10individu

alsw

ithskin

lesio

nsand10

controls

Bang

ladesh

PBL

Epigenom

e-wide

Arrays

6differentially

methylated

sites

inclu

ding

RHBD

F1[53]

38patie

ntsw

ithurothelial

carcinom

aTaiwan

Tumor

biop

sies

DAP

KBisulfitePC

Rsequ

encing

Hypermethylatio

n[52]

28patie

ntsw

ithurothelial

carcinom

aTaiwan

Tumor

biop

sies

Epigenom

e-wide

Arrays

Hypermethylatio

nin

CTNNA

2KL

K7N

PY2R

ZN

F132and

KCNK17

[54]

113mother-child

pairs

Ba

ngladesh

PBL(m

aternaland

umbilicalcord

samples)

p16p53LINE-1andAlu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natp16and

LINE-1

[55]

113mother-child

pairs

Ba

ngladesh

PBL(m

aternaland

umbilicalcord

samples)

Global

LINE-1Alu

Methylincorpo

ratio

nassay

bisulfitePC

Rpyrosequ

encing

LU

MA(Lum

inom

etric

Methylatio

nAs

say)

Hypermethylatio

n(sex-dependent)

[57]

71newbo

rnsTh

ailand

PBL(cordbloo

d)Global

LINE-1

p53

Globaltotal5-m

Cby

HPL

C-MS

LINE-1CO

BRA


restric

tionendo

nucle

ase

digestion

Hypermethylatio

natp53

[58]

44newbo

rnsBa

ngladesh

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin

thou

sand

sofsites

[56]

134infantsUSA

PBL

Epigenom

e-wide

Arrays

Hypermethylatio

natseveral

loci

[59]

newbo

rnsMexico

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin

thou

sand

sofsites

[60]

Chromium

(Cr)

115workers

and60

controls

China

PBL

Global

ELISA

Hypom

ethylatio

n[61]

Mercury

(Hg)

131d

entalprofessionals

USA

Buccalmucosa

LINE-1DNMT1SEP

W1

andSE

PP1

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natSE

PP1in

males

[63]

Lead

(Pb)

517eld

erlymenU

SAPB

LLINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[64]

9expo

sedindividu

als

PBL

p16

Methylatio

n-specificP

CRand

thermaldenaturatio

nHypermethylatio

n[65]

Cadm

ium

(Cd)

202wom

enA

rgentin

aPB

LLINE-1p16andMLH

1BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[66]

17mother-child

pairs

USA

PBL(m

aternaland

newbo

rn)

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat

subsetso

fgenes

[68]

Selenium

(Se)

286adults

Bang

ladesh

PBL

Global

Methylacceptancea

ssay

Hypom

ethylatio

n[67]

HgPb

and

Cd

43wom

enun

dergoing

IVFUSA

PBL

Epigenom

e-wide

Arrays

Hghyperm

ethylatio

nat

GSTM

1Pb

hypom

ethylatio

natCO

L1A2

[62]


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Airpo

llutio

n(in

cluding

PMandPA

H)

48adultn

onsm

okersBe

lgium

PBL

Global

HPL

CHypom

ethylatio

n[70]

718eld

erlyindividu

alsUSA

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[71]

706eld

erlyindividu

alsUSA

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylation

[72]

777elderly

individu

alsUSA

PBL

F3IFN

-120574IL-6TL

R-2and

ICAM

-1BisulfitePC

Rpyrosequ

encing

F3ICA

M-1

andTL

R-2

hypo

methylatio

nIFN-120574

and

IL-6

hyperm

ethylatio

n[73]

776eld

erlyindividu

alsUSA

PBL

F3ICA

M-1

IFN-120574IL-6

TLR-2CR

ATG

CRiNOS

andOGG

1BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

nat

TLR2

GCR

TLR

2F3and

IL6

[74]

63ste

elworkersItaly

PBL

LINE-1AluiNOS

p16 p53hT

ERT

andAP

CRA

SSF1A

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natiNOS

p53andRA

SSF1A

hyperm

ethylatio

natAP

Cp16

[81ndash83]

49no

nsmok

ingcoke-oven

workersand43

controls

Poland

PBL

p16p53IL-6H

IC1

LINE-1andAlu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natLINE-1

AluandIL-6

hypo

methylatio

natp53

[84]

60truckdriversa

nd60

controls

China

PBL

Tand

emrepeatsS

at120572

NBL

2andD4Z

4BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natSat120572

and

NBL

2[85]

120malew

orkersItalyand

China

PBL

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[87]

67indu

stria

lworkers65

resid

ents

and45

ruralcon

trols

Thailand

PBL

LINE-1Alup16p53HIC1

andIL-6

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natp53IL-6

andLINE-1

[88]

78gasolin

efilling

attend

ants77

urbantraffi

cofficers57control

office

workersItaly

PBL

LINE-1Alu

p15andMAG

E1BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natLINE-1

AluandMAG

E1

hyperm

ethylatio

natp15

[89]

78gasolin

efilling

attend

ants58

controloffice

workerIta

lyPB

LGlobal

High-resolutio

nGC-

MS

Hypom

ethylatio

n[90]

158petro

chem

icalworkersand

50controloffice

workers

Bulgaria

PBL

LINE-1Alup15and

MAG

E1BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natLINE-1

andp15

[91]

141a

sthm

aticchild

renand70

controls

USA

Treg

cells

from

PBL

Foxp3

Hypermethylatio

n[75]

940child

ren

USA

Buccalcells

NOS1N

OS2A

andNOS3

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

nat

NOS2AandNOS3

[ 76]

56mother-child

pairs

USA

PBL(cordbloo

d)AC

SL3

Methylatio

n-specificP

CRHypermethylatio

n[79]

164mother-child

pairs

USA

PBL(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[78]

53mother-child

pairs

USA

PBL(cordbloo

d)IFN120574andIL-4

BisulfitePC

Rsequ

encing

Hypermethylatio

natIFN120574

[80]

POPs

70Inuits

Greenland

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[92]

86adultsSou

thKo

rea

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[93]

358mother-child

pairs

USA

PBL(cordbloo

dandat9

years)

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[98]

Bispheno

lA43

wom

enun

dergoing

IVFUSA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natthe

TSP5

0[62]

46preado

lescentg

irlsEg

ypt

Saliva

Epigenom

e-wide

Arrays

Hypom

ethylatio

natseveral

loci

[94]


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

PFASs

685adults

USA

PBL

LINE-1

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[95]

262fertile

men

Greenland

PolandUkraine

Sperm

GlobalLINE-1Aluand

119878119886119905120572

Flow

cytometry

immun

odetectio

nof

5-mC

bisulfitePC

Rpyrosequ

encing

Noconsistentchanges

[96]

30mother-child

pairsU

SAPB

L(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[97]

EDs

192mother-child

pairs

Spain

Placenta

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

AluY

b8hypo

methylatio

nin

boys

[99]

Tobaccosm

oke

177adults

Germany

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3[103]

374adults

Italy

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3AH

RRand

otherloci

[105]

261a

dultsItaly

PBL

AHRR

6p21

(1locus)

2q37

(2loci)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[111]

3588adults

Germany

PBL

F2RL

3MALD

I-TOFMS

Hypom

ethylatio

n[106]

399African

American

youths

USA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[109]

107African

American

youn

gmenU

SAPB

LEp

igenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[110]

111a

dultAfrican

American

wom

enU

SAPB

LEp

igenom

e-wide

Arrays

Differentia

lmethylatio

nat910

locihypom

ethylationat

AHRR

andGP

R15

[112]

348mother-child

pairs

USA

Child

buccalcells

LINE-1AluY

b8BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAluY

b8[113]

272mother-child

pairs

USA

Child

buccalcells

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin


nat

AXLandPT

PRO

[113]

173mother-child

pairs

USA

Child

buccalcells

AXL

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[114]


pairs

USA

Child

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat19

loci

[115]

36mother-child

pairs

(18

nonsmokersa

nd18

smokers)

USA

Placenta

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat

severalloci

[117]

1062

mother-child

pairs

Norway

PBL(cordbloo

d)Ep

igenom

e-wide

Arrays

Differentia

lmethylatio

nin

10genesincluding

AHRR

CY

P1A1

and

GFI1

[118]

418mother-child

pairs

USA

PBL(cordbloo

d)DMRs

ofIG

F2andH19

BisulfitePC

Rpyrosequ

encing

IGF2

DMRdifferential

methylatio

n[119]

380mother-child

pairs

USA

PBL(cordbloo

d)LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natAluY

b8[120]

206mother-child

pairs

USA

Placenta

Epigenom

e-wide

Arrays

Hypermethylatio

natRU

NX3

[121]

132mother-child

pairs

Canada

PBL(ado

lescents)

Epigenom

e-wide

Arrays

Hypermethylatio

natMYO

1G

hypo

methylatio

nat

CNTN

AP2

[122]







































Table2Syno

psisofpapersrepo

rtinge

ffectso

fexp

erim

entaltreatmentson


maleo

rfem

aleg

erm

cells

(whenadditio

naltissuesw

erea

nalyzedthey

arespecified)

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Flutam

ide

Rats

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

sperm

ofadult

anim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Procym

idon

eRa

tsIn

uteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

Multip

leun

specified

Methylatio

n-specific

restr

ictio

nEn

donu

clease

digestion

Alteredmethylatio

ndetected

atmultip

lesequ

encesinvolving

both

hypo

-and

hyperm

ethylatio

nevents

[159]

Vinclozolin

Mice

Inuteroexpo

sure

ipinjectio

nof

50mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Inspermhighlysig

nificantH

19andMeg3

hypo

methylatio


hyperm

ethylation


tissues

[161]

Dioxin

Mice

Inuteroexpo

sure

ipinjectio

nof

2or

10ng

kgday

betweenday9andday19

ofgesta

tion

Spermplusliver

andskele

tal

muscle

cells

inadultanimals

SnrpnPeg3and

Igf2r

BisulfitePC

Rpyrosequ

encing


nchangesin

sperminliver

andmuscle

cells

significant

increaseso

fmethylationin

Igf2r

[163]

Metho

xychlor

Mice

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

H19

and

Meg3andsig

nificantly

increasedmethylatio

nof

MestSnrpnandPeg3

inspermn

oeffectin

somatictissues

[162]

Ethano

lMice

Inuteroexpo

sure

poadministratio

nof

05g

kgday

betweenday10

andday18

ofgesta

tion

Spermplustail

liverskeletal

muscle

and

brain

cells

inadult

anim

als

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Highlysig

nificant3decrease

inthen

umbero

fmethylatedCp

Gso

fH19noeffectintheo

ther

genesa

ndin

somatictissues

[168]

Folate-deficient

diet

Mice

Inuteroexpo

sure

treatmento

fdam

swith

folate-deficient

dietfro

mtwoweeks

before

mating

throug

hout

gesta

tionandlactation

Sperm

Epigenom

e-wide

Arrays

57geno

micregion

shad

alteredmethylatio

nprofi

lesinsperm

from

males

expo

sedto

folate-deficient

dietbothhypo

-and

hyperm

ethylatio

nwereo

bservedmethylatio

ndifferences

observed

inprom

oter

region

sofgenes

implicated

indevelopm

entand

with

functio

nsin

thec

entralnervou

ssystemkidneyspleen

digestive

tractandmuscle

tissueandof

genes

associated

with

diabetesautoimmun

edise

ases


schizop

hreniaand

cancer

[154]

Und

erno

urish

ment

Mice

Inuteroexpo



gesta

tion

Sperm

Global

epigenom

e-wide


166differentially

methylatedregion

sof

which

111

wereh

ypom

ethylatedand55

hyperm

ethylatedin

undernou

rishedrelativ

etocontrolm

icethe

bisulfitepyrosequ

encing

valid

ationconfi

rmed

1724hypo

methylated

and08hyperm

ethylated

region

s

[152]

Metho

xychlor

Mice

Adultexp

osure

ipinjectio

nof

10mgkgday

for8

consecutived

ays

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

Meg3and

significantly


andPeg3

inspermn


[162]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Ethano

lMice

Adultexp

osure

poadministratio

nof

59g

kgdayfor2

9days

over

aperiodof

5weeks

Sperm

H19R

asgrf1

BisulfitePC

Rpyrosequ

encing


nchanges

[169]

Fenvalerate

Mice

Adultexp

osure

poadministratio

nof

10mgkgday

for

30days

Sperm

Epigenom

e-wide

Arrays

Sign

ificant

Hap1h

ypom

ethylatio

nsig

nificantA

ce

Foxo3aN

r3c2P

mlandPtgfrn

hyperm

ethylatio

n[172]

Sodium

fluoride

Mice

Adultexp

osure

poadministratio

nof

100m

gLin

drinking

water

for3

5days

Spermplusliver

cells

inadult

anim

als

H19R

asgrf1

Peg3

andLine-1

glob

alBisulfitePC

Rsequ

encing

EL

ISA


nchanges

[173]

Tamoxifen

Rats

Adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Igf2-H

19global

BisulfitePC

Rsequ

encing

flo

wcytometry

after

immun

ostainingwith

5-methylcytosine

antib

ody

Sign

ificantlyredu


19

glob

almethylatio

nlevelu

naffected

[171]

Tamoxifen

Rats

adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Dlk1Plagl1

Peg5

Peg3Igf2rG

rb10

Kcnq

1Ascl2

and

Cdkn1c

BisulfitePC

Rsequ

encing


nchanges

[170]

Bispheno

lARa

tsNeonatalexp

osure

5daily

subcutaneous

injections

of04m

gkgday

BPAsta

rtingon

eday

after

birth

Sperm

Igf2-H

19BisulfitePC

Rsequ

encing

Sign

ificant

hypo

methylationattheH

19ICR

[166]

Particulatea

irpo

llutio

nMice

Adultexp

osure

3or

10weeks

ofexpo

sure

toam

bientair

inpo

llutedsites

Sperm

samplingeither

immediatelyor

6weeks

after

thee

ndof

10-w

eekexpo

sure

Sperm

Global

Cytosin

eextensio

nassay

andmethylacceptance

assay

Sign


almethylationin

10-w

eekexpo

sedsamplesw

hich

persisted

after

expo

sure

interrup

tion

methylationchanges

abolish

edby

useo

fairfilters

[167]

High-fatd

iet

Mice

Adultexp

osure

10-w

eekexpo

sure

tohigh

-fatd

ietfrom

5weeks

ofage

Testisc

ells

elong

ated

spermatids

Global

ELISAsem

iquantitativ

eim

mun

ohistochemistry

oftestissectio

nswith

anti-5-mCantib

ody

Abou

t25

redu

ctionin

glob

almethylationin

both

who

letesticularc

ellsandspermatids

[149]

High-fatd

ietp

lus

streptozotocin

subd

iabetogenic

treatment

Mice

Adultexp

osure

13-w

eekexpo

sure

tohigh

-fatd

ietfro

m3weeks

ofageplus

streptozotocinip

injectionat12

weeks

ofage

Sperm

Epigenom

e-wide

Arrays


lteredoverallm

ethylome

patte

rnsinspermw

ithalarge

portionof

differentially

methylated

geneso

verla

ppingwith

thatof


sprin

g[156]

Low-protein

diet

Mice

Adultexp

osure

9-weekexpo

sure

tolow-protein

diet

from

3weeks

ofage

Sperm

119875119901119886119903120572

epigenom

e-wide

BisulfitePC

Rsequ

encing

arrays

Noeffectsof


nin

sperm

overallsperm

cytosin

emethylationpatte

rnsw

ere

largely

conservedun

derv

arious

dietaryregimes

[153]

Olfactoryfear

cond

ition

ing

Mice

Adultexp

osuretoacetop

heno

neSperm

Olfr151

BisulfitePC

Rsequ

encing

Hypom

ethylation

[175]

Streptozotocin

diabetogenic

treatment

Mice

Adultexp

osure

singleipinjectio

nof

230m

gkg

streptozotocin

1525or

35days

before

oocytecollectionaft

ersuperovulation

Oocytes

H19Peg3and

Snrpn

COBR

A

Evidentd

emethylationwas

observed

inthe

methylatio

npatte

rnof

Peg3

DMRon

day35

after

treatmentthem

ethylatio

npatte

rnso

fH19

and

SnrpnDMRs

weren

otsig

nificantly

alteredby

maternald

iabetes

[157]

High-fatd

iet

Mice

Adultexp

osure

12weeks

offeedingwith

high

-fatd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

H19M

estPeg3

Igf2rSnrpnPp

ar120572

andLep

COBR

A

DNAmethylationof

imprintedgenesw

asno

talteredtheP

par120572

methylatio

nlevelw

assig

nificantly

decreasedandtheL

epmethylatio

nlevelw

assig

nificantly

increasedin

high

-fatd

iet

fedmicec

omparedwith

controlm

ice

[158]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Zinc-deficientd

iet

Mice

Adultexp

osure

5days

offeedingwith

zinc-deficientd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

Global

Immun

ocytochemistry

with

anti-5-mCantib

ody

DNAmethylatio

nwas

redu

cedto

abou

t60


ocytes

[155]

Bispheno

lAMice

Neonatalexp

osure

20or

40120583gkg

bw

either

bydaily

hypo

derm

alinjections

from

postn

atal

day7to

postn

atalday14

orby

intraperito

nealinjections

administered

each

fifthdaybetweenpo

stnataldays

5and20prio

rtocollectionof

ovarian

oocytes

Oocytes

H19Igf2rand

Peg3

BisulfitePC

Rsequ

encing

Sign

ificant

dose-dependent

redu

ctionof

methylatio

nin

Igf2rPeg3

genesno

effecto

nH19

[164

]

Bispheno

lAMice

Invitro

expo

sure

to3or

300n

Mdu

ring

12days

offollicle

cultu

refro

mpreantral

toantralsta

geOocytes

H19M

estIgf2r

andSnrpn

BisulfitePC

Rpyrosequ

encing

Sign


natthelow

but

notatthe

high

BPA

doseinMestIgf2rand

Snrpngenesno

effecto

nH19

[165]















4 Discussion


















Abbreviations






























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Airpo

llutio

n(in

cluding

PMandPA

H)

48adultn

onsm

okersBe

lgium

PBL

Global

HPL

CHypom

ethylatio

n[70]

718eld

erlyindividu

alsUSA

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatLINE-1

[71]

706eld

erlyindividu

alsUSA

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylation

[72]

777elderly

individu

alsUSA

PBL

F3IFN

-120574IL-6TL

R-2and

ICAM

-1BisulfitePC

Rpyrosequ

encing

F3ICA

M-1

andTL

R-2

hypo

methylatio

nIFN-120574

and

IL-6

hyperm

ethylatio

n[73]

776eld

erlyindividu

alsUSA

PBL

F3ICA

M-1

IFN-120574IL-6

TLR-2CR

ATG

CRiNOS

andOGG

1BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

nat

TLR2

GCR

TLR

2F3and

IL6

[74]

63ste

elworkersItaly

PBL

LINE-1AluiNOS

p16 p53hT

ERT

andAP

CRA

SSF1A

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natiNOS

p53andRA

SSF1A

hyperm

ethylatio

natAP

Cp16

[81ndash83]

49no

nsmok

ingcoke-oven

workersand43

controls

Poland

PBL

p16p53IL-6H

IC1

LINE-1andAlu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natLINE-1

AluandIL-6

hypo

methylatio

natp53

[84]

60truckdriversa

nd60

controls

China

PBL

Tand

emrepeatsS

at120572

NBL

2andD4Z

4BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natSat120572

and

NBL

2[85]

120malew

orkersItalyand

China

PBL

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[87]

67indu

stria

lworkers65

resid

ents

and45

ruralcon

trols

Thailand

PBL

LINE-1Alup16p53HIC1

andIL-6

BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natp53IL-6

andLINE-1

[88]

78gasolin

efilling

attend

ants77

urbantraffi

cofficers57control

office

workersItaly

PBL

LINE-1Alu

p15andMAG

E1BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natLINE-1

AluandMAG

E1

hyperm

ethylatio

natp15

[89]

78gasolin

efilling

attend

ants58

controloffice

workerIta

lyPB

LGlobal

High-resolutio

nGC-

MS

Hypom

ethylatio

n[90]

158petro

chem

icalworkersand

50controloffice

workers

Bulgaria

PBL

LINE-1Alup15and

MAG

E1BisulfitePC

Rpyrosequ

encing

Hypom

ethylatio

natLINE-1

andp15

[91]

141a

sthm

aticchild

renand70

controls

USA

Treg

cells

from

PBL

Foxp3

Hypermethylatio

n[75]

940child

ren

USA

Buccalcells

NOS1N

OS2A

andNOS3

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

nat

NOS2AandNOS3

[ 76]

56mother-child

pairs

USA

PBL(cordbloo

d)AC

SL3

Methylatio

n-specificP

CRHypermethylatio

n[79]

164mother-child

pairs

USA

PBL(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[78]

53mother-child

pairs

USA

PBL(cordbloo

d)IFN120574andIL-4

BisulfitePC

Rsequ

encing

Hypermethylatio

natIFN120574

[80]

POPs

70Inuits

Greenland

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[92]

86adultsSou

thKo

rea

PBL

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[93]

358mother-child

pairs

USA

PBL(cordbloo

dandat9

years)

LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAlu

[98]

Bispheno

lA43

wom

enun

dergoing

IVFUSA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natthe

TSP5

0[62]

46preado

lescentg

irlsEg

ypt

Saliva

Epigenom

e-wide

Arrays

Hypom

ethylatio

natseveral

loci

[94]


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

PFASs

685adults

USA

PBL

LINE-1

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[95]

262fertile

men

Greenland

PolandUkraine

Sperm

GlobalLINE-1Aluand

119878119886119905120572

Flow

cytometry

immun

odetectio

nof

5-mC

bisulfitePC

Rpyrosequ

encing

Noconsistentchanges

[96]

30mother-child

pairsU

SAPB

L(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[97]

EDs

192mother-child

pairs

Spain

Placenta

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

AluY

b8hypo

methylatio

nin

boys

[99]

Tobaccosm

oke

177adults

Germany

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3[103]

374adults

Italy

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3AH

RRand

otherloci

[105]

261a

dultsItaly

PBL

AHRR

6p21

(1locus)

2q37

(2loci)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[111]

3588adults

Germany

PBL

F2RL

3MALD

I-TOFMS

Hypom

ethylatio

n[106]

399African

American

youths

USA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[109]

107African

American

youn

gmenU

SAPB

LEp

igenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[110]

111a

dultAfrican

American

wom

enU

SAPB

LEp

igenom

e-wide

Arrays

Differentia

lmethylatio

nat910

locihypom

ethylationat

AHRR

andGP

R15

[112]

348mother-child

pairs

USA

Child

buccalcells

LINE-1AluY

b8BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAluY

b8[113]

272mother-child

pairs

USA

Child

buccalcells

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin


nat

AXLandPT

PRO

[113]

173mother-child

pairs

USA

Child

buccalcells

AXL

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[114]


pairs

USA

Child

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat19

loci

[115]

36mother-child

pairs

(18

nonsmokersa

nd18

smokers)

USA

Placenta

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat

severalloci

[117]

1062

mother-child

pairs

Norway

PBL(cordbloo

d)Ep

igenom

e-wide

Arrays

Differentia

lmethylatio

nin

10genesincluding

AHRR

CY

P1A1

and

GFI1

[118]

418mother-child

pairs

USA

PBL(cordbloo

d)DMRs

ofIG

F2andH19

BisulfitePC

Rpyrosequ

encing

IGF2

DMRdifferential

methylatio

n[119]

380mother-child

pairs

USA

PBL(cordbloo

d)LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natAluY

b8[120]

206mother-child

pairs

USA

Placenta

Epigenom

e-wide

Arrays

Hypermethylatio

natRU

NX3

[121]

132mother-child

pairs

Canada

PBL(ado

lescents)

Epigenom

e-wide

Arrays

Hypermethylatio

natMYO

1G

hypo

methylatio

nat

CNTN

AP2

[122]







































Table2Syno

psisofpapersrepo

rtinge

ffectso

fexp

erim

entaltreatmentson


maleo

rfem

aleg

erm

cells

(whenadditio

naltissuesw

erea

nalyzedthey

arespecified)

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Flutam

ide

Rats

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

sperm

ofadult

anim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Procym

idon

eRa

tsIn

uteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

Multip

leun

specified

Methylatio

n-specific

restr

ictio

nEn

donu

clease

digestion

Alteredmethylatio

ndetected

atmultip

lesequ

encesinvolving

both

hypo

-and

hyperm

ethylatio

nevents

[159]

Vinclozolin

Mice

Inuteroexpo

sure

ipinjectio

nof

50mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Inspermhighlysig

nificantH

19andMeg3

hypo

methylatio


hyperm

ethylation


tissues

[161]

Dioxin

Mice

Inuteroexpo

sure

ipinjectio

nof

2or

10ng

kgday

betweenday9andday19

ofgesta

tion

Spermplusliver

andskele

tal

muscle

cells

inadultanimals

SnrpnPeg3and

Igf2r

BisulfitePC

Rpyrosequ

encing


nchangesin

sperminliver

andmuscle

cells

significant

increaseso

fmethylationin

Igf2r

[163]

Metho

xychlor

Mice

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

H19

and

Meg3andsig

nificantly

increasedmethylatio

nof

MestSnrpnandPeg3

inspermn

oeffectin

somatictissues

[162]

Ethano

lMice

Inuteroexpo

sure

poadministratio

nof

05g

kgday

betweenday10

andday18

ofgesta

tion

Spermplustail

liverskeletal

muscle

and

brain

cells

inadult

anim

als

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Highlysig

nificant3decrease

inthen

umbero

fmethylatedCp

Gso

fH19noeffectintheo

ther

genesa

ndin

somatictissues

[168]

Folate-deficient

diet

Mice

Inuteroexpo

sure

treatmento

fdam

swith

folate-deficient

dietfro

mtwoweeks

before

mating

throug

hout

gesta

tionandlactation

Sperm

Epigenom

e-wide

Arrays

57geno

micregion

shad

alteredmethylatio

nprofi

lesinsperm

from

males

expo

sedto

folate-deficient

dietbothhypo

-and

hyperm

ethylatio

nwereo

bservedmethylatio

ndifferences

observed

inprom

oter

region

sofgenes

implicated

indevelopm

entand

with

functio

nsin

thec

entralnervou

ssystemkidneyspleen

digestive

tractandmuscle

tissueandof

genes

associated

with

diabetesautoimmun

edise

ases


schizop

hreniaand

cancer

[154]

Und

erno

urish

ment

Mice

Inuteroexpo



gesta

tion

Sperm

Global

epigenom

e-wide


166differentially

methylatedregion

sof

which

111

wereh

ypom

ethylatedand55

hyperm

ethylatedin

undernou

rishedrelativ

etocontrolm

icethe

bisulfitepyrosequ

encing

valid

ationconfi

rmed

1724hypo

methylated

and08hyperm

ethylated

region

s

[152]

Metho

xychlor

Mice

Adultexp

osure

ipinjectio

nof

10mgkgday

for8

consecutived

ays

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

Meg3and

significantly


andPeg3

inspermn


[162]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Ethano

lMice

Adultexp

osure

poadministratio

nof

59g

kgdayfor2

9days

over

aperiodof

5weeks

Sperm

H19R

asgrf1

BisulfitePC

Rpyrosequ

encing


nchanges

[169]

Fenvalerate

Mice

Adultexp

osure

poadministratio

nof

10mgkgday

for

30days

Sperm

Epigenom

e-wide

Arrays

Sign

ificant

Hap1h

ypom

ethylatio

nsig

nificantA

ce

Foxo3aN

r3c2P

mlandPtgfrn

hyperm

ethylatio

n[172]

Sodium

fluoride

Mice

Adultexp

osure

poadministratio

nof

100m

gLin

drinking

water

for3

5days

Spermplusliver

cells

inadult

anim

als

H19R

asgrf1

Peg3

andLine-1

glob

alBisulfitePC

Rsequ

encing

EL

ISA


nchanges

[173]

Tamoxifen

Rats

Adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Igf2-H

19global

BisulfitePC

Rsequ

encing

flo

wcytometry

after

immun

ostainingwith

5-methylcytosine

antib

ody

Sign

ificantlyredu


19

glob

almethylatio

nlevelu

naffected

[171]

Tamoxifen

Rats

adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Dlk1Plagl1

Peg5

Peg3Igf2rG

rb10

Kcnq

1Ascl2

and

Cdkn1c

BisulfitePC

Rsequ

encing


nchanges

[170]

Bispheno

lARa

tsNeonatalexp

osure

5daily

subcutaneous

injections

of04m

gkgday

BPAsta

rtingon

eday

after

birth

Sperm

Igf2-H

19BisulfitePC

Rsequ

encing

Sign

ificant

hypo

methylationattheH

19ICR

[166]

Particulatea

irpo

llutio

nMice

Adultexp

osure

3or

10weeks

ofexpo

sure

toam

bientair

inpo

llutedsites

Sperm

samplingeither

immediatelyor

6weeks

after

thee

ndof

10-w

eekexpo

sure

Sperm

Global

Cytosin

eextensio

nassay

andmethylacceptance

assay

Sign


almethylationin

10-w

eekexpo

sedsamplesw

hich

persisted

after

expo

sure

interrup

tion

methylationchanges

abolish

edby

useo

fairfilters

[167]

High-fatd

iet

Mice

Adultexp

osure

10-w

eekexpo

sure

tohigh

-fatd

ietfrom

5weeks

ofage

Testisc

ells

elong

ated

spermatids

Global

ELISAsem

iquantitativ

eim

mun

ohistochemistry

oftestissectio

nswith

anti-5-mCantib

ody

Abou

t25

redu

ctionin

glob

almethylationin

both

who

letesticularc

ellsandspermatids

[149]

High-fatd

ietp

lus

streptozotocin

subd

iabetogenic

treatment

Mice

Adultexp

osure

13-w

eekexpo

sure

tohigh

-fatd

ietfro

m3weeks

ofageplus

streptozotocinip

injectionat12

weeks

ofage

Sperm

Epigenom

e-wide

Arrays


lteredoverallm

ethylome

patte

rnsinspermw

ithalarge

portionof

differentially

methylated

geneso

verla

ppingwith

thatof


sprin

g[156]

Low-protein

diet

Mice

Adultexp

osure

9-weekexpo

sure

tolow-protein

diet

from

3weeks

ofage

Sperm

119875119901119886119903120572

epigenom

e-wide

BisulfitePC

Rsequ

encing

arrays

Noeffectsof


nin

sperm

overallsperm

cytosin

emethylationpatte

rnsw

ere

largely

conservedun

derv

arious

dietaryregimes

[153]

Olfactoryfear

cond

ition

ing

Mice

Adultexp

osuretoacetop

heno

neSperm

Olfr151

BisulfitePC

Rsequ

encing

Hypom

ethylation

[175]

Streptozotocin

diabetogenic

treatment

Mice

Adultexp

osure

singleipinjectio

nof

230m

gkg

streptozotocin

1525or

35days

before

oocytecollectionaft

ersuperovulation

Oocytes

H19Peg3and

Snrpn

COBR

A

Evidentd

emethylationwas

observed

inthe

methylatio

npatte

rnof

Peg3

DMRon

day35

after

treatmentthem

ethylatio

npatte

rnso

fH19

and

SnrpnDMRs

weren

otsig

nificantly

alteredby

maternald

iabetes

[157]

High-fatd

iet

Mice

Adultexp

osure

12weeks

offeedingwith

high

-fatd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

H19M

estPeg3

Igf2rSnrpnPp

ar120572

andLep

COBR

A

DNAmethylationof

imprintedgenesw

asno

talteredtheP

par120572

methylatio

nlevelw

assig

nificantly

decreasedandtheL

epmethylatio

nlevelw

assig

nificantly

increasedin

high

-fatd

iet

fedmicec

omparedwith

controlm

ice

[158]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Zinc-deficientd

iet

Mice

Adultexp

osure

5days

offeedingwith

zinc-deficientd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

Global

Immun

ocytochemistry

with

anti-5-mCantib

ody

DNAmethylatio

nwas

redu

cedto

abou

t60


ocytes

[155]

Bispheno

lAMice

Neonatalexp

osure

20or

40120583gkg

bw

either

bydaily

hypo

derm

alinjections

from

postn

atal

day7to

postn

atalday14

orby

intraperito

nealinjections

administered

each

fifthdaybetweenpo

stnataldays

5and20prio

rtocollectionof

ovarian

oocytes

Oocytes

H19Igf2rand

Peg3

BisulfitePC

Rsequ

encing

Sign

ificant

dose-dependent

redu

ctionof

methylatio

nin

Igf2rPeg3

genesno

effecto

nH19

[164

]

Bispheno

lAMice

Invitro

expo

sure

to3or

300n

Mdu

ring

12days

offollicle

cultu

refro

mpreantral

toantralsta

geOocytes

H19M

estIgf2r

andSnrpn

BisulfitePC

Rpyrosequ

encing

Sign


natthelow

but

notatthe

high

BPA

doseinMestIgf2rand

Snrpngenesno

effecto

nH19

[165]















4 Discussion


















Abbreviations






























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


Table1Con

tinued

Expo

sure

(chemical)

Stud

ypo

pulatio

nTargettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

PFASs

685adults

USA

PBL

LINE-1

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[95]

262fertile

men

Greenland

PolandUkraine

Sperm

GlobalLINE-1Aluand

119878119886119905120572

Flow

cytometry

immun

odetectio

nof

5-mC

bisulfitePC

Rpyrosequ

encing

Noconsistentchanges

[96]

30mother-child

pairsU

SAPB

L(cordbloo

d)Global

ELISA

Hypom

ethylatio

n[97]

EDs

192mother-child

pairs

Spain

Placenta

LINE-1sub

families

(L1H

SL1PA

5L1PA

2andL1Ta)

Alusubfam

ilies

(AluSx

AluY

b8and

AluY

d6)

HER

Vsubfam

ilies

(MLT

1D

ERV1

and

ERV9

)

BisulfitePC

Rpyrosequ

encing

AluY

b8hypo

methylatio

nin

boys

[99]

Tobaccosm

oke

177adults

Germany

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3[103]

374adults

Italy

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natF2RL

3AH

RRand

otherloci

[105]

261a

dultsItaly

PBL

AHRR

6p21

(1locus)

2q37

(2loci)

BisulfitePC

Rpyrosequ

encing

Differentia

lmethylatio

n[111]

3588adults

Germany

PBL

F2RL

3MALD

I-TOFMS

Hypom

ethylatio

n[106]

399African

American

youths

USA

PBL

Epigenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[109]

107African

American

youn

gmenU

SAPB

LEp

igenom

e-wide

Arrays

Hypom

ethylatio

natAH

RR[110]

111a

dultAfrican

American

wom

enU

SAPB

LEp

igenom

e-wide

Arrays

Differentia

lmethylatio

nat910

locihypom

ethylationat

AHRR

andGP

R15

[112]

348mother-child

pairs

USA

Child

buccalcells

LINE-1AluY

b8BisulfitePC

Rpyrosequ

encing

Hypom

ethylationatAluY

b8[113]

272mother-child

pairs

USA

Child

buccalcells

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nin


nat

AXLandPT

PRO

[113]

173mother-child

pairs

USA

Child

buccalcells

AXL

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

n[114]


pairs

USA

Child

PBL

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat19

loci

[115]

36mother-child

pairs

(18

nonsmokersa

nd18

smokers)

USA

Placenta

Epigenom

e-wide

Arrays

Differentia

lmethylatio

nat

severalloci

[117]

1062

mother-child

pairs

Norway

PBL(cordbloo

d)Ep

igenom

e-wide

Arrays

Differentia

lmethylatio

nin

10genesincluding

AHRR

CY

P1A1

and

GFI1

[118]

418mother-child

pairs

USA

PBL(cordbloo

d)DMRs

ofIG

F2andH19

BisulfitePC

Rpyrosequ

encing

IGF2

DMRdifferential

methylatio

n[119]

380mother-child

pairs

USA

PBL(cordbloo

d)LINE-1Alu

BisulfitePC

Rpyrosequ

encing

Hypermethylatio

natAluY

b8[120]

206mother-child

pairs

USA

Placenta

Epigenom

e-wide

Arrays

Hypermethylatio

natRU

NX3

[121]

132mother-child

pairs

Canada

PBL(ado

lescents)

Epigenom

e-wide

Arrays

Hypermethylatio

natMYO

1G

hypo

methylatio

nat

CNTN

AP2

[122]







































Table2Syno

psisofpapersrepo

rtinge

ffectso

fexp

erim

entaltreatmentson


maleo

rfem

aleg

erm

cells

(whenadditio

naltissuesw

erea

nalyzedthey

arespecified)

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Flutam

ide

Rats

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

sperm

ofadult

anim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Procym

idon

eRa

tsIn

uteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

Multip

leun

specified

Methylatio

n-specific

restr

ictio

nEn

donu

clease

digestion

Alteredmethylatio

ndetected

atmultip

lesequ

encesinvolving

both

hypo

-and

hyperm

ethylatio

nevents

[159]

Vinclozolin

Mice

Inuteroexpo

sure

ipinjectio

nof

50mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Inspermhighlysig

nificantH

19andMeg3

hypo

methylatio


hyperm

ethylation


tissues

[161]

Dioxin

Mice

Inuteroexpo

sure

ipinjectio

nof

2or

10ng

kgday

betweenday9andday19

ofgesta

tion

Spermplusliver

andskele

tal

muscle

cells

inadultanimals

SnrpnPeg3and

Igf2r

BisulfitePC

Rpyrosequ

encing


nchangesin

sperminliver

andmuscle

cells

significant

increaseso

fmethylationin

Igf2r

[163]

Metho

xychlor

Mice

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

H19

and

Meg3andsig

nificantly

increasedmethylatio

nof

MestSnrpnandPeg3

inspermn

oeffectin

somatictissues

[162]

Ethano

lMice

Inuteroexpo

sure

poadministratio

nof

05g

kgday

betweenday10

andday18

ofgesta

tion

Spermplustail

liverskeletal

muscle

and

brain

cells

inadult

anim

als

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Highlysig

nificant3decrease

inthen

umbero

fmethylatedCp

Gso

fH19noeffectintheo

ther

genesa

ndin

somatictissues

[168]

Folate-deficient

diet

Mice

Inuteroexpo

sure

treatmento

fdam

swith

folate-deficient

dietfro

mtwoweeks

before

mating

throug

hout

gesta

tionandlactation

Sperm

Epigenom

e-wide

Arrays

57geno

micregion

shad

alteredmethylatio

nprofi

lesinsperm

from

males

expo

sedto

folate-deficient

dietbothhypo

-and

hyperm

ethylatio

nwereo

bservedmethylatio

ndifferences

observed

inprom

oter

region

sofgenes

implicated

indevelopm

entand

with

functio

nsin

thec

entralnervou

ssystemkidneyspleen

digestive

tractandmuscle

tissueandof

genes

associated

with

diabetesautoimmun

edise

ases


schizop

hreniaand

cancer

[154]

Und

erno

urish

ment

Mice

Inuteroexpo



gesta

tion

Sperm

Global

epigenom

e-wide


166differentially

methylatedregion

sof

which

111

wereh

ypom

ethylatedand55

hyperm

ethylatedin

undernou

rishedrelativ

etocontrolm

icethe

bisulfitepyrosequ

encing

valid

ationconfi

rmed

1724hypo

methylated

and08hyperm

ethylated

region

s

[152]

Metho

xychlor

Mice

Adultexp

osure

ipinjectio

nof

10mgkgday

for8

consecutived

ays

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

Meg3and

significantly


andPeg3

inspermn


[162]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Ethano

lMice

Adultexp

osure

poadministratio

nof

59g

kgdayfor2

9days

over

aperiodof

5weeks

Sperm

H19R

asgrf1

BisulfitePC

Rpyrosequ

encing


nchanges

[169]

Fenvalerate

Mice

Adultexp

osure

poadministratio

nof

10mgkgday

for

30days

Sperm

Epigenom

e-wide

Arrays

Sign

ificant

Hap1h

ypom

ethylatio

nsig

nificantA

ce

Foxo3aN

r3c2P

mlandPtgfrn

hyperm

ethylatio

n[172]

Sodium

fluoride

Mice

Adultexp

osure

poadministratio

nof

100m

gLin

drinking

water

for3

5days

Spermplusliver

cells

inadult

anim

als

H19R

asgrf1

Peg3

andLine-1

glob

alBisulfitePC

Rsequ

encing

EL

ISA


nchanges

[173]

Tamoxifen

Rats

Adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Igf2-H

19global

BisulfitePC

Rsequ

encing

flo

wcytometry

after

immun

ostainingwith

5-methylcytosine

antib

ody

Sign

ificantlyredu


19

glob

almethylatio

nlevelu

naffected

[171]

Tamoxifen

Rats

adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Dlk1Plagl1

Peg5

Peg3Igf2rG

rb10

Kcnq

1Ascl2

and

Cdkn1c

BisulfitePC

Rsequ

encing


nchanges

[170]

Bispheno

lARa

tsNeonatalexp

osure

5daily

subcutaneous

injections

of04m

gkgday

BPAsta

rtingon

eday

after

birth

Sperm

Igf2-H

19BisulfitePC

Rsequ

encing

Sign

ificant

hypo

methylationattheH

19ICR

[166]

Particulatea

irpo

llutio

nMice

Adultexp

osure

3or

10weeks

ofexpo

sure

toam

bientair

inpo

llutedsites

Sperm

samplingeither

immediatelyor

6weeks

after

thee

ndof

10-w

eekexpo

sure

Sperm

Global

Cytosin

eextensio

nassay

andmethylacceptance

assay

Sign


almethylationin

10-w

eekexpo

sedsamplesw

hich

persisted

after

expo

sure

interrup

tion

methylationchanges

abolish

edby

useo

fairfilters

[167]

High-fatd

iet

Mice

Adultexp

osure

10-w

eekexpo

sure

tohigh

-fatd

ietfrom

5weeks

ofage

Testisc

ells

elong

ated

spermatids

Global

ELISAsem

iquantitativ

eim

mun

ohistochemistry

oftestissectio

nswith

anti-5-mCantib

ody

Abou

t25

redu

ctionin

glob

almethylationin

both

who

letesticularc

ellsandspermatids

[149]

High-fatd

ietp

lus

streptozotocin

subd

iabetogenic

treatment

Mice

Adultexp

osure

13-w

eekexpo

sure

tohigh

-fatd

ietfro

m3weeks

ofageplus

streptozotocinip

injectionat12

weeks

ofage

Sperm

Epigenom

e-wide

Arrays


lteredoverallm

ethylome

patte

rnsinspermw

ithalarge

portionof

differentially

methylated

geneso

verla

ppingwith

thatof


sprin

g[156]

Low-protein

diet

Mice

Adultexp

osure

9-weekexpo

sure

tolow-protein

diet

from

3weeks

ofage

Sperm

119875119901119886119903120572

epigenom

e-wide

BisulfitePC

Rsequ

encing

arrays

Noeffectsof


nin

sperm

overallsperm

cytosin

emethylationpatte

rnsw

ere

largely

conservedun

derv

arious

dietaryregimes

[153]

Olfactoryfear

cond

ition

ing

Mice

Adultexp

osuretoacetop

heno

neSperm

Olfr151

BisulfitePC

Rsequ

encing

Hypom

ethylation

[175]

Streptozotocin

diabetogenic

treatment

Mice

Adultexp

osure

singleipinjectio

nof

230m

gkg

streptozotocin

1525or

35days

before

oocytecollectionaft

ersuperovulation

Oocytes

H19Peg3and

Snrpn

COBR

A

Evidentd

emethylationwas

observed

inthe

methylatio

npatte

rnof

Peg3

DMRon

day35

after

treatmentthem

ethylatio

npatte

rnso

fH19

and

SnrpnDMRs

weren

otsig

nificantly

alteredby

maternald

iabetes

[157]

High-fatd

iet

Mice

Adultexp

osure

12weeks

offeedingwith

high

-fatd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

H19M

estPeg3

Igf2rSnrpnPp

ar120572

andLep

COBR

A

DNAmethylationof

imprintedgenesw

asno

talteredtheP

par120572

methylatio

nlevelw

assig

nificantly

decreasedandtheL

epmethylatio

nlevelw

assig

nificantly

increasedin

high

-fatd

iet

fedmicec

omparedwith

controlm

ice

[158]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Zinc-deficientd

iet

Mice

Adultexp

osure

5days

offeedingwith

zinc-deficientd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

Global

Immun

ocytochemistry

with

anti-5-mCantib

ody

DNAmethylatio

nwas

redu

cedto

abou

t60


ocytes

[155]

Bispheno

lAMice

Neonatalexp

osure

20or

40120583gkg

bw

either

bydaily

hypo

derm

alinjections

from

postn

atal

day7to

postn

atalday14

orby

intraperito

nealinjections

administered

each

fifthdaybetweenpo

stnataldays

5and20prio

rtocollectionof

ovarian

oocytes

Oocytes

H19Igf2rand

Peg3

BisulfitePC

Rsequ

encing

Sign

ificant

dose-dependent

redu

ctionof

methylatio

nin

Igf2rPeg3

genesno

effecto

nH19

[164

]

Bispheno

lAMice

Invitro

expo

sure

to3or

300n

Mdu

ring

12days

offollicle

cultu

refro

mpreantral

toantralsta

geOocytes

H19M

estIgf2r

andSnrpn

BisulfitePC

Rpyrosequ

encing

Sign


natthelow

but

notatthe

high

BPA

doseinMestIgf2rand

Snrpngenesno

effecto

nH19

[165]















4 Discussion


















Abbreviations






























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of







































Table2Syno

psisofpapersrepo

rtinge

ffectso

fexp

erim

entaltreatmentson


maleo

rfem

aleg

erm

cells

(whenadditio

naltissuesw

erea

nalyzedthey

arespecified)

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Flutam

ide

Rats

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

sperm

ofadult

anim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Procym

idon

eRa

tsIn

uteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

LPLa

seBisulfitePC

Rsequ

encing


nchanges

[160]

Vinclozolin

Rats

Inuteroexpo

sure

ipinjectio

nof

100m

gkgdaybetween

day8andday15

ofgestation

Testisc

ellsof

6-day-oldanim

als

Multip

leun

specified

Methylatio

n-specific

restr

ictio

nEn

donu

clease

digestion

Alteredmethylatio

ndetected

atmultip

lesequ

encesinvolving

both

hypo

-and

hyperm

ethylatio

nevents

[159]

Vinclozolin

Mice

Inuteroexpo

sure

ipinjectio

nof

50mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Inspermhighlysig

nificantH

19andMeg3

hypo

methylatio


hyperm

ethylation


tissues

[161]

Dioxin

Mice

Inuteroexpo

sure

ipinjectio

nof

2or

10ng

kgday

betweenday9andday19

ofgesta

tion

Spermplusliver

andskele

tal

muscle

cells

inadultanimals

SnrpnPeg3and

Igf2r

BisulfitePC

Rpyrosequ

encing


nchangesin

sperminliver

andmuscle

cells

significant

increaseso

fmethylationin

Igf2r

[163]

Metho

xychlor

Mice

Inuteroexpo

sure

ipinjectio

nof

10mgkgdaybetween

day10

andday18

ofgesta

tion

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

H19

and

Meg3andsig

nificantly

increasedmethylatio

nof

MestSnrpnandPeg3

inspermn

oeffectin

somatictissues

[162]

Ethano

lMice

Inuteroexpo

sure

poadministratio

nof

05g

kgday

betweenday10

andday18

ofgesta

tion

Spermplustail

liverskeletal

muscle

and

brain

cells

inadult

anim

als

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Highlysig

nificant3decrease

inthen

umbero

fmethylatedCp

Gso

fH19noeffectintheo

ther

genesa

ndin

somatictissues

[168]

Folate-deficient

diet

Mice

Inuteroexpo

sure

treatmento

fdam

swith

folate-deficient

dietfro

mtwoweeks

before

mating

throug

hout

gesta

tionandlactation

Sperm

Epigenom

e-wide

Arrays

57geno

micregion

shad

alteredmethylatio

nprofi

lesinsperm

from

males

expo

sedto

folate-deficient

dietbothhypo

-and

hyperm

ethylatio

nwereo

bservedmethylatio

ndifferences

observed

inprom

oter

region

sofgenes

implicated

indevelopm

entand

with

functio

nsin

thec

entralnervou

ssystemkidneyspleen

digestive

tractandmuscle

tissueandof

genes

associated

with

diabetesautoimmun

edise

ases


schizop

hreniaand

cancer

[154]

Und

erno

urish

ment

Mice

Inuteroexpo



gesta

tion

Sperm

Global

epigenom

e-wide


166differentially

methylatedregion

sof

which

111

wereh

ypom

ethylatedand55

hyperm

ethylatedin

undernou

rishedrelativ

etocontrolm

icethe

bisulfitepyrosequ

encing

valid

ationconfi

rmed

1724hypo

methylated

and08hyperm

ethylated

region

s

[152]

Metho

xychlor

Mice

Adultexp

osure

ipinjectio

nof

10mgkgday

for8

consecutived

ays

Spermplustail

liverand

skele

tal

muscle

cells

inadultanimals

H19M

eg3Mest

SnrpnandPeg3

BisulfitePC

Rpyrosequ

encing

Sign


nof

Meg3and

significantly


andPeg3

inspermn


[162]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Ethano

lMice

Adultexp

osure

poadministratio

nof

59g

kgdayfor2

9days

over

aperiodof

5weeks

Sperm

H19R

asgrf1

BisulfitePC

Rpyrosequ

encing


nchanges

[169]

Fenvalerate

Mice

Adultexp

osure

poadministratio

nof

10mgkgday

for

30days

Sperm

Epigenom

e-wide

Arrays

Sign

ificant

Hap1h

ypom

ethylatio

nsig

nificantA

ce

Foxo3aN

r3c2P

mlandPtgfrn

hyperm

ethylatio

n[172]

Sodium

fluoride

Mice

Adultexp

osure

poadministratio

nof

100m

gLin

drinking

water

for3

5days

Spermplusliver

cells

inadult

anim

als

H19R

asgrf1

Peg3

andLine-1

glob

alBisulfitePC

Rsequ

encing

EL

ISA


nchanges

[173]

Tamoxifen

Rats

Adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Igf2-H

19global

BisulfitePC

Rsequ

encing

flo

wcytometry

after

immun

ostainingwith

5-methylcytosine

antib

ody

Sign

ificantlyredu


19

glob

almethylatio

nlevelu

naffected

[171]

Tamoxifen

Rats

adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Dlk1Plagl1

Peg5

Peg3Igf2rG

rb10

Kcnq

1Ascl2

and

Cdkn1c

BisulfitePC

Rsequ

encing


nchanges

[170]

Bispheno

lARa

tsNeonatalexp

osure

5daily

subcutaneous

injections

of04m

gkgday

BPAsta

rtingon

eday

after

birth

Sperm

Igf2-H

19BisulfitePC

Rsequ

encing

Sign

ificant

hypo

methylationattheH

19ICR

[166]

Particulatea

irpo

llutio

nMice

Adultexp

osure

3or

10weeks

ofexpo

sure

toam

bientair

inpo

llutedsites

Sperm

samplingeither

immediatelyor

6weeks

after

thee

ndof

10-w

eekexpo

sure

Sperm

Global

Cytosin

eextensio

nassay

andmethylacceptance

assay

Sign


almethylationin

10-w

eekexpo

sedsamplesw

hich

persisted

after

expo

sure

interrup

tion

methylationchanges

abolish

edby

useo

fairfilters

[167]

High-fatd

iet

Mice

Adultexp

osure

10-w

eekexpo

sure

tohigh

-fatd

ietfrom

5weeks

ofage

Testisc

ells

elong

ated

spermatids

Global

ELISAsem

iquantitativ

eim

mun

ohistochemistry

oftestissectio

nswith

anti-5-mCantib

ody

Abou

t25

redu

ctionin

glob

almethylationin

both

who

letesticularc

ellsandspermatids

[149]

High-fatd

ietp

lus

streptozotocin

subd

iabetogenic

treatment

Mice

Adultexp

osure

13-w

eekexpo

sure

tohigh

-fatd

ietfro

m3weeks

ofageplus

streptozotocinip

injectionat12

weeks

ofage

Sperm

Epigenom

e-wide

Arrays


lteredoverallm

ethylome

patte

rnsinspermw

ithalarge

portionof

differentially

methylated

geneso

verla

ppingwith

thatof


sprin

g[156]

Low-protein

diet

Mice

Adultexp

osure

9-weekexpo

sure

tolow-protein

diet

from

3weeks

ofage

Sperm

119875119901119886119903120572

epigenom

e-wide

BisulfitePC

Rsequ

encing

arrays

Noeffectsof


nin

sperm

overallsperm

cytosin

emethylationpatte

rnsw

ere

largely

conservedun

derv

arious

dietaryregimes

[153]

Olfactoryfear

cond

ition

ing

Mice

Adultexp

osuretoacetop

heno

neSperm

Olfr151

BisulfitePC

Rsequ

encing

Hypom

ethylation

[175]

Streptozotocin

diabetogenic

treatment

Mice

Adultexp

osure

singleipinjectio

nof

230m

gkg

streptozotocin

1525or

35days

before

oocytecollectionaft

ersuperovulation

Oocytes

H19Peg3and

Snrpn

COBR

A

Evidentd

emethylationwas

observed

inthe

methylatio

npatte

rnof

Peg3

DMRon

day35

after

treatmentthem

ethylatio

npatte

rnso

fH19

and

SnrpnDMRs

weren

otsig

nificantly

alteredby

maternald

iabetes

[157]

High-fatd

iet

Mice

Adultexp

osure

12weeks

offeedingwith

high

-fatd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

H19M

estPeg3

Igf2rSnrpnPp

ar120572

andLep

COBR

A

DNAmethylationof

imprintedgenesw

asno

talteredtheP

par120572

methylatio

nlevelw

assig

nificantly

decreasedandtheL

epmethylatio

nlevelw

assig

nificantly

increasedin

high

-fatd

iet

fedmicec

omparedwith

controlm

ice

[158]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Zinc-deficientd

iet

Mice

Adultexp

osure

5days

offeedingwith

zinc-deficientd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

Global

Immun

ocytochemistry

with

anti-5-mCantib

ody

DNAmethylatio

nwas

redu

cedto

abou

t60


ocytes

[155]

Bispheno

lAMice

Neonatalexp

osure

20or

40120583gkg

bw

either

bydaily

hypo

derm

alinjections

from

postn

atal

day7to

postn

atalday14

orby

intraperito

nealinjections

administered

each

fifthdaybetweenpo

stnataldays

5and20prio

rtocollectionof

ovarian

oocytes

Oocytes

H19Igf2rand

Peg3

BisulfitePC

Rsequ

encing

Sign

ificant

dose-dependent

redu

ctionof

methylatio

nin

Igf2rPeg3

genesno

effecto

nH19

[164

]

Bispheno

lAMice

Invitro

expo

sure

to3or

300n

Mdu

ring

12days

offollicle

cultu

refro

mpreantral

toantralsta

geOocytes

H19M

estIgf2r

andSnrpn

BisulfitePC

Rpyrosequ

encing

Sign


natthelow

but

notatthe

high

BPA

doseinMestIgf2rand

Snrpngenesno

effecto

nH19

[165]















4 Discussion


















Abbreviations






























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Ethano

lMice

Adultexp

osure

poadministratio

nof

59g

kgdayfor2

9days

over

aperiodof

5weeks

Sperm

H19R

asgrf1

BisulfitePC

Rpyrosequ

encing


nchanges

[169]

Fenvalerate

Mice

Adultexp

osure

poadministratio

nof

10mgkgday

for

30days

Sperm

Epigenom

e-wide

Arrays

Sign

ificant

Hap1h

ypom

ethylatio

nsig

nificantA

ce

Foxo3aN

r3c2P

mlandPtgfrn

hyperm

ethylatio

n[172]

Sodium

fluoride

Mice

Adultexp

osure

poadministratio

nof

100m

gLin

drinking

water

for3

5days

Spermplusliver

cells

inadult

anim

als

H19R

asgrf1

Peg3

andLine-1

glob

alBisulfitePC

Rsequ

encing

EL

ISA


nchanges

[173]

Tamoxifen

Rats

Adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Igf2-H

19global

BisulfitePC

Rsequ

encing

flo

wcytometry

after

immun

ostainingwith

5-methylcytosine

antib

ody

Sign

ificantlyredu


19

glob

almethylatio

nlevelu

naffected

[171]

Tamoxifen

Rats

adultexp

osure

poadministratio

nof

04m

gkgday

5days

aweekfor6

0days

Sperm

Dlk1Plagl1

Peg5

Peg3Igf2rG

rb10

Kcnq

1Ascl2

and

Cdkn1c

BisulfitePC

Rsequ

encing


nchanges

[170]

Bispheno

lARa

tsNeonatalexp

osure

5daily

subcutaneous

injections

of04m

gkgday

BPAsta

rtingon

eday

after

birth

Sperm

Igf2-H

19BisulfitePC

Rsequ

encing

Sign

ificant

hypo

methylationattheH

19ICR

[166]

Particulatea

irpo

llutio

nMice

Adultexp

osure

3or

10weeks

ofexpo

sure

toam

bientair

inpo

llutedsites

Sperm

samplingeither

immediatelyor

6weeks

after

thee

ndof

10-w

eekexpo

sure

Sperm

Global

Cytosin

eextensio

nassay

andmethylacceptance

assay

Sign


almethylationin

10-w

eekexpo

sedsamplesw

hich

persisted

after

expo

sure

interrup

tion

methylationchanges

abolish

edby

useo

fairfilters

[167]

High-fatd

iet

Mice

Adultexp

osure

10-w

eekexpo

sure

tohigh

-fatd

ietfrom

5weeks

ofage

Testisc

ells

elong

ated

spermatids

Global

ELISAsem

iquantitativ

eim

mun

ohistochemistry

oftestissectio

nswith

anti-5-mCantib

ody

Abou

t25

redu

ctionin

glob

almethylationin

both

who

letesticularc

ellsandspermatids

[149]

High-fatd

ietp

lus

streptozotocin

subd

iabetogenic

treatment

Mice

Adultexp

osure

13-w

eekexpo

sure

tohigh

-fatd

ietfro

m3weeks

ofageplus

streptozotocinip

injectionat12

weeks

ofage

Sperm

Epigenom

e-wide

Arrays


lteredoverallm

ethylome

patte

rnsinspermw

ithalarge

portionof

differentially

methylated

geneso

verla

ppingwith

thatof


sprin

g[156]

Low-protein

diet

Mice

Adultexp

osure

9-weekexpo

sure

tolow-protein

diet

from

3weeks

ofage

Sperm

119875119901119886119903120572

epigenom

e-wide

BisulfitePC

Rsequ

encing

arrays

Noeffectsof


nin

sperm

overallsperm

cytosin

emethylationpatte

rnsw

ere

largely

conservedun

derv

arious

dietaryregimes

[153]

Olfactoryfear

cond

ition

ing

Mice

Adultexp

osuretoacetop

heno

neSperm

Olfr151

BisulfitePC

Rsequ

encing

Hypom

ethylation

[175]

Streptozotocin

diabetogenic

treatment

Mice

Adultexp

osure

singleipinjectio

nof

230m

gkg

streptozotocin

1525or

35days

before

oocytecollectionaft

ersuperovulation

Oocytes

H19Peg3and

Snrpn

COBR

A

Evidentd

emethylationwas

observed

inthe

methylatio

npatte

rnof

Peg3

DMRon

day35

after

treatmentthem

ethylatio

npatte

rnso

fH19

and

SnrpnDMRs

weren

otsig

nificantly

alteredby

maternald

iabetes

[157]

High-fatd

iet

Mice

Adultexp

osure

12weeks

offeedingwith

high

-fatd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

H19M

estPeg3

Igf2rSnrpnPp

ar120572

andLep

COBR

A

DNAmethylationof

imprintedgenesw

asno

talteredtheP

par120572

methylatio

nlevelw

assig

nificantly

decreasedandtheL

epmethylatio

nlevelw

assig

nificantly

increasedin

high

-fatd

iet

fedmicec

omparedwith

controlm

ice

[158]


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Zinc-deficientd

iet

Mice

Adultexp

osure

5days

offeedingwith

zinc-deficientd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

Global

Immun

ocytochemistry

with

anti-5-mCantib

ody

DNAmethylatio

nwas

redu

cedto

abou

t60


ocytes

[155]

Bispheno

lAMice

Neonatalexp

osure

20or

40120583gkg

bw

either

bydaily

hypo

derm

alinjections

from

postn

atal

day7to

postn

atalday14

orby

intraperito

nealinjections

administered

each

fifthdaybetweenpo

stnataldays

5and20prio

rtocollectionof

ovarian

oocytes

Oocytes

H19Igf2rand

Peg3

BisulfitePC

Rsequ

encing

Sign

ificant

dose-dependent

redu

ctionof

methylatio

nin

Igf2rPeg3

genesno

effecto

nH19

[164

]

Bispheno

lAMice

Invitro

expo

sure

to3or

300n

Mdu

ring

12days

offollicle

cultu

refro

mpreantral

toantralsta

geOocytes

H19M

estIgf2r

andSnrpn

BisulfitePC

Rpyrosequ

encing

Sign


natthelow

but

notatthe

high

BPA

doseinMestIgf2rand

Snrpngenesno

effecto

nH19

[165]















4 Discussion


















Abbreviations






























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


Table2Con

tinued

Expo

sure

Expo

sed

anim

als

Dosea

ndtim

eofexp

osure

Targettissue

TargetDNAregion

Metho

dDNAmethylatio

nchanges

Reference

Zinc-deficientd

iet

Mice

Adultexp

osure

5days

offeedingwith

zinc-deficientd

iet

priortooo

cytecollectionby

superovulatio

nOocytes

Global

Immun

ocytochemistry

with

anti-5-mCantib

ody

DNAmethylatio

nwas

redu

cedto

abou

t60


ocytes

[155]

Bispheno

lAMice

Neonatalexp

osure

20or

40120583gkg

bw

either

bydaily

hypo

derm

alinjections

from

postn

atal

day7to

postn

atalday14

orby

intraperito

nealinjections

administered

each

fifthdaybetweenpo

stnataldays

5and20prio

rtocollectionof

ovarian

oocytes

Oocytes

H19Igf2rand

Peg3

BisulfitePC

Rsequ

encing

Sign

ificant

dose-dependent

redu

ctionof

methylatio

nin

Igf2rPeg3

genesno

effecto

nH19

[164

]

Bispheno

lAMice

Invitro

expo

sure

to3or

300n

Mdu

ring

12days

offollicle

cultu

refro

mpreantral

toantralsta

geOocytes

H19M

estIgf2r

andSnrpn

BisulfitePC

Rpyrosequ

encing

Sign


natthelow

but

notatthe

high

BPA

doseinMestIgf2rand

Snrpngenesno

effecto

nH19

[165]















4 Discussion


















Abbreviations






























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of















4 Discussion


















Abbreviations






























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of











Abbreviations






























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


























Acknowledgment


References


























1metabolism




























































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


















































































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of

review article environmental impact on dna methylation in

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