proteasome-ubiquitin pathway in pathology

Proteasome-ubiquitin pathway in pathology

• Nikolajs Sjakste, Faculty of Medicine, University of Latvia

• Genetic and Environmental Influence of Bronchial Asthma in Taiwan, Latvia and Lithuania,

• Tainan, 02.11.12

Proteasomes

How the proteasome acts

“E3-diseases”

• There is only one E1 enzyme• About 10 E2 enzymes• 1000 E3 enzymes• E3 enzymes are divided in 3 classes• RING• U-box• HECT-domain E3 ligases

What happens if a E3 enzyme gene of the

proteasome-ubiquitin system gene is

completely deleted? • Subtelomeric region of

Chromosome 15 harbours UBE3A gene which encodes Ubiquitin-protein ligase E3A (UBE3A)

Inheritance of the deletion from the mother on chromosome 15 produces Angelman syndrome

• AS is characterized by intellectual and developmental delay, speech impediment, sleep disturbance, unstable jerky gait, seizures, hand flapping movements, frequent laughter/smiling and usually a happy demeanour. AS is a classic example of genetic imprinting caused by deletion or inactivation of critical genes on the maternally inherited chromosome 15.

• Angelman syndrome can also be the result of mutation of a single gene. This gene (Ube3a) part of the ubiquitin pathway) is present on both the maternal and paternal chromosomes, but differs in the pattern of methylation (Imprinting). The paternal silencing of the Ube3a gene occurs in a brain region-specific manner; the maternal allele is active almost exclusively in the hippocampus and cerebellum. The most common genetic defect leading to Angelman syndrome is an ~4Mb (mega base) maternal deletion in chromosomal region 15q11-13 causing an absence of Ube3a expression in the maternally imprinted brain regions. Ube3a codes for an E6-AP ubiquitin ligase, which chooses its substrates very selectively and the four identified E6-AP substrates have shed little light on the possible molecular mechanisms underlying the human Angelman syndrome mental retardation state.

E3 neurodevelopmental diseasesDisease UPS component

affectedFunction

Angelman syndrome UBE3A E3 ligase

Williams-Beuren syndrome TRIM50 E3 ligase

Intellectual disability not otherwise specified

CUL4B E3 ligase

HUWE1 E3 ligase. Suppresses N-Myc-DLl3 cascade, stops proliferation enables neuronal differentiation

A girl with Williams syndrome, illustrating typical facial features: broad forehead, short palpebral fissures, low nasal bridge, anteverted nostrils, long filtrum, full cheeks,

and relatively large and often downturned mouth

E3 neurodevelopmental diseases 2Autism spectrum disorders

UBE3A E3 ligase

PARK2 E3 ligaseRFWD2 E3 ligase

FBXO40 Constitutes one of the four subunits of the ubiquitin protein ligase complex called SCFs (SKP1-cullin-F-box),

Johanson-Blizzard syndrome

UBR1 E3 ligase

Johanson-Blizzard syndrome

• Ectodermal displasia:• Abnormal development of the pancreas• Nose• Scalp• Mental retardaton• Hearing loss • Growth failure

E3 neurodegenerative diseasesParkinson disease Parkin

(PARK2)E3-ligase

Machado-Joseph disease

ATXN3 Ataxin-3 interacts with ubiquitinated proteins,can bind the proteasome, when the gene harbors an expanded repeat length, can interfere with the degradation substrates. Associates with the ubiquitin- and proteasome-binding factors Rad23 and valosin-containing protein (VCP/p97). proteins.

E3 in inherited cancer syndromes

• Von Hippel-Lindau syndrome• Adenomatous polyposis coli

Von Hippel-Lindau syndrome pVHL is an E3 ligase

Deubiqitination diseases Disease UPS component

affectedFunction

Ataxia USP-14 Ubiquitin carboxyl-terminal hydrolase 14

Parkinson disease

UCH-L1(PARK5)

Ubiquitin carboxy-terminal hydrolase L1

Immunoproteasomes• IFN-gamma induces the synthesis of three active

site−containing beta-subunits as well as the synthesis of the proteasome maturation protein (POMP).

• The immunosubunits 1i, 2i and 5i are preferentially incorporated into the 20S core after de novo synthesis to form the immunoproteasome.

• In addition, IFN-gamma induces synthesis of PA28. Three PA28 and four P28 subunits form heptameric rings that can bind to the two outer alpha-rings of the 20S constitutive proteasome as well as the 20S immunoproteasome and activate the enzyme complex by opening the central gate.

Immunoproteasomes

“Immunoproteasome” diseases

• Nakajo-Nishimura syndrome• JMP syndrome• CANDLE syndrome

Nakajo-Nishimura syndrome

• an autoinflammatory disorder • pernio-like rashes • progressive partial lipodystrophy• homozygous mutation c.224C > T in exon 2

the PSMB8 gene, which encodes the β5i subunit of immunoproteasome is responsible for development of the disease

JMP syndrome

• Recessive autoinflammatory syndrome characterized by joint contractures, muscle atrophy, microcytic anemia, and panniculitis-induced lipodystrophy (JMP)

• Caused by homozygous missense mutation c.224C>T (p.Thr75Met) in the PSMB8

CANDLE syndrome

• Chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature is an autoinflammatory syndrome recently described in children.

CANDLE syndrome is caused by mutations in PSMB8

• One patient was homozygous for a novel nonsense mutation in PSMB8 (c.405C>A), suggesting a protein truncation;

• 4 patients were homozygous and 2 were heterozygous for a previously reported missense mutation (c.224C>T)

Pathologies of “bad substrates” for proteasomes

Polyglutamine (PolyQ) Diseases

Disease Gene Normal number of repeats

Pathologic number of repeats

DRPLA (Dentatorubropallidoluysian atrophy)

ATN1 or DRPLA

between 6 and 35 copies of CAG

between 49 and 88 copies

Polyglutamine (PolyQ) Diseases 2

HD (Huntington's disease)

HD between 10 and 35 copies of CAG

more than 35 copies

SBMA (Spinobulbar muscular atrophy or Kennedy disease)

AR - Androgen receptor on the X chromosome

between 9 and 36 copies of CAG

between 38 and 62 copies

Models of Poly Q diseases

• Aggregation-prone proteins

• Amyloid formation• Insoluble aggregates

Silica NPs

Liddle syndrome

• severe hypertension, hypokalemia, and metabolic alkalosis.

• In contrast to hyperaldosteronism, which can result in similar symptoms, low aldosterone and renin levels

• The gene responsible for Liddle syndrome was actually identified as a mutation in the beta subunit of the renal epithelial sodium channel (ENaC) . The site of the mutation is located in its binding site to Nedd4 (E3 ubiquitin ligase) .

• Because Nedd4 cannot recognize the channel and target it for degradation,it accumulates. Thus, the mutation leads to excessive re-absorption of Na+ accompanied by water.

Alzheimer’s disease

• Mutated ubiquitin• Impaired proteasome function• More immunoproteasomes

Ubiquitination sites on amino terminally processed tau.

Ihara Y et al. Cold Spring Harb Perspect Med 2012;2:a006361

©2012 by Cold Spring Harbor Laboratory Press

Dysfunction of autophagic and endocytic pathways to lysosomes driven by relevant genes and other risk factors in Alzheimer disease (left side of the diagram) causes or promotes pathophysiology critical to the

development and progression of Alzheimer disease...



Schematic illustrating the endocytic and the autophagic pathways to the lysosome.



Frontotemporal dementias

• Ubiquitinylated TAR DNA-binding protein (TDP-43) accumulates

• Ubiquilin 2 – involved in transport of ubiquinylated proteins to proteasome

• FUS protein

Amyotrophic lateral sclerosis

• Ubiquitinylated TAR DNA-binding protein (TDP-43) accumulates

Parkinson disease

• Degradation of aplha-synuclein is a crucial question for Parkinson’s disease

• Ubiquitin proteasomal system is defective in SN affected neurons

• Autophagy-lysosomal pathway is also affected

Parkinson disease (non-monogenic)

• Dysfunction of the UPS • Reduced proteasome activity in the substantia nigra• Reduced expression of proteasomal subunits in the subsatntia

nigra • Reduced proteasome activity and expression of UPS-related

proteins in peripheral blood mononuclear cells• Altered proteasome function in toxin-based models of PD• Altered proteasome function in alpha -synuclein

overexpressing rodents• Mutated PSMC1 subunit of ATPase in a rodent model

SKP1A protein interacting E3 ligase is down-regulated in PD

Cullin

UbE2

Early PD

Late PD

• Enahncement of autophagy by rapamycin (inhibitor of mTOR) is prospective for tratment of neurodeganerative diseases

Autoimmune diseases• Autonatibodies to proteasomes in• Sjogren’ s syndrome• SLE• Rheumatoid arthritis • Autoimmune myositis• Result in decreased proteasomal activity

Inflammatory response

Inflammatory disease

• Inflammatory arthritis. Proteasome inhibition improves the arhritis score.

• Psoriasis. T-cell mediated disease, related to activation of NF-kappa. Proteasome inhibition reduces lesions.

Asthma and allergy

• Abnormal activation of of Type 2 helper cells. E3 ubiquitin ligase Itch maintains immune tolerance. Itch-deficient mice fail to block development of airway inflamamation.

Cell proliferation and cancer

Proteasomes regulate density of cardiac ion channels

• Mutations in SCNA5 gene encoding Nav1.5 channel hindering its interactions with E3 (Nedd4-2) cause arrhythmias and conduction defects

• Mutations in the gene hERG1 (K+ channel) resulting in its rapid decay cause the long QT syndrome

Heart diseasesAtrophy/Unloading

Hypertrophy Hypoxemia Heartfailure

Ub mRNA Increased Increased Increased _

E2 mRNA Increased Increased _

Heart diseases 2Atrophy/Unloading


E3 mRNAAtrogin 1

Decreased Increased Increased _

E3 mRNAMuRF1

Decreased Increased Increased _



Proteasome proteolytic Activity

Decreased Decreased Decreased

PSMB4 mRNA

Increased Increased Increased



De-ubiquitinationenzymes

Increased

Proteasome inhibitors

• Cancer treatment• Antiinflammatory action

Funding• Joint research project “Genetic studies of human diseases and

longevity in Latvian population”, sub-project “Genome-wide scanning of proteasomal gene polymorphisms and their association with autoimmune diseases” - No 10.0010/09

• National Reserach Program 2010.10.-4/VPP4 „Creation of novel means and methods for prophylaxis, treatment and diagnostics, elaboration of biomedical Technologies for improvement of social health“

• ERAF project ESS2010/110 „Creation of a method for early diagnostics of autoimmune diseases”

• Joint LV-LT-TW project “Proteasomal gene alleles as risk factors for bronchial asthma in Latvian, Lithuanian and Taiwanese populations”

Ieguldījums Jūsu nākotnē

proteasome-ubiquitin pathway in pathology

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