myosin ii paper

8/8/2019 Myosin II Paper

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Myin cntitte a perfamily f mtr prteinthat play imprtant part in eeral celllar prcee thatreqire frce and tranlcatin13. Recent analye fgenmic dataae hae yielded an increaing nmerf myin clae in ekarytic cell4,5. Myin mleclecan walk alng, prpel the liding f r prdce teninn actin filaments. Thi reqire energy, which i pridedy the hydrlyi f ATP, and reqire myin t haecatalytic ite with ATPae actiity. Myin catalytic iteare ally fnd in the amin-terminal (head) regin fthe mlecle, and they are ften actiated when myinind t actin. The carxy-terminal regin f memyin ind t and me carg in a cell, wherea theC-terminal dmain f ther myin elf-aciate intfilament, which allw their head t tether actin fila-ment and exert tenin. Myin can al act indirectlythrgh actin t ring adhein-related prtein, cha integrins, r ignal trandctin mlecle int cleprximity2,3.

Mt myin elng t cla II and, tgether withactin, make p the majr cntractile prtein f car-diac, keletal and mth mcle, in which the lidingcrridge that cnnect thick myin filament withthin actin filament pride the frce t, fr example,pmp ld, lift ject and expel aie6,7. Imprtantly,myin II mlecle that reemle their mcle cnter-part, with repect t th trctre and fnctin, areal preent in all nn-mcle ekarytic cell811. Likemcle myin II, nn-mcle myin II (NM II) ml-ecle are cmpried f three pair f peptide: twheay chain f 230 kDa, tw 20 kDa reglatry lightchain (RLC) that reglate NM II actiity and tw

17 kDa eential light chain (ELC) that tailize theheay chain trctre (FIG. 1a). Althgh thee myinare referred t a nn-mcle myin II t diting-ih them frm their mcle cnterpart, they areal preent in mcle cell, where they hae ditinctfnctin dring keletal mcle deelpment anddifferentiatin12, a well a in the maintenance f teninin mth mcle13,14.

NM II ha a fndamental rle in prcee thatreqire celllar rehaping and mement, ch a celladhein, cell migratin and cell diiin. NM II can eit actin cr-linking and cntractile fnctin, whichare reglated y phphrylatin and the aility f NM IIt frm filament, t reglate the actin cytkeletn. In thi Reiew, we pride an eriew f thetrctre and reglatin f NM II, with emphai nit central rle in cell adhein and cell migratin, andal tline the relatinhip etween NM II mtatinand dieae.

Dmin ucu f NMII

The tw gllar head dmain f NM II cntain ainding ite fr th ATP and actin and they are fl-lwed y neck regin, each f which ind the twfnctinally different light chain. The neck dmainact a a leer arm t amplify head rtatin while thechemical energy f ATP i cnerted int the mechani-cal mement f the myin head1. Thi neck dmaini fllwed y a lng -helical coiled coil, which frman extended rd-haped dmain that effect dimeriza-tin etween the heay chain and terminate in a rela-tiely hrt nn-helical tail (FIG. 1a). The rd dmain

*Department of Cell Biology,University of Virginia School

of Medicine, Charlottesville,

Virginia 22908, USA.Laboratory of Molecular

Cardiology, National Heart,

Lung, and Blood Institute,

National Institutes of Health,

Bethesda, Maryland

208921583, USA.These authors contributed

equally to this work.

Correspondence to M.V.M.

email:

[email protected]

doi:10.1038/nrm2786

Actin filament

A strand of polymerized

globular actin subunits that

winds around another strand

to form a helix. Actin filaments

are one of the three major

cytoskeletal elements of a cell,along with microtubules and

intermediate filaments.

Integrin

One of a large family of

heterodimeric transmembrane

proteins that functions as a

receptor for ECM or cell

adhesion molecules.

Non-muscle myosin II takes centrestage in cell adhesion and migrationMiguel VicenteManzanares*, Xuefei Ma, Robert S. Adelstein and

Alan Rick Horwitz*

Abstract | Non-muscle myosin II (NM II) is an actin-binding protein that has actin cross-linking

and contractile properties and is regulated by the phosphorylation of its light and heavy

chains. The three mammalian NM II isoforms have both overlapping and unique properties.

Owing to its position downstream of convergent signalling pathways, NM II is central in thecontrol of cell adhesion, cell migration and tissue architecture. Recent insight into the role

of NM II in these processes has been gained from loss-of-function and mutant approaches,

methods that quantitatively measure actin and adhesion dynamics and the discovery of

NM II mutations that cause monogenic diseases.

Cytoskeletal Motors

R E V I E W S

778 | NovEMbER 2009 | voLuME 10 www.n.m/iw/mbi

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S-1

Non-helical tail

Globular head domain(actin binding andMg2+-ATPase motor domains)

RLC Heavy chain

ELC

HMM

Coiled-coil rod domain

RLC phosphorylation

10S assembly-incompetent NM IIa

b Bipolar NM II filaments

6S assembly-competent NM II

MHC phosphorylation

Actin filament

Coiled coil

A structural domain that can

mediate oligomerization. The

myosin coiled-coil rod domain

contains two -helices that

twist around each other to

form a supercoil.

f NM II elf-aciate t frm iplar filament (anti-parallel array f myin mlecle), which are cnider-aly maller than the fnd in cardiac and keletalmcle15,16(FIG. 1b).

Three different gene in mammalian cell (myinheay chain 9 (MYH9),MYH10 andMYH14) encdethe NM II heay chain (NMHC II) prtein (NMHC IIA,NMHC IIb and NMHC IIC, repectiely), althghthere i nly ne NMHC II gene, zipper, in Drosophilamelanogaster17. We refer t the whle myin II mlecle(heay chain and light chain) a NM II and the heaychain alne a NMHC. The NMHC ifrm deter-mine the NM II ifrm, which are named NM IIA,NM IIb r NM IIC, accrdingly. Fr NM II mtr tretain their nrmal, natie and actie cnfrmatin,

the light chain mt e nd t the heay chain.Deletin f a pecific NMHC II relt in the l f thatNM II ifrm.

The mammalian heay chain pre-mRNA that aretrancried in hman and mice frm MYH10 andMYH14 nderg alternatie plicing, predminantlyin nernal tie, which increae the ttal nmerf expreed NMHC II prtein t nine18. Althghthere i eidence fr alternatie plicing f theMYH9trancript at lcatin hmlg t the inMYH10andMYH14, it i nt knwn whether thee trancriptare tranlated19. The light chain are encded y a dif-ferent et f gene, which can al nderg alternatie

plicing, and there i crrently n knwn pecificityf light chain fr particlar NMHC II. The tw lightchain pair are ery tightly, t nn-calently, ndt -helical tretche f each heay chain. Depite ha-ing a high degree f hmlgy, particlarly in theiractin-inding gllar head, the myin ifrm arepatially egregated in me area f cell, t clearlyerlap in ther20,21. A detailed elw, me celllarfnctin are ifrm-pecific, wherea ther areredndant22,23.

The hrt, nn-helical tail f NMHC II prteindiffer fficiently amng the three mammalian i-frm that peptide can e yntheized t mimic theeeqence fr the generatin f ifrm-pecific anti-die24. There i n eidence fr heterdimer frm-

atin etween the three NMHC II ifrm, and whenimmnprecipitatin experiment are perfrmed n amixtre f ifrm with pecific antidie nly theantidy-pecific ifrm i detected24. Tw impr-tant kinetic prpertie that differ amng the NM IIifrm are the actin-actiated Mg 2+-ATPae actiity(the increae in ATP hydrlyi y myin when ndt actin) and the dty rati (the time that myin ind t actin in a frce-generating tate). NM IIA hathe highet rate f ATP hydrlyi f the three NM IIifrm and it prpel actin f ilament mre rapidlythan NM IIb and NM IIC25. NM IIb ha a ignificantlyhigher dty rati than NM IIA26,27. NM IIb al ha an

Figure 1 | Dmin NM II. | The subunit and domain structure of non-muscle myosin II (NM II), which forms

a dimer through interactions between the -helical coiled-coil rod domains. The globular head domain contains theactin-binding regions and the enzymatic Mg2+-ATPase motor domains. The essential light chains (ELCs) and the

regulatory light chains (RLCs) bind to the heavy chains at the lever arms that link the head and rod domains. In the absence

of RLC phosphorylation, NM II forms a compact molecule through a head to tail interaction. This results in an assembly-

incompetent form (10S; left) that is unable to associate with other NM II dimers. On RLC phosphorylation, the 10S

structure unfolds and becomes an assembly-competent form (6S). S-1 is a fragment of NM II that contains the motor

domain and neck but lacks the rod domain and is unable to dimerize. Heavy meromyosin (HMM) is a fragment that

contains the motor domain, neck and enough of the rod to effect dimerization. b | NM II molecules assemble into bipolar

filaments through interactions between their rod domains. These filaments bind to actin through their head domains and

the ATPase activity of the head enables a conformational change that moves actin filaments in an anti-parallel manner.

Bipolar myosin filaments link actin filaments together in thick bundles that form cellular structures such as stress fibres.

R E V I E W S

NATuRE REvIEWs |Molecular cell BIology voLuME 10 | NovEMbER 2009 |779

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Tonic contractions

Sustained muscular

contractions that develop

slowly and show a prolonged

phase of relaxation.

Actomyosin filaments

Produced when bipolar myosin

filaments interact with

polymerized actin filaments to

exert tension or produce

movement.

extremely high affinity fr ADP when cmpared tther myin, and the releae f ADP frm NM IIbi markedly lwed y ackward train n the myinhead (the frce exerted n myin head y the actinfilament, ppite t the directin f myin headmement)28. Th, NM IIb i particlarly well itedt exert tenin n actin filament fr lnger perid ftime and with le expenditre f energy than NM IIA.Indeed, NM IIb ha recently een hwn t play anancillary rle in mth mcle cntractin, in whichit may e repnile fr a prtin f the tenin main-tenance dring tonic contractions13. Thee difference inkinetic prpertie etween NM IIA and NM IIb mighthelp t explain why expreing NMHC IIA nderthe cntrl f the endgenMYH10 prmter canrece me, t nt all, f the anrmalitie fnd inNM IIb-alated mice29.

Wherea the different enzymatic and mtr actiitie fNM II reide in their N-terminal dmain, the C-terminalrd and nn-helical tail determine the aemlyf myin filament and the intracelllar lcalizatin f

the NM II ifrm. Tw aemly-cmpetent dmainin the NM IIb rd that hae a crcial rle in filamentfrmatin30, and tw regin in the NM IIb rd that areinled in ifrm-pecific filament aemly, hae eenidentified31.

Experiment ing chimaera f NM IIA and NM IIbhae hwn that the intracelllar lcalizatin f thee i-frm i determined y the C-terminal 179190 aminacid, which cntain ne f the aemly-cmpetentdmain and the nn-helical tail32,33.

rguin f NM II civi

In cntrat t keletal and cardiac myin, which arereglated y a eparate et f prtein that are ndt the actin filament, the reglatin f Mg2+-ATPhydrlyi and filament frmatin f NM II inlethe reerile phphrylatin f pecific amin acidpreent in the pair f 20 kDa RLC and the heay chain.The fnctin f the ELC pair i t tailize the NMHCand there i n eidence that they nderg reerilephphrylatin.

Regulation of NM II by RLC phosphorylation.The reg-latin f NM IIA, NM IIb, NM IIC and mth mclemyin, t nt cardiac r mammalian keletal mclemyin, depend n the reerile phphrylatin fthe RLC n ser19. Thi phphrylatin eent greatly

increae the Mg 2+-ATPae actiity f myin in thepreence f actin34 y cntrlling the cnfrmatin fthe myin head35. Hweer, phphrylatin ha littler n effect n the affinity f myin fr actin36. Thr18can al e phphrylated, and diphphrylatin f theRLC n ser19 and Thr18 ften ccr in cltred cell37.The additinal phphrylatin f Thr18 in the pre-ence f phphrylated ser19 (REF. 38) frther increaethe ttal actin-actiated Mg 2+-ATPae actiity at -atrating actin cncentratin, t de nt affect themyin v

max(the maximal actin-acti ated Mg2+-ATPae

actiity f myin at atrating actin cncentratin) rthe rate f mement f actin filament in vitro39.

There i cmpelling eidence frm in vitro experi-ment that phphrylatin f the RLC al reglatethe aemly f NM II filament40. In the preence fATP, nphphrylated NM II fld int a cmpactcnfrmatin, in which ne head lck the ecndhead f the ame mlecle thrgh an aymmetricalinteractin (FIG. 1a; aemly-incmpetent frm)35,4144.The tail al fld at tw pint and interact with thehead t frther cmpact the mlecle and preentfilament aemly. Phphrylatin f RLC dirptthe headhead and headtail interactin and cae thecmpact, fater edimenting (10s) mlecle t frman elngated lwer edimenting (6s) pecie (FIG. 1a),which frm iplar filament at phyilgical inictrength (FIG. 1b). Althgh thee dramatic change cane demntrated in ltin, there i n firm eidencethat they ccr in vivo. The frmatin f aemliecmpriing 1420 myin mlecle in iplar fila-ment prmte the interactin f myin filamentwith actin filament (FIG. 1b).

Mre than a dzen kinae hae een reprted t

phphrylate the RLC f NM II (FIG. 2), incldingmyin light chain kinae (MLCK; al knwn a MYLK),Rh-aciated, ciled cil-cntaining kinae (RoCK),citrn kinae, lecine zipper interacting kinae (ZIPK;al knwn a DAPK3) and mytnic dytrphy kinae-related CDC42-inding kinae (MRCK; al knwn aCDC42bP)6,34,45,46. Thee kinae phphrylate RLC nser19, Thr18 r th, t reliee the inhiitin impedn the myin mlecle y nphphrylated RLCand the headhead interactin tlined ae. Hweer,the actiating ignal fr thee kinae differ. Ca2+calmdlin actiate MLCK, which eem t e pecificfr the NM II RLC, wherea the mall GTP-inding pr-tein RHoA actiate RoCK and citrn kinae. unlikeMLCK, RoCK and citrn kinae phphrylate eeraltrate in additin t the RLC f NM II. Fr exam-ple, althgh RoCK can phphrylate RLC directly, itprimarily act t inhiit the majr myin phphatae,prtein phphatae 1 (PP1), which i repnile frthe dephphrylatin f NM II47. Phphrylatin fthe reglatry nit myin phphatae-targetingnit 1 (MYPT1; al knwn a PPP1R12A) f thitrimeric phphatae inactiate the enzymatic actiity,relting in increaed NM II phphrylatin and actia-tin. MLCK, at leat in me cell, i mre peripherallylcalized, wherae RoCK i mre central48,49. Thi dif-ferential lcalizatin mean that the actmyin trc-

tre in the cell centre (ch a tre fire and matrefcal adhein) are mch mre tale than the at theperiphery, which are mre repnie t ptream timli.Prtein kinae C (PKC) differ frm the ae kinaein that it phphrylate RLC n ser1, ser2 and Thr9,which render the RLC a prer trate fr MLCKand therefre decreae the actiity f NM II50(FIG. 2).Fr example, PKC phphrylatin f the RLC n ser1r ser2 initiated y timlatin f platelet-deried grwthfactr receptr inhiit NM II actiity t prmte thererganizatin factomyosin filaments51. A nted elw,in additin t phphrylating the RLC, PKC alphphrylate the heay chain.

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Regulatory light chain

S100A4

1721 2 9 18 19

PKC MLCK

ROCK

Citron kinase

MRCK

ZIPK

Kinases

TRPM7 PKCPKC

PKC

CK IIKinases

NMHC IIA

NMHC IIB

NMHC IIC

1,960

1,8001,803

1,808 1,916 1,927 1,943

2,0031,936

1,977

1,9881,957 1,961 1,964

1,976

1,810 1,815

1,840 1,846

1,922 1,9331,935 1,941

1,937 1,939

1,952

1,956

1,960

1,965

1,975

Lamellipodium

A 12 m-wide band that is

made up of a network of

dendritic actin filaments and

forms the outer edge of a cell

protrusion.

Lamellum

The cell region immediately

behind the lamellipodium,

characterized by the absence

of dendritic actin and the

presence of longer, bundled

actin filaments and slow

retrograde flow.

Regulation of NM II by NMHC phosphorylation.Althgh phphrylatin f NMHC II play an impr-tant part in reglating the actiity fDictyosteliumdis-coideum myin II (reiewed in REF. 52), the rle in

reglating the trctre and actiity f mammalian NM IIare till eing defined. There are eeral phphrylatinite near the C-termini f NMHC, in th the ciled-cil dmain and the nn-helical tail, inclding ite thatare phphrylated y PKC53, caein kinae II (CK II)54and tranient receptr ptential melatatin 7 (TRPM7)55(FIG. 2; ee elw). In each cae phphrylatin f theNMHC either diciate myin filament r preenttheir frmatin in vitro. A nmer f laratrie haereprted that ser1917 in rat NMHC IIA (eqialent tser1916 in hman NMHC IIA) i phphrylated yPKC, and phphrylatin f thi ite y PKC crre-late with excyti in mat cell56,57. ser1943 in the

nn-helical NMHC tail i a trate fr phphryla-tin y CK II, and phphrylatin f thi reide, r fser1917 y PKC, inhiit the aemly f NM IIA rdint filament54.

Phphrylatin f NM IIA al affect the indingfs100A4 (al knwn a MTs1) t the NMHC. Thiprtein, which i a memer f the s100 family f Ca2+-inding prtein, prmte the inain f metatatictmr cell. binding f s100A4 t NMHC IIA preentfilament frmatin, t s100A4NMHC IIA inding ilcked y the phphrylatin f ser1943 y CK II58.An alpha kinae frm the ame family a D. discoideumNMHC kinae A, TRPM7, and it cle hmlgeTRPM6, phphrylate NM IIb and NM IIC at eeralite in the nn-helical tail59. Althgh the effect fthee phphrylatin eent n filament aemly haent yet een tdied, the mre pecific phphrylatincatalyed y TRPM7 in the helical prtin f the rdin NM IIA at Thr1800, ser1803 and ser1808 eem tdecreae filament frmatin and alter the celllarlcalizatin f NM IIA55. A yet, there i n eidence fr

the endgen phphrylatin f thee ite.Phphrylatin f NM IIb y aPKC, which i

reglated y p21-actiated kinae 1 (PAK1), wa td-ied in a prtate cancer cell line. Thi phphrylatin,which ccr n ser1937 in the nn-helical tail reginf NMHC IIb, i timlated y epidermal grwth factr(EGF) and lead t lwer filament aemly in cltredcell53. Recently, phphrylatin f th the nn-helical tail and the rd f the NMHC ha een reprtedfr NM IIC. Phphrylatin increae the lility fNM IIC and al ha an effect n celllar lcalizatin60.Th, it i clear that cniderale reglatin f NM IIccr thrgh phphrylatin f the heay chain,particlarly in the tail regin (FIG. 2). The cntinedcharacterizatin f the rle f thee different phph-rylatin eent n NM II fnctin and ifrm-pecificreglatin hld prdce imprtant new inight.

NM II in c migin, dhin nd pi

NM II i an imprtant reglatr f adhein andplarity in cell migratin. Thee prcee inle thedynamic remdelling f the actin cytkeletn andthe interactin f the cell with it enirnment. Each f theNM II ifrm affect thee prcee differently, adiced elw.

NM II regulates protrusion and cell migration. In migrat-

ing cell, actin rganize int eeral ditinct trctreand it plymerizatin in celllar prtrin driecell migratin. Prtrin generally cntain tw actin-aed trctre: the lamellipodium and the lamellum61.Different clae f reglatry mlecle rganize actinin thee tw trctre. The actin ncleatr Arp2/3generate the lamellipdim. In vitro, Arp2/3 indt the ide f actin filament and generate rancheat a fixed angle (70) t frm a dendritic netwrk62.Hweer, the in vivo data are till nder deate. A recenttdy ha reprted actin filament with ariale angle(1590) in the lamellipdim, which challenge thedendritic netwrk ntin63. The relatie pitining f

Figure 2 | rin NM II iin nd imn min. Multiple kinases,

including myosin light chain kinase (MLCK; also known as MYLK), Rho-associated, coiled

coil-containing kinase (ROCK), citron kinase, myotonic dystrophy kinase-related

CDC42-binding kinase (MRCK; also known as CDC42BP) and leucine zipper interacting

kinase (ZIPK; also known as DAPK3) can phosphorylate the regulatory light chain (RLC)

of non-muscle myosin II (NM II) on Ser19 or on Thr18 and Ser19 to activate it. Protein

kinase C (PKC) can phosphorylate the RLC on Ser1, Ser2 and Thr9 to inhibit NM II. Human

RLC is encoded by myosin light chain 9 (MYL9). In addition to RLC phosphorylation,

NM II filament assembly is regulated by phosphorylation of the NM II heavy chain

(NMHC II) coiled-coil and tail domains. The phosphorylation sites and the correspondingkinases, including transient receptor potential melastatin 7 (TRPM7), PKC proteins

and casein kinase II (CK II), are shown for human NMHC IIA, NMHC IIB and NMHC IIC.

Phosphorylation of NMHC II by CK II blocks the binding of S100A4 (also known as MTS1)

to the tail of NM II to prevent it from inhibiting myosin filament assembly. Human

NMHC IIA is encoded by myosin heavy chain 9 (MYH9), NMHC IIB is encoded by MYH10

and NMHC IIC is encoded by MYH14. Note that each phosphorylation site and the kinase

that phosphorylates it are depicted in the same colour.

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Blebbistatin

A small-molecule inhibitor

with high affinity for myosin II

that blocks myosin in an

actin-detached state.

Pliability

The mechanical properties

of the cellular environment.

The environment can show low

pliability (that is, be elastic or

compliant) or high pliability

(that is, be rigid or stiff).

the lamellipdim and the lamellm i al nclear. Itwa recently prped that thee tw actin netwrkerlap at the leading edge, with the lamellipdimperimped nt the lamellm64, t a mre traditinal

iew i that the lamellipdim i patially anterir t thelamellm61. In the lamellm, actin filament caleceint thicker ndle (FIG. 3a). The lamellipdim and thelamellm are kinetically different: the lamellipdim iditingihed y a fat retrgrade flw f actin, whereathe lamellm exhiit lwer retrgrade flw. Thecnergent zne etween the tw i characterized yactie deplymerizatin f the dendritic netwrk andthe rerganizatin f actin64,65(FIG. 3b).

NM II de nt reide in r eem t play a part inthe phyical rganizatin f the lamellipdim, tit can affect the net rate f celllar prtrin 22,64,66(FIG. 3b). When NM II i kncked t, kncked dwny mall interfering RNA r inhiited with blebbistatin ,large actin ndle are nt ered in the lamellm,wherea the lamellipdim remain intact 64. In manycell, adancement f the prtrin i interrpted y

NM II-generated pae67 that are aent when myini inhiited r deleted22.

one hypthei fr the rle f NM II in prtrinfrmatin i that NM II generate the retrgrade flw factin in the lamellm, which i cnnected t the lamelli-pdim64,68(FIG. 3b). Inhiitin f NM II actiity with le-itatin, r genetic deletin f NM II, greatly decreaethe rate f actin retrgrade flw in the lamellm64,66and inhiit calecence f actin int prt-ndleat the lamellipdimlamellm interface69,70, whichincreae prtriene22,66,71(FIG. 3b). NM II-generatedretrgrade flw cnter the actin plymerizatin-mediated adancement f the leading edge and thereyredce the ered prtrin rate. Th, peridiccntractin f the lamellipdim cld cyclically inhiitthe prtrin rate. In thi mdel, the prtrin ratei the difference etween the actin plymerizatin andthe retrgrade flw rate. Adhein mdlate thi al-ance y cpling actin t the tratm, therey creatingtractin pint that cnter actin retrgrade flw72. scha mechanim premaly increae the rate f prtriny dierting the frce created y the retrgrade flw fthe actin t the tratm. Th, the linkage etweenactin and the tratm cntitte a mleclar cltch.Thee eratin, firt made in nernal grwth cnet later extended t many ther cell type, cntittethe cltch hypthei7274, which integrate adhein,

retrgrade flw and actin plymerizatin.

NM II in integrin-mediated adhesion.NM II i di-penale fr the aemly and diaemly f nacentadhein inide the lamellipdim75,76. Hweer, it ireqired fr their eqent matratin, which inleelngatin and grwth. Adhein matre alng thinactin ndle that riginate near the tranitin zne atthe lamellipdim and lamellm interface75(FIG. 3b). Thepraility that a nacent adhein in the lamellipdimmatre, rather than diaemle, eem t depend nthe leel f actie NM II75. Hweer, the mechanim ywhich adhein elngate and grw, and hw NM II

mediate thi matratin, i nt cmpletely nder-td. The actin ndling fnctin f NM II eem te fficient, at leat fr the initial tage f adheinmatratin, ecae mtr-deficient NM II mtantthat till ind t actin pprt grwth and elngatinf adhein75.

An integrinactin linkage tranlate the effect fNM II t adhein and mediate adhein frmatinand matratin. Different adhein prtein eem tparticipate in thi linkage, inclding -actinin, inclinand talin (FIG. 4). There are tw nn-exclie hyptheefr hw NM II mediate adhein matratin. one ithat NM II ndle actin filament, and a a cne-qence adhein prtein at the end f thee actin fila-ment are rght tgether and cltered. Thi increaemleclar interactin etween adhein prtein andrelt in increaed integrin aidity (the cminedtrength f mltiple integrinligand interactin) andignalling. Fr example, the actmyin-drien indingf inclin t talin indce integrin cltering77. The ec-nd hypthei i that NM II-generated frce indce

cnfrmatinal change that expe cryptic indingr actiatin ite in key adhein cmpnent 7880.Talin, an actinintegrin linkage prtein, ind inclinwhen mechanically tretched79 and i reqired t tran-late NM II-generated frce t the tratm81(FIG. 4).The adhein caffld prtein CRK-aciated -trate (p130CAs; al knwn a bCAR1) i al acti-

ated when tretched78. Frthermre, th end f theadheie linkage repnd t frce. Firnectin nder-ge cnfrmatinal change indced y mechanicalfrce that relt in the expre f it cryptic ite 82,and integrin are actiated y tenin80. Finally, NM IIitelf can al nderg frce-dependent cnfrmatinalchange83. Interetingly, the frce-dependent mdlatinf mechanreactie NM II mlecle al impinge nther ignalling mlecle that are nt mechaneni-tie themele. It ha recently een prped that NM IIal cntrl EGF-indced paxillin phphrylatinand it eqent dephphrylatin, which reglatecelllar prtrin and retractin84. In additin, zyxinaciate and diciate frm adhein in repne textracelllar frce85, and fcal adhein kinae (FAK),a prminent adhein-aciated tyrine kinae, ireqired fr drtaxi (that i, the tendency f cell tmigrate tward tiffer trate)86.

NM II i al an integral part f the celllar repnet mechanical timlatin. It react t mechanical tim-

li thrgh celllar ignalling pathway that reglate itactiatin. In thi way, NM II pride a cnergencepint fr external and cell-generated frce. Fr example,applicatin f external frce prdce pt-tranlatinalmdificatin ch a phphrylatin, r cnfrma-tinal change in different ignalling mlecle, whichinhiit prtrin frmatin and lead t adhein mat-ratin and actin filament ndling 87. Cnerely, cellin which NM II i inhiited d nt repnd t externalfrce88. In additin, cell ene trate pliability, inpart thrgh the actiatin f NM II y RLC ph-phrylatin89,90. When cell are plated n lw-pliailitytrate, NM II actiatin i lw, actin i nt highly

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http://www.uniprot.org/uniprot/P56945http://www.uniprot.org/uniprot/Q15942http://www.uniprot.org/uniprot/Q15942http://www.uniprot.org/uniprot/P56945


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Nascent adhesion

b Protrusion

c Trailing edge

a Polarized migrating fibroblast

d Nucleus

Stressfibre

Trailing edge

Leading edge

NM II-independent,fast retrograde flow

NM II-dependent,slow retrograde flow

Maturingadhesion

NM IIB

Nucleus

Dorsalarch

MRCK

PKCGSK3

CDC42

PAR6PAR3

MTOC

Perinuclearactin

+

+Dynein

Dynactin

Microtubule

Arp2/3complex

Dendriticactin

Lamellipodium

Lamellum

Interface

Actinfilament

Maturingadhesion

NM II

-Actinin

Actinfilament

NM IIA

Maturingadhesion

EB1

APC

DIAPH

1Dynamin

Microtubule

Calpain-mediatedproteolysis (release)

Microtubule-mediatedrelaxation

NM IIA-mediated

retraction

Disassemblingadhesion

Figure 3 | Mi NM II in miin. | A polarized, migrating fibroblast. Areas of the cell in which

non-muscle myosin II (NM II) has an active role are boxed and expanded in parts bd. b | NM II regulates retrograde flowin the lamellum and promotes adhesion maturation, thereby limiting protrusion. Nascent adhesions form in the

lamellipodium, in which dendritic actin branching mediated by the Arp2/3 complex also occurs. At the lamellipodium

lamellum interface, actin is depolymerized or bundled and adhesions disassemble or mature. A schematic of adhesions

maturing in the lamellum is also shown. NM II localizes to actin bundles contacting growing adhesions, forming a striated

pattern with -actinin. In other cells, such as in neuronal growth cones, NM II may have a more direct role controllingretrograde flow in the peripheral zone151. | NM II participates in adhesion disassembly at the rear of the cell.

NM IIA-mediated contraction, calpain-dependent cleavage of adhesion components and microtubule targeting

coordinately induce adhesion disassembly. d | NM II has a role in nuclear positioning and orienting the microtubule-

organizing centre (MTOC) and Golgi, which are important for cell polarization. NM II is thought to act in concert with the

CDC42partitioning defective 3 (PAR3) or PAR6protein kinase C (PKC) glycogen synthase kinase 3 (GSK3) pathway topolarize the cell. Myotonic dystrophy kinase-related CDC42-binding kinase (MRCK; also known as CDC42BP) activates

NM II and regulates its effect on nucleus repositioning. APC, adenomatous polyposis coli; DIAPH1, diaphanous 1;

EB1, end binding protein 1 (also known as MAPRE1).

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AM MYPT1

-Pix

-Actinin

Zyxin

Arp2/3

TalinCRK

GIT

ROCK

Rac

RHOA

p130CAS

Paxillin

DOCK180

RhoGEF

FAK

Src

PP1Myosinphosphatase

Mechano-responsivemolecules

Integrin

Talinp130CAS

Vinculin

Vinculin

FAK

-Integrinsubunit

-Integrinsubunit

NM II

Actin

Plasma membrane

ECM

ndled and adhein are mall. A rigidity increae,NM II actiatin increae, actin i iily ndled andadhein ecme large and elngated.

Adhesive signalling in NM II activation. NM II infl-ence adheie ignalling thrgh cltering and/rcnfrmatinal change, t adheie ignalling alcntrl NM II actiatin (FIG. 4). Fr example, integrinactiatin indce Tyr phphrylatin f the adheinadaptr paxillin n Tyr31 and Tyr118 and f FAK nTyr397. Thee phphrylatin trigger the actiatinand recritment t adhein f ignalling intermediatech a the p130CAsCRK and G prtein-cpled recep-tr kinae interacting ArfGAP (GIT)-Pix (al knwna ARHGEF7) cmplexe, relaying actiatin ignal tRh GTPae, particlarly Rac (reiewed in REFS 9193).

Amng ther fnctin, Rac trigger actin plymer-izatin thrgh the Arp2/3 cmplex and al inhiitNM II actiatin (FIG. 4). other ignalling pathway acti-ated y adhein hae the ppite effect and prmteNM II actiatin thrgh RHoA94,95. Rac i actiated yignal generated in mall adhein cle t the lead-ing edge that actiely nderg trner and reaemle.RHoA actiatin mediate actin filament frmatin andadhein matratin a the prtrin me awayand the adhein ecme mre central. Thi indcefrther actiatin f NM II and the calecence f thickactmyin ndle. Dring adhein matratin, Racignalling decreae and RHoA-mediated actiatin fNM II increae, which relt in enhanced actmyinndling87,89,96.

NM II i a dal reglatr f prtrin, thrgh iteffect n actin retrgrade flw and adhein-generatedignalling 22,66. Increaed actiatin f NM II reltin large actin ndle and tale adhein, decreaedignalling t Rac and decreaed prtrin. Lwer leelf actie NM II relt in le actin ndling and increaed

prtrin. Thi can explain, in part, the nderlyingdifference in migratin amng different cell type.specifically, highly migratry cell ch a lekcyte dnt exhiit large adhein97, praly reflecting lw leelf NM II actiatin r an intrinic inaility t rearrangetheir actin cytkeletn int large ndle, wherea lwming cell ch a firlat hae adhein that tendt matre int large, elngated trctre a a relt fNM II actiatin and rt actin ndling.

NM II actiatin prmte adhein matratinthrgh it actin ndling and cntractile actiitie.Cycle f Rac and Rh actiatin inactiate and acti-

ate NM II, relting in prtrin and actin ndling,repectiely. The rle f NM II in adhein depend nit aility t exert frce n adhein, een thgh it int phyically preent in the adhein t attache tthe actin ndle with which adhein are aciated22.Th, NM II inflence adhein frm a ditance.

NM II determines the polarity of migrating cells.Directinal migratin reqire an initial ymmetry reakand the plarizatin f the migratry machinery. Therei trng eidence that NM II cntractility initiate ym-metry reaking y frming the prpectie rear f thecell98100, which allw fr prtrin t ccr at the pp-ite end. The ignal leading t pecificatin f the cellrear and prtrin are patially egregated101.

The leading prtrin reide at the cell frnt, andthe cell rear ften adpt a defined mrphlgy, cha flat and parallel t the leading edge in keratcyte, rlagging and trianglar in me firlat. The mlec-lar cmpitin and rganizatin f thee frnt and rearcmpartment i ditinct102, particlarly with regard tthe actin cytkeletn and the adhein in thee regin.The tail regin i ally cmpried f larger actin fila-ment ndle that pprt adhein diaemly andretractin f the rear, and large, tale adhein thatd nt ignal t Rac. by cntrat, adhein at the frntare maller and mre dynamic and mediate rt Racignalling, which drie prtrin.

Figure 4 | NM II in inin-mdid din. Integrins that are bound to the

extracellular matrix (ECM) are linked to the actin cytoskeleton through an actin linkage

that is formed by multiple molecules, including talin, vinculin and -actinin. Kinases suchas focal adhesion kinase (FAK) and Src, and adaptors such as paxillin, are also recruited

and trigger the downstream activation of Rho GTPases such as Rac through adaptor and

activating proteins. Representative pathways and associations are shown, including

the activation of Rac through paxillin by the CRK-associated substrate (p130CAS; also

known as BCAR1) CRKdedicator of cytokinesis 1 (DOCK1; also known as DOCK180)

and G protein-coupled receptor kinase interacting ArfGAP (GIT)Pix (also known asARHGEF7) pathways. Activated Rac induces actin polymerization through the Arp2/3

complex, which can also interact with some of the molecules of the actin linkage, such as

vinculin and FAK. Rac is also thought to locally inhibit NM II activation. The activation of

RhoGEFs by integrins, and the subsequent activation of RHOA and Rho-associated,

coiled coil-containing kinase (ROCK), activates NM II. ROCK activates NM II directlyby phosphorylating the regulatory light chains (RLCs) or by inactivating myosin

phosphatase, which in turn promotes RLC dephosphorylation. The pathways are spatially

and temporally regulated. Additionally, the activation and inactivation of NM II itself

affects adhesive signalling by triggering conformational changes in the mechano-

responsive molecules shown (pink boxes), which induces the clustering of the indicated

adhesion proteins (blue boxes) by reinforcing or weakening the linkage of the adhesion

and the actin cytoskeleton. AM, adaptor module; MYPT1, myosin phosphatase-targeting

subunit 1 (also known as PPP1R12A); PP1, protein phosphatase 1.

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Nucleus

RHOA

NM IIA

RHOA

NM IIA

Cadherin signalling(contraction)

4 Integrinclustering

ECM

Contactinitiation(actinpolymerization)

3

Contactcompaction(NMI

I)

Cadherinclustering(NM IIA)

+

Cadherin

Integrin

Actin

1 Apical constriction(contraction)

2 Nuclear positioning(NM IIB)

Rac-driven actinpolymerization

Fibrillogenesis

Microtubule-organizing

centre

A eukaryotic cell structure from

which microtubules emanate.

During mitosis, the MTOC

organizes the mitotic spindle.

Cadherin

A member of a family of type I

transmembrane receptors that

mediate cellcell adhesion

through homophilic

interactions.

NM II actiatin i eential fr the frmatin f adefined rear cmpartment. NM II lcalize t the pte-

rir part f migrating lekcyte and D. discoideum103,104.Here, it create tale adhein and highly ndledactin, which preent prtrin and therey generatenn-prtrie area that cntitte the ide and thetrailing edge f the migrating cell33,98.

In migrating firlat, the NM II ifrm haedifferent rle in cell plarizatin. NM IIA i dynamicand aemle actmyin ndle in prtrin22,66.by cntrat, NM IIb incrprate int prefrmed actinndle and remain tatinary, defining the centreand rear f the migrating cell33. In thi manner, thecperatie fnctin f NM IIA and NM IIb indceig, nn-dynamic actmyin trctre that define

the nn-prtrie part f the cell (the centre and thetrailing edge), wherea dynamic filament in prtrdingregin f the cell are cmpried f NM IIA alne 33.NM IIA pecifically mediate retractin f the trailingedge dring migratin105 (FIG. 3c). When NM IIA iinhiited, cell ecme elngated wing t their failret retract105,106.

In additin t difference in actin and adheinrganizatin and fnctin, the pitin f the ncle,the microtubule-organizing centre (MToC) and the Glgiapparat are al hallmark f migratry cell plariza-tin. The MToC and Glgi apparat repitin in frntf the ncle tward the directin f prtrin107.Data frm experiment in which NM II actiity wainhiited y leitatin reeal that NM II al reglatencle repitining108(FIG. 3d). NM IIb eem t play aprminent part in nclear dynamic dring migratin acell depleted f NM IIb exhiit mltidirectinal prtr-in109, lack a clear frnt and ack, hae a milcalizedGlgi and MToC, exhiit inapprpriate rtatin f thencle and fail t repitin the ncle prperly dr-

ing plarized migratin22. one hypthei i that NM IIbdirectly anchr the perinclear actin at the ncle yinteracting with nclear tranmemrane receptr cha neprin, which are inled in nclear reditri-tin dring cell migratin110,111. Anther piility ithat NM IIb pride tenin r trctral rigidity t theperinclear actin and thi frce preent inapprpriatertatin f the ncle and me it frward (FIG. 3d).

NM II in cellcell adhesion and morphogenesis.NM IIi nt nly pital in cntrlling integrin-mediatedadhein and migratin, it al reglate epithelialcell adhein, plarizatin and mrphgenei. Well-defined cellcell jnctin are a key featre f epithelialheet and repreent a different type f adheie trctrethat i cntrlled y NM II. Althgh thee cellcell jnc-tin e cadherins a the main adhein receptr, theycntain caffld and ignalling intermediate analgt the fnd in integrin-mediated cmplexe. In aggre-gate, epithelial cell hae apical and alateral regina well a integrin-aed adhein t the extracelllarmatrix (ECM) at the aal rface (FIG. 5). Epithelial cellheet can me a mlticelllar chrt, with the leadingcell hwing prtrin and the trailing cell retract-ing, r they can detach frm the heet and me awaya ingle cell. In free edge f the heet, the migratingcell nderg a plarity witch frm apicaal (FIG. 5) t

frntack(FIG. 3).NM II cntrl the frmatin and taility f the

cellcell jnctin. NM IIA i reqired fr cadherincltering112,113(FIG. 5) and the taility f the cellcell

jnctin. The initiatin f the cntact i drien y actinplymerizatin114, and NM II-drien cntractility medi-ate the later tage f cntact frmatin (cmpactin).Actie RHoA and phphrylated RLC lcalize t theperiphery f the jnctin and drie the cntractin andcmpactin f the cellcell cntact114(FIG. 5). RHoAactiatin, which actiate NM II, al mediate cntactinhiitin f mement (that i, the inhiitin f pr-trin y cellcell cntact)115. NM IIA praly play

Figure 5 | r NM II in ii izin. The different roles of

non-muscle myosin II (NM II) in epithelial cell polarization. NM II is involved in apical

constriction (step 1), which leads to important morphogenic movements such as dorsalclosure (closure of the epidermis over the amnioserosa during embryogenesis)in

Drosophila melanogaster. In addition, NM II regulates nuclear positioning (step 2), in a

similar manner to how it does this in fibroblasts (see FIG 3). NM II and RHOA signalling

also stabilize cellcell contacts by reinforcing them through actin cross-linking (known

as contact compaction; step 3). The initial contacts are formed as a result of Rac-driven

actin polymerization, but NM IIA is required for contact formation and reinforcement

and cadherin clustering. NM II also mediates crosstalk between homophilic cadherin

contact-initiated signalling and extracellular matrix (ECM) remodelling triggered by

integrin activation and clustering (step 4).

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Convergent extension

A phase of gastrulation in

which layers of cells intercalate

(converge) and become longer

(extend). Extension is driven by

a rearrangement of the cells of

the ventral part of the

epithelium, which converge

towards the ventral midline.

Fibrillogenesis

A cell-induced reorganization

of the surrounding ECM

molecules into bundled fibres.

Macrothrombocytopenia

A condition that is

characterized by enlarged

blood platelets that are

approximately the size of red

blood cells, are reduced in

number and result in

prolonged bleeding times.

Haploinsufficiency

A state in which the loss of onlyone allele of a gene detectably

disables the encoded proteins

function.

Ectopia cordis

A congenital displacement of

the heart outside the thoracic

cavity and chest wall.

Omphalocele

A protrusion that occurs at

birth, whereby part of the

intestine protrudes through a

large defect in the abdominal

wall at the umbilicus.

a imilar part dring the frmatin f T cellantigen-preenting cell cnjgate in antigenic preentatin116.

NM II-drien mechanim al gern the three-dimeninal rganizatin f epithelial tie. In threedimenin, the frce applied t a ingle cell i ptentiallymlti-directinal, rather than planar r ne-dimeninal.The rigidity f the celllar micrenirnment i crcial.There i mch eidence that NM II i part f the mecha-nim y which the cell th generate and repnd tfrce. Three dimeninal repne hae een tdied inXenopus laevis and D. melanogasterdring early emry-nic deelpment and rgangenei. In th ytem,the ame general principle f reglatin f NM II apply.In D. melanogaster, NM II (NMHC encded yzipper)i actiated y phphrylatin f the RLC (encdedyspaghetti squash), which i nder the cntrl f Rhkinae (RoK)117119. NM II i al implicated in epithelialprcee inling cntractin, ch a gatrlatin120,trachea frmatin121,122, entral frrw frmatin123,124,dral clre117 and mrphgenei f the erterateneral te124126, a well a in the rerganizatin f cell

cntact in the plane f the epithelim dring convergentextension127,128. In D. melanogastereye imaginal dicfrmatin, mrphgenetic ignalling i nder the cn-trl f Hedgehg, which actiate NM II thrgh theRHoARoK pathway129.

Finally, NM II pride the tenin and tractin thatcell e t frm and remdel a fnctinal ECM dringtie mrphgenei and wnd repair. Thi incldeNM II-pwered cllagen fire remdelling 130 andfirnectin fibrillogenesis82,131. Recently, a link etweencellcell cntact rganizatin and firillgeneiwa prped. Actmyin rerganizatin drien ycadherin tranlate int ECM remdelling thrghintegrin, ggeting that cadherin-generated ignalreglate integrin actiatin y mdlating cytkeletaltenin132(FIG. 5).

NM II muin nd di

An early indicatin that NM IIA, NM IIb and NM IIChae different rle dring deelpment came frm td-ie in mice hwing that dirptin f the gene encd-ing the heay chain f thee prtein (MYH9, MYH10and MYH14, repectiely) lead t different phentype.NMHC IIA germline-alated mice fail t frm a plar-ized iceral endderm and hw defect in cellcelladhein that relt in death y emrynic day (E) 6.5,efre rgan frmatin133. Mice in which NMHC IIb

ha een deleted r mtated rie t E14.5 and hwcardiac and rain defect, which reflect the enrichmentf the NM IIb ifrm in thee rgan in wild-typemice134,135. A nted elw, the rain defect were de tfailre in th cell adhein and cell migratin.

T decipher the rle f NM II in adhein and migra-tin, eeral inetigatr ed mtant that mimic themtatin fnd in hman inMYH9 andMYH14 andexpreed the mtant NMHC IIA and NMHC IIC pr-tein in mice, D. melanogasterand cltred cell. Tdate, almt 40 mtatin in NMHC IIA, ditritedamng the head and rd dmain, hae een reprtedt caeMYH9-related dieae136(TABLE 1). All f the

patient with thee dieae were heterzyg frMYH9 mtatin. one f the mt cmmn anrmali-tie in patient withMYH9-related dieae i aciatedwith dyfnctin f the ld platelet, which play animprtant part in ld cltting and clt retractin, andaffected patient ffer frm macrothrombocytopenia.Platelet frm patient with mtated NM IIA hae ananrmal cytkeletal cmpitin and fail t frmand/r rerganize cytkeletal trctre n timla-tin with the thrmin receptr actiating peptide137.The initial hape change and internal cntractin f theplatelet fllwing timlatin reqire NM IIA actiity,which in trn i actiated y RLC phphrylatin138,139.bacliral-expreed catalytic fragment (heay mer-myin) f NM IIA mtant that mimic the hmanmtatin in the mtr dmain (N93K and R702Cin NMHC IIA), hae a redced actin-actiated Mg2+-ATPae actiity and an inaility t tranlcate actin fila-ment in vitro140. It i therefre likely that impairmentf NM IIA mtr fnctin cntrite t the plateletdefect in thee patient.

bth haploinsufficiency and the aility f mtantmyin t interfere with wild-type myin (dminant-negatie effect) hae een prped a mechanim ywhich mtated NM IIA lead tMYH9-related dieae.A redctin in wild-type NM IIA, accmpanied y nr ery lw leel f the mtant frm f NM IIA, haeen ered in platelet and their precrr (mega-karycyte) frm patient withMYH9-related dieae.Hweer, th haplinfficiency and dminant-negatie effect hae een reprted in different tiefrm the ame patient. Haplinfficiency wa hwnt e the mechanim y which mtated NM IIA lead tMYH9-related dieae in platelet, and dminant-negatie effect were hwn t e the mechanimin granlcyte141,142. Mice with NM IIA pecificallyalated frm megakarycyte hae thrmcytpeniawith large platelet imilar t the in patient withMYH9-related dieae, a well a defect in cytkeletalrerganizatin143,144.

s far there hae een n reprt f mtatin inMYH10, which encde NMHC IIb, aciated withhman dieae. T etalih a ptatie me mdelfr ch dieae, mice carrying the R709C mtatinin NMHC IIb (a hmlge f the R702C mta-tin in hman NMHC IIA) hae een generated 145.Hmzyg mtant mice die y E14.5 and hwmajr mrphgenetic defect, inclding a failre t

cle the entral dy wall, relting in a cleft palate,ectopia cordis and a large omphalocele, a well a defectin heart and diaphragm deelpment (X.M. and R.s.A.,nplihed eratin). Thee anrmalitie arereminicent f a rare hman yndrme knwn aPentalgy f Cantrell146.

Mice alated fr NM IIb, in cntrat t mice withpint mtatin in NMHC IIb, deelp hydrcephal(in which circlatin f the cereral pinal flid ilcked), ne f the mt cmmn cngenital dieaethat affect hman (13 per 1,000 lie irth). Thi iecae l f NM IIb cae dirptin f apical cellcelladhein f the nerepithelial cell that rder the

R E V I E W S




10/13

pinal canal147.Interetingly, thi phentype can ereced y exprein f the NMHC IIbpint mtantR709C, which ha a mtr that i deficient in enzymeactiity, r y ing gene tittin t replace NMIIb with NM IIA29,147. NM IIA i nrmally nt detectedin the nerepithelial apical adhein cmplex and

demntrate markedly increaed enzymatic mtrprpertie cmpared with NM IIb, a well a a decreaeddty rati (ee ae). Therefre it i likely that thetrctral prpertie f NM IIb, rather than it enzy-matic mtr actiity, are eential fr maintaining theintegrity f cellcell adhein in the nerepithelial cellthat line the pinal canal10.

Finally, fie mtatin in MYH14, which encdeNMHC IIC, hae een reprted t ccr in th themyin head and tail dmain. All f thee mtatinrelt in deafne148,149. The in vivo fnctin f NM IICi largely nknwn and mice alated fr NM IIC hwn i anrmalitie (X.M. and R.s.A., nplihederatin).

The pathphyilgical rle f NM II are till ntflly ndertd. Althgh there i n eidence frheterdimer frmatin amng the NMHC ifrm,there i eidence fr clcalizatin f NM II ifrmin filament. Thi raie the intereting piility that amtant ifrm might interfere with a ecnd (r third)wild-type ifrm.

stdie frm genetically maniplated me mdeldemntrate that NM II i inled in cellcell adheinand cell migratin in vivo. In maintaining the integrity fcellcell adhein, NM IIA and NM IIb are fnctinallyinterchangeale and thi fnctin eem t e independentf their actin-actiated Mg2+-ATPae mtr actiity. Indriing cell migratin, hweer, the ATPae actiity fthe myin mtr i eential and NM IIA and NM IIbcannt titte fr each ther.

Cncuding m

Thrgh it effect n actin ndling and cntractility,NM II act a a mater integratr f the prcee thatdrie cell migratin and adhein. It i al an impr-tant end pint n which many ignalling pathwaycnerge, largely thrgh Rh GTPae. NM II itelfi tightly reglated at different leel, inclding at theleel f flding, myin filament aemly and dia-emly, actin inding and ATPae and mtr actiity.The reglatin f the actin cytkeletn y NM II cn-trl mltiple interrelated prcee, ch a migratin,cellcell and cellmatrix adhein, cell differentiatin,tie mrphgenei and deelpment. Frthermre,NM II i at ne end f the reglatry feedack lpthat cntrl the actiatin f NM II wn ptreamignalling pathway, inclding the cnfrmatinal acti-atin f adhein mlecle and actin rganizatin. The

imprtance f NM II i highlighted y the prfnd andaried phyilgical effect f genetic deletin f NM IIifrm in animal mdel and the high nmer fnatrally ccrring mtatin in the gene encding theNMHC II prtein that cae hman dieae.

The recent interet in the celllar and tie fnctinf NM II ha prdced many reealing and inightfleratin, althgh many aic and tranlatinal qe-tin remain. Fr example, the patitempral reglatinf NM II y celllar lcalizatin and actiatin f itreglating kinae in different cell and tie ha impr-tant ramificatin in cntrlling the NM II fnctin tneed frther inetigatin. Emerging eidence trngly

Table 1 | th 39MYH9muin cid wihMYH9-d di*

exn Min cini (in ddiin mmbni)

Head

Exon 1 W33C and P35A152 or A95T Dhle-like inclusions

N93K Dhle-like inclusions and deafness

S96L Deafness and nephritis

Exon 10 K373N Dhle-like inclusions

Exon 16 R702C Dhle-like inclusions, deafness, nephritis andcataracts

R702H Deafness and nephritis

R705H Deafness

Q706E or R718W|| Dhle-like inclusions

Rod

Exon 24 G1055_Q1068del153 Dhle-like inclusions, deafness and nephritis

E1066_A1072del Dhle-like inclusions, deafness and cataracts

E1066_A1072dup154 Dhle-like inclusions and cataracts

E1084del153 Dhle-like inclusions

Exon 25 V1092_R1162del orT1155A||

Dhle-like inclusions

S1114P Nephritis

T1155I Dhle-like inclusions, deafness and nephritis

Exon 26 R1165C Dhle-like inclusions, deafness and cataracts

R1165L Dhle-like inclusions, deafness and nephritis

L1205_Q1207del Dhle-like inclusions

Exon 30 R1400W Nephritis

D1424Y, D1424N, D1447V||

or D1447HDhle-like inclusions

D1424H Dhle-like inclusions, deafness, nephritis andcataracts

K910Q and D1424H155 Dhle-like inclusions, deafness, nephritis andhypertension

Exon 31 V1516L Dhle-like inclusions

Exon 37 I1816V Dhle-like inclusions and nephritis

Exon 38 E1841K Dhle-like inclusions, deafness, nephritis andcataracts

Exon 40 G1924fs or D1925fs Dhle-like inclusions

Non-helical tail

Exon 40 P1927fs, R1933fs|| orD1941fs

Dhle-like inclusions

R1933X Dhle-like inclusions and nephritis

E1945X Dhle-like inclusions and deafness

*See also REF. 136. Basophilic spindle-shaped inclusion bodies in the granulocytes. Originallyreported as K371N. ||Clinical features listed are based on common findings for myosin heavychain 9 (MYH9)-related diseases, but were not described in the reference. Deletion of twodifferent nucleotides both cause D1925fs. del, deletion; dup, duplication; fs, frame shift.

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indicate that mechanical frce praly remdelthe tmr cell micrenirnment thrgh NM II taffect tmr prgrein and metatai150, t theprecie mechanim y which NM II repnd t and gen-erate the micrenirnment remain t e elcidated.In additin, the ntin that NM II i a central integratrf external frce dring cell and tie differentiatin, a

well a migratin, pen p the piility f manip-lating th the rigidity f the micrenirnment and theexprein and actiatin f NM II t gide cell prlifera-tin and differentiatin dring tie regeneratin andtem cell tranplantatin. In thi way, the maniplatin fNM II and it reglatr cntitte a ptentially alaleapprach in regeneratie medicine.

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AcknowledgementsThe authors apologize for the numerous studies left out owing

to journal limits on the number of references. We thank M. A.

Conti and J. R. Sellers (National Heart, Lung and Blood

Institute (NHLBI)) for helpful suggestions and critical reading

of the manuscript. This work was supported by the US

National Institutes of Health (NIH) grant GM23244, the Cell

Migration Consortium grant U54-GM064346 (A.R.H.), and

the Division of Intramural Research, NHLBI, NIH (R.S.A.).

DataBasesEntrez Gene:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=gene

MYH9 | MYH10| MYH14|MYL9

UniProtKB:http://www.uniprot.org

EGF|MLCK | MYPT1 | p130CAS | PAK1|RHOA|S100A4|

TRPM7 |ZIPK | zyxin

FUrtHer INForMatIoNAlan Rick Horwitzs homepage:http://people.virginia.

edu/~afh2n/

Robert S. Adelsteins homepage: http://dir.nhlbi.nih.gov/

labs/lmc

all lINks are actIve IN the oNlINe pDf

R E V I E W S
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=genehttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=genehttp://www.uniprot.org/uniprot/P35579http://www.uniprot.org/uniprot/P35580http://www.uniprot.org/uniprot/P35580http://www.uniprot.org/uniprot/Q7Z406http://volumes/npgmac/Review%20Journals%20Production/Subbed%20articles/Vicky/Reviews/November%202009/Vicente-Manzanares/DATABASEShttp://volumes/npgmac/Review%20Journals%20Production/Subbed%20articles/Vicky/Reviews/November%202009/Vicente-Manzanares/DATABASEShttp://www.uniprot.org/http://www.uniprot.org/http://www.uniprot.org/uniprot/P011

myosin ii paper

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