Cholinesterases and the basal lamina at vertebrate l i ... · matrix (ECM), or basal lamina (BL),...

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C h o lin e s t e r a s e s a n d t h e b a s a l l a m in a a t v e rt e br a t en e uro m u s c u l a r ju n c tio n sJ e an M assouli e1 and C harles B M illard2

M a cromole cules of the cholinergic b asa l la mina are essentia le le m ents of the c om p le x signa ling pro c esses governingd eve lop m ent, function, and re p a ir of the verte brateneuromuscular junction. O ne sp e c ia l form ofa c etylcholinesterase (A C h E) is anchore d w ithin B L through ac olla g en ta il ( C ol Q) that b inds he p aran sulfate prote oglyc ans,such as p erle c an, and the post-syna ptic musc le sp e c ific kinaseMuS K . N e w e x p erim enta l a p pro a ches are prob ing the sp atio-te m pora l dyna mics of C ol Q -A C h E over d ays or w e e ks in vivo,there by unrave ling its intera ctions w ith other B L c om ponents,as w e ll as pre-and post-syna ptic e le m ents. C oncurrenta dvanc es in und erstand ing of the b iologic a l effe cts of sp e c ificC ol Q -A C hE mutations prefigure im prove d d ia gnostics andc linic a l a p pro a ches for som e c ong enita l myasthenicsyndrom es.

A d dr e s s e s1 La boratoire d e N eurob iologie , U M R8544 C N RS , E c o le N orm a leSup erieure , 46 rue d’U lm, 75005 P aris, Franc e2 D ivision of B io che mistry, W a lter R e e d Army Institute of R ese arc h,S ilver S pring, M D 20910, U S A

C orrespon d ing author: M assoulie , J e an (je an.m assoulie@b io logie .ens.fr)

C urr e n t O p in io n in P h a r m a c o lo g y 2009, 9:316–325

This revie w c om e s from a the m e d issue onMusculosk e leta lE d ite d by J O liver D olly

Ava ila b le online 5th M ay 2009

1471-4892/$ – se e front m atter# 2009 E lsevier Ltd . A ll rights reserve d .

D O I 10.1016/j. c o p h .2009.04 .004

In tro d u c tio nThe neuromuscular junction (NMJ), or ‘endplate’, fas-tens the pre-synaptic membrane of the motoneuronterminal to the post-synaptic membrane of the musclefiber, creating a synapse that is remarkably wide (about100 nm) and stable compared with those of the centralnervous system [1 ,2 ,3 ] (Figure 1). Muscle fibers areentirely ensheathed in a specialized zone of extracellularmatrix (ECM), or basal lamina (BL), which occupies thesynapse and follows the post-synaptic folds [1 ,3 ]. TheBL plays an essential and dynamic role in the organiz-ation of the complex morphology of the NMJ, with itspre-synaptic active zones where acetylcholine (ACh) isreleased by calcium-triggered exocytosis of synapticvesicles, its post-synaptic clustering of acetylcholinereceptors (AChRs) and its secondary folds containing

voltage-dependent sodium channels where actionpotentials originate [3 ,4,5 ]. Different macromoleculespresent distinct spatial distributions in the extra-synap-tic zone and in the primary and secondary clefts [3 ,5 ](Figure 2).

The BL is built around a cooperative meshwork ofcollagen type-IV and laminins, stabilized by heparansulfate proteoglycans (HSPs) and linker proteins, whichorganizes and entraps an array of modular ECM glyco-proteins, including peri-synaptic fibronectin and tenas-cin-C, as well as other soluble and insoluble morphogenic,mitogenic, and trophic signals [1 ,2 ,3 ,7 ]. One keypost-synaptic signaling molecule is acetylcholinesterase(AChE,EC 3.1.1.7), a highly efficient enzyme responsiblefor controlling muscle contraction in vertebrates by rapidinactivation of ACh [8 ]. We focus herein on the currentunderstanding of collagen-tailed forms of AChE, as wellas reviewing selected companion molecules within theBL, and their perturbation in neuromuscular diseases.

A n e n s e m b l e o f B L m o l e c u l e s is e s s e n ti a l f o rN M J fu n c tio nCollagen type IV, the most abundantBL protein, containsboth a central triple helical domain and retained non-collagenous domains that permit it to self-assemble intothree-dimensional networks [1 ]. Laminin, the primarynon-collagenous glycoprotein of BL, is a heterotrimer ofone each a-subunit, b-subunit, and g-subunit; there are atleast 12 different subunits that can combine to producemore than 15 different isoforms [1 ,3 ,9]. Lamininassembles into networks partly stabilized by a family ofsulfated linker glycoproteins called nidogens (or entac-tins), some of which are essential for axonal migration andsynaptic transmission [10]; nidogen-2, in particular,becomes concentrated at NMJs and is required for properNMJ formation.

Laminin form 2-1-1 (meaning a trimer of a-2, b-1, and g-1) is the most abundant in muscle, but the synaptic cleft isenriched in laminin forms 2-2-1, 4-2-1 and 5-2-1, eachcontaining the b-2 subunit (originally called S-laminin)[1 ,3 ,9,11]. Muscle fibers produce b-2, a-4 and a-5subunits [9,11]. Laminin a-subunits, as well as agrin,perlecan and other proteins, contain repeats of a globulardomain (LG) that mediates a range of biological functions[9,12,13]. Deletion of the a-2-laminin subunit leads togross histological reduction in the depth and extent of in-folding of the post-synaptic NMJ, demyelination, andsevere congenital muscular dystrophies (CMD; reviewed

C urr e n t O p in io n in P h a r m a c o lo g y 2009, 9:316–325 w w w .sc ienc e d ire ct.c om

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in [3 ]). Laminin a-4 is required for pre-synaptic differ-entiation [12], as well as for the proper apposition of thepre-synaptic active zones and the post-synaptic junctionalfolds [14]. Deletion of laminin a-5 from mouse muscledelays NMJ development, and deletion of a-4 and a-5together arrests maturation completely [9].

HSPs, especially agrin and perlecan, also stabilizelaminin networks [7 ,15 ]. Agrin is a large HSP(>600 kDa) that was identified by its capacity to induceformation of dense clusters of AChRs on myotubes;these clusters also contain AChE. Agrin containsmultiple functional domains, but the AChR aggregatingactivity of the nerve-derived variant largely depends onthe insertion of small exons encoding eight and 11residues, in the C-terminal LG-3 domain [15 ]. Anearly event in the clustering of AChR involves theactivation of a specific receptor tyrosine kinase(muscle-specific kinase, MuSK) by agrin [16], throughits binding with Lrp4, a member of the low densitylipoprotein receptor family [17,18]. The formation ofNMJs is totally suppressed in the absence of agrin orMuSK [19]. Recent data suggest that miniaturizedforms of neural agrin, consisting solely of the lami-nin-binding and the Musk activating domains, sufficeto rescue the perinatal death caused by agrin deficiency[20]. In addition to laminin, agrin binds other HSPssuch as perlecan and a host of post-synaptic com-ponents, including a-dystroglycan (DG), neural-celladhesion molecule (NCAM), and some integrins, aswell as HSP-binding growth factors.

One of the HSP-binding growth factors found in BL is a42 kDa glycoprotein originally named ‘AChR-inducing

activity’ (ARIA), and later found to be identical with aneuregulin-1 gene product [1 ]. NRG-1 activates anerbB receptor kinase and induces selective expressionof adult e-AChR subunits in synaptic nuclei. Miceembryos with suppressed Nrg-1 in motor neurons ormyofibers remain capable of post-synaptic development,synapse-specific gene transcription, and normal AChRclustering with merely a modest reduction in AChRlevels, suggesting that, while agrin and MuSK are indis-pensable for synapse formation,Nrg-1 aids as amodifyingfactor [21 ,22 ].

Perlecan is a multi-domain HSP that participates in awide range of cell signaling events during developmentand morphogenesis [23]; it also is important for localiz-ation of AChE to the NMJ BL [24,25 ].The perlecan coreprotein (470 kDa) carries three N-terminal heparan sul-fate chains of about 380 kDa each (90 nm long), andcontains three C-terminal LG domains interspersed withEGF-like repeats [13,23,26]. Perlecan interacts withECM proteins, including laminin g-1 subunit throughnidogen-1, and also binds the transmembrane complexesof DG and a2/b1-integrin through its LG domains[13,26].

DG may provide a linkage for AChE, via perlecan, tothe post-synaptic cytoskeleton (Figure 3). The DGcomplex of post-synaptic glycoproteins, includingextracellular a-DG and transmembrane b-DG, partici-pates in the organization and stabilization of AChRclusters and links BL components with the muscle cellcytoskeleton [27]. The carbohydrate moieties of a-DGregulate its interactions with laminin, agrin, andperlecan [5 ,28]. For example, a-2 laminin LG-4 and

C h o lin e s t e r a s e s a n d t h e b a s a l l a m in a a t v e rt e br a t e n e ur o m u s c u l a r ju n c tio n s M assoulie and M illard 317

F ig ur e 1

E le ctron microgra phs of neuromuscular junctions. (a) Longitud ina l se ction of a frog N M J. The d ia m eter of the presyna p tic vesic les, c onta ining A C h, isa bout 500 A (M . P e c ot- D e chavassine , unpub lishe d). (b) M ouse N M J, from [4].

w w w .sc ien c e d ire ct.c om C urr e n t O p in io n in P h a r m a c o lo g y 2009, 9:316–325

LG-5 domains bind specifically to O-linked carbo-hydrates of a-DG. Moreover, the absence of DG inculture or in vivo disrupts the normal localization oflaminin, perlecan, and AChE with AChR clusters [27].

C o ll a g e n-t a il e d a c e tyl c h o lin e s t e r a s e ( C o l Q -A C h E)Vertebrate AChE exists as multiple molecular formsthat are generated from a single gene by alternativesplicing, co-translational/post-translational maturation,and oligomerization (reviewed in [8 ,29 ]). The splicevariant expressed in adult muscle and brain, calledAChE-T, contains a C-terminal peptide of 40 AA (T-peptide); likewise, the related butyrylcholinesterase(BChE, EC 3.1.1.8), bears a similar 41 AA T-peptide.The T-peptide exerts a strong influence on the specificprocessing of AChE subunits in the secretory pathway

[29 ] and allows the formation of monomers, dimers,homotetramers, and hetero-oligomers with a transmem-brane protein, the ‘proline-rich membrane anchor’(PRiMA) and with a specific collagen (ColQ)[30,31 ,32]. These anchoring polypeptides containcysteines and a ‘proline-rich attachment domain’ (PRA-D) [33]; their association with cholinesterases is basedon the formation of tight coiled-coil assembly in whichfour alpha helical T-peptides form a cylinder around aPRAD, organized as an elongated polyproline II helix,with three evenly spaced tryptophans from each T-peptide closely apposed to proline rings of the PRAD[34 ]. Interestingly, soluble BChE tetramers, whichrepresent the major species of this enzyme in the humanplasma, were shown recently to associate with a proline-rich peptide derived from the large cytoplasmic proteinlamellipodin [35]. Like the PRADs of ColQ and

318 M u s c u lo s k e l e t a l

F ig ur e 2

Junctiona l and e xtra-junctiona l B L. The ta b le ind ic ates the d istribution of som e B L c om pon ents in d ifferent re gion of the B L surround ing the mousemusc le fib er [3 ,5 ]. N ote that this m ay vary a c c ord ing to the sp e c ies: for e x a m p le , the c olla g en-ta ile d A C h E forms are present in e xtra-junctiona lre gions, in hum an musc le [6].


PRiMA, this polyproline peptide may serve to nucleatetetramer assembly.

The collagen-tailed enzyme (ColQ-AChE) is inserted inthe BL and is of special importance for NMJ function(Figure 4). Biochemical studies of neural and aneuralmuscle segments, as well as genetic inactivation inmouse, strongly suggest that the endplate containsmostlycollagen-tailed AChE [36 ]. In the absence of ColQcollagen, AChE globular forms, in particular thePRiMA-anchored tetramers are still produced andColQ( / ) mice develop functional NMJ, but they showconsiderable muscle weakness and few live to maturity.ColQ( / ) null mice are as severely affected as mice inwhich the AChE gene itself is suppressed [37 ], perhapsowing to a lack of collagen-tailed forms of both AChE andBChE. ColQ( / ) NMJs are fragmented, and show nodetectable accumulation of AChE. Electrophysiologicalrecordings show that muscles from ColQ( / ) mice are

insensitive to AChE inhibition [36 ,38 ]. These resultsdemonstrate that ColQ-AChE in the junctional BL isresponsible for limiting the activation of post-synapticAChRs by ACh.

Although the insertion of AChE in the synaptic BLdepends essentially on its association with ColQ, thecatalytic domain of AChE may also participate in specificinteractions, in agreement with its homology withadhesion molecules such as neuroligin; indeed, two-hybrid studies suggest that it may bind laminin [39].

C o l Q s y n t h e s is a n d r e g u l a tio nThe ColQ collagen precursor is composed of a secretorysignal peptide, an N-terminal region that contains thePRAD, a collagenous region of about 180 residuesbracketed by two pairs of cysteines, a trimerizationdomain of about 80 residues, and a downstream regionof about 60 residues containing 10 cysteines, homologous


F ig ur e 3

S e le cte d intera ctions a mong B L, presyna ptic and post-syna ptic mole cules. La minin b2 b inds the presyna ptic volta g e g ate d c a lc ium channe ls througha C -termina l Leu-Arg- G lu motif, induc ing the ir c lustering and the org aniz ation of the a ctive zone where syna ptic vesic les m ay b e re le a se d . Agrininduc es post-syna ptic d ifferentiation by a ctivating MuS K through an intera ction of its C -termina l L G 3 dom a in w ith Lrp4 but a lso b inds a-D G . Thec arbohydrat e moieties of a-D G re gulate its intera c tions w ith la minin, a grin, and p erle c an; la minin a-2 L G -4/5 dom a ins b ind sp e c ific a lly to O -link e dc arbohydrat es of a-D G . P erle c an, which intera cts w ith c olla g en, C ol Q , through its he p aran sulfate cha ins, a lso b inds a-D G , which thus esta b lishes alink b etw e en the B L and the post-syna ptic cytosk e leton through the dystrop hin–utrophin c om p le x. C ol Q a lso intera cts w ith MuS K , prob a b ly though itsC -termina l dom a in. The A C h E subunits m ay intera c t d ire ctly w ith la minins. A lthough this sche m e is not dra wn to sc a le , note that the d im ensions ofmole cules in the B L are c om p ara b le to the w idth of the syna ptic c left, sugg esting that the intera c tions of larg e mole cules in such a restricte d sp a c e areprob a b ly highly org aniz e d .



F ig ur e 5

C olla g en C ol Q . (a) E xistenc e of two promoters in the hum an C ol Q g ene , produc ing variants that d iffer in the ir se cre tory signa l p e ptid e and in the firstresidues of the m ature prote ins. The e xons are shown as box es and the c o d ing re gions are hatche d . The C ol Q 1 variant is enc od e d by e xons 1 and 2and the C ol Q 1a variant by e xons 1a and 2. The se quenc es of the signa l p e ptid es are in low er c ase letters, and the N-termina l re gions of the m a tureprote ins in c a p ita l letters; the residues c onserve d in hum an, rat, and mouse C ol Q are in bold typ e . (b) The dom a ins of C ol Q . (c) E ffe cts of hum anmutations im p lic ate d in C M S [41,42 ,43 ].

F ig ur e 4

C olla g en-t a ile d A C h E mole cule s. (a) E le ctron microgra phs of A12 A C h E from Torp e do e le ctric org an, from [30]. The arrow s point to theC -termina l globular dom a in of C ol Q . (b) S che m e of an A12 A C hE mole cule: the c ata lytic dom a ins of A C h E subunits are in d ifferent sha d es ofb lue; the c olla g en C ol Q subunits are in re d , and in e a ch A C h E tetra m er the asse m b ly of the PRA D w ith four C -termina l T-p e ptid e s is showna c c ord ing to [34 ].


to a motif from the human pregnancy associated plasmaprotein-A (PAPP-A) [31 ,40] (Figure 5). ColQ forms ahomotrimer with a collagen triple helix about 50 nm long.

The PRAD of each strand may or may not be associatedwith a tetramer of AChE subunits: collagen-tailed mol-ecules containing one, two, or three AChE tetramers aredesignated A4, A8, or A12, according to the number ofAChE subunits.The overall length of theA12molecule iscomparable to the width of the primary cleft in NMJs(Figure 4). These complex hetero-oligomers are stabil-ized by disulfide bonds between two cysteines upstreamof the PRAD and C-terminal cysteines from two AChEsubunits, while the other two AChE subunits are disul-fide-linked to each other.However, the complexes can beformed even in the absence of cysteines, either fromColQ collagen or from the T-peptides of AChE subunits[33,44]. Both AChE and ColQ polypeptides are trans-ferred into the lumen of the rough endoplasmic reticulum(ER).

The assembly of collagen helices occurs in the ER by azipper-like mechanism after trimerization of the C-term-inal non-collagenous domain. Several lines of evidenceshow that the association of the N-terminal PRAD withfour AChE subunits also occurs in the ER [44,45], afterwhich the complexes are transported into the Golgicompartment, where the carbohydrate chains are modi-fied.

The mammalian ColQ gene possesses two distinct pro-moters, generating transcripts ColQ1 and ColQ1a[31 ,46 ]. In the rat, ColQ1 and ColQ1a transcripts aremostly expressed in slow and fast muscles, respectively,and are driven by upstream elements called SURE andFIRE, similar to those that control the expression of fiber-specific contractile proteins. The ColQ1 and ColQ1atranscripts encode proteins that differ in their secretorysignal peptides and only a few AA of the mature ColQsubunits. However, they may differ in the efficiency ofpost-translational processing, or targeting toward differ-ent ER subcompartments, as suggested by differences inthe formation of collagen-tailed AChE, when co-expressed in Xenopus oocytes [47 ]. It would be inter-esting to explore the possible functional difference be-tween ColQ1 and ColQ1a, as it may be significant in slowand fast muscles.

Although ColQ is not known to associate with otherligands through its PRAD, it may exert other functionsthan anchoring cholinesterases, for example in the lungwhere it is highly expressed and may participate inorganization of pulmonary alveolar ECM.

C o l Q - A C h E lo c a li z a tio n a n d m o b ility in t h e B LSynaptic receptor sites for ColQ-AChE were demon-strated by testing the ability of purified quail muscle

AChE, with and without the collagen tail, to be ‘trans-planted’ to frog NMJs [48 ]. The collagen-tailed forms,but not globular AChE lacking ColQ, bound target NMJsand co-localized with AChR. HSPs are among the likelyECM acceptor sites for ColQ-AChE, because ColQ inter-acts with anionic, sulfated glycosaminoglycans [49,50 ].ColQ contains two clusters of basic AA capable of bindingheparin or heparin sulfate [51 ]. Additionally, a fraction ofColQ-AChE is bound to muscle tissue through inter-actions that depend upon divalent cations, possiblycalcium [52]. Once localized by reversible ionic inter-actions, a fraction of ColQ-AChE becomes progressivelyresistant to solubilization from the BL by heparin, but canbe released by collagenase [50 ]. This immobilizationmay result from cross-linking of ColQ lysines with othercomponents of the ECM, e.g. fibronectin, catalyzed bytransglutaminase [53].

Perlecan is one principal HSP acceptor site for ColQ-AChE [24,25 ]. Mice lacking perlecan die at birthbecause of respiratory failure, but their muscles becomeinnervated. Although they express normal levels of col-lagen-tailed forms, as well as synaptic agrin and AChRs,AChE fails to localize and accumulate at NMJs. Theglycosaminoglycans of perlecan are therefore thought toplay a major role in the localization of ColQ within theBL, but it remains unclear whether this is related to theirabundance or to specific interactions and whether ColQmight also interact with the core protein of perlecan. Inthis respect, it will be interesting to analyze AChE at theNMJs of mice expressing a perlecan mutant lacking theheparan sulfate chains.

Co-immunoprecipitation studies showed that ColQassociates with MuSK and this association is suppressedby a point mutation in the C-terminal PAPP-A motif[54 ].This interaction may participate in the localizationof collagen-tailed AChE. However, while MuSK islocated in the AChR-rich post-synaptic membrane thatfaces the presynaptic terminal across the primary cleft,ColQ-AChE molecules are distributed in the BL of theprimary cleft and also in the secondary folds [55], wherethey cannot interact with MuSK.

Innervation of Xenopus muscle fibers was found to inducethe clustering, at nerve-muscle contacts, of pre-existingendogenous AChE molecules, or of quail collagen-tailedmolecules that had been previously transplanted andwere scattered over the surface of the fiber [50 ]. Thisshows that the collagen-tailed molecules can migrate inthe plane of the BL, perhaps as a complex with HSPs. Bystudying mouse NMJ in vivo with time-lapse imaging,fluorescent labeling and photo-bleaching methods, it wasshown that mobile pools of AChE can be recruited fromnon-synaptic sites by lateral diffusion into the synapse;once localized within the synapse, the AChE becomes‘trapped’ and is relatively stable [56 ,57 ]. However, the



stability of synaptic AChE was reduced in mutant micelacking a-dystrobrevin, a post-synaptic protein that inter-acts with dystrophin and thus indirectly with the a-DGcomplex. This complex therefore participates in thestable junctional accumulation of AChE, as well as ofAChRs.

C o l Q - A C h E a n d N M J f or m a tio nDuring early muscle development, AChR gene expres-sion and clustering occur in a restricted region of themuscle fibers, forming a ‘pre-pattern’ that precedes inner-vation [58].This involves a nerve-independent activationof MuSK. Since ColQ interacts with MuSK, it may play arole at this stage. Suppression of the AChR gamma-subunit gene in mice prevents pre-patterned AChR clus-ters and induces an abnormal distribution of AChE andexcessive nerve branching [59].

However, in rat muscles, ColQ-AChE appearancecoincides with the establishment of nerve-muscle con-tacts, and is probably induced by nerve-derived agrin,which triggers the development of the NMJ [22 ]. ColQ-AChE is initially distributed over the entire fiber but laterbecomes concentrated at the sites of nerve-muscle con-tacts [47 ]. The overall shape and size of the NMJchanges throughout development and is further con-ditioned by physical activity and by the fiber-type distri-bution [60,61].

Denervation induces the disappearance ofColQ-AChE; itre-appears after re-innervation at original or ectopic sites,or after direct electrical stimulation, indicating that it isproduced and deposited by the muscle in the BL underthe influence of activity and of permanent signals left bythe original nerve terminals, possibly agrin, even atoriginal endplates that are no longer occupied by nerveterminals [62 ,63].

The distribution of collagen-tailed AChE forms and theeffect of denervation vary widely with species and muscletype. In the rat, fast muscles contain solely the A12 form,restricted to the NMJs, whereas the soleus contains A8and A4 forms even in aneural regions. This can beexplained by the different expressions ofColQ andAChEtranscripts in the two types of muscles [47 ]. In adulthuman muscles, ColQ-AChE forms are abundant allalong the muscle fibers [6]. After denervation of rabbitleg muscles, these forms disappear from the fast-twitchregion, but actually increase several-fold in the slow-twitch region [64].

AChE and ColQ subunits are expressed both by moto-neurons and by muscle fibers, and ColQ-AChE is trans-ported by the fast axonal flow in the chicken and rat sciaticnerves [65]. Although the normal deposition of ColQ-AChE in the BL depends on nerve-derived components,as well as muscle activity, the tissue-specific genetic

suppression of AChE expression in mouse muscles, butnot in motoneurons, showed that, in vivo, synaptic AChEis produced almost exclusively by the muscle [66 ].

G e n e ti c d e f e c t s in t h e ju n c tio n a l a c c u m u l a tio n o fC o l Q - A C h EThe Schwarz-Jampel syndrome is a recessive disorderproducing failure of muscle relaxation and skeletal dys-plasia that results from reduced expression of perlecan[67,68]. The neuromuscular defect may be caused partlyby a low content of AChE, due to a lack of acceptor sites inthe BL. When human perlecan mutations were intro-duced in mice, they reproduced the Schwarz-Jampelneuromyotonia, with spontaneous activity and fatigabilityat low stimulation frequencies, and the severity of theeffect was correlated with the decrease in perlecan level[69]. The muscle fibers were not damaged and the NMJswere not disorganized, but junctional AChE was reducedand there was a specific decrease of the A12 collagen-tailed form.

Congenital myasthenic syndromes (CMS) are a hetero-geneous group of human genetic disorders concerning atleast 10 different NMJ genes. In particular, more than 20mutations have been found in the ColQ gene and causeCMS with AChE deficiency [41,42 ,43 ]. Thesemutations generally present clinically asmyasthenic symp-toms but differ from myasthenia gravis by the absence ofAChR antibodies, a negative edrophonium test, and a lackof response to long-lasting AChE inhibitors. It is note-worthy that a point mutation within the PRAD of ColQ(replacement of a proline by a glutamine) is sufficient toprevent the junctional accumulationofAChE,demonstrat-ing that this depends on the formation of the collagen-tailed molecules (Figure 5). Mutations in the collagenousor in the trimerization domains prevent the formation ofthe triple helical tail and result in the formation of AChEtetramers that are linked to a fragment of ColQ and fail toassociate correctly with theBL. Interestingly,mutations inthe C-terminal PAPP-A motif of ColQ produce collagen-tailed molecules that do not bind MuSK and do notaccumulate normally in the junctional BL [41,54 ].Thus,theheparin-binding sites in the collagenous region ofColQand its C-terminal domain are both required for anchoringAChE [70 ].

Quite surprisingly, different patients carrying the samemutation inColQ may be very severely affected, as early asthe infant stage, orpresent only verymild symptoms [43 ].In addition, a few patients presented a short-term benefitfrom AChE inhibitors.This suggests that the effect of theColQ mutations may not depend solely on the lack ofsynaptic AChE, but also on complex interactions withMuSK and with the organization of the synaptic BL.

Recent experiments offer the hope of efficiently repla-cing the missing AChE at NMJs. The ColQ gene was



inserted in a viral vector and expressed in hindlegmusclesof ColQ( / ) mice [71 ]. This allowed a recovery ofAChE at NMJs, not only those of the injected fibers butalso those of foreleg muscles. This demonstrates an invivo transplantation, and a remarkable mobility of col-lagen-tailed molecules between muscle fibers and evenamong distant muscles.

C o n c lu s io n sThe vertebrate NMJ BL is a complex array of multi-domain glycoproteins, HSPs and non-fibrillar collagensforming a persistent structural bridge across the synapse,and expressing dynamic molecular signals such as func-tional carbohydrate moieties, EGF-like repeats, LG andMuSK domains, and in particular the ACh-hydrolyzingactivity of AChE. BL largely determines and coordinatesthe pre-synaptic differentiation of the active zones and thepost-synaptic accumulation of AChRs, as well as secondaryfolds facing the active zones. The precise expression ofprotein families within the BL, as well as co-translational/post-translational modifications and numerous heterophi-lic interactions, provide well-ordered molecular cues fornerve-muscle cell communication during normal develop-ment, function, and repair.Theperi-synapticglial cells andfibroblasts also may rely on such signals forNMJ mainten-ance and repair [72]. New experimental approaches, suchas FRET-based microscopy with live cells, are beginningto delineate the combinations of individual motifs respon-sible for NMJ function and to analyze their interactionsduring assembly of the BL. Moreover, the relatively largesize and familiarity of the vertebrate NMJ, combinedwithapplication of covalent or high-affinity fluorescent probesin multi-laser confocal microscopy, cryo-electron micro-scopy, or tomography, makes it possible to track move-ments of selected BL elements in living systems [57 ].Finally, an emerging understanding of how inheritedmutations can disrupt these molecular communicationnetworks at specific nodes sheds light upon the cause ofdevastating neuromuscular diseases (CMDs and CMS)[42 ,43 ] and, thereby, offers promise for target-basedNMJ therapies that may include gene replacement orsupplementation [71 ].

A c k n o w l e d g e m e n t sThis work was supported by grants from CNRS, ENS, AFM, DGA, andDTRA (USA). We thank Drs Jeanine Koenig, Claire Legay, and Eric Krejcifor helpful discussions.

R e f e r e n c e s a n d r e c o m m e n d e d r e a d in gP a p ers of p artic ular interest, pub lishe d w ithin the p eriod of revie w ,have b e en highlighte d as:

of sp e c ia l interest of outstand ing interest

1.

S anes JR, Lichtm an J W: D e v e lo p m e n t o f t h e v e rt e b r a t en e uro m u s c u l a r ju n c tio n . Annu R ev N eurosc i 1999, 22:389-442.

O ld er but c om preh ensive revie w that, in c om b ination w ith referenc es[3 ,9], w ill provid e re a d er w ith strong b a c kground in the b asic structurefunction of the B L.

2.

Lichtm an J W , S anes JR: W a t c h in g t h e n e uro m u s c u l a r ju n c tio n .J N euro cytol 2003, 32:767-775.

K ey referenc e for e m erging m ethods to study N M J asse m b ly and c om-ponent intera ctions. Transg enic mic e in which motor a xons are fluores-c ently la b e le d , c oup le d w ith se le ctive post-syna ptic sta ins, provid e a ne ww ay to im a g e N M Js in vivo over severa l w e e ks.

3.

S anes JR: T h e b a s e m e n t m e m b r a n e / b a s a l l a m in a o f s k e l e t a lm u s c l e . J B iol C he m 2003, 278:12601-12604.

The sp e c ific ity of syna ptic vs. e xtrasyna ptic B L in m a mm a lian musc le .

4. B urd en SJ, S arg ent P B , M c M ahan U J: A c e tyl c h o li n e r e c e p t orsin r e g e n e r a tin g m u s c l e a c c u m u l a t e a t o rig in a l s y n a p ti c s it e s int h e a b s e n c e o f t h e n e rv e . J C e ll B io l 1979, 82:412-425.

5.

P atton B L: B a s a l l a m in a a n d t h e o rg a n i z a tio n o fn e ur o m u s c u l a r s y n a p s e s . J. N euro cytol. 2003, 32:883-903.

The d istribution of B L c om pon ents in e xtrasyna ptic re gions, prim ary c leftand se c ond ary folds at the N M J.

6. Sk ete lj J, Brz in M: A s y m m e tri c m o l e c u l a r f o r m s o fa c e tyl c h o lin e s t e r a s e in m a m m a li a n s k e l e t a l m u s c l e s .J N eurosc i R es 1985, 14:95-103.

7.

Ioz zo RV: B a s e m e n t m e m br a n e pr o t e o g ly c a n s: fr o m c e ll a r t oc e ilin g . N at R ev M ol C e ll B iol 2005, 6:646-656.

An authorita tive revie w on the mole cular structure of p erle c an.

8.

M assoulie J: T h e orig in o f t h e m o l e c u l a r d iv e rs ity a n dfu n c tio n a l a n c h o rin g o f c h o lin e s t e r a s e s . N euroS ignals 2002,11:130-143.

K ey referenc e for und erstand ing C ol Q and the multip le mole cular forms ofA C h E a c c ounting for the b iolo gic a l d istribution and function of theenzym e .

9. N ishimune H , Va ld e z G , J ara d G , M oulson C L, Muller U , M iner J H ,S anes JR: L a m in in s pr o m o t e p o s t s y n a p ti c m a t ur a tio n b y a na u t o c rin e m e c h a n is m a t t h e n e uro m u s c u l a r ju n c tio n . J C e llB iol 2008, 182:1201-1215.

10. F ox M A , H o M S , Smyth N , S anes JR: A s y n a p ti c n id o g e n:d e v e lo p m e n t a l r e g u l a tio n a n d r o l e o f n id o g e n -2 a t t h en e ur o m u s c u l a r ju n c tio n . N eural D ev 2008, 3:24.

11. N ishimune H , S anes JR, C arlson S S: A s y n a p ti c l a m in in–c a l c iu mc h a n n e l in t e r a c tio n or g a n i z e s a c tiv e z o n e s in m o t or n e rv et e r m in a ls . N ature 2004, 432:580-587.

12. Ichik a w a N , K asa i S , Suzuki N , N ishi N , O ishi S , F ujii N , K a doya Y ,H atori K , M izuno Y , N omizu M et al.: Id e n tifi c a tio n o f n e urit eo u t g r o w t h a c tiv e s it e s o n t h e l a m in in a lp h a 4 c h a in G d o m a in .B io che mistry 2005, 44:5755-5762.

13. T a lts J F , And a c Z , G ohring W , Branc a c c io A , Tim p l R: B in d in g o ft h e G d o m a in s o f l a m in in a lp h a 1 a n d a lp h a 2 c h a in s a n dp e rl e c a n t o h e p a rin , s u lf a tid e s , a lp h a - d y s tr o g ly c a n a n ds e v e r a l e x tr a c e llu l a r m a trix p ro t e in s . E M B O J 1999,18:863-870.

14. P atton B L, C unningha m J M , Thybo ll J, K ortesm a a J,W esterb la d H , E dstrom L, Tryggvason K , S anes JR: Pro p e rlyf o r m e d b u t i m pr o p e rly lo c a li z e d s y n a p ti c s p e c i a li z a tio n s int h e a b s e n c e o f l a m in in 4. N at N eurosc i 2001, 4:597-604.

15.

B e z a kova G , Rue gg M A: N e w in s ig h t s in t o t h e r o l e s o f a grin . N atR ev M ol C e ll B iol 2003, 4:295-308.

Structura l, functiona l intera ctions of a grin sp lic e variants.

16. Z hou H , G lass D J, Y anc opoulos G D , S anes JR: D is tin c t d o m a in so f M u S K m e d i a t e it s a b iliti e s t o in d u c e a n d t o a s s o c i a t e w it hp o s t s y n a p ti c s p e c i a li z a tio n s . J C e ll B iol 1999, 146:1133-1146.

17. K im N , Stie gler AL, C a m eron T O , H a llc k PT, G om e z A M , Huang J H ,Hub b ard SR, Dustin ML, B urd e n SJ: Lr p 4 is a r e c e p t or f or a grina n d f o r m s a c o m p l e x w it h M u S K . C e ll 2008, 135:334-342.

18. Z hang B , Luo S , W ang Q , Suzuki T, Xiong W C , M e i L: L R P4 s e rv e sa s a c or e c e p t o r o f a grin . N euron 2008, 60:285-297.

19. G auta m M , D e C hiara T M , G lass D J, Y anc opoulos G D , S anes JR:D is tin c t p h e n o ty p e s o f m u t a n t m i c e l a c k in g a g rin , M u S K , orr a p s y n . D ev Brain R es 1999, 114:171-178.

20. Lin S , M a j M , B e z a kova G , M a gyar JP , Brenner H R, Rue gg M A:M u s c l e - w id e s e c r e tio n o f a m in i a t uri z e d f o r m o f n e ur a l a grinr e s c u e s f o c a l n e ur o m u s c u l a r in n e rv a tio n in a grin m u t a n tm i c e . Pro c N atl A c a d S c i U S A 2008, 105:11406-11411.



21.

J a worski A , B urd en SJ: N e uro m u s c u l a r s y n a p s e f o r m a tio n inm i c e l a c k in g m o t o r n e uro n- a n d s k e l e t a l m u s c l e - d e riv e dn e ur e g u lin -1 . J N eurosc i 2006, 26:655-661.

E vid enc e that neure gulin-1 is not re quire d for the syna ptic e x pression ofA C hRs at N M Js.

22.

Kumm er TT, M isg e ld T, S anes JR: A s s e m b ly o f t h e p o s t s y n a p ti cm e m br a n e a t t h e n e ur o m u s c u l a r ju n c tio n: p a r a d ig m lo s t . C urrO p in N eurob io l 2006, 16:74-82.

The current vie w on the essentia l role of a grin in the induc tion of N M Js.

23. White lo c k J M , M e lrose J, Ioz zo RV: D iv e rs e c e ll s ig n a lin g e v e n t sm o d u l a t e d b y p e rl e c a n . B io che mistry 2008, 47:11174-11183.

24. P eng H B , Xie H , Rossi S G , Rotundo RL: A c e tyl c h o lin e s t e r a s ec lu s t e rin g a t t h e n e ur o m u s c u l a r ju n c tio n in v o lv e s p e rl e c a na n d d y s tr o g ly c a n . J C e ll B iol 1999, 145:911-921.

25.

Arik a w a-H irasa w a E , Rossi S G , Rotundo RL, Y a m a d a Y: A b s e n c eo f a c e tyl c h o lin e s t e r a s e a t t h e n e uro m u s c u l a r ju n c tio n s o fp e rl e c a n- n u ll m i c e . N at N eurosc i 2002, 5:119-123.

The a c cumulation of C ol Q -A C h E at N M Js is a bolishe d in the a bsenc e ofp erle c an.

26. B ix G , F u J, G onz a le z E M , M a cro L, B ark er A , C a m p b e ll S ,Zutter M M , S antoro S A , K im J K , H ook M et al.: E n d o r e p e llinc a u s e s e n d o t h e li a l c e ll d is a s s e m b ly o f a c tin c yt o s k e l e t o n a n df o c a l a d h e s io n s t hr o u g h a lp h a 2b e t a 1 in t e g rin . J C e ll B io l 2004,166:97-109.

27. J a c obson C , C ot e P D , Rossi S G , Rotun do RL, C arbone tto S: T h ed y s tro g ly c a n c o m p l e x is n e c e s s a ry f or s t a b ili z a tio n o fa c e tyl c h o lin e r e c e p t o r c lu s t e rs a t n e uro m u s c u l a r ju n c tio n sa n d f or m a tio n o f t h e s y n a p ti c b a s e m e n t m e m b r a n e . J C e ll B iol2001, 152:435-450.

28. M c D e armon EL, C om bs A C , Ervasti J M: C or e 1 g ly c a n s o na lp h a - d y s tro g ly c a n m e d i a t e l a m in in -in d u c e d a c e tyl c h o lin er e c e p t or c lu s t e ri n g b u t n o t l a m in in b in d in g . J B iol C he m 2003,278:44868-44873.

29.

M assoulie J, P errier N , N oure d d ine H , Liang D , B on S: O ld a n dn e w q u e s tio n s a b o u t c h o lin e s t e r a s e s . C he m B iol Int 2008,175:30-44.

C urrent questions re g ard ing cholinesterase structure , intera ctions, andfunctions.

30. Kre jc i E , C oussen F , Duva l N , C hate l J M , Le g ay C , Puyp e M ,Vand e k erc khov e J, C artaud J, B on S , M assoulie J: Pri m a rys tru c t ur e o f a c o ll a g e n i c t a il p e p tid e o f T or p e d oa c e tyl c h o lin e s t e r a s e: c o - e x p r e s s io n w it h c a t a lyt i c s u b u n itin d u c e s t h e pr o d u c tio n o f c o ll a g e n - t a il e d f o r m s in tr a n sf e c t e dc e lls . E M B O J 1991, 10:1285-1293.

31.

Kre jc i E , Thomine S , B oschetti N , Le g ay C , Sk ete lj J, M assoulie J:T h e m a m m a li a n g e n e o f a c e tyl c h o lin e s t e r a s e - a s s o c i a t e dc o ll a g e n . J B iol C he m 1997, 272:22840-22847.

D escription of the m a mm a lian C ol Q g ene .

32. P errier AL, M assoulie J, Kre jc i E: P R i M A , t h e m e m b r a n e a n c h o ro f a c e tyl c h o lin e s t e r a s e in br a in . N euron 2002, 33:275-285.

33. B on S , C oussen F , M assoulie J: Q u a t e rn a ry a s s o c i a tio n s o fa c e tyl c h o lin e s t e r a s e . II. T h e p o ly p ro lin e a tt a c h m e n t d o m a ino f t h e c o ll a g e n t a il. J B iol C he m 1997, 272:3016-3021.

34.

Dvir H , H are l M , B on S , Liu W Q , Vid a l M , G arb ay C , Sussm an JL,M assoulie J, S ilm an I: T h e s y n a p ti c a c e tyl c h o lin e s t e r a s et e tr a m e r a s s e m b l e s a r o u n d a p o ly p r o lin e II h e lix . E M B O J2004, 23:4394-4405.

Crysta llogra phic ana lysis of the intera ction a mong four C -termina l T-p e ptid es of A C hE and a PRA D p e ptid e from C ol Q ; d e duc e d org aniz ationof an A C hE tetra m er asso c iate d w ith one strand of the C ol Q c olla g en.

35. Li H , S chopfer LM , M asson P , Lo c kridg e O : L a m e llip o d in p r o lin eri c h p e p tid e s a s s o c i a t e d w it h n a tiv e p l a s m ab u tyryl c h o lin e s t e r a s e t e tr a m e r s . B io che m J 2008, 411:425-432.

36.

F eng G , Kre jc i E , M olgo J, C unningh a m J M , M assoulie J,S anes JR: G e n e ti c a n a ly s is o f c o ll a g e n Q : r o l e s ina c e tyl c h o lin e s t e r a s e a n d b u tyryl c h o li n e s t e r a s e a s s e m b ly a n din s y n a p ti c s tru c t ur e a n d fu n c tio n . J C e ll B iol 1999,144:1349-1360.

A C hE is sup presse d from the N M Js of mic e in which the C ol Q g ene isina ctivate d and miniature end p late pot entia ls are not prolong e d by A C hEinhib ition.

37.

Li B , Strib ley JA , Ticu A , Xie W , S chopfer LM , H a mmond P ,Brimijoin S , H inrichs S H , Lo c kridg e O : A b u n d a n t tis s u eb u tyryl c h o lin e s t e r a s e a n d it s p o s s ib l e fu n c tio n in t h ea c e tyl c h o lin e s t e r a s e k n o c k o u t m o u s e . J N euro che m 2000,75:1320-1331.

M ic e are severe ly hand ic a p p e d but c an live after c om p lete sup pression ofA C h E; there is no c om p ensatory overe x pression of B C h E , but the pre-senc e of this enzym e b e c om es vita l.

38.

N guyen-Huu T, D ob b ertin A , B arb ier J, M inic J, Duva ld estin P ,M olgo J: C h o lin e s t e r a s e s a n d t h e r e s is t a n c e o f t h e m o u s ed i a p hr a g m t o t h e e ff e c t o f t u b o c ur a rin e . Anesthesiol 2005,103:788-795.

A physiolog ic a l study of musc le e x c itation in w ild-typ e and C ol Q -d efic ientmic e; d ifferent effe cts of A C h E inhib ition. The nerve-evok e d response ofthe rat d ia phra gm is less sensitive to d-tubo curarine than that of th eextensor d igitorum longus.

39. P ara o anu LE , Layer P G : M o u s e A C h E b in d s in viv o t o d o m a in IVo f l a m in in -1 b e t a . C he m B iol Intera ct 2005, 157-158:411-413.

40. B on S , Ayon A , Leroy J, M assoulie J: Tri m e ri z a tio n d o m a in o f t h ec o ll a g e n t a il o f a c e ty l c h o lin e s t e r a s e . N euro che m R es 2003,28:523-535.

41. D ong er C , Kre jc i E , Pou S erra d e ll A P , E ym ard B , B on S , N ic ole S ,C hate au D , G ary F , F ard e au M , M assoulie J et al.: M u t a tio n in t h eh u m a n a c e tyl c h o lin e s t e r a s e - a s s o c i a t e d c o ll a g e n g e n e , C o l Q ,is r e s p o n s ib l e f o r c o n g e n it a l m y a s t h e n i c s y n dr o m e w it h e n d -p l a t e a c e tyl c h o lin e s t e r a s e d e fi c i e n c y (ty p e Ic). A m J HumanG enet 1998, 63:967-975.

42.

O hno K , Eng e l A G , Brengm an J M , Shen XM , H e id enre ich F ,Vinc ent A , M ilone M , T an E , D e mirc i M , W a lsh P et al.: T h es p e c tru m o f m u t a tio n s c a u s in g e n d - p l a t ea c e tyl c h o lin e s t e r a s e d e fi c i e n c y . Ann N eurol 2000, 47:162-170.

D escription of num erous hum an mutations in the C ol Q g ene and the ireffe cts.

43.

M ihaylova V, Muller JS , Vilche z JJ, S a lih M A , K a b ira j M M ,D’Amic o A , B ertini E , W olfle J, S chre iner F , Kurle m ann G et al.:C lin i c a l a n d m o l e c u l a r g e n e ti c fi n d in g s in C O L Q - m u t a n tc o n g e n it a l m y a s t h e n i c s y n d r o m e s . Brain 2008,131:747-759.

C linic a l stud ies show ing a w id e varia b ility in the severity of sym ptomsc ause d by C ol Q mutations.

44. B e lb e o c’h S , F a lasc a C , Leroy J, Ayon A , M assoulie J, B on S:E l e m e n t s o f t h e C -t e r m in a l T p e p tid e o f a c e tyl c h o lin e s t e r a s et h a t d e t e r m in e a m p h ip h ili c ity, h o m o m e ri c a n d h e t e ro m e ri ca s s o c i a tio n s , s e c r e tio n a n d d e g r a d a tio n . Eur J B io che m 2004,271:1476-1487.

45. M assoulie J, Anse lm et A , B on S , Kre jc i E , Le g ay C , M aya t E ,M ore l N , S imon S: D iv e rs ity a n d p r o c e s s i n g o fa c e tyl c h o lin e s t e r a s e . In Structure and F unction ofC holinesterases and R e late d Prote ins. E d ite d by D o ctor B P , Q uinnD M , Rotundo RL, T aylor P . N e w York: P lenum Press; 1998:3-24.

46.

Le e H H , C hoi R C , Ting A K , S iow NL, Jiang JX, M assoulie J,Tsim K W: Tr a n s c rip tio n a l r e g u l a tio n o f a c e tyl c h o lin e s t e r a s e -a s s o c i a t e d c o ll a g e n C o l Q : d iff e r e n ti a l e x pr e s s io n in f a s t a n ds lo w t w it c h m u s c l e fi b e rs is driv e n b y d is tin c t p r o m o t e rs . J B iolC he m 2004, 279:27098-27107.

D ifferent transcriptiona l re gulation of the C ol Q 1 and C ol Q 1a transcripts,which are prefere ntia lly e x presse d in slow and fast musc les, resp e ctive ly.

47.

Kre jc i E , Le g ay C , Thomine S , Sk ete lj J, M assoulie J: D iff e r e n c e sin e x p r e s s io n o f a c e tyl c h o lin e s t e r a s e a n d c o ll a g e n Q c o n tro lt h e d is trib u tio n a n d o lig o m e ri z a tio n o f t h e c o ll a g e n - t a il e df o r m s in f a s t a n d s lo w m u s c l e s . J N eurosc i 1999,19:10672-10679.

E xistenc e and d istribution of C ol Q 1 and C ol Q 1a variants in slow and fastmusc les; d e monstration that the d ifferent proportions of A12, A8 and A4forms observe d in these musc le s c an b e re produc e d by e x pressingd ifferent ratios of C ol Q and A C h E transcrip ts in Xenop us oo cytes.

48.

Rotundo RL, Rossi S G , Anglister L: T r a n s p l a n t a tio n o f q u a ilc o ll a g e n-t a il e d a c e tyl c h o lin e s t e r a s e m o l e c u l e s o n t o t h e fr o gn e ur o m u s c u l a r s y n a p s e . J C e ll B io l 1997, 136:367-374.

C ol Q -A C h E forms of e xterna l origin c an b e sp e c ific a lly atta che d to frogN M Js.

49. Brand an E , M a ldona do M , G arrido J, Inestrosa N C : A n c h o r a g e o fc o ll a g e n-t a il e d a c e tyl c h o lin e s t e r a s e t o t h e e x tr a c e llu l a r



m a trix is m e d i a t e d b y h e p a r a n s u lf a t e pr o t e o g ly c a n s . J C e llB iol 1985, 101:985-992.

50.

Rossi S G , Rotundo RL: Tr a n s i e n t in t e r a c tio n s b e t w e e nc o ll a g e n - t a il e d a c e tyl c h o lin e s t e r a s e a n d s u lf a t e dpro t e o g ly c a n s p rio r t o i m m o b ili z a tio n in t h e e x tr a c e llu l a rm a trix . J B iol C he m 1996, 271:1979-1987.

After the ir e xterna liz ation at N M Js, C ol Q -A C hE forms are first reversib lyimmob iliz e d , most prob a b ly through ionic intera ctions w ith H S Ps, andlater b e c om e c ova lently atta che d to the B L.

51.

D e pre z P , Inestrosa N C , Kre jc i E: T w o d iff e r e n t h e p a rin - b in d in gd o m a in s in t h e trip l e - h e li c a l d o m a in o f C o l Q , t h e c o ll a g e n t a ils u b u n it o f s y n a p ti c a c e tyl c h o lin e s t e r a s e . J B io l C he m 2003,278:23233-23242.

Id entific ation and prop erties of two d istinct he p aran-b ind ing sites in thec olla g enous trip le he lic a l re gion of C ol Q .

52. B arat A , E scud ero E , R a m ıre z G : H e p a rin a n d t h e s o lu b ili z a tio no f a s y m m e tri c a c e tyl c h o lin e s t e r a s e . F E B S Lett 1986,195:209-214.

53. H and D , D ias D , H aynes LW: St a b ili z a tio n o f c o ll a g e n - t a il e da c e tyl c h o lin e s t e r a s e in m u s c l e c e lls t hr o u g h e x tr a c e llu l a ra n c h or a g e b y tr a n s g lu t a m in a s e - c a t a ly z e d c ro s s -lin k in g . M o lC e ll B io che m 2000, 204:65-76.

54.

C artaud A , Stro chlic L, G uerra M , B lanchard B , La m b erg e on M ,Kre jc i E , C artaud J, Le g ay C : M u S K is r e q u ir e d f or a n c h o rin ga c e tyl c h o lin e s t e r a s e a t t h e n e uro m u s c u l a r ju n c tio n . J C e ll B iol2004, 165:505-515.

C ol Q intera cts w ith MuS K through its C -termina l dom a in.

55. Anglister L, E ichler J, S z a bo M , H a esa ert B , S a lp eter M M: 125I-l a b e l e d f a s c i c u lin 2: a n e w t o o l f or q u a n tit a tio n o fa c e tyl c h o lin e s t e r a s e d e n s iti e s a t s y n a p ti c s it e s b y E M -a u t or a d io gr a p h y. J N eurosc i M ethods 1998, 81:63-71.

56.

Kre jc i E , M artine z-P ena y Va lenzue la I, Am e z iane R, Ak a a boune M:A c e tyl c h o lin e s t e r a s e d y n a m i c s a t t h e n e ur o m u s c u l a r ju n c tio no f liv e a n i m a ls . J B iol C he m 2006, 281:10347-10354.

A C hE w as la b e le d by fluoresc ent fasc iculin in living mouse N M Js andfluoresc enc e w as monitore d over a w e e k. A bout ha lf of the la b e le d A C hEw as rene w e d w ithin thre e d ays. C ol Q -A C h E a p p e are d to b e interna liz e dw ith A C hRs, in the sa m e vesic les.

57.

M artine z-P ena y Va lenzue la I, Ak a a boune M:A c e tyl c h o lin e s t e r a s e m o b ility a n d s t a b ility a t t h en e uro m u s c u l a r ju n c tio n o f livin g m i c e . M ol B iol C e ll 2007,18:2904-2911.

The latera l d iffusion of A C h E w as stud ie d in mic e N M Js in vivo , by la b e lingw ith fasc iculin c onjug ate d w ith stre pt avid ins of d ifferent c olors andphoto-unb ind ing . P erijunctiona l A C hE is mob ile and c an b e re cruite dto the N M J, where it b e c om es tra p p e d and immob ile . This sta b ility w asre duc e d in the a bsenc e of the post-syna p tic prote in dystrobrevin.

58. Arb er S , B urd en SJ, H arris AJ: P a tt e rn in g o f s k e l e t a l m u s c l e .C urr O p in N eurob iol 2002, 12:100-103.

59. Liu Y , P a dg ett D , T a k ahashi M , Li H , S aye e d A , T e ichert R W ,O livera B M , M c Ard le JJ, Gre en W N , Lin W: E s s e n ti a l r o l e s o f t h ea c e tyl c h o lin e r e c e p t o r g a m m a - s u b u n it in n e uro m u s c u l a rs y n a p ti c p a tt e rn in g . D eve lop m ent 2008, 135:1957-1967.

60. W ilson M H , D eschenes M R: T h e n e ur o m u s c u l a r ju n c tio n:a n a t o m i c a l f e a t ur e s a n d a d a p t a tio n s t o v a rio u s f o r m s o fin c r e a s e d , o r d e c r e a s e d n e ur o m u s c u l a r a c tivity . Int J N eurosc i2005, 115:803-828.

61. Hughes B W , Kusner LL, K a minski H J: M o l e c u l a r a r c h it e c t ur e o ft h e n e ur o m u s c u l a r ju n c tio n . Musc le N erve 2006, 33:445-461.

62.

W e inb erg C B , H a ll Z W: J u n c tio n a l f or m o f a c e tyl c h o lin e s t e r a s er e s t or e d a t n e rv e -fr e e e n d p l a t e s . D ev B iol 1979, 68:631-635.

An old observation that d eserves to b e re-visite d and e x p la ine d inmole cular terms: C ol Q -A C h E d isa p p e ars from rat N M Js after d enervationbut re-a p p e ar at origina l end p lates, as w e ll as at ne w end p lates, aftere ctop ic re-innervation, d e monstrating that the syna ptic B L w as a b le toinduc e the ir synthe sis and a c cumulation when the musc le w as a ctive .

63. Lømo T, M assoulie J, Vigny M: Sti m u l a tio n o f d e n e rv a t e d r a ts o l e u s m u s c l e w it h f a s t a n d s lo w a c tivity p a tt e rn s in d u c e sd iff e r e n t e x p r e s s io n o f a c e tyl c h o lin e s t e r a s e m o l e c u l a r f o r m s .J N eurosc i 1985, 5:1180-1187.

64. B a c ou F , Vigneron P , M assoulie J: A c e ty l c h o lin e s t e r a s e f o r m s inf a s t a n d s lo w r a b b it m u s c l e . N ature 1982, 296:661-664.

65. C ouraud JY , D i G ia m b erard ino L, H assig R, M ira J C : A x o n a ltr a n s p ort o f t h e m o l e c u l a r f or m s o f a c e tyl c h o lin e s t e r a s e ind e v e lo p in g a n d r e g e n e r a tin g p e rip h e r a l n e rv e . Exp N eurol1983, 80:94-110.

66.

C a m p S , D e J a c o A , Z hang L, M arque z M , D e la Torre B , T aylor P:A c e tyl c h o lin e s t e r a s e e x p r e s s io n in m u s c l e is s p e c ifi c a llyc o n tr o ll e d b y a p ro m o t e r- s e l e c tiv e e n h a n c e s o m e in t h e fi rs tin tr o n . J N eurosc i 2008, 28:2459-2470.

D e letion of an intronic re gion in the A C h E g ene sup presses its e x pressionin musc le and a bolishes the a c cumulation of C ol Q -A C h E at N M Js.

67. N ic ole S , D avoine C S , Top a lo glu H , C attolic o L, B arra l D ,B e ighton P , H a mid a C B , H a mmoud a H , Crua ud C , White P S et al.:P e rl e c a n , t h e m a j or pr o t e o g ly c a n o f b a s e m e n t m e m br a n e s , isa lt e r e d in p a ti e n t s w it h S c h w a rt z - J a m p e l s y n dr o m e(c h o n dr o d y s tr o p h i c m y o t o n i a). N at G enet 2000, 26:480-483.

68. Arik a w a-H irasa w a E , Le A H , N ishino I, N ona k a I, H o N C ,Franc om ano C A , G ovindra j P , H asse ll JR, D evaney J M , S prang er Jet al.: Stru c t ur a l a n d fu n c tio n a l m u t a tio n s o f t h e p e rl e c a n g e n ec a u s e S c h w a rt z - J a m p e l s y n d ro m e , w it h m y o t o n i c m y o p a t h ya n d c h o n d r o d y s p l a s i a . A m J Hum G enet 2002, 70:1368-1375.

69. Stum M , G irard E , B angratz M , B ernard V, H erb in M , Vignaud A ,F erry A , D avoine C S , E chaniz-La guna A , R e ne F et al.: E vid e n c e o fa d o s a g e e ff e c t a n d a p h y s io lo g i c a l e n d p l a t ea c e tyl c h o lin e s t e r a s e d e fi c i e n c y in t h e fi rs t m o u s e m o d e lsm i m i c k in g S c h w a rt z - J a m p e l s y n dr o m e n e ur o m y o t o n i a . HumM ol G enet 2008, 17:3166-3179.

70.

K im b e ll LM , O hno K , Eng e l A G , Rotundo RL: C -t e r m in a l a n dh e p a rin- b in d in g d o m a in s o f c o ll a g e n i c t a il s u b u n it a r e b o t he s s e n ti a l f or a n c h o rin g a c e tyl c h o lin e s t e r a s e a t t h e s y n a p s e .J B iol C he m 2004, 279:10997-11005.

C ol Q -A C h E A12 forms c onta ining severa l mutations of th e C -termina ldom a in of C ol Q , id entifie d in hum an p atients, which w ere produc e d invitro, fa ile d to atta ch to frog N M Js. This dom a in is therefore re quire d forthe atta chm ent of C ol Q -A C h E in the B L at N M Js, in a d d ition to ionicintera ctions of C ol Q w ith H S Ps.

71.

Ito M , Suzuki Y , O k a d a T, F ukudom e T, Yoshimura T, M asud a A ,Kre jc i E , O hno K: r A A V8- m e d i a t e d pr o t e in a n c h o rin g o fa s y m m e tri c a c e tyl c h o lin e s t e r a s e (A C h E) t o t h e s y n a p ti c b a s a ll a m in a a t t h e n e ur o m u c u l a r ju n c tio n (N M J). A S C B , 48th AnnualM e eting; San Franc isc o (D e c e m b er 13–17, 2008): 2008. A bstra ct2138.

In C ol Q d efic ient mic e , a vira l ve ctor a llow e d the e x pression of C ol Q in le gmusc le fib ers, and the resulting C ol Q -A C h E forms w ere found to migrateand atta ch at N M Js in front le g musc les.

72. F eng Z , K o C P: N e uro n a l g li a in t e r a c ti o n s a t t h e v e rt e br a t en e uro m u s c u l a r ju n c tio n . C urr O p in Pharma c ol 2007, 7:316-324.



Cholinesterases and the basal lamina at vertebrate l i ... · matrix (ECM), or basal lamina (BL),...

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Transcript of Cholinesterases and the basal lamina at vertebrate l i ... · matrix (ECM), or basal lamina (BL),...