Localization and Regulation of MuSK at the Neuromuscular Junction

Bowen, David C.; Park, John S.; Bodine, Sue C.; Stark, Jennifer; Valenzuela, David M.; Stitt, Trevor N.; Yancopouloš, George D.; Lindsay, Ronald M.; Glass, David J.; DiStefano, Peter S.

doi:10.1006/dbio.1998.8936

Cited by 86 publications

(68 citation statements)

References 31 publications

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“…The localization of MuSK clusters in the γ -/-muscle was similar to that observed in the wildtype muscle (arrowheads in Fig. 8B,F), and consistent with the previously reported pattern of MuSK antibody staining in wild-type embryonic muscles (Bowen et al, 1998). Therefore, the phenotype developed in the γ -/-muscles is unlikely to be due to alternation of MuSK expression; instead, it probably resulted from the lack of the γ-subunit and consequently the absence of prepatterned AChRs (Fig.…”

Section: Clustering Of Musk In the Absence Of The γ-Subunitsupporting

confidence: 91%

“…The samples were blocked in dilution buffer (500 mM NaCl, 0.01 M phosphate buffer, 3% BSA and 0.01% thimerosal), and then incubated with primary antibody-neurofilament 150 (Chemicon, Temecula, CA), rapsyn (Affinity Bioreagents, Golden, CO), synaptophysin (Dako, Carpinteria, CA), synaptic vesicle protein 2 (SV2) (Developmental Studies Hybridoma Bank, University of Iowa, Iowa City, IA), MuSK (41101K) (Bowen et al, 1998), synaptotagmin 2 or syntaxin (gifts from Dr Thomas Sudhof, UT Southwestern Medical Center, Dallas, TX). Muscles were then incubated with fluorescein isothiocyanateconjugated secondary antibodies and Texas Red-conjugated α-bungarotoxin (α-bgt) (10 -8 M, Molecular Probes).…”

Section: Immunocytochemistrymentioning

confidence: 99%

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Essential roles of the acetylcholine receptor γ-subunit in neuromuscular synaptic patterning

et al. 2008

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Formation of the vertebrate neuromuscular junction (NMJ) takes place in a stereotypic pattern in which nerves terminate at select sarcolemmal sites often localized to the central region of the muscle fibers. Several lines of evidence indicate that the muscle fibers may initiate postsynaptic differentiation independent of the ingrowing nerves. For example, nascent acetylcholine receptors (AChRs) are pre-patterned at select regions of the muscle during the initial stage of neuromuscular synaptogenesis. It is not clear how these pre-patterned AChR clusters are assembled, and to what extent they contribute to pre-and post-synaptic differentiation during development. Here, we show that genetic deletion of the AChR γ-subunit gene in mice leads to an absence of pre-patterned AChR clusters during initial stages of neuromuscular synaptogenesis. The absence of pre-patterned AChR clusters was associated with excessive nerve branching, increased motoneuron survival, as well as aberrant distribution of acetylcholinesterase (AChE) and rapsyn. However, clustering of muscle specific kinase (MuSK) proceeded normally in the γ-null muscles. AChR clusters emerged at later stages owing to the expression of the AChR epsilon-subunit, but these delayed AChR clusters were broadly distributed and appeared at lower level compared with the wild-type muscles. Interestingly, despite the abnormal pattern, synaptic vesicle proteins were progressively accumulated at individual nerve terminals, and neuromuscular synapses were ultimately established in γ-null muscles. These results demonstrate that the γ-subunit is required for the formation of pre-patterned AChR clusters, which in turn play an essential role in determining the subsequent pattern of neuromuscular synaptogenesis.

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Section: Clustering Of Musk In the Absence Of The γ-Subunitsupporting

confidence: 91%

Section: Immunocytochemistrymentioning

confidence: 99%

Essential roles of the acetylcholine receptor γ-subunit in neuromuscular synaptic patterning

et al. 2008

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“…MuSK signaling depends on an autophosphorylated tyrosine residue in its juxtamembrane region (Y553) contained within an NPXY motif for which Dok7 is the only known binding partner and target (Fig. 5B) (8,30,59,71). This motif was recognized, to various affinities, by the Appl, Dok2, and ShcD PTB domains in the array-based screen (Fig.…”

Section: Resultsmentioning

confidence: 99%

Screening for PTB Domain Binding Partners and Ligand Specificity Using Proteome-Derived NPXY Peptide Arrays

Smith

Hardy

Murphy

et al. 2006

Molecular and Cellular Biology

100

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Modular interaction domains that recognize peptide motifs in target proteins can impart selectivity in signaling pathways. Phosphotyrosine binding (PTB) domains are components of cytoplasmic docking proteins that bind cell surface receptors through NPXY motifs. We have employed a library of human proteome-derived NXXY sequences to explore PTB domain specificity and function. SPOTS peptide arrays were used to create a comprehensive matrix of receptor motifs that were probed with a set of 10 diverse PTB domains. This approach confirmed that individual PTB domains have selective and distinct recognition properties and provided a means to explore over 2,500 potential PTB domain-NXXY interactions. The results correlated well with previously known associations between full-length proteins and predicted novel interactions, as well as consensus binding data for specific PTB domains. Using the Ret, MuSK, and ErbB2 receptor tyrosine kinases, we show that interactions of these receptors with PTB domains predicted to bind by the NXXY arrays do occur in cells. Proteome-based peptide arrays can therefore identify networks of receptor interactions with scaffold proteins that may be physiologically relevant.External signaling molecules typically bind receptors that span the plasma membrane and thereby activate intracellular targets. This is often achieved through the selective recognition of short peptide motifs in receptors by proteins containing modular interaction domains. These binding events form the backbone of cellular signaling, and their regulation is a fundamental process by which cells organize their growth and survival (60, 62).Posttranslational modifications represent an important mechanism by which cell surface receptors recruit cytoplasmic targets (61, 67). Tyrosine phosphorylation of receptor tyrosine kinases (RTKs), cytokine receptors and adhesion proteins, for example, creates recognition motifs for the Src homology 2 (SH2) or PTB (phosphotyrosine binding) domains of cytoplasmic proteins that control responses such as cytoskeletal organization, metabolism, survival, differentiation, and division.PTB domains are found in scaffold proteins that often contain additional modular domains and motifs and thereby nucleate the formation of multiprotein complexes (24,37,50,79). They have been grouped into three broad families (insulin receptor substrate 1 [IRS-1]/Dok-like, Shc-like, and Dab-like) based on structural comparisons (75). The minimal PTB domain fold consists of a central ␤-sandwich comprised of seven antiparallel ␤-strands that is capped on one end by the Cterminal ␣-helix and on the other by a variable length ␣-helix found between strands ␤1 and ␤2 (or ␤2 and ␤3). Additional helices can be present in members of the Shc and Dab families. The canonical peptide-binding groove is located between the fifth ␤-strand and the conserved C-terminal ␣-helix. Peptide ligands typically adopt a ␤-turn that provides an anchor point for binding and is often initiated by Ϫ3 asparagine and Ϫ2 proline residues (relative to ty...

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“…AChRs aggregate and co-localize with a large number of other molecules [reviewed by Willmann and Fuhrer, 2002] in response to motor-neuron-derived agrin [reviewed by McMahan, 1990] through signaling events that require a muscle-specific kinase (MuSK) Sugiyama et al, 1997;Bowen et al, 1998;Gautam et al, 1999]. MuSK aggregates and co-localizes with AChRs [Fuhrer et al, 1997], is required for neuromuscular synapse formation and in the adult is found only at neuromuscular synapses [Valenzuela et al, 1995].…”

Section: Introductionmentioning

confidence: 99%

Reduced Glycosaminoglycan Sulfation Diminishes the Agrin Signal Transduction Pathway

McDonnell

Grow²

2004

Dev Neurosci

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Proteoglycans consist of a protein core complexed to glycosaminoglycan (GAG) side chains, are abundant in skeletal muscle cell membranes and basal lamina, and have important functions in neuromuscular synapse development. Treatment with chlorate results in the undersulfation of heparan sulfate and chondroitin sulfate GAGs in cell culture. In addition, chlorate treatment decreases the frequency of spontaneous acetylcholine receptor (AChR) clustering in skeletal muscle cell culture. AChRs and other molecules cluster to form the postsynaptic component of neuromuscular synapses. Chlorate treatment is shown here to decrease the frequency of agrin-induced AChR clustering and agrin-induced tyrosine phosphorylation of the AChR β-subunit. These data suggest that reduced GAG chain sulfation decreases the frequency of AChR clustering by diminishing the agrin signal transduction pathway.

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Localization and Regulation of MuSK at the Neuromuscular Junction

Cited by 86 publications

References 31 publications

Essential roles of the acetylcholine receptor γ-subunit in neuromuscular synaptic patterning

Essential roles of the acetylcholine receptor γ-subunit in neuromuscular synaptic patterning

Screening for PTB Domain Binding Partners and Ligand Specificity Using Proteome-Derived NPXY Peptide Arrays

Reduced Glycosaminoglycan Sulfation Diminishes the Agrin Signal Transduction Pathway

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