Agrin-induced acetylcholine receptor clustering in mammalian muscle requires tyrosine phosphorylation.

Ferns, Michael J.; Deiner, Michael; Hall, Zach W.

doi:10.1083/jcb.132.5.937

Cited by 141 publications

(170 citation statements)

References 36 publications

Supporting

Mentioning

160

Contrasting

Order By: Relevance

“…Phosphorylation correlates closely with reduced mobility and detergent extractability of the AChR (Meier et al., 1995, Borges andFerns, 2001), suggesting that it regulates linkage to the cytoskeleton. In addition, it precedes AChR clustering (Ferns et al, 1996) and tyrosine kinase inhibitors that block phosphorylation also block clustering (Wallace et al, 1991, Ferns et al, 1996. Consistent with these findings, mutation of the tyrosine phosphorylation site in the β subunit abolishes agrin-induced cytoskeletal anchoring of mutant AChR and impairs its aggregation in muscle cells (Borges and Ferns, 2001).…”

Section: Nih Public Accessmentioning

confidence: 53%

“…In muscle cells, agrin-or nerve-induced clustering of the receptor involves tyrosine phosphorylation of both the AChR β and δ subunits (Wallace et al, 1991, Meier et al, 1995, Ferns et al, 1996. Following MuSK activation, phosphorylation of each subunit occurs with a similar time-course and is inhibited by the same pharmacological agents , Mohamed et al, 2001.…”

Section: Phosphorylation Of Achr β and δ Subunitsmentioning

confidence: 99%

See 1 more Smart Citation

Rapsyn carboxyl terminal domains mediate muscle specific kinase–induced phosphorylation of the muscle acetylcholine receptor

et al. 2008

View full text Add to dashboard Cite

At the developing vertebrate neuromuscular junction, postsynaptic localization of the acetylcholine receptor (AChR) is regulated by agrin signaling via the muscle specific kinase (MuSK) and requires an intracellular scaffolding protein called rapsyn. In addition to its structural role, rapsyn is also necessary for agrin-induced tyrosine phosphorylation of the AChR, which regulates some aspects of receptor localization. Here, we have investigated the molecular mechanism by which rapsyn mediates AChR phosphorylation. In a heterologous COS cell system, we show that MuSK and rapsyn induced phosphorylation of β subunit tyrosine 390 (Y390) and δ subunit Y393, as in muscle cells. Mutation of β Y390 or δ Y393 did not inhibit MuSK/rapsyn-induced phosphorylation of the other subunit in COS cells, and mutation of β Y390 did not inhibit agrin-induced phosphorylation of the δ subunit in Sol8 muscle cells; thus, their phosphorylation occurs independently, downstream of MuSK activation. In COS cells, we further show that MuSK-induced phosphorylation of the β subunit was mediated by rapsyn, as MuSK plus rapsyn increased β Y390 phosphorylation more than rapsyn alone and MuSK alone had no effect. Intriguingly, MuSK also induced tyrosine phosphorylation of rapsyn itself. We then used deletion mutants to map the rapsyn domains responsible for activation of cytoplasmic tyrosine kinases that phosphorylate the AChR subunits. We found that rapsyn C-terminal domains (amino acids 212-412) are both necessary and sufficient for activation of tyrosine kinases and induction of cellular tyrosine phosphorylation. Moreover, deletion of the rapsyn RING domain (365-412) abolished MuSK-induced tyrosine phosphorylation of the AChR β subunit. Together, these findings suggest that rapsyn facilitates AChR phosphorylation by activating or localizing tyrosine kinases via its C-terminal domains. Keywords neuromuscular junction; synaptogenesis; agrin; postsynaptic membraneAt the developing neuromuscular junction in vertebrates, several nerve-derived signals combine to localize the acetylcholine receptor at postsynaptic sites (Sanes and Lichtman, 2001, Burden, 2002, Kummer et al., 2006. One essential factor is agrin, which signals via the MuSK receptor tyrosine kinase and induces and/or stabilizes clustering of the AChR in the postsynaptic membrane (reviewed in (Kummer et al., 2006 Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. is prepatterned and AChR clusters occur in the central region of the muscle prior to and even in the absence of neural innervation (Lin et al., 2001, Yang et al., 2001). However, upo...

show abstract

Section: Nih Public Accessmentioning

confidence: 53%

Section: Phosphorylation Of Achr β and δ Subunitsmentioning

confidence: 99%

Rapsyn carboxyl terminal domains mediate muscle specific kinase–induced phosphorylation of the muscle acetylcholine receptor

et al. 2008

View full text Add to dashboard Cite

show abstract

“…7). Tyrosine phosphorylated AChR is less detergent extractable than nonphosphorylated AChR, indicating that it is preferentially linked to the cytoskeleton (Ferns et al, 1996;Borges and Ferns, 2001). Phosphorylation could regulate anchoring of the AChR through a direct interaction with a cytoskeletal protein or indirectly via a linker protein.…”

Section: Discussionmentioning

confidence: 99%

Lipid Rafts Serve as a Signaling Platform for Nicotinic Acetylcholine Receptor Clustering

Zhu¹,

Xiong²,

Mei³

2006

J. Neurosci.

130

View full text Add to dashboard Cite

Agrin, a motoneuron-derived factor, and the muscle-specific receptor tyrosine kinase (MuSK) are essential for the acetylcholine receptor (AChR) clustering at the postjunctional membrane. However, the underlying signaling mechanisms remain poorly defined. We show that agrin stimulates a dynamic translocation of the AChR into lipid rafts-cholesterol and sphingolipid-rich microdomains in the plasma membrane. This follows MuSK partition into lipid rafts and requires its activation. Disruption of lipid rafts inhibits MuSK activation and downstream signaling and AChR clustering in response to agrin. Rapsyn, an intracellular protein necessary for AChR clustering, is located constitutively in lipid rafts, but its interaction with the AChR is inhibited when lipid rafts are perturbed. These results reveal that lipid rafts may regulate AChR clustering by facilitating the agrin/MuSK signaling and the interaction between the receptor and rapsyn, both necessary for AChR clustering and maintenance. These results provide insight into mechanisms of AChR cluster formation.

show abstract

“…This nerve-derived protein originally was isolated for its striking ability to cause AChR aggregation in chick myotubes (Godfrey et al, 1984). The observation that agrin induces tyrosine phosphorylation of the ␤ (Wallace et al, 1991;Qu and Huganir, 1994;Wallace, 1994;Ferns et al, 1996), and perhaps the ␦ (Qu and Huganir, 1994), subunit of the AChR has led to the hypothesis that this is a critical, and perhaps a prerequisite, step in the AChR clustering pathway. A recently identified musclespecific receptor tyrosine kinase, MuSK, has been shown to be essential for NMJ formation (Valenzuela et al, 1995;.…”

Section: Discussionmentioning

confidence: 99%

“…Phosphorylation of the AChR by both serine and tyrosine kinases is associated with an increased rate of receptor desensitization (Huganir et al, 1986;Hopfield et al, 1988). In addition, agrin-induced tyrosine phosphorylation of the AChR may play a role in its clustering to high densities in the postsynaptic membrane of the neuromuscular junction (Qu et al, 1990;Wallace et al, 1991;Qu and Huganir, 1994;Wallace, 1994;Ferns et al, 1996).…”

mentioning

confidence: 99%

Tyrosine Phosphorylation of Nicotinic Acetylcholine Receptor Mediates Grb2 Binding

Colledge

Froehner

1997

J. Neurosci.

View full text Add to dashboard Cite

Tyrosine phosphorylation of the nicotinic acetylcholine receptor (AChR) is associated with an altered rate of receptor desensitization and also may play a role in agrin-induced receptor clustering. We have demonstrated a previously unsuspected interaction between Torpedo AChR and the adaptor protein Grb2. The binding is mediated by the Src homology 2 (SH2) domain of Grb2 and the tyrosine-phosphorylated ␦ subunit of the AChR. Dephosphorylation of the ␦ subunit abolishes Grb2 binding. A cytoplasmic domain of the ␦ subunit contains a binding motif (pYXNX) for the SH2 domain of Grb2. Indeed, a phosphopeptide corresponding to this region of the ␦ subunit binds to Grb2 SH2 fusion proteins with relatively high affinity, whereas a peptide lacking phosphorylation on tyrosine exhibits no binding. Grb2 is colocalized with the AChR on the innervated face of Torpedo electrocytes. Furthermore, Grb2 specifically copurifies with AChR solubilized from postsynaptic membranes. These data suggest a novel role for tyrosine phosphorylation of the AChR in the initiation of a Grb2-mediated signaling cascade at the postsynaptic membrane.

show abstract

Agrin-induced acetylcholine receptor clustering in mammalian muscle requires tyrosine phosphorylation.

Cited by 141 publications

References 36 publications

Rapsyn carboxyl terminal domains mediate muscle specific kinase–induced phosphorylation of the muscle acetylcholine receptor

Rapsyn carboxyl terminal domains mediate muscle specific kinase–induced phosphorylation of the muscle acetylcholine receptor

Lipid Rafts Serve as a Signaling Platform for Nicotinic Acetylcholine Receptor Clustering

Tyrosine Phosphorylation of Nicotinic Acetylcholine Receptor Mediates Grb2 Binding

Contact Info

Product

Resources

About