PMID- 18436384
OWN - NLM
STAT- MEDLINE
DCOM- 20081008
LR  - 20211020
IS  - 0306-4522 (Print)
IS  - 0306-4522 (Linking)
VI  - 153
IP  - 4
DP  - 2008 Jun 2
TI  - Rapsyn carboxyl terminal domains mediate muscle specific kinase-induced 
      phosphorylation of the muscle acetylcholine receptor.
PG  - 997-1007
LID - 10.1016/j.neuroscience.2008.03.009 [doi]
AB  - 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 at the rodent neuromuscular junction. 
      In a heterologous COS cell system, we show that MuSK and rapsyn induced 
      phosphorylation of beta subunit tyrosine 390 (Y390) and delta subunit Y393, as in 
      muscle cells. Mutation of beta Y390 or delta Y393 did not inhibit 
      MuSK/rapsyn-induced phosphorylation of the other subunit in COS cells, and 
      mutation of beta Y390 did not inhibit agrin-induced phosphorylation of the delta 
      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 beta subunit was mediated by rapsyn, as MuSK plus rapsyn 
      increased beta 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 beta subunit. 
      Together, these findings suggest that rapsyn facilitates AChR phosphorylation by 
      activating or localizing tyrosine kinases via its C-terminal domains.
FAU - Lee, Y
AU  - Lee Y
AD  - Departments of Anesthesiology and Physiology and Membrane Biology, One Shields 
      Avenue, University of California-Davis, Davis, CA 95616, USA.
FAU - Rudell, J
AU  - Rudell J
FAU - Yechikhov, S
AU  - Yechikhov S
FAU - Taylor, R
AU  - Taylor R
FAU - Swope, S
AU  - Swope S
FAU - Ferns, M
AU  - Ferns M
LA  - eng
GR  - CO6 RR 17348-01/CO/NCI NIH HHS/United States
GR  - R01 NS049354-04/NS/NINDS NIH HHS/United States
GR  - R01 NS049354/NS/NINDS NIH HHS/United States
GR  - C06 RR017348/RR/NCRR NIH HHS/United States
GR  - NS 049354/NS/NINDS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
DEP - 20080318
PL  - United States
TA  - Neuroscience
JT  - Neuroscience
JID - 7605074
RN  - 0 (Antibodies)
RN  - 0 (Bungarotoxins)
RN  - 0 (Muscle Proteins)
RN  - 0 (Protein Subunits)
RN  - 0 (Receptors, Cholinergic)
RN  - 0 (Receptors, Nicotinic)
RN  - 0 (peripheral membrane protein 43K)
RN  - EC 2.7.10.1 (MuSK protein, rat)
RN  - EC 2.7.10.1 (Protein-Tyrosine Kinases)
RN  - EC 2.7.10.1 (Receptor Protein-Tyrosine Kinases)
SB  - IM
MH  - Animals
MH  - Antibodies/pharmacology
MH  - Bungarotoxins/pharmacology
MH  - Cell Line, Transformed
MH  - Chlorocebus aethiops
MH  - Cricetinae
MH  - Enzyme Activation/drug effects/physiology
MH  - Gene Expression Regulation, Enzymologic/drug effects/physiology
MH  - Mice
MH  - Muscle Proteins/genetics/*metabolism/pharmacology
MH  - Muscles/*metabolism
MH  - Mutation
MH  - Neuromuscular Junction/drug effects/metabolism
MH  - Phosphorylation/drug effects
MH  - Protein Structure, Tertiary/physiology
MH  - Protein Subunits/metabolism
MH  - Protein-Tyrosine Kinases/metabolism
MH  - Rats
MH  - Receptor Protein-Tyrosine Kinases/*metabolism
MH  - Receptors, Cholinergic/*metabolism
MH  - Receptors, Nicotinic/classification/genetics/immunology/*physiology
MH  - Transfection/methods
PMC - PMC2587422
MID - NIHMS55194
EDAT- 2008/04/26 09:00
MHDA- 2008/10/09 09:00
PMCR- 2008/11/25
CRDT- 2008/04/26 09:00
PHST- 2007/07/26 00:00 [received]
PHST- 2008/03/03 00:00 [revised]
PHST- 2008/03/06 00:00 [accepted]
PHST- 2008/04/26 09:00 [pubmed]
PHST- 2008/10/09 09:00 [medline]
PHST- 2008/04/26 09:00 [entrez]
PHST- 2008/11/25 00:00 [pmc-release]
AID - S0306-4522(08)00373-4 [pii]
AID - 10.1016/j.neuroscience.2008.03.009 [doi]
PST - ppublish
SO  - Neuroscience. 2008 Jun 2;153(4):997-1007. doi: 
      10.1016/j.neuroscience.2008.03.009. Epub 2008 Mar 18.