TRPC3-interacting triadic proteins in skeletal muscle.
The expression of TRPC3 (canonical-type transient receptor potential cation channel type 3) is tightly regulated during skeletal muscle cell differentiation, and a functional interaction between TRPC3 and RyR1 [(ryanodine receptor type 1), an SR (sarcoplasmic reticulum) Ca2+-release channel] regulates the gain of SR Ca2+ release during EC (excitation-contraction) coupling. However, it has not been possible to demonstrate direct protein-protein interactions between TRPC3 and RyR1. To identify possible candidate(s) for a linker protein(s) between TRPC3 and RyR1 in skeletal muscle, in the present study we performed MALDI-TOF (matrix-assisted laser-desorption ionization-time-of-flight) MS analysis of a cross-linked triadic protein complex from rabbit skeletal triad vesicles and co-immunoprecipitation assays using primary mouse skeletal myotubes. From these studies, we found that six triadic proteins, that are known to regulate RyR1 function and/or EC coupling [TRPC1, JP2 (junctophilin 2), homer, mitsugumin 29, calreticulin and calmodulin], interacted directly with TRPC3 in a Ca2+-independent manner. However we again found no direct interaction between TRPC3 and RyR1. TRPC1 was identified as a potential physical link between TRPC3 and RyR1, as it interacted with both TRPC3 and RyR1, and JPs showed subtype-specific interactions with both RyR1 and TRPC3 (JP1-RyR1 and JP2-TRPC3). These results support the hypothesis that TRPC3 and RyR1 are functionally engaged via linker proteins in skeletal muscle.
Woo
Jin Seok
JS
Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea.
Kim
Do Han
DH
Allen
Paul D
PD
Lee
Eun Hui
EH
D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D003432:Cross-Linking Reagents / Q000737:chemistry; D051379:Mice; D018345:Mice, Knockout; D015394:Molecular Structure; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism; D011485:Protein Binding; D019837:Ryanodine Receptor Calcium Release Channel / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D050052:TRPC Cation Channels / Q000235:genetics / Q000378:metabolism*
D003432:Cross-Linking Reagents; D019837:Ryanodine Receptor Calcium Release Channel; D050052:TRPC Cation Channels; C104603:TRPC3 cation channel; C096351:transient receptor potential cation channel, subfamily C, member 1