Involvement of calmodulin and myosin light chain kinase in activation of mTRPC5 expressed in HEK cells.
The classic type of transient receptor potential channel (TRPC) is a molecular candidate for Ca(2+)-permeable cation channels in mammalian cells. Because TRPC channels have calmodulin (CaM) binding sites at their COOH termini, we investigated the effect of CaM on mTRPC5. TRPC5 was initially activated by muscarinic stimulation with 50 microM carbachol and then decayed rapidly even in the presence of carbachol. Intracellular CaM (150 microg/ml) increased the amplitude of mTRPC5 current activated by muscarinic stimulation. CaM antagonists (W-7 and calmidazolium) inhibited mTRPC5 currents when they were applied during the activation of mTRPC5. Pretreatment of W-7 and calmidazolium also inhibited the activation of mTRPC5 current. Inhibitors of myosin light chain kinase (MLCK) inhibited the activation of mTRPC5 currents, whereas inhibitors of CaM-dependent protein kinase II did not. Small interfering RNA against cardiac type MLCK also inhibited the activation of mTRPC5 currents. However, inhibitors of CaM or MLCK did not show any effect on GTPgammaS-induced currents. Application of both Rho kinase inhibitor and MLCK inhibitor inhibited GTPgammaS-induced currents. We conclude that CaM and MLCK modulates the activation process of mTRPC5.
Kim
Min Tae
MT
Department of Physiology and Biophysics, Seoul National Univ. College of Medicine, 28 Yongon-Dong, Chongno-Gu, Seoul 110-799, Korea.
Kim
Byung Joo
BJ
Lee
Jae Hwa
JH
Kwon
Seong Chun
SC
Yeon
Dong Soo
DS
Yang
Dong Ki
DK
So
Insuk
I
Kim
Ki Whan
KW
D000818:Animals; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism*; D002217:Carbachol / Q000378:metabolism; D002460:Cell Line; D018679:Cholinergic Agonists / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000196:embryology; D051379:Mice; D009219:Myosin-Light-Chain Kinase / Q000235:genetics / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D050052:TRPC Cation Channels / Q000235:genetics / Q000378:metabolism*
D002147:Calmodulin; D018679:Cholinergic Agonists; D004791:Enzyme Inhibitors; D034741:RNA, Small Interfering; D050052:TRPC Cation Channels; C112021:Trpc5 protein, mouse; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D002217:Carbachol; D009219:Myosin-Light-Chain Kinase