A self-limiting regulation of vasoconstrictor-activated TRPC3/C6/C7 channels coupled to PI(4,5)P 2-diacylglycerol signalling

Yuko Imai, Kyohei Itsuki, Yasushi Okamura, Ryuji Inoue, Masayuki X. Mori

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32 Citations (Scopus)

Abstract

Activation of transient receptor potential (TRP) canonical TRPC3/C6/C7 channels by diacylglycerol (DAG) upon stimulation of phospholipase C (PLC)-coupled receptors results in the breakdown of phosphoinositides (PIPs). The critical importance of PIPs to various ion-transporting molecules is well documented, but their function in relation to TRPC3/C6/C7 channels remains controversial. By using an ectopic voltage-sensing PIP phosphatase (DrVSP), we found that dephosphorylation of PIPs robustly inhibits currents induced by carbachol (CCh), 1-oleolyl-2-acetyl-sn-glycerol (OAG) or RHC80267 in TRPC3, TRPC6 and TRPC7 channels, though the strength of the DrVSP-mediated inhibition (VMI) varied among the channels with a rank order of C7 > C6 > C3. Pharmacological and molecular interventions suggest that depletion of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P 2) is most likely the critical event for VMI in all three channels. When the PLC catalytic signal was vigorously activated through overexpression of the muscarinic type-I receptor (M1R), the inactivation of macroscopic TRPC currents was greatly accelerated in the same rank order as the VMI, and VMI of these currents was attenuated or lost. VMI was also rarely detected in vasopressin-induced TRPC6-like currents in A7r5 vascular smooth muscle cells, indicating that the inactivation by PI(4,5)P 2 depletion underlies the physiological condition. Simultaneous fluorescence resonance energy transfer (FRET)-based measurement of PI(4,5)P 2 levels and TRPC6 currents confirmed that VMI magnitude reflects the degree of PI(4,5)P 2 depletion. These results demonstrate that TRPC3/C6/C7 channels are differentially regulated by depletion of PI(4,5)P 2, and that the bimodal signal produced by PLC activation controls these channels in a self-limiting manner.

Original languageEnglish
Pages (from-to)1101-1119
Number of pages19
JournalJournal of Physiology
Volume590
Issue number5
DOIs
Publication statusPublished - Feb 1 2012

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All Science Journal Classification (ASJC) codes

  • Physiology

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