Gs cascade regulates canonical transient receptor potential 5 (TRPC5) through cAMP mediated intracellular Ca2+ release and ion channel trafficking

Abstract

Canonical transient receptor potential (TRPC) channels are Ca2+-permeable, non-selective cation channels those are widely expressed in mammalian cells. Various molecules have been found to regulate TRPC both in vivo and in vitro, but it is unclear how heterotrimeric G proteins transmit external stimuli to regulate the activity of TRPC5. Here, we demonstrated that TRPC5 was potentiated by the G alpha(s) regulatory pathway. Whole-cell TRPC5 current was significantly increased by beta-adrenergic receptor agonist, isoproterenol (ISO, 246 +/- 36%, n = 6), an activator of the adenylate cyclase, forskolin (FSK, 273 +/- 6%, n = 5), or a membrane permeable cAMP analogue, 8-Br-cAMP (251 +/- 63%, n = 7). In addition, robust Ca2+ transient induced by isoproterenol was observed utilizing a Ca2+ imaging technique. When intracellular [Ca2+](i) was buffered to 50 nM, cAMP-induced potentiation was attenuated. We also found that the Ca2+ release is mediated by IP3 since intracellular IP3 infusion attenuated the potentiation of TRPC5 by G alpha(s) cascade. Finally, we identified that the membrane localization of TRPC5 was significantly increased by ISO (155 +/- 17%, n = 3), FSK (172 +/- 39%, n = 3) or 8-Br-cAMP (216 +/- 59%, n = 3). In conclusion, these results suggest that the G alpha(s)-cAMP pathway potentiates the activity of TRPC5 via facilitating intracellular Ca2+ dynamics and increasing channel trafficking to the plasma membrane. (C) 2012 Elsevier Inc. All rights reserved.