Negative regulation of Ca2+ influx during P2Y(2) purinergic receptor activation is mediated by G beta gamma-subunits

作者：Hu Haibi; O'Mullane Lauren M; Cummins Michelle M; Campbell Craig R; Hosoda Yutaka; Poronnik Philip; Dinudom Anuwat; Cook David I^*

来源：Cell Calcium, 2010, 47(1): 55-64.

DOI：10.1016/j.ceca.2009.11.005

• P2Y(2) purinergic receptor
• M-3 muscarinic receptor
• G beta gamma
• Phospholipase A(2)
• Arachidonic acid
• Ca2+ signalling

We have previously reported that P2Y(2) purinoceptors and muscarinic M-3 receptors trigger Ca2+ responses in HT-29 cells that differ in their timecourse, the Ca2+ response to P2Y(2) receptor activation being marked by a more rapid decline of intracellular Ca2+ Concentration ([Ca2+](i)) after the peak response and that this rapid decline of [Ca2+](i) was slowed in cells expressing heterologous beta-adrenergic receptor kinase (beta ARK). In the present study, we demonstrate that, during P2Y(2) receptor activation, beta ARK expression increases the rate of Gd3+ -sensitive Mn2+ influx, a measure of the rate of store-operated Ca2+ entry from the extracellular space, during P2Y(2) activation and that this effect of beta ARK is mimicked by exogenous alpha-subunits of G(q) G(11) and G(i2). The effect of beta ARK on the rate of Mn2+ influx is thus attributable to its ability to scavenge G protein beta gamma-subunits released during activation of P2Y(2) receptor. We further find that the effect of beta ARK on the rate of Mn2+ influx during P2Y(2) receptor activation can be overcome by arachiclonic acid. In addition, the UTP-induced Mn2+ influx rate was significantly increased by inhibitors of phospholipase A(2) (PLA(2)) and an siRNA directed against PLA(2)beta, but not by an siRNA directed against PLA(2)alpha or by inhibitors of arachiclonic acid metabolism. These findings provide evidence for the existence of a P2Y(2) receptor-activated signalling system that acts in parallel with depletion of intracellular Ca2+ stores to inhibit Ca2+ influx across the cell membrane. This signalling process is mediated via G beta gamma and involves PLA(2)beta and arachiclonic acid.

• 出版日期2010-1