Role of Regulators of G-Protein Signaling 4 in Ca(2+) Signaling in Mouse Pancreatic Acinar Cells

Regulators of G-protein signaling (RGS) proteins are regulators of Ca(2+) signaling that accelerate the GTPase activity of the G-protein α-subunit. RGS1, RGS2, RGS4, and RGS16 are expressed in the pancreas, and RGS2 regulates G-protein coupled receptor (GPCR)-induced Ca(2+) oscillations. However, the role of RGS4 in Ca(2+) signaling in pancreatic acinar cells is unknown. In this study, we investigated the mechanism of GPCR-induced Ca(2+) signaling in pancreatic acinar cells derived from RGS4(-/-) mice. RGS4(-/-) acinar cells showed an enhanced stimulus intensity response to a muscarinic receptor agonist in pancreatic acinar cells. Moreover, deletion of RGS4 increased the frequency of Ca(2+) oscillations. RGS4(-/-) cells also showed increased expression of sarco/endoplasmic reticulum Ca(2+) ATPase type 2. However, there were no significant alterations, such as Ca(2+) signaling in treated high dose of agonist and its related amylase secretion activity, in acinar cells from RGS4(-/-) mice. These results indicate that RGS4 protein regulates Ca(2+) signaling in mouse pancreatic acinar cells.