TY - JOUR T1 - Ca<sub>v</sub>1.2 and Ca<sub>v</sub>1.3 Are Differentially Coupled to Glucagon-Like Peptide-1 Potentiation of Glucose-Stimulated Insulin Secretion in the Pancreatic β-Cell Line INS-1 JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 724 LP - 732 DO - 10.1124/jpet.109.158519 VL - 331 IS - 2 AU - Sarah Melissa P. Jacobo AU - Marcy L. Guerra AU - Gregory H. Hockerman Y1 - 2009/11/01 UR - http://jpet.aspetjournals.org/content/331/2/724.abstract N2 - The incretin peptides, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), potentiate glucose-stimulated insulin secretion (GSIS) and β-cell proliferation and differentiation. Ca2+ influx via voltage-gated L-type Ca2+ channels is required for GLP-1 and GIP potentiation of GSIS. We investigated the role of the L-type Ca2+ channels Cav1.2 and Cav1.3 in mediating GLP-1- and GIP-stimulated events in INS-1 cells and INS-1 cell lines expressing dihydropyridine-insensitive (DHPi) mutants of either Cav1.2 or Cav1.3. Cav1.3/DHPi channels supported full potentiation of GSIS by GLP-1 (50 nM) compared with untransfected INS-1 cells. However, GLP-1-potentiated GSIS mediated by Cav1.2/DHPi channels was markedly reduced compared with untransfected INS-1 cells. In contrast, GIP (10 nM) potentiation of GSIS mediated by both Cav1.2/DHPi and Cav1.3/DHPi channels was similar to that observed in untransfected INS-1 cells. Disruption of intracellular Ca2+ release with thapsigargin, ryanodine, or 2-aminoethyldiphenylborate and inhibition of protein kinase A (PKA) or protein kinase C (PKC) significantly reduced GLP-1 potentiation of GSIS by Cav1.3/DHPi channels and by endogenous L-type channels in INS-1 cells, but not by Cav1.2/DHPi channels. Inhibition of glucose-stimulated phospholipase C activity with 1-(6-((17b-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122) did not inhibit potentiation of GSIS by GLP-1 in INS-1 cells. In contrast, wortmannin, an inhibitor of phosphatidylinositol 3-kinase, and 2′-amino-3′-methoxyflavone (PD98059), an inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase, both markedly inhibited GLP-1 potentiation of GSIS by endogenous channels in INS-1 cells and Cav1.3/DHPi channels, but not by Cav1.2/DHPi channels. Thus, Cav1.3 is preferentially coupled to GLP-1 potentiation of GSIS in INS-1 cells via a mechanism that requires intact intracellular Ca2+ stores, PKA and PKC activity, and activation of ERK1/2. © 2009 by The American Society for Pharmacology and Experimental Therapeutics ER -