title: Ca2+ influx through L-type Ca2+ channels and Ca2+-induced Ca2+ release regulate cAMP accumulation and Epac1-dependent ERK 1/2 activation in INS-1 cells.
abstract: We previously reported that INS-1 cells expressing the intracellular II-III loop of the L-type Ca(2+) channel Cav1.2 (Cav1.2/II-III cells) are deficient in Ca(2+)-induced Ca(2+) release (CICR). Here we show that glucose-stimulated ERK 1/2 phosphorylation (GSEP) is slowed and reduced in Cav1.2/II-III cells compared to INS-1 cells. This parallels a decrease in glucose-stimulated cAMP accumulation (GS-cAMP) in Cav1.2/II-III cells. Influx of Ca(2+) via L-type Ca(2+) channels and CICR play roles in both GSEP and GS-cAMP in INS-1 cells since both are inhibited by nicardipine or ryanodine. Further, the Epac1-selective inhibitor CE3F4 abolishes glucose-stimulated ERK activation in INS-1 cells, as measured using the FRET-based sensor EKAR. The non-selective Epac antagonist ESI-09 but not the Epac2-selective antagonist ESI-05 nor the PKA antagonist Rp-cAMPs inhibits GSEP in both INS-1 and Cav1.2/II-III cells. We conclude that L-type Ca(2+) channel-dependent cAMP accumulation, that's amplified by CICR, activates Epac1 and drives GSEP in INS-1 cells.
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA; Purdue University Life Sciences Graduate Program, Purdue University, West Lafayette, IN, USA.
authors.forename: Evan P S
authors.initials: EP
authors.lastname: Pratt
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Salyer
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA.
authors.forename: Marcy L
authors.initials: ML
authors.lastname: Guerra
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA. Electronic address: gregh@purdue.edu.
authors.forename: Gregory H
authors.initials: GH
authors.lastname: Hockerman
mesh_terms: D000818:Animals; D001555:Benzene Derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D009529:Nicardipine / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011804:Quinolines / Q000494:pharmacology; D051381:Rats; D012433:Ryanodine / Q000494:pharmacology; D013450:Sulfones / Q000494:pharmacology
chemical_list: C588037:6-fluoro-5,7-dibromo-2-methyl-1-formyl-1,2,3,4-tetrahydroquinoline; D001555:Benzene Derivatives; D020746:Calcium Channels, L-Type; C000589230:ESI-05; D020662:Guanine Nucleotide Exchange Factors; D011804:Quinolines; C526973:Rapgef3 protein, rat; D013450:Sulfones; D012433:Ryanodine; D009529:Nicardipine; D000242:Cyclic AMP; D005947:Glucose; D002118:Calcium
keywords: Ca(2+)-induced Ca(2+) release; Ca(v)1.2; Exchange protein directly activated by cAMP; Extracellular signal regulated kinase 1/2; L-type Ca(2+) channel; Pancreatic beta-cell; cAMP