title: Molecular mechanisms of muscarinic acetylcholine receptor-stimulated increase in cytosolic free Ca(2+) concentration and ERK1/2 activation in the MIN6 pancreatic β-cell line.
abstract: Muscarinic acetylcholine receptor (mAChR) activation of pancreatic β-cells elevates intracellular Ca(2+) and potentiates glucose-stimulated insulin secretion. In addition, it activates a number of signaling molecules, including ERK1/2, whose activation has been shown to play an important role in regulating pancreatic β-cell function and mass. The aim of this work was to determine how mAChR activation elevates intracellular Ca(2+) concentration ([Ca(2+)](                            i                         )) and activates ERK1/2 in the pancreatic β-cell line MIN6. We demonstrate that agonist-stimulated ERK1/2 activation is dependent on the activation of phospholipase C and an elevation in [Ca(2+)](                            i                         ), but is independent of the activation of diacylglycerol-dependent protein kinase C isoenzymes. Using a pharmacological approach, we provide evidence that agonist-induced increases in [Ca(2+)](                            i                         ) and ERK activity require (1) IP(3) receptor-mediated mobilization of Ca(2+) from the endoplasmic reticulum, (2) influx of extracellular Ca(2+) through store-operated channels, (3) closure of K(ATP) channels, and (4) Ca(2+) entry via L-type voltage-operated Ca(2+) channels. Moreover, this Ca(2+)-dependent activation of ERK is mediated via both Ras-dependent and Ras-independent mechanisms. In summary, this study provides important insights into the multifactorial signaling mechanisms linking mAChR activation to increases in [Ca(2+)](                            i                         ) and ERK activity.
authors.affiliation: Department of Cell Physiology and Pharmacology, University of Leicester, Henry Wellcome Building, Leicester, LE1 9HN, UK.
authors.forename: Joanne L
authors.initials: JL
authors.lastname: Selway
authors.forename: Claire E
authors.initials: CE
authors.lastname: Moore
authors.forename: Rajendra
authors.initials: R
authors.lastname: Mistry
authors.forename: R A
authors.initials: RA
authors.lastname: John Challiss
authors.forename: Terence P
authors.initials: TP
authors.lastname: Herbert
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D018679:Cholinergic Agonists / Q000494:pharmacology; D004789:Enzyme Activation / Q000502:physiology; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000502:physiology; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation; D011976:Receptors, Muscarinic / Q000502:physiology*; D015398:Signal Transduction; D014162:Transfection; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D018679:Cholinergic Agonists; D053496:Inositol 1,4,5-Trisphosphate Receptors; D011976:Receptors, Muscarinic; D002217:Carbachol; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D010738:Type C Phospholipases; D002118:Calcium