title: Cholinergic activation of glucose transport in bovine chromaffin cells involves calmodulin and protein kinase Czeta signaling.
abstract: The aim of the present study was to delineate possible signaling pathways involved in acetylcholine (Ach)-induced glucose transport in chromaffin cells, a widely applied model system for sympathetic neurons. Acute Ach stimulation (10 min) enhanced the rate of glucose transport through activation of both nicotinic and muscarinic receptors. The calmodulin antagonist, W13, and the protein kinase C (PKC) inhibitor, staurosporine, each partially depressed Ach-induced glucose transport, with staurosporine exhibiting the stronger inhibitory effect. Pretreating the cells with phorbol 12-myristate 13-acetate (PMA) to downregulate PKC activity did not affect the nicotine-induced glucose transport, but completely attenuated that activated by muscarine, suggesting that Ach activation of transport involved both diacylglycerol-independent (PKCzeta) and diacylglycerol-dependent PKCs (PKCalpha/PKCepsilon). The PI 3-kinase inhibitor, wortmannin, diminished the Ach response, consistent with activation of the PKCs by the upstream PI 3-kinase-dependent phosphoinositide-dependent kinase, PDK1. Cholinergic activation strongly activated the ERK1/ERK2 cascade and p38 MAP kinase, but only p38 MAP kinase appeared to play a role, however minor, in nicotine-induced glucose uptake. The results are consistent with PKCs being more important than calmodulin in coupling cholinergic activation to glucose transport in chromaffin cells, but additional, yet unidentified, signaling pathways appear to be needed to obtain full activation of glucose transport in response to Ach.
authors.affiliation: Department of Physiology, University of Bergen, Bergen,Norway. guldborg.serck-hanssen@fys.uib.no
authors.forename: Guldborg
authors.initials: G
authors.lastname: Serck-Hanssen
authors.forename: Mona
authors.initials: M
authors.lastname: Grønning
authors.forename: Cathrine
authors.initials: C
authors.lastname: Fladeby
authors.forename: Robert
authors.initials: R
authors.lastname: Skar
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D015152:Blotting, Northern; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002417:Cattle; D018679:Cholinergic Agonists / Q000494:pharmacology*; D019439:Chromaffin Cells / Q000378:metabolism / Q000502:physiology*; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009153:Mutagens; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D019311:Staurosporine / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate; D013997:Time Factors; D000077191:Wortmannin; D048051:p38 Mitogen-Activated Protein Kinases; D000099221:Protein Kinase C zeta
chemical_list: D000109:Acetylcholine; D000730:Androstadienes; D002147:Calmodulin; D018679:Cholinergic Agonists; D004791:Enzyme Inhibitors; D019833:Genistein; D005947:Glucose; D020928:Mitogen-Activated Protein Kinases; D009153:Mutagens; D011493:Protein Kinase C; D019311:Staurosporine; D013449:Sulfonamides; D013755:Tetradecanoylphorbol Acetate; D000077191:Wortmannin; D048051:p38 Mitogen-Activated Protein Kinases; D000099221:Protein Kinase C zeta; C033772:N-(4-aminobutyl)-5-chloro-2-naphthalenesulfonamide