title: Calcium has a permissive role in interleukin-1beta-induced c-jun N-terminal kinase activation in insulin-secreting cells.
abstract: The c-jun N-terminal kinase (JNK) signaling pathway mediates IL-1beta-induced apoptosis in insulin-secreting cells, a mechanism relevant to the destruction of pancreatic beta-cells in type 1 and 2 diabetes. However, the mechanisms that contribute to IL-1beta activation of JNK in beta-cells are largely unknown. In this study, we investigated whether Ca(2+) plays a role for IL-1beta-induced JNK activation. In insulin-secreting rat INS-1 cells cultured in the presence of 11 mm glucose, combined pharmacological blockade of L- and T-type Ca(2+) channels suppressed IL-1beta-induced in vitro phosphorylation of the JNK substrate c-jun and reduced IL-1beta-stimulated activation of JNK1/2 as assessed by immunoblotting. Inhibition of IL-1beta-induced in vitro kinase activity toward c-jun after collective L- and T-type Ca(2+) channel blockade was confirmed in primary rat and ob/ob mouse islets and in mouse betaTC3 cells. Ca(2+) influx, specifically via L-type but not T-type channels, contributed to IL-1beta activation of JNK. Activation of p38 and ERK in response to IL-1beta was also dependent on L-type Ca(2+) influx. Membrane depolarization by KCl, exposure to high glucose, treatment with Ca(2+) ionophore A23187, or exposure to thapsigargin, an inhibitor of sarco(endo)plasmic reticulum Ca(2+) ATPase, all caused an amplification of IL-1beta-induced JNK activation in INS-1 cells. Finally, a chelator of intracellular free Ca(2+) [bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid-acetoxymethyl], an inhibitor of calmodulin (W7), and inhibitors of Ca(2+)/calmodulin-dependent kinase (KN62 and KN93) partially reduced IL-1beta-stimulated c-jun phosphorylation in INS-1 or betaTC3 cells. Our data suggest that Ca(2+) plays a permissive role in IL-1beta activation of the JNK signaling pathway in insulin-secreting cells.
authors.affiliation: Laboratory for Beta-Cell Biology, Steno Diabetes Center, Niels Steensensvej 8, NSPP, DK-2820 Gentofte, Denmark. jstq@steno.dk
authors.forename: Joachim
authors.initials: J
authors.lastname: Størling
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Zaitsev
authors.forename: Iouri L
authors.initials: IL
authors.lastname: Kapelioukh
authors.forename: Allan E
authors.initials: AE
authors.lastname: Karlsen
authors.forename: Nils
authors.initials: N
authors.lastname: Billestrup
authors.forename: Per-Olof
authors.initials: PO
authors.lastname: Berggren
authors.forename: Thomas
authors.initials: T
authors.lastname: Mandrup-Poulsen
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002460:Cell Line; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007375:Interleukin-1 / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000378:metabolism; D007515:Islets of Langerhans / Q000201:enzymology / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D020748:Mibefradil / Q000494:pharmacology; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D009553:Nimodipine / Q000494:pharmacology; D051381:Rats; D011920:Rats, Inbred WF; D015398:Signal Transduction / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D002121:Calcium Channel Blockers; D007328:Insulin; D007375:Interleukin-1; D016328:NF-kappa B; D020748:Mibefradil; D009553:Nimodipine; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium