title: Synergistic antiproliferative actions of cyclic adenosine 3',5'-monophosphate, interleukin-1beta, and activators of Ca2+/calmodulin-dependent protein kinase in primary hepatocytes.
abstract: cAMP and Ca2+ acted together with the acute phase cytokine interleukin-1beta (IL-1beta) to inhibit hepatocyte DNA replication. At sub-basal activity of cAMP-dependent protein kinase (PKA), neither IL-1beta nor the Ca2+-elevating hormone vasopressin affected hepatocyte proliferation. Basal level of PKA activity permitted IL-1beta action. Increased PKA activity also permitted vasopressin action and sensitized further towards IL-1beta, which acted at 10-50 pM concentrations. Vasopressin acted via Ca2+/calmodulin-dependent protein kinase II (CaMKII), and its action was mimicked by the serine/threonine phosphatase inhibitor microcystin, which activates CaMKII. Inhibitors (KN93 and KT5926) of CaMKII selectively counteracted the effects of vasopressin and microcystin on hepatocyte proliferation at concentrations similar to those required to inhibit CaMKII in vitro. Two-dimensional gel electrophoresis of 32P-prelabeled hepatocytes revealed a common set of proteins phosphorylated in response to vasopressin and microcystin. Their phosphorylation was counteracted by CaMKII inhibitor (KT5926). Phosphorylation of the CaMKII substrate phenylalanine hydroxylase (PAH; EC 1.14.16.1) was used as an endogenous marker of CaMKII activation. It was found that treatment of the cells with vasopressin or microcystin increased the phosphorylation of PAH, and that the vasopressin-induced PAH phosphorylation was inhibited by KT5926. In conclusion, the Ca2+-elevating hormone vasopressin potentiated the antiproliferative effects of cAMP and IL-1beta through CaMKII activation.
authors.affiliation: Department of Anatomy and Cell Biology, University of Bergen, Norway.
authors.forename: G
authors.initials: G
authors.lastname: Mellgren
authors.forename: T
authors.initials: T
authors.lastname: Bruland
authors.forename: A P
authors.initials: AP
authors.lastname: Døskeland
authors.forename: T
authors.initials: T
authors.lastname: Flatmark
authors.forename: O K
authors.initials: OK
authors.lastname: Vintermyr
authors.forename: S O
authors.initials: SO
authors.lastname: Døskeland
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001596:Benzylamines / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D002227:Carbazoles; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D000242:Cyclic AMP / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D004247:DNA / Q000378:metabolism; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007211:Indoles; D007375:Interleukin-1 / Q000494:pharmacology*; D008099:Liver / Q000166:cytology* / Q000201:enzymology* / Q000502:physiology; D008297:Male; D052998:Microcystins; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010651:Phenylalanine Hydroxylase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013449:Sulfonamides / Q000494:pharmacology; D014667:Vasopressins / Q000494:pharmacology*; D000096926:Benzenesulfonamides
chemical_list: D015056:1-Methyl-3-isobutylxanthine; D000470:Alkaloids; D001596:Benzylamines; D002118:Calcium; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002227:Carbazoles; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D004247:DNA; D004791:Enzyme Inhibitors; D007211:Indoles; D007375:Interleukin-1; D052998:Microcystins; D010456:Peptides, Cyclic; D010651:Phenylalanine Hydroxylase; D010750:Phosphoproteins; D013449:Sulfonamides; D014667:Vasopressins; C063769:KT 5926; C072105:KN 93; D000096926:Benzenesulfonamides; C078588:microcystin