Acidic fibroblast factor induction of cyclooxygenase II in rabbit cardiac muscle microvessel endothelial cells: mediation by protein kinase C.
OBJECTIVE
To determine if the novel cyclooxygenase, COX II, was induced by acidic fibroblast growth factor (aFGF) in rabbit cardiac muscle microvessel (RCME) endothelial cells and to determine the role of protein kinase C (PKC) activation in the mediation of the aFGF induction of COX activity.


METHODS
Cultured RCME cells were treated with aFGF (200 ng/ml). Induction of COX II activity was assessed by determination of COX activity (PGE2 production), by immunoprecipitation of metabolically labeled COX II, and by Northern analyses. The role of PKC was assessed using phorbol myristate acetate and PKC inhibitors and by determination of PKC activity in cytosol and membrane fractions of RCME cells treated with aFGF and phorbol myristate acetate.


RESULTS
aFGF selectively induced COX II protein and mRNA. Protein kinase C activation was implicated in the transduction of the effects of aFGF for the following reasons: (1) phorbol myristate acetate (PMA), a direct activator of protein kinase C, was a potent inducer of COX II mRNA, COX activity and synthesis of COX II protein. (2) H-7, an inhibitor of PKC, but not the inactive control, HA-1004, blocked aFGF induction of COX II mRNA, COX II protein synthesis, and COX activity. Two additional inhibitors of PKC, calphostin C and staurosporine, also inhibited aFGF induction of COX activity. (3) Downregulation of PKC by overnight incubation with 1 microM PMA blocked subsequent induction of COX II protein synthesis by aFGF. (4) aFGF treatment of RCME cells resulted in the translocation of PKC activity from the cytosol to the membrane fraction. However, aFGF, at concentrations that elicited COX II, neither induced Ca2+ mobilization from intracellular stores nor increased the accumulation of inositol phosphates.


CONCLUSIONS
aFGF induces COX II in RCME and this response in mediated, at least in part, by protein kinase C activation. However, aFGF mediated activation of PKC activation must stimulate this kinase through a pathway of signal transduction distinct from inositol phospholipid accumulation or elevation of intracellular Ca2+.
Moatter
T
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Department of Physiology, New York Medical College, Valhalla, New York, USA.
Gerritsen
M E
ME
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D015152:Blotting, Northern; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016220:Fibroblast Growth Factor 1 / Q000494:pharmacology*; D007295:Inositol Phosphates / Q000378:metabolism; D007527:Isoenzymes / Q000096:biosynthesis*; D007546:Isoquinolines / Q000494:pharmacology; D008833:Microcirculation; D009206:Myocardium / Q000201:enzymology*; D009281:Naphthalenes / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D019311:Staurosporine; D013449:Sulfonamides
D000470:Alkaloids; D004791:Enzyme Inhibitors; D007295:Inositol Phosphates; D007527:Isoenzymes; D007546:Isoquinolines; D009281:Naphthalenes; D010879:Piperazines; D012333:RNA, Messenger; D013449:Sulfonamides; D016220:Fibroblast Growth Factor 1; D016718:Arachidonic Acid; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C043204:N-(2-guanidinoethyl)-5-isoquinolinesulfonamide; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D011493:Protein Kinase C; D019311:Staurosporine; C058819:calphostin C; D015232:Dinoprostone