A role for protein kinase C-alpha in zymosan-stimulated eicosanoid synthesis in mouse peritoneal macrophages.
A possible regulatory function of protein kinase C (PKC) isoenzymes in zymosan-stimulated eicosanoid synthesis was studied in mouse peritoneal macrophages in culture. The addition of zymosan to intact cells labelled with [3H]arachidonic acid stimulated a time-dependent and concentration-dependent release of the fatty acid. There was a simultaneous marked increase in the synthesis of prostaglandin E2 and leukotriene C4. The protein-kinase inhibitor K-252a and the selective PKC inhibitor CGP41251 completely blocked zymosan-triggered arachidonic acid release as well as prostaglandin E2 and leukotriene C4 synthesis. In contrast, an inactive staurosporine derivative, CGP42700, failed to inhibit any of the zymosan-induced responses. The down-regulation of PKC by long-term treatment with phorbol 12-myristate 13-acetate eliminated zymosan-stimulated arachidonic acid release and eicosanoid synthesis (after 4-6 h treatment). By using specific antibodies it was observed that mouse macrophages express five PKC isoenzymes, PKC-alpha, -beta, -delta, -epsilon and -zeta. No PKC-gamma isoenzyme was detected. After exposure to phorbol 12-myristate 13-acetate, a complete depletion of PKC-beta was observed within 1 h and the complete depletion of PKC-alpha and PKC-delta isotypes was observed within 4 h. In contrast, PKC-epsilon was only partially down-regulated after a 24-h treatment with phorbol 12-myristate 13-acetate and PKC-zeta was not affected at all. These data indicate that PKC-alpha and PKC-delta isoenzymes are candidates for regulating prostaglandin and leukotriene production. From the potent inhibitory activities of K-252a and CGP41251, two compounds that reportedly display a higher selectivity for PKC-alpha compared to PKC-delta, it is suggested that PKC-alpha triggers arachidonic acid mobilization and eicosanoid synthesis in peritoneal macrophages.
Huwiler
A
A
Department of Pharmacology, University of Basel, Switzerland.
Pfeilschifter
J
J
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D002478:Cells, Cultured; D015232:Dinoprostone / Q000096:biosynthesis; D015777:Eicosanoids / Q000096:biosynthesis*; D005227:Fatty Acids / Q000378:metabolism; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D017997:Leukotriene C4 / Q000096:biosynthesis; D017737:Macrophages, Peritoneal / Q000378:metabolism*; D051379:Mice; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019311:Staurosporine / Q000031:analogs & derivatives*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015054:Zymosan / Q000494:pharmacology*
D000470:Alkaloids; D015777:Eicosanoids; D005227:Fatty Acids; D007527:Isoenzymes; D016718:Arachidonic Acid; D017997:Leukotriene C4; D015054:Zymosan; D011493:Protein Kinase C; D019311:Staurosporine; C059539:midostaurin; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate