Cyclooxygenase-2 expression in macrophages: modulation by protein kinase C-alpha.
Cyclooxygenase-2 (COX-2) is an inducible enzyme responsible for high levels of PG production during inflammation and immune responses. Previous studies with pharmacological inhibitors suggested a role for protein kinase C (PKC) in PG production possibly by regulating COX-2 expression. In this study, we addressed the role of PKC-alpha in the modulation of COX-2 expression and PGE2 synthesis by the overexpressing of a dominant-negative (DN) mutant of this isoenzyme in the mouse macrophage cell line RAW 264.7. We investigated the effect of various stimuli on COX-2 expression, namely, LPS, IFN-gamma, and the intracellular parasite Leishmania donovani. Whereas LPS-induced COX-2 mRNA and protein expression were down-regulated in DN PKC-alpha-overexpressing clones, IFN-gamma-induced COX-2 expression was up-regulated in DN PKC-alpha-overexpressing clones with respect to normal RAW 264.7 cells. Measurements of PGE2 levels revealed a strong correlation between PGE2 secretion and IFN-gamma-induced COX-2 mRNA and protein levels in DN PKC-alpha-overexpressing clones. Taken together, these results suggest a role for PKC-alpha in the modulation of LPS- and IFN-gamma-induced COX-2 expression, as well as in IFN-gamma-induced PGE2 secretion.
Giroux
M
M
Institut National de la Recherche Scientifique-Institut Armand-Frappier, Université du Québec, Laval, Canada.
Descoteaux
A
A
D000276:Adjuvants, Immunologic / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D000818:Animals; D002460:Cell Line; D002999:Clone Cells; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism; D004789:Enzyme Activation / Q000235:genetics / Q000276:immunology; D015971:Gene Expression Regulation, Enzymologic / Q000276:immunology; D005799:Genes, Dominant; D007371:Interferon-gamma / Q000494:pharmacology; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007893:Leishmania donovani / Q000254:growth & development / Q000276:immunology; D008264:Macrophages / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism / Q000469:parasitology; D051379:Mice; D010587:Phagocytosis / Q000276:immunology; D011401:Promoter Regions, Genetic / Q000276:immunology; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D011493:Protein Kinase C / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051571:Protein Kinase C-alpha
D000276:Adjuvants, Immunologic; D007527:Isoenzymes; D007371:Interferon-gamma; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D015232:Dinoprostone