title: Possible role of protein kinase C-epsilon isoenzyme in inhibition of interleukin 1 beta induction of nitric oxide synthase in rat renal mesangial cells.
abstract: In cultured glomerular mesangial cells, interleukin 1 beta (IL-1 beta) has been shown to induce a dose- and time-dependent accumulation of nitrite, a stable metabolite of nitric oxide (NO). In parallel, increased levels of mRNA of an inducible macrophage-type of nitric oxide synthase (iNOS) were observed after incubating mesangial cells with IL-1 beta. Here we report that addition of the biologically active phorbol esters, phorbol 12-myristate 13-acetate (PMA) and phorbol 12,13-dibutyrate (PDBu), dose-dependently inhibited the IL-1 beta-stimulated increase in iNOS mRNA levels and nitrite production. In contrast, the biologically inactive phorbol ester 4 alpha-phorbol 12,13-didecanoate, had no effect on cytokine induction of iNOS and nitrite formation. Incubation of mesangial cells with PMA or PDBu alone, in the absence of IL-1 beta, did not trigger any iNOS expression. Time-course studies indicated that phorbol ester needs to be added for only 1 h in order to maximally inhibit cytokine-induced nitrite production. Down-regulation of protein kinase C (PKC)-alpha and -delta isoenzymes by 8 h PMA or PDBu treatment before stimulation with IL-1 beta still resulted in full inhibition of iNOS induction. In contrast, a 24 h treatment of mesangial cells with PMA or PDBu, a regimen that also causes depletion of PKC-epsilon, abolished inhibition of IL-1 beta-induced iNOS expression and nitrite production. In addition, the selective PKC inhibitor calphostin C potentiated IL-1 beta induction of iNOS activity. In summary these data suggest that IL-1 beta induction of iNOS expression is tonically suppressed by PKC and the epsilon-isoenzyme is the most likely candidate mediating this effect.
authors.affiliation: Department of Pharmacology, University of Basel, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Mühl
authors.forename: J
authors.initials: J
authors.lastname: Pfeilschifter
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D015152:Blotting, Northern; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D005920:Glomerular Mesangium / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D007375:Interleukin-1 / Q000494:pharmacology*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology*; D009245:NADH Dehydrogenase / Q000187:drug effects / Q000378:metabolism; D009281:Naphthalenes; D019001:Nitric Oxide Synthase; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D010703:Phorbol Esters / Q000494:pharmacology; D011083:Polycyclic Compounds / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D007375:Interleukin-1; D007527:Isoenzymes; D009281:Naphthalenes; D010703:Phorbol Esters; D011083:Polycyclic Compounds; D012333:RNA, Messenger; C008876:phorbol-12,13-didecanoate; D015240:Phorbol 12,13-Dibutyrate; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D009245:NADH Dehydrogenase; D011493:Protein Kinase C; C058819:calphostin C; D013755:Tetradecanoylphorbol Acetate