Independent regulation of cyclo-oxygenase 2 expression by p42/44 mitogen-activated protein kinases and Ca2+/calmodulin-dependent kinase.
5-Hydroxytryptamine (5-HT, 'serotonin') is a potent inducer of the early response gene cyclo-oxygenase 2 (Cox-2; prostaglandin G/H synthase) in mesangial cells. Protein kinase C (PKC), Ca2+-dependent enzymes and mitogen-activated protein kinase (p42/44 MAPK) have previously been shown to be essential modules of the signalling pathway leading from the pertussis-insensitive 5-HT2A receptor to the induction of Cox-2 mRNA expression. In the present study, PKC activation was linked to the 5-HT-mediated phosphorylation and thus the activation of p42/44 MAPK: the inhibition of PKC by the specific inhibitor GF109203x prevented p42/44 MAPK activation. Ca2+/calmodulin-dependent (CaM) kinase II delta2 was detected in mesangial cells by Western blot analysis. The inhibition of CaM kinase by the inhibitors KN62 or KN93 led to a partial inhibition of 5-HT-induced Cox-2 mRNA expression and decreased basal, but not PMA-mediated, Cox-2 expression. The 5-HT-mediated activation of MAPK was not decreased by KN62 or KN93, excluding CaM kinase as a signalling module upstream of p42/44 MAPK. Taken together, these results indicate a modulatory involvement of CaM kinase in the regulation of 5-HT-mediated Cox-2 mRNA expression in addition to the main pathway that consists of the activation of PKC and p42/44 MAPK.
Goppelt-Struebe
M
M
Medizinische Klinik IV, Universität Erlangen-Nürnberg, Loschgestrasse 8, D-91054 Erlangen, Germany.
Hahn
A
A
Stroebel
M
M
Reiser
C O
CO
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005920:Glomerular Mesangium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D012701:Serotonin / Q000494:pharmacology; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007527:Isoenzymes; D012333:RNA, Messenger; D012701:Serotonin; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate