Role for mitogen-activated protein kinases in phenobarbital-induced expression of cytochrome P450 2B in primary cultures of rat hepatocytes.
Phenobarbital (PB) alters expression of numerous hepatic genes, including genes of cytochrome P450 2B1 and 2B2 (CYP2B). However, the intracellular mechanisms remain to be fully elucidated. The present study investigated the involvement of mitogen-activated protein kinases (MAPKs) in rat hepatocytes in primary culture. We showed that PB induced an early, dose-dependent activation of ERK (extracellular signal-regulated kinase), JNK (c-Jun N-terminal kinase) and p38 MAPKs. Regarding the PB (1mM) induction of CYP2B mRNA expression, while chemically inhibiting JNK had no effect, specific inhibitors of the ERK (U0-126) and p38 (SB-203580) pathways up- and down-regulated this expression, respectively. However, although such a regulation was confirmed when testing the effect of a dominant negative mutant of the ERK pathway on the CYP2B2 enhancer-promoter activity, no such transcriptional role was found with the p38 pathway. Moreover, upon arrest of transcription, the stability of CYP2B mRNA remained unaffected by SB-203580. In conclusion, we show that the ERK pathway negatively regulates CYP2B2 enhancer-promoter activity and that, despite p38 activation upon PB exposure, the sensitivity of CYP2B mRNA expression to SB-203580 appears to be unrelated to this kinase.
Joannard
Florence
F
INSERM UMR 620, Faculté de Pharmacie, Université Rennes 1, 2 av Prof Léon Bernard, 35043 Rennes Cedex, France.
Rissel
Mary
M
Gilot
David
D
Anderson
Alan
A
Orfila-Lefeuvre
Luz
L
Guillouzo
André
A
Atfi
Azzedine
A
Lagadic-Gossmann
Dominique
D
D000818:Animals; D015152:Blotting, Northern; D002070:Butadienes / Q000494:pharmacology; D002478:Cells, Cultured; D019362:Cytochrome P-450 CYP2B1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D004004:Dichlororibofuranosylbenzimidazole / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007093:Imidazoles / Q000494:pharmacology; D049409:Luciferases, Firefly / Q000235:genetics / Q000378:metabolism; D008297:Male; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology; D010634:Phenobarbital / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
D002070:Butadienes; D004791:Enzyme Inhibitors; D007093:Imidazoles; D009570:Nitriles; D011725:Pyridines; D012333:RNA, Messenger; C465539:SB202494; C113580:U 0126; D004004:Dichlororibofuranosylbenzimidazole; D049409:Luciferases, Firefly; D019362:Cytochrome P-450 CYP2B1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580; D010634:Phenobarbital