In vivo phenobarbital treatment increases protein binding to a putative AP-1 site in the CYP2B2 promoter.
Phenobarbital (PB) is a potent inducer of cytochrome P450 enzymes, particularly CYP2B1/2B2. Although the mechanism(s) of PB induction of CYP2B1/2B2 is not fully understood, current research is focusing on the role PB may play in altering the binding of nuclear proteins to critical DNA response elements in the 5'-flanking region of these genes. In this study, rat liver nuclear proteins were analyzed for DNA binding ability using both a general consensus and a CYP2B2 sequence-specific AP-1 oligonucleotide. We demonstrate that in vivo PB treatment enhances protein binding activity to the consensus AP-1 oligonucleotide. Likewise, a putative AP-1 site, identified at -1441 in the CYP2B2 5'-flanking region, also formed a sequence specific DNA/protein complex which was enhanced after PB exposure. These data may support a role of AP-1 in the PB induction mechanism of CYP2B1/2B2.
Graduate Center for Toxicology, University of Kentucky, Lexington 40536, USA.
A L
AL
Roe
R A
RA
Blouin
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Howard
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D001665:Binding Sites; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D008297:Male; D009687:Nuclear Proteins / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides / Q000235:genetics / Q000378:metabolism; D010634:Phenobarbital / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D013250:Steroid Hydroxylases / Q000235:genetics*; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*
D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D018808:Transcription Factor AP-1; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C025619:steroid 16-beta-hydroxylase; D010634:Phenobarbital