title: Characterization of a phenobarbital-responsive enhancer module in mouse P450 Cyp2b10 gene.
abstract: Induction of drug- and carcinogen-metabolizing cytochrome P450s by xenobiotic chemicals is a common cellular defense mechanism, usually leading to increased detoxification of xenobiotics but sometimes, paradoxically, to formation of more toxic and carcinogenic metabolites. Phenobarbital (PB) is an archetypal representative for chemicals including industrial solvents, pesticides, plant products, and clinically used drugs that induce several genes within CYP subfamilies 2B, 2A, 2C, and 3A in rodents and humans. Although the transcription of these CYP genes is activated by PB, the associated molecular mechanisms have not yet been elucidated. Here we have analyzed, in detail, enhancer activity of a far upstream region of mouse Cyp2b10 gene and report a 132-base pair PB-responsive enhancer module (PBREM) with a 33-base pair core element containing binding sites for nuclear factor I- and nuclear receptor-like factors. Mutations of these binding sites abolish the ability of PBREM to respond to inducers in mouse primary hepatocytes.
authors.affiliation: Pharmacogenetics Section, Laboratory of Reproductive and Developmental Toxicology, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
authors.forename: P
authors.initials: P
authors.lastname: Honkakoski
authors.forename: M
authors.initials: M
authors.lastname: Negishi
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D001482:Base Composition; D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000235:genetics*; D000072467:Cytochrome P450 Family 2; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic / Q000187:drug effects*; D004790:Enzyme Induction; D006801:Humans; D008099:Liver / Q000201:enzymology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D010634:Phenobarbital / Q000494:pharmacology*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis; D013250:Steroid Hydroxylases; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D051840:Y-Box-Binding Protein 1
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C101679:Cyp2b10 protein, mouse; D000072467:Cytochrome P450 Family 2; D010634:Phenobarbital