title: A CAR-responsive enhancer element locating approximately 31 kb upstream in the 5'-flanking region of rat cytochrome P450 (CYP) 3A1 gene.
abstract: Constitutive androstane receptor (CAR) is one of the principal regulators of hepatic cytochrome P450s (CYPs) 3A (CYP3A). cDNA-mediated expression of a mature rat CAR (rCAR) into rat hepatoma cells induced CYP3A1 and CYP2B mRNAs. Aberrant rCAR failed in these inductions. Three important human CYP3A4 regulatory elements (REs), proximal ER6 (proER6), xenobiotic responsive enhancer module (XREM) and constitutive liver enhancer module (CLEM), support constitutive and inducible expression of CYP3As mediated by CAR and pregnane X receptor (PXR). NHR-scan software predicted proER6, XREM and CLEM at -255 b, -8 kb and -11.5 kb, respectively of CYP3A4, but neither XREM nor CLEM was predicted in rat CYP3A. A luciferase reporter construct carrying a 5'-flanking sequence of CYP3A1 (-31,739 to -31,585 from its transcription initiation site) revealed important for the rCAR-dependent transactivation of CYP3A1. This region includes two putative binding motifs of nuclear receptors (DR4 and DR2), a putative hepatocyte nuclear factor-1 binding motif (HNF1), nuclear factor-kappa B binding motif (NFκB), activator protein 1 binding motif (AP-1), and ecotropic viral integration site 1 binding motif (Evi1). We hereby conclude DR4 and/or DR2 motifs being primarily responsible and HNF1 being synergistically functioning elements for the rCAR-mediated transcription of CYP3A1.
authors.affiliation: Department of Pharmacodynamics and Molecular Genetics, School of Pharmacy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba-cho, Shiwa-gun, Iwate 028-3694, Japan.
authors.forename: Toshie
authors.initials: T
authors.lastname: Gamou
authors.affiliation: Department of Pharmacodynamics and Molecular Genetics, School of Pharmacy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba-cho, Shiwa-gun, Iwate 028-3694, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Habano
authors.affiliation: Department of Pharmacodynamics and Molecular Genetics, School of Pharmacy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba-cho, Shiwa-gun, Iwate 028-3694, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Terashima
authors.affiliation: Department of Pharmacodynamics and Molecular Genetics, School of Pharmacy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba-cho, Shiwa-gun, Iwate 028-3694, Japan. Electronic address: sozawa@iwate-med.ac.jp.
authors.forename: Shogo
authors.initials: S
authors.lastname: Ozawa
mesh_terms: D024506:5' Flanking Region; D000818:Animals; D001665:Binding Sites; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000235:genetics; D045744:Cell Line, Tumor; D000090702:Constitutive Androstane Receptor; D051544:Cytochrome P-450 CYP3A / Q000235:genetics* / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D051537:Hepatocyte Nuclear Factor 1 / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology*; D008113:Liver Neoplasms / Q000201:enzymology / Q000235:genetics; D008297:Male; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D011916:Rats, Inbred F344; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000378:metabolism; D020218:Response Elements; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014233:Tricarboxylic Acids / Q000494:pharmacology
chemical_list: D000090702:Constitutive Androstane Receptor; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D014233:Tricarboxylic Acids; D051537:Hepatocyte Nuclear Factor 1; D003907:Dexamethasone; C465138:Cyp3a23-3a1 protein, rat; D051544:Cytochrome P-450 CYP3A
keywords: CYP3A family; Constitutive androstane receptor (CAR); Cytochrome P450; Enzyme induction; Nuclear receptor