title: A common regulatory region functions bidirectionally in transcriptional activation of the human CYP1A1 and CYP1A2 genes.
abstract: The human CYP1A1 and CYP1A2 genes on chromosome 15 are orientated head-to-head and are separated by a 23-kilobase (kb) intergenic spacer region. Thus, the possibility exists for sharing common regulatory elements contained in the spacer region responsible for transcriptional activation and regulation of the CYP1A1 and CYP1A2 genes. In the present study, a reporter gene construct containing -22.4 kb of the 5'-flanking region of the CYP1A2 gene was found to support beta-naphthoflavone (BNF) and 3-methylchoranthrene (3-MC)-mediated transcriptional activation. The responsive region was also functional in directing activation of the CYP1A1 promoter, indicating that the region works bidirectionally to govern transcriptional activation of both CYP1A1 and CYP1A2. To simultaneously evaluate transcriptional activation of both genes, a dual reporter vector was developed in which the spacer region was inserted between two different reporter genes, firefly luciferase and secreted alkaline phosphatase. Transient transfection of the dual reporter vector in HepG2 cells revealed increases in both reporter activities after exposure of the cells to BNF and 3-MC. Deletion studies of the spacer region indicated that a region from -464 to -1829 of the CYP1A1 gene works bidirectionally to enhance the transcriptional activation of not only CYP1A1 but also CYP1A2. In addition, a negative bidirectional regulatory region was found to exist from -18,989 to -21,992 of the CYP1A1 gene. These data established that induction of human CYP1A1 and CYP1A2 is simultaneously controlled through bidirectional and common regulatory elements.
authors.affiliation: Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki-Aoba 6-3, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Rika
authors.initials: R
authors.lastname: Ueda
authors.forename: Hiromi
authors.initials: H
authors.lastname: Iketaki
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Nagata
authors.forename: Shioko
authors.initials: S
authors.lastname: Kimura
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Gonzalez
authors.forename: Kazutomi
authors.initials: K
authors.lastname: Kusano
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Yoshimura
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yamazoe
mesh_terms: D024506:5' Flanking Region / Q000502:physiology; D001551:Benz(a)Anthracenes / Q000494:pharmacology; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics* / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D008748:Methylcholanthrene; D012333:RNA, Messenger / Q000378:metabolism; D020218:Response Elements / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D017384:Sequence Deletion; D015533:Transcriptional Activation; D019324:beta-Naphthoflavone / Q000494:pharmacology
chemical_list: D001551:Benz(a)Anthracenes; D012333:RNA, Messenger; D008748:Methylcholanthrene; D019324:beta-Naphthoflavone; C504573:CYP1A2 protein, human; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2