title: Sequence diversity and functional characterization of the 5'-regulatory region of human CYP2C19.
abstract: Cytochrome p4502C19 (CYP2C19) plays an important role in drug biotransformation and has been shown to be genetically polymorphic. While polymorphisms in the coding region that have large effects on activity are well described, until recently, a lack of knowledge of the promoter sequence has hindered efforts to study it. Genetic variants in the promoter region have not been described and factors that influence its gene expression via promotor regulation remain largely undefined. We have cloned and sequenced 1.8 kb of the human CYP2C19 promoter. This promoter contains a number of putative transcription factor sites, including HepG2-specific factor 1, glucocorticoid response element, estrogen receptor element, constitutive androstane receptor and peroxisome proliferator-activated receptor. Sequencing of DNA obtained from 67 individuals identified eight single nucleotide polymorphisms within this region. No sequence of a known human pregnane X receptor response element was found in this section of the CYP2C19 promoter, despite the known effect of rifampin on the expression of this gene. A plasmid containing the 1.8-kb CYP2C19 promoter coupled to a luciferase reporter gene has been constructed and demonstrated to be functional and sensitive to induction by omeprazole in HuH7 cells. Nested deletions of CYP2C19 promoter were generated and the ability of serial promoter deletion constructs to activate luciferase expression in the HepG2 cell line was analysed. These data make possible future studies to elucidate the molecular mechanisms by which CYP2C19 can be induced in clinical settings and the consequences of genetic variability in its promoter.
authors.affiliation: Department of Medicine Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
authors.forename: Million
authors.initials: M
authors.lastname: Arefayene
authors.forename: Todd C
authors.initials: TC
authors.lastname: Skaar
authors.forename: Xiaojiong
authors.initials: X
authors.lastname: Zhao
authors.forename: James M
authors.initials: JM
authors.lastname: Rae
authors.forename: Jose E
authors.initials: JE
authors.lastname: Tanus-Santos
authors.forename: Ulrich
authors.initials: U
authors.lastname: Brinkmann
authors.forename: Ilka
authors.initials: I
authors.lastname: Brehm
authors.forename: Ulrike
authors.initials: U
authors.lastname: Salat
authors.forename: Anne
authors.initials: A
authors.lastname: Nguyen
authors.forename: Zeruesenay
authors.initials: Z
authors.lastname: Desta
authors.forename: David A
authors.initials: DA
authors.lastname: Flockhart
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D017931:DNA Primers; D014644:Genetic Variation; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D009853:Omeprazole / Q000494:pharmacology; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: D017931:DNA Primers; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D008156:Luciferases; D009853:Omeprazole