Identification of a single nucleotide polymorphism in the TATA box of the CYP2A6 gene: impairment of its promoter activity

Biochem Biophys Res Commun. 2001 Jun 8;284(2):455-60. doi: 10.1006/bbrc.2001.4990.

Abstract

Human cytochrome P450 2A6 (CYP2A6) constitutes the major nicotine oxidase, and large interindividual differences are seen in the levels of this enzyme, to a great extent caused by the distribution of several different polymorphic gene variants mainly located in the open reading frame (ORF). In the present study, we report a common polymorphism located in the 5' flanking region of CYP2A6 affecting its expression. DHPLC analysis and complete sequence of the open reading frame of the gene from a Turkish individual revealed a -48T > G substitution disrupting the TATA box. Using dynamic allele-specific hybridization (DASH), genotyping of this novel variant (named CYP2A6*9) was carried out in 116 Swedish, 132 Turkish, and 102 Chinese subjects, and the allele frequencies were found to be 5.2, 7.2, and 15.7%, respectively. The significance of the polymorphism was investigated by the construction of luciferase reporter plasmids containing 135 or 500 bp of the 5'-upstream region of the gene transfected into human hepatoma B16A2 cells. The constructs carrying the -48T > G mutation were only expressed at about 50% of the wild-type alleles. It is concluded that the CYP2A6*9 allele might be one of the most common CYP2A6 variants in Caucasians that alters the levels of enzyme expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Aryl Hydrocarbon Hydroxylases*
  • Asian Continental Ancestry Group / genetics
  • Cell Line
  • China / ethnology
  • Chromatography, High Pressure Liquid
  • Cytochrome P-450 CYP2A6
  • Cytochrome P-450 Enzyme System / genetics*
  • DNA Mutational Analysis
  • European Continental Ancestry Group / genetics
  • Gene Expression / physiology
  • Genes, Reporter
  • Genetic Testing
  • Genetic Variation
  • Genotype
  • Humans
  • Mixed Function Oxygenases / genetics*
  • Nucleic Acid Denaturation
  • Nucleic Acid Heteroduplexes / analysis
  • Nucleic Acid Heteroduplexes / genetics
  • Nucleic Acid Hybridization / methods
  • Oxidoreductases / genetics*
  • Polymorphism, Single Nucleotide / genetics*
  • Promoter Regions, Genetic / physiology*
  • Sweden / ethnology
  • TATA Box / genetics*
  • Transfection
  • Turkey / ethnology

Substances

  • Nucleic Acid Heteroduplexes
  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • Oxidoreductases
  • Aryl Hydrocarbon Hydroxylases
  • CYP2A6 protein, human
  • Cytochrome P-450 CYP2A6
  • nicotine oxidase