Transcriptional regulation of human CYP2C genes: functional comparison of CYP2C9 and CYP2C18 promoter regions

Biochemistry. 1995 Jun 27;34(25):8028-36. doi: 10.1021/bi00025a008.


The cytochrome P4502C subfamily comprises a group of constitutive microsomal hemoproteins which are expressed primarily in liver. In humans, this subfamily is responsible for metabolism of a variety of therapeutic drugs such as warfarin, mephenytoin, omeprazole, and antiinflammatory drugs. In the present study, we analyzed the promoter activity of the 5'-flanking region of two human CYP2C genes, CYP2C9 and CYP2C18. The ability of the 2.2-kb 5'-flanking region of the CYP2C9 gene to direct expression of a luciferase reporter gene in HepG2 cells was 25 times greater than that of the 1.3-kb 5'-flanking region of CYP2C18. Deletional analysis of CYP2C9 indicated that the minimal promoter was located between the translation start site and nucleotide -155, and an HPF-1 domain consensus sequence was identified in this region. Gel shift analysis demonstrated that nuclear proteins from HepG2 cells had a high binding affinity for a 20-bp oligonucleotide containing the HPF-1 site of CYP2C9. Antiserum to rat HNF-4 supershifted this DNA--protein complex, and an oligonucleotide derived from an HNF-4 motif present in the human apolipoprotein CIII promoter competed for the supershifted complex. Cotransfection with an HNF-4 expression plasmid increased transcriptional activity of the CYP2C9 minimal promoter (approximately 2-fold) in HepG2 cells and elevated activity more substantially in nonhepatic NIH3T3 cells (26-fold) and Cos 1 cells (9-fold).(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Aryl Hydrocarbon Hydroxylases*
  • Base Sequence
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • Binding Sites
  • Carcinoma, Hepatocellular
  • Cytochrome P-450 CYP2C9
  • Cytochrome P-450 Enzyme System / genetics*
  • DNA / chemistry
  • DNA / metabolism
  • DNA-Binding Proteins*
  • Gene Deletion
  • Gene Expression Regulation*
  • Haplorhini
  • Hepatocyte Nuclear Factor 4
  • Humans
  • Liver Neoplasms
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Phosphoproteins*
  • Promoter Regions, Genetic*
  • Steroid 16-alpha-Hydroxylase*
  • Steroid Hydroxylases / genetics*
  • Transcription Factors / metabolism
  • Transcription Factors / pharmacology
  • Transcription, Genetic*
  • Transcriptional Activation
  • Transfection
  • Tumor Cells, Cultured


  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • DNA-Binding Proteins
  • Hepatocyte Nuclear Factor 4
  • MLX protein, human
  • Phosphoproteins
  • Tcfl4 protein, mouse
  • Transcription Factors
  • DNA
  • Cytochrome P-450 Enzyme System
  • Steroid Hydroxylases
  • CYP2C9 protein, human
  • Cytochrome P-450 CYP2C9
  • Aryl Hydrocarbon Hydroxylases
  • CYP2C18 protein, human
  • Steroid 16-alpha-Hydroxylase