Impairment of human CYP1A2-mediated xenobiotic metabolism by Antley-Bixler syndrome variants of cytochrome P450 oxidoreductase

Arch Biochem Biophys. 2008 Jul 15;475(2):93-9. doi: 10.1016/j.abb.2008.04.014. Epub 2008 Apr 20.

Abstract

Y459H and V492E mutations of cytochrome P450 reductase (CYPOR) cause Antley-Bixler syndrome due to diminished binding of the FAD cofactor. To address whether these mutations impaired the interaction with drug-metabolizing CYPs, a bacterial model of human liver expression of CYP1A2 and CYPOR was implemented. Four models were generated: POR(null), POR(wt), POR(YH), and POR(VE), for which equivalent CYP1A2 and CYPOR levels were confirmed, except for POR(null), not containing any CYPOR. The mutant CYPORs were unable to catalyze cytochrome c and MTT reduction, and were unable to support EROD and MROD activities. Activity was restored by the addition of FAD, with V492E having a higher apparent FAD affinity than Y459H. The CYP1A2-activated procarcinogens, 2-aminoanthracene, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, and 2-amino-3-methylimidazo(4,5-f)quinoline, were significantly less mutagenic in POR(YH) and POR(VE) models than in POR(wt), indicating that CYP1A2, and likely other drug-metabolizing CYPs, are impaired by ABS-related POR mutations as observed in the steroidogenic CYPs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Craniosynostoses / genetics*
  • Cytochrome P-450 CYP1A2 / genetics*
  • Flavin-Adenine Dinucleotide / chemistry*
  • Formazans / metabolism
  • Humans
  • Mutation*
  • NADPH-Ferrihemoprotein Reductase / genetics*
  • NADPH-Ferrihemoprotein Reductase / physiology
  • Oxidation-Reduction
  • Syndrome
  • Tetrazolium Salts / metabolism
  • Xenobiotics / metabolism

Substances

  • Formazans
  • Tetrazolium Salts
  • Xenobiotics
  • Flavin-Adenine Dinucleotide
  • MTT formazan
  • Cytochrome P-450 CYP1A2
  • NADPH-Ferrihemoprotein Reductase