Impairment of human CYP1A2-mediated xenobiotic metabolism by Antley-Bixler syndrome variants of cytochrome P450 oxidoreductase.
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.
Kranendonk
Michel
M
Department of Genetics, Faculty of Medical Sciences, Universidade Nova de Lisboa, Rua da Junqueira 96, 1349-008 Lisbon, Portugal. mkranendonk.gene@fcm.unl.pt <mkranendonk.gene@fcm.unl.pt>
Marohnic
Christopher C
CC
Panda
Satya P
SP
Duarte
Maria Paula
MP
Oliveira
José Santos
JS
Masters
Bettie Sue Siler
BS
Rueff
José
J
D002384:Catalysis; D003398:Craniosynostoses / Q000235:genetics*; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics*; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry*; D005562:Formazans / Q000378:metabolism; D006801:Humans; D009154:Mutation; D009251:NADPH-Ferrihemoprotein Reductase / Q000235:genetics* / Q000502:physiology; D010084:Oxidation-Reduction; D013577:Syndrome; D013778:Tetrazolium Salts / Q000378:metabolism; D015262:Xenobiotics / Q000378:metabolism
D005562:Formazans; D013778:Tetrazolium Salts; D015262:Xenobiotics; D005182:Flavin-Adenine Dinucleotide; C079782:MTT formazan; D019388:Cytochrome P-450 CYP1A2; D009251:NADPH-Ferrihemoprotein Reductase