Cytochrome b5 and epoxide hydrolase contribute to benzo[a]pyrene-DNA adduct formation catalyzed by cytochrome P450 1A1 under low NADPH:P450 oxidoreductase conditions

Marie Stiborová (Lead / Corresponding author), Michaela Moserová, Vera Černá, Radek Indra, Martin Dračínský, Miroslav Šulc, Colin J. Henderson, C. Roland Wolf, Heinz H. Schmeiser, David H. Phillips, Eva Frei, Volker M. Arlt

    Research output: Contribution to journalArticle

    37 Citations (Scopus)

    Abstract

    In previous studies we had administered benzo[a]pyrene (BaP) to genetically engineered mice (HRN) which do not express NADPH:cytochrome P450 oxidoreductase (POR) in hepatocytes and observed higher DNA adduct levels in livers of these mice than in wild-type mice. To elucidate the reason for this unexpected finding we have used two different settings for in vitro incubations; hepatic microsomes from control and BaP-pretreated HRN mice and reconstituted systems with cytochrome P450 1A1 (CYP1A1), POR, cytochrome b, and epoxide hydrolase (mEH) in different ratios. In microsomes from BaP-pretreated mice, in which Cyp1a1 was induced, higher levels of BaP metabolites were formed, mainly of BaP-7,8-dihydrodiol. At a low POR:CYP1A1 ratio of 0.05:1 in the reconstituted system, the amounts of BaP diones and BaP-9-ol formed were essentially the same as at an equimolar ratio, but formation of BaP-3-ol was ~1.6-fold higher. Only after addition of mEH were BaP dihydrodiols found. Two BaP-DNA adducts were formed in the presence of mEH, but only one when CYP1A1 and POR were present alone. At a ratio of POR:CYP1A1 of 0.05:1, addition of cytochrome b increased CYP1A1-mediated BaP oxidation to most of its metabolites indicating that cytochrome b participates in the electron transfer from NADPH to CYP1A1 required for enzyme activity of this CYP. BaP-9-ol was formed even by CYP1A1 reconstituted with cytochrome b without POR. Our results suggest that in livers of HRN mice Cyp1a1, cytochrome b and mEH can effectively activate BaP to DNA binding species, even in the presence of very low amounts of POR.
    Original languageEnglish
    Pages (from-to)1-12
    Number of pages12
    JournalToxicology
    Volume318
    Issue number1
    DOIs
    Publication statusPublished - 6 Apr 2014

    Fingerprint Dive into the research topics of 'Cytochrome b<sub>5</sub> and epoxide hydrolase contribute to benzo[a]pyrene-DNA adduct formation catalyzed by cytochrome P450 1A1 under low NADPH:P450 oxidoreductase conditions'. Together they form a unique fingerprint.

  • Cite this

    Stiborová, M., Moserová, M., Černá, V., Indra, R., Dračínský, M., Šulc, M., Henderson, C. J., Wolf, C. R., Schmeiser, H. H., Phillips, D. H., Frei, E., & Arlt, V. M. (2014). Cytochrome b5 and epoxide hydrolase contribute to benzo[a]pyrene-DNA adduct formation catalyzed by cytochrome P450 1A1 under low NADPH:P450 oxidoreductase conditions. Toxicology, 318(1), 1-12. https://doi.org/10.1016/j.tox.2014.02.002