The <i>bis</i>-Electrophile Diepoxybutane Cross-Links DNA to Human Histones but Does Not Result in Enhanced Mutagenesis in Recombinant Systems

Loecken, Elisabeth M.; Dasari, Surendra; Hill, Salisha; Tabb, David L.; Guengerich, F. Peter

doi:10.1021/tx900037u

Cited by 27 publications

(47 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…44 Although GAPDH and histone H3 with DEB form DNA-protein cross-links, the adducts are not mutagenic. 43,44 We previously reported a dramatic enhancement of base pair mutagenicity of DEB following GST expression in Salmonella typhimurium TA1535, 30,31 and subsequently a synthetic DEB-GSH conjugate was formed to be considerably more mutagenic than DEB or several other butadiene-derived epoxides in S. typhimurium TA1535. 32 …”

Section: Discussionmentioning

confidence: 99%

Conjugation of Butadiene Diepoxide with Glutathione Yields DNA Adducts in Vitro and in Vivo

Cho

Guengerich

2012

Chem. Res. Toxicol.

Self Cite

View full text Add to dashboard Cite

1,2,3,4-diepoxybutane (DEB) is reported to be the most potent mutagenic metabolite of 1,3-butadiene, an important industrial chemical and environmental pollutant. DEB is capable of inducing the formation of monoalkylated DNA adducts, and DNA-DNA and DNA-protein crosslinks. We previously reported that DEB forms a conjugate with glutathione (GSH) and that the conjugate is considerably more mutagenic than several other butadiene-derived epoxides, including DEB, in the base pair tester strain Salmonella typhimurium TA1535 (Cho et. al., Chem. Res. Toxicol. 23, 1544–1546 (2010)). In the present study, we determined steady-state kinetic parameters of the conjugation of the three DEB stereoisomers— R,R-, S,S-, and meso- — (all formed by butadiene oxidation) with GSH by six GSH transferases. Only small differences (< 3-fold) were found in the catalytic efficiency of conjugate formation (kcat/Km) with all three DEB stereoisomers and the six GSH transferases. The three stereochemical DEB-GSH conjugates had similar mutagenicity. Six DNA adducts (N3-adenyl, N6-adenyl, N7-guanyl, N1-guanyl, N4-cytidyl, and N3-thymidyl) were identified in the reactions of DEB-GSH conjugate with nucleosides and calf thymus DNA using LC-MS and UV and NMR spectroscopy. N6-Adenyl and N7-guanyl GSH adducts were identified and quantitated in vivo in the livers of mice and rats treated with DEB i.p.. These results indicate that such DNA adducts are formed from the DEB-GSH conjugate, are mutagenic irregardless of sterochemistry, and therefore expected to contribute to the carcinogenicity of DEB.

show abstract

Section: Discussionmentioning

confidence: 99%

Conjugation of Butadiene Diepoxide with Glutathione Yields DNA Adducts in Vitro and in Vivo

Cho

Guengerich

2012

Chem. Res. Toxicol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…In fact, four histidine and two tyrosine residues present in human CYP2E1 react with EB to form adducts (Boysen et al, 2007), although their impact on activity was not investigated. As a bifunctional electrophile, DEB can modify individual residues and form intra- and inter-protein crosslinks (Cho and Guengerich, 2012), as well as protein-DNA crosslinks (Loecken et al, 2009). In this study, we did not specifically investigate the covalent modification of rodent CYP2E1 enzymes by BD metabolites; however, we did not observe any irreversible inhibition/inactivation of CYP2E1 by EB and DEB that would suggest covalent binding.…”

Section: Discussionmentioning

confidence: 99%

Differences in butadiene adduct formation between rats and mice not due to selective inhibition of CYP2E1 by butadiene metabolites

et al. 2013

View full text Add to dashboard Cite

CYP2E1 metabolizes 1,3-butadiene (BD) into genotoxic and possibly carcinogenic 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB), and 1,2-epoxy-3,4-butanediol (EB-diol). The dose response of DNA and protein adducts derived from BD metabolites increase linearly at low BD exposures and then saturate at higher exposures in rats, but not mice. It was hypothesized that differences in adduct formation between rodents reflect more efficient BD oxidation in mice than rats. Herein, we assessed whether BD-derived metabolites selectively inhibit rat but not mouse CYP2E1 activity using B6C3F1 mouse and Fisher 344 rat liver microsomes. Basal CYP2E1 activities toward 4-nitrophenol were similar between rodents. Through IC50 studies, EB was the strongest inhibitor (IC50 54 μM, mouse; 98 μM, rat), BD-diol considerably weaker (IC50 1200 μM, mouse; 1000 μM, rat), and DEB inhibition nonexistent (IC50 >25 mM). Kinetic studies showed that in both species EB and BD-diol inhibited 4-nitrophenol oxidation through two-site mechanisms in which inhibition constants reflected trends observed in IC50 studies. None of the reactive epoxide metabolites inactivated CYP2E1 irreversibly. Thus, there was no selective inhibition or inactivation of rat CYP2E1 by BD metabolites relative to mouse Cyp2e1, and it can be inferred that CYP2E1 activity toward BD between rodent species would similarly not be impacted by the presence of BD metabolites. Inhibition of CYP2E1 by BD metabolites is then not responsible for the reported species difference in BD metabolism, formation of BD-derived DNA and protein adducts, mutagenicity and tumorigenesis.

show abstract

“…16 Mass spectrometric analysis of tryptic peptides identified two cross-linking sites within the AGT protein: the catalytic alkyl acceptor site (Cys 145 ), and a neighboring active site residue (Cys 150 ). Loecken and colleagues have reported that DEB also forms DPCs involving GAPDH22 and histones H2b and H3 23. Like AGT, DPC formation by GAPDH involves a cysteine residue (Cys 246 ) 22.…”

Section: Introductionmentioning

confidence: 99%

“…Alkylation of Cys 246 in vitro results in the inhibition of GAPDH activity 22. Similarly, DEB is capable of cross-linking the Cys 111 residue of histone H3 to DNA 23 . In vitro DPC formation by all three proteins required treatment with relatively high concentrations of DEB (20 mM for GAPDH and histone proteins and 15 mM for AGT) 16,22,23.…”

Section: Introductionmentioning

confidence: 99%

DNA−Protein Cross-Linking by 1,2,3,4-Diepoxybutane

et al. 2010

View full text Add to dashboard Cite

Abstract1,2,3,4-Diepoxybutane (DEB) is a strongly genotoxic diepoxide hypothesized to be the ultimate carcinogenic metabolite of the common industrial chemical and environmental carcinogen 1,3-butadiene. DEB is a bis-electrophile capable of cross-linking cellular biomolecules to form DNA-DNA and DNA-protein cross-links (DPCs), which are thought to play a central role in its biological activity. Previous studies with recombinant proteins have shown that the biological outcomes of DEB-induced DPCs are strongly influenced by protein identities. The present work combines affinity capture methodology with mass spectrometry-based proteomics and immunological detection to identify the proteins which form DPCs in nuclear extracts from human cervical carcinoma (HeLa) cells. We identified 39 human proteins that form covalent DPCs in the presence of DEB. DNA-protein cross-linking efficiency following treatment with 25 mM DEB was 2-12%, depending on protein identity. HPLC-ESI + -MS/MS analysis of the total proteolytic digests of cross-linked proteins revealed the presence of 1-(S-cysteinyl)-4-(guan-7-yl)-2,3-butanediol conjugates, suggesting that DEB forms DPCs between cysteine thiols within proteins and the N-7 guanine positions within DNA.

show abstract

The bis-Electrophile Diepoxybutane Cross-Links DNA to Human Histones but Does Not Result in Enhanced Mutagenesis in Recombinant Systems

Cited by 27 publications

References 47 publications

Conjugation of Butadiene Diepoxide with Glutathione Yields DNA Adducts in Vitro and in Vivo

Conjugation of Butadiene Diepoxide with Glutathione Yields DNA Adducts in Vitro and in Vivo

Differences in butadiene adduct formation between rats and mice not due to selective inhibition of CYP2E1 by butadiene metabolites

DNA−Protein Cross-Linking by 1,2,3,4-Diepoxybutane

Contact Info

Product

Resources

About