期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 280, 期 27, 页码 25377-25382出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M503079200
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资金
- NCI NIH HHS [CA103146, CA26735] Funding Source: Medline
- NIEHS NIH HHS [ES002109] Funding Source: Medline
- NIGMS NIH HHS [GM59790] Funding Source: Medline
The endogenous DNA adduct, M(1)dG, has been shown to arise in vitro in reactions of dG with malondialdehyde (MDA), a product of both lipid peroxidation and 4'-oxidation of deoxyribose in DNA, and with base propenals also derived from deoxyribose 4'-oxidation. We now report the results of cellular studies consistent with base propenals, and not MDA, as the major source of M(1)dG under biological conditions. As a foundation for cellular studies, M(1)dG, base propenals, and MDA were quantified in purified DNA treated with oxidizing agents known to produce deoxyribose 4'-oxidation. The results revealed a consistent pattern; Fe2+-EDTA and gamma-radiation generated MDA but not base propenals or M(1)dG, whereas bleomycin and peroxynitrite (ONOO-) both produced M(1)dG as well as base propenals with no detectable MDA. These observations were then assessed in Escherichia coli with controlled membrane levels of polyunsaturated fatty acids (PUFA). ONOO- treatment (2 mM) of cells containing no PUFA (defined medium with 18:0/stearic acid) produced 6.5 M(1)dG/10(7) deoxynucleotides and no detectable lipid peroxidation products, including MDA, as compared with 3.8 M(1)dG/10(7) deoxynucleotides and 0.07 mu g/ ml lipid peroxidation products with control cells grown in a mixture of fatty acids (0.5% PUFA) mimicking Luria-Bertani medium. In cells grown with linoleic acid (18:2), the level of PUFA rose to 54% and the level of MDA rose to 0.14 mu g/ml, whereas M(1)dG fell to 1.4/10(7) deoxynucleotides. Parallel studies with gamma- radiation revealed levels of MDA similar to those produced by ONOO- but no detectable M(1)dG. These results are consistent with base propenals as the major source of M(1)dG in this model cell system.
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