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Mitochondrial endogenous oxidative damage has been overestimated
Author(s) -
Michael Anson R.,
Hudson Edgar,
Bohr Vilhelm A.
Publication year - 2000
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.14.2.355
Subject(s) - mitochondrial dna , mitochondrion , endogeny , nuclear dna , microbiology and biotechnology , oxidative phosphorylation , biology , dna damage , dna , oxidative damage , western blot , biochemistry , oxidative stress , gene
The oxidatively induced DNA lesion 8‐oxo‐dG in mitochondrial DNA (mtDNA) is commonly used as a marker for oxidative damage to mitochondria, which in turn is thought to be a fundamental cause of aging. For years, mitochondrial levels of 8‐oxo‐dG were believed to be ~10‐fold higher in mtDNA than in nuclear DNA even in normal, young animals. However, studies in our own and other laboratories have shown that this lesion is efficiently repaired. Also, mutational consequences specific to 8‐oxo‐dG (G to T transversions) are rarely reported. In the present study, we showed that the levels of damage measured using high‐pressure liquid chromatography/electrochemical detection and an enzymatic/Southern blot assay were comparable. The latter assay does not require isolation of mitochondria, and so this assay was then used to determine the level of in vivo damage present in rat liver mtDNA both with and without organelle isolation. Levels of 8‐oxo‐dG are approximately threefold higher when measured in mtDNA purified from isolated mitochondria than when measured without prior mitochondrial isolation. Furthermore, most genomes were free of endogenous enzyme‐sensitive sites (i.e., they did not contain 8‐oxo‐dG), and only after mitochondrial isolation were levels higher in mtDNA than in a nuclear sequence. Anson, R. M., Hudson, E., Bohr, V. A. Mitochondrial endogenous oxidative damage has been overestimated. FASEB J. 14, 355–360 (2000)