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Mutation in the glucose-6-phosphate dehydrogenase gene leads to inactivation of Ku DNA end binding during oxidative stress.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2002 Mar 22; Vol. 277 (12), pp. 9929-35. Date of Electronic Publication: 2002 Jan 11. - Publication Year :
- 2002
-
Abstract
- Glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the oxidative pentose phosphate cycle, regulates the NADPH/NADP(+) ratio in eukaryotic cells. G6PD deficiency is one of the most common mutations in humans and is known to cause health problems for hundreds of millions worldwide. Although it is known that decreased G6PD functionality can result in increased susceptibility to oxidative stress, the molecular targets of this stress are not known. Using a Chinese hamster ovary G6PD-null mutant, we previously demonstrated that exposure to a thiol-specific oxidant, hydroxyethyldisulfide, caused enhanced radiation sensitivity and an inability to repair DNA double strand breaks. We now demonstrate a molecular mechanism for these observations: the direct inhibition of DNA end binding activity of the Ku heterodimer, a DNA repair protein, by oxidation of its cysteine residues. Inhibition of Ku DNA end binding was found to be reversible by treatment of the nuclear extract with dithiothreitol, suggesting that the homeostatic regulation of reduced cysteine residues in Ku is a critical function of G6PD and the oxidative pentose cycle. In summary, we have discovered a new layer of DNA damage repair, that of the functional maintenance of repair proteins themselves. In view of the rapidly escalating number of roles ascribed to Ku, these results may have widespread ramifications.
- Subjects :
- Animals
Blotting, Western
CHO Cells
Cell Nucleus metabolism
Chromatography, High Pressure Liquid
Cricetinae
Cysteine chemistry
DNA metabolism
DNA Damage
DNA Repair
Disulfides pharmacology
Dithiothreitol pharmacology
Ethanol pharmacology
Ku Autoantigen
Models, Chemical
NAD metabolism
NADP metabolism
Protein Binding
Reducing Agents pharmacology
Sulfhydryl Compounds chemistry
Time Factors
Transfection
Antigens, Nuclear
DNA Helicases
DNA-Binding Proteins metabolism
Ethanol analogs & derivatives
Glucosephosphate Dehydrogenase genetics
Mutation
Nuclear Proteins metabolism
Oxidative Stress
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 277
- Issue :
- 12
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 11788599
- Full Text :
- https://doi.org/10.1074/jbc.M111366200