Mitochondrial repair of 8-oxoguanine is deficient in Cockayne syndrome group B.
Reactive oxygen species, which are prevalent in mitochondria, cause oxidative DNA damage including the mutagenic DNA lesion 7,8-dihydroxyguanine (8-oxoG). Oxidative damage to mitochondrial DNA has been implicated as a causative factor in a wide variety of degenerative diseases, and in cancer and aging. 8-oxoG is repaired efficiently in mammalian mitochondrial DNA by enzymes in the base excision repair pathway, including the 8-oxoguanine glycosylase (OGG1), which incizes the lesion in the first step of repair. Cockayne syndrome (CS) is a segmental premature aging syndrome in humans that has two complementation groups, CSA and CSB. Previous studies showed that CSB-deficient cells have reduced capacity to repair 8-oxoG. This study examines the role of the CSB gene in regulating repair of 8-oxoG in mitochondrial DNA in human and mouse cells. 8-oxoG repair was measured in liver cells from CSB deficient mice and in human CS-B cells carrying expression vectors for wild type or mutant forms of the human CSB gene. For the first time we report that CSB stimulates repair of 8-oxoG in mammalian mitochondrial DNA. Furthermore, evidence is presented to support the hypothesis that wild type CSB regulates expression of OGG1.[1]References
- Mitochondrial repair of 8-oxoguanine is deficient in Cockayne syndrome group B. Stevnsner, T., Nyaga, S., de Souza-Pinto, N.C., van der Horst, G.T., Gorgels, T.G., Hogue, B.A., Thorslund, T., Bohr, V.A. Oncogene (2002) [Pubmed]
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