Journal Article

Overexpression of Ogg1 in mammalian cells: effects on induced and spontaneous oxidative DNA damage and mutagenesis

Stephan Hollenbach, Andreia Dhénaut, Inge Eckert, J. Pablo Radicella and Bernd Epe

in Carcinogenesis

Volume 20, issue 9, pages 1863-1868
Published in print September 1999 | ISSN: 0143-3334
Published online September 1999 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/20.9.1863
Overexpression of Ogg1 in mammalian cells: effects on induced and spontaneous oxidative DNA damage and mutagenesis

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Chinese hamster ovary cell lines (AA8 and AS52) were stably transfected to overexpress hOgg1 protein, the human DNA repair glycosylase for 7,8-dihydro-8-oxoguanine (8-oxoG). In the transfectants, the repair rate of 8-oxoG residues induced by either potassium bromate or the photosensitizer [R]-1-[(10-chloro-4-oxo-3-phenyl-4H-benzo[a]quinolizin-1-yl)-carbonyl]-2-pyrrolidinemethanolplus light was up to 3-fold more rapid than in the parental cells. However, the improved repair had little effect on the mutagenicity of potassium bromate in the guanine phosphoribosyl transferase (gpt) locus of the OGG1-transfected AS52 cells. The steady-state (background) levels of DNA base modifications sensitive to Fpg protein, which include 8-oxoG, in cells not exposed to a damaging agent were not reduced by the overexpression of Ogg1 protein. Moreover, the spontaneous mutation rates in the gpt locus were similar in OGG1-transformed and vector-only-transformed cells. The results demonstrate the potential of Ogg1 protein to remove its substrate modifications from most of the chromosomal DNA. They indicate, on the other hand, that the Ogg1 protein alone may not be rate limiting for the repair of the residual substrate modifications observed in cells under normal growth conditions.

Keywords: gpt, guanine phosphoribosyl transferase; 8-oxoG, 7,8-dihydro-8-guanine; Ro19-8022, [R]-1-[(10-chloro-4-oxo-3-phenyl-4H-benzo[a]quinolizin-1-yl)-carbonyl]-2-pyrrolidinemethanol.

Journal Article.  4707 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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