Overexpression of Ogg1 in mammalian cells:: effects on induced and spontaneous oxidative DNA damage and mutagenesis
Overexpression of Ogg1 in mammalian cells:: effects on induced and spontaneous oxidative DNA damage and mutagenesis
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DOI：
10.1093/carcin/20.9.1863
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发表时间：
1999-09-01
期刊：
影响因子：
4.7
通讯作者：
Epe, B
中科院分区：
文献类型：
--
作者：
Hollenbach, S;Dhénaut, A;Epe, B
稳定转染中国仓鼠卵巢细胞系（AA 8和AS 52），使其过表达hOgg 1蛋白，hOgg 1蛋白是7，8-二氢-8-氧代鸟嘌呤（8-oxoG）的人DNA修复糖基化酶。在转染子中，由溴酸钾或光敏剂[R]-1-[（10-氯-4-氧代-3-苯基-4H-苯并[a]喹嗪-1-基）-羰基] -2-吡咯烷甲醇加光诱导的8-oxoG残基的修复速率比亲本细胞快3倍。然而，改进的修复对溴酸钾在OGG 1转染的AS 52细胞的鸟嘌呤磷酸核糖转移酶（gpt）位点的致突变性几乎没有影响。稳态（背景）水平的DNA碱基修饰敏感的Fpg蛋白，其中包括8-oxoG，在细胞中不暴露于破坏剂没有减少过表达的Ogg 1蛋白。此外，在gpt基因座的自发突变率在OGG 1转化的和仅载体转化的细胞中是相似的。结果证明Ogg 1蛋白从大多数染色体DNA中去除其底物修饰的潜力。另一方面，它们表明，单独的Ogg 1蛋白对于在正常生长条件下在细胞中观察到的残留底物修饰的修复可能不是速率限制。
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-pyrrolidinemethanol plus 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.