Abstract：
We investigated the interplay among oxidative DNA damage and repair, expression of genes encoding major base excision repair (BER) enzymes and bypass DNA polymerases, and mutagenesis in mammalian cells. Primary mouse embryonic fibroblasts were challenged with oxidative stress induced by methylene blue plus visible light, and formation and repair of DNA damage, changes in gene expression, and mutagenesis were determined at increasing intervals post-treatment (0 - 192 hours). Significant formation of oxidative DNA damage together with upregulation of Ogg1, Polβ, and Polκ, and no changes in Mutyh and Nudt1 expression were found in treated cells. There was a distinct interconnection between Ogg1 and Polβ expression and DNA damage formation and repair whereby changes in expression of these two genes were proportionate to the levels of oxidative DNA damage, once a 3-plus hour lag time passed (P < 0.05). Equally notable was the matching pattern of Polκ expression and kinetics of oxidative DNA damage and repair (P < 0.05). The DNA damage and gene expression data were remarkably consistent with mutagenicity data in the treated cells; the induced mutation spectrum is indicative of erroneous bypass of oxidized DNA bases and incorporation of oxidized deoxynucleoside triphosphates during replication of the genomic DNA. Our findings support follow-up functional studies to elucidate how oxidation of DNA bases and the nucleotide pool, overexpression of Polκ, delayed upregulation of Ogg1 and Polβ, and inadequate expression of Nudt1 and Mutyh collectively affect mutagenesis consequent to oxidative stress.
摘要：
我们调查了氧化DNA损伤和修复之间的相互作用，编码主要碱基切除修复（BER）酶和旁路DNA聚合酶的基因的表达，和哺乳动物细胞中的诱变。原代小鼠胚胎成纤维细胞被亚甲蓝和可见光诱导的氧化应激攻击，以及DNA损伤的形成和修复，基因表达的变化，并且在处理后(0-192小时)以增加的间隔测定诱变。氧化DNA损伤的显着形成以及Ogg1，Polβ的上调，和波尔κ，在处理的细胞中没有发现Mutyh和Nudt1表达的变化。Ogg1和Polβ表达与DNA损伤形成和修复之间存在明显的相互联系，这两个基因的表达变化与氧化性DNA损伤水平成正比。超过3小时的滞后时间（P<0.05）。Polκ表达与氧化性DNA损伤和修复动力学的匹配模式同样显著(P<0.05)。DNA损伤和基因表达数据与处理细胞中的诱变性数据非常一致;诱导的突变谱指示在基因组DNA复制期间氧化的DNA碱基的错误旁路和氧化的脱氧核苷三磷酸的掺入。我们的发现支持后续功能研究，以阐明DNA碱基和核苷酸池的氧化，Polk过表达,Ogg1和Polβ的延迟上调，Nudt1和Mutyh的表达不足共同影响氧化应激后的诱变。
