5′-nicked apurinic/apyrimidinic sites are resistant to β-elimination by β-polymerase and are persistent in human cultured cells after oxidative stress
5′-nicked apurinic/apyrimidinic sites are resistant to β-elimination by β-polymerase and are persistent in human cultured cells after oxidative stress
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DOI：
10.1074/jbc.275.8.5323
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发表时间：
2000-02-25
影响因子：
4.8
通讯作者：
Swenberg, JA
中科院分区：
文献类型：
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作者：
Nakamura, J;La, DK;Swenberg, JA
基因组DNA持续暴露于氧化应激。尽管活性氧（ROS）优先与DNA中的碱基反应，但自由基也从脱氧核糖中提取氢原子，导致形成脱嘌呤/脱嘧啶（AP）位点和链断裂。我们最近报道了大鼠组织和人肝DNA中AP位点的高稳态水平（中村，J.，和Swenberg，J. A.（1999）Cancer Res.59，2522-2526）。这些AP位点主要在病变的5'处裂解。我们假设这些内源性AP位点来源于氧化应激。在这项调查中，AP网站诱导的ROS进行了定量和表征。H_2O_2和FeSO_4的组合诱导小牛胸腺DNA中大量的AP位点，这些位点主要被切割到AP位点的5'端（占总DNA AP位点的75%）。在暴露于H2 O2的人培养细胞中也检测到5 '-AP位点数量的增加，并且这些5'-AP位点在暴露后期间是持续的。通过DNA β-聚合酶的β-消除有效地切除了来自暴露于H2 O2的细胞的DNA中的5 ′-常规AP位点，但不切除5 ′-AP位点。这些结果表明，由ROS诱导的5 '-氧化AP位点不能被哺乳动物短补丁碱基切除修复途径有效修复。
Genomic DNA is continuously exposed to oxidative stress. Whereas reactive oxygen species (ROS) preferentially react with bases in DNA, free radicals also abstract hydrogen atoms from deoxyribose, resulting in the formation of apurinic/apyrimidinic (AP) sites and strand breaks. We recently reported high steady-state levels of AP sites in rat tissues and human liver DNA (Nakamura, J., and Swenberg, J. A. (1999) Cancer Res. 59, 2522-2526), These AP sites were predominantly cleaved 5' to the lesion. We hypothesized that these endogenous AP sites were derived from oxidative stress. In this investigation, AP sites induced by ROS were quantitated and characterized. A combination of H2O2 and FeSO4 induced significant numbers of AP sites in calf thymus DNA, which were predominantly cleaved 5' to the AP sites (75%) of total aldehydic AP sites). An increase in the number of 5'-AP sites was also detected in human cultured cells exposed to H2O2, and these 5'-AP sites were persistent during the post-exposure period. beta-Elimination by DNA beta-polymerase efficiently excised 5'-regular AP sites, but not 5'-AP sites, in DNA from cells exposed to H2O2. These results suggest that 5'-oxidized AP sites induced by ROS are not efficiently repaired by the mammalian short patch base excision repair pathway.