DNA-protein cross-link formation mediated by oxanine - A novel genotoxic mechanism of nitric oxide-induced DNA damage
DNA-protein cross-link formation mediated by oxanine - A novel genotoxic mechanism of nitric oxide-induced DNA damage
复制标题
DOI：
10.1074/jbc.m212847200
复制
发表时间：
2003-07-04
影响因子：
4.8
通讯作者：
Ide, H
中科院分区：
文献类型：
--
作者：
Nakano, T;Terato, H;Ide, H
慢性炎症是许多人类癌症的危险因素，并且已经提出在发炎组织中产生的一氧化氮（NO）通过碱基部分的亚硝化或氧化引起DNA损伤。因此，NO诱导的DNA损伤可能与慢性炎症相关的致癌作用有关。在这份报告中，我们报告了一种新的遗传毒性机制，涉及DNA-蛋白质交联（DPC）诱导的氧杂嘌呤（Oxa），一个主要的NO诱导的鸟嘌呤病变。当在位点特异性位置含有Oxa的双链DNA与DNA结合蛋白如组蛋白、高迁移率族（HMG）蛋白和DNA糖基化酶孵育时，在Oxa和蛋白之间形成DPC。与DNA糖基化酶的DPC形成的速率是约两个数量级高于组蛋白和HMG蛋白。个别氨基酸对Oxa的反应性的分析表明，DPC形成发生在Oxa和蛋白质中的赖氨酸或精氨酸的侧链之间。HeLa细胞提取物与含DNA的Oxa孵育时也产生了两种主要的DPC。这些结果揭示了Oxa作为DPC形成的因果损害和作为DNA修复酶的自杀底物的双重方面，这两者都可能对DNA的遗传和结构完整性构成威胁，因此可能导致致癌作用。
Chronic inflammation is a risk factor for many human cancers, and nitric oxide ( NO) produced in inflamed tissues has been proposed to cause DNA damage via nitrosation or oxidation of base moieties. Thus, NO-induced DNA damage could be relevant to carcinogenesis associated with chronic inflammation. In this report, we report a novel genotoxic mechanism of NO that involves DNA-protein cross-links (DPCs) induced by oxanine (Oxa), a major NO-induced guanine lesion. When a duplex DNA containing Oxa at the site-specific position was incubated with DNA-binding proteins such as histone, high mobility group (HMG) protein, and DNA glycosylases, DPCs were formed between Oxa and protein. The rate of DPC formation with DNA glycosylases was approximately two orders of magnitude higher than that with histone and HMG protein. Analysis of the reactivity of individual amino acids to Oxa suggested that DPC formation occurred between Oxa and side chains of lysine or arginine in the protein. A HeLa cell extract also gave rise to two major DPCs when incubated with DNA-containing Oxa. These results reveal a dual aspect of Oxa as causal damage of DPC formation and as a suicide substrate of DNA repair enzymes, both of which could pose a threat to the genetic and structural integrity of DNA, hence potentially leading to carcinogenesis.