REPAIR OF OXIDATIVELY DAMAGED GUANINES IN HUMAN

错配修复是一种错误避免途径，致力于增强 DNA复制的保真度和保持遗传稳定性。 人类错配修复基因突变使个体更容易患上 癌症。产生反应性的氧化应激和代谢过程 氧物种被认为是导致 诱变、致癌、衰老等多种疾病。人类 MutY同源(HMYH)错配修复途径修复A/G、A/C和 A/8-oxoG不匹配将是我们的主要关注点。8-oxoG损伤是一种 主要稳定的DNA氧化损伤产物和拥有最多 有害的影响，因为它可能与腺嘌呤错配。因此，A/8-oxoG 错配是hMYH的重要生物底物。 HMYH和E.ColiMutY蛋白一样，是一种腺嘌呤DNA糖基酶。 因为在大肠杆菌中表达的重组hMYH蛋白和天然的hMYH 具有不同的不匹配特性，结构和功能 这些蛋白质的差异将进一步分析。糖基酶和 含A/G，A/C，DNA的脱嘌呤/脱嘧啶(AP)裂解酶活性 A/8-oxoG和其他碱基类似物将被检测。我们的结果表明 HMYH、MutS同源物(hMSH2和hMSH6)和MutL同源物(hMLH1和 HPMS2)与DNA复制复合体相关，因此 HMYH与复制和错配修复的相互作用 蛋白质将通过免疫共沉淀和亲和力进行研究。 层析法。HMYH修复与DNA复制的耦合可能 直接MYH修复女儿的错误结合的腺嘌呤 思特斯。增殖细胞核抗原(增殖细胞核抗原，An)的作用 DNA聚合酶辅助因子Delta和epsilon)对hMYH活性的影响 将会被确定。人类乳腺和肺癌细胞将被分析 用于hMYH的表达，并筛选hMYH基因的突变。这个 MYH缺陷细胞对氧化剂和 将对辐射进行分析。通过对DNA作用机制的研究 错配修复，我们对癌症、衰老和基因的理解 疾病可能会进一步发展。

Mismatch repair is an error avoidance pathway devoted to enhancing the fidelity of DNA replication and maintaining genetic stability. Mutations in human mismatch repair genes predispose individuals to cancer. Oxidative stress and metabolic processes which produce reactive oxygen species have been implicated as important causative agents of mutagenesis, carcinogenesis, aging, and a number of diseases. The human MutY homolog (hMYH) mismatch repair pathway for repairing A/G, A/C, and A/8-oxoG mismatches will be our major focus. The 8-oxoG lesion is a major stable product of DNA oxidative damage and has the most deleterious effects because it can mispair with adenine. Thus, A/8-oxoG mismatches are particularly important biological substrates for hMYH. hMYH, like the E. coli MutY protein, is an adenine DNA glycosylase. Because recombinant hMYH protein expressed in E. coli and native hMYH have different mismatch specificities, the structural and functional differences of these proteins will be further analyzed. Glycosylase and apurinic/apyrimidinic (AP) lyase activities on DNA containing A/G, A/C, A/8-oxoG, and other base analogs will be assayed. Our results indicate the hMYH, MutS homologs (hMSH2 and hMSH6), and MutL homologs (hMLH1 and hPMS2) are associated with the DNA replication complex, thus the interactions between hMYH and replicative as well as mismatch repair proteins will be investigated by co-immunoprecipretation and affinity chromatography. The coupling of hMYH repair with DNA replication may direct MYH repair to the misincorporated adenines on the daughter strands. The effect of proliferating cell nuclear antigen (PCNA, an accessory factor for DNA polymerases delta and epsilon) on hMYH activity will be determined. Human breast and lung cancer cells will be analyzed for hMYH expression and screened for mutations in the hMYH gene. The sensitivities of the MYH defective cells to oxidative agents and radiation will be analyzed. Through the study of the mechanism of DNA mismatch repair, our understanding of cancer, aging, and genetic diseases can be advanced.