Repair of Oxidatively Damaged Guanines in Human

描述（由申请人提供）：DNA修复缺陷可导致基因组不稳定，这是癌症的标志。氧化性DNA损伤是生物体中突变负荷的主要来源，并且在致癌和衰老中起作用。8-氧代-7，8-二氢脱氧鸟嘌呤（8-oxoG）损伤是氧化损伤的主要稳定产物，并且具有最有害的作用，因为它可以在DNA复制期间与腺嘌呤错配。因此，通过hMYH修复ol A/8-oxoG和C/8-oxoG（MutY腺嘌呤糖基化酶同系物），hOGG 1（8-oxoG糖基化酶），hMSH2/hMSH 6依赖的错配修复通路提供了对氧化应激的防御水平。本项目的总体目标是了解hMYH通路在控制癌发生中的作用，以及它与其他修复通路在响应氧化应激（如氢处理）中的相互作用。过氧化物和电离辐射。将研究hMYH与复制蛋白hPCNA和hRPA、与修复酶hAPE 1和hMSH 6以及细胞周期检查点蛋白hHus 1/hRad 1/hRad 9的相互作用。(I)将研究在氧化应激下hMYH与hPCNA和hHusl的相互作用的改变。将绘制hMYH和hHusl上的相互作用结构域，并在体内测试它们的功能相互作用的意义。将测试hMYH-hPCNA tc hMYH-hRad 9/hRadl/hHusl的分子开关发生以诱导DNA损伤反应以及hMYH可将hRad 9/hRadl/hHusl募集到损伤位点的工作模型。(II)hMYH和hMSH 6之间的相互作用将在体外和体内阐明。裂殖酵母pombe将被用作模型系统来测试hMYH突变体的体外功能。(III)将检查hMYH与hAPE 1、hPCNA、hHus 1、hRPA和hMSH 6 ir修复和复制基因座的共定位。(IV)将确定DNA损伤后hMYH的磷酸化状态、负责hMYH磷酸化的激酶和hMYH的磷酸化位点。将检查DNA损伤后hMYH活性与蛋白质磷酸化或某些蛋白质-蛋白质相互作用的相关性。这项研究将促进我们对DNA修复在肿瘤易感性中的作用的理解。

DESCRIPTION (provided by applicant): Defects in DNA repair can lead to genome instability, a hallmark of cancer. Oxidative DNA damage is a major source of mutation load in living organisms and plays a role in carcinogenesis and aging. The 8-oxo-7,8-dihydrodeoxyguanine (8-oxoG) lesion is a major stable product of oxidative damage and has the most deleterious effects because it can mispair with adenine during DNA replication. Thus, repair ol A/8-oxoG and C/8-oxoG by hMYH (MutY adenine glycosylase homolog), hOGG1 (an 8-oxoG glycosylase), and hMSH2/hMSH6 dependent mismatch repair pathways provide levels of defense against oxidative stress The overall goals of this project is to understand the role of hMYH pathway in controlling carcinogenesis and its interplay with other repair pathways in response to oxidative stress such as treatments by hydrogen peroxide and ionizing radiation. The interactions of hMYH with replication proteins hPCNA and hRPA, with repai] enzymes hAPE1 and hMSH6, as well as cell cycle checkpoint proteins hHusl/hRadl/hRad9 will be investigated. (I) Alterations in the interactions of hMYH with hPCNA and hHusl under oxidative stress will be investigated. The interacting domains on hMYH and hHusl will be mapped and the significance of their functional interaction will be tested in vivo. Working models that a molecular switch of hMYH-hPCNA tc hMYH-hRad9/hRadl/hHusl occurs to induce DNA damage response and that hMYH may recruit_ hRad9/hRadl/hHusl to the lesion sites will be tested. (II) Interaction between hMYH and hMSH6 will be elucidated both in vitro and in vivo. Fission yeast S. pombe will be used as a model system to test the in viw function of hMYH mutants. (III) Co-localization of hMYH with hAPE 1, hPCNA, hHus 1, hRPA, and hMSH6 ir repair and replication loci will be examined. (IV) The phosphorylation state of hMYH after DNA damage, the kinase responsible for the hMYH phosphorylation, and the phosphorylation site(s) of hMYH will be determined. The correlation of hMYH activities with protein phosphorylation or certain protein-protein interaction(s) after DNA damage will be examined. This study will advance our understanding of the role of DNA repair in tumor susceptibility.