Tyrosyl-DNA phosphodiesterase and oxidative DNA damage

酪氨酰 DNA 磷酸二酯酶和氧化 DNA 损伤

• 批准号: 6761269
• 负责人: Lawrence F Povirk
• 金额: $ 26.33万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6761269
• 关键词: DNA damage; DNA repair; aging; apoptosis; ataxia; cell line; clinical research; cytotoxicity; enzyme deficiency; gel electrophoresis; genetic susceptibility; genetically modified animals; human genetic material tag; laboratory mouse; lymphoblast; neoplastic process; neuropathology; oxidative stress; phosphodiesterases; prostate neoplasms; prostate preneoplastic state; protein structure function; soma; telomere; terminal nick end labeling

DESCRIPTION (provided by applicant): When transient DNA strand breaks formed by DNA topoisomerase I fail to religate, the topoisomerase becomes irreversibly attached to the 3' DNA end via a tyrosyl linkage. This linkage must then be cleaved by tyrosyI-DNA phosphodiesterase (Tdp1) in order to allow repair of the break. Human deficiency in Tdp1 has been implicated in hereditary spinocerebellar ataxia with axonal neuropathy (SCAN1), the clinical features of which are similar to those of other ataxias associated with oxidative stress. These similarities, combined with the finding that Tdp1 also removes glycolate moieties from 3' ends of free radical-mediated DNA strand breaks, suggest that Tdp1 may be involved in repair of oxidative DNA damage, and that failure to repair such damage may lead to neuronal dysfunction in SCAN1. In order to test these hypotheses, cytotoxicity as well as repair of 3'-phosphoglycolate-terminated DNA double-strand breaks will be examined in Tdp1-deficient lymphoblastoid cells, derived from SCAN1 patients. Oxidative DNA damage to telomeric DNA, as well as telomere structure and function, will be compared in normal and Tdp1-deficient cells. Both conventional and conditional Tdp1 knockout mice will be generated and extensively characterized. This will include an assessment for the development of ataxia or other behavioral dysfunctions as well as for neuronal apoptosis both in the presence and absence of oxidative stress. Tumor incidence will be determined at a number of sites in both untreated animals and those exposed to oxidative stress, and the effects of Tdp1 deficiency on tumor progression will be evaluated in mice that are predisposed to the development of premalignant prostate neoplasia. In addition, mice will be monitored for signs of accelerated aging. These studies are intended to clarify the mechanism by which Tdp1 deficiency leads to SCAN1, and may also help elucidate the role of oxidative stress in various other neurological disorders, cancer and aging.

描述（由申请人提供）：当DNA拓扑异构酶I无法宗教形成时，瞬时DNA链断裂时，拓扑异构酶通过酪蛋白链接不可逆地连接到3'DNA端。然后，必须通过酪体-DNA磷酸二酯酶（TDP1）裂解此连接，以允许修复断裂。 TDP1中的人缺乏与轴突神经病（SCAN1）的遗传性脊髓性共济失调有关，其临床特征与与氧化应激相关的其他共济失调的临床特征相似。这些相似之处加上TDP1还从自由基介导的DNA链断裂的3端去除乙酸部分的发现，这表明TDP1可能与修复氧化DNA损伤有关，并且不修复这种损伤可能会导致SCAN1中的神经元功能障碍。为了检验这些假设，将在TDP1缺陷型淋巴母细胞中检查细胞毒性以及3'-磷酸乙二醇终止的DNA双链断裂的修复，这些双链断裂将在SCAN1患者中得出。在正常和TDP1缺陷型细胞中，将比较对端粒DNA以及端粒结构和功能的氧化DNA损伤。常规和条件TDP1基因敲除小鼠将被生成并广泛表征。这将包括评估共济失调或其他行为功能障碍以及在存在和不存在氧化应激的情况下神经元凋亡的评估。肿瘤的发生率将在未处理的动物和暴露于氧化应激的许多部位上确定，TDP1缺乏对肿瘤进展的影响将在易于发育的小鼠中评估。此外，将监测小鼠的加速衰老迹象。这些研究旨在阐明TDP1缺乏导致SCAN1的机制，并且还可能有助于阐明氧化应激在其他各种神经系统疾病，癌症和衰老中的作用。