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: 7092128
• 负责人: Lawrence F Povirk
• 金额: $ 25.71万
• 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/7092128
• 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无法形成瞬时DNA链断裂时，拓扑异构酶通过酪氨酸键不可逆地连接到3' DNA末端。为了修复断裂，这个连接必须被酪氨酸- dna磷酸二酯酶（Tdp1）切割。人类缺乏Tdp1与遗传性脊髓小脑性共济失调伴轴突神经病变（SCAN1）有关，其临床特征与其他与氧化应激相关的共济失调相似。这些相似之处，再加上Tdp1也从自由基介导的DNA链断裂的3'端去除乙醇酸基团的发现，表明Tdp1可能参与氧化DNA损伤的修复，而修复这种损伤的失败可能导致SCAN1中的神经元功能障碍。为了验证这些假设，我们将检测来自SCAN1患者的tdp1缺陷淋巴母细胞样细胞的细胞毒性以及3'-磷酸乙醇酸末端DNA双链断裂的修复。将比较正常细胞和tdp1缺陷细胞对端粒DNA的氧化损伤以及端粒结构和功能。常规Tdp1基因敲除小鼠和条件Tdp1基因敲除小鼠将被生成并广泛表征。这将包括在氧化应激存在和不存在的情况下对共济失调或其他行为功能障碍的发展以及神经元凋亡的评估。肿瘤发生率将在未治疗的动物和暴露于氧化应激的动物的许多部位确定，Tdp1缺乏对肿瘤进展的影响将在易患前列腺癌前病变的小鼠中进行评估。此外，还将监测小鼠加速衰老的迹象。这些研究旨在阐明Tdp1缺乏导致SCAN1的机制，也可能有助于阐明氧化应激在各种其他神经系统疾病、癌症和衰老中的作用。