Cellular repair and toxicity determinants of the major oxidative DNA lesion thymine glycol

主要氧化DNA损伤胸腺嘧啶乙二醇的细胞修复和毒性决定因素

• 批准号: 406568501
• 负责人: Professor Dr. Andriy Khobta
• 金额: --
• 依托单位: Institut für Ernährungswissenschaften
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/406568501?language=en
• 关键词: Cellular; repair; toxicity; determinants; major

Thymine glycol (TG) is a major oxidation product of thymine and 5-methylcytosine in DNA generated by ionizing radiation (IR) and, to a lesser extent, by free radicals of endogenous origin. The non-planar structure of TG and its inability to form Watson-Crick hydrogen bonding result in a significant degree of DNA helix distortion and a substantial capacity to hinder replication of the damaged DNA. The peculiar properties of TG account for its pronounced cytotoxicity as compared to other oxidative base modifications. Biochemical studies demonstrated that at least two DNA glycosylases can initiate base excision repair of TG and the involvement of several additional DNA repair mechanisms is considered plausible. However, the true significance in cells and possible functional overlaps between such repair pathways remain to be explored.The present project is a collaborative effort aimed at elucidating the biological relevance of different repair pathways proposed for TG as well as identifying factors that determine the repair pathway choice in human cells. We will generate human cell models in which the major components of the base excision repair pathway of TG (DNA glycosylases NTHL1 and NEIL1) and of putative alternative repair pathways will be inactivated. The French team will apply laser microirradiation of pre-selected areas of nuclei of living cells in the presence of photosensitizers to detect recruitment of components of the specific DNA repair pathways and to measure repair in situ. The German team will introduce synthetic TG into functional reporter genes and analyse the repair as well as the outcomes of TG for transcription and replication of the damaged template DNA in transfected cells. The complementary approaches of the teams shall reveal the functional significance of the individual pathways for recognition and processing of TG in the context of living cells.

胸腺嘧啶二醇（TG）是由电离辐射（IR）和内源性自由基（在较小程度上）产生的DNA中胸腺嘧啶和5-甲基胞嘧啶的主要氧化产物。TG的非平面结构及其不能形成Watson-Crick氢键导致显著程度的DNA螺旋扭曲和阻碍受损DNA复制的显著能力。TG的特殊性质解释了其与其他氧化碱修饰相比的显著细胞毒性。生化研究表明，至少有两种DNA糖基化酶可以启动TG的碱基切除修复，并认为可能涉及几种额外的DNA修复机制。然而，在细胞中的真正意义和可能的功能重叠之间的这种修复pathways仍然有待探讨，目前的项目是一个合作的努力，旨在阐明不同的修复途径提出的TG的生物学相关性，以及确定因素，确定在人类细胞中的修复途径的选择。我们将产生人类细胞模型，其中TG（DNA糖基化酶NTHL 1和NEIL 1）的碱基切除修复途径和推定的替代修复途径的主要成分将被灭活。法国研究小组将在光敏剂存在的情况下对活细胞核的预选区域进行激光微照射，以检测特定DNA修复途径组分的募集并原位测量修复。德国研究小组将把合成的TG引入功能性报告基因中，并分析TG在转染细胞中受损模板DNA转录和复制的修复和结果。团队的互补方法将揭示在活细胞背景下识别和处理TG的各个途径的功能意义。