Resolution of Complex Breaks by Nonhomologous End Joining

通过非同源末端连接解决复杂断裂

• 批准号: 8460124
• 负责人: DALE A RAMSDEN
• 金额: $ 23.61万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-04 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8460124
• 关键词: APTX gene; Active Sites; Acute; Address; Aging; Biological; Cell Aging; Cells; Chromosomal Breaks; Chromosomes; Chronic; Chronic stress; Complex; DNA; Dwarfism; Effectiveness; Excision; Experimental Models; Genome Stability; Immunologic Deficiency Syndromes; In Vitro; Ionizing radiation; Ligation; Lyase; Malignant Neoplasms; Mammals; Molecular; Mutation; Normal Cell; Nucleotides; Organism; Oxidative Stress; Pathway interactions; Pharmaceutical Preparations; Phenotype; Phosphorylation; Predisposition; Radiation; Regulation; Resistance; Resolution; Role; Site; Structure; Substrate Specificity; Work; XRCC4 gene; abstracting; base; cell killing; coping; insight; interest; killings; neoplastic cell; neurogenesis; premature; repaired; restriction enzyme; tool; tumor

Abstract Nonhomologous end joining (NHEJ) is a major pathway for resolving chromosome double strand breaks. NHEJ deficiency results in a wide variety of phenotypes including premature cellular senescence, immunodeficiency, defective neurogenesis, dwarfism, accelerated aging, and cancer predisposition. Notably, NHEJ is mostly dispensable in resolving the "clean" chromosome breaks used in many experimental models. Why, then, are the phenotypes of NHEJ deficiency so severe? We will address here if NHEJ's pivotal role in maintaining genome stability is at least in part due to a unique ability to flexibly cope with the complex end structures expected in biologically relevant contexts. Of particular interest to this proposal, broken ends generated by ionizing radiation, radiomimetic drugs, or chronic oxidative stress possess associated damage to flanking DNA, including oxidized and missing bases. The ability of ionizing radiation and radiomimetic drugs to introduce such complex damage is a major factor in the biological impact of these agents, and thus critical in the effectiveness of these agents in tumor therapy. In Aim 1, we will determine how associated radiomimetic damage effects how NHEJ joins ends, both in vitro and in cells. Ku is a key factor in repair of breaks by NHEJ. In Aim 2 we will address the extent to which Ku's recently described ability to excise damaged nucleotides from ends contributes to its role in NHEJ. In Aim 3 we will determine how NHEJ regulates the fidelity of the ligation step, and what impact regulation of fidelity has on resolution of complex end structures.

抽象的 非同源末端连接（NHEJ）是解析染色体的主要途径 双链断裂。 NHEJ 缺陷会导致多种表型，包括 细胞过早衰老、免疫缺陷、神经发生缺陷、侏儒症、 加速衰老和癌症倾向。 值得注意的是，NHEJ 在解决所使用的“干净”染色体断裂方面基本上是可有可无的 在许多实验模型中。那么，为什么 NHEJ 缺陷的表型如此严重？ 严重的？ 我们将在这里讨论 NHEJ 在维持基因组稳定性方面的关键作用至少是在 部分归因于灵活应对复杂端部结构的独特能力 生物学相关的背景。对此提案特别感兴趣的是，断头 由电离辐射、拟放射药物或慢性氧化应激产生的 侧翼 DNA 的相关损伤，包括碱基氧化和缺失。的能力 电离辐射和拟放射药物引入这种复杂的损伤是一个主要的原因 这些因素的生物影响因素，因此对有效性至关重要 这些药物在肿瘤治疗中的作用。 在目标 1 中，我们将确定相关的拟辐射损伤如何影响 NHEJ 在体外和细胞内连接末端。 Ku 是 NHEJ 修复断裂的关键因素。在目标 2 中，我们将解决以下问题： Ku 最近描述了从末端切除受损核苷酸的能力 有助于其在 NHEJ 中的作用。 在目标 3 中，我们将确定 NHEJ 如何调节连接步骤的保真度，以及什么 保真度调节对复杂末端结构的分辨率有影响。