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: 8056148
• 负责人: DALE A RAMSDEN
• 金额: $ 25.12万
• 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/8056148
• 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; Health; 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; base; cell killing; coping; insight; interest; killings; neoplastic cell; neurogenesis; premature; repaired; restriction enzyme; tool; tumor

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: This work represents a systematic study addressing how our cells resolve chromosome breaks caused by chronic stress or acute radiation exposure. Our work will provide insights into aging and how radiation kills cells, and will be used to generate safer and more effective ways to use radiation as a tool for therapy.

描述（由申请人提供）：非同源末端连接（NHEJ）是解决染色体双链断裂的主要途径。 NHEJ缺乏会导致多种表型，包括过早的细胞衰老，免疫缺陷，神经发生缺陷，矮人，加速衰老和癌症易感性。值得注意的是，NHEJ在解决许多实验模型中使用的“清洁”染色体断裂方面大多是可分配的。那么，为什么NHEJ缺乏症的表型如此严重？如果NHEJ在维持基因组稳定性方面的关键作用至少是由于独特的能力灵活应对生物学相关环境中预期的复杂端结构，我们将在此处解决。该提案特别感兴趣的是，电离辐射，放射性药物或慢性氧化应激产生的破碎末端对侧翼DNA具有相关的损害，包括氧化和缺失的碱基。电离辐射和放射性药物引入这种复杂损伤的能力是这些药物的生物学影响的主要因素，因此对于这些药物在肿瘤治疗中的有效性中至关重要。在AIM 1中，我们将确定相关的放射性损伤如何影响NHEJ在体外和细胞中如何结束。 KU是NHEJ修复休息时间的关键因素。在AIM 2中，我们将解决KU最近描述从末端切除核苷酸损坏的核苷酸的能力的程度，从而有助于其在NHEJ中的作用。在AIM 3中，我们将确定NHEJ如何调节结扎步骤的保真度，以及忠诚度的影响对解决复杂终端结构的解决的影响。公共卫生相关性：这项工作代表了一项系统的研究，解决了我们的细胞如何解决由慢性应激或急性辐射暴露引起的染色体断裂。我们的工作将提供有关衰老和辐射如何杀死细胞的见解，并将用于生成更安全，更有效的方法，以使用辐射作为治疗工具。