Mechanism and Regulation of Nonhomologous DNA End Joining

非同源DNA末端连接的机制和调控

• 批准号: 7942230
• 负责人: MICHAEL R LIEBER
• 金额: $ 15.79万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7942230
• 关键词: Affect; Age; Aging; BRCT Domain; Binding; Cancer Etiology; Cells; Chemicals; Chromosomal translocation; Chromosome Pairing; Complex; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; DNA Repair Pathway; DNA Sequence; DNA Structure; DNA ligase IV; DNA-PKcs; DNA-Protein Interaction; Development; Enzymes; Free Radicals; Histones; Human; Ionizing radiation; Ku Protein; Length; Ligase; Ligation; Malignant Neoplasms; Mediating; Modification; Mutation; Nonhomologous DNA End Joining; Pathway interactions; Polymerase; Positioning Attribute; Price; Process; Property; Proteins; Radiation; Radiation-Sensitizing Agents; Regulation; Site; Somatic Cell; System; Tail; Testing; Therapeutic; Time; Variant; Vertebral column; Vertebrates; Work; X-Ray Crystallography; artemis; chemotherapy; flexibility; homologous recombination; improved; in vivo; inhibitor/antagonist; inorganic phosphate; insight; mutant; nuclease; phosphodiester; public health relevance; reconstitution; repaired; small molecule; spatial relationship; stoichiometry

DESCRIPTION (provided by applicant): Double-strand DNA breaks (DSBs) occur in all cells multiple times per day. Homologous recombination (HR) and nonhomologous DNA end-joining (NHEJ) are the two primary pathways for repairing DSBs. However, NHEJ is the more general pathway because it does not require a homologous donor, and NHEJ is sufficiently flexible that it can join almost any pair of incompatible DNA ends. The flexibility of NHEJ is essential because natural causes of DSBs (ionizing radiation, free radicals, enzyme malfunction) generate DNA ends with diverse chemical and structural configurations. Hence, that flexibility is well-suited for the task, but the price that we pay for that flexibility is that NHEJ causes DNA sequence changes at most sites where it functions (in humans and other vertebrates). Hence, NHEJ generates somatic cell mutations that cause cancer and likely contribute to aging. The flexibility of NHEJ represents one of the most sophisticated protein:DNA interaction pathways. Though we know most of the proteins that participate in NHEJ and know, in broad terms, what they do, we do not have a clear picture of how they function together, their spatial configuration, or the temporal relationships. With a clearer mechanistic and structural picture of human NHEJ, we will be in a position to develop small molecule inhibitors that may be useful for treating cancer (as chemotherapy or as a radiation sensitizer). Aims 1 and 2 of this proposal focus precisely on the issues of structural and spatial relationships among the NHEJ proteins and with the DNA ends. Aim 3 tests the hypothesis that the NHEJ ligase complex is important for making key end-to-end contacts during NHEJ. Aim 4 describes development of a more robust NHEJ reconstitution. In Aim 4, that system is then used to identify any remaining NHEJ factors by testing for enhancement of activity. Aim 5 describes analysis of how histone octamers influence the nuclease, polymerase, and ligase activities of NHEJ. These studies will markedly improve our understanding of how NHEJ participates in processes such as chromosomal translocations that are of key importance in cancer etiology and how NHEJ might be made 'druggable' for therapeutic purposes. PUBLIC HEALTH RELEVANCE: This project would clarify our insights into one of the key pathways for the repair of DNA damage. These insights will allow us to understand how some of the DNA damage that causes cancer and aging occurs. The benefits of some chemotherapy and therapeutic radiation work can be increased by this deeper level of understanding of this key DNA repair pathway.

描述（由申请人提供）：双链 DNA 断裂（DSB）每天在所有细胞中发生多次。同源重组 (HR) 和非同源 DNA 末端连接 (NHEJ) 是修复 DSB 的两种主要途径。然而，NHEJ 是更通用的途径，因为它不需要同源供体，并且 NHEJ 足够灵活，可以连接几乎任何一对不相容的 DNA 末端。 NHEJ 的灵活性至关重要，因为 DSB（电离辐射、自由基、酶故障）的自然原因会产生具有不同化学和结构构型的 DNA 末端。因此，这种灵活性非常适合这项任务，但我们为这种灵活性付出的代价是 NHEJ 在其发挥作用的大多数位点（在人类和其他脊椎动物中）导致 DNA 序列发生变化。因此，NHEJ 会产生导致癌症并可能导致衰老的体细胞突变。 NHEJ 的灵活性代表了最复杂的蛋白质：DNA 相互作用途径之一。虽然我们知道参与 NHEJ 的大多数蛋白质，并且从广义上讲，知道它们的作用，但我们并不清楚它们如何一起发挥作用、它们的空间配置或时间关系。随着人类 NHEJ 的机制和结构更加清晰，我们将能够开发可用于治疗癌症的小分子抑制剂（作为化疗或放射增敏剂）。该提案的目标 1 和 2 重点关注 NHEJ 蛋白之间以及与 DNA 末端的结构和空间关系问题。目标 3 检验 NHEJ 连接酶复合物对于 NHEJ 期间关键的端到端接触非常重要的假设。目标 4 描述了更稳健的 NHEJ 重建的开发。在目标 4 中，该系统随后用于通过测试活动增强来识别任何剩余的 NHEJ 因素。目标 5 描述了组蛋白八聚体如何影响 NHEJ 的核酸酶、聚合酶和连接酶活性的分析。这些研究将显着提高我们对 NHEJ 如何参与染色体易位等过程的理解，这些过程在癌症病因学中至关重要，以及 NHEJ 如何变得“可成药”用于治疗目的。 公共健康相关性：该项目将阐明我们对修复 DNA 损伤的关键途径之一的见解。这些见解将使我们了解导致癌症和衰老的一些 DNA 损伤是如何发生的。通过更深入地了解这一关键的 DNA 修复途径，可以增加一些化疗和放射治疗工作的益处。