Structure and Mechanism of Non-Homologous End Joining

非同源末端连接的结构和机制

• 批准号: 10331036
• 负责人: Yuan He
• 金额: $ 34.56万
• 依托单位: NORTHWESTERN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-11 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10331036
• 关键词: Adaptive Immune System; Address; Apoptosis; Architecture; Biochemical; Cancer Etiology; Cancerous; Catalytic Domain; Cell Cycle; Cells; Chemicals; Chromatin; Chromosomes; Complex; Coupling; Cryoelectron Microscopy; DNA; DNA Damage; DNA-PKcs; DNA-dependent protein kinase; Development; Double Strand Break Repair; Exons; Filament; G22P1 gene; Genes; Genetic Recombination; Genome; Genome Stability; Genomic Instability; Goals; Holoenzymes; Human; Immune; Immunoglobulin Genes; In Vitro; Ionizing radiation; LIG4 gene; Lead; Ligase; Ligation; Malignant Neoplasms; Mass Spectrum Analysis; Modeling; Molecular; Molecular Machines; Nonhomologous DNA End Joining; Nucleosomes; Pathway interactions; Phosphorylation; Phosphotransferases; Physiological; Process; Reactive Oxygen Species; Regulation; Resolution; Role; Signal Transduction; Site; Structure; Structure-Activity Relationship; Synapses; System; Techniques; Testing; Time; Transcription Initiation; V(D)J Recombination; XRCC4 gene; cancer therapy; crosslink; dimer; ds-DNA; improved; interdisciplinary approach; mechanical signal; novel; operation; particle; reconstitution; recruit; repaired; response; senescence

Summary Among all different types of DNA damages, double strand breaks (DSBs) are viewed as the most toxic ones that lead to genome instability. They are created by either endogenous agents such as reactive oxygen species, or exogenous ionizing radiation and chemicals. Unrepaired DSBs drive apoptosis and senescence, and incorrect DSB repair can lead to undesired genome rearrangements, such as deletions, translocations, and fusions. Non-homologous end-joining (NHEJ) pathway, in which the two broken DNA ends are directly ligated without referring to a homologous template, is the primary DSB repair pathway that remains active throughout the cell cycle. NHEJ is also responsible for the assembly of gene segments in V(D)J recombination, where various immunoglobulin genes are generated by exon recombination in immune cells. NHEJ is initialized by Ku heterodimer (Ku70/80) recognizing DSB ends. Upon recognizing a dsDNA broken end, Ku70/80 recruits the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and assembles into the so-called DNA-PK holoenzyme. Other evolutionarily conserved NHEJ factors, including components of the ligase complex (DNA ligase IV, XRCC4 and XLF) are then recruited to the end reparation site. Successful DSB repair through NHEJ relies on the efficient bridging of two broken DNA ends, and this proposal aims to investigate the mechanism of NHEJ by directly visualizing the key steps of repair using single-particle cryo-EM. A more refined picture of the system specifically recognizing and correcting DSBs will provide an unprecedented, comprehensive view of these essential molecular machines during operation, and could lead to the development of novel treatments for various types of human cancer.

概括 在所有不同类型的DNA损伤中，双链断裂（DSB）被视为最有毒的损坏 这导致基因组不稳定。它们是由两种内源性剂（例如活性氧）创建的 物种，或外源电离辐射和化学物质。未修复的DSB驱动凋亡和衰老， 不正确的DSB修复会导致不希望的基因组重排，例如缺失，易位， 和融合。非同源最终连接（NHEJ）途径，其中两个断裂的DNA末端直接 连接而无需指代同源模板，是保持活跃的主要DSB修复途径 在整个细胞周期中。 NHEJ还负责V（d）J重组中的基因段组装， 其中通过免疫细胞中外显子重组产生了各种免疫球蛋白基因。 NHEJ是初始化的 由KU Heterodimer（KU70/80）识别DSB末端。一旦识别出DSDNA破裂的末端，Ku70/80新兵 DNA依赖性蛋白激酶催化亚基（DNA-PKC）并组装到所谓的DNA-PK中 全酶。其他进化保守的NHEJ因子，包括连接酶复合物的成分（DNA 然后将连接酶IV，XRCC4和XLF）招募到最终赔偿站点。通过NHEJ成功维修DSB 依赖于两个破裂的DNA末端的有效桥接，该建议旨在研究 NHEJ通过直接使用单粒子冷冻EM可视化修复的关键步骤。更精致的图片 专门识别和纠正DSB的系统将提供前所未有的全面观点 操作过程中这些必需的分子机器，并可能导致新治疗的发展 对于各种类型的人类癌症。