Mechanisms of Error Prone Repair of DNA Breaks

DNA 断裂的易错修复机制

• 批准号: 7216699
• 负责人: SANG EUN LEE
• 金额: $ 22.81万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7216699
• 关键词: Affect; Base Pairing; Biochemical Genetics; Biological; Biological Assay; Candidate Disease Gene; Cell Cycle Checkpoint; Cell Death; Cell physiology; Cells; Chemicals; Chromosomal Breaks; Chromosomal translocation; Complex; DNA; DNA Double Strand Break; DNA Ligation; DNA Repair; DNA annealing; Double Strand Break Repair; Excision; Exposure to; Failure; Gene Deletion; Gene Silencing; Genes; Genetic; Genetic Epistasis; Genetic Recombination; Genome; Goals; Human; Ionizing radiation; Ku Protein; Lead; Link; Malignant Neoplasms; Mediating; Mismatch Repair; Mutagens; Mutation; Nonhomologous DNA End Joining; Organism; Pathway interactions; Play; Process; Property; Proteins; Public Health; Rad52 protein; Radio; Reaction; Regulation; Research; Role; Saccharomyces; Single-Stranded DNA; Site; Staging; Surgical Flaps; System; Yeasts; base; endonuclease; homologous recombination; insight; interest; novel; nuclease; repaired; seal

DESCRIPTION (provided by applicant): DNA double-strand breaks (DSB)s are induced by a variety of genotoxic agents, including ionizing radiation and chemicals used for treating cancers. The elimination of DSBs proceeds via distinctive error-free and error-prone pathways. Repair by homologous recombination is largely error-free and mediated by the RAD52 epistasis group genes. Non-homologous end joining (NHEJ) that requires the Ku heterodimer can efficiently rejoin breaks, with occasional loss or gain of DNA information. Emerging evidence has unveiled a novel DNA end-joining mechanism that is independent of Rad52 and Ku proteins. This novel pathway of DSB repair seals DNA breaks by microhomology-mediated base-pairing of DNA single strands, followed by nucleolytic trimming of DNA flaps, DNA gap filling, and DNA ligation, yielding products that are almost always associated with DNA deletion. This highly error-prone DSB repair pathway is termed microhomology-mediated end joining (MMEJ). Dissecting the mechanism of MMEJ is of great interest because of its potential to destabilize the genome through gene deletions. We have developed a Saccharomyces-based biological system to create specific double-strand breaks that are preferentially repaired by MMEJ. The availability of this MMEJ assay presents a unique opportunity to dissect the genetic requirement of this reaction. In fact, this biological system has already allowed us to identify several gene products that affect the efficiency of MMEJ. The focus of this proposal is to delineate the functions of these gene products in MMEJ and to identify additional genes that influence this process. Since the components of DSB repair are conserved from yeast to humans, the insights garnered from our research will be valuable for dissecting the equivalent process in human cells and will be of relevance to public health.

描述（由申请人提供）：DNA双链断裂（DSB）由多种遗传毒性剂诱导，包括电离辐射和用于治疗癌症的化学品。DSB的消除是通过独特的无错误和易错误途径进行的。通过同源重组的修复在很大程度上是无错误的，并且由RAD 52上位组基因介导。需要Ku异源二聚体的非同源末端连接（NHEJ）可以有效地重新连接断裂，偶尔会丢失或获得DNA信息。新出现的证据揭示了一种新的DNA末端连接机制，该机制独立于Rad52和Ku蛋白。这种新的DSB修复途径通过DNA单链的微同源介导的碱基配对来密封DNA断裂，然后是DNA瓣的溶核修剪，DNA缺口填充和DNA连接，产生几乎总是与DNA缺失相关的产物。这种高度易错的DSB修复途径被称为微同源介导的末端连接（MMEJ）。剖析MMEJ的机制是非常感兴趣的，因为它有可能通过基因缺失使基因组不稳定。我们已经开发了一种基于放线菌的生物系统，以产生优先由MMEJ修复的特异性双链断裂。这种MMEJ检测的可用性提供了一个独特的机会来剖析这种反应的遗传要求。事实上，这个生物系统已经使我们能够鉴定出几种影响MMEJ效率的基因产物。这项建议的重点是描绘这些基因产物在MMEJ中的功能，并确定影响这一过程的其他基因。由于DSB修复的组成部分从酵母到人类都是保守的，因此从我们的研究中获得的见解对于解剖人类细胞中的等效过程非常有价值，并且与公共卫生相关。