Role of Telomerase is DSB Repair

端粒酶的作用是 DSB 修复

• 批准号: 10052953
• 负责人: Weihang Chai
• 金额: $ 1.6万
• 依托单位: LOYOLA UNIVERSITY CHICAGO
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-12-01 至 2020-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10052953
• 关键词: Role; Telomerase; DSB; Repair

Double-strand breaks (DSBs) represent one of the most deleterious forms of DNA damage. They arise following exposure to ionizing radiation or radio-mimetic chemicals, and are also generated as a byproduct of normal cellular metabolism. Faithful repair of DSBs is critical for preserving genome integrity and suppressing malignant transformation. Accurate understanding of DSB repair mechanisms is not only important for understanding tumorigenesis, but also impacts tumor response to radiation therapy and most chemotherapy agents. During DSB repair, telomerase — an enzyme normally catalyzing the extension of telomeric DNA at chromosome ends — is capable of promiscuously adding telomeric repeats at intra-chromosomal DSBs, potentially interfering with accurate repair. Previous studies have shown that addition of telomeric repeats into intra-chromosomal regions (known as telomere sequence insertion, or TSI) causes chromosome breakage, recombination, and rearrangements. Therefore, TSI is normally suppressed to prevent genome instability. However, the role of telomerase in DSB repair has long been neglected, and it remains unknown how telomerase-mediated TSI at DSBs is suppressed in human and mammalian cells. Our recent findings strongly support that TSI is caused by erroneous addition of telomeric repeats at DSBs by telomerase. In addition, we have identified MLH1 as a TSI suppressor in telomerase-expressing cells. Using domain-specific mutations of MLH1, we also find that MLH1 recruitment to DSBs is required for suppressing TSI. The central hypothesis of this proposal is that in response to DSB induction, MLH1 localizes at intra-chromosomal break sites to prevent telomerase from adding telomeric repeats at DSBs, therefore ensuring accurate repair and protecting genome stability. The objective of this R03 proposal is to perform a second analysis of TSI and establish a defined molecular system to investigate the regulatory mechanism underlying TSI. In Aim 1, we will develop an inducible DSB repair system to study TSI. In Aim 2, we will define the roles of various DSB repair proteins in TSI suppression. Findings from the proposed research will gain novel insights and accurate understanding of DSB repair and genome instabilities, and offer guidance in developing new therapeutic strategies for tumor management.

双链断裂（DSB）是DNA损伤的最有害形式之一。于产生 在暴露于电离辐射或放射性模拟化学品后， 正常细胞代谢的副产品DSB的忠实修复是基因组保存的关键 完整性和抑制恶性转化。准确理解DSB修复机制 不仅对理解肿瘤发生很重要，而且影响肿瘤对辐射的反应 治疗和大多数化疗药物。在DSB修复过程中，端粒酶-一种通常催化 端粒DNA在染色体末端的延伸-能够混杂地添加端粒 在染色体内DSB重复，可能干扰准确的修复。以前的研究 已经表明在染色体内区域（称为端粒）中添加端粒重复序列 序列插入或TSI）引起染色体断裂、重组和重排。 因此，TSI通常被抑制以防止基因组不稳定。然而， 端粒酶在DSB修复中的作用一直被忽视， 在人类和哺乳动物细胞中，DSB的TSI受到抑制。我们最近的研究结果有力地支持了这一点， TSI是由端粒酶在DSB处错误添加端粒重复序列引起的。另外我们 已经确定MLH1是端粒酶表达细胞中的TSI抑制因子。使用特定于域的 我们还发现MLH1募集到DSB是抑制TSI所必需的。的 该建议的中心假设是，响应于DSB诱导，MLH1定位于 染色体内断裂位点以防止端粒酶在DSB处添加端粒重复， 从而保证了精确修复，保护了基因组的稳定性。本R03的目的 建议对TSI进行第二次分析，并建立一个定义的分子系统， 研究TSI背后的调控机制。在目标1中，我们将开发一种诱导型DSB 维修系统，以研究TSI。在目标2中，我们将定义各种DSB修复蛋白在 TSI抑制。从拟议的研究结果将获得新的见解和准确的 了解DSB修复和基因组不稳定性，并为开发新的 肿瘤管理的治疗策略。