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) 是最有害的 DNA 损伤形式之一。 暴露于电离辐射或拟辐射化学物质后，也以 DSB 的忠实修复对于保存基因组至关重要。 完整性和抑制恶性转化的准确理解。 不仅对肿瘤发生很重要，而且影响肿瘤对辐射的反应 在 DSB 修复过程中，端粒酶（一种通常具有催化作用的酶）会发挥作用。 染色体末端端粒 DNA 的延伸——能够随意添加端粒 在染色体内 DSB 处重复，可能会干扰先前的研究。 已经表明，将端粒重复添加到染色体内区域（称为端粒） 序列插入（TSI）会导致染色体断裂、重组和重排。 因此，通常会抑制 TSI 以防止基因组不稳定。 端粒酶在 DSB 修复中的作用长期以来一直被忽视，并且端粒酶如何介导仍不清楚 DSB 的 TSI 在人类和哺乳动物细胞中受到抑制。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 上错误添加端粒重复序列引起的。 使用域特异性将 MLH1 鉴定为端粒酶表达细胞中的 TSI 抑制因子。 MLH1 突变，我们还发现 MLH1 招募到 DSB 是抑制 TSI 所必需的。 该提议的中心假设是，响应 DSB 诱导，MLH1 定位于 染色体内断裂位点，以防止端粒酶在 DSB 处添加端粒重复序列， 因此确保精确修复并保护基因组稳定性是 R03 的目标。 建议对 TSI 进行第二次分析并建立一个明确的分子系统 研究 TSI 的调控机制 在目标 1 中，我们将开发一种诱导型 DSB。 修复系统来研究 TSI 在目标 2 中，我们将定义各种 DSB 修复蛋白在其中的作用。 TSI 抑制。拟议研究的结果将获得新颖和准确的见解。 了解 DSB 修复和基因组不稳定性，并为开发新的技术提供指导 肿瘤管理的治疗策略。