53BP1-dependent pathway in DNA repair

项目总结 尽管在过去几年中在定义不同的DNA修复途径方面取得了快速进展，但我们对 DNA修复中的P53结合蛋白1(53BP1)仍不完整。我的实验室有兴趣弄清楚 基因组不稳定和肿瘤发生的分子机制。自从我在年开始我的实验室 1999年以来，我们已经发现并鉴定了许多重要的DNA损伤检查点和修复蛋白。我们的 长期目标是揭示DNA修复网络的复杂规则，这将使我们能够 对癌症生物学和治疗做出有意义的贡献。 这项提案的重点是53BP1，它是DNA修复的关键组成部分。很多年前，我们的团队是 首次证明了53BP1在DNA损伤反应中的作用。我们建立了第一个53BP1基因敲除 并揭示了53BP1是DNA修复所必需的，并在体内起到了肿瘤抑制作用。此外, 我们阐明了53BP1在DNA损伤后的调控。特别是，在过去十年中，我们和其他人 研究表明，依赖于H_2AX的DNA损伤信号通路由H_2AX、MDC1、RNF8、 和RNF168，控制53BP1在DNA断裂部位的募集和积累。特别是，我们 研究表明，由于53BP1在DNA修复中的作用，它对一种名为Class-1的特殊修复过程至关重要 开关重组，表明53BP1参与了一种特殊的DNA修复途径，这种途径明显 不同于典型的非同源末端连接(NHEJ)途径。此外，我们最近的研究和 其他人则认为53BP1控制着两条下游亚通路，并抑制同源基因 BRCA1缺陷细胞中的重组(HR)修复，这对癌症的反应至关重要 基于聚(ADP-核糖)聚合酶抑制剂(PARPI)的治疗。总而言之，这些数据突出了 存在真正的53BP1依赖的修复途径，但尚未得到彻底的研究。我们的 本提案的目标是进一步了解53BP1依赖的修复途径并揭示 从机制上讲，它是如何抵消HR修复途径对DNA损伤的反应。 为了实现这些目标，我们提出了以下具体目标：1)划定53BP1依赖的末端- 加入修复途径；2)阐明其调控和功能的分子机制。 Rif1-Rev7分支的53BP1依赖的修复途径；3)从机械上揭示HR是如何 通路在没有BRCA1和53BP1的情况下工作。这些拟议的研究具有重要意义，因为它们 不仅将阐明复杂DNA修复网络中53BP1依赖的修复途径，而且还将 为癌症患者提供克服治疗阻力的方法。

PROJECT SUMMARY Despite rapid progress in defining distinct DNA repair pathways over the past few years, our knowledge of p53-binding protein 1 (53BP1) in DNA repair remains incomplete. My laboratory is interested in elucidating the molecular mechanisms underlying genomic instability and tumorigenesis. Since I started my laboratory in 1999, we have discovered and characterized many essential DNA damage checkpoint and repair proteins. Our long-term goal is to reveal the complex regulation of the DNA repair network, which will permit us to meaningfully contribute to cancer biology and treatment. This proposal focuses on 53BP1, a key component in DNA repair. Many years ago, our group was one of the first to demonstrate the role of 53BP1 in DNA damage response. We established the first 53bp1 knockout mice and revealed that 53BP1 is required for DNA repair and acts as a tumor suppressor in vivo. In addition, we elucidated the regulation of 53BP1 after DNA damage. In particular, over the past decade, we and others demonstrated that the H2AX-dependent DNA damage signaling pathway, composed of H2AX, MDC1, RNF8, and RNF168, controls the recruitment and accumulation of 53BP1 at sites of DNA breaks. In particular, we showed that 53BP1, because of its role in DNA repair, is critical for a particular repair process called class- switch recombination, indicating that 53BP1 is involved in a special DNA repair pathway that is distinctly different from the canonical nonhomologous end-joining (NHEJ) pathway. Moreover, our recent studies and those of others suggest that 53BP1 controls two downstream sub-pathways and suppresses homologous recombination (HR) repair in BRCA1-deficient cells, which is critically important for response to cancer therapies based on poly (ADP-ribose) polymerase inhibitors (PARPi). Together, these data highlight the existence of a bona fide 53BP1-dependent repair pathway that has not been thoroughly investigated. Our goals in this proposal are to further understand the 53BP1-dependent repair pathway and reveal mechanistically how it counteracts the HR repair pathway in response to DNA damage. To achieve these goals, we propose the following specific aims: 1) delineate the 53BP1-dependent end- joining repair pathway; 2) elucidate the molecular mechanisms underlying the regulation and function of the RIF1-REV7 branch of the 53BP1-dependent repair pathway; and 3) reveal mechanistically how the HR pathway operates in the absence of BRCA1 and 53BP1. These proposed studies are significant because they not only will elucidate the 53BP1-dependent repair pathway in the complex DNA repair network, but also will provide ways to overcome therapy resistance for cancer patients.