53BP1-dependent pathway in DNA repair

项目摘要 尽管在过去的几年里，在定义不同的DNA修复途径方面取得了迅速的进展，但我们对DNA修复途径的认识仍然不足。 p53结合蛋白1（53 BP 1）在DNA修复中的作用仍然不完全。我的实验室对阐明 基因组不稳定性和肿瘤发生的分子机制。自从我在2004年开始我的实验室以来， 1999年，我们发现并鉴定了许多重要的DNA损伤检查点和修复蛋白。我们 长期目标是揭示DNA修复网络的复杂调控，这将使我们能够 对癌症生物学和治疗有意义的贡献。 该提案的重点是53 BP 1，这是DNA修复的关键组成部分。很多年前，我们的团队是 第一个证明了53 BP 1在DNA损伤反应中的作用。我们建立了第一个53 bp 1敲除 小鼠，并揭示53 BP 1是DNA修复所需的，并在体内作为肿瘤抑制因子。此外，本发明还提供了一种方法， 我们阐明了53 BP 1在DNA损伤后的调节作用。特别是，在过去十年中，我们和其他人 证实了由H2 AX，MDC 1，RNF 8， 和RNF 168控制53 BP 1在DNA断裂位点的募集和积累。我们尤其 表明，53 BP 1，由于其在DNA修复中的作用，是一个特殊的修复过程称为类- 开关重组，表明53 BP 1参与了一个特殊的DNA修复途径， 与典型的非同源末端连接（NHEJ）途径不同。此外，我们最近的研究和 其他人的结果表明，53 BP 1控制两个下游亚通路，并抑制同源的 BRCA 1缺陷细胞中的重组（HR）修复，这对癌症反应至关重要 基于聚（ADP-核糖）聚合酶抑制剂（PARPi）的疗法。总之，这些数据突出了 一个真正的53 BP 1依赖性修复途径的存在尚未得到彻底的研究。我们 该提案的目标是进一步了解53 BP 1依赖的修复途径，并揭示 它是如何机械地抵消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）描绘53 BP 1依赖的末端， 连接修复途径; 2）阐明了调节和功能的分子机制， 53 BP 1依赖性修复途径的RIF 1-REV 7分支;和3）揭示HR如何在机制上 在BRCA 1和53 BP 1不存在的情况下，这些建议的研究意义重大，因为它们 不仅将阐明复杂DNA修复网络中依赖于53 BP 1的修复途径， 为癌症患者提供克服治疗耐药性的方法。

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.