Define redundant functions of H2AX and NBS1 in DNA repair

项目摘要 破译基因组不稳定和肿瘤发生的分子机制是长期的 我实验室的目标。这项提议的广泛目标反映了我们对获得全面的 了解参与DNA修复的网络，并确定这些蛋白质和途径是如何 交叉、相互作用、交流、协调和协作，以进行基因组维护。短期目标是 对几个DNA损伤信号和修复途径进行详细的机制研究，这将 为实现我们利用DNA修复网络进行癌症治疗的长期目标提供基础。 这项提案将定义两条重叠的DNA损伤信号通路，这两条通路共同对 细胞存活。我们和其他研究人员已经构建了一条复杂的信号通路，它作用于下游 并调节许多DNA损伤修复蛋白在DNA位点的募集和积累 休息一下。这种依赖于H_2AX的途径由H_2AX、MDC1、RNF8和RNF168组成。然而，修复 在H2 AX、MDC1、RNF8或RNF168缺陷的细胞或小鼠中观察到的缺陷是轻微的，增加了这种可能性 在这些下游修复的招募中涉及到一种不依赖于H_2AX的机制 蛋白质。我们认为这种不依赖于H_2AX的途径是由NBS1控制的。 根据我们以前的研究和本提案中提出的初步数据，我们假设 依赖于H_2AX和NBS_1的通路参与了DNA损伤反应，对细胞至关重要 生死存亡。我们认为这两条途径有多余的功能，特别是在促进同源 重组修复。然而，它们并不是完全分开的，因为它们在多个点相交。这 这给我们描绘这两条多余路径的功能带来了相当大的挑战。它是 未知我们是否可以阐明单一路径对不断增长的网络的贡献，即可以 我们解开网络以了解不同路径相交和贡献的机制 到生物过程吗？我们将在本申请中解决这个问题，并将进一步研究 依赖H_2AX和NBS1的通路共同作用以确保细胞存活和 完成DNA修复。我们提出以下具体目标：1)确定NBS1是否发挥作用 冗余地与已建立的H2 AX-MDC1-RNF8-RNF168途径一起确保细胞存活；2)描绘 NBS1依赖的途径；3)探讨NBS1和H_2AX致细胞死亡的机制 共同耗尽。这些研究不仅将使我们了解H_2AX和NBS1的冗余功能 但也将揭示研究蛋白质和通路在当今复杂信号转导中的功能的方法 网络。此外，这些研究的结果将为利用DNA修复缺陷和 综合致命性概念在癌症患者精准医学中的应用。

Project Summary Deciphering the molecular mechanisms underlying genomic instability and tumorigenesis is the long-term goal of my laboratory. The broad objective, of this proposal, reflects our pursuit to gain a comprehensive understanding of the network involved in DNA repair and to determine how these proteins and pathways intersect, interact, communicate, coordinate, and collaborate for genome maintenance. The short-term goal is to perform detailed mechanistic studies of several DNA damage signaling and repair pathways, which will provide the foundation to achieve our long-term goal of exploiting DNA repair network for cancer therapy. This proposal will define two overlapping DNA damage-signaling pathways that together are essential for cell survival. We and other researchers have constructed an elaborate signaling pathway that acts downstream of H2AX and regulates the recruitment and accumulation of many DNA damage repair proteins at sites of DNA breaks. This H2AX-dependent pathway is composed of H2AX, MDC1, RNF8, and RNF168. However, repair defects observed in H2AX-, MDC1-, RNF8-, or RNF168-deficient cells or mice are mild, raising the possibility that there is an H2AX-independent mechanism involved in the recruitment of these downstream repair proteins. We propose that this H2AX-independent pathway is controlled by NBS1. On the basis of our previous studies and preliminary data presented in this proposal, we hypothesize that the H2AX- and NBS1-dependent pathways are involved in the DNA damage response and are critical for cell survival. We believe that these two pathways have redundant functions, especially in promoting homologous recombination repair. However, they are not completely separate, since they intersect at multiple points. This makes it considerably challenging for us to delineate the functions of these two redundant pathways. It is unknown whether we can elucidate the contribution of a single pathway to the ever-growing network, i.e., can we untangle the network to understand the mechanisms by which different pathways intersect and contribute to biological processes? We will address this question in this application and we will further study the mechanisms by which the H2AX- and NBS1-dependent pathways act together to ensure cell survival and the completion of DNA repair. We propose the following specific aims: 1) determine whether NBS1 acts redundantly with the established H2AX-MDC1-RNF8-RNF168 pathway to ensure cell survival; 2) delineate the NBS1-dependent pathway; and 3) explore the mechanisms underlying cell lethality caused by NBS1 and H2AX co-depletion. These studies will not only allow us to understand the redundant functions of H2AX and NBS1 in vivo but will also reveal ways to investigate the functions of proteins and pathways in today’s complex signaling networks. Moreover, results from these studies will provide the rationale for exploiting DNA repair defect and applying synthetic lethality concept in precision medicine for cancer patients.