Defining WASp-dependent pathways in replication stress

复制应激反应(RSR)和DNA损伤反应(DDR)中的扰动导致 基因组不稳定。复制蛋白A(RPA)是单链DNA(SsDNA)结合蛋白 在RSR和DDR中扮演关键角色。Wiskott-Aldrich综合征患者存在基因组不稳定性 (曾是)，一种原发免疫缺陷和癌症易感性疾病，但分子 RAS细胞中不稳定基因组的基础仍未确定。黄蜂，一种蛋白质 在这种紊乱中缺乏，在细胞质和细胞核中都起作用。在细胞核中，黄蜂 防止有害的R环(RNA-DNA杂交物+单链DNA)积累的功能 修复前步骤，通过同源定向修复将断裂的DNA末端护送到修复位置 (HDR)途径。因此，患者的淋巴细胞装备不佳，既不能预防也不能预防 解决DNA损伤，这是一种“基因毒素敏感型”免疫失调 无序。我们的基础性研究揭示了黄蜂在RSR中的一个重要作用 羟基脲诱导的复制应激对RPA功能的影响 非免疫细胞。因此，这项提议的总体目标是解释分子 黄蜂如何保护正常复制以及黄蜂有哪些蛋白质和途径的详细信息 与关联以在复制应激期间启用此功能。我们将检验这一假设 黄蜂是预防和管理复制应激和DNA损伤所必需的。具体来说， 我们将在处理被阻止的复制分叉的机制中定义黄蜂角色(在目标1中)和 阐述黄蜂在改变肌动蛋白状态(G-肌动蛋白与F-肌动蛋白)方面的具体作用 RSR(目标2)。实现这些目标将提出黄蜂作为一种新的RSR因子，而人类 是一种RSR功能障碍的疾病，这可能为肿瘤的发生提供新的机制 在过去。

Perturbation in the replication-stress response (RSR) and DNA damage response (DDR) causes genomic-instability. Replication protein A (RPA) is a single-strand DNA (ssDNA) binding protein with key roles in the RSR and DDR. Genomic-instability occurs in Wiskott-Aldrich syndrome (WAS), a primary immunodeficiency and cancer susceptibility disorder, yet the molecular underpinnings of unstable genome in WAS cells remain uncharacterized. WASp, the protein deficient in this disorder, functions both in the cytoplasm and nucleus. In the nucleus, WASp functions to prevent the accumulation of harmful R loops (RNA-DNA hybrids + ssDNA) and in the pre-repair step of escorting broken DNA ends to the repair sites by the homology-directed repair (HDR) pathway. Accordingly, WAS patient lymphocytes are poorly-equipped to both prevent and resolve DNA damage, which proposes WAS as a “genotoxin-sensitive” immune dysregulation disorder. Our foundational studies have uncovered an essential role of WASp in the RSR by influencing RPA functions under hydroxyurea-induced replication stress, in both immune and nonimmune cells. Therefore, the overall objective of this proposal is to explicate the molecular details of how WASp safeguards normal replication and which proteins and pathways WASp associates with to enable this function during replicative stress. We will test the hypothesis that WASp is required to both prevent and manage replication stress and DNA damage. Specifically, we will define WASp role in mechanisms that process a blocked replication fork (in Aim 1) and address how WASp role specifically on modifying the actin state (G-actin vs. F-actin) influence RSR (in Aim 2). Achieving these aims will propose WASp as a novel RSR factor, and human WAS as a disease of dysfunctional RSR, which may provide new mechanisms for oncogenesis in WAS.