Mechanistic Characterization of the Replication Stress Response

项目摘要 准确的DNA复制是决定每一个生物体生存的基本过程。 细胞DNA不断受到各种来源的攻击。细胞复制机制 经常遇到并且非常容易受到阻碍其前进的代理人的攻击，导致 复制错误，突变的发展和各种形式的遗传不稳定性。因此 其中，复制应激水平升高是各种疾病的特征性标志， 条件因此，关键是要了解分子细节的不同机制， 在复制应激过程中，细胞会对受损的DNA做出反应并充分修复。虽然 我们对DNA断裂是如何修复的了解很多，但在我们的理解中存在着一个重大的差距。 细胞如何充分应对复制压力，部分原因是缺乏遗传和 生化工具来探测这些过程。为了进一步了解所涉及的过程， 在复制应激反应中，为了识别和描述基因的全貌， 在我的博士后期间，我在多个细胞中进行了全基因组筛选， 用低剂量的复制应激诱导剂扰动后的细胞系。从这些 我生成了一个新的数据集，其中包括多个尚未与 基因组不稳定性一些新发现的基因与染色质反应有关， 复制叉维持途径、核苷酸生物合成的调节等。的 注意，我鉴定了Protexin复合物，由单链DNA结合蛋白组成 SCAI和DNA聚合酶REV3。蛋白质是维持基因组不稳定性的关键 通过未知的机制调节单链DNA的积累。这些屏幕 还揭示了RNA依赖过程在复制应激反应中的显著作用， 这是一个以前从未被重视的新的监管层。在我们的热门歌曲中，我们 鉴定了几种新的RNA解旋酶和RNA结合因子，以及几种非编码 RNA分子，证明了RNA依赖性过程和 保持基因组的稳定性。我的实验室将利用这一巨大的资源， 新发现的因素，以表征新的基因组维护机制。调查 这些新的因素将使我们能够详细地破译协调的，多层次的修复， 反应和叉恢复控制后暴露于DNA损伤。我们将（1）描述 复制应激后单链积累的机制。2)识别 RNA修饰酶在复制应激反应中发挥作用的机制，以及 3)阐明非编码RNA基因在复制应激反应中的作用。 这些研究项目的完成将使我们获得重要和基本的新见解 细胞基因组在面对破坏性的侮辱时是如何维持的， 更详细和开放地了解癌症发病机制的原理 为利用缺陷DNA修复过程治疗癌症开辟了新的途径。

PROJECT SUMMARY Accurate DNA replication is a fundamental process that governs the survival of every organism. Cellular DNA is under constant assault from various sources. The cellular replication machinery frequently encounters and is severely vulnerable to agents that stall its advancement, leading to replicative errors, development of mutations, and various forms of genetic instability. As a result of this, elevated levels of replication stress is a characteristic hallmark of various disease conditions. It is therefore critical to understand in molecular detail the varied mechanisms by which cells respond to and adequately repair damaged DNA during replication stress. Although we know a lot about how breaks in DNA are repaired, there is a major gap in our understanding of how cells adequately respond to replication stress in part due to the lack of genetic and biochemical tools to probe these processes. To gain further insights into the processes involved in the replication stress response, and in order to identify and characterize the panoply of genes required for this pathway, during my postdoc I performed whole genome screens in multiple cell lines following perturbations with low doses of replication stress-inducing agents. From these screens I generated a novel dataset that includes multiple genes that have yet to be linked with genome instability. Several newly identified genes were linked to chromatin responses, replication fork maintenance pathways, regulation of nucleotide biosynthesis and others. Of note, I identified the Protexin complex, consisting of the single stranded DNA binding protein SCAI and the DNA polymerase REV3. Protexin was critical for maintaining genomic instability by regulating single stranded DNA accumulation through unknown mechanisms. These screens also revealed a striking role for RNA dependent processes in the replication stress response, a novel layer of regulation that had not been appreciated before now. Among our top hits, we identified several novel RNA helicases and RNA-binding factors, as well as several non-coding RNA molecules, demonstrating a crucial, intimate link between RNA-dependent processes and adequate maintenance of genome stability. My lab will take advantage of this vast resource of newly identified factors to characterize novel genome maintenance mechanisms. Investigating these novel factors will allow us to decipher in detail the concerted, multi-layered repair response and fork restoration control upon exposure to DNA damage. We will (1) characterize the mechanism of single stranded accumulation following replication stress. 2) Identify mechanisms by which RNA-modifying enzymes function in the replication stress response, and 3) elucidate roles for non-coding RNA genes during the replication stress Response. Completion of these research projects will grant us significant and fundamental novel insights into how cellular genomes are maintained in the face of damaging insults, grant us improved mechanistic understanding of the principles of cancer pathogenesis in greater detail and open up novel avenues for exploiting defective DNA repair processes in the treatment of cancers.