XRN2-DDX23 Cooperation in Avoiding R-loop-induced Genomic Instability

项目摘要 受损的基因组完整性导致几种使人衰弱的疾病，例如 神经退行性疾病、自身免疫性疾病和癌症。持久核酸 含有带有置换单链DNA（R环）的RNA-DNA杂交体的结构是一种 基因组不稳定性的潜在来源。R环的主要来源之一是调节受损 RNA聚合酶II（RNAPII）在蛋白质编码基因的转录终止位点。在 在人类中，5 '-3'-核糖核酸外切酶2（XRN 2）对于全基因组及时终止 多聚腺苷酸位点下游的RNAPII。从本质上讲，XRN 2在RNA代谢中的作用是很好的。 明白然而，它在基因组维持中的作用仍然难以捉摸， 关于其在协调DNA修复、解决 复制应激和促进细胞存活。我们的长期研究目标是定义 包括XRN 2在内的转录终止因子在阻止R环诱导的基因组 不稳定并确定针对其脆弱性的途径。对于这个研究项目，我们将 主要集中于描述XRN 2和DEAD（Asp-Glu-Ala-Asp）Box解旋酶的相互作用 23（DDX23）。我们最近定义了XRN 2的相互作用组，并确定了 将其与DNA双链断裂（DSB）修复和染色体的细胞周期调控联系起来， 复制的我们的数据支持XRN 2和DDX 23的相互作用以及这两者的潜在相互作用 酶在R环代谢和基因组维护中的作用。我们假设XRN 2-DDX 23 相互作用使它们能够协同抑制R环诱导的基因组不稳定性， 这些酶的缺乏会使中央DNA损伤传感蛋白聚（ADP-核糖） 聚合酶1（PARP 1）协调修复从受损的R环发出的DSB 体内平衡我们将追求以下具体目标来测试我们的假设：目标1：确定 XRN 2和DDX 23相互作用的生化基础和功能意义。目标2：确定 XRN 2-DDX 23相互作用在R环代谢和基因组中生物学意义 上维护总的来说，我们的研究将提供对XRN 2-DDX 23的机制见解。 合作避免R环诱导的基因组不稳定性，并建立潜在的途径， 针对XRN 2和DDX 23漏洞。

Project Summary Compromised genomic integrity results in several debilitating diseases such as neurodegenerative disorders, autoimmune diseases, and cancer. Persistent nucleic acid structures containing RNA-DNA hybrids with a displaced single-stranded DNA (R-loops) are a potent source of genomic instability. One of the major sources of R-loops is impaired regulation of RNA polymerase II (RNAPII) at transcription termination sites of protein coding genes. In humans, the 5’-3’-exoribonuclease 2 (XRN2) is essential for genome-wide timely termination of RNAPII downstream of poly(A) sites. In essence, XRN2’s role in RNA metabolism is well understood. However, its role in genome maintenance remains elusive and there is lack of functional information regarding its molecular contributions in coordinating DNA repair, resolving replication stress, and promoting cell survival. Our long-term research goal is to define the roles of transcription termination factors including XRN2, in preventing R-loop-induced genomic instability and identify avenues to target their vulnerabilities. For this research program, we will primarily focus on delineating the interplay of XRN2 and DEAD (Asp-Glu-Ala-Asp) Box helicase 23 (DDX23). We recently defined the interactome of XRN2 and identified molecular links that connect it to DNA double-strand break (DSB) repair and cell cycle control of chromosomal replication. Our data support XRN2 and DDX23 interaction and a potential interplay of these two enzymes in R-loop metabolism and genome maintenance. We hypothesize that XRN2-DDX23 interaction enables them to cooperatively suppress R-loop-induced genomic instability and deficiencies of these enzymes engage central DNA damage sensor protein poly(ADP-ribose) polymerase 1 (PARP1) to coordinate repair of DSBs emanating from impaired R-loop homeostasis. We will pursue following specific aims to test our hypothesis; Aim 1: Determine the biochemical basis and functional implications of XRN2 and DDX23 interaction. Aim 2: Determine the biological significance of XRN2-DDX23 interplay in R-loop metabolism and genome maintenance. Collectively, our studies will provide mechanistic insights into XRN2-DDX23 cooperation in avoiding R-loop-induced genomic instability, and establish potential avenues for targeting XRN2 and DDX23 vulnerabilities.