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

项目摘要 基因组完整性受损会导致几种衰弱的疾病，例如 神经退行性疾病、自身免疫性疾病和癌症。持久性核酸 含有带有置换的单链DNA(R-环)的RNA-DNA杂交物的结构是 基因组不稳定的潜在来源。R环的主要来源之一是调节受损 蛋白质编码基因转录终止点的RNA聚合酶II(RNAPII)。在……里面 人类，5‘-3’-外切核糖核酸酶2(XRN2)是全基因组适时终止 Poly(A)位点下游的RNAPII。从本质上讲，XR2的S在核糖核酸代谢中的作用是好的 明白了。然而，它在基因组维持中的作用仍然难以捉摸，而且缺乏 关于其在协调DNA修复、分解过程中的分子贡献的功能信息 复制应激，并促进细胞存活。我们的长期研究目标是确定这些角色 包括XRN2在内的转录终止因子在防止R-环诱导基因组中的作用 并找出针对其脆弱性的途径。对于这个研究项目，我们将 主要研究XRN2与DEAD(Asp-Glu-Ala-Asp)Box解旋酶的相互作用 23(DDX23)。我们最近定义了XRN2的相互作用体，并确定了 与染色体的DNA双链断裂(DSB)修复和细胞周期调控有关 复制。我们的数据支持XRN2和DDX23的相互作用以及这两者之间的潜在相互作用 R环代谢和基因组维持中的酶。我们假设XRN2-DDX23 相互作用使它们能够协同抑制R-环诱导的基因组不稳定和 这些酶的缺陷与中心DNA损伤感受器蛋白聚(ADP-核糖)有关 聚合酶1(PARP1)对R环受损的DSB的协调修复作用 动态平衡。我们将追求以下具体目标来验证我们的假设；目标1：确定 XRN2和DDX23相互作用的生化基础和功能意义。目标2：确定 XRN2-DDX23在R环代谢和基因组中相互作用的生物学意义 维修。总而言之，我们的研究将提供对XRN2-DDX23的机械性见解 合作避免R环导致的基因组不稳定，并建立潜在的途径 瞄准XRN2和DDX23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.