2021-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/709473哺乳動物細胞依靠去氧核醣核酸損傷反應(DDR)來避免基因體不穩定性發生-此 為癌症的一大特性。儘管ATM-Chk2途徑主要負責去氧核醣核酸雙股斷裂 (DSB)訊息傳遞與修補，ATR-Chk1訊息路徑在DDR中扮演中心角色，透過協調 細胞週期檢查點和去氧核醣核酸修復來抵抗複製壓力和各種去氧核醣核酸的損傷。 R環是轉錄過程的核醣核酸 /去氧核醣核酸雜合體的結構，R環的持久存在會傷害基 因體穩定性，並與人類疾病產生相關。DHX9是一種多功能蛋白，對解決R環，核 醣核酸加工和保護基因體完整性很重要，並已知道在去氧核醣核酸損傷反應有其角 色。然而，DHX9和DDR之間相互關係的潛在機制尚不清楚。我們首次證實在去氧 核醣核酸損傷脅迫下，DHX9對於ATR-Chk1信號轉導活化是不可缺少的。此外 ，我們證實DHX9會被ATR磷酸化，以應對會造成去氧核醣核酸損傷的脅迫。更有 趣的是，表達DHX9突變體的細胞在沒有外源性損傷的情況下會出現去氧核醣核酸 雙股斷裂。綜合以上初步發現，我們假設:1)DHX9對ATR-Chk1訊息路徑很重要 並參與其調控; 2)DHX9磷酸化對於基因體穩定性和核醣核酸加工可能具有生理 調控意義。本研究旨在闡明DHX9和ATR-Chk1訊息路徑協同調節R環、去氧核醣核 酸孫傷訊息傳遞和核醣核酸加工的調控機制，終而維持基因體的穩定。 "Mammalian cells rely on the DNA damage response (DDR) to prevent genome instability, a hallmark of cancer. While the ATM-Chk2 pathway is mainly responsible for the DNA double-stranded breaks (DSBs), the ATR-Chk1 signaling plays a central role in the DDR to counteract replication stress and various DNA lesions by coordinating cell cycle checkpoints and DNA repair. R-loops are structures of RNA/DNA hybrids arisen from transcription, and the persistence of R-loops is detrimental to genomic stability and linked to the pathology of human diseases. DHX9, a multi-function protein important for resolving R-loops, RNA processing, and protecting genome integrity, has been shown to have a role in the DDR. However, the underlying mechanism of the interrelationship between DHX9 and the DDR is not fully clear. We, for the first time, identified DHX9 as an indispensable factor for the ATR-Chk1 signaling under genotoxic stress. Further, we confirmed that DHX9 is phosphorylated by ATR in response to genotoxic stress. More interestingly, cells expressing DHX9 mutants result in increase DNA DSBs in the absence of exogenous insults. Together, we hypothesize that i) DHX9 is important for activation or regulation of the ATR-Chk1 signaling pathway; ii) DHX9 phosphorylation may have regulatory roles in genome stability and RNA processing. This research proposal aims to elucidate the underlying mechanisms by which DHX9 and the ATR-Chk1 signaling cooperate to regulate R-loops, DNA damage signaling, and RNA processing, thus preventing genomic instability. 計畫概述"去氧核醣核酸損傷反應R環核醣核酸解旋&#37238基因體穩定性核酸修復ATRChk1DHX9R-loopsgenome stabilityreplication stress