Yang, Bing-ZeBing-ZeYangLiu, Mei-YinMei-YinLiuChiu, Kuan-LinKuan-LinChiuChien, Yuh-LingYuh-LingChienCheng, Ching-AnChing-AnChengChen, Yu-LinYu-LinChenTsui, Li-YuLi-YuTsuiLin, Keng-RuKeng-RuLinChu, Hsueh-Ping CatherineHsueh-Ping CatherineChuCHING-SHYI WU2024-10-152024-10-152024-12https://scholars.lib.ntu.edu.tw/handle/123456789/722047RNA helicase DHX9 is essential for genome stability by resolving aberrant R-loops. However, its regulatory mechanisms remain unclear. Here we show that SUMOylation at lysine 120 (K120) is crucial for DHX9 function. Preventing SUMOylation at K120 leads to R-loop dysregulation, increased DNA damage, and cell death. Cells expressing DHX9 K120R mutant which cannot be SUMOylated are more sensitive to genotoxic agents and this sensitivity is mitigated by RNase H overexpression. Unlike the mutant, wild-type DHX9 interacts with R-loop-associated proteins such as PARP1 and DDX21 via SUMO-interacting motifs. Fusion of SUMO2 to the DHX9 K120R mutant enhances its association with these proteins, reduces R-loop accumulation, and alleviates survival defects of DHX9 K120R. Our findings highlight the critical role of DHX9 SUMOylation in maintaining genome stability by regulating protein interactions necessary for R-loop balance.en[SDGs]SDG3journal article10.1038/s41467-024-50428-439019926