DHX9 SUMOylation is required for the suppression of R-loop-associated genome instability

• Published in: Nature communications Vol. 15; no. 1; pp. 6009 - 18
• Main Authors: Yang, Bing-Ze, Liu, Mei-Yin, Chiu, Kuan-Lin, Chien, Yuh-Ling, Cheng, Ching-An, Chen, Yu-Lin, Tsui, Li-Yu, Lin, Keng-Ru, Chu, Hsueh-Ping Catherine, Wu, Ching-Shyi Peter
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 17.07.2024; Nature Publishing Group UK; Nature Portfolio
• Subjects: Cell death; Damage prevention; DEAD-box RNA Helicases - genetics; DEAD-box RNA Helicases - metabolism; Deoxyribonucleic acid; DNA; DNA Damage; DNA helicase; Genomes; Genomic Instability; Genotoxic chemicals; Genotoxicity; HEK293 Cells; Humans; Lysine; Lysine - metabolism; Mutants; Mutation; Neoplasm Proteins; Poly (ADP-Ribose) Polymerase-1 - genetics; Poly (ADP-Ribose) Polymerase-1 - metabolism; Poly(ADP-ribose) polymerase; Protein interaction; Proteins; R-Loop Structures; R-loops; Regulatory mechanisms (biology); Ribonuclease H; Ribonucleic acid; RNA; RNA helicase; Small Ubiquitin-Related Modifier Proteins - genetics; Small Ubiquitin-Related Modifier Proteins - metabolism; Stability; SUMO protein; Sumoylation
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-50428-4

RNA 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.