FUS-dependent liquid-liquid phase separation is important for DNA repair initiation

• Published in: The Journal of cell biology Vol. 220; no. 5; p. 1
• Main Authors: Levone, Brunno R, Lenzken, Silvia C, Antonaci, Marco, Maiser, Andreas, Rapp, Alexander, Conte, Francesca, Reber, Stefan, Mechtersheimer, Jonas, Ronchi, Antonella E, Mühlemann, Oliver, Leonhardt, Heinrich, Cardoso, M Cristina, Ruepp, Marc-David, Barabino, Silvia M L
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 03.05.2021
• Subjects: Biochemistry; Cell Line; Cell Line, Tumor; Damage; Deoxyribonucleic acid; DNA; DNA biology; DNA damage; DNA Damage - genetics; DNA repair; DNA Repair - genetics; HEK293 Cells; HeLa Cells; Humans; Liquid phases; Metabolism; Phase separation; Protein Binding - genetics; Protein Domains - genetics; Relocation; Repair; Ribonucleic acid; RNA; RNA-binding protein; RNA-Binding Protein FUS - genetics; RNA-Binding Proteins - genetics
• ISSN: 0021-9525; 1540-8140; 1540-8140
• DOI: 10.1083/jcb.202008030

RNA-binding proteins (RBPs) are emerging as important effectors of the cellular DNA damage response (DDR). The RBP FUS is implicated in RNA metabolism and DNA repair, and it undergoes reversible liquid-liquid phase separation (LLPS) in vitro. Here, we demonstrate that FUS-dependent LLPS is necessary for the initiation of the DDR. Using laser microirradiation in FUS-knockout cells, we show that FUS is required for the recruitment to DNA damage sites of the DDR factors KU80, NBS1, and 53BP1 and of SFPQ, another RBP implicated in the DDR. The relocation of KU80, NBS1, and SFPQ is similarly impaired by LLPS inhibitors, or LLPS-deficient FUS variants. We also show that LLPS is necessary for efficient γH2AX foci formation. Finally, using superresolution structured illumination microscopy, we demonstrate that the absence of FUS impairs the proper arrangement of γH2AX nanofoci into higher-order clusters. These findings demonstrate the early requirement for FUS-dependent LLPS in the activation of the DDR and the proper assembly of DSB repair complexes.