DIAPH3 condensates formed by liquid-liquid phase separation act as a regulatory hub for stress-induced actin cytoskeleton remodeling
Ke Zhang, Miaodan Huang, Ang Li, Jing Wen, Lingli Yan, Yunhao Li, Liman Guo, Kumaran Satyanarayanan Senthil, Yangyang Zhou, Guobing Chen, Yong Liu, Xiaofei Zhang, Xiaoli Yao, Dajiang Qin, Huanxing Su
Abstract
Membraneless condensates, such as stress granules (SGs) and processing bodies (P-bodies), have attracted wide attention due to their unique feature of rapid response to stress without first requiring nuclear feedback. In this study, we identify diaphanous-related formin 3 (DIAPH3), an actin nucleator, as a scaffold protein to initiate liquid-liquid phase separation (LLPS) and form abundant cytosolic phase-separated DIAPH3 granules (D-granules) in mammalian cells such as HeLa, HEK293, and fibroblasts under various stress conditions. Neither mRNAs nor known stress-associated condensate markers, such as G3BP1, G3BP2, and TIA1 for SGs and DCP1A for P-bodies, are detected in D-granules. Using overexpression and knockout of DIAPH3, pharmacological interventions, and optogenetics, we further demonstrate that stress-induced D-granules spatially sequester DIAPH3 within the condensation to inhibit the assembly of actin filaments in filopodia. This study reveals that D-granules formed by LLPS act as a regulatory hub for actin cytoskeletal remodeling in response to stress.