Ubiquitin assisted phase separation of Dishevelled-2 promotes Wnt signaling.

Dishvelled-2 (Dvl2) is an essential component of Wnt pathway, which controls several cell fate decisions during development such as proliferation, survival and differentiation. Dvl2 forms higher-order protein assemblies in cell that are critical for relaying the signal from upstream Wnt ligand-Frizzled receptor binding to downstream effector β-catenin activation. However, the precise molecular nature and contribution of Dvl2 protein assemblies during Wnt signaling is unknown. Here, we show that Dvl2 forms protein condensates driven by liquid-liquid phase separation. An intrinsically disordered region (IDR) on the N-terminus is essential for Dvl2 phase separation. Importantly, we identified a HECT-E3 ligase WWP2 as an essential driver of Dvl2 phase separation in vitro and in cells. We demonstrated that ubiquitination of Dvl2 through K63 linkage by WWP2 is required for formation of Dvl2 condensates. Phase separated Dvl2 activates Wnt signaling by sequestering the components of destruction complex and thus relieving β-catenin. Together, our results reveal a ubiquitination-dependent liquid-liquid phase separation as a new identity for Dvl2 in cells, which is necessary for transduction of Wnt signaling.