Regulation of YAP activity by nuclear G-actin binding.

The Yes-associated protein YAP belongs to the TEAD (TEA/ATTS domain) transcriptional co-activators that shuttle between the cytoplasm and the nuclear compartment. YAP and its paralog TAZ (transcriptional co-activator with PDZ-binding motif) play essential roles in the Hippo pathway to control tissue and organ size. In addition, YAP is critically involved in numerous cellular processes such as differentiation, proliferation, cell migration, and cancer metastasis, as well as mechanotransduction and cytoskeletal dynamics. The actin cytoskeleton controls YAP activity in multiple ways via tensile forces, cell density and cell-cell adhesion as well as shear stress or other biomechanical cues. Here we discover YAP as a novel G-actin binding protein. We identify three high-affinity YAP actin binding sites involving critical residues within the N-terminus of YAP. Moreover, actin binding to YAP is necessary for its transcriptional activity and function, such as during cell density control. Mutation of the three actin-binding residues results in a loss of nuclear YAP co-activator function towards TEAD, while actin binding to YAP is required for TEAD target gene regulation. Our data point towards the formation of a dynamic TEAD/YAP/actin ternary complex necessary for transcription.