Hippo signalling regulates the nuclear behaviour and DNA dwell times of YAP and TEAD to control transcription

Over the past two decades, genetic and proteomic screens have enabled the discovery and elucidation of the Hippo pathway as a complex signalling network that controls tissue growth and cell fate and which is of major importance for human cancers. Despite these advances, our understanding of how Hippo signalling regulates transcription is less clear. To address this, we used live microscopy approaches to study the nuclear behaviour of the major transcription effectors of the human Hippo pathway, YAP and TEADs. Our experiments revealed that TEADs are a major determinant of YAPs nuclear biophysical behaviour, whilst YAP only has a minor influence on TEAD behaviour. Acute chemical inhibition of Hippo signalling stimulated an increase in the DNA residence time of both YAP and TEAD1. Consistently, YAP and TEAD1 bound DNA for longer periods in cells with high intrinsic YAP/TEAD activity (induced trophoblast stem cells) than in cells with low intrinsic YAP/TEAD activity (induced pluripotent stem cells). TEAD1 bound the genome on a broad range of timescales, and this is extended substantially in nuclear condensates. Finally, single molecule tracking experiments revealed that a fusion protein encoded by a cancer-associated YAP allele exhibits substantially different nuclear biophysical behaviour than either YAP or TEAD1. These live microscopy experiments reveal that Hippo signalling regulates transcription at least in part by influencing the DNA dwell times of both YAP and TEAD.