Heat stress activates YAP/TAZ to induce the heat shock transcriptome

The Hippo pathway plays critical roles in cell growth, differentiation, organ development, and tissue homeostasis whereas its dysregulation can lead to tumorigenesis. YAP/TAZ are transcription co-activators and represent the main downstream effectors of the Hippo pathway. Here we show that heat stress induces a strong and rapid YAP dephosphorylation and activation. The effect of heat shock on YAP is dominant to other signals known to modulate the Hippo pathway. Heat shock inhibits LATS kinase by promoting HSP90-dependent LATS interaction with and inactivation by PP5 phosphatase. Heat shock also induces LATS ubiquitination and degradation. YAP/TAZ are crucial for cellular heat shock responses, including the heat shock transcriptome and cell viability. This study uncovers previously unknown mechanisms of Hippo regulation by heat shock as well as physiological functions of YAP in heat stress response. Our observations also reveal a potential combinational therapy involving hyperthermia and targeting of the Hippo pathway.