GSE193861
Transcriptional co-activators YAP1-TAZ of Hippo signalling in doxorubicin-induced cardiomyopathy
Aims: Hippo signalling is an evolutionarily conserved pathway that controls organ size by regulating apoptosis, cell proliferation and stem cell self-renewal. Recently, the pathway has been shown to exert powerful growth regulatory activity in cardiomyocytes. However, the functional role of this stress- and cell death-related pathway in the human heart and cardiomyocytes is not known. In this study, we investigated the role of the transcriptional co-activators of Hippo signalling, YAP and TAZ, in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) in response to cardiotoxic agents and investigated the effects of modulating the pathway on cardiomyocyte function and survival. Methods and Results: RNA sequencing analysis of human heart samples with doxorubicin-induced end-stage heart failure and healthy controls showed YAP and ERBB2 (HER2) as upstream regulators of differentially expressed genes correlated with doxorubicin treatment. Thus, we tested the effects of doxorubicin and/or small molecule inhibitor lapatinib on hiPSC-CM in vitro . Using an automated high contentscreen of 96 clinically relevant chemotherapeutic drugs, we showed that doxorubicin induced the highest activation of YAP/TAZ nuclear translocation in both hiPSC-CM and  control MCF7 breast cancer cells. The overexpression of YAP rescued doxorubicin- induced cell loss in hiPSC-CM by inhibiting apoptosis and inducing proliferation. In  contrast, silencing of YAP and TAZ by siRNAs resulted in elevated mitochondrial membrane potential loss in response to doxorubicin. Human iPSC-CM calcium transients did not change in response to YAP/TAZ silencing. Conclusions: Our results suggest that Hippo signalling is involved in clinical anthracycline-induced cardiomyopathy. Modelling with hiPSC-CM in vitro showed similar responses to doxorubicin as adult cardiomyocytes and revealed a potential cardioprotective effect of YAP in doxorubicin-induced cardiotoxicity. Overall design: 5 left ventricular