ErbB2 drives Yap activation during cardiac regeneration

Cardiomyocyte (CM) loss after injury results in adverse remodelling and fibrosis, which inevitably lead to heart failure. Neuregulin-ErbB2 and Hippo-Yap signaling pathways are key mediators of CM proliferation and regeneration although the crosstalk between these pathways is unclear. Here, we demonstrate in mice that temporal over-expression (OE) of activated ErbB2 in CMs promotes cardiac regeneration in a heart failure model. Cellularly, OE CMs present an EMT-like regenerative response involving cytoskeletal reprograming, migration, ECM turnover, and displacement. Molecularly, we identified Yap as a critical mediator of ErbB2 signaling. In OE CMs, Yap interacts with nuclear envelope and cytoskeletal components, reflective of the altered mechanic state elicited by ErbB2. Hippo-independent activating phosphorylation on Yap at S352 and S274 were enriched in OE CMs, peaking during metaphase. Viral overexpression of Yap phospho-mutants dampened the proliferative competence of OE CMs. Taken together, we demonstrate a potent ErbB2-mediated Yap mechanosensory signaling involving EMT-like characteristics, resulting in heart regeneration.