Intercalated disc protein Xinβ is required for Hippo-YAP signaling in the heart

Intercalated discs (ICD), specific cell-to-cell contacts that connect adjacent cardiomyocytes, ensure mechanical and electrochemical coupling during contraction of the heart. Mutations in genes encoding ICD components are linked to cardiovascular diseases. Here, we show that loss of Xin beta, a newly-identified component of ICDs, results in cardiomyocyte proliferation defects and cardiomyopathy. We uncovered a role for Xin beta in signaling via the Hippo-YAP pathway by recruiting NF2 to the ICD to modulate cardiac function. In Xin beta mutant hearts levels of phosphorylated NF2 are substantially reduced, suggesting an impairment of Hippo-YAP signaling. Cardiac-specific overexpression of YAP rescues cardiac defects in Xin beta knock-out mice-indicating a functional and genetic interaction between Xin beta and YAP. Our study reveals a molecular mechanism by which cardiac-expressed intercalated disc protein Xin beta modulates Hippo-YAP signaling to control heart development and cardiac function in a tissue specific manner. Consequently, this pathway may represent a therapeutic target for the treatment of cardiovascular diseases. Intercalated discs ensure mechanical and electrochemical coupling during contraction of the heart. Here, the authors show that loss of Xin beta results in cardiomyocyte proliferation defects and cardiomyopathy by influencing the Hippo-YAP signalling pathway, thus affecting cardiac development and function.