Cardiomayocyte specific translating RNA sequencing from mice in heart failure

Mammalian organs vary widely in regenerative capacity, and poorly regenerative organs, such as the heart are particularly vulnerable to organ failure. Once established, heart failure commonly results in in considerable mortality and early demise. The Hippo pathway, a kinase cascade that prevents adult cardiomyocyte proliferation and regeneration, is upregulated in human heart failure. We show that deletion of the Hippo pathway component Salvador (Salv) in mouse hearts with established ischemic heart failure after myocardial infarction induced a reparative genetic program characterized by increased scar border vascularity, reduced fibrosis, and recovery of pumping function to that of sham-operated controls. To isolate cardiomyocyte specific translating mRNA we used TRAP (translating ribosomal affinity purification) followed by RNA sequencing. Hippo deficient cardiomyocytes had increased expression of proliferative, and stress response genes. Interestingly the mitochondrial quality control gene, Park2 was among the stress response genes. Further genetic studies indicated that Park2 was essential for heart repair in both the neonatal mouse and the adult Salv conditional knockout mouse. Thus, suggesting a requirement for mitochondrial quality control in the regenerating myocardium. Our findings indicate that the failing heart has a previously unrecognized capacity for repair involving more than cardiomyocyte renewal.