Mammalian cardiac regeneration is greatly impeded by the massive loss of cardiomyocytes that occurs following acute injury. The failure of the remaining cells to proliferate is a considerable challenge for the field, but the molecular mechanisms that control cardiomyocyte proliferation in the adult heart are largely unknown. Now, on , James Martin and colleagues demonstrate a role for Hippo signalling in suppressing adult and postnatal murine cardiomyocyte proliferation. Using conditional knockouts, the authors show that removal of Hippo pathway members Salv or Lats1 and Lats2 from normal adult cardiomyocytes results in increased proliferation, as these cells are able to re-enter the cell cycle and undergo cytokinesis. Moreover, removal of Salv from cardiomyocytes in vivo results in improved cardiac regeneration after adult myocardial infarction, a time when regeneration is usually severely impaired. Here, the authors observed reduced scarring and full restoration of cardiac function. This elegant study suggests that Hippo signalling is a repressor of adult cardiomyocyte renewal and regeneration.
