miR-31a-5p promotes postnatal cardiomyocyte proliferation by targeting RhoBTB1

The discovery of a short RNA that promotes cardiac muscle growth could lead to new strategies for repairing heart damage. Mammalian heart muscle stops proliferating shortly after birth, but scientists are looking for ways to reactivate this capacity in adult tissue. Researchers led by Xiangqing Kong and Xinli Li from the First Affiliated Hospital of Nanjing Medical University, China, have now linked heart muscle growth to miR-31a-5p, a tiny RNA that regulates the activity of other genes. They demonstrated that excess miR-31a-5p promotes division of rat heart muscle and its depletion inhibits proliferation. Subsequent experiments in cultured cells and newborn rats suggest that miR-31a-5p acts by inhibiting a protein previously shown to halt tumor cell proliferation. If this pathway truly regulates regeneration in the adult heart, it could be exploited to repair damage from cardiovascular disease.