Epicardial CCM2 Promotes Cardiac Development and Repair Via its Regulation on Cytoskeletal Reorganization.

The epicardium provides epicardial-derived cells and molecular signals to support cardiac development and regeneration. Zebrafish and mouse studies have shown that , a cerebral cavernous malformation disease gene, is essential for cardiac development. Endocardial cell-specific deletion of in mice has previously established that Ccm2 is essential for maintenance of the cardiac jelly for cardiac development during early gestation. The current study aimed to explore the function of Ccm2 in epicardial cells for heart development and regeneration. Through genetic deletion of in epicardial cells, our in vivo and ex vivo experiments revealed that is required by epicardial cells to support heart development. Ccm2 regulates epicardial cell adhesion, cell polarity, cell spreading, and migration. Importantly, the loss of in epicardial cells delays cardiac function recovery and aggravates cardiac fibrosis following myocardial infarction. Molecularly, Ccm2 targets the production of cytoskeletal and matrix proteins to maintain epicardial cell function and behaviors. Epicardial Ccm2 plays a critical role in heart development and regeneration via its regulation of cytoskeleton reorganization.