Abstract
Within the first month of human gestation, the heart begins to contract, even though it is still undergoing morphogenesis, including the development of valves to promote proper blood flow. Thus, the heart is subjected to mechanical forces throughout development, but whether mechanical forces instruct morphogenesis has remained unknown. Although mechanoresponsive factors have been identified, it is challenging to directly interrogate the role of mechanical inputs during cardiogenesis and to decipher how such forces are transduced into molecular signals in vivo (1). Mechanoregulation of cardiac development is clinically relevant because diminished blood flow is thought to contribute to the pathogenesis of hypoplastic left heart syndrome, a congenital heart disease associated with valve abnormalities (2). On page 351 of this issue, Fukui et al. (3) show how mechanical forces are sensed by endocardial cells (the layer of endothelial cells lining the inside of the heart) to direct cardiac valve formation in zebrafish.
