Stretched divisions

Abstract

Many organ surfaces are covered by a protective epithelial-cell layer. It emerges that such layers are maintained by cell stretching that triggers cell division mediated by the force-sensitive ion-channel protein Piezo1. See Letter p.118 Epithelial cell layers serve as barriers for the organs they cover, yet they continuously undergo cell division and cell death. So how do these dynamic processes avoid compromising the barrier function of epithelia? Jody Rosenblatt and colleagues previously reported in Nature that when epithelial cells become too crowded they trigger the stretch-activated channel Piezo1 to effect extrusion of cells that later die. They now ask how epithelia deal with the opposite situation—cell death. It emerges that, following cell death, the low density of surrounding cells also activate Piezo1, driving cell division to rebalance the cell numbers. The authors provide insights into the molecular mechanism through which stretch triggers cell division, and propose that whether Piezo1 signals for cell division or cell extrusion depends on the type of mechanical forces that it experiences.