Dead cells get the squeeze

Mzacrophages can clean up the detritus of dying cells. But that, say Jody Rosenblatt, Martin Raff, and Louise Cramer (University College London, London, UK), is not the whole story. They have found that cells undergoing apoptosis in an epithelial sheet signal to their neighbors to begin squeezing, in a process that maintains the barrier function of the epithelium while extruding the dying cell. Macrophages may come along only after the dying cell is liberated from its neighbors.

Rosenblatt noticed the squeezing when she was looking at wound healing in epithelial sheets. The fate of apoptosing cells “looked very similar,” she says. In retrospect, she noticed that the literature included accounts of cell sloughing in the gut, and possible cell extrusion in developing fly embryos. “But at the most it would be one sentence in...