Poised to migrate

Epithelial cells are ready to run off at any moment, at least based on the results of Olga Speck, Richard Fehon (Duke University, Durham, NC), and colleagues. They have found that moesin, previously thought to be a stolid structural component, is actually a signaling protein that maintains epithelial cell identity by suppressing Rho activity.

Ezrin, radixin, and moesin (ERM)—represented only by Moesin in flies—are proteins that link actin to various transmembrane proteins at the apical surface of epithelial cells. The link was thought to help maintain epithelial structures such as microvilli, but Fehon's group found that flies lacking Moesin had epithelial cells that lost polarity, dropped out of monolayers, and migrated invasively.

Moesin appears to act by suppressing Rho. Interfering with ERM proteins in mammalian epithelial cells boosted Rho activity, and fly...