Membrane-proximal F-actin restricts local membrane protrusions and directs cell migration

Actin cortex controls cell migration Cell migration is mainly controlled by local actin polymerization–driven membrane protrusion. However, a second structural mechanism might also regulate membrane protrusions and directed migration: changes in the density of the attachment between the plasma membrane and the underlying F-actin cortex, a parameter related to membrane tension. Many types of attachment and signaling mechanisms are known to alter the density of membrane-proximal cortical actin. Bisariaet al. designed a membrane-proximal F-actin (MPA) reporter that could directly measure local changes in the density of MPA in living cells. Levels of MPA were surprisingly low toward the front of migrating cells despite an opposing high overall concentration of F-actin in the same front region. The researchers propose that MPA density can integrate different signaling processes to direct local membrane protrusions and stabilize cell polarity during cell migration.Science , this issue p.1205