Make junction, will travel

Cadherin-based adhesion complexes can trigger actin assembly, according to a proposal from Eva Kovacs, Alpha Yap, and colleagues (University of Queensland, Brisbane, Australia). The actin assembly may, in turn, control how cells recognize and move over one another.

Kovacs and Yap began their study by observing cells moving over a substrate covered with E-cadherin. They noticed that clumps of E-cadherin colocalized with both filamentous actin and components of the actin-nucleating Arp2/3 complex. Similar colocalization was apparent upon addition of E-cadherin beads. Finally, E-cadherin coimmunoprecipitated with Arp2/3 components, even in the presence of the actin-depolymerizing drug cytochalasin D.

The association suggests that cadherin ligation might trigger actin assembly by Arp2/3. “What we'd like to correct,” says Yap, “is the notion that cadherin complexes are solely binding to preformed actin filaments.” In his view, the adhesion machinery is no...