Membrane and actin dynamics interplay at lamellipodia leading edge.

The multimolecular WAVE regulatory (WRC) and Arp2/3 complexes are primarily responsible to generate pushing forces at migratory leading edges by promoting branch elongation of actin filaments. The architectural complexity of these units betrays the necessity to impose a tight control on their activity. This is exerted through temporally coordinated and coincident signals which limit the intensity and duration of this activity. In addition, interactions of the WRC and Arp2/3 complexes with membrane binding and surprisingly membrane trafficking proteins is also emerging, revealing the existence of an 'endocytic wiring system' that spatially restrict branched actin elongation for the execution of polarized functions during cell migration.