Cell motility involves the formation of locally restricted membrane protrusions and invaginations. These shape changes are controlled by cytoskeletal remodelling, which is driven by cycles of actin polymerization and depolymerization. Recent evidence suggests that actin-crosslinking or -bundling proteins might help to control actin dynamics. On , Evelyne Friederich and co-workers add to this evidence by showing that the actin-crosslinking protein T-plastin increases actin-based force generation and stabilizes actin structures. Beads coated with the VCA domain of the Wiskott/Aldrich syndrome protein (WASP) recruit the actin-nucleating Arp2/3 complex, form polymerized actin comets at their surface, and move in cell-free extracts. The authors show that both intact T-plastin and its first actin-binding domain, which binds but does not bundle actin, increase the velocity of such beads and stabilize actin comets. Additional assays confirm these findings and lead the authors to propose that T-plastin controls actin turnover independently of crosslink formation. This newly discovered activity of T-plastin may contribute to actin cytoskeleton assembly and maintenance of plasma membrane protrusions in vivo.
