Focal adhesion (FA) dynamics influence cell motility in morphogenesis, cancer progression and immune responses. The factors that regulate FA dynamics are numerous and complex, and include members of the F-actin-binding coronin family of proteins. On , James Bear and colleagues now investigate the role of coronin 2A, a type-II coronin that was functionally uncharacterised, in regulating FA dynamics. They first show that, unlike type-I coronins (which localise to the leading edge of cells), coronin 2A localises to internal FAs and is not present in lamellipodia. Furthermore, coronin-2A-depleted cells migrate more slowly than control cells owing to a 50% decrease in the disassembly rate of internal FAs. But how is this effect mediated at the molecular level? The authors go on to show that coronin 2A affects FA dynamics through cofilin, which – despite its well-known role in regulating actin dynamics – has not previously been shown to directly regulate FA turnover. On the basis of these findings, the authors propose a new role for coronin 2A in enhancing the disassembly of a subset of FAs by activating the actin-severing activity of cofilin. As coronin 2A is also shown to physically interact with the cofilin-activating phosphatase Slingshot-1L, they suggest that coronin 2A might regulate cofilin activity via Slingshot-1L.
