Profilin is an effector for Daam 1 in non-canonical Wnt signaling and is required for vertebrate gastrulation

Non-canonical Wnt signaling plays important roles during vertebrate embryogenesis and is required for cell motility during gastrulation. However, the molecular mechanisms of how Wnt signaling regulates modification of the actin cytoskeleton remain incompletely understood. We had previously identified the Formin homology protein Daam 1 as an important link between Dishevelled and the Rho GTPase for cytoskeletal modulation. Here, we report that Profilin 1 is an effector downstream of Daam 1 required for cytoskeletal changes. Profilin 1 interacted with the FH1 domain of Daam 1 and was localized with Daam 1 to actin stress fibers in response to Wnt signaling in mammalian cells. In addition, depletion of Profilin 1 inhibited stress fiber formation induced by non-canonical Wnt signaling. Inhibition or depletion of Profilin 1 in vivo specifically inhibited blastopore closure in Xenopus but did not affect convergent extension movements, tissue separation or neural fold closure. Our studies define a molecular pathway downstream of Daam 1 that controls Wnt-mediated cytoskeletal reorganization for a specific morphogenetic process during vertebrate gastrulation.