PCP and Septins govern the polarized organization of the actin cytoskeleton during convergent extension

Summary Actin is generally required for cell movement but must be brought under the control of distinct developmental systems to drive specific morphogenetic processes, such as convergent extension (CE) 1 . This evolutionarily conserved collective cell movement elongates the body axis of all vertebrates and is governed by the Planar Cell Polarity (PCP) signaling system 1,2 . Here, we sought to understand the interplay of PCP and actin during Xenopus CE. Our data provide new insights into the organization and emergence of polarity in this network and reveal new roles for the actin organizing Septins 3 , thereby shedding light on the mechanisms by which developmental signaling systems exploit the ubiquitous machinery of cells to drive morphogenesis.