[Elife. ]Robo recruitment of the Wave Regulatory Complex plays an essential and conserved role in midline repulsion

Robo recruitment of the Wave Regulatory Complex plays an essential and conserved role in midline repulsion Elife. 2021 Apr 12;10:e64474. doi: 10.7554/eLife.64474. Online ahead of print. Authors Karina Chaudhari 1 , Madhavi Gorla 1 , Chao Chang 2 , Artur Kania 2 , Greg J Bashaw 1 Affiliations 1 Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States. 2 Anatomy and Cell Biology, Institut de recherches cliniques de Montréal (IRCM), Montreal, Canada. PMID: 33843588 DOI: 10.7554/eLife.64474 Abstract The Roundabout (Robo) guidance receptor family induces axon repulsion in response to its ligand Slit by inducing local cytoskeletal changes; however, the link to the cytoskeleton and the nature of these cytoskeletal changes are poorly understood. Here, we show that the heteropentameric Scar/Wave Regulatory Complex (WRC) which drives Arp2/3-induced branched actin polymerization, is a direct effector of Robo signaling. Biochemical evidence shows that Slit triggers WRC recruitment to the Robo receptor's WIRS motif. In Drosophila embryos, mutants of the WRC enhance Robo1-dependent midline crossing defects. Additionally, mutating Robo1's WIRS motif significantly reduces receptor activity in rescue assays in vivo, and CRISPR-Cas9 mutagenesis shows that the WIRS motif is essential for endogenous Robo1 function. Finally, axon guidance assays in mouse dorsal spinal commissural axons and gain-of-function experiments in chick embryos demonstrate that the WIRS motif is also required for Robo1 repulsion in mammals. Together, our data support an essential conserved role for the WIRS-WRC interaction in Robo1-mediated axon repulsion. Keywords: D. melanogaster; chicken; developmental biology; mouse; neuroscience. © 2021, Chaudhari et al. Conflict of interest statement KC, MG, CC, AK, GB The authors declare that no competing interests exist.