A conserved role for Syntaxin-1 in pre- and post-commissural midline axonal guidance in fly, chick, and mouse

• DOI: 10.1371/journal.pgen.1007432
• Publication Date: 2018-06-18T18:10:22Z
• Authors: Oriol Ros; Pablo José Barrec...; Tiziana Cotrufo; Martina Schaettin; Cristina Roselló-...; Alba Vílchez-Acosta; Marc Hernaiz-Llorens; Ramón Martínez-Ma...; Fausto Ulloa; Esther T. Stoeckli; Sofia J. Araújo; Eduardo Soriano
• Keywords: 2716 Genetics (clinical); Evolution; Neurogenesis; Nerve Tissue Proteins; Chick Embryo; QH426-470; Nervous System; Exocytosis; 1105 Ecology; Mice; 03 medical and health sciences; Behavior and Systematics; 1311 Genetics; Cell Viability; 1312 Molecular Biology; Genetics; Animals; Drosophila Proteins; 1306 Cancer Research; Neutrins; Nerve Growth Factors; Neutrinos; Glycoproteins; Mice, Knockout; 0303 health sciences; Qa-SNARE Proteins; Chemotaxis; Membrane; Gene Expression Regulation, Developmental; Netrin-1; 10124 Institute of Molecular Life Sciences; Axons; 3. Good health; Sonic Hedgehog; 1105 Ecology, Evolution, Behavior and Systematics; Spinal Cord; NEURONAL GROWTH CONES; SONIC HEDGEHOG; IN-VIVO; DROSOPHILA; RECEPTOR; EXOCYTOSIS; NETRIN-1; SNAP-25; DCC; CHEMOATTRACTION; 570 Life sciences; biology; Drosophila; In-Vivo; SNARE Proteins; Neuronal Growth Cones; Genètica; Receptor; Research Article; Signal Transduction

Axonal growth and guidance rely on correct growth cone responses to guidance cues. Unlike the signaling cascades that link axonal growth to cytoskeletal dynamics, little is known about the crosstalk mechanisms between guidance and membrane dynamics and turnover. Recent studies indicate that whereas axonal attraction requires exocytosis, chemorepulsion relies on endocytosis. Indeed, our own studies have shown that Netrin-1/Deleted in Colorectal Cancer (DCC) signaling triggers exocytosis through the SNARE Syntaxin-1 (STX1). However, limited in vivo evidence is available about the role of SNARE proteins in axonal guidance. To address this issue, here we systematically deleted SNARE genes in three species. We show that loss-of-function of STX1 results in pre- and post-commissural axonal guidance defects in the midline of fly, chick, and mouse embryos. Inactivation of VAMP2, Ti-VAMP, and SNAP25 led to additional abnormalities in axonal guidance. We also confirmed that STX1 loss-of-function results in reduced sensitivity of commissural axons to Slit-2 and Netrin-1. Finally, genetic interaction studies in Drosophila show that STX1 interacts with both the Netrin-1/DCC and Robo/Slit pathways. Our data provide evidence of an evolutionarily conserved role of STX1 and SNARE proteins in midline axonal guidance in vivo, by regulating both pre- and post-commissural guidance mechanisms.