title: Sonic hedgehog guides commissural axons along the longitudinal axis of the spinal cord.
abstract: Dorsal commissural axons in the developing spinal cord cross the floor plate, then turn rostrally and grow along the longitudinal axis, close to the floor plate. We used a subtractive hybridization approach to identify guidance cues responsible for the rostral turn in chicken embryos. One of the candidates was the morphogen Sonic hedgehog (Shh). Silencing of the gene SHH (which encodes Shh) by in ovo RNAi during commissural axon navigation demonstrated a repulsive role in post-commissural axon guidance. This effect of Shh was not mediated by Patched (Ptc) and Smoothened (Smo), the receptors that mediate effects of Shh in morphogenesis and commissural axon growth toward the floor plate. Rather, functional in vivo studies showed that the repulsive effect of Shh on postcommissural axons was mediated by Hedgehog interacting protein (Hip).
authors.affiliation: University of Zurich, Institute of Zoology, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Bourikas
authors.forename: Vladimir
authors.initials: V
authors.lastname: Pekarik
authors.forename: Thomas
authors.initials: T
authors.lastname: Baeriswyl
authors.forename: Asa
authors.initials: A
authors.lastname: Grunditz
authors.forename: Rejina
authors.initials: R
authors.lastname: Sadhu
authors.forename: Michele
authors.initials: M
authors.lastname: Nardó
authors.forename: Esther T
authors.initials: ET
authors.lastname: Stoeckli
mesh_terms: D000367:Age Factors; D000818:Animals; D001369:Axons / Q000502:physiology*; D019521:Body Patterning / Q000502:physiology*; D002232:Carbocyanines / Q000378:metabolism; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002642:Chick Embryo; D003001:Cloning, Molecular / Q000379:methods; D003952:Diagnostic Imaging / Q000379:methods; D004622:Embryo, Mammalian / Q000166:cytology*; D004625:Embryo, Nonmammalian; D004627:Embryonic Induction; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D053823:Hedgehog Proteins; D006825:Hybridomas; D017403:In Situ Hybridization / Q000379:methods; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D016372:RNA, Antisense / Q000494:pharmacology; D034741:RNA, Small Interfering; D013116:Spinal Cord / Q000166:cytology* / Q000196:embryology*; D015534:Trans-Activators / Q000502:physiology*; D014704:Veratrum Alkaloids / Q000494:pharmacology
chemical_list: C035005:3,3'-dihexadecylindocarbocyanine; D002232:Carbocyanines; D015816:Cell Adhesion Molecules, Neuronal; D053823:Hedgehog Proteins; D008565:Membrane Proteins; D016372:RNA, Antisense; D034741:RNA, Small Interfering; D015534:Trans-Activators; D014704:Veratrum Alkaloids; C000541:cyclopamine