title: NRP1-mediated Sema3A signals coordinate laminar formation in the developing chick optic tectum.
abstract: The optic tectum comprises multiple layers, which are formed by radial and tangential migration during development. Here, we report that Neuropilin 1 (NRP1)-mediated Sema3A signals are involved in the process of tectal laminar formation, which is elaborated by tangential migration. In the developing chick tectum, NRP1, a receptor for Sema3A, is expressed in microtubule-associated protein 2 (MAP2)-positive intermediate layers IV and V. Sema3A itself is a diffusible guidance factor and is expressed in the overlying layer VI. Using stable fluorescent labeling of tectal cells, we show that MAP2-positive intermediate layers are formed by the neurons that have been dispersed by tangential migration along the tectal efferent axons. When Sema3A was mis-expressed during laminar formation, local Sema3A repelled the tangential migrants, thus eliminating MAP2-positive neurons that expressed NRP1. Furthermore, in the absence of the MAP2-positive neurons, tectal layers were disorganized into an undulated form, indicating that MAP2-positive intermediate layers are required for proper laminar formation. These results suggest that NRP1-mediated Sema3A signals provide repulsive signals for MAP2-positive neurons to segregate tectal layers, which is important in order to coordinate laminar organization of the optic tectum.
authors.affiliation: Department of Molecular Neurobiology, Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8575, Japan Institute of Development, Aging & Cancer, Tohoku University, Sendai 980-8575, Japan Department of Neuroanatomy and Embryology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan yuji-w@fmu.ac.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Watanabe
authors.affiliation: Department of Neuroanatomy and Embryology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan.
authors.forename: Chie
authors.initials: C
authors.lastname: Sakuma
authors.affiliation: Department of Neuroanatomy and Embryology, School of Medicine, Fukushima Medical University, Fukushima 960-1295, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yaginuma
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine; D002465:Cell Movement / Q000502:physiology; D002642:Chick Embryo; D018274:Electroporation; D005453:Fluorescence; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D039942:Neuropilin-1 / Q000378:metabolism*; D038081:Organogenesis / Q000502:physiology*; D040121:Semaphorin-3A / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013477:Superior Colliculi / Q000196:embryology* / Q000378:metabolism
chemical_list: D008869:Microtubule-Associated Proteins; D040121:Semaphorin-3A; D039942:Neuropilin-1; D001973:Bromodeoxyuridine
keywords: Cell migration; Chick; Laminar formation; NRP1; Optic tectum; Sema3A