title: Short-range and long-range guidance by Slit and its Robo receptors: a combinatorial code of Robo receptors controls lateral position.
abstract: Slit is secreted by midline glia in Drosophila and functions as a short-range repellent to control midline crossing. Although most Slit stays near the midline, some diffuses laterally, functioning as a long-range chemorepellent. Here we show that a combinatorial code of Robo receptors controls lateral position in the CNS by responding to this presumptive Slit gradient. Medial axons express only Robo, intermediate axons express Robo3 and Robo, while lateral axons express Robo2, Robo3, and Robo. Removal of robo2 or robo3 causes lateral axons to extend medially; ectopic expression of Robo2 or Robo3 on medial axons drives them laterally. Precise topography of longitudinal pathways appears to be controlled by a combination of long-range guidance (the Robo code determining region) and short-range guidance (discrete local cues determining specific location within a region).
authors.affiliation: Howard Hughes Medical Institute, Division of Neurobiology, Department of Molecular and Cell Biology, 519 LSA, University of California, Berkeley CA 94720, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Simpson
authors.forename: K S
authors.initials: KS
authors.lastname: Bland
authors.forename: R D
authors.initials: RD
authors.lastname: Fetter
authors.forename: C S
authors.initials: CS
authors.lastname: Goodman
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology; D004330:Drosophila / Q000196:embryology* / Q000502:physiology; D029721:Drosophila Proteins; D018507:Gene Expression Regulation, Developmental; D016253:Microscopy, Immunoelectron; D016296:Mutagenesis / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D009420:Nervous System / Q000737:chemistry / Q000196:embryology; D009474:Neurons / Q000502:physiology / Q000648:ultrastructure; D010641:Phenotype; D011971:Receptors, Immunologic / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D000097905:Roundabout Proteins
chemical_list: D029721:Drosophila Proteins; D009419:Nerve Tissue Proteins; D011971:Receptors, Immunologic; D000097905:Roundabout Proteins; C421243:Robo2 protein, Drosophila; C421244:robo3 protein, Drosophila; C066819:sli protein, Drosophila