title: Compartmentalization of visual centers in the Drosophila brain requires Slit and Robo proteins.
abstract: Brain morphogenesis depends on the maintenance of boundaries between populations of non-intermingling cells. We used molecular markers to characterize a boundary within the optic lobe of the Drosophila brain and found that Slit and the Robo family of receptors, well-known regulators of axon guidance and neuronal migration, inhibit the mixing of adjacent cell populations in the developing optic lobe. Our data suggest that Slit is needed in the lamina to prevent inappropriate invasion of Robo-expressing neurons from the lobula cortex. We show that Slit protein surrounds lamina glia, while the distal cell neurons in the lobula cortex express all three Drosophila Robos. We examine the function of these proteins in the visual system by isolating a novel allele of slit that preferentially disrupts visual system expression of Slit and by creating transgenic RNA interference flies to inhibit the function of each Drosophila Robo in a tissue-specific fashion. We find that loss of Slit or simultaneous knockdown of Robo, Robo2 and Robo3 causes distal cell neurons to invade the lamina, resulting in cell mixing across the lamina/lobula cortex boundary. This boundary disruption appears to lead to alterations in patterns of axon navigation in the visual system. We propose that Slit and Robo-family proteins act to maintain the distinct cellular composition of the lamina and the lobula cortex.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue 68-230B, Cambridge, MA 02139, USA.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Tayler
authors.forename: Myles B
authors.initials: MB
authors.lastname: Robichaux
authors.forename: Paul A
authors.initials: PA
authors.lastname: Garrity
mesh_terms: D000483:Alleles; D000818:Animals; D001921:Brain / Q000196:embryology / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009474:Neurons / Q000378:metabolism; D009899:Optic Lobe, Nonmammalian / Q000196:embryology*; D010641:Phenotype; D017956:Photoreceptor Cells, Invertebrate / Q000196:embryology*; D034622:RNA Interference; D011971:Receptors, Immunologic / Q000235:genetics*; D013997:Time Factors; D019076:Transgenes; D014785:Vision, Ocular; 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