Slit1 and Slit2 Cooperate to Prevent Premature Midline Crossing of Retinal Axons in the Mouse Visual System

During development, retinal ganglion cell (RGC) axons either cross or avoid the midline at the optic chiasm. In Drosophila, the Slit protein regulates midline axon crossing through repulsion. To determine the role of Slit proteins in RGC axon guidance, we disrupted Slit1 and Slit2, two of three known mouse Slit genes. Mice defective in either gene alone exhibited few RGC axon guidance defects, but in double mutant mice a large additional chiasm developed anterior to the true chiasm, many retinal axons projected into the contralateral optic nerve, and some extended ectopically-dorsal and lateral to the chiasm. Our results indicate that Slit proteins repel retinal axons in vivo and cooperate to establish a corridor through which the axons are channeled, thereby helping define the site in the ventral diencephalon where the optic chiasm forms.

[1]  J. Rothberg,et al.  slit: an extracellular protein necessary for development of midline glia and commissural axon pathways contains both EGF and LRR domains. , 1990, Genes & development.

[2]  O. Marín,et al.  Slit Proteins Prevent Midline Crossing and Determine the Dorsoventral Position of Major Axonal Pathways in the Mammalian Forebrain , 2002, Neuron.

[3]  Alain Chédotal,et al.  Slit2-Mediated Chemorepulsion and Collapse of Developing Forebrain Axons , 1999, Neuron.

[4]  William A. Harris,et al.  Ephrin-B Regulates the Ipsilateral Routing of Retinal Axons at the Optic Chiasm , 2000, Neuron.

[5]  U. Dräger,et al.  Birth dates of retinal ganglion cells giving rise to the crossed and uncrossed optic projections in the mouse , 1985, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[6]  Sophie Dupuis,et al.  Directional guidance of neuronal migration in the olfactory system by the protein Slit , 1999, Nature.

[7]  Toshiya Yamada,et al.  Distinct but overlapping expression patterns of two vertebrate slit homologs implies functional roles in CNS development and organogenesis , 1998, Mechanisms of Development.

[8]  Chad A. Cowan,et al.  Kinase independent function of EphB receptors in retinal axon pathfinding to the optic disc from dorsal but not ventral retina. , 2000, Development.

[9]  Y. Rao,et al.  Cellular and Molecular Guidance of GABAergic Neuronal Migration from an Extracortical Origin to the Neocortex , 1999, Neuron.

[10]  C. Mason,et al.  Retinal axon divergence in the optic chiasm: dynamics of growth cone behavior at the midline [published erratum appears in J Neurosci 1995 Mar;15(3):following table of contents] , 1994, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[11]  J. Trojanowski,et al.  Monoclonal antibodies distinguish several differentially phosphorylated states of the two largest rat neurofilament subunits (NF-H and NF-M) and demonstrate their existence in the normal nervous system of adult rats , 1987, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[12]  Richard Axel,et al.  Visualizing an Olfactory Sensory Map , 1996, Cell.

[13]  R. Guillery,et al.  The early development of retinal ganglion cells with uncrossed axons in the mouse: retinal position and axonal course. , 1990, Development.

[14]  S. Chan,et al.  Changes in axon arrangement in the retinofungal pathway of mouse embryos: Confocal microscopy study using single‐ and double‐dye label , 1999 .

[15]  Michael S. Deiner,et al.  Netrin-1 and DCC Mediate Axon Guidance Locally at the Optic Disc: Loss of Function Leads to Optic Nerve Hypoplasia , 1997, Neuron.

[16]  G. Martin,et al.  Cre–mediated chromosome loss in mice , 1997, Nature Genetics.

[17]  J. Silver,et al.  A chondroitin sulfate proteoglycan may influence the direction of retinal ganglion cell outgrowth. , 1991, Development.

[18]  J. S. Taylor,et al.  Axon routing at the optic chiasm after enzymatic removal of chondroitin sulfate in mouse embryos. , 2000, Development.

[19]  Y. Rao,et al.  Vertebrate Slit, a Secreted Ligand for the Transmembrane Protein Roundabout, Is a Repellent for Olfactory Bulb Axons , 1999, Cell.

[20]  Franco Weth,et al.  Modulation of EphA Receptor Function by Coexpressed EphrinA Ligands on Retinal Ganglion Cell Axons , 1999, Neuron.

[21]  M. Tessier-Lavigne,et al.  Hierarchical Organization of Guidance Receptors: Silencing of Netrin Attraction by Slit Through a Robo/DCC Receptor Complex , 2001, Science.

[22]  U. Drescher,et al.  Topographic targeting and pathfinding errors of retinal axons following overexpression of ephrinA ligands on retinal ganglion cell axons. , 1999, Developmental biology.

[23]  E. Puré,et al.  Embryonic neurons of the developing optic chiasm express L1 and CD44, cell surface molecules with opposing effects on retinal axon growth , 1994, Neuron.

[24]  Y. Rao,et al.  The neuronal repellent Slit inhibits leukocyte chemotaxis induced by chemotactic factors , 2001, Nature.

[25]  J. Silver.  Studies on the factors that govern directionality of axonal growth in the embryonic optic nerve and at the chiasm of mice , 1984, The Journal of comparative neurology.

[26]  C. Chien,et al.  astray, a Zebrafish roundabout Homolog Required for Retinal Axon Guidance , 2001, Science.

[27]  Marc Tessier-Lavigne,et al.  Squeezing Axons Out of the Gray Matter A Role for Slit and Semaphorin Proteins from Midline and Ventral Spinal Cord , 2000, Cell.

[28]  C. Mason,et al.  Retinal axon pathfinding in the optic chiasm: Divergence of crossed and uncrossed fibers , 1990, Neuron.

[29]  C. Goodman,et al.  Slit Inhibition of Retinal Axon Growth and Its Role in Retinal Axon Pathfinding and Innervation Patterns in the Diencephalon , 2000, The Journal of Neuroscience.

[30]  C. Goodman,et al.  Slit Proteins Bind Robo Receptors and Have an Evolutionarily Conserved Role in Repulsive Axon Guidance , 1999, Cell.

[31]  D. Sretavan.  Specific routing of retinal ganglion cell axons at the mammalian optic chiasm during embryonic development , 1990, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[32]  J. Silver,et al.  Chondroitin sulfate as a regulator of neuronal patterning in the retina. , 1992, Science.

[33]  Paul A Yates,et al.  Molecular Development of Sensory Maps Representing Sights and Smells in the Brain , 1999, Cell.

[34]  C. Mason,et al.  Retinal axon divergence in the optic chiasm: uncrossed axons diverge from crossed axons within a midline glial specialization , 1995, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[35]  S. Niclou,et al.  Slit2 Is a Repellent for Retinal Ganglion Cell Axons , 2000, The Journal of Neuroscience.

[36]  Vance Lemmon,et al.  Unique Changes of Ganglion Cell Growth Cone Behavior Following Cell Adhesion Molecule Perturbations: A Time-Lapse Study of the Living Retina , 1995, Molecular and Cellular Neuroscience.

[37]  S. Sakano,et al.  Cloning and expressions of three mammalian homologues of Drosophila slit suggest possible roles for Slit in the formation and maintenance of the nervous system. , 1998, Brain research. Molecular brain research.

[38]  S. Munro,et al.  A C-terminal signal prevents secretion of luminal ER proteins , 1987, Cell.

[39]  Julie H. Simpson,et al.  Short-Range and Long-Range Guidance by Slit and Its Robo Receptors A Combinatorial Code of Robo Receptors Controls Lateral Position , 2000, Cell.

[40]  J. Silver,et al.  Axon pathway boundaries in the developing brain. I. Cellular and molecular determinants that separate the optic and olfactory projections , 1987, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[41]  L Erskine,et al.  Growth cone form, behavior, and interactions in vivo: retinal axon pathfinding as a model. , 2000, Journal of neurobiology.

[42]  C. Goodman,et al.  Slit Is the Midline Repellent for the Robo Receptor in Drosophila , 1999, Cell.

[43]  L Erskine,et al.  Retinal Ganglion Cell Axon Guidance in the Mouse Optic Chiasm: Expression and Function of Robos and Slits , 2000, The Journal of Neuroscience.

[44]  Marc Tessier-Lavigne,et al.  Roundabout Controls Axon Crossing of the CNS Midline and Defines a Novel Subfamily of Evolutionarily Conserved Guidance Receptors , 1998, Cell.

[45]  B. Dickson,et al.  Selecting a Longitudinal Pathway Robo Receptors Specify the Lateral Position of Axons in the Drosophila CNS , 2000, Cell.

[46]  I. Rodriguez,et al.  Variable Patterns of Axonal Projections of Sensory Neurons in the Mouse Vomeronasal System , 1999, Cell.

[47]  D. O'Leary,et al.  Retinal axon guidance by region-specific cues in diencephalon. , 1998, Development.

[48]  Michael S. Deiner,et al.  Altered Midline Axon Pathways and Ectopic Neurons in the Developing Hypothalamus of Netrin-1- and DCC-Deficient Mice , 1999, The Journal of Neuroscience.

[49]  L. Cox,et al.  Cloning and functional studies of a novel gene aberrantly expressed in RB-deficient embryos. , 1999, Developmental biology.