title: A role for Nr-CAM in the patterning of binocular visual pathways.
abstract: Retinal ganglion cell (RGC) axons diverge within the optic chiasm to project to opposite sides of the brain. In mouse, contralateral RGCs are distributed throughout the retina, whereas ipsilateral RGCs are restricted to the ventrotemporal crescent (VTC). While repulsive guidance mechanisms play a major role in the formation of the ipsilateral projection, little is known about the contribution of growth-promoting interactions to the formation of binocular visual projections. Here, we show that the cell adhesion molecule Nr-CAM is expressed by RGCs that project contralaterally and is critical for the guidance of late-born RGCs within the VTC. Blocking Nr-CAM function causes an increase in the size of the ipsilateral projection and reduces neurite outgrowth on chiasm cells in an age- and region-specific manner. Finally, we demonstrate that EphB1/ephrin-B2-mediated repulsion and Nr-CAM-mediated attraction comprise distinct molecular programs that each contributes to the proper formation of binocular visual pathways.
authors.affiliation: Center for Neurobiology and Behavior and Department of Pathology, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Williams
authors.forename: Martin
authors.initials: M
authors.lastname: Grumet
authors.forename: David R
authors.initials: DR
authors.lastname: Colman
authors.forename: Mark
authors.initials: M
authors.lastname: Henkemeyer
authors.forename: Carol A
authors.initials: CA
authors.lastname: Mason
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sakurai
mesh_terms: D000818:Animals; D019062:Cell Adhesion Molecules, Neuron-Glia / Q000235:genetics / Q000378:metabolism*; D007839:Functional Laterality; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009897:Optic Chiasm / Q000196:embryology / Q000254:growth & development*; D012165:Retinal Ganglion Cells / Q000378:metabolism*; D015348:Vision, Binocular / Q000502:physiology*; D014795:Visual Pathways / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism
chemical_list: D019062:Cell Adhesion Molecules, Neuron-Glia