title: Ephrin-B2 and EphB1 mediate retinal axon divergence at the optic chiasm.
abstract: In animals with binocular vision, retinal ganglion cell (RGC) axons either cross or avoid the midline at the optic chiasm. Here, we show that ephrin-Bs in the chiasm region direct the divergence of retinal axons through the selective repulsion of a subset of RGCs that express EphB1. Ephrin-B2 is expressed at the mouse chiasm midline as the ipsilateral projection is generated and is selectively inhibitory to axons from ventrotemporal (VT) retina, where ipsilaterally projecting RGCs reside. Moreover, blocking ephrin-B2 function in vitro rescues the inhibitory effect of chiasm cells and eliminates the ipsilateral projection in the semiintact mouse visual system. A receptor for ephrin-B2, EphB1, is found exclusively in regions of retina that give rise to the ipsilateral projection. EphB1 null mice exhibit a dramatically reduced ipsilateral projection, suggesting that this receptor contributes to the formation of the ipsilateral retinal projection, most likely through its repulsive interaction with ephrin-B2.
authors.affiliation: Departments of Pathology, Anatomy and Cell Biology, Center for Neurobiology and Behavior, Columbia University, College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Williams
authors.forename: Fanny
authors.initials: F
authors.lastname: Mann
authors.forename: Lynda
authors.initials: L
authors.lastname: Erskine
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sakurai
authors.forename: Shiniu
authors.initials: S
authors.lastname: Wei
authors.forename: Derrick J
authors.initials: DJ
authors.lastname: Rossi
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Gale
authors.forename: Christine E
authors.initials: CE
authors.lastname: Holt
authors.forename: Carol A
authors.initials: CA
authors.lastname: Mason
authors.forename: Mark
authors.initials: M
authors.lastname: Henkemeyer
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism*; D002478:Cells, Cultured; D036387:Ephrin-B1 / Q000096:biosynthesis / Q000172:deficiency* / Q000235:genetics; D036388:Ephrin-B2 / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009897:Optic Chiasm / Q000196:embryology / Q000378:metabolism*; D011247:Pregnancy; D012160:Retina / Q000196:embryology / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000378:metabolism; D014981:Xenopus
chemical_list: D036387:Ephrin-B1; D036388:Ephrin-B2