Ephrin-B2 and EphB1 mediate retinal axon divergence at the optic chiasm.
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.
Williams
Scott E
SE
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.
Mann
Fanny
F
Erskine
Lynda
L
Sakurai
Takeshi
T
Wei
Shiniu
S
Rossi
Derrick J
DJ
Gale
Nicholas W
NW
Holt
Christine E
CE
Mason
Carol A
CA
Henkemeyer
Mark
M
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
D036387:Ephrin-B1; D036388:Ephrin-B2