Abstract
We report that EphB receptors direct unique axonal behaviors required for mapping the dorsal-ventral (D-V) retinal axis along the lateral-medial (L-M) axis of the superior colliculus (SC). EphBs are expressed in a D-V gradient, ephrin-B1 in a L-M gradient in SC, and ephrin-B3 at its midline. EphBs and ephrin-Bs are expressed in countergradients in retina and SC. Developmental analyses reveal that retinal axons lack D-V ordering along the L-M axis, but directionally extend branches along it to establish ordered arbors. Directed branch extension is disrupted in EphB2; EphB3-deficient mice resulting in lateral ectopic arbors. Mice with kinase-inactive EphB2 have similar D-V mapping defects indicating that forward signaling dominates over reverse signaling. Our data suggest that branches of EphB expressing axons are attracted medially by ephrin-B1, and provide molecular mechanisms for D-V mapping in visual centers.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Body Patterning / genetics*
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Brain Mapping
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Cell Communication / physiology
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Cell Differentiation / genetics*
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Ephrin-B1
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Ephrin-B2
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Ephrin-B3
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Functional Laterality / genetics
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Gene Expression Regulation, Developmental / physiology
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Growth Cones / metabolism*
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Growth Cones / ultrastructure
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Membrane Proteins / deficiency
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Membrane Proteins / genetics
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Mice
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Mice, Knockout / abnormalities
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Mice, Knockout / metabolism*
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Receptor Protein-Tyrosine Kinases / genetics
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Receptor Protein-Tyrosine Kinases / metabolism*
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Receptors, Eph Family
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Retina / abnormalities
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Retina / cytology
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Retina / metabolism*
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Signal Transduction / physiology
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Superior Colliculi / abnormalities
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Superior Colliculi / cytology
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Superior Colliculi / metabolism*
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Visual Pathways / abnormalities
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Visual Pathways / cytology
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Visual Pathways / metabolism*
Substances
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Ephrin-B1
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Ephrin-B2
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Ephrin-B3
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Membrane Proteins
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Receptor Protein-Tyrosine Kinases
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Receptors, Eph Family