Abstract
During spinal cord development, commissural (C) neurons, located near the dorsal midline, send axons ventrally and across the floor plate (FP). The trajectory of these axons toward the FP is guided in part by netrins. The mechanisms that guide the early phase of C axon extension, however, have not been resolved. We show that the roof plate (RP) expresses a diffusible activity that repels C axons and orients their growth within the dorsal spinal cord. Bone morphogenetic proteins (BMPs) appear to act as RP-derived chemorepellents that guide the early trajectory of the axons of C neurons in the developing spinal cord: BMP7 mimics the RP repellent activity for C axons in vitro, can act directly to collapse C growth cones, and appears to serve an essential function in RP repulsion of C axons.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Axons / physiology
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Bone Morphogenetic Protein 7
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Bone Morphogenetic Proteins / antagonists & inhibitors
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Bone Morphogenetic Proteins / genetics
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Bone Morphogenetic Proteins / physiology*
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COS Cells
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Culture Techniques
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Follistatin
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Gene Expression
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Glycoproteins / pharmacology
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Immunoglobulin G / pharmacology
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Mice
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Nerve Growth Factors / pharmacology
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Netrin-1
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Neurites / physiology
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Neurons / physiology*
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Rats
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Spinal Cord / cytology*
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Spinal Cord / embryology*
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Spinal Cord / metabolism
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Time Factors
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Transfection
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Transforming Growth Factor beta*
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Tumor Suppressor Proteins
Substances
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Bmp7 protein, rat
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Bone Morphogenetic Protein 7
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Bone Morphogenetic Proteins
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Follistatin
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Glycoproteins
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Immunoglobulin G
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Nerve Growth Factors
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Transforming Growth Factor beta
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Tumor Suppressor Proteins
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Netrin-1