Abstract
EphA receptor tyrosine kinases and their ephrin ligands play important roles in wiring of the developing nervous system. We have investigated here the function of Src family kinases (SFKs) in the retinotectal projection to dissect the signaling pathways by which EphA receptors control actin/microtubule rearrangements that underlie growth cone guidance and collapse. Both EphAs and SFKs are expressed broadly in retinal growth cones, and SFKs are recruited to EphA receptors after ephrinA stimulation. In the stripe and growth cone collapse assays we observe an abolition of EphA-mediated repulsion after inhibiting SFKs, either pharmacologically or enzymatically via electroporation-mediated overexpression of the SFK inhibitor Csk. In addition, we identify cortactin and the RhoGEF ephexin, which interact with EphA receptors in retinal axons, as targets of SFK-dependent tyrosine phosphorylation. In sum, our data suggest an important role of SFKs as downstream signaling molecules in EphA receptor-mediated repulsive axon guidance.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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CSK Tyrosine-Protein Kinase
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Cell Line
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Chick Embryo
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Cortactin
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Electroporation
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Enzyme Inhibitors / pharmacology
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Eye Proteins / antagonists & inhibitors
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Eye Proteins / physiology*
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Green Fluorescent Proteins / analysis
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Green Fluorescent Proteins / genetics
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Growth Cones / enzymology*
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Growth Cones / physiology
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Guanine Nucleotide Exchange Factors / metabolism
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Humans
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Kidney
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Mice
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Microfilament Proteins / metabolism
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Optic Nerve / embryology
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Optic Nerve / enzymology*
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Phosphorylation
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Protein Processing, Post-Translational
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Protein-Tyrosine Kinases / genetics
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Protein-Tyrosine Kinases / physiology
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Receptors, Eph Family / physiology*
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Recombinant Fusion Proteins / physiology
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Retinal Ganglion Cells / cytology
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Retinal Ganglion Cells / enzymology*
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src-Family Kinases / antagonists & inhibitors
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src-Family Kinases / genetics
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src-Family Kinases / physiology*
Substances
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CTTN protein, human
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Cortactin
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Cttn protein, mouse
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Enzyme Inhibitors
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Eye Proteins
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Guanine Nucleotide Exchange Factors
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Microfilament Proteins
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NGEF protein, human
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Ngef protein, mouse
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Recombinant Fusion Proteins
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green fluorescent protein, Aequorea victoria
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Green Fluorescent Proteins
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Protein-Tyrosine Kinases
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Receptors, Eph Family
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CSK Tyrosine-Protein Kinase
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src-Family Kinases
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CSK protein, human