Abstract
Growth factor-induced signaling by receptor tyrosine kinases (RTKs) plays a central role in embryonic development and in pathogenesis and, hence, is tightly controlled by several regulatory proteins. Recently, Sprouty, an inhibitor of Drosophila development-associated RTK signaling, has been discovered. Subsequently, four mammalian Sprouty homologues (Spry-1-4) have been identified. Here, we report the functional characterization of two of them, Spry-1 and -2, in endothelial cells. Overexpressed Spry-1 and -2 inhibit fibroblast growth factor- and vascular endothelial growth factor-induced proliferation and differentiation by repressing pathways leading to p42/44 mitogen-activating protein (MAP) kinase activation. In contrast, although epidermal growth factor-induced proliferation of endothelial cells was also inhibited by Spry-1 and -2, activation of p42/44 MAP kinase was not affected. Biochemical and immunofluorescence analysis of endogenous and overexpressed Spry-1 and -2 reveal that both Spry-1 and -2 are anchored to membranes by palmitoylation and associate with caveolin-1 in perinuclear and vesicular structures. They are phosphorylated on serine residues and, upon growth factor stimulation, a subset is recruited to the leading edge of the plasma membrane. The data indicate that mammalian Spry-1 and -2 are membrane-anchored proteins that negatively regulate angiogenesis-associated RTK signaling, possibly in a RTK-specific fashion.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing
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Amino Acid Sequence
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Animals
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Caveolin 1
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Caveolins / metabolism
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Cell Differentiation / drug effects
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Cell Division / drug effects
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Cell Membrane / chemistry
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Cell Membrane / drug effects
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Cell Membrane / metabolism
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Cells, Cultured
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Cloning, Molecular
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Endothelium / cytology
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Endothelium / drug effects
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Endothelium / enzymology
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Endothelium / metabolism
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Enzyme Activation / drug effects
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Epidermal Growth Factor / antagonists & inhibitors
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Epidermal Growth Factor / pharmacology
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Fibroblast Growth Factors / pharmacology
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Growth Inhibitors / chemistry
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Growth Inhibitors / genetics
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Growth Inhibitors / metabolism*
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Growth Substances / pharmacology*
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Humans
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MAP Kinase Signaling System / drug effects*
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Membrane Proteins / chemistry
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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Mice
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Mitogen-Activated Protein Kinases / metabolism
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Molecular Sequence Data
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Nerve Tissue Proteins / chemistry
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / metabolism*
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Palmitic Acid / metabolism
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Phosphoproteins / chemistry
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Phosphoproteins / genetics
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Phosphoproteins / metabolism*
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Phosphorylation
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Sequence Alignment
Substances
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Adaptor Proteins, Signal Transducing
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CAV1 protein, human
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Cav1 protein, mouse
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Caveolin 1
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Caveolins
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Growth Inhibitors
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Growth Substances
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Membrane Proteins
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Nerve Tissue Proteins
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Phosphoproteins
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SPRY1 protein, human
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Spry1 protein, mouse
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Spry2 protein, rat
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Palmitic Acid
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Fibroblast Growth Factors
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Epidermal Growth Factor
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Mitogen-Activated Protein Kinases