Mammalian sprouty-1 and -2 are membrane-anchored phosphoprotein inhibitors of growth factor signaling in endothelial cells.
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.
Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria.
M A
MA
Impagnatiello
S
S
Weitzer
G
G
Gannon
A
A
Compagni
M
M
Cotten
G
G
Christofori
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004727:Endothelium / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D006131:Growth Inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019308:Palmitic Acid / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D016415:Sequence Alignment
D048868:Adaptor Proteins, Signal Transducing; C495540:CAV1 protein, human; C495541:Cav1 protein, mouse; D051242:Caveolin 1; D022461:Caveolins; D006131:Growth Inhibitors; D006133:Growth Substances; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; C486055:SPRY1 protein, human; C425468:Spry1 protein, mouse; C404992:Spry2 protein, rat; D019308:Palmitic Acid; D005346:Fibroblast Growth Factors; D004815:Epidermal Growth Factor; D020928:Mitogen-Activated Protein Kinases