Abstract
Vascular Endothelial Growth Factor-A (VEGF-A) is a key molecule in normal and tumor angiogenesis. This study addresses the role of c-ABL as a novel downstream target of VEGF-A in primary Human Umbilical Vein Endothelial Cells (HUVEC). On the basis of immunoprecipitation experiments, in vitro kinase assay and RNA interference, we demonstrate that VEGF-A induces the c-ABL kinase activity through the VEGF Receptor-2/Phosphatidylinositol-3-Kinase pathway. By treating HUVEC with the specific tyrosine kinase inhibitor STI571 and over-expressing a dominant negative c-ABL mutant, we show that the VEGF-A-activated c-ABL reduces the amplitude of Mitogen-Activated Protein Kinases (ERK1/2, JNKs and p38) activation in a dose-dependent manner by a negative feedback mechanism. By analysis of the adaptor proteins NCK1 and GRB2 mutants we further show that the negative loop on p38 is mediated by c-ABL phosphorylation at tyrosine 105 of the adaptor protein NCK1, while the phosphorylation at tyrosine 209 of GRB2 down-modulates ERK1/2 and JNKs signaling. These findings suggest that c-ABL function is to establish a correct and tightly controlled response of endothelial cells to VEGF-A during the angiogenic process.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing / genetics
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Adaptor Proteins, Signal Transducing / immunology*
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Adaptor Proteins, Signal Transducing / metabolism*
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Benzamides
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Cells, Cultured
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Endothelial Cells / cytology
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Endothelial Cells / metabolism
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Enzyme Activation / drug effects
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Enzyme Activation / physiology
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Extracellular Signal-Regulated MAP Kinases / genetics
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Extracellular Signal-Regulated MAP Kinases / metabolism*
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GRB2 Adaptor Protein / genetics
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GRB2 Adaptor Protein / metabolism*
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Humans
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Imatinib Mesylate
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MAP Kinase Signaling System / drug effects
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MAP Kinase Signaling System / physiology*
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Mutation
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Neovascularization, Physiologic / drug effects
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Neovascularization, Physiologic / physiology*
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Oncogene Proteins / genetics
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Oncogene Proteins / immunology*
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Oncogene Proteins / metabolism*
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Phosphatidylinositol 3-Kinases / genetics
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Phosphatidylinositol 3-Kinases / metabolism
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Phosphoinositide-3 Kinase Inhibitors
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Phosphorylation / drug effects
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Phosphorylation / physiology
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Piperazines / pharmacology
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Protein Kinase Inhibitors / pharmacology
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Proto-Oncogene Proteins c-abl / genetics
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Proto-Oncogene Proteins c-abl / metabolism*
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Pyrimidines / pharmacology
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Vascular Endothelial Growth Factor Receptor-2 / genetics
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Vascular Endothelial Growth Factor Receptor-2 / metabolism*
Substances
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Adaptor Proteins, Signal Transducing
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Benzamides
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GRB2 Adaptor Protein
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GRB2 protein, human
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Nck protein
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Oncogene Proteins
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Phosphoinositide-3 Kinase Inhibitors
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Piperazines
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Protein Kinase Inhibitors
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Pyrimidines
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Imatinib Mesylate
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Vascular Endothelial Growth Factor Receptor-2
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Proto-Oncogene Proteins c-abl
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Extracellular Signal-Regulated MAP Kinases