Abstract
Interactions between integrins and growth factor receptors play a critical role in the development and healing of the vasculature. This study mapped two binding domains on fibronectin (FN) that modulate the activity of the angiogenic factor, vascular endothelial growth factor (VEGF). Using solid-phase assays and surface plasmon resonance analysis, we identified two novel VEGF binding domains within the N- and C-terminus of the FN molecule. Native FN bound to VEGF enhanced endothelial cell migration and mitogen-activated protein (MAP) kinase activity, but FN that is devoid of the VEGF binding domains failed to do so. Coprecipitation studies confirmed a direct physical association between VEGF receptor-2 (Flk-1) and the FN integrin, alpha5beta1, which required intact FN because FN fragments lacking the VEGF binding domains failed to support receptor association. Thrombin-activated platelets released intact VEGF/FN complexes, which stimulated endothelial cell migration and could be inhibited by soluble high affinity VEGF receptor 1 and antibodies to alpha5beta1 integrin. This study demonstrates that FN is potentially a physiological cofactor for VEGF and provides insights into mechanisms by which growth factor receptors and integrins cooperate to influence cellular behavior.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Binding Sites
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Blood Platelets / drug effects
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Blood Platelets / metabolism
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Cell Line
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Cell Movement / drug effects
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Endothelial Growth Factors / chemistry
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Endothelial Growth Factors / metabolism*
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Endothelium, Vascular / cytology
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Endothelium, Vascular / drug effects
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Endothelium, Vascular / metabolism*
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Enzyme Activation
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Extracellular Matrix Proteins / pharmacology
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Fibronectins / chemistry
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Fibronectins / metabolism*
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Humans
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Lymphokines / chemistry
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Lymphokines / metabolism*
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Mitogen-Activated Protein Kinases / metabolism
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Peptide Fragments / pharmacology
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Protein Binding
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Proto-Oncogene Proteins / metabolism
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Receptor Protein-Tyrosine Kinases / metabolism
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Receptors, Fibronectin / metabolism
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Receptors, Vitronectin / metabolism
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Thrombin / pharmacology
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Vascular Endothelial Growth Factor A
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Vascular Endothelial Growth Factor Receptor-1
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Vascular Endothelial Growth Factors
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Vitronectin / pharmacology
Substances
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Endothelial Growth Factors
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Extracellular Matrix Proteins
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Fibronectins
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Lymphokines
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Peptide Fragments
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Proto-Oncogene Proteins
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Receptors, Fibronectin
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Receptors, Vitronectin
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Vascular Endothelial Growth Factor A
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Vascular Endothelial Growth Factors
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Vitronectin
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Receptor Protein-Tyrosine Kinases
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Vascular Endothelial Growth Factor Receptor-1
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Mitogen-Activated Protein Kinases
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Thrombin