title: Integrin activation is required for VEGF and FGF receptor protein presence on human microvascular endothelial cells.
abstract: Endothelial cell proliferation and migration is initiated by growth factors including FGF and VEGF that bind to specific transmembrane receptor tyrosine kinases. Mechanisms that regulate in vivo expression of fibroblast growth factor receptors (FGFR) and vascular endothelial growth factor receptors (VEGFR) are not well understood. Since it is well known that different matrices influence the proliferation and migration of endothelial cells in culture, we hypothesized that changes in the extracellular matrix environment can regulate growth factor receptors on endothelial cells. We cultured human microvascular endothelial cells on different matrices (vitronectin, laminin, fibronectin, fibrin, and collagen IV) and examined for the presence of growth factor receptors (FGFR-1, FGFR-2, VEGFR-1, and VEGFR-2). We show that vitronectin increased the presence of all four growth factor receptors and most notably, VEGFR-1. In contrast, fibrin decreased all four receptors, especially FGFR-1 and FGFR-2. Inhibiting phosphotyrosine signaling abolished immunostaining for all four receptors, regardless of the matrix, but was not dependent on activating the Fyn-Shc pathway. Cells plated on vitronectin in the presence of blocking antibodies to integrins alphavbeta3 and alphavbeta5 similarly decreased presence of these growth factor receptors. Our data suggests a possible mechanism of how matrix-integrin interactions regulate endothelial cell responsiveness to growth factors and anchorage-dependent cell growth.
authors.affiliation: Department of Surgery, VA Puget Sound Health Care System and University of Washington Medical Center Seattle, 98195, USA.
authors.forename: R
authors.initials: R
authors.lastname: Tsou
authors.forename: F F
authors.initials: FF
authors.lastname: Isik
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D015153:Blotting, Western; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D004789:Enzyme Activation; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005337:Fibrin / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D019000:Phosphotyrosine / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051076:Proto-Oncogene Proteins c-fyn; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D017468:Receptors, Fibroblast Growth Factor / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013936:Thymidine / Q000378:metabolism; D019096:Vitronectin / Q000378:metabolism / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D016326:Extracellular Matrix Proteins; D016023:Integrins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D017468:Receptors, Fibroblast Growth Factor; D017978:Receptors, Growth Factor; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D019096:Vitronectin; D019000:Phosphotyrosine; D005337:Fibrin; D004247:DNA; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; D013936:Thymidine