title: Platelet-derived growth factor receptor beta and vascular endothelial growth factor receptor 2 bind to the beta 3 integrin through its extracellular domain.
abstract: Integrin-mediated cell attachment and growth factor stimulation often act synergistically on cell proliferation, differentiation, migration, and survival. Some of these synergistic effects depend on the physical interaction of integrins with growth factor receptors. Here we examine the nature of the physical interaction between the alpha(v)beta(3) integrin and two receptor tyrosine kinases (RTKs), the platelet-derived growth factor receptor beta (PDGF-Rbeta) and the vascular endothelial growth factor receptor 2 (VEGF-R2, also known as KDR and flk-1). Both of these RTKs associate with the alpha(v)beta(3) integrin but do not associate with beta(1) integrins. Furthermore, growth factor stimulation of these RTKs promotes increased cell proliferation and migration when cells are attached to the alpha(v)beta(3) ligand, vitronectin. We show that alpha(v)beta(3) in which the beta(3) cytoplasmic domain is deleted or replaced with the beta(1) cytoplasmic domain coimmunoprecipitates with PDGF-Rbeta and VEGF-R2. The beta(3) extracellular domain alone was sufficient for the PDGF-Rbeta association whereas the VEGF-R2 association required the presence of the alpha(v) subunit. Activation of the RTKs by their ligands was not required for them to associate with the integrin. Cell migration to PDGF was enhanced in the cells transfected with the chimeric subunit containing the beta(3) extracellular domain but not when that domain came from the beta(1) subunit. These results show that the interactions that lead to the association of the alpha(v)beta(3) integrin with PDGF-Rbeta and VEGF-R2 and enhancement of RTK activity take place outside the cell.
authors.affiliation: Cancer Research Center, The Burnham Institute, La Jolla, California 92037, USA.
authors.forename: E
authors.initials: E
authors.lastname: Borges
authors.forename: Y
authors.initials: Y
authors.lastname: Jan
authors.forename: E
authors.initials: E
authors.lastname: Ruoslahti
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D006801:Humans; D039661:Integrin beta3; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D011485:Protein Binding; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D013552:Swine
chemical_list: D015703:Antigens, CD; D039661:Integrin beta3; D010980:Platelet Membrane Glycoproteins; D017978:Receptors, Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D020797:Receptor, Platelet-Derived Growth Factor beta; D040262:Receptors, Vascular Endothelial Growth Factor