title: Platelet-derived growth factor-BB and basic fibroblast growth factor directly interact in vitro with high affinity.
abstract: Platelet-derived growth factor-BB (PDGF-BB) and basic fibroblast growth factor (bFGF) are potent growth factors active on many cell types. The present study indicates that they directly interact in vitro. The interaction was investigated with overlay experiments, surface plasmon resonance experiments, and solid-phase immunoassays by immobilizing one factor or the other and by steady-state fluorescence analysis. The interaction observed was specific, dose-dependent, and saturable, and the bFGF/PDGF-BB binding stoichiometry was found to be 2:1. K(D)(1) for the first step equilibrium and the overall K(D) values were found to be in the nanomolar and in the picomolar range, respectively. Basic FGF/PDGF-BB interaction was strongly reduced as a function of time of PDGF-BB proteolysis. Furthermore, docking analysis suggested that the PDGF-BB region interacting with bFGF may overlap, at least in part, with the PDGF-BB receptor-binding site. This hypothesis was supported by surface plasmon resonance experiments showing that an anti-PDGF-BB antibody, known to inhibit PDGF-BB binding with its receptor, strongly reduced bFGF/PDGF-BB interaction, whereas a control antibody was ineffective. According to these data, the observed bFGF.PDGF-BB complex formation might explain, at least in part, previous observations showing that PDGF-BB chemotactic and mitogenic activity on smooth muscle cells are strongly inhibited in the presence of bFGF.
authors.affiliation: Laboratorio di Patologia Vascolare, Istituto Dermopatico dell'Immacolata, Istituto di Ricovero e Cura a Carattere Scientifico, 00167 Roma, Italy.
authors.forename: Katia
authors.initials: K
authors.lastname: Russo
authors.forename: Raffaele
authors.initials: R
authors.lastname: Ragone
authors.forename: Angelo M
authors.initials: AM
authors.lastname: Facchiano
authors.forename: Maurizio C
authors.initials: MC
authors.lastname: Capogrossi
authors.forename: Antonio
authors.initials: A
authors.lastname: Facchiano
mesh_terms: D000077214:Becaplermin; D003198:Computer Simulation; D004229:Dithiothreitol / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000737:chemistry / Q000378:metabolism*; D007118:Immunoassay; D008958:Models, Molecular; D010982:Platelet-Derived Growth Factor / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D020574:Proto-Oncogene Proteins c-sis; D013050:Spectrometry, Fluorescence; D020349:Surface Plasmon Resonance
chemical_list: D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D016222:Fibroblast Growth Factor 2; D000077214:Becaplermin; D004229:Dithiothreitol