title: Heparin/Heparan sulfate domains in binding and signaling of fibroblast growth factor 8b.
abstract: The role of heparin and heparan sulfate in the binding and signaling of fibroblast growth factors (FGFs) has been subject to intense investigation, but the studies have largely been confined to two species (FGF1 and FGF2) of the family with approximately 20 members. We have investigated the structural requirements for heparin/heparan sulfate in binding and activation of FGF8 (splice variant b). We present evidence that the minimal FGF8b-binding saccharide domain encompasses 5-7 monosaccharide units. The N-, 2-O-, and 6-O-sulfate substituents of heparin/heparan sulfate (HS) are all involved in the interaction, preferentially in the form of trisulfated IdoUA(2-OSO(3))-GlcNSO(3)(6-OSO(3)) disaccharide constituents. These structural characteristics resemble those described earlier for FGF1. By contrast, the saccharide structures required for the biological activity of FGF8b differed significantly from those characteristic for FGF1 and FGF2. Experiments with cells lacking active HS indicated that extended >/=14-mer heparin domains were needed to enhance cell proliferation and Erk phosphorylation by FGF8b, whereas in cells stimulated with FGF1 or FGF2 the corresponding responses were achieved by much shorter, 6-8-mer, oligosaccharides. Furthermore, still longer domains were needed to activate FGF8b in cells with "non-optimal" FGF receptor expression. Collectively, our data suggest that the heparin/HS structures enhancing the biological activity of FGFs were influenced by the FGF species involved as well as by the cellular composition of FGF receptors.
authors.affiliation: Turku Centre for Biotechnology, University of Turku and Abo Akademi University and BioTie Therapies Corporation, FIN-20520 Turku, Finland.
authors.forename: Britt-Marie
authors.initials: BM
authors.lastname: Loo
authors.forename: Markku
authors.initials: M
authors.lastname: Salmivirta
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D002417:Cattle; D002455:Cell Division; D006224:Cricetinae; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004187:Disaccharides / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006493:Heparin / Q000737:chemistry* / Q000378:metabolism; D006497:Heparan Sulfate / Q000737:chemistry* / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D013552:Swine; D013997:Time Factors; D014162:Transfection
chemical_list: D016895:Culture Media, Serum-Free; D004187:Disaccharides; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors; D006493:Heparin; D006497:Heparan Sulfate; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020033:Protein Isoforms