LTBP-2 Has a Single High-Affinity Binding Site for FGF-2 and Blocks FGF-2-Induced Cell Proliferation

• Published in: PloS one Vol. 10; no. 8; p. e0135577
• Main Authors: Menz, Clementine, Parsi, Mahroo K, Adams, Julian R J, Sideek, Mohamed A, Kopecki, Zlatko, Cowin, Allison J, Gibson, Mark A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11-08-2015; Public Library of Science (PLoS)
• Subjects: Anticoagulants; Binding Sites; Biological activity; Biology; Cell Line; Cell proliferation; Cell Proliferation - drug effects; Chemical properties; Confocal microscopy; Discipline; Epidermal growth factor; Extracellular matrix; Fibrillin; Fibrillins; Fibroblast growth factor 2; Fibroblast Growth Factor 2 - antagonists & inhibitors; Fibroblast Growth Factor 2 - chemistry; Fibroblast Growth Factor 2 - pharmacology; Fibroblasts; Fibroblasts - metabolism; Fibrosis; Growth factors; Heparan sulfate; Heparin; Heparin - metabolism; Humans; In vivo methods and tests; Keloid - metabolism; Kinases; Latent TGF-beta Binding Proteins - chemistry; Latent TGF-beta Binding Proteins - metabolism; Latent TGF-beta Binding Proteins - pharmacology; Medicine; Microfilament Proteins - metabolism; Microscopy; Molecular chains; Motility; Mutation; Pathology; Protein Binding; Protein Interaction Domains and Motifs; Protein Transport; Proteins; Receptor, Fibroblast Growth Factor, Type 1 - agonists; Receptor, Fibroblast Growth Factor, Type 1 - metabolism; Recombinant Proteins; Rodents; Skin - metabolism; Tissues; Transforming growth factor-b; Wound healing; Australia; South Australia Australia
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0135577

Latent transforming growth factor-beta-1 binding protein-2 (LTBP-2) belongs to the fibrillin-LTBP superfamily of extracellular matrix proteins. LTBPs and fibrillins are involved in the sequestration and storage of latent growth factors, particularly transforming growth factor β (TGF-β), in tissues. Unlike other LTBPs, LTBP-2 does not covalently bind TGF-β, and its molecular functions remain unclear. We are screening LTBP-2 for binding to other growth factors and have found very strong saturable binding to fibroblast growth factor-2 (FGF-2) (Kd = 1.1 nM). Using a series of recombinant LTBP-2 fragments a single binding site for FGF-2 was identified in a central region of LTBP-2 consisting of six tandem epidermal growth factor-like (EGF-like) motifs (EGFs 9-14). This region was also shown to contain a heparin/heparan sulphate-binding site. FGF-2 stimulation of fibroblast proliferation was completely negated by the addition of 5-fold molar excess of LTBP-2 to the assay. Confocal microscopy showed strong co-localisation of LTBP-2 and FGF-2 in fibrotic keloid tissue suggesting that the two proteins may interact in vivo. Overall the study indicates that LTBP-2 is a potent inhibitor of FGF-2 that may influence FGF-2 bioactivity during wound repair particularly in fibrotic tissues.