LTBP-2 Has a Single High-Affinity Binding Site for FGF-2 and Blocks FGF-2-Induced Cell Proliferation.
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.
Discipline of Anatomy and Pathology, School of Medicine, University of Adelaide, Adelaide, South Australia, 5005, Australia.
Clementine
C
Menz
Discipline of Anatomy and Pathology, School of Medicine, University of Adelaide, Adelaide, South Australia, 5005, Australia.
Mahroo K
MK
Parsi
Discipline of Anatomy and Pathology, School of Medicine, University of Adelaide, Adelaide, South Australia, 5005, Australia.
Julian R J
JR
Adams
Discipline of Anatomy and Pathology, School of Medicine, University of Adelaide, Adelaide, South Australia, 5005, Australia.
Mohamed A
MA
Sideek
Regenerative Medicine, Mawson Institute, University of South Australia, Adelaide, South Australia, 5095, Australia.
Zlatko
Z
Kopecki
Regenerative Medicine, Mawson Institute, University of South Australia, Adelaide, South Australia, 5095, Australia.
Allison J
AJ
Cowin
Discipline of Anatomy and Pathology, School of Medicine, University of Adelaide, Adelaide, South Australia, 5005, Australia.
Mark A
MA
Gibson
D001665:Binding Sites; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D000071837:Fibrillins; D016222:Fibroblast Growth Factor 2 / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D006493:Heparin / Q000378:metabolism; D006801:Humans; D007627:Keloid / Q000378:metabolism; D053779:Latent TGF-beta Binding Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D008840:Microfilament Proteins / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D021381:Protein Transport; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000819:agonists / Q000378:metabolism; D011994:Recombinant Proteins; D012867:Skin / Q000378:metabolism
D000071837:Fibrillins; C509035:LTBP2 protein, human; D053779:Latent TGF-beta Binding Proteins; D008840:Microfilament Proteins; D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2; D006493:Heparin; D051496:Receptor, Fibroblast Growth Factor, Type 1