The online version of this article (doi:10.1186/ar3441) contains supplementary material, which is available to authorized users.
The authors declare that they have no competing interests.
DY designed the experiments for this study, acquired the data, interpreted the data, carried out the flow cytometry analysis and drafted the manuscript. DC and H-JI designed the experiments for this study, interpreted the data and drafted the manuscript. SC and GM interpreted the data. KM interpreted the data and carried out the flow cytometry analysis. AW interpreted the data and drafted the manuscript. All authors read, edited and approved the final manuscript.
Cartilage degeneration driven by catabolic stimuli is a critical pathophysiological process in osteoarthritis (OA). We have defined fibroblast growth factor 2 (FGF-2) as a degenerative mediator in adult human articular chondrocytes. Biological effects mediated by FGF-2 include inhibition of proteoglycan production, up-regulation of matrix metalloproteinase-13 (MMP-13), and stimulation of other catabolic factors. In this study, we identified the specific receptor responsible for the catabolic functions of FGF-2, and established a pathophysiological connection between the FGF-2 receptor and OA.
Primary human articular chondrocytes were cultured in monolayer (24 hours) or alginate beads (21 days), and stimulated with FGF-2 or FGF18, in the presence or absence of FGFR1 (FGF receptor 1) inhibitor. Proteoglycan accumulation and chondrocyte proliferation were assessed by dimethylmethylene blue (DMMB) assay and DNA assay, respectively. Expression of FGFRs (FGFR1 to FGFR4) was assessed by flow cytometry, immunoblotting, and quantitative real-time PCR (qPCR). The distinctive roles of FGFR1 and FGFR3 after stimulation with FGF-2 were evaluated using either pharmacological inhibitors or FGFR small interfering RNA (siRNA). Luciferase reporter gene assays were used to quantify the effects of FGF-2 and FGFR1 inhibitor on MMP-13 promoter activity.
Chondrocyte proliferation was significantly enhanced in the presence of FGF-2 stimulation, which was inhibited by the pharmacological inhibitor of FGFR1. Proteoglycan accumulation was reduced by 50% in the presence of FGF-2, and this reduction was successfully rescued by FGFR1 inhibitor. FGFR1 inhibitors also fully reversed the up-regulation of MMP-13 expression and promoter activity stimulated by FGF-2. Blockade of FGFR1 signaling by either chemical inhibitors or siRNA targeting FGFR1 rather than FGFR3 abrogated the up-regulation of matrix metalloproteinases 13 (MMP-13) and a disintegrin and metalloproteinase with a thrombospondin type 1 motif 5 (ADAMTS5), as well as down-regulation of aggrecan after FGF-2 stimulation. Flow cytometry, qPCR and immunoblotting analyses suggested that FGFR1 and FGFR3 were the major FGFR isoforms expressed in human articular chondrocytes. FGFR1 was activated more potently than FGFR3 upon FGF-2 stimulation. In osteoarthritic chondrocytes, FGFR3 was significantly down regulated (P < 0.05) with a concomitant increase in the FGFR1 to FGFR3 expression ratio (P < 0.05), compared to normal chondrocytes. Our results also demonstrate that FGFR3 was negatively regulated by FGF-2 at the transcriptional level through the FGFR1-ERK (extracellular signal-regulated kinase) signaling pathway in human articular chondrocytes.
FGFR1 is the major mediator with the degenerative potential in the presence of FGF-2 in human adult articular chondrocytes. FGFR1 activation by FGF-2 promotes catabolism and impedes anabolism. Disruption of the balance between FGFR1 and FGFR3 signaling ratio may contribute to the pathophysiology of OA.
Bauge C, Legendre F, Leclercq S, Elissalde JM, Pujol JP, Galera P, Boumediene K: Interleukin-1beta impairment of transforming growth factor beta1 signaling by down-regulation of transforming growth factor beta receptor type II and up-regulation of Smad7 in human articular chondrocytes. Arthritis Rheum. 2007, 56: 3020-3032. 10.1002/art.22840. CrossRefPubMed
Kaiser M, Haag J, Soder S, Bau B, Aigner T: Bone morphogenetic protein and transforming growth factor beta inhibitory Smads 6 and 7 are expressed in human adult normal and osteoarthritic cartilage in vivo and are differentially regulated in vitro by interleukin-1beta. Arthritis Rheum. 2004, 50: 3535-3540. 10.1002/art.20750. CrossRefPubMed
Im HJ, Muddasani P, Natarajan V, Schmid TM, Block JA, Davis F, van Wijnen AJ, Loeser RF: Basic fibroblast growth factor stimulates matrix metalloproteinase-13 via the molecular cross-talk between the mitogen-activated protein kinases and protein kinase Cdelta pathways in human adult articular chondrocytes. J Biol Chem. 2007, 282: 11110-11121. 10.1074/jbc.M609040200. PubMedCentralCrossRefPubMed
Muddasani P, Norman JC, Ellman M, van Wijnen AJ, Im HJ: Basic fibroblast growth factor activates the MAPK and NFkappaB pathways that converge on Elk-1 to control production of matrix metalloproteinase-13 by human adult articular chondrocytes. J Biol Chem. 2007, 282: 31409-31421. 10.1074/jbc.M706508200. CrossRefPubMed
Im HJ, Pacione C, Chubinskaya S, Van Wijnen AJ, Sun Y, Loeser RF: Inhibitory effects of insulin-like growth factor-1 and osteogenic protein-1 on fibronectin fragment- and interleukin-1beta-stimulated matrix metalloproteinase-13 expression in human chondrocytes. J Biol Chem. 2003, 278: 25386-25394. 10.1074/jbc.M302048200. PubMedCentralCrossRefPubMed
Loeser RF, Todd MD, Seely BL: Prolonged treatment of human osteoarthritic chondrocytes with insulin-like growth factor-I stimulates proteoglycan synthesis but not proteoglycan matrix accumulation in alginate cultures. J Rheumatol. 2003, 30: 1565-1570. PubMed
Ellsworth JL, Berry J, Bukowski T, Claus J, Feldhaus A, Holderman S, Holdren MS, Lum KD, Moore EE, Raymond F, Ren H, Shea P, Sprecher C, Storey H, Thompson DL, Waggie K, Yao L, Fernandes RJ, Eyre DR, Hughes SD: Fibroblast growth factor-18 is a trophic factor for mature chondrocytes and their progenitors. Osteoarthritis Cartilage. 2002, 10: 308-320. 10.1053/joca.2002.0514. CrossRefPubMed
Valverde-Franco G, Binette JS, Li W, Wang H, Chai S, Laflamme F, Tran-Khanh N, Quenneville E, Meijers T, Poole AR, Mort JS, Buschmann MD, Henderson JE: Defects in articular cartilage metabolism and early arthritis in fibroblast growth factor receptor 3 deficient mice. Hum Mol Genet. 2006, 15: 1783-1792. 10.1093/hmg/ddl100. CrossRefPubMed
Neuhold LA, Killar L, Zhao W, Sung ML, Warner L, Kulik J, Turner J, Wu W, Billinghurst C, Meijers T, Poole AR, Babij P, DeGennaro LJ: Postnatal expression in hyaline cartilage of constitutively active human collagenase-3 (MMP-13) induces osteoarthritis in mice. J Clin Invest. 2001, 107: 35-44. 10.1172/JCI10564. PubMedCentralCrossRefPubMed
Kaul G, Cucchiarini M, Arntzen D, Zurakowski D, Menger MD, Kohn D, Trippel SB, Madry H: Local stimulation of articular cartilage repair by transplantation of encapsulated chondrocytes overexpressing human fibroblast growth factor 2 (FGF-2) in vivo. J Gene Med. 2006, 8: 100-111. 10.1002/jgm.819. CrossRefPubMed
- Fibroblast growth factor receptor 1 is principally responsible for fibroblast growth factor 2-induced catabolic activities in human articular chondrocytes
Simon M Cool
Andre J van Wijnen
- BioMed Central
Neu im Fachgebiet Innere Medizin
Meistgelesene Bücher aus der Inneren Medizin
Mail Icon II