Abstract
The production of chemokine stromal cell-derived factor (SDF)-1 is significantly higher in synovial fluid of patients with osteoarthritis and rheumatoid arthritis. Matrix metalloproteinase (MMP)-13 may contribute to the breakdown of articular cartilage during arthritis. Here, we found that SDF-1α increased the secretion of MMP-13 in cultured human chondrocytes, as shown by reverse transcriptase-polymerase chain reaction, Western blot, and zymographic analysis. SDF-1α also increased the surface expression of CXCR4 receptor in human chondrocytes. CXCR4-neutralizing antibody, CXCR4-specific inhibitor [1-[[4-(1,4,8,11-tetrazacyclotetradec-1-ylmethyl)phenyl]methyl]-1,4,8,11-tetrazacyclotetradecane (AMD3100)], or small interfering RNA against CXCR4 inhibited the SDF-1α-induced increase of MMP-13 expression. The transcriptional regulation of MMP-13 by SDF-1α was mediated by phosphorylation of extracellular signal-regulated kinases (ERK) and activation of the activator protein (AP)-1 components of c-Fos and c-Jun. The binding of c-Fos and c-Jun to the activator protein (AP-1) element on the MMP-13 promoter and the increase in luciferase activity was enhanced by SDF-1α. Cotransfection with dominant-negative mutant of ERK2 or c-Fos and c-Jun antisense oligonucleotide inhibited the potentiating action of SDF-1α on MMP-13 promoter activity. Taken together, our results provide evidence that SDF-1α acts through CXCR4 to activate ERK and the downstream transcription factors (c-Fos and c-Jun), resulting in the activation of AP-1 on the MMP-13 promoter and contributing cartilage destruction during arthritis.
Footnotes
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This work was supported by a grant from Taichung Veterans General Hospital (TCVGH-TTMHH968501) and National Science Council.
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Y.-C.C., R.-S.Y., and K.-H.H. contributed equally to this work. C.-H.T. and W.-M.F. contributed equally to this work.
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Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
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doi:10.1124/mol.107.036541.
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ABBREVIATIONS: MMP, matrix metalloproteinase; OA, osteoarthritis; RA, rheumatoid arthritis; SDF, stromal cell-derived factor; SF, synovial fluid; RT-PCR, reverse transcription-polymerase chain reaction; PCR, polymerase chain reaction; Akt, protein kinase B; ERK, extracellular signalregulated kinase(s); AP, activator protein; p-, phosphorylated; JNK, c-Jun NH2-terminal kinase; PD98059, 2′-amino-3′-methoxyflavone; SB203580, 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole; SP600125, anthra(1,9-cd)pyrazol-6(2H)-one; Ly294002, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; PBS, phosphate-buffered saline; ODN, oligonucleotide; AS, antisense; MS, missense; ChIP, chromatin immunoprecipitation; MAPK, mitogen-activated protein kinase; TNF, tumor necrosis factor; si, small interfering, mut, mutated.
- Received March 28, 2007.
- Accepted June 4, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
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