Transcriptional regulation of the mPGES-1 gene in primary cultured articular chondrocytes

  • P Bausero1,

    Affiliated with

    • C Salvat1,

      Affiliated with

      • V Meynier de Salinelles1,

        Affiliated with

        • A Pigenet1,

          Affiliated with

          • M Raymondjean1 and

            Affiliated with

            • F Berenbaum1

              Affiliated with

              Arthritis Res Ther20046(Suppl 3):10

              DOI: 10.1186/ar1344

              Published: 13 September 2004

               

              Healthy cartilage is maintained in a state of dynamic equilibrium by matrix synthesis and matrix degradation by the chondrocytes. Any dysregulation with increased degradation and/or inadequate synthesis leads to the loss of tissue structure and function, as in rheumatoid arthritis and osteoarthritis. The proinflammatory cytokine IL-1 plays a major role in this phenomenon. IL-1 acts on chondrocytes in part by stimulating the release of prostaglandin E2 (PGE2) at the sites of inflammation. Recently, a human membrane-associated prostaglandin E2 synthase-1 (mPGES-1) was cloned. This enzyme catalyzes the conversion of prostaglandin H2 to PGE2 in a highly specific manner. We previously demonstrated that mPGES-1 mRNA is induced by IL-1 in chondrocytes in a dose-dependent and time-dependent manner.

              In order to study the transcriptional regulation of mPGES-1 in primary rabbit articular chondrocytes, we have cloned its promoter upstream of the CAT ORF (vector pCAT3-basic; Promega, Charbonnièresles-Bains, France). We show by transient transfection experiments that the mPGES-1 promoter is stimulated by IL-1. A close examination of putative binding sites has revealed the presence of two CCAAT/Enhancer Binding Protein (C/EBP) binding sequences (TTNNGNAAT) located between -548 to -558 base pairs and -610 to -619 base pairs. Co-transfections of expression vectors encoding the two different isoforms of C/EBP (β and δ) strongly stimulate the promoter activity. To further study the role of C/EBP in mPGES-1 expression, we performed gel shift experiments on wild-type and mutated oligonucleotides derived from the mPGES-1 sequence. These experiments confirm the specific binding of C/EBP on the mPGES-1 promoter. Taken together, our results suggest that C/EBP factors indeed bind and regulate the mPGES promoter in articular chondrocytes.

              Authors’ Affiliations

              (1)
              University Paris 6 Pierre & Marie Curie, UMR 7079 CNRS

              Copyright

              © BioMed Central Ltd 2004

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