Fig. 6

NF-κB and c-Jun are identified as the essential transcriptional factor for MMP-12 synthesis in shear-activated human chondrocytes. a and b T/C-28a2 cells were transfected with mmp-12 promoter expression plasmids or mutation constructs before being subjected to fluid shear stress (20 dyn/cm²) for 6 h. Luciferase activities, normalized to Renilla luciferase activities, were measured using the Dual-Luciferase Reporter Assay Kit. c and d In select experiments, nuclear extracts were isolated, and NF-κB and c-Jun-specific DNA-protein complex formation was determined by EMSA. e and f In separate experiments, cross-linked chromatin was immunoprecipitated using an anti-p65 or anti-c-Jun antibody. In ChIP assays, the anti-RNA polymerase II antibody was used as a positive control. DNAs purified from both immunoprecipitated (IP) and preimmune (Input) specimens were subjected to qPCR amplification using primers for mm-12 promoter genes. Data represent the mean ± SE of at least three independent experiments. * p < 0.05 compared with static or vehicle treatment control. ^# p < 0.05 with respect to shear stress or PGE₂ treatment specimens