Figure 5
15d-PGJ2 induces MMP-1 synthesis via HO-1 in shear-activated T/C-28a2 chondrocytes.
PGD2 (1 μg/5 μl) or 15d-PGJ2 (1 μg/5 μl) was injected to the cavity of articular cartilage of wild type mice (a). In select experiments, T/C-28a2 cells were treated with PGE2 (10 μM), forskolin (10 μM), PGD2 (1 μM) or 15d-PGJ2 (500 nM) for 48 h (b). In separate experiments, T/C-28a2 chondorcytes were transfected with HO-1 siRNA before exposing in high fluid shear stress for 48 h (c). In distinct experiments, T/C-28a2 cells were transfected with HO-1 siRNA before treating with PGD2 (1 μM) or 15d-PGJ2 (500 nM) for 48 h (d). The tissues of articular cartilage were immunostained with MMP-1 antibody (a). Phosphorylated AKT and p38 and total levels of HO-1 were detected by immunoblotting using specific Abs. Equal lane loading is demonstrated by the similar intensities of total AKT, p38 and β-actin. These western blots are representative of three independent experiments, all revealing similar results (b,c). The MMP-1 mRNA and protein levels were determined by qRT-PCR, western blots and zymography, respectively. The total amounts of GAPDH and MMP-11 served as internal controls in the qRT-PCR and zymography assays, respectively (c,d). *, p < 0.05 with respect to the static- or vehicle-treated control. #, p < 0.05 compared with the fluid shear stress, PGD2 or 15d-PGJ2 treatment.
