Fig. 2

Trichostatin A (TSA) activates nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and suppresses matrix metalloproteinase (MMP) expression in human chondrocytes. a SW1353 chondrosarcoma cells were treated with various doses of TSA for 16 h. Heme oxygenase 1 (HO-1), NAD(P)H:quinine oxidoreductase 1 (NQO1), and acetylated histone 3 (ac-H3) were assayed by Western blotting. β-actin and total histone 3 were used as loading controls. b Quantitative analysis of HO-1 and NQO1 protein levels. *p < 0.05 compared with control. c SW1353 chondrosarcoma cells were treated with TSA (10 nM) for various times. HO-1 and NQO1 were assayed by Western blotting. d SW1353 chondrosarcoma cells were treated with TSA (10 nM) for 4 h. The cell cytoplasmic and nuclear fractions were isolated and assayed for Nrf2 by Western blotting. β-actin, total Nrf2, and lamin B from total cell lysates served as controls. e Quantitative analysis of cytoplasmic and nuclear Nrf2 from (d). *p < 0.05 compared with no-treatment controls. f HEK293 cells were transiently transfected with HO-1 promoter reporter plasmid and a Renilla luciferase plasmid for 24 h. The cells were then treated with 10 nM and 30 nM of TSA for 24 h. The luciferase activity was measured. The reporter luciferase activities were normalized to Renilla luciferase activity. *p < 0.05, **p < 0.01 compared with no-treatment control. g SW1353 chondrosarcoma cells were treated with increasing concentrations of TSA for 1 h and then stimulated with interleukin (IL)-1β (5 ng/ml) for 16 h. MMP-1, MMP-3, and MMP-13 were assayed by RT-PCR. h MMP-1, MMP-3, and MMP-13 were assayed by Western blotting. i Quantitative analysis of MMP-1, MMP-3, and MMP-13 levels from (h). *p < 0.05 compared with IL-1β treatment only. All the Western blotting and RT-PCR results are representative of, and the statistical analyses were performed with results from, at least three independent experiments