Figure 4

Effects of sodium ferulate on the IKK/NF-κB signaling pathway of rat osteoarthritis chondrocytes. Effects of sodium ferulate (SF) on the TNF/TNF receptor (TNFR)-mediated IKK/NF-κB signaling pathway of rat osteoarthritis (OA) chondrocytes induced by IL-1β. (a) Effects of SF on protein expression of TNF receptor-associated factor 2 (TRAF-2), inhibitor of NF-κB kinase (IKK) subunit alpha (IKKα), IKK subunit beta (IKKβ), NF-κB light polypeptide gene enhancer in B-cell inhibitor, alpha (IκBα), phosphorylation of IKKα (p-IKKα), phosphorylation of IKKβ (p-IKKβ), phosphorylation of IκBα (p-IκBα) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in rat OA chondrocytes. Chondrocytes were incubated with SF alone for 24 hours, and then co-treated with IL-1β and SF for 48 hours. Expressions of proteins determined by western blotting. (b, c, d, e) Relative level of TRAF-2, IKKα, IKKβ, IκBα, p-IKKα, p-IKKβ and p-IκBα normalized to GAPDH and compared with normal control, quantitatively analyzed by Kodak Digital Science 1D software (Eastman Kodak, Rochester, NY, USA) and expressed as mean optical density. Values represent mean ± standard error of the mean of three different simples. **P < 0.01 versus normal control. ^##P < 0.01 versus OA model control. (f) Effects of SF on activity of NF-κB in rat OA chondrocytes. Nuclear extracts were incubated with biotin-labeled double-stranded oligonucleotide probes. Reactions were fractionated on nonreducing 6.5% polyacrylamide gel and transferred to nylon membranes, then incubated with streptonuclide-horseradish peroxidase and visualized. NS, nonspecific free DNA band.