Retinoic Acid Receptor Gamma (RARγ) Promotes Cartilage Destruction through Positive Feedback Activation of NF-κB Pathway in Human Osteoarthritis

Figure 2

TNF-α promoted the expression of RARγ by activating NF-κB signaling pathway. (a,b) The 24 hours supernatant of synovial fibroblasts from healthy human and OA patients was cocultured with normal chondrocyte C28/I2 for 24 hours, respectively. Then, the activation of NF-κB signaling pathway and the expression of RARγ in C28/I2 cells were detected by western blot (a) and qRT-PCR (b). (c) The expression of TNF-α in synovial fibroblasts of healthy persons and OA patients was detected by qRT-PCR. (d) After C28/I2 cells were treated with TNF-α (30 ng/mL) or IKK inhibitor BMS-345541 (10 μm) at different time points, the expression of RARγ and NF-κB signaling pathway were examined by western blot. (e,f) After the C28/I2 cells were treated with TNF-α (30 ng/mL) and BMS-345541 (10 μm) separately or in combination, changes in NF-κB signaling pathway and the expression of RARγ in C28/I2 cells were detected by western blot and qRT-PCR. (g) HEK-293 cells were transfected with RARγ promoter reporter plasmid and pRL-TK reporter internal reference plasmid; the fluorescence intensity of renilla (RL) and firefly (FL) was detected after 4 hours of treatment with TNF-α (30 ng/mL) and BMS-345541 (10 μm), respectively, or in combination, and the values were normalized. Data were of three independent assays (; ; and ).

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