Figure 2.

Effects of recombinant PGRN on chondrocytes anabolism and SIRT1 expression. Chondrocytes isolated from newborn Sprague-Dawley rat articular cartilage were cultured in the presence of graded concentrations of recombinant PGRN (0–200ng/ml) for 48 h. a, at the end of the culture period, col2a1 mRNA level was examined by real-time PCR. One-way ANOVA and Dunnett's multiple comparison test. b, quantification of secreted COL2A1 in the conditioned medium of chondrocytes treated with PGRN. One-way ANOVA and Dunnett's multiple comparison test. c and d, aggrecan expression and secretion were detected by real-time PCR and ELISA, respectively. One-way ANOVA and Dunnett's multiple comparison test. e, COL2A1 and aggrecan protein expression were detected by Western blotting. f–h, the expression and activity of SIRT1 in chondrocytes treated with PGRN. One-way ANOVA and Dunnett's multiple comparison test. Chondrocytes transfected with control siRNA or SIRT1 siRNA cultured in the absence or presence of 100 ng/ml PGRN. SIRT1i-1, SIRT1i-2, and SIRT1i-3 indicate three independent siRNAs against SIRT1. i–j, the protein and mRNA level of SIRT1 were detected by Western blotting and real-time PCR. One-way ANOVA and Tukey's multiple comparison test. k and l, COL2A1 expression and secretion were detected by real-time PCR and soluble collagen quantification assay. One-way ANOVA and Tukey's multiple comparison test. m and n, aggrecan expression and secretion were detected by real-time PCR and ELISA. One-way ANOVA and Tukey's multiple comparison test. o, the protein levels of COL2A1 and aggrecan were analyzed by Western blotting. Data were expressed as mean ± S.D. in each scatterplot. *, p < 0.05; **, p < 0.01; ***, p < 0.001.