Figure 3.

TNFα regulates cartilage-selective matrix genes and proteinases in a MEK1/2-dependent manner. Chondrocytes were pretreated with dimethyl sulfoxide, U0124 (10 μM) or U0126 (10 μM) for 30 minutes prior to treatment with TNFα for 24 hours. Total mRNA was collected and analysed for (a) aggrecan (Agc1), (b) link protein (Hapln1), (c) type II collagen (Col2a1), (d) macrophage colony-stimulating factor 1 (Csf-1), (e) matrix metalloproteinase-12 (Mmp-12) and (f) matrix metalloproteinase-9 (Mmp-9), and 18S transcript levels by quantitative real-time PCR. (a) to (f) Data were analysed by the ΔΔCT method to acquire matrix gene transcript levels relative to 18S transcript levels and were normalized to DMSO-treated cells. Data were log-transformed prior to analysis by one-way analysis of variance followed by Tukey's post-hoc tests. Unlabelled bars or bars labelled with the same lowercase letter are not significantly different (P > 0.05). Data are expressed as the mean ± standard error of five independent experiments – except (c), four independent experiments. MEK, mitogen-activated kinase kinase.