Fig. 7.

Analysis of matrix metalloproteinase expression during osteoarthritis progression. Total RNA from the articular cartilage layer was isolated 10 and 17 days after osteoarthritis (OA) induction by detaching the medial meniscus (DMM), and expression of the matrix metalloproteinase 3 (Mmp3) (a) and Mmp13 (b) was analyzed by quantitative RT-PCR. (A) Mmp3 mRNA expression was approximately identical in all sham joints (S) at both time points, and only a minor induction could be detected in the DMM joints compared with the sham joints. (b) In contrast, a significant higher basal level of Mmp13 expression could be detected in the sham joints of the Tfap2e ^−/− mice compared with the sham joints of the wild-type (WT) mice at both time points. In addition, the expression of Mmp13 was significantly upregulated in the DMM joints compared with the sham joints 17 days after OA induction in both genotypes. In combination with the higher basal expression rate, this resulted in a significantly increased total Mmp13 expression level in articular chondrocytes of the Tfap2e ^−/− mice at day 17 after OA onset. The data are given as the means ± standard error of the mean. ns, Not significant; Tfap2e ^−/−, Deficient for activating enhancer binding protein 2, epsilon. *P < 0.05; **P < 0.01. Five to eight animals were used for each group