Expression of MIG-6, WNT-9A, and WNT-7B during osteoarthritis.

Although the molecular mechanisms for initiation of cartilage destruction in osteoarthritis (OA) are unknown, it has been demonstrated that disruption of mitogen-inducible gene 6 (Mig-6) in mice leads to the onset of a degenerative joint disease like OA. On this basis, we correlated gene expression of Mig-6 with Wnt-9a and Wnt-7b genes; we showed downregulation of Mig-6, Wnt-7b, and Wnt-9a during OA, while Wnt-7b was expressed also in osteoblast-like cells. Here we suggest that Aggrecan degradation occurs before the downregulation of Mig-6. It remains to be proven whether there is any relation between Wnt signaling and Aggrecan degradation.