Activation of β‐catenin in Col2‐expressing chondrocytes leads to osteoarthritis‐like defects in hip joint

Although osteoarthritis (OA) in the hip joint is a common and debilitating degenerative disease, the precise molecular mechanisms underlying its pathological process remains unclear. This study sets out to investigate whether β‐catenin plays a critical role in hip OA pathogenesis. Here, we showed overexpressed β‐catenin protein in human OA cartilage tissues. Then, we analyzed β‐cat(ex3) (Col2ER) mice, in which β‐catenin gene was conditionally activated in femoral head chondrocytes. At 2 months of age, β‐cat(ex3) (Col2ER) mice already showed a phenotype of severe cartilage degeneration in the femoral head. More changes observed in β‐cat(ex3) (Col2ER) mice with age included subchondral sclerosis and osteophyte formation along joint margins, resembling a hip OA phenotype in humans. In addition, cartilage degradation and chondrocyte apoptosis as the results of β‐catenin activation possibly contributed to this hip OA‐like phenotype. Overall our findings provide direct evidence about the importance of β‐catenin in hip OA pathogenesis.