The roles of the Hippo-YAP signalling pathway in Cartilage and Osteoarthritis

Osteoarthritis (OA) is an age-related disease, characterized by cartilage degeneration. The pathogenesis of OA is complicated and the current therapeutic approaches for OA are limited. Cartilage, an integral part of the skeletal system composed of chondrocytes, is essential for skeletal development, tissue patterning, and maintaining the normal activity of joints. The development, homeostasis and degeneration of cartilage are tightly associated with OA. Over the past decade, accumulating evidence indicates that Hippo/YAP is a vital biochemical signalling pathway that strictly governs tissue development and homeostasis. The joint tissues, especially for cartilage, are sensitive to changes of Hippo/YAP signalling. In this review, we summarize the role of Hippo/YAP signalling in cartilage and discuss its involvement in OA progression from points of cartilage degradation, subchondral bone remodeling, and synovial alteration. We also highlight the potential therapeutic implications of Hippo/YAP signalling and further discuss current limitations and controversy on Hippo/YAP-based application for OA treatment.