FIGURE 1.

Pathogenesis in OA related to GPCRs. Different GPCRs are widely expressed on various cells and play a key role in transmembrane signal transmission. Extracellular stimuli initiate a series of intracellular signaling pathways by activating GPCRs, leading to a variety of physiological and pathological processes, such as cartilage matrix degradation, synovial inflammation, subchondral bone remodeling, osteophyte formation, chondrocyte hypertrophy, cartilage angiogenesis, and chondrocyte apoptosis. These processes greatly promote the occurrence and progression of OA.