Gsmtx4 Alleviated Osteoarthritis through Piezo1/Calcineurin/NFAT1 Signaling Axis under Excessive Mechanical Strain.

Excessive mechanical strain is the prominent risk factor for osteoarthritis (OA), causing cartilage destruction and degeneration. However, the underlying molecular mechanism contributing to mechanical signaling transduction remains unclear in OA. Piezo type mechanosensitive ion channel component 1 (Piezo1) is a calcium-permeable mechanosensitive ion channel and provides mechanosensitivity to cells, but its role in OA development has not been determined. Herein, we found up-regulated expression of Piezo1 in OA cartilage, and that its activation contributes to chondrocyte apoptosis. The knockdown of Piezo1 could protect chondrocytes from apoptosis and maintain the catabolic and anabolic balance under mechanical strain. In vivo, Gsmtx4, a Piezo1 inhibitor, markedly ameliorated the progression of OA, inhibited the chondrocyte apoptosis, and accelerated the production of the cartilage matrix. Mechanistically, we observed the elevated activity of calcineurin (CaN) and the nuclear transfection of nuclear factor of activated T cells 1 (NFAT1) under mechanical strain in chondrocytes. Inhibitors of CaN or NFAT1 rescued the pathologic changes induced by mechanical strain in chondrocytes. Overall, our findings revealed that Piezo1 was the essential molecule response to mechanical signals and regulated apoptosis and cartilage matrix metabolism via the CaN/NFAT1 signaling axis in chondrocytes, and that Gsmtx4 could be an attractive therapeutic drug for OA treatment.