FAM3A protects chondrocytes against interleukin-1β-induced apoptosis through regulating PI3K/Akt/mTOR pathway

Chondrocyte death due to apoptosis is central for osteoarthritis (OA) pathogenesis. The family with sequence similarity 3A (FAM3A) is a mitochondrial protein that plays an important role for cellular adaptation to stress and cell survival. Yet, whether FAM3A is associated with chondrocyte apoptosis and OA pathogenesis remains uncharacterized. In this study, we found that FAM3A expression was downregulated in cartilage tissue from an experimental OA mouse model. Besides, FAM3A expression was also reduced in chondrocytes treated with interleukin-1β (IL-1β), an inflammatory cytokine that promotes cartilage degradation. Moreover, we discovered that FAM3A attenuated chondrocyte apoptosis induced by IL-1β treatment in vitro, suggesting a protective effect of FAM3A against chondrocyte apoptosis. Moreover, mechanistically, FAM3A activated PI3K/Akt/mTOR pathway in IL-1β-treated chondrocytes, and blockade of PI3K/Akt/mTOR pathway with specific inhibitors, wortmannin and LY294002, diminished FAM3A effect on IL-1β-induced chondrocyte apoptosis, hence demonstrating that FAM3A attenuates IL-1β-induced chondrocyte apoptosis through activating the pro-survival PI3K/Akt/mTOR pathway. In conclusion, our study may identify FAM3A as a potential regulator of chondrocyte apoptosis involved in OA pathogenesis.