Blockade of ASIC1a inhibits acid-induced rat articular chondrocyte senescence through regulation of autophagy.

Acid-sensitive ion channel 1a (ASIC1a), which is abundant in chondrocytes, can sense changes in extracellular acidification. Our previous data demonstrated that ASIC1a is involved in acid-induced rat articular chondrocyte damage in osteoarthritis; however, its specific mechanisms remain unclear. The present study aims to explore the role of ASIC1a in rat articular chondrocyte senescence. RNA-seq transcriptome analysis identified senescence-associated secretory phenotype and matrix metalloproteinases genes were overexpressed by extracellular acidification (pH 6.0) in rat articular chondrocytes. An increase in senescence-associated β-galactosidase and senescence-related markers p16, p21 and p53 was observed in the pH 6.0-treated group compared with the control group. Acid-induced senescence-related markers could be blocked by the ASIC1a-specific inhibitor psalmotoxin-1 in rat articular chondrocytes and human immortalized C28/I2 chondrocyte cell lines. Moreover, our results showed that extracellular acidification increased autophagosomes and the autophagy-related proteins LC3B-II and Beclin-1; these effects could also be reversed by psalmotoxin-1 treatment, indicating ASIC1a participated in acid-induced chondrocyte autophagy. Blocking ASIC1a-mediated autophagy with chloroquine also inhibited senescence-related markers, decreased ROS expression, and restored cell membrane potential induced by pH 6.0 treatment. Taken together, these findings suggested that ASIC1a may be involved in acid-induced rat articular chondrocyte senescence by activating autophagy, which provides a potential therapeutic strategy for the treatment of osteoarthritis.