Fig. 2
SPI1 and PERK are involved in mechanical stress-induced chondrocyte senescence. a RT-qPCR of SPI1, PERK, CDKN2A, CDKN1A mRNA expression in the chondrocytes under mechanical stress time and stress gradient (n = 6 per group). b The CCK-8 was used to assess the proliferative activity of chondrocytes under 20% mechanical stress. c, d WB and RT-qPCR analyses were performed to detect the expression of SPI1, PERK, GCN2, p16INK4A, p21, and GLB1 in chondrocytes subjected to 48 h of 20% mechanical stress (model groups). e Representative IF images of SPI1 and PERK expression in model groups and control groups. Scale bars: 50 μm. f The model groups and control groups were analyzed by β-galactosidase staining (n = 6 per group). Scale bars: 50 μm. g, h Flow cytometry (JC-1) and microscopy were used to observe the mitochondrial membrane potential of model groups and control groups. Scale bars: 50 μm. i Mitochondrial respiratory chain complexes I-IV were determined in model groups and control groups. j TEM was used to observe the morphology of mitochondria in model groups and control groups. Scale bars: 2 μm and 500 nm. The cell sample size is n = 4. Experiments were independently repeated three times. Data are expressed as mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.000 1 versus the control group. ns indicates not significant. t-test
