Fig. 8: AGEs regulate meniscal calcification by activating the mTOR-ATF4-positive feedback loop.

a, c Human primary meniscal cells were treated with the indicated drugs during osteogenic induction; Alizarin Red staining was used to detect osteogenic differentiation. b, d Quantification of Alizarin Red staining; n = 3. e Human primary meniscal cells were treated with the indicated drugs for 24 h; WB analysis of Ub and ATF4 was performed using proteins isolated from the ATF4 immunoprecipitate or total lysate. f Quantification of the WB data; n = 3. g Human primary meniscal cells were treated with the indicated drugs during osteogenic induction, and relative quantification of the intracellular arginine concentration was performed via ELISA; n = 3. O.I., osteogenic induction (21 days). The data are expressed as the mean ± SD; *P < 0.05; **P < 0.01; and ***P < 0.001. One-way ANOVA was used for comparisons.