Fig. 3.

Blockade of TRPM7 ion channel function protected against chondrocyte ferroptosis through a Ca²⁺-dependent mechanism. (A, B) Visualization and TEM of indicated TRPM7 KD C28/I2 cells treated with erastin (2.5 μM, 12 h). Orange triangles indicate mitochondria. (C) Cell viability, LDH release and GSH in indicated TRPM7 KD C28/I2 cells (n = 3–10). (D) Western blot analysis for ACSL4, COX2, SLC7A11, FTH and GPX4 in indicated TRPM7 KD C28/I2 cells (n = 3). Data are means ± SD. *P < 0.05, **P < 0.01, Control KD + erastin versus Control KD; ^#P < 0.05, ^##P < 0.01, TRPM7 KD + erastin versus Control KD + erastin. (E) Representative original traces of Ca²⁺ influx mediated by TRPM7 channels in RACs using Fluo-4 AM Ca²⁺ imaging. (F) Ca²⁺ dynamics were monitored using Fluo-4 AM in RACs following exposure to erastin (5 μM) and 2-APB (100 μM). (G, H) Cell viability, LDH release and GSH of RACs treated with/without erastin and EGTA (2 mM) (n = 3–4). (I) Measurement of ΔΨm by Rh123 in RACs in different treatment groups. (J) Lipid ROS production was assessed by C11-BODIPY in RACs (n = 3). (K) Western blot analysis for ACSL4, NOX4, FTH and GPX4 in RACs (n = 3). Data are means ± SD. *P < 0.05, **P < 0.01 erastin versus control; ^#P < 0.05, ^##P < 0.01 erastin + EGTA versus erastin. (L) Cell viability and LDH release of RACs treated with/without erastin and different concentrations of TG100-115 for 24 h (n = 3–4). Data are means ± SD. **P < 0.01 erastin versus control; ^##P < 0.01 erastin + TG100-115 versus erastin. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)