镉通过诱导自噬促进肾小管上皮细胞铁死亡的研究

Cadmium promotes ferroptosis in renal tubular epithelial cells by inducing autophagy

目的 研究铁自噬诱导的铁死亡在镉(cadmium, Cd)暴露致肾小管上皮细胞毒性中的作用。方法 采用HK-2细胞构建镉暴露模型,观察CdCl_(2)处理后细胞铁死亡、自噬、铁自噬及细胞毒性的影响。同时抑制铁死亡、自噬及铁自噬并观察其对细胞毒性的影响。结果 镉以剂量依赖性方式诱导肾小管上皮细胞铁死亡,铁死亡标志物长链脂酰CoA合成酶(Acyl-CoA synthetase long chain family member 4, ACSL4)水平升高,谷胱甘肽过氧化物酶4(glutathione peroxidase 4, GPX4)水平降低;脂质过氧化作用抑制剂ferrastatin-1(Fer-1)和铁离子螯合剂去铁胺(deferroamine, DFO)可减轻Cd诱导的肾小管上皮细胞死亡;镉诱导肾小管上皮细胞自噬,自噬小体数量增加,自噬标志物LC3B-Ⅱ表达增加;抑制自噬减轻镉诱导的肾小管上皮细胞铁死亡;此外,镉诱导肾小管上皮细胞铁自噬,铁自噬标志物核受体共同活化子4(nuclear receptor coactivator 4, NCOA4)表达增加,铁自噬底物铁蛋白重链多肽1 (ferritin heavy chain 1, FTH)表达降低;NCOA4敲除抑制了镉诱导的储铁蛋白降解及细胞死亡。结论 铁自噬介导的铁死亡参与了镉诱导的肾小管上皮细胞死亡。

Objective To investigate the role of ferritinophagy-mediated ferroptosis in renal tubular epithelial cytotoxicity induced by cadmium (Cd) exposure. Methods HK-2 cells were used to construct Cd exposed cell model, and the effects of Cd on ferroptosis, autophagy, ferritinophagy and cytotoxicity were observed. Meanwhile, the effects of inhibition of ferroptosis, autophagy and ferritinophagy on Cd cytotoxicity were evaluated. Results Cd induced ferroptosis in renal tubular epithelial cells in a dose-dependent manner, and the level of acyl-CoA synthetase long chain family member 4 (ACSL4) was increased and that of glutathione peroxidase 4 (GPX4) was decreased. Treatment of lipid peroxidation inhibitor ferrastatin-1 (Fer-1) and iron chelating agent deferroamine (DFO) attenuated Cd-induced death in renal tubular epithelial cells. Cd induced renal tubular epithelial cell autophagy, increased the number of autophagosomes, and enhanced the expression of autophagy marker LC3B-Ⅱ. Inhibition of autophagy alleviated Cd-induced ferroptosis in renal tubular epithelial cells. In addition, Cd induced ferritinophagy in renal tubular epithelial cells, and the expression of ferritinophagy marker nuclear receptor coactivator 4 (NCOA4) was elevated, while the expression of ferritin heavy chain 1(FTH), substrate of ferritinophagy, was decreased. NCOA4 knockdown inhibited Cd-induced ferritin degradation and cell death. Conclusion Ferritinophagy-mediated ferroptosis is involved in Cd-induced renal tubular epithelial cell death.