NCOA4 介导的铁蛋白自噬促进依马替尼诱导的铁死亡,但不促进 RSL3 诱导的铁死亡。
NCOA4-mediated ferritinophagy promotes ferroptosis induced by erastin, but not by RSL3 in HeLa cells.
机构信息
Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123 Brescia, Italy.
出版信息
Biochim Biophys Acta Mol Cell Res. 2021 Feb;1868(2):118913. doi: 10.1016/j.bbamcr.2020.118913. Epub 2020 Nov 25.
Ferroptosis is a regulated cell death characterized by a lethal accumulation of lipid peroxides due to an increase of intracellular iron and a decrease of antioxidant capacity. The reduction of antioxidant activity is obtained by using chemical agents, such as erastin and RSL3, the first one inhibiting the transmembrane cystine-glutamate antiporter causing a cysteine and glutathione depletion and the second one inactivating directly the glutathione peroxidase 4 (GPX4) respectively. The role of iron and its related proteins in supporting the formation of lipid peroxides, is not completely understood hence to try to shed light on it we generated HeLa clones with altered ferritinophagy, the ferritin degradation process, by knocking-out or overexpressing Nuclear Receptor Coactivator 4 (NCOA4), the ferritin autophagic cargo-receptor. NCOA4 deficiency abolished ferritinophagy increasing ferritin level and making the cells more resistant to erastin, but unexpectedly more sensitive to RSL3. Interestingly, we found that erastin promoted ferritinophagy in HeLa cells expressing NCOA4, increasing the free iron, lipid peroxidation and the sensitivity to ferroptosis. In contrast, RSL3 did not modulate ferritinophagy, while NCOA4 overexpression delayed RSL3-induced cell death suggesting that RSL3 mechanism of action is independent of ferritin degradation process. Therefore, the ferritin-iron release in the execution of ferroptosis seems to depend on the inducing compound, its target and downstream pathway of cell death activation.
铁死亡是一种受调控的细胞死亡形式,其特征是由于细胞内铁的增加和抗氧化能力的降低,导致脂质过氧化物的致命积累。抗氧化活性的降低是通过使用化学剂来实现的,例如 erastin 和 RSL3,前者抑制跨膜半胱氨酸-谷氨酸反向转运体,导致半胱氨酸和谷胱甘肽耗竭,后者直接使谷胱甘肽过氧化物酶 4 (GPX4)失活。铁及其相关蛋白在支持脂质过氧化物形成中的作用尚未完全清楚,因此,为了阐明这一点,我们通过敲除或过表达核受体共激活因子 4 (NCOA4),即铁蛋白自噬货物受体,生成了 HeLa 克隆,改变了铁蛋白的自噬降解过程。NCOA4 缺乏会抑制铁蛋白自噬,增加铁蛋白水平,使细胞对 erastin 的耐药性增强,但出人意料的是对 RSL3 更为敏感。有趣的是,我们发现 erastin 促进了表达 NCOA4 的 HeLa 细胞中的铁蛋白自噬,增加了游离铁、脂质过氧化和对铁死亡的敏感性。相比之下,RSL3 并没有调节铁蛋白自噬,而 NCOA4 的过表达则延迟了 RSL3 诱导的细胞死亡,这表明 RSL3 的作用机制独立于铁蛋白降解过程。因此,铁蛋白-铁的释放似乎取决于诱导化合物、其靶标和细胞死亡激活的下游途径,在铁死亡的执行中起作用。