铁死亡是一种由脂质过氧化积累引起的铁依赖性程序性细胞死亡(PCD)。转铁蛋白受体 (TFRC) 是铁死亡的标志蛋白之一,在肝细胞癌 (HCC) 中大量表达。然而,TFRC 的翻译后修饰 (PTM) 和铁死亡调节的潜在机制仍知之甚少。在这项研究中,我们发现 TFRC 发生 O-GlcNAc 酰化,影响肝细胞中 Erastin 诱导的铁死亡敏感性。进一步的机制研究发现,Erastin 可以触发 TFRC 在丝氨酸 687 (Ser687) 处的去-O-GlcNAcylation,从而减少泛素 E3 连接酶膜相关的 RING-CH8 (MARCH8) 的结合,并减少赖氨酸 665 (Lys665) 上的多泛素化,从而增强 TFRC 稳定性,有利于不稳定铁的积累。因此,我们的研究结果报告了铁死亡的重要调节蛋白上的O-GlcNAc糖基化,并揭示了铁代谢途径控制HCC铁死亡的有趣机制。
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O-GlcNAcylation regulates the stability of transferrin receptor (TFRC) to control the ferroptosis in hepatocellular carcinoma cells
Ferroptosis is an iron-dependent programmed cell death (PCD) enforced by lipid peroxidation accumulation. Transferrin receptor (TFRC), one of the signature proteins of ferroptosis, is abundantly expressed in hepatocellular carcinoma (HCC). However, post-translational modification (PTM) of TFRC and the underlying mechanisms for ferroptosis regulation remain less understood. In this study, we found that TFRC undergoes O-GlcNAcylation, influencing Erastin-induced ferroptosis sensitivity in hepatocytes. Further mechanistic studies found that Erastin can trigger de-O-GlcNAcylation of TFRC at serine 687 (Ser687), which diminishes the binding of ubiquitin E3 ligase membrane-associated RING-CH8 (MARCH8) and decreases polyubiquitination on lysine 665 (Lys665), thereby enhancing TFRC stability that favors labile iron accumulation. Therefore, our findings report O-GlcNAcylation on an important regulatory protein of ferroptosis and reveal an intriguing mechanism by which HCC ferroptosis is controlled by an iron metabolism pathway.