2-脱氧-d-核糖通过泛素-蛋白酶体系统介导的 xCT 蛋白降解诱导肾小管上皮细胞发生铁死亡。

2-Deoxy-d-ribose induces ferroptosis in renal tubular epithelial cells via ubiquitin-proteasome system-mediated xCT protein degradation.

机构信息

Department of Internal Medicine, Jeju National University College of Medicine, 15 Aran 13-gil, Jeju, 63241, Republic of Korea; Deparment of Internal Medicine, Jeju National University Hospital, 15 Aran 13-gil, Jeju, 63241, Republic of Korea.

Department of Internal Medicine, Jeju National University College of Medicine, 15 Aran 13-gil, Jeju, 63241, Republic of Korea.

出版信息

Free Radic Biol Med. 2023 Nov 1;208:384-393. doi: 10.1016/j.freeradbiomed.2023.08.027. Epub 2023 Sep 1.

Abstract

Ferroptosis is a novel form of cell death triggered by iron-dependent lipid peroxidation. Recent findings suggest that inhibiting system χc-induces ferroptosis by reducing intracellular cystine levels, and that ferroptosis in renal tubular epithelial cells (RTECs) contributes to acute kidney injury (AKI) and diabetic nephropathy. Moreover, 2-deoxy-d-ribose (dRib) has been shown to inhibit cystine uptake through xCT, the functional unit of system χc-, in β-cells. This study aimed to investigate if dRib induces ferroptosis in RTECs and identify the underlying mechanisms. dRib treatment reduced cystine uptake and glutathione (GSH) content, and increased intracellular levels of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), lipid reactive oxygen species (ROS), and cell death in both NRK-52E cells and primary cultured RTECs. However, treatment with inhibitors of ferroptosis, such as deferoxamine (DFO), ferrostatin-1 (Fer-1), and liproxstatin-1 (Lip-1), counteracted the effects of dRib on GSH, MDA, 4-HNE, and lipid ROS levels, as well as cell death. Additionally, 2-mercaptoethanol (2-ME) treatment or xCT gene overexpression protected against dRib-induced changes. Moreover, transmission electron microscopy revealed dRib-induced mitochondrial shrinkage, decrease in cristae number, and outer membrane rupture. Furthermore, dRib treatment upregulated the expression of genes associated with ferroptosis, and downregulated xCT protein expression. The decrease in xCT protein caused by dRib was consistently observed even when treated with the protein synthesis inhibitor cycloheximide. However, treatment with the proteasome inhibitor MG132 reversed the dRib-induced decrease in xCT protein expression. Additionally, dRib increased xCT protein ubiquitination. Overall, dRib induces ferroptosis in RTECs by degrading xCT protein through ubiquitin-proteasome system (UPS), resulting in reduced intracellular cystine uptake. Therefore, targeting the regulation of system χc-through UPS could be a potential therapeutic approach for AKI and diabetic nephropathy.

摘要

铁死亡是一种新型的细胞死亡方式,由铁依赖性脂质过氧化引发。最近的研究表明,抑制系统 χc 通过降低细胞内半胱氨酸水平诱导铁死亡,肾小管上皮细胞 (RTECs) 中的铁死亡导致急性肾损伤 (AKI) 和糖尿病肾病。此外,2-脱氧-D-核糖 (dRib) 已被证明可通过系统 χc 的功能单位 xCT 抑制半胱氨酸摄取。本研究旨在探讨 dRib 是否会诱导 RTECs 发生铁死亡,并确定其潜在机制。dRib 处理降低了胱氨酸摄取和谷胱甘肽 (GSH) 含量,并增加了丙二醛 (MDA)、4-羟基壬烯醛 (4-HNE)、脂质活性氧 (ROS) 和 NRK-52E 细胞和原代培养的 RTECs 中的细胞死亡。然而,用铁死亡抑制剂(如去铁胺 (DFO)、Fer-1 和 Lip-1)处理可逆转 dRib 对 GSH、MDA、4-HNE 和脂质 ROS 水平以及细胞死亡的影响。此外,2-巯基乙醇 (2-ME) 处理或 xCT 基因过表达可防止 dRib 诱导的变化。此外,透射电子显微镜显示 dRib 诱导线粒体收缩、嵴数量减少和外膜破裂。此外,dRib 处理上调了与铁死亡相关的基因表达,并下调了 xCT 蛋白表达。即使在用蛋白合成抑制剂环己酰亚胺处理时,也始终观察到 dRib 引起的 xCT 蛋白表达减少。然而,用蛋白酶体抑制剂 MG132 处理可逆转 dRib 诱导的 xCT 蛋白表达减少。此外,dRib 增加了 xCT 蛋白的泛素化。总的来说,dRib 通过泛素-蛋白酶体系统 (UPS) 降解 xCT 蛋白诱导 RTEC 中铁死亡,导致细胞内半胱氨酸摄取减少。因此,通过 UPS 靶向调节系统 χc 可能是 AKI 和糖尿病肾病的一种潜在治疗方法。

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