铁凋亡是由铁依赖性脂质过氧化引发的一种新形式的细胞死亡。最近的发现表明,抑制系统χc-诱导铁凋亡通过降低细胞内胱氨酸水平,肾小管上皮细胞(RTEC)的铁凋亡有助于急性肾损伤(AKI)和糖尿病肾病。此外,2-脱氧-d-核糖(dRib)已被证明可以通过xCT抑制胱氨酸的摄取,系统的功能单元χc-,在β细胞中。本研究旨在研究dRib是否在RTEC中诱导铁凋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,细胞内丙二醛(MDA)水平升高,4-羟基壬烯醛(4-HNE),脂质活性氧(ROS),NRK-52E细胞和原代培养的RTEC中的细胞死亡。然而,用铁性凋亡抑制剂治疗,例如去铁胺(DFO),Fer-1(Fer-1),和利丙他汀-1(Lip-1),抵消了dRib对GSH的影响,MDA,4-HNE,和脂质ROS水平,以及细胞死亡。此外,2-巯基乙醇(2-ME)处理或xCT基因过表达保护免受dRib诱导的变化。此外,透射电镜显示dRib诱导的线粒体收缩,cr数减少,和外膜破裂。此外,dRib处理上调与铁凋亡相关的基因的表达,并下调xCT蛋白表达。甚至当用蛋白质合成抑制剂环己酰亚胺处理时,也一致观察到由dRib引起的xCT蛋白质的减少。然而,蛋白酶体抑制剂MG132治疗逆转了dRib诱导的xCT蛋白表达下降.此外,dRib增加xCT蛋白泛素化。总的来说,dRib通过UPS降解xCT蛋白诱导RTEC的铁凋亡,导致细胞内胱氨酸摄取减少。因此,靶向系统χc-throughUPS的调节可能是AKI和糖尿病肾病的潜在治疗方法。
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.