摘要目的:探究核受体亚家族4 A组成员1（nuclear receptor subfamily 4 group A member 1， NR4A1）在缓解顺铂对近端肾小管上皮细胞毒性的作用及其分子机制。 方法:通过“Tabula-muris”单细胞转录组测序数据库分析肾脏组织各细胞亚群 NR4A1基因的表达。在近端肾小管上皮细胞HK-2细胞系及原代细胞中，通过慢病毒感染以过表达 NR4A1基因。采用细胞增殖与毒性检测试剂盒（cell counting kit-8，CCK-8）检测顺铂的细胞毒性。细胞用碘化丙啶（propidium iodide，PI）单染后通过流式细胞仪检测细胞的死亡比例。通过实时荧光定量PCR和Western印迹法检测细胞中 NR4A1和核因子E2相关因子2（nuclear factor erythroid 2-related factor 2， NRF2）基因的表达。通过检测丙二醛（malondialdehyde，MDA）和氧化型谷胱甘肽（oxidized glutathione，GSSG）以及脂质活性氧（reactive oxygen species，ROS）的含量分析细胞铁死亡程度。 结果:单细胞转录组数据分析的结果表明 NR4A1基因表达在肾脏组织的近端肾小管上皮细胞亚群中最低。50 μmol/L和100 μmol/L顺铂能够显著诱导近端肾小管上皮细胞MDA、GSSG和脂质ROS含量的上升（均 P<0.01），且顺铂浓度越高诱导MDA、GSSG和脂质ROS增加越多。相比对照HK-2细胞，过表达 NR4A1的HK-2细胞脂质ROS含量及铁离子含量显著较低（均 P<0.01），过表达 NR4A1抑制了顺铂对近端肾小管上皮细胞的毒性及其诱导的铁死亡。分子机制研究发现，在近端肾小管上皮细胞中，过表达 NR4A1上调了抗铁死亡基因 NRF2的表达（ P<0.01）。进一步单细胞转录组数据分析的结果表明，与 NR4A1在肾脏组织细胞亚群的表达状态相似， NRF2表达在近端肾小管上皮细胞中也最低。 结论:顺铂能够诱导近端肾小管上皮细胞发生铁死亡，且浓度越高越明显。 NR4A1通过上调近端肾小管上皮细胞 NRF2的表达抑制顺铂诱导的细胞铁死亡，从而缓解顺铂对细胞的毒性。

abstractsObjective:To explore the role and mechanism of nuclear receptor subfamily 4 group A member 1 ( NR4A1) in suppressing cisplatin nephrotoxicity. Methods:The expression of NR4A1 gene in renal cell subpopulations was analyzed using the "Tabula-muris" single cell transcriptome sequencing database. NR4A1 gene was over-expressed by lentivirus infection in HK-2 cell line and primary renal proximal tubular epithelial cells. Cell counting kit-8 was used to detect the cytotoxicity of cisplatin. The cell death ratio was analyzed using propidium iodide (PI) staining by flow cytometry. The expression of NR4A1 and nuclear factor erythroid 2-related factor 2 ( NRF2) was detected by real-time fluorescent quantitative PCR and Western blotting. Ferroptosis was analyzed by detecting the contents of malondialdehyde (MDA), oxidized glutathione (GSSG) and lipid reactive oxygen species (ROS). Results:The single cell transcriptome sequencing database showed that NR4A1 gene was the lowest expression in renal proximal tubular epithelial cell subsets. Cisplatin (50 μmol/L or 100 μmol/L) could significantly induce MDA, GSSG and lipid ROS production in renal proximal tubular epithelial cells (all P<0.01), and higher cisplatin concentration accompanied with a more increase of MDA, GSSG and lipid ROS. Compared with the control HK-2 cells, the lipid ROS content and iron ion content of HK-2 cells over-expressing NR4A1 were significantly lower (all P<0.01), and the over-expression of NR4A1 inhibited cisplatin-induced cytotoxicity and ferroptosis in renal proximal tubular epithelial cells. Mechanistically, NR4A1 up-regulated the expression of anti-ferroptosis gene NRF2 in proximal renal tubular epithelial cells ( P<0.01). Furthermore, single cell data analysis showed that, similar to the expression of NR4A1 in renal tissue subsets, NRF2 was also the lowest in renal proximal tubular epithelial cells. Conclusions:Cisplatin can induce ferroptosis of renal proximal tubular epithelial cells in a dose-dependent manner. NR4A1 can inhibit cisplatin-induced ferroptosis by up-regulating NRF2 in renal proximal tubular epithelial cells, thereby alleviating the cytotoxicity of cisplatin.