Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
Department of Nephrology, The First Medical Center of Chinese PLA General Hospital, Nephrology Institute of the Chinese People's Liberation Army, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Beijing Key Laboratory of Kidney Disease Research, Beijing 100853, China.
Chin Med J (Engl). 2024 Nov 5;137(21):2603-2614. doi: 10.1097/CM9.0000000000002957. Epub 2024 Feb 26.
Renal ischemia-reperfusion (R-I/R) injury is the most prevalent cause of acute kidney injury, with high mortality and poor prognosis. However, the underlying pathological mechanisms are not yet fully understood. Therefore, this study aimed to investigate the role of N-myc downstream-regulated gene 2 ( Ndrg2 ) in R-I/R injury.
We examined the expression of Ndrg2 in the kidney under normal physiological conditions and after R-I/R injury by immunofluorescence staining, real-time polymerase chain reaction, and western blotting. We then detected R-I/R injury in Ndrg2-deficient ( Ndrg2-/- ) mice and wild type ( Ndrg2+/+ ) littermates in vivo , and detected oxygen and glucose deprivation and reperfusion (OGD-R) injury in HK-2 cells. We further conducted transcriptomic sequencing to investigate the role of Ndrg2 in R-I/R injury and detected levels of oxidative stress and mitochondrial damage by dihydroethidium staining, biochemical assays, and western blot. Finally, we measured the levels of mitophagy in Ndrg2+/+ and Ndrg2-/- mice after R-I/R injury or HK-2 cells in OGD-R injury.
Ndrg2 was primarily expressed in renal proximal tubules and its expression was significantly decreased 24 h after R-I/R injury. Ndrg2-/- mice exhibited significantly attenuated R-I/R injury compared to Ndrg2+/+ mice. Transcriptomics profiling showed that Ndrg2 deficiency induced perturbations of multiple signaling pathways, downregulated inflammatory responses and oxidative stress, and increased autophagy following R-I/R injury. Further studies revealed that Ndrg2 deficiency reduced oxidative stress and mitochondrial damage. Notably, Ndrg2 deficiency significantly activated phosphatase and tensin homologue on chromosome ten-induced putative kinase 1 (PINK1)/Parkin-mediated mitophagy. The downregulation of NDRG2 expression significantly increased cell viability after OGD-R injury, increased the expression of heme oxygenase-1, decreased the expression of nicotinamide adenine dinucleotide phosphate oxidase 4, and increased the expression of the PINK1/Parkin pathway.
Ndrg2 deficiency might become a therapy target for R-I/R injury by decreasing oxidative stress, maintaining mitochondrial homeostasis, and activating PINK1/Parkin-mediated mitophagy.
肾缺血再灌注（R-I/R）损伤是急性肾损伤最常见的原因，具有高死亡率和预后不良的特点。然而，其潜在的病理机制尚不完全清楚。因此，本研究旨在探讨 N- MYC 下游调节基因 2（Ndrg2）在 R-I/R 损伤中的作用。
我们通过免疫荧光染色、实时聚合酶链反应和蛋白质印迹法检测正常生理条件下和 R-I/R 损伤后肾脏中 Ndrg2 的表达。然后，我们在 Ndrg2 缺陷（Ndrg2-/-）小鼠和野生型（Ndrg2+/+）同窝仔鼠体内检测 R-I/R 损伤，并在 HK-2 细胞中检测氧和葡萄糖剥夺及再灌注（OGD-R）损伤。我们进一步通过转录组测序研究 Ndrg2 在 R-I/R 损伤中的作用，并通过二氢乙啶染色、生化测定和蛋白质印迹法检测氧化应激和线粒体损伤水平。最后，我们在 R-I/R 损伤后或 HK-2 细胞在 OGD-R 损伤后测量 Ndrg2+/+和 Ndrg2-/-小鼠中的自噬水平。
Ndrg2 主要在肾近端小管中表达，其表达在 R-I/R 损伤后 24 小时显著降低。与 Ndrg2+/+ 小鼠相比，Ndrg2-/- 小鼠的 R-I/R 损伤明显减轻。转录组谱分析表明，Ndrg2 缺失诱导了多种信号通路的紊乱，下调了炎症反应和氧化应激，并增加了 R-I/R 损伤后的自噬。进一步的研究表明，Ndrg2 缺失减少了氧化应激和线粒体损伤。值得注意的是，Ndrg2 缺失显著激活了磷酸酶和张力蛋白同源物诱导的假定激酶 1（PINK1）/Parkin 介导的自噬。NDRG2 表达下调显著增加了 OGD-R 损伤后的细胞活力，增加了血红素加氧酶-1 的表达，降低了烟酰胺腺嘌呤二核苷酸磷酸氧化酶 4 的表达，并增加了 PINK1/Parkin 通路的表达。
Ndrg2 缺失可能通过减少氧化应激、维持线粒体稳态和激活 PINK1/Parkin 介导的自噬成为 R-I/R 损伤的治疗靶点。
