Duan Tongyue, Sun Liya, Xi Yiyun, Li Chenrui, Zhao Qing, Xu Lujun, Yang Ming, Liu Chongbin, Xiao Li, Deng Tuo, Sun Lin
Department of Nephrology, The Second Xiangya Hospital of Central South University, Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, Hunan, 410011, China.
National Clinical Research Center for Metabolic Diseases, Department of Metabolism and Endocrinology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China; Key Laboratory of Diabetes Immunology, Ministry of Education, and Metabolic Syndrome Research Center, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China.
Free Radic Biol Med. 2025 Sep;237:147-159. doi: 10.1016/j.freeradbiomed.2025.05.431. Epub 2025 May 31.
Diabetic nephropathy (DN) is a common microvascular complication of diabetes mellitus linked to the overproduction of mitochondrial reactive oxygen species (mtROS). The mitochondria-targeted antioxidant Mito-tempo (MT) can reduce tubular damage in DN. It's known that mitochondrial double-stranded RNA (mt-dsRNA) can be released into the cytoplasm, leading to inflammation and apoptosis in disease states. However, it remains unclear whether MT prevents renal injury in DN by reducing mtROS production and subsequently mt-dsRNA release.
Type 1 DN model (STZ-induced mice) and type 2 DN model (db/db mice), as well as the high glucose (HG) induced human proximal tubular epithelial cells (HK-2 cells) were performed in vivo and in vitro experiments, respectively. Polynucleotide phosphorylase (PNPase) siRNA was transiently transfected into HK-2 cells to overexpress mt-dsRNA, and C16 was used to inhibit protein kinase R (PKR) phosphorylation. Mitochondrial damage, oxidative stress and apoptosis indicators, the localization and expression of mt-dsRNA, and downstream pathways changes were examined.
Treatment of MT to DN mice significantly reduced renal pathological changes. In addition, mt-dsRNA expression significantly decreased in tubular cells of DN mice treated with MT, along with oxidative stress, cell apoptosis and phosphorylated PKR/eukaryotic translation initiation factor 2 subunit alpha (eIF2α) reduced. Similar results were found in HK-2 cells treated with HG and MT, while mt-dsRNA release from the mitochondria to the cytoplasm and cell apoptosis were decreased, but cell apoptosis was further amplified by PNPase siRNA and partially blocked by C16.
These data suggest that mitochondria-targeted antioxidant MT reduces mtROS overproduction and prevents tubular injury in DN by inhibiting mt-dsRNA release and PKR/eIF2α pathway activation.
糖尿病肾病（DN）是糖尿病常见的微血管并发症，与线粒体活性氧（mtROS）过度产生有关。线粒体靶向抗氧化剂米托坦（MT）可减轻DN中的肾小管损伤。已知线粒体双链RNA（mt-dsRNA）可释放到细胞质中，在疾病状态下导致炎症和细胞凋亡。然而，MT是否通过减少mtROS产生及随后的mt-dsRNA释放来预防DN中的肾损伤仍不清楚。
分别在1型DN模型（链脲佐菌素诱导的小鼠）和2型DN模型（db/db小鼠）以及高糖（HG）诱导的人近端肾小管上皮细胞（HK-2细胞）中进行体内和体外实验。将多核苷酸磷酸化酶（PNPase）小干扰RNA瞬时转染到HK-2细胞中以过表达mt-dsRNA，并使用C16抑制蛋白激酶R（PKR）磷酸化。检测线粒体损伤、氧化应激和细胞凋亡指标、mt-dsRNA的定位和表达以及下游通路变化。
用MT治疗DN小鼠可显著减轻肾脏病理变化。此外，用MT治疗的DN小鼠肾小管细胞中mt-dsRNA表达显著降低，同时氧化应激、细胞凋亡以及磷酸化PKR/真核翻译起始因子2α亚基（eIF2α）减少。在用HG和MT处理的HK-2细胞中也发现了类似结果，同时从线粒体释放到细胞质中的mt-dsRNA和细胞凋亡减少，但PNPase小干扰RNA进一步放大了细胞凋亡，而C16部分阻断了细胞凋亡。
这些数据表明，线粒体靶向抗氧化剂MT通过抑制mt-dsRNA释放和PKR/eIF2α通路激活，减少mtROS过度产生并预防DN中的肾小管损伤。
