Department of Nephrology, General Hospital of Tianjin Medical University, Tianjin 300052, China.
Department of Emergency, The Affiliated People's Hospital of Zhangjiakou University, Hebei 075000, China.
Biosci Rep. 2018 Nov 20;38(6). doi: 10.1042/BSR20180876. Print 2018 Dec 21.
Reactive oxygen species (ROS) overproduction and renal tubular epithelial cell (TEC) apoptosis are key mechanisms of contrast-induced acute kidney injury (CI-AKI). Mitochondria are the main source of intracellular ROS. In the present study, the characteristics of mitophagy and the effects of rapamycin on contrast-induced abnormalities in oxidative stress, mitochondrial injury and mitophagy, TEC apoptosis and renal function were investigated in a CI-AKI rat model. Rats were divided into control group, CI-AKI group, and pretreatment groups (with rapamycin dose of 2 or 5 mg/kg). CI-AKI was induced by intraperitoneal injection of iohexol (12.25 g iodine/kg). Renal malondialdehyde (MDA) and catalase (CAT) were measured as oxidative markers. Light-chain 3 (LC3), P62, Beclin-1, PTEN-induced putative kinase (Pink1), and cytochrome (Cyt ) expression were measured by Western blot. Mitochondrial membrane potential (ΔΨm) was determined by JC-1, colocalization of LC3-labeled autophagosomes with TOMM20-labeled mitochondria or LAMP2-labeled lysosomes was observed by fluorescence microscopy. Significantly increased serum creatinine (Scr), MDA and CAT, obvious mitochondrial injury including increase in cytosolic/mitochondrial Cyt and decrease in ΔΨm, TEC apoptosis were induced by contrast administration. Contrast administration induced an increased expression of LC3II/I, Beclin-1, and Pink1 and decreased expression of P62. Rapamycin pretreatment induced overexpression of LC3II/I and Beclin-1. Moreover, LC3-labeled autophagosomes increasingly overlapped with TOMM20-labeled mitochondria and LAMP2-labeled lysosomes in CI-AKI, which was further enhanced by rapamycin administration. Contrast-induced Scr increase, oxidative stress, mitochondrial injury, TEC apoptosis, and necrosis were dose-dependently attenuated by rapamycin pretreatment. Rapamycin exerts renoprotective effects against CI-AKI by attenuating mitochondrial injury and oxidative stress, which might be associated with increasing mitophagy.
活性氧(ROS)过度产生和肾小管上皮细胞(TEC)凋亡是对比剂诱导急性肾损伤(CI-AKI)的关键机制。线粒体是细胞内 ROS 的主要来源。在本研究中,研究了自噬在 CI-AKI 大鼠模型中氧化应激、线粒体损伤和自噬、TEC 凋亡和肾功能异常中的特征,以及雷帕霉素对其的影响。大鼠分为对照组、CI-AKI 组和预处理组(雷帕霉素剂量为 2 或 5mg/kg)。通过腹腔注射碘海醇(12.25g 碘/kg)诱导 CI-AKI。测定肾丙二醛(MDA)和过氧化氢酶(CAT)作为氧化标志物。通过 Western blot 测定 LC3、P62、Beclin-1、PTEN 诱导的假定激酶(Pink1)和细胞色素(Cyt)的表达。通过 JC-1 测定线粒体膜电位(ΔΨm),通过荧光显微镜观察 LC3 标记的自噬体与 TOMM20 标记的线粒体或 LAMP2 标记的溶酶体的共定位。造影剂给药导致血清肌酐(Scr)、MDA 和 CAT 显著升高,明显的线粒体损伤,包括胞浆/线粒体 Cyt 增加和 ΔΨm 降低,TEC 凋亡。造影剂给药诱导 LC3II/I、Beclin-1 和 Pink1 的表达增加,P62 的表达减少。雷帕霉素预处理诱导 LC3II/I 和 Beclin-1 的过表达。此外,CI-AKI 中 LC3 标记的自噬体与 TOMM20 标记的线粒体和 LAMP2 标记的溶酶体的重叠增加,雷帕霉素给药进一步增强了这种重叠。雷帕霉素预处理剂量依赖性地减轻了对比剂诱导的 Scr 升高、氧化应激、线粒体损伤、TEC 凋亡和坏死。雷帕霉素通过减轻线粒体损伤和氧化应激对 CI-AKI 发挥肾保护作用,这可能与增加自噬有关。
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