Department of Ophthalmology, The Second Affiliated Hospital of Nanchang University, No. 1 Minde Road, Nanchang, 330006, China.
Endocrine. 2018 Jun;60(3):445-457. doi: 10.1007/s12020-018-1575-7. Epub 2018 Mar 21.
Diabetic retinopathy (DR) is a major vision threatening disease mainly induced by high glucose. Despite great efforts were made to explore the etiology of DR, the exact mechanism responsible for its pathogenesis remains elusive.
In our study, we constructed diabetic rats via Streptozotocin (STZ) injection. TUNEL assay was employed to examine retinal cell apoptosis. The levels of mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were analyzed via flow cytometry. The mRNA and protein levels of mitochondrial respiratory chain were investigated by RT-qPCR and western blot.
Compared with normal rats, the retinal cell apoptosis rate in diabetic rats was significantly upregulated. What's more, the signals of 8-OHdG and the levels of Cytochrome C in diabetic rats were enhanced; however, the MnSOD signals and NADPH-1 levels were reduced. We investigated the effect of mitochondrialy targeted hOGG1 (MTS-hOGG1) on the primary rRECs under high glucose. Compared with vector-transfected cells, MTS-hOGG1-expressing cells blocked high glucose-induced cell apoptosis, the loss of MMP and the overproduction of ROS. In addition, under high glucose, MTS-hOGG1 transfection blocked the expression of Cytochrome C, but enhanced the expression of cytochrome c oxidase subunit 1 and NADPH-1.
These findings indicated that high glucose induced cell apoptosis by causing the loss of MMP, the overproduction of ROS and mtDNA damage. Targeting DNA repair enzymes hOGG1 in mitochondria partly mitigated the high glucose-induced consequences, which shed new light for DR therapy.
糖尿病视网膜病变（DR）是一种主要由高血糖引起的威胁视力的疾病。尽管人们努力探索 DR 的病因，但导致其发病机制的确切机制仍不清楚。
我们通过链脲佐菌素（STZ）注射构建了糖尿病大鼠模型。采用 TUNEL 检测法检测视网膜细胞凋亡。通过流式细胞术分析线粒体膜电位（MMP）和活性氧（ROS）水平。通过 RT-qPCR 和 Western blot 检测线粒体呼吸链的 mRNA 和蛋白水平。
与正常大鼠相比，糖尿病大鼠的视网膜细胞凋亡率明显升高。此外，糖尿病大鼠中 8-OHdG 的信号和细胞色素 C 的水平增强，而 MnSOD 信号和 NADPH-1 的水平降低。我们研究了线粒体靶向 hOGG1（MTS-hOGG1）对高糖条件下原代 rRECs 的影响。与载体转染的细胞相比，MTS-hOGG1 表达细胞阻断了高糖诱导的细胞凋亡、MMP 丧失和 ROS 过度产生。此外，在高糖条件下，MTS-hOGG1 转染阻断了细胞色素 C 的表达，但增强了细胞色素 c 氧化酶亚基 1 和 NADPH-1 的表达。
这些发现表明，高糖通过引起 MMP 丧失、ROS 过度产生和 mtDNA 损伤诱导细胞凋亡。靶向线粒体中的 DNA 修复酶 hOGG1 部分减轻了高糖诱导的后果，为 DR 治疗提供了新的思路。
