Peroxisome proliferator-activated receptor alpha (PPARα) is associated with diabetic retinopathy (DR), and the underlying mechanism is still unclear. Aim of this work was to investigate the mechanism of PPARα in DR. Human retinal capillary pericytes (HRCPs) were treated with high glucose (HG) to induce DR cell model. DR mouse model was established by streptozotocin injection, and then received 5-Aza-2-deoxycytidine (DAC; DNA methyltransferase inhibitor) treatment. Hematoxylin–eosin staining was performed to assess retinal tissue damage. PPARα methylation was examined by Methylation-Specific PCR. Flow cytometry and DCFH-DA fluorescent probe was used to estimate apoptosis and reactive oxygen species (ROS). The interaction between DNA methyltransferase-1 (DNMT1) and PPARα promoter was examined by Chromatin Immunoprecipitation. Quantitative real-time PCR and western blot were performed to assess gene and protein expression. HG treatment enhanced the methylation levels of PPARα, and repressed PPARα expression in HRCPs. The levels of apoptotic cells and ROS were significantly increased in HRCPs in the presence of HG. Moreover, DNMT1 was highly expressed in HG-treated HRCPs, and DNMT1 interacted with PPARα promoter. PPARα overexpression suppressed apoptosis and ROS levels of HRCPs, which was rescued by DNMT1 up-regulation. In DR mice, DAC treatment inhibited PPARα methylation and reduced damage of retinal tissues. DNMT1-mediated PPARα methylation promotes apoptosis and ROS levels of HRCPs and aggravates damage of retinal tissues in DR mice. Thus, this study may highlight novel insights into DR pathogenesis.

中文翻译：

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DNMT1介导的PPARα甲基化加重糖尿病视网膜病变小鼠视网膜组织的损伤

过氧化物酶体增殖物激活受体α (PPARα) 与糖尿病视网膜病变 (DR) 相关，其潜在机制仍不清楚。这项工作的目的是研究 PPARα 在 DR 中的作用机制。用高葡萄糖（HG）处理人视网膜毛细血管周细胞（HRCP）以诱导DR细胞模型。通过注射链脲佐菌素建立DR小鼠模型，然后接受5-Aza-2-脱氧胞苷（DAC；DNA甲基转移酶抑制剂）治疗。进行苏木精-伊红染色以评估视网膜组织损伤。通过甲基化特异性 PCR 检查 PPARα 甲基化。流式细胞术和 DCFH-DA 荧光探针用于估计细胞凋亡和活性氧 (ROS)。通过染色质免疫沉淀检查 DNA 甲基转移酶-1 (DNMT1) 和 PPARα 启动子之间的相互作用。进行定量实时 PCR 和蛋白质印迹以评估基因和蛋白质表达。HG 处理增强了 PPARα 的甲基化水平，并抑制了 HRCPs 中 PPARα 的表达。在 HG 存在下，HRCPs 中凋亡细胞和 ROS 的水平显着增加。此外，DNMT1 在 HG 处理的 HRCP 中高表达，DNMT1 与 PPARα 启动子相互作用。PPARα过表达抑制了HRCPs的细胞凋亡和ROS水平，这被DNMT1上调所挽救。在 DR 小鼠中，DAC 治疗抑制了 PPARα 甲基化并减少了视网膜组织的损伤。DNMT1 介导的 PPARα 甲基化促进了 HRCPs 的凋亡和 ROS 水平，并加重了 DR 小鼠视网膜组织的损伤。因此，这项研究可能会突出对 DR 发病机制的新见解。