DNMT1-mediated PPARα methylation aggravates damage of retinal tissues in diabetic retinopathy mice

Background: Peroxisome proliferator-activated receptor alpha (PPAR alpha) is associated with diabetic retinopathy (DR), and the underlying mechanism is still unclear. Aim of this work was to investigate the mechanism of PPAR alpha in DR. Methods: 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. PPAR alpha 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 PPAR alpha promoter was examined by Chromatin Immunoprecipitation. Quantitative real-time PCR and western blot were performed to assess gene and protein expression. Results: HG treatment enhanced the methylation levels of PPAR alpha, and repressed PPAR alpha 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 PPAR alpha promoter. PPAR alpha overexpression suppressed apoptosis and ROS levels of HRCPs, which was rescued by DNMT1 up-regulation. In DR mice, DAC treatment inhibited PPAR alpha methylation and reduced damage of retinal tissues. Conclusion: DNMT1-mediated PPAR alpha 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.

Automated summary

The study found that DNMT1-mediated PPAR alpha methylation promotes apoptosis and ROS levels in HRCPs, exacerbating retinal tissue damage in DR mice.