Abstract
Purpose :
Keratopathy is one of the most frequent clinical problems faced by diabetic patients, and this potentially sight-threatening condition is caused mainly by corneal epithelial disturbances. Diabetes impairs corneal epithelial cells functionally, morphologically and biochemically, and overproduction of mitochondrial superoxide radicals is considered as a causal link between elevated glucose and the major biochemical pathways implicated in the development of keratopathy. Mitochondria are dynamic structures, and depending on the energy demand, they continuously fuse and divide. An imbalance in the fusion-fission can alter their membrane potential, respiration and bioenergetics. Mitochondria dynamics is regulated by GTPases; fission is mainly controlled by dynamin-related protein1 (Drp1) and fusion by mitofusin-2 (Mfn2) and optic atrophy1. During mitochondrial fission, fission protein 1 (Fis1) and mitochondrial fission factor (Mff) direct Drp1 to the fission site. The aim of this study was to investigate the role of mitochondrial dynamics in the development of diabetic keratopathy.
Methods :
Cornea from streptozotocin-induced diabetic rats (3 months duration) were used to quantify mitochondrial reactive oxygen species (ROS) by DCFDA, and expression of Drp1, Fis1, Mff, Mfn2 and OPA1 by quantitative real time PCR (β-actin as a housekeeping gene). Effect of diabetes on the expressions of Drp1 and Mfn2 was confirmed in the corneal cryosections by immunohistochemical technique.
Results :
Compared to normal rats, ROS were elevated, and while Drp1, Fis1 and Mff expressions were increased, Mfn2 and OPA1 were decreased in the cornea from diabetic rats. While immunofluorescence of Drp1 was increased in the corneal epithelial cell layer from diabetic rats, that of Mfn2 was significantly decreased.
Conclusions :
Our data demonstrate an impaired corneal mitochondria fusion-fission machinery in diabetes, suggesting an important role of mitochondrial dynamics in the development of diabetic keratopathy.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.