Abstract
PURPOSE: The effects of enolase dysfunction-mediated glycolytic attenuation on oxidative stress-induced retinal ganglion cell (RGC) death were investigated. METHODS: Retinal expression of Enolase (ENO) 1 and 2 was detected using immunohistochemistry. Exogenous genes were introduced into mouse RGCs using viral vectors, and into the rat-derived retinal progenitor cell line R28 using lipofection. The effects of enolase dysfunction were evaluated using N-methyl-D-aspartate (NMDA)-induced RGC death and H2O2-induced death assays. Cell viability and gene expression were investigated using the alamarBlue, quantitative RT-PCR, and Western blotting, respectively. Reactive oxygen species (ROS) were detected using CM-H2DCFDA dye. 2-deoxyglucose and oligomycin were used to attenuate adenosine triphosphate (ATP) production in glycolysis and oxidative phosphorylation (OXPHOS), respectively. RESULTS: ENO1 and ENO2 were expressed in the RGCs. Enolase overexpression inhibited NMDA-induced mouse RGC death, whereas deficiency of ENO1 but not ENO2 enhanced cell death. Additionally, ENO1 overexpression prevented the CDKN2B-induced enhancement of RGC death. H2O2 treatment increased ENO1 expression in R28 cells and inhibited H2O2-induced cell death. ATP production was immediately enhanced in ENO1 wild-type cells treated with H2O2. 2-deoxyglucose and oligomycin prevented enhanced ATP production, but ATP levels were still higher than, or similar to, those in untreated wild-type cells; in contrast, in knockdown cells, oligomycin-mediated OXPHOS inhibition led to lower ATP production in H2O2-treatment than in untreated cells. H2O2 treatment increased ROS production in knockdown R28 cells. CONCLUSIONS: ENO1 dysfunction leads to glycolytic attenuation, resulting in an excessive dependence of ATP production on OXPHOS under oxidative stress, contributing to excitotoxicity-induced RGC death. Preventing glycolytic attenuation may represent a promising treatment for RGC degeneration.