# EPO-R76E Enhances Retinal Pigment Epithelium Viability Under Mitochondrial Oxidative Stress Induced by Paraquat

## TL;DR

This study shows that EPO-R76E protects retinal pigment epithelium cells from oxidative stress, suggesting it could help treat age-related macular degeneration.

## Contribution

The study demonstrates the novel cytoprotective role of EPO-R76E in retinal pigment epithelium under oxidative stress.

## Key findings

- EPO-R76E-expressing cells showed increased viability and resistance to mitochondrial damage.
- EPO-R76E reduced intracellular iron accumulation and reactive oxygen species in paraquat-exposed cells.
- EPO-R76E modulated oxidative stress pathways by restoring GPX4 and reducing p-AMPK and NRF2 activation.

## Abstract

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss, primarily driven by oxidative stress–induced degeneration of retinal pigment epithelium (RPE). Erythropoietin (EPO), a hematopoietic cytokine with neuroprotective properties, has been shown to reduce apoptosis and retinal degeneration. In this study, we examined the cytoprotective role of a non-erythropoietic EPO variant, EPO-R76E, in suppressing oxidative stress and mitochondrial dysfunction related to oxidative stress in RPE cells. Stable ARPE-19 cell lines expressing EPO-R76E were generated via lentiviral transduction and exposed to paraquat to induce oxidative stress. Oxidative stress was induced using paraquat. EPO-R76E expression conferred increased cell viability and resistance to mitochondrial damage, as assessed by cytotoxicity assays. Western blot analysis revealed reduced expression of ferritin and p62/SQSTM1, diminished activation of p-AMPK and NRF2, and restoration of GPX4 levels, indicating enhanced antioxidant defenses. Moreover, intracellular iron accumulation and reactive oxygen species were significantly reduced in EPO-R76E-expressing cells exposed to paraquat. These findings suggest that EPO-R76E promotes mitochondrial homeostasis and modulates oxidative stress pathways. Our study positions EPO-R76E as a promising therapeutic candidate for halting RPE degeneration in AMD.