# Beyond readthrough: ataluren restores mitochondrial function and reduces oxidative stress in FANCA-mutated cells via mTOR–DRP1 modulation

## TL;DR

Ataluren improves mitochondrial function and reduces oxidative stress in Fanconi anemia cells, beyond its known readthrough effect.

## Contribution

Ataluren's metabolic and redox benefits in FA cells are revealed, independent of mutation type and involving mTOR–DRP1 modulation.

## Key findings

- Ataluren improves ATP/AMP ratio and oxidative phosphorylation efficiency in FA cells.
- Ataluren reduces lipid peroxidation and oxidative DNA damage without affecting glycolysis.
- Ataluren lowers DRP1 and mTOR-S6 signaling, suggesting modulation of mitochondrial dynamics.

## Abstract

Fanconi anemia (FA) is a rare inherited bone marrow failure syndrome characterized by genomic instability, mitochondrial dysfunction, and oxidative stress. While the therapeutic potential of ataluren, a translational readthrough-inducing drug, has been investigated in FA cells carrying nonsense mutations, its broader metabolic impact remains unclear. Here, we demonstrate that ataluren (tested at 2.5, 5, and 10 μM) modulates cellular energy metabolism and redox homeostasis in FA lymphoblasts harboring either nonsense or missense mutations in the FANCA gene. At low doses (2.5 μM for 72 h), ataluren improved the ATP/AMP ratio, enhanced oxidative phosphorylation efficiency, and reduced lipid peroxidation and oxidative DNA damage. These effects were independent of mutation type and were not associated with compensatory glycolysis, as lactate dehydrogenase activity remained unchanged. Strikingly, ataluren restored the P/O ratio under pyruvate/malate-driven respiration to near-normal values, indicating improved coupling between oxygen consumption and ATP synthesis. Mechanistically, ataluren reduced DRP1 protein levels and attenuated mTOR-S6 signaling, suggesting that mitochondrial dynamics and bioenergetic efficiency are modulated via the mTOR–DRP1 axis. Additionally, ataluren lowered IMPDH activity, contributing to reduced cell proliferation and DNA damage without impairing cellular energy status. Notably, these beneficial effects persisted under immune stimulation, where ataluren mitigated the metabolic and oxidative burden imposed by lymphocyte activation. Our findings unveil a pleiotropic role for ataluren that extends beyond its canonical readthrough activity, highlighting its potential as a metabolic modulator for FA and possibly other DNA repair–deficient disorders.