Background. There are currently no effective treatments for amyotrophic lateral sclerosis (ALS), highlighting the importance of unraveling the mechanisms leading to motor neuron loss. One candidate is the WW domain-containing oxidoreductase (WWOX), which is widely involved in neurodegeneration.
Objectives. To determine whether and how alterations in WWOX levels and mutations in the WWOX gene may contribute to ALS pathogenesis.
Results. WWOX levels were decreased in ALS mCTX based on western blots. We also identified several rare and ALS-specific variants in WWOX using genomic data from Project MinE. Among these variants, the stop codon mutation at amino acid 261 decreased cell viability, reduced ATP levels, and increased ROS in SH-SY5Y cells treated with mutant recombinant WWOX protein compared to wild-type recombinant protein. These in vitro findings were consistent with decreases in the mitochondrial membrane ATP synthase of complex V and the cytochrome c oxidase of complex IV in ALS mCTX. Furthermore, knocking down WWOX using small interfering RNA (siWWOX) decreased ROS levels in SH-SY5Y cells, suggesting a link between loss of WWOX and increases in oxidative stress in ALS. Similarly, siWWOX reduced sleep in a fly model, supporting a pathogenic role for loss of WWOX.
Conclusions. Collectively, our findings suggest that loss of WWOX or mutations in the gene that lead to a truncated protein exacerbate mitochondrial dysfunction in ALS.