Overexpression of ferroptosis defense enzyme Gpx4 retards motor neuron disease of SOD1G93A mice

Abstract

Degeneration and death of motor neurons in Amyotrophic Lateral Sclerosis (ALS) are associated with increased lipid peroxidation. Lipid peroxidation is the driver of ferroptosis, an iron-dependent oxidative mode of cell death. However, the importance of ferroptosis in motor neuron degeneration of ALS remains unclear. Glutathione peroxidase 4 (Gpx4) is a key enzyme in suppressing ferroptosis by reducing phospholipid hydroperoxides in membranes. To assess the effect of increased protection against ferroptosis on motor neuron disease, we generated SOD1 ^G93AGPX4 double transgenic mice by cross-breeding GPX4 transgenic mice with SOD1 ^G93A mice, a widely used ALS mouse model. Compared with control SOD1 ^G93A mice, both male and female SOD1 ^G93AGPX4 mice had extended lifespans. SOD1 ^G93AGPX4 mice also showed delayed disease onset and increased motor function, which were correlated with ameliorated spinal motor neuron degeneration and reduced lipid peroxidation. Moreover, cell toxicity induced by SOD1 ^G93A was ameliorated by Gpx4 overexpression and by chemical inhibitors of ferroptosis in vitro. We further found that the anti-ferroptosis defense system in spinal cord tissues of symptomatic SOD1 ^G93A mice and sporadic ALS patients might be compromised due to deficiency of Gpx4. Thus, our results suggest that ferroptosis plays a key role in motor neuron degeneration of ALS.