Prevention of ferroptosis by the Alzheimer multifactorial therapeutic agent E2F4DN correlates with reduced neuronal tetraploidization

Abstract

AbstractBackgroundSomatic mutations accumulate during aging in human neurons (Science 2018;359:555‐559), resembling the progressive increase of somatic tetraploid neurons that is observed in the human entorhinal cortex, which precedes the neuropathological hallmarks of Alzheimer’s disease (AD) (Neurobiol. Aging 2017;56:50‐66). Oxidative stress can trigger lipid peroxidation, which can mediate somatic mutations and ferroptosis in neurons. E2F4 is a transcription factor that regulates the expression of genes involved in the oxidative stress response (Int. J. Mol. Sci. 2022;23:12093). A modified version of E2F4, unable to become phosphorylated in two conserved Thr residues by the stress kinase p38MAPK (E2F4DN), is a multifactorial therapeutic agent against AD. This therapeutic agent prevents pathological neuronal tetraploidization (NT) (Neurotherapeutics 2021;18:2484‐2503, Mol. Neurobiol. 2022;59:3016‐3039).MethodTo study the connection between somatic mutations and neuronal tetraploidy, we performed whole exome sequencing of diploid and tetraploid neurons isolated from the parietal cortex of AD patients as well as diploid neurons from control individuals. We also studied by qPCR whether oxidative stress‐related genes are modulated by E2F4DN in the cerebral cortex of both WT and 5xFAD mice, a known AD mouse model.ResultTetraploid neurons contain a significantly higher proportion of single nucleotide variants (SNVs) as compared to diploid neurons. These SNVs, which showed a molecular signature associated to lipid peroxidation, were exacerbated in DNA repair genes involved in base excision repair. SNVs in cancer‐related genes showed high pathogenicity scores in all cases. In both WT and 5xFAD mice, neuronal expression of E2F4DN reduced the expression of molecular markers of ferroptosis, a process associated with lipid peroxidation. This correlated with reduced NT.ConclusionWe propose that oxidative stress induces somatic mutations in neurons. When this process stochastically occurs in DNA repair genes, it facilitates the accumulation of SNVs in cancer‐related genes. This would lead to a tumor‐like process triggering NT followed by delayed neuronal degeneration (Am. J. Pathol. 2010;177:15‐20), as previously shown in vitro (Sci. Rep. 2018;8:14316). This mechanism likely participates in the etiology of neurodegenerative diseases including AD. E2F4DN prevents pathological NT likely due to its capacity to regulate oxidative stress response genes even under stressful conditions.