E2F4-BASED GENE THERAPY RESTORES LONG-TERM POTENTIATION AND MEMORY FORMATION AND BLOCKS NEURONAL DEATH IN AN ALZHEIMER MOUSE MODEL

Despite decades of work, effective therapies for Alzheimer’s disease (AD) remain elusive, likely due to its complex etiology. Synaptic dysfunction is an early hallmark of AD, preceding neuronal loss. We have previously identified the transcription factor E2F4 as a multifactorial therapeutic target in AD, showing that phosphorylation of two conserved threonine residues contributes to cognitive impairment. Based on this, we developed a novel gene therapy strategy consisting of neuronal expression of a dominant-negative form of human E2F4 (hE2F4DN), which cannot be phosphorylated at these residues. Here, we investigated whether hE2F4DN expression could repair synaptic dysfunction and prevent neuronal loss in a model of AD, the homozygous 5xFAD (h5xFAD) mice. An AAV-hE2F4DN vector was administered intravenously to control and h5xFAD mice at either 6 weeks of age, when pathology is minimal, or 13 weeks of age, when hippocampal long-term potentiation (LTP) and memory are already lost. Stereological, electrophysiological, biochemical, and behavioral analyses were conducted at 6 months of age. Neuronal expression of hE2F4DN prevented neuronal loss in the CA1 region of the hippocampus in h5xFAD mice. Early treatment prevents LTP loss leading to cognitive improvement. Remarkably, treatment at 13 weeks of age led to a full recovery of both LTP and memory, accompanied by increased levels of the postsynaptic marker PSD-95. We conclude that E2F4-Based Gene Therapy blocks neuronal death and recovers the loss of LTP and cognition in already affected h5xFAD mice, supporting its potential as a safe multifactorial therapeutic approach for both prodromal and demented AD patients.