Gene replacement therapy for Lafora disease in theEpm2a-/-mouse model

Abstract

AbstractLafora disease is a rare and fatal form of progressive myoclonic epilepsy typically occurring early in adolescence. Common symptoms include seizures, dementia, and a progressive neurological decline leading to death within 5-15 years from onset. The disease results from mutations transmitted with autosomal recessive inheritance in theEPM2Agene, encoding laforin, a dual-specificity phosphatase, or theEPM2Bgene, encoding malin, an E3-ubiquitin ligase. Laforin has glucan phosphatase activity, is an adapter of enzymes involved in glycogen metabolism, is involved in endoplasmic reticulum-stress and protein clearance, and acts as a tumor suppressor protein. Laforin and malin work together in a complex to control glycogen synthesis and prevent the toxicity produced by misfolded proteins via the ubiquitin-proteasome system. Disruptions in either protein can lead to alterations in this complex, leading to the formation of Lafora bodies that contain abnormal, insoluble, and hyperphosphorylated forms of glycogen called polyglucosans.We used theEpm2a-/-knock-out mouse model of Lafora disease to apply a gene replacement therapy by administering intracerebroventricular injections of a recombinant adeno-associated virus carrying the humanEPM2Agene. We evaluated the effects of this treatment by means of neuropathological studies, behavioral tests, video-electroencephalography recording, and proteomic/phosphoproteomic analysis.Gene therapy with recombinant adeno-associated virus containing theEPM2Agene ameliorated neurological and histopathological alterations, reduced epileptic activity and neuronal hyperexcitability, and decreased the formation of Lafora bodies. Differential quantitative proteomics and phosphoproteomics revealed beneficial changes in various molecular pathways altered in Lafora disease. Improvements were observed for up to nine months following a single intracerebroventricular injection. In conclusion, gene replacement therapy with humanEPM2Agene in theEpm2a-/-knock-out mice shows promise as a potential treatment for Lafora disease.