Identification of key genes involved in Down's syndrome pathogenesis by gene therapy

Abstract

Viruses have evolved ways of encapsulating and delivering their genes into human cells. Gene therapy takes advantage of this capability to manipulate the viral genome and convert an infectious agent into an efficient vector that delivers therapeutic genes. In the current work we have applied gene therapy approaches based on adeno-associated virus and lentivirus delivery to identify candidate genes (protein-coding or miRNAs) involved in the cognitive deficits in Down Syndrome. We show that the hippocampal injection of the adeno-associated virus AAV2/1-shDyrk1A normalized Dyrk1A expression in the trisomic Ts65Dn mice. As a consequence the regulation of key molecular players in memory and learning processes was rescued and mice showed an attenuation of synaptic plasticity defects and improved efficacy in learning strategies. All together these results reinforce the role of Dyrk1A in cognition. On the other hand, with the lentiviral strategy developed to specifically inhibit miR-155 and miR-802 (Lv-anti-miR155/802), we were able to show a tight control of the miRNAs target Mecp2 suggesting that the downregulation of MeCP2 in Down syndrome could be a contributing factor to the cognitive defects.