In vivo repair of a protein underlying a neurological disorder by programmable RNA editing

Abstract

RNA base editing is gaining momentum as an approach to repair mutations, but its application to neurological disease has not been established. We have succeeded in directed transcript editing of a pathological mutation in a mouse model of the neurodevelopmental disease, Rett syndrome. Specifically, we directed editing of a guanosine to adenosine mutation in RNA encoding Methyl CpG Binding Protein 2 (MECP2). Repair was mediated by injecting the hippocampus of juvenile Rett mice with an adeno-associated virus expressing both an engineered enzyme containing the catalytic domain of Adenosine Deaminase Acting on RNA 2 and a Mecp2 targeting guide. After one month, 50% of Mecp2 RNA was recoded in three different hippocampal neuronal subtypes, and the ability of MeCP2 protein to associate with heterochromatin was similarly restored to 50% of wild-type levels. This study represents the first in vivo programmable RNA editing applied to a model of neurological disease.

Robust RNA editing via recruitment of endogenous ADARs using circular guide RNAs

“…The structural similarity between inosine and guanosine results in the translation and splicing machinery recognizing the edited base as guanosine, thereby making ADARs attractive tools for recoding protein sequences (14). To this end, several studies have recently repurposed the ADAR system for programmable RNA editing both in vitro (1,(15)(16)(17)(18)(19)(20)(21)(22) and in vivo (1,23) by engineering recruitment of ADARs to a target RNA sequence using ADAR recruiting guide RNAs (adRNAs). Although ADARs, and in particular ADAR1, are widely expressed throughout the body, most of these studies relied on exogenously delivered ADAR enzymes and their variants to achieve robust RNA editing efficiencies.…”