Short-Chain Guide RNA for Site-Directed A-to-I RNA Editing

Site-directed RNA editing is a promising genetic modification technology for therapeutic and pharmaceutical applications. We previously constructed adenosine deaminases acting on RNA (ADAR)-guiding RNAs (AD-gRNAs) that direct A-to-I RNA editing activity of native human ADAR2 into a programmable target site. In this study, we developed the short-chain AD-gRNA (shAD-gRNA) as a potential basic framework for practical RNA-editing oligonucleotides. Based on knowledge of previous AD-gRNA, shAD-gRNAs were designed to have the shortest possible sequence for the induction of editing activity. In vitro, compared to the original AD-gRNA, the shAD-gRNAs showed similar or superior editing induction activity, depending on the target RNA sequence, and had lower off-target editing activity around the target site, which is predicted to be a hotspot for off-target editing. Moreover, shAD-gRNAs achieved target RNA editing with both exogenous and endogenous human ADARs in cultured cells. Our results present shAD-gRNA as a short basic framework that would be applicable to further development for practical RNA-editing oligonucleotides.