# RNAi-Induced Expression of Paternal UBE3A

## TL;DR

This study explores using RNA interference to activate the paternal UBE3A gene in neurons, which could help treat Angelman syndrome.

## Contribution

The study demonstrates that RNAi targeting SNORD115 can activate paternal UBE3A in both mouse and human neurons.

## Key findings

- RNAi targeting SNORD115 reduced UBE3A-ATS and activated paternal UBE3A in mouse neurons.
- Similar activation was observed in human iPSC-derived neurons using LV-shSNORD115.
- AAV-based delivery of shRNA shows potential but requires further in vivo evaluation.

## Abstract

Background/Objectives: Angelman syndrome is a neurodevelopmental disorder resulting from a deficiency of the maternally inherited UBE3A gene. In mature neurons, UBE3A expression is restricted to the maternal allele due to tissue-specific genomic imprinting, while the paternal allele is silenced in cis by the UBE3A antisense transcript (UBE3A-ATS). To date, numerous strategies have been employed to activate paternal UBE3A expression. In this study, we utilized RNA interference (RNAi) to investigate the downregulation of UBE3A-ATS in mouse primary neurons and human induced pluripotent stem cell (iPSC)-derived neurons. Methods: To induce paternal UBE3A expression, we employed small interfering RNA (siRNA) oligonucleotides (20 mouse candidates and 47 human candidates) and lentiviral short hairpin RNA (LV-shRNA) targeting SNORD115 to suppress UBE3A-ATS expression in both mouse primary neurons and iPSCs. Subsequently, we assessed the expression levels of Angelman syndrome-related neighboring and target genes at the transcript and, where applicable, protein levels. Results: Following treatment with siSnord115 or LV-shSnord115, we observed a reduction in Ube3a-ATS and a corresponding activation of paternal Ube3a RNA and protein expression in both Ube3aP-YFP/m+ and Ube3ap+/m− mouse primary neurons. A similar effect was observed upon treatment with LV-shSNORD115s in human iPSC-derived neurons. Conclusions: shRNA-mediated inhibition of Ube3a-ATS by targeting Snord115 effectively restores Ube3a/UBE3A expression in both mouse neurons and human iPSCs. While promising, the mild reduction in Snord116 raises concerns about potential off-target effects. AAV-based delivery of shRNA shows potential, but its translational applicability remains to be evaluated in vivo.