Antisense oligonucleotide treatment rescues UBE3A expression and multiple phenotypes of an Angelman syndrome mouse model

Claudia Milazzo,Thomas Kremer,Tejaswini Kakunuri,Kamille Dumong Erichsen,Ype Elgersma,Ilse Wallaard,A.S Elise Van Der Sman,Marius C Hoener,Meghan T Miller,Edwin J Mientjes,Søren Vestergaard Rasmussen

doi:10.1172/jci.insight.145991

Abstract

Angelman syndrome (AS) is a severe neurodevelopmental disorder for which only symptomatic treatment with limited benefits is available. AS is caused by mutations affecting the maternally inherited ubiquitin protein ligase E3A (UBE3A) gene. Previous studies showed that the silenced paternal Ube3a gene can be activated by targeting the antisense Ube3a-ATS transcript. We investigated antisense oligonucleotide–induced (ASO-induced) Ube3a-ATS degradation and its ability to induce UBE3A reinstatement and rescue of AS phenotypes in an established Ube3a mouse model. We found that a single intracerebroventricular injection of ASOs at postnatal day 1 (P1) or P21 in AS mice resulted in potent and specific UBE3A reinstatement in the brain, with levels up to 74% of WT levels in the cortex and a full rescue of sensitivity to audiogenic seizures. AS mice treated with ASO at P1 also showed rescue of established AS phenotypes, such as open field and forced swim test behaviors, and significant improvement on the reversed rotarod. Hippocampal plasticity of treated AS mice was comparable to WT but not significantly different from PBS-treated AS mice. No rescue was observed for the marble burying and nest building phenotypes. Our findings highlight the promise of ASO-mediated reactivation of UBE3A as a disease-modifying treatment for AS.

Highlights

Angelman syndrome (AS) is a severe neurodevelopmental disorder affecting approximately 1:20,000 individuals [1]
Two of the 3 ASOs injected at postnatal day 1 (P1) given at an initial testing dose of 11 and 22 μg led to overt signs of toxicity in mice
Using a lower dose prevented any sign of toxicity but resulted in limited ubiquitin protein ligase E3A (UBE3A) reinstatement

Summary

Introduction

Angelman syndrome (AS) is a severe neurodevelopmental disorder affecting approximately 1:20,000 individuals [1]. The paternal UBE3A allele is silenced as a result of transcriptional interference by the long noncoding UBE3A-ATS (antisense) transcript [6,7,8] In both humans and mice, the UBE3A-ATS transcript originates from the same precursor encoding small nuclear ribonucleoprotein N (SNRPN), which has multiple upstream promoters in the Prader-Willi syndrome imprinting center (PWS-IC) and upstream of the U exons where it initiates, and it overlaps with the UBE3A gene (Figure 1A) [9]. The combination of both paternal UBE3A silencing and loss of maternal UBE3A expression due to mutations in the maternal allele in AS patients results in the complete loss of neuronal UBE3A protein expression in AS patients. Meng and colleagues showed that transcription inhibition of the Ube3aATS transcript, either by deletion of the genomic area around its promoter or by insertion of a transcriptional stop cassette to induce premature termination, leads to paternal Ube3a expression [9, 10]

Methods

Results

Conclusion