Suppression of Mutant Protein Expression in SCA3 and SCA1 Mice Using a CAG Repeat-Targeting Antisense Oligonucleotide

• Main Authors: Eleni Kourkouta, Rudie Weij, Anchel González-Barriga, Melissa Mulder, Ruurd Verheul, Sieto Bosgra, Bas Groenendaal, Jukka Puoliväli, Jussi Toivanen, Judith C.T. van Deutekom, Nicole A. Datson
• Format: Article
• Language: English
• Published: Elsevier 2019-09-01
• Series: Molecular Therapy: Nucleic Acids
• Online Access: http://www.sciencedirect.com/science/article/pii/S2162253119301945

Spinocerebellar ataxia type 3 (SCA3) and type 1 (SCA1) are dominantly inherited neurodegenerative disorders that are currently incurable. Both diseases are caused by a CAG-repeat expansion in exon 10 of the Ataxin-3 and exon 8 of the Ataxin-1 gene, respectively, encoding an elongated polyglutamine tract that confers toxic properties to the resulting proteins. We have previously shown lowering of the pathogenic polyglutamine protein in Huntington’s disease mouse models using (CUG)7, a CAG repeat-targeting antisense oligonucleotide. Here we evaluated the therapeutic capacity of (CUG)7 for SCA3 and SCA1, in vitro in patient-derived cell lines and in vivo in representative mouse models. Repeated intracerebroventricular (CUG)7 administration resulted in a significant reduction of mutant Ataxin-3 and Ataxin-1 proteins throughout the brain of SCA3 and SCA1 mouse models, respectively. Furthermore, in both a SCA3 patient cell line and the MJD84.2 mouse model, (CUG)7 induced formation of a truncated Ataxin-3 protein species lacking the polyglutamine stretch, likely arising from (CUG)7-mediated exon 10 skipping. In contrast, skipping of exon 8 of Ataxin-1 did not significantly contribute to the Ataxin-1 protein reduction observed in (CUG)7-treated SCA1154Q/2Q mice. These findings support the therapeutic potential of a single CAG repeat-targeting AON for the treatment of multiple polyglutamine disorders. Keywords: antisense oligonucleotide, SCA1, SCA3, polyglutamine disorders, exon skip, CAG repeat