Allele-specific targeting of mutant ataxin-3 by antisense oligonucleotides in SCA3-iPSC-derived neurons

• Published in: Molecular therapy. Nucleic acids Vol. 27; pp. 99 - 108
• Main Authors: Hauser, Stefan, Helm, Jacob, Kraft, Melanie, Korneck, Milena, Hübener-Schmid, Jeannette, Schöls, Ludger
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 08.03.2022; American Society of Gene & Cell Therapy; Elsevier
• Subjects: allele-specific targeting; antisense oligonucleotides; ASO; iPSC-derived neurons; Machado-Joseph disease; MJD; Original; SCA3; SNP; spinocerebellar ataxia type 3; Machado-Joseph disease; SCA3; SNP; spinocerebellar ataxia type 3; iPSC-derived neurons; MJD; allele-specific targeting; antisense oligonucleotides; ASO
• ISSN: 2162-2531; 2162-2531
• DOI: 10.1016/j.omtn.2021.11.015

Spinocerebellar ataxia type 3 (SCA3) is caused by an expanded polyglutamine stretch in ataxin-3. While wild-type ataxin-3 has important functions, e.g., as a deubiquitinase, downregulation of mutant ataxin-3 is likely to slow down the course of this fatal disease. We established a screening platform with human neurons of patients and controls derived from induced pluripotent stem cells to test antisense oligonucleotides (ASOs) for their effects on ataxin-3 expression. We identified an ASO that suppressed mutant and wild-type ataxin-3 levels by >90% after a singular treatment. Next, we screened pairs of ASOs designed to selectively target the mutant or the wild-type allele by taking advantage of a SNP (c.987G > C) in ATXN3 that is present in most SCA3 patients. We found ASOmut4 to reduce levels of mutant ataxin-3 by 80% after 10 days while leaving expression of wild-type ataxin-3 largely unaffected. In a long-term study we proved this effect to last for about 4 weeks after a single treatment without signs of neurotoxicity. This study provides proof of principle that allele-specific lowering of poly(Q)-expanded ataxin-3 by selective ASOs is feasible and long lasting, with sparing of wild-type ataxin-3 expression in a human cell culture model that is genetically identical to SCA3 patients. [Display omitted] Spinocerebellar ataxia type 3 (SCA3) is caused by an expanded polyglutamine stretch in ataxin-3. Our study highlights patient-derived neurons as an in vitro tool to screen and identify antisense oligonucleotides (ASOs) to selectively decrease the expression of mutant ataxin-3 as a potential treatment for SCA3.