Mutant CAG Repeats Effectively Targeted by RNA Interference in SCA7 Cells

Area of Science:

• Neurogenetics
• Molecular Biology
• RNA Therapeutics

Background:

• Spinocerebellar ataxia type 7 (SCA7) is a human neurodegenerative disease characterized by polyglutamine (polyQ) expansion in the ATXN7 gene.
• Current therapeutic strategies for polyQ diseases include allele-selective silencing of mutant transcripts.
• Targeting the expanded CAG repeat tract offers a potential strategy for SCA7 treatment.

Purpose of the Study:

• To investigate the feasibility of using RNA interference (RNAi) to selectively target and silence the mutant ATXN7 allele in SCA7.
• To assess the efficacy of allele-selective silencing in reducing mutant ataxin-7 protein levels in patient-derived cells.
• To evaluate the impact of this approach on the expression of the normal ATXN7 allele and other affected genes, such as UCHL1.

Main Methods:

• Development and application of allele-selective oligonucleotides (ONs) designed to target the CAG repeat expansion in the mutant ATXN7 transcript.
• Utilizing RNA interference (RNAi) mechanisms to achieve selective downregulation of the mutant ATXN7 allele.
• Quantification of mutant and normal ataxin-7 protein levels in patient-derived cells.
• Assessment of UCHL1 gene expression levels.

Main Results:

• Demonstrated that RNA interference targeting the repeat tract in the mutant ATXN7 transcript is a feasible approach for SCA7.
• Achieved an efficient decrease in mutant ataxin-7 protein levels in patient-derived cells.
• Showed that specific ONs, such as A2, selectively downregulate the mutant ATXN7 allele while upregulating the normal allele.
• Observed restoration of UCHL1 expression, which is typically downregulated in SCA7.

Conclusions:

• Allele-selective silencing of the mutant ATXN7 transcript via RNA interference is a promising therapeutic strategy for Spinocerebellar ataxia type 7.
• The developed ONs demonstrate high allele selectivity and efficacy in reducing toxic protein aggregates and restoring normal gene function.
• This approach holds potential for treating SCA7 and possibly other polyglutamine diseases.