Genome editing in spinocerebellar ataxia type 3 cells improves Golgi apparatus structure

Abstract

Abstract Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disease caused by repeat expansion of the CAG trinucleotide within exon 10 of the ATXN3 gene. This mutation results in the production of an abnormal ataxin-3 protein containing an extended polyglutamine tract, referred to as mutant ataxin-3. In this study, we investigated the therapeutic potential of CRISPR/Cas9-mediated genome editing for SCA3. First, we designed a specific single-guide RNA targeting the ATXN3 gene and constructed the corresponding targeting vector. Induced pluripotent stem cells (iPSCs) derived from a SCA3 patient were then electroporated with the CRISPR/Cas9 components. Positive clones were screened and validated by PCR and Sanger sequencing to obtain genome-editing iPSCs (GE-iPSCs). Subsequently, the pluripotency of GE-iPSCs was confirmed, and the effects of genome editing on mutant ataxin-3 protein expression and Golgi apparatus morphology were assessed using Western blotting and immunofluorescence analyses. Our results demonstrated that targeted insertion of polyadenylation signals (PAS) upstream of the abnormal CAG repeats effectively suppressed the production of mutant ataxin-3. This intervention also reduced the formation of neuronal nuclear inclusions in differentiated neurons, restored the structural integrity of the Golgi apparatus (which exhibited a loose and enlarged morphology in SCA3 cells), and increased the expression levels of Golgi structural proteins (GM130 and GORASP2). In conclusion, our findings indicate that the targeted insertion of PAS upstream of the abnormal CAG repeats in the ATXN3 gene represents a promising therapeutic strategy for SCA3 through genome editing.

Keywords

• Spinocerebellar ataxia type 3
• CRISPR/Cas9
• Golgi apparatus
• Genome editing