Dysregulation of alternative splicing in spinocerebellar ataxia type 1

Spinocerebellar ataxia type 1 is caused by an expansion of the polyglutamine tract in ATAXIN-1. Ataxin-1 is broadly expressed throughout the brain and is involved in regulating gene expression. However, it is not yet known if mutant ataxin-1 can impact the regulation of alternative splicing events. We performed RNA sequencing in mouse models of spinocerebellar ataxia type 1 and identified that mutant ataxin-1 expression abnormally leads to diverse splicing events in the mouse cerebellum of spinocerebellar ataxia type 1. We found that the diverse splicing events occurred in a predominantly cell autonomous manner. A majority of the transcripts with misregulated alternative splicing events were previously unknown, thus allowing us to identify overall new biological pathways that are distinctive to those affected by differential gene expression in spinocerebellar ataxia type 1. We also provide evidence that the splicing factor Rbfox1 mediates the effect of mutant ataxin-1 on misregulated alternative splicing and that genetic manipulation of Rbfox1 expression modifies neurodegenerative phenotypes in a Drosophila model of spinocerebellar ataxia type 1 in vivo. Together, this study provides novel molecular mechanistic insight into the pathogenesis of spinocerebellar ataxia type 1 and identifies potential therapeutic strategies for spinocerebellar ataxia type 1.

Automated summary

This study reveals that mutant ATAXIN-1 can lead to diverse splicing events and contribute to the pathogenesis of spinocerebellar ataxia type 1. The researchers identify Rbfox1 as a mediator of mutant ATAXIN-1's effect on misregulated alternative splicing and demonstrate that manipulation of Rbfox1 expression can modify neurodegenerative phenotypes in a Drosophila model. These findings provide valuable insights into the molecular mechanisms and potential therapeutic strategies for spinocerebellar ataxia type 1.