Ataxin-1 (ATXN1) is a nuclear-cytoplasmic shuttling protein that plays roles in transcriptional regulation, RNA processing, and synaptic development. Expansions of a CAG trinucleotide repeat in the ATXN1 gene cause Spinocerebellar Ataxia Type 1 (SCA1), an autosomal dominant neurodegenerative disorder characterized by progressive cerebellar degeneration and brainstem dysfunction.[1]
Ataxin-1 contains several functional domains:
The AXH domain adopts an OB-fold structure and mediates dimerization and interaction with transcription factors and RNA-binding proteins.[2]
Ataxin-1 functions in transcriptional complexes:
The AXH domain binds RNA and influences:[3]
Ataxin-1 is essential for:
CAG repeat expansion causes SCA1 through multiple mechanisms:[4]
SCA1 severity is modified by:
| Strategy | Mechanism | Status |
|---|---|---|
| S776 phosphorylation inhibitors | Reduce mutant ataxin-1 stability | Preclinical |
| AXH domain disruptors | Prevent protein-protein interactions | Discovery |
| Proteostasis modulators | Enhance clearance of mutant protein | Preclinical |
| Partner | Function | Disease Relevance |
|---|---|---|
| CIC (Capicua) | Transcriptional repressor | SCA1 transcriptional dysregulation |
| RBM17 | RNA splicing factor | Altered splicing in SCA1 |
| ATXN1L | Ataxin-1-like protein | Functional redundancy |
| 14-3-3 proteins | Phospho-binding proteins | S776-mediated stabilization |
Orr HT, et al. Expansion of an unstable trinucleotide CAG repeat in spinocerebellar ataxia 1. Nature Genetics. 1993. ↩︎
de Chiara C, et al. The AXH domain of Ataxin-1 mediates neurodegeneration through its interaction with Gfi-1/Senseless proteins. Journal of Neuroscience. 2009. ↩︎
Lam YC, et al. The AXH domain of Ataxin-1 mediates protein-protein and protein-RNA interactions. Journal of Molecular Biology. 2012. ↩︎
Klement IA, et al. [Ataxin-1 nuclear localization and aggregation: role in polyglutamine-induced disease in SCA1 transgenic mice](https://doi.org/10.1016/s0092-8674(00). Cell. 1998. ↩︎
Park J, et al. Genetic modifiers of SCA1 identified through genome-wide association study in a founder population. Brain. 2021. ↩︎