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Updated: Jun 21, 2025
CRISPR/Cas9-mediated Targeted Integration In Vivo Using a Homology-mediated End Joining-based Strategy
Published on: March 12, 2018
In vivo CRISPR base editing for treatment of Huntington's disease
Insights
CRISPR base editing offers a novel approach to Huntington's disease (HD) treatment. This method engineers resistance to toxic protein fragment formation, reducing neuronal damage in HD models.
Area of Science:
- Neuroscience
- Genetics
- Molecular Biology
Background:
- Huntington's disease (HD) is a fatal neurodegenerative disorder.
- It stems from an expanded CAG repeat in the huntingtin (HTT) gene.
- Proteolytic cleavage of mutant HTT by caspase-6 generates toxic fragments, a key pathogenic event.
Purpose of the Study:
- To investigate CRISPR base editing as a therapeutic strategy for HD.
- To develop HTT protein variants resistant to caspase-6 cleavage.
- To assess the efficacy of base editing in reducing HD pathology.
Main Methods:
- Screened 141 CRISPR base editor variants targeting HTT gene splice elements.
- Edited the splice acceptor sequence for exon 13 to induce exon skipping.
- Delivered base editors to the striatum of a rodent HD model.
Main Results:
- Identified base editors producing HTT isoforms resistant to caspase-6 proteolysis.
- Achieved efficient exon skipping and reduced N-terminal fragment formation.
- Observed decreased HTT protein aggregation and attenuated striatal/cortical atrophy.
Conclusions:
- CRISPR base editing shows potential for treating Huntington's disease.
- Editing HTT splice elements can mitigate key pathogenic mechanisms.
- This approach may reduce mutant HTT protein toxicity in HD.
Abstract:
Huntington's disease (HD) is an inherited and ultimately fatal neurodegenerative disorder caused by an expanded polyglutamine-encoding CAG repeat within exon 1 of the huntingtin (HTT) gene, which produces a mutant protein that destroys striatal and cortical neurons. Importantly, a critical event in the pathogenesis of HD is the proteolytic cleavage of the mutant HTT protein by caspase-6, which generates fragments of the N-terminal domain of the protein that form highly toxic aggregates. Given the role that proteolysis of the mutant HTT protein plays in HD, strategies for preventing this process hold potential for treating the disorder. By screening 141 CRISPR base editor variants targeting splice elements in the HTT gene, we identified platforms capable of producing HTT protein isoforms resistant to caspase-6-mediated proteolysis via editing of the splice acceptor sequence for exon 13. When delivered to the striatum of a rodent HD model, these base editors induced efficient exon skipping and decreased the formation of the N-terminal fragments, which in turn reduced HTT protein aggregation and attenuated striatal and cortical atrophy. Collectively, these results illustrate the potential for CRISPR base editing to decrease the toxicity of the mutant HTT protein for HD.
