DNA double-strand break-free CRISPR interference delays Huntington's disease progression in mice

The use of CRISPR interference (CRISPRi) to repress the expression of mutant with relative preservation of wild-type huntingtin may represent a potential therapeutic strategy to delay disease progression in a mouse model of Huntington's disease. Huntington's disease (HD) is caused by a CAG repeat expansion in the huntingtin (HTT) gene. CRISPR-Cas9 nuclease causes double-strand breaks (DSBs) in the targeted DNA that induces toxicity, whereas CRISPR interference (CRISPRi) using dead Cas9 (dCas9) suppresses the target gene expression without DSBs. Delivery of dCas9-sgRNA targeting CAG repeat region does not damage the targeted DNA in HEK293T cells containing CAG repeats. When this study investigates whether CRISPRi can suppress mutant HTT (mHTT), CRISPRi results in reduced expression of mHTT with relative preservation of the wild-type HTT in human HD fibroblasts. Although both dCas9 and Cas9 treatments reduce mHTT by sgRNA targeting the CAG repeat region, CRISPRi delays behavioral deterioration and protects striatal neurons against cell death in HD mice. Collectively, CRISPRi can delay disease progression by suppressing mHtt, suggesting DNA DSB-free CRISPRi is a potential therapy for HD that can compensate for the shortcoming of CRISPR-Cas9 nuclease.

Automated summary

The use of CRISPR interference (CRISPRi) can repress the expression of mutant huntingtin while preserving wild-type huntingtin, potentially delaying disease progression in Huntington's disease, which is caused by a CAG repeat expansion in the huntingtin gene.