Allele-Specific Knockdown of Mutant Huntingtin Protein via Editing at Coding Region Single Nucleotide Polymorphism Heterozygosities.

Huntington's disease (HD) is a devastating, autosomal dominant neurodegenerative disease caused by a trinucleotide repeat expansion in the huntingtin (HTT) gene. Inactivation of the mutant allele by clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 based gene editing offers a possible therapeutic approach for this disease, but permanent disruption of normal HTT function might compromise adult neuronal function. Here, we use a novel HD mouse model to examine allele-specific editing of mutant HTT (mHTT), with a BAC97 transgene expressing mHTT and a YAC18 transgene expressing normal HTT.

Safe and Efficient Silencing with a Pol II, but Not a Pol lII, Promoter Expressing an Artificial miRNA Targeting Human Huntingtin.

Huntington's disease is a devastating, incurable neurodegenerative disease affecting up to 12 per 100,000 patients worldwide. The disease is caused by a mutation in the Huntingtin (Htt) gene. There is interest in reducing mutant Huntingtin by targeting it at the mRNA level, but the maximum tolerable dose and long-term effects of such a treatment are unknown.

Does the Mutant CAG Expansion in Huntingtin mRNA Interfere with Exonucleolytic Cleavage of its First Exon?

Background: Silencing mutant huntingtin mRNA by RNA interference (RNAi) is a therapeutic strategy for Huntington's disease. RNAi induces specific endonucleolytic cleavage of the target HTT mRNA, followed by exonucleolytic processing of the cleaved mRNA fragments.

Objectives: We investigated the clearance of huntingtin mRNA cleavage products following RNAi, to find if particular huntingtin mRNA sequences persist.

Increased Steady-State Mutant Huntingtin mRNA in Huntington's Disease Brain.

Background: Huntington's disease is caused by expansion of CAG trinucleotide repeats in the first exon of the huntingtin gene, which is essential for both development and neurogenesis. Huntington's disease is autosomal dominant. The normal allele contains 6 to 35 CAG triplets (average, 18) and the mutant, disease-causing allele contains >36 CAG triplets (average, 42).

Increased huntingtin protein length reduces the number of polyglutamine-induced gene expression changes in mouse models of Huntington's disease.

Both transcriptional dysregulation and proteolysis of mutant huntingtin (htt) are postulated to be important components of Huntington's disease (HD) pathogenesis. In previous studies, we demonstrated that transgenic mice that express short mutant htt fragments containing 171 or fewer N-terminal residues (R6/2 and N171-82Q mice) recapitulate many of the mRNA changes observed in human HD brain. To examine whether htt protein length influences the ability of its expanded polyglutamine domain to alter gene expression, we conducted mRNA profiling analyses of mice that express an extended N-terminal fragment (HD46, HD100; 964 amino acids) or full-length (YAC72; 3144 amino acids) mutant htt transprotein.