A genome-scale RNA-interference screen identifies RRAS signaling as a pathologic feature of Huntington's disease.

A genome-scale RNAi screen was performed in a mammalian cell-based assay to identify modifiers of mutant huntingtin toxicity. Ontology analysis of suppressor data identified processes previously implicated in Huntington's disease, including proteolysis, glutamate excitotoxicity, and mitochondrial dysfunction. In addition to established mechanisms, the screen identified multiple components of the RRAS signaling pathway as loss-of-function suppressors of mutant huntingtin toxicity in human and mouse cell models.

Caspase-6 activity in a BACHD mouse modulates steady-state levels of mutant huntingtin protein but is not necessary for production of a 586 amino acid proteolytic fragment.

Huntington's disease (HD) is caused by a mutation in the huntingtin (htt) gene encoding an expansion of glutamine repeats at the N terminus of the Htt protein. Proteolysis of Htt has been identified as a critical pathological event in HD models. In particular, it has been postulated that proteolysis of Htt at the putative caspase-6 cleavage site (at amino acid Asp-586) plays a critical role in disease progression and pathogenesis.

Identification and evaluation of small molecule pan-caspase inhibitors in Huntington's disease models.

Huntington's Disease (HD) is characterized by a mutation in the huntingtin (Htt) gene encoding an expansion of glutamine repeats on the N terminus of the Htt protein. Numerous studies have identified Htt proteolysis as a critical pathological event in HD postmortem human tissue and mouse HD models, and proteases known as caspases have emerged as attractive HD therapeutic targets. We report the use of the substrate activity screening method against caspase-3 and -6 to identify three novel, pan-caspase inhibitors that block proteolysis of Htt at caspase-3 and -6 cleavage sites.

Matrix metalloproteinases are modifiers of huntingtin proteolysis and toxicity in Huntington's disease.

Proteolytic cleavage of huntingtin (Htt) is known to be a key event in the pathogenesis of Huntington's disease (HD). Our understanding of proteolytic processing of Htt has thus far focused on the protease families-caspases and calpains. Identifying critical proteases involved in Htt proteolysis and toxicity using an unbiased approach has not been reported.

Proteolysis of mutant huntingtin produces an exon 1 fragment that accumulates as an aggregated protein in neuronal nuclei in Huntington disease.

Huntingtin proteolysis has been implicated in the molecular pathogenesis of Huntington disease (HD). Despite an intense effort, the identity of the pathogenic smallest N-terminal fragment has not been determined. Using a panel of anti-huntingtin antibodies, we employed an unbiased approach to generate proteolytic cleavage maps of mutant and wild-type huntingtin in the HdhQ150 knock-in mouse model of HD.