Expanded Polyglutamine-Binding Peptoid as a Novel Therapeutic Agent for Treatment of Huntington's Disease

SummaryPolyglutamine(polyQ)-expanded proteins are potential therapeutic targets for the treatment of polyQ expansion disorders such as Huntington's disease (HD) and spinocerebellar ataxia type 3 (SCA3). Here, we used an amino-terminal fragment of a mutant Huntingtin protein (Htt-N-82Q) as bait in an unbiased screen of a 60,000 peptoid library. Peptoid HQP09 was selected from the isolated hits and confirmed as a specific ligand of Htt-N-82Q and Atxn3-77Q mutant proteins in biochemical experiments. We identified three critical residues in the HQP09 sequence that are important for its activity and generated a minimal derivative, HQP09_9, which maintains the specific polyQ-binding activity. We demonstrated that HQP09 and HQP09_9 inhibited aggregation of Htt-N-53Q in vitro and exerted Ca2+-stabilizing and neuroprotective effects in experiments with primary striatal neuronal cultures derived from HD mice. We further demonstrated that intracerebroventricular delivery of HQP09 to an HD mouse model resulted in reduced accumulation of mutant Huntingtin aggregates and improved motor behavioral outcomes. These results suggest that HQP09 and similar peptoids hold promise as novel therapeutics for developing treatments for HD, SCA3, and other polyglutamine expansion disorders.

Graphical AbstractFigure optionsDownload high-quality image (172 K)Download as PowerPoint slideHighlights
► In an unbiased screen, identified a peptoid molecule (HQP09) that specifically binds to expanded polyglutamine track in Huntingtin and Ataxin-3 proteins
► Demonstrated ability of HQP09 to block aggregation of mutant Huntingtin in vitro
► Demonstrated that HQP09 exhibits calcium stabilizing and neuroprotective effects in studies with transgenic HD mouse neurons
► Demonstrated that intracerebroventricular delivery of HQP09 to an HD mouse model resulted in reduced accumulation of mutant Huntingtin aggregates and improved motor behavioral outcomes
► Developed peptoid reagent constitutes a novel class of potential therapeutics for HD and other polyglutamine expansion disorders