Peptide therapeutics to prevent protein aggregation in Huntington’s disease

Abstract

Huntington’s disease is a progressive, autosomal dominant neurodegenerative disease caused by dramatic CAG repeat expansion in exon 1 of the Huntington (HTT) gene. More than 36 CAG repeats lead to the generation of mutant HTT (mHTT) fragments. These amino-terminal mutant HTT fragments result in misfolded proteins that give rise to oligomers and subsequent aggregate formation in relevant brain areas. Available therapies mainly focus on ameliorating the symptoms of the disease. Therefore, therapeutic interventions which can delay the onset of disease are imperative for halting disease progression. Peptide-based drug therapy provide such a platform. Previously in our lab, candidate ligand peptides were screened against both willd type (Htt-Q25) and mHTT fragments such as Htt-Q46, and Htt-Q103. This was done using different display technologies This work focuses on the in vitro characterization of those selected peptides. Fibril formation was observed in real-time using Thiofllavin T assay. Selected peptides were added to check their effect on fibril formation by change in fluorescence signal. The effect of peptides on fibril formation was also studied using Atomic Force microscopy. 3 of the 6 selected peptides (HHGANSLSLVSQD), (HGLHSMHNKLTR) and (WMFPSLKLLDYH) successfully showed a blocking in aggregation. These studies show that the selected peptides are affective for inhibiting the aggregation of fibrils in mHTT proteins.