Green tea (-)-epigallocatechin-gallate modulates early events in huntingtin misfolding and reduces toxicity in Huntington's disease models

Huntington's disease (HD) is a progressive neurodegenerative disorder for which only symptomatic treatments of limited effectiveness are available. Preventing early misfolding steps and thereby aggregation of the polyglutamine (polyQ)-containing protein huntingtin (htt) in neurons of patients may represent an attractive therapeutic strategy to postpone the onset and progression of HD. Here, we demonstrate that the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) potently inhibits the aggregation of mutant htt exon 1 protein in a dose-dependent manner. Dot-blot assays and atomic force microscopy studies revealed that EGCG modulates misfolding and oligomerization of mutant htt exon 1 protein in vitro, indicating that it interferes with very early events in the aggregation process. Also, EGCG significantly reduced polyQ-mediated htt protein aggregation and cytotoxicity in an yeast model of HD. When EGCG was fed to transgenic HD flies overexpressing a pathogenic htt exon 1 protein, photoreceptor degeneration and motor function improved. These results indicate that modulators of htt exon 1 misfolding and oligomerization like EGCG are likely to reduce polyQ-mediated toxicity in vivo. Our studies may provide the basis for the development of a novel pharmacotherapy for HD and related polyQ disorders.