title: High-throughput screen of natural product extracts in a yeast model of polyglutamine proteotoxicity.
abstract: Proteins with expanded polyglutamine (polyQ) segments cause a number of fatal neurodegenerative disorders, including Huntington's disease (HD). Previous high-throughput screens in cellular and biochemical models of HD have revealed compounds that mitigate polyQ aggregation and proteotoxicity, providing insight into the mechanisms of disease and leads for potential therapeutics. However, the structural diversity of natural products has not yet been fully mobilized toward these goals. Here, we have screened a collection of ~11 000 natural product extracts for the ability to recover the slow growth of ΔProQ103-expressing yeast cells in 384-well plates (Z' ~ 0.7, CV ~ 8%). This screen identified actinomycin D as a strong inhibitor of polyQ aggregation and proteotoxicity at nanomolar concentrations (~50-500 ng/mL). We found that a low dose of actinomycin D increased the levels of the heat-shock proteins Hsp104, Hsp70 and Hsp26 and enhanced binding of Hsp70 to the polyQ in yeast. Actinomycin also suppressed aggregation of polyQ in mammalian cells, suggesting a conserved mechanism. These results establish natural products as a rich source of compounds with interesting mechanisms of action against polyQ disorders.
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, MI, 48109-2216, USA; Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109-2216, USA.
authors.forename: Gladis M
authors.initials: GM
authors.lastname: Walter
authors.forename: Avi
authors.initials: A
authors.lastname: Raveh
authors.forename: Sue-Ann
authors.initials: SA
authors.lastname: Mok
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: McQuade
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Arevang
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Schultz
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Smith
authors.forename: Samuel
authors.initials: S
authors.lastname: Asare
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Cruz
authors.forename: Susanne
authors.initials: S
authors.lastname: Wisen
authors.forename: Teatulohi
authors.initials: T
authors.lastname: Matainaho
authors.forename: David H
authors.initials: DH
authors.lastname: Sherman
authors.forename: Jason E
authors.initials: JE
authors.lastname: Gestwicki
mesh_terms: D000818:Animals; D001688:Biological Products / Q000032:analysis / Q000737:chemistry*; D003609:Dactinomycin / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D057166:High-Throughput Screening Assays; D006801:Humans; D008954:Models, Biological; D016716:PC12 Cells; D010455:Peptides / Q000737:chemistry / Q000235:genetics*; D066263:Protein Aggregation, Pathological / Q000188:drug therapy; D051381:Rats; D012441:Saccharomyces cerevisiae
chemical_list: D001688:Biological Products; D010455:Peptides; D003609:Dactinomycin; C097188:polyglutamine
keywords: Huntington's disease; heat shock protein 70; high throughput screening; molecular chaperones