title: Regulation of RNA interference by Hsp90 is an evolutionarily conserved process.
abstract: RNAi is a highly conserved mechanism in almost every eukaryote with a few exceptions including the model organism Saccharomyces cerevisiae. A recent study showed that the introduction of the two core components of canonical RNAi systems, Argonaute and Dicer, from another budding yeast, Saccharomyces castellii, restores RNAi in S. cerevisiae. We report here that a functional RNAi system can be reconstituted in yeast with the introduction of only S. castellii Dicer and human Argonaute2. Interestingly, whether or not TRBP2 was present, human Dicer was unable to restore RNAi with either S. castellii or human Argonaute. Contrary to previous reports, we find that human Dicer, TRBP2 and Argonaute2 are not sufficient to reconstitute RNAi in yeast when bona fide RNAi precursors are co-expressed. We and others have previously reported that Hsp90 regulates conformational changes in human and Drosophila Argonautes required to accommodate the loading of dsRNA duplexes. Here we show that the activities of both human and S. castellii Argonaute are subject to Hsp90 regulation in S. cerevisiae. In summary, our results suggest that regulation of the RNAi machinery by Hsp90 may have evolved at the same time as ancestral RNAi.
authors.affiliation: Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Canada.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Canada.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Mercier
authors.affiliation: Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Canada; Department of Medical Microbiology & Immunology, Faculty of Medicine and Dentistry, University of Alberta, Canada; Li Ka Shing Institute of Virology, Faculty of Medicine and Dentistry, University of Alberta, Canada.
authors.forename: Tom C
authors.initials: TC
authors.lastname: Hobman
authors.affiliation: Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Canada. Electronic address: paul.lapointe@ualberta.ca.
authors.forename: Paul
authors.initials: P
authors.lastname: LaPointe
mesh_terms: D060565:Argonaute Proteins / Q000737:chemistry / Q000378:metabolism; D019143:Evolution, Molecular; D005453:Fluorescence; D020868:Gene Silencing; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D018942:Macrolides / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism
chemical_list: C466422:AGO2 protein, human; D060565:Argonaute Proteins; D018841:HSP90 Heat-Shock Proteins; D018942:Macrolides; D029701:Saccharomyces cerevisiae Proteins; C554167:URA3 protein, S cerevisiae; D049452:Green Fluorescent Proteins; C035359:monorden
keywords: Argonaute; Dicer; GFP; Hsp90; RNA interference; RNAi; TRBP2; Tar (HIV)-RNA binding protein 2; Yeast; green fluorescent protein