title: Hsp90 regulates the function of argonaute 2 and its recruitment to stress granules and P-bodies.
abstract: Argonaute proteins are effectors of RNA interference that function in the context of cytoplasmic ribonucleoprotein complexes to regulate gene expression. Processing bodies (PBs) and stress granules (SGs) are the two main types of ribonucleoprotein complexes with which Argonautes are associated. Targeting of Argonautes to these structures seems to be regulated by different factors. In the present study, we show that heat-shock protein (Hsp) 90 activity is required for efficient targeting of hAgo2 to PBs and SGs. Furthermore, pharmacological inhibition of Hsp90 was associated with reduced microRNA- and short interfering RNA-dependent gene silencing. Neither Dicer nor its cofactor TAR RNA binding protein (TRBP) associates with PBs or SGs, but interestingly, protein activator of the double-stranded RNA-activated protein kinase (PACT), another Dicer cofactor, is recruited to SGs. Formation of PBs and recruitment of hAgo2 to SGs were not dependent upon PACT (or TRBP) expression. Together, our data suggest that Hsp90 is a critical modulator of Argonaute function. Moreover, we propose that Ago2 and PACT form a complex that functions at the level of SGs.
authors.affiliation: Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Pare
authors.forename: Nasser
authors.initials: N
authors.lastname: Tahbaz
authors.forename: Joaquín
authors.initials: J
authors.lastname: López-Orozco
authors.forename: Paul
authors.initials: P
authors.lastname: LaPointe
authors.forename: Paul
authors.initials: P
authors.lastname: Lasko
authors.forename: Tom C
authors.initials: TC
authors.lastname: Hobman
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D060565:Argonaute Proteins; D016227:Benzoquinones / Q000494:pharmacology; D002460:Cell Line; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000378:metabolism*; D004330:Drosophila; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D020868:Gene Silencing / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D034741:RNA, Small Interfering / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D043244:Ribonuclease III / Q000378:metabolism; D000099253:Trans-Activation Responsive RNA-Binding Protein
chemical_list: D000954:Antigens, Surface; D060565:Argonaute Proteins; D016227:Benzoquinones; D015852:Eukaryotic Initiation Factor-2; D049452:Green Fluorescent Proteins; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D035683:MicroRNAs; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D043244:Ribonuclease III; D000099253:Trans-Activation Responsive RNA-Binding Protein; C466422:AGO2 protein, human; C104647:PRKRA protein, human; C001277:geldanamycin