title: Cell stress is related to re-localization of Argonaute 2 and to decreased RNA interference in human cells.
abstract: Various kinds of stress on human cells induce the formation of endogenous stress granules (SGs). Human Argonaute 2 (hAgo2), the catalytic core component of the RNA-induced silencing complex (RISC), can be recruited to SGs as well as P-bodies (PBs) indicating that the dynamic intracellular distribution of hAgo2 in SGs, in PBs or at other sub-cellular sites could be related to the efficiency of the RNA interference (RNAi) machinery. Here, we studied the influence of heat shock, sodium arsenite (NaAsO2), cycloheximide (CHX) and Lipofectamine 2000-mediated transfection of phosphorothioate (PS)-modified oligonucleotides (ON) on the intracellular localization of hAgo2 and the efficiency of RNAi. Fluorescence microscopy and sedimentation analysis of cell fractions indicate stress-induced accumulation of hAgo2 in SGs and the loss of distinctly composed complexes containing hAgo2 or their sub-cellular context. Transfection of cells with PS-ON induces cell stress that is phenotypically similar to the established inducers heat shock and NaAsO2. The intracellular re-distribution of hAgo2 is related to its increased metabolic stability and to decreased RNAi directed by microRNA or by short interfering RNA. Here, we propose a functional model of the relationship between cell stress, translocation of hAgo2 to SGs providing a depot function, and loss of RNAi activity.
authors.affiliation: Institut für Molekulare Medizin, Centre for Structural and Cell Biology in Medicine (CSCM), Universität zu Lübeck and UK S-H, Ratzeburger Allee 160, D-23538 Lübeck, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Detzer
authors.forename: Christina
authors.initials: C
authors.lastname: Engel
authors.forename: Winfried
authors.initials: W
authors.lastname: Wünsche
authors.forename: Georg
authors.initials: G
authors.lastname: Sczakiel
mesh_terms: D060565:Argonaute Proteins; D002460:Cell Line; D003594:Cytoplasmic Granules / Q000737:chemistry / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2 / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D009841:Oligonucleotides / Q000737:chemistry; D021381:Protein Transport; D034622:RNA Interference; D013312:Stress, Physiological
chemical_list: C466422:AGO2 protein, human; D060565:Argonaute Proteins; D015852:Eukaryotic Initiation Factor-2; D009841:Oligonucleotides