title: Roles of R2D2, a cytoplasmic D2 body component, in the endogenous siRNA pathway in Drosophila.
abstract: Endogenous small interfering RNAs (endo-siRNAs) in Drosophila are processed by Dicer-2 (Dcr-2) and loaded onto Ago2 by the Dcr-2/R2D2 heterodimer. In r2d2 mutants, the level of endo-siRNAs is unchanged, but endo-siRNAs are misloaded onto Ago1. However, the mechanism underlying the control of endo-siRNA sorting by R2D2 remains unknown. Here, we show that R2D2 controls endo-siRNA sorting by localizing Dcr-2, and presumably endo-siRNA duplexes, to cytoplasmic foci, D2 bodies. Ago2, but not Ago1, localized to D2 bodies. dsRNA-binding-deficient mutant, but not wild-type, R2D2 failed to localize D2 bodies and caused endo-siRNA misdirection to Ago1 in R2D2-depleted cells. However, R2D2 was dispensable for sorting miRNAs and exogenous siRNAs onto Ago1 and Ago2, respectively, in vivo. Endo- and exo-siRNA guide selection also occurred R2D2 independently. The functions of R2D2 are required to avoid endo-siRNA misdirection to Ago1, because Ago1 is capable of loading incompletely complementary miRNA duplexes and endo-siRNA duplexes.
authors: Department of Molecular Biology, Keio University School of Medicine, Tokyo 160-8582, Japan.
authors: Kazumichi M
authors: KM
authors: Nishida
authors: Keita
authors: K
authors: Miyoshi
authors: Akiyo
authors: A
authors: Ogino
authors: Tomohiro
authors: T
authors: Miyoshi
authors: Haruhiko
authors: H
authors: Siomi
authors: Mikiko C
authors: MC
authors: Siomi
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000378:metabolism; D002460:Cell Line; D003594:Cytoplasmic Granules / Q000378:metabolism*; D029721:Drosophila Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics*; D005260:Female; D009865:Oocytes / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D021381:Protein Transport; D020365:RNA Helicases / Q000737:chemistry / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D043244:Ribonuclease III / Q000737:chemistry / Q000378:metabolism
chemical_list: C433807:AGO2 protein, Drosophila; D060565:Argonaute Proteins; D029721:Drosophila Proteins; C478068:R2D2 protein, Drosophila; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C478069:DCR-2 protein, Drosophila; D043244:Ribonuclease III; D020365:RNA Helicases