title: The DEAD box helicase RDE-12 promotes amplification of RNAi in cytoplasmic foci in C. elegans.
abstract: RNAi is a potent mechanism for downregulating gene expression. Conserved RNAi pathway components are found in animals, plants, fungi, and other eukaryotes. In C. elegans, the RNAi response is greatly amplified by the synthesis of abundant secondary small interfering RNAs (siRNAs). Exogenous double-stranded RNA is processed by Dicer and RDE-1/Argonaute into primary siRNA that guides target mRNA recognition. The RDE-10/RDE-11 complex and the RNA-dependent RNA polymerase RRF-1 then engage the target mRNA for secondary siRNA synthesis. However, the molecular link between primary siRNA production and secondary siRNA synthesis remains largely unknown. Furthermore, it is unclear whether the subcellular sites for target mRNA recognition and degradation coincide with sites where siRNA synthesis and amplification occur. In the C. elegans germline, cytoplasmic P granules at the nuclear pores and perinuclear Mutator foci contribute to target mRNA surveillance and siRNA amplification, respectively. We report that RDE-12, a conserved phenylalanine-glycine (FG) domain-containing DEAD box helicase, localizes in P granules and cytoplasmic foci that are enriched in RSD-6 but are excluded from the Mutator foci. Our results suggest that RDE-12 promotes secondary siRNA synthesis by orchestrating the recruitment of RDE-10 and RRF-1 to primary siRNA-targeted mRNA in distinct cytoplasmic compartments.
authors.affiliation: Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Huan
authors.initials: H
authors.lastname: Yang
authors.affiliation: Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
authors.forename: Jim
authors.initials: J
authors.lastname: Vallandingham
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Philip
authors.initials: P
authors.lastname: Shiu
authors.affiliation: Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Craig P
authors.initials: CP
authors.lastname: Hunter
authors.affiliation: Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA. Electronic address: hym@ust.hk.
authors.forename: Ho Yi
authors.initials: HY
authors.lastname: Mak
mesh_terms: D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D003594:Cytoplasmic Granules / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D040461:Gene Components; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D034622:RNA Interference / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000096:biosynthesis* / Q000235:genetics; D016601:RNA-Binding Proteins / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D029742:Caenorhabditis elegans Proteins; D017931:DNA Primers; C572735:RDE-10 protein, C elegans; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D012324:RNA-Dependent RNA Polymerase; C574791:RRF-1 protein, C elegans; D053487:DEAD-box RNA Helicases; C000600925:RDE-12 protein, C elegans