title: On the role of RNA amplification in dsRNA-triggered gene silencing.
abstract: We have investigated the role of trigger RNA amplification during RNA interference (RNAi) in Caenorhabditis elegans. Analysis of small interfering RNAs (siRNAs) produced during RNAi in C. elegans revealed a substantial fraction that cannot derive directly from input dsRNA. Instead, a population of siRNAs (termed secondary siRNAs) appeared to derive from the action of a cellular RNA-directed RNA polymerase (RdRP) on mRNAs that are being targeted by the RNAi mechanism. The distribution of secondary siRNAs exhibited a distinct polarity (5'-->3' on the antisense strand), suggesting a cyclic amplification process in which RdRP is primed by existing siRNAs. This amplification mechanism substantially augments the potency of RNAi-based surveillance, while ensuring that the RNAi machinery will focus on expressed mRNAs.
authors.affiliation: Hubrecht Laboratory, Center for Biomedical Genetics, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands.
authors.forename: T
authors.initials: T
authors.lastname: Sijen
authors.forename: J
authors.initials: J
authors.lastname: Fleenor
authors.forename: F
authors.initials: F
authors.lastname: Simmer
authors.forename: K L
authors.initials: KL
authors.lastname: Thijssen
authors.forename: S
authors.initials: S
authors.lastname: Parrish
authors.forename: L
authors.initials: L
authors.lastname: Timmons
authors.forename: R H
authors.initials: RH
authors.lastname: Plasterk
authors.forename: A
authors.initials: A
authors.lastname: Fire
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001426:Bacterial Proteins; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics*; D004722:Endoribonucleases / Q000502:physiology; D020868:Gene Silencing / Q000502:physiology*; D015801:Helminth Proteins / Q000235:genetics / Q000502:physiology*; D008957:Models, Genetic; D012330:RNA, Double-Stranded / Q000502:physiology*; D018510:RNA, Helminth / Q000502:physiology*; D034741:RNA, Small Interfering; D022661:RNA, Untranslated / Q000502:physiology*; D012194:RNA-Directed DNA Polymerase / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000502:physiology; D043244:Ribonuclease III; D017384:Sequence Deletion; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D019076:Transgenes
chemical_list: D001426:Bacterial Proteins; D015801:Helminth Proteins; D012330:RNA, Double-Stranded; D018510:RNA, Helminth; D034741:RNA, Small Interfering; D022661:RNA, Untranslated; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C404342:frr1 protein, Lactococcus lactis; D012194:RNA-Directed DNA Polymerase; D004722:Endoribonucleases; D043244:Ribonuclease III