On the role of RNA amplification in dsRNA-triggered gene silencing.
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.
Sijen
T
T
Hubrecht Laboratory, Center for Biomedical Genetics, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands.
Fleenor
J
J
Simmer
F
F
Thijssen
K L
KL
Parrish
S
S
Timmons
L
L
Plasterk
R H
RH
Fire
A
A
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
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