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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Animals, Genetically Modified
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Bacterial Proteins*
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Caenorhabditis elegans / embryology
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Caenorhabditis elegans / genetics*
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Endoribonucleases / physiology
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Gene Silencing / physiology*
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Helminth Proteins / genetics
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Helminth Proteins / physiology*
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Models, Genetic*
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RNA, Double-Stranded / physiology*
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RNA, Helminth / physiology*
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RNA, Small Interfering
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RNA, Untranslated / physiology*
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RNA-Directed DNA Polymerase / physiology*
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Recombinant Fusion Proteins / physiology
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Ribonuclease III
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Sequence Deletion
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Transcription Factors / genetics
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Transcription Factors / physiology*
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Transgenes
Substances
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Bacterial Proteins
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Helminth Proteins
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RNA, Double-Stranded
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RNA, Helminth
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RNA, Small Interfering
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RNA, Untranslated
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Recombinant Fusion Proteins
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Transcription Factors
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frr1 protein, Lactococcus lactis
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RNA-Directed DNA Polymerase
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Endoribonucleases
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Ribonuclease III