RETRACTED: Secondary siRNAs result from unprimed RNA synthesis and form a distinct class

In Caenorhabditis elegans, an effective RNA interference (RNAi) response requires the production of secondary short interfering RNAs (siRNAs) by RNA-directed RNA polymerases (RdRPs). We cloned secondary siRNAs from transgenic C. elegans lines expressing a single 22-nucleotide primary siRNA. Several...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2007-01, Vol.315 (5809), p.244-247
Main Authors: Sijen, Titia, Steiner, Florian A, Thijssen, Karen L, Plasterk, Ronald H A
Format: Article
Language:English
Subjects:
Animals
Animals, Genetically Modified
Base Pairing
Caenorhabditis elegans - genetics
Caenorhabditis elegans - metabolism
Caenorhabditis elegans Proteins - metabolism
Cloning, Molecular
Phosphates - analysis
Ribonuclease III - metabolism
RNA Interference
RNA, Antisense - biosynthesis
RNA, Antisense - chemistry
RNA, Antisense - metabolism
RNA, Complementary - biosynthesis
RNA, Helminth - biosynthesis
RNA, Helminth - genetics
RNA, Helminth - metabolism
RNA, Messenger - genetics
RNA, Messenger - metabolism
RNA, Small Interfering - biosynthesis
RNA, Small Interfering - chemistry
RNA, Small Interfering - metabolism
RNA-Dependent RNA Polymerase - metabolism
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Summary:In Caenorhabditis elegans, an effective RNA interference (RNAi) response requires the production of secondary short interfering RNAs (siRNAs) by RNA-directed RNA polymerases (RdRPs). We cloned secondary siRNAs from transgenic C. elegans lines expressing a single 22-nucleotide primary siRNA. Several secondary siRNAs start a few nucleotides downstream of the primary siRNA, indicating that non-RISC (RNA-induced silencing complex)-cleaved mRNAs are substrates for secondary siRNA production. In lines expressing primary siRNAs with single-nucleotide mismatches, secondary siRNAs do not carry the mismatch but contain the nucleotide complementary to the mRNA. We infer that RdRPs perform unprimed RNA synthesis. Secondary siRNAs are only of antisense polarity, carry 5' di- or triphosphates, and are only in the minority associated with RDE-1, the RNAi-specific Argonaute protein. Therefore, secondary siRNAs represent a distinct class of small RNAs. Their biogenesis depends on RdRPs, and we propose that each secondary siRNA is an individual RdRP product.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1136699