Publication Date:
2006-12-13
Description:
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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sijen, Titia -- Steiner, Florian A -- Thijssen, Karen L -- Plasterk, Ronald H A -- New York, N.Y. -- Science. 2007 Jan 12;315(5809):244-7. Epub 2006 Dec 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Hubrecht Laboratory (NIOB-KNAW), Uppsalalaan 8, 3584 CT, the Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17158288" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Animals, Genetically Modified
;
Base Pairing
;
Caenorhabditis elegans/*genetics/metabolism
;
Caenorhabditis elegans Proteins/metabolism
;
Cloning, Molecular
;
Phosphates/analysis
;
*RNA Interference
;
RNA Replicase/metabolism
;
RNA, Antisense/*biosynthesis/chemistry/metabolism
;
RNA, Complementary/biosynthesis
;
RNA, Helminth/*biosynthesis/genetics/metabolism
;
RNA, Messenger/genetics/metabolism
;
RNA, Small Interfering/*biosynthesis/chemistry/metabolism
;
Ribonuclease III/metabolism
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
