Short-interfering-RNA-mediated gene silencing in mammalian cells requires Dicer and eIF2C translation initiation factors.

RNA interference (RNAi) is the process of long, double-stranded (ds), RNA-dependent posttranscriptional gene silencing (PTGS). In lower eukaryotes, dsRNA introduced into the cytoplasm is cleaved by the RNaseIII-like enzyme, Dicer, to 21-23 nt RNA (short interfering [si] RNA), which may serve as guide for target mRNA degradation. In mammals, long-dsRNA-dependent ...
PTGS is applicable only to a limited number of cell types, whereas siRNA synthesized in vitro is capable of effectively inducing gene silencing in a wide variety of cells. Although biochemical and genetic analyses in lower eukaryotes showed that Dicer and some PIWI family member proteins are essential for long-dsRNA-dependent PTGS, little is known about the molecular mechanisms underlying siRNA-based PTGS. Here, we show that Dicer and eIF2C translation initiation factors belonging to the PIWI family (eIF2C1-4) play an essential role in mammalian siRNA-mediated PTGS, most probably through synergistic interactions. Immunoprecipitation experiments suggest that, in human and mouse cells, complex formation occurs between Dicer and eIF2C1 or 2 and that the PIWI domain of eIF2C is essential for the formation of this complex.
Mesh Terms:
3T3 Cells, Amino Acid Sequence, Animals, Endoribonucleases, Eukaryotic Initiation Factors, Gene Silencing, Genes, myc, Hela Cells, Humans, Macromolecular Substances, Mammals, Mice, Molecular Sequence Data, Peptide Initiation Factors, Precipitin Tests, Protein Biosynthesis, RNA Interference, RNA, Small Interfering, Ribonuclease III
Curr. Biol.
Date: Jan. 08, 2003
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