Abstract
Gene silencing through RNA interference (RNAi) is carried out by RISC, the RNA-induced silencing complex. RISC contains two signature components, small interfering RNAs (siRNAs) and Argonaute family proteins. Here, we show that the multiple Argonaute proteins present in mammals are both biologically and biochemically distinct, with a single mammalian family member, Argonaute2, being responsible for messenger RNA cleavage activity. This protein is essential for mouse development, and cells lacking Argonaute2 are unable to mount an experimental response to siRNAs. Mutations within a cryptic ribonuclease H domain within Argonaute2, as identified by comparison with the structure of an archeal Argonaute protein, inactivate RISC. Thus, our evidence supports a model in which Argonaute contributes "Slicer" activity to RISC, providing the catalytic engine for RNAi.
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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Amino Acid Sequence
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Animals
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Argonaute Proteins
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Catalysis
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Cell Line
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Cells, Cultured
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Central Nervous System / embryology
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Embryonic and Fetal Development
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Eukaryotic Initiation Factor-2
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Gene Expression Profiling
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Gene Expression Regulation, Developmental
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Humans
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In Situ Hybridization
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Mice
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MicroRNAs / metabolism
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Molecular Sequence Data
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Mutagenesis, Insertional
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Oligonucleotide Array Sequence Analysis
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Peptide Initiation Factors / chemistry
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Peptide Initiation Factors / metabolism*
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Point Mutation
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RNA Interference*
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RNA, Double-Stranded
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RNA, Messenger / metabolism*
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RNA, Small Interfering / metabolism
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RNA-Induced Silencing Complex / chemistry
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RNA-Induced Silencing Complex / metabolism*
Substances
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AGO2 protein, human
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Argonaute Proteins
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Eukaryotic Initiation Factor-2
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MicroRNAs
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Peptide Initiation Factors
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RNA, Double-Stranded
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RNA, Messenger
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RNA, Small Interfering
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RNA-Induced Silencing Complex