Abstract
The RNase III enzyme Dicer processes RNA into siRNAs and miRNAs, which direct a RNA-induced silencing complex (RISC) to cleave mRNA or block its translation (RNAi). We have characterized mutations in the Drosophila dicer-1 and dicer-2 genes. Mutation in dicer-1 blocks processing of miRNA precursors, whereas dicer-2 mutants are defective for processing siRNA precursors. It has been recently found that Drosophila Dicer-1 and Dicer-2 are also components of siRNA-dependent RISC (siRISC). We find that Dicer-1 and Dicer-2 are required for siRNA-directed mRNA cleavage, though the RNase III activity of Dicer-2 is not required. Dicer-1 and Dicer-2 facilitate distinct steps in the assembly of siRISC. However, Dicer-1 but not Dicer-2 is essential for miRISC-directed translation repression. Thus, siRISCs and miRISCs are different with respect to Dicers in Drosophila.
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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Drosophila Proteins / genetics
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Drosophila Proteins / metabolism*
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Drosophila melanogaster / genetics*
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Eye Abnormalities / genetics*
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Female
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Male
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MicroRNAs / genetics*
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MicroRNAs / metabolism
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Molecular Sequence Data
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Mutation / genetics
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Protein Biosynthesis / genetics
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Protein Structure, Tertiary / physiology
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RNA Helicases / genetics
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RNA Helicases / metabolism*
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RNA Interference / physiology*
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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RNA, Small Interfering / genetics*
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RNA, Small Interfering / metabolism
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RNA-Induced Silencing Complex / genetics
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RNA-Induced Silencing Complex / metabolism
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Ribonuclease III / genetics
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Ribonuclease III / metabolism*
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Sequence Homology, Amino Acid
Substances
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Drosophila Proteins
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MicroRNAs
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RNA, Messenger
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RNA, Small Interfering
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RNA-Induced Silencing Complex
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DCR-2 protein, Drosophila
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Ribonuclease III
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RNA Helicases