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, 117 (1), 69-81

Distinct Roles for Drosophila Dicer-1 and Dicer-2 in the siRNA/miRNA Silencing Pathways

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Distinct Roles for Drosophila Dicer-1 and Dicer-2 in the siRNA/miRNA Silencing Pathways

Young Sik Lee et al. Cell.

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.

Comment in

  • Dicers at RISC; The Mechanism of RNAi
    M Tijsterman et al. Cell 117 (1), 1-3. PMID 15066275. - Review
    The pathway of RNA interference starts when Dicer cuts dsRNA into small interfering RNAs (siRNAs) that subsequently target homologous mRNAs for destruction. microRNA proc …

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