Endogenous siRNAs derived from transposons and mRNAs in Drosophila somatic cells
Department of Biochemistry and Molecular Pharmacology; Program in Molecular Medicine; Department of Molecular Genetics and Microbiology; Program in Bioinformatics and Integrative Biology; Graduate School of Biomedical Sciences
Medical Subject Headings
Animals; Base Sequence; Cell Line; *DNA Transposable Elements; Drosophila Proteins; Drosophila melanogaster; Mutation; RNA Helicases; *RNA Interference; RNA, Double-Stranded; RNA, Messenger; RNA, Small Interfering; RNA-Induced Silencing Complex; Retroelements
Life Sciences | Medicine and Health Sciences
Small interfering RNAs (siRNAs) direct RNA interference (RNAi) in eukaryotes. In flies, somatic cells produce siRNAs from exogenous double-stranded RNA (dsRNA) as a defense against viral infection. We identified endogenous siRNAs (endo-siRNAs), 21 nucleotides in length, that correspond to transposons and heterochromatic sequences in the somatic cells of Drosophila melanogaster. We also detected endo-siRNAs complementary to messenger RNAs (mRNAs); these siRNAs disproportionately mapped to the complementary regions of overlapping mRNAs predicted to form double-stranded RNA in vivo. Normal accumulation of somatic endo-siRNAs requires the siRNA-generating ribonuclease Dicer-2 and the RNAi effector protein Argonaute2 (Ago2). We propose that endo-siRNAs generated by the fly RNAi pathway silence selfish genetic elements in the soma, much as Piwi-interacting RNAs do in the germ line.
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Citation: Science. 2008 May 23;320(5879):1077-81. Epub 2008 Apr 10. Link to article on publisher's site