title: Endogenous siRNAs derived from transposons and mRNAs in Drosophila somatic cells.
abstract: 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.
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Megha
authors.initials: M
authors.lastname: Ghildiyal
authors.forename: Hervé
authors.initials: H
authors.lastname: Seitz
authors.forename: Michael D
authors.initials: MD
authors.lastname: Horwich
authors.forename: Chengjian
authors.initials: C
authors.lastname: Li
authors.forename: Tingting
authors.initials: T
authors.lastname: Du
authors.forename: Soohyun
authors.initials: S
authors.lastname: Lee
authors.forename: Jia
authors.initials: J
authors.lastname: Xu
authors.forename: Ellen L W
authors.initials: EL
authors.lastname: Kittler
authors.forename: Maria L
authors.initials: ML
authors.lastname: Zapp
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Weng
authors.forename: Phillip D
authors.initials: PD
authors.lastname: Zamore
mesh_terms: D000818:Animals; D060565:Argonaute Proteins; D001483:Base Sequence; D002460:Cell Line; D004251:DNA Transposable Elements; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D020365:RNA Helicases / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism*; D034743:RNA-Induced Silencing Complex / Q000235:genetics / Q000378:metabolism; D018626:Retroelements; D043244:Ribonuclease III
chemical_list: C433807:AGO2 protein, Drosophila; D060565:Argonaute Proteins; D004251:DNA Transposable Elements; D029721:Drosophila Proteins; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D034743:RNA-Induced Silencing Complex; D018626:Retroelements; C478069:DCR-2 protein, Drosophila; D043244:Ribonuclease III; D020365:RNA Helicases