title: Somatic Primary piRNA Biogenesis Driven by cis-Acting RNA Elements and trans-Acting Yb.
abstract: Primary piRNAs in Drosophila ovarian somatic cells arise from piRNA cluster transcripts and the 3' UTRs of a subset of mRNAs, including Traffic jam (Tj) mRNA. However, it is unclear how these RNAs are determined as primary piRNA sources. Here, we identify a cis-acting 100-nt fragment in the Tj 3' UTR that is sufficient for producing artificial piRNAs from unintegrated DNA. These artificial piRNAs were effective in endogenous gene transcriptional silencing. Yb, a core component of primary piRNA biogenesis center Yb bodies, directly bound the Tj-cis element. Disruption of this interaction markedly reduced piRNA production. Thus, Yb is the trans-acting partner of the Tj-cis element. Yb-CLIP revealed that Yb binding correlated with somatic piRNA production but Tj-cis element downstream sequences produced few artificial piRNAs. We thus propose that Yb determines primary piRNA sources through two modes of action: primary binding to cis elements to specify substrates and secondary binding to downstream regions to increase diversity in piRNA populations.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Ishizu
authors.affiliation: Department of Molecular Biology, Keio University School of Medicine, Tokyo 160-8582, Japan.
authors.forename: Yuka W
authors.initials: YW
authors.lastname: Iwasaki
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Hirakata
authors.affiliation: Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Ozaki
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0032, Japan; Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Iwasaki
authors.affiliation: Department of Molecular Biology, Keio University School of Medicine, Tokyo 160-8582, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Siomi
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0032, Japan. Electronic address: siomim@bs.s.u-tokyo.ac.jp.
authors.forename: Mikiko C
authors.initials: MC
authors.lastname: Siomi
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000235:genetics; D018929:Cell Culture Techniques; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster; D010957:Plasmids; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D060565:Argonaute Proteins; D029721:Drosophila Proteins; D034741:RNA, Small Interfering; C116498:piwi protein, Drosophila