A role for transcription from a piRNA cluster in de novo piRNA production
- Shinpei Kawaoka1,6,
- Hiroshi Mitsutake2,6,
- Takashi Kiuchi1,
- Maki Kobayashi3,4,
- Mayu Yoshikawa3,4,
- Yutaka Suzuki4,
- Sumio Sugano4,
- Toru Shimada1,
- Jun Kobayashi2,5,7,
- Yukihide Tomari3,4,7 and
- Susumu Katsuma1,7
- 1Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
- 2The United Graduate School of Agricultural Sciences, Tottori University, Koyama-cho, Minami 4-101, Tottori 680-8553, Japan
- 3Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
- 4Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
- 5Faculty of Agriculture, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8515, Japan
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↵6 These authors contributed equally to this work.
Abstract
PIWI-interacting RNAs (piRNAs) are at the heart of the nucleic acid–based adaptive immune system against transposons in animal gonads. To date, how the piRNA pathway senses an element as a substrate and how de novo piRNA production is initiated remain elusive. Here, by utilizing a GFP transgene, we screened and obtained clonal silkworm BmN4 cell lines producing massively amplified GFP-derived piRNAs capable of silencing GFP in trans. In multiple independent cell lines where GFP expression was silenced by the piRNA pathway, we detected a common transcript from an endogenous piRNA cluster, in which a part of the cluster is uniquely fused with an antisense GFP sequence. Bioinformatic analyses suggest that the fusion transcript is a source of GFP primary piRNAs. Our data implicate a role for transcription from a piRNA cluster in initiating de novo piRNA production against a new insertion.
Keywords
Footnotes
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↵7 Corresponding authors.
E-mail koba-jun{at}yamaguchi-u.ac.jp.
E-mail tomari{at}iam.u-tokyo.ac.jp.
E-mail katsuma{at}ss.ab.a.u-tokyo.ac.jp.
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Article published online ahead of print. Article and publication date are at http://www.rnajournal.org/cgi/doi/10.1261/rna.029777.111.
- Received August 8, 2011.
- Accepted November 8, 2011.
- Copyright © 2012 RNA Society