title: Artificial "ping-pong" cascade of PIWI-interacting RNA in silkworm cells.
abstract: PIWI-interacting RNAs (piRNAs) play essential roles in the defense system against selfish elements in animal germline cells by cooperating with PIWI proteins. A subset of piRNAs is predicted to be generated via the "ping-pong" cascade, which is mainly controlled by two different PIWI proteins. Here we established a cell-based artificial piRNA production system using a silkworm ovarian cultured cell line that is believed to possess a complete piRNA pathway. In addition, we took advantage of a unique silkworm sex-determining one-to-one ping-pong piRNA pair, which enabled us to precisely monitor the behavior of individual artificial piRNAs. With this novel strategy, we successfully generated artificial piRNAs against endogenous protein-coding genes via the expected back-and-forth traveling mechanism. Furthermore, we detected "primary" piRNAs from the upstream region of the artificial "ping-pong" site in the endogenous gene. This artificial piRNA production system experimentally confirms the existence of the "ping-pong" cascade of piRNAs. Also, this system will enable us to identify the factors involved in both, or each, of the "ping" and "pong" cascades and the sequence features that are required for efficient piRNA production.
authors: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors: Keisuke
authors: K
authors: Shoji
authors: Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-0882, Japan.
authors: Yutaka
authors: Y
authors: Suzuki
authors: Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan.
authors: Sumio
authors: S
authors: Sugano
authors: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors: Toru
authors: T
authors: Shimada
authors: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors: Susumu
authors: S
authors: Katsuma
mesh_terms: D000818:Animals; D012831:Bombyx / Q000235:genetics*; D002460:Cell Line; D002478:Cells, Cultured; D005260:Female; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D010053:Ovary / Q000166:cytology* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics*
chemical_list: D019476:Insect Proteins; D034741:RNA, Small Interfering
keywords: PIWI proteins; artificial piRNAs; piRNAs; ping-pong cycle; silkworm cells