title: Gatekeepers for Piwi-piRNA complexes to enter the nucleus.
abstract: RNA silencing pathways are now recognized to participate in essential cellular functions ranging from the regulation of mRNA turnover to the suppression of the activity of potentially deleterious transposable elements (TEs). Piwi-interacting RNAs (piRNAs) are germline-specific, small silencing RNAs that suppress TE activity and maintain genome integrity during germline development. In Drosophila ovarian somatic cells, piRNAs are processed from long single-stranded RNAs by a Dicer-independent pathway and are loaded onto Piwi in the cytoplasm. The Piwi-piRNA complexes are then transported into the nucleus to exert TE silencing. This mechanism involves gatekeepers for a functional Piwi-piRNA complex to be imported, which parallels with the Tetrahymena Twi1p-scan RNA pathway used to carry out the programmed DNA elimination.
authors.affiliation: Department of Molecular Biology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Ishizu
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nagao
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Siomi
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034443:RNA Transport; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism*; D034743:RNA-Induced Silencing Complex / Q000235:genetics / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D034741:RNA, Small Interfering; D034743:RNA-Induced Silencing Complex