title: Tudor-domain containing proteins act to make the piRNA pathways more robust in Drosophila.
abstract: PIWI-interacting RNAs (piRNAs), a subset of small non-coding RNAs enriched in animal gonads, repress transposons by assembling with PIWI proteins to form potent gene-silencing RNP complexes, piRISCs. Accumulating evidence suggests that piRNAs are produced through three interdependent pathways; the de novo primary pathway, the ping-pong pathway, and the phased primary pathway. The de novo primary pathway in Drosophila ovaries produces primary piRNAs for two PIWI members, Piwi and Aub. Aub then initiates the ping-pong pathway to produce secondary piRNAs for AGO3. AGO3-slicer dependent cleavage subsequently produces secondary piRNAs for Aub. Trailer products of AGO3-slicer activity are consumed by the phased primary pathway to increase the Piwi-bound piRNA population. All these pathways are regulated by a number of piRNA factors in a highly coordinated fashion. Recent studies show that two Tudor-domain containing piRNA factors, Krimper (Krimp) and Qin/Kumo, play crucial roles in making Aub-AGO3 heterotypic ping-pong robust. This maintains the levels of piRNAs loaded onto Piwi and Aub to efficiently repress transposons at transcriptional and post-transcriptional levels, respectively.
authors.affiliation: a Department of Biophysics and Biochemistry ; Graduate School of Science; The University of Tokyo ; Tokyo , Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sato
authors.affiliation: b Department of Molecular Biology ; Keio University School of Medicine ; Tokyo , Japan.
authors.forename: Yuka W
authors.initials: YW
authors.lastname: Iwasaki
authors.affiliation: b Department of Molecular Biology ; Keio University School of Medicine ; Tokyo , Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Siomi
authors.affiliation: a Department of Biophysics and Biochemistry ; Graduate School of Science; The University of Tokyo ; Tokyo , Japan.
authors.forename: Mikiko C
authors.initials: MC
authors.lastname: Siomi
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D034741:RNA, Small Interfering / Q000502:physiology*; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
chemical_list: D060565:Argonaute Proteins; D029721:Drosophila Proteins; C000602673:Krimp protein, Drosophila; D034741:RNA, Small Interfering; D017411:Ribonucleoproteins, Small Nuclear; C116498:piwi protein, Drosophila; C569287:Qin protein, Drosophila; D044767:Ubiquitin-Protein Ligases
keywords: PIWI; Qin; Transposon; Tudor domain; krimp; piRNA; ping-pong