title: Spatio-temporal requirements for transposable element piRNA-mediated silencing during Drosophila oogenesis.
abstract: During Drosophila oogenesis, transposable element (TE) repression involves the Piwi-interacting RNA (piRNA) pathway which ensures genome integrity for the next generation. We developed a transgenic model to study repression of the Idefix retrotransposon in the germline. Using a candidate gene KD-approach, we identified differences in the spatio-temporal requirements of the piRNA pathway components for piRNA-mediated silencing. Some of them (Aub, Vasa, Spn-E) are necessary in very early stages of oogenesis within the germarium and appear to be less important for efficient TE silencing thereafter. Others (Piwi, Ago3, Mael) are required at all stages of oogenesis. Moreover, during early oogenesis, in the dividing cysts within the germarium, Idefix anti-sense transgenes escape host control, and this is associated with very low piwi expression. Silencing of P-element-based transgenes is also strongly weakened in these cysts. This region, termed the 'Piwiless pocket' or Pilp, may ensure that new TE insertions occur and are transmitted to the next generation, thereby contributing to genome dynamics. In contrast, piRNA-mediated silencing is strong in germline stem cells in which TE mobilization is tightly repressed ensuring the continued production of viable germline cysts.
authors.affiliation: Inserm, UMR1103, F-63001 Clermont-Ferrand, France, CNRS, UMR6293, F-63001 Clermont-Ferrand, France, Clermont Université, Université d'Auvergne, Laboratoire GReD, BP 10448, F-63000 Clermont-Ferrand, France, Laboratoire Biologie du Développement, UMR7622, CNRS-Université Pierre et Marie Curie, 9 quai Saint Bernard, 75005 Paris, France and CHU, F-63001 Clermont-Ferrand, France.
authors.forename: Jérémy
authors.initials: J
authors.lastname: Dufourt
authors.forename: Cynthia
authors.initials: C
authors.lastname: Dennis
authors.forename: Antoine
authors.initials: A
authors.lastname: Boivin
authors.forename: Nathalie
authors.initials: N
authors.lastname: Gueguen
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Théron
authors.forename: Coline
authors.initials: C
authors.lastname: Goriaux
authors.forename: Pierre
authors.initials: P
authors.lastname: Pouchin
authors.forename: Stéphane
authors.initials: S
authors.lastname: Ronsseray
authors.forename: Emilie
authors.initials: E
authors.lastname: Brasset
authors.forename: Chantal
authors.initials: C
authors.lastname: Vaury
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000378:metabolism; D004330:Drosophila / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism; D005260:Female; D020868:Gene Silencing; D009154:Mutation; D009866:Oogenesis / Q000235:genetics*; D034741:RNA, Small Interfering / Q000378:metabolism*; D018626:Retroelements; D019076:Transgenes
chemical_list: D060565:Argonaute Proteins; D029721:Drosophila Proteins; D034741:RNA, Small Interfering; D018626:Retroelements; C116498:piwi protein, Drosophila