title: The Drosophila HP1 homolog Rhino is required for transposon silencing and piRNA production by dual-strand clusters.
abstract: Piwi-interacting RNAs (piRNAs) silence transposons and maintain genome integrity during germline development. In Drosophila, transposon-rich heterochromatic clusters encode piRNAs either on both genomic strands (dual-strand clusters) or predominantly one genomic strand (uni-strand clusters). Primary piRNAs derived from these clusters are proposed to drive a ping-pong amplification cycle catalyzed by proteins that localize to the perinuclear nuage. We show that the HP1 homolog Rhino is required for nuage organization, transposon silencing, and ping-pong amplification of piRNAs. rhi mutations virtually eliminate piRNAs from the dual-strand clusters and block production of putative precursor RNAs from both strands of the major 42AB dual-strand cluster, but not of transcripts or piRNAs from the uni-strand clusters. Furthermore, Rhino protein associates with the 42AB dual-strand cluster,but does not bind to uni-strand cluster 2 or flamenco. Rhino thus appears to promote transcription of dual-strand clusters, leading to production of piRNAs that drive the ping-pong amplification cycle.
authors.affiliation: University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Carla
authors.initials: C
authors.lastname: Klattenhoff
authors.forename: Hualin
authors.initials: H
authors.lastname: Xi
authors.forename: Chengjian
authors.initials: C
authors.lastname: Li
authors.forename: Soohyun
authors.initials: S
authors.lastname: Lee
authors.forename: Jia
authors.initials: J
authors.lastname: Xu
authors.forename: Jaspreet S
authors.initials: JS
authors.lastname: Khurana
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: Nadine
authors.initials: N
authors.lastname: Schultz
authors.forename: Birgit S
authors.initials: BS
authors.lastname: Koppetsch
authors.forename: Anetta
authors.initials: A
authors.lastname: Nowosielska
authors.forename: Herve
authors.initials: H
authors.lastname: Seitz
authors.forename: Phillip D
authors.initials: PD
authors.lastname: Zamore
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Weng
authors.forename: William E
authors.initials: WE
authors.lastname: Theurkauf
mesh_terms: D000818:Animals; D047369:Chromatin Immunoprecipitation; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D004251:DNA Transposable Elements; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D006570:Heterochromatin / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004251:DNA Transposable Elements; D029721:Drosophila Proteins; D006570:Heterochromatin; D034741:RNA, Small Interfering; C449641:rhi protein, Drosophila