The Drosophila HP1 homolog Rhino is required for transposon silencing and piRNA production by dual-strand clusters.
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.
Klattenhoff
Carla
C
University of Massachusetts Medical School, Worcester, MA 01605, USA.
Xi
Hualin
H
Li
Chengjian
C
Lee
Soohyun
S
Xu
Jia
J
Khurana
Jaspreet S
JS
Zhang
Fan
F
Schultz
Nadine
N
Koppetsch
Birgit S
BS
Nowosielska
Anetta
A
Seitz
Herve
H
Zamore
Phillip D
PD
Weng
Zhiping
Z
Theurkauf
William E
WE
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
D002868:Chromosomal Proteins, Non-Histone; D004251:DNA Transposable Elements; D029721:Drosophila Proteins; D006570:Heterochromatin; D034741:RNA, Small Interfering; C449641:rhi protein, Drosophila