Collapse of germline piRNAs in the absence of Argonaute3 reveals somatic piRNAs in flies.
Piwi-interacting RNAs (piRNAs) silence transposons in animal germ cells. piRNAs are thought to derive from long transcripts spanning transposon-rich genomic loci and to direct an autoamplification loop in which an antisense piRNA, bound to Aubergine or Piwi protein, triggers production of a sense piRNA bound to the PIWI protein Argonaute3 (Ago3). In turn, the new piRNA is envisioned to produce a second antisense piRNA. Here, we describe strong loss-of-function mutations in ago3, allowing a direct genetic test of this model. We find that Ago3 acts to amplify piRNA pools and to enforce on them an antisense bias, increasing the number of piRNAs that can act to silence transposons. We also detect a second, Ago3-independent piRNA pathway centered on Piwi. Transposons targeted by this second pathway often reside in the flamenco locus, which is expressed in somatic ovarian follicle cells, suggesting a role for piRNAs beyond the germline.
Li
Chengjian
C
Department of Biochemistry and Molecular Pharmacology and Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, 01605, USA.
Vagin
Vasily V
VV
Lee
Soohyun
S
Xu
Jia
J
Ma
Shengmei
S
Xi
Hualin
H
Seitz
Hervé
H
Horwich
Michael D
MD
Syrzycka
Monika
M
Honda
Barry M
BM
Kittler
Ellen L W
EL
Zapp
Maria L
ML
Klattenhoff
Carla
C
Schulz
Nadine
N
Theurkauf
William E
WE
Weng
Zhiping
Z
Zamore
Phillip D
PD
D000818:Animals; D060565:Argonaute Proteins; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D020868:Gene Silencing; D009154:Mutation; D006080:Ovarian Follicle / Q000378:metabolism*; D010448:Peptide Initiation Factors / Q000235:genetics* / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D018626:Retroelements
C518392:AGO3 protein, Drosophila; D060565:Argonaute Proteins; D029721:Drosophila Proteins; D010448:Peptide Initiation Factors; D034741:RNA, Small Interfering; D018626:Retroelements