Piwi and piRNAs act upstream of an endogenous siRNA pathway to suppress Tc3 transposon mobility in the Caenorhabditis elegans germline.
The Piwi proteins of the Argonaute superfamily are required for normal germline development in Drosophila, zebrafish, and mice and associate with 24-30 nucleotide RNAs termed piRNAs. We identify a class of 21 nucleotide RNAs, previously named 21U-RNAs, as the piRNAs of C. elegans. Piwi and piRNA expression is restricted to the male and female germline and independent of many proteins in other small-RNA pathways, including DCR-1. We show that Piwi is specifically required to silence Tc3, but not other Tc/mariner DNA transposons. Tc3 excision rates in the germline are increased at least 100-fold in piwi mutants as compared to wild-type. We find no evidence for a Ping-Pong model for piRNA amplification in C. elegans. Instead, we demonstrate that Piwi acts upstream of an endogenous siRNA pathway in Tc3 silencing. These data might suggest a link between piRNA and siRNA function.
Wellcome Trust Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK.
Partha P
PP
Das
Marloes P
MP
Bagijn
Leonard D
LD
Goldstein
Julie R
JR
Woolford
Nicolas J
NJ
Lehrbach
Alexandra
A
Sapetschnig
Heeran R
HR
Buhecha
Michael J
MJ
Gilchrist
Kevin L
KL
Howe
Rory
R
Stark
Nik
N
Matthews
Eugene
E
Berezikov
René F
RF
Ketting
Simon
S
Tavaré
Eric A
EA
Miska
D000818:Animals; D060565:Argonaute Proteins; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D004251:DNA Transposable Elements / Q000235:genetics*; D029721:Drosophila Proteins; D005260:Female; D020868:Gene Silencing; D017238:Genes, Helminth; D005854:Germ Cells / Q000254:growth & development / Q000378:metabolism*; D008297:Male; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D018510:RNA, Helminth / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism*; D034743:RNA-Induced Silencing Complex; D019895:Transposases / Q000378:metabolism
D060565:Argonaute Proteins; D029742:Caenorhabditis elegans Proteins; D004251:DNA Transposable Elements; D029721:Drosophila Proteins; C530363:PRG-1 protein, C elegans; C530626:PRG-2 protein, C elegans; D011506:Proteins; D018510:RNA, Helminth; D034741:RNA, Small Interfering; D034743:RNA-Induced Silencing Complex; C116498:piwi protein, Drosophila; D019895:Transposases