RRC ID 30635
Author Lee HC, Gu W, Shirayama M, Youngman E, Conte D Jr, Mello CC.
Title C. elegans piRNAs mediate the genome-wide surveillance of germline transcripts.
Journal Cell
Abstract Piwi Argonautes and Piwi-interacting RNAs (piRNAs) mediate genome defense by targeting transposons. However, many piRNA species lack obvious sequence complementarity to transposons or other loci; only one C. elegans transposon is a known piRNA target. Here, we show that, in mutants lacking the Piwi Argonaute PRG-1 (and consequently its associated piRNAs/21U-RNAs), many silent loci in the germline exhibit increased levels of mRNA expression with a concomitant depletion of RNA-dependent RNA polymerase (RdRP)-derived secondary small RNAs termed 22G-RNAs. Sequences depleted of 22G-RNAs are proximal to potential target sites that base pair imperfectly but extensively to 21U-RNAs. We show that PRG-1 is required to initiate, but not to maintain, silencing of transgenes engineered to contain complementarity to endogenous 21U-RNAs. Our findings support a model in which C. elegans piRNAs utilize their enormous repertoire of targeting capacity to scan the germline transcriptome for foreign sequences, while endogenous germline-expressed genes are actively protected from piRNA-induced silencing.
Volume 150(1)
Pages 78-87
Published 2012-7-6
DOI 10.1016/j.cell.2012.06.016
PII S0092-8674(12)00765-9
PMID 22738724
PMC PMC3410639
MeSH Animals Argonaute Proteins / metabolism Caenorhabditis elegans / genetics* Caenorhabditis elegans / metabolism* Gene Silencing Genome, Helminth* Germ Cells RNA, Helminth / metabolism* RNA, Small Interfering / metabolism*
IF 31.398
Times Cited 139
C.elegans tm872