A conserved upstream motif orchestrates autonomous, germline-enriched expression of Caenorhabditis elegans piRNAs.
PLoS Genet
; 9(3): e1003392, 2013.
Article
em En
| MEDLINE
| ID: mdl-23516384
ABSTRACT
Piwi-interacting RNAs (piRNAs) fulfill a critical, conserved role in defending the genome against foreign genetic elements. In many organisms, piRNAs appear to be derived from processing of a long, polycistronic RNA precursor. Here, we establish that each Caenorhabditis elegans piRNA represents a tiny, autonomous transcriptional unit. Remarkably, the minimal C. elegans piRNA cassette requires only a 21 nucleotide (nt) piRNA sequence and an â¼50 nt upstream motif with limited genomic context for expression. Combining computational analyses with a novel, in vivo transgenic system, we demonstrate that this upstream motif is necessary for independent expression of a germline-enriched, Piwi-dependent piRNA. We further show that a single nucleotide position within this motif directs differential germline enrichment. Accordingly, over 70% of C. elegans piRNAs are selectively expressed in male or female germline, and comparison of the genes they target suggests that these two populations have evolved independently. Together, our results indicate that C. elegans piRNA upstream motifs act as independent promoters to specify which sequences are expressed as piRNAs, how abundantly they are expressed, and in what germline. As the genome encodes well over 15,000 unique piRNA sequences, our study reveals that the number of transcriptional units encoding piRNAs rivals the number of mRNA coding genes in the C. elegans genome.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
RNA Interferente Pequeno
/
Sequências Reguladoras de Ácido Ribonucleico
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Motivos de Nucleotídeos
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Células Germinativas
Limite:
Animals
Idioma:
En
Revista:
PLoS Genet
Assunto da revista:
GENETICA
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Estados Unidos