A Conserved Upstream Motif Orchestrates Autonomous, Germline-Enriched Expression of Caenorhabditis elegans piRNAs
Year: 2013
Type: article
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 ∼50 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.
Source: PLoS Genetics
Authors: Allison C. Billi, Mallory A. Freeberg, Amanda M. Day, Sang Young Chun, Vishal Khivansara, John K. Kim
Institution: University of Michigan
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,043
Awards: Michigan Predoctoral Training in Genetics, IGERT: Open Data: Graduate Training for Data Sharing and Reuse in E-Science, The University of Michigan Bioinformatics Training Program, G4699534745, Cellular and Molecular Biology at Michigan, Regulation of Gene Expression by microRNAs in C. elegans, G8728404023
OpenAlex ID: W2085361724