title: Protection of germline gene expression by the C. elegans Argonaute CSR-1.
abstract: In Caenorhabditis elegans, the Piwi-interacting small RNA (piRNA)-mediated germline surveillance system encodes more than 30,000 unique 21-nucleotide piRNAs, which silence a variety of foreign nucleic acids. What mechanisms allow endogenous germline-expressed transcripts to evade silencing by the piRNA pathway? One likely candidate in a protective mechanism is the Argonaute CSR-1, which interacts with 22G-small RNAs that are antisense to nearly all germline-expressed genes. Here, we use an in vivo RNA tethering assay to demonstrate that the recruitment of CSR-1 to a transcript licenses expression of the transcript, protecting it from piRNA-mediated silencing. Licensing occurs mainly at the level of transcription, as we observe changes in pre-mRNA levels consistent with transcriptional activation when CSR-1 is tethered. Furthermore, the recruitment of CSR-1 to a previously silenced locus transcriptionally activates its expression. Together, these results demonstrate a rare positive role for an endogenous Argonaute pathway in heritably licensing and protecting germline transcripts.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Wedeles
authors.forename: Monica Z
authors.initials: MZ
authors.lastname: Wu
authors.forename: Julie M
authors.initials: JM
authors.lastname: Claycomb
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D020868:Gene Silencing; D005854:Germ Cells / Q000378:metabolism*; D018510:RNA, Helminth / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: C544459:CSR-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D018510:RNA, Helminth; D012333:RNA, Messenger; D034741:RNA, Small Interfering