The nuclear PIWI-interacting protein Gtsf1 controls the selective degradation of small RNAs in Paramecium
Résumé
Ciliates undergo de v elopmentally programmed genome elimination, in which small RNAs direct the remo v al of transposable elements (TEs) during the de v elopment of the somatic nucleus. Tw enty -fiv e nucleotide scanRNAs (scnRNAs) are produced from the entire germline genome and transported to the maternal somatic nucleus, where selection of scnRNAs corresponding to germline-specific sequences is thought to take place. Selected scnRNAs then guide the elimination of TEs in the de v eloping somatic nucleus. Ho w germline-specific scnRNAs are selected remains to be determined. Here, we provide important mechanistic insights into the scnRNA selection pathw a y b y identifying a Paramecium homolog of Gtsf1 as essential for the selective degradation of scnRNAs corresponding to retained somatic sequences. Consistently, we also show that Gtsf1 is localized in the maternal somatic nucleus where it associates with the scnRNA-binding protein Ptiwi09. Furthermore, we demonstrate that the scnRNA selection process is critical for genome elimination. We propose that Gtsf1 is required for the coordinated degradation of Ptiwi09-scnRNA comple x es that pair with target RNA via the ubiquitin pathw a y, similarly to the mechanism suggested for microRNA target-directed degradation in metazoans.
Domaines
Sciences du Vivant [q-bio]| Origine | Publication financée par une institution |
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