title: The P granule component PGL-1 promotes the localization and silencing activity of the PUF protein FBF-2 in germline stem cells.
abstract: In the C. elegans germline, maintenance of undifferentiated stem cells depends on the PUF family RNA-binding proteins FBF-1 and FBF-2. FBF-1 and FBF-2 are 89% identical and are required redundantly to silence the expression of mRNAs that promote meiosis. Here we show that, despite their extensive sequence similarity, FBF-1 and FBF-2 have different effects on target mRNAs. FBF-1 promotes the degradation and/or transport of meiotic mRNAs out of the stem cell region, whereas FBF-2 prevents translation. FBF-2 activity depends on the P granule component PGL-1. PGL-1 is required to localize FBF-2 to perinuclear P granules and for efficient binding of FBF-2 to its mRNA targets. We conclude that multiple regulatory mechanisms converge on meiotic RNAs to ensure silencing in germline stem cells. Our findings also support the view that P granules facilitate mRNA silencing by providing an environment in which translational repressors can encounter their mRNA targets immediately upon exit from the nucleus.
authors.affiliation: Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205,  USA.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Voronina
authors.forename: Alexandre
authors.initials: A
authors.lastname: Paix
authors.forename: Geraldine
authors.initials: G
authors.lastname: Seydoux
mesh_terms: D000818:Animals; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D053595:Embryonic Stem Cells / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005854:Germ Cells / Q000378:metabolism*; D008540:Meiosis / Q000235:genetics; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; C114543:PGL-1 protein, C elegans; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C109286:fem-3-binding protein, C elegans