title: FBF and its dual control of gld-1 expression in the Caenorhabditis elegans germline.
abstract: FBF, a PUF RNA-binding protein, is a key regulator of the mitosis/meiosis decision in the Caenorhabditis elegans germline. Genetically, FBF has a dual role in this decision: it maintains germ cells in mitosis, but it also facilitates entry into meiosis. In this article, we explore the molecular basis of that dual role. Previous work showed that FBF downregulates gld-1 expression to promote mitosis and that the GLD-2 poly(A) polymerase upregulates gld-1 expression to reinforce the decision to enter meiosis. Here we ask whether FBF can act as both a negative regulator and a positive regulator of gld-1 expression and also investigate its molecular mechanisms of control. We first show that FBF co-immunoprecipitates with gld-1 mRNA, a result that complements previous evidence that FBF directly controls gld-1 mRNA. Then we show that FBF represses gld-1 expression, that FBF physically interacts with the CCF-1/Pop2p deadenylase and can stimulate deadenylation in vitro, and that CCF-1 is partially responsible for maintaining low GLD-1 in the mitotic region. Finally, we show that FBF can elevate gld-1 expression, that FBF physically interacts with the GLD-2 poly(A) polymerase, and that FBF can enhance GLD-2 poly(A) polymerase activity in vitro. We propose that FBF can affect polyadenylation either negatively by its CCF-1 interaction or positively by its GLD-2 interaction.
authors.affiliation: Department of Biochemistry, Howard Hughes Medical Institute, Program in Cellular and Molecular Biology, University of Wisconsin, Madison, Wisconsin 53706-1544, USA.
authors.forename: Nayoung
authors.initials: N
authors.lastname: Suh
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Crittenden
authors.forename: Aaron
authors.initials: A
authors.lastname: Goldstrohm
authors.forename: Brad
authors.initials: B
authors.lastname: Hook
authors.forename: Beth
authors.initials: B
authors.lastname: Thompson
authors.forename: Marvin
authors.initials: M
authors.lastname: Wickens
authors.forename: Judith
authors.initials: J
authors.lastname: Kimble
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D005095:Exoribonucleases / Q000378:metabolism / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation; D005854:Germ Cells / Q000378:metabolism*; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D009866:Oogenesis / Q000235:genetics; D011062:Polynucleotide Adenylyltransferase / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013091:Spermatogenesis / Q000235:genetics
chemical_list: D029742:Caenorhabditis elegans Proteins; D005095:Exoribonucleases; D011062:Polynucleotide Adenylyltransferase; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C094448:GLD-1 protein, C elegans; C109286:fem-3-binding protein, C elegans; C491056:GLD-2 protein, C elegans