FBF and its dual control of gld-1 expression in the Caenorhabditis elegans germline

Genetics. 2009 Apr;181(4):1249-60. doi: 10.1534/genetics.108.099440. Epub 2009 Feb 16.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Caenorhabditis elegans / genetics*
  • Caenorhabditis elegans / metabolism
  • Caenorhabditis elegans Proteins / genetics*
  • Caenorhabditis elegans Proteins / metabolism
  • Caenorhabditis elegans Proteins / physiology*
  • Exoribonucleases / metabolism
  • Exoribonucleases / physiology
  • Female
  • Gene Expression Regulation
  • Germ Cells / metabolism*
  • Male
  • Models, Biological
  • Molecular Sequence Data
  • Oogenesis / genetics
  • Polynucleotide Adenylyltransferase / metabolism
  • Protein Binding
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / metabolism
  • RNA-Binding Proteins / physiology*
  • Sequence Homology, Amino Acid
  • Spermatogenesis / genetics


  • Caenorhabditis elegans Proteins
  • GLD-1 protein, C elegans
  • RNA, Messenger
  • RNA-Binding Proteins
  • fem-3-binding protein, C elegans
  • GLD-2 protein, C elegans
  • Polynucleotide Adenylyltransferase
  • Exoribonucleases
  • poly(A)-specific ribonuclease