An eIF4E-binding protein regulates katanin protein levels in C. elegans embryos

J Cell Biol. 2009 Oct 5;187(1):33-42. doi: 10.1083/jcb.200903003. Epub 2009 Sep 28.


In Caenorhabditis elegans, the MEI-1-katanin microtubule-severing complex is required for meiosis, but must be down-regulated during the transition to embryogenesis to prevent defects in mitosis. A cullin-dependent degradation pathway for MEI-1 protein has been well documented. In this paper, we report that translational repression may also play a role in MEI-1 down-regulation. Reduction of spn-2 function results in spindle orientation defects due to ectopic MEI-1 expression during embryonic mitosis. MEL-26, which is both required for MEI-1 degradation and is itself a target of the cullin degradation pathway, is present at normal levels in spn-2 mutant embryos, suggesting that the degradation pathway is functional. Cloning of spn-2 reveals that it encodes an eIF4E-binding protein that localizes to the cytoplasm and to ribonucleoprotein particles called P granules. SPN-2 binds to the RNA-binding protein OMA-1, which in turn binds to the mei-1 3' untranslated region. Thus, our results suggest that SPN-2 functions as an eIF4E-binding protein to negatively regulate translation of mei-1.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism*
  • Adenosine Triphosphatases / physiology*
  • Animals
  • Caenorhabditis elegans / embryology
  • Caenorhabditis elegans / physiology*
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Caenorhabditis elegans Proteins / physiology*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cytoplasm / metabolism
  • Embryo, Nonmammalian / physiology
  • Eukaryotic Initiation Factor-4E / genetics
  • Eukaryotic Initiation Factor-4E / metabolism*
  • Eukaryotic Initiation Factor-4E / physiology*
  • Katanin
  • Protein Binding / genetics
  • Ribonucleoproteins / metabolism


  • Caenorhabditis elegans Proteins
  • Carrier Proteins
  • Eukaryotic Initiation Factor-4E
  • Ribonucleoproteins
  • Adenosine Triphosphatases
  • Katanin