title: Embryonic-stage-dependent changes in the level of eIF4E-binding proteins during early development of sea urchin embryos.
abstract: The eukaryotic initiation factor 4E (eIF4E)-binding proteins (4E-BPs) inhibit translation initiation by binding eIF4E and preventing recruitment of the translation machinery to mRNA. We have previously shown that fertilization of sea urchin eggs triggers eIF4E-4E-BP complex dissociation and 4E-BP degradation. Here, we show that microinjection of eIF4E-binding motif peptide into unfertilized eggs delays the onset of the first mitosis triggered by fertilization, demonstrating that dissociation of the eIF4E-4E-BP complex is functionally important for the first mitotic division in sea urchin embryos. We also show by gel filtration analyses that eIF4E is present in unfertilized eggs as an 80 kDa molecular mass complex containing 4E-BP and a new 4E-BP of 40 kDa. Fertilization triggers the dissociation of eIF4E from these two 4E-BPs and triggers the rapid recruitment of eIF4E into a high-molecular-mass complex. Release of eIF4E from the two 4E-BPs is correlated with a decrease in the total level of both 4E-BPs following fertilization. Abundance of the two 4E-BPs has been monitored during embryonic development. The level of the two proteins remains very low during the rapid cleavage stage of early development and increases 8 hours after fertilization. These results demonstrate that these two 4E-BPs are down- and upregulated during the embryonic development of sea urchins. Consequently, these data suggest that eIF4E availability to other partners represents an important determinant of the early development of sea urchin embryos.
authors.affiliation: Station Biologique de Roscoff, Cycle Cellulaire et Développement, Unité Mer et Santé (UMR 7150), Université Pierre et Marie Curie (EI 37), Centre National de la Recherche Scientifique (CNRS), BP 74, 29682 Roscoff Cedex, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Salaün
authors.forename: Sandrine
authors.initials: S
authors.lastname: Boulben
authors.forename: Odile
authors.initials: O
authors.lastname: Mulner-Lorillon
authors.forename: Robert
authors.initials: R
authors.lastname: Bellé
authors.forename: Nahum
authors.initials: N
authors.lastname: Sonenberg
authors.forename: Julia
authors.initials: J
authors.lastname: Morales
authors.forename: Patrick
authors.initials: P
authors.lastname: Cormier
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism* / Q000494:pharmacology; D004625:Embryo, Nonmammalian / Q000378:metabolism; D047108:Embryonic Development / Q000502:physiology; D039561:Eukaryotic Initiation Factor-4E / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005306:Fertilization / Q000502:physiology; D008970:Molecular Weight; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D012617:Sea Urchins / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D039561:Eukaryotic Initiation Factor-4E; D012333:RNA, Messenger