Suppression of Translation During in vitro Maturation of Pig Oocytes Despite Enhanced Formation of Cap-binding Protein Complex eIF4F and 4E-BP1 hyperphosphorylation.

0040774 - ÚŽFG 2007 RIV US eng J - Journal Article
Ellederová, Zdeňka - Kovářová, Hana - Melo Sterza, F. - Livingstone, M. - Tomek, W. - Kubelka, Michal
Suppression of Translation During in vitro Maturation of Pig Oocytes Despite Enhanced Formation of Cap-binding Protein Complex eIF4F and 4E-BP1 hyperphosphorylation.
[Suprese translace v průběhu in vitro zrání prasečích oocytů bez ohledu na zvýšenou tvorbu čepičku- vázajícího komplexu eIF4F a 4E-BP1 hyperfosforylaci.]
Molecular Reproduction and Development. Roč. 73, 1 (2006), s. 68-76. ISSN 1040-452X. E-ISSN 1098-2795
R&D Projects: GA ČR GA301/00/0781; GA ČR GA524/04/0104
Grant - others:Deutche Forschungsgemeinschaft(DE) 463TSE113/28
Institutional research plan: CEZ:AV0Z50450515
Keywords : meiosis * translation initiation * eIF-4E
Subject RIV: ED - Physiology
Impact factor: 2.379, year: 2006

In this study, we document that the overall rate of protein synthesis decreases during in vitro maturation (IVM) of pig oocytes despite enhanced formation of the 50 cap structure eIF4F. Within somatic/interphase cells, formation of the eIF4F protein complex correlates very well with overall rates of protein translation, and the formation of this complex is controlled primarily by the availability of the 50 cap binding protein eIF4E. We show that the eIF4E inhibitory protein, 4E-BP1, becomes phosphorylated during IVM, which results in gradual release of eIF4E from 4E-BP1, as documented by immunoprecipitation analyses. Isoelectric focusing and Western blotting experiments show conclusively that eIF4E becomes gradually phosphorylated with a maximum at metaphase II (M II). The activity of eIF4E and its ability to bind mRNA also increases during oocyte maturation as documented in experiments with m7-methyl GTPSepharose, which mimics the cap structure of mRNA. Complementary analysis of flow-through fraction for 4E-BP1, and eIF4G proteins additionally provides evidence for enhanced formation of cap-binding protein complex eIF4F. Altogether, our results bring new insights to the regulation of translation initiation during meiotic division, and more specifically clarify that 4EBP1 hyper-phosphorylation is not the cause of the observed suppression of overall translation rates.

V této studii dokumentujeme, že celková rychlost syntézy proteinů se snižuje v průběhu in vitro meiotického zrání prasečích oocytů bez ohledu na zvýšenou tvorbu čepičkové struktury eIF4F. Ukázali jsme, že 4E-BP1 protein se fosforyluje v průběhu IVM což vede k uvolnění vazby eIF4E. Současně dochází k fosforylaci eIF4E. Komplementární analýza eIF4G proteinu poskytla další důkaz pro zvýšenou tvorbu proteinového komplexu eIF4F. Tyto výsledky objasňují regulaci iniciace translace během meiotického dělení.
Permanent Link: http://hdl.handle.net/11104/0134420