CDC25A is able to induce resumption of meiosis but compromises metaphase I-metaphase II transition in mouse oocytes

0089293 - ÚŽFG 2008 RIV CZ eng K - Konferenční příspěvek (tuzemská konf.)
Šolc, Petr - Šašková, Adéla - Baran, V. - Kubelka, Michal - Motlík, Jan
CDC25A is able to induce resumption of meiosis but compromises metaphase I-metaphase II transition in mouse oocytes.
[CDC25A je schopna indukovat znovuzahájení meiosy, ale inhibuje metafase I – metafase II přechod.]
Programme and book of abstracts of Conference on Reproductive and Developmental Biology. Mělník: ÚŽFG, 2007, s. 9-9.
[Conference on Reproductive and Developmental Biology. Praha (CZ), 21.06.2007-22.06.2007]
Výzkumný záměr: CEZ:AV0Z50450515
Klíčová slova: meiosis
Kód oboru RIV: EB - Genetika a molekulární biologie

We have shown that CDC25A protein is expressed in GV-stage oocytes but decreases, in CDK1-dependent manner, during meiotic maturation. As compared with GV-stage only a very low level of CDC25A protein is present at metaphase I (MI) and metaphase II (MII) stages. CDC25A mRNA is stable during entire meiotic maturation. Exogenous CDC25A was sufficient to overcome cAMP-mediated GV-stage block. Using microinjection of GFP-CDC25A and GFP-CDC25B mRNAs constructs we have revealed that CDC25A is exclusively nuclear protein until nuclear envelope break down (NEBD). In contrast CDC25B localizes to cytoplasm at GV-stage oocytes and translocates to nucleus shortly before NEBD. Overexpression of GFP-CDC25A, to interfere with CDC25A degradation during meiotic maturation, resulted in MI block characterized with problems in chromosome congression and spindle formation. This MI block was accompanied with the transient reduction of both CDK1 and MAPK activities. RNAi mediated CDC25A knock-down resulted in a reduced ability to resume meiosis and to reach MII. These data demonstrate that behavior of CDC25A during female meiosis differs significantly from mitosis and CDC25A is involved in both, resumption of meiosis and also in metaphase I spindle formation as a prerequisite for correct MI-MII transition. It is evident that CDC25B is not only important CDC25 phosphatase for meiotic maturation but also CDC25A has its meiotic specific role.

Práce se zabývá expresí a funkcí CDC25A v myších oocytech. Bylo zjištěno, že CDC25A protein se exprimuje v GV-oocytech, avšak jeho hladina při meiotickém zrání klesá, přičemž na konci meiosy je v metafase II oocytech pouze velmi nízká hladina CDC25A proteinu. Tento CDC25A proteinový pokles je závislý na CDK1 aktivitě, nesouvisí však se změnami hladiny Cdc25A mRNA, která zůstává konstantní. Pomocí funkčních studií (RNA interference, mikroinjekce mRNA) jsme jasně prokázali, že CDC25A je nezbytná pro znovuzahájení meiosy a tvorbu metafase I spindelu. Pokles CDC25A aktivity po znovuzahájení meiosy je klíčový pro korektní metafase I – metafase II přechod.
Trvalý link: http://hdl.handle.net/11104/0150549