Phosphatidylinositol 3-kinase and Akt participate in the fsh-induced meiotic maturation of mouse oocytes

Yumi Hoshino, Masaki Yokoo, Noriyuki Yoshida, Hiroshi Sasada, Hiromichi Matsumoto, Eimei Sato

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59 Citations (Scopus)


Phosphatidylinositol 3-kinase (PI3K) is known to play critical roles in signal transduction processes related to a variety of cellular activities. In the present study, we investigated the role of PI3K during meiotic maturation in mouse oocytes using a specific inhibitor, LY294002. In follicle-stimulating hormone (FSH)-induced reversal of hypoxanthine-mediated meiotic arrest of cumulus oocyte complexes (COCs), LY294002 suppressed germinal vesicle breakdown (GVBD), first polar body (PB1) emission, and cumulus expansion. To examine the effect of LY294002, denuded oocytes (DOs) were cultured in medium containing follicular fluid meiosis-activating sterol (FF-MAS) since absence of gonadotropin receptors in oocytes has been reported and FSH did not stimulate meiotic maturation of DOs in the presence of hypoxanthine. In FF-MAS-induced maturation of DOs, LY294002 suppressed PB1 emission, but not GVBD. In spontaneous gonadotropin-independent oocyte maturation, LY294002 had no effect on COCs and DOs. Akt/protein kinase B, a serine-threonine kinase, is a key downstream effector of the PI3K pathway. Therefore, we also examined the distribution of Akt during FSH-induced meiotic maturation. The distribution of Ser473 phosphorylated Akt was similar to the localization of microtubules, while Thr308 phosphorylated Akt was present in the pericentriolar materials (PCM) in metaphase I (MI) and II (MII) oocytes. LY294002 decreased the amount of Thr308 phosphorylated Akt to very low to undetectable levels in MI and MII oocytes. Ser473 phosphorylated Akt showed aberrant distribution and very low to undetectable levels of expression in LY294002-treated MI and MII oocytes, respectively. These results suggest that PI3K and Akt participate in mouse meiotic maturation.

Original languageEnglish
Pages (from-to)77-86
Number of pages10
JournalMolecular reproduction and development
Issue number1
Publication statusPublished - 2004 Sep
Externally publishedYes


  • LY294002
  • PI3K
  • PKB

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology
  • Cell Biology


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