The role of the PI3K-Akt signaling pathway in the developmental competence of bovine oocytes

PLoS One. 2017 Sep 18;12(9):e0185045. doi: 10.1371/journal.pone.0185045. eCollection 2017.

Abstract

The ovarian follicle encloses oocytes in a microenvironment throughout their growth and acquisition of competence. Evidence suggests a dynamic interplay among follicular cells and oocytes, since they are constantly exchanging "messages". We dissected bovine ovarian follicles and recovered follicular cells (FCs-granulosa and cumulus cells) and cumulus-oocyte complexes (COCs) to investigate whether the PI3K-Akt signaling pathway impacted oocyte quality. Following follicle rupture, COCs were individually selected for in vitro cultures to track the follicular cells based on oocyte competence to reach the blastocyst stage after parthenogenetic activation. Levels of PI3K-Akt signaling pathway components in FCs correlated with oocyte competence. This pathway is upregulated in FCs from follicles with high-quality oocytes that are able to reach the blastocyst stage, as indicated by decreased levels of PTEN and increased levels of the PTEN regulators bta-miR-494 and bta-miR-20a. Using PI3K-Akt responsive genes, we showed decreased FOXO3a levels and BAX levels in lower quality groups, indicating changes in cell cycle progression, oxidative response and apoptosis. Based on these results, the measurement of levels of PI3K-Akt pathway components in FCs from ovarian follicles carrying oocytes with distinct developmental competences is a useful tool to identify putative molecular pathways involved in the acquisition of oocyte competence.

MeSH terms

  • Animals
  • Blastocyst / enzymology
  • Cattle
  • Female
  • Forkhead Box Protein O3 / metabolism
  • Oocytes / enzymology*
  • PTEN Phosphohydrolase / metabolism
  • Parthenogenesis
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Signal Transduction*
  • bcl-2-Associated X Protein / metabolism

Substances

  • Forkhead Box Protein O3
  • bcl-2-Associated X Protein
  • Phosphatidylinositol 3-Kinases
  • Proto-Oncogene Proteins c-akt
  • PTEN Phosphohydrolase

Grants and funding

This work was supported by the Sao Paulo Research Foundation (FAPESP grants 2014/21034-3; 2014/22887-0; 2013/08135-2 and 2012/50533-2). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.