The effects of kinase modulation on in vitro maturation according to different cumulus-oocyte complex morphologies

PLoS One. 2018 Oct 11;13(10):e0205495. doi: 10.1371/journal.pone.0205495. eCollection 2018.

Abstract

Successful production of transgenic pigs requires oocytes with a high developmental competence. However, cumulus-oocyte complexes (COCs) obtained from antral follicles have a heterogeneous morphology. COCs can be classified into one of two classes: class I, with five or more layers of cumulus cells; and class II, with one or two layers of cumulus cells. Activator [e.g., epidermal growth factor (EGF)] or inhibitors (e.g., wortmannin and U0126) are added to modulate kinases in oocytes during meiosis. In the present study, we investigated the effects of kinase modulation on nuclear and cytoplasmic maturation in COCs. Class I COCs showed a significantly higher developmental competence than class II COCs. Moreover, the expression of two kinases, AKT and ERK, differed between class I and class II COCs during in vitro maturation (IVM). Initially, inhibition of the PI3K/AKT signaling pathway in class I COCs during early IVM (0-22 h) decreased developmental parameters, such as blastocyst formation rate, blastomere number, and cell survival. Conversely, EGF-mediated AKT activation in class II COCs enhanced developmental capacity. Regarding the MAPK signaling pathway, inhibition of ERK by U0126 in class II COCs during early IVM impaired developmental competence. However, transient treatment with U0126 in class II COCs increased oocyte maturation and AKT activity, improving embryonic development. Additionally, western blotting showed that inhibition of ERK activity negatively regulated the AKT signaling pathway, indicative of a relationship between AKT and MAPK signaling in the process underlying meiotic progression in pigs. These findings may help increase the developmental competence and utilization rate of pig COCs with regard to the production of transgenic pigs and improve our understanding of kinase-associated meiosis events.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blastocyst / cytology
  • Blastocyst / drug effects
  • Blastocyst / enzymology
  • Cell Nucleus / drug effects
  • Cell Nucleus / enzymology
  • Cell Survival / drug effects
  • Cumulus Cells / cytology
  • Cumulus Cells / drug effects
  • Cumulus Cells / enzymology*
  • Cytoplasm / drug effects
  • Cytoplasm / enzymology
  • Epidermal Growth Factor / pharmacology
  • Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • In Vitro Oocyte Maturation Techniques*
  • Oncogene Protein v-akt / antagonists & inhibitors
  • Oncogene Protein v-akt / metabolism*
  • Oocytes / cytology
  • Oocytes / drug effects
  • Oocytes / enzymology*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors
  • Signal Transduction / drug effects
  • Sus scrofa

Substances

  • Phosphoinositide-3 Kinase Inhibitors
  • Epidermal Growth Factor
  • Oncogene Protein v-akt
  • Extracellular Signal-Regulated MAP Kinases

Grants and funding

This study was supported by grants from the KRIBB Research Initiative Programs (KGM4241844), KRIBB Research Initiative Programs (KGM4251824), and Republic of Korea and the Bio & Medical Technology Development Program of the NRF funded by the Korean government, MSIT (2018M3A9H1023142).