The dynamics of MAPK inactivation at fertilization in mouse eggs

Jose Raul Gonzalez-Garcia, Josephine Bradley, Michail Nomikos, Laboni Paul, Zoltan Machaty, F. Anthony Lai, Karl Swann*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)
22 Downloads (Pure)


Egg activation at fertilization in mammals is initiated by prolonged Ca 2+ oscillations that trigger the completion of meiosis and formation of pronuclei. A fall in mitogen-activated protein kinase (MAPK) activity is essential for pronuclear formation, but the precise timing and mechanism of decline are unknown. Here, we have measured the dynamics of MAPK pathway inactivation during fertilization of mouse eggs using novel chemiluminescent MAPK activity reporters. This reveals that the MAPK activity decrease begins during the Ca 2+ oscillations, but MAPK does not completely inactivate until after pronuclear formation. The MAPKs present in eggs are Mos, MAP2K1 and MAP2K2 (MEK1 and MEK2, respectively) and MAPK3 and MAPK1 (ERK1 and ERK2, respectively). Notably, the MAPK activity decline at fertilization is not explained by upstream destruction of Mos, because a decrease in the signal from a Mos-luciferase reporter is not associated with egg activation. Furthermore, Mos overexpression does not affect the timing ofMAPK inactivation or pronuclear formation. However, the late decrease in MAPK could be rapidly reversed by the protein phosphatase inhibitor, okadaic acid. These data suggest that the completion of meiosis in mouse zygotes is driven by an increased phosphatase activity and not by a decline in Mos levels or MEK activity.

Original languageEnglish
Pages (from-to)2749-2760
Number of pages12
JournalJournal of Cell Science
Issue number12
Publication statusPublished - 25 Mar 2014
Externally publishedYes


  • Egg
  • Fertilization
  • MAPK
  • Zygote


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