Calmodulin-dependent protein kinase II triggers mouse egg activation and embryo development in the absence of Ca2+ oscillations

Dev Biol. 2006 Aug 15;296(2):388-95. doi: 10.1016/j.ydbio.2006.06.004. Epub 2006 Jun 7.

Abstract

Fertilization in mammalian eggs is accompanied by oscillatory changes in intracellular Ca(2+) concentration, which are critical for initiating and completing egg activation events and the developmental program. Ca(2+)/Camodulin-dependent protein kinase II (CaMKII) is a multifunctional enzyme that is postulated to be the downstream transducer of the Ca(2+) signal in many cell types. We tested the hypothesis that CaMKII is the major integrator of Ca(2+)-induced egg activation events and embryo development by microinjecting a cRNA that encodes a constitutively active (Ca(2+)-independent) mutant form of CaMKII (CA-CaMKII) into mouse eggs. Expression of this cRNA, which does not increase intracellular Ca(2+), induced a sustained rise in CaMKII activity and triggered egg activation events, including cell cycle resumption, and degradation and recruitment of maternal mRNAs; cortical granule exocytosis, however, did not occur normally. Furthermore, when mouse eggs were injected with sperm devoid of Ca(2+)-releasing activity and activated with either CA-CaMKII cRNA or by SrCl(2), similar rates and incidence of development to the blastocyst stage were observed. These results strongly suggest that CaMKII is a major integrator of the Ca(2+) changes that occur following fertilization.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium Signaling / physiology
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases / physiology*
  • Embryonic Development / physiology*
  • Female
  • Fertilization / physiology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Ovum / enzymology*
  • Ovum / metabolism
  • Sperm Injections, Intracytoplasmic
  • Sperm-Ovum Interactions / physiology
  • Spermatozoa / physiology
  • Tissue Culture Techniques

Substances

  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Calcium