Calcium oscillations and mammalian egg activation
Article first published online: 9 SEP 2005
Copyright © 2005 Wiley-Liss, Inc.
Journal of Cellular Physiology
Volume 206, Issue 3, pages 565–573, March 2006
How to Cite
Malcuit, C., Kurokawa, M. and Fissore, R. A. (2006), Calcium oscillations and mammalian egg activation. J. Cell. Physiol., 206: 565–573. doi: 10.1002/jcp.20471
- Issue published online: 16 DEC 2005
- Article first published online: 9 SEP 2005
- Manuscript Accepted: 3 JUN 2005
- Manuscript Received: 12 MAY 2005
Fertilization in all species studied to date induces an increase in the intracellular concentration of free calcium ions ([Ca2+]i) within the egg. In mammals, this [Ca2+]i signal is delivered in the form of long-lasting [Ca2+]i oscillations that begin shortly after fusion of the gametes and persist beyond the time of completion of meiosis. While not fully elucidated, recent evidence supports the notion that the sperm delivers into the ooplasm a trigger of oscillations, the so-called sperm factor (SF). The recent discovery that mammalian sperm harbor a specific phospholipase C (PLC), PLCζ has consolidated this view. The fertilizing sperm, and presumably PLCζ promote Ca2+ release in eggs via the production of inositol 1,4,5-trisphosphate (IP3), which binds and gates its receptor, the type-1 IP3 receptor, located on the endoplasmic reticulum, the Ca2+ store of the cell. Repetitive Ca2+ release in this manner results in a positive cumulative effect on downstream signaling molecules that are responsible for the completion of all the events comprising egg activation. This review will discuss recent advances in our understanding of how [Ca2+]i oscillations are initiated and regulated in mammals, highlight areas of discrepancies, and emphasize the need to better characterize the downstream molecular cascades that are dependent on [Ca2+]i oscillations and that may impact embryo development. © 2005 Wiley-Liss, Inc.