A series of intracellular oscillations in the free cytosolic Ca2+ concentration is responsible for activating mammalian eggs at fertilization, thus initiating embryo development. It has been proposed that the sperm causes these Ca2+ oscillations after membrane fusion by delivering a soluble protein into the egg cytoplasm. We previously identified sperm-specific phospholipase C (PLC)-ζ as a protein that can trigger the same pattern of Ca2+ oscillations in eggs seen at fertilization. PLCζ appears to be the elusive sperm factor mediating egg activation in mammals. It has potential therapeutic use in infertility treatments to improve the rate of egg activation and early embryo development after intra-cytoplasmic sperm injection. A stable form of recombinant human PLCζ could be a prototype for use in such in vitro fertilization (IVF) treatments. We do not yet understand exactly how PLCζ causes inositol 1,4,5-trisphosphate (InsP3) production in eggs. Sperm PLCζ is distinct among mammalian PI-specific PLCs in that it is far more potent in triggering Ca2+ oscillations in eggs than other PLCs, but it lacks a PH domain that would otherwise be considered essential for binding to the phosphatidylinositol 4,5-bisphosphate (PIP2) substrate. PLCζ is also unusual in that it does not appear to interact with or hydrolyse plasma membrane PIP2. We consider how other regions of PLCζ may mediate its binding to PIP2 in eggs and how interaction of PLCζ with egg-specific factors could enable the hydrolysis of internal sources of PIP2.
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February 2016
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Cover Image
Scanning electron micrograph of a cell from the endosperm of a barley grain. The cell is tightly packed with large, disk-shaped (A-type) and much smaller, almost spherical (B-type) starch granules. The smooth areas in this image are the surface of the cell walls of neighbouring endosperm cells. For further details see pp. 157-163. Image kindly provided by Elaine Barclay and Vasilios Andriotis (John Innes Centre, Norwich). - PDF Icon PDF LinkTable of Contents
Review Article|
February 09 2016
The sperm phospholipase C-ζ and Ca2+ signalling at fertilization in mammals
Karl Swann;
Karl Swann
1
*College of Biomedical and Life Sciences, Cardiff University, Cardiff CF14 4XN, U.K.
1To whom correspondence should be addressed (email swannk1@cardiff.ac.uk).
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F. Anthony Lai
F. Anthony Lai
*College of Biomedical and Life Sciences, Cardiff University, Cardiff CF14 4XN, U.K.
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Publisher: Portland Press Ltd
Received:
November 20 2015
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2016 Authors; published by Portland Press Limited
2016
Biochem Soc Trans (2016) 44 (1): 267–272.
Article history
Received:
November 20 2015
Citation
Karl Swann, F. Anthony Lai; The sperm phospholipase C-ζ and Ca2+ signalling at fertilization in mammals. Biochem Soc Trans 15 February 2016; 44 (1): 267–272. doi: https://doi.org/10.1042/BST20150221
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