title: Starting a new life: sperm PLC-zeta mobilizes the Ca2+ signal that induces egg activation and embryo development: an essential phospholipase C with implications for male infertility.
abstract: We have discovered that a single sperm protein, phospholipase C-zeta (PLCζ), can stimulate intracellular Ca(2+)  signalling in the unfertilized oocyte ('egg') culminating in the initiation of embryonic development. Upon fertilization by a spermatozoon, the earliest observed signalling event in the dormant egg is a large, transient increase in free Ca(2+)  concentration. The fertilized egg responds to the intracellular Ca(2+)  rise by completing meiosis. In mammalian eggs, the Ca(2+)  signal is delivered as a train of long-lasting cytoplasmic Ca(2+)  oscillations that begin soon after gamete fusion and persist beyond the completion of meiosis. Sperm PLCζ effects Ca(2+)  release from egg intracellular stores by hydrolyzing the membrane lipid PIP(2)  and consequent stimulation of the inositol 1,4,5-trisphosphate (InsP(3) ) receptor Ca(2+) -signalling pathway, leading to egg activation and early embryogenesis. Recent advances have refined our understanding of how PLCζ induces Ca(2+)  oscillations in the egg and also suggest its potential dysfunction as a cause of male infertility.
authors.affiliation: Cell Signalling Laboratory, WHRI, Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff, UK.
authors.forename: Michail
authors.initials: M
authors.lastname: Nomikos
authors.forename: Karl
authors.initials: K
authors.lastname: Swann
authors.forename: F Anthony
authors.initials: FA
authors.lastname: Lai
mesh_terms: D000818:Animals; D002118:Calcium; D020013:Calcium Signaling; D047108:Embryonic Development; D005260:Female; D005306:Fertilization; D006801:Humans; D007246:Infertility / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008297:Male; D008540:Meiosis; D051379:Mice; D009865:Oocytes / Q000254:growth & development / Q000378:metabolism*; D054801:Phosphoinositide Phospholipase C / Q000378:metabolism*; D011247:Pregnancy; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D015544:Inositol 1,4,5-Trisphosphate; C499235:PLCZ1 protein, human; D054801:Phosphoinositide Phospholipase C; D002118:Calcium