PLCγ, G-protein of the Gαq type and cADPr pathway are associated to trigger the fertilization Ca2+ signal in the sea urchin egg.
In all species, fertilization triggers in the egg a rapid and transient increase of intracellular free calcium (Cai), but how this signal is generated following sperm and egg interaction has not been clearly characterised yet. In sea urchin, a signalling pathway involving tyrosine kinase and PLCγ has been proposed to be at the origin of the fertilization Cai signal. We report here that injection of src homology-2 (SH2) domains of the sea urchin PLCγ inhibits in a competitive manner the endogenous PLCγ, alters both the amplitude and duration of the fertilization Cai wave, but does not abrogate it. Our results suggest that PLCγ acts in conjunction with a cADPr pathway and G-proteins of the Gαq type to trigger the fertilization Cai wave, and reinforce a crucial role for PLCγ at mitosis and cytokinesis.
INSERM U935/Université Paris Sud/AP-HP, Histologie-Embryologie-Cytogénétique, Hôpital Antoine Béclère, 92141 Clamart, France.
Lucie
L
Tosca
Rainer
R
Glass
Odile
O
Bronchain
Laetitia
L
Philippe
Brigitte
B
Ciapa
D000818:Animals; D001483:Base Sequence; D020013:Calcium Signaling; D002478:Cells, Cultured; D036563:Cyclic ADP-Ribose / Q000378:metabolism*; D005260:Female; D005306:Fertilization; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D010063:Ovum / Q000378:metabolism*; D051966:Phospholipase C gamma / Q000235:genetics / Q000378:metabolism*; D012617:Sea Urchins / Q000502:physiology*; D013084:Sperm-Ovum Interactions; D019076:Transgenes / Q000235:genetics; D018909:src Homology Domains / Q000235:genetics
D036563:Cyclic ADP-Ribose; D051966:Phospholipase C gamma; D043802:GTP-Binding Protein alpha Subunits, Gq-G11