Divergent effect of mammalian PLC-zeta in generating Ca2+ oscillations in somatic cells versus eggs

Sally Phillips , Yuansong Yu , Andreas Rossbach , Michail Nomikos , Vyronia Vassilakopoulou , Evangelia Livaniou , Bevan Cumbes , F. Anthony Lai , Christopher H George , Karl Swann (1)

1 Obstetrics and Gynaecology

Sperm PLC-zeta (PLCz) is a distinct phosphoinositide-specific phospholipase C isoform that is proposed to be the physiological trigger of egg activation and embryo development at mammalian fertilization. Recombinant PLCz has the ability to trigger Ca2+ oscillations when expressed in eggs, but it is not known how PLCz activity is regulated in sperm or eggs. Here, we have transfected CHO cells with PLCz fused with either YFP or luciferase and found that PLCz-transfected cells did not display cytoplasmic Ca2+ oscillations any different from control cells. PLCz expression was not associated with changes in CHO cell resting Ca2+ levels, nor in a significantly changed Ca2+ response to extracellular ATP compared to control cells transfected with either YFP alone, a catalytically-inactive PLCz, or luciferase alone. Sperm extracts containing PLCz also failed to cause Ca2+ oscillations in CHO cells. Despite these findings, PLCz-transfected CHO cell extracts exhibited high recombinant protein expression and PLC activity. Further, either PLCz-transfected CHO cells, or derived cell extracts, could specifically cause cytoplasmic Ca2+ oscillations when microinjected into mouse eggs. This data suggests that PLCz-mediated Ca2+ oscillations may require specific factors that are only present within the egg cytoplasm or be inhibited by factors present only in somatic cell lines.

Mots clés: Life Sciences

Sally Phillips, Yuansong Yu, Andreas Rossbach, Michail Nomikos, Vyronia Vassilakopoulou, et al.. Divergent effect of mammalian PLC-zeta in generating Ca2+ oscillations in somatic cells versus eggs. Biochemical Journal, 2011, 438 (3), pp.545-553. ⟨10.1042/BJ20101581⟩. ⟨hal-00617331⟩