Divergent effect of mammalian PLC? in generating Ca²? oscillations in somatic cells compared with eggs.

ABSTRACT: Sperm PLC? (phospholipase C?) is a distinct phosphoinositide-specific PLC isoform that is proposed to be the physiological trigger of egg activation and embryo development at mammalian fertilization. Recombinant PLC? has the ability to trigger Ca²? oscillations when expressed in eggs, but it is not known how PLC? activity is regulated in sperm or eggs. In the present study, we have transfected CHO (Chinese-hamster ovary) cells with PLC? fused with either YFP (yellow fluorescent protein) or luciferase and found that PLC?-transfected cells did not display cytoplasmic Ca²? oscillations any differently from control cells. PLC? expression was not associated with changes in CHO cell resting Ca²? levels, nor with a significantly changed Ca²? response to extracellular ATP compared with control cells transfected with either YFP alone, a catalytically inactive PLC? or luciferase alone. Sperm extracts containing PLC? also failed to cause Ca²? oscillations in CHO cells. Despite these findings, PLC?-transfected CHO cell extracts exhibited high recombinant protein expression and PLC activity. Furthermore, either PLC?-transfected CHO cells or derived cell extracts could specifically cause cytoplasmic Ca²? oscillations when microinjected into mouse eggs. These data suggest that PLC?-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.

SUBMITTER: Phillips SV 

PROVIDER: S-EPMC3195308 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature