Expression And Regulation Of Cytosolic Phospholipase A₂α Gene In Mouse Uterus During Early Pregnancy

Cytosolic phospholipase A2α (cPLA2α), one of the phospholipase A2 superfamily(PLA2)members, is ubiquitously and constitutively expressed in most cells and tissues. The activation of cPLA2α is regulated by Ca2+ concentration and phosphorylation. cPLA2α catalyzes the hydrolysis of the sn-2 position of membrane glycerophos-pholipids to liberate arachidonic acid (AA) and is a major provider of arachidonic acid for the cyclooxygenase (COX) system for the biosynthesis of prostaglandins (PGs). PGs synthesized by this pathway are implicated in various female reproductive functions, which is under the regulation of cPLA2α. The aim of this study was to examine cPLA2α gene expression and regulation in mouse uterus during early pregnancy, pseudopregnancy, delayed implantation, artificial decidualization and hormonal treatment by in situ hybridization and immunohistochemistry.cPLA2α immunostaining was detected in the luminal epithelium and glandular epithelium of mouse uterus from days 1 to 5 of pregnancy. cPLA2α mRNA signal could only be detected from days 2 to 4 of pregnancy. A strong level of cPLA2α expression was observed in the epithelium on day 3 of pregnancy. cPLA2α mRNA and immunostaining were located in decidualized cells in the mesometrium side from days 6 to 8 of pregnancy. Under artificial decidualization, cPLA2α mRNA signal and immunostaining were mainly seen in the decidualized cells at the mesometrium side.cPLA2α immunostaining was observed in luminal and glandular epithelium of mouse uterus on days 1, 4, 5 and 8 of pseudopregnancy. cPLA2α mRNA signal could only be detected on 4, 5 and 8 of pseudopregnancy. In the uterus under delayed implantation, cPLA2α mRNA and immunostaining were strongly located in the luminal and glandular epithelium. cPLA2α protein expression was weakened and cPLA2α mRNA signal could hardly be detected after activation. In the ovariectomized mice, cPLA2α mRNA and immunostaining were detected in the luminal and glandular epithelium. cPLA2α immunostaining remained unchanged by hormonal treatment. Estrogen down-regulated cPLA2α mRNA signal and progesterone had no effects on cPLA2α mRNA signal.In conclusion, our results suggest that cPLA2α may be closely related to embryo implantation and decidualization. Postgraduate: Yu Hao Speciality: Developmental Biology Supervisor: Professor Yang Zengming...