Changes in the Activity and Expression of Cytosolic Pospholipase A2 in Human Amnion at Parturition

Han, G S; Lee, Y K; Park, Y K

Abstract

OBJECTIVE
Cytosolic phospholipase A2 [cPLA2 exhibits preference for arachidonic acid in the sn-2 phospholipid, and it may play a role in agonist-stimulated signal transduction pathways involving prostaglandin synthesis. The purpose of this study was to examine the activity and expression of cPLA2, and to determine whether an increased cPLA2 mediated the arachidonic acid mobilization for prostaglandin synthesis in amnion at parturition.
METHODS
Amnion was collected immediately after delivery from four patients groups; preterm or term, either in or not in labor and stored at -70degrees C. Preterm was defined as < or =37 weeks of gestation and term as >37 completed weeks of gestation. Tissues were homogenized and centrifuged for 1 hour at 13,000rpm. The characterization of cPLA2 in amnion was tested.
RESULTS
The molecular mass was estimated to approximately 100 Kd on SDS-PAGE. The cPLA2 activity showed protein dose dependency. The maximum activity of cPLA2 was shown in a wide range of neutral pH and 37degrees C in temperature. This cPLA2 activity also showed requirement of Ca at the nanomolar concentration. Furthermore, the cPLA2 activity in the term group with no labor was significantly higher than the other groups. In addition, the changes in the expression of cPLA2 protein correlated with the activities.
CONCLUSION
The cPLA2 in amnion may be involved in the mobilization of arachidonic acid during the parturition. Taken together, the results suggest that the changes of cPLA2 between term and preterm groups show different mechanisms of arachidonic acid mobilization.