Distribution of the phospholipase A2 receptor messenger RNA in human gestational tissues

Recently, a model has been proposed for the involvement of secretory phospholipase A2 (sPLA2) in the onset of and/or progression of human labour via the metabolism of cell membrane glycerophospholipids to generate biologically active, phospholipid-derived mediators. The recent molecular cloning and characterization of a cell-surface receptor for sPLA2 raise the possibility that sPLA2 enzymes may also affect cell function in intrauterine tissues via a receptor-mediated pathway. The aim of this study was to determine the expression profile of the PLA2 receptor messenger RNA in human gestational tissues at term. Messenger RNA for the PLA2 receptor was detected in amnion, choriodecidua and placenta by RT-PCR and transcripts of similar size to the 6.5- and 5.4-kb transcripts previously reported in various other human tissues were detected in choriodecidua by Northern blot analysis. However, smaller transcripts of approximately 4, 2.3 and 1 kb were also detected in choriodecidua by Northern blot analysis and the 2.3-kb transcript and the 1-kb transcript were the only major transcripts detected in amnion and placenta, respectively. The presence of PLA2 receptor mRNA in human gestational tissues indicates that an alternative non-catalytic pathway may contribute to the regulatory effects of sPLA2 isozymes in these tissues. While the specificity and affinity of the various transcripts identified in this study have yet to be determined, PLA2 isozymes released from human gestational tissues during pregnancy and at the time of labour may function as paracrine or autocrine mediators to affect cell function.