Fig. 2.
Working model of the role of lysophosphatidic acid (LPA) at the maternal-conceptus interface in pigs. Estrogen of conceptus origin induces endometrial epithelial expression of LPA receptor 3 (LPAR3), and ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2) activates endometrial production of LPA. LPAs secreted into the uterine lumen act on endometrial luminal (LE) and glandular epithelial (GE) cells to increase the expression of prostaglandin (PG)-endoperoxide synthase 2 (PTGS2), which in turn acts on the production of PGF2α and PGE2. LPAs also act on the conceptus trophectoderm to activate the extracellular signal-regulated kinases 1/2 (ERK1/2) and p90 ribosomal S6 kinase (P90RSK) signaling pathway and the p38 mitogen-activated protein kinase (MAPK) signaling pathway, which induces the expression of urokinase-type plasminogen activator (PLAU) and PTGS2