Functional platelet-activating factor receptors linked to inositol lipid hydrolysis, calcium mobilization and tyrosine kinase activity in the human endometrial HEC-1B cell line

摘要

Platelet-activating factor (PAF; sn-1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is thought to be an important mediator of embryo–endometrial interactions in early pregnancy, and an understanding of its role in the establishment of early human pregnancy can only follow an understanding of its mechanism of action. In a human endometrial epithelial cell line, HEC-1B, the presence of mRNA encoding the platelet-activating factor receptor was demonstrated by reverse transcription–polymerase chain reaction. The presence of functional receptors was shown by inositol trisphosphate accumulation and a rise in the concentration of intracellular free calcium evoked by platelet-activating factor in myo-[2-3H]inositol-labelled and fura-2-loaded cells, respectively. Platelet-activating factor evoked rapid and concentration-dependent increases in the concentration of intracellular free calcium and inositol trisphosphate that were inhibited by the platelet-activating factor receptor antagonist WEB 2086, indicating that the responses are receptor mediated. Inositol trisphosphate accumulation evoked by platelet-activating factor was unaffected by pretreatment with pertussis toxin. Platelet-activating factor also stimulated the tyrosine phosphorylation of at least two major proteins of 80 kDa and 44 kDa; the smaller protein is an isoform of mitogen-activated protein kinase. These results show that functional platelet-activating factor receptors are located on the endometrial epithelial cell line HEC-1B and are linked to inositol lipid hydrolysis, calcium mobilization and tyrosine kinase activity.