Epiregulin promotes trophoblast epithelial-mesenchymal transition through poFUT1 and O-fucosylation by poFUT1 on uPA.

OBJECTIVES:The transformation of cytotrophoblasts into mesenchymal-like extravillous trophoblasts is necessary for successful embryo implantation, and the inadequate transformation may cause abortion. Epiregulin, which is a new growth factor, plays important roles in the reproductive processes. The glycosylation of many proteins in reproduction processes is critical. Protein O-fucosyltransferase 1 (poFUT1) is the key enzyme for the biosynthesis of O-fucosylation on the specific glycoproteins. Urokinase-type plasminogen activator (uPA) contains O-fucosylated domain on Thr¹⁸ . However, the functions of epiregulin and poFUT1 in the trophoblast epithelial-mesenchymal transition (EMT) process, the regulatory mechanism of epiregulin on poFUT1 and the resulting O-fucosylated uPA remain unclear. MATERIALS AND METHODS:We employed ELISA and Western blot to detect serum levels of epiregulin and poFUT1 from non-pregnancy women, pregnancy women and abortion patients. Using two trophoblast cell lines and a mouse pregnancy model, we investigated the underlying mechanisms of epiregulin and poFUT1 in trophoblast EMT process. RESULTS:Serum levels of epiregulin and poFUT1 were higher in pregnant women compared with non-pregnant women, and their levels were significantly decreased in abortion patients compared with pregnant women. The results showed that epiregulin upregulated poFUT1 expression and increased O-fucosylation on uPA, which further activated the PI3K/Akt signalling pathway, facilitating EMT behaviour of trophoblast cells and embryo implantation in the mouse pregnant model. CONCLUSIONS:Level of epiregulin and poFUT1 is lower in abortion patients than early pregnancy women. Epiregulin promotes trophoblast EMT through O-fucosylation on uPA catalysed by poFUT1. Epiregulin and poFUT1 may be suggested as the potential diagnostic biomarkers and useful treatment targets for abortion.

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