Expression and localization of TMED2/p24 beta in human placenta and two models of human placenta BeWo and JEG-3 cells

Normal development of the chorionic villi in human placenta is critical for proper exchange of nutrients and oxygen between the mother and the fetus. The chorionic villi of the placenta are formed by the differentiation of trophoblast cells into cytotrophoblast and syncytiotrophoblast cells, which are both important for proper placental function. Tmed2 was shown to be required for normal embryo and placental development in the mouse. In Tmed2 mutant embryos, the labyrinth layer of the placenta fails to form. The labyrinth layer of the mouse placenta is equivalent to the chorionic villi of the human placenta, and is essential for a successful pregnancy. We hypothesized that TMED2 is expressed in the human placenta, and could be involved in trophoblast differentiation. The objectives of this study are to characterize TMED2 expression in first trimester and term human placenta, and to compare TMED2 mRNA and protein levels in two cell lines, BeWo and JEG-3, that are widely used for studying trophoblast differentiation. We found by immunocytochemistry that TMED2 is expressed in both first trimester and term human placenta. We also found that TMED2 is expressed in BeWo cells, which are known to form syncytiotrophoblast after forskolin treatment, but not expressed in JEG-3 cells, which do not undergo syncytiotrophoblast differentiation.