Regulatory Effects of Fyn on Trophoblast Cell Behaviors and Function

Fyn has been proven to be involved in various cell behaviors and pathophysiological processes. However, the expression and roles of Fyn in trophoblasts remain unclear. Here, we aimed to evaluate the participation of Fyn in trophoblast behavior and function, and the related mechanisms were briefly explored. Fyn expression in the HTR-8/SVneo, JEG-3, and JAR cell lines was evaluated by immunofluorescence, quantitative real-time PCR and western blotting. Fyn expression in human hydatidiform moles was also determined by immunohistochemistry and western blot. To explore the effects of Fyn, HTR-8/SVneo and JEG-3 cells were transfected with Fyn shRNA or overexpression plasmid or treated with the Fyn activity inhibitor SU6656 or ERK1/2 inhibitor U0126. The migration, proliferation, and apoptosis of trophoblast cells were assessed using transwell assays, flow cytometry, and cell counting kit-8 assays, respectively. The production of primary inflammatory cytokines, HLA-G and active matrix metallopeptidase (MMP) 2/9, and the phosphorylation of ERK1/2 and STAT3 were evaluated by ELISA, western blot, or gelatin zymography. The results showed that Fyn was expressed by trophoblast cells, mainly in the cytoplasm and membrane. Fyn expression and activity levels both increased in order from HTR-8/SVneo and JAR to JEG-3. The overexpression of Fyn promoted the proliferation and migration of trophoblast cells and inhibited their apoptosis, while the opposite effects were observed for Fyn knockdown and inhibition. Fyn regulated inflammatory cytokine production in trophoblast cells by promoting TGF-β and IL-4 secretion while inhibiting IFN-γ and TNF-α secretion. Moreover, HLA-G expression in JEG-3 was positively regulated by Fyn. Fyn also facilitated the expression of active MMP2/9 and the activation of ERK1/2 and STAT3. Besides, it was confirmed that Fyn regulated trophoblast cell activities through ERK1/2 signal pathway by using U0126. Our study first detected the expression of Fyn in trophoblast cells. Fyn played pivotal roles in trophoblast cell behaviors and function, ERK1/2 was one of its targets, and MMP2/9 and STAT3 may also be involved in the regulatory mechanism.