Impaired Wnt5a signaling in extravillous trophoblasts: Relevance to poor placentation in early gestation and subsequent preeclampsia

Background: Defective decidual endovascular trophoblast invasion and subsequent impaired spiral artery remodeling is highly associated with the pathogenesis of preeclampsia (PE). Since there are scant and conflicting data regarding the function of Wnt5a signaling in extravillous trophoblasts (EVT), the aim of this study was to investigate whethere impaired Wnt5a signaling affects the invasive and tube forming capabilities of EVT. Methods: Expression levels of Wnt ligands were compared between first trimester chorionic villi of women who later developed PE and women with unaffected pregnancies using publicly available microarray data (GSE12767). Wnt5a expression was examined in placentas using quantitative RT-PCR, Western blot analysis and immunohistochemistry. The function of Wnt5a signaling in EVT was investigated in an immortalized first trimester EVT cell line, HTR-8/SVneo, using small-interfering RNAs, recombinant human Wnt5a (rhWnt5a), and inhibitors of JNK or PKC. Results: Microarray data analysis of the first trimester placentas showed that, among Wnt ligands, Wnt5a expression was significantly lower in women who later developed PE. The mRNA and protein expression levels of Wnt5a were significantly decreased in PE placentas compared with normal term placentas. Wnt5a knockdown significantly suppressed invasion and tube formation of HTR-8/SVneo cells, while the addition of rhWnt5a augmented the cell migration, invasion, and tube formation. Repression of Wnt5a/PKC signaling in HTR-8/SVneo cells inhibited cell invasion, but did not alter cell tube formation. In contrast, inhibition of Wnt5a/JNK signaling attenuated rhWnt5a-induced invasion and tube formation capabilities. Conclusions: These findings suggest that impaired Wnt5a signaling is associated with poor placentation and subsequent PE.