The Role of Syncytin in Placental Angiogenesis and Fetal Growth

Background: Syncytin, a retroviral envelope protein, is specifically expressed on trophoblast cells and mediates formation of the syncytiotrophoblast through fusogenic activity. Decreased expression of Syncytin was found in fetal growth restriction placentas.Results: By generating an inducible knockout of the syncytin-a gene in mice, we show a specific disruption of placental angiogenesis with abnormal formation of two syncytiotrophoblast layers. Consistent with the defects observed in vivo, conditioned medium collected from trophoblast cells, following Syncytin-1 knockdown, contains lower expression of vascular endothelial growth factor and placental growth factor, and higher levels of soluble fms-like protein kinase-1 in BeWo and HTR-8/SVneo cells which related with suppressed PI3K/Akt/mTOR pathway, and is reduced in ability to induce tube formation by HUVECs.Conclusion: Syncytin participates in angiogenesis during placental development was first identified both in vivo and in vitro. Here, we give a new sight on understanding syncytin and pathophysiology of placenta related disease such as fetal growth restriction.

Automated summary

In this study, we found that syncytin participates in angiogenesis during placental development, as observed in mice with an inducible syncytin-a gene knockout. We also found that syncytin affects the expression of vascular endothelial growth factor, placental growth factor, and soluble fms-like protein kinase-1, as well as the PI3K/Akt/mTOR pathway and the ability to induce tube formation by HUVECs. This new insight into syncytin and the pathophysiology of placenta-related diseases such as fetal growth restriction is significant.