The Role of Syncytin in Placental Angiogenesis and Fetal Growth

Abstract

<b>Background:</b> 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. <b>Results:</b> By generating an inducible knockout of the <i>syncytin-a</i> gene in mice, we show a specific disruption of placental angiogenesis with abnormal formation of two syncytiotrophoblast layers. Consistent with the defects observed <i>in vivo</i>, 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. <b>Conclusion:</b> Syncytin participates in angiogenesis during placental development was first identified both <i>in vivo</i> and <i>in vitro</i>. Here, we give a new sight on understanding syncytin and pathophysiology of placenta related disease such as fetal growth restriction.