Decreased Expression and Altered Methylation of Syncytin-1 Gene in Human Placentas Associated with Preeclampsia

Author(s): Xue-Wei Zhuang, Jinping Li, Brian C. Brost, Xi-Yan Xia, Hai Bin Chen, Chuan-Xin Wang, Shi-Wen Jiang

Journal Name: Current Pharmaceutical Design

Volume 20 , Issue 11 , 2014

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Syncytin-1 is a protein coded by a human endogenous retrovirus (HERV) gene of the HERV-W family (HERVWE1). Syncytin- 1 mediates formation of syncytiotrophoblasts through fusion of cytotrophoblasts, a hallmark of terminal differentiation of placental trophoblast linage. Syncytin-1 also possesses nonfusogenic functions and regulates cell cycle progression. While decreased syncytin-1 expression and syncytium deficiency are considered important pathological changes in preeclampsia, the molecular mechanism(s) underlying syncytin-1 downregulation remains unclear. In this study, we confirmed that expression levels of syncytin-1 mRNA and protein were significantly lower in preeclamptic placentas compared to normal controls. Human chorionic somatomammotropin expression, a marker for syncytium function, was also decreased in preeclamptic placentas. The mRNA levels of ASCT2, the syncytin-1 receptor involved in cell fusion process, and GCMa, a transcriptional factor known to regulate syncytin-1 expression, were not significantly altered. Methylation in the 5’LTR of syncytin-1 promoter was quantified by COBRA, methylation-specific PCR, and DNA sequencing. Results from all three assays indicated significantly hypermethylated syncytin-1 promoter in preeclamptic placentas compared to normal controls. Methylation levels were inversely correlated with syncytin-1 mRNA levels, suggesting that hypermethylation may lead to syncytin-1 downregulation. Further experiments indicated that DNMT1 and DNMT3B3 mRNA and protein levels were increased in preeclamptic placentas, suggesting that higher DNA methyltransferase activity may contribute to the hypermethylation of syncytin-1 in preeclamptic placentas. These results indicated that aberrant hypermethylation is involved in downregulation of syncytin-1, and epigenetic alterations may play a significant role in the development of preeclampsia.

Keywords: Syncytin-1, DNA methylation, preeclampsia, trophoblast, placenta.

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Article Details

Year: 2014
Page: [1796 - 1802]
Pages: 7
DOI: 10.2174/13816128113199990541
Price: $65

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