This study investigated the role of milk fat globule-epidermal growth factor-factor 8 (MFGE8) in TGF-β-induced epithelial–mesenchymal transition (EMT) of endometrial epithelial cells. These were in vitro studies using human endometrial epithelial cells and mouse blastocysts. We investigated the ability of TGF-β to induce EMT in endometrial epithelial cells (HEC-1A) by assessment of cytological phenotype (by light and atomic force microscopy), changes in expression of the markers of cell adhesion/differentiation E- and N-cadherin, and of the transcription factor Snail (by immunofluorescence and immunoblotting), and competence to support embryo attachment in a mouse blastocyst outgrowth assay. We also studied the effects of E-cadherin expression in cells transfected by retroviral shRNA vectors specifically silencing MFGE8. Results demonstrated that TGF-β induced EMT as demonstrated by phenotypic cell changes, by a switch of cadherin expression as well as by upregulation of the expression of the mesenchymal markers Snail and Vimentin. Upon MFGE8 knockdown, these processes were interfered with, suggesting that MFGE8 and TGF-β together may participate in regulation of EMT. This study demonstrated for the first time that endometrial MFGE8 modulates TGF-β-induced EMT in human endometrium cells.
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Liang Yu, Rong Hu, Claretta Sullivan, R James Swanson, Sergio Oehninger, Ying-Pu Sun, and Silvina Bocca
Lanlan Fang, Sijia Wang, Yiran Li, Yiping Yu, Yuxi Li, Yang Yan, Jung-Chien Cheng, and Ying-Pu Sun
Polycystic ovary syndrome (PCOS) is the most common cause of female infertility. Growth differentiation factor-8 (GDF-8) is expressed in the ovary and can be detected in human follicular fluid which provides an important microenvironment for maintaining physiological functions of the ovarian follicle. To date, the relationship between GDF-8 levels in follicular fluid and the risk of PCOS is completely unknown. In the present study, we show that during the process of the controlled ovarian hyperstimulation (COH), serum GDF-8 levels are higher on the day of gonadotropin administration and 14 days after embryo transfer in in vitro fertilization (IVF) patients with PCOS than they are in IVF patients without PCOS. Importantly, GDF-8 levels in follicular fluid at oocyte retrieval are also higher in PCOS patients than in non-PCOS patients. Treatment of primary human granulosa-lutein (hGL) cells with GDF-8 downregulates StAR protein expression and the inhibition is more pronounced in hGL cells from PCOS patients than it is in cells from non-PCOS patients. Importantly, high GDF-8 levels and low progesterone (P4) levels were associated with poor pregnancy outcomes in PCOS patients. Our results provide the first evidence that aberrant expression of GDF-8 in the follicular fluid of PCOS patients results in abnormal P4 expression, which leads to poor pregnancy outcomes.
Lanlan Fang, Zhen Wang, Ze Wu, Yang Yan, Yibo Gao, Yuxi Li, Jung-Chien Cheng, and Ying-Pu Sun
Matrix metalloproteinases (MMPs) play a pivotal role in the regulation of cell invasion. Placental trophoblast cell invasion is a precisely regulated event. Dysregulation of MMPs has been linked to various placental diseases. Growth differentiation factor-8 (GDF-8), also known as myostatin, is a member of the transforming growth factor-beta (TGF-β) superfamily. GDF-8 and its putative receptors are expressed in human extravillous cytotrophoblast cells (EVTs). Although the pro-invasive effect of GDF-8 in human EVT cells has been recently reported, the underlying molecular mechanism remains largely unknown. In this study, we investigate the effects of GDF-8 on the expression of the two most important MMPs, MMP2 and MMP9, in the HTR-8/SVneo human EVT cell line. Our results show that GDF-8 significantly upregulates the expression of MMP2. The expression of MMP9 is not affected by GDF-8. Using a siRNA-mediated knockdown approach, we reveal that the stimulatory effect of GDF-8 on MMP2 expression is mediated by the ALK5-SMAD2/3 signaling pathway. Additionally, the knockdown of MMP2 attenuates the GDF-8-induced cell invasiveness. These findings deepen our understanding of the biological roles of GDF-8 in the regulation of human trophoblast cell invasion.