Over-expression of stomatin causes syncytium formation in nonfusogenic JEG-3 choriocarcinoma placental cells
Over-expression of stomatin causes syncytium formation in nonfusogenic JEG-3 choriocarcinoma placental cells
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DOI：
10.1002/cbin.10636
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发表时间：
2016-08-01
影响因子：
3.9
通讯作者：
Lin, Chi-Hung
中科院分区：
文献类型：
--
作者：
Chen, Tung-Wei;Liu, Hong-Wen;Lin, Chi-Hung
胎盘滋养层细胞的分化涉及单个核细胞滋养层细胞的持续融合。然而，除了合胞素，很少有人知道滋养层融合的详细机制。以前的研究表明，脂筏在HTLV-1合胞体形成中起重要作用。为了确定可能参与胎盘滋养层分化的蛋白质，我们研究了stomatin，一种重要的脂筏蛋白，定位于抗洗涤剂的膜结构域。通过免疫荧光染色观察合胞体和人绒毛膜促性腺激素（-hCG;胎盘滋养层分化的标志物）。我们发现在非融合的JEG-3细胞系中过表达stomatin可引起合胞体的形成并增加细胞的融合指数。用N-6，2-O-二丁酰腺苷3，5-环一磷酸处理这些细胞进一步增加了气孔蛋白引起的细胞融合。48 h时，在少数高表达气孔蛋白的JEG-3细胞中发现了-hCG，沿着多核合胞体的形成，-hCG的表达水平在72 h时显著升高。利用RNA干扰技术降低融合型人绒毛膜癌细胞系BeWo细胞中气孔蛋白的表达。敲除72 h后，气孔蛋白水平下降了近95%。对照组和气孔蛋白基因敲除组的融合指数在72 h时分别为9.4和6.5%。我们的数据表明，气孔蛋白可以触发合胞体的形成和上调-hCG的细胞融合在非融合JEG-3细胞。下调气孔蛋白的表达可轻微抑制融合BeWo细胞的融合指数。因此，这些数据表明，气孔蛋白在滋养细胞分化中起着重要作用。
Placental trophoblast differentiation involves the continuous fusion of mononuclear cytotrophoblasts. However, except for syncytin, little is known about the detailed mechanisms underlying trophoblast fusion. A previous study indicated that lipid rafts play an important role in HTLV-1 syncytium formation. To identify proteins that may be involved in placental trophoblast differentiation, we examined stomatin, an important lipid-raft protein that localizes to detergent-resistant membrane domains. The syncytium and human chorionic gonadotropin (-hCG; a marker of placental trophoblast differentiation) were visualized by immunofluorescence staining. We found that overexpression of stomatin in the nonfusogenic JEG-3 cell line caused syncytium formation and increased the fusion index of cells. Treating these cells with N-6,2-O-dibutyryladenosine 3,5-cyclic monophosphate further increased cell fusion by stomatin. -hCG was found in a few JEG-3 cells overexpressing stomatin at 48h, and its levels increased dramatically at 72h along with the formation of the multinuclear syncytium. RNA interference was used to decrease stomatin expression in BeWo cells, a fusogenic human choriocarcinoma cell line. After knockdown for 72h, stomatin levels decreased by almost 95%. The fusion indexes of control and stomatin-knockdown cells at 72h were 9.4 and 6.5%, respectively. Our data indicated that stomatin could trigger syncytium formation and upregulate -hCG for cell fusion in nonfusogenic JEG-3 cells. Downregulation of stomatin slightly inhibited the fusion index of fusogenic BeWo cells. Thus, these data suggested that stomatin plays an important role in trophoblast differentiation.