Cell and Molecular mechanisms of placental syncytialisation : implications for the pathogenesis of pre-eclampsia

(1)A胎盘滋养层合胞化的独特生物学过程已经使用合胞化的细胞模型（细胞滋养层细胞系BeWo，在通过毛喉素增加细胞内cAMP之后）进行了研究。（2）已经产生了组成型表达融合蛋白绿色荧光蛋白和人组蛋白H2 B或红色荧光蛋白和来自人细胞色素c氧化酶亚基VIII的线粒体靶向序列的融合蛋白的稳定BeWo细胞系。使用表达不同颜色的荧光蛋白的这两种BeWo细胞系，细胞融合（合胞化）已经可视化，并且已经开发了用于定量测定合胞化速率的基于荧光激活细胞分选的测定。（3）利用DNA微阵列技术研究了细胞合体化的时间进程。在毛喉素治疗后表达增加的基因中，有许多是细胞通讯和代谢所需的。已知参与细胞粘附和融合的几个基因在毛喉素暴露后很早就显著改变了表达水平，从而先于BeWo细胞的形态融合。进一步分析这些数据和表达谱一般将有助于了解胎盘合体滋养层形成的功能基础。（4）利用反义寡核苷酸或RNA干扰平行研究了CD98表面抗原在调节合胞化和氨基酸转运活性中的生理重要性。结果表明，CD98参与了合胞体滋养层形成所必需的细胞融合过程，并且在此生理重要事件期间，氨基酸转运活性也通过该膜蛋白的表达来调节。

(1)A unique biological process of placental trophoblast syncytialisation has been studied using a cell model of syncytialisation (the cytotrophoblast cell line BeWo following increased intracellular cAMP by forskolin).(2)Stable BeWo cell lines constitutively expressing either a fusion protein green fluorescent protein and human histone H2B or a fusion protein of red fluorescent protein and the mitochondrial targeting sequence from subunit VIII of human cytochrome c oxidase have been generated. Using these two BeWo cell lines expressing fluorescent protein of different colour cell fusion (syncytialisation) has been visualized and a fluorescence activated cell sorting based assay for determining quantitatively the rate of syncytialisation has been developed.(3)The time course of syncytialisation has been studied using DNA microarray in a cell model of syncytialisation. Among the genes with increased expression following forskolin treatment were many required for cellular communication and metabolism. Several genes known to be involved in cell adhesion and fusion have markedly changed expression levels very early following forskolin exposure, thus preceding morphological fusion of BeWo cells. Further analysis of this data and expression profiling in general will be able to contribute to understanding the functional basis for the formation of the placental syncytiotrophoblast.(4)The physiological importance of CD98 surface antigen in regulating syncytialisation and amino acid transport activity has been studied in parallel using either antisense oligonucleotides or RNA interference. The results show that CD98 is involved in the process of cell fusion necessary for syncytiotrophoblast formation and that during this physiologically important event amino acid transport activity is also regulated through expression of this membrane protein.