Trophoblast Intercellular Fusion

描述(由申请者提供)：胎盘的生长是人类成功怀孕的关键。人类胎盘的表面是由合体滋养层细胞形成的，合体滋养层细胞是一种大的多核高度分化的细胞，负责将营养物质从母体循环输送到胎儿循环。合体滋养细胞本质上是合体滋养细胞，不会增殖，也不会独立增大细胞大小。胎盘表面的生长依赖于增殖绒毛细胞滋养层和合体滋养层之间的持续细胞间融合。某些形式的妊娠丢失和宫内生长受限(IUGR)是由于干扰滋养层细胞间融合造成的。然而，大多数复发性妊娠丢失和IUGR的机制尚不清楚。可以合理地预测，细胞间融合缺陷可能是其他形式的妊娠丢失或IUGR的潜在原因。很难研究这一假说，因为滋养层细胞融合的具体过程还没有被很好地理解。许多研究人员的工作表明，滋养层细胞间的融合依赖于质膜上的三个变化：多个细胞间黏附蛋白的外化，一个或多个融合蛋白的表达，以及氨基磷脂的外流。已经研究了与融合相关的质膜蛋白的一些具体变化，尽管这是以零碎的方式完成的。没有与细胞间融合相关的相关质膜蛋白的总变化的信息。这个R21应用程序旨在利用亚细胞蛋白质组学获得与合体滋养层细胞融合相关的质膜变化的全球信息。从研究质膜蛋白质组变化中获得的数据将通过全细胞蛋白质组学、免疫组织学、蛋白质印迹分析和其他技术得到证实。融合相关质膜蛋白的转录将用定量RT-PCR进行研究。这一提议之外的后续研究将确定单个蛋白质在细胞间融合过程中的重要性。这些研究将首次确定滋养层细胞间融合所必需的质膜蛋白家族，并为未来与反复妊娠丢失和IUGR相关的这些蛋白表达变化的研究奠定基础。公共卫生相关性：尽管细胞滋养细胞之间的细胞间融合对于人类胎盘的正常生长和功能是必不可少的，但人们对这一过程中导致妊娠丢失或宫内生长迟缓的正常过程和异常情况知之甚少。这项建议使用最先进的技术，如亚细胞蛋白质组学，来表征正常的细胞间融合过程，并为广泛研究融合缺陷可能引起的妊娠并发症提供基础。

DESCRIPTION (provided by applicant): Growth of the placenta is essential for a successful human pregnancy. The surface of the human placenta is formed by the syncytiotrophoblast, which is a large multinucleate highly differentiated cell that is responsible for transport of nutrients from the maternal to fetal circulations. Being syncytial in nature, the syncytiotrophoblast does not proliferate and does not independently increase cell size. The growth of the placental surface is dependent on continuous intercellular fusion between the underlying proliferative villous cytotrophoblast layer and the syncytiotrophoblast. Some forms of pregnancy loss and intrauterine growth restriction (IUGR) result from interference with intertrophoblast fusion. However, the mechanism underlying most cases of recurrent pregnancy loss and IUGR is unknown. It would be reasonable to predict that defective intercellular fusion may be the underlying cause of other forms of pregnancy loss or IUGR. It is difficult to investigate this hypothesis because the specific process by which trophoblast fuse is not well understood. From the work of many investigators it appears that intertrophoblast fusion is dependent on three changes in the plasma membrane: the externalization of multiple intercellular adhesion proteins, the expression of one or more fusion proteins, and efflux of aminophospholipids. A few specific changes in fusion-related plasma membrane proteins have been investigated, although this has been done in a piece-meal fashion. There is no information on the total change in relevant plasma membrane proteins related to intercellular fusion. This R21 application is designed to obtain global information about plasma membrane changes related to syncytiotrophoblast fusion using subcellular proteomics. The data obtained from studying changes in the plasma membrane proteome will be confirmed using whole cell proteomics, immunohistology, Western blot analysis, and other techniques. The transcription of fusion- related plasma membrane proteins will be investigated using quantitative RT-PCR. Later studies beyond this proposal will ascertain the importance of individual proteins to the intercellular fusion process. These studies will, for the first time, identify a family of plasma membrane proteins that are essential for intertrophoblast fusion and form the basis for future studies on alterations of the expression of these proteins related to recurrent pregnancy loss and IUGR. PUBLIC HEALTH RELEVANCE: Although intercellular fusion between cytotrophoblast cells is essential for normal growth and function of the human placenta, the normal process and aberrations in that process leading to pregnancy loss or intrauterine growth retardation are understood very little. This proposal uses state-of-the-art techniques, such as subcellular proteomics, to characterize the normal intercellular fusion process and provide a foundation for extensive investigations of pregnancy complications that may arise from defective fusion.