Institute of Cell Biology, Histology and Embryology, Center for Molecular Medicine, Medical University of Graz, 8010, Graz, Austria.
Adv Exp Med Biol. 2011;713:81-95. doi: 10.1007/978-94-007-0763-4_6.
The villous trophoblast of the human placenta is the epithelial cover of the fetal chorionic villi floating in maternal blood. This epithelial cover is organized in two distinct layers, the multinucleated syncytiotrophoblast directly facing maternal blood and a second layer of mononucleated cytotrophoblasts. During pregnancy single cytotrophoblasts continuously fuse with the overlying syncytiotrophoblast to preserve this end-differentiated layer until delivery. Syncytial fusion continuously supplies the syncytiotrophoblast with compounds of fusing cytotrophoblasts such as proteins, nucleic acids and lipids as well as organelles. At the same time the input of cytotrophoblastic components is counterbalanced by a continuous release of apoptotic material from the syncytiotrophoblast into maternal blood. Fusion is an essential step in maintaining the syncytiotrophoblast. Trophoblast fusion was shown to be dependant on and regulated by multiple factors such as fusion proteins, proteases and cytoskeletal proteins as well as cytokines, hormones and transcription factors. In this chapter we focus on factors that may be involved in the fusion process of trophoblast directly or that may prepare the cytotrophoblast to fuse.
人类胎盘的绒毛滋养层是漂浮在母体血液中的胎儿绒毛的上皮覆盖物。这个上皮覆盖物组织成两个不同的层，直接面向母体血液的多核合胞滋养层和第二层单核滋养层细胞。在怀孕期间，单个滋养层细胞不断融合到覆盖的合胞滋养层中，以维持这种终末分化的层直到分娩。合胞融合不断为合胞滋养层提供融合滋养层细胞的化合物，如蛋白质、核酸和脂质以及细胞器。同时，合胞滋养层细胞的输入被不断从合胞滋养层释放到母体血液中的凋亡物质所平衡。融合是维持合胞滋养层的必要步骤。滋养层融合被证明依赖于多种因素，如融合蛋白、蛋白酶和细胞骨架蛋白以及细胞因子、激素和转录因子，并受到这些因素的调节。在本章中，我们重点关注可能直接参与滋养层融合过程的因素，或可能使滋养层细胞准备融合的因素。
