Institute of Cell Biology, Histology and Embryology, Center for Molecular Medicine, Medical University of Graz, Austria.
Placenta. 2010 Feb;31(2):82-8. doi: 10.1016/j.placenta.2009.12.007. Epub 2009 Dec 30.
Differentiation and subsequent fusion of villous cytotrophoblasts with the overlying syncytiotrophoblast is an essential process for growth and maintenance of the villous trophoblast layer in the human placenta. The understanding of intrinsic mechanisms behind this process is in its infancy, while the list of suggested factors, involved in intercellular fusion of trophoblasts, rapidly increased in the recent past and promises progress on this issue. The early stages of the apoptosis cascade, in particular caspase 8, was suggested to trigger differentiation of cytotrophoblasts, priming them for upcoming fusion. This may sound paradoxical, especially for those who still associate caspase activity with apoptosis only. Here, we summarize data on caspase 8 in the villous trophoblast layer, with a specific focus on localization of pro- and active forms, the sites of its activation and deactivation, and its role and regulation during fusion. Moreover, we revisit the knowledge on fusogens in the villous trophoblast, compare in vitro models for trophoblast fusion and discuss methods to quantify fusion.
绒毛滋养细胞的分化和随后与覆盖的合体滋养层融合是人类胎盘绒毛滋养层生长和维持的必要过程。尽管最近内在机制的研究仍处于起步阶段，但参与滋养细胞细胞间融合的因子的列表迅速增加，并有望在这个问题上取得进展。凋亡级联反应的早期阶段，特别是半胱天冬酶 8，被认为触发滋养细胞的分化，为即将发生的融合做好准备。这听起来可能有些矛盾，尤其是对于那些仍然将半胱天冬酶活性与凋亡联系在一起的人。在这里，我们总结了绒毛滋养层中半胱天冬酶 8 的相关数据，特别关注其前体和活性形式的定位、激活和失活的部位，以及其在融合过程中的作用和调节。此外，我们重新审视了绒毛滋养层中融合素的知识，比较了滋养细胞融合的体外模型，并讨论了融合的定量方法。
