Apoptosis and Trophoblast Fusion

常见的妊娠并发症，如宫内生长受限(IUGR)和流产，与胎盘的异常发育密切相关。胎盘缺陷可能是由外源性环境或母体因素或先天遗传异常引起的。然而，我们对宫内发育迟缓或流产的细胞学基础的理解受阻于我们对 正常的胎盘发育过程。我们认识到，正常的胎盘发育依赖于绒毛细胞滋养层细胞的分化，最终细胞间融合为胎盘表面扩张的合体滋养层细胞。合胞化涉及几个过程，特别是细胞增殖的停止，质膜磷脂的重新分布形成富含磷脂酰丝氨酸(PS)的外表面，融合蛋白的表达和插入质膜，以及肌动蛋白细胞骨架元件的重排。我们的初步数据显示 一些与细胞凋亡相关的蛋白，特别是caspase3、8和14，可能是滋养层细胞分化的关键参与者。本研究的目的是探讨半胱氨酸天冬氨酸氨基转移酶在绒毛细胞滋养层细胞分化中的作用。我们将使用原代绒毛细胞滋养层细胞培养和BeWo绒毛膜癌模型。利用多肽抑制剂和基因沉默，我们将确定caspase3、8和14在合胞化过程的各个组成部分(PS外流、G1期停滞、细胞骨架重排、融合蛋白表达、hCG产生)中的作用。更多的研究将评估通过核因子κB的信号转导的作用。这项研究的最终目标是 确定控制绒毛细胞滋养细胞分化机制的关键成分。不明原因的宫内发育迟缓和流产是导致婴儿死亡或新生儿严重受损的常见并发症，需要在新生儿重症监护病房进行广泛护理。通过这项研究获得的信息，我们可以开始调查可能解释IUGR或流产的胎盘缺陷，从而设计诊断测试或干预措施来降低这些并发症的风险。

Common pregnancy complications, such as intrauterine growth restriction (IUGR) and miscarriage, are strongly associated with abnormal development of the placenta. Defective placentation may result from exogenous environmental or maternal factors or from inborn genetic anomalies. However, our understanding of the cellular basis of IUGR or miscarriage is blocked by our ignorance about the process of normal placental development. We are cognizant that normal human placental development is dependent on differentiation of the villous cytotrophoblast culminating in intercellular fusion into the expanding syncytiotrophoblast on the placental surface. Syncytialization involves several processes, particularly cessation of cellular proliferation, redistribution of plasma membrane phospholipids to form a phosphatidylserine (PS)-rich exofacial surface, expression and insertion of fusion proteins into the plasma membrane, and rearrangement of actin cytoskeletal elements. Our preliminary data suggest that several apoptosis-related proteins, particularly caspases 3, 8, and 14, may be critical participants in trophoblast differentiation. The aim of this application is to investigate the role of these caspases in villous cytotrophoblast differentiation. We will use both primary villous cytotrophoblast cultures and a BeWo choriocarcinoma model. Using peptide inhibitors and gene silencing, we will determine the role of caspases 3, 8, and 14 in individual components of the syncytialization process (PS efflux, G1 arrest, cytoskeletal rearrangement, fusion protein expression, hCG production). Additional studies will evaluate the role of signal transduction through NFκB. The ultimate goal of this investigation is to identify the critical components controlling the mechanism of villous cytotrophoblast differentiation. Unexplained IUGR and miscarriage are common complications that lead to death of a child or to a severely compromised newborn requiring extensive care in newborn intensive care units. With the information obtained through this research, we can begin to investigate the placental defects that may explain IUGR or miscarriage, and thereby design diagnostic tests or interventions to decrease the risk of these complications.