Analysis of Trophoblast Cell Motility

描述（由申请人提供）：胚胎植入子宫并随后形成胎盘是哺乳动物发育的独特和关键特征。它们由滋养层细胞介导，滋养层细胞由胚泡的上皮性滋养外胚层细胞产生。在植入时，它们转化为侵袭性细胞，取代并吞噬子宫上皮细胞，以穿透子宫间质，与母体血液供应建立血管连接。上皮性滋养外胚层转化为可运动的滋养细胞并随后转化为内皮性滋养细胞巨细胞的相关细胞行为对着床和胎盘的成功以及最终对胚胎本身的发育至关重要。然而，我们对涉及这两种转变的关键细胞事件及其调控的理解仍然相当初级。本研究的中心假设是，滋养细胞运动行为的调控变化是其着床和胎盘功能的基础。拟开展的实验主要关注滋养层巨细胞分化的两个方面：一是上皮性滋养外胚层向运动性滋养细胞的转变，二是运动性滋养细胞向滋养层巨细胞的转变。在滋养外胚层的运动的开始是由氨基酸的可用性，特别是亮氨酸和精氨酸调节。这些氨基酸激活的信号机制在调节滋养外胚层突起活动的功能将被表征，特别是关于一氧化氮和多胺合成的作用。滋养细胞着床后，经过向滋养细胞巨细胞的终末分化，形成卵黄囊胎盘血窦的复杂吻合网。这个过程与运动和细胞形状的进一步变化有关，从而启动鼻窦的形成，以及细胞骨架组织和细胞-细胞粘附的特定变化，我们假设这些变化将稳定和加强最终结构。层粘连蛋白异构体在指导滋养细胞行为中的作用，以及细胞骨架和粘附变化在维持其结构中的重要性将被检查。这些实验将阐明滋养细胞行为和分化的调控机制，为胚胎着床提供更深入的整体认识。

DESCRIPTION (provided by applicant): Implantation of the embryo into the uterus and subsequent formation of the placenta are unique and critical features of mammalian development. They are mediated by the trophoblast cells, which arise from the epithelial trophectoderm cells of the blastocyst. At the time of implantation they transform into invasive cells that displace and phagocytose the uterine epithelial cells in order to penetrate the uterine stroma and make vascular connections with the matemal blood supply. The cellular behaviors associated with the transformation of the epithelial trophectoderm into a motile trophoblast and subsequently to an endothelial trophoblast giant cell are important for the success of implantation and placentation and ultimately for the development of the embryo itself. However our understanding of the key cellular events involved in these two transitions, and of their regulation, is still quite rudimentary. The central hypothesis being tested in this proposal is that regulated changes in the motile behavior of trophoblast cells are the basis for their function in implantation and placentation. The proposed experiments focus on two aspects of trophoblast giant cell differentiation: first, the transition of epithelial trophectoderm to motile trophoblast, and second, the transition from motile trophoblast-to-trophoblast giant cell. The onset of motility in the trophectoderm is regulated by the availability of amino acids, in particular leucine and arginine. The functions of the signaling mechanisms activated by these amino acids in regulating the onset of protrusive activity of the trophectoderm will be characterized, especially with respect to the roles of nitric oxide and polyamine synthesis. After implantation, trophoblast cells form the intricate anastomotic network of blood sinuses of the yolk sac placenta as they undergo terminal differentiation to trophoblast giant cells. This process is associated with further changes in motility and cell shape to initiate the formation of the sinuses, as well as specific changes in cytoskeletat organization and cell-cell adhesion, which we hypothesize will stabilize and reinforce the final structure. The roles of laminin isoforms in directing trophoblast behavior, and the importance of cytoskeletal and adhesive changes in maintaining their structure will be examined. These experiments will clarify the mechanisms regulating trophoblast cell behavior and differentiation, and will provide a deeper overall understanding of embryo implantation.