Analysis of Trophoblast Cell Motility

描述(申请人提供)：胚胎植入子宫和随后的胎盘形成是哺乳动物发育的独特和关键特征。它们是由滋养层细胞介导的，滋养层细胞来自胚泡的上皮滋养外胚层细胞。在植入时，它们会转化为侵袭性细胞，取代和吞噬子宫上皮细胞，以穿透子宫间质，并与母体血液供应建立血管连接。上皮性滋养外胚层转变为运动性滋养层细胞，继而转化为内皮滋养层巨细胞，其细胞行为对着床和胎盘的成功，最终对胚胎本身的发育是重要的。然而，我们对这两个转变中涉及的关键细胞事件及其调控的了解仍然相当初级。在这项提议中检验的中心假设是，滋养层细胞运动行为的调节变化是它们在植入和胎盘形成中功能的基础。这些实验主要集中在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层细胞的转化，二是运动性滋养层细胞向滋养层巨细胞的转化。滋养外胚层运动的开始受氨基酸，特别是亮氨酸和精氨酸的调节。这些氨基酸激活的信号机制在调节滋养外胚层突起活动中的作用将被描述，特别是关于一氧化氮和多胺合成的作用。植入后，滋养层细胞在向滋养层巨细胞的终末分化过程中，在卵黄囊胎盘形成错综复杂的血窦吻合网络。这一过程与启动鼻窦形成的运动性和细胞形状的进一步变化以及细胞骨架组织和细胞-细胞黏附的具体变化有关，我们假设这些变化将稳定和加强最终的结构。将研究层粘连蛋白亚型在指导滋养层细胞行为中的作用，以及细胞骨架和粘附性变化在维持其结构中的重要性。这些实验将阐明调控滋养层细胞行为和分化的机制，并将提供对胚胎植入的更深层次的全面了解。

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.