RESPONSE OF ENDOTHELIAL CELLS TO CELL-CELL CONTACT

细胞间的接触对内皮细胞的正常功能起着重要作用。细胞之间的接触不仅起到了密封血管的物理屏障的作用，还改变了这些细胞的解剖结构和生物功能。这些接触性质的异常会导致血管系统的许多病理变化，如癌症转移和肺水肿。虽然已知细胞间的接触随着体内动态局部环境的变化而不断变化，但关于细胞对这些细胞间结合变化的反应知之甚少。目前促进或破坏细胞-细胞接触的体外模型使用的是药理学或机械方法，这些方法在细胞内的反应中引入了混淆的变量，因此不适合于解决细胞-细胞结合和细胞反应之间的因果关系。这项拟议的研究旨在研究内皮细胞对细胞-细胞接触启动的早期(几秒钟到几小时)反应。它假设接触之间的初始接触在决定最终导致细胞-细胞连接形成、细胞内信号传递、细胞骨架锚定和重组以及细胞分化的一系列事件中发挥因果作用。需要研究的行为包括细胞骨架的重排，膜蛋白的重新定位，以及细胞之间最初和随后结合时信号通路的激活。这项研究将开发一种通用的方法，基于细胞附着在其上的微型、独立的底物的自组装，在特定的时间引入物理的细胞-细胞接触，而不改变细胞-基质的相互作用。识别细胞间结合时细胞内发生的事件将有助于加深对正常和病理性血管形成的分子和结构基础的了解，并可能导致开发有效的治疗方法来治疗某些血管疾病。

Cell-cell contacts play an important role in the normal function of endothelial cells. Contacts between cells not only act as a physical barrier that seals the vessel, but also alter the anatomical structure and biological function of these cells. Abnormalities in the nature of these contacts result in many pathologies of the vascular system, such as cancer metastasis and pulmonary edema. While it is known that cell-cell contacts change continually in response to the dynamic local environment in vivo, little is known about the cellular response to these changes in intercellular binding. Current in vitro models that promote or disrupt cell-cell contacts use pharmacologic or mechanical approaches that introduce confounding variables to the intracellular responses, and thus are not suited to address the causal relationship between cell-cell binding and cellular response. The proposed research intends to study the early (seconds to hours) stage response of endothelial cells to initiation of cell-cell contact. It hypothesizes that the initial contact between contacts plays a causal role in determining the sequence of events that ultimately lead to cell-cell junctional formation, intracellular signaling, cytoskeletal anchoring and reorganization, and cell differentiation. The behaviors to be examined are the rearrangement of cytoskeleton, the relocalization of membrane proteins, and the activation of signaling pathways upon the initial and subsequent binding between cells. This research will develop a general methodology based on the self-assembly of microscale, free-standing substrates on which cells are attached, to introduce physical cell-cell contact at specific times and without alteration of cell-matrix interactions. Identification of the events that occur within the cell upon initiation of intercellular binding will help to advance the understanding of the molecular and structural bases of normal and pathologic vessel formation, and may lead to the development of effective therapies to treat certain vascular diseases.