Regulation of leukocyte recruitment and endothelial functions by LSP1-mediated protein-protein interactions

炎症是身体对感染或损伤的反应。在炎症过程中，白细胞(白细胞)和内皮细胞之间存在复杂的相互作用，内皮细胞排列在血管壁上。白细胞特异性蛋白1(LSP1)是白细胞和内皮细胞中的一种信号分子。它在白细胞与内皮细胞的相互作用中起着重要作用。当发生炎症时，LSP1被激活，调节血管壁的通透性，在不同的间隔内移动，并可以与细胞中的许多其他蛋白质相互作用。我们的研究发现了明确的生物学证据：(1)内皮细胞LSP1可以附着到另一种名为SUMO1的小而短的蛋白质上，即LSP1被SUMO1翻译后修饰；(2)当发生炎症时，内皮细胞LSP1与细胞内支架蛋白Ezrin-Radisin-moesin(ERM)和F-actiins相互作用；以及(3)在动脉血管，内皮细胞LSP1与一种名为eNOS的内皮蛋白相互作用，调节与血压调节相关的内皮功能。我们假设内皮LSP1与内皮细胞中的SUMO1、ERM和eNOS蛋白相互作用，从而调节多种内皮功能，包括白细胞-内皮相互作用、血管通透性变化和血压调节。*首先，我们将利用培养的内皮细胞和许多生物学技术来证实LSP1确实被SUMO1连接(即翻译后修饰)，以维持LSP1‘S在内皮细胞中的稳定性和功能。其次，我们将提供强有力的科学证据，证明当内皮细胞被激活时，内皮细胞LSP1与ERM蛋白相互作用，从而调节炎症中白细胞的跨内皮细胞迁移和血管通透性增加。我们还将在显微镜下观察LSP1与SUMO1和ERM相互作用的图像。第三，我们将验证LSP1缺乏会导致缺乏LSP1的小鼠的高血压。我们拥有专业技术和设备来测量和比较缺乏LSP1的小鼠和有LSP1的对照小鼠分离的动脉血管的收缩和松弛反应。同样利用培养的内皮细胞，我们将确定LSP1和eNOS之间的物理和功能相互作用。这项研究将增加我们对LSP1与SUMO1、ERM和eNOS相互作用机制的科学认识，并揭示这些相互作用的重要功能。

Inflammation is the body's response to infection or injury. During inflammation, there are complex interactions between the white blood cells (leukocytes) and endothelial cells, the cells lining the blood vessel wall. Leukocyte-specific protein 1 (LSP1) is a signaling molecule in leukocytes and endothelial cells. It has an important role in leukocyte-endothelial interactions. When there is an inflammation, LSP1 becomes activated, regulates the permeability of the blood vessel wall, moves in different compartments and can interact with many other proteins in cells. Our research have found clear, biological evidence that, (1) endothelial cell LSP1 can attach to another small and short protein called SUMO1, i.e., LSP1 is post-translationally modified by SUMO1; (2) when there is an inflammation, endothelial LSP1 interacts with intracellular scaffold proteins ezrin-radixin-moesin (ERM) and F-actins; and (3) at arterial blood vessels, endothelial LSP1 interacts with an endothelial protein called eNOS and regulates endothelial functions that are related to blood pressure regulation. We hypothesize that endothelial LSP1 interacts with SUMO1, ERM and eNOS proteins in endothelial cells and by doing so regulates multiple endothelial functions, including leukocyte-endothelial interactions, blood vessel permeability changes and blood pressure regulation. ******Firstly, we will use cultured endothelial cells and many biological techniques to establish that LSP1 is indeed attached (i.e., post-translationally modified) by SUMO1 for maintaining LSP1's stability and functions in endothelial cells. Secondly, we will provide strong scientific evidence that endothelial LSP1 interacts with ERM proteins when endothelial cells are activated and thereby regulates trans-endothelial migration of leukocytes and blood vessel permeability increases in inflammation. We will also watch under microscope the images of LSP1 interacting with SUMO1 and ERM. Thirdly, we will verify that LSP1-deficiency causes hypertension in the mice lacking LSP1. We have the expertise and equipment to measure and compare the contraction and relaxation responses of arterial vessels isolated from the mice lacking LSP1 and control mice having LSP1. Also using cultured endothelial cells, we will determine physical and functional interactions between LSP1 and eNOS. This study will add our scientific knowledge on the mechanisms of LSP1 interacting with SUMO1, ERM and eNOS and reveal important functions of these interactions.