Role of Shear-Sensitive Protein HEG1 in Endothelial Biology and Atherosclerosis

项目总结/摘要 动脉粥样硬化是指动脉壁脂肪斑块的形成，是心脏病发作的基础， 中风是美国和国外最致命的两起医疗事件。一般来说，必须满足两个标准， 为了在给定的动脉中发展动脉粥样硬化：1）动脉必须暴露于高水平的循环中， 胆固醇和脂质，以及2）动脉通常必须位于动脉的弯曲或分支区域中， 血管系统，其中动脉壁的内皮细胞经历低幅度和振荡剪切 血流紊乱造成的压力尽管许多不同的降胆固醇和降脂药物被广泛使用， 预防动脉粥样硬化、心脏病发作和中风的药物仍然是两大杀手 在美国.因此，开发靶向不同机制的药物变得越来越重要。 动脉粥样硬化形成，如内皮细胞对血流紊乱的反应。目前的研究解决了这个问题， 研究流动敏感性蛋白质玻璃心脏同源物1（HEG 1）在内皮功能中的作用， 动脉粥样硬化HEG 1是一种内皮富集的单程跨膜糖蛋白， 对血管发育和完整性至关重要。最近，我们的实验室发现，HEG 1是 在暴露于干扰流的内皮细胞中下调，在暴露于干扰流的内皮细胞中上调。 稳定流动。这一结果在RNA和蛋白质水平，在体外和体内，在人和动物中得到了证实。 小鼠内皮细胞最近的一份出版物证明了斑马鱼的类似结果。因为明显的剪切- HEG 1的敏感性及其在血管发育和完整性中的重要性，我们假设 HEG 1对血流紊乱的反应性下调导致内皮功能障碍， 动脉粥样硬化的发展。为了验证这一假设，我们提出了两个目标：1）确定的作用， HEG 1在内皮功能障碍中的作用; 2）确定HEG 1在动脉粥样硬化发病机制中的作用。 为了解决Aim 1，HEG 1将在人主动脉内皮细胞中过表达并被敲低，并且这些细胞将在人主动脉内皮细胞中表达。 将在一系列测试常见内皮功能如渗透性的实验中评估细胞， 炎症和迁移。随后将进行机制研究，以准确描述 HEG 1如何参与内皮功能。为了解决目标2，将在小鼠中敲除HEG 1，并且 这些小鼠将经受我们的部分颈动脉结扎、流动诱导的动脉粥样硬化模型。标志物 将在这些小鼠中研究内皮功能障碍和动脉粥样硬化 内皮细胞HEG 1表达对疾病发病机制的影响。实现这些目标将有助于了解 HEG 1下调内皮细胞暴露于干扰流，并提供了一种新的机制，以靶向 动脉粥样硬化的治疗。

Project Summary/Abstract Atherosclerosis refers to the formation of fatty plaques in the arterial wall that underlie heart attacks and strokes, two of the deadliest medical events in the US and abroad. In general, two criteria must be met in order to develop atherosclerosis in a given artery: 1) the artery must be exposed to high levels of circulating cholesterol and lipids, and 2) the artery must typically be located in a curved or branching region of the vasculature, in which endothelial cells of the arterial wall experience low-magnitude and oscillatory shear stress from disturbed blood flow. Despite the widespread use of many different cholesterol- and lipid-lowering medications in the prevention of atherosclerosis, heart attacks and strokes have remained two of the top killers in the US. As such, it has become increasingly important to develop drugs that target different mechanisms of atherogenesis, like endothelial responses to disturbed blood flow. The current study addresses this problem by investigating the role of the flow-sensitive protein heart of glass homolog 1 (HEG1) in endothelial function and atherosclerosis. HEG1 is an endothelial-enriched single-pass transmembrane glycoprotein that has been shown to be essential for vascular development and integrity. Recently, our laboratory found that HEG1 is downregulated in endothelial cells exposed to disturbed flow and upregulated in endothelial cells exposed to stable flow. This result was confirmed at both the RNA and protein level, in vitro and in vivo, in both human and mouse endothelial cells. A recent publication demonstrated a similar result in zebrafish. Due to the clear shear- sensitivity of HEG1 and its demonstrated importance in vascular development and integrity, we hypothesize that downregulation of HEG1 in response to disturbed flow causes endothelial dysfunction, which contributes to the development of atherosclerosis. To test this hypothesis, we propose two aims: 1) to determine the role of HEG1 in endothelial dysfunction, and 2) to determine the role of HEG1 in the pathogenesis of atherosclerosis. To address Aim 1, HEG1 will be overexpressed and knocked down in human aortic endothelial cells, and these cells will be assessed in a series of experiments testing common endothelial functions such as permeability, inflammation, and migration. Mechanistic studies will subsequently be performed in order to describe exactly how HEG1 is involved in endothelial function. To address Aim 2, HEG1 will be knocked down in mice, and these mice will be subjected to our partial carotid ligation, flow-induced atherosclerosis model. Markers of endothelial dysfunction and atherosclerosis will be studied in these mice in order to assess the effects of endothelial HEG1 expression on disease pathogenesis. Addressing these aims will shed light on the effects of HEG1 downregulation in endothelial cells exposed to disturbed flow and provide a novel mechanism to target in the treatment of atherosclerosis.