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

项目摘要/摘要 动脉粥样硬化是指动脉壁中脂肪斑块的形成，这些斑块是心脏病发作和 中风，美国和国外最致命的两起医疗事件。一般而言，必须满足两个标准 要在特定的动脉中形成动脉粥样硬化：1)该动脉必须暴露在高水平的血液循环中 胆固醇和脂类，以及2)动脉通常必须位于动脉的弯曲或分支区域 血管系统，其中动脉壁内皮细胞经历低幅度和振荡剪切 由于血液流动紊乱而产生的压力。尽管许多不同的降胆固醇和降血脂药物被广泛使用 预防动脉粥样硬化、心脏病发作和中风的药物仍然是头号杀手。 在美国。因此，开发针对不同机制的药物变得越来越重要。 动脉粥样硬化，就像血管内皮细胞对血流紊乱的反应一样。目前的研究通过以下方式解决了这个问题 探讨玻璃同系物1(HEG1)对血管内皮细胞功能和功能的影响 动脉硬化。HEG1是一种内皮丰富的单程跨膜糖蛋白，已被 被证明对血管发育和完整性是必不可少的。最近，我们实验室发现HEG1是 在受到干扰的血流中内皮细胞表达下调，在暴露于受干扰血流的内皮细胞中上调 稳定的流动。这一结果在体外和体内的RNA和蛋白质水平上都得到了证实，在人类和 小鼠内皮细胞。最近的一篇论文在斑马鱼身上展示了类似的结果。由于有明显的切变- 我们假设HEG1的敏感性及其在血管发育和完整性中的重要性 HEG1对血流紊乱的反应下调会导致内皮功能障碍，这在 与动脉粥样硬化的发展有关。为了验证这一假设，我们提出了两个目标：1)确定 HEG1在内皮功能障碍中的作用；2)确定HEG1在动脉粥样硬化发病机制中的作用。 为了解决目标1，HEG1将在人的主动脉内皮细胞中过表达并被下调，这些 细胞将在一系列测试常见内皮功能的实验中进行评估，如通透性， 炎症和迁移。随后将进行机理研究，以便准确地描述 HEG1是如何参与内皮功能的。为了解决目标2，HEG1将在小鼠身上被击倒，并且 这些小鼠将受到我们的部分颈动脉结扎，血流诱导的动脉粥样硬化模型的影响。标记： 将在这些小鼠身上进行内皮功能障碍和动脉粥样硬化的研究，以评估 内皮细胞HEG1表达在疾病发病机制中的作用解决这些目标将有助于阐明 干扰血流对内皮细胞HEG1表达下调及靶向作用机制的研究 在治疗动脉粥样硬化方面。

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.