Dichotomous Role of Endothelial SR-BI in Atherosclerosis

内皮 SR-BI 在动脉粥样硬化中的二分作用

基本信息

批准号：
9235634
负责人：
PHILIP W SHAUL
金额：
$ 40.5万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-12-12 至 2020-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9235634
关键词：
Adaptor Signaling Protein Address Adhesions Affect Anti-Inflammatory Agents Anti-inflammatory Aorta Apolipoprotein A-I Apolipoprotein E Arteries Atherosclerosis Attenuated Binding Blood Blood Vessels Breeding C-terminal Cardiovascular Diseases Cardiovascular system Cell Culture Techniques Cell Line Cell membrane Cells Cholesterol Complex Confocal Microscopy Deposition Development Disease Electron Microscopy Endothelial Cells Endothelium Enterobacteria phage P1 Cre recombinase Foam Cells Gene Expression Genes Health Hepatocyte High Density Lipoprotein Cholesterol High Density Lipoproteins Human Infiltration Inflammation Injectable Injection of therapeutic agent Intervention Knowledge LDL Cholesterol Lipoproteins Label Leukocytes Lipids Liver Low Density Lipoprotein Receptor Low-Density Lipoproteins LoxP-flanked allele Lymphatic Lymphatic Endothelium Lymphocyte Mediating Mediation Modeling Movement Mus Nitric Oxide Synthase Peripheral Pharmacology Phosphotransferases Process Production Proteins Research Role SR-BI receptor Signal Transduction Skin Tail Testing Tissues Transgenic Organisms Very low density lipoprotein atherogenesis atheroprotective cadherin 5 cardiovascular health endothelial cell scavenger receptor foot high density lipoprotein receptor high density lipoprotein-2 in vivo in vivo Model intravital microscopy loss of function macrophage mutant novel novel therapeutics oxidation oxidized low density lipoprotein programs promoter receptor repaired reverse cholesterol transport trafficking transcytosis uptake vascular inflammation

项目摘要

Project Summary/ Abstract Differences in both high density lipoprotein (HDL) cholesterol abundance and function likely impact the cardiovascular protective potential of HDL. HDL classically mediates reverse cholesterol transport (RCT) to the liver via processes that include the binding of apolipoprotein A-I (apoA-I) in HDL to scavenger receptor class B, type I (SR-BI) in hepatocytes. Other actions of the HDL/SR-BI tandem may also be protective, such as their capacity to activate endothelial NO production and repair via kinase signaling that uniquely requires the adaptor protein PDZK1. However, we surprisingly discovered that endothelial- specific SR-BI deletion in apoE-/- mice, which have high VLDL/LDL and low HDL, results in decreased atherosclerosis. We have further discovered that this is related to a >80% decline in LDL delivery to the artery wall, revealing the mechanism underlying a critical step in atherogenesis. As such, there may be a dichotomous role for endothelial SR-BI in atherosclerosis, promoting it in the setting of low HDL yet affording atheroprotection in the setting of high HDL. This novel concept and its mechanistic underpinnings will be interrogated in mice and in human endothelial cells. Aim 1 is to compare how endothelial SR-BI influences atherosclerosis in the setting of relatively low vs. high HDL. Atherosclerosis will be evaluated with vs. without endothelial SR-BI and HDL raised via transgenic expression of human apoA-I, and findings will be compared with those made with low HDL. The impact of endothelial SR-BI signaling on atherosclerosis will also be evaluated at low vs. high HDL by deleting endothelial PDZK1. Aim 2 is to determine the roles of endothelial SR-BI and PDZK1 in the putative atheroprotective actions of HDL. To assess HDL's anti-inflammatory actions in vivo, endothelial cell-leukocyte adhesion will be evaluated by intravital microscopy, and HDL, SR-BI and PDZK1 modulation of endothelial genes that influence vascular inflammation will also be interrogated. The roles of endothelial SR-BI and PDZK1 in RCT will be determined in models that query processes in both blood and lymphatic endothelium, and in both microvasculature and arteries. Aim 3 is to determine how endothelial SR-BI governs artery wall LDL deposition. LDL uptake will be studied in cultured endothelium expressing mutant forms of SR-BI with specific loss-of-function for lipid flux, sensing of plasma membrane cholesterol movement, or C-terminal protein interaction. Further studies in culture will evaluate possible roles of other LDL receptors, and co- trafficking of LDL and SR-BI across the endothelium. Aorta LDL uptake will be evaluated in vivo in models testing the role of PDZK1, the impact of elevated HDL, and if pharmacologic intervention targeting SR-BI can decrease LDL deposition. By accomplishing these aims, we will elucidate how vascular health is influenced by endothelial SR-BI, which may be a critical point of intersection of atherosclerosis modulation by HDL and LDL. The new knowledge gained will potentially identify novel therapies for atherosclerosis.

项目概要/摘要高密度脂蛋白（HDL）胆固醇丰度和功能的差异可能会影响 HDL 的心血管保护潜力。 HDL 通常介导胆固醇逆向转运 (RCT) 通过 HDL 中的载脂蛋白 A-I (apoA-I) 与清除剂结合等过程到达肝脏肝细胞中的 B 类受体 I 型 (SR-BI)。 HDL/SR-BI 串联的其他作用也可能是保护性，例如它们通过激酶信号激活内皮 NO 产生和修复的能力唯一需要接头蛋白 PDZK1。然而，我们惊奇地发现，内皮细胞具有高 VLDL/LDL 和低 HDL 的 apoE-/- 小鼠中特异性 SR-BI 缺失会导致动脉粥样硬化。我们进一步发现，这与 LDL 输送量下降超过 80% 有关。动脉壁，揭示动脉粥样硬化形成关键步骤的机制。因此，可能有一个内皮 SR-BI 在动脉粥样硬化中的二分作用，在低 HDL 的情况下促进动脉粥样硬化在高 HDL 的情况下提供动脉粥样硬化保护。这个新颖的概念及其机制基础将在小鼠和人类内皮细胞中进行研究。目标 1 是比较如何在 HDL 相对较低和较高的情况下，内皮 SR-BI 会影响动脉粥样硬化。动脉粥样硬化将使用与不使用通过人类转基因表达产生的内皮 SR-BI 和 HDL 进行评估 apoA-I，并将结果与低 HDL 的结果进行比较。内皮SR-BI的影响还将通过删除内皮 PDZK1 来评估低 HDL 与高 HDL 时动脉粥样硬化的信号传导。目标 2 是确定内皮 SR-BI 和 PDZK1 在假定的动脉粥样硬化保护作用中的作用高密度脂蛋白。为了评估 HDL 的体内抗炎作用，将检测内皮细胞-白细胞粘附通过活体显微镜评估，以及 HDL、SR-BI 和 PDZK1 对内皮基因的调节血管炎症的影响也将受到质疑。内皮SR-BI和PDZK1的作用 RCT 将在查询血液和淋巴内皮细胞过程的模型中确定，并在微血管和动脉。目标 3 是确定内皮 SR-BI 如何控制动脉壁 LDL 沉积。将在表达 SR-BI 突变体形式的培养内皮细胞中研究 LDL 摄取脂质流动、质膜胆固醇运动感知或 C 末端的特定功能丧失蛋白质相互作用。进一步的培养研究将评估其他 LDL 受体的可能作用，并共同 LDL 和 SR-BI 穿过内皮的运输。主动脉 LDL 摄取将在模型中进行体内评估测试 PDZK1 的作用、HDL 升高的影响以及是否针对 SR-BI 进行药物干预可以减少低密度脂蛋白沉积。通过实现这些目标，我们将阐明血管健康如何受内皮SR-BI影响，这可能是动脉粥样硬化调节的关键交叉点由高密度脂蛋白和低密度脂蛋白组成。获得的新知识将有可能确定动脉粥样硬化的新疗法。