ACAT2-Derived LDL Cholesteryl Esters In Atherosclerosis

ACAT2 衍生的 LDL 胆固醇酯在动脉粥样硬化中的作用

• 批准号: 7537452
• 负责人: Lawrence L Rudel
• 金额: $ 44.14万
• 依托单位: WAKE FOREST UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-15 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7537452
• 关键词: Active Sites; Acyltransferase; Affect; Amino Acids; Arterial Intimas; Atherosclerosis; Back; Bile Acids; Bile fluid; Binding; Biological Assay; Biological Markers; Carotid Arteries; Cell membrane; Cells; Characteristics; Chest; Cholesterol; Cholesterol Esters; Cholesterol Homeostasis; Chylomicrons; Data; Diet; Dietary Cholesterol; Dietary Fats; Duct (organ) structure; Enterocytes; Enzymes; Esterification; Fatty Liver; Fatty acid glycerol esters; Female; Fish Oils; Gene Deletion; Genes; Goals; Hepatic; Hepatocyte; Human; Hypertriglyceridemia; Individual; Intestinal Absorption; Intestines; Lipids; Lipoproteins; Liver; Liver Microsomes; Low-Density Lipoproteins; Lymph; Maintenance; Measurement; Medial; Membrane; Metabolic; Metabolism; Modification; Monitor; Mus; Outcome; Pathway interactions; Patients; Perfusion; Phytosterols; Plasma; Prevention; Principal Investigator; Process; Property; Proteins; Proteoglycan; Proteomics; Reaction; Regulation; Relative (related person); Research; Research Design; Role; Secondary to; Sterols; Surface; Thick; Transgenic Mice; Triad Acrylic Resin; Triglycerides; Very low density lipoprotein; Week; Whole Organism; absorption; atherogenesis; base; cholesterol absorption; cholesteryl oleate; enzyme mechanism; enzyme structure; feeding; inhibitor/antagonist; lipid metabolism; low density lipoprotein inhibitor; male; particle; preference; prevent; programs; protein structure; pyripyropene A; sterol O-acyltransferase 1; sterol O-acyltransferase 2

We have observed that gene deletion and gene knockdown of ACAT2 protects against atherosclerosis when VLDL and LDL in plasma are depleted of ACAT2-derived cholesteryl esters. The goal of the research in project 1 is to define the mechanisms by which ACAT2 affects cholesterol metabolism and atherosclerosis. AIM1. We propose to identify how cholesteryl oleate enrichment of LDL promotes atherogeneisis. We will monitor cholesterol metabolism in the intestine and in the liver. ACAT2 is known to catalyze synthesis of cholesteryl esters for transport into the body in chylomicrons during intestinal cholesterol absorption. AIM2. ACAT2 is an important component helping to regulate the efficiency of intestinal cholesterol absorption and we have designed studies to define the specific contributions of ACAT2 together with ABCG5/G8, a transporter that is known to move cholesterol back out of cells after entry. AIM2. We hope to determine the relative roles of ACAT2 and ABCG5/G8 in facilitating cholesterol absorption while limiting plant sterol absorption. The fate of newly absorbed chylomicron cholesterol, most of which is esterified, is to be efficiently delivered to the liver where the influx of newly absorbed dietary cholesterol provides substrate for many pathways of cholesterol homeostasis. These include secretion into bile, incorporation into the plasma membrane, esterification by ACAT2 resulting in CE that get secreted in VLDL or stored in cytoplasmic lipid droplets within hepatocytes. AIMS. We hope to determine how ACAT2 in the liver directs the outcome of cholesterol handling. During cholesterol feeding, the amount of hepatic CE storage and secretion rises significantly depending on the type of fat in the diet. Paradoxically, when the ACAT2 gene has been deleted, triglyceride secretion in VLDL is increased while triglyceride concentration in the liver is greatly reduced and the levels of cholesterol and cholesteryl ester stored and secreted by the liver remain low, even when dietary cholesterol is fed, effectively preventing hepatic steatosis. The mechanism for this shift in lipid metabolism will be investigated. The data suggest that ACAT2 activity is integral to the metabolic regulation of cholesterol and triglyceride both of which are stored and secreted by the liver. AIM4. Studies on the protein structure and active site of the ACAT2 protein are also proposed. We have identified a putative 'catalytic triad' reaction mechanism for the enzyme and we have identified specific amino acid residues that appear to form the active site. In addition, we have identified the single amino acid residue that appears to interact with the most highly ACAT2-specific inhibitor yet identified, pyripyropene A. AIMS. We have proposed studies to identify whether cholesteryl oleate in human plasma can be a biomarker for ACAT2 activity in patients with CHD. Ultimately we would hope that inhibition of ACAT2 in human beings would become a reality providing prevention of CHD and hepatic steatosis.

我们已经观察到ACAT2的基因缺失和基因敲低可以预防动脉粥样硬化 当血浆中的VLDL和LDL耗尽ACAT2衍生的胆固醇酯时。目标的目标 项目1中的研究是为了定义ACAT2影响胆固醇代谢和的机制 动脉粥样硬化。 AIM1。我们建议确定LDL的胆固醇如何促进 动脉粥样硬化。我们将监测肠和肝脏中的胆固醇代谢。 ACAT2是已知的 催化胆固醇酯的合成，以便在肠道期间进入胆小性的体内 胆固醇吸收。 AIM2。 ACAT2是有助于调节效率的重要组成部分 肠道胆固醇吸收，我们设计了研究以定义 ACAT2与ABCG5/g8一起，一种转运蛋白，已知会在后面移至细胞的转运蛋白 入口。 AIM2。我们希望确定ACAT2和ABCG5/G8在促进胆固醇中的相对作用 吸收同时限制植物固醇吸收。新吸收的乳糜微粒胆固醇的命运，大多数 其中有酯化，应有效地递送到肝脏，在那里新近吸收的饮食 胆固醇为许多胆固醇稳态的途径提供底物。这些包括分泌 进入胆汁，掺入质膜中，通过ACAT2酯化，导致CE 分泌于VLDL或储存在肝细胞内的细胞质脂质液滴中。目标。我们希望确定 肝脏中的ACAT2如何指导胆固醇处理的结果。在胆固醇喂养过程中 肝CE储存和分泌的量显着增加，具体取决于饮食中的脂肪类型。 自相矛盾的是，当删除ACAT2基因时，VLDL中的甘油三酸酯分泌增加，而 肝脏中的甘油三酸酯浓度大大降低，胆固醇和胆固醇的水平 肝脏存储和分泌的肝脏仍保持低，即使饮食胆固醇喂养，有效防止 肝脂肪变性。将研究这种脂质代谢转变的机制。数据建议 ACAT2活性与胆固醇和甘油三酸酯的代谢调节不可或缺 由肝脏储存和分泌。 AIM4。关于ACAT2的蛋白质结构和活性位点的研究 还提出了蛋白质。我们已经确定了推定的“催化三合会”反应机制 酶和我们已经确定了似乎形成活性位点的特定氨基酸残基。在 此外，我们已经确定了似乎与最高度相互作用的单个氨基酸残基 ACAT2特异性抑制剂尚未鉴定出吡吡烯A. Aims。我们提出了研究以识别 人血浆中的胆固醇是否可以成为CHD患者ACAT2活性的生物标志物。 最终，我们希望在人类中抑制ACAT2的抑制作用将成为现实 预防冠心病和肝脂肪变性。