Vascular Lipolysis: A Determinant of Atherosclerosis

血管脂肪分解：动脉粥样硬化的决定因素

• 批准号: 6779804
• 负责人: David Yiu-Kwan Hui
• 金额: $ 38.25万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6779804
• 关键词: atherosclerosis; carboxylic ester hydrolases; ceramides; dietary lipid; gene expression; genetic polymorphism; genetic screening; genetic strain; genetic susceptibility; genetically modified animals; isozymes; laboratory mouse; lipase; lipid metabolism; lipolysis; low density lipoprotein; low density lipoprotein receptor; lysolecithins; molecular pathology; nutrition related tag; oxidized lipid; pathogenic diet; site directed mutagenesis; vascular endothelium

DESCRIPTION (provided by applicant): Recent studies have clearly documented the importance of phospholipid and sphingolipid metabolites in atherosclerosis and vascular biology. While enzymes responsible for phospholipid and sphingomyelin hydrolysis in the vessel wall have been identified and were shown to contribute to atherogenesis, enzyme(s) responsible for lowering the level of their hydrolytic products, the bioactive lysophosphatidylcholine (LysoPC) and ceramide, have not been characterized to date. Results generated from this laboratory revealed the presence of the pancreatic-type carboxyl ester lipase (CEL) in human vascular wall. This protein is synthesized by aortic endothelial cells and monocyte-derived macrophages in a manner inducible by oxidized LDL (oxLDL). Importantly, CEL displayed avid bile salt-independent lysoPC and ceramide hydrolytic activities. Human CEL is also highly polymorphic, encoding proteins varying in the number of proline-rich repeating units at the carboxyl terminus. Based on these novel observations, this application proposes to test the following hypotheses: (1) CEL expression in the vasculature is an inflammatory response mechanism that protects early stages of atherogenesis by hydrolyzing and reducing the atherogenic properties of lysoPC and ceramide; (2) the number of proline-rich repeating units in the C-terminus of CEL is important in determining its ability to hydrolyze lysoPC and ceramide; and (3) CEL gene polymorphism is a determinant of individual susceptibility to modified-LDL mediated atherogenic events. These hypotheses viii be tested by experiments under 3 specific aims. Specific Aim 1 plans to produce vascular-specific CEL transgenic mice to evaluate the impact of vascular CEL gene expression on initiation and progression of the atherosclerotic plaque. Specific Aim 2 will use site-directed mutagenesis approach to test the hypothesis that the number of proline-rich repeating units at its C-terminus is an important determinant of lysoPC and ceramide hydrolytic activities of CEL, and thus the effectiveness of different CEL isoforms in protecting vascular cells against lysoPC- and ceramide-induced atherogenic events. Specific Aim 3 will identify the mechanism by which modified LDL induces CEL gene expression in human macrophages and endothelia cells. Experiments will be designed to test the hypothesis that CEL gene activation is mediated via signal transduction mechanisms as a consequence of oxLDL binding to scavenger receptors on the cell surface, or alternatively requires the internalization of specific lipid constituents associated with oxidized lipoproteins. Taken together, these studies will identify novel factors that contribute to determining atherosclerosis susceptibility. Genetic screening strategy may also be designed to identify subjects predispose to atherosclerosis for early intervention and reducing their risk of developing this disease.

描述（由申请人提供）：最近的研究清楚地记录了 磷脂和鞘脂代谢物在动脉粥样硬化中重要性 血管生物学而负责磷脂和鞘磷脂的酶 已经确定了血管壁中的水解，并显示出有助于 与动脉粥样硬化形成有关，负责降低其 水解产物，生物活性溶血磷脂酰胆碱（LysoPC）和 神经酰胺，迄今尚未被表征。由此产生的结果 实验室揭示了胰腺型羧基酯脂肪酶的存在 (CEL)在人体血管壁中。该蛋白由主动脉内皮细胞合成 细胞和单核细胞衍生的巨噬细胞以氧化LDL诱导的方式 （oxLDL）。重要的是，CEL显示了亲胆汁盐非依赖性lysoPC， 神经酰胺水解活性。人CEL也是高度多态的，编码 羧基富含脯氨酸的重复单位数量不同的蛋白质 终点站基于这些新的观察，本申请提出测试 以下假设：（1）血管系统中的CEL表达是一个重要因素， 炎症反应机制，保护动脉粥样硬化形成的早期阶段， 水解并降低lysoPC和神经酰胺的致动脉粥样硬化性质;（2） CEL的C-末端中富含脯氨酸的重复单元的数目为 在确定其水解lysoPC和神经酰胺的能力方面是重要的;和（3） CEL基因多态性是个体易感性的决定因素， 修饰LDL介导的动脉粥样硬化事件。这些假设可以通过 3个具体目标下的实验。具体目标1计划生产 血管特异性CEL转基因小鼠，以评估血管CEL 基因表达对动脉粥样硬化斑块发生和发展的影响。 具体目标2将使用定点诱变方法来测试 假设在其C-末端富含脯氨酸的重复单元的数量是 CEL的lysoPC和神经酰胺水解活性的重要决定因素， 因此，不同的CEL亚型在保护血管内皮细胞中的有效性是不同的。 细胞对抗lysoPC和神经酰胺诱导的致动脉粥样硬化事件。具体目标3 将确定修饰LDL诱导CEL基因表达的机制 在人类巨噬细胞和内皮细胞中。实验将被设计来测试 CEL基因激活是通过信号转导介导的假说 oxLDL与细胞上的清道夫受体结合的结果 表面，或者需要特定脂质的内化 与氧化脂蛋白相关的成分。综上所述各项 研究将确定有助于确定 动脉粥样硬化易感性也可以设计遗传筛查策略 识别易患动脉粥样硬化的受试者进行早期干预， 降低他们患上这种疾病的风险。