Role of Endothelial Lipase in Atherosclerosis

描述(申请人提供)：冠心病(CHD)的主要原因是冠状动脉粥样硬化，这是人类最常见的发病率和死亡率的原因之一。动脉粥样硬化的一个主要易感因素是低水平的高密度脂蛋白胆固醇(HDLC)。高密度脂蛋白胆固醇水平的变化大约有一半是由于遗传因素造成的。最近，一种新发现的基因，称为内皮脂肪酶(EL)，已被证明具有几个独特的特征，使EL成为低高密度脂蛋白-C和动脉粥样硬化的首选候选基因。EL影响体内的高密度脂蛋白代谢，具有高水平的磷脂酶活性，由血管内皮细胞表达，并被炎性细胞因子上调。本项目的目标是确定EL对血脂谱变异的遗传贡献，并从结构和功能上评估其作用。为实现这些目标，将实现以下具体目标。1)为了鉴定和鉴定EL基因外显子和内含子-外显子边界的突变，分子遗传学技术将被用于选择表达高和低高密度脂蛋白胆固醇水平的极端表型的个体。已发现的突变对血脂谱的影响将在两个以人群为基础的样本中进行评估，其中拉美裔(n=406)和非拉美裔白人(n=604)将使用统计方法。2)为了建立和表征EL的精细三维分子模型，将使用同源建模技术并对其结构特征进行表征。将为目标1中识别的所有错义突变生成突变3D模型，并使用分子建模技术与野生型模型进行结构差异比较。3)为了评估在AIM 1中确定的和在AIM 2中进行结构评估的突变的脂肪酶活性，将使用体外诱变、表达和功能研究。综上所述，这一综合项目将从遗传、结构和调节血浆高密度脂蛋白水平的功能方面描述EL的特征，从而成为动脉粥样硬化的主要遗传危险因素。了解动脉粥样硬化危险因素的分子基础可能会导致降低人群中冠心病风险的新策略。

DESCRIPTION (provided by applicant): The leading cause of coronary heart disease (CHD) is atherosclerosis of the coronary arteries, which is one of the most prevalent causes of morbidity and mortality in man. A major predisposing factor to atherosclerosis is low levels of high density lipoprotein-cholesterol (HDL-C). About half of the variation in HDL-C levels is due to genetic influences. Recently, a newly discovered gene, called endothelial lipase (EL), has been shown to have several unique features that make EL a prime candidate gene for low HDL-C and atherosclerosis. EL affects HDL metabolism in vivo, has high levels of phospholipase activity, is expressed by vascular endothelium, and is upregulated by inflammatory cytokines. The objectives of this project are to determine the genetic contribution of EL to variation in plasma lipid profile and to assess its role structurally and functionally. To achieve these objectives, the following specific aims will be carried out. 1) To identify and characterize mutations in the exons and intron-exon boundaries of the EL gene, molecular genetic techniques will be used in selected individuals expressing the extreme phenotype of high and low HDL-C levels. The impact of the discovered mutations on plasma lipid profile will be evaluated in two population- based samples of Hispanics (n=406) and non-Hispanic Whites (n=604) using statistical methods. 2) To build and characterize a refined 3D molecular model of EL, homology modeling techniques will be used and its structural features will be characterized. Mutant 3D models will be generated for all missense mutations identified in Aim 1 and compared with the wild type model for structural differences using molecular modeling techniques. 3) To assess the lipase activity of the mutations identified in Aim 1 and structurally assessed in Aim 2, in vitro mutagenesis, expression, and functional studies will be used. In summary, this comprehensive project will characterize EL with respect to its genetic, structure, and function in regulating plasma HDL-C levels and hence a major genetic risk factor for atherosclerosis. Understanding the molecular basis of risk factors in atherosclerosis may lead to new strategies for reducing the risk of coronary heart disease in the population.