The Role of Scavenger Receptor Class B Type 1 in Humans

描述（由申请人提供）：高密度脂蛋白胆固醇（HDL-C）水平被认为可以预防心血管疾病。在某些人群中，这可能是真的，也可能不是。本研究项目的长期目标是确定脂蛋白受体、I型B类清道夫受体或SR-BI的缺乏是否是高水平HDL-C的原因，并且可能是矛盾的，增加心血管疾病的风险。在具体目标1中，我们将进行体外实验以检查某些SR-BI基因（SCARB 1）变体影响SR-BI蛋白表达的机制。在具体目标2中，我们将继续招募HDL-C水平高于60 mg/dl的受试者（这是因为高于60 mg/dl的水平被认为具有心脏保护作用），并获得血液样本以测量胆固醇水平、DNA和表达SR-BI蛋白的单核细胞源性巨噬细胞。我们将研究SCARB 1基因内的遗传变异与脂质水平、巨噬细胞SR-BI蛋白和RNA表达以及SR-BI功能的相关性（通过从放射性标记的HDL中摄取胆固醇酯来测量）。我们还将在多种族动脉粥样硬化研究（梅萨）和早发性心肌梗死（心肌梗死遗传学联合会研究）的受试者中研究SCARB 1多态性和脂质水平与亚临床动脉粥样硬化的相关性。我们的研究结果将进一步深入了解SR-BI对HDL-C水平升高受试者、由白人、非洲裔美国人、西班牙裔和亚洲血统人群充分代表的较大人群（梅萨）以及早发心肌梗死受试者的血脂水平和心血管疾病的作用。 高密度脂蛋白（HDL）被认为是血液胆固醇水平的“健康”或“良好”部分。然而，心脏病可能发生，尽管一个人有理想的HDL水平。我们的研究将检测HDL受体基因的变异，即清道夫受体B I型或SR-BI，是否与高密度脂蛋白水平和心脏病有关。

DESCRIPTION (provided by applicant): High density lipoprotein cholesterol (HDL-C) levels are thought to protect against cardiovascular disease. This may or may not be true in certain populations. The long-term goal of this research project is to determine if a deficiency in the lipoprotein receptor, scavenger receptor class B type I or SR-BI, is a cause of high levels of HDL-C and, perhaps paradoxically, an increased risk for cardiovascular disease. In specific aim 1, we will perform in vitro experiments to examine the mechanism(s) by which certain SR-BI gene (SCARB1) variants affect SR-BI protein expression. In specific aim 2, we will continue recruiting subjects with HDL-C levels above 60 mg/dl (this is because levels above 60 mg/dl are thought to be cardioprotective) and obtaining blood specimens to measure cholesterol levels, DNA, and monocyte-derived macrophage that express SR-BI protein. We will examine the association of genetic variations within the SCARB1 gene with lipid levels, macrophage SR-BI protein and RNA expression and SR-BI function (as measured by the uptake of cholesteryl esters from radiolabeled HDL). We will also examine the association of SCARB1 polymorphisms and lipid levels and subclinical atherosclerosis in participants of the Multi-Ethnic Study of Atherosclerosis (MESA) and in subjects with premature myocardial infarction (Myocardial Infarction Genetics Consortium Study). The results from our studies will provide further insight into the role of SR-BI on lipid levels and cardiovascular disease in subjects with elevated levels of HDL-C, in a larger population (MESA) well-represented by persons of Caucasian, African-American, Hispanic and Asian ancestry, and in subjects with premature myocardial infarction. PUBLIC HEALTH RELEVANCE: High density lipoproteins (HDL) are considered the "healthy" or "good" fraction of the blood cholesterol levels. However, heart disease can occur despite a person having desirable levels of HDL. Our study will examine whether variations in the gene for the HDL receptor, scavenger receptor class B type I or SR-BI, might be associated with good levels of HDL and heart disease.