SR-BI: INFLUENCE OF APOA-II

描述：(改编自《研究人员摘要》)：高密度脂蛋白和载脂蛋白A-I血浆 血糖值与冠状动脉疾病呈负相关。两个主要的子类 高密度脂蛋白中只含有apoA-I(LPAI)的那些和同时含有apoA-I的那些 和载脂蛋白A-II(LPAI/AII)。鉴于载脂蛋白A-1一般被认为是 抗动脉粥样硬化，证据表明载脂蛋白A-II是促动脉粥样硬化的。高密度脂蛋白 受体SR-BI在高密度脂蛋白代谢中起重要作用。SR-BI 介导细胞对高密度脂蛋白中胆固醇酯的选择性摄取 促进细胞内游离胆固醇向高密度脂蛋白的外流。尽管SR-BI是 被认为表现出广泛的脂蛋白结合特异性的小组 PI在未发表的研究中发现，LPAI/AII在其 绑定SR-BI的能力。这项提议中要检验的中心假设 载脂蛋白AII通过抑制高密度脂蛋白发挥调节功能 与SR-BI结合，从而SR-BI介导的高密度脂蛋白和高密度脂蛋白之间的脂质流动 细胞。载脂蛋白A-II的这种调节功能将对 高密度脂蛋白代谢，包括它在胆固醇反向运输中的作用。这 因此，该提案试图研究载脂蛋白A-II对SR-BI介导的影响 高密度脂蛋白代谢和高密度脂蛋白与细胞之间的胆固醇流量。具体目标 目的：1)确定载脂蛋白A-II对SR-BI介导的胆固醇流量的影响 在高密度脂蛋白和细胞之间。这将通过研究 人载脂蛋白A-II对SR-BI结合和代谢人高密度脂蛋白的影响 转染组CHO细胞。仅apoA-I和apoAI/apoAII-包含粒子将 比较和提高重组人载脂蛋白A-II水平的效果 被研究的颗粒，2)评估载脂蛋白A-II对高密度脂蛋白水平和 小鼠肝脏选择性摄取胆固醇酯。这将通过以下方式实现 测定肝脏选择性摄取胆固醇酯的相对速率 载脂蛋白A-1-/-小鼠的LPAI和LPAI/AII及腺病毒介导的作用 人或小鼠血浆载脂蛋白A-II水平升高对高密度脂蛋白水平的影响 在人apoA-I转基因小鼠或C57BL/6小鼠中，3)研究 载脂蛋白A-I作为一种核糖核酸的调节所需的结构要求 Sr-BI配体。这将通过在体内和体内研究来实现。 培养细胞，一系列结构变异和突变的影响 载脂蛋白A-II对高密度脂蛋白与SR-BI结合和选择性胆固醇酯摄取的影响。

DESCRIPTION: (Adapted from the Investigator's Abstract):HDL and apoA-I plasma levels are inversely related to coronary artery disease. Two major subclasses of HDL are those containing only apoA-I (LpAI) and those containing both apoA-I and apoA-II (LpAI/AII). Whereas apoA-1 is considered to be generally anti-atherogenic, evidence points to apoA-II being pro-atherogenic. The HDL receptor, SR-BI, plays an important role in the metabolism in HDL. SR-BI mediates the selective uptake of cholesterol esters from HDL into cells and enhances the efflux of cellular free cholesterol to HDL. Although SR-BI is considered to exhibit a broad lipoprotein binding specificity, the group of the PI has found in unpublished studies that LpAI/AII is markedly deficient in its ability to bind SR-BI. The central hypothesis to be examined in this proposal is that apolipoprotein AII exerts a regulatory function by inhibiting HDL binding to SR-BI and consequently SR-BI-mediated lipid flux between HDL and cells. Such a regulatory function of apoA-II would have major implications for HDL metabolism, including its role in reverse cholesterol transport. This proposal therefore seeks to examine the influence of apoA-II on SR-BI-mediated HDL metabolism and on cholesterol flux between HDL and cells. The specific aims are: 1) to determine the effect of apoA-II on SR-BI-mediated cholesterol flux between HDL and cells. This will be accomplished by studying the influence of human apoA-II on the binding and metabolism of human HDL by SR-BI expressed in transfected CHO cells. ApoA-I only and apoAI/apoAII-containing particles will be compared and the effect of increasing apoA-II levels in reconstituted particles studied, 2) to assess the effect of apoA-II on HDL levels and on hepatic selective cholesterol ester uptake in mice. This will be achieved by determining relative rates of hepatic selective cholesterol ester uptake from LpAI and LpAI/AII in apoA-1-/- mice and the effect of adenovirus-mediated expression of increasing plasma levels of human or mouse apoA-II on HDL levels in human apoA-I transgenic mice or C57BL/6 mice and 3) to investigate the structural requirements of apoA-II necessary for the modulation of apoA-I as an SR-BI ligand. This will be accomplished by studying both in vivo and in cultured cells, the effects of a series of structural variants and mutations of apoA-II on HDL binding to SR-BI and on selective cholesterol ester uptake.