HDL RECEPTOR SR B1--REGULATION AND ROLE

描述(摘自申请者摘要)：血浆高密度脂蛋白水平为 与动脉粥样硬化的风险成反比。高密度脂蛋白或 清道夫受体-B1(SR-B1)是最近发现的一种质膜蛋白 介导高密度脂蛋白胆固醇选择性输送的高密度脂蛋白受体 酯到细胞。首席调查员已经证明了替代方案 SR-B1 mRNA的剪接发生在人和小鼠的组织中，与 这是个未知数。SR-B1已被映射到与高密度脂蛋白相关的一个基因座 水平(未发表的观测结果)。炎症会导致各种各样的 代谢变化，其中两个特别会导致高密度脂蛋白的调节 结构和新陈代谢。诱发急性期血清类淀粉样蛋白A(SAA) 取代载脂蛋白A-I，显著重塑高密度脂蛋白颗粒。 另一种急性时相蛋白--分泌型非胰腺磷脂酶A2 (SPLA2)是伴随诱导的，可以水解高密度脂蛋白磷脂。这个 这项提议要检验的中心假设是，修改 在炎症过程中发生的高密度脂蛋白会导致 高密度脂蛋白与SR-B1的相互作用。这样的变化将具有重要的 对高密度脂蛋白代谢的影响，并可能影响高密度脂蛋白介导的胆固醇 向肝脏的传递以及高密度脂蛋白和细胞之间的胆固醇流量 局限性动脉粥样硬化性病变。 这项建议的具体目的是：1)确定 选择性mRNA剪接在细胞周期调控和功能活性中的作用 SR-B1。这将通过量化不同的 调节SR-B1的条件下SR-B1的mRNA和蛋白质的形式 SR-B1在培养细胞中的表达及不同形式的表达 并比较它们作为高密度脂蛋白受体的功能；2)确定 炎症诱导的高密度脂蛋白修饰影响高密度脂蛋白与SR-B1的结合 受体和选择性脂质摄取进入细胞。这将通过以下方式实现 确定在急性期反应期间高密度脂蛋白的改变或 特别是sPLA2和SAA的修饰，改变了高密度脂蛋白与SR-B1或 SR-B1介导的脂类输送到细胞；以及3)决定了 SR-B1在小鼠体内的表达影响正常和正常血浆水平 急性期高密度脂蛋白。这将通过确定 腺病毒载体介导的SR-B1在正常和正常细胞水平的高表达 急性时相高密度脂蛋白和其他脂蛋白。

DESCRIPTION (Adapted from applicant's abstract): Plasma HDL levels are inversely associated with the risk for atherosclerosis. The HDL or scavenger receptor-B1 (SR-B1) is a recently-described plasma membrane receptor for HDL that mediates the selective delivery of HDL cholesterol ester to cells. The principal investigator has shown that alternative splicing of SR-B1 mRNA occurs in man and mouse tissues, the relevance of which is unknown. SR-B1 has been mapped to a locus associated with HDL levels (unpublished observations). Inflammation induces a wide variety of metabolic changes and two of these in particular lead to modulation of HDL structure and metabolism. The induced acute phase serum amyloid A (SAA) displaces apolipoprotein A-I and markedly remodels the HDL particle. Another acute phase protein, secretory non-pancreatic phospholipase A2 (sPLA2) is concomitantly induced and can hydrolyze HDL phospholipids. The central hypothesis to be examined in this proposal is that the modification of HDL that occurs during inflammation leads to alterations in the interaction between HDL and SR-B1. Such changes would have important implications for HDL metabolism and could affect HDL-mediated cholesterol delivery to the liver as well as cholesterol flux between HDL and cells in localized atherosclerotic lesions. The specific aims of this proposal are: 1) determine the significance of alternative mRNA splicing in the regulation and functional activity of SR-B1. This will be achieved by quantifying the expression of the different forms of SR-B1 mRNA and protein under conditions that regulate SR-B1 expression and by expressing the different forms of SR-B1 in cultured cells and comparing their abilities to function as HDL receptors; 2) determine how inflammation-induced modifications of HDL influence HDL binding to the SR-B1 receptor and selective lipid uptake into cells. This will be achieved by determining whether modifications of HDL during an acute phase response or modification by sPLA2 and SAA specifically, alters HDL binding to SR-B1 or SR-B1-mediated lipid delivery to cells; and 3) determine the extent to which SR-B1 expression in the mouse influences the plasma levels of normal and acute phase HDL. This will be achieved by determining the effect of adenovirus-mediated over-expression of SR-B1 on the levels of normal and acute phase HDL and of other lipoproteins.