APOE RECYCLING: Cell Biology and Physiologic Relevance

描述(申请人提供)：载脂蛋白(Apo)E发挥关键作用 在细胞外和脂蛋白代谢中的作用 在细胞内。我们实验室最近的研究表明， 内化的载脂蛋白E可以避免降解和回收，这一过程 会使载脂蛋白E影响细胞功能。这就是我们的目标 授予定义载脂蛋白E回收和再利用的机制并启动 解决它的生理学相关性。这项建议将对工作进行测试 假设内化的载脂蛋白E的一小部分在 细胞和循环，提供了一种机制，使一种蛋白质是关键的 许多生物过程可以最大限度地发挥其对细胞功能的影响。这 假设将通过以下具体目标进行检验：具体目标1。 要确定载脂蛋白E循环是否取决于细胞入口点或 与载脂蛋白E相关的脂蛋白颗粒。这些研究将测试 假设内化载脂蛋白E的处置和潜在的 回收取决于apoE所在的粒子和 进入牢房。具体目标#2.定义细胞内的贩运 载脂蛋白E的循环途径。这些研究将检验载脂蛋白E 通过分泌途径循环，特别是通过高尔基体 仪器。具体目标#3.确定载脂蛋白E的生理学相关性 回收利用。这些研究将检验这样的假设，即回收提供了 载脂蛋白E影响细胞功能的途径，特别是脂质和 脂蛋白代谢、分泌捕获和胆固醇外流。这些 研究将主要集中在肝细胞的载脂蛋白E循环，但也将 扩展到巨噬细胞，这是载脂蛋白E再循环对其影响的一种细胞类型 功能可能与动脉粥样硬化的形成密切相关。

DESCRIPTION (provided by applicant): Apolipoprotein (apo) E plays critical roles in lipid and lipoprotein metabolism both extracellularly and intracellularly. Recent studies in our laboratories have shown that internalized apoE may be spared from degradation and recycled, a process that would enable apoE to impact cellular functions. It is the objective of this grant to define the mechanisms of apoE recycling and resecretion and to start addressing its physiologic relevance. This proposal will test the working hypothesis that a fraction of internalized apoE is spared degradation in the cell and recycled, providing a mechanism whereby a protein that is critical for many biological processes can maximize its impact on cellular functions. This hypothesis will be tested through the following specific aims: Specific Aim #1. To determine if apoE recycling is dependent upon cellular entry point or the lipoprotein particle with which apoE is associated. These studies will test the hypothesis that the disposition of internalized apoE and the potential for recycling are dependent on the particle on which apoE resides and the point of entry into the cell. Specific Aim #2. To define the intracellular trafficking pathway of recycling apoE. These studies will test the hypothesis that apoE recycles through the secretory pathway, specifically through the Golgi apparatus. Specific Aim #3. To define the physiologic relevance of apoE recycling. These studies will test the hypothesis that recycling provides a pathway for apoE to impact cellular functions, specifically lipid and lipoprotein metabolism, secretion-capture, and cholesterol efflux. These studies will primarily focus on apoE recycling by the hepatocyte, but will also expand to the macrophage, a cell type for which the impact of apoE recycling on function may be of great relevance to atherogenesis.