Characterization of the Role of ARH on LDLR Function

描述(申请人提供)：低密度脂蛋白(LDL)受体(LDLR)介导的内吞作用清除低密度脂蛋白(LDL)和极低密度脂蛋白(VLDL)在预防动脉粥样硬化和血管疾病方面起着至关重要的作用。最近发现，适配蛋白ARH与LDLR上的FDNPVY序列结合，是清除低密度脂蛋白所必需的，这为研究LDLR介导脂蛋白摄取和清除的分子机制提供了一个工具。最近的研究和我们的初步数据表明，ARH在LDLR功能中扮演着复杂的角色。我们的假设是，ARH主要参与低密度脂蛋白的摄取，ARH在摄取过程中有三个水平的作用：第一，ARH促进LDLR结合低密度脂蛋白的能力；第二，ARH促进LDLR-LDL复合体的摄取；第三，ARH确保内体LDLR有效地释放低密度脂蛋白。这项赠款计划将采用生物化学、显微镜和动物研究的多学科方法，以确定ARH促进脂蛋白结合、吸收和降解的机制。实验将确定ARH中负责促进低密度脂蛋白结合的区域，表征ARH在低密度脂蛋白和极低密度脂蛋白摄取中的作用，并确定ARH在低密度脂蛋白和低密度脂蛋白受体的内体运输中的功能。我们还将研究新的ARH结合伙伴在LDLR功能中的作用。ARH是一种多功能的接头蛋白，不同的结合伙伴亚群可能参与脂蛋白结合和摄取途径的不同阶段。低密度脂蛋白受体对ARH及其相关蛋白在脂蛋白摄取中作用的研究可能有助于我们对清除过程的理解。

DESCRIPTION (provided by applicant): The clearance of low density lipoprotein (LDL) and very low density lipoprotein (VLDL) by LDL receptor (LDLR) mediated endocytosis plays a critical role in preventing atherosclerosis and vascular disease. The recent finding that the adaptor protein, ARH, binds to the FDNPVY sequence on the LDLR and is required for LDL clearance has provided a tool with which to characterize the molecular mechanisms by which the LDLR mediates lipoprotein uptake and clearance. Recent studies and our preliminary data indicate that ARH plays a complex role in LDLR function. Our hypothesis is that ARH is principally involved in the uptake of LDL and that ARH functions at three levels in the uptake process: first, ARH promotes the ability of the LDLR to bind LDL; second, ARH promotes the uptake of LDLR-LDL complexes; and third, ARH ensures efficient release of LDL from the LDLR in endosomes. This grant proposal will employ a multidisciplinary approach using biochemistry, microscopy and animal studies to identify the mechanisms by which ARH promotes the binding, uptake and degradation of lipoproteins. Experiments will identify the regions of ARH that are responsible for promoting LDL binding, characterize the role of ARH in LDL and VLDL uptake, and determine the function of ARH in the endosomal trafficking of LDL and the LDLR. We will also examine the role of novel ARH binding partners in LDLR function. ARH is a multifunctional adaptor protein and different subsets of binding partners may participate at different stages in the lipoprotein binding and uptake pathway. The characterization of the function of ARH and its associated proteins in lipoprotein uptake by LDLR may clarify our understanding of the clearance process.