Characterization of the Role of ARH on LDLR Function

描述（由申请人提供）：低密度脂蛋白受体（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中起着关键作用。最近的研究发现，接头蛋白ARH与LDLR上的FDNPVY序列结合，是LDL清除所必需的，这为描述LDLR介导脂蛋白摄取和清除的分子机制提供了一种工具。最近的研究和我们的初步数据表明，ARH在LDLR功能中起着复杂的作用。我们的假设是ARH主要参与LDL的摄取，并且在摄取过程中ARH在三个水平上起作用：首先，ARH促进LDLR结合LDL的能力；其次，ARH促进ldl - ldl复合物的摄取；第三，ARH确保LDL从内体的LDLR中有效释放。这项拨款提案将采用多学科方法，利用生物化学、显微镜和动物研究来确定ARH促进脂蛋白结合、摄取和降解的机制。实验将确定ARH负责促进LDL结合的区域，表征ARH在LDL和VLDL摄取中的作用，并确定ARH在LDL和LDLR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，不同亚群的结合伙伴可能在脂蛋白结合和摄取途径的不同阶段参与。ARH及其相关蛋白在LDLR脂蛋白摄取中的功能特征可以澄清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.