Characterization of the Role of ARH on LDLR Function

描述（由申请人提供）：LDL受体（LDLR）介导的内吞作用对低密度脂蛋白（LDL）和极低密度脂蛋白（VLDL）的清除在预防动脉粥样硬化和血管疾病中发挥着关键作用。最近发现接头蛋白 ARH 与 LDLR 上的 FDNPVY 序列结合并且是 LDL 清除所必需的，这提供了一种工具来表征 LDLR 介导脂蛋白摄取和清除的分子机制。最近的研究和我们的初步数据表明 ARH 在 LDLR 功能中发挥着复杂的作用。我们的假设是，ARH 主要参与 LDL 的摄取，并且 ARH 在摄取过程中在三个层面发挥作用：首先，ARH 促进 LDLR 结合 LDL 的能力；其次，ARH 促进 LDLR 结合 LDL 的能力。其次，ARH促进LDLR-LDL复合物的摄取；第三，ARH 确保内体中 LDLR 有效释放 LDL。该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 中负责促进 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 内体运输中的功能。我们还将研究新型 ARH 结合伴侣在 LDLR 功能中的作用。 ARH 是一种多功能衔接蛋白，不同的结合伴侣子集可能参与脂蛋白结合和摄取途径的不同阶段。 ARH 及其相关蛋白在 LDLR 摄取脂蛋白中的功能特征可能会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.