Control of ErbB Receptor Sorting in Endosomes

内体中 ErbB 受体分选的控制

基本信息

批准号：
6544872
负责人：
CATHLEEN R CARLIN
金额：
$ 28.92万
依托单位：
CASE WESTERN RESERVE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-09-05 至 2006-08-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): The endosomal apparatus is a major site of membrane sorting in both endocytic and exocytic pathways. For ligand activated receptors it also provides a mechanism for achieving the proper balance of cell signaling from different membrane compartments. A main objective of this proposal is to understand how endocytosis controls cellular responses to the EGF receptor (EGFR), the prototype for the ErbB receptor family. The complexity of endocytic trafficking predicts that EGFRs use a multitude of distinct sorting signals at different locations in the cell. Characterization of these signals provides a framework for understanding regulation of EGFR transit in the endosomal apparatus. We have identified three non-overlapping sorting signals that control critical benchmarks in EGFR trafficking: 679-LL, which controls sorting in multivesicular endosome-to-lysosome transport intermediates or MVEs; 954-YLVI, which controls lysosomal sorting at a site intersecting the exocytic pathway; and 662-RxxxxPLTP, which controls sorting from endosomes to the plasma membrane. Completion of the proposed studies will provide new insights on the coordinated action of these signals during ligand-regulated EGFR trafficking. Since related ErbB receptors have divergent sorting signals compared to EGFR, we will also gain insight to how ErbB signaling in general is controlled by intracellular trafficking. This is particularly important for ErbB2, whose ligand-dependent activation by EGFR requires EGFR sequences that regulate post-endocytic trafficking and not intrinsic tyrosine kinase activity. The availability of dominant-inhibitory mutations that disrupt EGFR trafficking at defined steps also provides a unique set of reagents with which to study the temporal and spatial organization of signaling from endosomes. The following hypotheses will be tested: 1. Ligand-induced EGFR post-endocytic sorting to lysosomes is mediated by the concerted action of multiple sorting signals acting in a step-wise fashion. 2. The 679-LL MVE sorting signal is recognized as part of a larger motif whose physiological function is dependent on protein-protein interactions. 3. The 662-RxxxxPLTP sorting signal controls EGFR recycling to the plasma membrane, and is regulated by MAP kinase-mediated phosphorylation of Thr669. 4. The 679-LL sorting signal regulates EGFR signaling by controlling the balance of growth stimulatory pathways elicited during endocytosis. This hypothesis is based on new data suggesting that EGFRs with an inactivating L679A,L680A mutation selectively activate survival pathways compared to wild-type, and will be tested using both in vitro and in vivo experimental models.

描述（由申请人提供）：内体设备是内吞和外生途径中膜分类的主要位点。对于配体激活受体，它还提供了一种实现来自不同膜室的细胞信号的适当平衡的机制。该提案的一个主要目的是了解内吞作用如何控制对EGF受体（EGFR）的细胞反应，EGF受体（EGFR）是ERBB受体家族的原型。内吞运输的复杂性预测，EGFR在细胞的不同位置使用多种不同的分类信号。这些信号的表征为理解内体设备中EGFR传输的调节提供了一个框架。我们已经确定了三个非重叠的分类信号，这些信号控制着EGFR运输中的关键基准：679-LL，它们控制在多囊体内体到溶解体传输中间体或MVE中进行排序； 954-ylvi，控制在外部途径的位点控制溶酶体分选；和662-RXXXXXPLTP，它控制从内体到质膜的排序。拟议的研究的完成将提供有关配体调节的EGFR贩运期间这些信号的协调作用的新见解。由于与EGFR相比，相关的ERBB受体具有不同的排序信号，因此我们还将深入了解ERBB信号通常如何通过细胞内运输控制。这对于ERBB2尤其重要，ERBB2的配体依赖性EGFR的激活需要EGFR序列来调节注入后流trag虫而不是固有的酪氨酸激酶活性。在定义步骤中破坏EGFR运输的主要抑制突变的可用性也提供了一组独特的试剂，可利用内体信号传导的时间和空间组织。将测试以下假设：1。配体诱导的EGFR在溶酶体中分类后分类后，是由以逐步作用的多种分类信号的一致作用介导的。 2。679-ll MVE排序信号被认为是较大基序的一部分，其生理功能取决于蛋白质 - 蛋白质相互作用。 3。662-RXXXXXXXPLTP STARMING信号控制EGFR回收到质膜，并由TH669的MAP激酶介导的磷酸化调节。 4。679-LL分选信号通过控制内吞作用期间引起的生长刺激途径的平衡来调节EGFR信号传导。该假设基于新数据表明，与野生型相比，具有灭活L679A的EGFR选择性地激活生存途径，并将使用体外和体内实验模型进行测试。