Control of ErbB Receptor Sorting in Endosomes

内体中 ErbB 受体分选的控制

• 批准号: 6794606
• 负责人: CATHLEEN R CARLIN
• 金额: $ 27.54万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 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
• 来源: https://reporter.nih.gov/project-details/6794606
• 关键词: biological signal transduction; cell line; cell membrane; electron microscopy; gene mutation; intracellular transport; ligands; lysosomes; membrane fusion; membrane proteins; mitogen activated protein kinase; nuclear magnetic resonance spectroscopy; phosphorylation; phosphotransferases; protein protein interaction; protein structure function; receptor binding; receptor expression; receptor mediated endocytosis; site directed mutagenesis; vesicle /vacuole

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）：在内吞和胞外途径中，内体装置是膜分选的主要部位。对于配体激活的受体，它也提供了一种机制来实现来自不同膜室的细胞信号的适当平衡。本提案的主要目的是了解内吞作用如何控制细胞对EGF受体（EGFR）的反应，EGFR是ErbB受体家族的原型。内吞运输的复杂性预示着egfr在细胞的不同位置使用大量不同的分选信号。这些信号的表征为理解EGFR在内体装置中的转运调节提供了一个框架。我们已经确定了三个控制EGFR运输关键基准的非重叠分选信号：679-LL，控制多泡内核体到溶酶体转运中间体或MVEs的分选；954-YLVI，控制溶酶体在胞外通路相交部位的分选；以及662-RxxxxPLTP，它控制从核内体到质膜的分选。拟议研究的完成将为这些信号在配体调节的EGFR运输过程中的协调作用提供新的见解。由于与EGFR相比，相关的ErbB受体具有不同的分选信号，因此我们也将深入了解ErbB信号通常是如何由细胞内运输控制的。这对ErbB2尤其重要，它的EGFR配体依赖性激活需要EGFR序列调节内吞后运输，而不是内在的酪氨酸激酶活性。显性抑制突变在特定步骤破坏EGFR运输的有效性也提供了一套独特的试剂，用于研究内体信号传导的时空组织。以下假设将被检验：1。配体诱导的EGFR内吞后对溶酶体的分选是由多个分选信号以循序渐进的方式协同作用介导的。2. 679-LL MVE分类信号被认为是一个更大的基序的一部分，其生理功能依赖于蛋白质-蛋白质相互作用。3. 662-RxxxxPLTP分选信号控制EGFR再循环到质膜，并受MAP激酶介导的Thr669磷酸化调控。4. 679-LL分选信号通过控制胞吞过程中引发的生长刺激通路的平衡来调节EGFR信号。这一假设是基于新的数据，这些数据表明，与野生型相比，具有失活L679A、L680A突变的egfr可以选择性地激活存活途径，并将使用体外和体内实验模型进行验证。