Trafficking and Proteolysis of Notch and Other Gamma-Secretase Substrates

Notch 和其他γ-分泌酶底物的运输和蛋白水解

• 批准号: 8067753
• 负责人: Mark E Fortini
• 金额: $ 31.42万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8067753
• 关键词: Affect; Alzheimer' s Disease; Amyloid; Amyloid beta-Protein Precursor; Aspartic Endopeptidases; Biochemical; Biogenesis; Biological; Biology; Brain; Cell Adhesion Molecules; Cell physiology; Cell surface; Cells; Chromosomes; Cleaved cell; Complex; Data; Development; Disease; Drosophila genus; Early Endosome; Endocytosis; Endosomes; Event; Excision; Family; Genes; Genetic; Genetic Screening; Goals; Health; Human; Immune system; Integral Membrane Protein; Intracellular Membranes; Ions; Lead; Ligand Binding; Ligands; Light; Lysosomes; Malignant Neoplasms; Mammalian Cell; Mediating; Membrane; Membrane Protein Traffic; Molecular; Molecular Cloning; Mutation; Neurodegenerative Disorders; Neurons; Pathogenesis; Pathway interactions; Peptides; Play; Process; Production; Proteins; Proteolysis; Proteolytic Processing; Receptor Signaling; Recovery; Recycling; Research Proposals; Role; Route; Screening Result; Signal Pathway; Signal Transduction; Sorting - Cell Movement; T-Cell Leukemia; T-Lymphocyte; Water; amyloid precursor protein processing; animal tissue; brain tissue; cell fate specification; gamma secretase; human disease; human tissue; interest; member; mutant; notch protein; novel; secretase; solute; trafficking; tumorigenesis; water channel

DESCRIPTION (provided by applicant): Many integral membrane proteins have been identified as cleavage substrates for the intramembrane aspartyl protease complex termed ??secretase. These ??secretase substrates include receptors for signaling pathways, adhesion molecules, and other factors that are localized at the cell surface and whose activities are regulated by ??secretase-mediated cleavage. Understanding the molecular details of ??secretase substrate biology is important due to the prominent role that many substrates play in normal cellular physiology and in human disease. For example, the Notch receptor, a well- characterized ??secretase substrate, is essential for proper cell-fate specification and cellular differentiation during the development of animal and human tissues. Inappropriate activation of the Notch pathway in the human immune system causes T-cell leukemia and dysregulated Notch activity has been implicated in other cancers and developmental diseases. Furthermore, processing of the Amyloid Precursor Protein (APP) by ??secretase contributes directly to the production of secreted amyloid-2 peptide in human brain tissue, a crucial event in the pathogenesis of Alzheimer's disease. A key feature of ??secretase substrate cleavage is its tight control by ligand binding, ectodomain removal, and other regulatory processes. A growing body of data indicates that cleavage also depends upon intracellular membrane trafficking of ??secretase substrates and their sorting within specific trafficking compartments. In the case of both Notch and APP, ??secretase-mediated cleavage is associated with endocytosis of the substrate from the cell surface and its entry into endosomes. We have found that proper biogenesis of the early endosome compartment requires the function of an aquaporin channel protein, defining a specialized endosome route for efficient ??secretase-dependent Notch trafficking and signaling. In Specific Aim 1, we propose to characterize further the role of this aquaporin in endosome biogenesis and Notch trafficking. These studies will shed light on the cell biological aspects of ?? secretase substrate trafficking and their relationship to ??secretase substrate cleavage, recycling, and degradation. In Specific Aim 2, we propose to conduct a forward genetic screen for new factors involved in the intracellular membrane trafficking of Notch and other ??secretase substrates. Preliminary results from this screen have already proven to be very promising, including the recovery of many potentially new genes needed for various steps of Notch intracellular trafficking. Further analysis and molecular cloning of several of these new genes is now underway. The main goal of this project is to advance our understanding of ??secretase substrate trafficking and its relevance to secretase- dependent processes in tumorigenesis and neurodegenerative disease. PUBLIC HEALTH RELEVANCE: Proteins cleaved by ??secretase, including the Notch receptor and amyloid precursor protein, are important for developmental signaling and neuronal function, and their dysregulation contributes to cancer and neurodegenerative disease. This research proposal seeks to identify cellular factors that control the production, trafficking, and proteolytic processing of ?? secretase targets. These studies might lead to the identification of new proteins and intracellular pathways that could be therapeutically targeted in cancer and neurodegenerative disorders.

描述(由申请人提供)：许多完整的膜蛋白已被鉴定为膜内天冬氨酸蛋白酶复合体的切割底物，称为分泌酶。这些分泌酶底物包括信号通路的受体、黏附分子和其他定位于细胞表面的因子，它们的活性受分泌酶介导的切割调节。了解分泌酶底物生物学的分子细节很重要，因为许多底物在正常的细胞生理和人类疾病中扮演着重要的角色。例如，Notch受体是一种特性良好的分泌酶底物，在动物和人类组织的发育过程中，对适当的细胞命运指定和细胞分化至关重要。人类免疫系统中Notch通路的不适当激活会导致T细胞白血病，而Notch活性失调也与其他癌症和发育疾病有关。此外，分泌酶对淀粉样前体蛋白(APP)的加工直接促进了人脑组织分泌淀粉样蛋白-2肽的产生，这是阿尔茨海默病发病机制中的关键事件。分泌酶底物切割的一个关键特征是它受到配体结合、胞外结构域去除和其他调节过程的严格控制。越来越多的数据表明，切割还依赖于分泌酶底物的胞内膜运输及其在特定运输间隔内的分选。在Notch和APP的情况下，？？分泌酶介导的切割与底物从细胞表面的内吞作用和它进入内吞体内有关。我们已经发现，早期内吞体室的正确生物发生需要水通道蛋白的功能，为有效的分泌酶依赖的Notch运输和信号传递定义了一条专门的内体途径。在具体目标1中，我们建议进一步表征这种水通道蛋白在内体生物发生和Notch运输中的作用。这些研究将阐明细胞生物学方面的问题？？分泌底物运输及其与分泌底物的裂解、循环和降解的关系。在特定的目标2中，我们建议对参与Notch和其他分泌酶底物的细胞膜运输的新因素进行正向遗传筛选。这一筛选的初步结果已经被证明是非常有希望的，包括恢复了Notch细胞内运输的各个步骤所需的许多潜在的新基因。对其中几个新基因的进一步分析和分子克隆目前正在进行中。这个项目的主要目的是促进我们对分泌酶底物运输及其与肿瘤发生和神经退行性疾病中分泌酶依赖过程的相关性的理解。公共卫生相关性：被分泌酶切割的蛋白质，包括Notch受体和淀粉样前体蛋白，对发育信号和神经功能至关重要，它们的失调导致癌症和神经退行性疾病。这项研究计划试图确定控制？？的生产、运输和蛋白分解过程的细胞因素。偷偷袭击目标。这些研究可能导致识别新的蛋白质和细胞内通路，这些蛋白质和细胞内通路可以作为癌症和神经退行性疾病的治疗靶点。