ROLE OF APP-RELATED PROTEINS DURING NEURONAL MIGRATION

APP 相关蛋白在神经元迁移过程中的作用

• 批准号: 7099351
• 负责人: PHILIP F COPENHAVER
• 金额: $ 30.39万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7099351
• 关键词: Alzheimer' s disease; G protein; Manduca; amyloid proteins; aspartic endopeptidases; cell migration; cell motility; cell surface receptors; developmental neurobiology; disease /disorder model; enteric nervous system; gene expression; genetic translation; immunoprecipitation; ligands; neuronal guidance; neurons; neuropathology; peptide analog; protein protein interaction; protein structure function; video microscopy; video recording system

DESCRIPTION (provided by applicant): The long-term goals of this proposal are to determine the in vivo functions of proteins related to the amyloid precursor protein (APP) during normal development, and to gain insight into how perturbations of these functions may contribute to the pathology of Alzheimer's Disease (AD). AD is associated with the misregulated processing of APP by a combination of secretases, which results in the generation of excessive beta-amyloid fragments (Abeta) that can aggregate into amyloid plaques within the nervous system. Although Abeta has been shown to have neurotoxic effects, the normal functions of APP may also be disrupted by this process, contributing to the pathology of AD. A variety of studies in vitro have indicated that APP can act as a transmembrane receptor capable of regulating neuronal migration and outgrowth via several candidate intracellular signaling pathways. Particularly compelling are experiments showing that APP695 (considered a neuronal form of APP) binds directly to the heterotrimeric G protein Go-alpha and can regulate its activity. However, a functional analysis of this interaction has been precluded by complexities associated with the mammalian nervous system, and due to the lack of a biologically relevant assay for APP-Go-alpha signaling. To address this issue, a model system (the enteric nervous system or ENS of Manduca sexta) has been established, in which an identified set of migratory neurons (the EP cells) can be visualized and manipulated within the intact nervous system. The EP cells express an orthologue of APP (msAPPL, or APP-Like protein), which undergoes regulated trafficking and processing as the neurons develop. MsAPPL also interacts with Goa in their leading processes. Preliminary studies have shown that inhibiting msAPPL expression in the EP cells induces ectopic, inappropriate migration, consistent with a disruption of Go-alpha- mediated signaling events. The goals of this proposal are to test the hypothesis that msAPPL acts as a novel Go-alpha-coupled receptor: when activated by endogenous ligands the ENS, it regulates neuronal guidance in a Go-alpha-dependent manner. The nature of msAPPL-Go-alpha interactions in the migrating neurons and the role that secretases may play in modulating msAPPL-dependent aspects of migration will also be explored. Lastly, an expression cloning strategy will be employed to identify candidate ligands for msAPPL, using the ENS as an in vivo assay system. These studies will provide new insight into the molecular mechanisms of APP-related signaling in the developing nervous system, and they should serve as a foundation for future research into how disrupting the normal functions of APP may contribute to the pathology of AD.

描述（由申请人提供）：该提案的长期目标是确定正常发育过程中与淀粉样蛋白前体蛋白（APP）相关的蛋白质的体内功能，并深入了解这些功能的扰动如何有助于阿尔茨海默氏病的病理（AD）。 AD与分泌酶的结合结合了APP的处理不正，这导致产生过多的β-淀粉样蛋白片段（ABETA），这些片段可以汇总成神经系统中的淀粉样蛋白斑块。尽管已证明ABETA具有神经毒性作用，但APP的正常功能也可能因此过程而受到破坏，从而有助于AD的病理。各种体外研究表明，APP可以充当跨膜受体，能够通过几种候选细胞内信号通路来调节神经元迁移和出生。特别令人信服的是实验表明App695（被认为是APP的神经元形式）直接与异源三聚体G蛋白Go-Alpha结合并可以调节其活性。但是，与哺乳动物神经系统相关的复杂性排除了对这种相互作用的功能分析，并且由于缺乏针对App-Go-Alpha信号的生物学相关测定法。为了解决这个问题，已经建立了模型系统（肠神经系统或肠神经系统），其中可以在完整的神经系统中可视化并操纵一组已鉴定的迁移神经元（EP细胞）。 EP细胞表达APP的直系同源物（MSAPPL或类似App的蛋白质），随着神经元的发展，经过受调节的运输和处理。 MSAPPL还在其领先过程中与果阿互动。初步研究表明，EP细胞中抑制MSAPPL的表达会诱导异位，不当迁移，这与破坏α-α-介导的信号事件的破坏一致。该提案的目标是检验以下假设：MSAPPL充当一种新型的Go-Alpha耦合受体：当由内源配体激活ENS时，它以依赖Go-Alpha依赖性方式调节神经元引导。还将探索迁移神经元中MSAPPL-GO-ALPHA相互作用的性质以及分泌酶在调节MSAPPL依赖性方面的作用。最后，将采用表达克隆策略来使用ENS作为体内测定系统来识别MSAPPL的候选配体。这些研究将为发育中的神经系统中与应用程序相关的信号的分子机制提供新的见解，它们应该为将来研究的基础，以研究如何破坏APP的正常功能可能有助于AD的病理。