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病（AD）的病理学。 AD 与分泌酶组合对 APP 的加工失调有关，导致产生过量的 β-淀粉样蛋白片段 (Abeta)，这些片段可以在神经系统内聚集成淀粉样斑块。尽管 Abeta 已被证明具有神经毒性作用，但 APP 的正常功能也可能被这一过程破坏，从而导致 AD 的病理学。各种体外研究表明，APP 可以充当跨膜受体，能够通过几种候选的细胞内信号传导途径调节神经元迁移和生长。特别引人注目的是实验表明 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。然而，由于与哺乳动物神经系统相关的复杂性以及缺乏针对 APP-Go-alpha 信号传导的生物学相关测定，无法对这种相互作用进行功能分析。为了解决这个问题，建立了一个模型系统（肠神经系统或 Manduca sexta 的 ENS），其中可以在完整的神经系统内可视化和操纵一组已识别的迁移神经元（EP 细胞）。 EP 细胞表达 APP（msAPPL 或 APP 样蛋白）的直系同源物，随着神经元的发育，该蛋白会受到调节的运输和加工。 MsAPPL 还在其主导流程中与果阿进行互动。初步研究表明，抑制 EP 细胞中的 msAPPL 表达会诱导异位、不适当的迁移，这与 Go-alpha 介导的信号传导事件的破坏一致。该提案的目标是检验 msAPPL 作为一种新型 Go-α 偶联受体的假设：当被内源性配体 ENS 激活时，它以 Go-α 依赖性方式调节神经元引导。还将探讨迁移神经元中 msAPPL-Go-alpha 相互作用的性质以及分泌酶在调节迁移的 msAPPL 依赖性方面可能发挥的作用。最后，将使用 ENS 作为体内测定系统，采用表达克隆策略来鉴定 msAPPL 的候选配体。这些研究将为发育中的神经系统中 APP 相关信号传导的分子机制提供新的见解，并且它们应该为未来研究破坏 APP 的正常功能如何导致 AD 的病理学奠定基础。