Molecular Mechanisms of Neuron Motility and Axon Guidance

神经元运动和轴突引导的分子机制

• 批准号: 10584813
• 负责人: John G Flanagan
• 金额: $ 166.54万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10584813
• 关键词: ASD patient; Affect; Alzheimer' s Disease; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Axon; Basement membrane; Behavior; Binding; Biological; Biological Models; Biological Process; Biology; Brain; Cell Surface Receptors; Cerebral cortex; Complex; Defect; Development; Developmental Process; Dimerization; Disease; Disparate; Distal; Elements; Exons; Failure; Family; Floor; Funding; Funding Agency; Gatekeeping; Genes; Goals; Grant; In Vitro; Individual; Laminin; Lead; Life; Ligand Binding; Ligands; Link; Maps; Mediating; Membrane; Messenger RNA; Modeling; Molecular; Mus; Nervous System; Neurodegenerative Disorders; Neurodevelopmental Disorder; Neurons; Pathogenicity; Pathway interactions; Pattern; Phosphorylation; Phosphorylation Site; Physiological; Protein Biosynthesis; Protein Region; Proteins; RNA; RNA-Binding Proteins; Radial; Regulation; Research; Role; Signal Pathway; Signal Transduction; Source; Spinal; Spinal Cord; System; Technology; Testing; Therapeutic Intervention; Translations; Up-Regulation; Vertebral column; Work; autism spectrum disorder; axon guidance; cell motility; design; extracellular; gene network; genome-wide; genome-wide analysis; in vivo; insight; interest; mRNA Translation; migration; nervous system development; neurodevelopment; neuronal patterning; novel; operation; receptor; risk variant; spatiotemporal; therapeutic target

The brain relies for its function on a precise and complex pattern of neuronal connections. The broad long-term goal of this project is to understand molecular mechanisms that set up this pattern of connections during development, and how aberrations of these mechanisms lead to Alzheimer’s Disease (AD) later in life. This project focuses particularly on RNA-based regulatory mechanisms. Key advantages of regulating mRNA translation via RNA-binding proteins (RBPs) are: (1) allowing protein synthesis to be locally regulated in specific subcellular regions where the proteins are needed, and (2) coordinately regulating expression of large networks of functionally related mRNAs. To understand the basic principles of axon guidance, a major model system has been spinal commissural axon guidance at the midline. Navigating this intermediate target requires axons to be attracted and then repelled, and the classic mechanism for this is the ‘Robo switch’ where repellent Robo receptors are upregulated in post-crossing axons; however, the extracellular signal and the mechanism by which it triggers this switch have remained unknown. We have now identified a highly novel mechanism for the Robo switch, involving extracellular ligand binding to the transmembrane Amyloid Precursor Protein (APP), which interacts intracellularly with the RBP CPEB4, to regulate Robo local translation in post-crossing axon segments. Having identified this novel APP-CPEB4 pathway, the proposed studies are designed to expand our understanding of the pathway’s molecular mechanisms and functions. In commissural axon guidance, expression of many proteins is known to be locally regulated in axon segments at the midline; the proposed studies of the APP-CPEB4 pathway are expected to identify coordinate regulation of a large gene network, bringing together many disparate past observations into a unifying model for this premier paradigm of axon guidance. In addition to axon guidance, preliminary studies reveal an overlapping yet distinct set of functions for the same molecular pathway in another major developmental model system, cortical neuron migration. The novel APP-CPEB4 pathway also has high relevance to disease: in addition to its involvement in developmental processes that lead to Autism Spectrum Disorder (ASD), the pivotal role of APP in our pathway gives it key relevance to AD. Regarding autism, abnormalities at the cortical neuron migration stage are believed to be a leading cause of ASD, and CPEB4 disruption in mouse cortex at this specific stage causes ASD-like behaviors. Moreover, all the components of our pathway from ligands to downstream targets have been implicated in ASD, though not previously linked in a unifying model. Regarding AD, the transmembrane structure of APP has long led to the idea that it is a cell surface receptor, yet despite decades of intensive work no instructive receptor role – where the spatiotemporal pattern of a ligand regulates a downstream developmental or physiological function – has yet been identified for APP. Now identifying a receptor role for APP – including a pathway from ligands through a signaling pathway to functional readouts – opens the door to a qualitatively new level of understanding APP, which is especially important since the challenges of therapeutically targeting Aβ place increased emphasis on understanding the roles of APP itself. Studies of our APP-CPEB4 pathway will uncover novel biological principles, while leading to enhanced understanding of mechanisms underlying neurodevelopmental and neurodegenerative disorders. Approaches include genome-wide target mRNA identification, and functional cellular and developmental studies in vitro and in vivo. Additionally, studies of signal transduction mechanisms in the novel APP-CPEB4 pathway will be essential to understand its operation and its potential for therapeutic intervention.

大脑依靠其功能基于神经元连接的精确和复杂的模式。该项目的广泛长期目标是了解开发过程中建立这种联系模式的分子机制，以及这些机制的畸变如何导致后来生活中的阿尔茨海默氏病（AD）。该项目尤其着重于基于RNA的调节机制。通过RNA结合蛋白（RBP）的RNA翻译的关键优势为：（1）允许蛋白质合成在需要蛋白质的特定亚细胞区域中进行局部调节，（2）（2）协同调节功能相关mRNA的大型网络的表达。为了了解Axon指导的基本原理，主要模型系统是中线的脊柱连击轴突指导。导航此中间目标需要吸引轴突然后驱逐，而经典的机制是“机器人开关”，在横断后轴突中，驱虫剂Robo接收器被上调。但是，细胞外信号及其触发此开关的机制尚不清楚。现在，我们已经确定了一种用于机器人开关的高度新颖机制，涉及细胞外配体与跨膜淀粉样蛋白前体蛋白（APP）结合，该蛋白（APP）与RBP CPEB4在细胞内相互作用，以调节后交叉轴突片段中的ROBO局部翻译。在确定了这种新颖的App-CPEB4途径之后，拟议的研究旨在扩大我们对途径分子机制和功能的理解。在轴突指导中，已知许多蛋白质的表达在中线的轴突段中受到局部调节。对APP-CPEB4途径的拟议研究有望识别大基因网络的坐标调节，将许多不同的过去观察结果汇总为这一首要轴突指导范式的统一模型。除轴突指导外，初步研究揭示了在另一个主要的发育模型系统皮质神经元迁移中，同一分子途径的重叠但不同的功能集。新型的APP-CPEB4途径也与疾病具有很高的相关性：除了它参与导致自闭症谱系障碍（ASD）的发育过程之外，APP在我们的途径中的关键作用还使其与AD的关键相关。关于自闭症，认为皮质神经元迁移阶段的异常被认为是ASD的主要原因，而在此特定阶段，小鼠皮层中的CPEB4破坏会导致类似ASD的行为。此外，ASD中暗示了我们从配体到下游目标的所有途径的所有组件，尽管以前没有在统一模型中链接。关于AD，APP的跨膜结构长期以来一直导致它是一种细胞表面受体，但是尽管有数十年的密集型工作没有指导性的受体角色 - 配体的空间时间模式调节了下游的发育或物理功能 - 尚未确定应用程序。现在，确定应用程序的受体角色 - 包括从配体到信号通路到功能读数的途径 - 打开了通往定性较新的理解应用水平的大门，这尤其重要，因为生物学上靶向Aβ的挑战的挑战增加了对理解应用程序本身的作用的重点。对我们的APP-CPEB4途径的研究将揭示新的生物学原理，同时提高对神经发育和神经退行性疾病的机制的理解。方法包括全基因组靶标mRNA鉴定以及体外和体内功能性细胞和发育研究。此外，对新型APP-CPEB4途径中信号转导机制的研究对于了解其运行及其治疗干预的潜力至关重要。