The Role of Semaphorins in Axon and Blood Vessel Guidance

成人神经系统的正常功能主要依赖于血管系统的正常结构和功能。血管为神经元提供氧气和营养，保护它们免受毒素和病原体的侵害。神经，反过来，控制血管的扩张和收缩，以及心率。这种功能相互依赖的关键是神经系统和血管系统之间异常紧密的物理联系。在外周神经系统中，神经和血管通常平行运行，而在中枢神经系统中，神经活动和血管动力学是紧密耦合的。事实上，新出现的证据表明，一些神经退行性疾病，如阿尔茨海默病（AD）、肌萎缩侧索硬化症（ALS）和多发性硬化症（MS），曾经被认为是由内在神经元缺陷引起的，实际上是由血管异常引发和延续的。尽管神经系统和血管系统之间有这些重要的联系，但人们对神经系统在发育过程中如何与血管系统如此紧密地联系在一起知之甚少。在本提案中，我们建立了一个简单的系统，以发育中的小鼠体感外周目标神经支配为模型来研究这个问题。在Aim1中，我们将剖析紧密神经/血管关联组织的分子机制，特别是关注最近发现的配体-受体对Sema3E-Pelxin-D1的作用。我们将采用体外实验和体内小鼠遗传学方法来解决Sema3E-Pelxin-D1信号在建立神经/血管关联中的功能。在Aim 2中，我们将识别和表征Sema3E-Pelxin-D1下游在神经元和内皮细胞中的细胞内信号传导机制。使用一种新的基于图像的RNAi全基因组筛选，我们已经确定并验证了几种介导Sema3E-Plexin-D1信号传导的潜在候选物质。我们将描述它们在Sema3E- plexin - d1信号传导中的作用，并比较Sema3E介导的轴突引导和内皮细胞迁移中是否使用类似的信号传导机制。总之，这些拟议的实验将揭示神经血管相互作用的细胞和分子机制。这些结果也可能提高我们诊断、治疗和预防影响神经元和血管的神经系统疾病的能力，包括：周围神经病变、阿尔茨海默病（AD）、肌萎缩侧索硬化症（ALS）和多发性硬化症（MS）。

DESCRIPTION (provided by applicant): The normal functioning of the adult nervous system relies critically on the proper structure and function of the vascular system. Blood vessels provide neurons with oxygen and nutrients and protect them from toxins and pathogens. Nerves, in turn, control blood vessel dilation and contraction and also heart rate. Key to this functional interdependence is an extraordinarily tight physical association between nervous and vascular systems. In the periphery, nerves and vessels often run parallel to one another and in the central nervous system neural activity and vascular dynamics are tightly coupled. Indeed, emerging evidence shows that some neurodegenerative diseases, such as Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), once thought to be caused by intrinsic neuronal defects, are in fact initiated and perpetuated by vascular abnormalities. Despite these important connections between the nervous and vascular systems, little is known about how the nervous system becomes so closely aligned with the vascular system during development. In this proposal, we have established a simple system using developing mouse somatosensory peripheral target innervation as a model to study this question. In Aim1, we will dissect the molecular mechanisms underlying the organization of the tight nerve/vessel association, particularly focusing on the role of a recently identified ligand-receptor pair, Sema3E-Pelxin-D1. We will apply both in vitro assays and in vivo mouse genetics approaches to address the function of Sema3E-Pelxin-D1 signaling in establishing the nerve/vessel association. In Aim 2, we will identify and characterize the intracellular signaling mechanisms downstream of Sema3E-Pelxin-D1 in neurons and endothelial cells. Using a novel image-based RNAi genome-wide screen, we have identified and validated several potential candidates mediate Sema3E-Plexin-D1 signaling. We will characterize their roles in Sema3E-Plexin-D1 signaling and compare whether similar signaling mechanisms are used in Sema3E -mediated axon guidance and endothelial cell migration. Together, these proposed experiments will uncover cellular and molecular mechanisms underlying neuro-vascular interactions. These results may also improve our ability to diagnose, treat, and prevent neurological disorders that affect both neurons and vessels, including: peripheral neuropathies, Alzheimer's Disease (AD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS).