The Role of Semaphorins in Axon and Blood Vessel Guidance

描述(申请人提供)：成人神经系统的正常功能关键依赖于血管系统的适当结构和功能。血管为神经元提供氧气和营养，并保护它们免受毒素和病原体的伤害。神经反过来控制血管的扩张和收缩，也控制心率。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，神经和血管经常平行运行，在中枢神经系统中，神经活动和血管动力学紧密耦合。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)，曾经被认为是由固有的神经元缺陷引起的，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，但对于神经系统如何在发育过程中与血管系统如此紧密地结合在一起，我们知之甚少。在这个方案中，我们建立了一个简单的系统，使用发展中的小鼠体感觉外周靶神经作为模型来研究这一问题。在AIM1中，我们将剖析紧密神经/血管联系组织的分子机制，特别是最近发现的配体-受体对Sema3E-PELXIN-D1的作用。我们将应用体外分析和小鼠体内遗传学方法来研究Sema3E-Pelsin-D1信号在建立神经/血管联系中的作用。在目标2中，我们将识别和表征Sema3E-Pelsin-D1下游在神经元和内皮细胞中的细胞内信号机制。利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个潜在的介导Sema3E-Plexin-D1信号的候选基因。我们将研究它们在Sema3E-Plexin-D1信号转导中的作用，并比较在Sema3E介导的轴突引导和内皮细胞迁移中是否使用了类似的信号机制。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。这些结果还可能提高我们诊断、治疗和预防同时影响神经元和血管的神经疾病的能力，包括：周围神经病、阿尔茨海默病(AD)、肌萎缩侧索硬化症(ALS)和多发性硬化症(MS)。 公共卫生相关性：了解血管和神经系统之间的相互作用将促进几种神经疾病的诊断、治疗和预防，包括糖尿病神经病变和三叉神经痛。此外，新出现的证据表明，一些神经退行性疾病，如阿尔茨海默病、肌萎缩侧索硬化症(ALS)和多发性硬化症(MS)，曾经被认为主要是由固有的神经元缺陷引起的，实际上可能与血管异常有关。最后，由于在发育过程中控制血管生成的机制可能对肿瘤的新生血管至关重要，这项研究可能会对癌症的治疗产生直接影响。

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). PUBLIC HEALTH RELEVANCE: Understanding the interactions between vascular and nervous systems will advance the diagnosis, therapy, and prevention of several neurological diseases, including diabetic neuropathy and trigeminal neuralgia. Moreover, emerging evidence shows some neurodegenerative diseases, such as Alzheimer's disease, amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), that once were thought to be caused primarily by intrinsic neuronal defects, actually may be related to vascular abnormalities. Finally, since mechanisms that control angiogenesis during development are likely to be essential for neovascularization in tumors, this study may have a direct impact on cancer treatment.