Notch mediated arterial-venous specification in the mammalian cerebrovasculature

描述（由申请人提供）：血管系统通过建立常规血管组织以确保适当的组织灌注，在健康和疾病中发挥主要作用。动脉将血液从心脏输送到毛细血管，从而逐渐缩小血管口径。Captured，动脉-静脉（AV）界面，其中发生营养物质和废物与组织的交换，必然是最小直径的血管。毛细血管后的小静脉依次连接较宽的静脉，使血液返回心脏。在发育过程中，Notch信号传导通过促进动脉相对于静脉EC的命运，在从内皮细胞（EC）组装第一动脉/静脉对期间已经成为AV特化的关键介体。Notch基因表达在出生后血管内皮中维持，表明Notch在建立和/或维持出生后AV组织中具有作用。出生后不久，未成熟的脑血管系统经历形态发生的动态时期，在此期间，动脉/毛细血管/静脉的精细组织从宽口径AV连接的原始丛形成。目前，人们对确保大脑中这种AV组织的遗传控制知之甚少。我们假设Notch信号通过指示单个EC从未成熟AV连接到动脉与静脉的分配来管理未成熟哺乳动物血管系统中的AV组织。在目标1中，我们假设未成熟脑血管丛内的单个EC被分配到动脉与静脉，从而允许AV界面处的血管狭窄。为了全面分析脑内AV组织，我们将：1）随着时间的推移，检查AV标记物在未成熟AV连接内EC中的表达; 2）监测体内EC迁移。在目标2中，我们假设Notch的缺失促进静脉程序并增加EC从大脑中不成熟的AV连接分配到静脉。我们将废除Notch信号，特别是在未成熟的EC和分析表型的后果，涉及AV标志物的表达和EC迁移血管。在目标3中，我们假设激活的Notch促进动脉程序并增加EC从大脑中不成熟的AV连接分配到动脉。我们将在未成熟血管内皮中特异性激活Notch信号传导，并评估与AV标志物表达和EC分配至动脉与静脉相关的表型效应。在未成熟大脑中血管变窄和回路形成的动态期间，血管系统特别容易发生畸变和相关的神经损伤，强调了正确AV连接的必要性。这些研究将提供分子和细胞的决议对目前的观点出生后脑血管形态和开放的途径，为治疗应用。

DESCRIPTION (provided by applicant): The vasculature plays a principal role in health and disease, by establishing stereotypical vessel organization to ensure proper tissue perfusion. Arteries carry blood from the heart to capillaries, successively reducing vessel caliber. Capillaries, the arterial-venous (AV) interface where exchange of nutrients and waste with tissues occurs, are by necessity the smallest diameter vessels. Post-capillary venules join successively wider veins to return blood to the heart. During development, Notch signaling has emerged as a critical mediator of AV specification during assembly of the first artery/vein pair from endothelial cells (ECs), by promoting arterial over venous EC fate. Notch gene expression is maintained in postnatal vascular endothelium, suggesting that Notch has a role in establishing and/or maintaining postnatal AV organization. Shortly after birth, the immature brain vasculature undergoes a dynamic period of morphogenesis, during which a refined organization of arteries/capillaries/veins forms from a primitive plexus of wide-bore AV connections. Currently, little is known about the genetic controls to ensure such AV organization in the brain. We hypothesize that Notch signaling governs AV organization in the immature mammalian cerebrovasculature, by dictating the allocation of individual ECs from immature AV connections to artery vs. vein. In Aim 1, we hypothesize that individual ECs within the immature brain vascular plexus are allocated to artery vs. vein, thereby permitting vessel narrowing at the AV interface. Toward a comprehensive analysis of AV organization within the brain, we will: 1) examine, over time, AV marker expression in ECs within immature AV connections; 2) monitor EC migration in vivo. In Aim 2, we hypothesize that loss of Notch promotes a venous program and increases EC allocation to the vein from immature AV connections in the brain. We will abrogate Notch signaling specifically in immature ECs and analyze the phenotypic consequences, as relate to AV marker expression and EC migration in the cerebrovasculature. In Aim 3, we hypothesize that activated Notch promotes an arterial program and increases EC allocation to the artery from immature AV connections in the brain. We will activate Notch signaling specifically in immature vascular endothelium and assess phenotypic effects, as relate to AV marker expression and EC allocation to artery vs. vein. During this dynamic period of vessel narrowing and circuitry formation in the immature brain, the vasculature is particularly susceptible to aberrations and associated neurological impairments, underscoring the necessity for proper AV connectivity. These studies will provide molecular and cellular resolution toward the current view of postnatal cerebrovascular morphogenesis and open avenues for therapeutic application.