Notch Signaling in Vascular Development and Homeostasis

描述（由申请人提供）：我们的长期目标是全面了解血管形成所需的分子程序。遗传和细胞生物学数据的结合已经确定了Notch信号在血管形态发生中的关键作用。然而，关于Notch在血管发育和分化中的细胞作用的具体机制尚不清楚。缺失Notch 1会导致早期胚胎死亡（E.9.5），并伴有多种缺陷，包括心脏和血管的改变。为了详细了解Notch1在血管室中的作用，我们使用Cre-lox策略创建了一个内皮细胞特异性缺失Notch1的小鼠模型。与完全缺失的小鼠一样，这只小鼠在E9.5-10.5之间因血管系统崩溃而死亡，但没有表现出整体失活后的躯体中胚层缺陷和心脏特征。突变胚胎表现为先天性主动脉分支缺陷、主动脉腔缩小、动脉瘤、动静脉分流和血管分支失调。我们还生成了一个可诱导的Cre-lox小鼠，并随后在发育后期删除了Notch。有趣的是，在E10.5处消融Notch会导致E13.5处出血和死亡。此外，Notch在E15.5位点的缺失也会导致多种出血事件，并在出生时致死性。这些发现支持并扩展了我们对Notch的理解，并进一步强调了该信号通路在后期血管稳定和成熟过程中的精细需求。我们目前的重点是在细胞水平上获得Notch功能的机制理解，并建立Notch信号通路下游这些作用的分子联系。通过多种小鼠模型和体外方法，我们提出：(1)了解Notch1在血管发育过程中的作用机制；(2)探索Notch1在成年血管稳态和病理状态中的作用；(3)评估Notch1配体Jagged1在发育过程中的作用。血管形态发生的分子作图对于理解血管如何形成至关重要。在发育过程中发生的许多事件在成人新生血管生成和血管修复的情况下重演。因此，这些信息对于产生新的和更有效的治疗方法至关重要，这些治疗方法将能够在病理条件下操纵血管功能。

DESCRIPTION (provided by applicant): Our long-term goal is to gain a comprehensive understanding of the molecular programs required for the formation of blood vessels. A combination of genetic and cell biological data has established a critical role for Notch signaling in vascular morphogenesis. However, concrete mechanistic insight into Notch's cellular effects in vascular development and differentiation is still far reached. Deletion of Notch 1 results in early embryonic lethality (E.9.5) with multiple defects, including alterations in the heart and vessels. To gain a detailed understanding of Notch1 effects in the vascular compartment, we have generated a mouse model with endothelial-cell specific deletion of Notch1 using a Cre-lox strategy. As in the full deletion, this mouse dies between E9.5-10.5 from collapse of the vascular system, but does not exhibit somitic mesodermal defects and cardiac features seen after global inactivation. Mutant embryos displayed congenital aortic branch defects, reduced aortic lumen, aneurisms, arterial-venous shunts and deregulated vascular branching. We also generated an inducible Cre-lox mouse and subsequently deleted Notch at later developmental time points. Interestingly, ablation of Notch at E10.5 results in hemorrhage and lethality at E13.5. Furthermore, deletion of Notch at E15.5 also leads to multiple hemorrhagic events with lethality at birth. These findings support and expand our understanding of Notch and further highlight the exquisite requirement of this signaling pathway during vascular stabilization and maturation at later time-points. Our current focus is to gain a mechanistic understanding of Notch function at the cellular level and to establish the molecular links of these effects downstream of the Notch signaling pathway. By using a variety of mouse models and in vitro approaches, we propose: (1) to gain a mechanistic understanding of Notch1's effects during vascular development, (2) to explore the contribution of Notch1 in the homeostasis of adult vessels and in pathological conditions, and (3) to evaluate the contribution of Notch-ligand Jagged1 during development. The molecular mapping of vascular morphogenesis is critical to understanding how vessels are formed. Many of the events that take place during development are recapitulated in situations of neoangiogenesis and vascular repair in the adult. Thus, this information is central to the generation of novel and more effective therapies that will enable manipulation of vascular function during pathological conditions.