Evaluation of the differential roles of Bone Morphogenetic Proteins during vascular development

骨形态发生蛋白（BMPs）在血管系统的形成中起着至关重要的作用。事实上，BMP信号通路在发育过程中的内皮分化、静脉特化和血管生成中具有重要功能。在血管发育中特别重要的是BMP受体激活素样受体激酶1（Alk1），其几乎仅由内皮细胞表达，并且是血管重塑的关键调节剂。Alk1功能丧失导致血管发育缺陷，其特征为不成熟、扩张的血管易于形成动静脉畸形（AVM）。其他BMP受体Alk2和Alk3也已显示在血管生长和渗透性中具有重要作用。有趣的是，BMP受体的活性似乎是环境依赖性的，因为它们在某些条件下可以促进血管生成，而在其他情况下可以阻止血管生成。现在很清楚，BMP信号传导比以前认为的更复杂和动态调节。为了更精确地了解BMP信号的功能细节，重要的是要揭示它何时、何地以及如何动态传播，BMP信号的可视化是必不可少的。本提案的目标是评估BMP的信号传导如何在内皮细胞中传播以及BMP受体在血管发育期间的时空激活模式。这项研究计划将首先评估内皮细胞中单个BMP受体的信号传导。利用遗传学、蛋白质组学和细胞信号传导方法，我们将确定内皮细胞中每种I型BMP受体（Alk1、Alk2、Alk3）的关键信号传导特异性。研究计划的第二部分将涉及调查每个BMP受体在血管发育的特定阶段何时何地被激活。为此，我们已经产生了一个活的报告系统，以检测真实的时间BMP受体的激活。** * 目标1：评估内皮细胞中单个BMP受体（Alk 1、Alk 2和Alk 3）信号传导的功能后果 * 目标2：BMP信号传导报告基因的产生和验证：将产生和验证Alk 1和Alk 3报告基因的人类和小鼠版本，一旦激活，它们就会发出荧光。目的3：评价体内BMP受体信号传导：将产生表达BMP信号传导报告基因的转基因小鼠。将在血管发育期间评估报告构建体的时空激活。*这项研究计划产生的知识将产生一个全面的模型，如何以及何时产生BMP信号，调节和完成血管发育过程中。

Bone Morphogenetic Proteins (BMPs) play crucial roles in the formation of the vascular system. Indeed, the BMP signalling pathway has important functions in endothelial differentiation, venous specification, and angiogenesis, during development. Of particular importance in vascular development is the BMP receptor Activin-like receptor Kinase 1 (Alk1), which is almost exclusively expressed by endothelial cells, and is a critical regulator of vascular remodeling. Alk1 loss-of-function results in defective vascular development, characterized by immature, dilated vessels prone to forming arteriovenous malformations (AVM). Other BMP receptors, Alk2 and Alk3, have also been shown to have important roles in vascular growth and permeability. Interestingly, the activity of BMP receptors appears to be context-dependent, as they can promote angiogenesis under certain conditions while preventing it in other contexts.***It is now clear that BMP signalling is under more complex and dynamic regulation than previously thought. To understand the functional details of BMP signalling more precisely, it is important to reveal when, where, and how it is dynamically propagated, for which the visualization of BMP signalling is essential. The goal of the present proposal is to evaluate how the signalling of BMPs is propagated in endothelial cells and the spatio-temporal activation pattern of BMP receptors during vascular development.***This research program will first evaluate the signalling of individual BMP receptors in the endothelium. Using genetic, proteomics and cell signalling approaches, we will identify the key signalling specificities of each type I BMP receptor (Alk1, Alk2, Alk3) in endothelial cells. The second part of the research program will involve investigating where and when each BMP receptor is activated at specific stages of vascular development. For this, we have generated a live reporter system to detect the activation of BMP receptors in real time.******The following research projects will be developed:***Aim 1: Evaluate the functional consequences of the signalling of individual BMP receptors (Alk1, Alk2 and Alk3) in endothelial cells***Aim 2: Generation and validation of BMP signalling reporters: Human and mouse versions of Alk1 and Alk3 reporters, which become fluorescent once activated, will be produced and validated.***Aim 3: Evaluate BMP receptor signalling in vivo: Transgenic mice expressing BMP signalling reporters will be generated. Spatiotemporal activation of the reporter constructs will be assessed during vascular development.***The knowledge generated by this research program will to produce a comprehensive model of how and when the signalling of BMPs is generated, regulated and accomplished during vascular development.