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重要作用。事实上，BMP信号通路在发育过程中对内皮分化、静脉规范和血管生成具有重要作用。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)，它几乎只由内皮细胞表达，是血管重塑的关键调节因子。Alk1功能丧失导致血管发育缺陷，其特征是未成熟、扩张的血管容易形成动静脉畸形(AVM)。其他BMP受体Alk2和Alk3也被证明在血管生长和通透性方面发挥重要作用。有趣的是，BMP受体的活性似乎与环境有关，因为它们可以在某些条件下促进血管生成，而在其他环境中阻止血管生成。*现在很明显，BMP信号受到比之前认为的更复杂和动态的调节。为了更准确地了解BMP信令的功能细节，揭示其动态传播的时间、地点和方式是很重要的，对BMP信令的可视化是必不可少的。本研究的目的是评估BMP信号如何在血管内皮细胞中传播，以及BMP受体在血管发育过程中的时空激活模式。*本研究计划将首先评估单个BMP受体在内皮细胞中的信号传递。利用遗传学、蛋白质组学和细胞信号传递的方法，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，我们开发了一个实时报告系统来实时检测BMP受体的激活。*将开展以下研究项目：*目标1：评估单个BMP受体(Alk1、Alk2和Alk3)信号在内皮细胞中的功能后果*目标2：BMP信号报告的产生和验证：人和小鼠版本的Alk1和Alk3一旦激活就会变成荧光，并得到验证。*目标3：评估体内的BMP受体信号：将产生表达BMP信号报告的转基因小鼠。报告结构的时空激活将在血管发育过程中进行评估。*这项研究计划产生的知识将产生一个全面的模型，说明BMP信号是如何以及何时在血管发育过程中产生、调节和完成的。

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.