Regulation of TGF-beta Receptor-dependent Vascular Disease

这个实验室的长期目标是了解内皮细胞(ECs)调节血管稳定性和动态平衡的过程。我们的重点是了解转化生长因子-β受体ALK1和它的辅助受体endoglin之间的功能关系。这些分子是血管生成和伤口愈合的重要调节因子，是血管疾病遗传性出血性毛细血管扩张症(HHT)的靶基因。我们将检验这一假设，即endoglin通过一种新的Smad非依赖机制在内皮细胞中传递转化生长因子-β受体信号。我们的研究表明，Endoglin被ALK1磷酸化，我们假设Alk1调节Enoglin？S对内皮细胞中焦点黏附重组、细胞骨架结构和迁移的影响。为了了解这一新的endoglin信号通路及其在血管系统中的相关性，本方案的目的是：特定的目标1：检测转化生长因子-β受体介导的endoglin磷酸化的后果，以确定该途径如何调节EC的功能。研究将集中在内源性S胞浆结构域介导的蛋白-蛋白相互作用中的作用，重点是EC局部黏附组装、小管形成、转化生长因子-β受体亚细胞定位和EC特异性细胞间信号的调节。具体目标2：研究EC靶向表达endoglin CD突变体在卵黄囊血管系统中的后果。这一目标将强调胞浆结构域依赖对EC小管生成和血管生成重建的影响，并强调用于目标1的终点。这些研究结果将阐明内源性S调控内皮细胞内在功能的机制，以及在体卵黄囊血管内EC启动的细胞间信号。 具体目标3：描述在FVB：Eng+/-小鼠模型中观察到的血管异常。这一目标建立在新的初步数据基础上，这些数据表明，在FVB小鼠遗传背景上表达的杂合子Eng+/-构成了一种潜在的新的和有用的HHT血管畸形模型。我们将研究FVB：Eng+/-血管系统的结构和生化特性，以了解其血管畸形的基础。这个模型将被用来测试EC表达的转基因endoglin是否足以挽救血管缺陷。我们提出的Enoglin功能的转基因、遗传和生化模型将使我们更深入地理解转化生长因子-β受体依赖的内皮细胞增殖、黏附、小管形成和血管生成重塑的新机制，最终建立和维持血管完整性。拟议的研究与正常的血管功能高度相关，并将阐明endoglin在成人发病的血管疾病中的作用。

The long-term goal of this laboratory is to understand the processes by which endothelial cells (ECs) regulate vessel stability and homeostasis. Our focus is to understand the functional relationship between the TGF-beta receptor ALK1 and its co-receptor, endoglin. These molecules are important regulators of angiogenesis and wound healing, and are the target genes for the vascular disease hereditary hemorrhagic telangiectasia (HHT). We will test the hypothesis that endoglin transduces TGF-beta receptor signals in endothelial cells via a novel Smad-independent mechanism. Our studies demonstrate that endoglin is phosphorylated by ALK1, which we hypothesize regulates endoglin?s effects on focal adhesion re-organization, cytoskeletal architecture, and migration in ECs. To understand this novel endoglin signaling pathway and its relevance in the vasculature, the aims of this proposal are: Specific Aim 1: Examine the consequences of TGF-beta receptor-mediated phosphorylation of endoglin to determine how this pathway regulates EC function. Studies will focus on the role of putative protein-protein interactions mediated by endoglin?s cytosolic domain, emphasizing the regulation of EC focal adhesion assembly, tubulogenesis, TGF-beta receptor subcellular localization, and EC-specific intercellular signals. Specific Aim 2: Examine the consequences of EC-targeted expression of endoglin CD mutants in the yolk sac vasculature. This aim will emphasize cytosolic domain-dependent effects on EC tubulogenesis and angiogenic remodeling, and emphasize the endpoints used for Aim 1. The results obtained in these studies will elucidate the mechanism underlying endoglin?s regulation of intrinsic EC function as well as EC-initiated intercellular signals within the yolk sac vasculature in vivo. Specific Aim 3: Characterize the vascular abnormalities observed in the FVB:eng+/- mouse model. This aim builds on new preliminary data which suggests that the heterozygous eng+/- expressed on the FVB mouse genetic background constitutes a potentially novel and useful model of HHT vascular malformation. We will study the structural and biochemical properties of the FVB:eng+/- vasculature in order to understand the basis for its vascular malformations. This model will then be used to test whether EC-expressed transgenic endoglin is sufficient to rescue the vascular deficiencies. Our proposed mouse transgenic, genetic, and biochemical models of endoglin function will lead to a deeper understanding of novel mechanisms of TGF-beta receptor-dependent regulation of EC proliferation, adhesion, tubulogenesis, and angiogenic remodeling that culminate in the establishment and maintenance of vessel integrity. The proposed studies are highly relevant to normal vascular function, and will elucidate endoglin's role in adult-onset vascular diseases.