How Tetraspanins Regulate Vascular Morphogenesis

血管形态发生需要适当的内皮细胞（EC）粘附和迁移。 跨膜蛋白四跨膜蛋白在内皮细胞中大量且普遍存在。我们的 最近的发现表明，四跨膜蛋白 CD82 可以抑制新生血管形成 病理刺激。我们的研究还表明，这种四跨膜蛋白通过以下方式抑制新血管形成： 抑制 EC 运动，通过限制 EC 粘连来抑制 EC 运动，并限制 EC 通过促进细胞粘附分子 (CAM) 的内吞作用并防止 质膜上脂筏的聚集。明确、完整的机制 控制 CD82 介导的病理性血管生成和 EC 运动的抑制，然而，仍然 在分子、细胞和有机体水平上仍然很大程度上未知。 为了阐明 CD82 如何抑制新生血管形成，我们假设在细胞水平上， CD82 下调 EC 基质动态粘附，这是 EC 正常运动所必需的。 在分子水平上，CD82 通过以下方式降低 EC 表面的功能性细胞粘附蛋白： 改变膜脂的分子景观以及随后的内吞机制 EC。在这个项目中，我们将首先确定CD82选择性抑制的机制 病理性新生血管形成。我们将确定具体影响的 CD82 效应子 病理性新生血管形成，确定 CD82 是否限制血管生成信号 优先影响病理性新生血管形成，并评估CD82对EC的影响 主要影响病理性新生血管的事件。其次，我们将确定 CD82 通过检查细胞粘附分子改变细胞粘附分子运输的机制 CD82对其内吞作用、再循环和外泌体释放的影响。最后，我们将 通过评估 CD82 的活性来确定 CD82 如何组织 EC 的膜微域 CD82 去除后的鞘糖脂代谢酶、神经节苷脂的调节作用 膜微结构域，以及神经节苷脂在 CAM 运输和 CD82- 中的作用 介导抑制 EC 运动和病理性血管生成。因此，该项目的目标 是了解CD82如何在分子水平上选择性地抑制病理性血管生成， 细胞和有机体水平。 从这些研究中，我们将描述四跨膜蛋白调节血管的机制 形态发生，建立病理性血管生成和膜之间的新范式 微域组织，并揭示控制 EC 之间串扰的信号轴 运动和 EC 粘附。从深入的机理研究出发，我们将开发一个集成的 了解 CD82 的独特功能，这最终将导致开发 对抗病理性血管生成的治疗手段。

Vascular morphogenesis requires proper endothelial cell (EC) adhesion and migration. Transmembrane proteins tetraspanins are abundantly and ubiquitously present in endothelia. Our recent finding indicates that tetraspanin CD82 inhibits neovascularization in response to pathological stimuli. Our study also revealed that this tetraspanin inhibits neovascularization by restraining EC movement, restrains EC movement by confining EC adhesions, and confines EC adhesion by facilitating the endocytosis of cell adhesion molecules (CAMs) and preventing the aggregation of lipid rafts at the plasma membrane. The explicit and complete mechanisms that govern CD82-mediated inhibitions of pathological angiogenesis and EC movement, however, still remain largely unknown at the molecular, cellular, and organism levels. To elucidate how CD82 inhibits neovascularization, we hypothesize that, at the cellular level, CD82 down-regulates the dynamic EC-matrix adhesion, which is needed for proper EC movement. At the molecular level, CD82 reduces the functional cell adhesion proteins at the EC surface by altering the molecular landscape of membrane lipids and subsequently the endocytic machinery of ECs. In this project, we will first determine the mechanism by which CD82 selectively restrains pathological neovascularization. We will identify the CD82 effecter(s) that specifically affects pathological neovascularization, determine if CD82 confines angiogenic signaling that preferentially affects pathological neovascularization, and assess the effect of CD82 on the EC event(s) that mainly affects pathological neovascularization. Secondly, we will determine the mechanism by which CD82 alters the trafficking of cell adhesion molecules by examining the effects of CD82 on their endocytosis, recycling, and exosomal release in ECs. Finally, we will determine how CD82 organizes the membrane microdomains of ECs by assessing the activities of glycosphingolipid-metabolic enzymes upon CD82 removal, the regulatory effects of gangliosides on membrane microdomains, and the roles of gangliosides in CAM trafficking and in CD82- mediated inhibitions of EC movement and pathological angiogenesis. Thus, the goal of this project is to understand how CD82 selectively restrains pathological angiogenesis at the molecular, cellular, and organism levels. From these studies, we will delineate the mechanisms by which tetraspanins regulate vascular morphogenesis, establish a novel paradigm between pathological angiogenesis and membrane microdomain organization, and reveal the signaling axis that governs the crosstalk between EC movement and EC adhesion. From the in-depth mechanistic study, we will develop an integrated understanding of the unique features of CD82, which will ultimately lead to the development of therapeutic mean against pathological angiogenesis.