Endothelial cell autonomous mechanisms of blood vessel diameter control

摘要 血管对于将营养和氧气分配到我们身体的各个部位非常重要。分层 不同大小的血管的组织是其功能的关键。几种疾病会影响血液 血管拓扑和直径，导致人类血管畸形。此前的报告显示， 血管直径的增加可由内皮细胞数量的增加引起， 血管内壁我们在斑马鱼胚胎中建立了一种成像方法，使我们能够精确地 分析胚胎发育过程中内皮细胞的数量以及它们的形状和大小。 令人惊讶的是，我们发现最初内皮细胞的形状和大小对血管形成更重要， 直径控制比他们的数量和内皮细胞数量增加，只有在后期阶段的血管 畸形建立重要的是，我们还发现，内皮细胞的形状和大小受到影响， 导致血管畸形的几种不同基因的突变体。然而，到目前为止，还不知道这些 基因影响细胞的形状和大小，以及这将如何影响血管直径。本提案的目的是 通过分析影响细胞形状和大小的细胞和分子成分来解决这个问题。在 目的1我们将研究细胞骨架及其收缩特性如何影响细胞尺寸， 这可能对血管直径产生反馈。我们还将研究是否改变细胞骨架， 因此内皮细胞收缩性可以挽救血管畸形。在目标2中，我们计划审问 内皮细胞极性对血管直径影响内皮细胞顶端有一个，面向血液 血管腔和基底外侧膜域。目前，我们还不知道突变是如何导致血管 畸形改变了顶-底极性，以及这些变化如何影响血管直径。我们将 通过检查不同斑马鱼突变体的顶端和基底侧极性来测试这些可能性， 血管畸形我们还将研究改变顶侧-基底侧极性如何影响内皮细胞 细胞的形状和大小。最终，我们的目标是通过正常化， 顶-基底侧极性和内皮细胞收缩性，从而增加之前的内皮细胞形状 在内皮细胞数量上。

Abstract Blood vessels are important for the distribution of nutrients and oxygen to all parts of our bodies. A hierarchical organization of differently sized blood vessels is key for their functionality. Several diseases can affect blood vessel topologies and diameters, leading to vascular malformations in humans. Previous reports suggested that increases in blood vessel diameters can be caused by increases in endothelial cell numbers, the cells of the blood vessels’ inner lining. We established an imaging approach in zebrafish embryos that allows us to precisely analyze endothelial cell numbers in addition to their shapes and sizes during embryonic development. Surprisingly, we found that initially the shapes and sizes of endothelial cells were more critical for blood vessel diameter control than their numbers and that endothelial cell numbers increased only at later stages of vascular malformation establishment. Importantly, we also found that endothelial shapes and sizes were affected in mutants of several different genes causing vascular malformations. However, to date it is not known how these genes affect cell shapes and sizes and how this would impact blood vessel diameters. The aims in this proposal address this question by analyzing the cellular and molecular components influencing cell shapes and sizes. In aim 1 we will investigate how the cytoskeleton and its contractile properties affect cellular dimensions and how this might feedback on blood vessel diameters. We will also investigate whether changing the cytoskeleton and hence endothelial cell contractility can rescue vascular malformations. In aim 2 we plan to interrogate the influence of endothelial cell polarity on blood vessel diameters. Endothelial cells have an apical, facing the blood vessel lumen, and a basolateral membrane domain. At present, we do not know how mutations causing vascular malformations change apical-basal polarity and how these changes would affect blood vessel diameters. We will test for these possibilities by examining apical and basolateral polarity in different zebrafish mutants that develop vascular malformations. We will also investigate how changing apical-basolateral polarity will affect endothelial cell shapes and sizes in these mutants. Ultimately, we aim to reverse vascular malformations through normalizing apical-basolateral polarity and endothelial cell contractility and thereby endothelial cell shapes prior to increases in endothelial cell numbers.