Understanding the Molecular Mechanisms of Fibromuscular Dysplasia

项目总结 纤维肌肉发育不良(Fmd)是一种未被充分研究，有时甚至是致命的医学谜团，可导致动脉。 纤维化、狭窄、夹层、曲折、动脉瘤和闭塞，遍及全身。确诊时的平均年龄为50岁- 55岁和94%的人是女性。尽管它在女性中的患病率高达5%，但没有专门的治疗方法，而且 人们对其病因知之甚少。在媒体上，这种知识的缺乏，低估了流行率和 有时，致命的后果会导致口蹄疫被称为“不致命的罕见疾病”(《华尔街日报》，2009年6月27日)。 我们的团队是口蹄疫领域的世界领先者，他们加深了我们对其临床特征的了解。为了解决缺乏 为了了解其原因，我们在2013年启动了Define-FMD研究-一项大型的功能组学研究 口蹄疫的遗传学和分子基础。Define-FMD已经帮助提供了对 口蹄疫，表明它有一个复杂的(非孟德尔)遗传基础。在这里，我们提出了详细的功能和 机制研究以了解在Define-FMD研究中确定的FMD的首要原因候选因素-a 关键调控基因网络(RGN)我们称之为“FMD-RGN”。使用不同的方法，我们有 反复验证此RGN与FMD的关联，P值始终小于1 x 10-16。此外, 我们已经确定FMD-RGN的最重要的驱动因素之一是UBR4(泛素蛋白连接酶E3组分n- 认可4)。UBR4是FMD的有力的因果候选，我们已经证实它具有很强的影响 关于FMD-RGN中其他基因表达水平的调控。作为我们的总体目标，我们旨在确定 FMD-RGN对血管细胞和动脉表型的特异性影响，并了解UBR4在 管理FMD-RGN并导致FMD。·在具体目标1中，我们将对 UBR4和FMD-RGN对细胞表型的影响。我们将进行一系列体外研究，使用 UBR4基因敲除和过表达的人成纤维细胞了解该基因和FMD-1的作用 FMD中的RGN。·在特定目标2中，我们将描述细胞特异性Ubr4对体内心血管的影响 删除。我们将在血管内皮细胞、平滑肌细胞和成纤维细胞的小鼠身上进行一系列体内研究。 特定的Ubr4删除。我们将提供这些小鼠心血管表型的详细特征 LINES，包括组织病理学、原子力显微镜下的生物力学特性和使用液体的蛋白质组学 色谱串联质谱。·在具体目标3中，我们将进行进一步研究，以了解 表达UBR4的血管细胞在体内的去向和功能。我们将应用单细胞RNA测序和 其他尖端技术为新鲜获得的小鼠和人类动脉样本提供了体内决定性的 表达Ubr4的人血管细胞的特性及Ubr4缺失对细胞特异性表型的影响 在老鼠身上。总而言之，使用这些集成但独立的方法，这台R01将全面剖析分子 UBR4和FMD-RGN的作用机制，构建FMD血管病理生物学的整体功能图景。 作为1938年首次报道的一种疾病，我们认为这些关于口蹄疫的拟议研究势在必行，而且早就应该进行了。

PROJECT SUMMARY Fibromuscular dysplasia (FMD) is an understudied and sometimes fatal medical enigma that can cause arterial fibrosis, stenosis, dissection, tortuosity, aneurysm and occlusion, throughout the body. Mean age at diagnosis is 50- 55 yrs and 94% are female. Although it has a prevalence of up to 5% in females, there is no specific treatment, and very little is known about its etiology. In the press, this lack of knowledge, underappreciated prevalence and sometimes fatal outcomes have led to FMD being called “The Rare Disease That Isn’t” (WSJ, June 27, 2009). Our team, world leaders in FMD, have advanced our knowledge of its clinical features. To address the lack of understanding about its cause, in 2013 we initiated the DEFINE-FMD study - a large, functional ‘omics study of the genetic and molecular basis of FMD. Already, DEFINE-FMD has helped provide important insights into the cause of FMD, showing that it has a complex (non-Mendelian) genetic basis. Here, we propose detailed functional and mechanistic studies to understand a top causal candidate for FMD that was identified in the DEFINE-FMD study – a critical regulatory gene network (RGN) we refer to as the “FMD-RGN.” Using differing approaches, we have repeatedly validated the association of this RGN with FMD, with P values consistently less than 1 x 10-16. In addition, we have identified that one of the top key drivers of the FMD-RGN is UBR4 (ubiquitin protein ligase E3 component n- recognin 4). UBR4 is a strong causal candidate for FMD, and we have already confirmed that it exerts strong effects on modulating the expression levels of other genes in the FMD-RGN. As our overall goals we aim to determine the specific effects of the FMD-RGN on the vascular cell and arterial phenotypes, and to understand the role of UBR4 in governing the FMD-RGN and in causing FMD. • In Specific Aim 1 we will undertake detailed analyses of the impact of UBR4 and the FMD-RGN on the cellular phenotype. We will perform a series of in vitro studies using human fibroblasts with knockdown and overexpression of UBR4 to understand the role of this gene and the FMD- RGN in FMD. • In Specific Aim 2 we will characterize the in vivo cardiovascular effects of cell-specific Ubr4 deletion. We will perform a series of in vivo studies in mice with endothelial-, smooth muscle cell-, and fibroblast- specific Ubr4 deletion. We will provide a detailed characterization of the cardiovascular phenotypes of these mouse lines, including histopathology, biomechanical properties by atomic force microscopy, and proteomics using liquid chromatography tandem mass spectrometry. • In Specific Aim 3 we will perform further studies to understand the in vivo fate and function of vascular cells expressing UBR4. We will apply single cell RNA sequencing and other cutting edge techniques to freshly obtained mouse and human artery samples to provide a decisive in vivo characterization of human UBR4-expressing vascular cells, and the cell-specific phenotypic effects of Ubr4 deletion in mice. Collectively, using these integrated but independent approaches, this R01 will fully dissect the molecular mechanisms of UBR4 and the FMD-RGN, to build a holistic functional picture of the vascular pathobiology of FMD. As a disease first reported in 1938, we believe these proposed studies on FMD are imperative, and long overdue.