Role of Connexin47 mutations in primary lymphedema

Connexin47 突变在原发性淋巴水肿中的作用

• 批准号: 8831729
• 负责人: JANIS M BURT
• 金额: $ 18.65万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-04 至 2017-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8831729
• 关键词: Ablation; Adult; Affect; Animal Model; Arteries; Blood Vessels; Cells; Chylothorax; Connexin 43; Connexins; Defect; Development; Dietary Fats; Disease; Disease model; Docking; Dominant-Negative Mutation; Effectiveness; Embryonic Development; Ensure; Family; Fluid Balance; Functional disorder; Future; Gap Junctions; Genes; Goals; Health; Human; Immune System Diseases; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Inherited; Intercellular Fluid; Knockout Mice; Knowledge; Lead; Life; Location; Lymph; Lymphatic; Lymphatic Diseases; Lymphatic Endothelial Cells; Lymphatic System; Lymphatic vessel; Lymphedema; Metabolic Diseases; Missense Mutation; Modeling; Molecular; Morphogenesis; Morphology; Mus; Mutate; Mutation; Nature; Normal tissue morphology; Pathway interactions; Persons; Phase; Phenotype; Physiological; Physiology; Play; Proteins; Reflux; Research Personnel; Role; Secondary to; Signal Transduction; Structure; Testing; Venous; Work; absorption; arteriole; base; disease phenotype; extracellular; immune function; insight; loss of function; loss of function mutation; mouse model; mutant mouse model; novel; novel strategies; null mutation; prevent; primary lymphedema; small molecule; theories

DESCRIPTION (provided by applicant): The goal of this project is to explore the idea that some forms of primary lymphedema are caused specifically by defective valve formation resulting from mutations in Connexin (Cx) genes. Lymphatic (Ly) system function is essential for normal tissue fluid balance, immune function, and absorption and transport of dietary fat, and valves ensure that lymph moves forward rather than abnormally collecting or refluxing. Defects of the Ly system, including those that may involve defective or incompetent valves, lead to a number of congenital and acquired disorders. Lymphedema, in particular, is a potentially debilitating disorder in which interstitial fluid abnormally accumulates and is estimated to affect as many as 140-250 million people worldwide. Despite progress in identifying key genes involved in Ly development, the molecular mechanisms controlling the morphogenesis of Ly valves remain poorly understood. Thus, increased knowledge about the molecular pathways functioning during Ly valve development provides an excellent opportunity for new approaches to prevent or treat lymphatic disorders such as lymphedema. Recently, a new key player in valve development was discovered: Cxs - a family of related proteins which assemble into gap junction intercellular channels, structures that allow for the direct transfer of small molecules between adjacent cells. Previous vascular work focused on the role of Cxs in the development, remodeling, and physiology of arteries and arterioles. However, we have discovered that three Cxs (Cx37, Cx43, and Cx47) are expressed in the Ly endothelial cells of developing Ly vessels and that these proteins become progressively enriched at Ly valves (and venous valves). Using global Cx knockout mice, Cx37 and Cx43 were shown to be critical for Ly valve formation. Although Cx47 was shown to be mutated in some families with primary lymphedema, nothing is known about the role of Cx47 in Ly development or function. Based on the location of the Cx47 missense mutations in highly conserved Cx extracellular loops, we propose that the mutations are dominant negative in nature and result in primary lymphedema through a combined inhibition of wild-type Cx47 and Cx43 (which colocalize at valves), leading to defective valve development. In this proposal, we will compare the effects, in mouse models, of a Cx47 null mutation and a putative Cx47 dominant negative mutation that causes lymphedema in humans. The effects of these mutations on Ly valve formation, Ly function, and development of lymphedema will be assessed in the mice. In addition, the effects of a combined null mutation of Cx47 and Cx43 will be determined as another test of the theory that both Cx47 and Cx43 must be inhibited for a severe disease phenotype. The mouse lines generated in this project will provide valuable new animal models for the study of primary lymphedema and allow for a better understanding of how Ly dysfunction initiates or contributes to disease. In addition, the mouse models will be useful for future studies aimed at identifying the local physiological conditions that contribute to secondary lymphedema.

描述（由申请人提供）：本项目的目标是探索某些形式的原发性水肿是由连接蛋白（Cx）基因突变导致的瓣膜形成缺陷引起的。淋巴（Ly）系统功能对于正常的组织液平衡、免疫功能以及膳食脂肪的吸收和运输至关重要，并且瓣膜确保淋巴向前移动而不是异常收集或堵塞。Ly系统的缺陷，包括可能涉及缺陷或功能不全的瓣膜的缺陷，导致许多先天性和获得性疾病。特别是淋巴水肿，是一种潜在的使人衰弱的疾病，其中间质液异常积聚，估计会影响 全世界有1.4 - 2.5亿人。尽管在确定参与赖氨酸发育的关键基因方面取得了进展，但控制赖氨酸瓣膜形态发生的分子机制仍然知之甚少。因此，关于在Ly瓣膜发育期间起作用的分子途径的知识的增加为预防或治疗淋巴系统疾病如水肿的新方法提供了极好的机会。最近，发现了瓣膜开发中的一个新的关键参与者：Cxs -一个相关蛋白质家族，其组装成间隙连接细胞间通道，允许相邻细胞之间直接转移小分子的结构。以前的血管工作集中在Cx在动脉和小动脉的发育、重塑和生理学中的作用。然而，我们已经发现三种Cx（Cx 37、Cx43和Cx47）在发育中的Ly血管的Ly内皮细胞中表达，并且这些蛋白质在Ly瓣膜（和静脉瓣膜）处逐渐富集。使用全局Cx敲除小鼠，Cx 37和Cx43被证明对Ly瓣膜形成至关重要。虽然Cx47在一些原发性水肿的家族中被证明是突变的，但关于Cx47在Ly发育或功能中的作用还一无所知。基于高度保守的Cx细胞外环中Cx47错义突变的位置，我们提出这些突变在本质上是显性负性的，并通过野生型Cx47和Cx43（共定位于瓣膜）的联合抑制导致原发性水肿，从而导致瓣膜发育缺陷。在这个建议中，我们将比较的影响，在小鼠模型中，一个Cx47无效突变和一个假定的Cx47显性负突变，导致水肿在人类。将在小鼠中评估这些突变对Ly瓣膜形成、Ly功能和水肿发展的影响。此外，将确定Cx47和Cx43的组合无效突变的影响，作为对严重疾病表型必须抑制Cx47和Cx43的理论的另一个检验。本项目中产生的小鼠品系将为原发性脑水肿的研究提供有价值的新动物模型，并允许更好地了解Ly功能障碍如何引发或促成疾病。此外，小鼠模型将有助于未来的研究，旨在确定当地的生理条件，有助于继发性水肿。