EPHB4-RASA1 regulation of lymphatic vessel valve development and function

淋巴管系统在间质液体和脂质的运输中起着至关重要的作用， 以及在脊椎动物中诱导适应性免疫反应。淋巴管的正常功能 血管系统依赖于腔内淋巴瓣(LV)，它促进血管的推进流动 收集淋巴管中的淋巴液体。左心室发育和功能缺陷导致心力衰竭。 淋巴充盈组织或体腔内的淋巴，导致淋巴水肿、乳糜胸和乳糜性腹水。 从医学角度，了解调节发育的分子机制 LV的功能是至关重要的，但我们对这些机制的了解仍然有限。我们已经重新- 先前移植了RASA1，它抑制了细胞内RAS信号转导的激活 途径，是左室发育和维持所必需的。此外，其他人也报告说 受体酪氨酸激酶EphB4是左心室发育所必需的。然而，精确的运动-- RASA1和EphB4调节LV的分子机制尚不清楚。中国的长期目标是 King实验室正在研究RAS信号通路在不同生理系统中的作用。 健康和疾病方面的主题。这个应用程序的总体目标与这一长期一致- 学期目标是了解RASA1如何调节左心室的发育和功能。我们的中央 假设RASA1通过与EphB4的物理相互作用促进胶原的输出 IV从LV形成(LVF)淋巴管内皮细胞(LEC)和成熟LEC中沉积。 分别为发育中和已建立的左心室叶的微细胞基质核心。这样做的理由是 研究表明，它们将揭示RASA1和EphB4调控的分子机制 LV的发展和功能。我们计划测试我们的中心假设，从而实现 通过追求以下两个具体目标来实现此应用程序的目标：在第一个目标中，我们将使用 不同的分子细胞生物学、小鼠遗传学和生理学方法来理解分子生物学和分子生物学。 RASA1缺失导致LV发育和维持失败的机制。在 第二个目标，我们将使用类似的方法来理解EphB4在 LV及其涉及的机制。拟议的研究具有创新性，因为方法新颖-- 所采用的技术和概念，即EphB4-RASA1轴对于发育和 LV从LVF LEC和LV LEC输出IV型胶原的功能。这些研究具有重要意义，因为- 它们有可能导致预防和治疗左心室畸形的新疗法的原因 在RASA1和EphB4基因发生遗传突变的人类中。

The lymphatic vascular system plays an essential role in the transport of interstitial fluid and lipids, and in the induction of adaptive immune responses in vertebrates. Normal functioning of the lymphatic vascular system depends upon intraluminal lymphatic valves (LV) that facilitate propulsive flow of lymph fluid in collecting lymphatic vessels. Defects in LV development and function results in accumu- lation of lymph in tissues or body cavities resulting in lymphedema, chylothorax and chylous ascites. From a medical perspective, understanding the molecular mechanisms that regulate the development and function of LV is critical, yet our knowledge of these mechanisms remains limited. We have re- ported previously that RASA1, which inhibits activation of the intracellular Ras signal transduction pathway, is required for the development and maintenance of LV. In addition, others have reported that the receptor tyrosine kinase, EPHB4, is required for LV development. However, the precise mo- lecular mechanisms by which RASA1 and EPHB4 regulate LV are unknown. A long-term goal of the King laboratory is to understand the role of the Ras signaling pathway in different physiological sys- tems in health and disease. The overall objective of this application, which is consistent with this long- term goal, is to understand how RASA1 regulates the development and function of LV. Our central hypothesis is that RASA1, through physical interaction with EPHB4, promotes the export of collagen IV from LV-forming (LVF) lymphatic endothelial cells (LEC) and mature LEC for deposition in the ex- tracellular matrix core of developing and established LV leaflets respectively. The rationale for these studies is that they will inform upon the molecular mechanisms by which RASA1 and EPHB4 regulate the development and function of LV. We plan to test our central hypothesis and, thereby, attain the objective of this application by pursuing the following two specific aims: In the first aim, we will use different molecular cell biologic, mouse genetic, and physiological approaches to understand the mo- lecular mechanism by which RASA1 loss results in failed development and maintenance of LV. In the second aim, we will use similar approaches to understand the role of EPHB4 in the development of LV and the mechanisms involved. The proposed studies are innovative because of the novel method- ologies employed and the concept that an EPHB4-RASA1 axis is essential for the development and function of LV acting to export collagen IV from LVF LEC and LV LEC. The studies are significant be- cause of their potential to lead to new therapies for the prevention and treatment of LV abnormalities in humans with inherited mutations in RASA1 and EPHB4 genes.