EPHB4-RASA1 regulation of lymphatic vessel valve development and function

淋巴血管系统在组织间液和脂质的运输中起着至关重要的作用， 以及诱导脊椎动物适应性免疫反应。淋巴管的正常功能 血管系统依赖于腔内淋巴瓣 (LV)，促进淋巴液的推进流动 淋巴管中的淋巴液。左心室发育和功能缺陷导致累积 组织或体腔内淋巴液淤积，导致淋巴水肿、乳糜胸和乳糜性腹水。 从医学角度，了解调控发育的分子机制 左室的功能至关重要，但我们对这些机制的了解仍然有限。我们有重新 之前移植的RASA1，抑制细胞内Ras信号转导的激活 途径，是 LV 发育和维持所必需的。此外，还有人报道称 受体酪氨酸激酶 EPHB4 是 LV 发育所必需的。然而，精确的模式 RASA1 和 EPHB4 调节 LV 的分子机制尚不清楚。该组织的一个长期目标是 King实验室就是要了解Ras信号通路在不同生理系统中的作用 健康和疾病方面的问题。该应用程序的总体目标与这一长期目标一致 术语目标是了解 RASA1 如何调节 LV 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蛋白的输出 来自 LV 形成 (LVF) 淋巴内皮细胞 (LEC) 和成熟 LEC 的 IV 沉积在前- 分别是发育中和已建立的左心室小叶的细胞基质核心。这些的理由 研究表明，他们将了解 RASA1 和 EPHB4 调节的分子机制 LV的发育和功能。我们计划检验我们的中心假设，从而获得 本应用程序的目标是通过追求以下两个具体目标：在第一个目标中，我们将使用 不同的分子细胞生物学、小鼠遗传和生理学方法来了解分子 RASA1 缺失导致 LV 发育和维持失败的分子机制。在 第二个目标，我们将使用类似的方法来了解 EPHB4 在发育中的作用 LV 及其相关机制。由于采用了新颖的方法，所提出的研究具有创新性—— 采用的技术以及 EPHB4-RASA1 轴对于发育和发育至关重要的概念 LV 的功能是从 LVF LEC 和 LV LEC 输出胶原蛋白 IV。这些研究具有重要意义—— 其有潜力开发出预防和治疗左室异常的新疗法 在具有 RASA1 和 EPHB4 基因遗传突变的人类中。

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.