VEGFR Signaling Controls Lymphatic Junctions

先天性水肿是由遗传性基因突变引起的， 血管系统，并导致四肢肿胀，毁容，蜂窝组织炎，并增加对MRSA的敏感性 皮肤感染和败血症。先天性水肿也是淋巴管畸形的合并症， 其他常见综合征（如努南综合征）。最常见的基因突变导致先天性 水肿是VEGFR 3基因中的杂合失活突变，导致米尔罗伊病。而 VEGFR 3作为诱导淋巴管生成的主要受体已被广泛研究，实际上没有什么是 关于VEGFR 3如何调节淋巴脉管系统的生理功能的已知。因此 Milroy病的发病机制仍然未知，禁止药物治疗的发展。患者 具有VEGFR 3先天性突变的患者具有小腿水肿，并且在淋巴管造影成像时， 发现他们的淋巴管不能吸收任何来自淋巴管的示踪剂。这里有 开发了一种小鼠模型，其中VEGFR 3基因可以特异性地从淋巴细胞中缺失， 了解其生理功能。我们的初步数据显示， 对毛细淋巴管重塑其连续细胞-细胞连接的能力产生负面影响， 拉链，变成不连续的大开口的连接处，称为纽扣。淋巴结的连接重建 毛细血管是一个相对较新的生物学过程，人们对其了解甚少，但它依赖于粘附连接 蛋白质，VE-钙粘蛋白，我们的实验室在这方面有专长。重要的是，按钮连接被认为是 能从氚中吸收液体我们的初步数据确定VEGFR 3作为一种新的调节剂， 毛细淋巴管连接重塑以形成纽扣连接。我们将联合收割机将这种小鼠模型与细胞 培养和生理学方法来研究VEGFR 3在淋巴管系统中的作用， 具体目标。在目标1中，我们将评估毛细淋巴管重塑其连接的能力， 在出生后的不同时间点缺乏VEGFR 3。我们还将研究是否需要VEGFR 3 不仅用于形成钮扣结，而且用于这些特殊结的终身维护。淋巴 将在体内评估血流，以确定纽扣连接的丧失如何影响生理性间质液 吸收在目标2中，我们将研究调节按钮连接形成的下游细胞信号， 使用各种方法确定所涉及的信号通路。这些目标的实现将 鉴定VEGFR 3控制淋巴结重塑的新信号通路， 毛细淋巴管吸收液体。这项工作将显著影响先天性心脏病患者 通过提供对疾病发病机制的机械见解， 开发药物治疗。

Congenital lymphedema is caused by inherited gene mutations that impair the functioning of the lymphatic vasculature and lead to swelling of the limbs, disfigurement, cellulitis, and increased susceptibility to MRSA infections of the skin and sepsis. Congenital lymphedema is also a comorbidity of lymphatic malformations and other common syndromes (e.g. Noonan). The most common gene mutation that causes congenital lymphedema is a heterozygous inactivating mutation in the VEGFR3 gene that causes Milroy’s disease. While VEGFR3 has been widely studied as the main receptor that induces lymphangiogenesis, virtually nothing is known about how VEGFR3 regulates physiological functions of the lymphatic vasculature. Thus, the pathogenesis of Milroy’s disease remains unknown, prohibiting the development of drug therapies. Patients with congenital mutations in VEGFR3 have lower leg lymphedema and upon lymphoscintigraphy imaging it is revealed that their lymphatic vessels are unable to absorb any tracer from the interstitium. Here, we have developed a mouse model in which the VEGFR3 gene can be deleted specifically from the lymphatic vasculature to understand its physiological functions. Our preliminary data show that loss of VEGFR3 negatively affects the ability of lymphatic capillaries to remodel their continuous cell-cell junctions, reminiscent of zippers, into discontinuous wide-open junctions called buttons. Junctional remodeling in the lymphatic capillaries is a relatively new biological process that is poorly understood but relies on the adherens junction protein, VE-cadherin, in which our laboratory has expertise. Importantly, the button junctions are thought to enable fluid absorption from the interstitium. Our preliminary data identify VEGFR3 as a novel regulator of lymphatic capillary junction remodeling to form button junctions. We will combine this mouse model with cell culture and physiological approaches to investigate the role of VEGFR3 in the lymphatic vasculature in the following specific aims. In Aim 1, we will assess the ability of lymphatic capillaries to remodel their junctions in the absence of VEGFR3 at various timepoints after birth. We will also investigate whether VEGFR3 is required not only for button junction formation, but also for the lifelong maintenance of these special junctions. Lymph flow will be assessed in vivo to determine how the loss of button junctions affects physiological interstitial fluid absorption. In Aim 2, we will investigate the downstream cell signals that regulate button junction formation and identify the signaling pathways involved using a variety of approaches. The completion of these aims will identify a new signaling pathway by which VEGFR3 controls lymphatic junction remodeling to enable interstitial fluid absorption by the lymphatic capillaries. This work will significantly impact patients with congenital lymphedema by providing mechanistic insight into the pathogenesis of the disease, opening the door to developing pharmacological treatments.