New Roles for VEGFR1 in Angiogenesis

摘要 血管内皮生长因子(VEGF)配体家族及其受体酪氨酸激酶家族， 包括在控制血管生长中发挥核心作用的VEGF-VEGFR超家族 (血管生成)在发育、成人生理学和70多种疾病中。VEGFs和VEGFR是 因此，许多高死亡率和高发病率疾病的关键治疗目标。然而，结果是 通过靶向血管内皮生长因子和血管内皮生长因子受体治疗疾病的尝试有多种。已经取得了一些成功 可见于癌症和视网膜病变的血管生成抑制；但在外周和冠状动脉疾病中， 十几项提供血管内皮生长因子的人体临床试验都未能增加血管生成和灌注量，尽管 临床前动物模型的成功。无法成功地将治疗从动物过渡到人类 说明我们对多配体、多受体的VEGF-VEGFR系统了解还不够。仅限 通过对复杂系统的定量理解，使用一个框架，在这个框架下，我们可以比较 通过有意义的方式，我们将能够成功地预测治疗情况。 到目前为止，大多数受体的研究只集中在内皮细胞表达的三种VEGFR中的一种， VEGFR2，而在大多数血管内皮细胞中强效表达的VEGFR1相对被忽视。 然而，我们最近的研究表明，质膜驻留形式的VEGFR1有两个 内皮细胞生物学中的重要作用：它通过磷酸化STAT3自身传递信号，独立于 VEGFR2激活；它隔离配体，阻止其从VEGFR2中释放，并调节VEGFR2信号。 我们称之为VEGFR1的“信号”作用和“诱饵”作用。既是配体隔离的诱饵角色 膜结合的(M)VEGFR1的信号转导作用可能与血管生成有关。我们假设 信号与诱骗信号的相对重要性取决于配体和受体的表达，以及对 受体交易和稳定性。在这项研究中，我们将使用一种综合的方法来结合 我们的实验室：计算模型；小鼠和人类内皮细胞培养试验；以及靶向治疗 对老鼠和人类的干预。这种集成的方法将使我们能够分离和量化信号 以及诱饵效应，并界定和提炼它们对血管生成的相对贡献。该项目的目标是 目的：(1)建立和验证mVEGFR1的第一个计算模型；(2)定义和量化信号和 MVEGFR1的诱骗作用；以及(3)预测和检验mVEGFR1的S作用在体内治疗中的作用。我们的 中心假设是，整合了mVEGFR1配体结合的预测性计算框架， 激活、转运、稳定和信号传递将确定实现治疗所需的调节 血管生成。这项研究的结果将是更好地了解mVEGFR1的生物学及其对 发展和疾病；我们的计算和实验相结合的方法将阐明 MVEGFR1比单独的计算或实验方法更完整。好了！

SUMMARY The Vascular Endothelial Growth Factor (VEGF) family of ligands, and their receptor tyrosine kinase family, comprise the VEGF-VEGFR superfamily that plays a central role in the control of blood vessel growth (angiogenesis) in development, in adult physiology, and in over 70 diseases. VEGFs and VEGFRs are therefore key therapeutic targets across many high-mortality and high-morbidity illnesses. However, the results of attempts to treat diseases by targeting VEGFs and VEGFRs have been mixed. Some successes have been seen in angiogenesis inhibition for cancer and retinopathy; but in peripheral and coronary artery diseases, over a dozen human clinical trials delivering VEGF have failed to increase angiogenesis and perfusion, despite success in preclinical animal models. This inability to successfully bridge treatment from animals to humans shows that we do not sufficiently understand the multi-ligand, multi-receptor VEGF-VEGFR system. Only through a quantitative understanding of the complex system, using a framework under which we can compare mouse and human in a meaningful way, will we be able to successfully make predictions regarding treatment. Most receptor work to date has focused on just one of the three VEGFRs expressed by endothelial cells, VEGFR2, while VEGFR1, which is robustly expressed in most endothelial cells, has been relatively ignored. However, our recent studies have shown that the plasma membrane-resident form of VEGFR1 has two important roles in endothelial cell biology: it transduces signals itself via phosphoSTAT3, independent of VEGFR2 activation; and it sequesters ligand, withholding it from VEGFR2 and modulating VEGFR2 signaling. We term these the `signaling' role and the `decoy' role of VEGFR1. Both the ligand-sequestering decoy role and signaling role of membrane-bound (m)VEGFR1 likely contribute to angiogenesis. We hypothesize that the relative importance of signaling vs decoy depends on ligand and receptor expression, and on the regulation of receptor trafficking and stability. In this study, we will use an integrative approach to combine the expertise of our labs: computational modeling; mouse and human endothelial cell culture assays; and targeted therapeutic interventions in mice and humans. This integrated approach will enable us to isolate and quantify the signaling and decoy effects, and to define and refine their relative contributions to angiogenesis. The project goals are to: (1) build and validate the first computational model of mVEGFR1; (2) define and quantify the signaling and decoy roles of mVEGFR1; and (3) predict and test the effect of mVEGFR1's roles on therapies in vivo. Our central hypothesis is that a predictive computational framework that integrates mVEGFR1 ligand-binding, activation, trafficking, stability, and signaling will identify the modulations needed to achieve therapeutic angiogenesis. The outcome of this study will be a better understanding of mVEGFR1 biology and its impact on development and disease; our combined computational and experimental approach will elucidate the roles of mVEGFR1 more completely than computational or experimental approaches alone. !