Distinct Pathways of VPF/VEGF Receptors

描述(申请人提供)：我们建议的长期目标是阐明血管通透性因子/血管内皮生长因子(VPF/VEGF，VEGF-A)促进血管形成和影响微环境的信号通路。血管内皮生长因子-A通过其两种酪氨酸激酶受体VEGFR-1和VEGFR-2以及非酪氨酸激酶受体神经粘连蛋白(NRP)参与血管内皮细胞(EC)的增殖、迁移、存活和分化(动静脉细胞命运规范)等多种血管过程。在我们资助的最后两个周期中，我们定义了几条不同和复杂的血管内皮生长因子-A途径。这些途径主要集中在增殖、迁移和生存上。尽管有证据表明血管内皮生长因子-A通过血管内皮生长因子受体(VEGFRs)介导的信号具有不同的功能，但目前尚不清楚某些血管内皮生长因子介导的下游信号转导通路如何选择性地增强两个重要功能：促进内皮细胞分化和创造内皮细胞高通透性。为了了解血管内皮生长因子-A独特的信号通路，我们提出了两个目标。目标1将描述VEGFR-2和NRPs在EC分化中的作用。我们还将确定血管内皮生长因子介导的P53调控的信号通路及其在EC分化中的作用。同样，将评估蛋白激酶D(PKD)在血管内皮生长因子(VEGF)介导的EC分化中的关键作用。然而，目标2将实时确定血管内皮生长因子诱导的血管通透性(VP)的分子机制。最近，我们建立了一种热诱导的血管内皮生长因子-A转基因斑马鱼模型，用于实时研究VP。为此，我们将评估单个VEGFRs和通路下游的分子在导致三种截然不同的环境中的作用：基础血管通透性(BVP)、急性血管高通透性(AVH)和慢性血管高通透性(CVH)。建议的研究将阐明已知和未知分子介导不同类型血管通透性的信号通路。因此，拟议的研究结果将促进对这两个重要功能的分子机制和途径的理解，并将影响我们对伤口愈合等正常生理过程以及包括癌症、糖尿病视网膜病变和导致心脏病和中风的缺血条件在内的病理条件的了解。最后，拟议的研究将扩大我们对血管内皮生长因子-A信号的理解，因为它与其他类型的血管内皮生长因子反应细胞有关，包括循环祖细胞、骨细胞和神经前体细胞。

DESCRIPTION (provided by applicant): The long-term objective of our proposal is to elucidate the signaling pathways by which vascular permeability factor/vascular endothelial growth factor (VPF/VEGF, VEGF-A) promotes blood vessel formation and influences microenvironment. VEGF-A participates in a variety of vascular processes including endothelial cell (EC) proliferation, migration, survival, and differentiation (arterial-venous cell fate specification) through its two tyrosine kinase receptors, VEGFR-1 and VEGFR-2 and non-tyrosine kinase receptors neuropilins (NRPs). During the last two cycles of our funding, we defined several diverse and complex pathways of VEGF-A. These pathways focused mainly on proliferation, migration, and survival. Although there is striking evidence for distinct functional roles of VEGF-A-mediated signaling through VEGF receptors (VEGFRs), it is still unclear how certain VEGF-mediated downstream signal transduction cascades selectively potentiate two important functions: promotes EC differentiation and creates EC hyperpermeability. To understand the unique signaling pathways of VEGF-A, we have proposed two aims. Aim 1 will delineate the roles of VEGFR-2 and NRPs for EC differentiation. We will also define the signaling pathways of VEGF-mediated p53 regulation and its role in EC differentiation. Similarly, the key role of Protein Kinase D (PKD) in VEGF-mediated EC differentiation will be evaluated. Whereas, Aim 2 will define the molecular mechanism of VEGF-induced vascular permeability (VP) in real-time. Recently we have developed a heat-inducible VEGF-A transgenic zebrafish model to study VP in real-time. In this aim, we will evaluate the role of individual VEGFRs and the molecules downstream of the pathways that lead to three distinctly different settings: basal vascular permeability (BVP), acute vascular hyperpermeability (AVH), and chronic vascular hyperpermeability (CVH). The proposed studies will elucidate the signaling pathways by which the known as well as unknown molecules mediate the different types of vascular permeability. Hence, the results of the proposed studies will promote understanding of the molecular mechanisms and pathways of these two important functions of VEGF-A and will impact our knowledge of normal physiological processes such as wound healing as well as pathological conditions, including cancer, diabetic retinopathy, and ischemic conditions leading to heart disease and stroke. Lastly, the proposed studies will expand our understanding of VEGF-A signaling as it relates to other VEGF-responsive cell types including circulating progenitor cells, bone cells, and neuronal progenitors.