Role of NgBR

描述（由申请人提供）：内皮细胞（EC）的激活和定向迁移是血管生成的第一步，参与肿瘤生长和糖尿病视网膜病变的发病机制。我们之前发现NgBR是一种新的受体，对nogo - b刺激的EC体外迁移至关重要。最近，我们证明了NgBR对斑马鱼体内血管生成至关重要。在初步结果中，我们提供的新数据表明，NgBR结合法酰化Ras (F-Ras)，从而激活Ras- pi3k - akt依赖通路，诱导EC迁移。尽管Ras是一种癌基因，在癌症中已经得到了很好的研究，但它在内皮细胞生物学中的作用仍然相对不清楚。事实上，VEGF可以显著增加EC中Ras的激活。组成性激活的Ras可以刺激Akt的磷酸化，Akt是EC迁移的关键参与者。我们的初步数据显示，Ras敲低可使vegf诱导的EC迁移减少约50%，并完全消除nogo - b诱导的EC迁移。这表明Ras在调节EC迁移中的作用值得进一步研究。此外，考虑到NgBR敲低可使vegf诱导的EC迁移减少约60%，并完全消除nogo - b诱导的EC迁移，NgBR介导的Ras-PI3K-Akt信号通路可能比之前认为的更为突出。在本应用程序中，我们将确定NgBR与F-Ras相互作用以启动依赖于ras的EC迁移的机制。我们的应用假设是：“NgBR通过其细胞质域的特定位点招募F-Ras，这是Nogo-B和vegf刺激的内皮细胞迁移的重要步骤。”为了验证这一假设，我们将：1。鉴定NgBR细胞质结构域的哪些区域需要结合F-Ras。此外，我们将使用NgBR功能缺失突变体来确定EC迁移和血管生成是否以及在多大程度上依赖于NgBR介导的Ras易位；2. 确定NgBR调控Nogo-B/VEGF刺激的Ras活化的机制；3. 确定NgBR在协同VEGFR2诱导Ras依赖性EC迁移和血管生成中的作用。这项应用具有创新性，因为它首次确定了NgBR作为一种新型支架蛋白在调节Ras易位和激活Ras- pi3k -akt通路中的作用。这一应用的成功发现将对血管生物学产生“巨大”的影响，因为它将揭示或揭示刺激EC迁移和血管生成的全新途径。虽然Ras在癌症中是一个被充分研究的致癌基因，但Ras易位到质膜上影响EC功能的确切机制尚不清楚。我们提出的研究将首次定义NgBR介导Ras激活影响EC迁移的机制。这些研究的发现将使我们能够开发新的抗血管生成疗法来预防糖尿病视网膜病变和肿瘤血管生成。

DESCRIPTION (provided by applicant): Endothelial cell (EC) activation and directional migration is an initial step in angiogenesis that is involved in the pathogenesis of tumor growth and diabetic retinopathy. We previously identified NgBR as a new receptor that is essential for Nogo-B-stimulated EC migration in vitro. Recently, we demonstrated that NgBR is essential for in vivo angiogenesis in zebrafish. In Preliminary Results, we present new data showing that NgBR binds farnesylated Ras (F-Ras) and in so doing, activate Ras-PI3K-Akt dependent pathways to induce EC migration. Although Ras, an oncogene, is well studied in cancer, its role in endothelial cell biology remains relatively unclear. In fact, VEGF can remarkably increase Ras activation in EC. Constitutively activated Ras can stimulate the phosphorylation of Akt, a key player for EC migration. Our preliminary data show that Ras knockdown decreases VEGF-induced EC migration by about 50% and completely abolishes Nogo-B-induced EC migration. It suggests that the role of Ras in regulating EC migration deserves further investigation. Further, considering the fact that NgBR knockdown decreases VEGF-induced EC migration by about 60% and completely abolishes Nogo-B-induced EC migration, NgBR-mediated Ras-PI3K-Akt signaling likely represents a much more prominent pathway than previously considered. In this application, we will determine the mechanisms by which NgBR interacts with F-Ras to initiate Ras-dependent EC migration. The hypothesis of our application is: "NgBR recruits F-Ras via specific sites in its cytoplasmic domain, which is an essential step for Nogo-B- and VEGF-stimulated endothelial cell migration." To test this hypothesis, we will: 1. identify which regions in the cytoplasmic domain of NgBR are required for binding F-Ras. Furthermore, we will use NgBR loss of function mutants to determine if and the extent to which EC migration and angiogenesis are dependent on NgBR-mediated Ras translocation; 2. determine the mechanism by which NgBR regulates Nogo-B/VEGF- stimulated Ras activation; 3. determine the roles of NgBR in coordinating with VEGFR2 to induce Ras- dependent EC migration and angiogenesis. This application is innovative because it is the first to define the role of NgBR as a novel scaffold protein in modulating Ras translocation and in activating Ras-PI3K-akt pathway. Successful findings from this application have a "huge" impact on vascular biology because it will have uncovered or revealed an entirely new pathway for stimulating EC migration and angiogenesis. Although Ras is a well-studied oncogene in cancer, the exact mechanisms by which Ras translocates to plasma membrane to influence EC function are unknown. Our proposed studies will be the first to define the mechanisms by which NgBR mediates Ras activation to influence EC migration. Findings from these studies will allow us to develop new and novel anti-angiogenic therapies to protect against diabetic retinopathy and tumor angiogenesis.