Regulation of angiogenesis by syndecan-1

描述(申请人提供)：Syndecan-1是硫酸乙酰肝素蛋白多糖家族之一，在细胞外基质黏附中作为受体发挥作用。尽管Syndecan-1在成熟血管衬里的内皮细胞上不表达，但我们发现它表达在经历肿瘤诱导血管生成的活化内皮细胞上，并认为它调节该部位的α-v-β3和α-v-β5整合素的活性；这两个整合素是成纤维细胞生长因子和血管内皮生长因子诱导血管生成的完整途径，特别是对细胞凋亡具有保护作用。我们最近的工作发现了一种新的机制，在其中Syndecan-1调节α-v-Beta3和α-v-Beta5整合素的活性。我们的初步发现表明，沉默syndecan-1的表达，或与细菌中表达的syndecan-1胞外区竞争，将阻止这两个整合素在内皮细胞中的激活。我们建议定位负责调节这些整合素的位点(S)(S)，并分离Syndecan-1中可竞争性用于血管生成检测的活性部位的多肽。我们还计划对包含Syndecan和每个整合素的调控复合体进行分子表征。由于在肿瘤诱导的血管生成过程中，Syndecan-1在血管内皮细胞中表达上调，我们将通过比较成纤维细胞生长因子和血管内皮生长因子的刺激作用，并将Syndecan-1的表达与Hox D3、B3和Dig主要调控基因相关联，来探索在血管生成过程中是什么调节这种表达。这些检测还将测量由成纤维细胞生长因子或血管内皮生长因子激活的两种不同的下游保护途径，因为它们分别依赖于α-v-β3和α-v-β5整合素，并确定两者是否都依赖于syndecan-1介导的对这些整合素的调节。最后，我们将利用这些信息以及我们希望获得的竞争性多肽，通过小鼠角膜血管生成实验和小鼠肿瘤诱导的血管生成实验，在体内扰乱Syndecan-1的调节。这些研究将为Syndecan-1在血管生成过程中如何发挥作用提供新的见解，并有望带来阻止癌症、子宫内膜异位症、糖尿病视网膜病变等疾病中发生的有害血管生成的新药。

DESCRIPTION (provided by applicant): Syndecan-1 is one of a family of heparan sulfate proteoglycans that function as receptors in extracellular matrix adhesion. Although syndecan-1 is reportedly not expressed on endothelial cells lining mature vessels, we have found that it is expressed on activated endothelial cells undergoing tumor-induced angiogenesis and propose that it regulates the activity of the alpha-v-beta3 and alpha-v-beta5 integrins at this site; these two integrins are integral to the pathways by which FGF and VEGF induce angiogenesis, particularly providing protection against apoptosis. Our recent work has identified a novel mechanism in which syndecan-1 regulates the activity of the alpha-v-beta3 and alpha-v-beta5 integrins. Our preliminary findings suggest that silencing of syndecan-1 expression, or competition with the syndecan-1 ectodomain expressed in bacteria, will block the activation of these two integrins in endothelial cells. We propose to localize the site(s) responsible for regulating these integrin (s) and to isolate peptides representing the active sites in syndecan-1 that can be used competitively in angiogenesis assays. We also plan to molecularly characterize the regulatory complex that encompasses the syndecan and each integrin. Since syndecan-1 appears upregulated in vascular endothelium undergoing tumor-induced angiogenesis, we will explore what regulates this expression during the angiogenesis program, comparing stimulation by FGF and VEGF, and correlating syndecan-1 expression with the Hox D3, B3 and DIG master regulatory genes. These assays will also measure the two different downstream pathways of protection against apoptosis activated by either FGF or VEGF, as they have been shown to depend on the alpha-v-beta3 and alpha-v-beta5 integrins, respectively, and determine whether both rely on the syndecan-1-mediated regulation of these integrins. Finally, we will use this information, and the competitive peptides that we hope to derive, to disrupt the syndecan-1 regulation in vivo, using a mouse cornea angiogenesis assay, and angiogenesis induced by mouse tumors. These studies will provide new insights into how syndecan-1 functions during angiogenesis, and will hopefully lead to new drugs that block the deleterious angiogenesis that occurs in diseases such as cancer, endometriosis, diabetic retinopathy and others.