Regulation of angiogenesis by syndecan-1

描述（由申请人提供）：Syndecan-1是硫酸肝素蛋白聚糖家族中的一员，在细胞外基质粘附中作为受体起作用。虽然据报道syndecan-1在成熟血管内壁的内皮细胞上不表达，但我们发现它在经历肿瘤诱导的血管生成的活化内皮细胞上表达，并提出它调节α -v- β 3和α -v- β 5整合素在该位点的活性；这两种整合素在FGF和VEGF诱导血管生成的途径中是不可或缺的，特别是提供防止细胞凋亡的保护。我们最近的工作已经确定了syndecan-1调节α -v- β 3和α -v- β 5整合素活性的新机制。我们的初步研究结果表明，沉默syndecan-1的表达，或与细菌中表达的syndecan-1外结构域竞争，将阻断这两种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，并分离代表syndecan-1活性位点的肽，这些肽可以竞争性地用于血管生成分析。我们还计划对包括syndecan和每个整合素的调控复合体进行分子表征。由于syndecan-1在肿瘤诱导的血管生成过程中出现上调，我们将探讨在血管生成过程中是什么调控了这种表达，比较FGF和VEGF的刺激，并将syndecan-1的表达与Hox D3、B3和DIG主调控基因的关系。这些试验还将测量由FGF或VEGF激活的两种不同的保护细胞凋亡的下游途径，因为它们分别依赖于α -v- β 3和α -v- β 5整合素，并确定两者是否依赖于这些整合素的syndecan-1介导的调节。最后，我们将利用这些信息，以及我们希望获得的竞争性肽，利用小鼠角膜血管生成实验和小鼠肿瘤诱导的血管生成，在体内破坏syndecan-1调控。这些研究将为syndecan-1在血管生成过程中的功能提供新的见解，并有望导致新药阻止癌症、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。

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.