Angiopoietins in Angiogenesis

描述（申请人提供）：血管生成过多或不足往往在许多疾病的进展中起着至关重要的作用，如缺血性心脏和肢体，肿瘤的生长和转移。血管生成是指从新血管中萌发形成新血管的过程。这项建议的长期目标是阐明血管生成素在血管生成中的作用，并确定这些作用是如何调节的。血管生成素是三种密切相关的蛋白，作为Tie-2受体酪氨酸激酶的配体。血管生成素- tie -2通路在胚胎血管生成中起重要作用。然而，血管生成素在肿瘤血管生成中的作用尚不清楚，其潜在的细胞分子机制及其调控尚不清楚。血管生成是肿瘤生长和转移的关键。我们已经证明，Ang-1与细胞外基质（ECM）结合，而Ang-3通过硫酸肝素蛋白多糖（HSPGs）保留在细胞表面，分别调节Ang-1或Ang-3的功能。我们假设Ang-1和Ang-3在体内调节内皮细胞行为和血管生成中起重要的拮抗作用，并且Ang-1的促血管生成作用通过其与ECM的结合而负调控，而Ang-3的抗血管生成作用通过其与细胞表面HSPGs的结合而促进。以下具体目标旨在验证这一假设：确定1)Ang-1与ECM和2)Ang-3与细胞表面HSPGs之间相互作用的分子基础；3)研究Ang-1与ECM的结合和Ang-3与细胞表面HSPGs的结合如何影响它们在调节内皮细胞行为中的作用；4)体内血管生成：我们计划利用已建立的生化、分子和细胞生物学方法，转染细胞，以及Lewis肺癌细胞的体内自发肺转移模型来实现这一目标。这些研究的完成将对Ang-1和Ang-3在内皮细胞生物学和肿瘤血管生成中的作用以及Ang-1和Ang-3的这些功能如何分别受到ECM或细胞表面HSPGs的调节产生新的见解。这些结果将有助于我们对血管生成的总体理解，并有助于开发潜在的新颖有效的血管生成相关疾病的治疗靶点，并且具有很高的生物学和治疗相关性。

DESCRIPTION (provided by applicant): Over or insufficient angiogenesis often plays essential roles in the progression of many diseases, such as ischemic heart and limb, and tumor growth and metastasis. Angiogenesis is a process of formation of new blood vessels by sprouting from pre-existing ones. The long-term objective of this proposal is to elucidate the roles of angiopoietins in angiogenesis and determine how these roles are regulated. Angiopoietins are three closely related proteins that serve as ligands of Tie-2 receptor tyrosine kinase. Angiopoietin-Tie-2 pathway has been shown to play important role in embryonic angiogenesis. However, the roles of angiopoietins in tumor angiogenesis, which is essential for tumor growth and metastasis, is not well established, and the underlying cellular and molecular mechanism and the regulation of these roles are not well understood. We have demonstrated that Ang-1 binds to the extracellular matrix (ECM) and Ang-3 is retained to the cell surface via heparan sulfate proteoglycans (HSPGs), which modulate the function of Ang-1 or Ang-3, respectively. We hypothesize that Ang-1 and Ang-3 play important antagonistic roles in regulating endothelial cell behavior and angiogenesis in vivo and the pro-angiogenic role of Ang-1 is negatively regulated by its binding to the ECM and the anti-angiogenic role of Ang-3 is facilitated by its binding to cell surface HSPGs. The following specific aims are designed to test this hypotheses: To determine the molecular bases of the interactions between 1) Ang-1 and the ECM and 2) Ang-3 and the cell surface HSPGs; 3) to investigate how the binding of Ang-1 to the ECM and the binding of Ang-3 to the cell surface HSPGs affect their roles in regulating endothelial cell behavior and; 4) angiogenesis in vivo, We plan to accomplish the aims by using the established biochemical, molecular and cell biology approaches, the transfected cells, and the in vivo spontaneous pulmonary metastatic models of Lewis lung carcinoma cells. The completion of the proposed studies will generate new insights on the roles of Ang-1 and Ang-3 in endothelial cell biology and tumor angiogenesis and on how these functions of Ang-1 and -3 are regulated by the ECM or cell surface HSPGs, respectively. These results would contribute to our understanding of angiogenesis in general and help to develop potential novel and effective targets for therapies of the angiogenesis-related diseases, and are of high biologic and therapeutic relevance.