Mechanisms of PAI-1 Induced Anti-Angiogenesis

描述（由申请人提供）： 血管壁的内皮细胞通常通过抗血管生成分子维持在分化的静止状态。促血管生成分子使静止的内皮不稳定，变成形成新的毛细血管的迁移、增殖的内皮细胞。血管内皮的稳定周转率由分别具有细胞存活和死亡功能的促血管生成分子和抗血管生成分子的严格控制的平衡来维持。这种平衡的改变可以改变内皮的周转率，破坏血管的稳态。研究表明，血管内皮生长因子（VEGF）在动脉粥样硬化斑块的形成中起作用。这得到了研究的支持，研究表明血管生成与纤溶酶和金属蛋白酶活性的增加有关，纤溶酶和金属蛋白酶活性增加了斑块对急性破裂或斑块不稳定的易感性。几项动物研究表明，用血管生成抑制剂治疗后，动脉粥样硬化斑块新血管形成和斑块生长减少。纤溶酶原激活物抑制剂-1（PAI-1）在冠状动脉粥样硬化血管壁内膜层过度表达。这导致了一种假设，即PA 1 -1表达是控制有助于细胞外基质降解和平滑肌细胞迁移的局部纤溶酶原激活物的手段。我们已经构建了重组截短的PA 1 -1（rPAI-1）蛋白，以检查PA 1 -1在“非活性”构象（无反应中心环）的抗血管生成活性。一种rPAI-1蛋白rPAI-123具有有效的抗血管生成活性。rPAI-123的活性诱导纤溶酶裂解成血管抑素并抑制VEGF的生物利用度。在本研究中，我们将利用rPAI-123：目的I：阐明rPAI-123诱导纤溶酶裂解为血管抑素的相互作用;目的II：确定rPAI-123是否抑制硫酸乙酰肝素释放VEGF;目的III：确定rPAI-123处理的主动脉内皮细胞中的抗血管生成/促凋亡信号通路。由于rPAI-123蛋白的有效抗血管生成活性，它最终可能在以过度血管生成为特征的疾病的治疗中发挥有用的作用，例如动脉粥样硬化斑块的进展和稳定、糖尿病视网膜病变和某些类型的癌症。

DESCRIPTION (provided by applicant): Endothelial cells lining the vascular wall are normally maintained in a differentiated, quiescent state by anti-angiogenic molecules. Pro-angiogneic molecules destabilize the quiescent endothelium into migratory, proliferative endothelial cells that form new capillary blood vessels. The steady turn over rate of the vascular endothelium is maintained by a tightly controlled balance of pro- and anti-angiogenic molecules that have cell survival and death functions, respectively. A shift in the balance can alter the turn over rate of the endothetium and disrupt vascular homeostasis. It has been shown that vascular endothelial growth factor (VEGF) has a role in atherosclerotic plaque development. This is supported by studies which show that angiogenesis is associated with increases in plasmin and metalloproteinase activity which increases plaque susceptibility to acute rupture or plaque destabilization. Several animal studies have shown a reduction in atherosclerotic plaque neovascularization and plaque growth after treatment with angiogenesis inhibitors. Plasminogen activator inhibitor-1 (PAl-1) is over expressed in the intimal layer in the atherosclerotic vessel wall in human coronary artery disease. This has led to one hypothesis that PAl-1 expression is a means of controlling localized plasminogen activators that contribute to extracellular matrix degradation and smooth muscle cell migration. We have constructed recombinant truncated PAl-1 (rPAI-1) proteins to examine the anti-angiogenic activity of PAl-1 in "inactive" conformations (absence of reactive center loop). One rPAI-1 protein, rPAI-123, has potent anti-angiogenic activity. The activity of rPAI-123 induces cleavage of plasmin into angiostatin and inhibits the bioavailability of VEGF. In this study, we will utilize rPAI-123 to: Aim I: Clarify the rPAI-123 interactions that induce cleavage of plasmin into angiostatin; Aim II: Determine if rPAI-123 inhibits VEGF release from heparan sulfate; and Aim Ill: Define the anti-angiogenic/pro-apoptotic signaling pathways in rPAI-123 treated aortic endothelial cells. Due to the potent anti-angiogenic activity of rPAI-123 protein, it may ultimately play a useful role in the treatment of diiseases characterized by excessive angiogenesis, such as progression and stabilization of atherosclerotic plaques, diabetic retinopathy, and certain types of cancer.