UROKINASE KRINGLE-MEDIATED VASCULAR REMODELING

尿激酶型纤溶酶原激活物(UPA)与纤溶和 涉及细胞迁移的不同过程，如动脉粥样硬化， 血管生成、伤口修复和肿瘤转移。靶向性药物在小鼠体内的研究 UPA和uPAR基因缺失提示uPA诱导跨膜 通过不同于与其结合的通路的信号传递 糖脂锚定受体(UPAR)，但到目前为止这一机制的细节 目前还没有得到澄清。UPA由一种受体结合生长因子组成 结构域，其功能未知的kringle结构域，以及蛋白酶 域。来自我们实验室的最新研究表明， UPA与血管平滑肌细胞(VSMC)结合并传递信号 增强uPA介导的VSMC收缩和细胞迁移。此外， Kringle的识别介导了uPA从细胞表面的清除， 提示Kringle结构域代表了VSMC中的一个重要控制点 功能。我们现在建议扩大这些研究的范围，并重新研究这些 更详细地描述了UPA Kringle的特性 相互关联的具体目标。1)我们将描述UPA的相互作用 Kringle与低密度脂蛋白受体/α2巨球蛋白受体 它调节uPA的降解。2)我们将分离和鉴定uPA-kringle VSMC上的结合蛋白。3)我们将研究kringle介导的信号 VSMC中的信号转导通路。4)我们将研究Kringle之间的相互作用 VSMC中结合蛋白依赖和uPAR依赖的信号转导事件 使用能够激活其中一个或两个通路的uPA变异体。5)我们会 检测uPA kringle和kringle结合蛋白在血管中的作用 血管内创伤大鼠模型的室壁重塑。这些研究将 深入了解新描述的uPA介导的信号转导途径 参与平滑肌细胞迁移和血管修复。身份识别 Kringle结合蛋白可能提供了一个机会来调节 血管平滑肌细胞增殖和迁移在血管内皮细胞损伤中的作用 动脉粥样硬化和再狭窄。

Urokinase plasminogen activator (uPA) has been implicated in fibrinolysis and diverse processes that involve cell migration such as atherosclerosis, angiogenesis, wound repair, and tumor metastases. Studies in mice with targeted deletion of the genes for uPA and uPAR indicate that uPA induces transmembrane signaling through pathways discrete from those involved in binding to its glycolipid-anchored receptor (uPAR), but to date the details of this mechanism have not been elucidated. uPA is composed of a receptor-binding growth factor domain, a kringle domain, the function of which is unknown, and a protease domain. Recent studies from our laboratories demonstrate that the kringle of uPA binds to vascular smooth muscle cells (VSMC) and delivers a signal that potentiates uPA-mediated VSMC contraction and cell migration. Further, recognition of the kringle mediates clearance of uPA from cell surfaces, suggesting the kringle domain represents an important control point in VSMC function. We now propose to extend these studies and to examine these newly described properties of the uPA kringle in greater detail through five inter-related specific aims. 1) We will characterize the interaction of the uPA kringle with the low-density lipoprotein receptor/alpha2 macroglobulin receptor which mediates uPA degradation. 2) We will isolate and identify the uPA-kringle binding protein on VSMC. 3) We will examine the kringle-mediated signal transduction pathway in VSMC. 4) We will study the interaction between kringle binding protein-dependent and uPAR-dependent signal transduction events in VSMC using uPA variants capable of activation either or both pathways. 5) We will examine the role of the uPA kringle and kringle binding protein in vascular wall remodeling in a rat model of intravascular trauma. These studies will provide insight into a newly described uPA-mediated signal transduction pathway involved in smooth muscle cell migration and vascular repair. Identification of the kringle binding protein may provide an opportunity to modulate the contribution of vascular smooth muscle cell proliferation and migration to atherosclerosis and restenosis.