Classical and Alternative Pathways of Fibrinolysis

描述（由申请人提供）：纤溶酶原（本申请的焦点）在纤维蛋白溶解中起重要作用的证据是无可争议的，但最近已将其他功能归因于该分子。其中最突出的是纤溶酶原参与细胞迁移。后一种作用变得特别明显的竞技场是炎症细胞募集。因此，在纤溶酶原缺陷小鼠中的研究显示，在巯基乙酸盐诱导的腹膜炎、动脉粥样硬化、再狭窄、关节炎、哮喘和血管生成中，白细胞募集减弱，所有这些都是特异性炎症反应的例子。纤溶酶原在白细胞迁移中的作用取决于其与细胞表面结合位点的相互作用。这些结合位点是异质性的，但积累的数据现在已经将数量缩小到五种纤溶酶原受体，这可能是其与白细胞相互作用的关键。目的1将分析这五种候选纤溶酶原受体的作用，利用体外和体内分析在小鼠中评估每个在不同炎症反应中的贡献。纤溶酶原含有对其生物学功能至关重要的两类位点：其赖氨酸结合位点（LBS），其与其kringles相关并介导其与细胞表面的相互作用;以及其活性位点，其与其轻链相关并催化其蛋白水解功能。在目标2中，将通过将纯化的蛋白质施用到Plg-/-小鼠中以及通过转基因到这些动物中的重建方法来剖析LBS和活性位点在体内不同炎症反应中的贡献。此外，纤溶酶原的LBS调节剂、脱辅基蛋白（a）和TAFI天然存在，将评价它们对纤溶酶原依赖性炎症反应的影响。尚未在白细胞中评估纤溶酶原与其受体相互作用导致细胞内信号传导事件和下游后果的可能性。基于初步的数据表明，信号事件是由纤溶酶原诱导的，本提案的第三个目标将分析诱发的信号通路，这种信号的后果和纤溶酶原受体参与转导这些信号。总体而言，这些研究将提供新的见解纤溶酶原的功能，并将导致更好地了解调节其对炎症反应的贡献的分子和细胞事件。

DESCRIPTION (provided by applicant): The evidence that plasminogen, the focus of this application, plays an essential role in fibrinolysis, is indisputable but other functions have been more recently ascribed to the molecule. Most prominent among these is the involvement of plasminogen in cell migration. The arena in which this latter role becomes particularly evident is in inflammatory cell recruitment. Thus, studies in plasminogen-deficient mice have shown blunted leukocyte recruitment in thioglycollate-induced peritonitis, atherosclerosis, restenosis, arthritis, asthma and angiogenesis, all examples of specialized inflammatory responses. The role of plasminogen in leukocyte migration depends upon its interactions with binding sites on cell surfaces. These binding sites are heterogenous, but accumulated data now have narrowed down the number to five plasminogen receptors that may be key to its interaction with leukocytes. Aim 1 will analyze the role of these five candidate plasminogen receptors utilizing in vitro and in vivo analyses in mice to assess the contribution of each in different inflammatory responses. Plasminogen contains two classes of sites that are critical to its biological functions: its lysine binding sites (LBS), which are associated with its kringles and mediate its interactions with cell surfaces, and its active site, which is associated with its light chain and catalyzes its proteolytic functions. In Aim 2, reconstitution approaches by administration of purified proteins into Plg-/- mice and by transgenesis into these animals will be undertaken to dissect the contributions of the LBS and the active site in different inflammatory responses in vivo. In addition, modulators of the LBS of plasminogen, apoprotein(a) and TAFI, occur naturally and their influence on plasminogen-dependent inflammatory responses of plasminogen will be evaluated. The possibility that the interaction of plasminogen with its receptors leads to intracellular signaling events and downstream consequences has not been assessed in leukocytes. Based on preliminary data showing that signaling events are induced by plasminogen, the third aim of this proposal will analyze the signaling pathways evoked, the consequences of such signaling and the plasminogen receptors involved in transducing these signals. Overall, these studies will provide new insights into the functions of plasminogen and will lead to a greater understanding of the molecular and cellular events that regulate its contribution to inflammatory responses.