Classical and Alternative Pathways of Fibrinolysis

描述（由申请人提供）：证明纤溶酶原（本申请的重点）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。后一种作用在炎症细胞募集中变得特别明显。因此，对纤溶酶原缺乏小鼠的研究表明，在巯基乙酸盐诱导的腹膜炎、动脉粥样硬化、再狭窄、关节炎、哮喘和血管生成等特化炎症反应中，白细胞募集减弱。纤溶酶原在白细胞迁移中的作用取决于它与细胞表面结合位点的相互作用。这些结合位点是异质的，但现在积累的数据已经将数量缩小到五个纤溶酶原受体，这可能是纤溶酶原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，利用小鼠体内和体外分析来评估每种受体在不同炎症反应中的作用。纤溶酶原包含两类对其生物学功能至关重要的位点：赖氨酸结合位点（lysine binding sites， LBS），与纤溶酶原的皱褶相关，并介导其与细胞表面的相互作用；活性位点（active site），与纤溶酶原的轻链相关，并催化其蛋白水解功能。在Aim 2中，将通过将纯化蛋白注入Plg-/-小鼠并将其转基因到这些动物中进行重构，以解剖LBS和活性位点在体内不同炎症反应中的作用。此外，纤溶酶原的LBS调节剂、载脂蛋白(a)和TAFI是天然存在的，它们对纤溶酶原依赖性炎症反应的影响将被评估。纤溶酶原与其受体的相互作用导致细胞内信号事件和下游后果的可能性尚未在白细胞中评估。基于初步数据显示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所诱发的信号通路、这些信号的后果以及参与转导这些信号的纤溶酶原受体。总的来说，这些研究将为纤溶酶原的功能提供新的见解，并将导致对调节其对炎症反应贡献的分子和细胞事件的更好理解。

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.