Classical and Alternative Pathways of Fibrinolysis

描述(由申请人提供)：纤溶酶原在纤溶中发挥重要作用的证据是无可争辩的，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领域是炎性细胞招募。因此，对纤溶酶原缺陷小鼠的研究表明，在硫代乙醇酸盐诱导的腹膜炎、动脉粥样硬化、再狭窄、关节炎、哮喘和血管生成中，白细胞招募迟钝，所有这些都是特殊炎症反应的例子。纤溶酶原在白细胞迁移中的作用依赖于它与细胞表面结合部位的相互作用。这些结合位点是不同的，但现在积累的数据已经将纤溶酶原受体的数量缩小到5个，这可能是它与白细胞相互作用的关键。目的1分析这五种候选纤溶酶原受体在小鼠体内和体外的作用，以评估每种受体在不同炎症反应中的作用。纤溶酶原含有两类对其生物学功能至关重要的部位：赖氨酸结合部位(LBS)和活性部位，LBS与纤溶酶原结合在一起，介导纤溶酶原与细胞表面的相互作用，活性结合部位与纤溶酶原轻链相关，催化纤溶酶原蛋白分解功能。在目标2中，将通过将纯化的蛋白注射到PLG-/-小鼠体内和通过转基因进入这些动物来重建LBS，以剖析LBS在体内不同炎症反应中的作用和活性部位。此外，纤溶酶原LBS的调节物，载脂蛋白(A)和TAFI，是自然产生的，它们对纤溶酶原依赖的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得到评估。根据初步数据显示，信号事件是由纤溶酶原诱导的，本提案的第三个目的将分析引起的信号通路、这种信号的后果以及参与转导这些信号的纤溶酶原受体。总体而言，这些研究将为纤溶酶原的功能提供新的见解，并将使人们更好地理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.