REGULATION OF PLASMA PROTEIN BIOSYNTHESIS

纤维蛋白原和纤溶酶原是两种来源于肝脏的血浆蛋白 在止血方面发挥关键但相反的作用。活化的纤维蛋白原 (纤维蛋白)形成凝块，激活的纤溶酶原(纤溶酶)形成凝块 溶解。尽管我们对这两种物质的化学性质知道得很多 蛋白质的合成是如何被调节的，或者蛋白质是如何被调节的 多肽被组装并加工成功能蛋白质。这个 这项提议的长期目标是在细胞和 分子水平的这些调控过程。纤维蛋白原是一种血浆蛋白 在炎症反应中，它的合成会大大增加。我们 从单核细胞中分离出一种因子，使培养中的肝细胞 大大增加其纤维蛋白原的合成，从而模仿 培养中的急性时相反应。这个细胞培养物将被用作模型 系统调查导致增加的细胞内事件 纤维蛋白原信使核糖核酸的转录。我们将使用 高度特异的cDNAs作为探针，用于确定两种药物的动力学 纤维蛋白原信使核糖核酸的转录和半衰期。我们会 也用肝细胞培养和刺激因子来研究什么 细胞内信号是可操作的，导致转录增加 纤维蛋白原。我们将试图确定这六个人是如何 纤维蛋白原的多肽被组装成一种功能蛋白质。这些 将通过在体外转化纤维蛋白原mRNA进行实验 并使用非常特异的(克隆)抗体作为探针来确定 亚基连接在一起的方式。阐明该病毒的分子起源 两种形式的纤溶酶原是这项提案的目标之一。纤溶酶原 MRNA将被分离并用于体外翻译系统和 分析产品以确定是否有两种不同的翻译形式 纤溶酶原是存在的。这些结果应该会给出两个 两种形式的mRNA码。我们将用纯化的mRNA构建 CDNA克隆。选定的克隆将被隔离并鉴定为第一个克隆 了解纤溶酶原基因结构的步骤。这是意料之中的 从这些研究中获得的信息将显著增加我们的 了解这些重要分子是如何被调控的。一旦 控制系统被完全理解，那么就有可能 能够调节它们的合成，这可能具有巨大的治疗价值 在血管疾病方面。

Fibrinogen and plasminogen are two hepatically derived plasma protein that play critical but opposite roles in hemostasis. Activated fibrinogen (fibrin) is clot forming and activated plasminogen (plasmin) is clot dissolving. Even though much is known about the chemistry of these two proteins little is known about how their synthesis is regulated or how the polypeptides are assembled and processed into functional proteins. The long range goal of this proposal is to elucidate at the cellular and molecular level these regulatory processes. Fibrinogen is a plasma protein whose synthesis is greatly increased during an inflammatory reaction. We have isolated a factor from monocytes that causes hepatocytes in culture to greatly increase their synthesis of fibrinogen thus mimicing the acute-phase response in culture. This cell culture will be used as a model system to investigate the intracellular events which leads to increased transcription of the fibrinogen mRNA's. We will use well characterized highly specific cDNA's as probes to determine both the kinetics of transcription of the fibrinogen mRNA's and the mRNA half-lives. We will also use the hepatocyte culture and stimulating factor to investigate what intracellular signals are operant that leads to the increased transcription of fibrinogen. We will attempt to determine exactly how the six polypeptides of fibrinogen are assembled into a functional protein. These experiments will be carried out by translating fibrinogen mRNA's in vitro and using very specific (monoclonal) antibodies as probes to determine the way the subunits link together. Elucidating the molecular origin of the two forms of plasminogen is one of the goals of this proposal. Plasminogen mRNA will be isolated and used in an in vitro translation system and the products analyzed to determine if two different translational forms of plasminogen exist. These results should give information on whether two mRNA's code for the two forms. We will use the purified mRNA to construct cDNA clones. Selected clones will be isolated and characterized as a first step to understanding the plasminogen gene structure. It is anticipated that information derived from these studies will significantly increase our understanding of how these important molecules are regulated. Once the control systems are fully understood then there is a possibility of being able to regulate their synthesis which can be of enormous therapeutic value in vascular diseases.