COORDINATE HORMONAL REGULATION OF THE FIBRINOGEN GENES

止血药中几种不同成分的缺陷 发病机制通常见于新生儿，尤其是 那些早产的人，与许多 严重的，常常是致命的疾病。传播的情况 血管内凝血(DIC)构成了潜在的 许多出血异常的病理，显然是因为 凝血蛋白被消耗掉，而且没有足够的 被替换了。为了开发治疗这些疾病的特殊疗法 对于凝固性疾病，了解其调节机制是至关重要的 促凝血蛋白和抗凝血蛋白的合成，几乎所有的 它们是在肝脏中制造的。纤维蛋白原尤其重要 研究是因为它是纤维蛋白的前体，纤维蛋白绝对是 形成凝块的结构网络所必需的，而且它是 从DIC的血浆中耗尽。研究计划 本提案中描述的内容旨在描述 糖皮质激素诱导纤维蛋白原合成 它们直接作用于肝脏，增加肝脏中 纤维蛋白原的三个亚基。这些调查利用 非洲爪蛙是因为在这种有机体中有可能 低基础水平诱导纯化肝纤维蛋白原合成 在全限定培养条件下维持的实质细胞 条件。正在进行的研究将决定激素是否 通过增强转录或转录增加稳定状态的mRNA水平 信使稳定。这里概述的实验将 确定潜在的分子机制，通过定义 激素所必需的纤维蛋白原基因的特定区域 刺激。这将通过开发一种基因来实现 调控外源基因表达的转基因系统 添加克隆的纤维蛋白原基因即可实现。这个强大的 技术将允许功能性监管要素 通过现场指导确定并随后详细绘制地图 诱变。将进行补充性研究，以确定 纤维蛋白原附近的糖皮质激素受体结合位点 基因，以便将它们与基因的激活相关联。 主要目标之一是确定坐标是否 三个亚基的诱导是由于荷尔蒙作用于 在分离的基因上有着完全相同的机制。这个 非洲爪哇系统也有可能在未来对 肝分化与表达能力的获得 纤维蛋白原基因。在该系统中进行的实验表明 与发育、成熟和激素调节的相关性 止血剂。

Deficiencies in several different components of the hemostatic mechanisms are commonly found in newborn infants, particularly those born prematurely, and are associated with a number of serious and often fatal disorders. The condition disseminated intravascular coagulation (DIC) constitutes part of the underlying pathology of many bleeding abnormalities, apparently because blood clotting proteins are consumed and are not adequately replaced. In order to develop specific therapies for treating these coagulopathies, it is essential to understand the regulation of synthesis of procoagulant and anticoagulant proteins, almost all of which are made in the liver. Fibrinogen is particularly important to study because it is the precursor of fibrin, which is absolutely required for forming the structural network of a clot, and it is depleted from the plasma in DIC. The research program described in this proposal is directed toward characterizing the induction of fibrinogen synthesis by glucocorticoid hormones, which act directly on the liver to increase the mRNA levels for the three subunits of fibrinogen. These investigations utilize the frog Xenopus laevis because in this organism it is possible to induce fibrinogen synthesis from low basal levels in purified liver parenchymal cells maintained under fully-defined culture conditions. Work in progress will determine whether the hormone increases steady state mRNA levels by enhancing transcription or messenger stability. The experiments outlined here will determine the underlying molecular mechanisms by defining the specific regions of the fibrinogen genes necessary for hormonal stimulation. This will be accomplished by developing a gene transfection system in which regulated expression of exogenously- added cloned fibrinogen genes can be achieved. This powerful technology will allow functional regulatory elements to be identified and subsequently mapped in fine detail by site-directed mutagenesis. Complementary studies will be carried out to locate specific glucocorticoid receptor binding sites near the fibrinogen genes, in order to correlate them with the activation of the genes. One of the major goals is to ascertain whether the coordinate induction of the three subunits is due to the hormone acting by precisely the same mechanism on the separate genes. The Xenopus system also has potential for future investigations into liver differentiation and the acquisition of competence to express the fibrinogen genes. Experimentation in this system has relevance to development, maturation, and hormonal regulation of hemostatis.