PLEIOTROPIC DEFENSES--THE HEMOPEXIN SYSTEM

描述(摘自申请人的摘要) 这里使用的术语“多效性防御”指的是生物系统。 保护生物体免受不止一种有害物质侵害的行为 条件。血凝素系统的性质，它实现了 受体介导的血红素及其血浆的内吞转运 膜受体，使其成为此类保护机制的范例，并且 这两种蛋白质是R03研究提案的重点。这个 血凝素系统扮演着几个截然不同但又相互关联的角色，作为 人体防御机制，在创伤、溶血中起抗氧化剂的作用 以及炎症，一种从病原体中隔离的血红素，一种 细胞营养铁，以及保护蛋白的诱导物，如铁蛋白和 金属硫蛋白。 请求支持的两年的具体目标是：(1) 亲和层析分离足够量的人血凝素受体 允许：(A)受体的初步特征，即分子 重量、亚基组成和糖基化，(B)产生特定的 高亲和力的受体抗体，使用商业服务 (C)人血凝血素基因的克隆和测序 受体，和(2)继续表征结构决定因素 血凝素-血凝素受体的相互作用。 为了实现这些目标，标准但健壮的技术 已经在这个实验室建立的将被使用，包括亲和力 受体分离层析；全细胞、配基印迹和可溶性 受体结合分析；cDNA克隆、测序和定点定位 诱变。我们还将为未来对该结构的研究获得工具 以及受体的调节和相互作用的基本信息 血凝素及其受体。这样的信息是需要开发的 对再灌流损伤等情况的治疗措施。信息 对哺乳动物受体的研究也将补充对人类的研究 病原体细菌血凝素受体，并提供设计所需的洞察力 选择性地抑制细菌，而不是宿主的血凝素受体。

DESCRIPTION (taken from the applicant's abstract) The term "pleiotropic defense" is used here to refer to biological systems that act to defend the organism against more than one deleterious agent or condition. The properties of the hemopexin system, which carries out receptor-mediated heme transport by endocytosis of hemopexin and its plasma membrane receptor, make it a paradigm for such protective mechanisms, and these two proteins are the foci of this R03 research proposal. The hemopexin system plays several distinct yet connected roles as part of the body's defense mechanisms, acting as an anti-oxidant in trauma, hemolysis and inflammation, a sequester of heme from pathogens, a conserver of the cell nutrient iron, and an inducer of protective proteins like ferritin and metallothionein. The specific aims for the two years of requested support are: (1) to isolate by affinity chromatography sufficient human hemopexin receptor to allow: (a) initial characterization of the receptor, i.e., molecular weight, subunit composition, and glycosylation, (b) production of specific high affinity antibodies to the receptor, using the services of a commercial facility, and (c) cloning and sequencing the cDNA for the human hemopexin receptor, and (2) to continue to characterize the structural determinants of the hemopexin-hemopexin receptor interaction. To accomplish these objectives, standard yet robust techniques that are already established in this laboratory will be employed, including affinity chromatography for receptor isolation; whole cell, ligand blot and soluble receptor binding assays; cDNA cloning and sequencing and site-directed mutagenesis. We will also obtain tools for future research on the structure and regulation of the receptor and basic information on the interaction of hemopexin with its receptor. Such information is needed to develop therapeutic measures for conditions like re-perfusion injury. Information on the mammalian receptor will also complement research on the human pathogen bacterial hemopexin receptors and provide insight needed to design means to selectively inhibit bacterial, but not host, hemopexin receptors.