PROTEINS IN HEME TRANSPORT AND GENE REGULATION

血红素由血浆糖蛋白血球蛋白(HPX)转运是一种特异性的， 膜受体介导的过程中，转运蛋白和 它的受体在内吞作用后循环，就像铁通过转铁蛋白运输一样。 血红素被内质网中的血红素加氧酶(HO)分解。 HPX是人体抵御损伤的急性期防御系统的重要组成部分 病原体；减缓导致衰老的氧化损伤；以及 节约了铁元素。血红素-HPX对小鼠肝脏、神经元、细胞的影响 神经视网膜和免疫系统(如T淋巴细胞)。的总目标是 这项研究计划是为了确定多效性的机制 血红素-HPX复合体与其膜结合后的细胞反应 受体，其中包括协调的基因调控。两个本金 这项研究项目的领域是确定蛋白质在 表面HPX受体的细胞内血红素转运及其意义 涉及血红素和铁的蛋白质基因的机制 代谢包括HO、HPX、转铁蛋白和转铁蛋白受体 对HPX的协同调控和差异性调控 与编码对细胞防御重要的蛋白质的其他基因一样 抗氧化应激，如金属硫蛋白(MT)。这些活动 在维持细胞动态平衡方面具有重要的生物学意义 与生理相关的细胞内血红素和铁的变化 在创伤、感染、溶血、炎症和 手术中的再灌注损伤。为了实现这些目标，一个全面的 正在采取的方法是在基因调控机制中 对HPX受体单独占据的反应或对血红素摄取的反应 HO、MT和HPX本身的细胞内转运将被定义。HPX 受体占位激活蛋白激酶C和活性氧 中间产物可能是在血红素释放和运输过程中产生的， 从而提供了通过激活来影响核事件的手段 转录因子(如Jun、Fos和NFkappaB)。已经取得了进展 在识别顺式作用元件和反式作用元件方面取得了进展 在血红素-HPX和血红素介导的基因调控中工作的蛋白质。这个 具体目标是：L)和2)继续界定顺位代理要素 在……里面 HO-1和MT-1基因的启动子及其反式作用 参与血红素-HPX和血红素转录调控的因素；3) 建立调控HPX自身表达的机制 对血红素-HPX或血红素的反应：4)以表征HPX受体 通过亲和层析分离，我们成功地将其用于纯化 流感嗜血杆菌HPX受体基因的克隆和测序 5)继续阐明细胞色素b5和 细胞内血红素转运中的其他血红素结合蛋白 生化、免疫学和形态学技术。

Heme transport by the plasma glycoprotein hemopexin (HPX) is a specific, membrane receptor-mediated process in which both the transport protein and its receptor recycle after endocytosis, like iron transport by transferrin. Heme is catabolized by heme oxygenase (HO) in the endoplasmic reticulum. HPX is a vital part of the body's acute phase defence against injury and pathogens; acts to slow oxidative damage which contributes to aging; and conserves iron. Heme-HPX exerts effects on liver, neurons, cells of the neural retina and immune system (e.g. T-lymphocytes). The overall goal of this research program is to determine the mechanisms for the pleiotropic cellular responses after the heme-HPX complex binds to its membrane receptor, which include coordinated gene regulation. The two principal areas of this research project are to define the role of proteins in intracellular heme transport from the surface HPX receptor and to elucidate the mechanisms whereby the genes for proteins involved in heme and iron metabolism including HO, HPX, transferrin and the transferrin receptor are coordinately and differentially regulated in response to heme-HPX as well as other genes which encode proteins important for cellular defenses against oxidative stress, such as metallothionein (MT). These activities are biologically important in maintaining cell homeostasis under physiologically relevant changes in intracellular heme and iron which take place during trauma, infection, hemolytic conditions, inflammation and reperfusion injury in surgery. To achieve these goals, a comprehensive approach is being taken in which the mechanisms of gene regulation in response to HPX receptor occupancy alone or to heme uptake and intracellular transport will be defined for HO, MT and HPX itself. HPX receptor occupancy activates protein kinase C and reactive oxygen intermediates are generated, perhaps during heme release and transport, thus providing a means to influence nuclear events by activating transcription factors (e.g. Jun, Fos and NFkappaB). Progress has already been made towards identifying the cis-acting elements and trans-acting proteins that operate in heme-HPX and heme-mediated gene regulation. The specific aims are: l) and 2) to continue to define the cis-acting elements in the promoter of the HO-1 and the MT-1 genes together with the trans-acting factors involved in transcriptional regulation by heme-HPX and heme; 3) to establish the mechanisms whereby the expression of HPX itself is regulated in response to heme-HPX or heme: 4) to characterize the HPX receptor isolated by affinity chromatography which we successfully used to purify the HPX receptor from Haemophilus influenzae, and to clone and sequence this protein; 5) to continue to elucidate the role of cytochrome b5 and other heme-binding proteins in intracellular heme transport using biochemical, immunological and morphological techniques.