REGULATION OF IRON METABOLISM GENES IN EUKARYOTES

真核生物铁代谢基因的调控

基本信息

批准号：
2634260
负责人：
WILLIAM EDWARD WALDEN
金额：
$ 17.1万
依托单位：
UNIVERSITY OF ILLINOIS AT CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
1995
资助国家：
美国
起止时间：
1995-01-01 至 2002-01-31
项目状态：
已结题

项目摘要

Iron is an essential nutrient to living systems. As a result, organisms have evolved specific mechanisms for the acquisition and storage of iron for use in growth and development. Ferritin is the major iron storage protein in eukaryotes. The transferrin receptor (TfR) is the major route of iron transport into the animal cells. These proteins play a central role in iron metabolism in animal cells. Synthesis of both ferritin and the TfR is regulated in coordination with the iron balance of the cell. when iron is limiting, synthesis of ferritin is repressed, whereas that of the TfR is elevated. When iron is in excess, ferritin synthesis is elevated while synthesis of the TfR is depressed. Regulation of synthesis of these proteins is mediated by a cytosolic protein called the Iron Responsive Element-Binding Protein (IRE-BP). The IRE-BP binds to a conserved 28 nucleotide element, the IRE, located in the 5' untranslated region of ferritin mRNAs and in the 3' untranslated region of the TfR mRNA. In binding to the IRE, the IRE-BP represses translation of ferritin mRNA while it prevents rapid degradation of the TfR mRNA, resulting in reciprocal but coordinated synthesis of ferritin and TfR. Our long term objectives are to understand the mechanisms of iron regulated gene expression, the molecular basis underlying protein/RNA interaction and the mechanism of translational control via trans-acting repressors. During the next 5 years, we will use yeast as a system for expression of the rabbit IRE-BP to investigate structure/function relationships in the IRE-BP with a particular focus on determining the basis for its specific interaction with the IRE and how this is integrated with iron sensing domains. We will also investigate the mechanism of translational repression by the lRE-BP through the identification of genes in yeast that disrupt (or aid) IRE-BP function. Information gained in these areas will shed light on the molecular basis underlying a variety of nutritional and genetic iron metabolism disorders, including iron deficiency anemia and hemochromatosis. Towards these goals we will: 1) Determine structure/function relationships in the IRE-BP; 2) Investigate the mechanism(s) of regulating IRE-BP activity by iron in vivo, determine the significance of its aconitase activity to iron metabolism; Identify extragenic suppressors of IRE-BP function. These studies will be performed using standard molecular biology, biochemical and yeast genetic techniques. Successful completion of these studies will provide significant insight towards our understanding of nutrient regulated gene expression.

铁是生命系统的重要营养。结果，有机体已经进化了以获取和存储铁的特定机制用于增长和发展。铁蛋白是主要的铁储存真核生物中的蛋白质。转铁蛋白受体（TFR）是主要途径铁运输到动物细胞中。这些蛋白质发挥了中心在动物细胞中铁代谢中的作用。综合铁蛋白和 TFR与细胞的铁平衡协调。当铁被限制时，铁蛋白的合成被抑制，而那是 TFR的升高。当铁过量时，铁蛋白的合成为 TFR合成时升高。调节合成这些蛋白质是由称为铁的胞质蛋白介导的响应元素结合蛋白（IRE-BP）。 IRE-BP与A结合保守的28个核苷酸元件，IRE，位于5'未翻译的铁蛋白mRNA和TFR的3'未翻译区域 mRNA。在与IRE的结合时，IRE-BP抑制铁蛋白的翻译 mRNA虽然防止TFR mRNA的快速降解，从而导致铁蛋白和TFR的倒数但协调的合成。我们的长期目标是了解铁调节基因的机制表达，分子基础蛋白/RNA相互作用和通过反式阻遏物转移控制的机制。在接下来的5年中，我们将使用酵母作为表达的系统兔子IRE-BP研究在 IRE-BP特别着眼于确定其特定的基础与IRE的相互作用以及如何与铁感应整合域。我们还将研究翻译的机制 LRE-BP通过酵母中的基因抑制破坏（或辅助）IRE-BP功能。在这些领域获得的信息会根据分子的基础来阐明各种各样的基础营养和遗传铁代谢疾病，包括铁缺乏贫血和血色素症。朝向这些目标，我们将：1）确定IRE-BP中的结构/功能关系； 2）调查铁在体内调节IRE-BP活性的机制，确定其刺刺酶活性对铁代谢的重要性；确认 IRE-BP功能的基因抑制剂。这些研究将是使用标准分子生物学，生化和酵母遗传进行技术。这些研究的成功完成将提供对我们对养分调节基因的理解的重大见解表达。