Regulation Of Intracellular Iron Metabolism

细胞内铁代谢的调节

基本信息

批准号：
7594181
负责人：
TRACEY A. ROUAULT
金额：
$ 113.08万
依托单位：
EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/7594181
关键词：
5&apos Untranslated Regions Aconitate Hydratase Adult Affect Anemia Animals Binding Biochemical Biological Assay Cell Line Cells Disease Elements Embryo Erythropoietic Protoporphyria Ferritin Gait abnormality Gene Expression Goals H ferritin Human Indium Iron Iron Regulatory Protein 1 Iron Regulatory Protein 2 Iron-Sulfur Proteins Laboratories Lead Mammals Mediating Messenger RNA Molecular Mus Nerve Degeneration Neurologic Neurons Oligodendroglia Phenotype Physiology Protein Binding Proteins RNA Regulation Staging Stimulus Sulfur Syndrome Transcript Transferrin Receptor Translations Work base blastomere structure homologous recombination human WNT2 protein iron metabolism loss of function mutation mouse model multicatalytic endopeptidase complex oxidation prevent progressive neurodegeneration protein function small molecule stem

项目摘要

This project aims to understand the molecular basis for regulation of intracellular iron metabolism. The cis and trans elements mediating the iron-dependent alterations in abundance of ferritin and the transferrin receptor have been identified and characterized in previous years in this laboratory. Iron- responsive elements (IREs) are RNA stem-loops found in the 5 end of ferritin mRNA and the 3 end of transferrin receptor mRNA. We have cloned, expressed, and characterized two essential iron- sensing proteins, Iron Regulatory Protein 1 (IRP1) and Iron Regulatory Protein 2 (IRP2). IRPs bind IREs when iron levels are depleted, resulting in the inhibition of translation of ferritin mRNA and other transcripts that contain an IRE in the 5 untranslated regions, or in stabilization of the transferrin receptor mRNA and possibly other transcripts that contain IREs in the 3UTR. The IRE-binding activity of IRP1 depends on whether the protein contains an iron-sulfur cluster (see project 1 Z01 HD008814-01). IRP2 also binds IREs in iron-depleted cells, but unlike IRP1, IRP2 is degraded in cells that are iron- replete. Experimental evidence indicates that IRP2 binds iron and undergoes iron-catalyzed oxidation. In iron-replete cells, IRP2 is selectively ubiquitinated and degraded by the proteasome. To approach questions about the physiology of iron metabolism, loss of function mutations of IRP1 and IRP2 have been generated in mice through homologous recombination in embryonic cell lines. In the absence of provocative stimuli, there are no abnormalities in iron metabolism associated with loss of IRP1 function. IRP2-/- mice develop a progressive neurologic syndrome characterized by gait abnormalities and axonal degeneration. Ferritin over-expression occurs in affected neurons, and in protrusions of oligodendrocytes into the space created by axonal degeneration. IRP2-/- animals develop iron-insufficiency anemia and erythropoietic protoporphyria. In animals that lack IRP1, IRP 2 compensates for loss of IRP1 regulatory activity. Animals that lack both IRP1 and IRP2 die as early embryos. The adult-onset neurodegeneration of adult IRP2-/- mice is exacerbated when one copy of IRP1 is also deleted. IRP2-/- mice offer a unique example of spontaneous adult-onset slowly progressive neurodegeneration, and analyses of gene expression and iron status at various stages of disease are ongoing. In addition, small molecule treatments to prevent neurodegeneration have yielded promising results.

该项目旨在了解调节细胞内铁代谢的分子基础。在该实验室的前几年中，已经确定并表征了介导铁依赖铁和转移蛋白受体的依赖铁依赖性改变的顺式和跨元件。铁反应性元素（IRES）是在铁蛋白mRNA的5端发现的RNA干循环和转铁蛋白受体mRNA的3端。我们已经克隆，表达和表征了两个必需的铁感应蛋白，即铁调节蛋白1（IRP1）和铁调节蛋白2（IRP2）。当铁水平耗尽时，IRP结合了IRP，导致抑制铁蛋白mRNA的翻译和其他在5个未翻译区域中包含IRE的转录物，或者稳定转铁蛋白受体mRNA，以及可能包含IRES的其他转录物在3UTR中。 IRP1的激怒结合活性取决于该蛋白是否含有铁硫簇（请参阅项目1 Z01 HD008814-01）。 IRP2还结合了铁缺失细胞中的IRE，但是与IRP1不同，IRP2在铁质的细胞中降解。实验证据表明，IRP2结合铁并经历铁催化的氧化。在铁植入的细胞中，IRP2被蛋白酶体有选择地泛素化和降解。为了解决有关铁代谢生理的问题，通过胚胎细胞系中的同源重组，已经在小鼠中产生了IRP1和IRP2功能突变的丧失。在没有挑衅性刺激的情况下，与IRP1功能丧失有关的铁代谢没有异常。 IRP2 - / - 小鼠发展出一种以步态异常和轴突变性为特征的进行性神经系统综合征。铁蛋白过表达发生在受影响的神经元中，以及少突胶质细胞的突起中，轴突变性产生的空间。 IRP2 - / - 动物会产生铁不适性贫血和红血病原生质。在缺乏IRP1的动物中，IRP 2弥补了IRP1调节活性的损失。缺乏IRP1和IRP2的动物死于早期胚胎。当一份IRP1副本也被删除时，成年IRP2 - / - 小鼠的成人发神经变性会加剧。 IRP2 - / - 小鼠提供了一个独特的例子，即自发性成年人发作的缓慢进行性神经退行性创变，以及对疾病各个阶段的基因表达和铁状态的分析。此外，用于预防神经变性的小分子处理已产生有希望的结果。