Regulation Of Intracellular Iron Metabolism

细胞内铁代谢的调节

基本信息

批准号：
7734737
负责人：
TRACEY A. ROUAULT
金额：
$ 116.62万
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/7734737
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 tempol

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。介导铁蛋白和转铁蛋白受体丰度的铁依赖性改变的顺式和反式元件已在本实验室前几年被鉴定和表征。铁反应元件 (IRE) 是在铁蛋白 mRNA 的 5 端和转铁蛋白受体 mRNA 的 3 端发现的 RNA 茎环。我们克隆、表达并表征了两种重要的铁感应蛋白：铁调节蛋白 1 (IRP1) 和铁调节蛋白 2 (IRP2)。当铁水平耗尽时，IRP 与 IRE 结合，从而抑制铁蛋白 mRNA 和其他在 5 个非翻译区域中包含 IRE 的转录物的翻译，或者稳定转铁蛋白受体 mRNA 和可能在 3UTR 中包含 IRE 的其他转录物。 IRP1 的 IRE 结合活性取决于该蛋白质是否含有铁硫簇（参见项目 1 Z01 HD008814-01）。 IRP2 也在缺铁细胞中结合 IRE，但与 IRP1 不同的是，IRP2 在铁充足的细胞中会被降解。实验证据表明 IRP2 结合铁并进行铁催化的氧化。在铁充足的细胞中，IRP2 被选择性泛素化并被蛋白酶体降解。为了解决有关铁代谢生理学的问题，通过胚胎细胞系中的同源重组在小鼠体内产生了 IRP1 和 IRP2 的功能丧失突变。在没有刺激的情况下，铁代谢不存在与 IRP1 功能丧失相关的异常。 IRP2-/- 小鼠会出现一种进行性神经系统综合征，其特征是步态异常和轴突变性。铁蛋白过度表达发生在受影响的神经元中，以及少突胶质细胞突出到轴突变性产生的空间中。 IRP2-/- 动物会出现缺铁性贫血和红细胞生成性原卟啉症。在缺乏 IRP1 的动物中，IRP 2 可以补偿 IRP1 调节活性的损失。同时缺乏 IRP1 和 IRP2 的动物会在早期胚胎时死亡。当 IRP1 的一个拷贝也被删除时，成年 IRP2-/- 小鼠的成年期神经变性会加剧。 IRP2-/- 小鼠提供了成人自发性缓慢进行性神经变性的独特例子，并且正在对疾病各个阶段的基因表达和铁状态进行分析。此外，预防神经退行性变的小分子治疗也取得了有希望的结果。