Biological Function of Iron Responsive Elements

铁反应元件的生物学功能

• 批准号: 7125466
• 负责人: Richard S. Eisenstein
• 金额: $ 30.58万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-30 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7125466
• 关键词: RNA binding protein; aconitate hydratase; genetic regulation; iron; iron metabolism; laboratory rat; messenger RNA; nuclear magnetic resonance spectroscopy; nucleic acid structure; protein biosynthesis; thermodynamics; translation factor

DESCRIPTION (provided by applicant): Iron is an essential but potentially toxic nutrient for nearly all organisms. Iron deficiency is the most common human nutritional deficiency disease with 2 to 22% of Americans suffering from it depending on age and gender. At the same time excessive iron stores are associated with neurological disorders and certain cancers. Mammalian iron metabolism is modulated by two regulatory RNA binding proteins, iron regulatory protein 1 (IRP1) and IRP2. IRPs bind to iron responsive elements (IRE) in up to seven different mRNA encoding proteins critical for the maintenance of iron homeostasis or for other pathways needed during the adaptive response to iron deficiency. This includes proteins involved in the transport, use and storage of iron as well as the TCA cycle enzyme mitochondrial aconitase. It is clear that IRE-containing mRNA are differentially regulated by IRP in order to meet the physiological demands of various cell types yet relatively little is known as to how IRPs discriminate between different mRNA. Because IRPs are pivotal regulators of iron metabolism, and dysregulation of the expression of proteins encoded by IRE-containing mRNA contributes to neurodegenerative, iron overload and other diseases, it is important to elucidate the mechanisms through which IRE-containing mRNA are selectively regulated. Our overall goal is to understand how iron metabolism is controlled through the hierarchical regulation of IRE-containing mRNA. We demonstrate that mRNA with one IRE in their 5' untranslated region are differentially regulated by IRP; we propose several novel hypotheses to explain this hierarchical regulation and we propose to: 1) determine the structure of the 5' IRE region of mitochondrial aconitase (macon) mRNA and the role of IRP and specific translation factors as well as flanking sequences in the structure and/or thermodynamic stability of this region; 2) determine the role of specific translation factors, cellular protein synthetic capacity and individual IRP in the selective regulation of the use of IRE-containing mRNA; 3) elucidate the role of IRE and flanking sequences in the hierarchical regulation of the translation in vivo of mRNA containing functionally strong or weak IRE-regions in the 5' UTR. Our studies provide a comprehensive approach from the molecular to the cellular level that will: a) delineate the mechanisms that define the breadth of the IRP regulatory spectrum; b) demonstrate how target site diversity amongst RNA regulatory elements controls mRNA fate; and c) serve as a paradigm for understanding how combinatorial mRNA regulation controls fundamental biological processes.

描述（由申请人提供）：铁是几乎所有生物体必需但具有潜在毒性的营养素。铁缺乏症是最常见的人类营养缺乏症，根据年龄和性别，2%至22%的美国人患有铁缺乏症。同时，过量的铁储存与神经系统疾病和某些癌症有关。哺乳动物的铁代谢受两种RNA结合蛋白调节，即铁调节蛋白1（IRP 1）和IRP 2。IRP与多达七种不同的mRNA编码蛋白质中的铁响应元件（IRE）结合，所述蛋白质对于维持铁稳态或对于在对铁缺乏的适应性反应期间所需的其他途径至关重要。这包括参与铁的运输，使用和储存的蛋白质以及TCA循环酶线粒体顺乌头酸酶。很明显，IRE-含有mRNA的差异调节IRP，以满足各种细胞类型的生理需求，但相对较少的是知道IRP如何区分不同的mRNA。由于IRP是铁代谢的关键调节因子，并且由含IRE的mRNA编码的蛋白质的表达失调有助于神经退行性疾病、铁过载和其他疾病，因此阐明含IRE的mRNA被选择性调节的机制是重要的。 我们的总体目标是了解如何通过含IRE的mRNA的分级调节来控制铁代谢。我们证明了在5'非翻译区含有一个IRE的mRNA受IRP的不同调节，我们提出了几个新的假说来解释这种分级调节，我们建议：1）确定线粒体顺乌头酸酶（macon）mRNA 5' IRE区的结构和IRP和特异性翻译因子以及侧翼序列在该区域结构和/或热力学稳定性中的作用; 2）确定特异性翻译因子、细胞蛋白质合成能力和个体IRP在选择性调节含IRE的mRNA的使用中的作用; 3）阐明IRE和侧翼序列在分级调节5' UTR中含有功能强或弱IRE区的mRNA的体内翻译中的作用。我们的研究提供了一个全面的方法，从分子到细胞水平，将：a）描绘的机制，定义的宽度的IRP监管频谱; B）演示如何靶位点的多样性之间的RNA调控元件控制mRNA的命运;和c）作为一个范例，了解如何组合mRNA调控控制基本的生物过程。