IRON METABOLISM AND PHOSPHORYLATION OF IRPS BY PKC

PKC 的铁代谢和 IRPS 磷酸化

• 批准号: 6342467
• 负责人: Richard S. Eisenstein
• 金额: $ 23.84万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-01-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6342467
• 关键词: RNA binding protein; aconitate hydratase; enzyme activity; erythropoietin; gene expression; genetically modified animals; immunofluorescence technique; intermolecular interaction; iron; iron metabolism; iron sulfur protein; laboratory mouse; laboratory rabbit; nitric oxide; nutrition related tag; oxidation reduction reaction; oxidative stress; phosphorylation; protein degradation; protein kinase C; protein structure function; site directed mutagenesis; superoxide dismutase

Iron is an essential but potentially toxic nutrient for virtually all organisms. Iron deficiency is the most common human nutritional deficiency disease. At the same time excessive iron stores have been associated with increased occurrence of neurological disorders and certain cancers. Mammalian iron metabolism is modulated through the action of two regulatory RNA binding proteins, iron regulatory protein 1 (IRP1) and IRP2. IRPs bind to iron responsive elements (IRE) in ferritin (iron storage) and transferrin receptor (TfR) (iron uptake) mRNAs and regulate their translation or stability, respectively. IRP1 is an Fe-S protein and the presence or absence of the Fe-S cluster modulates the RNA binding activity of the protein. Iron regulates the RNA binding activity of a related protein, IRP2, by inducing its degradation. Because IRPs are pivotal regulators of iron metabolism, and directed changes in iron metabolism occur in human health and disease, it is important to better understand how iron and other factors affect IRP function. Our overall goal is to determine how iron metabolism is modulated through the action of intracellular and extracellular effectors that influence IRP action. We have begun to elucidate a novel mechanism by which protein kinase C (PKC)-dependent phosphorylation of IRPs serves as a means through which hormones, growth factors and other agents can act to influence cellular iron metabolism. We propose to: 1) use a structure/function approach to determine how phosphorylation affects IRP function in vitro; 2) determine the cellular role of phosphorylation in the function and compartmentalization of IRPs; and 3) determine the effect of iron and oxidative stress on the cellular function of phosphorylated IRPs. Our broad goal with regard to IRP1 is to understand how regulated changes in assembly and stability of its Fe-S cluster affect its function as an iron-regulated RNA protein. Our overall goal for IRP2 is to delineate how phosphorylation affects the redox and iron-regulation of its proteasomal degradation. Our studies provide a comprehensive approach from the molecular to the whole animal level that will: 1) delineate a novel mechanism for regulated changes in stability of Fe-S clusters in mammals; 2) describe a unique example of how phosphoregulation and iron-regulation overlap to establish the steady state level of the regulatory RNA binding proteins, IRP1 and IRP2; 3) further define the molecular pathways through which mammalian iron metabolism can be regulated.

铁对于几乎所有人来说都是一种必需但具有潜在毒性的营养素 有机体。 缺铁是人类最常见的营养问题 缺乏症。 与此同时，过多的铁库存已被 与神经系统疾病发生率增加有关 某些癌症。 哺乳动物的铁代谢通过以下途径调节 两种调节RNA结合蛋白、铁调节蛋白的作用 1 (IRP1) 和 IRP2。 IRP 与铁反应元件 (IRE) 结合 铁蛋白（铁储存）和转铁蛋白受体 (TfR)（铁摄取） mRNA 并分别调节其翻译或稳定性。 IRP1 是一种 Fe-S 蛋白以及是否存在 Fe-S 簇 调节蛋白质的 RNA 结合活性。 铁调节 相关蛋白 IRP2 的 RNA 结合活性，通过诱导其 降解。 因为 IRP 是铁代谢的关键调节因子， 铁代谢的直接变化对人类健康和 疾病，重要的是更好地了解铁和其他因素如何 影响IRP功能。 我们的总体目标是确定铁代谢是如何调节的 通过细胞内和细胞外效应器的作用 影响 IRP 行动。 我们已经开始阐明一种新机制 IRP 的蛋白激酶 C (PKC) 依赖性磷酸化发挥作用 作为激素、生长因子和其他药物可以发挥作用的手段 影响细胞铁代谢。 我们建议：1）使用 确定磷酸化如何影响 IRP 的结构/功能方法 体外功能； 2) 确定磷酸化的细胞作用 IRP 的功能和划分； 3) 确定 铁和氧化应激对细胞功能的影响 磷酸化IRP。 我们关于 IRP1 的总体目标是 了解如何调节其 Fe-S 的组装和稳定性变化 簇影​​响其作为铁调节 RNA 蛋白的功能。 我们的 IRP2 的总体目标是描述磷酸化如何影响 其蛋白酶体降解的氧化还原和铁调节。 我们的研究 提供从分子到整个动物的综合方法 该级别将：1）描绘一种新的监管变革机制 哺乳动物中 Fe-S 簇的稳定性； 2）描述一个独特的例子 磷调节和铁调节如何重叠以建立 调节RNA结合蛋白IRP1和的稳态水平 IRP2； 3）进一步明确哺乳动物的分子途径 铁的代谢可以得到调节。