IRON METABOLISM AND PHOSPHORYLATION OF IRPS BY PKC

铁是几乎所有人都必须的但具有潜在毒性的营养物质。 有机体。缺铁是人类最常见的营养问题 缺乏症。与此同时，过多的铁储备一直是 与神经性疾病的发生率增加有关， 某些癌症。哺乳动物的铁代谢是通过 两种调节RNA结合蛋白--铁调节蛋白的作用 1(IRP1)和IRP2。IRPS与铁响应元件(IRE)结合 铁蛋白(铁储存)和转铁蛋白受体(TFR)(铁摄取) MRNAs，并分别调节其翻译或稳定性。IRP1 是铁-S蛋白与铁-S簇的存在与否 调节蛋白质的RNA结合活性。铁可以调节体内的 相关蛋白IRP2通过诱导其RNA结合活性 退化。因为IRPS是铁代谢的关键调节器， 和铁代谢的直接变化发生在人类健康和 疾病，重要的是更好地了解铁和其他因素是如何 影响IRP功能。 我们的总体目标是确定铁的新陈代谢是如何调节的 通过细胞内和细胞外效应器的作用 影响IRP的行动。我们已经开始通过以下方式阐明一种新的机制 依赖蛋白激酶C(PKC)的IRPS的磷酸化服务于什么 作为荷尔蒙、生长因子和其他因素 影响细胞的铁代谢。我们建议：1)使用 确定磷酸化如何影响IRP的结构/功能方法 2)确定磷酸化在细胞中的作用。 信息平台的功能和划分；3)决定了信息平台的功能 铁和氧化应激对细胞功能的影响 磷酸化的IRPS。我们关于IRp1的广泛目标是 了解调控变化对其组装和稳定性的影响--S 簇影响其作为铁调节的RNA蛋白的功能。我们的 IRP2的总体目标是描绘磷酸化如何影响 氧化还原和铁对其蛋白酶体降解的调节。我们的研究 提供从分子到整个动物的全面方法 将：1)为监管变化勾画出一种新的机制 在哺乳动物中铁-S团簇的稳定性；2)描述一个独特的例子 关于磷调节和铁调节如何重叠来建立 调节RNA结合蛋白Irp1和Irp1的稳态水平 IRP2；3)进一步定义了哺乳动物 铁的代谢是可以调节的。

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.