Mechanism and Regulation of Iron Export by Ferroportin

Ferroportin 铁输出的机制和调控

• 批准号: 7061390
• 负责人: JERRY KAPLAN
• 金额: $ 38.27万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-05-15 至 2010-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7061390
• 关键词: CHO cells; biological transport; cell communication molecule; fluorescent dye /probe; iron; iron metabolism; laboratory mouse; liver metabolism; macrophage; membrane activity; membrane transport proteins; peptides; protein structure function; tissue /cell culture

DESCRIPTION (provided by applicant): Ferroportin (Fpn, IREG1, MTP1) is the only identified transmembrane iron exporter in vertebrates. Our preliminary data indicate that hepcidin inhibits cellular iron export by inducing the internalization and degradation of Fpn. The goals of this proposal are to understand the mechanism of Fpn-mediated iron export and the mechanism of hepcidin-mediated Fpn internalization. The entry of iron into plasma is highly regulated and is affected by iron stores, inflammation and hypoxia. Chronic inflammation results in decreased plasma iron and an iron-limited anemia, referred to as the Anemia of Chronic Disease. Increased iron stores or inflammation result in high levels of hepcidin, a peptide secreted by liver that regulates iron metabolism. We hypothesize that this interaction is a major controlling factor in mammalian iron homeostasis. We will determine if metal export by Fpn is specific for iron through the use of metal sensitive fluorescent dyes. We will define the structure of Fpn and determine the number of transmembrane domains and the location of intracellular and extracellular domains. Biochemical and genetic approaches will be used to determine how hepcidin binds to Fpn and how Fpn is internalized. Human hepcidin will be modified to generate radiolabeled and photoaffinity ligands, which will then be used to characterize the hepcidin/Fpn interaction. By selectively changing amino acid residues in human and fish hepcidins, we will define residues critical for Fpn binding. Residues in Fpn that are required for internalization and metal transport will be identified through genetic screens and biochemical examination of hepcidin treated Fpn. RNAi silencing will be used to determine if Fpn is the only mammalian iron exporter or if are there are other iron export systems. These studies will probe the mechanism that underlines the regulation of iron export by hepcidin and will define the roles of hepcidin and Fpn in iron physiology.

描述（由申请人提供）：铁蛋白（FPN，IREG1，MTP1）是脊椎动物中唯一已识别的跨膜铁出口商。我们的初步数据表明，肝素通过诱导FPN的内在化和降解来抑制细胞铁的出口。该提案的目标是了解FPN介导的铁出口的机制以及肝素介导的FPN内在化的机制。铁进入等离子体受到高度调节，并受铁储存，炎症和缺氧的影响。慢性炎症导致血浆铁和铁限制的贫血减少，被称为慢性疾病的贫血。铁储存或炎症增加会导致肝素高水平，肝素是由肝脏分泌的肽，可调节铁代谢。我们假设这种相互作用是哺乳动物铁稳态的主要控制因素。我们将通过使用金属敏感荧光染料来确定FPN的金属出口是否特定于铁。我们将定义FPN的结构，并确定跨膜结构域的数量以及细胞内和细胞外域的位置。生化方法和遗传方法将用于确定肝素如何与FPN结合以及FPN如何内化。人肝素将被修饰以产生放射性标记和光亲和力配体，然后将其用于表征肝素/FPN相互作用。通过选择性改变人和鱼肝素中的氨基酸残基，我们将定义对FPN结合至关重要的残留物。 FPN中内部化和金属转运所需的残基将通过遗传筛选和对肝素治疗的FPN的生化检查来鉴定。 RNAi沉默将用于确定FPN是唯一的哺乳动物铁出口商还是还有其他铁出口系统。这些研究将探究强调肝素对铁出口调节的机制，并将定义肝素和FPN在铁生理学中的作用。