Mechanism and Regulation of Iron Export by Ferroportin

Ferroportin 铁输出的机制和调控

基本信息

批准号：
6910334
负责人：
JERRY KAPLAN
金额：
$ 43.07万
依托单位：
UNIVERSITY OF UTAH
依托单位国家：
美国
项目类别：
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/6910334
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

项目摘要

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）：铁转运蛋白（Fpn、IREG1、MTP1）是脊椎动物中唯一确定的跨膜铁输出蛋白。我们的初步数据表明，hepcidin 通过诱导 Fpn 的内化和降解来抑制细胞铁输出。该提案的目标是了解 Fpn 介导的铁输出机制和铁调素介导的 Fpn 内化机制。铁进入血浆受到高度调节，并受到铁储存、炎症和缺氧的影响。慢性炎症导致血浆铁减少和铁限制性贫血，称为慢性病贫血。铁储备增加或炎症会导致铁调素水平升高，铁调素是肝脏分泌的一种调节铁代谢的肽。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 的金属输出是否针对铁。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结构域的位置。将使用生化和遗传学方法来确定铁调素如何与 Fpn 结合以及 Fpn 如何内化。人铁调素将被修饰以产生放射性标记和光亲和配体，然后将其用于表征铁调素/Fpn 相互作用。通过选择性地改变人类和鱼类铁调素中的氨基酸残基，我们将定义对 Fpn 结合至关重要的残基。 Fpn 中内化和金属转运所需的残基将通过铁调素处理的 Fpn 的基因筛选和生化检查来鉴定。 RNAi 沉默将用于确定 Fpn 是否是唯一的哺乳动物铁输出系统，或者是否存在其他铁输出系统。这些研究将探讨铁调素调节铁输出的机制，并确定铁调素和 Fpn 在铁生理学中的作用。