Hephaestin: A Copper Protein Involved in Iron Metabolism

Hephaestin：一种参与铁代谢的铜蛋白

• 批准号: 6611839
• 负责人: CHRISTOPHER D VULPE
• 金额: $ 36.27万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6611839
• 关键词: copper; dietary iron; disease /disorder model; electron microscopy; enzyme activity; ferroxidase; gastrointestinal absorption /transport; gel electrophoresis; gene expression; immunocytochemistry; immunoprecipitation; iron disorder; iron metabolism; laboratory mouse; malnutrition; matrix assisted laser desorption ionization; membrane transport proteins; metalloenzyme; microcytic /hypochromic anemia; nutrition related tag; protein localization; protein protein interaction; protein structure function; protein transport; tissue /cell culture; yeast two hybrid system

DESCRIPTION (provided by applicant): Iron deficiency adversely affects over one-third of the world's population. Conversely, iron overload disease hemochromatosis is one of the commonest genetic defects in man. In order to maintain a balance between deficiency and toxicity, multiple regulatory systems exist to optimize iron levels in the human body. The absorption of iron by the intestine is central to this regulation because no physiologic means exists to excrete excess iron. Our long-term goal is to understand how changes the body communicates its iron needs to the intestine and how the intestine controls iron absorption into the body. We previously identified, hephaestin, which oxidizes iron from ferrous to ferric iron and is required for moving iron from gut cells into the body. We are studying its function and role in intestinal iron transport and whole body iron homeostasis. Remarkable changes occur in response to iron deficiency, the expression of iron transport proteins increase and some proteins including hephaestin move from intracellular locations to the cell surface to facilitate iron transport. In systemic iron deficiency, the intestinal enterocyte is poised for maximal absorption but is also capable of buffering the uptake of iron in case of potentially toxic dietary levels. In this study, we will ask three questions. 1) How is hephaestin regulated in response to local and systemic iron status? We will independently manipulate dietary and systemic iron status in mice to define the dietary versus systemic effects on hephaestin and other iron transport proteins. We will use cell culture studies to define the regulatory mechanisms. 2) What regulates the movement of hephaestin? We will define the dietary conditions for movement and the rate at which it occurs. We will use a cell culture system to identify the parts of hephaestin that are necessary for movement. We will try to identify the proteins that play a role in the movement of hephaestin. Finally, we will ask 3) how iron oxidation by hephaestin facilitates iron transport ? Hephaestin could be directly required in order to release iron from the iron transporter or alternatively it could create a gradient of ferrous iron which would drive the transport of iron. Iron transport assays using a buffer system that allows us to very tightly control the amount of ferrous and ferric iron will allow us to distinguish between these possibilities.

描述（由申请人提供）：缺铁对世界三分之一以上的人口产生不利影响。相反，铁超载疾病血色素沉着症是人类最常见的遗传缺陷之一。为了维持缺铁和中毒之间的平衡，存在多个调节系统来优化人体内的铁水平。肠道对铁的吸收是这种调节的核心，因为没有生理手段可以排出多余的铁。我们的长期目标是了解身体是如何将铁需求传递给肠道的，以及肠道是如何控制铁的吸收进入身体的。我们之前发现了hephaestin，它可以将铁从亚铁氧化为铁，并且是将铁从肠道细胞转移到体内所必需的。我们正在研究其在肠道铁转运和全身铁稳态中的功能和作用。铁缺乏会引起显著的变化，铁转运蛋白的表达增加，包括hephaestin在内的一些蛋白从细胞内位置移动到细胞表面以促进铁的运输。在全身性缺铁的情况下，肠上皮细胞可以最大限度地吸收铁，但也可以在潜在有毒的饮食水平下缓冲铁的吸收。在这项研究中，我们将提出三个问题。1) hephaestin在局部和全身铁状态下是如何调节的？我们将独立控制小鼠的饮食和全身铁状态，以确定饮食对hephaestin和其他铁转运蛋白的影响。我们将使用细胞培养研究来确定调节机制。2)是什么调控了hephaestin的运动？我们将定义运动的饮食条件和运动发生的速率。我们将使用细胞培养系统来识别运动所必需的hephaestin部分。我们将尝试找出在肝蛋白酶运动中起作用的蛋白质。最后，我们将问3)hephaestin氧化铁是如何促进铁运输的？为了从铁转运体中释放铁，可以直接需要Hephaestin，或者它可以产生亚铁梯度，这将驱动铁的运输。使用缓冲系统进行铁运输分析，使我们能够非常严格地控制亚铁和三铁的数量，这将使我们能够区分这些可能性。