Roles of Iron Transport Factor Genes In Iron Absorption

说明(申请人提供)：铁对人体正常的细胞功能是必不可少的，铁稳态的紊乱会导致各种器官出现危及生命的危急症状。由于排泄的铁很少，为了防止铁超载，体内的铁量通过调节肠道铁吸收来严格保持。尽管我们对细胞对铁的利用和储存有了先进的了解，但铁跨粘膜转移的机制仍然不清楚。我们研究的长期目标是了解肠道铁吸收过程的细胞和分子机制，以及它对各种病理生理条件的调节反应。最近发现的两个基因，即Hephestn和Iron portin1(Ireg1/MTP1)，将有助于理解铁吸收的机制及其调节。虽然Hephestn被认为在跨粘膜基底膜运输铁的过程中起着重要作用，而铁蛋白则被认为是铁的输出器。这些基因在肠道铁吸收过程中的确切功能目前仍不清楚。因此，这一探索性的R21方案的主要目标是了解和定义Hephestn和Iron portinl在肠道铁吸收过程中的功能。在这个R21项目中，我们将利用人类肠道细胞系来研究这两个基因的功能。我们将用编码人肝素和铁蛋白的基因转染人肠道Caco-2细胞，以确定它们在肠道铁吸收过程中的作用。具体地说，这些研究将：(1)确定Hephaestin和Feportin1在人类肠道细胞中的细胞位置和铁转运功能，以及(2)确定Hephaestin和Feportin1的联系以及它们如何相互作用影响铁的转运，利用高表达Hephaestin但缺乏Feportin1(或缺乏Hephaestin但过表达的Feportin1)的人肠道Caco-2细胞。这项拟议研究的结果将为理解调节肠道铁吸收的细胞和分子机制提供关键信息。这项R21建议研究的完成将是实现我们长期目标的关键一步。

DESCRIPTION (provided by applicant): Iron is essential for normal cellular functions in human body and the disturbances of iron homeostasis can cause life-threatening critical manifestations in various organs. Since very little iron is excreted, to prevent iron overload, the amount of iron in the body is tightly maintained by regulating intestinal iron absorption. Despite our advanced knowledge on the cellular utilization and storage of iron, the mechanism of iron transfer across the mucosa still remains unclear. The long-term goals of our research are to understand the cellular and molecular mechanism of the intestinal iron absorption processes and its regulation response to the various patho-physiological conditions. Recent discovery of two genes, hephaestin and ferroportinl (Iregl/MTP1), will help understand the mechanism of iron absorption and its regulation. While hephaestin was proposed to have an important role in iron transport across the basolateral membrane of mucosa, ferroportinl was expected to function as an iron exporter. The exact functions of these genes in the processes of intestinal iron absorption currently remain unknown. Thus, the primary goals of this exploratory R21 proposal are to understand and define functions of hephaestin and ferroportinl in the intestinal iron absorption processes. In this R21 project, we will utilize the human intestinal cell line to study the function of these two genes. We will transfect human intestinal Caco-2 cells with the genes encoding human hephaestin and ferroportinl to determine their roles in the processes of intestinal iron absorption. Specifically, these studies will: (1) characterize the cellular location and iron transport function of hephaestin and ferroportinl in human intestinal cell, and (2) determine the association of hephaestin with ferroportinl and how they might interact to affect the transfer of iron utilizing human intestinal Caco-2 cells overexpressing hephaestin but lacking ferroportinl (or hephaestin deficient but overexpressing ferroportinl). Results from this proposed study will provide critical information towards understanding the cellular and molecular mechanisms of regulating intestinal iron absorption. The completion of the proposed study in this R21 will be a critical step in achieving our long-term goals.