Chemical Genetics of Iron Transport

铁转运的化学遗传学

• 批准号: 7807861
• 负责人: Marianne Wessling-Resnick
• 金额: $ 36.41万
• 依托单位: HARVARD SCHOOL OF PUBLIC HEALTH
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-15 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7807861
• 关键词: Address; Alleles; Binding; Caucasians; Caucasoid Race; Cells; Cholesterol; Clathrin; Country; Dietary Iron; Emerging Technologies; Endosomes; Enterocytes; Genes; Goals; Health; Hereditary Disease; Hereditary hemochromatosis; In Vitro; Iron; Iron Overload; Iron-Binding Proteins; Knowledge; Libraries; Lipids; Mediating; Membrane Microdomains; Molecular; Molecular Bank; Mus; Nutritional; Pathway interactions; Population; Rattus; Reagent; Regulation; SLC11A2 gene; Screening procedure; Serum; System; Testing; Transferrin; Transferrin Receptor; absorption; apical membrane; chemical genetics; combinatorial; in vivo; inhibitor/antagonist; novel; public health relevance; receptor mediated endocytosis; small molecule; transport inhibitor; uptake

DESCRIPTION (provided by applicant): Iron deficiency is the most prevalent nutritional problem in our country today. Iron overload promoted by hereditary hemochromatosis is one of the most common genetic disorders in our population. Increased knowledge about iron transport factors and how they are regulated to protect against iron deficiency and overload is essential to address these significant health problems. We have applied the emerging technologies of chemical genetics to advance our understanding of the factors and mechanisms involved in different pathways of iron uptake to discover several new transport inhibitors. Our goals are to characterize the activity of these compounds in vivo and in vitro and to discover new small molecule inhibitors using chemical genetics. We will use these reagents to advance our understanding of the factors, mechanisms, and regulation of iron uptake through the following specific aims: 1) To characterize the influence of small molecule inhibitors on iron transport in rats and mice. Using chemical genetics, we discovered ferristatin inhibits iron uptake from receptor-mediated endocytosis of the serum iron-binding protein transferrin. Ferristatin also blocks iron uptake by DMT1, a ferrous iron transporter that functions in dietary iron absorption across the apical membrane of enterocytes and after iron delivery into endosomes by the transferrin-mediated pathway. We propose to examine the effects of ferristatin and related compounds in vivo; 2) To determine the molecular mechanism of ferristatin inhibition of iron transport in vitro. We have shown that ferristatin inhibits transferrin-mediated iron uptake by inducing degradation of transferrin receptors by a clathrin- independent endocytic pathway. The actions of ferristatin are antagonized by cholesterol depletion, suggesting that lipid raft microdomains may be involved. Ferristatin also blocks iron uptake by DMT1 but the mechanism of inhibition remains to be identified. We propose to test the hypothesis that ferristatin modulates both iron transport pathways through lipid microdomains using cell molecular approaches; and 3) To identify and characterize novel small molecule inhibitors of DMT1. Recent combinatorial library screens have yielded a new class of structurally-related small molecule inhibitors of DMT1. We propose to define their effects on DMT1-mediated transport, transferrin-mediated iron uptake and non-transferrin bound iron uptake and to continue the discovery of inhibitors using the Molecular Libraries Screening Network (MLSN) system. PUBLIC HEALTH RELEVANCE: Iron deficiency remains the most prevalent nutritional problem in our country, yet recent identification of the gene responsible for hereditary hemochromatosis indicates that 1 in 20 Caucasians carry the defective allele and thus 1 in 400 may be susceptible to iron overload. Increased knowledge about the transport factors and how they protect against iron deficiency and overload is essential to more broadly address these significant health problems.

描述（由申请人提供）：铁缺乏症是当今我国最普遍的营养问题。遗传性血色素沉重促进的铁超负荷是我们人群中最常见的遗传疾病之一。对铁运输因素以及如何调节以防止铁缺乏和超负荷的知识对于解决这些重大健康问题至关重要。我们已经应用了化学遗传学的新兴技术来促进我们对铁摄取不同途径的因素和机制的理解，以发现几种新的运输抑制剂。我们的目标是表征这些化合物在体内和体外的活性，并使用化学遗传学发现新的小分子抑制剂。我们将使用这些试剂来通过以下特定目的来促进对铁吸收的因素，机制和调节的理解：1）表征小分子抑制剂对大鼠和小鼠铁转运的影响。使用化学遗传学，我们发现铁蛋白抑制了血清铁结合蛋白转移蛋白的受体介导的内吞作用中的铁吸收。铁蛋白还可以阻止DMT1的铁吸收，DMT1是一种亚铁转运蛋白，在肠肠上皮细胞的根尖膜中以及铁递送到内体中通过转铁蛋白介导的途径发挥了铁的铁吸收。我们建议检查体内铁脂蛋白和相关化合物的作用； 2）确定铁脂蛋白在体外抑制铁转运的分子机制。我们已经表明，铁蛋白质通过通过网状蛋白独立的内吞途径诱导转铁蛋白受体降解来抑制转铁蛋白介导的铁摄取。铁脂蛋白的作用通过胆固醇耗竭拮抗，表明可能涉及脂质筏微区。铁蛋白也通过DMT1阻断了铁的吸收，但抑制的机理仍有待鉴定。我们建议测试铁蛋白的假设，即使用细胞分子方法通过脂质微域调节了两种铁的转运途径。 3）识别和表征DMT1的新型小分子抑制剂。最近的组合库筛选产生了一类新的与结构相关的小分子抑制剂DMT1。我们建议定义它们对DMT1介导的运输，转铁蛋白介导的铁吸收和非转移蛋白结合的铁吸收的影响，并使用分子文库筛选网络（MLSN）系统继续发现抑制剂。 公共卫生相关性：铁缺乏症仍然是我国最普遍的营养问题，但最近对负责遗传性血色素沉着症的基因的鉴定表明，有1只高加索人携带缺陷的等位基因，因此400中的1个可能容易受到铁超载的影响。对运输因素及其防御能力缺乏和超负荷的越来越多的知识对于更广泛地解决这些重大健康问题至关重要。