Divalent Metal-ion Transporter 1 as a Therapeutic Target to Optimize Intestinal Iron Transport

二价金属离子转运蛋白 1 作为优化肠道铁转运的治疗靶点

• 批准号: 9314563
• 负责人: James F. Collins
• 金额: $ 51.35万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-15 至 2021-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9314563
• 关键词: Adult; Anemia; Arthritis; Binding; Biochemical; Cardiomyopathies; Chronic; Complex; Copper; Data; Development; Diabetes Mellitus; Dietary Iron; Disease; Duodenum; Enterocytes; Epithelium; Erythropoiesis; Fatigue; Future; Gene Silencing; Genes; Ginger; Globin; Goals; Hemorrhage; Hereditary hemochromatosis; Homeostasis; Hormones; Human; Hypoxia; Immune response; Immunologic Techniques; Impaired cognition; Impairment; Impotence; Individual; Infant; Inflammation; Inherited; Intestines; Investigation; Ions; Iron; Iron Overload; Knockout Mice; Lipids; Maintenance; Malignant neoplasm of liver; Mediating; Mediator of activation protein; Modality; Modeling; Molecular; Morbidity - disease rate; Mus; Mutate; Mutation; Nutrient; Nutritional; Osteoporosis; Oxides; Pathologic; Patients; Physiological; Play; Post-Translational Protein Processing; Pregnancy; Process; Production; Property; Proteins; Rat Cell Line; Rattus; Regulation; Risk; Rodent Model; Role; Small Interfering RNA; Small Intestines; Structure; Symptoms; System; Technology; Testing; Thalassemia intermedia; Therapeutic; Tissues; Transferrin; absorption; bariatric surgery; base; basolateral membrane; beta Thalassemia; brush border membrane; clinically significant; divalent metal; falls; hepcidin; in vivo; insight; iron deficiency; liver injury; mRNA Expression; metal transporting protein 1; mortality; mouse model; nanoparticle; novel; novel therapeutics; nutritional approach; pre-clinical; prevent; prophylactic; protein function; rapid growth; therapeutic target; uptake; vector; young woman

Project Summary Iron is an essential nutrient for humans, yet excess iron is toxic. As such, iron overload and iron deficiency result in severe homeostatic perturbations. Iron overload is most frequently associated with hereditary hemochromatosis (HH), which afflicts ~1:250 adults in the U.S. Tissue iron accumulation in patients with HH leads to arthritis, osteoporosis, liver damage and cancer, cardiomyopathy, diabetes mellitus, and impotence. HH results from impaired production of the iron-regulatory hormone hepcidin (HEPC) or as a result of mutations in the HAMP gene (encoding HEPC). HEPC limits intestinal iron absorption. Moreover, reduced HEPC synthesis underlies the iron loading that typifies disorders of ineffective erythropoiesis (e.g. β- thalassemia intermedia [βTI]). In HH and βTI, intestinal iron absorption is thus excessive. This leads to pathological iron overload since humans cannot excrete excess iron. Regulation of intestinal iron absorption is thus critical to properly control body iron levels. Dietary iron exists primarily as inorganic (or nonheme) iron. Ferric (Fe3+) nonheme iron is first reduced to Fe2+, imported into duodenal enterocytes by divalent metal-ion transporter 1 (DMT1), exported by ferroportin 1 (FPN1) and oxidized for binding to transferrin. DMT1 is the primary intestinal iron importer under basal conditions, but the relative contribution of DMT1 to iron accumulation in HH and βTI is unknown. In Aim 1, we will thus test the hypothesis that DMT1 is required for iron loading in mouse models of HH (HEPC KO) and βTI (Hbbd3th; with a mutated β major globin [Hbb- b1]) gene. We will thus generate HEPC and Hbb-b1 KO mice that are also lacking intestinal DMT1. We further hypothesize that decreasing DMT1 expression will prevent iron loading in HH and βTI. Accordingly, we have developed ginger nanoparticle-derived lipid vectors (GNLVs) which can deliver functional DMT1 siRNA to the mouse duodenum in vivo (~40% reduction in DMT1 expression). In Aim 2, this GNLV delivery system will be tested for its ability to prevent iron loading in rodent models of HH and βTI. Furthermore, iron deficiency (ID) is also common in the U.S., afflicting ~8 million young women, and 700,000 infants. ID frequently occurs when absorption of dietary iron does not meet the body’s demand. ID most commonly occurs as a consequence of rapid growth, pregnancy, menstrual blood loss, malabsorptive disorders, gastric bypass surgery and chronic inflammation. ID symptoms include anemia, impaired cognition, decreased immune response, and fatigue. During ID, DMT1 increases Cu transport into duodenal enterocytes and emerging data demonstrates that copper is critical to support iron repletion during states of deficiency. The mechanism that transforms DMT1 into a copper transporter is, however, unknown. Aim 3 will thus test the hypothesis that the DMT1 protein is post-translationally modified during iron deficiency, allowing Cu transport. Plausible alternative hypotheses may also be considered. Overall, this DMT1-focused investigation is likely to potentiate the development of novel therapeutic and nutritional approaches to modulate intestinal iron absorption in at-risk individuals.

项目摘要 铁是人体必需的营养素，但过量的铁是有毒的。因此，铁过量和缺铁 导致严重的体内平衡紊乱铁超负荷最常与遗传性 血色素沉着症（HH），在美国约有1：250的成年人患有HH患者的组织铁蓄积 导致关节炎、骨质疏松症、肝损伤和癌症、心肌病、糖尿病和阳痿。 HH由铁调节激素铁调素（HEPC）的产生受损或由于 HAMP基因（编码HEPC）中的突变。HEPC限制肠道铁吸收。此外，减少 HEPC合成是铁负载的基础，铁负载代表无效红细胞生成障碍（例如β-造血干细胞）。 中间型地中海贫血[βTI]。因此，在HH和βTI中，肠铁吸收过量。这导致 病理性铁超载，因为人类不能排出多余的铁。肠铁吸收的调节是 因此对适当控制体内铁水平至关重要。膳食铁主要以无机（或非血红素）铁的形式存在。 铁（Fe 3+）非血红素铁首先被还原为Fe 2+，通过二价金属离子转运到十二指肠细胞中， 转运蛋白1（DMT 1），由膜铁转运蛋白1（FPN 1）输出并被氧化以结合转铁蛋白。DMT 1是 在基础条件下，主要肠道铁进口商，但DMT 1对铁的相对贡献 HH和βTI中的蓄积未知。因此，在目标1中，我们将检验DMT 1是必需的假设 对于HH（HEPC KO）和βTI（Hbbd 3 th;具有突变的β主要珠蛋白[Hbb-3 th]）的小鼠模型中的铁负荷， b1]）基因。因此，我们将产生同样缺乏肠道DMT 1的HEPC和Hbb-b1 KO小鼠。我们进一步 假设DMT 1表达降低将阻止HH和βTI中的铁负荷。因此，我们有 开发了生姜纳米颗粒衍生的脂质载体（GNLV），可以将功能性DMT 1 siRNA递送到 小鼠体内十二指肠（DMT 1表达减少约40%）。在目标2中，该GNLV输送系统将 测试其在HH和βTI的啮齿动物模型中防止铁负荷的能力。缺铁（ID） 在美国也很常见，约800万年轻女性和70万婴儿患病。ID经常发生在 膳食铁的吸收不能满足身体的需求。ID最常发生的结果是 快速生长、妊娠、月经失血、吸收障碍、胃旁路手术和慢性 炎症ID症状包括贫血、认知受损、免疫反应降低和疲劳。 在ID期间，DMT 1增加了Cu转运到十二指肠上皮细胞中，新的数据表明， 在缺铁状态下，铜对于支持铁的补充是至关重要的。DMT 1的转化机制 转化成铜转运体的可能性尚不清楚因此，目的3将检验DMT 1蛋白是 在缺铁期间进行后期修饰，允许Cu运输。合理的替代假设 也可以考虑。总的来说，这项以DMT 1为重点的研究可能会促进以下方面的发展： 新的治疗和营养方法来调节高危个体的肠铁吸收。