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

基本信息

批准号：
9920132
负责人：
James F. Collins
金额：
$ 51.14万
依托单位：
UNIVERSITY OF FLORIDA
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-07-15 至 2023-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9920132
关键词：
Adult Anemia Arthritis Binding Biochemical Cardiomyopathies Chronic Complex Copper Data Development Diabetes Mellitus Dietary Iron Disease Duodenum Enterocytes Epithelial 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 Therapeutic Tissues Transferrin absorption bariatric surgery base basolateral membrane brush border membrane clinically significant divalent metal falls hepcidin in vivo insight iron absorption 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 siRNA delivery thalassemia intermedia therapeutic target uptake vector young woman

项目摘要

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.

项目摘要铁是人类必不可少的营养素，但超过铁是有毒的。因此，铁超载和铁缺乏症导致严重的稳态扰动。铁超负荷最常与遗传有关血色素沉着病（HH），其中HH患者的美国组织铁积累〜1：250 导致关节炎，骨质疏松症，肝脏损伤和癌症，心肌病，糖尿病和阳ot。 HH导致铁调节马酮肝素（HEPC）的产生受损或由于汉普基因中的突变（编码HEPC）。 HEPC限制了肠道滥用。而且，减少了 HEPC的合成是铁负荷的基础，即典型的无效性红细胞生成疾病（例如β-- Thalassyia Intermedia [βTI]）。在HH和βTI中，肠道吸收量太高。这导致病理铁超负荷，因为人类不能极大的铁。滥用肠道铁的调节是因此，对于正确控制人体铁的水平至关重要。饮食铁作为无机（或非血红素）铁的主要存在。首先将铁（Fe3+）非血红素铁还原为Fe2+，并通过二价金属离子进口到十二指肠肠细胞中转运蛋白1（DMT1），由亚铁蛋白1（FPN1）导出，并氧化以与转铁蛋白结合。 DMT1是在基本条件下，初级肠道进口商，但DMT1对铁的相对贡献 HH和βTI中的积累尚不清楚。在AIM 1中，我们将测试需要DMT1的假设用于HH（HEPC KO）和βTI的小鼠模型中的铁载 B1]）基因。因此，我们将产生也缺乏肠道DMT1的HEPC和HBB-B1 KO小鼠。我们进一步假设降低DMT1表达将防止HH和βTI中的铁负荷。根据，我们有开发了生姜纳米粒子衍生的脂质载体（GNLV），可以将功能性DMT1 siRNA传递到小鼠十二指肠体内（DMT1表达降低约40％）。在AIM 2中，此GNLV交付系统将是测试了其预防HH和βTI啮齿动物模型中铁负荷的能力。此外，铁缺乏症（ID）是在美国也很常见，遭受了约800万年轻妇女和70万名婴儿。当id经常发生时饮食中铁的吸收无法满足人体的需求。 id最常见的是由于快速生长，怀孕，月经流失，不良疾病，胃搭桥手术和慢性炎。 ID症状包括贫血，认知受损，免疫反应降低和疲劳。在ID期间，DMT1增加了CU的运输到十二指肠肠细胞，并且新兴数据表明这表明了这一点铜对于在不足状态下支持铁补充至关重要。转换DMT1的机制但是，进入铜转运蛋白是未知的。 AIM 3因此将检验DMT1蛋白是在铁缺乏期间，翻译后修饰，允许CU运输。合理的替代假设也可以考虑。总体而言，这项以DMT1为中心的调查可能有可能发展新型的热和营养方法来调节高危个体的肠道滥用。