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Collins JF. Intestinal Stem Cells Require Iron to Orchestrate Tissue Repair Mechanisms. J Nutr 2024; 154:1067-1068. [PMID: 38403253 DOI: 10.1016/j.tjnut.2024.02.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 02/19/2024] [Indexed: 02/27/2024] Open
Affiliation(s)
- James F Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, United States.
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Zeidan RS, Martenson M, Tamargo JA, McLaren C, Ezzati A, Lin Y, Yang JJ, Yoon HS, McElroy T, Collins JF, Leeuwenburgh C, Mankowski RT, Anton S. Iron homeostasis in older adults: balancing nutritional requirements and health risks. J Nutr Health Aging 2024; 28:100212. [PMID: 38489995 DOI: 10.1016/j.jnha.2024.100212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/05/2024] [Accepted: 03/06/2024] [Indexed: 03/17/2024]
Abstract
Iron plays a crucial role in many physiological processes, including oxygen transport, bioenergetics, and immune function. Iron is assimilated from food and also recycled from senescent red blood cells. Iron exists in two dietary forms: heme (animal based) and non-heme (mostly plant based). The body uses iron for metabolic purposes, and stores the excess mainly in splenic and hepatic macrophages. Physiologically, iron excretion in humans is inefficient and not highly regulated, so regulation of intestinal absorption maintains iron homeostasis. Iron losses occur at a steady rate via turnover of the intestinal epithelium, blood loss, and exfoliation of dead skin cells, but overall iron homeostasis is tightly controlled at cellular and systemic levels. Aging can have a profound impact on iron homeostasis and induce a dyshomeostasis where iron deficiency or overload (sometimes both simultaneously) can occur, potentially leading to several disorders and pathologies. To maintain physiologically balanced iron levels, reduce risk of disease, and promote healthy aging, it is advisable for older adults to follow recommended daily intake guidelines and periodically assess iron levels. Clinicians can evaluate body iron status using different techniques but selecting an assessment method primarily depends on the condition being examined. This review provides a comprehensive overview of the forms, sources, and metabolism of dietary iron, associated disorders of iron dyshomeostasis, assessment of iron levels in older adults, and nutritional guidelines and strategies to maintain iron balance in older adults.
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Affiliation(s)
- Rola S Zeidan
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA; Department of Health Outcomes and Biomedical Informatics, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Matthew Martenson
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Javier A Tamargo
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Christian McLaren
- Department of Clinical and Health Psychology, College of Health and Health Professions, University of Florida, Gainesville, Florida, USA
| | - Armin Ezzati
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA; Department of Food, Nutrition, Dietetics and Health, Kansas State University, Manhattan, KS, USA
| | - Yi Lin
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Jae Jeong Yang
- UF Health Cancer Center, Gainesville, FL, USA; Department of Surgery, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Hyung-Suk Yoon
- UF Health Cancer Center, Gainesville, FL, USA; Department of Surgery, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Taylor McElroy
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA; Department of Health Outcomes and Biomedical Informatics, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - James F Collins
- Department of Food Science & Human Nutrition, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Christiaan Leeuwenburgh
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Robert T Mankowski
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Stephen Anton
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL, USA; Department of Clinical and Health Psychology, College of Health and Health Professions, University of Florida, Gainesville, Florida, USA.
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Ebea PO, Vidyasagar S, Connor JR, Frazer DM, Knutson MD, Collins JF. Oral iron therapy: Current concepts and future prospects for improving efficacy and outcomes. Br J Haematol 2024; 204:759-773. [PMID: 38253961 PMCID: PMC10939879 DOI: 10.1111/bjh.19268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 12/01/2023] [Accepted: 12/08/2023] [Indexed: 01/24/2024]
Abstract
Iron deficiency (ID) and iron-deficiency anaemia (IDA) are global public health concerns, most commonly afflicting children, pregnant women and women of childbearing age. Pathological outcomes of ID include delayed cognitive development in children, adverse pregnancy outcomes and decreased work capacity in adults. IDA is usually treated by oral iron supplementation, typically using iron salts (e.g. FeSO4 ); however, dosing at several-fold above the RDA may be required due to less efficient absorption. Excess enteral iron causes adverse gastrointestinal side effects, thus reducing compliance, and negatively impacts the gut microbiome. Recent research has sought to identify new iron formulations with better absorption so that lower effective dosing can be utilized. This article outlines emerging research on oral iron supplementation and focuses on molecular mechanisms by which different supplemental forms of iron are transported across the intestinal epithelium and whether these transport pathways are subject to regulation by the iron-regulatory hormone hepcidin.
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Affiliation(s)
- Pearl O. Ebea
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | | | - James R. Connor
- Department of Neurosurgery, Penn State College of Medicine, Hershey, PA, USA
| | - David M. Frazer
- Molecular Nutrition Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Mitchell D. Knutson
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - James F. Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
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Sasidharan A, Peethambar BA, Kumar KS, Kumar AV, Hiregange A, Fawkes N, Collins JF, Grosche A, Vidyasagar S. Advancing peristalsis deciphering in mouse small intestine by multi-parameter tracking. Commun Biol 2023; 6:1237. [PMID: 38062160 PMCID: PMC10703907 DOI: 10.1038/s42003-023-05631-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 11/23/2023] [Indexed: 12/18/2023] Open
Abstract
Assessing gastrointestinal motility lacks simultaneous evaluation of intraluminal pressure (ILP), circular muscle (CM) and longitudinal muscle (LM) contraction, and lumen emptying. In this study, a sophisticated machine was developed that synchronized real-time recordings to quantify the intricate interplay between CM and LM contractions, and their timings for volume changes using high-resolution cameras with machine learning capability, the ILP using pressure transducers and droplet discharge (DD) using droplet counters. Results revealed four distinct phases, BPhase, NPhase, DPhase, and APhase, distinguished by pressure wave amplitudes. Fluid filling impacted LM strength and contraction frequency initially, followed by CM contraction affecting ILP, volume, and the extent of anterograde, retrograde, and segmental contractions during these phases that result in short or long duration DD. This comprehensive analysis sheds light on peristalsis mechanisms, understand their sequence and how one parameter influenced the other, offering insights for managing peristalsis by regulating smooth muscle contractions.
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Affiliation(s)
- Anusree Sasidharan
- Department of Radiation Oncology, University of Florida, Gainesville, FL, USA
| | | | | | - Ashok V Kumar
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA
| | | | | | - James F Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Astrid Grosche
- Department of Radiation Oncology, University of Florida, Gainesville, FL, USA
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Yu Y, Woloshun RR, Lee JK, Ebea PO, Zhu S, Nemeth E, Garrick LM, Garrick MD, Collins JF. Fetal factors disrupt placental and maternal iron homeostasis in murine β-thalassemia. Blood 2023; 142:185-196. [PMID: 37146247 PMCID: PMC10352602 DOI: 10.1182/blood.2022018839] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 03/28/2023] [Accepted: 04/17/2023] [Indexed: 05/07/2023] Open
Abstract
Pregnancy rates in β-thalassemia are increasing but the risk of complications is higher; thus, better understanding of maternal and fetal iron homeostasis in this disorder is needed. HbbTh3/+ (Th3/+) mice model human β-thalassemia. Both the murine and human diseases are characterized by low hepcidin, high iron absorption, and tissue iron overload, with concurrent anemia. We hypothesized that disordered iron metabolism in pregnant Th3/+ mice would negatively affect their unborn offspring. The experimental design included these groups: wild-type (WT) dams carrying WT fetuses (WT1); WT dams carrying WT and Th3/+ fetuses (WT2); Th3/+ dams carrying WT and Th3/+ fetuses (Th3/+); and age-matched, nonpregnant adult females. Serum hepcidin was low, and mobilization of splenic and hepatic storage iron was enhanced in all 3 groups of experimental dams. Intestinal 59Fe absorption was lower in Th3/+ dams (as compared with WT1/2 dams) but splenic 59Fe uptake was higher. Th3/+ dams had hyperferremia, which led to fetal and placenta iron loading, fetal growth restriction, and placentomegaly. Notably, Th3/+ dams loaded Th3/+ and WT fetuses, with the latter situation more closely mirroring human circumstances when mothers with thalassemia have relatively unaffected (thalassemia trait) offspring. Iron-related oxidative stress likely contributed to fetal growth impairment; enhanced placental erythropoiesis is a probable cause of placental enlargement. Moreover, high fetal liver iron transactivated Hamp; fetal hepcidin downregulated placental ferroportin expression, limiting placental iron flux and thus mitigating fetal iron loading. Whether gestational iron loading occurs in human thalassemic pregnancy, when blood transfusion can further elevate serum iron, is worth consideration.
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Affiliation(s)
- Yang Yu
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL
| | - Regina R. Woloshun
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL
| | - Jennifer K. Lee
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL
| | - Pearl Onuwa Ebea
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL
| | - Sean Zhu
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL
| | - Elizabeta Nemeth
- Department of Medicine, University of California, Los Angeles, CA
| | | | | | - James F. Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL
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Shi L, Tao Z, Zheng L, Yang J, Hu X, Scott K, de Kloet A, Krause E, Collins JF, Cheng Z. FoxO1 regulates adipose transdifferentiation and iron influx by mediating Tgfβ1 signaling pathway. Redox Biol 2023; 63:102727. [PMID: 37156218 DOI: 10.1016/j.redox.2023.102727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 04/24/2023] [Accepted: 04/30/2023] [Indexed: 05/10/2023] Open
Abstract
Adipose plasticity is critical for metabolic homeostasis. Adipocyte transdifferentiation plays an important role in adipose plasticity, but the molecular mechanism of transdifferentiation remains incompletely understood. Here we show that the transcription factor FoxO1 regulates adipose transdifferentiation by mediating Tgfβ1 signaling pathway. Tgfβ1 treatment induced whitening phenotype in beige adipocytes, reducing UCP1 and mitochondrial capacity and enlarging lipid droplets. Deletion of adipose FoxO1 (adO1KO) dampened Tgfβ1 signaling by downregulating Tgfbr2 and Smad3 and induced browning of adipose tissue in mice, increasing UCP1 and mitochondrial content and activating metabolic pathways. Silencing FoxO1 also abolished the whitening effect of Tgfβ1 on beige adipocytes. The adO1KO mice exhibited a significantly higher energy expenditure, lower fat mass, and smaller adipocytes than the control mice. The browning phenotype in adO1KO mice was associated with an increased iron content in adipose tissue, concurrent with upregulation of proteins that facilitate iron uptake (DMT1 and TfR1) and iron import into mitochondria (Mfrn1). Analysis of hepatic and serum iron along with hepatic iron-regulatory proteins (ferritin and ferroportin) in the adO1KO mice revealed an adipose tissue-liver crosstalk that meets the increased iron requirement for adipose browning. The FoxO1-Tgfβ1 signaling cascade also underlay adipose browning induced by β3-AR agonist CL316243. Our study provides the first evidence of a FoxO1-Tgfβ1 axis in the regulation of adipose browning-whitening transdifferentiation and iron influx, which sheds light on the compromised adipose plasticity in conditions of dysregulated FoxO1 and Tgfβ1 signaling.
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Affiliation(s)
- Limin Shi
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, 32611, USA; Interdisciplinary Nutritional Sciences Doctoral Program, Center for Nutritional Sciences, University of Florida, Gainesville, FL, 32611, USA; Center for Integrative Cardiovascular and Metabolic Diseases, University of Florida, Gainesville, FL, 32610, USA
| | - Zhipeng Tao
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, Blacksburg, VA, 24061, USA; Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Louise Zheng
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Jinying Yang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, 32611, USA; Interdisciplinary Nutritional Sciences Doctoral Program, Center for Nutritional Sciences, University of Florida, Gainesville, FL, 32611, USA
| | - Xinran Hu
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, 32611, USA
| | - Karen Scott
- Center for Integrative Cardiovascular and Metabolic Diseases, University of Florida, Gainesville, FL, 32610, USA; Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL32610, USA
| | - Annette de Kloet
- Center for Integrative Cardiovascular and Metabolic Diseases, University of Florida, Gainesville, FL, 32610, USA; Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, FL, 32610, USA
| | - Eric Krause
- Center for Integrative Cardiovascular and Metabolic Diseases, University of Florida, Gainesville, FL, 32610, USA; Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL32610, USA
| | - James F Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, 32611, USA; Interdisciplinary Nutritional Sciences Doctoral Program, Center for Nutritional Sciences, University of Florida, Gainesville, FL, 32611, USA
| | - Zhiyong Cheng
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, 32611, USA; Interdisciplinary Nutritional Sciences Doctoral Program, Center for Nutritional Sciences, University of Florida, Gainesville, FL, 32611, USA; Center for Integrative Cardiovascular and Metabolic Diseases, University of Florida, Gainesville, FL, 32610, USA; Department of Human Nutrition, Foods, and Exercise, Virginia Tech, Blacksburg, VA, 24061, USA.
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Helman SL, Zhou J, Fuqua BK, Lu Y, Collins JF, Chen H, Vulpe CD, Anderson GJ, Frazer DM. The biology of mammalian multi-copper ferroxidases. Biometals 2023; 36:263-281. [PMID: 35167013 PMCID: PMC9376197 DOI: 10.1007/s10534-022-00370-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 02/04/2022] [Indexed: 12/24/2022]
Abstract
The mammalian multicopper ferroxidases (MCFs) ceruloplasmin (CP), hephaestin (HEPH) and zyklopen (ZP) comprise a family of conserved enzymes that are essential for body iron homeostasis. Each of these enzymes contains six biosynthetically incorporated copper atoms which act as intermediate electron acceptors, and the oxidation of iron is associated with the four electron reduction of dioxygen to generate two water molecules. CP occurs in both a secreted and GPI-linked (membrane-bound) form, while HEPH and ZP each contain a single C-terminal transmembrane domain. These enzymes function to ensure the efficient oxidation of iron so that it can be effectively released from tissues via the iron export protein ferroportin and subsequently bound to the iron carrier protein transferrin in the blood. CP is particularly important in facilitating iron release from the liver and central nervous system, HEPH is the major MCF in the small intestine and is critical for dietary iron absorption, and ZP is important for normal hair development. CP and HEPH (and possibly ZP) function in multiple tissues. These proteins also play other (non-iron-related) physiological roles, but many of these are ill-defined. In addition to disrupting iron homeostasis, MCF dysfunction perturbs neurological and immune function, alters cancer susceptibility, and causes hair loss, but, despite their importance, how MCFs co-ordinately maintain body iron homeostasis and perform other functions remains incompletely understood.
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Affiliation(s)
- Sheridan L Helman
- Molecular Nutrition Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Jie Zhou
- Department of Physiological Sciences, University of Florida, Gainsville, FL, USA
| | - Brie K Fuqua
- David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Yan Lu
- Iron Metabolism Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Road, Brisbane, QLD, 4006, Australia
- Mucosal Immunology Group, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - James F Collins
- Food Science and Human Nutrition Department, University of Florida, Gainsville, FL, USA
| | - Huijun Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Christopher D Vulpe
- Department of Physiological Sciences, University of Florida, Gainsville, FL, USA
| | - Gregory J Anderson
- Iron Metabolism Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Road, Brisbane, QLD, 4006, Australia.
- School of Chemistry and Molecular Bioscience, University of Queensland, Brisbane, Australia.
| | - David M Frazer
- Molecular Nutrition Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia
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Lee JK, Yu Y, DeLellis RR, Ebea P, Zhu S, Theophilus R, Collins JF. Establishing Dietary Iron Requirements for Mouse and Rat Models of Hereditary Hemochromatosis. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r2602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jennifer K. Lee
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - Yang Yu
- University of FloridaGainesvilleFL
| | | | - Pearl Ebea
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - Sean Zhu
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - Rufus Theophilus
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - James F. Collins
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
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Yu Y, Yang C, Shine JS, Lee JK, Ebea P, Zhu S, Merlin D, Collins JF. Intestinal Dmt1 is Required for Iron Loading in Mice Modeling β‐Thalassemia Intermedia. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r1912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yang Yu
- Food science and Human NutritionUniversity of FloridaGainesvilleFL
| | | | | | | | | | - Sean Zhu
- University of FloridaGainesvilleFL
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Affiliation(s)
- Jason L Burkhead
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK, USA
| | - James F Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA.
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Collins JF. A Synthetic Ferritin Core Analog Functions as a Next-Generation Iron Supplement. J Nutr 2022; 152:651-652. [PMID: 35134990 PMCID: PMC8891172 DOI: 10.1093/jn/nxab436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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Flores SRL, Nelson S, Woloshun RR, Wang X, Ha JH, Lee JK, Yu Y, Merlin D, Collins JF. Intestinal iron absorption is appropriately modulated to match physiological demand for iron in wild-type and iron-loaded Hamp (hepcidin) knockout rats during acute colitis. PLoS One 2021; 16:e0252998. [PMID: 34143808 PMCID: PMC8213193 DOI: 10.1371/journal.pone.0252998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 05/26/2021] [Indexed: 11/18/2022] Open
Abstract
Mucosal damage, barrier breach, inflammation, and iron-deficiency anemia (IDA) typify ulcerative colitis (UC) in humans. The anemia in UC appears to mainly relate to systemic inflammation. The pathogenesis of this ‘anemia of inflammation’ (AI) involves cytokine-mediated transactivation of hepatic Hamp (encoding the iron-regulatory hormone, hepcidin). In AI, high hepcidin represses iron absorption (and iron release from stores), thus lowering serum iron, and restricting iron for erythropoiesis (causing anemia). In less-severe disease states, inflammation may be limited to the intestine, but whether this perturbs iron homeostasis is uncertain. We hypothesized that localized gut inflammation will increase overall iron demand (to support the immune response and tissue repair), and that hepatic Hamp expression will decrease in response, thus derepressing (i.e., enhancing) iron absorption. Accordingly, we developed a rat model of mild, acute colitis, and studied iron absorption and homeostasis. Rats exposed (orally) to DSS (4%) for 7 days had intestinal (but not systemic) inflammation, and biomarker analyses demonstrated that iron utilization was elevated. Iron absorption was enhanced (by 2-3-fold) in DSS-treated, WT rats of both sexes, but unexpectedly, hepatic Hamp expression was not suppressed. Therefore, to gain a better understanding of regulation of iron absorption during acute colitis, Hamp KO rats were used for further experimentation. The severity of DSS-colitis was similar in Hamp KOs as in WT controls. In the KOs, increased iron requirements associated with the physiological response to colitis were satisfied by mobilizing hepatic storage iron, rather than by increasing absorption of enteral iron (as occurred in WT rats). In conclusion then, in both sexes and genotypes of rats, iron absorption was appropriately modulated to match physiological demand for dietary iron during acute intestinal inflammation, but regulatory mechanisms may not involve hepcidin.
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Affiliation(s)
- Shireen R. L. Flores
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, United States of America
| | - Savannah Nelson
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, United States of America
| | - Regina R. Woloshun
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, United States of America
| | - Xiaoyu Wang
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, United States of America
| | - Jung-Heun Ha
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, United States of America
| | - Jennifer K. Lee
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, United States of America
| | - Yang Yu
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, United States of America
| | - Didier Merlin
- Center for Diagnostics and Therapeutics, Institute for Biomedical Science, Georgia State University, Atlanta, GA, United States of America
- Atlanta Veterans Affairs Medical Center, Decatur, GA, United States of America
| | - James F. Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, United States of America
- * E-mail:
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Wang X, Zhang M, Woloshun RR, Yu Y, Lee JK, Flores SRL, Merlin D, Collins JF. Oral Administration of Ginger-Derived Lipid Nanoparticles and Dmt1 siRNA Potentiates the Effect of Dietary Iron Restriction and Mitigates Pre-Existing Iron Overload in Hamp KO Mice. Nutrients 2021; 13:1686. [PMID: 34063414 PMCID: PMC8157040 DOI: 10.3390/nu13051686] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 12/28/2022] Open
Abstract
Intestinal iron transport requires an iron importer (Dmt1) and an iron exporter (Fpn1). The hormone hepcidin regulates iron absorption by modulating Fpn1 protein levels on the basolateral surface of duodenal enterocytes. In the genetic, iron-loading disorder hereditary hemochromatosis (HH), hepcidin production is low and Fpn1 protein expression is elevated. High Fpn1-mediated iron export depletes intracellular iron, causing a paradoxical increase in Dmt1-mediated iron import. Increased activity of both transporters causes excessive iron absorption, thus initiating body iron loading. Logically then, silencing of intestinal Dmt1 or Fpn1 could be an effective therapeutic intervention in HH. It was previously established that Dmt1 knock down prevented iron-loading in weanling Hamp (encoding hepcidin) KO mice (modeling type 2B HH). Here, we tested the hypothesis that Dmt1 silencing combined with dietary iron restriction (which may be recommended for HH patients) will mitigate iron loading once already established. Accordingly, adult Hamp KO mice were switched to a low-iron (LFe) diet and (non-toxic) folic acid-coupled, ginger nanoparticle-derived lipid vectors (FA-GDLVs) were used to deliver negative-control (NC) or Dmt1 siRNA by oral, intragastric gavage daily for 21 days. The LFe diet reduced body iron burden, and experimental interventions potentiated iron losses. For example, Dmt1 siRNA treatment suppressed duodenal Dmt1 mRNA expression (by ~50%) and reduced serum and liver non-heme iron levels (by ~60% and >85%, respectively). Interestingly, some iron-related parameters were repressed similarly by FA-GDLVs carrying either siRNA, including 59Fe (as FeCl3) absorption (~20% lower), pancreatic non-heme iron (reduced by ~65%), and serum ferritin (decreased 40-50%). Ginger may thus contain bioactive lipids that also influence iron homeostasis. In conclusion, the combinatorial approach of FA-GDLV and Dmt1 siRNA treatment, with dietary iron restriction, mitigated pre-existing iron overload in a murine model of HH.
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Affiliation(s)
- Xiaoyu Wang
- Key Laboratory of Precision Nutrition and Food Quality, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China;
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA; (R.R.W.); (Y.Y.); (J.K.L.); (S.R.L.F.)
| | - Mingzhen Zhang
- Center for Diagnostics and Therapeutics, Institute for Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (M.Z.); (D.M.)
- School of Basic Medical Science, Health Science Center, Institute of Medical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
| | - Regina R. Woloshun
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA; (R.R.W.); (Y.Y.); (J.K.L.); (S.R.L.F.)
| | - Yang Yu
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA; (R.R.W.); (Y.Y.); (J.K.L.); (S.R.L.F.)
| | - Jennifer K. Lee
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA; (R.R.W.); (Y.Y.); (J.K.L.); (S.R.L.F.)
| | - Shireen R. L. Flores
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA; (R.R.W.); (Y.Y.); (J.K.L.); (S.R.L.F.)
| | - Didier Merlin
- Center for Diagnostics and Therapeutics, Institute for Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (M.Z.); (D.M.)
- Atlanta Veterans Affairs Medical Center, Decatur, GA 30033, USA
| | - James F. Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA; (R.R.W.); (Y.Y.); (J.K.L.); (S.R.L.F.)
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14
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Abstract
The essential trace mineral copper plays important roles in human physiology and pathophysiology. Disruption of copper homeostasis may underlie the development of ischemic heart disease, and connective tissue and neurodegenerative disorders. Copper also likely participates in the host response to bacterial infection and is further implicated more broadly in regulating immunity. Recent studies further associate copper with disruption of lipid homeostasis, as is frequently seen in, for example, non-alcoholic fatty liver disease (NAFLD). Moreover, continuing investigation of copper chaperones has revealed new roles for these intracellular copper-binding proteins. Despite these (and many other) significant advances, many questions related to copper biology remain unanswered. For example, what are the most sensitive and specific biomarkers of copper status, and which ones are useful in marginal (or "sub-clinical" copper deficiency)? Further research on this topic is required to inform future investigations of copper metabolism in humans (so the copper status of study participants can be fully appreciated). Also, are current recommendations for copper intake adequate? Recent studies suggest that overt copper deficiency is more common than once thought, and further, some have suggested that the copper RDAs for adults may be too low. Additional human balance and interventional studies are necessary and could provide the impetus for reconsidering the copper RDAs in the future. These and myriad other unresolved aspects of copper nutrition will undoubtedly be the focus of future investigation.
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Affiliation(s)
- James F Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, United States.
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15
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Abstract
The nicotianamine-iron chelate [NA-Fe2+], which is found in many plant-based foods, has been recently described as a new form of bioavailable iron in mice and chickens. How NA-Fe2+ is assimilated from the diet, however, remains unclear. The current investigation by Murata et al. has identified the proton-coupled amino acid transporter 1 (PAT1) as the main mechanism by which NA-Fe2+ is absorbed in the mammalian intestine. Discovery of this new form of dietary iron and elucidation of its pathway of intestinal absorption may lead to the development of improved iron supplementation approaches.
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Affiliation(s)
- James F Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, Florida, USA.
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16
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Woloshun RR, Yu Y, Xu X, Lee JK, Zhu S, Theophilus R, Ebea P, Vidyasagar S, Collins JF. Amino Acids Influence DMT1 Trafficking in Duodenal Enterocytes and Modulate Iron Absorption. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.05521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Yu Y, Woloshun RR, Lee JK, Ebea PO, Zhu S, Garrick LM, Garrick MD, Collins JF. Dysregulation of Iron Homeostasis in Beta‐thalassemia Intermedia (
Th3/+
) Mice During Pregnancy. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.06903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Sung J, Yang C, Collins JF, Merlin D. Preparation and Characterization of Ginger Lipid-derived Nanoparticles for Colon-targeted siRNA Delivery. Bio Protoc 2020; 10:e3685. [PMID: 32782915 DOI: 10.21769/bioprotoc.3685] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Synthetic nanoparticle-based drug delivery system is widely known for its ability to increase the efficacy and specificity of loaded drugs, but it often suffers from relatively higher immunotoxicity and higher costs as compared to traditional drug formulations. Contrarily, plant-derived nanoparticles appear to be free from these limitations of synthetic nanoparticles; they are naturally occurring biocompatible vesicles that do not generate immunotoxicity and are easy to obtain. Additionally, lipids isolated from plant-derived nanoparticles have shown the capability of assembling themselves to spherical nano-sized liposomal particles. Herein, we employ lipids extracted from ginger-derived nanoparticles and load them with therapeutic siRNA (CD98-siRNA) to create CD98-siRNA/ginger-lipid nanoparticles. Characterization of the CD98-siRNA/ginger-lipid nanoparticles showed that they present a spherical shape, with a diameter of around 189.5 nm. The surface zeta potential of the nanoparticles varies from -18.1 to -18.4 mV. Furthermore, in recent research, the CD98-siRNA/ginger-lipid nanoparticles have shown specific colon targeting capability and excellent anti-inflammatory efficacy in a Dextran Sodium Sulfate (DSS) induced mouse model of colitis.
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Affiliation(s)
- Junsik Sung
- Institute for Biomedical Science, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, USA
| | - Chunhua Yang
- Institute for Biomedical Science, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, USA
| | - James F Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Didier Merlin
- Institute for Biomedical Science, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, USA.,Atlanta Veterans Affairs Medical Center, Decatur, GA, USA
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19
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Wang X, Garrick MD, Collins JF. Animal Models of Normal and Disturbed Iron and Copper Metabolism. J Nutr 2019; 149:2085-2100. [PMID: 31504675 PMCID: PMC6887953 DOI: 10.1093/jn/nxz172] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 05/04/2019] [Accepted: 06/28/2019] [Indexed: 01/19/2023] Open
Abstract
Research on the interplay between iron and copper metabolism in humans began to flourish in the mid-20th century, and diseases associated with dysregulated homeostasis of these essential trace minerals are common even today. Iron deficiency is the most frequent cause of anemia worldwide, leading to significant morbidity, particularly in developing countries. Iron overload is also quite common, usually being the result of genetic mutations which lead to inappropriate expression of the iron-regulatory hormone hepcidin. Perturbations of copper homeostasis in humans have also been described, including rare genetic conditions which lead to severe copper deficiency (Menkes disease) or copper overload (Wilson disease). Historically, the common laboratory rat (Rattus norvegicus) was the most frequently utilized species to model human physiology and pathophysiology. Recently, however, the development of genetic-engineering technology combined with the worldwide availability of numerous genetically homogenous (i.e., inbred) mouse strains shifted most research on iron and copper metabolism to laboratory mice. This created new opportunities to understand the function of individual genes in the context of a living animal, but thoughtful consideration of whether mice are the most appropriate models of human pathophysiology was not necessarily involved. Given this background, this review is intended to provide a guide for future research on iron- and copper-related disorders in humans. Generation of complementary experimental models in rats, swine, and other mammals is now facile given the advent of newer genetic technologies, thus providing the opportunity to accelerate the identification of pathogenic mechanisms and expedite the development of new treatments to mitigate these important human disorders.
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Affiliation(s)
- Xiaoyu Wang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Michael D Garrick
- Department of Biochemistry, University at Buffalo–The State University of New York, Buffalo, NY, USA
| | - James F Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA,Address correspondence to JFC (e-mail: )
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20
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Garrick MD, Garrick LM, Zhao L, Collins JF, Soukup J, Ghio AJ. A direct comparison of divalent metal-ion transporter (DMT1) and hinokitiol, a potential small molecule replacement. Biometals 2019; 32:745-755. [PMID: 31368012 PMCID: PMC6768898 DOI: 10.1007/s10534-019-00207-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 07/22/2019] [Indexed: 01/01/2023]
Abstract
Hinokitiol, a natural lipophilic chelator, appears capable of replacing several iron transporters after they have been genetically ablated. Divalent metal-ion transporter (DMT1) is the major iron importer in enterocytes and erythroblasts. We have compared DMT1 and hinokitiol in multiple fashions to learn if the smaller molecule is a suitable substitute using two HEK293 cell lines engineered to overexpress different isoforms of DMT1. Both the macromolecule and the lipophilic chelator enable import of ferrous ions into HEK293 cells. Hinokitiol also mediates ferric ion import but DMT1 cannot do so. While DMT1 can also import Mn2+ ions, hinokitiol lacks this ability. The Michaelis–Menten analysis for kinetics of macromolecular catalysis is also suitable for hinokitiol-supported iron import. To compare hinokitiol to DMT1 relative to other metal ions that DMT1 can transport, we employed an organic extraction procedure with which we initially matched the results obtained for Fe2+, Fe3+ and Mn2+, and then showed that multiple other cations were unlikely to enter via hinokitiol. The small chelator thus shares some functional properties with DMT1, but distinct difference were also noted.
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Affiliation(s)
- Michael D Garrick
- Department of Biochemistry, University at Buffalo, Buffalo, NY, USA. .,Department of Pediatrics, University at Buffalo, Buffalo, NY, USA.
| | - Laura M Garrick
- Department of Biochemistry, University at Buffalo, Buffalo, NY, USA
| | - Lin Zhao
- Department of Biochemistry, University at Buffalo, Buffalo, NY, USA
| | - James F Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Joleen Soukup
- National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Chapel Hill, NC, USA
| | - Andrew J Ghio
- National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Chapel Hill, NC, USA
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21
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Wang X, Zhang M, Flores SR, Woloshun RR, Yang C, Yin L, Xiang P, Xu X, Garrick MD, Vidyasagar S, Merlin D, Collins JF. Oral Delivery of Dmt1 siRNAs by Ginger Nanoparticle‐derived Lipid Vectors Mitigates Iron Loading in Hepcidin KO Mice. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.lb551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xiaoyu Wang
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - Mingzhen Zhang
- Center for Diagnostics and TherapeuticsGeorgia State UniversityAtlantaGA
| | | | | | - Chunhua Yang
- Center for Diagnostics and TherapeuticsGeorgia State UniversityAtlantaGA
| | - Liangjie Yin
- Department of Radiation OncologyUniversity of FloridaGainesvilleFL
| | - Ping Xiang
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - Xiaodong Xu
- Department of Radiation OncologyUniversity of FloridaGainesvilleFL
| | | | | | - Didier Merlin
- Center for Diagnostics and TherapeuticsGeorgia State UniversityAtlantaGA
| | - James F Collins
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
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22
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Woloshun RR, Xu X, Wang X, Yu Y, Flores SRL, Vidyasagar S, Collins JF. Select Amino Acids Alter DMT1 Abundance on the BBM of Intestinal Enterocytes and Enhance or Reduce Iron Flux in Duodenal Organ Cultures. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.lb549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Xiaodong Xu
- Radiation OncologyUniversity of FloridaGainesvilleFL
| | - Xiaoyu Wang
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - Yang Yu
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | | | | | - James F Collins
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
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23
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Wang X, Zhang M, Flores SRL, Woloshun RR, Yang C, Yin L, Xiang P, Xu X, Garrick MD, Vidyasagar S, Merlin D, Collins JF. Oral Gavage of Ginger Nanoparticle-Derived Lipid Vectors Carrying Dmt1 siRNA Blunts Iron Loading in Murine Hereditary Hemochromatosis. Mol Ther 2019; 27:493-506. [PMID: 30713087 PMCID: PMC6401192 DOI: 10.1016/j.ymthe.2019.01.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/21/2018] [Accepted: 01/08/2019] [Indexed: 12/19/2022] Open
Abstract
Nanoparticles (NPs) have been utilized to deliver drugs to the intestinal epithelium in vivo. Moreover, NPs derived from edible plants are less toxic than synthetic NPs. Here, we utilized ginger NP-derived lipid vectors (GDLVs) in a proof-of-concept investigation to test the hypothesis that inhibiting expression of divalent metal-ion transporter 1 (Dmt1) would attenuate iron loading in a mouse model of hereditary hemochromatosis (HH). Initial experiments using duodenal epithelial organ cultures from intestine-specific Dmt1 knockout (KO) (Dmt1int/int) mice in the Ussing chamber established that Dmt1 is the only active iron importer during iron-deficiency anemia. Further, when Dmt1int/int mice were crossed with mice lacking the iron-regulatory hormone, hepcidin (Hepc-/-), iron loading was abolished. Hence, intestinal Dmt1 is required for the excessive iron absorption that typifies HH. Additional experiments established a protocol to produce GDLVs carrying functional Dmt1 small interfering RNAs (siRNAs) and to target these gene delivery vehicles to the duodenal epithelium in vivo (by incorporating folic acid [FA]). When FA-GDLVs carrying Dmt1 siRNA were administered to weanling Hepc-/- mice for 16 days, intestinal Dmt1 mRNA expression was attenuated and tissue iron accumulation was blunted. Oral delivery of functional siRNAs by FA-GDLVs is a suitable therapeutic approach to mitigate iron loading in murine HH.
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Affiliation(s)
- Xiaoyu Wang
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Mingzhen Zhang
- Institute of Medical Engineering, School of Basic Medical Science, Health Science Center, Xi'an Jiaotong University, Xi'an, China; Center for Diagnostics and Therapeutics, Institute for Biomedical Science, Georgia State University, Atlanta, GA, USA
| | - Shireen R L Flores
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Regina R Woloshun
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Chunhua Yang
- Center for Diagnostics and Therapeutics, Institute for Biomedical Science, Georgia State University, Atlanta, GA, USA
| | - Liangjie Yin
- Department of Radiation Oncology, University of Florida, Gainesville, FL, USA
| | - Ping Xiang
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA; State Key Lab of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China
| | - Xiaodong Xu
- Department of Radiation Oncology, University of Florida, Gainesville, FL, USA
| | - Michael D Garrick
- Department of Biochemistry, State University of New York (SUNY), Buffalo, NY, USA
| | | | - Didier Merlin
- Center for Diagnostics and Therapeutics, Institute for Biomedical Science, Georgia State University, Atlanta, GA, USA; Atlanta Veterans Affairs Medical Center, Decatur, GA, USA
| | - James F Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, USA.
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24
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Abstract
Iron and copper have similar physiochemical properties; thus, physiologically relevant interactions seem likely. Indeed, points of intersection between these two essential trace minerals have been recognized for many decades, but mechanistic details have been lacking. Investigations in recent years have revealed that copper may positively influence iron homeostasis, and also that iron may antagonize copper metabolism. For example, when body iron stores are low, copper is apparently redistributed to tissues important for regulating iron balance, including enterocytes of upper small bowel, the liver, and blood. Copper in enterocytes may positively influence iron transport, and hepatic copper may enhance biosynthesis of a circulating ferroxidase, ceruloplasmin, which potentiates iron release from stores. Moreover, many intestinal genes related to iron absorption are transactivated by a hypoxia-inducible transcription factor, hypoxia-inducible factor-2α (HIF2α), during iron deficiency. Interestingly, copper influences the DNA-binding activity of the HIF factors, thus further exemplifying how copper may modulate intestinal iron homeostasis. Copper may also alter the activity of the iron-regulatory hormone hepcidin. Furthermore, copper depletion has been noted in iron-loading disorders, such as hereditary hemochromatosis. Copper depletion may also be caused by high-dose iron supplementation, raising concerns particularly in pregnancy when iron supplementation is widely recommended. This review will cover the basic physiology of intestinal iron and copper absorption as well as the metabolism of these minerals in the liver. Also considered in detail will be current experimental work in this field, with a focus on molecular aspects of intestinal and hepatic iron-copper interplay and how this relates to various disease states. © 2018 American Physiological Society. Compr Physiol 8:1433-1461, 2018.
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Affiliation(s)
- Caglar Doguer
- Food Science and Human Nutrition Department, University of Florida, Florida, Gainesville, USA.,Nutrition and Dietetics Department, Namık Kemal University, Tekirdag, Turkey
| | - Jung-Heun Ha
- Food Science and Human Nutrition Department, University of Florida, Florida, Gainesville, USA.,Department of Food and Nutrition, Chosun University Note: Caglar Doguer and Jung-Heun Ha have contributed equally to this work., Gwangju, Korea
| | - James F Collins
- Food Science and Human Nutrition Department, University of Florida, Florida, Gainesville, USA
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25
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Collins JF. Ferroxidases and Mammalian Iron Homeostasis: Novel Insight Into a Physiological Phenomenon First Described More Than Half a Century Ago. Cell Mol Gastroenterol Hepatol 2018; 6:470-471. [PMID: 30364771 PMCID: PMC6198015 DOI: 10.1016/j.jcmgh.2018.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
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26
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Wang X, Flores SRL, Ha JH, Doguer C, Woloshun RR, Xiang P, Grosche A, Vidyasagar S, Collins JF. Intestinal DMT1 Is Essential for Optimal Assimilation of Dietary Copper in Male and Female Mice with Iron-Deficiency Anemia. J Nutr 2018; 148:1244-1252. [PMID: 30137476 PMCID: PMC6074787 DOI: 10.1093/jn/nxy111] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 05/02/2018] [Indexed: 12/14/2022] Open
Abstract
Background Divalent metal-ion transporter 1 (DMT1) may transport copper, but studies to date on this topic have been equivocal. Previously, an ex vivo experiment showed that intestinal copper transport was impaired in Dmt1-mutant Belgrade rats. Objective In this study, we tested the hypothesis that intestinal DMT1 transports copper in vivo. Methods Intestine-specific Dmt1 knockout (Dmt1int/int) mice and normal (control) littermates (Dmt1fl/fl) were used. In study 1, intestinal copper absorption was assessed in 7-wk-old mice of both sexes and genotypes by oral-intragastric gavage of 64Cu under normal and iron-deficiency anemia (IDA) conditions. In study 2, both sexes and genotypes of 8-wk-old mice were fed diets with adequate iron concentrations [72 parts per million (ppm)] plus adequate (9 ppm) or excessive (183 ppm) copper concentrations for 4 wk. Iron- and copper-related physiologic variables were subsequently assessed. Results Study 1 showed that intestinal copper transport was enhanced in normal (∼11% increase in males, 35% in females) and anemic (∼42% increase in males, 35% in females) Dmt1int/int mice. Study 2 showed that, with adequate copper intakes, serum ceruloplasmin (Cp) activity was decreased (by ∼29% in males and 20% in females) and spleens were enlarged (by 3-fold in both sexes) in Dmt1int/int mice. Higher dietary copper increased hepatic copper concentrations (by ∼3.3-fold in males and 1.5-fold in females), restored serum Cp activity, and mitigated the noted splenomegaly in Dmt1int/int mice. Conclusions Copper homeostasis was disrupted in Dmt1int/int mice, particularly during IDA, despite the noted increases in intestinal copper transport. This was exemplified by the fact that extra dietary copper was required to restore serum Cp activity (a biomarker of copper status) and reduce the severity of the noted splenomegaly (which could reflect changes in erythropoietic demand) in Dmt1int/int mice. Collectively, these observations show that intestinal DMT1 is essential for the assimilation of sufficient quantities of dietary copper to maintain systemic copper homeostasis during IDA.
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Affiliation(s)
- Xiaoyu Wang
- Departments of Food Science and Human Nutrition, University of Florida, Gainesville, FL
| | - Shireen RL Flores
- Departments of Food Science and Human Nutrition, University of Florida, Gainesville, FL
| | - Jung-Heun Ha
- Departments of Food Science and Human Nutrition, University of Florida, Gainesville, FL
| | - Caglar Doguer
- Departments of Food Science and Human Nutrition, University of Florida, Gainesville, FL
| | - Regina R Woloshun
- Departments of Food Science and Human Nutrition, University of Florida, Gainesville, FL
| | - Ping Xiang
- Departments of Food Science and Human Nutrition, University of Florida, Gainesville, FL,State Key Lab of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China
| | - Astrid Grosche
- Departments of Radiation Oncology, University of Florida, Gainesville, FL
| | | | - James F Collins
- Departments of Food Science and Human Nutrition, University of Florida, Gainesville, FL,Address correspondence to JFC (e-mail: )
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27
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Wang T, Xiang P, Ha JH, Wang X, Doguer C, Flores SRL, Kang YJ, Collins JF. Copper supplementation reverses dietary iron overload-induced pathologies in mice. J Nutr Biochem 2018; 59:56-63. [PMID: 29960117 DOI: 10.1016/j.jnutbio.2018.05.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 04/16/2018] [Accepted: 05/10/2018] [Indexed: 02/05/2023]
Abstract
Dietary iron overload in rodents impairs growth and causes cardiac hypertrophy, serum and tissue copper depletion, depression of serum ceruloplasmin (Cp) activity and anemia. Notably, increasing dietary copper content to ~25-fold above requirements prevents the development of these physiological perturbations. Whether copper supplementation can reverse these high-iron-related abnormalities has, however, not been established. The current investigation was thus undertaken to test the hypothesis that supplemental copper will mitigate negative outcomes associated with dietary iron loading. Weanling mice were thus fed AIN-93G-based diets with high (>100-fold in excess) or adequate (~80 ppm) iron content. To establish the optimal experimental conditions, we first defined the time course of iron loading, and assessed the impact of supplemental copper (provided in drinking water) on the development of high-iron-related pathologies. Copper supplementation (20 mg/L) for the last 3 weeks of a 7-week high-iron feeding period reversed the anemia, normalized serum copper levels and Cp activity, and restored tissue copper concentrations. Growth rates, cardiac copper concentrations and heart size, however, were only partially normalized by copper supplementation. Furthermore, high dietary iron intake reduced intestinal 64Cu absorption (~60%) from a transport solution provided to mice by oral, intragastric gavage. Copper supplementation of iron-loaded mice enhanced intestinal 64Cu transport, thus allowing sufficient assimilation of dietary copper to correct many of the noted high-iron-related physiological perturbations. We therefore conclude that high- iron intake increases the requirement for dietary copper (to overcome the inhibition of intestinal copper absorption).
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Affiliation(s)
- Tao Wang
- Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China; Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Ping Xiang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA; School of the Environment, Nanjing University, Nanjing, China
| | - Jung-Heun Ha
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Xiaoyu Wang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Caglar Doguer
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Shireen R L Flores
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - Yujian James Kang
- Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - James F Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA.
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28
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Wang T, Xiang P, Ha J, Doguer C, Wang X, Flores S, Kang YJ, Collins JF. Copper supplementation in drinking water reverses dietary iron overload‐induced anemia and cardiac hypertrophy in mice. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.750.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Tao Wang
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
- Regenerative Medicine Research CenterSichuan UniversityChengduPeople's Republic of China
| | - Ping Xiang
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
- School of the EnvironmentNanjing UniversityNanjingPeople's Republic of China
| | - Jung‐Heun Ha
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - Caglar Doguer
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - Xiaoyu Wang
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - Shireen Flores
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - Y. James Kang
- Regenerative Medicine Research CenterSichuan UniversityChengduPeople's Republic of China
| | - James F. Collins
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
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29
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Ha JH, Doguer C, Flores SRL, Wang T, Collins JF. Progressive Increases in Dietary Iron Are Associated with the Emergence of Pathologic Disturbances of Copper Homeostasis in Growing Rats. J Nutr 2018; 148:373-378. [PMID: 29546308 PMCID: PMC6669950 DOI: 10.1093/jn/nxx070] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 12/18/2017] [Indexed: 12/27/2022] Open
Abstract
Background Consumption of a high-iron diet causes copper deficiency in weanling rodents; however, the minimum amount of dietary iron that disrupts copper homeostasis has not been established. Objective We tested the hypothesis that dietary iron at only several-fold above physiologic requirements would cause copper depletion. Methods Weanling male Sprague-Dawley rats (n = 6/group) were fed AIN-93G-based diets with adequate (88 µg Fe/g = 1×), or excessive (4×, 9.5×, 18.5×, 38×, or 110×) iron content for 7 wk (110× group, due to notable morbidity) or 8 wk (all other groups). Copper-related physiologic parameters were then assessed. Results A hierarchy of copper-related, pathologic symptoms was noted as dietary iron concentrations increased. All statistical comparisons reported here refer to differences from the 1× (i.e., control) group. The highest iron concentration (110×) impaired growth (final body weights decreased ∼40%; P < 0.0001), and caused anemia (blood hemoglobin and hematocrit decreased ∼65%; P < 0.0001) and hepatic copper depletion (>85% reduction; P < 0.01). Cardiac hypertrophy occurred in the 110× (∼130% increase in mass; P < 0.0001) and 38× (∼25% increase; P < 0.05) groups, whereas cardiac copper content was lower in the 110× (P < 0.01), 38× (P < 0.01), and 18.5× (P < 0.05) groups (∼70% reductions). Splenic copper was also depleted in the 110× (>90% reduction; P < 0.0001), and in the 38× (P < 0.001) and 18.5× (P < 0.01) groups (∼70% reductions). Moreover, serum ceruloplasmin activity was decreased in the 110× and 38× (>90% reductions; P < 0.0001), and 18.5× (P < 0.001) and 9.5× (P < 0.05) (∼50% reductions) groups, typifying moderate to severe copper deficiency. Conclusions Increasing dietary iron intakes to ∼9.5-fold above dietary recommendations caused copper deficiency. Importantly, human iron supplementation is common, and recommended intakes for at-risk individuals may be ≤10-fold above the RDA. Whether these iron intakes perturb copper metabolism is worth considering, especially since copper defi-ciency can impair iron utilization (e.g., by decreasing the ferroxidase activity of ceruloplasmin).
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Affiliation(s)
- Jung-Heun Ha
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL
| | - Caglar Doguer
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL
| | - Shireen RL Flores
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL
| | - Tao Wang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL,Regenerative Medicine Research Center, Sichuan University, Chengdu, China
| | - James F Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL,Address correspondence to JFC (e-mail: )
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Ha JH, Doguer C, Collins JF. Knockdown of copper-transporting ATPase 1 (Atp7a) impairs iron flux in fully-differentiated rat (IEC-6) and human (Caco-2) intestinal epithelial cells. Metallomics 2017; 8:963-972. [PMID: 27714044 DOI: 10.1039/c6mt00126b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Intestinal iron absorption is highly regulated since no mechanism for iron excretion exists. We previously demonstrated that expression of an intestinal copper transporter (Atp7a) increases in parallel with genes encoding iron transporters in the rat duodenal epithelium during iron deprivation (Am. J. Physiol.: Gastrointest. Liver Physiol., 2005, 288, G964-G971). This led us to postulate that Atp7a may influence intestinal iron flux. Therefore, to test the hypothesis that Atp7a is required for optimal iron transport, we silenced Atp7a in rat IEC-6 and human Caco-2 cells. Iron transport was subsequently quantified in fully-differentiated cells plated on collagen-coated, transwell inserts. Interestingly, 59Fe uptake and efflux were impaired in both cell lines by Atp7a silencing. Concurrent changes in the expression of key iron transport-related genes were also noted in IEC-6 cells. Expression of Dmt1 (the iron importer), Dcytb (an apical membrane ferrireductase) and Fpn1 (the iron exporter) was decreased in Atp7a knockdown (KD) cells. Paradoxically, cell-surface ferrireductase activity increased (>5-fold) in Atp7a KD cells despite decreased Dcytb mRNA expression. Moreover, increased expression (>10-fold) of hephaestin (an iron oxidase involved in iron efflux) was associated with increased ferroxidase activity in KD cells. Increases in ferrireductase and ferroxidase activity may be compensatory responses to increase iron flux. In summary, in these reductionist models of the mammalian intestinal epithelium, Atp7a KD altered expression of iron transporters and impaired iron flux. Since Atp7a is a copper transporter, it is a logical supposition that perturbations in intracellular copper homeostasis underlie the noted biologic changes in these cell lines.
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Affiliation(s)
- Jung-Heun Ha
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, USA
| | - Caglar Doguer
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, USA
| | - James F Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, USA and Food Science & Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA.
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Ha JH, Doguer C, Collins JF. Consumption of a High-Iron Diet Disrupts Homeostatic Regulation of Intestinal Copper Absorption in Adolescent Mice. Am J Physiol Gastrointest Liver Physiol 2017; 313:G535-G360. [PMID: 28619730 PMCID: PMC5668571 DOI: 10.1152/ajpgi.00169.2017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 06/12/2017] [Accepted: 06/12/2017] [Indexed: 01/31/2023]
Abstract
High-iron feeding of rodents has been commonly used to model human iron-overload disorders. We recently noted that high-iron consumption impaired growth and caused severe systemic copper deficiency in growing rats, but the mechanism by which this occurred could not be determined due to technical limitations. In the current investigation, we thus utilized mice; first to determine if the same phenomenon occurred in another mammalian species, and secondly since we could assess in vivo copper absorption in mice. We hypothesized that excessive dietary iron impaired intestinal copper absorption. Weanling, male mice were thus fed AIN-93G-based diets containing high (HFe) (~8800 ppm) or adequate (AdFe) (~80 ppm) iron in combination with low (~0.9 ppm), adequate (~9 ppm) or high (~180 ppm) copper for several weeks. Iron and copper homeostasis was subsequently assessed. Mice consuming the HFe diets grew slower, were anemic, and had lower hepatic copper levels and serum ceruloplasmin activity. These physiologic perturbations were all prevented by higher dietary copper, demonstrating that copper depletion was the underlying cause. Furthermore, homeostatic regulation of copper absorption was noted in the mice consuming the AdFe diets, with absorption increasing as dietary copper decreased. HFe-fed mice did not have impaired copper absorption (disproving our hypothesis), but homeostatic control of absorption was disrupted. There were also noted perturbations in the tissue distribution of copper in the HFe-fed mice, suggesting that altered storage and thus bioavailability contributed to the noted copper deficiency. Dietary iron loading thus antagonizes copper homeostasis leading to pathological symptoms of severe copper depletion.
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Affiliation(s)
- Jung-Heun Ha
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida
| | - Caglar Doguer
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida
| | - James F. Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida
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Zhang M, Wang X, Han MK, Collins JF, Merlin D. Oral administration of ginger-derived nanolipids loaded with siRNA as a novel approach for efficient siRNA drug delivery to treat ulcerative colitis. Nanomedicine (Lond) 2017; 12:1927-1943. [PMID: 28665164 PMCID: PMC5827822 DOI: 10.2217/nnm-2017-0196] [Citation(s) in RCA: 143] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 06/21/2017] [Indexed: 12/12/2022] Open
Abstract
AIM To develop novel siRNA delivery system overcoming the limitations of synthetic nanoparticles, such as potential side effects, nonspecificity and economic production for ulcerative colitis therapy. MATERIALS & METHODS Nanoparticles composed of edible ginger-derived lipid, termed ginger-derived lipid vehicles (GDLVs) were generated from ginger lipids through hydration of a lipid film, a commonly used method for a liposome fabrication. The morphology, biocompatibility and transfection efficiency of GDLVs loaded with siRNA-CD98 (siRNA-CD98/GDLVs) were characterized by standard methods. RESULTS Orally administered siRNA-CD98/GDLVs were effectively targeted specifically to colon tissues, resulting in reduced expression of CD98. CONCLUSION These GDLVs have great promise as efficient siRNA-delivery vehicles while potentially obviating issues related to the traditional synthetic nanoparticles. As such, they help shift the current paradigm of siRNA delivery away from artificially synthesized nanoparticles toward the use of naturally derived nanovehicles from edible plants.
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Affiliation(s)
- Mingzhen Zhang
- Institute for Biomedical Sciences, Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30302, USA
| | - Xiaoyu Wang
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA
| | - Moon Kwon Han
- Institute for Biomedical Sciences, Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30302, USA
| | - James F Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA
| | - Didier Merlin
- Institute for Biomedical Sciences, Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30302, USA
- Alanta Veterans Affairs Medical Center, Decatur, GA 30033, USA
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Zhang M, Collins JF, Merlin D. Do ginger-derived nanoparticles represent an attractive treatment strategy for inflammatory bowel diseases? Nanomedicine (Lond) 2016; 11:3035-3037. [PMID: 27813445 PMCID: PMC5561796 DOI: 10.2217/nnm-2016-0353] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 10/11/2016] [Indexed: 11/21/2022] Open
Affiliation(s)
- Mingzhen Zhang
- Institute for Biomedical Sciences, Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA, 30302 USA
| | - James F Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL, 32611 USA
| | - Didier Merlin
- Institute for Biomedical Sciences, Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA, 30302 USA
- Atlanta Veterans Affairs Medical Center, Decatur, GA, 30033 USA
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Ha JH, Doguer C, Wang X, Flores SR, Collins JF. High-Iron Consumption Impairs Growth and Causes Copper-Deficiency Anemia in Weanling Sprague-Dawley Rats. PLoS One 2016; 11:e0161033. [PMID: 27537180 PMCID: PMC4990348 DOI: 10.1371/journal.pone.0161033] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 07/28/2016] [Indexed: 02/06/2023] Open
Abstract
Iron-copper interactions were described decades ago; however, molecular mechanisms linking the two essential minerals remain largely undefined. Investigations in humans and other mammals noted that copper levels increase in the intestinal mucosa, liver and blood during iron deficiency, tissues all important for iron homeostasis. The current study was undertaken to test the hypothesis that dietary copper influences iron homeostasis during iron deficiency and iron overload. We thus fed weanling, male Sprague-Dawley rats (n = 6-11/group) AIN-93G-based diets containing high (~8800 ppm), adequate (~80) or low (~11) iron in combination with high (~183), adequate (~8) or low (~0.9) copper for 5 weeks. Subsequently, the iron- and copper-related phenotype of the rats was assessed. Rats fed the low-iron diets grew slower than controls, with changes in dietary copper not further influencing growth. Unexpectedly, however, high-iron (HFe) feeding also impaired growth. Furthermore, consumption of the HFe diet caused cardiac hypertrophy, anemia, low serum and tissue copper levels and decreased circulating ceruloplasmin activity. Intriguingly, these physiologic perturbations were prevented by adding extra copper to the HFe diet. Furthermore, higher copper levels in the HFe diet increased serum nonheme iron concentration and transferrin saturation, exacerbated hepatic nonheme iron loading and attenuated splenic nonheme iron accumulation. Moreover, serum erythropoietin levels, and splenic erythroferrone and hepatic hepcidin mRNA levels were altered by the dietary treatments in unanticipated ways, providing insight into how iron and copper influence expression of these hormones. We conclude that high-iron feeding of weanling rats causes systemic copper deficiency, and further, that copper influences the iron-overload phenotype.
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Affiliation(s)
- Jung-Heun Ha
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, United States of America
| | - Caglar Doguer
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, United States of America
| | - Xiaoyu Wang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, United States of America
| | - Shireen R. Flores
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, United States of America
| | - James F. Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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Prasad AS, Brewer G, Collins JF. The history of the International Society for Trace Element Research in Humans (ISTERH) and summary of the 10th ISTERH meeting in Tokyo, Japan (November 2013). J Trace Elem Med Biol 2014; 28:355-6. [PMID: 25305094 DOI: 10.1016/j.jtemb.2014.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Ananda S Prasad
- Department of Oncology, Wayne State University, School of Medicine, Karmanos Cancer Institute, Detroit, MI, United States.
| | - George Brewer
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, United States
| | - James F Collins
- Department of Food Science & Human Nutrition, University of Florida, Gainesville, FL, United States
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Gulec S, Collins JF. Silencing of the Menkes copper-transporting ATPase (Atp7a) gene increases cyclin D1 protein expression and impairs proliferation of rat intestinal epithelial (IEC-6) cells. J Trace Elem Med Biol 2014; 28:459-64. [PMID: 25156967 PMCID: PMC4344117 DOI: 10.1016/j.jtemb.2014.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Indexed: 11/20/2022]
Abstract
The Menkes copper-transporting ATPase (Atp7a) has dual roles in mammalian enterocytes: pumping copper into the trans-Golgi network (to support cuproenzyme synthesis) and across the basolateral membrane (to deliver dietary copper to the blood). Atp7a is strongly induced in the rodent duodenum during iron deprivation, suggesting that copper influences iron homeostasis. To investigate this possibility, Atp7a was silenced in rat intestinal epithelial (IEC-6) cells. Irrespective of its influence on iron homeostasis, an unexpected observation was made in the Atp7a knockdown (KD) cells: the cells grew slower (∼40% fewer cells at 96h) and were larger than negative-control shRNA-transfected cells. Lack of Atp7a activity thus perturbed cell cycle control. To elucidate a possible molecular mechanism, expression of two important cell cycle control proteins was assessed. Cyclin D1 (CD1) protein expression increased in Atp7a KD cells whereas proliferating-cell nuclear antigen (PCNA) expression was unaltered. Increased CD1 expression is consistent with impaired cell cycle progression. Expression of additional cell proliferation marker genes (p21 and Ki67) was also investigated; p21 expression increased, whereas Ki67 decreased, both consistent with diminished cell growth. Further experiments were designed to determine whether increased cellular copper content was the trigger for the altered growth phenotype of the Atp7a KD cells. Copper loading, however, did not influence the expression patterns of CD1, p21 or Ki67. Overall, these findings demonstrate that Atp7a is required for normal proliferation of IEC-6 cells. How Atp7a influences cell growth is unclear, but the underlying mechanism could relate to its roles in intracellular copper distribution or cuproenzyme synthesis.
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Affiliation(s)
- Sukru Gulec
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA
| | - James F Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL, USA.
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Abstract
Iron is an essential trace mineral that plays a number of important physiological roles in humans, including oxygen transport, energy metabolism, and neurotransmitter synthesis. Iron absorption by the proximal small bowel is a critical checkpoint in the maintenance of whole-body iron levels since, unlike most other essential nutrients, no regulated excretory systems exist for iron in humans. Maintaining proper iron levels is critical to avoid the adverse physiological consequences of either low or high tissue iron concentrations, as commonly occurs in iron-deficiency anemia and hereditary hemochromatosis, respectively. Exquisite regulatory mechanisms have thus evolved to modulate how much iron is acquired from the diet. Systemic sensing of iron levels is accomplished by a network of molecules that regulate transcription of the HAMP gene in hepatocytes, thus modulating levels of the serum-borne, iron-regulatory hormone hepcidin. Hepcidin decreases intestinal iron absorption by binding to the iron exporter ferroportin 1 on the basolateral surface of duodenal enterocytes, causing its internalization and degradation. Mucosal regulation of iron transport also occurs during low-iron states, via transcriptional (by hypoxia-inducible factor 2α) and posttranscriptional (by the iron-sensing iron-regulatory protein/iron-responsive element system) mechanisms. Recent studies demonstrated that these regulatory loops function in tandem to control expression or activity of key modulators of iron homeostasis. In health, body iron levels are maintained at appropriate levels; however, in several inherited disorders and in other pathophysiological states, iron sensing is perturbed and intestinal iron absorption is dysregulated. The iron-related phenotypes of these diseases exemplify the necessity of precisely regulating iron absorption to meet body demands.
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Affiliation(s)
- Sukru Gulec
- 1Food Science & Human Nutrition Department, University of Florida, Gainesville, Florida; and
| | | | - James F. Collins
- 1Food Science & Human Nutrition Department, University of Florida, Gainesville, Florida; and
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Abstract
Given their similar physiochemical properties, it is a logical postulate that iron and copper metabolism are intertwined. Indeed, iron-copper interactions were first documented over a century ago, but the homeostatic effects of one on the other has not been elucidated at a molecular level to date. Recent experimental work has, however, begun to provide mechanistic insight into how copper influences iron metabolism. During iron deficiency, elevated copper levels are observed in the intestinal mucosa, liver, and blood. Copper accumulation and/or redistribution within enterocytes may influence iron transport, and high hepatic copper may enhance biosynthesis of a circulating ferroxidase, which potentiates iron release from stores. Moreover, emerging evidence has documented direct effects of copper on the expression and activity of the iron-regulatory hormone hepcidin. This review summarizes current experimental work in this field, with a focus on molecular aspects of iron-copper interplay and how these interactions relate to various disease states.
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Affiliation(s)
- Sukru Gulec
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida 32611;
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Gulec S, Collins JF. Silencing the Menkes copper-transporting ATPase (Atp7a) gene in rat intestinal epithelial (IEC-6) cells increases iron flux via transcriptional induction of ferroportin 1 (Fpn1). J Nutr 2014; 144:12-9. [PMID: 24174620 PMCID: PMC3861793 DOI: 10.3945/jn.113.183160] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The Menkes copper-transporting ATPase (Atp7a) gene is induced in rat duodenum during iron deficiency, consistent with copper accumulation in the intestinal mucosa and liver. To test the hypothesis that ATP7A influences intestinal iron metabolism, the Atp7a gene was silenced in rat intestinal epithelial (IEC-6) cells using short hairpin RNA (shRNA) technology. Perturbations in intracellular copper homeostasis were noted in knockdown cells, consistent with the dual roles of ATP7A in pumping copper into the trans-Golgi (for cuproenzyme synthesis) and exporting copper from cells. Intracellular iron concentrations were unaffected by Atp7a knockdown. Unexpectedly, however, vectorial iron ((59)Fe) transport increased (∼33%) in knockdown cells grown in bicameral inserts and increased further (∼70%) by iron deprivation (compared with negative control shRNA-transfected cells). Additional experiments were designed to elucidate the molecular mechanism of increased transepithelial iron flux. Enhanced iron uptake by knockdown cells was associated with increased expression of a ferrireductase (duodenal cytochrome b) and activity of a cell-surface ferrireductase. Increased iron efflux from knockdown cells was likely mediated via transcriptional activation of the ferroportin 1 gene (by an unknown mechanism). Moreover, Atp7a knockdown significantly attenuated expression of an iron oxidase [hephaestin (HEPH); by ∼80%] and membrane ferroxidase activity (by ∼50%). Cytosolic ferroxidase activity, however, was retained in knockdown cells (75% of control cells), perhaps compensating for diminished HEPH activity. This investigation has thus documented alterations in iron homeostasis associated with Atp7a knockdown in enterocyte-like cells. Alterations in copper transport, trafficking, or distribution may underlie the increase in transepithelial iron flux noted when ATP7A activity is diminished.
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Jiang L, Garrick MD, Garrick LM, Zhao L, Collins JF. Divalent metal transporter 1 (Dmt1) mediates copper transport in the duodenum of iron-deficient rats and when overexpressed in iron-deprived HEK-293 cells. J Nutr 2013; 143:1927-33. [PMID: 24089420 PMCID: PMC3827639 DOI: 10.3945/jn.113.181867] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Intracellular copper-binding proteins (metallothionein I/II) and a copper exporter (Menkes copper-transporting ATPase) are upregulated in duodenal enterocytes from iron-deficient rats, consistent with copper accumulation in the intestinal mucosa. How copper enters enterocytes during iron deficiency is, however, not clear. Divalent metal transporter 1 (Dmt1), the predominant iron importer in the mammalian duodenum, also transports other metal ions, possibly including copper. Given this possibility and that Dmt1 expression is upregulated by iron deprivation, we sought to test the hypothesis that Dmt1 transports copper during iron deficiency. Two model systems were utilized: the Belgrade (b) rat, expressing mutant Dmt1, and an inducible Dmt1-overexpression cell culture system. Mutant rats (b/b) were fed a semipurified, AIN93G-based control diet and phenotypically normal littermates (+/b) were fed control or iron-deficient diets for ~14 wk. An everted gut sleeve technique and a colorimetric copper quantification assay were utilized to assess duodenal copper transport. The control diet-fed +/b rats had normal hematological parameters, whereas iron-deprived +/b and b/b rats were iron deficient and Dmt1 mRNA and protein levels increased. Importantly, duodenal copper transport was similar in the control +/b and b/b rats; however, it significantly increased (~4-fold) in the iron-deprived +/b rats. Additional experiments in Dmt1 overexpressing HEK-293 cells showed that copper ((64)Cu) uptake was stimulated (∼3-fold) in the presence of an iron chelator. Dmt1 transcript stabilization due to a 3' iron-responsive element was also documented, likely contributing to increased transport activity. In summary, these studies suggest that Dmt1 enhances copper uptake into duodenal enterocytes during iron deprivation.
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Affiliation(s)
- Lingli Jiang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL; and
| | | | | | - Lin Zhao
- Department of Biochemistry, University at Buffalo, Buffalo, NY
| | - James F. Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL; and,To whom correspondence should be addressed. E-mail:
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Xie L, Collins JF. Transcription factors Sp1 and Hif2α mediate induction of the copper-transporting ATPase (Atp7a) gene in intestinal epithelial cells during hypoxia. J Biol Chem 2013; 288:23943-52. [PMID: 23814049 DOI: 10.1074/jbc.m113.489500] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Genes with G/C-rich promoters were up-regulated in the duodenal epithelium of iron-deficient rats including those encoding iron (e.g. Dmt1 and Dcytb) and copper (e.g. Atp7a and Mt1) metabolism-related proteins. It was shown previously that an intestinal copper transporter (Atp7a) was co-regulated with iron transport-related genes by a hypoxia-inducible transcription factor, Hif2α. In the current study, we sought to test the role of Sp1 in transcriptional regulation of Atp7a expression during iron deprivation/hypoxia. Initial studies in IEC-6 cells showed that mithramycin, an Sp1 inhibitor, reduced expression of Atp7a and iron transport-related genes (Dmt1, Dcytb, and Fpn1) and blocked their induction by CoCl2, a hypoxia mimetic. Consistent with this, overexpression of Sp1 increased endogenous Atp7a mRNA and protein expression and stimulated Atp7a, Dmt1, and Dcytb promoter activity. Site-directed mutagenesis and functional analysis of a basal Atp7a promoter construct revealed four functional Sp1 binding sites that were necessary for Hif2α-mediated induction of promoter activity. Furthermore, chromatin immunoprecipitation (ChIP) assays confirmed that Sp1 specifically interacts with the Atp7a promoter in IEC-6 cells and in rat duodenal enterocytes. This investigation has thus revealed a novel aspect of Atp7a gene regulation in which Sp1 may be necessary for the HIF-mediated induction of gene transcription during iron deficiency/hypoxia. Understanding regulation of Atp7a expression may help further clarify the physiological role of copper in the maintenance of iron homeostasis. Furthermore, this Sp1/Hif2α regulatory mechanism may have broader implications for understanding the genetic response of the intestinal epithelium to maintain whole-body iron homeostasis during states of deficiency.
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Affiliation(s)
- Liwei Xie
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida 32611, USA
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Gulec S, Collins JF. Investigation of iron metabolism in mice expressing a mutant Menke's copper transporting ATPase (Atp7a) protein with diminished activity (Brindled; Mo (Br) (/y) ). PLoS One 2013; 8:e66010. [PMID: 23776592 PMCID: PMC3679098 DOI: 10.1371/journal.pone.0066010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 04/29/2013] [Indexed: 12/13/2022] Open
Abstract
During iron deficiency, perturbations in copper homeostasis have frequently been documented. Previous studies in iron-deprived rats demonstrated that enterocyte and hepatic copper levels increase and a copper transporter (the Menkes Copper ATPase; Atp7a) is induced in the duodenal epithelium in parallel to iron transport-related genes (e.g. Dmt1, Dcytb, Fpn1). Moreover, two ferroxidase proteins involved in iron homeostasis, hephaestin expressed in enterocytes and ceruloplasmin, produced and secreted into blood by the liver, are copper-dependent enzymes. We thus aimed to test the hypothesis that Atp7a function is important for the copper-related compensatory response of the intestinal epithelium to iron deficiency. Accordingly, iron homeostasis was studied for the first time in mice expressing a mutant Atp7a protein with minimal activity (Brindled [MoBr/y]). Mutant mice were rescued by perinatal copper injections, and, after a 7–8 week recovery period, were deprived of dietary iron for 3 weeks (along with WT littermates). Adult MoBr/y mice displayed copper-deficiency anemia but had normal iron status; in contrast, iron-deprived MoBr/y mice were iron deficient and more severely anemic with partial amelioration of the copper-deficient phenotype. Intestinal iron absorption in both genotypes (WT and MoBr/y) increased ∼3-fold when mice consumed a low-iron diet and ∼6-fold when mice were concurrently bled. WT mice exhibited no alterations in copper homeostasis in response to iron deprivation or phlebotomy. Conversely, upregulation of iron absorption was associated with increased enterocyte and liver copper levels and serum ferroxidase (ceruloplasmin) activity in MoBr/y mice, typifying the response to iron deprivation in many mammalian species. We thus speculate that a copper threshold exists that is necessary to allow appropriate regulate of iron absorption. In summary, MoBr/y mice were able to adequately regulate iron absorption, but unlike in WT mice, concurrent increases in enterocyte and liver copper levels and serum ferroxidase activity may have contributed to maintenance of iron homeostasis.
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Affiliation(s)
- Sukru Gulec
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, United States of America
| | - James F. Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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Gulec S, Collins JF. Iron Metabolism in a Rodent Model of Menkes Disease (Brindled Mice). FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.634.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Xie L, Collins JF. Specificity Factor 1 (Sp1) Mediates Transcriptional Induction of Atp7a During Hypoxia in Rat Intestinal Epithelial (IEC‐6) Cells. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.222.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Liwei Xie
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - James F. Collins
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
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Gulec S, Doguer C, Collins JF. Knock‐Downof Atp7a Expression Reduces Hephaestin Expression and Activity in A Rat Intestinal Epithelial Cell Line (IEC‐6). FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.lb293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Gulec S, Collins JF. Silencing of the Menkes Copper‐Transporting ATPase (Atp7a) in Intestinal Epithelial Cells Impairs Cell Growth and Cell Cycle Control. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.223.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Xie L, Collins JF. Copper stabilizes the Menkes copper-transporting ATPase (Atp7a) protein expressed in rat intestinal epithelial cells. Am J Physiol Cell Physiol 2012; 304:C257-62. [PMID: 23174565 DOI: 10.1152/ajpcell.00336.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Iron deficiency decreases oxygen tension in the intestinal mucosa, leading to stabilization of hypoxia-inducible transcription factor 2α (Hif2α) and subsequent upregulation of genes involved in iron transport [e.g., divalent metal transporter (Dmt1) and ferroportin 1 (Fpn1)]. Iron deprivation also alters copper homeostasis, reflected by copper accumulation in the intestinal epithelium and induction of an intracellular copper-binding protein [metallothionein (Mt)] and a copper exporter [Menkes copper ATPase (Atp7a)]. Importantly, Atp7a is also a Hif2α target. It was, however, previously noted that Atp7a protein expression was induced more strongly than mRNA in the duodenum of iron-deprived rats, suggesting additional regulatory mechanisms. The current study was thus designed to decipher mechanistic aspects of Atp7a regulation during iron deprivation using an established in vitro model of the mammalian intestine, rat intestinal epithelial (IEC-6) cells. Cells were treated with an iron chelator and/or copper loaded to mimic the in vivo situation. IEC-6 cells exposed to copper showed a dose-dependent increase in Mt expression, confirming intracellular copper accumulation. Iron chelation with copper loading increased Atp7a mRNA and protein levels; however, contrary to our expectation, copper alone increased only protein levels. This suggested that copper increased Atp7a protein levels by a posttranscriptional regulatory mechanism. Therefore, to determine if Atp7a protein stability was affected, the translation inhibitor cycloheximide was utilized. Experiments in IEC-6 cells revealed that the half-life of the Atp7a protein was ~41 h and, furthermore, that intracellular copper accumulation increased steady-state Atp7a protein levels. This investigation thus reveals a novel mechanism of Atp7a regulation in which copper stabilizes the protein, possibly complementing Hif2α-mediated transcriptional induction during iron deficiency.
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Affiliation(s)
- Liwei Xie
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA
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Lu Y, Kim C, Collins JF. Multiple Menkes copper ATPase (Atp7a) transcript and protein variants are induced by iron deficiency in rat duodenal enterocytes. J Trace Elem Med Biol 2012; 26:109-14. [PMID: 22579041 PMCID: PMC3663448 DOI: 10.1016/j.jtemb.2012.04.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 03/28/2012] [Indexed: 11/21/2022]
Abstract
The Menkes copper ATPase (Atp7a) pumps copper into the trans-Golgi for cuproenzyme synthesis, and translocates to the basolateral membrane of enterocytes for copper export. Recent studies demonstrated that three 5' end splice variants of the Atp7a transcript exist in rat duodenum, all of which are strongly induced during iron deprivation. To explore a possible role for Atp7a (and copper) in intestinal iron absorption, the current studies were undertaken to test the hypothesis that multiple Atp7a transcript and protein variants exist in intestinal epithelial cells. Northern blot analyses using probes generated from the full-length Atp7a cDNA revealed several specific hybridization bands, all of which were more intense in RNA samples extracted from duodenal enterocytes isolated from iron-deficient rats. A PCR-based approach, using forward primers specific for the alternative 5' end splice variants and a reverse primer in exon 23, demonstrated that 3 full-length transcripts exist in rat IEC-6 cells. To identify possible Atp7a protein variants, three distinct polyclonal antisera were utilized. The specificity of the antisera was first established by western blotting and immunoprecipitation studies using samples derived from isolated rat enterocytes and Atp7a knockdown IEC-6 cells. Several specific immunoreactive bands were documented, and a unique Atp7a protein distribution in cytosolic vesicle-like structures was noted. In conclusion, multiple Atp7a transcript and protein variants exist in rodent intestinal epithelial cells and are induced by dietary iron deprivation. Further studies will be designed to determine the subcellular distribution of Atp7a protein variants and possible unique functions of each.
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Affiliation(s)
- Yan Lu
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL. USA
| | - Changae Kim
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL. USA
| | - James F. Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, FL. USA
- Corresponding author: J. F. Collins; FSHN Dept., University of Florida, FSHN Bldg., #441, Newell Dr., PO Box 110370, Gainesville, FL, 32611, USA.
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Xie L, Collins JF. Posttranslational Regulation of the Menkes Copper ATPase (Atp7a) in Intestinal Epithelial Cells. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.641.30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Liwei Xie
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - James F. Collins
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
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Jiang L, Collins JF. Copper Transport by Divalent Metal Transporter 1 (Dmt1) Under Low Iron Conditions. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.641.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Lingli Jiang
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
| | - James F. Collins
- Food Science and Human NutritionUniversity of FloridaGainesvilleFL
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