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Evcan E, Gulec S. Comparison of apical and basolateral Cu treatment for iron-related gene regulation during deferoxamine induced iron deficiency. GENES & NUTRITION 2022; 17:16. [PMID: 36494833 PMCID: PMC9733202 DOI: 10.1186/s12263-022-00717-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 11/10/2022] [Indexed: 12/13/2022]
Abstract
BACKGROUND Intestinal copper transporter (Atp7a) mutant-brindled mice with systemic Cu deficiency had elevated Cu levels in enterocyte cells without any perturbation of iron-regulating genes, suggesting that blood Cu level might be important for intestinal iron homeostasis during iron deficiency (ID). We hypothesized that the blood Cu level and polarization (apical and basolateral) of enterocyte cells might be important regulators for the compensatory response on the regulation of genes in enterocyte cells during iron deficiency. METHODS We grew Caco-2 cells on a bicameral cell culture plate to mimic the human intestine system and on a regular tissue culture plate. Iron deficiency was induced by deferoxamine (DFO). The cells were treated with Cu and Cu with Fe following mRNA expressions of DMT1, FPN, TFR, and ANKRD37 were analyzed. RESULTS Our main finding was that basolateral treatment of Cu significantly reduced mRNA expressions of iron-regulated genes, including DMT1, FPN, TFR, and ANKRD37, compared to DFO-treated and DFO with apical Cu-treated groups in both bicameral and regular tissue culture plates. CONCLUSIONS Cu level in the basolateral side of Caco-2 cells significantly influenced the intracellular gene regulation in DFO-induced iron-deficient condition, and polarization of the cells might be important factor gene regulation in enterocyte cells.
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Affiliation(s)
- Ezgi Evcan
- grid.419609.30000 0000 9261 240Xİzmir Institute of Technology, Faculty of Engineering, Department of Food Engineering, Molecular Nutrition and Human Physiology Laboratory, Urla, 35430 İzmir, Turkey
| | - Sukru Gulec
- grid.419609.30000 0000 9261 240Xİzmir Institute of Technology, Faculty of Engineering, Department of Food Engineering, Molecular Nutrition and Human Physiology Laboratory, Urla, 35430 İzmir, Turkey
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2
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Comparison of bioavailability and transporters gene expression of four iron fortificants added to infant cereals. FOOD BIOSCI 2022. [DOI: 10.1016/j.fbio.2022.102023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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LI XCQ, YANG T, WANG J, HUANG CZ. CdTe Quantum Dots-Electrospun Nanofibers Assembly for Visual and Portable Detection of Cu2+. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2021. [DOI: 10.1016/s1872-2040(20)60079-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Simmen S, Cosin-Roger J, Melhem H, Maliachovas N, Maane M, Baebler K, Weder B, Maeyashiki C, Spanaus K, Scharl M, de Vallière C, Zeitz J, Vavricka SR, Hausmann M, Rogler G, Ruiz PA. Iron Prevents Hypoxia-Associated Inflammation Through the Regulation of Nuclear Factor-κB in the Intestinal Epithelium. Cell Mol Gastroenterol Hepatol 2018; 7:339-355. [PMID: 30704983 PMCID: PMC6357696 DOI: 10.1016/j.jcmgh.2018.10.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 09/24/2018] [Accepted: 10/01/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS Hypoxia-associated pathways influence the development of inflammatory bowel disease. Adaptive responses to hypoxia are mediated through hypoxia-inducible factors, which are regulated by iron-dependent hydroxylases. Signals reflecting oxygen tension and iron levels in enterocytes regulate iron metabolism. Conversely, iron availability modulates responses to hypoxia. In the present study we sought to elucidate how iron influences the responses to hypoxia in the intestinal epithelium. METHODS Human subjects were exposed to hypoxia, and colonic biopsy specimens and serum samples were collected. HT-29, Caco-2, and T84 cells were subjected to normoxia or hypoxia in the presence of iron or the iron chelator deferoxamine. Changes in inflammatory gene expression and signaling were assessed by quantitative polymerase chain reaction and Western blot. Chromatin immunoprecipitation was performed using antibodies against nuclear factor (NF)-κB and primers for the promoter of tumor necrosis factor (TNF) and interleukin (IL)1β. RESULTS Human subjects presented reduced levels of ferritin in the intestinal epithelium after hypoxia. Hypoxia reduced iron deprivation-associated TNF and IL1β expression in HT-29 cells through the induction of autophagy. Contrarily, hypoxia triggered TNF and IL1β expression, and NF-κB activation in Caco-2 and T84 cells. Iron blocked autophagy in Caco-2 cells, while reducing hypoxia-associated TNF and IL1β expression through the inhibition of NF-κB binding to the promoter of TNF and IL1β. CONCLUSIONS Hypoxia promotes iron mobilization from the intestinal epithelium. Hypoxia-associated autophagy reduces inflammatory processes in HT-29 cells. In Caco-2 cells, iron uptake is essential to counteract hypoxia-induced inflammation. Iron mobilization into enterocytes may be a vital protective mechanism in the hypoxic inflamed mucosa.
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Affiliation(s)
- Simona Simmen
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Jesus Cosin-Roger
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Hassan Melhem
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Nikolaos Maliachovas
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Max Maane
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Katharina Baebler
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Bruce Weder
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Chiaki Maeyashiki
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Katharina Spanaus
- Institute of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Michael Scharl
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Cheryl de Vallière
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Jonas Zeitz
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland,Center of Gastroenterology, Clinic Hirslanden, Zurich, Switzerland
| | - Stephan R. Vavricka
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Martin Hausmann
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Gerhard Rogler
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Pedro A. Ruiz
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland,Correspondence Address correspondence to: Pedro A. Ruiz-Castro, PhD, Department of Gastroenterology and Hepatology, University of Zurich, Raemistrasse 100, 8091 Zurich, Switzerland.
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Doguer C, Ha JH, Collins JF. Intersection of Iron and Copper Metabolism in the Mammalian Intestine and Liver. Compr Physiol 2018; 8:1433-1461. [PMID: 30215866 DOI: 10.1002/cphy.c170045] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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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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] [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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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] [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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Guo Z, Martucci NJ, Moreno-Olivas F, Tako E, Mahler GJ. Titanium Dioxide Nanoparticle Ingestion Alters Nutrient Absorption in an In Vitro Model of the Small Intestine. NANOIMPACT 2017; 5:70-82. [PMID: 28944308 PMCID: PMC5604471 DOI: 10.1016/j.impact.2017.01.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Ingestion of titanium dioxide (TiO2) nanoparticles from products such as agricultural chemicals, processed food, and nutritional supplements is nearly unavoidable. The gastrointestinal tract serves as a critical interface between the body and the external environment, and is the site of essential nutrient absorption. The goal of this study was to examine the effects of ingesting the 30 nm TiO2 nanoparticles with an in vitro cell culture model of the small intestinal epithelium, and to determine how acute or chronic exposure to nano-TiO2 influences intestinal barrier function, reactive oxygen species generation, proinflammatory signaling, nutrient absorption (iron, zinc, fatty acids), and brush border membrane enzyme function (intestinal alkaline phosphatase). A Caco-2/HT29-MTX cell culture model was exposed to physiologically relevant doses of TiO2 nanoparticles for acute (four hours) or chronic (five days) time periods. Exposure to TiO2 nanoparticles significantly decreased intestinal barrier function following chronic exposure. Reactive oxygen species (ROS) generation, proinflammatory signaling, and intestinal alkaline phosphatase activity all showed increases in response to nano-TiO2. Iron, zinc, and fatty acid transport were significantly decreased following exposure to TiO2 nanoparticles. This is because nanoparticle exposure induced a decrease in absorptive microvilli in the intestinal epithelial cells. Nutrient transporter protein gene expression was also altered, suggesting that cells are working to regulate the transport mechanisms disturbed by nanoparticle ingestion. Overall, these results show that intestinal epithelial cells are affected at a functional level by physiologically relevant exposure to nanoparticles commonly ingested from food.
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Affiliation(s)
- Zhongyuan Guo
- Department of Biomedical Engineering, Binghamton University, Binghamton, NY, 13902
| | - Nicole J. Martucci
- Department of Biomedical Engineering, Binghamton University, Binghamton, NY, 13902
| | | | - Elad Tako
- Plant, Soil and Nutrition Laboratory, Agricultural Research Services, U.S. Department of Agriculture, Ithaca, NY
| | - Gretchen J. Mahler
- Department of Biomedical Engineering, Binghamton University, Binghamton, NY, 13902
- Correspondence to Gretchen Mahler, PhD, Binghamton University, Department of Biomedical Engineering, 2608 Biotechnology Building, Binghamton, NY 13902, Phone: 607-777-5238, Fax: 607-777-5780,
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Chen F, Luo Z, Chen GH, Shi X, Liu X, Song YF, Pan YX. Effects of waterborne Cu exposure on intestinal copper transport and lipid metabolism of Synechogobius hasta. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2016; 178:171-181. [PMID: 27509383 DOI: 10.1016/j.aquatox.2016.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/01/2016] [Accepted: 08/03/2016] [Indexed: 06/06/2023]
Abstract
The present study was conducted to explore the effects of waterborne Cu exposure on intestinal Cu transport and lipid metabolism of Synechogobius hasta. S. hasta were exposed to 0, 0.4721 and 0.9442μM Cu, respectively. Sampling occurred on days 0, 21 and 42, respectively. Growth performance, intestinal lipid deposition, Cu content, and activities and mRNA expression of enzymes and genes involved in Cu transport and lipid metabolism were analyzed. Cu exposure decreased WG and SGR on days 21 and 42. Cu exposure increased intestinal Cu and lipid contents. Increased Cu accumulation was attributable to increased enzymatic activities (Cu-ATPase and Cu, Zn-SOD) and genes' (CTR1, CTR2, DMT1, ATP7a, ATP7b, MT1 and MT2) expression involved in Cu transport. Waterborne Cu exposure also increased activities of lipogenic enzymes (6PGD and ICDH on both days 21 and 42, ME on day 42), up-regulated mRNA levels of lipogenic genes (G6PD, 6PGD, ME, ICDH, FAS and ACCa), lipolytic genes (ACCb, CPT I and HSLa) and genes involved in intestinal fatty acid uptake (IFABP and FATP4) on both days 21 and 42. The up-regulation of lipolysis may result from the increased metabolic expenditure for detoxification and maintenance of the normal body functions in a response to Cu exposure. Meantime, Cu exposure increased lipogenesis and fatty acid uptake, leading to net lipid accumulation in the intestine despite increased lipolysis. To our knowledge, this is the first report involved in intestinal lipid metabolism in combination with intestinal Cu absorption following waterborne Cu exposure, which provides new insights and evidence into Cu toxicity in fish.
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Affiliation(s)
- Feng Chen
- Laboratory of Nutrition and Feed Formulation for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhi Luo
- Laboratory of Nutrition and Feed Formulation for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province, Changde 415000, China; Hubei Provincial Engineering Laboratory for Pond Aquaculture, Wuhan 430070, China.
| | - Guang-Hui Chen
- Laboratory of Nutrition and Feed Formulation for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan 430070, China
| | - Xi Shi
- Laboratory of Nutrition and Feed Formulation for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan 430070, China
| | - Xu Liu
- Postgraduate Research Base, Panjin Guanghe Fishery Co. Ltd., Panjin 124200, China
| | - Yu-Feng Song
- Laboratory of Nutrition and Feed Formulation for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan 430070, China
| | - Ya-Xiong Pan
- Laboratory of Nutrition and Feed Formulation for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan 430070, China
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Chen F, Luo Z, Fan YF, Wu K, Pan YX, Liu X, Zhang LH, Song YF. Five metal elements homeostasis-related genes in Synechogobius hasta: Molecular characterization, tissue expression and transcriptional response to Cu and Fe exposure. CHEMOSPHERE 2016; 159:392-402. [PMID: 27323292 DOI: 10.1016/j.chemosphere.2016.06.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 06/02/2016] [Accepted: 06/06/2016] [Indexed: 06/06/2023]
Abstract
Two isoforms of Cu transporter (CTR1 and CTR2) and metallothionein (MT1 and MT2), and divalent metal ion transporter 1 (DMT1) were cloned and characterized in Synechogobius hasta, respectively. The protein sequences of S. hasta CTRs possessed two methionine-rich regions (MxM and MxxxM) and three transmembrane regions. At the C-terminus, CTR1 contained a sequence of conserved cysteine and histidine residues (HCH), while CTR2 did not contain the conserved sequence. The protein sequence of S. hasta DMT1 possessed all the characteristic features of DMT1, including twelve conserved hydrophobic cores of transmembrane domains. The protein sequences of S. hasta MTs were highly conserved in the total number of cysteine residues and their locations. mRNA of the five genes were expressed in a wide range of tissues but the levels were relatively higher in the liver. Cu exposure tended to up-regulate the mRNA expressions of CTR2, DMT1, MT1 and MT2. However, Fe down-regulated the Cu-induced increase of CTR2 and DMT1 mRNA levels. For the first time, our study cloned and characterized CTR1, CTR2, DMT1, MT1 and MT2 genes in S. hasta and determined their tissue-specific expression, and also the transcriptional change by Cu and Fe exposure, which shed new light on the CuFe relationship and help to understand the basic mechanisms of Cu and Fe homeostasis in fish.
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Affiliation(s)
- Feng Chen
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhi Luo
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan 430070, China; Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province, Changde 415000, China.
| | - Yao-Fang Fan
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan 430070, China
| | - Kun Wu
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan 430070, China
| | - Ya-Xiong Pan
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan 430070, China
| | - Xu Liu
- Postgraduate Research Base, Panjin Guanghe Fishery Co. Ltd., Panjin 124200, China
| | - Li-Han Zhang
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan 430070, China
| | - Yu-Feng Song
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture of P.R.C., Fishery College, Huazhong Agricultural University, Wuhan 430070, China
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Guo W, Zhang J, Li W, Xu M, Liu S. Disruption of iron homeostasis and resultant health effects upon exposure to various environmental pollutants: A critical review. J Environ Sci (China) 2015; 34:155-164. [PMID: 26257358 DOI: 10.1016/j.jes.2015.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 04/19/2015] [Accepted: 04/20/2015] [Indexed: 06/04/2023]
Abstract
Environmental pollution has become one of the greatest problems in the world, and the concerns about environmental pollutants released by human activities from agriculture and industrial production have been continuously increasing. Although intense efforts have been made to understand the health effects of environmental pollutants, most studies have only focused on direct toxic effects and failed to simultaneously evaluate the long-term adaptive, compensatory and secondary impacts on health. Burgeoning evidence suggests that environmental pollutants may directly or indirectly give rise to disordered element homeostasis, such as for iron. It is crucially important to maintain concerted cellular and systemic iron metabolism. Otherwise, disordered iron metabolism would lead to cytotoxicity and increased risk for various diseases, including cancers. Thus, study on the effects of environmental pollutants upon iron homeostasis is urgently needed. In this review, we recapitulate the available findings on the direct or indirect impacts of environmental pollutants, including persistent organic pollutants (POPs), heavy metals and pesticides, on iron homeostasis and associated adverse health problems. In view of the unanswered questions, more efforts are warranted to investigate the disruptive effects of environmental pollutants on iron homeostasis and consequent toxicities.
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Affiliation(s)
- Wenli Guo
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Jie Zhang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Wenjun Li
- School of Stomatology, Wuhan University, Wuhan 430072, China
| | - Ming Xu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Sijin Liu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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Gao C, Zhu L, Zhu F, Sun J, Zhu Z. Effects of different sources of copper on Ctr1, ATP7A, ATP7B, MT and DMT1 protein and gene expression in Caco-2 cells. J Trace Elem Med Biol 2014; 28:344-50. [PMID: 24815816 DOI: 10.1016/j.jtemb.2014.04.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 03/17/2014] [Accepted: 04/14/2014] [Indexed: 01/04/2023]
Abstract
Copper sulfate (CuSO4), micron copper oxide (micron CuO) and nano copper oxide (nano CuO) at different concentrations were, respectively, added to culture media containing Caco-2 cells and their effects on Ctr1, ATP7A/7B, MT and DMT1 gene expression and protein expression were investigated and compared. The results showed that nano CuO promoted mRNA expression of Ctr1 in Caco-2 cells, and the difference was significant compared with micron CuO and CuSO4. Nano CuO was more effective in promoting the expression of Ctr1 protein than CuSO4 and micron CuO at the same concentration. Nano CuO at a concentration of 62.5 μM increased the mRNA expression levels of ATP7A and ATP7B, and the difference was significant compared with CuSO4. The addition of CuSO4 and nano CuO to the culture media promoted the expression of ATP7B proteins. CuSO4 at a concentration of 125 μM increased the mRNA expression level of MT in Caco-2 cells, and the difference was significant compared with nano CuO and micron CuO. Nano CuO at a concentration of 62.5 μM inhibited the mRNA expression of DMT1, and the difference was significant compared with CuSO4 and micron CuO. Thus, the effects of CuSO4, micron CuO and nano CuO on the expression of copper transport proteins and the genes encoding these proteins differed considerably. Nano CuO has a different uptake and transport mechanism in Caco-2 cells to those of CuSO4 and micron CuO.
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Affiliation(s)
- Chen Gao
- College of Veterinary Medicine, Jilin University, Changchun 130062, China; College of Animal Science and Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China; College of Agriculture, Dezhou University, Dezhou 253023, China
| | - Lianqin Zhu
- College of Veterinary Medicine, Jilin University, Changchun 130062, China; College of Animal Science and Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China.
| | - Fenghua Zhu
- College of Animal Science and Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China
| | - Jinquan Sun
- College of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China
| | - Zuxian Zhu
- College of Animal Science and Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China
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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] [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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15
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Arredondo M, Mendiburo MJ, Flores S, Singleton ST, Garrick MD. Mouse divalent metal transporter 1 is a copper transporter in HEK293 cells. Biometals 2013; 27:115-23. [PMID: 24327293 DOI: 10.1007/s10534-013-9691-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 12/01/2013] [Indexed: 01/14/2023]
Abstract
Divalent Metal Transporter 1 (DMT1) is an apical Fe transporter in the duodenum and is involved in endosomal Fe export. Four protein isoforms have been described for DMT1, two from mRNA with an iron responsive element (IRE) and two from mRNA without it. The sets of two begin in exon 1A or 2. We have characterized copper transport using mouse 2/-IRE DMT1 during regulated ectopic expression. HEK293 cells carrying a TetR:Hyg element were stably transfected with pDEST31 containing a 2/-IRE construct. (64)Cu(1+) incorporation in doxycycline treated cells exhibited 18.6 and 30.0-fold increases in Cu content, respectively when were exposed to 10 and 100 μM of extracellular Cu. Cu content was ~4-fold above that of parent cells or cells carrying just the vector. (64)Cu uptake in transfected cells pre-incubated with 5 μM of Cu-His revealed a Vmax and Km of 11.98 ± 0.52 pmol mg protein(-1) min(-1) and 2.03 ± 0.03 μM, respectively. Doxycycline-stimulated Cu uptake was linear with time. The rates of apical Cu uptake decreased and transepithelial transport increased when intracellular Cu increased. The optimal pH for Cu transport was 6.5; uptake of Cu was temperature dependent. Silver does not inhibit Cu uptake in cells carrying the vector. In conclusion, Cu uptake in HEK293 cells that over-expressed the 2/-IRE isoform of DMT1 transporter supports our earlier contention that DMT1 transports Cu as Cu(1+).
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Affiliation(s)
- Miguel Arredondo
- Micronutrients Laboratory, Nutrition Institute and Food Technology (INTA), Universidad de Chile, El Líbano 5524, Macul, Santiago, Chile,
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16
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Tinkov AA, Ajsuvakova OP, Shehtman AM, Boev VM, Nikonorov AA. Influence of iron and copper consumption on weight gain and oxidative stress in adipose tissue of Wistar rats. Interdiscip Toxicol 2012; 5:127-32. [PMID: 23554552 PMCID: PMC3600512 DOI: 10.2478/v10102-012-0021-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 07/03/2012] [Accepted: 07/17/2012] [Indexed: 12/23/2022] Open
Abstract
The aim of the present study was to assess the effect of iron and copper consumption on weight gain and development of oxidative stress in adipose tissue of rats. Control rats obtained pure drinking water. Iron-treated groups of animals obtained FeSO4•12H2O with drinking water in concentrations of 3 and 6 mg/l, while copper-treated rats obtained CuSO4 in concentrations of 4.88 and 9.76 mg/l. The animals of the 6th group received a mixture of FeSO4•12H2O and CuSO4 in the respective concentrations of 3 and 4.88 mg/l in drinking water. All animals received a standard chow. The final weight of rats from all the experimental groups, especially in those obtaining the combination of iron and cooper, exceeded the control values. Maximal weight of fat pads was observed in animals receiving drinking water with 3 mg/l FeSO4•12H2O, 4.88 and 9.76 mg/l CuSO4, and the mixture of FeSO4•12H2O and CuSO4. The maximal intensity of free radical processes, as estimated by the concentration of fluorescent modified amino acids and the intensity of chemiluminescence in adipose tissue homogenates, was observed in rats obtaining iron in the concentration of 3 mg/l in the drinking water.
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Affiliation(s)
- Alexey A. Tinkov
- Department of Biochemistry, Orenburg State Medical Academy, Orenburg, Russia
- Interdepartmental Biochemical Laboratory, Orenburg State Medical Academy, Orenburg, Russia
| | - Olga P. Ajsuvakova
- Interdepartmental Biochemical Laboratory, Orenburg State Medical Academy, Orenburg, Russia
| | - Alexandr M. Shehtman
- Department of Human Pathology, 1st Orenburg Regional Clinical Hospital, Orenburg, Russia
| | - Viktor M. Boev
- Department of general and communal hygiene and human ecology, Orenburg State Medical Academy, Orenburg, Russia
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17
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Monnot AD, Zheng G, Zheng W. Mechanism of copper transport at the blood-cerebrospinal fluid barrier: influence of iron deficiency in an in vitro model. Exp Biol Med (Maywood) 2012; 237:327-33. [PMID: 22442359 DOI: 10.1258/ebm.2011.011170] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Copper (Cu) is an essential trace element that requires tight homeostatic regulation to ensure appropriate supply while not causing cytotoxicity due to its strong redox potential. Our previous in vivo study has shown that iron deficiency (FeD) increases Cu levels in brain tissues, particularly in the choroid plexus, where the blood-cerebrospinal fluid (CSF) barrier resides. This study was designed to elucidate the mechanism by which FeD results in excess Cu accumulation at the blood-CSF barrier. The effect of FeD on cellular Cu retention and transporters Cu transporter-1 (Ctr1), divalent metal transporter 1 (DMT1), antioxidant protein-1 (ATOX1) and ATP7A was examined in choroidal epithelial Z310 cells. The results revealed that deferoximine treatment (FeD) resulted in 70% increase in cellular Cu retention (P < 0.05). A significant increase in the mRNA levels of DMT1, but not Ctr1, was also observed after FeD treatment, suggesting a critical role of DMT1 in cellular Cu regulation during FeD. Knocking down Ctr1 or DMT1 resulted in significantly lower Cu uptake by Z310 cells, whereas the knocking down of ATOX1 or ATP7A led to substantial increases of cellular retention of Cu. Taken together, these results suggest that Ctr1, DMT1, ATOX1 and ATP7A contribute to Cu transport at the blood-CSF barrier, and that the accumulation of intracellular Cu found in the Z310 cells during FeD appears to be mediated, at least in part, via the upregulation of DMT1 after FeD treatment.
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Affiliation(s)
- Andrew D Monnot
- School of Health Sciences, Purdue University, 550 Stadium Mall Drive, CIVL1169, West Lafayette, IN 47907, USA
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18
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Li YQ, Bai B, Cao XX, Zhang YH, Yan H, Zheng QQ, Zhuang GH. Divalent metal transporter 1 expression and regulation in human placenta. Biol Trace Elem Res 2012; 146:6-12. [PMID: 21947861 DOI: 10.1007/s12011-011-9214-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 09/14/2011] [Indexed: 01/13/2023]
Abstract
Divalent metal transporter 1 (DMT1) is likely responsible for the release of iron from endosomes to the cytoplasm in placental syncytiotrophoblasts (STB). To determine the localization and the regulation of DMT1 expression by iron directly in placenta, the expression of DMT1 in human term placental tissues and BeWo cells (human placental choriocarcinoma cell line) was detected and the change in expression in response to different iron treatments on BeWo cells was observed. DMT1 was shown to be most prominent near the maternal side in human term placenta and predominantly in the cytoplasm of BeWo cells. BeWo cells were treated with desferrioxamine (DFO) and human holotransferrin (hTf-2Fe) and it was found that both DMT1 mRNA and protein increased significantly with DFO treatment and decreased with hTf-2Fe treatment. Further, DMT1 mRNA responded more significantly to treatments if it possessed an iron-responsive element than mRNA without this element. This study indicated that DMT1 is likely involved in endosomal iron transport in placental STB and placental DMT1 + IRE expression was primarily regulated by the IRE/IRP mechanism.
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Affiliation(s)
- Yan-Qin Li
- Department of Public Health, Xi'an Jiaotong University College of Medicine, Xi'an, Shaanxi, China.
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19
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Regulation of brain iron and copper homeostasis by brain barrier systems: implication in neurodegenerative diseases. Pharmacol Ther 2011; 133:177-88. [PMID: 22115751 DOI: 10.1016/j.pharmthera.2011.10.006] [Citation(s) in RCA: 198] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 10/27/2011] [Indexed: 12/21/2022]
Abstract
Iron (Fe) and copper (Cu) are essential to neuronal function; excess or deficiency of either is known to underlie the pathoetiology of several commonly known neurodegenerative disorders. This delicate balance of Fe and Cu in the central milieu is maintained by the brain barrier systems, i.e., the blood-brain barrier (BBB) between the blood and brain interstitial fluid and the blood-cerebrospinal fluid barrier (BCB) between the blood and cerebrospinal fluid (CSF). This review provides a concise description on the structural and functional characteristics of the brain barrier systems. Current understanding of Fe and Cu transport across the brain barriers is thoroughly examined, with major focuses on whether the BBB and BCB coordinate the direction of Fe and Cu fluxes between the blood and brain/CSF. In particular, the mechanism by which pertinent metal transporters in the barriers, such as the transferrin receptor (TfR), divalent metal transporter (DMT1), copper transporter (CTR1), ATP7A/B, and ferroportin (FPN), regulate metal movement across the barriers is explored. Finally, the detrimental consequences of dysfunctional metal transport by brain barriers, as a result of endogenous disorders or exogenous insults, are discussed. Understanding the regulation of Fe and Cu homeostasis in the central nervous system aids in the design of new drugs targeted on the regulatory proteins at the brain barriers for the treatment of metal's deficiency or overload-related neurological diseases.
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20
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Boyle D, Hogstrand C, Bury NR. Physiological response to a metal-contaminated invertebrate diet in zebrafish: importance of metal speciation and regulation of metal transport pathways. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2011; 105:21-28. [PMID: 21684238 DOI: 10.1016/j.aquatox.2011.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 04/29/2011] [Accepted: 05/08/2011] [Indexed: 05/30/2023]
Abstract
Dietary metal uptake in fish is determined by metal bioavailability in prey and the metal requirements of the fish. In this study zebrafish were fed the intertidal polychaete worm Nereis diversicolor (3% wet weight day(-1)) collected from Ag, Cd and Cu-impacted Restronguet Creek (RC) or a reference site, Blackwater estuary (BW), for 21 days. On days 0, 7, 14 and 21 fish were fed a single meal of RC or BW N. diversicolor labeled with (110m)Ag or (109)Cd for measurements of metal assimilation efficiency (AE). Zebrafish intestines were also taken for mRNA expression analysis of copper transporter 1 (ctr1), divalent metal transporter 1 (dmt1) and metallothionein 2 (mt2). No significant difference was observed in the AE of (109)Cd in metal naïve fish at day 0 between RC and BW worms, 11.8±2.1 and 15.3±2.8%, respectively. However, AE of (110m)Ag was significantly greater in fish fed worms from BW compared to RC, 5±1.2% and 1.6±0.5%, respectively at day 0. Fractionation analysis of radiolabeled metal partitioned in N. diversicolor from RC revealed a greater proportion of Ag (40±1.1%) in a fraction containing protein and organelle bound metal, associated with high trophic availability, compared to BW polychaetes (24±2.5%). Lower AE of (110m)Ag from RC polychaetes is therefore unlikely due to speciation of (110m)Ag in N. diversicolor from RC, but to the high concentration of Cu, a potential Ag antagonist. Exposure to RC polychaetes significantly increased the AE of (110m)Ag (6.2±1%), but not (109)Cd, from RC worms, after 21 days. AE of (110m)Ag and (109)Cd was unaffected by pre-exposure to BW. Elevated concentration of intestinal Cu and increased expression of ctr1, dmt1 and mt2 after 14 days exposure in fish fed worms from RC suggest altered Cu handling strategy of these fish which may increase AE of Ag via shared Ag and Cu transport pathways. These data suggest metal exposure history of invertebrates may affect metal bioavailability to fish, and fish may alter intestinal uptake physiology during chronic dietary exposure with implications for the assimilation and toxicity of dietary metals.
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Affiliation(s)
- David Boyle
- Nutritional Sciences Division, King's College London, London SE1 9NH, United Kingdom.
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Kim EY, Pai TK, Han O. Effect of bioactive dietary polyphenols on zinc transport across the intestinal Caco-2 cell monolayers. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:3606-12. [PMID: 21410257 PMCID: PMC3087602 DOI: 10.1021/jf104260j] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Polyphenolic compounds are known to possess many beneficial health effects, including the antioxidative activities of scavenging reactive oxygen species and chelating metals, such as iron and zinc. Tea and red wine are thought to be important sources of these compounds. However, some polyphenolic compounds can also reduce the absorption of iron, and possibly other trace metals, when included in a diet. There is very little information on the effect of dietary polyphenolic compounds on the status of trace elements other than iron. The effects of epigallocatechin-3-gallate (EGCG), green tea extract (GT), and grape seed extract (GSE) on the absorption of (65)Zn were examined and compared with their effects on (55)Fe absorption in human intestinal Caco-2 cells grown on microporous membrane inserts. The levels of EGCG, GT, and GSE used in this study were within physiological ranges and did not affect the integrity of the Caco-2 cell monolayers. GSE significantly (P < 0.05) reduced zinc transport across the cell monolayer, and the decreased zinc transport was associated with a reduction in apical zinc uptake. However, EGCG and GT did not alter zinc absorption. In contrast, the polyphenolic compounds in EGCG, GT, and GSE almost completely blocked transepithelial iron transport across the cell monolayer. The effect of GSE on zinc absorption was very different from that on iron absorption. Whereas GSE decreased zinc absorption by reducing apical zinc uptake, the polyphenolic compounds inhibited iron absorption by enhancing apical iron uptake. GSE inhibited zinc absorption similarly to that observed for phytate. Phytate significantly (P < 0.05) decreased transepithelial zinc transport by reducing apical zinc uptake. The inhibition of zinc absorption may be due to the presence of procyanidins in GSE, which bind zinc with high affinity and block the transport of zinc across the apical membrane of enterocytes. Further research on the absorption of zinc as zinc-polyphenol complexes and free zinc should provide further insight into the process of dietary zinc absorption in the presence of GSE and other bioactive dietary polyphenols. The present study suggests that some individuals should consider their zinc status if they regularly consume procyanidin-containing foods in their diet. However, further studies, especially in vivo studies, are needed to confirm these results.
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Affiliation(s)
- Eun-Young Kim
- Department of Nutritional Sciences, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Ma Q, Kim EY, Han O. Bioactive dietary polyphenols decrease heme iron absorption by decreasing basolateral iron release in human intestinal Caco-2 cells. J Nutr 2010; 140:1117-21. [PMID: 20375262 DOI: 10.3945/jn.109.117499] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Because dietary polyphenolic compounds have a wide range of effects in vivo and vitro, including chelation of metals such as iron, it is prudent to test whether the regular consumption of dietary bioactive polyphenols impair the utilization of dietary iron. Because our previous study showed the inhibitory effect of (-) -epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) on nonheme iron absorption, we investigated whether EGCG and GSE also affect iron absorption from heme. The fully differentiated intestinal Caco-2 cells grown on microporous membrane inserts were incubated with heme (55)Fe in uptake buffer containing EGCG or GSE in the apical compartment for 7 h. Both EGCG and GSE decreased (P < 0.05) transepithelial transport of heme-derived iron. However, apical heme iron uptake was increased (P < 0.05) by GSE. Despite the increased cellular levels of heme (55)Fe, the transfer of iron across the intestinal basolateral membrane was extremely low, indicating that basolateral export was impaired by GSE. In contrast, EGCG moderately decreased the cellular assimilation of heme (55)Fe, but the basolateral iron transfer was extremely low, suggesting that the basolateral efflux of heme iron was also inhibited by EGCG. Expression of heme oxygenase, ferroportin, and hephaestin protein was not changed by EGCG and GSE. The apical uptake of heme iron was temperature dependent and saturable in fully differentiated Caco-2 cells. Our data show that bioactive dietary polyphenols inhibit heme iron absorption mainly by reducing basolateral iron exit rather than decreasing apical heme iron uptake in intestinal cells.
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Affiliation(s)
- Qianyi Ma
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA 16802, USA
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Crisponi G, Nurchi VM, Fanni D, Gerosa C, Nemolato S, Faa G. Copper-related diseases: From chemistry to molecular pathology. Coord Chem Rev 2010. [DOI: 10.1016/j.ccr.2009.12.018] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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24
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Abstract
Interactions between the essential dietary metals, iron and copper, have been known for many years. This review highlights recent advances in iron-copper interactions with a focus on tissues and cell types important for regulating whole-body iron and copper homeostasis. Cells that mediate dietary assimilation (enterocytes) and storage and distribution (hepatocytes) of iron and copper are considered, along with the principal users (erythroid cells) and recyclers of red cell iron (reticuloendothelial macrophages). Interactions between iron and copper in the brain are also discussed. Many unanswered questions regarding the role of these metals and their interactions in health and disease emerge from this synopsis, highlighting extensive future research opportunities.
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Affiliation(s)
- James F Collins
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida 32611, USA
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25
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Smith A, Rish KR, Lovelace R, Hackney JF, Helston RM. Role for copper in the cellular and regulatory effects of heme-hemopexin. Biometals 2008; 22:421-37. [DOI: 10.1007/s10534-008-9178-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Accepted: 11/04/2008] [Indexed: 10/21/2022]
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Kim EY, Ham SK, Shigenaga MK, Han O. Bioactive dietary polyphenolic compounds reduce nonheme iron transport across human intestinal cell monolayers. J Nutr 2008; 138:1647-51. [PMID: 18716164 DOI: 10.1093/jn/138.9.1647] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
There is persuasive epidemiological evidence that regular intake of dietary bioactive polyphenolic compounds promotes human health. Because dietary polyphenolic compounds have a wide range of effects in vivo and vitro, including chelation of metals such as iron, it is prudent to test whether the regular consumption of bioactive polyphenolic components impair the utilization of dietary iron. We examined the influence of the dietary polyphenols (-) -epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) on transepithelial iron transport in Caco-2 intestinal cells. The range of EGCG and GSE concentrations used in this study was within physiological levels and did not affect the integrity of differentiated Caco-2 cell monolayers. Both EGCG and GSE decreased (P < 0.001) transepithelial iron transport. However, apical iron uptake was increased (P < 0.001) by the addition of EGCG and GSE. The increased uptake of iron might be due in part to the reducing activity of EGCG and GSE. Both EGCG and GSE reduced approximately 15% of the applied Fe(3+) to Fe(2+) in the uptake buffer. Despite the increased cellular levels of (55)Fe, the transfer of iron across the basolateral membrane of the enterocyte was extremely low, indicating that basolateral exit via ferroportin-1 was impaired, possibly through formation of a nontransportable polyphenol-iron complex. Our data show that polyphenols inhibit nonheme iron absorption by reducing basolateral iron exit rather than by decreasing apical iron import in intestinal cells.
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Affiliation(s)
- Eun-Young Kim
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA 16802, USA
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Kong WN, Zhao SE, Duan XL, Yang Z, Qian ZM, Chang YZ. Decreased DMT1 and increased ferroportin 1 expression is the mechanisms of reduced iron retention in macrophages by erythropoietin in rats. J Cell Biochem 2008; 104:629-41. [PMID: 18189270 DOI: 10.1002/jcb.21654] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recycled iron from reticuloendothelial macrophages to erythroid precursors is important to maintain the iron homeostasis. However, the molecular mechanisms underlying iron homeostasis in macrophages are poorly understood. In this study, male Sprague-Dawley rats were treated with recombinant human erythropoietin (rHuEpo, 500 IU/day, s.c.) for 3 days. At the fifth day, peritoneal exudate macrophages were harvested, and then (55)Fe uptake and release were measured by liquid scintillation counting method. The expression of divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) in peritoneal exudate macrophages was detected by RT-PCR and Western blot. In order to exclude the direct effect of rHuEpo on macrophages, the parallel experiments were performed with incubation normal peritoneal exudate macrophages with rHuEpo (2 IU/ml). Our results showed rHuEpo injection reduced the peritoneal exudate macrophages iron retention. The uptake of Fe(II) was decreased via the suppression of DMT1 (+IRE) expression and the release of Fe(II) was increased with increasing the expression of FPN1 in macrophages. Moreover, the expression of HAMP mRNA was four times lower in rHuEpo-treated liver of rats than control group (CG). HAMP mRNA expression was increased; the synthesis of DMT1 had no significant change, whereas the FPN1 was decreased in normal peritoneal exudate macrophages after treatment with rHuEpo in vitro. We conclude that hepcidin may play a major, causative role in the change of FPN1 synthesis and that decreased the iron retention in macrophages of rHuEpo-treated rats.
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Affiliation(s)
- Wei-Na Kong
- Laboratory of Molecular Iron Metabolism, College of Life Science, Hebei Normal University, Shijiazhuang 050016, Hebei Province, PR China
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Qian ZM, Chang YZ, Zhu L, Yang L, Du JR, Ho KP, Wang Q, Li LZ, Wang CY, Ge X, Jing NL, Li L, Ke Y. Development and iron-dependent expression of hephaestin in different brain regions of rats. J Cell Biochem 2008; 102:1225-33. [PMID: 17516501 DOI: 10.1002/jcb.21352] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
It has been suggested that Hephaestin (Heph), a newly discovered ceruloplasmin homologue, is necessary for iron egress from the enterocytes into circulation via interacting with ferroportin1 (FP1). Based on the putative function of Heph, and the similarity between the process of iron transport in the enterocytes and that in the blood-brain barrier (BBB) cells, it has also been proposed that Heph plays a similar role in exporting iron from the BBB cells and other brain cells as it works in the enterocytes via interacting with FP1. The existence of FP1 in the brain has been demonstrated. In this study, we investigated Heph expression and effects of development and iron in the cortex, hippocampus, striatum, and substantia nigra. The data demonstrated that all the four regions we examined have the ability to express Heph mRNA and protein. The findings also showed that both the development and iron status have a significant effect on Heph expression and the effects of iron status are regionally specific. It was also suggested that Heph expression is probably regulated at the transcriptional level by the development and iron in these brain regions. These findings, together with other published data, support a putative role of Heph in the iron metabolism in the brain.
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Affiliation(s)
- Zhong-Ming Qian
- Institute for Nautical Medicine and Key Laboratory of Neuroregeneration, Nantong University, Nantong 226001, P.R. China
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30
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Rashtchizadeh N, Ettehad S, DiSilvestro RA, Mahdavi R. Antiatherogenic effects of zinc are associated with copper in iron-overloaded hypercholesterolemic rabbits. Nutr Res 2008; 28:98-105. [DOI: 10.1016/j.nutres.2007.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2007] [Revised: 11/29/2007] [Accepted: 12/02/2007] [Indexed: 11/29/2022]
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31
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Han O, Kim EY. Colocalization of ferroportin-1 with hephaestin on the basolateral membrane of human intestinal absorptive cells. J Cell Biochem 2007; 101:1000-10. [PMID: 17486601 DOI: 10.1002/jcb.21392] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An iron exporter ferroportin-1 (FPN-1) and a multi-copper oxidase hephaestin (Heph) are predicted to be expressed on the basolateral membrane of the enterocyte and involved in the processes of iron export across the basolateral membrane of the enterocyte. However, it is not clear where these proteins are exactly located in the intestinal absorptive cell. We examined cellular localization of FPN-1 and Heph in the intestinal absorptive cells using the fully differentiated Caco-2 cells. Confocal microscope study showed that FPN-1 and Heph are located on the basolateral membrane and they are associated with the transferrin receptor (TfR) in fully differentiated Caco-2 cells grown on microporous membrane inserts. However, Heph protein was not detected in the crypt cell-like proliferating Caco-2 cell. In stably transfected human intestinal absorptive cells expressing human FPN-1 modified by the addition of GFP at the C-terminus, we show that FPN-1-GFP is located on the basolateral membrane and it is associated with Heph suggesting the possibility that FPN-1 might associate and interact with Heph in the process of iron exit across the basolateral membrane of intestinal absorptive cell.
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Affiliation(s)
- Okhee Han
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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32
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Abstract
Transfer of iron from the mucosa is a critical step in dietary iron assimilation that is tightly regulated to ensure the appropriate amount of iron is absorbed to meet the body's demands. Too much iron is highly toxic, and failure to properly control intestinal iron export causes iron overload associated with hereditary forms of hemochromatosis. One form of genetic iron overload, ferroportin disease, originates due to defects in ferroportin, the membrane iron exporter. Ferroportin acts in conjunction with the intestinal ferroxidase hephaestin to mediate release of iron from the enterocyte. How iron is then acquired by transferrin and released into circulation remains an unknown step in this process.
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Affiliation(s)
- Marianne Wessling-Resnick
- Dept. of Genetics and Complex Diseases, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA.
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Huang XP, Spino M, Thiessen JJ. Transport kinetics of iron chelators and their chelates in Caco-2 cells. Pharm Res 2006; 23:280-90. [PMID: 16388408 DOI: 10.1007/s11095-005-9258-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Accepted: 10/25/2005] [Indexed: 02/01/2023]
Abstract
PURPOSE Caco-2 monolayers were used to contrast the bidirectional transport of iron chelators and their chelates and to estimate fundamental kinetics associated with their intestinal absorption. METHODS Bidirectional transport was studied at 37 degrees C and pH 7.4 using 500-microM concentrations. Monolayer integrity was tested via transepithelial electrical resistance and sodium fluorescein permeability. Apical and basolateral analysis provided mass balance evidence. Apparent permeability coefficient (P(app)) served to rank and compare molecules and estimate in vivo bioavailability. Model-dependent rate constants defined cellular influx and efflux. RESULTS 1) P(app) ranked in decreasing order for chelators from directional transport studies were CP363 > deferiprone> ICL670 > CP502 > deferoxamine (DFO). 2) Fe(CP502)(3), Fe(ICL670)(2), and FeDFO were not measurable in receiving chambers, whereas Fe(deferiprone)(3) and Fe(CP363)(3) were detected in both directions. 3) CP363 was transported significantly faster from the basolateral to the apical direction than the converse. 4) Mass balance of donor and receiver chambers gave approximately 100% recovery in all cases. 5) Kinetic analysis supports the view that the Caco-2 chelator efflux constants are generally greater than their influx constants. CONCLUSIONS Caco-2 cells are useful in screening iron chelators and chelates and estimating bioavailabilities. Structure and distribution coefficients partially predict passive transport through Caco-2 monolayers.
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Affiliation(s)
- Xi-Ping Huang
- Leslie Dan Faculty of Pharmacy, University of Toronto, 19 Russell St., Toronto, Ontario, Canada, M5S 2S2
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34
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Petrak J, Vyoral D. Hephaestin—a ferroxidase of cellular iron export. Int J Biochem Cell Biol 2005; 37:1173-8. [PMID: 15778082 DOI: 10.1016/j.biocel.2004.12.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Indexed: 01/09/2023]
Abstract
Hephaestin is a transmembrane copper-dependent ferroxidase necessary for effective iron transport from intestinal enterocytes into the circulation. Hephaestin is mutated in sex-linked anemia (sla) mice. The initial uptake of iron from the diet in these animals is normal, but the basolateral export of iron from enterocytes is defective, resulting in iron deficiency and microcytic hypochromic anemia. In addition to the small intestine, hephaestin is expressed to a lesser extent in colon, spleen, placenta and kidney but its role in these tissues remains unknown. So far, hephaestin has not been linked to a human disease.
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Affiliation(s)
- Jiri Petrak
- Institute of Hematology and Blood Transfusion, U Nemocnice 1, 128 20 Praha 2, Czech Republic.
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35
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Marzullo L, Tosco A, Capone R, Andersen HS, Capasso A, Leone A. Identification of dietary copper- and iron-regulated genes in rat intestine. Gene 2004; 338:225-33. [PMID: 15315826 DOI: 10.1016/j.gene.2004.05.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2003] [Revised: 05/13/2004] [Accepted: 05/28/2004] [Indexed: 10/26/2022]
Abstract
Copper and iron act at different levels on gene expression. Due to their chemical reactivity, both metals could play a role in the regulation of the protein machinery involved in their metabolism, and/or of the metabolic function they are involved in. Experimental and clinical evidences raise also the hypothesis of the existence of genes commonly regulated by both metals. Purpose of this work was to find genes modulated by copper and iron in the rat intestine. A panel of 24 animals was randomly divided into three nutritional treatments including a control, a copper-deficient and an iron-deficient diet. The positive regulation of iron responsive element (IRE)-DMT1 gene was found, with different extent, in both experimental groups. A differential display reverse transcription (DDRT)-polymerase chain reaction (PCR) analysis carried out on the rat intestinal mRNAs demonstrated the differential expression of five cDNA fragments. Among these, the Cytochrome c oxidase (COX) subunit II mitochondrial gene resulted to be regulated by both metals, the Serum and Glucocorticoids-regulated Kinase (SGK) gene mainly by iron, and an Ebnerin-like 2 kb mRNA dramatically down-regulated by copper. Two residual clones showed low identity scores with sequences present in data bank. Finally, we observed that both iron and copper are able to modulate the expression of the three characterized genes in some tissues, other than intestine.
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Affiliation(s)
- Liberato Marzullo
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Salerno-Via Ponte Don Melillo, Fisciano, Salerno 84084, Italy.
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36
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Bauerly KA, Kelleher SL, Lönnerdal B. Functional and molecular responses of suckling rat pups and human intestinal Caco-2 cells to copper treatment. J Nutr Biochem 2004; 15:155-62. [PMID: 15023397 DOI: 10.1016/j.jnutbio.2003.10.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Revised: 10/09/2003] [Accepted: 10/16/2003] [Indexed: 11/25/2022]
Abstract
Ctr1 and Atp7A are copper (Cu) transporters that may play a role in the regulation of intestinal Cu absorption; however, intestinal regulation of these transporters by Cu in vivo has not been well defined. In this study, we hypothesized that Cu supplementation would alter the expression of intestine Ctr1 and Atp7A in vivo and further documented effects of Cu exposure on Cu transport, Ctr1 and Atp7A levels and localization in enterocyte-like Caco-2 cells. Suckling rat pups were supplemented with Cu (0 and 25 microg Cu/day) for 10 days and small intestine Cu concentration, Ctr1, Atp7A and metallothionein (MT) gene expression were measured by Northern blot analysis. Caco-2 cells were treated with basal medium, or medium supplemented with 3 and 94 microM CuSO4 and 67Cu transport, Ctr1 and Atp7A levels and localization were determined. In rat pups, Cu supplementation increased intestinal Cu, Ctr1 and MT gene expression; however, Atp7A gene expression was not significantly affected. Caco-2 cells treated with 94 microM Cu had lower cellular Cu uptake and export compared to untreated cells. While Ctr1 and Atp7A gene and protein levels were unaffected, confocal microscopy indicated that Ctr1 was endocytosed and co-localized with transferrin in Cu treated cells. This study demonstrates the functional response of intestinal cells to Cu treatment and suggests that both Ctr1 and Atp7A may regulate Cu absorption.
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Affiliation(s)
- Kathryn A Bauerly
- Department of Nutrition, University of California, Davis, CA 95616, USA
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37
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Abstract
A recent study of mice with sex-linked anemia compared differences between genetic and nutritional iron deficiencies. Comparison of these models helps to illuminate how the body regulates dietary iron absorption at the molecular level.
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38
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Arredondo M, Cambiazo V, Tapia L, González-Agüero M, Núñez MT, Uauy R, González M. Copper overload affects copper and iron metabolism in Hep-G2 cells. Am J Physiol Gastrointest Liver Physiol 2004; 287:G27-32. [PMID: 14988066 DOI: 10.1152/ajpgi.00297.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Divalent metal transporter #1 (DMT1) is responsible for intestinal nonheme Fe apical uptake. However, DMT1 appears to have an additional function in Cu transport in intestinal cells. Because the liver has an essential role in body Cu homeostasis, we examined the potential involvement of Cu in the regulation of DMT1 expression and activity in Hep-G2 cells. Cells exposed to 10 microM Cu exhibited a 22-fold increase in Cu content and a twofold decrease in Fe content compared with cells maintained in 0.4 microM Cu. (64)Cu uptake in Cu-deficient Hep-G2 cells showed a twofold decrease in K(m) compared with cells grown in 10 microM Cu. The decreased K(m) may represent an adaptive response to Cu deficiency. Cells treated with >50 microM Cu, showed an eightfold increase in cytosolic metallothionein. DMT1 protein decreased (35%), suggesting that intracellular Cu caused a reduction of DMT1 protein levels. Our data indicate that, as a result of Cu overload, Hep-G2 cells reduced their Fe content and their DMT1 protein levels. These findings strongly suggest a relationship between Cu and Fe homeostasis in Hep-G2 cells in which Cu accumulation downregulates DMT1 activity.
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Affiliation(s)
- M Arredondo
- Microminerals Laboratory, Institute of Nutrition and Food Technology, University of Chile, Casillo 138-11, Santiago, Chile
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Heath LM, Soole KL, McLaughlin ML, McEwan GTA, Edwards JW. Toxicity of environmental lead and the influence of intestinal absorption in children. REVIEWS ON ENVIRONMENTAL HEALTH 2003; 18:231-250. [PMID: 15025188 DOI: 10.1515/reveh.2003.18.4.231] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Exposure to metals, particularly lead, remains a widespread issue that is associated with historical and current industrial practices. Whereas the toxic properties of metals are well described, exposure to metals per se is only one of many factors contributing to elevated blood metal concentrations and their consequent health effects in humans. The absorbed dose of metal is affected by geochemical, biochemical, and physiological parameters that influence the rate and extent of absorption. In children, the interplay among these factors can be of critical importance, especially when biochemical and physiological processes might not have matured to their normal adult status. Such immaturity represents an elevated risk to metal-exposed children because they might be more susceptible to enhanced absorption, especially via the oral route. This review brings together the more recent findings on the physiological mechanisms of metal absorption, especially lead, and examines several models that can be useful in assessing the potential for metal uptake in children.
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Affiliation(s)
- Linda M Heath
- Department of Environmental Health, School of Medicine, Flinders University, Adelaide, South Australia
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40
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Zerounian NR, Redekosky C, Malpe R, Linder MC. Regulation of copper absorption by copper availability in the Caco-2 cell intestinal model. Am J Physiol Gastrointest Liver Physiol 2003; 284:G739-47. [PMID: 12540371 DOI: 10.1152/ajpgi.00415.2002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Relatively little is known about the individual steps in intestinal copper absorption and whether or how they may be regulated. Polarized Caco-2 cell monolayers with tight junctions offer an already tested model in which to study intestinal metal transport. This model was used to examine potential effects of cellular copper availability on copper absorption. Uptake and transport were determined on application of (64)Cu(II) to the brush border. In the range of 0.2-2 micro M, uptake was dose dependent and was approximately 20% of dose/90 min. Overall transport of (64)Cu across the basolateral surface was approximately 0.3%. When cellular copper levels were depleted 40% by 18-h pretreatment with the specific copper chelator triethylenetetraamine, uptake and overall transport were markedly increased, going to 80 and 65% of dose, respectively. Cellular retention of (64)Cu fell fourfold, from 6 to 1.5%. Depletion of copper with the chelator was rapid and preceded initial changes in uptake and overall transport by 4 h. A lesser depletion of cellular copper (13%) failed to enhance copper uptake but doubled the rate of overall transport, as measured with (64)Cu and by atomic absorption. As previously reported, preexposure of the cells to excess copper (10 micro M, 18 h) also enhanced copper uptake ( approximately 3-fold). In contrast, ascorbate (10-1,000 micro M) failed to significantly alter uptake and transport of 1 micro M (64)Cu. Our findings are consistent with the concepts that, in the low physiological range, copper availability alters the absorption capacity of the intestine to support whole body homeostasis and that basolateral transport is more sensitively regulated than uptake.
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Affiliation(s)
- Nora R Zerounian
- Department of Chemistry and Biochemistry and Institute for Molecular Biology and Nutrition, California State University, Fullerton, California 92834-6866, USA
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Chung J, Wessling-Resnick M. Molecular mechanisms and regulation of iron transport. Crit Rev Clin Lab Sci 2003; 40:151-82. [PMID: 12755454 DOI: 10.1080/713609332] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Iron homeostasis is primarily maintained through regulation of its transport. This review summarizes recent discoveries in the field of iron transport that have shed light on the molecular mechanisms of dietary iron uptake, pathways for iron efflux to and between peripheral tissues, proteins implicated in organellar transport of iron (particularly the mitochondrion), and novel regulators that have been proposed to control iron assimilation. The transport of both transferrin-bound and nontransferrin-bound iron to peripheral tissues is discussed. Finally, the regulation of iron transport is also considered at the molecular level, with posttranscriptional, transcriptional, and posttranslational control mechanisms being reviewed.
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Affiliation(s)
- Jayong Chung
- Department of Nutrition, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA
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Anderson GJ, Frazer DM, McKie AT, Vulpe CD. The ceruloplasmin homolog hephaestin and the control of intestinal iron absorption. Blood Cells Mol Dis 2002; 29:367-75. [PMID: 12547227 DOI: 10.1006/bcmd.2002.0576] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hephaestin is the gene affected in the sex-linked anemic (sla) mouse. These animals have a defect in the export of iron from intestinal enterocytes into the circulation and this implicates hephaestin in the basolateral transfer step of iron absorption. Hephaestin is homologous to the plasma copper-containing protein ceruloplasmin, and all residues involved in copper binding and disulfide bond formation in ceruloplasmin are conserved in hephaestin. Unlike ceruloplasmin, hephaestin is an integral membrane protein with a single trans-membrane domain. It is highly expressed throughout the small intestine, to a lesser extent in the colon, and at low levels in several other tissues. Surprisingly, most hephaestin appears to be located intracellularly in a perinuclear distribution. Like ceruloplasmin, hephaestin has a ferroxidase activity which is predicted to underlie its biological function. In addition, its expression is stimulated under iron deficient conditions. Analysis of the sla mouse has supported our model for the regulation of intestinal iron absorption whereby changes in systemic iron requirements alter the levels of basolateral transport components with subsequent regulation of brush border transport.
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Affiliation(s)
- Gregory J Anderson
- Iron Metabolism Laboratory, Queensland Institute of Medical Research, PO Royal Brisbane Hospital, Brisbane, Queensland 4029, Australia.
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