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Tian S, Wang B, Ding Y, Zhang Y, Yu P, Chang YZ, Gao G. The role of iron transporters and regulators in Alzheimer's disease and Parkinson's disease: Pathophysiological insights and therapeutic prospects. Biomed Pharmacother 2024; 179:117419. [PMID: 39245001 DOI: 10.1016/j.biopha.2024.117419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2024] [Revised: 09/02/2024] [Accepted: 09/04/2024] [Indexed: 09/10/2024] Open
Abstract
Brain iron homeostasis plays a vital role in maintaining brain development and controlling neuronal function under physiological conditions. Many studies have shown that the imbalance of brain iron homeostasis is closely related to the pathogenesis of neurodegenerative diseases (NDs), such as Alzheimer's disease (AD) and Parkinson's disease (PD). Recent advances have revealed the importance of iron transporters and regulatory molecules in the pathogenesis and treatment of NDs. This review summarizes the research progress on brain iron overload and the aberrant expression of several key iron transporters and regulators in AD and PD, emphasizes the pathological roles of these molecules in the pathogenesis of AD and PD, and highlights the therapeutic prospects of targeting these iron transporters and regulators to restore brain iron homeostasis in the treatment of AD and PD. A comprehensive understanding of the pathophysiological roles of iron, iron transporters and regulators, and their regulations in NDs may provide new therapeutic avenues for more targeted neurotherapeutic strategies for treating these diseases.
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Affiliation(s)
- Siqi Tian
- Ministry of Education Key Laboratory of Molecular and Cellular Biology; Hebei Collaborative Innovation Center for Eco-Environment; Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology; Hebei Research Center of the Basic Discipline of Cell Biology; College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Bing Wang
- Ministry of Education Key Laboratory of Molecular and Cellular Biology; Hebei Collaborative Innovation Center for Eco-Environment; Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology; Hebei Research Center of the Basic Discipline of Cell Biology; College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Yiqian Ding
- Ministry of Education Key Laboratory of Molecular and Cellular Biology; Hebei Collaborative Innovation Center for Eco-Environment; Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology; Hebei Research Center of the Basic Discipline of Cell Biology; College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Yu Zhang
- Ministry of Education Key Laboratory of Molecular and Cellular Biology; Hebei Collaborative Innovation Center for Eco-Environment; Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology; Hebei Research Center of the Basic Discipline of Cell Biology; College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Peng Yu
- Ministry of Education Key Laboratory of Molecular and Cellular Biology; Hebei Collaborative Innovation Center for Eco-Environment; Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology; Hebei Research Center of the Basic Discipline of Cell Biology; College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
| | - Yan-Zhong Chang
- Ministry of Education Key Laboratory of Molecular and Cellular Biology; Hebei Collaborative Innovation Center for Eco-Environment; Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology; Hebei Research Center of the Basic Discipline of Cell Biology; College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
| | - Guofen Gao
- Ministry of Education Key Laboratory of Molecular and Cellular Biology; Hebei Collaborative Innovation Center for Eco-Environment; Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology; Hebei Research Center of the Basic Discipline of Cell Biology; College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
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2
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Liu D, Hu Z, Lu J, Yi C. Redox-Regulated Iron Metabolism and Ferroptosis in Ovarian Cancer: Molecular Insights and Therapeutic Opportunities. Antioxidants (Basel) 2024; 13:791. [PMID: 39061859 PMCID: PMC11274267 DOI: 10.3390/antiox13070791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 06/21/2024] [Accepted: 06/24/2024] [Indexed: 07/28/2024] Open
Abstract
Ovarian cancer (OC), known for its lethality and resistance to chemotherapy, is closely associated with iron metabolism and ferroptosis-an iron-dependent cell death process, distinct from both autophagy and apoptosis. Emerging evidence suggests that dysregulation of iron metabolism could play a crucial role in OC by inducing an imbalance in the redox system, which leads to ferroptosis, offering a novel therapeutic approach. This review examines how disruptions in iron metabolism, which affect redox balance, impact OC progression, focusing on its essential cellular functions and potential as a therapeutic target. It highlights the molecular interplay, including the role of non-coding RNAs (ncRNAs), between iron metabolism and ferroptosis, and explores their interactions with key immune cells such as macrophages and T cells, as well as inflammation within the tumor microenvironment. The review also discusses how glycolysis-related iron metabolism influences ferroptosis via reactive oxygen species. Targeting these pathways, especially through agents that modulate iron metabolism and ferroptosis, presents promising therapeutic prospects. The review emphasizes the need for deeper insights into iron metabolism and ferroptosis within the redox-regulated system to enhance OC therapy and advocates for continued research into these mechanisms as potential strategies to combat OC.
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Affiliation(s)
- Dan Liu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Yangtze University, Jingzhou 434000, China; (D.L.); (Z.H.)
- Hubei Provincial Clinical Research Center for Personalized Diagnosis and Treatment of Cancer, Jingzhou 434000, China
| | - Zewen Hu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Yangtze University, Jingzhou 434000, China; (D.L.); (Z.H.)
- Hubei Provincial Clinical Research Center for Personalized Diagnosis and Treatment of Cancer, Jingzhou 434000, China
| | - Jinzhi Lu
- Hubei Provincial Clinical Research Center for Personalized Diagnosis and Treatment of Cancer, Jingzhou 434000, China
- Department of Laboratory Medicine, The First Affiliated Hospital, Yangtze University, Jingzhou 434000, China
| | - Cunjian Yi
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Yangtze University, Jingzhou 434000, China; (D.L.); (Z.H.)
- Hubei Provincial Clinical Research Center for Personalized Diagnosis and Treatment of Cancer, Jingzhou 434000, China
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3
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Ramavath HN, Chandra Mashurabad P, Yaduvanshi PS, Veleri S, Sharp PA, Pullakhandam R. Zinc induces hephaestin expression via a PI3K-CDX2 dependent mechanism to regulate iron transport in intestinal Caco-2 cells. Biochem Biophys Res Commun 2022; 626:1-7. [DOI: 10.1016/j.bbrc.2022.07.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/11/2022] [Accepted: 07/14/2022] [Indexed: 11/16/2022]
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4
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Arif HM, Qian Z, Wang R. Signaling Integration of Hydrogen Sulfide and Iron on Cellular Functions. Antioxid Redox Signal 2022; 36:275-293. [PMID: 34498949 DOI: 10.1089/ars.2021.0203] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Significance: Hydrogen sulfide (H2S) is an endogenous signaling molecule, regulating numerous physiological functions from vasorelaxation to neuromodulation. Iron is a well-known bioactive metal ion, being the central component of hemoglobin for oxygen transportation and participating in biomolecule degradation, redox balance, and enzymatic actions. The interplay between H2S and iron metabolisms and functions impacts significantly on the fate and wellness of different types of cells. Recent Advances: Iron level in vivo affects the production of H2S via nonenzymatic reactions. On the contrary, H2S quenches excessive iron inside the cells and regulates the redox status of iron. Critical Issues: Abnormal metabolisms of both iron and H2S are associated with various conditions and diseases such as iron overload, anemia, oxidative stress, and cardiovascular and neurodegenerative diseases. The molecular mechanisms for the interactions between H2S and iron are unsettled yet. Here we review signaling links of the production, metabolism, and their respective and integrative functions of H2S and iron in normalcy and diseases. Future Directions: Physiological and pathophysiological importance of H2S and iron as well as their therapeutic applications should be evaluated jointly, not separately. Future investigation should expand from iron-rich cells and tissues to the others, in which H2S and iron interaction has not received due attention. Antioxid. Redox Signal. 36, 275-293.
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Affiliation(s)
| | - Zhongming Qian
- Institute of Translational & Precision Medicine, Nantong University, Nantong, China
| | - Rui Wang
- Department of Biology, York University, Toronto, Canada
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5
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Chen M, Xu E, Zeng C, Zhu W, Zheng J, Chen H. High Dietary Iron Has a Greater Impact on Brain Iron Homeostasis and Cognitive Function in Old Compared with Young C57BL/6J Male Mice. J Nutr 2021; 151:2835-2842. [PMID: 34191031 DOI: 10.1093/jn/nxab189] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 02/25/2021] [Accepted: 05/18/2021] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Brain iron accumulation is a feature of Alzheimer disease (AD) but whether a chronic dietary iron overload contributes to AD induction is unknown. We previously showed that young mice fed a high iron diet did not display cognitive impairment despite the AD pathological markers in hippocampus. OBJECTIVES We aim to compare the impact of high dietary iron on brain pathologic changes and cognitive function in young and old mice. METHODS Male C57BL/6J mice at 1 mo and 13 mo of age were fed with either a control diet (66 mg Fe/kg; Young-Ctrl and Old-Ctrl) or a high iron diet (14 g Fe/kg; Young-High Fe and Old-High Fe) for 7 mo, and outcomes were evaluated at 8 mo and 20 mo of age. Iron concentrations in brain regions were measured by atomic absorption spectrophotometry. Perls's Prussian blue staining and amyloid-β (Aβ) immunostaining were performed. Protein expression in the cerebral cortex and hippocampus was determined by immunoblotting. Superoxide dismutase activity and malondialdehyde concentration were examined. Cognitive functions were tested with the Morris water maze system. Two-factor ANOVA was used to analyze most data. RESULTS Compared with Old-Ctrl mice, Old-High Fe mice showed significantly higher iron concentrations in cerebral cortex (60% higher), cerebellum (60% higher), and hippocampus (90% higher), paralleled by lower superoxide dismutase activity and greater malondialdehyde concentration in cerebral cortex and hippocampus and worse cognitive function. In contrast, these variables did not significantly differ between the 2 young groups. Nevertheless, ferritin, phospho-tau, and Aβ1-42 expression in hippocampus and ferritin and Aβ1-42 expression in cerebral cortex were induced by the high iron diet irrespective of the age of mice (40-200% greater). CONCLUSIONS High dietary iron induced cognitive defects in old mice but not young mice, suggesting that elderly people should avoid consuming abnormally high concentrations of iron.
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Affiliation(s)
- Min Chen
- Clinic for Psychiatry and Psychotherapy, Ludwig-Maximilians-Universität München, München, Germany.,Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - En Xu
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China.,Department of General Surgery, Affiliated Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Chong Zeng
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Wenjie Zhu
- Department of Urology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Institute of Urology, Nanjing University, Nanjing, China
| | - Jiashuo Zheng
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China.,Helmholtz Zentrum München, Institute of Metabolism and Cell Death, Neuherberg, Germany
| | - Huijun Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
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6
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Jiang L, Wang J, Wang K, Wang H, Wu Q, Yang C, Yu Y, Ni P, Zhong Y, Song Z, Xie E, Hu R, Min J, Wang F. RNF217 regulates iron homeostasis through its E3 ubiquitin ligase activity by modulating ferroportin degradation. Blood 2021; 138:689-705. [PMID: 33895792 PMCID: PMC8394904 DOI: 10.1182/blood.2020008986] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 02/24/2021] [Indexed: 12/14/2022] Open
Abstract
Ferroportin (FPN), the body's sole iron exporter, is essential for maintaining systemic iron homeostasis. In response to either increased iron or inflammation, hepatocyte-secreted hepcidin binds to FPN, inducing its internalization and subsequent degradation. However, the E3 ubiquitin ligase that underlies FPN degradation has not been identified. Here, we report the identification and characterization of a novel mechanism involving the RNF217-mediated degradation of FPN. A combination of 2 different E3 screens revealed that the Rnf217 gene is a target of Tet1, mediating the ubiquitination and subsequent degradation of FPN. Interestingly, loss of Tet1 expression causes an accumulation of FPN and an impaired response to iron overload, manifested by increased iron accumulation in the liver together with decreased iron in the spleen and duodenum. Moreover, we found that the degradation and ubiquitination of FPN could be attenuated by mutating RNF217. Finally, using 2 conditional knockout mouse lines, we found that knocking out Rnf217 in macrophages increases splenic iron export by stabilizing FPN, whereas knocking out Rnf217 in intestinal cells appears to increase iron absorption. These findings suggest that the Tet1-RNF217-FPN axis regulates iron homeostasis, revealing new therapeutic targets for FPN-related diseases.
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Affiliation(s)
- Li Jiang
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
- The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
- Department of Nutrition, Precision Nutrition Innovation Center, School of Public Health, Zhengzhou University, Zhengzhou, China; and
| | - Jiaming Wang
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
| | - Kai Wang
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
| | - Hao Wang
- Department of Nutrition, Precision Nutrition Innovation Center, School of Public Health, Zhengzhou University, Zhengzhou, China; and
| | - Qian Wu
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
| | - Cong Yang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Yingying Yu
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
| | - Pu Ni
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
| | - Yueyang Zhong
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
| | - Zijun Song
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
| | - Enjun Xie
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
| | - Ronggui Hu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Junxia Min
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
| | - Fudi Wang
- The First Affiliated Hospital, School of Public Health, Institute of Translational Medicine, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China
- The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
- Department of Nutrition, Precision Nutrition Innovation Center, School of Public Health, Zhengzhou University, Zhengzhou, China; and
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7
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Jończy A, Mazgaj R, Starzyński RR, Poznański P, Szudzik M, Smuda E, Kamyczek M, Lipiński P. Relationship between Down-Regulation of Copper-Related Genes and Decreased Ferroportin Protein Level in the Duodenum of Iron-Deficient Piglets. Nutrients 2020; 13:nu13010104. [PMID: 33396831 PMCID: PMC7823587 DOI: 10.3390/nu13010104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/26/2020] [Accepted: 12/27/2020] [Indexed: 12/14/2022] Open
Abstract
In mammals, 2 × 1012 red blood cells (RBCs) are produced every day in the bone marrow to ensure a constant supply of iron to maintain effective erythropoiesis. Impaired iron absorption in the duodenum and inefficient iron reutilization from senescent RBCs by macrophages contribute to the development of anemia. Ferroportin (Fpn), the only known cellular iron exporter, as well as hephaestin (Heph) and ceruloplasmin, two copper-dependent ferroxidases involved in the above-mentioned processes, are key elements of the interaction between copper and iron metabolisms. Crosslinks between these metals have been known for many years, but metabolic effects of one on the other have not been elucidated to date. Neonatal iron deficiency anemia in piglets provides an interesting model for studying this interplay. In duodenal enterocytes of young anemic piglets, we identified iron deposits and demonstrated increased expression of ferritin with a concomitant decline in both Fpn and Heph expression. We postulated that the underlying mechanism involves changes in copper distribution within enterocytes as a result of decreased expression of the copper transporter—Atp7b. Obtained results strongly suggest that regulation of iron absorption within enterocytes is based on the interaction between proteins of copper and iron metabolisms and outcompetes systemic regulation.
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Affiliation(s)
- Aneta Jończy
- Department of Molecular Biology, Institute of Genetics and Animal Biotechnology, PAS, 05-552 Jastrzębiec, Poland; (R.M.); (R.R.S.); (M.S.); (E.S.)
- Correspondence: (A.J.); (P.L.); Tel.: +48-227-367-058 (A.J.); +48-227-367-046 (P.L.)
| | - Rafał Mazgaj
- Department of Molecular Biology, Institute of Genetics and Animal Biotechnology, PAS, 05-552 Jastrzębiec, Poland; (R.M.); (R.R.S.); (M.S.); (E.S.)
| | - Rafał Radosław Starzyński
- Department of Molecular Biology, Institute of Genetics and Animal Biotechnology, PAS, 05-552 Jastrzębiec, Poland; (R.M.); (R.R.S.); (M.S.); (E.S.)
| | - Piotr Poznański
- Department of Experimental Genomics, Institute of Genetics and Animal Biotechnology, PAS, 05-552 Jastrzębiec, Poland;
| | - Mateusz Szudzik
- Department of Molecular Biology, Institute of Genetics and Animal Biotechnology, PAS, 05-552 Jastrzębiec, Poland; (R.M.); (R.R.S.); (M.S.); (E.S.)
| | - Ewa Smuda
- Department of Molecular Biology, Institute of Genetics and Animal Biotechnology, PAS, 05-552 Jastrzębiec, Poland; (R.M.); (R.R.S.); (M.S.); (E.S.)
| | - Marian Kamyczek
- Pig Hybridization Centre, National Research Institute of Animal Production, 64-122 Pawłowice, Poland;
| | - Paweł Lipiński
- Department of Molecular Biology, Institute of Genetics and Animal Biotechnology, PAS, 05-552 Jastrzębiec, Poland; (R.M.); (R.R.S.); (M.S.); (E.S.)
- Correspondence: (A.J.); (P.L.); Tel.: +48-227-367-058 (A.J.); +48-227-367-046 (P.L.)
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Kondaiah P, Sharp PA, Pullakhandam R. Zinc induces iron egress from intestinal Caco-2 cells via induction of Hephaestin: A role for PI3K in intestinal iron absorption. Biochem Biophys Res Commun 2020; 523:987-992. [DOI: 10.1016/j.bbrc.2020.01.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 01/03/2020] [Indexed: 01/23/2023]
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9
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Chen M, Zheng J, Liu G, Zeng C, Xu E, Zhu W, Anderson GJ, Chen H. High Dietary Iron Disrupts Iron Homeostasis and Induces Amyloid-β and Phospho-τ Expression in the Hippocampus of Adult Wild-Type and APP/PS1 Transgenic Mice. J Nutr 2019; 149:2247-2254. [PMID: 31373375 PMCID: PMC6887700 DOI: 10.1093/jn/nxz168] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/21/2019] [Accepted: 06/25/2019] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Brain iron deposition is a feature of Alzheimer disease and may contribute to its development. However, the relative contribution of dietary iron remains unclear. OBJECTIVES We investigated the impact of high dietary iron on brain pathological changes and cognitive function in adult wild-type (WT) mice and amyloid precursor protein/presenilin 1 (APP/PS1) double transgenic mice. METHODS Male WT mice and APP/PS1 mice aged 10 wk were fed either a control diet (66 mg Fe/kg) (WT-Ctrl and APP/PS1-Ctrl) or a high iron diet (14 g Fe/kg) (WT-High Fe and APP/PS1-High Fe) for 20 wk. Iron concentrations in brain regions were measured by atomic absorption spectrophotometry. Brain iron staining and amyloid-β (Aβ) immunostaining were performed. Protein expressions in the hippocampus were determined by immunoblotting. Superoxide dismutase (SOD) activity and malondialdehyde concentration were examined. Cognitive functions were tested with the Morris water maze system. RESULTS In the hippocampus, APP/PS1-High Fe mice had significantly higher iron concentration (2.5-fold) and ferritin (2.0-fold) than APP/PS1-Ctrl mice (P < 0.001), and WT-High Fe mice had significantly higher ferritin (2.0-fold) than WT-Ctrl mice (P < 0.001). Interestingly, APP/PS1 mice had significantly higher iron concentration (2-3-fold) and ferritin (2-2.5-fold) than WT mice fed either diet (P < 0.001). Histological analysis indicated that iron accumulated in the hippocampal dentate gyrus region in APP/PS1 mice, consistent with the pattern of Aβ deposition. For both mouse strains, iron treatment induced Aβ and phospho-τ expression (1.5-3-fold) in the hippocampus, but had little impact on oxidative stress and cognitive function. Furthermore, APP/PS1 mice had significantly lower SOD activity and higher malondialdehyde concentration than WT mice in the hippocampus (P < 0.0001), paralleled by apparent cognitive dysfunction. CONCLUSIONS Dietary iron overload induces iron disorder and Aβ and phospho-τ expression in the hippocampus of adult WT and APP/PS1 transgenic mice.
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Affiliation(s)
- Min Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China,Address correspondence to HC (e-mail: )
| | - Jiashuo Zheng
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Guohao Liu
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Chong Zeng
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - En Xu
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Wenjie Zhu
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | | | - Huijun Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
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10
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Xu E, Chen M, Zheng J, Maimaitiming Z, Zhong T, Chen H. Deletion of hephaestin and ceruloplasmin induces a serious systemic iron deficiency and disrupts iron homeostasis. Biochem Biophys Res Commun 2018; 503:1905-1910. [PMID: 30060949 DOI: 10.1016/j.bbrc.2018.07.134] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 07/25/2018] [Indexed: 11/24/2022]
Abstract
Multi-copper ferroxidases (MCFs) play important roles in cellular iron metabolism and homeostasis. In this study, we generated the hephaestin (Heph), ceruloplasmin (Cp) single and Heph/Cp double knockout (KO) mice to investigate the roles of MCFs in iron transport among system and vital organs in mice at 4 weeks and 6 months of age. Compared with wild-type (WT) mice, Heph/Cp mice at both ages presented with severe anemia and significantly lower iron level in the serum and spleen, but with significantly higher iron level in the liver, heart, kidney, and duodenal enterocytes. Furthermore, Heph/Cp mice displayed significantly lower level of hepcidin mRNA and transferrin receptor 1 (TFR1) protein expression, but significantly higher level of ferroportin 1 (FPN1) protein expression in the liver than WT mice at 6 months of age. Liver superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzyme activities were significantly lower in Heph/Cp KO mice than WT mice at 6 months of age. Together, our results suggest that ablation of HEPH and CP could lead to severe systemic iron deficiency and local tissue iron overload, which disrupt the whole body iron homeostasis and impact on tissue functions.
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Affiliation(s)
- En Xu
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Min Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Jiashuo Zheng
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Zaitunamu Maimaitiming
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Tianjiao Zhong
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Huijun Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China.
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11
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Nairz M, Dichtl S, Schroll A, Haschka D, Tymoszuk P, Theurl I, Weiss G. Iron and innate antimicrobial immunity-Depriving the pathogen, defending the host. J Trace Elem Med Biol 2018; 48:118-133. [PMID: 29773170 DOI: 10.1016/j.jtemb.2018.03.007] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/25/2018] [Accepted: 03/06/2018] [Indexed: 02/08/2023]
Abstract
The acute-phase response is triggered by the presence of infectious agents and danger signals which indicate hazards for the integrity of the mammalian body. One central feature of this response is the sequestration of iron into storage compartments including macrophages. This limits the availability of this essential nutrient for circulating pathogens, a host defence strategy known as 'nutritional immunity'. Iron metabolism and the immune response are intimately linked. In infections, the availability of iron affects both the efficacy of antimicrobial immune pathways and pathogen proliferation. However, host strategies to withhold iron from microbes vary according to the localization of pathogens: Infections with extracellular bacteria such as Staphylococcus aureus, Streptococcus, Klebsiella or Yersinia stimulate the expression of the iron-regulatory hormone hepcidin which targets the cellular iron-exporter ferroportin-1 causing its internalization and blockade of iron egress from absorptive enterocytes in the duodenum and iron-recycling macrophages. This mechanism disrupts both routes of iron delivery to the circulation, contributes to iron sequestration in the mononuclear phagocyte system and mediates the hypoferraemia of the acute phase response subsequently resulting in the development of anaemia of inflammation. When intracellular microbes are present, other strategies of microbial iron withdrawal are needed. For instance, in macrophages harbouring intracellular pathogens such as Chlamydia, Mycobacterium tuberculosis, Listeria monocytogenes or Salmonella Typhimurium, ferroportin-1-mediated iron export is turned on for the removal of iron from infected cells. This also leads to reduced iron availability for intra-macrophage pathogens which inhibits their growth and in parallel strengthens anti-microbial effector pathways of macrophages including the formation of inducible nitric oxide synthase and tumour necrosis factor. Iron plays a key role in infectious diseases both as modulator of the innate immune response and as nutrient for microbes. We need to gain a more comprehensive understanding of how the body can differentially respond to infection by extra- or intracellular pathogens. This knowledge may allow us to modulate mammalian iron homeostasis pharmaceutically and to target iron-acquisition systems of pathogens, thus enabling us to treat infections with novel strategies that act independent of established antimicrobials.
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Affiliation(s)
- Manfred Nairz
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria.
| | - Stefanie Dichtl
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
| | - Andrea Schroll
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
| | - David Haschka
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
| | - Piotr Tymoszuk
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
| | - Igor Theurl
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
| | - Günter Weiss
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
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Chen M, Zheng J, Liu G, Xu E, Wang J, Fuqua BK, Vulpe CD, Anderson GJ, Chen H. Ceruloplasmin and hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux. Redox Biol 2018; 17:432-439. [PMID: 29883959 PMCID: PMC6007082 DOI: 10.1016/j.redox.2018.05.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 05/23/2018] [Accepted: 05/28/2018] [Indexed: 02/07/2023] Open
Abstract
Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls’ Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage.
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Affiliation(s)
- Min Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Jiashuo Zheng
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Guohao Liu
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - En Xu
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Junzhuo Wang
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Brie K Fuqua
- Center for Environmental and Human Toxicology, Department of Physiological Sciences, University of Florida, Gainesville, FL, USA
| | - Chris D Vulpe
- Center for Environmental and Human Toxicology, Department of Physiological Sciences, University of Florida, Gainesville, FL, USA
| | - Gregory J Anderson
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Huijun Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China.
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13
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Zheng J, Jiang R, Chen M, Maimaitiming Z, Wang J, Anderson GJ, Vulpe CD, Dunaief JL, Chen H. Multi-Copper Ferroxidase-Deficient Mice Have Increased Brain Iron Concentrations and Learning and Memory Deficits. J Nutr 2018; 148:643-649. [PMID: 29659961 DOI: 10.1093/jn/nxy012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 01/11/2018] [Indexed: 11/12/2022] Open
Abstract
Background The accumulation of iron occurs in the central nervous system (CNS) in several neurodegenerative diseases. Although multi-copper ferroxidases (MCFs) play an important role in cellular iron metabolism and homeostasis, the mechanism of MCFs in the CNS remains unclear. Objective The aim was to study the role of MCFs in CNS iron metabolism and homeostasis by using hephaestin/ceruloplasmin (Heph/Cp) double knockout (KO) mice. Methods Heph/Cp double KO male mice were generated by crossing both single KO mice. In Heph/Cp KO and wild-type (WT) control mice at 4 wk and 6 mo of age, iron concentrations of selected brain regions were measured by atomic absorption spectrophotometry, and gene expressions of Heph, Cp, ferroportin 1 (Fpn1) [+ iron responsive element (IRE)], L-ferritin, H-ferritin, transferrin receptor 1 (Tfrc), and divalent metal transporter 1 (Dmt1) (+IRE) were quantitated by quantitative reverse transcriptase-polymerase chain reaction. Brain region L-ferritin protein concentration, superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities and malondialdehyde (MDA) concentration were also determined. Learning and memory abilities in Heph/Cp KO and WT control mice at 6 mo of age were tested by the IntelliCage system (New Behavior). Results Iron concentration was significantly higher in Heph/Cp KO mice than in WT control mice at 4 wk of age in the cortex (50%), hippocampus (120%), brainstem (35%), and cerebellum (220%) and at 6 mo of age in the cortex (140%), hippocampus (420%), brainstem (560%), and cerebellum (340%). L-Ferritin and MDA concentrations were significantly higher and SOD and GPx activities were significantly lower in the cortex, hippocampus, brainstem, and cerebellum of KO mice than in those of WT controls at both 4 wk and 6 mo of age. Iron-related gene expressions also differed significantly between groups. Learning and memory deficits occurred in Heph/Cp KO mice at 6 mo of age. Conclusion Mutation of both MCFs in mice induces iron accumulation in brain regions, oxidative damage, and learning and memory defects.
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Affiliation(s)
- Jiashuo Zheng
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Ruiwei Jiang
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Min Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Zaitunamu Maimaitiming
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Junzhuo Wang
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Gregory J Anderson
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Chris D Vulpe
- Center for Environmental and Human Toxicology, Department of Physiological Sciences, University of Florida, Gainesville, FL
| | - Joshua L Dunaief
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, PA
| | - Huijun Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
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Zheng J, Chen M, Liu G, Xu E, Chen H. Ablation of hephaestin and ceruloplasmin results in iron accumulation in adipocytes and type 2 diabetes. FEBS Lett 2018; 592:394-401. [PMID: 29355933 DOI: 10.1002/1873-3468.12978] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 10/22/2017] [Accepted: 01/15/2018] [Indexed: 01/09/2023]
Abstract
Little is known about the iron efflux mechanism in adipocytes. Here, we used hephaestin (Heph) and ceruloplasmin (Cp) single-knockout (KO) mice and Heph/Cp double-KO mice to investigate the roles of multicopper ferroxidases (MCFs) in this process. We show that both HEPH and CP are expressed in subcutaneous adipose tissue. Ablation of either MCF leads to a compensatory increase in the other, which contributes to the balance of iron status. However, ablation of both MCFs together induces severe iron deposition in adipocytes which is associated with decreased adiponectin and leptin mRNA expression. Furthermore, Heph/Cp KO mice display disordered carbohydrate metabolism characterized as type 2 diabetes. Together, these results demonstrate the protective roles of HEPH and CP in preventing iron overload in adipocytes.
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Affiliation(s)
- Jiashuo Zheng
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Min Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Guohao Liu
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - En Xu
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
| | - Huijun Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, China
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15
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Organ-specific regulation of ATP7A abundance is coordinated with systemic copper homeostasis. Sci Rep 2017; 7:12001. [PMID: 28931909 PMCID: PMC5607234 DOI: 10.1038/s41598-017-11961-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 09/01/2017] [Indexed: 01/31/2023] Open
Abstract
Copper (Cu) is an essential cofactor for various enzymatic activities including mitochondrial electron transport, iron mobilization, and peptide hormone maturation. Consequently, Cu dysregulation is associated with fatal neonatal disease, liver and cardiac dysfunction, and anemia. While the Cu transporter ATP7A plays a major role in both intestinal Cu mobilization to the periphery and prevention of Cu over-accumulation, it is unclear how regulation of ATP7A contributes to Cu homeostasis in response to systemic Cu fluctuation. Here we show, using Cu-deficient mouse models, that steady-state levels of ATP7A are lower in peripheral tissues (including the heart, spleen, and liver) under Cu deficiency and that subcutaneous administration of Cu to these animals restore normal ATP7A levels in these tissues. Strikingly, ATP7A in the intestine is regulated in the opposite manner - low systemic Cu increases ATP7A while subcutaneous Cu administration decreases ATP7A suggesting that intestine-specific non-autonomous regulation of ATP7A abundance may serve as a key homeostatic control for Cu export into the circulation. Our results support a systemic model for how a single transporter can be inversely regulated in a tissue-specific manner to maintain organismal Cu homeostasis.
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16
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Nairz M, Theurl I, Swirski FK, Weiss G. "Pumping iron"-how macrophages handle iron at the systemic, microenvironmental, and cellular levels. Pflugers Arch 2017; 469:397-418. [PMID: 28251312 PMCID: PMC5362662 DOI: 10.1007/s00424-017-1944-8] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/25/2017] [Accepted: 01/29/2017] [Indexed: 12/12/2022]
Abstract
Macrophages reside in virtually every organ. First arising during embryogenesis, macrophages replenish themselves in the adult through a combination of self-renewal and influx of bone marrow-derived monocytes. As large phagocytic cells, macrophages participate in innate immunity while contributing to tissue-specific homeostatic functions. Among the key metabolic tasks are senescent red blood cell recycling, free heme detoxification, and provision of iron for de novo hemoglobin synthesis. While this systemic mechanism involves the shuttling of iron between spleen, liver, and bone marrow through the concerted function of defined macrophage populations, similar circuits appear to exist within the microenvironment of other organs. The high turnover of iron is the prerequisite for continuous erythropoiesis and tissue integrity but challenges macrophages’ ability to maintain cellular iron homeostasis and immune function. This review provides a brief overview of systemic, microenvironmental, and cellular aspects of macrophage iron handling with a focus on exciting and unresolved questions in the field.
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Affiliation(s)
- Manfred Nairz
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Anichstr. 35, 6020, Innsbruck, Austria. .,Center for Systems Biology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA. .,Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Igor Theurl
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Anichstr. 35, 6020, Innsbruck, Austria
| | - Filip K Swirski
- Center for Systems Biology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.,Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Guenter Weiss
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Anichstr. 35, 6020, Innsbruck, Austria.
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Hephaestin and ceruloplasmin facilitate iron metabolism in the mouse kidney. Sci Rep 2016; 6:39470. [PMID: 27991585 PMCID: PMC5171654 DOI: 10.1038/srep39470] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 11/21/2016] [Indexed: 12/12/2022] Open
Abstract
Multicopper ferroxidases (MCFs) play an important role in cellular iron homeostasis. However, the role of MCFs in renal metabolism remains unclear. We used Hephaestin (Heph) and Ceruloplasmin (Cp) single or double (Heph/Cp) knockout (KO) mice to study the roles of MCFs in the kidney. Renal iron levels and the expression of iron metabolism genes were examined. The non-heme iron content both in the renal cortex and medulla of Heph/Cp KO mice was significantly increased. Perls' Prussian blue staining showed iron accumulation on the apical side of renal tubular cells in Heph/Cp KO mice. A significant increase in ferritin protein expression was also observed in the renal medulla and cortex of Heph/Cp KO mice. Both DMT1 and TfR1 protein expression were significantly decreased in the renal medulla of Heph/Cp KO mice, while the expression of DMT1 protein was significantly increased in the renal cortex of these animals. Significant increase in proteinuria and total urinary iron was observed in the double knockout mice, and this was associated with compromised structural integrity. These results suggest that KO of both the HEPH and CP genes leads to kidney iron deposition and toxicity, MCFs could protect kidney against a damage from iron excess.
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18
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Britton L, Jaskowski L, Bridle K, Santrampurwala N, Reiling J, Musgrave N, Subramaniam VN, Crawford D. Heterozygous Hfe gene deletion leads to impaired glucose homeostasis, but not liver injury in mice fed a high-calorie diet. Physiol Rep 2016; 4:4/12/e12837. [PMID: 27354540 PMCID: PMC4923236 DOI: 10.14814/phy2.12837] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 05/26/2016] [Indexed: 12/30/2022] Open
Abstract
Heterozygous mutations of the Hfe gene have been proposed as cofactors in the development and progression of nonalcoholic fatty liver disease (NAFLD). Homozygous Hfe deletion previously has been shown to lead to dysregulated hepatic lipid metabolism and accentuated liver injury in a dietary mouse model of NAFLD. We sought to establish whether heterozygous deletion of Hfe is sufficient to promote liver injury when mice are exposed to a high‐calorie diet (HCD). Eight‐week‐old wild‐type and Hfe+/− mice received 8 weeks of a control diet or HCD. Liver histology and pathways of lipid and iron metabolism were analyzed. Liver histology demonstrated that mice fed a HCD had increased NAFLD activity score (NAS), steatosis, and hepatocyte ballooning. However, liver injury was unaffected by Hfe genotype. Hepatic iron concentration (HIC) was increased in Hfe+/− mice of both dietary groups. HCD resulted in a hepcidin‐independent reduction in HIC. Hfe+/− mice demonstrated raised fasting serum glucose concentrations and HOMA‐IR score, despite unaltered serum adiponectin concentrations. Downstream regulators of hepatic de novo lipogenesis (pAKT, SREBP‐1, Fas, Scd1) and fatty acid oxidation (AdipoR2, Pparα, Cpt1) were largely unaffected by genotype. In summary, heterozygous Hfe gene deletion is associated with impaired iron and glucose metabolism. However, unlike homozygous Hfe deletion, heterozygous gene deletion did not affect lipid metabolism pathways or liver injury in this model.
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Affiliation(s)
- Laurence Britton
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia The Department of Gastroenterology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Lesley Jaskowski
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Kim Bridle
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia
| | - Nishreen Santrampurwala
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Janske Reiling
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia Department of Surgery, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Nick Musgrave
- Sullivan and Nicolaides Pathology, Greenslopes Private Hospital, Greenslopes, Queensland, Australia
| | | | - Darrell Crawford
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia
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Beard J, deRegnier RA, Shaw MD, Rao R, Georgieff M. Diagnosis of Iron Deficiency in Infants. Lab Med 2015. [DOI: 10.1309/7kj11rx758uklxxm] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Abstract
Iron-deficient individuals experience a loss of appetite that can be restored with iron supplementation. It has been proposed that iron influences the satiety hormone leptin; however, a direct link between iron and leptin has remained elusive. In this issue of the JCI, Gao and colleagues demonstrate an inverse relationship between adipocyte iron and leptin that is mediated by iron-dependent activation of cAMP-responsive element binding protein (CREB), the transcription factor that represses leptin transcription. Together, the results of this study provide a mechanistic connection between dietary iron and the appetite-regulating hormone leptin.
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21
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Jiang R, Hua C, Wan Y, Jiang B, Hu H, Zheng J, Fuqua BK, Dunaief JL, Anderson GJ, David S, Vulpe CD, Chen H. Hephaestin and ceruloplasmin play distinct but interrelated roles in iron homeostasis in mouse brain. J Nutr 2015; 145:1003-9. [PMID: 25788583 DOI: 10.3945/jn.114.207316] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 02/18/2015] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Iron accumulation in the central nervous system (CNS) is a common feature of many neurodegenerative diseases. Multicopper ferroxidases (MCFs) play an important role in cellular iron metabolism. However, the role of MCFs in the CNS in health and disease remains poorly characterized. OBJECTIVE The aim was to study the role of hephaestin (HEPH) and ceruloplasmin (CP) in CNS iron metabolism and homeostasis. METHODS Iron concentrations and L-ferritin protein levels of selected brain regions were determined in global hephaestin knockout (Heph KO), global ceruloplasmin knockout (Cp KO), and wild-type (WT) male mice at 6-7 mo of age. Gene expression of divalent metal transporter 1 (Dmt1), ferroportin 1 (Fpn1), Heph, Cp, and transferrin receptor 1 (Tfrc) and HEPH protein level was quantitated in the same brain regions. RESULTS Iron and L-ferritin protein levels were significantly increased in Heph KO mouse brain cortex (iron: 30%, P < 0.05; L-ferritin: 200%, P < 0.05), hippocampus (iron: 80%, P < 0.05; L-ferritin: 300%, P < 0.05), brainstem (iron: 20%, P < 0.05; L-ferritin: 150%, P < 0.05), and cerebellum (iron: 20%, P < 0.05; L-ferritin: 100%, P < 0.05) regions than in WT and Cp KO mouse brain regions at 6 mo of age. Expression of the Heph gene was significantly increased in the Cp KO mouse cortex (100%; P < 0.01), hippocampus (350%; P < 0.001), brainstem (30%; P < 0.01), and cerebellum (150%; P < 0.001) than in WT controls, and Cp gene expression was significantly decreased in the Heph KO mouse hippocampus (20%; P < 0.05) than in WT control mice at 6 mo of age. CONCLUSIONS Ablation of HEPH or CP results in disordered brain iron homeostasis in mice. Heph KO may provide a novel model for neurodegenerative disorders.
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Affiliation(s)
- Ruiwei Jiang
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Chao Hua
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Yike Wan
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Bo Jiang
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Huiyin Hu
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Jiashuo Zheng
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Brie K Fuqua
- Department of Nutritional Science and Toxicology, University of California, Berkeley, CA; Berghofer Medical Research Institute, Brisbane, Australia
| | - Joshua L Dunaief
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA; and
| | | | - Samuel David
- Center for Research in Neuroscience, The Research Institute of the McGill University Health Center, Montreal, Canada
| | - Chris D Vulpe
- Department of Nutritional Science and Toxicology, University of California, Berkeley, CA
| | - Huijun Chen
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China;
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Aslam MF, Frazer DM, Faria N, Bruggraber SFA, Wilkins SJ, Mirciov C, Powell JJ, Anderson GJ, Pereira DIA. Ferroportin mediates the intestinal absorption of iron from a nanoparticulate ferritin core mimetic in mice. FASEB J 2014; 28:3671-8. [PMID: 24776745 PMCID: PMC4101650 DOI: 10.1096/fj.14-251520] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 04/21/2014] [Indexed: 12/21/2022]
Abstract
The ferritin core is composed of fine nanoparticulate Fe(3+) oxohydroxide, and we have developed a synthetic mimetic, nanoparticulate Fe(3+) polyoxohydroxide (nanoFe(3+)). The aim of this study was to determine how dietary iron derived in this fashion is absorbed in the duodenum. Following a 4 wk run-in on an Fe-deficient diet, mice with intestinal-specific disruption of the Fpn-1 gene (Fpn-KO), or littermate wild-type (WT) controls, were supplemented with Fe(2+) sulfate (FeSO4), nanoFe(3+), or no added Fe for a further 4 wk. A control group was Fe sufficient throughout. Direct intestinal absorption of nanoFe(3+) was investigated using isolated duodenal loops. Our data show that FeSO4 and nanoFe(3+) are equally bioavailable in WT mice, and at wk 8 the mean ± SEM hemoglobin increase was 18 ± 7 g/L in the FeSO4 group and 30 ± 5 g/L in the nanoFe(3+) group. Oral iron failed to be utilized by Fpn-KO mice and was retained in enterocytes, irrespective of the iron source. In summary, although nanoFe(3+) is taken up directly by the duodenum its homeostasis is under the normal regulatory control of dietary iron absorption, namely via ferroportin-dependent efflux from enterocytes, and thus offers potential as a novel oral iron supplement.
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Affiliation(s)
- Mohamad F Aslam
- Medical Research Council Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, UK
| | - David M Frazer
- Iron Metabolism Laboratory, Queensland Institute of Medical Research Berghofer Medical Research Institute, Brisbane, Queensland, Australia; and
| | - Nuno Faria
- Medical Research Council Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, UK
| | - Sylvaine F A Bruggraber
- Medical Research Council Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, UK
| | - Sarah J Wilkins
- Iron Metabolism Laboratory, Queensland Institute of Medical Research Berghofer Medical Research Institute, Brisbane, Queensland, Australia; and
| | - Cornel Mirciov
- Iron Metabolism Laboratory, Queensland Institute of Medical Research Berghofer Medical Research Institute, Brisbane, Queensland, Australia; and
| | - Jonathan J Powell
- Medical Research Council Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, UK
| | - Greg J Anderson
- Iron Metabolism Laboratory, Queensland Institute of Medical Research Berghofer Medical Research Institute, Brisbane, Queensland, Australia; and School of Chemistry and Molecular Bioscience and School of Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - Dora I A Pereira
- Medical Research Council Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, UK;
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23
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The multicopper ferroxidase hephaestin enhances intestinal iron absorption in mice. PLoS One 2014; 9:e98792. [PMID: 24896847 PMCID: PMC4045767 DOI: 10.1371/journal.pone.0098792] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 05/06/2014] [Indexed: 12/31/2022] Open
Abstract
Hephaestin is a vertebrate multicopper ferroxidase important for the transfer of dietary iron from intestinal cells to the blood. Hephaestin is mutated in the sex-linked anemia mouse, resulting in iron deficiency. However, sex-linked anemia mice still retain some hephaestin ferroxidase activity. They survive, breed, and their anemia improves with age. To gain a better understanding of the role of hephaestin in iron homeostasis, we used the Cre-lox system to generate knockout mouse models with whole body or intestine-specific (Villin promoter) ablation of hephaestin. Both types of mice were viable, indicating that hephaestin is not essential and that other mechanisms, multicopper ferroxidase-dependent or not, must compensate for hephaestin deficiency. The knockout strains, however, both developed a microcytic, hypochromic anemia, suggesting severe iron deficiency and confirming that hephaestin plays an important role in body iron acquisition. Consistent with this, the knockout mice accumulated iron in duodenal enterocytes and had reduced intestinal iron absorption. In addition, the similarities of the phenotypes of the whole body and intestine-specific hephaestin knockout mice clarify the important role of hephaestin specifically in intestinal enterocytes in maintaining whole body iron homeostasis. These mouse models will serve as valuable tools to study the role of hephaestin and associated proteins in iron transport in the small intestine and other tissues.
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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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25
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Ngueta G. Racial disparities in children's blood lead levels: possible implication of divalent metal transporter 1. Med Hypotheses 2014; 82:71-3. [PMID: 24290248 DOI: 10.1016/j.mehy.2013.11.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Accepted: 11/06/2013] [Indexed: 02/02/2023]
Abstract
Adverse effects of lead exposure at low-dose (<10 μg/dL) in children showed a growing interest over the last decades. Black ethnicity is usually associated with elevated blood lead levels (BLLs), independently of age and socioeconomic conditions. The gastrointestinal uptake of lead represents a key step in the process of lead kinetic and toxicity. The involvement of divalent metal transporter 1 (DMT1) in the lead absorption has been previously presumed and reported. I postulate that inter-ethnic differences in DMT1 expression may explain a large part of the racial disparity in children's BLLs, and suggest a few analyses to test this hypothesis. The hypothesis rests on some observations from previous researches. The inverse association between BLLs and iron intake has been reported in both cross-sectional and follow-up studies. It appears that no study specifically addressed the modifying effect of ethnicity in this association. Previous reports suggest that DMT1 is the primary mechanism for gastrointestinal iron absorption. There are four forms of DMT1 expressed in the enterocytes, which did not respond similarly to iron changes. It is not excluded that some children be more likely to uptake ingested lead depending on DMT1 isoform expressed. I hypothesize that the expression of the more active DMT1 isoform (+1A/+IRE) is more common in Non-Hispanic Black compared with Non-Hispanic White children, and I suggest how to test this hypothesis. If the hypothesis is confirmed, this would suggest that the prevention of iron-deficiency must be included in the primary programs for preventing increase of BLLs in Non-Hispanic Black children, rather than as part of secondary prevention. Moreover, thorough studies would be useful to characterize the interaction between environmental lead levels and DMT1 expression in relation to BLLs in young children.
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Affiliation(s)
- Gerard Ngueta
- Population Health and Optimal Health Practices Research Unit, CHUQ Research Center, Laval University, Quebec, Canada.
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Jahanshad N, Rajagopalan P, Thompson PM. Neuroimaging, nutrition, and iron-related genes. Cell Mol Life Sci 2013; 70:4449-61. [PMID: 23817740 PMCID: PMC3827893 DOI: 10.1007/s00018-013-1369-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 04/23/2013] [Accepted: 05/13/2013] [Indexed: 02/08/2023]
Abstract
Several dietary factors and their genetic modifiers play a role in neurological disease and affect the human brain. The structural and functional integrity of the living brain can be assessed using neuroimaging, enabling large-scale epidemiological studies to identify factors that help or harm the brain. Iron is one nutritional factor that comes entirely from our diet, and its storage and transport in the body are under strong genetic control. In this review, we discuss how neuroimaging can help to identify associations between brain integrity, genetic variations, and dietary factors such as iron. We also review iron's essential role in cognition, and we note some challenges and confounds involved in interpreting links between diet and brain health. Finally, we outline some recent discoveries regarding the genetics of iron and its effects on the brain, suggesting the promise of neuroimaging in revealing how dietary factors affect the brain.
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Affiliation(s)
- Neda Jahanshad
- Imaging Genetics Center, Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Neuroscience Research Building 225E, 635 Charles Young Drive, Los Angeles, CA 90095-1769 USA
| | - Priya Rajagopalan
- Imaging Genetics Center, Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Neuroscience Research Building 225E, 635 Charles Young Drive, Los Angeles, CA 90095-1769 USA
| | - Paul M. Thompson
- Imaging Genetics Center, Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Neuroscience Research Building 225E, 635 Charles Young Drive, Los Angeles, CA 90095-1769 USA
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27
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Multi-copper oxidases and human iron metabolism. Nutrients 2013; 5:2289-313. [PMID: 23807651 PMCID: PMC3738974 DOI: 10.3390/nu5072289] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/29/2013] [Accepted: 06/06/2013] [Indexed: 01/13/2023] Open
Abstract
Multi-copper oxidases (MCOs) are a small group of enzymes that oxidize their substrate with the concomitant reduction of dioxygen to two water molecules. Generally, multi-copper oxidases are promiscuous with regards to their reducing substrates and are capable of performing various functions in different species. To date, three multi-copper oxidases have been detected in humans—ceruloplasmin, hephaestin and zyklopen. Each of these enzymes has a high specificity towards iron with the resulting ferroxidase activity being associated with ferroportin, the only known iron exporter protein in humans. Ferroportin exports iron as Fe2+, but transferrin, the major iron transporter protein of blood, can bind only Fe3+ effectively. Iron oxidation in enterocytes is mediated mainly by hephaestin thus allowing dietary iron to enter the bloodstream. Zyklopen is involved in iron efflux from placental trophoblasts during iron transfer from mother to fetus. Release of iron from the liver relies on ferroportin and the ferroxidase activity of ceruloplasmin which is found in blood in a soluble form. Ceruloplasmin, hephaestin and zyklopen show distinctive expression patterns and have unique mechanisms for regulating their expression. These features of human multi-copper ferroxidases can serve as a basis for the precise control of iron efflux in different tissues. In this manuscript, we review the biochemical and biological properties of the three human MCOs and discuss their potential roles in human iron homeostasis.
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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] [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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29
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Kwong RWM, Hamilton CD, Niyogi S. Effects of elevated dietary iron on the gastrointestinal expression of Nramp genes and iron homeostasis in rainbow trout (Oncorhynchus mykiss). FISH PHYSIOLOGY AND BIOCHEMISTRY 2013; 39:363-372. [PMID: 22893023 DOI: 10.1007/s10695-012-9705-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 08/06/2012] [Indexed: 06/01/2023]
Abstract
Diet is the primary source of iron (Fe) for freshwater fish, and the absorption of Fe is believed to occur via the Nramp family of divalent metal transporters (also called DMT1). Presently, the homeostatic regulation of dietary Fe absorption in fish is poorly understood. This study examined the gastrointestinal mRNA expression of two Nramp isoforms, Nramp-β and Nramp-γ, in the freshwater rainbow trout (Oncorhynchus mykiss), following exposure to elevated dietary Fe [1,256 mg Fe/kg food vs. 136 mg Fe/kg food (control)] for 14 days. The physiological performance, plasma Fe status and tissue-specific accumulation of Fe were also evaluated. In general, the mRNA expression level of Nramp was higher in the intestine relative to the stomach. Interestingly, fish fed on a high-Fe diet exhibited a significant induction in Nramp expression after 7 days, followed by a decrease to the level observed in control fish on day 14. The increase in Nramp expression correlated with the elevated gastrointestinal and plasma Fe concentrations. However, the hepatic Fe concentration remained unchanged during the entire exposure period, indicating strong homeostatic regulation of hepatic Fe level in fish. Fish appeared to handle increased systemic Fe level by elevating the plasma transferrin level, thereby enhancing the Fe-binding capacity in the plasma. Overall, our study provides new interesting insights into the homeostatic regulation of dietary Fe uptake and handling in freshwater fish.
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Affiliation(s)
- Raymond W M Kwong
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada
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30
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Matak P, Zumerle S, Mastrogiannaki M, El Balkhi S, Delga S, Mathieu JRR, Canonne-Hergaux F, Poupon J, Sharp PA, Vaulont S, Peyssonnaux C. Copper deficiency leads to anemia, duodenal hypoxia, upregulation of HIF-2α and altered expression of iron absorption genes in mice. PLoS One 2013; 8:e59538. [PMID: 23555700 PMCID: PMC3610650 DOI: 10.1371/journal.pone.0059538] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 02/15/2013] [Indexed: 01/25/2023] Open
Abstract
Iron and copper are essential trace metals, actively absorbed from the proximal gut in a regulated fashion. Depletion of either metal can lead to anemia. In the gut, copper deficiency can affect iron absorption through modulating the activity of hephaestin - a multi-copper oxidase required for optimal iron export from enterocytes. How systemic copper status regulates iron absorption is unknown. Mice were subjected to a nutritional copper deficiency-induced anemia regime from birth and injected with copper sulphate intraperitoneally to correct the anemia. Copper deficiency resulted in anemia, increased duodenal hypoxia and Hypoxia inducible factor 2α (HIF-2α) levels, a regulator of iron absorption. HIF-2α upregulation in copper deficiency appeared to be independent of duodenal iron or copper levels and correlated with the expression of iron transporters (Ferroportin - Fpn, Divalent Metal transporter - Dmt1) and ferric reductase - Dcytb. Alleviation of copper-dependent anemia with intraperitoneal copper injection resulted in down regulation of HIF-2α-regulated iron absorption genes in the gut. Our work identifies HIF-2α as an important regulator of iron transport machinery in copper deficiency.
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Affiliation(s)
- Pavle Matak
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
- Department of Pharmacology and Cancer Biology, Duke University, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Sara Zumerle
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Maria Mastrogiannaki
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | | | - Stephanie Delga
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Jacques R. R. Mathieu
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - François Canonne-Hergaux
- INSERM U1043-CPTP, Toulouse, France
- CNRS, U5282, Toulouse, France
- Université de Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France
| | - Joel Poupon
- Laboratoire de Toxicologie Biologique, Hôpital Lariboisière, Paris, France
| | - Paul A. Sharp
- King’s College London, Diabetes & Nutritional Sciences Division, London, United Kingdom
| | - Sophie Vaulont
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Carole Peyssonnaux
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
- * E-mail:
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31
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Galy B, Ferring-Appel D, Becker C, Gretz N, Gröne HJ, Schümann K, Hentze MW. Iron regulatory proteins control a mucosal block to intestinal iron absorption. Cell Rep 2013; 3:844-57. [PMID: 23523353 DOI: 10.1016/j.celrep.2013.02.026] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 02/11/2013] [Accepted: 02/22/2013] [Indexed: 12/21/2022] Open
Abstract
Mammalian iron metabolism is regulated systemically by the hormone hepcidin and cellularly by iron regulatory proteins (IRPs) that orchestrate a posttranscriptional regulatory network. Through ligand-inducible genetic ablation of both IRPs in the gut epithelium of adult mice, we demonstrate that IRP deficiency impairs iron absorption and promotes mucosal iron retention via a ferritin-mediated "mucosal block." We show that IRP deficiency does not interfere with intestinal sensing of body iron loading and erythropoietic iron need, but rather alters the basal expression of the iron-absorption machinery. IRPs thus secure sufficient iron transport across absorptive enterocytes by restricting the ferritin "mucosal block" and define a basal set point for iron absorption upon which IRP-independent systemic regulatory inputs are overlaid.
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Affiliation(s)
- Bruno Galy
- European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg 69117, Germany.
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32
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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] [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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Copper deficiency has minimal impact on ferroportin expression or function. Biometals 2012; 25:633-42. [PMID: 22294464 DOI: 10.1007/s10534-012-9521-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 01/07/2012] [Indexed: 02/08/2023]
Abstract
Interactions between copper and iron homeostasis have been known since the nineteenth century when anemia in humans was first described due to copper limitation. However, the mechanism remains unknown. Intestinal and liver iron concentrations are usually higher following copper deficiency (CuD). This may be due to impaired function of the multicopper oxidases hephaestin or ceruloplasmin (Cp), respectively. However, iron retention could be due to altered ferroportin (Fpn), the essential iron efflux transporter in enterocytes and macrophages. Fpn mRNA is controlled partially by intracellular iron and IRE dependence. CuD should augment Fpn based on iron level. Some argue that Fpn stability is controlled partially by membrane ferroxidase (GPI-Cp). CuD should result in lower Fpn since GPI-Cp expression and function is reduced. Fpn turnover is controlled by hepcidin. CuD results in variable Hamp (hepcidin) expression. Fpn mRNA and protein level were evaluated following dietary CuD in rats and mice. To correlate with Fpn expression, measurements of tissue iron were conducted in several rodent models. Following CuD there was little change in Fpn mRNA. Previous work indicated that under certain circumstances Fpn protein was augmented in liver and spleen following CuD. Fpn levels in CuD did not correlate with either total iron or non-heme iron (NHI), as iron levels in CuD liver were higher and in spleen lower than copper adequate controls. Fpn steady state levels appear to be regulated by a complex set of factors. Changes in Fpn do not explain the anemia of CuD.
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Iron repletion relocalizes hephaestin to a proximal basolateral compartment in polarized MDCK and Caco2 cells. Biochem Biophys Res Commun 2012; 421:449-55. [PMID: 22503983 DOI: 10.1016/j.bbrc.2012.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 04/01/2012] [Indexed: 01/07/2023]
Abstract
While intestinal cellular iron entry in vertebrates employs multiple routes including heme and non-heme routes, iron egress from these cells is exclusively channeled through the only known transporter, ferroportin. Reduced intestinal iron export in sex-linked anemia mice implicates hephaestin, a ferroxidase, in this process. Polarized cells are exposed to two distinct environments. Enterocytes contact the gut lumen via the apical surface of the cell, and through the basolateral surface, to the body. Previous studies indicate both local and systemic control of iron uptake. We hypothesized that differences in iron availability at the apical and/or basolateral surface may modulate iron uptake via cellular localization of hephaestin. We therefore characterized the localization of hephaestin in two models of polarized epithelial cell lines, MDCK and Caco2, with varying iron availability at the apical and basolateral surfaces. Our results indicate that hephaestin is expressed in a supra-nuclear compartment in non-polarized cells regardless of the iron status of the cells and in iron deficient and polarized cells. In polarized cells, we found that both apical (as FeSO(4)) and basolateral iron (as the ratio of apo-transferrin to holo-transferrin) affect mobilization of hephaestin from the supra-nuclear compartment. We find that the presence of apical iron is essential for relocalization of hephaestin to a cellular compartment in close proximity but not overlapping with the basolateral surface. Surface biotinylation studies indicate that hephaestin in the peri-basolateral location is accessible to the extra-cellular environment. These results support the hypothesis that hephaestin is involved in iron mobilization of iron from the intestine to circulation.
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35
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Chen C, Sibley E. Expression profiling identifies novel gene targets and functions for Pdx1 in the duodenum of mature mice. Am J Physiol Gastrointest Liver Physiol 2012; 302:G407-19. [PMID: 22135308 PMCID: PMC3287393 DOI: 10.1152/ajpgi.00314.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 11/28/2011] [Indexed: 01/31/2023]
Abstract
Transcription factor pancreatic and duodenal homeobox 1 (Pdx1) plays an essential role in the pancreas to regulate its development and maintain proper islet function. However, the functions of Pdx1 in mature small intestine are less known. We aimed to investigate the intestinal role of Pdx1 by profiling the expression of genes differentially regulated in response to inactivation of Pdx1 specifically in the intestinal epithelium. Pdx1 was conditionally inactivated in the intestinal epithelium of Pdx1(flox/flox);VilCre mice. Total RNA was isolated from the first 5 cm of the small intestine from mature Pdx1(flox/flox);VilCre and littermate control mice. Microarray analysis identified 86 probe sets representing 68 genes significantly upregulated or downregulated 1.5-fold or greater in Pdx(flox/flox);VilCre mice maintained under standard conditions. Ingenuity Pathway Analysis revealed that functions of the differentially expressed genes are significantly associated with metabolism of nutrients including lipids and iron. Network analysis examining the interactions among the differentially expressed genes further supports the notion that Pdx1 may modulate metabolism of lipids and iron from mature intestinal epithelium. Following forced oil feeding, Pdx1(flox/flox);VilCre mice showed diminished lipid staining in the duodenal epithelium and decreased serum triglyceride levels, indicating reduced lipid absorption compared with control duodenal epithelium. Blood samples from Pdx1(flox/flox);VilCre mice have significantly lower mean values for mean corpuscular volume and mean corpuscular hemoglobin, consistent with iron deficiency. The absence of nonheme iron in the villous epithelium and lamina propria of Pdx1(flox/flox);VilCre duodenum indicates that the duodenal epithelium lacking Pdx1 may have defects in importing iron through enterocytes, resulting in iron deficiency in Pdx1(flox/flox);VilCre mice.
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Affiliation(s)
- Chin Chen
- Dept. of Pediatrics, Stanford Univ. School of Medicine, Stanford, CA 94305-5208, USA.
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36
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Abstract
Hephaestin (Heph), a membrane-bound multicopper ferroxidase (FOX) expressed in duodenal enterocytes, is required for optimal iron absorption. However, sex-linked anemia (sla) mice harboring a 194-amino acid deletion in the Heph protein are able to absorb dietary iron despite reduced expression and mislocalization of the mutant protein. Thus Heph may not be essential, and mice are able to compensate for the loss of its activity. The current studies were undertaken to search for undiscovered FOXs in rodent enterocytes. An experimental approach was developed to investigate intestinal FOXs in which separate membrane and cytosolic fractions were prepared and FOX activity was measured by a spectrophotometric transferrin-coupled assay. Unexpectedly, FOX activity was noted in membrane and cytosolic fractions of rat enterocytes. Different experimental approaches demonstrated that cytosolic FOX activity was not caused by contamination with membrane Heph or a method-induced artifact. Cytosolic FOX activity was abolished by SDS and heat (78 °C), suggesting protein-mediated iron oxidation, and was also sensitive to Triton X-100. Furthermore, cytosolic FOX activity increased ∼30% in iron-deficient rats (compared with controls) but was unchanged in copper-deficient rats (in contrast to the reported dramatic reduction of Heph expression and activity during copper deficiency). Additional studies done in sla, Heph-knockout, and ceruloplasmin-knockout mice proved that cytosolic FOX activity could not be fully explained by Heph or ceruloplasmin. Therefore rodent enterocytes contain a previously undescribed soluble cytosolic FOX that may function in transepithelial iron transport and complement membrane-bound Heph.
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37
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Jiang L, Ranganathan P, Lu Y, Kim C, Collins JF. Exploration of the copper-related compensatory response in the Belgrade rat model of genetic iron deficiency. Am J Physiol Gastrointest Liver Physiol 2011; 301:G877-86. [PMID: 21852364 PMCID: PMC3220320 DOI: 10.1152/ajpgi.00261.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The Menkes copper ATPase (Atp7a) and metallothionein (Mt1a) are induced in the duodenum of iron-deficient rats, and serum and hepatic copper levels increase. Induction of a multi-copper ferroxidase (ceruloplasmin; Cp) has also been documented. These findings hint at an important role for Cu during iron deficiency. The intestinal divalent metal transporter 1 (Dmt1) is also induced during iron deficiency. The hypothesis that Dmt1 is involved in the copper-related compensatory response during iron deficiency was tested, utilizing a mutant Dmt1 rat model, namely the Belgrade (b/b) rat. Data from b/b rats were compared with phenotypically normal, heterozygous +/b rats. Intestinal Atp7a and Dmt1 expression was increased in b/b rats, whereas Mt1a expression was unchanged. Serum and liver copper levels did not increase in the Belgrades nor did Cp protein or activity. The lack of fully functional Dmt1 may thus partially blunt the compensatory response to iron deficiency by 1) decreasing copper levels in enterocytes, as exemplified by a lack of Mt1a induction and a lesser induction of Atp7a, 2) abolishing the frequently described increase in liver and serum copper, and 3) attenuating the documented increase in Cp expression and activity.
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Affiliation(s)
- Lingli Jiang
- Food Science & Human Nutrition Department, University of Florida, Gainesville, Florida
| | | | - Yan Lu
- Food Science & Human Nutrition Department, University of Florida, Gainesville, Florida
| | - Changae Kim
- Food Science & Human Nutrition Department, University of Florida, Gainesville, Florida
| | - James F. Collins
- Food Science & Human Nutrition Department, University of Florida, Gainesville, Florida
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Abstract
Iron-loading disorders (haemochromatosis) represent an important class of human diseases. Primary iron loading results from inherited disturbances in the mechanisms regulating intestinal iron absorption, such that excess iron is taken up from the diet. Body iron load can also be increased by repeated blood transfusions (secondary iron loading), usually as part of the treatment for various haematological disorders. In these syndromes, an element of enhanced iron absorption is also often involved. The central regulator of body iron trafficking is the liver-derived peptide hepcidin. Hepcidin limits iron entry into the plasma from macrophages, intestinal enterocytes and other cells by binding to the sole iron-export protein ferroportin, and facilitating its removal from the plasma membrane. Mutations in hepcidin or its upstream regulators (HFE, TFR2, HFE2 and BMP6) lead to reduced or absent hepcidin expression and a concomitant increase in iron absorption. Mutations in ferroportin that prevent hepcidin binding produce a similar result. Increased ineffective erythropoiesis, which often characterises erythrocyte disorders, also leads to reduced hepcidin expression and increased absorption. Recent advances in our understanding of hepcidin and body iron homeostasis provide the potential for a range of new diagnostic and therapeutic tools for haemochromatosis and related conditions.
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Chen H, Attieh ZK, Syed BA, Kuo Y, Stevens V, Fuqua BK, Andersen HS, Naylor CE, Evans RW, Gambling L, Danzeisen R, Bacouri‐Haidar M, Usta J, Vulpe CD, McArdle HJ. Identification of zyklopen, a new member of the vertebrate multicopper ferroxidase family, and characterization in rodents and human cells. J Nutr 2010; 140:1728-35. [PMID: 20685892 PMCID: PMC2937573 DOI: 10.3945/jn.109.117531] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We previously detected a membrane-bound, copper-containing oxidase that may be involved in iron efflux in BeWo cells, a human placental cell line. We have now identified a gene encoding a predicted multicopper ferroxidase (MCF) with a putative C-terminal membrane-spanning sequence and high sequence identity to hephaestin (Heph) and ceruloplasmin (Cp), the other known vertebrate MCF. Molecular modeling revealed conservation of all type I, II, and III copper-binding sites as well as a putative iron-binding site. Protein expression was observed in multiple diverse mouse tissues, including placenta and mammary gland, and the expression pattern was distinct from that of Cp and Heph. The protein possessed ferroxidase activity, and protein levels decreased in cellular copper deficiency. Knockdown with small interfering RNA in BeWo cells indicates that this gene represents the previously detected oxidase. We propose calling this new member of the MCF family "zyklopen."
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Affiliation(s)
- Huijun Chen
- Department of Nutritional Science and Toxicology, University of California, Berkeley, CA 94720,Medical School, Nanjing University, Nanjing 210008, Jiangsu Province, China
| | - Zouhair K. Attieh
- Department of Nutritional Science and Toxicology, University of California, Berkeley, CA 94720,Department of Laboratory Science and Technology, American University of Science and Technology, Ashrafieh 1100, Lebanon
| | - Basharut A. Syed
- Department of Nutritional Science and Toxicology, University of California, Berkeley, CA 94720,Visiongain Ltd, London EC1V 2QY, UK
| | - Yien‐Ming Kuo
- Department of Medicine, University of California, San Francisco, CA 94143
| | - Valerie Stevens
- Rowett Institute of Nutrition and Health, University of Aberdeen, Bucksburn, AB21 9SB, UK
| | - Brie K. Fuqua
- Department of Nutritional Science and Toxicology, University of California, Berkeley, CA 94720
| | - Henriette S. Andersen
- Rowett Institute of Nutrition and Health, University of Aberdeen, Bucksburn, AB21 9SB, UK
| | - Claire E. Naylor
- Department of Crystallography, Birkbeck College, London, WC1E 7HX, UK
| | - Robert W. Evans
- Division of Biosciences, Centre for Infection, Immunity and Disease Mechanisms, School of Health Sciences and Social Care, Brunel University, Uxbridge, Middlesex, UB8 3PH, UK
| | - Lorraine Gambling
- Rowett Institute of Nutrition and Health, University of Aberdeen, Bucksburn, AB21 9SB, UK
| | - Ruth Danzeisen
- Rowett Institute of Nutrition and Health, University of Aberdeen, Bucksburn, AB21 9SB, UK,International Copper Association, Inc., New York, NY 10016
| | - Mhenia Bacouri‐Haidar
- Department of Biology, Faculty of Sciences, Lebanese University, Hadath 1500, Lebanon
| | - Julnar Usta
- Department of Biochemistry, School of Medicine, American University of Beirut, Beirut 1103, Lebanon
| | - Chris D. Vulpe
- Department of Nutritional Science and Toxicology, University of California, Berkeley, CA 94720,To whom correspondence should be addressed. E-mail:
| | - Harry J. McArdle
- Rowett Institute of Nutrition and Health, University of Aberdeen, Bucksburn, AB21 9SB, UK
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40
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Polonifi A, Politou M, Kalotychou V, Xiromeritis K, Tsironi M, Berdoukas V, Vaiopoulos G, Aessopos A. Iron metabolism gene expression in human skeletal muscle. Blood Cells Mol Dis 2010; 45:233-7. [PMID: 20691620 DOI: 10.1016/j.bcmd.2010.07.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 06/22/2010] [Accepted: 06/22/2010] [Indexed: 11/24/2022]
Abstract
Little is known about iron metabolism in skeletal muscle while hepatic iron metabolism is well understood. The aim of this study is to compare the iron metabolism gene expression profile in skeletal muscle and the liver in humans. Muscle and hepatic biopsies from six normal individuals were acquired. Twelve genes involved in iron metabolism( import, storage, export) were selected to be studied. Reverse transcriptase polymerase chain reaction (RT-PCR) was performed in order to determine the expression profile in skeletal muscle and compare it to the one from the liver. Semi-quantification of the gene expression in the studied tissues was performed by densitometric analysis (DA). The results were expressed relative to the percentage of the β-actin gene. Fine analysis was performed by real-time PCR (q-PCR) quantification for the genes that their expression presented a difference of more than 20% in the 2 tissues in the first applied densitometric analysis. Most of the studied genes, HJV, TFR1, HFE, DMT1, DMT1nonIRE, NGAL, HEPH, IREG1, FTH1 were well expressed (>70% of β-actin) in skeletal muscle . HAMP, CP, and TFR2 were absent or minimally expressed (<10% of β-actin) in skeletal muscle while they were well expressed in liver. HJV and Heph were found to have higher expression in skeletal muscle (SM) compared to liver (L) (SM/L=2.65 ± 1.1(p<0.05) and SM/L=1.5 ± 0.06(p<0.05 respectively in q-PCR). The relative expressions of the studied genes in both tissues and their relative contribution in iron homeostasis in different pathways are discussed.
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Affiliation(s)
- Aikaterini Polonifi
- First Department of Medicine, Medical School, National and Kapodistrian University of Athens, Goudi, Athens, Greece
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41
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Camberlein E, Abgueguen E, Fatih N, Canonne-Hergaux F, Leroyer P, Turlin B, Ropert M, Brissot P, Loréal O. Hepcidin induction limits mobilisation of splenic iron in a mouse model of secondary iron overload. Biochim Biophys Acta Mol Basis Dis 2010; 1802:339-46. [PMID: 20045050 DOI: 10.1016/j.bbadis.2009.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 11/25/2009] [Accepted: 12/01/2009] [Indexed: 11/30/2022]
Abstract
Venesection has been proposed as a treatment for hepatic iron overload in a number of chronic liver disorders that are not primarily linked to mutations in iron metabolism genes. Our aim was to analyse the impact of venesection on iron mobilisation in a mouse model of secondary iron overload. C57Bl/6 mice were given oral iron supplementation with or without phlebotomy between day 0 (D0) and D22, and the results were compared to controls without iron overload. We studied serum and tissue iron parameters, mRNA levels of hepcidin1, ferroportin, and transferrin receptor 1, and protein levels of ferroportin in the liver and spleen. On D0, animals with iron overload displayed elevations in iron parameters and hepatic hepcidin1 mRNA. By D22, in the absence of phlebotomies, splenic iron had increased, but transferrin saturation had decreased. This was associated with high hepatic hepcidin1 mRNA, suggesting that iron bioavailability decreased due to splenic iron sequestration through ferroportin protein downregulation. After 22days with phlebotomy treatments, control mice displayed splenic iron mobilisation that compensated for the iron lost due to phlebotomy. In contrast, phlebotomy treatments in mice with iron overload caused anaemia due to inadequate iron mobilisation. In conclusion, our model of secondary iron overload led to decreased plasma iron associated with an increase in hepcidin expression and subsequent restriction of iron export from the spleen. Our data support the importance of managing hepcidin levels before starting venesection therapy in patients with secondary iron overload that are eligible for phlebotomy.
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Affiliation(s)
- Emilie Camberlein
- UMR INSERM U991, University of Rennes1, Rue Henri le Guilloux, 35033 Rennes, France
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42
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Chen H, Attieh ZK, Dang T, Huang G, van der Hee RM, Vulpe C. Decreased hephaestin expression and activity leads to decreased iron efflux from differentiated Caco2 cells. J Cell Biochem 2009; 107:803-8. [PMID: 19452451 DOI: 10.1002/jcb.22178] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Iron is transported across intestinal brush border cells into the circulation in at least two distinct steps. Iron can enter the enterocyte via the apical surface through several paths. However, iron egress from the basolateral side of enterocytes converges on a single export pathway requiring the iron transporter, ferroportin1, and hephaestin, a ferroxidase. Copper deficiency leads to reduced hephaestin protein expression and activity in mouse enterocytes and intestinal cell lines. We tested the effect of copper deficiency on differentiated Caco2 cells grown in transwells and found decreased hephaestin protein expression and activity as well as reduced ferroportin1 protein levels. Furthermore, the decrease in hephaestin levels correlates with a decrease of (55)Fe release from the basolateral side of Caco2 cells. Presence of ceruloplasmin, apo-transferrin or holo-transferrin did not significantly alter the results observed. Repletion of copper in Caco2 cells leads to reconstitution of hephaestin protein expression, activity, and transepithelial iron transport.
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Affiliation(s)
- Huijun Chen
- Department of Nutritional Science and Toxicology, University of California, Berkeley, 94720-3104, USA.
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43
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Simpson RJ, McKie AT. Regulation of intestinal iron absorption: the mucosa takes control? Cell Metab 2009; 10:84-7. [PMID: 19656486 DOI: 10.1016/j.cmet.2009.06.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Revised: 06/05/2009] [Accepted: 06/19/2009] [Indexed: 01/24/2023]
Abstract
Two studies (Shah et al., 2009; Mastrogiannaki et al., 2009) show that the hypoxia inducible factor HIF-2alpha is a major player in regulating iron absorption by directly controlling the transcription of iron transporters in the intestine in response to changes in mucosal iron or oxygen levels. The HIF-2alpha mechanism has major effects on iron metabolism which can override the well-known hepcidin-ferroportin regulatory axis.
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Affiliation(s)
- Robert J Simpson
- Kings College London, Division of Nutritional Sciences, London, UK
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44
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Bleackley MR, Wong AY, Hudson DM, Wu CHY, MacGillivray RT. Blood Iron Homeostasis: Newly Discovered Proteins and Iron Imbalance. Transfus Med Rev 2009; 23:103-23. [DOI: 10.1016/j.tmrv.2008.12.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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45
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Age-related changes in iron homeostasis in mouse ferroxidase mutants. Biometals 2009; 22:827-34. [DOI: 10.1007/s10534-009-9229-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2008] [Accepted: 03/16/2009] [Indexed: 02/08/2023]
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46
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Aydemir F, Jenkitkasemwong S, Gulec S, Knutson MD. Iron loading increases ferroportin heterogeneous nuclear RNA and mRNA levels in murine J774 macrophages. J Nutr 2009; 139:434-8. [PMID: 19141705 PMCID: PMC2646225 DOI: 10.3945/jn.108.094052] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The transmembrane protein ferroportin is highly expressed in tissue macrophages, where it mediates iron export into the bloodstream. Although ferroportin expression can be controlled post-transcriptionally through a 5' iron-responsive element in its mRNA, various studies have documented increased ferroportin mRNA levels in response to iron, suggesting transcriptional regulation. We studied the effect of iron loading on levels of macrophage ferroportin mRNA, as well as heterogeneous nuclear RNA (hnRNA), the immediate product of ferroportin gene transcription. J774 cells, a mouse macrophage cell line, were incubated for 0, 3, 6, 9, 12, and 24 h in medium supplemented or not with 200 mumol/L iron. Quantitative RT-PCR was used to measure steady-state levels of ferroportin mRNA and hnRNA. Ferroportin mRNA levels increased by 12 h after iron treatment, reaching 6 times the control levels after 24 h. Changes in ferroportin mRNA levels were paralleled by similar changes in the levels of ferroportin hnRNA. Time course studies of ferroportin mRNA and hnRNA abundance after incubating cells with the transcriptional inhibitor actinomycin D revealed that ferroportin mRNA has a half-life of approximately 4 h and that iron loading does not stabilize ferroportin mRNA or hnRNA. Collectively, these data are consistent with the hypothesis that iron increases macrophage ferroportin mRNA levels by inducing transcription of the ferroportin gene.
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Affiliation(s)
- Fikret Aydemir
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA
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47
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Muckenthaler MU, Galy B, Hentze MW. Systemic iron homeostasis and the iron-responsive element/iron-regulatory protein (IRE/IRP) regulatory network. Annu Rev Nutr 2008; 28:197-213. [PMID: 18489257 DOI: 10.1146/annurev.nutr.28.061807.155521] [Citation(s) in RCA: 500] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The regulation and maintenance of systemic iron homeostasis is critical to human health. Iron overload and deficiency diseases belong to the most common nutrition-related pathologies across the globe. It is now well appreciated that the hormonal hepcidin/ferroportin system plays an important regulatory role for systemic iron metabolism. We review recent data that uncover the importance of the cellular iron-responsive element/iron-regulatory protein (IRE/IRP) regulatory network in systemic iron homeostasis. We also discuss how the IRE/IRP regulatory system communicates with the hepcidin/ferroportin system to connect the control networks for systemic and cellular iron balance.
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Affiliation(s)
- Martina U Muckenthaler
- Molecular Medicine Partnership Unit, Department of Pediatric Oncology, Hematology and Immunology, University of Heidelberg, D-69120 Heidelberg, Germany
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48
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Kong WN, Chang YZ, Wang SM, Zhai XL, Shang JX, Li LX, Duan XL. Effect of erythropoietin on hepcidin, DMT1 with IRE, and hephaestin gene expression in duodenum of rats. J Gastroenterol 2008; 43:136-43. [PMID: 18306987 DOI: 10.1007/s00535-007-2138-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Accepted: 10/24/2007] [Indexed: 02/04/2023]
Abstract
BACKGROUND Erythropoietin (Epo) is the central regulator of red blood cell production and can stimulate proliferation and differentiation of erythroid progenitor cells. Now, recombinant human erythropoietin (rHuEpo) is widely used in patients with renal disease, chronic anemia, and iron deficiency of early childhood. It has been reported that the enhanced erythropoiesis associated with erythropoietin therapy increases intestinal iron absorption, but the molecular mechanisms underlying are unknown. Therefore, we have investigated the effect of rHuEpo on duodenal iron transport protein synthesis in rats. METHODS Male Sprague-Dawley rats weighing 250 g were randomly divided into two groups: (1) rHuEpo injection group (rHuEpo, 500 IU/day, s.c.), and (2) control group (injection of the same volume of saline). After 3 days injection, blood parameters, serum iron status, and non-heme iron concentrations in the liver and duodenum were examined at the fifth day. The mRNA levels and protein synthesis of duodenal divalent metal transporter 1 (DMT1), ferroportin 1 (FPN1), and hephaestin (Hp) were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis. Hepatic hepcidin mRNA expression was analyzed by RT-PCR. RESULTS rHuEpo injection significantly stimulated erythropoiesis and decreased serum iron status, non-heme iron concentrations in the liver and duodenum. DMT1 (+IRE) and Hp expression in duodenum were increased significantly. However, DMT1 (-IRE) and FPN1 expression had no apparent change. Hepatic hepcidin mRNA expression was decreased dramatically, reaching an almost undetectable level in rHuEpo-treated rats. CONCLUSIONS rHuEpo administration improved the duodenal iron absorption by increasing the expression of DMT1 (+IRE) and Hp.
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Affiliation(s)
- Wei-Na Kong
- Laboratory of Molecular Iron Metabolism, College of Life Science, Hebei Normal University, Shijiazhuang, Hebei Province, PR China
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Noncitrus Fruits as Novel Dietary Environmental Modifiers of Iron Stores in People With or Without HFE Gene Mutations. Mayo Clin Proc 2008. [PMID: 18452683 DOI: 10.1016/s0025-6196(11)60726-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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50
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Milward EA, Baines SK, Knuiman MW, Bartholomew HC, Divitini ML, Ravine DG, Bruce DG, Olynyk JK. Noncitrus fruits as novel dietary environmental modifiers of iron stores in people with or without HFE gene mutations. Mayo Clin Proc 2008; 83:543-9. [PMID: 18452683 DOI: 10.4065/83.5.543] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE To investigate whether citrus fruit, noncitrus fruit, and other dietary factors act as environmental modifiers of iron status in the absence or presence of hemochromatotic HFE gene mutations. PARTICIPANTS AND METHODS Iron studies, HFE genotypic analyses, and dietary data from a survey conducted from March 21, 1994, through December 15, 1995, were analyzed for a group of 2232 residents (1105 men, 1127 women) aged 20 to 79 years recruited from the community electoral roll of Busselton in Western Australia. Data were analyzed by linear regression analysis and analysis of covariance. RESULTS Higher levels of fresh fruit intake (excluding citrus fruits and citrus juices) had a significant protective effect (P=.002) against high body iron status as gauged by ferritin levels in men, irrespective of HFE genotype. Consumption of 2 or more pieces of fruit per day on average reduced mean serum ferritin levels by 20% compared with average consumption of less than 1 piece of fruit per day. This effect was not observed in women. Consumption of citrus fruits and citrus juices had no significant effects in either sex. No protective effects were observed for tea consumption or any other dietary factors studied. Red meat and alcohol consumption correlated with high body iron stores (P<.05), consistent with previous studies, but did not interact with fruit with regard to effects on serum ferritin (P>.05). CONCLUSION Noncitrus fruits are environmental modifiers of iron status independent of HFE genotype. This could have important implications for the provision of evidence-based dietary advice to patients with other iron-storage disorders.
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Affiliation(s)
- Elizabeth A Milward
- School of Biomedical Sciences and Hunter Medical Research Institute, University of Newcastle, Callaghan, NSW, Australia
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