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Katsarou A, Gkouvatsos K, Fillebeen C, Pantopoulos K. Tissue-Specific Regulation of Ferroportin in Wild-Type and Hjv-/- Mice Following Dietary Iron Manipulations. Hepatol Commun 2021; 5:2139-2150. [PMID: 34558857 PMCID: PMC8631100 DOI: 10.1002/hep4.1780] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 05/28/2021] [Accepted: 06/17/2021] [Indexed: 12/03/2022] Open
Abstract
Hepcidin is a liver‐derived peptide hormone that limits iron egress from tissues to the bloodstream. It operates by binding to the iron exporter ferroportin, which blocks iron transport and tags ferroportin for degradation. Genetic hepcidin inactivation leads to hereditary hemochromatosis, a disease of iron overload. We used wild‐type and Hjv‐/‐ mice, a model of hemochromatosis, to examine the expression of ferroportin and other proteins of iron metabolism in hepcidin target tissues. The animals were previously subjected to dietary iron manipulations. In Hjv‐/‐ mice, hepcidin messenger RNA correlated significantly with hepatic iron load (r = 0.8211, P < 0.001), but was substantially lower compared with wild‐type controls. Duodenal ferroportin and divalent metal transporter 1 (DMT1), as well as splenic and hepatic ferroportin, were overexpressed in these animals. A high‐iron diet (2% carbonyl iron) suppressed duodenal DMT1 levels in both wild‐type and Hjv‐/‐ mice; however, it did not affect duodenal ferroportin expression in Hjv‐/‐ mice, and only reduced it in wild‐type mice. In contrast, the high‐iron diet decreased splenic ferroportin exclusively in Hjv‐/‐ mice, whereas it induced hepatic ferroportin exclusively in wild‐type mice. Conclusion: Our data show that dietary iron differentially affects ferroportin expression in mouse tissues and are consistent with hepcidin‐dependent and hepcidin‐independent mechanisms for ferroportin regulation. In the Hjv‐/‐ mouse model of hemochromatosis, duodenal ferroportin remains unresponsive to iron but DMT1 is appropriately iron‐regulated.
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Affiliation(s)
- Angeliki Katsarou
- Department of Medicine, Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Konstantinos Gkouvatsos
- Department of Medicine, Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Carine Fillebeen
- Department of Medicine, Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Kostas Pantopoulos
- Department of Medicine, Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, QC, Canada
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Diabetes-Related Induction of the Heme Oxygenase System and Enhanced Colocalization of Heme Oxygenase 1 and 2 with Neuronal Nitric Oxide Synthase in Myenteric Neurons of Different Intestinal Segments. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:1890512. [PMID: 29081883 PMCID: PMC5610792 DOI: 10.1155/2017/1890512] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 08/02/2017] [Accepted: 08/17/2017] [Indexed: 12/17/2022]
Abstract
Increase in hyperglycaemia-induced oxidative stress and decreased effectiveness of endogenous defense mechanisms plays an essential role in the initiation of diabetes-related neuropathy. We demonstrated that nitrergic myenteric neurons display different susceptibilities to diabetic damage in different gut segments. Therefore, we aim to reveal the gut segment-specific differences in the expression of heme oxygenase (HO) isoforms and the colocalization of these antioxidants with neuronal nitric oxide synthase (nNOS) in myenteric neurons. After ten weeks, samples from the duodenum, ileum, and colon of control and streptozotocin-induced diabetic rats were processed for double-labelling fluorescent immunohistochemistry and ELISA. The number of both HO-immunoreactive and nNOS/HO-immunoreactive myenteric neurons was the lowest in the ileal and the highest in the colonic ganglia of controls; it increased the most extensively in the ileum and was also elevated in the colon of diabetics. Although the total number of nitrergic neurons decreased in all segments, the proportion of nNOS-immunoreactive neurons colocalizing with HOs was enhanced robustly in the ileum and colon of diabetics. We presume that those nitrergic neurons which do not colocalize with HOs are the most seriously affected by diabetic damage. Therefore, the regional induction of the HO system is strongly correlated with diabetes-related region-specific nitrergic neuropathy.
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Buffler M, Becker C, Windisch W, Schümann K. Inflammation neither increases hepatic hepcidin nor affects intestinal (59)Fe-absorption in two murine models of bowel inflammation, hemizygous TNF(ΔARE/+) and homozygous IL-10(-/-) mice. J Trace Elem Med Biol 2015; 32:162-7. [PMID: 26302924 DOI: 10.1016/j.jtemb.2015.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/06/2015] [Accepted: 07/06/2015] [Indexed: 01/25/2023]
Abstract
Hepcidin-synthesis was reported to be stimulated by inflammation. In contrast, hepcidin synthesis was inhibited by TNFα and serum hepcidin was low. To elucidate these contradictions, we compare data on hepcidin expression, on iron absorption and homoeostasis and markers of inflammation between two murine models of intestinal inflammation and corresponding wild-types as determined by standard methods. In TNF(ΔARE/+) and IL-10(-/-)-mice hepatic hepcidin expression and protein content was significantly lower than in corresponding wild-types. However, (59)Fe whole-body retention showed no difference between knock-outs and corresponding wild-types 7d after gavage, in neither strain. Compared to wild-types, body weight, hepatic non-haem iron content, hemoglobin and hematocrit were significantly decreased in TNF(ΔARE/+) mice, while erythropoiesis increased. These differences were not seen in IL-10(-/-) mice. Duodenal IL-6 and TNFα content increased significantly in TNF(ΔARE/+) mice, while ferritin-H decreased along with hepatic hepcidin expression, ferritin L, and non-haem iron. In IL-10(-/-) mice, these changes were less marked or missing for non-haem iron. Duodenal ferritin-L and ferroportin increased significantly, while HFE decreased. Our results corroborate the conflicting combination of low hepcidin with inflammation and without increased intestinal iron absorption. Speculating on underlying mechanism, decreased hepcidin may result from stimulated erythropoiesis. Unaltered intestinal iron-absorption may compromise between the stimulation by increased erythropoiesis and inhibition by local and systemic inflammation. The findings suggest intense interaction between counterproductive mechanisms and ask for further research.
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Affiliation(s)
- M Buffler
- Chair of Animal Nutrition, TUM School of Life Sciences, Technische Universität München, Germany
| | - C Becker
- Chair of Animal Nutrition, TUM School of Life Sciences, Technische Universität München, Germany.
| | - W Windisch
- Chair of Animal Nutrition, TUM School of Life Sciences, Technische Universität München, Germany
| | - K Schümann
- Research Center for Nutrition and Food Science (ZIEL), TUM School of Life Sciences, Technische Universität München, Germany
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Fillebeen C, Gkouvatsos K, Fragoso G, Calvé A, Garcia-Santos D, Buffler M, Becker C, Schümann K, Ponka P, Santos MM, Pantopoulos K. Mice are poor heme absorbers and do not require intestinal Hmox1 for dietary heme iron assimilation. Haematologica 2015; 100:e334-7. [PMID: 25975840 DOI: 10.3324/haematol.2015.126870] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Carine Fillebeen
- Department of Medicine, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Konstantinos Gkouvatsos
- Department of Medicine, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Gabriela Fragoso
- Département de Médecine, Université de Montréal, and Centre de Recherche du Centre Hospitalier de l'Université de Montŕeal (CRCHUM), Montreal, Quebec, Canada
| | - Annie Calvé
- Département de Médecine, Université de Montréal, and Centre de Recherche du Centre Hospitalier de l'Université de Montŕeal (CRCHUM), Montreal, Quebec, Canada
| | - Daniel Garcia-Santos
- Department of Physiology, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Marzell Buffler
- Science Center Weihenstephan, Technical University Munich, Am Forum 5, Freising, Germany
| | - Christiane Becker
- Science Center Weihenstephan, Technical University Munich, Am Forum 5, Freising, Germany
| | - Klaus Schümann
- Science Center Weihenstephan, Technical University Munich, Am Forum 5, Freising, Germany
| | - Prem Ponka
- Department of Physiology, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Manuela M Santos
- Département de Médecine, Université de Montréal, and Centre de Recherche du Centre Hospitalier de l'Université de Montŕeal (CRCHUM), Montreal, Quebec, Canada
| | - Kostas Pantopoulos
- Department of Medicine, McGill University, and Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
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Kent P, Wilkinson N, Constante M, Fillebeen C, Gkouvatsos K, Wagner J, Buffler M, Becker C, Schümann K, Santos MM, Pantopoulos K. Hfe and Hjv exhibit overlapping functions for iron signaling to hepcidin. J Mol Med (Berl) 2015; 93:489-98. [DOI: 10.1007/s00109-015-1253-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/10/2014] [Accepted: 12/29/2014] [Indexed: 02/07/2023]
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Should we reconsider iron administration based on prevailing ferritin and hepcidin concentrations? Clin Exp Nephrol 2012; 16:819-26. [PMID: 23053592 PMCID: PMC3521641 DOI: 10.1007/s10157-012-0694-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 08/29/2012] [Indexed: 12/21/2022]
Abstract
The results of recent randomized, controlled trials in patients with chronic kidney disease and anemia have suggested that hyporesponsiveness to erythropoiesis stimulating agents (ESA) is a significant predictor of poor patient outcomes. Functional iron deficiency (FID) is the most common cause of suboptimal ESA response, and intravenous iron administration (IVFe) efficiently raises hemoglobin (Hb) concentrations even under the condition of FID. Consequently, renal anemia correction has conceptually shifted from ‘higher Hb values with high ESA doses’ to ‘prevention of ESA hyporesponsiveness with IVFe’. The discovery of hepcidin has profoundly changed our understanding of the place of FID in renal anemia therapy. Hepcidin reduces the abundance of iron transport proteins which facilitate iron absorption from the gut and iron mobilization from macrophages. Serum hepcidin is mainly modulated by iron stores, as is serum ferritin. High hepcidin or ferritin levels block intestinal iron absorption and iron recycling in macrophages and decrease iron availability for erythropoiesis, leading to FID. Iron administration, especially IVFe, increases hepcidin levels and concomitantly inhibits iron supply to erythroid cells. This in turn could lead to a vicious circle, exacerbating FID and increasing iron demand. Therefore, physicians should be cautious with unrestricted IVFe to chronic kidney disease patients with FID.
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Shanmugam NKN, Ellenbogen S, Trebicka E, Wang L, Mukhopadhyay S, Lacy-Hulbert A, Gallini CA, Garrett WS, Cherayil BJ. Tumor necrosis factor α inhibits expression of the iron regulating hormone hepcidin in murine models of innate colitis. PLoS One 2012; 7:e38136. [PMID: 22675442 PMCID: PMC3365004 DOI: 10.1371/journal.pone.0038136] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 04/30/2012] [Indexed: 12/21/2022] Open
Abstract
Background Abnormal expression of the liver peptide hormone hepcidin, a key regulator of iron homeostasis, contributes to the pathogenesis of anemia in conditions such as inflammatory bowel disease (IBD). Since little is known about the mechanisms that control hepcidin expression during states of intestinal inflammation, we sought to shed light on this issue using mouse models. Methodology/Principal Findings Hepcidin expression was evaluated in two types of intestinal inflammation caused by innate immune activation—dextran sulfate sodium (DSS)-induced colitis in wild-type mice and the spontaneous colitis occurring in T-bet/Rag2-deficient (TRUC) mice. The role of tumor necrosis factor (TNF) α was investigated by in vivo neutralization, and by treatment of a hepatocyte cell line, as well as mice, with the recombinant cytokine. Expression and activation of Smad1, a positive regulator of hepcidin transcription, were assessed during colitis and following administration or neutralization of TNFα. Hepcidin expression progressively decreased with time during DSS colitis, correlating with changes in systemic iron distribution. TNFα inhibited hepcidin expression in cultured hepatocytes and non-colitic mice, while TNFα neutralization during DSS colitis increased it. Similar results were obtained in TRUC mice. These effects involved a TNFα-dependent decrease in Smad1 protein but not mRNA. Conclusions/Significance TNFα inhibits hepcidin expression in two distinct types of innate colitis, with down-regulation of Smad1 protein playing an important role in this process. This inhibitory effect of TNFα may be superseded by other factors in the context of T cell-mediated colitis given that in the latter form of intestinal inflammation hepcidin is usually up-regulated.
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Affiliation(s)
- Nanda Kumar N. Shanmugam
- Mucosal Immunology Laboratory, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Shiri Ellenbogen
- Mucosal Immunology Laboratory, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Estela Trebicka
- Mucosal Immunology Laboratory, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Lijian Wang
- Mucosal Immunology Laboratory, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Subhankar Mukhopadhyay
- Developmental Immunology Laboratory, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Adam Lacy-Hulbert
- Developmental Immunology Laboratory, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
| | - Carey Ann Gallini
- Departments of Immunology and Infectious Diseases and Genetics and Complex Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Wendy S. Garrett
- Harvard Medical School, Boston, Massachusetts, United States of America
- Departments of Immunology and Infectious Diseases and Genetics and Complex Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
- Dana-Farber Cancer Institute, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Bobby J. Cherayil
- Mucosal Immunology Laboratory, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Gkouvatsos K, Wagner J, Papanikolaou G, Sebastiani G, Pantopoulos K. Conditional disruption of mouse HFE2 gene: maintenance of systemic iron homeostasis requires hepatic but not skeletal muscle hemojuvelin. Hepatology 2011; 54:1800-7. [PMID: 21748766 DOI: 10.1002/hep.24547] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 06/29/2011] [Indexed: 01/25/2023]
Abstract
UNLABELLED Mutations of the HFE2 gene are linked to juvenile hemochromatosis, a severe hereditary iron overload disease caused by chronic hyperabsorption of dietary iron. HFE2 encodes hemojuvelin (Hjv), a membrane-associated bone morphogenetic protein (BMP) coreceptor that enhances expression of the liver-derived iron regulatory hormone hepcidin. Hjv is primarily expressed in skeletal muscles and at lower levels in the heart and the liver. Moreover, a soluble Hjv form circulates in plasma and is thought to act as a decoy receptor, attenuating BMP signaling to hepcidin. To better understand the regulatory function of Hjv, we generated mice with tissue-specific disruption of this protein in hepatocytes or in muscle cells. The hepatic ablation of Hjv resulted in iron overload, quantitatively comparable to that observed in ubiquitous Hjv-/- mice. Serum iron and ferritin levels, transferrin saturation, and liver iron content were significantly (P < 0.001) elevated in liver-specific Hjv-/- mice. Hepatic Hjv mRNA was undetectable, whereas hepcidin expression was markedly suppressed (12.6-fold; P < 0.001) and hepatic BMP6 mRNA up-regulated (2.4-fold; P < 0.01), as in ubiquitous Hjv-/- counterparts. By contrast, the muscle-specific disruption of Hjv was not associated with iron overload or altered hepcidin expression, suggesting that muscle Hjv mRNA is dispensable for iron metabolism. Our data do not support any significant iron-regulatory function of putative muscle-derived soluble Hjv in mice, at least under physiological conditions. CONCLUSION The hemochromatotic phenotype of liver-specific Hjv-/- mice suggests that hepatic Hjv is necessary and sufficient to regulate hepcidin expression and control systemic iron homeostasis.
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Affiliation(s)
- Konstantinos Gkouvatsos
- Lady Davis Institute for Medical Research, Jewish General Hospital, and Department of Medicine, McGill University, Montreal, Quebec, Canada
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Abstract
PURPOSE OF REVIEW Recent advances in the study of iron metabolism have led to a better understanding of the molecular basis for the interactions between iron and the inflammatory response. We will review this new information in the context of the gastrointestinal tract. RECENT FINDINGS The effects of iron on microbial enteropathogens are well known. Recent work has demonstrated that iron also has potentially important effects on the intestinal microbiota. On the host side, hepcidin, a key regulator of mammalian iron metabolism, has emerged as an important mediator of the cross-talk between iron homeostasis and inflammation. Hepcidin-dependent changes in iron flux can influence the expression of inflammatory cytokines, and conversely, inflammatory cytokines can induce hepcidin expression and alter iron homeostasis. Hepcidin levels have been found to be elevated in some studies of inflammatory bowel disease, while manipulating hepcidin expression in animal models of this condition has beneficial effects on both inflammation and dysregulated iron metabolism. SUMMARY The information on iron metabolism that has become available in recent years has shed new light on the pathogenesis of inflammatory diseases of the gastrointestinal tract, and is also starting to suggest new approaches to treating such diseases.
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Maffettone C, Chen G, Drozdov I, Ouzounis C, Pantopoulos K. Tumorigenic properties of iron regulatory protein 2 (IRP2) mediated by its specific 73-amino acids insert. PLoS One 2010; 5:e10163. [PMID: 20405006 PMCID: PMC2854138 DOI: 10.1371/journal.pone.0010163] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Accepted: 03/23/2010] [Indexed: 12/21/2022] Open
Abstract
Iron regulatory proteins, IRP1 and IRP2, bind to mRNAs harboring iron responsive elements and control their expression. IRPs may also perform additional functions. Thus, IRP1 exhibited apparent tumor suppressor properties in a tumor xenograft model. Here we examined the effects of IRP2 in a similar setting. Human H1299 lung cancer cells or clones engineered for tetracycline-inducible expression of wild type IRP2, or the deletion mutant IRP2Δ73 (lacking a specific insert of 73 amino acids), were injected subcutaneously into nude mice. The induction of IRP2 profoundly stimulated the growth of tumor xenografts, and this response was blunted by addition of tetracycline in the drinking water of the animals, to turnoff the IRP2 transgene. Interestingly, IRP2Δ73 failed to promote tumor growth above control levels. As expected, xenografts expressing the IRP2 transgene exhibited high levels of transferrin receptor 1 (TfR1); however, the expression of other known IRP targets was not affected. Moreover, these xenografts manifested increased c-MYC levels and ERK1/2 phosphorylation. A microarray analysis identified distinct gene expression patterns between control and tumors containing IRP2 or IRP1 transgenes. By contrast, gene expression profiles of control and IRP2Δ73-related tumors were more similar, consistently with their growth phenotype. Collectively, these data demonstrate an apparent pro-oncogenic activity of IRP2 that depends on its specific 73 amino acids insert, and provide further evidence for a link between IRPs and cancer biology.
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Affiliation(s)
- Carmen Maffettone
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Guohua Chen
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Ignat Drozdov
- Cardiovascular Division, King's College London British Heart Foundation (BHF) Centre of Excellence, London, England, United Kingdom
- Centre for Bioinformatics, School of Physical Sciences & Engineering, King's College London, London, England, United Kingdom
| | - Christos Ouzounis
- Centre for Bioinformatics, School of Physical Sciences & Engineering, King's College London, London, England, United Kingdom
| | - Kostas Pantopoulos
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, and Department of Medicine, McGill University, Montreal, Quebec, Canada
- * E-mail:
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