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Jang G, Lee EM, Kim HJ, Park Y, Bang NH, Lee Kang J, Park EM. Visceral adiposity is associated with iron deposition and myelin loss in the brains of aged mice. Neurochem Int 2024; 179:105833. [PMID: 39128623 DOI: 10.1016/j.neuint.2024.105833] [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: 04/09/2024] [Revised: 08/05/2024] [Accepted: 08/08/2024] [Indexed: 08/13/2024]
Abstract
Iron deposition and myelin loss are observed in the brain with aging, and iron accumulation is suggested to be involved in myelin damage. However, the exact mechanism of iron deposition with aging remains unclear. This study was aimed to determine whether expanded visceral adipose tissue contributes to iron deposition and myelin loss by inducing hepcidin in the brains of aged male mice. Compared with young adult mice, levels of hepcidin in the brain, epididymal adipose tissue, and circulation were increased in aged mice, which had expanded visceral adipose tissue with inflammation. An increase in expressions of ferritin, an indicator of intracellular iron status, was accompanied by decreased levels of proteins related to myelin sheath in the brains of aged mice. These age-related changes in the brain were improved by visceral fat removal. In addition, IL-6 level, activation of microglia/macrophages, and nuclear translocation of phosphorylated Smad1/5 (pSmad1/5) inducing hepcidin expression were reduced in the brains of aged mice after visceral fat removal, accompanied by decreases of pSmad1/5- and ferritin-positive microglia/macrophages and mature oligodendrocytes. These findings indicate that visceral adiposity contributes to hepcidin-mediated iron deposition and myelin loss with inflammation in the aged brain. Our results support the importance of preventing visceral adiposity for maintaining brain health in older individuals.
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Affiliation(s)
- Gyeonghui Jang
- Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, 07084, Republic of Korea
| | - Eun-Mi Lee
- Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, 07084, Republic of Korea
| | - Hyun-Jung Kim
- Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, 07084, Republic of Korea
| | - Yelin Park
- Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, 07084, Republic of Korea
| | - Nayun Hanna Bang
- School of Medicine, Ewha Womans University, Seoul, 07084, Republic of Korea
| | - Jihee Lee Kang
- Inflammation-Cancer Microenvironment Research Center, College of Medicine, Ewha Womans University, 07084, Republic of Korea; Department of Physiology, College of Medicine, Ewha Womans University, Seoul, 07084, Republic of Korea.
| | - Eun-Mi Park
- Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, 07084, Republic of Korea.
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2
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Sobieska K, Buczyńska A, Krętowski AJ, Popławska-Kita A. Iron homeostasis and insulin sensitivity: unraveling the complex interactions. Rev Endocr Metab Disord 2024:10.1007/s11154-024-09908-7. [PMID: 39287729 DOI: 10.1007/s11154-024-09908-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/05/2024] [Indexed: 09/19/2024]
Abstract
Diabetes has arisen as a noteworthy global health issue, marked by escalating incidence and mortality rates. Insulin, crucial for preserving euglycemia, acts as a vital energy provider for various tissues. Iron metabolism notably plays a significant role in the development of insulin resistance, a key factor in the onset of various metabolic disorders. The intricate interaction between iron and insulin signaling encompasses complex regulatory mechanisms at the molecular level, thereby impacting cellular reactions to insulin. The intricate interplay between insulin and glucagon, essential for precise regulation of hepatic glucose production and systemic glucose levels, may be influenced by certain microelements for instance zinc, copper, iron, boron, calcium, cobalt, chromium, iodine, magnesium and selenium. While significant progress has been achieved in elucidating the pathophysiological connections between iron overload and glucose metabolism, our understanding of the involvement of the Fenton reaction and oxidative stress in insulin resistance influencing many chronical conditions remains limited. Furthermore, the exploration of the multifaceted roles of insulin in the human body continues to be a subject of active investigation by numerous scientific researchers. This review comprehensively outlines the potential adverse impact of iron overload on insulin function and glucose metabolism. Additionally, we provide a synthesis of findings derived from various research domains, encompassing population studies, animal models, and clinical investigations, to scrutinize the multifaceted relationship between iron and insulin sensitivity. Moreover, we delineate instances of correlations between serum iron levels and various medical conditions, including the diabetes also gestational diabetes and obesity.
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Affiliation(s)
- Katarzyna Sobieska
- Department of Endocrinology, Diabetology and Internal Medicine, Medical University of Bialystok, Bialystok, Poland
| | - Angelika Buczyńska
- Clinical Research Centre, Medical University of Bialystok, Bialystok, Poland
| | - Adam Jacek Krętowski
- Department of Endocrinology, Diabetology and Internal Medicine, Medical University of Bialystok, Bialystok, Poland
- Clinical Research Centre, Medical University of Bialystok, Bialystok, Poland
| | - Anna Popławska-Kita
- Department of Endocrinology, Diabetology and Internal Medicine, Medical University of Bialystok, Bialystok, Poland.
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Lu B, Guo S, Zhao J, Wang X, Zhou B. Adipose knockout of H-ferritin improves energy metabolism in mice. Mol Metab 2024; 80:101871. [PMID: 38184276 PMCID: PMC10803945 DOI: 10.1016/j.molmet.2024.101871] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 12/12/2023] [Accepted: 01/02/2024] [Indexed: 01/08/2024] Open
Abstract
OBJECTIVE Ferritin, the principal iron storage protein, is essential to iron homeostasis. How iron homeostasis affects the adipose tissue is not well understood. We investigated the role of ferritin heavy chain in adipocytes in energy metabolism. METHODS We generated adipocyte-specific ferritin heavy chain (Fth, also known as Fth1) knockout mice, herein referred to as FthAKO. These mice were analyzed for iron homeostasis, oxidative stress, mitochondrial biogenesis and activity, adaptive thermogenesis, insulin sensitivity, and metabolic measurements. Mouse embryonic fibroblasts and primary mouse adipocytes were used for in vitro experiments. RESULTS In FthAKO mice, the adipose iron homeostasis was disrupted, accompanied by elevated expression of adipokines, dramatically induced heme oxygenase 1(Hmox1) expression, and a notable decrease in the mitochondrial ROS level. Cytosolic ROS elevation in the adipose tissue of FthAKO mice was very mild, and we only observed this in the brown adipose tissue (BAT) but not in the white adipose tissue (WAT). FthAKO mice presented an altered metabolic profile and showed increased insulin sensitivity, glucose tolerance, and improved adaptive thermogenesis. Interestingly, loss of ferritin resulted in enhanced mitochondrial respiration capacity and a preference for lipid metabolism. CONCLUSIONS These findings indicate that ferritin in adipocytes is indispensable to intracellular iron homeostasis and regulates systemic lipid and glucose metabolism.
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Affiliation(s)
- Binyu Lu
- Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Shanshan Guo
- Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Jialin Zhao
- Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Xiaoting Wang
- Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Bing Zhou
- Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
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4
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Larsen JK, Kruse R, Sahebekhtiari N, Moreno-Justicia R, Gomez Jorba G, Petersen MH, de Almeida ME, Ørtenblad N, Deshmukh AS, Højlund K. High-throughput proteomics uncovers exercise training and type 2 diabetes-induced changes in human white adipose tissue. SCIENCE ADVANCES 2023; 9:eadi7548. [PMID: 38019916 PMCID: PMC10686561 DOI: 10.1126/sciadv.adi7548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 10/30/2023] [Indexed: 12/01/2023]
Abstract
White adipose tissue (WAT) is important for metabolic homeostasis. We established the differential proteomic signatures of WAT in glucose-tolerant lean and obese individuals and patients with type 2 diabetes (T2D) and the response to 8 weeks of high-intensity interval training (HIIT). Using a high-throughput and reproducible mass spectrometry-based proteomics pipeline, we identified 3773 proteins and found that most regulated proteins displayed progression in markers of dysfunctional WAT from lean to obese to T2D individuals and were highly associated with clinical measures such as insulin sensitivity and HbA1c. We propose that these distinct markers could serve as potential clinical biomarkers. HIIT induced only minor changes in the WAT proteome. This included an increase in WAT ferritin levels independent of obesity and T2D, and WAT ferritin levels were strongly correlated with individual insulin sensitivity. Together, we report a proteomic signature of WAT related to obesity and T2D and highlight an unrecognized role of human WAT iron metabolism in exercise training adaptations.
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Affiliation(s)
- Jeppe Kjærgaard Larsen
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Rikke Kruse
- Steno Diabetes Center Odense, Odense University Hospital, Odense C, Denmark
- Department of Clinical Research, University of Southern Denmark, Odense C, Denmark
| | - Navid Sahebekhtiari
- Steno Diabetes Center Odense, Odense University Hospital, Odense C, Denmark
- Department of Clinical Research, University of Southern Denmark, Odense C, Denmark
| | - Roger Moreno-Justicia
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Gerard Gomez Jorba
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Maria H. Petersen
- Steno Diabetes Center Odense, Odense University Hospital, Odense C, Denmark
| | - Martin E. de Almeida
- Steno Diabetes Center Odense, Odense University Hospital, Odense C, Denmark
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Atul S. Deshmukh
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Kurt Højlund
- Steno Diabetes Center Odense, Odense University Hospital, Odense C, Denmark
- Department of Clinical Research, University of Southern Denmark, Odense C, Denmark
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“Ferrocrinology”—Iron Is an Important Factor Involved in Gluco- and Lipocrinology. Nutrients 2022; 14:nu14214693. [DOI: 10.3390/nu14214693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/04/2022] [Accepted: 11/04/2022] [Indexed: 11/09/2022] Open
Abstract
“Ferrocrinology” is the term used to describe the study of iron effects on the functioning of adipose tissue, which together with muscle tissue makes the largest endocrine organ in the human body. By impairing exercise capacity, reducing AMP-activated kinase activity, and enhancing insulin resistance, iron deficiency can lead to the development of obesity and type 2 diabetes mellitus. Due to impaired browning of white adipose tissue and reduced mitochondrial iron content in adipocytes, iron deficiency (ID) can cause dysfunction of brown adipose tissue. By reducing ketogenesis, aconitase activity, and total mitochondrial capacity, ID impairs muscle performance. Another important aspect is the effect of ID on the impairment of thermogenesis due to reduced binding of thyroid hormones to their nuclear receptors, with subsequently impaired utilization of norepinephrine in tissues, and impaired synthesis and distribution of cortisol, which all make the body’s reactivity to stress in ID more pronounced. Iron deficiency can lead to the development of the most common endocrinopathy, autoimmune thyroid disease. In this paper, we have discussed the role of iron in the cross-talk between glucocrinology, lipocrinology and myocrinology, with thyroid hormones acting as an active bystander.
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Kindi H, Willems C, Zhao M, Menzel M, Schmelzer CEH, Herzberg M, Fuhrmann B, Gallego-Ferrer G, Groth T. Metal Ion Doping of Alginate-Based Surface Coatings Induces Adipogenesis of Stem Cells. ACS Biomater Sci Eng 2022; 8:4327-4340. [PMID: 36174215 DOI: 10.1021/acsbiomaterials.2c00444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Metal ions are important effectors of protein and cell functions. Here, polyelectrolyte multilayers (PEMs) made of chitosan (Chi) and alginate (Alg) were doped with different metal ions (Ca2+, Co2+, Cu2+, and Fe3+), which can form bonds with their functional groups. Ca2+ and Fe3+ ions can be deposited in PEM at higher quantities resulting in more positive ζ potentials and also higher water contact angles in the case of Fe3+. An interesting finding was that the exposure of PEM to metal ions decreases the elastic modulus of PEM. Fourier transformed infrared (FTIR) spectroscopy of multilayers provides evidence of interaction of metal ions with the carboxylic groups of Alg but not for hydroxyl and amino groups. The observed changes in wetting and surface potential are partly related to the increased adhesion and proliferation of multipotent C3H10T1/2 fibroblasts in contrast to plain nonadhesive [Chi/Alg] multilayers. Specifically, PEMs doped with Cu2+ and Fe3+ ions greatly promote cell attachment and adipogenic differentiation, which indicates that changes in not only surface properties but also the bioactivity of metal ions play an important role. In conclusion, metal ion-doped multilayer coatings made of alginate and chitosan can promote the differentiation of multipotent cells on implants without the use of other morphogens like growth factors.
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Affiliation(s)
- Husnia Kindi
- Institute of Pharmacy, Department Biomedical Materials, Martin Luther University Halle-Wittenberg, Heinrich-Damerow Strasse 4, 06120 Halle (Saale), Germany
| | - Christian Willems
- Institute of Pharmacy, Department Biomedical Materials, Martin Luther University Halle-Wittenberg, Heinrich-Damerow Strasse 4, 06120 Halle (Saale), Germany
| | - Mingyan Zhao
- Stem Cell Research and Cellular Therapy Center, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524003, China
| | - Matthias Menzel
- Department of Biological and Macromolecular Materials, Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Walter-Hülse-Strasse 1, 06120 Halle (Saale), Germany
| | - Christian E H Schmelzer
- Department of Biological and Macromolecular Materials, Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Walter-Hülse-Strasse 1, 06120 Halle (Saale), Germany
| | - Martin Herzberg
- Molecular Microbiology, Institute for Biology/Microbiology, Martin-Luther-University, Halle- Wittenberg, Kurt-Mothes-Strasse 3, 06120 Halle (Saale), Germany
| | - Bodo Fuhrmann
- Institute of Physics, Martin Luther University Halle-Wittenberg, Heinrich-Damerow-Strasse 4, 06120 Halle (Saale), Germany.,Interdisciplinary Center of Materials Science, Martin Luther University Halle-Wittenberg, Heinrich-Damerow-Strasse 4, 06120 Halle (Saale), Germany
| | - Gloria Gallego-Ferrer
- Centre for Biomaterials and Tissue Engineering, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.,Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 46022 Valencia, Spain
| | - Thomas Groth
- Institute of Pharmacy, Department Biomedical Materials, Martin Luther University Halle-Wittenberg, Heinrich-Damerow Strasse 4, 06120 Halle (Saale), Germany.,Interdisciplinary Center of Materials Science, Martin Luther University Halle-Wittenberg, Heinrich-Damerow-Strasse 4, 06120 Halle (Saale), Germany
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7
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Essential role of systemic iron mobilization and redistribution for adaptive thermogenesis through HIF2-α/hepcidin axis. Proc Natl Acad Sci U S A 2021; 118:2109186118. [PMID: 34593646 DOI: 10.1073/pnas.2109186118] [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] [Accepted: 08/30/2021] [Indexed: 12/23/2022] Open
Abstract
Iron is an essential biometal, but is toxic if it exists in excess. Therefore, iron content is tightly regulated at cellular and systemic levels to meet metabolic demands but to avoid toxicity. We have recently reported that adaptive thermogenesis, a critical metabolic pathway to maintain whole-body energy homeostasis, is an iron-demanding process for rapid biogenesis of mitochondria. However, little information is available on iron mobilization from storage sites to thermogenic fat. This study aimed to determine the iron-regulatory network that underlies beige adipogenesis. We hypothesized that thermogenic stimulus initiates the signaling interplay between adipocyte iron demands and systemic iron liberation, resulting in iron redistribution into beige fat. To test this hypothesis, we induced reversible activation of beige adipogenesis in C57BL/6 mice by administering a β3-adrenoreceptor agonist CL 316,243 (CL). Our results revealed that CL stimulation induced the iron-regulatory protein-mediated iron import into adipocytes, suppressed hepcidin transcription, and mobilized iron from the spleen. Mechanistically, CL stimulation induced an acute activation of hypoxia-inducible factor 2-α (HIF2-α), erythropoietin production, and splenic erythroid maturation, leading to hepcidin suppression. Disruption of systemic iron homeostasis by pharmacological HIF2-α inhibitor PT2385 or exogenous administration of hepcidin-25 significantly impaired beige fat development. Our findings suggest that securing iron availability via coordinated interplay between renal hypoxia and hepcidin down-regulation is a fundamental mechanism to activate adaptive thermogenesis. It also provides an insight into the effects of adaptive thermogenesis on systemic iron mobilization and redistribution.
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8
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Yook JS, Thomas SS, Toney AM, You M, Kim YC, Liu Z, Lee J, Chung S. Dietary Iron Deficiency Modulates Adipocyte Iron Homeostasis, Adaptive Thermogenesis, and Obesity in C57BL/6 Mice. J Nutr 2021; 151:2967-2975. [PMID: 34383942 PMCID: PMC8485911 DOI: 10.1093/jn/nxab222] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/29/2021] [Accepted: 06/15/2021] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Adaptive thermogenesis is an iron-demanding pathway, significantly contributing to whole-body energy expenditure. However, the effects of iron-deficient diets on adaptive thermogenesis and obesity remain unknown. OBJECTIVES We aimed to determine the impact of dietary iron deficiency on iron homeostasis in adipocytes, adaptive thermogenic capacity, and metabolic consequences in obesity. METHODS C57BL/6 male mice were assigned to either the iron-adequate (IA, 35 ppm) or the iron-deficient group (ID, 3 ppm) at weaning. Upon 8 wk of age, both IA and ID groups received an isocaloric high-fat diet (45% kcal from fat) for 10 wk, maintaining the same iron content. Mice (n = 8) were used to determine the iron status at the systemic and tissue levels and lipid metabolism and inflammatory signaling in adipose tissue. The same mice were used to evaluate cold tolerance (4°C) for 3 h. For assessing adaptive thermogenesis, mice (n = 5) received an intraperitoneal injection of β3-adrenoceptor agonist CL316243 (CL) for 5 d. RESULTS Compared with the IA group, the ID group had nonanemic iron deficiency, lower serum ferritin (42.8%, P < 0.01), and greater weight gain (8.67%, P < 0.05) and insulin resistance (159%, P < 0.01), partly due to reduced AMP-activated protein kinase activation (61.0%, P < 0.05). Upon cold exposure, the ID group maintained a core body temperature 2°C lower than the IA group. The ID group had lower iron content (47.0%, P < 0.01) in the inguinal adipose tissue (iWAT) than the IA group, which was associated with impaired adaptive thermogenesis. In response to CL, ID mice showed decreased heat production (P < 0.01) and defective upregulation of beige adipocyte-specific markers, including uncoupling protein 1 (41.1%, P < 0.001), transferrin receptor 1 (47.5%, P < 0.001), and mitochondrial respiratory chain complexes (P < 0.05) compared with IA mice. CONCLUSIONS Dietary iron deficiency deregulates iron balance in the iWAT and impairs adaptive thermogenesis, thereby escalating the diet-induced weight gain in C57BL/6 mice.
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Affiliation(s)
- Jin-Seon Yook
- Department of Nutrition, University of Massachusetts, Amherst, MA, USA
| | | | - Ashley Mulcahy Toney
- Department of Nutrition and Health Sciences, University of Nebraska–Lincoln, Lincoln, NE, USA
| | - Mikyoung You
- Department of Nutrition, University of Massachusetts, Amherst, MA, USA
| | - Young-Cheul Kim
- Department of Nutrition, University of Massachusetts, Amherst, MA, USA
| | - Zhenhua Liu
- Department of Nutrition, University of Massachusetts, Amherst, MA, USA
| | - Jaekwon Lee
- Department of Biochemistry, University of Nebraska–Lincoln, Lincoln, NE, USA
| | - Soonkyu Chung
- Department of Nutrition, University of Massachusetts, Amherst, MA, USA
- Department of Nutrition and Health Sciences, University of Nebraska–Lincoln, Lincoln, NE, USA
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9
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Kindi H, Menzel M, Heilmann A, Schmelzer CEH, Herzberg M, Fuhrmann B, Gallego-Ferrer G, Groth T. Effect of metal ions on the physical properties of multilayers from hyaluronan and chitosan, and the adhesion, growth and adipogenic differentiation of multipotent mouse fibroblasts. SOFT MATTER 2021; 17:8394-8410. [PMID: 34550141 DOI: 10.1039/d1sm00405k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Polyelectrolyte multilayers (PEMs) consisting of the polysaccharides hyaluronic acid (HA) as the polyanion and chitosan (Chi) as the polycation were prepared with layer-by-layer technique (LbL). The [Chi/HA]5 multilayers were exposed to solutions of metal ions (Ca2+, Co2+, Cu2+ and Fe3+). Binding of metal ions to [Chi/HA]5 multilayers by the formation of complexes with functional groups of polysaccharides modulates their physical properties and the bioactivity of PEMs with regard to the adhesion and function of multipotent murine C3H10T1/2 embryonic fibroblasts. Characterization of multilayer formation and surface properties using different analytical methods demonstrates changes in the wetting, surface potential and mechanical properties of multilayers depending on the concentration and type of metal ion. Most interestingly, it is observed that Fe3+ metal ions greatly promote adhesion and spreading of C3H10T1/2 cells on the low adhesive [Chi/HA]5 PEM system. The application of intermediate concentrations of Cu2+, Ca2+ and Co2+ as well as low concentrations of Fe3+ to PEMs also results in increased cell spreading. Moreover, it can be shown that complex formation of PEMs with Cu2+ and Fe3+ ions leads to increased metabolic activity in cells after 24 h and induces cell differentiation towards adipocytes in the absence of any additional adipogenic media supplements. Overall, complex formation of [Chi/HA]5 PEM with metal ions like Cu2+ and Fe3+ represents an interesting and cheap alternative to the use of growth factors for making cell-adhesive coatings and guiding stem cell differentiation on implants and scaffolds to regenerate connective-type of tissues.
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Affiliation(s)
- Husnia Kindi
- Department Biomedical Materials, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany.
| | - Matthias Menzel
- Department of Biological and Macromolecular Materials, Fraunhofer Institute for Microstructure of Materials and Systems IMWS, 06120 Halle (Saale), Germany
| | - Andreas Heilmann
- Department of Biological and Macromolecular Materials, Fraunhofer Institute for Microstructure of Materials and Systems IMWS, 06120 Halle (Saale), Germany
| | - Christian E H Schmelzer
- Department of Biological and Macromolecular Materials, Fraunhofer Institute for Microstructure of Materials and Systems IMWS, 06120 Halle (Saale), Germany
| | - Martin Herzberg
- Molecular Microbiology, Institute for Biology/Microbiology, Martin-Luther-University, Halle-Wittenberg, Germany
| | - Bodo Fuhrmann
- Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale), Germany
- Interdisciplinary Center of Materials Science, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
| | - Gloria Gallego-Ferrer
- Centre for Biomaterials and Tissue Engineering, Universitat Politècnica de València, Caminode Veras/n, 46022 Valencia, Spain
- Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 46022 Valencia, Spain
| | - Thomas Groth
- Department Biomedical Materials, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany.
- Interdisciplinary Center of Materials Science, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany
- Laboratory of Biomedical Nanotechnologies, Institute of Bionic Technologies and Engineering, I.M. Sechenov First Moscow State University, 119991, Trubetskaya street 8, Moscow, Russian Federation
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10
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Yook JS, You M, Kim Y, Zhou M, Liu Z, Kim YC, Lee J, Chung S. The thermogenic characteristics of adipocytes are dependent on the regulation of iron homeostasis. J Biol Chem 2021; 296:100452. [PMID: 33631196 PMCID: PMC8010711 DOI: 10.1016/j.jbc.2021.100452] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/09/2021] [Accepted: 02/18/2021] [Indexed: 12/15/2022] Open
Abstract
The development of thermogenic adipocytes concurs with mitochondrial biogenesis, an iron-dependent pathway. Iron regulatory proteins (IRP) 1 and 2 are RNA-binding proteins that regulate intracellular iron homeostasis. IRPs bind to the iron-response element (IRE) of their target mRNAs, balancing iron uptake and deposition at the posttranscriptional levels. However, IRP/IRE-dependent iron regulation in adipocytes is largely unknown. We hypothesized that iron demands are higher in brown/beige adipocytes than white adipocytes to maintain the thermogenic mitochondrial capacity. To test this hypothesis, we investigated the IRP/IRE regulatory system in different depots of adipose tissue. Our results revealed that 1) IRP/IRE interaction was increased in proportional to the thermogenic function of the adipose depot, 2) adipose iron content was increased in adipose tissue browning upon β3-adrenoceptor stimulation, while decreased in thermoneutral conditions, and 3) modulation of iron content was linked with mitochondrial biogenesis. Moreover, the iron requirement was higher in HIB1B brown adipocytes than 3T3-L1 white adipocytes during differentiation. The reduction of the labile iron pool (LIP) suppressed the differentiation of brown/beige adipocytes and mitochondrial biogenesis. Using the 59Fe-Tf, we also demonstrated that thermogenic stimuli triggered cell-autonomous iron uptake and mitochondrial compartmentalization as well as enhanced mitochondrial respiration. Collectively, our work demonstrated that IRP/IRE signaling and subsequent adaptation in iron metabolism are a critical determinant for the thermogenic function of adipocytes.
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Affiliation(s)
- Jin-Seon Yook
- Department of Nutrition and Health Sciences, University of Massachusetts, Amherst, Massachusetts, USA
| | - Mikyoung You
- Department of Nutrition and Health Sciences, University of Massachusetts, Amherst, Massachusetts, USA
| | - Yongeun Kim
- Department of Nutrition and Health Sciences, University of Nebraska, Lincoln, Nebraska, USA
| | - Mi Zhou
- Department of Nutrition and Health Sciences, University of Nebraska, Lincoln, Nebraska, USA
| | - Zhenhua Liu
- Department of Nutrition and Health Sciences, University of Massachusetts, Amherst, Massachusetts, USA
| | - Young-Cheul Kim
- Department of Nutrition and Health Sciences, University of Massachusetts, Amherst, Massachusetts, USA
| | - Jaekwon Lee
- Department of Biochemistry, University of Nebraska, Lincoln, Nebraska, USA
| | - Soonkyu Chung
- Department of Nutrition and Health Sciences, University of Massachusetts, Amherst, Massachusetts, USA; Department of Nutrition and Health Sciences, University of Nebraska, Lincoln, Nebraska, USA.
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11
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Development of insulin resistance preceded major changes in iron homeostasis in mice fed a high-fat diet. J Nutr Biochem 2020; 84:108441. [PMID: 32629238 PMCID: PMC7115812 DOI: 10.1016/j.jnutbio.2020.108441] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 03/10/2020] [Accepted: 05/22/2020] [Indexed: 02/06/2023]
Abstract
Type 2 diabetes mellitus (T2DM) and insulin resistance (IR) have been associated with dysregulation of iron metabolism. The basis for this association is not completely understood. To attempt to investigate this, we studied temporal associations between onset of insulin resistance (IR) and dysregulated iron homeostasis, in a mouse model of T2DM. Male C57Bl/6 mice (aged 8 weeks) were fed a high-fat diet (HFD; 60% energy from fat) or a control diet (CD; 10% energy from fat) for 4, 8, 12, 16, 20 and 24 weeks. Development of IR was documented, and various metabolic, inflammatory and iron-related parameters were studied in these mice. HFD-feeding induced weight gain, hepato-steatosis and IR in the mice. Onset of IR occurred from 12 weeks onwards. Hepatic iron stores progressively declined from 16 weeks onwards. Accompanying changes included a decrease in hepatic hepcidin (Hamp1) mRNA expression and serum hepcidin levels and an increase in iron content in the epididymal white adipose tissue (eWAT). Iron content in the liver negatively correlated with that in the eWAT. Factors known to regulate hepatic Hamp1 expression (such as serum iron levels, systemic inflammation, and bone marrow-derived erythroid regulators) were not affected by HFD-feeding. In conclusion, the results show that the onset of IR in HFD-fed mice preceded dysregulation of iron homeostasis, evidence of which were found both in the liver and visceral adipose tissue.
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Orliaguet L, Dalmas E, Drareni K, Venteclef N, Alzaid F. Mechanisms of Macrophage Polarization in Insulin Signaling and Sensitivity. Front Endocrinol (Lausanne) 2020; 11:62. [PMID: 32140136 PMCID: PMC7042402 DOI: 10.3389/fendo.2020.00062] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 01/30/2020] [Indexed: 12/11/2022] Open
Abstract
Type-2 diabetes (T2D) is a disease of two etiologies: metabolic and inflammatory. At the cross-section of these etiologies lays the phenomenon of metabolic inflammation. Whilst metabolic inflammation is characterized as systemic, a common starting point is the tissue-resident macrophage, who's successful physiological or aberrant pathological adaptation to its microenvironment determines disease course and severity. This review will highlight the key mechanisms in macrophage polarization, inflammatory and non-inflammatory signaling that dictates the development and progression of insulin resistance and T2D. We first describe the known homeostatic functions of tissue macrophages in insulin secreting and major insulin sensitive tissues. Importantly we highlight the known mechanisms of aberrant macrophage activation in these tissues and the ways in which this leads to impairment of insulin sensitivity/secretion and the development of T2D. We next describe the cellular mechanisms that are known to dictate macrophage polarization. We review recent progress in macrophage bio-energetics, an emerging field of research that places cellular metabolism at the center of immune-effector function. Importantly, following the advent of the metabolically-activated macrophage, we cover the known transcriptional and epigenetic factors that canonically and non-canonically dictate macrophage differentiation and inflammatory polarization. In closing perspectives, we discuss emerging research themes and highlight novel non-inflammatory or non-immune roles that tissue macrophages have in maintaining microenvironmental and systemic homeostasis.
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Affiliation(s)
- Lucie Orliaguet
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
| | - Elise Dalmas
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
| | - Karima Drareni
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA, United States
| | - Nicolas Venteclef
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
| | - Fawaz Alzaid
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
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Tomay F, Marinelli A, Leoni V, Caccia C, Matros A, Mock HP, Tonelli C, Petroni K. Purple corn extract induces long-lasting reprogramming and M2 phenotypic switch of adipose tissue macrophages in obese mice. J Transl Med 2019; 17:237. [PMID: 31337415 PMCID: PMC6651915 DOI: 10.1186/s12967-019-1972-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/05/2019] [Indexed: 02/08/2023] Open
Abstract
Background Obesity is a chronic and systemic inflammatory disorder and an important risk factor for the onset of several chronic syndromes. Adipose tissue (AT) plays a crucial role in the development of obesity, promoting the infiltration and accumulation of leukocytes in the tissue and sustaining adipocyte expansion. Anthocyanins exert a broad range of health benefits, but their effect in improving obesity-related inflammation in vivo has been poorly characterized. We examined the effects of a purple corn cob extract in the context of AT inflammation in a murine diet-induced obesity (DIO) model. Methods Male C57BL/6J mice were subjected to control diet (CTR + H2O), high fat diet (HF + H2O) or high fat diet plus purple corn extract (HF + RED) for 12 weeks. Blood glucose, AT, and liver gene expression, metabolism, biochemistry, and histology were analysed and flow cytometry was performed on AT leukocytes and Kupffer cells. Results RED extract intake resulted in lower MCP-1 mediated recruitment and proliferation of macrophages into crown-like structures in the AT. AT macrophages (ATM) of HF + RED group upregulated M2 markers (ArgI, Fizz1, TGFβ), downregulating inflammatory mediators (TNF-α, IL-6, IL-1β, COX-2) thanks to the suppression of NF-kB signalling. ATM also increased the expression of iron metabolism-related genes (FABP4, Hmox1, Ferroportin, CD163, TfR1, Ceruloplasmin, FtL1, FtH1) associated with a reduction in iron storage and increased turnover. ATM from HF + RED mice did not respond to LPS treatment ex vivo, confirming the long-lasting effects of the treatment on M2 polarization. Adipocytes of HF + RED group improved lipid metabolism and displayed a lower inflammation grade. Liver histology revealed a remarkable reduction of steatosis in the HF + RED group, and Kupffer cell profiling displayed a marked switch towards the M2 phenotype. Conclusions RED extract attenuated AT inflammation in vivo, with a long-lasting reprogramming of ATM and adipocyte profiles towards the anti-inflammatory phenotype, therefore representing a valuable supplement in the context of obesity-associated disorders. Electronic supplementary material The online version of this article (10.1186/s12967-019-1972-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Federica Tomay
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy
| | | | - Valerio Leoni
- Laboratory of Clinical Chemistry, Hospital of Varese, ASST-Settelaghi, Varese, Italy
| | - Claudio Caccia
- Laboratory of Clinical Pathology and Human Genetics, Foundation IRCCS Carlo Besta, Milan, Italy
| | - Andrea Matros
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany.,School of Agriculture, Food and Wine, University of Adelaide, Adelaide, Australia
| | - Hans-Peter Mock
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | - Chiara Tonelli
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy.
| | - Katia Petroni
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy.
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Adamska A, Łebkowska A, Krentowska A, Adamski M, Kowalska I. The Association Between Serum Ferritin Concentration and Visceral Adiposity Estimated by Whole-Body DXA Scan in Women With Polycystic Ovary Syndrome. Front Endocrinol (Lausanne) 2019; 10:873. [PMID: 31969861 PMCID: PMC6960176 DOI: 10.3389/fendo.2019.00873] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 11/28/2019] [Indexed: 12/23/2022] Open
Abstract
Objective: Women with polycystic ovary syndrome (PCOS) are characterized by insulin resistance and higher prevalence of obesity. Serum ferritin is increased in obesity and is associated with insulin resistance. The aim of the present study was to evaluate the relationships between serum ferritin concentration with insulin resistance and body composition estimated by dual-energy X-ray absorptiometry (DXA) in PCOS women in comparison to the control group. Patients and Methods: One hundred four women were enrolled to the study-65 women with PCOS and 39 women matched for age and BMI as a control group. Serum ferritin concentration and oral glucose tolerance test (OGTT) were performed. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. DXA was performed to estimate fat, fat-free mass, and visceral adipose tissue (VAT). Results: Women with PCOS have higher serum concentration of ferritin (p = 0.002), insulin at baseline (p = 0.03), at 60 min of OGTT (p = 0.01), at 120 min of OGTT (p = 0.004), HOMA-IR (p = 0.03), and VAT (p = 0.0001) in comparison to the control group. We observed a relationship of serum ferritin with insulin concentration at baseline (r = 0.25, p = 0.04) and at 120 min of OGTT (r = 0.31, p = 0.01) and with HOMA-IR (r = 0.30, p = 0.01) in the PCOS group. We noticed an association between serum ferritin concentration and VAT (r = 0.42, p = 0.001), trunk fat mass (r = 0.25, p = 0.04), and android fat mass (r = 0.25, p = 0.04) in the PCOS group. Multiple regression analysis revealed that ferritin (p = 0.02, β = 0.17), insulin at baseline (p = 0.001, β = 0.30), glucose at the 120 min of OGTT (p = 0.007, β = 0.26), and triglycerides (p = 0.001, β = 0.33) were independent predictors of VAT amount in PCOS women. Conclusions: Elevated serum ferritin concentration is connected with insulin resistance as well as with DXA-estimated VAT, android, and trunk fat mass in PCOS women, and could be a marker of metabolic dysfunction.
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Affiliation(s)
- Agnieszka Adamska
- Department of Endocrinology, Diabetology and Internal Medicine, Medical University of Białystok, Białystok, Poland
- *Correspondence: Agnieszka Adamska
| | - Agnieszka Łebkowska
- Department of Internal Medicine and Metabolic Diseases, Medical University of Białystok, Białystok, Poland
| | - Anna Krentowska
- Department of Internal Medicine and Metabolic Diseases, Medical University of Białystok, Białystok, Poland
| | - Marcin Adamski
- Faculty of Computer Science, Bialystok University of Technology, Białystok, Poland
| | - Irina Kowalska
- Department of Internal Medicine and Metabolic Diseases, Medical University of Białystok, Białystok, Poland
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Sukhbaatar N, Weichhart T. Iron Regulation: Macrophages in Control. Pharmaceuticals (Basel) 2018; 11:ph11040137. [PMID: 30558109 PMCID: PMC6316009 DOI: 10.3390/ph11040137] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/10/2018] [Accepted: 12/12/2018] [Indexed: 12/21/2022] Open
Abstract
Macrophages are sentinel cells of the innate immune system and have important functions in development, tissue homeostasis, and immunity. These phylogenetically ancient cells also developed a variety of mechanisms to control erythropoiesis and the handling of iron. Red pulp macrophages in the spleen, Kupffer cells in the liver, and central nurse macrophages in the bone marrow ensure a coordinated metabolism of iron to support erythropoiesis. Phagocytosis of senescent red blood cells by macrophages in the spleen and the liver provide a continuous delivery of recycled iron under steady-state conditions and during anemic stress. Central nurse macrophages in the bone marrow utilize this iron and provide a cellular scaffold and niche to promote differentiation of erythroblasts. This review focuses on the role of the distinct macrophage populations that contribute to efficient iron metabolism and highlight important cellular and systemic mechanisms involved in iron-regulating processes.
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Affiliation(s)
- Nyamdelger Sukhbaatar
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Vienna 1090, Austria.
| | - Thomas Weichhart
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Vienna 1090, Austria.
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Hamedi Asl D, Naserpour Farivar T, Rahmani B, Hajmanoochehri F, Emami Razavi AN, Jahanbin B, Soleimani Dodaran M, Peymani A. The role of transferrin receptor in the Helicobacter pylori pathogenesis; L-ferritin as a novel marker for intestinal metaplasia. Microb Pathog 2018; 126:157-164. [PMID: 30391537 DOI: 10.1016/j.micpath.2018.10.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 10/25/2018] [Accepted: 10/30/2018] [Indexed: 12/13/2022]
Abstract
Helicobacter pylori growth requirements is a prerequisite to invade gastric epithelium and the process of injury to gastric cells will eventually lead to gastric cancer. The aim of this study is to investigate the effect of iron challenge on the expression of genes involved in iron homeostasis. The presence of Phosphoglucosamine mutase (glmM), cytotoxin-associated gene A (cagA) and vacuolating cytotoxin A (vacA) genes and mRNA expression of Iron Regulatory Protein 2 (IRP2), Transferrin Receptor (TFRC) and Ferritin Light Chain (FTL) genes in samples of 28 normal gastric mucosa, 33 chronic gastritis, 29 gastritis with intestinal metaplasia, 29 intestinal type adenocarcinoma patients were examined by real-time PCR. Immunohistochemistry was used to analyze cellular localization and protein levels. In the all H. pylori positive tissues, particularly in the basal regions of foveolar cells, TFRC was overexpressed (P < 0.05), and regardless of the H. pylori infection, FTL was overexpressed in all patient, exclusively in metaplastic glandular cells (P < 0.05). Furthermore, overexpression of IRP2 was associated with H. pylori positive chronic gastritis and intestinal metaplasia (P < 0.05). Our findings confirm the role of transferrin receptor in H. pylori attachment into the gastric mucosa to capture iron. Overexpression of FTL gene in metaplastic cells could be considered as a research background to investigate the role of this gene in the differentiation of gastric cells into intestinal metaplasia. In addition, this gene could be suggested as a diagnostic marker to be included among the other markers routinely performed by clinical diagnostic laboratories.
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Affiliation(s)
- Dariush Hamedi Asl
- Department of Molecular Medicine, Faculty of Medical Sciences, Qazvin University of Medical Sciences, Qazvin, Iran
| | | | - Babak Rahmani
- Department of Molecular Medicine, Faculty of Medical Sciences, Qazvin University of Medical Sciences, Qazvin, Iran
| | | | - Amir Nader Emami Razavi
- Iran National Tumor Bank, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran
| | - Behnaz Jahanbin
- Department of Pathology, Cancer Research Institute, Tehran University of Medical, Tehran, Iran
| | | | - Amir Peymani
- Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran.
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Adipocyte Model of Mycobacterium tuberculosis Infection Reveals Differential Availability of Iron to Bacilli in the Lipid-Rich Caseous Environment. Infect Immun 2018; 86:IAI.00041-18. [PMID: 29632245 PMCID: PMC5964510 DOI: 10.1128/iai.00041-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 03/28/2018] [Indexed: 12/18/2022] Open
Abstract
Mycobacterium tuberculosis, a successful human pathogen, utilizes multiple carbon sources from the host but adapts to a fatty-acid-rich environment in vivo. We sought to delineate the physiologic response of M. tuberculosis to a lipid-rich environment by using differentiated adipocytes as a model system. Global transcriptome profiling based on RNA sequencing was performed for bacilli from infected adipocytes and preadipocytes. Genes involved in de novo fatty acid synthesis were downregulated, while those predicted to be involved in triglyceride biosynthesis were upregulated, in bacilli isolated from adipocytes, indicating reliance on host-derived fatty acids. Transcription factor network analysis indicated suppression of IdeR-regulated genes, suggesting decreased iron uptake by M. tuberculosis in the adipocyte model. This suppression of iron uptake coincided with higher ferritin and iron levels in adipocytes than in preadipocytes. In accord with the role of iron in mediating oxidative stress, we observed upregulation of genes involved in mitigating oxidative stress in M. tuberculosis isolated from adipocytes. We provide evidence that oleic acid, a major host-derived fatty acid, helps reduce the bacterial cytoplasm, thereby providing a safe haven for an M. tuberculosis mutant that is sensitive to iron-mediated oxidative stress. Via an independent mechanism, host ferritin is also able to rescue the growth of this mutant. Our work highlights the inherent synergy between macronutrients and micronutrients of the host environment that converge to provide resilience to the pathogen. This complex synergy afforded by the adipocyte model of infection will aid in the identification of genes required by M. tuberculosis in a caseous host environment.
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18
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Li B, Qiao L, An L, Wang W, Liu J, Ren Y, Pan Y, Jing J, Liu W. Transcriptome analysis of adipose tissues from two fat-tailed sheep breeds reveals key genes involved in fat deposition. BMC Genomics 2018; 19:338. [PMID: 29739312 PMCID: PMC5941690 DOI: 10.1186/s12864-018-4747-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/30/2018] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The level of fat deposition in carcass is a crucial factor influencing meat quality. Guangling Large-Tailed (GLT) and Small-Tailed Han (STH) sheep are important local Chinese fat-tailed breeds that show distinct patterns of fat depots. To gain a better understanding of fat deposition, transcriptome profiles were determined by RNA-sequencing of perirenal, subcutaneous, and tail fat tissues from both the sheep breeds. The common highly expressed genes (co-genes) in all the six tissues, and the genes that were differentially expressed (DE genes) between these two breeds in the corresponding tissues were analyzed. RESULTS Approximately 47 million clean reads were obtained for each sample, and a total of 17,267 genes were annotated. Of the 47 highly expressed co-genes, FABP4, ADIPOQ, FABP5, and CD36 were the four most highly transcribed genes among all the known genes related to adipose deposition. FHC, FHC-pseudogene, and ZC3H10 were also highly expressed genes and could, thus, have roles in fat deposition. A total of 2091, 4233, and 4131 DE genes were identified in the perirenal, subcutaneous, and tail fat tissues between the GLT and STH breeds, respectively. Gene Ontology (GO) analysis showed that some DE genes were associated with adipose metabolism. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that PPAR signaling pathway and ECM-receptor interaction were specifically enriched. Four genes, namely LOC101102230, PLTP, C1QTNF7, and OLR1 were up-regulated and two genes, SCD and UCP-1, were down-regulated in all the tested tissues of STH. Among the genes involved in ECM-receptor interaction, the genes encoding collagens, laminins, and integrins were quite different depending on the depots or the breeds. In STH, genes such as LAMB3, RELN, TNXB, and ITGA8, were identified to be up regulated and LAMB4 was observed to be down regulated. CONCLUSIONS This study unravels the complex transcriptome profiles in sheep fat tissues, highlighting the candidate genes involved in fat deposition. Further studies are needed to investigate the roles of the candidate genes in fat deposition and in determining the meat quality of sheep.
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Affiliation(s)
- Baojun Li
- Shanxi Agricultural University, College of Veterinary and Animal Science, Taigu, 030801, China
| | - Liying Qiao
- Shanxi Agricultural University, College of Veterinary and Animal Science, Taigu, 030801, China
| | - Lixia An
- Shanxi Agricultural University, College of Information, Taigu, 030800, China
| | - Weiwei Wang
- Shanxi Agricultural University, College of Veterinary and Animal Science, Taigu, 030801, China
| | - Jianhua Liu
- Shanxi Agricultural University, College of Veterinary and Animal Science, Taigu, 030801, China
| | - Youshe Ren
- Shanxi Agricultural University, College of Veterinary and Animal Science, Taigu, 030801, China
| | - Yangyang Pan
- Shanxi Agricultural University, College of Veterinary and Animal Science, Taigu, 030801, China
| | - Jiongjie Jing
- Shanxi Agricultural University, College of Veterinary and Animal Science, Taigu, 030801, China
| | - Wenzhong Liu
- Shanxi Agricultural University, College of Veterinary and Animal Science, Taigu, 030801, China.
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Jiang C, Wu D, Haacke EM. Ferritin-EGFP Chimera as an Endogenous Dual-Reporter for Both Fluorescence and Magnetic Resonance Imaging in Human Glioma U251 Cells. ACTA ACUST UNITED AC 2017; 3:1-8. [PMID: 30042970 PMCID: PMC6024424 DOI: 10.18383/j.tom.2015.00181] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A unique hybrid protein ferritin–enhanced green fluorescent protein (EGFP) was built to serve as an endogenous dual reporter for both fluorescence and magnetic resonance imaging (MRI). It consists of a human ferritin heavy chain (an iron-storage protein) at the N terminus, a flexible polypeptide in the middle as a linker, and an EGFP at the C terminus. Through antibiotic screening, we established stable human glioma U251 cell strains that expressed ferritin–EGFP under the control of tetracycline. These cells emitted bright green fluorescence and were easily detected by a fluorescent microscope. Ferritin–EGFP overexpression proved effective in triggering obvious intracellular iron accumulation as shown by Prussian blue staining and by MRI. Further, we found that ferritin–EGFP overexpression did not cause proliferation differences between experimental and control group cells when ferritin–EGFP was expressed for <96 hours. Application of this novel ferritin–EGFP chimera has a promising future for combined optical and MRI approaches to study in vivo imaging at a cellular level.
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Affiliation(s)
- Caihong Jiang
- Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China and
| | - Dongmei Wu
- Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China and
| | - E Mark Haacke
- Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai, China and.,Department of Radiology, Wayne State University, Detroit, Michigan
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20
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Ma X, Pham VT, Mori H, MacDougald OA, Shah YM, Bodary PF. Iron elevation and adipose tissue remodeling in the epididymal depot of a mouse model of polygenic obesity. PLoS One 2017. [PMID: 28651003 PMCID: PMC5484604 DOI: 10.1371/journal.pone.0179889] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Background Iron dysregulation is a potential contributor to the pathology of obesity-related metabolic complications. KK/HIJ (KK) mice, a polygenic obese mouse model, have elevated serum iron levels. A subset of KK male mice display a bronzing of epididymal adipose tissue (eAT) associated with >100-fold (p<0.001) higher iron concentration. Methods To further phenotype and characterize the adipose tissue iron overload, 27 male KK mice were evaluated. 14 had bronzing eAT and 13 had normal appearing eAT. Fasting serum and tissues were collected for iron content, qPCR, histology and western blot. Results High iron levels were confirmed in bronzing eAT (High Iron group, HI) versus normal iron level (NI) in normal appearing eAT. Surprisingly, iron levels in subcutaneous and brown adipose depots were not different between the groups (p>0.05). The eAT histology revealed iron retention, macrophage clustering, tissue fibrosis, cell death as well as accumulation of HIF-2α in the high iron eAT. qPCR showed significantly decreased Lep (leptin) and AdipoQ (adiponectin), whereas Tnfα (tumor necrosis factor α), and Slc40a1 (ferroportin) were up-regulated in HI (p<0.05). Elevated HIF-2α, oxidative stress and local insulin signaling loss was also observed. Significance Our data suggest that deposition of iron in adipose tissue is limited to the epididymal depot in male KK mice. A robust adipose tissue remodeling is concomitant with the high iron concentration, which causes local adipose tissue insulin resistance.
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Affiliation(s)
- Xiaoya Ma
- School of Kinesiology, University of Michigan, 1402 Washington Hts., Ann Arbor, MI, United States of America
- Department of Molecular & Integrative Physiology, Ann Arbor, MI, United States of America
| | - Vinh T. Pham
- School of Kinesiology, University of Michigan, 1402 Washington Hts., Ann Arbor, MI, United States of America
| | - Hiroyuki Mori
- Department of Molecular & Integrative Physiology, Ann Arbor, MI, United States of America
| | - Ormond A. MacDougald
- Department of Molecular & Integrative Physiology, Ann Arbor, MI, United States of America
- Internal Medicine, University of Michigan Medical School, Ann Arbor MI, United States of America
| | - Yatrik M. Shah
- Department of Molecular & Integrative Physiology, Ann Arbor, MI, United States of America
- Internal Medicine, University of Michigan Medical School, Ann Arbor MI, United States of America
| | - Peter F. Bodary
- School of Kinesiology, University of Michigan, 1402 Washington Hts., Ann Arbor, MI, United States of America
- * E-mail:
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21
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Backe MB, Moen IW, Ellervik C, Hansen JB, Mandrup-Poulsen T. Iron Regulation of Pancreatic Beta-Cell Functions and Oxidative Stress. Annu Rev Nutr 2016; 36:241-73. [PMID: 27146016 DOI: 10.1146/annurev-nutr-071715-050939] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dietary advice is the cornerstone in first-line treatment of metabolic diseases. Nutritional interventions directed at these clinical conditions mainly aim to (a) improve insulin resistance by reducing energy-dense macronutrient intake to obtain weight loss and (b) reduce fluctuations in insulin secretion through avoidance of rapidly absorbable carbohydrates. However, even in the majority of motivated patients selected for clinical trials, massive efforts using this approach have failed to achieve lasting efficacy. Less attention has been given to the role of micronutrients in metabolic diseases. Here, we review the evidence that highlights (a) the importance of iron in pancreatic beta-cell function and dysfunction in diabetes and (b) the integrative pathophysiological effects of tissue iron levels in the interactions among the beta cell, gut microbiome, hypothalamus, innate and adaptive immune systems, and insulin-sensitive tissues. We propose that clinical trials are warranted to clarify the impact of dietary or pharmacological iron reduction on the development of metabolic disorders.
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Affiliation(s)
- Marie Balslev Backe
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark;
| | - Ingrid Wahl Moen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark;
| | - Christina Ellervik
- Department of Laboratory Medicine, Boston Children's Hospital, Boston, Massachusetts 02115
| | - Jakob Bondo Hansen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark;
| | - Thomas Mandrup-Poulsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark;
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22
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Fernández-Real JM, Blasco G, Puig J, Moreno M, Xifra G, Sánchez-Gonzalez J, Maria Alustiza J, Pedraza S, Ricart W, María Moreno-Navarrete J. Adipose tissue R2* signal is increased in subjects with obesity: A preliminary MRI study. Obesity (Silver Spring) 2016; 24:352-8. [PMID: 26813526 DOI: 10.1002/oby.21347] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 08/28/2015] [Accepted: 08/29/2015] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Circulating and adipose tissue markers of iron overload are increased in subjects with obesity. The aim is to study iron signals in adipose tissue. METHODS Adipose tissue R2* values and hepatic iron concentration (HIC) were evaluated using magnetic resonance imaging (MRI) in 23 middle-aged subjects with obesity and 20 subjects without obesity. RESULTS Subcutaneous (SAT) and visceral adipose tissue (VAT) R2* were increased in subjects with obesity (P = 0.004 and P = 0.008) and correlated significantly and positively with HIC in all subjects. Strikingly, most of the associations of liver iron with metabolic parameters were replicated with SAT and VAT R2*. BMI, waist circumference, fat mass, HOMA value, and C-reactive protein positively correlated with HIC and SAT and VAT R2*. BMI or percent fat mass (but not insulin resistance) contributed independently to 26.8-34.8% of the variance in sex- and age-adjusted SAT or VAT R2* (β > 0.40, P < 0.005). Within subjects with obesity, total cholesterol independently contributed to 14.8% of sex- and age-adjusted VAT iron variance (β = 0.50, P = 0.025). CONCLUSIONS Increased R2* in adipose tissue, which might indicate iron content, runs in parallel to liver iron stores of subjects with obesity. VAT iron seems also associated with serum cholesterol within subjects with obesity.
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Affiliation(s)
- José Manuel Fernández-Real
- Department of Diabetes, Endocrinology and Nutrition, Institut D'investigació Biomèdica De Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto De Salud Carlos III (ISCIII), Girona, Spain
| | - Gerard Blasco
- Department of Radiology, Girona Biomedical Research Institute (IDIBGI)-Diagnostic Imaging Institute (IDI), Girona, Spain
| | - Josep Puig
- Department of Radiology, Girona Biomedical Research Institute (IDIBGI)-Diagnostic Imaging Institute (IDI), Girona, Spain
| | - Maria Moreno
- Department of Diabetes, Endocrinology and Nutrition, Institut D'investigació Biomèdica De Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto De Salud Carlos III (ISCIII), Girona, Spain
| | - Gemma Xifra
- Department of Diabetes, Endocrinology and Nutrition, Institut D'investigació Biomèdica De Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto De Salud Carlos III (ISCIII), Girona, Spain
| | | | - Jose Maria Alustiza
- Department of Liver and Gastrointestinal Diseases, Biodonostia Research Institute, Donostia University Hospital (HUD), University of the Basque Country (UPV/EHU), San Sebastian, Spain
| | - Salvador Pedraza
- Department of Radiology, Girona Biomedical Research Institute (IDIBGI)-Diagnostic Imaging Institute (IDI), Girona, Spain
| | - Wifredo Ricart
- Department of Diabetes, Endocrinology and Nutrition, Institut D'investigació Biomèdica De Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto De Salud Carlos III (ISCIII), Girona, Spain
| | - José María Moreno-Navarrete
- Department of Diabetes, Endocrinology and Nutrition, Institut D'investigació Biomèdica De Girona (IdIBGi), CIBEROBN (CB06/03/010) and Instituto De Salud Carlos III (ISCIII), Girona, Spain
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Fernández-Real JM, McClain D, Manco M. Mechanisms Linking Glucose Homeostasis and Iron Metabolism Toward the Onset and Progression of Type 2 Diabetes. Diabetes Care 2015; 38:2169-76. [PMID: 26494808 DOI: 10.2337/dc14-3082] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The bidirectional relationship between iron metabolism and glucose homeostasis is increasingly recognized. Several pathways of iron metabolism are modified according to systemic glucose levels, whereas insulin action and secretion are influenced by changes in relative iron excess. We aimed to update the possible influence of iron on insulin action and secretion and vice versa. RESEARCH DESIGN AND METHODS The mechanisms that link iron metabolism and glucose homeostasis in the main insulin-sensitive tissues and insulin-producing β-cells were revised according to their possible influence on the development of type 2 diabetes (T2D). RESULTS The mechanisms leading to dysmetabolic hyperferritinemia and hepatic overload syndrome were diverse, including diet-induced alterations in iron absorption, modulation of gluconeogenesis, heme-mediated disruption of circadian glucose rhythm, impaired hepcidin secretion and action, and reduced copper availability. Glucose metabolism in adipose tissue seems to be affected by both iron deficiency and excess through interaction with adipocyte differentiation, tissue hyperplasia and hypertrophy, release of adipokines, lipid synthesis, and lipolysis. Reduced heme synthesis and dysregulated iron uptake or export could also be contributing factors affecting glucose metabolism in the senescent muscle, whereas exercise is known to affect iron and glucose status. Finally, iron also seems to modulate β-cells and insulin secretion, although this has been scarcely studied. CONCLUSIONS Iron is increasingly recognized to influence glucose metabolism at multiple levels. Body iron stores should be considered as a potential target for therapy in subjects with T2D or those at risk for developing T2D. Further research is warranted.
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Affiliation(s)
- José Manuel Fernández-Real
- University Hospital of Girona "DrJosepTrueta," Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona (IdIBGi), Girona, Spain CIBER Fisiopatología de la Obesidad y Nutrición, Girona, Spain
| | - Donald McClain
- Departments of Biochemistry and Internal Medicine, University of Utah, Salt Lake City, UT Veterans Administration Research Service, Salt Lake City VAHCS, Salt Lake City, UT
| | - Melania Manco
- Bambino Gesù Children's Hospital and Research Institute, Research Unit for Multifactorial Disease, Rome, Italy
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Guglielmi V, D'Adamo M, Bellia A, Ciotto RT, Federici M, Lauro D, Sbraccia P. Iron status in obesity: An independent association with metabolic parameters and effect of weight loss. Nutr Metab Cardiovasc Dis 2015; 25:541-547. [PMID: 25843660 DOI: 10.1016/j.numecd.2015.02.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 02/23/2015] [Accepted: 02/23/2015] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND AIMS Growing evidence has shown that ferritin concentrations are associated with obesity and insulin resistance, and with nonalcoholic fatty liver disease. However, it is unclear whether ferritin is simply an inflammatory marker, or it may directly contribute to the pathogenesis of obesity-related metabolic alterations. The aim of our study was to investigate the independent associations of ferritin levels with metabolic parameters in overweight/obese subjects before and after hypocaloric diet-induced weight changes. METHODS AND RESULTS A sample study of 48 premenopausal, 39 postmenopausal women and 50 men was retrospectively analyzed. Clinical, bioimpedentiometry and biochemical data from baseline evaluations and after 3, 6 and 12 months of hypocaloric diet were collected. In the whole sample study, the baseline values of ferritin concentrations were positively correlated with body mass index (BMI) (r = 0.21, p < 0.05) and mass body fat (MBF) (r = 0.26, p < 0.05), whereas the serum iron level was negatively correlated with MBF (r = -0.29, p < 0.05). In premenopausal women, BMI-adjusted ferritin concentrations were negatively associated with high-density lipoprotein-cholesterol and positively related with triglycerides and aspartate aminotransferase. Moreover, the quantitative ferritin reduction at 12 months was positively associated with the relative reduction of BMI (r = 0.34, p < 0.05). Finally, the association between changes of alanine aminotransferase and ferritin levels at 12 months from baseline turned out to be independent of respective BMI changes (β = 0.31, p < 0.05). CONCLUSION In obesity, ferritin, putatively entailing increased iron storage, is independently associated with lipid derangements and transaminase levels, and the association with the latter persists after weight changes.
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Affiliation(s)
- V Guglielmi
- Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy; Obesity Center, University Hospital Policlinico Tor Vergata, Rome, Italy
| | - M D'Adamo
- Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy; Obesity Center, University Hospital Policlinico Tor Vergata, Rome, Italy
| | - A Bellia
- Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy
| | - R T Ciotto
- Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy; Obesity Center, University Hospital Policlinico Tor Vergata, Rome, Italy
| | - M Federici
- Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy
| | - D Lauro
- Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy
| | - P Sbraccia
- Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy; Obesity Center, University Hospital Policlinico Tor Vergata, Rome, Italy.
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H-ferritin-regulated microRNAs modulate gene expression in K562 cells. PLoS One 2015; 10:e0122105. [PMID: 25815883 PMCID: PMC4376865 DOI: 10.1371/journal.pone.0122105] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/17/2015] [Indexed: 01/13/2023] Open
Abstract
In a previous study, we showed that the silencing of the heavy subunit (FHC) offerritin, the central iron storage molecule in the cell, is accompanied by a modification in global gene expression. In this work, we explored whether different FHC amounts might modulate miRNA expression levels in K562 cells and studied the impact of miRNAs in gene expression profile modifications. To this aim, we performed a miRNA-mRNA integrative analysis in K562 silenced for FHC (K562shFHC) comparing it with K562 transduced with scrambled RNA (K562shRNA). Four miRNAs, namely hsa-let-7g, hsa-let-7f, hsa-let-7i and hsa-miR-125b, were significantly up-regulated in silenced cells. The remarkable down-regulation of these miRNAs, following FHC expression rescue, supports a specific relation between FHC silencing and miRNA-modulation. The integration of target predictions with miRNA and gene expression profiles led to the identification of a regulatory network which includes the miRNAs up-regulated by FHC silencing, as well as91 down-regulated putative target genes. These genes were further classified in 9 networks; the highest scoring network, “Cell Death and Survival, Hematological System Development and Function, Hematopoiesis”, is composed by 18 focus molecules including RAF1 and ERK1/2. We confirmed that, following FHC silencing, ERK1/2 phosphorylation is severely impaired and that RAF1 mRNA is significantly down-regulated. Taken all together, our data indicate that, in our experimental model, FHC silencing may affect RAF1/pERK1/2 levels through the modulation of a specific set of miRNAs and add new insights in to the relationship among iron homeostasis and miRNAs.
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Moreno M, Ortega F, Xifra G, Ricart W, Fernández-Real JM, Moreno-Navarrete JM. Cytosolic aconitase activity sustains adipogenic capacity of adipose tissue connecting iron metabolism and adipogenesis. FASEB J 2014; 29:1529-39. [PMID: 25550467 DOI: 10.1096/fj.14-258996] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 12/09/2014] [Indexed: 12/22/2022]
Abstract
To gain insight into the regulation of intracellular iron homeostasis in adipose tissue, we investigated the role of iron regulatory protein 1/cytosolic aconitase 1 (ACO1). ACO1 gene expression and activity increased in parallel to expression of adipogenic genes during differentiation of both murine 3T3-L1 cells and human preadipocytes. Lentiviral knockdown (KD) of Aco1 in 3T3-L1 preadipocytes led to diminished cytosolic aconitase activity and isocitrate dehydrogenase 1 (NADP(+)), soluble (Idh1) mRNA levels, decreased intracellular NADPH:NADP ratio, and impaired adipogenesis during adipocyte differentiation. In addition, Aco1 KD in fully differentiated 3T3-L1 adipocytes decreased lipogenic, Idh1, Adipoq, and Glut4 gene expression. A bidirectional cross-talk was found between intracellular iron levels and ACO1 gene expression and protein activity. Although iron in excess, known to increase reactive oxygen species production, and iron depletion both resulted in decreased ACO1 mRNA levels and activity, Aco1 KD led to reduced gene expression of transferrin receptor (Tfrc) and transferrin, disrupting intracellular iron uptake. In agreement with these findings, in 2 human independent cohorts (n = 85 and n = 38), ACO1 gene expression was positively associated with adipogenic markers in subcutaneous and visceral adipose tissue. ACO1 gene expression was also positively associated with the gene expression of TFRC while negatively linked to ferroportin (solute carrier family 40 (iron-regulated transporter), member 1) mRNA levels. Altogether, these results suggest that ACO1 activity is required for the normal adipogenic capacity of adipose tissue by connecting iron, energy metabolism, and adipogenesis.
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Affiliation(s)
- María Moreno
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona, CIBEROBN (CB06/03/010), and Instituto de Salud Carlos III, Girona, Spain
| | - Francisco Ortega
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona, CIBEROBN (CB06/03/010), and Instituto de Salud Carlos III, Girona, Spain
| | - Gemma Xifra
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona, CIBEROBN (CB06/03/010), and Instituto de Salud Carlos III, Girona, Spain
| | - Wifredo Ricart
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona, CIBEROBN (CB06/03/010), and Instituto de Salud Carlos III, Girona, Spain
| | - José Manuel Fernández-Real
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona, CIBEROBN (CB06/03/010), and Instituto de Salud Carlos III, Girona, Spain
| | - José María Moreno-Navarrete
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona, CIBEROBN (CB06/03/010), and Instituto de Salud Carlos III, Girona, Spain
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Jiang X, Wang H, Shi W, Shen Z, Shen H, Li M. Hyperinsulinemia induces hepatic iron overload by increasing liver TFR1 via the PI3K/IRP2 pathway. J Mol Endocrinol 2014; 53:381-92. [PMID: 25385842 DOI: 10.1530/jme-14-0122] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dysmetabolic iron overload syndrome (DIOS) is frequently observed, but the underlying mechanism remains unclear. We propose the hypothesis that hyperinsulinemia, a common characteristic of DIOS, may stimulate liver transferrin receptor 1 (TFR1) expression via the PI3K/iron regulatory protein 2 (IRP2) pathway, leading to the occurrence of DIOS. The hepatic iron content, serum iron parameters, and expressions of TFRs and IRPs in the liver were determined in rats with temporary or long-lasting hyperinsulinemia induced by acute or chronic administration of insulin. The effect of insulin on TFR1 expression and its molecular mechanism were determined in HL-7702 cells in vitro. It was found that long-lasting hyperinsulinemia significantly increased TFR1 expression in the liver and induced mild-to-moderate hepatic iron overload, which was accompanied by a normal level of serum iron. Insulin markedly upregulated both protein and mRNA levels of TFR1 in HL-7702 cells. The stability of TFR1 mRNA stability, together with expression of IRPs expression, were both significantly increased by insulin treatment. Insulin-induced TFR1 expression was blocked by IRP2, but not by IRP1 interference, and disappeared when HL-7702 cells were pretreated with LY294002, triciribine hydrate, or rapamycin. In conclusion, the findings of this study indicate that hyperinsulnemia could induce hepatic iron overload by upregulating liver TFR1 via the PI3K/AKT/mTOR/IRP2 pathway, which may be one of the main reasons for the occurrence of DIOS.
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Affiliation(s)
- Xin Jiang
- Military Hygiene DepartmentFaculty of Naval Medicine, Second Military Medical University, No. 800, Xiangyin Road, Shanghai 200433, China
| | - Heyang Wang
- Military Hygiene DepartmentFaculty of Naval Medicine, Second Military Medical University, No. 800, Xiangyin Road, Shanghai 200433, China
| | - Wencai Shi
- Military Hygiene DepartmentFaculty of Naval Medicine, Second Military Medical University, No. 800, Xiangyin Road, Shanghai 200433, China
| | - Zhilei Shen
- Military Hygiene DepartmentFaculty of Naval Medicine, Second Military Medical University, No. 800, Xiangyin Road, Shanghai 200433, China
| | - Hui Shen
- Military Hygiene DepartmentFaculty of Naval Medicine, Second Military Medical University, No. 800, Xiangyin Road, Shanghai 200433, China
| | - Min Li
- Military Hygiene DepartmentFaculty of Naval Medicine, Second Military Medical University, No. 800, Xiangyin Road, Shanghai 200433, China
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Moreno-Navarrete JM, Ortega F, Moreno M, Ricart W, Fernández-Real JM. Fine-tuned iron availability is essential to achieve optimal adipocyte differentiation and mitochondrial biogenesis. Diabetologia 2014; 57:1957-67. [PMID: 24973963 DOI: 10.1007/s00125-014-3298-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 05/27/2014] [Indexed: 12/21/2022]
Abstract
AIMS/HYPOTHESIS Adipose tissue from obese and insulin-resistant individuals showed altered expression of several iron-related genes in a recent study, suggesting that iron might have an important role in adipogenesis. To investigate this possible role, we aimed to characterise the effects of iron on adipocyte differentiation. METHODS Intracellular iron deficiency was achieved using two independent approaches: deferoxamine administration (20 and 100 μmol/l) and transferrin knockdown (TF KD). The effects of added FeSO4, holo-transferrin and palmitate were studied during human and 3T3-L1 adipocyte differentiation. Finally, the relationship between iron-related and mitochondrial-related genes was investigated in human adipose tissue. RESULTS Most adipose tissue iron-related genes were predominantly expressed in adipocytes compared with stromal vascular cells. Of note, transferrin gene and protein expression increased significantly during adipocyte differentiation. Both deferoxamine and TF KD severely blunted adipocyte differentiation in parallel with increased inflammatory mRNAs. These effects were reversed in a dose-dependent manner after iron supplementation. Palmitate administration also led to a state of functional intracellular iron deficiency, with decreased Tf gene expression and iron uptake during adipocyte differentiation, which was reversed with transferrin co-treatment. On the other hand, iron in excess impaired differentiation, but this antiadipogenic effect was less pronounced than under iron chelation. Of interest, expression of several genes involved in mitochondrial biogenesis occurred in parallel with expression of iron-related genes both during adipogenesis and in human adipose tissue. CONCLUSIONS/INTERPRETATION Precise and fine-tuned iron availability is essential to achieve optimal adipocyte differentiation, possibly modulating adipocyte mitochondrial biogenesis.
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Affiliation(s)
- José María Moreno-Navarrete
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona (IdIBGi), Hospital of Girona 'Dr Josep Trueta', Girona, Spain
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Abstract
Iron can affect the clinical course of several chronic metabolic diseases such as type 2 diabetes, obesity, non-alcoholic fatty liver disease, and atherosclerosis. Iron overload can affect major tissues involved in glucose and lipid metabolism (pancreatic β cells, liver, muscle, and adipose tissue) and organs affected by chronic diabetic complications. Because iron is a potent pro-oxidant, fine-tuned control mechanisms have evolved to regulate entry, recycling, and loss of body iron. These mechanisms include the interplay of iron with transferrin, ferritin, insulin, and hepcidin, as well as with adipokines and proinflammatory molecules. An imbalance of these homoeostatic mechanisms results in systemic and parenchymal siderosis that contributes to organ damage (such as β-cell dysfunction, fibrosis in liver diseases, and atherosclerotic plaque growth and instability). Conversely, iron depletion can exert beneficial effects in patients with iron overload and even in healthy frequent blood donors. Regular assessment of iron balance should be recommended for patients with chronic metabolic diseases, and further research is needed to produce guidelines for the identification of patients who would benefit from iron depletion.
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Affiliation(s)
- José Manuel Fernández-Real
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomédica de Girona, Hospital de Girona 'Doctor Josep Trueta', Girona, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Girona, Spain.
| | - Melania Manco
- Research Unit for Multifactorial Disease, Bambino Gesù Children's Hospital and Research Institute, Rome, Italy
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Moreno-Navarrete JM, Novelle MG, Catalán V, Ortega F, Moreno M, Gomez-Ambrosi J, Xifra G, Serrano M, Guerra E, Ricart W, Frühbeck G, Diéguez C, Fernández-Real JM. Insulin resistance modulates iron-related proteins in adipose tissue. Diabetes Care 2014; 37:1092-100. [PMID: 24496804 DOI: 10.2337/dc13-1602] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Circulating markers of iron overload are associated with insulin resistance. Less is known about the impact of iron overload on adipose tissue (AT). We hypothesized that gene expression markers of iron metabolism in AT could be associated with insulin action. RESEARCH DESIGN AND METHODS The AT expression of ferroportin (SLC40A1), transferrin (TF), TF receptor (TFRC), ferritin (FT) heavy polypeptide 1 (FTH1), and FT light polypeptide (FTL) was analyzed cross-sectionally in three independent cohorts and also after weight loss-induced changes in insulin sensitivity (clamp M value) in an independent fourth cohort. RESULTS In human AT, TF mRNA and protein levels were decreased with obesity and insulin resistance in the three cohorts and were positively associated with adipogenic mRNAs and insulin action. Otherwise, FTL mRNA and protein and SLC40A1 transcripts were positively associated with BMI and negatively linked to adipogenic genes and insulin action. Bariatric surgery-induced weight loss led to increased TF and decreased TFRC, FTH1, FTL, and SLC40A1 in subcutaneous AT in parallel to improved insulin action. CONCLUSIONS These results suggest that iron overload impacts on AT in association with insulin resistance.
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Orr JS, Kennedy A, Anderson-Baucum EK, Webb CD, Fordahl SC, Erikson KM, Zhang Y, Etzerodt A, Moestrup SK, Hasty AH. Obesity alters adipose tissue macrophage iron content and tissue iron distribution. Diabetes 2014; 63:421-32. [PMID: 24130337 PMCID: PMC3900546 DOI: 10.2337/db13-0213] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Adipose tissue (AT) expansion is accompanied by the infiltration and accumulation of AT macrophages (ATMs), as well as a shift in ATM polarization. Several studies have implicated recruited M1 ATMs in the metabolic consequences of obesity; however, little is known regarding the role of alternatively activated resident M2 ATMs in AT homeostasis or how their function is altered in obesity. Herein, we report the discovery of a population of alternatively activated ATMs with elevated cellular iron content and an iron-recycling gene expression profile. These iron-rich ATMs are referred to as MFe(hi), and the remaining ATMs are referred to as MFe(lo). In lean mice, ~25% of the ATMs are MFe(hi); this percentage decreases in obesity owing to the recruitment of MFe(lo) macrophages. Similar to MFe(lo) cells, MFe(hi) ATMs undergo an inflammatory shift in obesity. In vivo, obesity reduces the iron content of MFe(hi) ATMs and the gene expression of iron importers as well as the iron exporter, ferroportin, suggesting an impaired ability to handle iron. In vitro, exposure of primary peritoneal macrophages to saturated fatty acids also alters iron metabolism gene expression. Finally, the impaired MFe(hi) iron handling coincides with adipocyte iron overload in obese mice. In conclusion, in obesity, iron distribution is altered both at the cellular and tissue levels, with AT playing a predominant role in this change. An increased availability of fatty acids during obesity may contribute to the observed changes in MFe(hi) ATM phenotype and their reduced capacity to handle iron.
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Affiliation(s)
- Jeb S. Orr
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Arion Kennedy
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Emily K. Anderson-Baucum
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Corey D. Webb
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Steve C. Fordahl
- Department of Nutrition, University of North Carolina at Greensboro, Greensboro, NC
| | - Keith M. Erikson
- Department of Nutrition, University of North Carolina at Greensboro, Greensboro, NC
| | - Yaofang Zhang
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN
| | - Anders Etzerodt
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Alyssa H. Hasty
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
- Corresponding author: Alyssa H. Hasty,
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Aderibigbe OR, Pisa PT, Vorster HH, Kruger SH. The Relationship Between Iron Status and Adiposity in Women from Developing Countries: A Review. Crit Rev Food Sci Nutr 2013; 54:553-60. [DOI: 10.1080/10408398.2011.594914] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Do THT, Gaboriau F, Cannie I, Batusanski F, Ropert M, Moirand R, Brissot P, Loreal O, Lescoat G. Iron-mediated effect of alcohol on hepatocyte differentiation in HepaRG cells. Chem Biol Interact 2013; 206:117-25. [PMID: 24025710 DOI: 10.1016/j.cbi.2013.08.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 08/19/2013] [Accepted: 08/30/2013] [Indexed: 01/16/2023]
Abstract
The development of alcoholic liver diseases depends on the ability of hepatocyte to proliferate and differentiate in the case of alcohol-induced injury. Our previous work showed an inhibitory effect of alcohol on hepatocyte proliferation. However, the effect of alcohol on hepatocyte differentiation has not yet been precisely characterized. In the present study, we evaluated the effect of alcohol on hepatocyte differentiation in relationship with changes of iron metabolism in HepaRG cells. This unique bipotent human cell line can differentiate into hepatocytes and biliary epithelial cells, paralleling liver development. Results showed that alcohol reduced cell viability, total protein level and enhanced hepatic enzymes leakage in differentiated HepaRG cells. Moreover, it caused cell enlargement, decreased number of hepatocyte and expression of C/EBPα as well as bile canaliculi F-actin. Alcohol increased expression of hepatic cell-specific markers and alcohol-metabolizing enzymes (ADH2, CYP2E1). This was associated with a lipid peroxidation and an iron excess expressed by an increase in total iron content, ferritin level, iron uptake as well as an overexpression of genes involved in iron transport and storage. Alcohol-induced hepatoxicity was amplified by exogenous iron via exceeding iron overload. Taken together, our data demonstrate that in differentiated hepatocytes, alcohol reduces proliferation while increasing expression of hepatic cell-specific markers. Moreover, iron overload could be one of the underlying mechanisms of effect of alcohol on the whole differentiation process of hepatocytes.
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Affiliation(s)
- Thi Hong Tuoi Do
- Inserm, UMR 991, «Foie, Métabolismes et Cancer», F-35033 Rennes, France; Université de Rennes 1, F-35043 Rennes, France; University of Medicine and Pharmacy at Ho Chi Minh City, Viet Nam.
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Meli R, Mattace Raso G, Irace C, Simeoli R, Di Pascale A, Paciello O, Pagano TB, Calignano A, Colonna A, Santamaria R. High Fat Diet Induces Liver Steatosis and Early Dysregulation of Iron Metabolism in Rats. PLoS One 2013; 8:e66570. [PMID: 23805238 PMCID: PMC3689747 DOI: 10.1371/journal.pone.0066570] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 05/09/2013] [Indexed: 02/06/2023] Open
Abstract
This paper is dedicated to the memory of our wonderful colleague Professor Alfredo Colonna, who passed away the same day of its acceptance. Fatty liver accumulation, inflammatory process and insulin resistance appear to be crucial in non-alcoholic fatty liver disease (NAFLD), nevertheless emerging findings pointed an important role also for iron overload. Here, we investigate the molecular mechanisms of hepatic iron metabolism in the onset of steatosis to understand whether its impairment could be an early event of liver inflammatory injury. Rats were fed with control diet or high fat diet (HFD) for 5 or 8 weeks, after which liver morphology, serum lipid profile, transaminases levels and hepatic iron content (HIC), were evaluated. In liver of HFD fed animals an increased time-dependent activity of iron regulatory protein 1 (IRP1) was evidenced, associated with the increase in transferrin receptor-1 (TfR1) expression and ferritin down-regulation. Moreover, ferroportin (FPN-1), the main protein involved in iron export, was down-regulated accordingly with hepcidin increase. These findings were indicative of an increased iron content into hepatocytes, which leads to an increase of harmful free-iron also related to the reduction of hepatic ferritin content. The progressive inflammatory damage was evidenced by the increase of hepatic TNF-α, IL-6 and leptin, in parallel to increased iron content and oxidative stress. The major finding that emerged of this study is the impairment of iron homeostasis in the ongoing and sustaining of liver steatosis, suggesting a strong link between iron metabolism unbalance, inflammatory damage and progression of disease.
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Affiliation(s)
- Rosaria Meli
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
- * E-mail: (RM); (AC)
| | | | - Carlo Irace
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Raffaele Simeoli
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | | | - Orlando Paciello
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Teresa Bruna Pagano
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Antonio Calignano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - Alfredo Colonna
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
- * E-mail: (RM); (AC)
| | - Rita Santamaria
- Department of Pharmacy, University of Naples Federico II, Naples, Italy
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Simcox JA, McClain DA. Iron and diabetes risk. Cell Metab 2013; 17:329-41. [PMID: 23473030 PMCID: PMC3648340 DOI: 10.1016/j.cmet.2013.02.007] [Citation(s) in RCA: 356] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 11/03/2012] [Accepted: 11/29/2012] [Indexed: 02/06/2023]
Abstract
Iron overload is a risk factor for diabetes. The link between iron and diabetes was first recognized in pathologic conditions-hereditary hemochromatosis and thalassemia-but high levels of dietary iron also impart diabetes risk. Iron plays a direct and causal role in diabetes pathogenesis mediated both by β cell failure and insulin resistance. Iron also regulates metabolism in most tissues involved in fuel homeostasis, with the adipocyte in particular serving an iron-sensing role. The underlying molecular mechanisms mediating these effects are numerous and incompletely understood but include oxidant stress and modulation of adipokines and intracellular signal transduction pathways.
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Affiliation(s)
- Judith A Simcox
- Departments of Medicine and Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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Biswas S, Tapryal N, Mukherjee R, Kumar R, Mukhopadhyay CK. Insulin promotes iron uptake in human hepatic cell by regulating transferrin receptor-1 transcription mediated by hypoxia inducible factor-1. Biochim Biophys Acta Mol Basis Dis 2012; 1832:293-301. [PMID: 23160040 DOI: 10.1016/j.bbadis.2012.11.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 10/24/2012] [Accepted: 11/06/2012] [Indexed: 01/04/2023]
Abstract
Hepatic iron is known to regulate insulin signaling pathways and to influence insulin sensitivity in insulin resistance (IR) patients. However, the role of insulin on hepatic iron homeostasis remains unexplored. Here, we report that insulin promotes transferrin-bound iron uptake but shows no influence on non transferrin-bound iron uptake in human hepatic HepG2 cells. As a mechanism we detected increased transferrin receptor-1 (TfR1) expression both at protein and mRNA levels. Unaltered stability of protein and transcript of TfR1 suggested the regulation at transcriptional level that was confirmed by promoter activity. Involvement of transcription factor hypoxia inducible factor-1 (HIF-1) was shown by mutational analyses of the TfR1 promoter region and by electrophoretic mobility shift assay. When HepG2 cells were transfected with specific siRNA targeted to 3'UTR of HIF-1α, the regulatory subunit of HIF-1; insulin-induced TfR1 expression and iron uptake were inhibited. Transfection of cDNA expressing stable form of HIF-1α reversed the increased TfR1 expression and iron uptake. These results suggest a novel role of insulin in hepatic iron uptake by a HIF-1 dependent transcriptional regulation of TfR1.
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Affiliation(s)
- Sudipta Biswas
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi-110 067, India
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Gabrielsen JS, Gao Y, Simcox JA, Huang J, Thorup D, Jones D, Cooksey RC, Gabrielsen D, Adams TD, Hunt SC, Hopkins PN, Cefalu WT, McClain DA. Adipocyte iron regulates adiponectin and insulin sensitivity. J Clin Invest 2012; 122:3529-40. [PMID: 22996660 DOI: 10.1172/jci44421] [Citation(s) in RCA: 226] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 07/19/2012] [Indexed: 12/15/2022] Open
Abstract
Iron overload is associated with increased diabetes risk. We therefore investigated the effect of iron on adiponectin, an insulin-sensitizing adipokine that is decreased in diabetic patients. In humans, normal-range serum ferritin levels were inversely associated with adiponectin, independent of inflammation. Ferritin was increased and adiponectin was decreased in type 2 diabetic and in obese diabetic subjects compared with those in equally obese individuals without metabolic syndrome. Mice fed a high-iron diet and cultured adipocytes treated with iron exhibited decreased adiponectin mRNA and protein. We found that iron negatively regulated adiponectin transcription via FOXO1-mediated repression. Further, loss of the adipocyte iron export channel, ferroportin, in mice resulted in adipocyte iron loading, decreased adiponectin, and insulin resistance. Conversely, organismal iron overload and increased adipocyte ferroportin expression because of hemochromatosis are associated with decreased adipocyte iron, increased adiponectin, improved glucose tolerance, and increased insulin sensitivity. Phlebotomy of humans with impaired glucose tolerance and ferritin values in the highest quartile of normal increased adiponectin and improved glucose tolerance. These findings demonstrate a causal role for iron as a risk factor for metabolic syndrome and a role for adipocytes in modulating metabolism through adiponectin in response to iron stores.
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Affiliation(s)
- J Scott Gabrielsen
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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Gene expression profiles analyzed by DNA sequencing of cDNA clones constructed from porcine preadipocytes and adipocytes. Genes Genomics 2012. [DOI: 10.1007/s13258-011-0075-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Bu W, Liu R, Cheung-Lau JC, Dmochowski IJ, Loll PJ, Eckenhoff RG. Ferritin couples iron and fatty acid metabolism. FASEB J 2012; 26:2394-400. [PMID: 22362897 DOI: 10.1096/fj.11-198853] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A physiological relationship between iron, oxidative injury, and fatty acid metabolism exists, but transduction mechanisms are unclear. We propose that the iron storage protein ferritin contains fatty acid binding sites whose occupancy modulates iron uptake and release. Using isothermal microcalorimetry, we found that arachidonic acid binds ferritin specifically and with 60 μM affinity. Arachidonate binding by ferritin enhanced iron mineralization, decreased iron release, and protected the fatty acid from oxidation. Cocrystals of arachidonic acid and horse spleen apoferritin diffracted to 2.18 Å and revealed specific binding to the 2-fold intersubunit pocket. This pocket shields most of the fatty acid and its double bonds from solvent but allows the arachidonate tail to project well into the ferrihydrite mineralization site on the ferritin L-subunit, a structural feature that we implicate in the effects on mineralization by demonstrating that the much shorter saturated fatty acid, caprylate, has no significant effects on mineralization. These combined effects of arachidonate binding by ferritin are expected to lower both intracellular free iron and free arachidonate, thereby providing a previously unrecognized mechanism for limiting lipid peroxidation, free radical damage, and proinflammatory cascades during times of cellular stress.
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Affiliation(s)
- Weiming Bu
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Hou Y, Xue P, Bai Y, Liu D, Woods CG, Yarborough K, Fu J, Zhang Q, Sun G, Collins S, Chan JY, Yamamoto M, Andersen ME, Pi J. Nuclear factor erythroid-derived factor 2-related factor 2 regulates transcription of CCAAT/enhancer-binding protein β during adipogenesis. Free Radic Biol Med 2012; 52:462-72. [PMID: 22138520 PMCID: PMC3307524 DOI: 10.1016/j.freeradbiomed.2011.10.453] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 10/20/2011] [Accepted: 10/21/2011] [Indexed: 01/29/2023]
Abstract
Nuclear factor erythroid-derived factor 2-related factor 2 (Nrf2) is a cap-n-collar basic leucine zipper transcription factor that is involved in the cellular adaptive response to oxidative stress. Our previous study reported that targeted disruption of the Nrf2 gene in mice decreases adipose tissue mass and protects against obesity induced by a high-fat diet. Deficiency of Nrf2 in preadipocytes and mouse embryonic fibroblasts led to impaired adipogenesis. Consistent with these findings, the current study found that lack of Nrf2 in primary cultured mouse preadipocytes and 3T3-L1 cells hampered adipogenic differentiation induced by hormonal cocktails. Stable knockdown of Nrf2 in 3T3-L1 cells blocked the enhanced adipogenesis caused by deficiency of kelch-like ECH-associated protein 1 (Keap1), a Cul3-adapter protein that allows for Nrf2 to be ubiquinated and degraded by the 26S protesome complex. In addition, increased production of reactive oxygen species (ROS) and activation of Nrf2 occurred at the very early stage upon adipogenic hormonal challenge in 3T3-L1 cells, followed by an immediate induction of CCAAT/enhancer-binding protein β (C/EBPβ). Knockdown of Nrf2 led to reduced expression of C/EBPβ induced by adipogenic hormonal cocktails, chemical Nrf2 activators or Keap1 silencing. Cebpβ promoter-driven reporter assays and chromatin immunoprecipitation suggested that Nrf2 associates with a consensus antioxidant response element (ARE) binding site in the promoter of the Cebpβ gene during adipogenesis and upregulates its expression. These findings demonstrate a novel role of Nrf2 beyond xenobiotic detoxification and antioxidant response, and suggest that Nrf2 is one of the transcription factors that control the early events of adipogenesis by regulating expression of Cebpβ.
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Affiliation(s)
- Yongyong Hou
- Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
| | - Peng Xue
- Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
| | - Yushi Bai
- Department of Molecular Biology, Duke University, Durham, NC 27708, USA
| | - Dianxin Liu
- Sanford-Burnham Medical Research Institute, Orlando, FL 32827, USA
| | - Courtney G. Woods
- Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
| | - Kathy Yarborough
- Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
| | - Jingqi Fu
- Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
| | - Qiang Zhang
- Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
| | - Guifan Sun
- School of Public Health, China Medical University, Shenyang, China
| | - Sheila Collins
- Sanford-Burnham Medical Research Institute, Orlando, FL 32827, USA
| | - Jefferson Y. Chan
- Department of Laboratory Medicine and Pathology, University of California, Irvine, CA 92697, USA
| | - Masayuki Yamamoto
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Melvin E. Andersen
- Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
| | - Jingbo Pi
- Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
- Corresponding author at: Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709, USA. Phone: 919-558-1395. Fax: 919-558-1305.
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Aderibigbe OR, Pisa PT, Mamabolo RL, Kruger HS, Vorster HH. The relationship between indices of iron status and selected anthropometric cardiovascular disease risk markers in an African population: the THUSA study. Cardiovasc J Afr 2011; 22:249-56. [PMID: 21556462 PMCID: PMC3721951 DOI: 10.5830/cvja-2011-015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 04/15/2011] [Indexed: 11/06/2022] Open
Abstract
There is evidence that certain indices of iron status are associated with anthropometric measures, which are used independently as markers of cardiovascular disease (CVD) risk. This study examined whether this association exists in an African population. The study was a cross-sectional comparative study that examined a total of 1 854 African participants. Ferritin was positively associated with body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), percentage body fat and subscapular skinfold thickness. Serum ferritin concentration was higher in the high-WHR category than the normal-WHR category for both genders. Additionally, WC and WHR increased with increasing ferritin concentrations in both genders. Serum iron was lower in the obese than the normal-weight and pre-obese women only. In this population-based study, increased serum ferritin concentrations associated positively with increased WHR and WC, indicating that individuals or populations at risk of iron overload as defined by high serum ferritin concentrations may be at a greater risk of developing CVD.
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Affiliation(s)
- O R Aderibigbe
- Centre of Excellence for Nutrition, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa.
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43
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2,3,7,8-Tetrachlorodibenzo-p-dioxin impairs iron homeostasis by modulating iron-related proteins expression and increasing the labile iron pool in mammalian cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:704-12. [PMID: 21333694 DOI: 10.1016/j.bbamcr.2011.02.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 01/31/2011] [Accepted: 02/02/2011] [Indexed: 02/05/2023]
Abstract
Cellular iron metabolism is essentially controlled by the binding of cytosolic iron regulatory proteins (IRP1 or IRP2) to iron-responsive elements (IREs) located on mRNAs coding for proteins involved in iron acquisition, utilization and storage. The 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is one of the most potent toxins of current interest that occurs as poisonous chemical in the environment. TCDD exposure has been reported to induce a broad spectrum of toxic and biological responses, including significant changes in gene expression for heme and iron metabolism associated with liver injury. Here, we have investigated the molecular effects of TCDD on the iron metabolism providing the first evidence that administration of the toxin TCDD to mammalian cells affects the maintenance of iron homeostasis. We found that exposure of Madin-Darby Bovine Kidney cell to TCDD caused a divergent modulation of IRP1 and IRP2 RNA-binding capacity. Interestingly, we observed a concomitant IRP1 down-regulation and IRP2 up-regulation thus determining a marked enhancement of transferrin receptor 1 (TfR-1) expression and a biphasic response in ferritin content. The changed ferritin content coupled to TfR-1 induction after TCDD exposure impairs the cellular iron homeostasis, ultimately leading to significant changes in the labile iron pool (LIP) extent. Since important iron requirement changes occur during the regulation of cell growth, it is not surprising that the dioxin-dependent iron metabolism dysregulation herein described may be linked to cell-fate decision, supporting the hypothesis of a central connection among exposure to dioxins and the regulation of critical cellular processes. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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Recalcati S, Minotti G, Cairo G. Iron regulatory proteins: from molecular mechanisms to drug development. Antioxid Redox Signal 2010; 13:1593-616. [PMID: 20214491 DOI: 10.1089/ars.2009.2983] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Eukaryotic cells require iron for survival but, as an excess of poorly liganded iron can lead to the catalytic production of toxic radicals that can damage cell structures, regulatory mechanisms have been developed to maintain appropriate cell and body iron levels. The interactions of iron responsive elements (IREs) with iron regulatory proteins (IRPs) coordinately regulate the expression of the genes involved in iron uptake, use, storage, and export at the post-transcriptional level, and represent the main regulatory network controlling cell iron homeostasis. IRP1 and IRP2 are similar (but not identical) proteins with partially overlapping and complementary functions, and control cell iron metabolism by binding to IREs (i.e., conserved RNA stem-loops located in the untranslated regions of a dozen mRNAs directly or indirectly related to iron metabolism). The discovery of the presence of IREs in a number of other mRNAs has extended our knowledge of the influence of the IRE/IRP regulatory network to new metabolic pathways, and it has been recently learned that an increasing number of agents and physiopathological conditions impinge on the IRE/IRP system. This review focuses on recent findings concerning the IRP-mediated regulation of iron homeostasis, its alterations in disease, and new research directions to be explored in the near future.
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Affiliation(s)
- Stefania Recalcati
- Department of Human Morphology and Biomedical Sciences Città Studi, University of Milan, Milano, Italy
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45
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Ono K, Fuma K, Tabata K, Sawada M. Ferritin reporter used for gene expression imaging by magnetic resonance. Biochem Biophys Res Commun 2009; 388:589-94. [DOI: 10.1016/j.bbrc.2009.08.055] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 08/11/2009] [Indexed: 10/20/2022]
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Ovariectomy and estrogen treatment modulate iron metabolism in rat adipose tissue. Biochem Pharmacol 2009; 78:1001-7. [PMID: 19501056 DOI: 10.1016/j.bcp.2009.05.034] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 05/26/2009] [Accepted: 05/26/2009] [Indexed: 11/21/2022]
Abstract
Iron is essential for many biological processes and its deficiency or excess is involved in pathological conditions. At cellular level, the maintenance of iron homeostasis is largely accomplished by the transferrin receptor (TfR-1) and by ferritin, whose expression is mainly regulated post-transcriptionally by iron regulatory proteins (IRPs). This study examines the hypothesis that modification of serum estrogen levels by ovariectomy and 17beta-estradiol (E(2)) treatment in rats modulate serum iron-status parameters and iron metabolism in adipose tissue. In particular, we evaluated the RNA binding of IRP1 by electrophoretic mobility-shift assay and IRP1, ferritin, and TfR-1 expression in adipose tissue by Western blot analysis. Ovariectomy, besides a lowered serum iron and transferrin iron binding capacity, remarkably decreased the binding activity of IRP1 in peritoneal and subcutaneous adipose tissues, and these effects were reversed by E(2) treatment. Moreover, ovariectomy determined a decrease of IRP1 expression, which was significant in subcutaneous adipose tissue. Consistent with IRP1 regulation, an increase of ferritin and a decrease of TfR-1 expression were observed in peritoneal adipose tissue from ovariectomized animals, while the treatment with E(2) reconstituted TfR-1 level. A similar expression profile of TfR-1 was observed in subcutaneous adipose tissue, where ferritin level did not change in ovariectomized animals, and was increased after E(2) treatment. Our results indicate that estrogen level changes can regulate the binding activity of the IRP1, and consequently ferritin and TfR-1 expression in adipose tissue, suggesting a relationship among serum and tissue iron parameters, estrogen status and adiposity.
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Maffettone C, De Martino L, Irace C, Santamaria R, Pagnini U, Iovane G, Colonna A. Expression of iron-related proteins during infection by bovine herpes virus type-1. J Cell Biochem 2008; 104:213-23. [PMID: 17990282 DOI: 10.1002/jcb.21618] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Bovine herpesvirus 1 (BHV-1), a dsDNA animal virus, is an economically important pathogen of cattle and the aetiological agent of many types of disease. The efficient replication of a DNA virus is strictly dependent on iron since this metal plays a crucial role in the catalytic center of viral ribonucleotide reductase. Consequently, iron metabolism is an important area for virus/host interaction and a large body of evidence suggests that viral infection is potentially influenced by the iron status of the host. The aim of the present study was to address the effects of BHV-1 on iron metabolism in Madin-Darby bovine kidney (MDBK) cells at different times of post-infection. For this purpose, cell viability, iron regulatory proteins (IRPs) activity and levels, transferrin receptor 1 (TfR-1), ferritin expression and LIP were evaluated. Our data demonstrate that a productive BHV-1 infection in MDBK cells determines an overall decrease of IRPs RNA-binding activity without affecting their expression. As consequence of this modulation, an increased ferritin mRNA translation and a decreased TfR-1 mRNA translation were also observed. Moreover, the LIP level was decreased following viral infection. These results are consistent with the hypothesis that by reducing the iron up-take and by enhancing the sequestration of free iron, animal cells will limit the iron availability for virus proliferation. Therefore, the results presented herein support the view that iron metabolism could be critical for the interaction between DNA viruses, such as BHV-1, and mammalian cells. Delineation of the interplay among pathogen and host may provide new antimicrobial agents.
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Affiliation(s)
- Carmen Maffettone
- Dipartimento di Farmacologia Sperimentale, Università di Napoli Federico II, via D. Montesano 49, I-80131 Napoli, Italy
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Hulgan T, Tebas P, Canter JA, Mulligan K, Haas DW, Dubé M, Grinspoon S, Robbins GK, Motsinger AA, Kallianpur AR. Hemochromatosis gene polymorphisms, mitochondrial haplogroups, and peripheral lipoatrophy during antiretroviral therapy. J Infect Dis 2008; 197:858-66. [PMID: 18419350 DOI: 10.1086/528697] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Antiretroviral therapy (ART)-associated lipoatrophy involves mitochondrial dysfunction. Iron metabolism impacts mitochondrial function and oxidative stress. Mitochondrial haplogroups and hemochromatosis gene (HFE) polymorphisms have been associated with ART-induced neuropathy. We assessed relationships between these variants and lipoatrophy. METHODS The AIDS Clinical Trials Group 384 study randomized ART-naive individuals to receive didanosine-stavudine or zidovudine-lamivudine, combined with efavirenz and/or nelfinavir. Substudy A5005s evaluated fat distribution by dual-energy X-ray absorptiometry (DEXA). We characterized HFE polymorphisms 845G>A and 187C>G and European mitochondrial haplogroups in A5005s participants who consented to genetic analyses. RESULTS Among 96 participants (58% were white, and 10% were female) with baseline and 48 or 64 week DEXA data, the median limb fat change was -8.8% (interquartile range, -28.7% to +15.6%). HFE 187C/G heterozygotes (n = 23) had less limb fat loss than 187C/C homozygotes (n = 71) (+6.1% vs. -12.5%; P = .02) and were less likely to develop lipoatrophy after adjustment for age, sex, race, and ART randomization (odds ratio, 0.31; 95% confidence interval, 0.10-0.95; P = .04). Among non-Hispanic white participants, median limb fat change was +26.1% among 5 participants with mitochondrial haplogroup J, compared with -9.7% among 49 participants with other mitochondrial haplogroups (P = .07). CONCLUSIONS HFE 187C>G and, possibly, mitochondrial haplogroup J gave relative protection against lipoatrophy during ART in A5005s. These associations should be replicated in other studies.
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Affiliation(s)
- Todd Hulgan
- Division of Infectious Diseases, Vanderbilt University School of Medicine, Nashville, Tennessee 37203, USA.
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Koorts AM, Viljoen M. Ferritin and ferritin isoforms II: protection against uncontrolled cellular proliferation, oxidative damage and inflammatory processes. Arch Physiol Biochem 2007; 113:55-64. [PMID: 17558604 DOI: 10.1080/13813450701422575] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Ferritin is a major iron storage protein involved in the regulation of iron availability. Each ferritin molecule comprises 24 subunits. Various combinations of H-subunits and L-subunits make up the 24-subunit protein structure and these ferritin isoforms differ in their H-subunit to L-subunit ratio, as well as in their metabolic properties. Ferritin is an acute-phase protein and its expression is up-regulated in conditions such as uncontrolled cellular proliferation, in any condition marked by excessive production of toxic oxygen radicals, and by infectious and inflammatory processes. Under such conditions ferritin up-regulation is predominantly stimulated by increased reactive oxygen radical production and by cytokines. The major function of ferritin in these conditions is to reduce the bio-availability of iron in order to stem uncontrolled cellular proliferation and excessive production of reactive oxygen radicals. Ferritin is not, however, indiscriminately up-regulated in these conditions as a marked shift towards a predominance in H-subunit rich ferritins occurs. Preliminary indications are that, while the L-subunit primarily fulfils the conventional iron storage role, the H-subunit functions primarily as rapid regulator of iron availability, and perhaps indirectly as regulator of other cellular processes. It is suggested that the optimum differential expression of the two subunits differ for different cells and under different conditions and that the expression of appropriate isoferritins offers protection against uncontrolled cellular proliferation, oxidative stress and against side effects of infectious and inflammatory conditions.
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Affiliation(s)
- A M Koorts
- Department of Physiology, School of Medicine, University of Pretoria, Pretoria, South Africa.
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50
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Koorts AM, Viljoen M. Ferritin and ferritin isoforms I: Structure-function relationships, synthesis, degradation and secretion. Arch Physiol Biochem 2007; 113:30-54. [PMID: 17522983 DOI: 10.1080/13813450701318583] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Ferritin is the intracellular protein responsible for the sequestration, storage and release of iron. Ferritin can accumulate up to 4500 iron atoms as a ferrihydrite mineral in a protein shell and releases these iron atoms when there is an increase in the cell's need for bioavailable iron. The ferritin protein shell consists of 24 protein subunits of two types, the H-subunit and the L-subunit. These ferritin subunits perform different functions in the mineralization process of iron. The ferritin protein shell can exist as various combinations of these two subunit types, giving rise to heteropolymers or isoferritins. Isoferritins are functionally distinct and characteristic populations of isoferritins are found depending on the type of cell, the proliferation status of the cell and the presence of disease. The synthesis of ferritin is regulated both transcriptionally and translationally. Translation of ferritin subunit mRNA is increased or decreased, depending on the labile iron pool and is controlled by an iron-responsive element present in the 5'-untranslated region of the ferritin subunit mRNA. The transcription of the genes for the ferritin subunits is controlled by hormones and cytokines, which can result in a change in the pool of translatable mRNA. The levels of intracellular ferritin are determined by the balance between synthesis and degradation. Degradation of ferritin in the cytosol results in complete release of iron, while degradation in secondary lysosomes results in the formation of haemosiderin and protection against iron toxicity. The majority of ferritin is found in the cytosol. However, ferritin with slightly different properties can also be found in organelles such as nuclei and mitochondria. Most of the ferritin produced intracellularly is harnessed for the regulation of iron bioavailability; however, some of the ferritin is secreted and internalized by other cells. In addition to the regulation of iron bioavailability ferritin may contribute to the control of myelopoiesis and immunological responses.
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Affiliation(s)
- A M Koorts
- Department of Physiology, School of Medicine, University of Pretoria, Pretoria, South Africa.
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