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Von Holle A, O'Brien KM, Sandler DP, Janicek R, Karagas MR, White AJ, Niehoff NM, Levine KE, Jackson BP, Weinberg CR. Toenail and serum levels as biomarkers of iron status in pre- and postmenopausal women: correlations and stability over eight-year follow-up. Sci Rep 2024; 14:1682. [PMID: 38242893 PMCID: PMC10798942 DOI: 10.1038/s41598-023-50506-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 12/20/2023] [Indexed: 01/21/2024] Open
Abstract
Iron status is often assessed in epidemiologic studies, and toenails offer a convenient alternative to serum because of ease of collection, transport, and storage, and the potential to reflect a longer exposure window. Very few studies have examined the correlation between serum and toenail levels for trace metals. Our aim was to compare iron measures using serum and toenails on both a cross-sectional and longitudinal basis. Using a subset of the US-wide prospective Sister Study cohort, we compared toenail iron measures to serum concentrations for iron, ferritin and percent transferrin saturation. Among 146 women who donated both blood and toenails at baseline, a subsample (59%, n = 86) provided specimens about 8 years later. Cross-sectional analyses included nonparametric Spearman's rank correlations between toenail and serum biomarker levels. We assessed within-woman maintenance of rank across time for the toenail and serum measures and fit mixed effects models to measure change across time in relation to change in menopause status. Spearman correlations at baseline (follow-up) were 0.08 (0.09) for serum iron, 0.08 (0.07) for transferrin saturation, and - 0.09 (- 0.17) for ferritin. The within-woman Spearman correlation for toenail iron between the two time points was higher (0.47, 95% CI 0.30, 0.64) than for serum iron (0.30, 95% CI 0.09, 0.51) and transferrin saturation (0.34, 95% CI 0.15, 0.54), but lower than that for ferritin (0.58, 95% CI 0.43, 0.73). Serum ferritin increased over time while nail iron decreased over time for women who experienced menopause during the 8-years interval. Based on cross-sectional and repeated assessments, our evidence does not support an association between serum biomarkers and toenail iron levels. Toenail iron concentrations did appear to be moderately stable over time but cannot be taken as a proxy for serum iron biomarkers and they may reflect physiologically distinct fates for iron.
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Affiliation(s)
- Ann Von Holle
- Biostatistics and Computational Biology Branch National Institute of Environmental Health Sciences, Mail Drop A3-03, P.O. Box 12233, Research Triangle Park, Durham, NC, 27709, USA
| | - Katie M O'Brien
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Dale P Sandler
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Robert Janicek
- Advanced Research and Diagnostic Laboratory, University of Minnesota, Minneapolis, MN, USA
| | - Margaret R Karagas
- Department of Epidemiology, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH, USA
| | - Alexandra J White
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Nicole M Niehoff
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
- Ontada, Durham, NC, USA
| | | | - Brian P Jackson
- Department of Earth Sciences, Dartmouth College, Hanover, NH, USA
| | - Clarice R Weinberg
- Biostatistics and Computational Biology Branch National Institute of Environmental Health Sciences, Mail Drop A3-03, P.O. Box 12233, Research Triangle Park, Durham, NC, 27709, USA.
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2
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Yoganathan T, Perez-Liva M, Balvay D, Le Gall M, Lallemand A, Certain A, Autret G, Mokrani Y, Guillonneau F, Bruce J, Nguyen V, Gencer U, Schmitt A, Lager F, Guilbert T, Bruneval P, Vilar J, Maissa N, Mousseaux E, Viel T, Renault G, Kachenoura N, Tavitian B. Acute stress induces long-term metabolic, functional, and structural remodeling of the heart. Nat Commun 2023; 14:3835. [PMID: 37380648 DOI: 10.1038/s41467-023-39590-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/21/2023] [Indexed: 06/30/2023] Open
Abstract
Takotsubo cardiomyopathy is a stress-induced cardiovascular disease with symptoms comparable to those of an acute coronary syndrome but without coronary obstruction. Takotsubo was initially considered spontaneously reversible, but epidemiological studies revealed significant long-term morbidity and mortality, the reason for which is unknown. Here, we show in a female rodent model that a single pharmacological challenge creates a stress-induced cardiomyopathy similar to Takotsubo. The acute response involves changes in blood and tissue biomarkers and in cardiac in vivo imaging acquired with ultrasound, magnetic resonance and positron emission tomography. Longitudinal follow up using in vivo imaging, histochemistry, protein and proteomics analyses evidences a continued metabolic reprogramming of the heart towards metabolic malfunction, eventually leading to irreversible damage in cardiac function and structure. The results combat the supposed reversibility of Takotsubo, point to dysregulation of glucose metabolic pathways as a main cause of long-term cardiac disease and support early therapeutic management of Takotsubo.
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Affiliation(s)
| | | | - Daniel Balvay
- Université Paris Cité, Inserm, PARCC, F-75015, Paris, France
- Université Paris Cité, Plateforme d'Imageries du Vivant, PARCC, F-75015, Paris, France
| | - Morgane Le Gall
- Université Paris Cité, P53 proteom'IC facility, Institut Cochin, INSERM, CNRS, F-75014, Paris, France
| | - Alice Lallemand
- Université Paris Cité, Inserm, PARCC, F-75015, Paris, France
| | - Anais Certain
- Université Paris Cité, Inserm, PARCC, F-75015, Paris, France
| | - Gwennhael Autret
- Université Paris Cité, Inserm, PARCC, F-75015, Paris, France
- Université Paris Cité, Plateforme d'Imageries du Vivant, PARCC, F-75015, Paris, France
| | - Yasmine Mokrani
- Université Paris Cité, Inserm, PARCC, F-75015, Paris, France
| | - François Guillonneau
- Institut de Cancérologie de l'Ouest, CNRS UMR6075 INSERM U1307, 15 rue André Boquel, F-49055, Angers, France
| | - Johanna Bruce
- Université Paris Cité, P53 proteom'IC facility, Institut Cochin, INSERM, CNRS, F-75014, Paris, France
| | - Vincent Nguyen
- Sorbonne Université, Laboratoire d'Imagerie Biomédicale, Inserm, CNRS, F-75006, Paris, France
| | - Umit Gencer
- Service de Radiologie, AP-HP, hôpital européen Georges Pompidou, F-75015, Paris, France
| | - Alain Schmitt
- Université Paris Cité, Cochin Imaging, Electron microscopy, Institut Cochin, INSERM, CNRS, F-75014, Paris, France
| | - Franck Lager
- Université Paris Cité, Plateforme d'Imageries du Vivant, Institut Cochin, Inserm-CNRS, F-75014, Paris, France
| | - Thomas Guilbert
- Université Paris Cité, Cochin Imaging Photonic, IMAG'IC, Institut Cochin, Inserm, CNRS, F-75014, Paris, France
| | | | - Jose Vilar
- Université Paris Cité, Inserm, PARCC, F-75015, Paris, France
| | - Nawal Maissa
- Université Paris Cité, Inserm, PARCC, F-75015, Paris, France
| | - Elie Mousseaux
- Service de Radiologie, AP-HP, hôpital européen Georges Pompidou, F-75015, Paris, France
| | - Thomas Viel
- Université Paris Cité, Inserm, PARCC, F-75015, Paris, France
- Université Paris Cité, Plateforme d'Imageries du Vivant, PARCC, F-75015, Paris, France
| | - Gilles Renault
- Université Paris Cité, Plateforme d'Imageries du Vivant, Institut Cochin, Inserm-CNRS, F-75014, Paris, France
| | - Nadjia Kachenoura
- Sorbonne Université, Laboratoire d'Imagerie Biomédicale, Inserm, CNRS, F-75006, Paris, France
| | - Bertrand Tavitian
- Université Paris Cité, Inserm, PARCC, F-75015, Paris, France.
- Université Paris Cité, Plateforme d'Imageries du Vivant, PARCC, F-75015, Paris, France.
- Service de Radiologie, AP-HP, hôpital européen Georges Pompidou, F-75015, Paris, France.
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3
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James JV, Varghese J, John NM, Deschemin JC, Vaulont S, McKie AT, Jacob M. Insulin resistance and adipose tissue inflammation induced by a high-fat diet are attenuated in the absence of hepcidin. J Nutr Biochem 2023; 111:109175. [PMID: 36223834 DOI: 10.1016/j.jnutbio.2022.109175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 06/15/2022] [Accepted: 08/17/2022] [Indexed: 11/09/2022]
Abstract
Increased body iron stores and inflammation in adipose tissue have been implicated in the pathogenesis of insulin resistance (IR) and type 2 diabetes mellitus. However, the underlying basis of these associations is unclear. To attempt to investigate this, we studied the development of IR and associated inflammation in adipose tissue in the presence of increased body iron stores. Male hepcidin knock-out (Hamp1-/-) mice, which have increased body iron stores, and wild-type (WT) mice were fed a high-fat diet (HFD) for 12 and 24 weeks. Development of IR and metabolic parameters linked to this, insulin signaling in various tissues, and inflammation and iron-related parameters in visceral adipose tissue were studied in these animals. HFD-feeding resulted in impaired glucose tolerance in both genotypes of mice. In response to the HFD for 24 weeks, Hamp1-/- mice gained less body weight and developed less systemic IR than corresponding WT mice. This was associated with less lipid accumulation in the liver and decreased inflammation and lipolysis in the adipose tissue in the knock-out mice, than in the WT animals. Fewer macrophages infiltrated the adipose tissue in the knockout mice than in wild-type mice, with these macrophages exhibiting a predominantly anti-inflammatory (M2-like) phenotype and indirect evidence of a possible lowered intracellular iron content. The absence of hepcidin was thus associated with attenuated inflammation in the adipose tissue and increased whole-body insulin sensitivity, suggesting a role for it in these processes.
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Affiliation(s)
- Jithu Varghese James
- Department of Biochemistry, Christian Medical College, Vellore, India; Department of Diabetes & Obesity, School of Cardiovascular and Metabolic Medicine & Sciences, King's College London, London, UK
| | - Joe Varghese
- Department of Biochemistry, Christian Medical College, Vellore, India
| | | | - Jean-Christophe Deschemin
- Université de Paris, Institut Cochin, INSERM, CNRS, F-75014 Paris, France; Laboratory of Excellence GR-Ex, Paris, France
| | - Sophie Vaulont
- Université de Paris, Institut Cochin, INSERM, CNRS, F-75014 Paris, France; Laboratory of Excellence GR-Ex, Paris, France
| | - Andrew Tristan McKie
- Department of Haematology, UCL Cancer Institute, University College London, London, WC1E 6DD, UK
| | - Molly Jacob
- Department of Biochemistry, Christian Medical College, Vellore, India.
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Fillebeen C, Lam NH, Chow S, Botta A, Sweeney G, Pantopoulos K. Regulatory Connections between Iron and Glucose Metabolism. Int J Mol Sci 2020; 21:ijms21207773. [PMID: 33096618 PMCID: PMC7589414 DOI: 10.3390/ijms21207773] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/07/2020] [Accepted: 10/16/2020] [Indexed: 02/06/2023] Open
Abstract
Iron is essential for energy metabolism, and states of iron deficiency or excess are detrimental for organisms and cells. Therefore, iron and carbohydrate metabolism are tightly regulated. Serum iron and glucose levels are subjected to hormonal regulation by hepcidin and insulin, respectively. Hepcidin is a liver-derived peptide hormone that inactivates the iron exporter ferroportin in target cells, thereby limiting iron efflux to the bloodstream. Insulin is a protein hormone secreted from pancreatic β-cells that stimulates glucose uptake and metabolism via insulin receptor signaling. There is increasing evidence that systemic, but also cellular iron and glucose metabolic pathways are interconnected. This review article presents relevant data derived primarily from mouse models and biochemical studies. In addition, it discusses iron and glucose metabolism in the context of human disease.
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Affiliation(s)
- Carine Fillebeen
- Lady Davis Institute for Medical Research, Jewish General Hospital and Department of Medicine, McGill University, Montreal, QC H3Y 1P3, Canada;
| | - Nhat Hung Lam
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada; (N.H.L.); (S.C.); (A.B.); (G.S.)
| | - Samantha Chow
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada; (N.H.L.); (S.C.); (A.B.); (G.S.)
| | - Amy Botta
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada; (N.H.L.); (S.C.); (A.B.); (G.S.)
| | - Gary Sweeney
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada; (N.H.L.); (S.C.); (A.B.); (G.S.)
| | - Kostas Pantopoulos
- Lady Davis Institute for Medical Research, Jewish General Hospital and Department of Medicine, McGill University, Montreal, QC H3Y 1P3, Canada;
- Correspondence: ; Tel.: +1-514-340-8260 (ext. 25293)
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5
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Corradini E, Buzzetti E, Pietrangelo A. Genetic iron overload disorders. Mol Aspects Med 2020; 75:100896. [PMID: 32912773 DOI: 10.1016/j.mam.2020.100896] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 08/11/2020] [Accepted: 08/17/2020] [Indexed: 02/06/2023]
Abstract
Due to its pivotal role in orchestrating vital cellular functions and metabolic processes, iron is an essential component of the human body and a main micronutrient in the human diet. However, excess iron causes an increased production of reactive oxygen species leading to cell dysfunction or death, tissue damage and organ disease. Iron overload disorders encompass a wide spectrum of pathological conditions of hereditary or acquired origin. A number of 'iron genes' have been identified as being associated with hereditary iron overload syndromes, the most common of which is hemochromatosis. Although linked to at least five different genes, hemochromatosis is recognized as a unique syndromic entity based on a common pathogenetic mechanism leading to excessive entry of unneeded iron into the bloodstream. In this review, we focus on the pathophysiologic basis and clinical aspects of the most common genetic iron overload syndromes in humans.
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Affiliation(s)
- Elena Corradini
- Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia; Internal Medicine and Centre for Hemochromatosis and Heredometabolic Liver Diseases, ERN -EuroBloodNet Center, Azienda Ospedaliero-Universitaria di Modena, Policlinico, Modena, Italy
| | - Elena Buzzetti
- Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia; Internal Medicine and Centre for Hemochromatosis and Heredometabolic Liver Diseases, ERN -EuroBloodNet Center, Azienda Ospedaliero-Universitaria di Modena, Policlinico, Modena, Italy
| | - Antonello Pietrangelo
- Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia; Internal Medicine and Centre for Hemochromatosis and Heredometabolic Liver Diseases, ERN -EuroBloodNet Center, Azienda Ospedaliero-Universitaria di Modena, Policlinico, Modena, Italy.
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6
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Enhanced insulin signaling and its downstream effects in iron-overloaded primary hepatocytes from hepcidin knock-out mice. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118621. [DOI: 10.1016/j.bbamcr.2019.118621] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 11/08/2019] [Accepted: 12/03/2019] [Indexed: 12/22/2022]
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7
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Gupta AP, Syed AA, Garg R, Goand UK, Singh P, Riyazuddin M, Valicherla GR, Husain A, Gayen JR. Pancreastatin inhibitor PSTi8 attenuates hyperinsulinemia induced obesity and inflammation mediated insulin resistance via MAPK/NOX3-JNK pathway. Eur J Pharmacol 2019; 864:172723. [PMID: 31586632 DOI: 10.1016/j.ejphar.2019.172723] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/26/2019] [Accepted: 10/02/2019] [Indexed: 01/13/2023]
Abstract
Pancreastatin (PST), a chromogranin A derived peptide has anti-insulin effects and plays a significant role in obesity-induced insulin resistance. In obesity and type 2 diabetes mellitus, both insulin and PST level are elevated, but it is not clearly understood how anti-insulin effect of PST get regulated in hyperinsulinemic state. Simultaneously we have explored pancreastatin inhibitor PSTi8 against the native PST in the same hyperinsulinemic state. In in-vitro studies, we found that PST treatment increases lipid droplets and reactive oxygen species production in 3T3L1 adipocyte cells and theses effects of PST was found synergistic with chronic-insulin treatment. Treatment of PSTi8 in 3T3L1 adipocytes attenuates PST effect on lipid droplet formation and reactive oxygen species production. We further validated these findings in epididymal white adipose tissue of C57BL/6 mice, implanted with mini-osmotic insulin pump with and without PSTi8 for 4 weeks. We found that chronic hyperinsulinemia enhanced PST levels in circulation which in turn induces expression of various pro-inflammatory cytokines and oxidative stress. In addition, it also stimulated the expression of lipogenic genes, fat mass and body weight gain through the regulation of circulating adiponectin level. The change in PST mediated inflammatory and lipogenic parameters were attenuated by PSTi8 treatment, leading to enhanced insulin sensitivity and improved glucose homeostasis. PSTi8 rescue from PST mediated insulin resistance in adipose via inhibition of MAPK and NOX3-JNK stress signalling pathway which stimulates GLUT4 expression through activation of AKT-AS160 pathway. Thus PSTi8 may be a novel therapeutic agent for the treatment of hyperinsulinemia induced obesity and inflammation mediated insulin resistance.
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Affiliation(s)
- Anand P Gupta
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India
| | - Anees A Syed
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Richa Garg
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Umesh K Goand
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India
| | - Pragati Singh
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India
| | - Mohammed Riyazuddin
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India
| | - Guru R Valicherla
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Athar Husain
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Jiaur R Gayen
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India.
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Gupta AP, Singh P, Garg R, Valicherla GR, Riyazuddin M, Syed AA, Hossain Z, Gayen JR. Pancreastatin inhibitor activates AMPK pathway via GRP78 and ameliorates dexamethasone induced fatty liver disease in C57BL/6 mice. Biomed Pharmacother 2019; 116:108959. [PMID: 31108350 DOI: 10.1016/j.biopha.2019.108959] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 05/02/2019] [Accepted: 05/03/2019] [Indexed: 12/16/2022] Open
Abstract
AIMS To investigate the role of pancreastatin inhibitor (PSTi8) in lipid homeostasis and insulin sensitivity in dexamethasone induced fatty liver disease associated type 2 diabetes. MAIN METHODS Glucose releases assay, lipid O staining and ATP/AMP ratio were performed in HepG2 cells. Twenty four mice were randomly divided into 4 groups: Control group (saline), DEX (1 mg/kg, im) for 17 days, DEX+PSTi8 (acute 5 mg/kg and chronic 2 mg/kg, ip) for 10 days. The glucose, insulin and pyruvate tolerance tests (GTT, ITT and PTT), biochemical parameters and Oxymax-CLAMS were performed. Further to elucidate the action mechanisms of PSTi8, we performed genes expression and western blotting of biological samples. KEY FINDINGS We found that PSTi8 suppresses hepatic glucose release, lipid deposition, oxidative stress induced by DEX, stimulates the cellular energy level in hepatocytes and enhances GRP78 activity. It reduces lipogensis and enhances fatty acid oxidation to improve insulin sensitivity and glucose tolerance in DEX induced diabetic mice. The above cellular effects are the result of activated AMPK signalling pathway in liver, which increases Srebp1c and ACC phosphorylation. The increased ACC phosphorylation suppresses protein kinase C activity and enhances insulin sensitivity. The increased expression of UCP3 in liver elicits fatty acid oxidation and energy expenditure, which suppress oxidative stress. SIGNIFICANCE Thus the activation of AMPK signalling through GRP78, improves lipid homeostasis, enhances insulin sensitivity via inhibition of PKC activity. PSTi8 suppresses inflammation associated with incomplete fatty acid oxidation. Hence, PSTi8 may be a potential therapeutic agent to treat glucocorticoid-induced fatty liver associated type 2 diabetes.
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Affiliation(s)
- Anand P Gupta
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India
| | - Pragati Singh
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India
| | - Richa Garg
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Guru R Valicherla
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Mohammed Riyazuddin
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India
| | - Anees A Syed
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India
| | - Zakir Hossain
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India
| | - Jiaur R Gayen
- Pharmaceutics & Pharmacokinetics Division, CSIR-Central Drug Research Institute, Lucknow, 226031, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India.
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9
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Liang C, Mickey MC, Receno CN, Atalay M, DeRuisseau KC. Functional and biochemical responses of skeletal muscle following a moderate degree of systemic iron loading in mice. J Appl Physiol (1985) 2019; 126:799-809. [PMID: 30653415 DOI: 10.1152/japplphysiol.00237.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Excessive iron loading may cause skeletal muscle atrophy and weakness because of its free radical generating properties. To determine whether a clinically relevant degree of iron loading impairs skeletal muscle function, young male mice received injections of iron dextran (4 mg iron/200 µl) or 2 mM d-glucose (control) 5 days/week for 2 weeks ( n = 10/group). Systemic iron loading induced an approximate fourfold increase in the skeletal muscle nonheme iron concentration. Soleus specific tension (1, 30-250 Hz) was lower among iron-loaded animals compared with controls despite similar body mass and muscle mass. Soleus lipid peroxidation (4-hydroxynonenal adducts) and protein oxidation (protein carbonyls) levels were similar between groups. In gastrocnemius muscle, reduced glutathione (GSH) and glutathione peroxidase activity were similar but glutathione disulfide (GSSG) and the GSSG/GSH ratio were greater in iron-loaded muscle. A greater protein expression level of endogenous thiol antioxidant thioredoxin (TRX) was observed among iron-loaded muscle whereas its endogenous inhibitor thioredoxin-interacting protein (TXNip) and the TRX/TXNip ratio were similar. Glutaredoxin2, a thiol-disulfide oxidoreductase activated by GSSG-induced destabilization of its iron-sulfur [2Fe-2S] cluster, was lower following iron loading. Additionally, protein levels of α-actinin and αII-spectrin at 240 kDa were lower in the iron-loaded group. Ryanodine receptor stabilizing subunit calstabin1 was also lower following iron loading. In summary, the contractile dysfunction that resulted from moderate iron loading may be mediated by a disturbance in the muscle redox balance and from changes arising from an increased proteolytic response and aberrant sarcoplasmic reticulum Ca2+ release. NEW & NOTEWORTHY Although severe iron loading is known to cause muscle oxidative stress and dysfunction, the effects of a moderate degree of systemic iron loading on muscle contractile function and biochemical responses remain unclear. This study demonstrates that a pathophysiological elevation in the skeletal muscle iron load leads to force deficits that coincide with impaired redox status, structural integrity, and lower ryanodine receptor-associated calstabin1 in the absence of muscle mass changes or oxidative damage.
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Affiliation(s)
- Chen Liang
- Department of Exercise Science, Syracuse University , Syracuse, New York
| | - Marisa C Mickey
- Department of Exercise Science, Syracuse University , Syracuse, New York
| | - Candace N Receno
- Department of Exercise Science, Syracuse University , Syracuse, New York
| | - Mustafa Atalay
- Institute of Biomedicine, Physiology, University of Eastern Finland , Kuopio , Finland
| | - Keith C DeRuisseau
- Department of Exercise Science, Syracuse University , Syracuse, New York
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Gao Y, Liu J, Bai Z, Sink S, Zhao C, Lorenzo FR, McClain DA. Iron down-regulates leptin by suppressing protein O-GlcNAc modification in adipocytes, resulting in decreased levels of O-glycosylated CREB. J Biol Chem 2019; 294:5487-5495. [PMID: 30709903 DOI: 10.1074/jbc.ra118.005183] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 01/28/2019] [Indexed: 11/06/2022] Open
Abstract
We previously reported that iron down-regulates transcription of the leptin gene by increasing occupancy of phosphorylated cAMP response element-binding protein (pCREB) at two sites in the leptin gene promoter. Several nutrient-sensing pathways including O-GlcNAcylation also regulate leptin. We therefore investigated whether O-glycosylation plays a role in iron- and CREB-mediated regulation of leptin. We found that high iron decreases protein O-GlcNAcylation both in cultured 3T3-L1 adipocytes and in mice fed high-iron diets and down-regulates leptin mRNA and protein levels. Glucosamine treatment, which bypasses the rate-limiting step in the synthesis of substrate for glycosylation, increased both O-GlcNAc and leptin, whereas inhibition of O-glycosyltransferase (OGT) decreased O-GlcNAc and leptin. The increased leptin levels induced by glucosamine were susceptible to the inhibition by iron, but in the case of OGT inhibition, iron did not further decrease leptin. Mice with deletion of the O-GlcNAcase gene, either via whole-body heterozygous deletion or through adipocyte-targeted homozygous deletion, exhibited increased O-GlcNAc levels in adipose tissue and increased leptin levels that were inhibited by iron. Of note, iron increased the occupancy of pCREB and decreased the occupancy of O-GlcNAcylated CREB on the leptin promoter. These patterns observed in our experimental models suggest that iron exerts its effects on leptin by decreasing O-glycosylation and not by increasing protein deglycosylation and that neither O-GlcNAcase nor OGT mRNA and protein levels are affected by iron. We conclude that iron down-regulates leptin by decreasing CREB glycosylation, resulting in increased CREB phosphorylation and leptin promoter occupancy by pCREB.
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Affiliation(s)
- Yan Gao
- From the Department of Internal Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina 27157 and
| | - Jingfang Liu
- From the Department of Internal Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina 27157 and
| | - Zhenzhong Bai
- From the Department of Internal Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina 27157 and
| | - Sandy Sink
- From the Department of Internal Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina 27157 and
| | - Chengyu Zhao
- From the Department of Internal Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina 27157 and
| | - Felipe Ramos Lorenzo
- From the Department of Internal Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina 27157 and
| | - Donald A McClain
- From the Department of Internal Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina 27157 and .,the W. G. Hefner Veterans Affairs Medical Center, Salisbury, North Carolina 28144
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11
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Varghese J, James J, Vaulont S, Mckie A, Jacob M. Increased intracellular iron in mouse primary hepatocytes in vitro causes activation of the Akt pathway but decreases its response to insulin. Biochim Biophys Acta Gen Subj 2018; 1862:1870-1882. [PMID: 29859963 DOI: 10.1016/j.bbagen.2018.05.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 05/17/2018] [Accepted: 05/28/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND An iron-overloaded state has been reported to be associated with insulin resistance. On the other hand, conditions such as classical hemochromatosis (where iron overload occurs primarily in the liver) have been reported to be associated with increased insulin sensitivity. The reasons for these contradictory findings are unclear. In this context, the effects of increased intracellular iron per se on insulin signaling in hepatocytes are not known. METHODS Mouse primary hepatocytes were loaded with iron in vitro by incubation with ferric ammonium citrate (FAC). Intracellular events related to insulin signaling, as well as changes in gene expression and hepatocyte glucose production (HGP), were studied in the presence and absence of insulin and/or forskolin (a glucagon mimetic). RESULTS In vitro iron-loading of hepatocytes resulted in phosphorylation-mediated activation of Akt and AMP-activated protein kinase. This was associated with decreased basal and forskolin-stimulated HGP. Iron attenuated forskolin-mediated induction of the key gluconeogenic enzyme, glucose-6-phosphatase. It also attenuated activation of the Akt pathway in response to insulin, which was associated with decreased protein levels of insulin receptor substrates 1 and 2, constituting insulin resistance. CONCLUSIONS Increased intracellular iron has dual effects on insulin sensitivity in hepatocytes. It increased basal activation of the Akt pathway, but decreased activation of this pathway in response to insulin. GENERAL SIGNIFICANCE These findings may help explain why both insulin resistance and increased sensitivity have been observed in iron-overloaded states. They are of relevance to a variety of disease conditions characterized by hepatic iron overload and increased risk of diabetes.
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Affiliation(s)
- Joe Varghese
- Department of Biochemistry, Christian Medical College, Vellore 632002, India(1).
| | - Jithu James
- Department of Biochemistry, Christian Medical College, Vellore 632002, India(1)
| | | | - Andrew Mckie
- Diabetes and Nutritional Sciences Division, School of Medicine, King's College, London, UK
| | - Molly Jacob
- Department of Biochemistry, Christian Medical College, Vellore 632002, India(1)
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12
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Britton L, Jaskowski L, Bridle K, Santrampurwala N, Reiling J, Musgrave N, Subramaniam VN, Crawford D. Heterozygous Hfe gene deletion leads to impaired glucose homeostasis, but not liver injury in mice fed a high-calorie diet. Physiol Rep 2016; 4:4/12/e12837. [PMID: 27354540 PMCID: PMC4923236 DOI: 10.14814/phy2.12837] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 05/26/2016] [Indexed: 12/30/2022] Open
Abstract
Heterozygous mutations of the Hfe gene have been proposed as cofactors in the development and progression of nonalcoholic fatty liver disease (NAFLD). Homozygous Hfe deletion previously has been shown to lead to dysregulated hepatic lipid metabolism and accentuated liver injury in a dietary mouse model of NAFLD. We sought to establish whether heterozygous deletion of Hfe is sufficient to promote liver injury when mice are exposed to a high‐calorie diet (HCD). Eight‐week‐old wild‐type and Hfe+/− mice received 8 weeks of a control diet or HCD. Liver histology and pathways of lipid and iron metabolism were analyzed. Liver histology demonstrated that mice fed a HCD had increased NAFLD activity score (NAS), steatosis, and hepatocyte ballooning. However, liver injury was unaffected by Hfe genotype. Hepatic iron concentration (HIC) was increased in Hfe+/− mice of both dietary groups. HCD resulted in a hepcidin‐independent reduction in HIC. Hfe+/− mice demonstrated raised fasting serum glucose concentrations and HOMA‐IR score, despite unaltered serum adiponectin concentrations. Downstream regulators of hepatic de novo lipogenesis (pAKT, SREBP‐1, Fas, Scd1) and fatty acid oxidation (AdipoR2, Pparα, Cpt1) were largely unaffected by genotype. In summary, heterozygous Hfe gene deletion is associated with impaired iron and glucose metabolism. However, unlike homozygous Hfe deletion, heterozygous gene deletion did not affect lipid metabolism pathways or liver injury in this model.
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Affiliation(s)
- Laurence Britton
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia The Department of Gastroenterology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Lesley Jaskowski
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Kim Bridle
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia
| | - Nishreen Santrampurwala
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Janske Reiling
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia Department of Surgery, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Nick Musgrave
- Sullivan and Nicolaides Pathology, Greenslopes Private Hospital, Greenslopes, Queensland, Australia
| | | | - Darrell Crawford
- Gallipoli Medical Research Institute, Greenslopes Private Hospital, Greenslopes, Queensland, Australia The School of Medicine, University of Queensland, Herston, Queensland, Australia
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13
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Kim DK, Kim YH, Jung YS, Kim KS, Jeong JH, Lee YS, Yuk JM, Oh BC, Choy HE, Dooley S, Muckenthaler MU, Lee CH, Choi HS. Orphan nuclear receptor SHP regulates iron metabolism through inhibition of BMP6-mediated hepcidin expression. Sci Rep 2016; 6:34630. [PMID: 27688041 PMCID: PMC5043349 DOI: 10.1038/srep34630] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 09/12/2016] [Indexed: 02/08/2023] Open
Abstract
Small heterodimer partner (SHP) is a transcriptional corepressor regulating diverse metabolic processes. Here, we show that SHP acts as an intrinsic negative regulator of iron homeostasis. SHP-deficient mice maintained on a high-iron diet showed increased serum hepcidin levels, decreased expression of the iron exporter ferroportin as well as iron accumulation compared to WT mice. Conversely, overexpression of either SHP or AMP-activated protein kinase (AMPK), a metabolic sensor inducing SHP expression, suppressed BMP6-induced hepcidin expression. In addition, an inhibitory effect of AMPK activators metformin and AICAR on BMP6-mediated hepcidin gene expression was significantly attenuated by ablation of SHP expression. Interestingly, SHP physically interacted with SMAD1 and suppressed BMP6-mediated recruitment of the SMAD complex to the hepcidin gene promoter by inhibiting the formation of SMAD1 and SMAD4 complex. Finally, overexpression of SHP and metformin treatment of BMP6 stimulated mice substantially restored hepcidin expression and serum iron to baseline levels. These results reveal a previously unrecognized role for SHP in the transcriptional control of iron homeostasis.
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Affiliation(s)
- Don-Kyu Kim
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Yong-Hoon Kim
- Korea Research Institute of Bioscience and Biotechnology, University of Science and Technology (UST), Yuseong-gu, Daejeon, Republic of Korea
| | - Yoon Seok Jung
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Ki-Sun Kim
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Jae-Ho Jeong
- Department of Microbiology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Yong-Soo Lee
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | - Jae-Min Yuk
- Department of Medical Science and Infection Biology, Chungnam National University School of Medicine, Daegeon, Republic of Korea
| | - Byung-Chul Oh
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University Graduate School of Medicine, Incheon, Republic of Korea
| | - Hyon E Choy
- Department of Microbiology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Steven Dooley
- Department of Medicine II, Section Molecular Hepatology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Martina U Muckenthaler
- Department of Pediatric Oncology, Hematology and Immunology, University of Heidelberg, Heidelberg, Germany.,Molecular Medicine Partnership Unit, University of Heidelberg, Heidelberg, Germany
| | - Chul-Ho Lee
- Korea Research Institute of Bioscience and Biotechnology, University of Science and Technology (UST), Yuseong-gu, Daejeon, Republic of Korea
| | - Hueng-Sik Choi
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
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14
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Britton LJ, Subramaniam VN, Crawford DHG. Iron and non-alcoholic fatty liver disease. World J Gastroenterol 2016; 22:8112-8122. [PMID: 27688653 PMCID: PMC5037080 DOI: 10.3748/wjg.v22.i36.8112] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 07/06/2016] [Accepted: 08/05/2016] [Indexed: 02/06/2023] Open
Abstract
The mechanisms that promote liver injury in non-alcoholic fatty liver disease (NAFLD) are yet to be thoroughly elucidated. As such, effective treatment strategies are lacking and novel therapeutic targets are required. Iron has been widely implicated in the pathogenesis of NAFLD and represents a potential target for treatment. Relationships between serum ferritin concentration and NAFLD are noted in a majority of studies, although serum ferritin is an imprecise measure of iron loading. Numerous mechanisms for a pathogenic role of hepatic iron in NAFLD have been demonstrated in animal and cell culture models. However, the human data linking hepatic iron to liver injury in NAFLD is less clear, with seemingly conflicting evidence, supporting either an effect of iron in hepatocytes or within reticulo-endothelial cells. Adipose tissue has emerged as a key site at which iron may have a pathogenic role in NAFLD. Evidence for this comes indirectly from studies that have evaluated the role of adipose tissue iron with respect to insulin resistance. Adding further complexity, multiple strands of evidence support an effect of NAFLD itself on iron metabolism. In this review, we summarise the human and basic science data that has evaluated the role of iron in NAFLD pathogenesis.
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15
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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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16
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Gao Y, Li Z, Gabrielsen JS, Simcox JA, Lee SH, Jones D, Cooksey B, Stoddard G, Cefalu WT, McClain DA. Adipocyte iron regulates leptin and food intake. J Clin Invest 2015; 125:3681-91. [PMID: 26301810 DOI: 10.1172/jci81860] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/17/2015] [Indexed: 12/17/2022] Open
Abstract
Dietary iron supplementation is associated with increased appetite. Here, we investigated the effect of iron on the hormone leptin, which regulates food intake and energy homeostasis. Serum ferritin was negatively associated with serum leptin in a cohort of patients with metabolic syndrome. Moreover, the same inverse correlation was observed in mice fed a high-iron diet. Adipocyte-specific loss of the iron exporter ferroportin resulted in iron loading and decreased leptin, while decreased levels of hepcidin in a murine hereditary hemochromatosis (HH) model increased adipocyte ferroportin expression, decreased adipocyte iron, and increased leptin. Treatment of 3T3-L1 adipocytes with iron decreased leptin mRNA in a dose-dependent manner. We found that iron negatively regulates leptin transcription via cAMP-responsive element binding protein activation (CREB activation) and identified 2 potential CREB-binding sites in the mouse leptin promoter region. Mutation of both sites completely blocked the effect of iron on promoter activity. ChIP analysis revealed that binding of phosphorylated CREB is enriched at these two sites in iron-treated 3T3-L1 adipocytes compared with untreated cells. Consistent with the changes in leptin, dietary iron content was also directly related to food intake, independently of weight. These findings indicate that levels of dietary iron play an important role in regulation of appetite and metabolism through CREB-dependent modulation of leptin expression.
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17
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Aigner E, Weiss G, Datz C. Dysregulation of iron and copper homeostasis in nonalcoholic fatty liver. World J Hepatol 2015; 7:177-188. [PMID: 25729473 PMCID: PMC4342600 DOI: 10.4254/wjh.v7.i2.177] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 12/12/2014] [Accepted: 12/31/2014] [Indexed: 02/06/2023] Open
Abstract
Elevated iron stores as indicated by hyperferritinemia with normal or mildly elevated transferrin saturation and mostly mild hepatic iron deposition are a characteristic finding in subjects with non-alcoholic fatty liver disease (NAFLD). Excess iron is observed in approximately one third of NAFLD patients and is commonly referred to as the “dysmetabolic iron overload syndrome”. Clinical evidence suggests that elevated body iron stores aggravate the clinical course of NAFLD with regard to liver-related and extrahepatic disease complications which relates to the fact that excess iron catalyses the formation of toxic hydroxyl-radicals subsequently resulting in cellular damage. Iron removal improves insulin sensitivity, delays the onset of type 2 diabetes mellitus, improves pathologic liver function tests and likewise ameliorates NAFLD histology. Several mechanisms contribute to pathologic iron accumulation in NAFLD. These include impaired iron export from hepatocytes and mesenchymal Kupffer cells as a consequence of imbalances in the concentrations of iron regulatory factors, such as hepcidin, cytokines, copper or other dietary factors. This review summarizes the knowledge about iron homeostasis in NAFLD and the rationale for its therapeutic implications.
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18
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Padda RS, Gkouvatsos K, Guido M, Mui J, Vali H, Pantopoulos K. A high-fat diet modulates iron metabolism but does not promote liver fibrosis in hemochromatotic Hjv⁻/⁻ mice. Am J Physiol Gastrointest Liver Physiol 2015; 308:G251-61. [PMID: 25501544 DOI: 10.1152/ajpgi.00137.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hemojuvelin (Hjv) is a membrane protein that controls body iron metabolism by enhancing signaling to hepcidin. Hjv mutations cause juvenile hemochromatosis, a disease of systemic iron overload. Excessive iron accumulation in the liver progressively leads to inflammation and disease, such as fibrosis, cirrhosis, or hepatocellular cancer. Fatty liver (steatosis) may also progress to inflammation (steatohepatitis) and liver disease, and iron is considered as pathogenic cofactor. The aim of this study was to investigate the pathological implications of parenchymal iron overload due to Hjv ablation in the fatty liver. Wild-type (WT) and Hjv(-/-) mice on C57BL/6 background were fed a standard chow, a high-fat diet (HFD), or a HFD supplemented with 2% carbonyl iron (HFD+Fe) for 12 wk. The animals were analyzed for iron and lipid metabolism. As expected, all Hjv(-/-) mice manifested higher serum and hepatic iron and diminished hepcidin levels compared with WT controls. The HFD reduced iron indexes and promoted liver steatosis in both WT and Hjv(-/-) mice. Notably, steatosis was attenuated in Hjv(-/-) mice on the HFD+Fe regimen. Hjv(-/-) animals gained less body weight and exhibited reduced serum glucose and cholesterol levels. Histological and ultrastructural analysis revealed absence of iron-induced inflammation or liver fibrosis despite early signs of liver injury (expression of α-smooth muscle actin). We conclude that parenchymal hepatic iron overload does not suffice to trigger progression of liver steatosis to steatohepatitis or fibrosis in C57BL/6 mice.
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Affiliation(s)
- Ranjit Singh Padda
- Lady Davis Institute for Medical Research, Jewish General Hospital, and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Konstantinos Gkouvatsos
- Lady Davis Institute for Medical Research, Jewish General Hospital, and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Maria Guido
- Department of Diagnostic Sciences and Special Therapies, University of Padova, Padova, Italy; and
| | - Jeannie Mui
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Hojatollah Vali
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Kostas Pantopoulos
- Lady Davis Institute for Medical Research, Jewish General Hospital, and Department of Medicine, McGill University, Montreal, Quebec, Canada;
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19
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Abbas MA, Abraham D, Kushner JP, McClain DA. Anti-obesity and pro-diabetic effects of hemochromatosis. Obesity (Silver Spring) 2014; 22:2120-2. [PMID: 25044717 PMCID: PMC4180762 DOI: 10.1002/oby.20839] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 06/26/2014] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Levels of tissue iron contribute to determining diabetes risk, but little is known about the effects of higher iron levels on weight, and on the interaction of weight and iron overload on diabetes risk. Therefore, the effect of iron on body mass index and diabetes in individuals with iron overload from hereditary hemochromatosis (HH), compared to non-HH siblings and historical controls was examined. METHODS Chart reviews were performed on a cohort of adults (age ≥40, N = 101) with the common C282Y/C282Y HFE genotype, compared to wild type siblings (N = 32) and comparable NHANES cohorts, with respect to body mass index and diabetes status. RESULTS Males with HH have lower body mass index (BMI) than control siblings. Females had a trend toward decreased BMI that was not significant, possibly related to decreased degrees of iron overload. In both males and females, increased rates of diabetes were seen, especially in the overweight or obese. CONCLUSIONS High tissue iron levels may be both pro- and anti-diabetic. The prevalence of obesity and diabetes in HH is likely dependent upon the degree of iron overload, caloric intake, and other genetic and environmental factors, contributing to the observed heterogeneity in the frequency of disease-related morbidities in HH.
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Affiliation(s)
- Mousa Al Abbas
- Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Deveraprabu Abraham
- Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - James P. Kushner
- Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Donald A. McClain
- Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
- Salt Lake City Veterans Administration Health Care System, Salt Lake City, UT 84132
- Corresponding Author: Donald A. McClain, M.D., Ph.D. Department of Medicine, Division of Endocrinology, University of Utah 15 North 2030 East Bldg 533, Room 3110B Phone: 801458746736 Fax: 801458540956
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20
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Coffey R, Nam H, Knutson MD. Microarray analysis of rat pancreas reveals altered expression of Alox15 and regenerating islet-derived genes in response to iron deficiency and overload. PLoS One 2014; 9:e86019. [PMID: 24465846 PMCID: PMC3897611 DOI: 10.1371/journal.pone.0086019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 12/04/2013] [Indexed: 12/27/2022] Open
Abstract
It is well known that iron overload can result in pancreatic iron deposition, beta-cell destruction, and diabetes in humans. Recent studies in animals have extended the link between iron status and pancreatic function by showing that iron depletion confers protection against beta-cell dysfunction and diabetes. The aim of the present study was to identify genes in the pancreas that are differentially expressed in response to iron deficiency or overload. Weanling male Sprague-Dawley rats (n = 6/group) were fed iron-deficient, iron-adequate, or iron-overloaded diets for 3 weeks to alter their iron status. Total RNA was isolated from the pancreases and pooled within each group for microarray analyses in which gene expression levels were compared to those in iron-adequate controls. In iron-deficient pancreas, a total of 66 genes were found to be differentially regulated (10 up, 56 down), whereas in iron-overloaded pancreas, 164 genes were affected (82 up, 82 down). The most up-regulated transcript in iron-deficient pancreas was arachidonate 15-lipoxygenase (Alox15), which has been implicated in the development of diabetes. In iron-overloaded pancreas, the most upregulated transcripts were Reg1a, Reg3a, and Reg3b belonging to the regenerating islet-derived gene (Reg) family. Reg expression has been observed in response to pancreatic stress and is thought to facilitate pancreatic regeneration. Subsequent qRT-PCR validation indicated that Alox15 mRNA levels were 4 times higher in iron-deficient than in iron-adequate pancreas and that Reg1a, Reg3a, and Reg3b mRNA levels were 17–36 times higher in iron-overloaded pancreas. The elevated Alox15 mRNA levels in iron-deficient pancreas were associated with 8-fold higher levels of Alox15 protein as indicated by Western blotting. Overall, these data raise the possibility that Reg expression may serve as a biomarker for iron-related pancreatic stress, and that iron deficiency may adversely affect the risk of developing diabetes through up-regulation of Alox15.
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Affiliation(s)
- Richard Coffey
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, United States of America
| | - Hyeyoung Nam
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, United States of America
| | - Mitchell D. Knutson
- Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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21
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Parra V, Verdejo HE, Iglewski M, del Campo A, Troncoso R, Jones D, Zhu Y, Kuzmicic J, Pennanen C, Lopez‑Crisosto C, Jaña F, Ferreira J, Noguera E, Chiong M, Bernlohr DA, Klip A, Hill JA, Rothermel BA, Abel ED, Zorzano A, Lavandero S. Insulin stimulates mitochondrial fusion and function in cardiomyocytes via the Akt-mTOR-NFκB-Opa-1 signaling pathway. Diabetes 2014; 63:75-88. [PMID: 24009260 PMCID: PMC3868041 DOI: 10.2337/db13-0340] [Citation(s) in RCA: 174] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 08/23/2013] [Indexed: 12/12/2022]
Abstract
Insulin regulates heart metabolism through the regulation of insulin-stimulated glucose uptake. Studies have indicated that insulin can also regulate mitochondrial function. Relevant to this idea, mitochondrial function is impaired in diabetic individuals. Furthermore, the expression of Opa-1 and mitofusins, proteins of the mitochondrial fusion machinery, is dramatically altered in obese and insulin-resistant patients. Given the role of insulin in the control of cardiac energetics, the goal of this study was to investigate whether insulin affects mitochondrial dynamics in cardiomyocytes. Confocal microscopy and the mitochondrial dye MitoTracker Green were used to obtain three-dimensional images of the mitochondrial network in cardiomyocytes and L6 skeletal muscle cells in culture. Three hours of insulin treatment increased Opa-1 protein levels, promoted mitochondrial fusion, increased mitochondrial membrane potential, and elevated both intracellular ATP levels and oxygen consumption in cardiomyocytes in vitro and in vivo. Consequently, the silencing of Opa-1 or Mfn2 prevented all the metabolic effects triggered by insulin. We also provide evidence indicating that insulin increases mitochondrial function in cardiomyocytes through the Akt-mTOR-NFκB signaling pathway. These data demonstrate for the first time in our knowledge that insulin acutely regulates mitochondrial metabolism in cardiomyocytes through a mechanism that depends on increased mitochondrial fusion, Opa-1, and the Akt-mTOR-NFκB pathway.
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Affiliation(s)
- Valentina Parra
- Advanced Center for Chronic Diseases (ACCDIS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
- Department of Internal Medicine (Cardiology) and Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Hugo E. Verdejo
- Advanced Center for Chronic Diseases (ACCDIS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento Enfermedades Cardiovasculares, Facultad Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Myriam Iglewski
- Department of Internal Medicine (Cardiology) and Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Andrea del Campo
- Advanced Center for Chronic Diseases (ACCDIS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Rodrigo Troncoso
- Advanced Center for Chronic Diseases (ACCDIS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Deborah Jones
- Program in Molecular Medicine and Division of Endocrinology, Metabolism, and Diabetes, University of Utah School of Medicine, Salt Lake City, UT
| | - Yi Zhu
- Program in Molecular Medicine and Division of Endocrinology, Metabolism, and Diabetes, University of Utah School of Medicine, Salt Lake City, UT
| | - Jovan Kuzmicic
- Advanced Center for Chronic Diseases (ACCDIS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Christian Pennanen
- Advanced Center for Chronic Diseases (ACCDIS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Camila Lopez‑Crisosto
- Advanced Center for Chronic Diseases (ACCDIS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Fabián Jaña
- Programa de Farmacología Molecular y Clínica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Jorge Ferreira
- Programa de Farmacología Molecular y Clínica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | | | - Mario Chiong
- Advanced Center for Chronic Diseases (ACCDIS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - David A. Bernlohr
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota: Twin Cities, Minneapolis, MN
| | - Amira Klip
- The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Joseph A. Hill
- Department of Internal Medicine (Cardiology) and Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Beverly A. Rothermel
- Department of Internal Medicine (Cardiology) and Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Evan Dale Abel
- Program in Molecular Medicine and Division of Endocrinology, Metabolism, and Diabetes, University of Utah School of Medicine, Salt Lake City, UT
| | | | - Sergio Lavandero
- Advanced Center for Chronic Diseases (ACCDIS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Departamento de Bioquímica y Biología Molecular, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
- Department of Internal Medicine (Cardiology) and Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX
- Programa de Biología Molecular y Celular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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22
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Evaluation of Different Normalization and Analysis Procedures for Illumina Gene Expression Microarray Data Involving Small Changes. MICROARRAYS 2013; 2:131-52. [PMID: 27605185 PMCID: PMC5003482 DOI: 10.3390/microarrays2020131] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 05/08/2013] [Accepted: 05/10/2013] [Indexed: 12/28/2022]
Abstract
While Illumina microarrays can be used successfully for detecting small gene expression changes due to their high degree of technical replicability, there is little information on how different normalization and differential expression analysis strategies affect outcomes. To evaluate this, we assessed concordance across gene lists generated by applying different combinations of normalization strategy and analytical approach to two Illumina datasets with modest expression changes. In addition to using traditional statistical approaches, we also tested an approach based on combinatorial optimization. We found that the choice of both normalization strategy and analytical approach considerably affected outcomes, in some cases leading to substantial differences in gene lists and subsequent pathway analysis results. Our findings suggest that important biological phenomena may be overlooked when there is a routine practice of using only one approach to investigate all microarray datasets. Analytical artefacts of this kind are likely to be especially relevant for datasets involving small fold changes, where inherent technical variation-if not adequately minimized by effective normalization-may overshadow true biological variation. This report provides some basic guidelines for optimizing outcomes when working with Illumina datasets involving small expression changes.
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Dongiovanni P, Ruscica M, Rametta R, Recalcati S, Steffani L, Gatti S, Girelli D, Cairo G, Magni P, Fargion S, Valenti L. Dietary iron overload induces visceral adipose tissue insulin resistance. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 182:2254-63. [PMID: 23578384 DOI: 10.1016/j.ajpath.2013.02.019] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 01/08/2013] [Accepted: 02/04/2013] [Indexed: 02/07/2023]
Abstract
Increased iron stores associated with elevated levels of the iron hormone hepcidin are a frequent feature of the metabolic syndrome. The aim of this study was to assess the effect of dietary iron supplementation on insulin resistance and the role of hepcidin in C57Bl/6 male mice fed a standard or iron-enriched diet for 16 weeks. Iron supplementation increased hepatic iron and serum hepcidin fivefold and led to a 40% increase in fasting glucose due to insulin resistance, as confirmed by the insulin tolerance test, and to threefold higher levels of triglycerides. Iron supplemented mice had lower visceral adipose tissue mass estimated by epididymal fat pad, associated with iron accumulation in adipocytes. Decreased insulin signaling, evaluated by the phospho-Akt/Akt ratio, was detected in the visceral adipose tissue of iron overloaded mice, and gene expression analysis of visceral adipose tissue showed that an iron-enriched diet up-regulated iron-responsive genes and adipokines, favoring insulin resistance, whereas lipoprotein lipase was down-regulated. This resulted in hyperresistinemia and increased visceral adipose tissue expression of suppressor of cytokine signaling-3 (Socs3), a target of resistin and hepcidin implicated in insulin resistance. Acute hepcidin administration down-regulated lipoprotein lipase and up-regulated Socs3 in visceral adipose tissue. In conclusion, we characterized a model of dysmetabolic iron overload syndrome in which an iron-enriched diet induces insulin resistance and hypertriglyceridemia and affects visceral adipose tissue metabolism by a mechanism involving hepcidin up-regulation.
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Affiliation(s)
- Paola Dongiovanni
- Department of Pathophysiology and Transplantation, Centro Malattie Metaboliche del Fegato, Università degli Studi di Milano, and Internal Medicine, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milano, Italy
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24
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Huang J, Simcox J, Mitchell TC, Jones D, Cox J, Luo B, Cooksey RC, Boros LG, McClain DA. Iron regulates glucose homeostasis in liver and muscle via AMP-activated protein kinase in mice. FASEB J 2013; 27:2845-54. [PMID: 23515442 DOI: 10.1096/fj.12-216929] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Excess iron is associated with hepatic damage and diabetes in humans, although the detailed molecular mechanisms are not known. To investigate how iron regulates glucose homeostasis, we fed C57BL/6J male mice with high-iron (HI) diets (2 or 20 g Fe/kg chow). Mice fed an HI diet exhibited elevated AMP-activated protein kinase (AMPK) activity and impaired insulin signaling in skeletal muscle and liver. Consistent with the increased AMPK activity, glucose uptake was enhanced in mice fed an HI diet. The effects of improved glucose tolerance induced by HI feeding were abolished in transgenic mice with expression of muscle specific dominant-negative AMPK. Glucose output was suppressed in the liver of wild-type mice fed an HI diet, due to decreased expression of gluconeogenic genes and decreased substrate (lactate) from peripheral glycolysis. Iron activated AMPK by increasing deacetylase and decreasing LKB1 acetylation, in turn stimulating the phosphorylation of LKB1 and AMPK. The effects of HI diet were abrogated by treatment of the mice with N-acetyl cysteine, suggesting a redox-dependent mechanism for increasing deacetylase activity. In addition, tissue from iron-fed mice exhibited an elevated AMP/ATP ratio, further contributing to AMPK activation. In summary, a diet high in iron improves glucose tolerance by activating AMPK through mechanisms that include deacetylation.
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Affiliation(s)
- Jingyu Huang
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA
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25
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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: 345] [Impact Index Per Article: 31.4] [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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26
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Abstract
Obesity promotes increased secretion of a number of inflammatory factors from adipose tissue. These factors include cytokines and very lately, extracellular matrix components (ECM). Biglycan, a small leucine rich proteoglycan ECM protein, is up-regulated in obesity and has recently been recognized as a pro-inflammatory molecule. However, it is unknown whether biglycan contributes to adipose tissue dysfunction. In the present study, we characterized biglycan expression in various adipose depots in wild-type mice fed a low fat diet (LFD) or obesity-inducing high fat diet (HFD). High fat feeding induced biglycan mRNA expression in multiple adipose depots. Adiponectin is an adipokine with anti-inflammatory and insulin sensitizing effects. Due to the importance of adiponectin, we examined the effect of biglycan on adiponectin expression. Comparison of adiponectin expression in biglycan knockout (bgn(-/0)) and wild-type (bgn(+/0)) reveals higher adiponectin mRNA and protein in epididymal white adipose tissue in bgn(-/0) mice, as well higher serum concentration of adiponectin, and lower serum insulin concentration. On the contrary, knockdown of biglycan in 3T3-L1 adipocytes led to decreased expression and secretion of adiponectin. Furthermore, treatment of 3T3-L1 adipocytes with conditioned medium from biglycan treated macrophages resulted in an increase in adiponectin mRNA expression. These data suggest a link between biglycan and adiponectin expression. However, the difference in the pattern of regulation between in vivo and in vitro settings reveals the complexity of this relationship.
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27
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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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28
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Iron in fatty liver and in the metabolic syndrome: a promising therapeutic target. J Hepatol 2011; 55:920-32. [PMID: 21718726 DOI: 10.1016/j.jhep.2011.05.008] [Citation(s) in RCA: 240] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 05/29/2011] [Accepted: 05/31/2011] [Indexed: 12/17/2022]
Abstract
The dysmetabolic iron overload syndrome (DIOS) is now a frequent finding in the general population, as is detected in about one third of patients with nonalcoholic fatty liver disease (NAFLD) and the metabolic syndrome. The pathogenesis is related to altered regulation of iron transport associated with steatosis, insulin resistance, and subclinical inflammation, often in the presence of predisposing genetic factors. Evidence is accumulating that excessive body iron plays a causal role in insulin resistance through still undefined mechanisms that probably involve a reduced ability to burn carbohydrates and altered function of adipose tissue. Furthermore, DIOS may facilitate the evolution to type 2 diabetes by altering beta-cell function, the progression of cardiovascular disease by contributing to the recruitment and activation of macrophages within arterial lesions, and the natural history of liver disease by inducing oxidative stress in hepatocytes, activation of hepatic stellate cells, and malignant transformation by promotion of cell growth and DNA damage. Based on these premises, the association among DIOS, metabolic syndrome, and NAFLD is being investigated as a new risk factor to predict the development of overt cardiovascular and hepatic diseases, and possibly hepatocellular carcinoma, but most importantly, represents also a treatable condition. Indeed, iron depletion, most frequently achieved by phlebotomy, has been shown to decrease metabolic alterations and liver enzymes in controlled studies in NAFLD. Additional studies are warranted to evaluate the potential of iron reductive therapy on hard clinical outcomes in patients with DIOS.
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29
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Huang J, Jones D, Luo B, Sanderson M, Soto J, Abel ED, Cooksey RC, McClain DA. Iron overload and diabetes risk: a shift from glucose to Fatty Acid oxidation and increased hepatic glucose production in a mouse model of hereditary hemochromatosis. Diabetes 2011; 60:80-7. [PMID: 20876715 PMCID: PMC3012200 DOI: 10.2337/db10-0593] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Excess tissue iron levels are a risk factor for diabetes, but the mechanisms underlying the association are incompletely understood. We previously published that mice and humans with a form of hereditary iron overload, hemochromatosis, exhibit loss of β-cell mass. This effect by itself is not sufficient, however, to fully explain the diabetes risk phenotype associated with all forms of iron overload. RESEARCH DESIGN AND METHODS We therefore examined glucose and fatty acid metabolism and hepatic glucose production in vivo and in vitro in a mouse model of hemochromatosis in which the gene most often mutated in the human disease, HFE, has been deleted (Hfe⁻(/)⁻). RESULTS Although Hfe⁻(/)⁻ mice exhibit increased glucose uptake in skeletal muscle, glucose oxidation is decreased and the ratio of fatty acid to glucose oxidation is increased. On a high-fat diet, the Hfe⁻(/)⁻ mice exhibit increased fatty acid oxidation and are hypermetabolic. The decreased glucose oxidation in skeletal muscle is due to decreased pyruvate dehydrogenase (PDH) enzyme activity related, in turn, to increased expression of PDH kinase 4 (pdk4). Increased substrate recycling to liver contributes to elevated hepatic glucose production in the Hfe⁻(/)⁻ mice. CONCLUSIONS Increased hepatic glucose production and metabolic inflexibility, both of which are characteristics of type 2 diabetes, may contribute to the risk of diabetes with excessive tissue iron.
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Affiliation(s)
- Jingyu Huang
- Departments of Medicine and Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah
| | - Deborah Jones
- Departments of Medicine and Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah
| | - Bai Luo
- Departments of Medicine and Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah
| | - Michael Sanderson
- Departments of Medicine and Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah
| | - Jamie Soto
- Departments of Medicine and Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah
| | - E. Dale Abel
- Departments of Medicine and Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah
| | - Robert C. Cooksey
- Departments of Medicine and Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah
- Research Service, VA Medical Center, Salt Lake City, Utah
| | - Donald A. McClain
- Departments of Medicine and Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah
- Research Service, VA Medical Center, Salt Lake City, Utah
- Corresponding author: Donald A. McClain,
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30
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Cooksey RC, Jones D, Gabrielsen S, Huang J, Simcox JA, Luo B, Soesanto Y, Rienhoff H, Abel ED, McClain DA. Dietary iron restriction or iron chelation protects from diabetes and loss of beta-cell function in the obese (ob/ob lep-/-) mouse. Am J Physiol Endocrinol Metab 2010; 298:E1236-43. [PMID: 20354157 PMCID: PMC2886527 DOI: 10.1152/ajpendo.00022.2010] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Iron overload can cause insulin deficiency, but in some cases this may be insufficient to result in diabetes. We hypothesized that the protective effects of decreased iron would be more significant with increased beta-cell demand and stress. Therefore, we treated the ob/ob mouse model of type 2 diabetes with an iron-restricted diet (35 mg/kg iron) or with an oral iron chelator. Control mice were fed normal chow containing 500 mg/kg iron. Neither treatment resulted in iron deficiency or anemia. The low-iron diet significantly ameliorated diabetes in the mice. The effect was long lasting and reversible. Ob/ob mice on the low-iron diet exhibited significant increases in insulin sensitivity and beta-cell function, consistent with the phenotype in mouse models of hereditary iron overload. The effects were not accounted for by changes in weight or feeding behavior. Treatment with iron chelation had a more dramatic effect, allowing the ob/ob mice to maintain normal glucose tolerance for at least 10.5 wk despite no effect on weight. Although dietary iron restriction preserved beta-cell function in ob/ob mice fed a high-fat diet, the effects on overall glucose levels were less apparent due to a loss of the beneficial effects of iron on insulin sensitivity. Beneficial effects of iron restriction were minimal in wild-type mice on normal chow but were apparent in mice on high-fat diets. We conclude that, even at "normal" levels, iron exerts detrimental effects on beta-cell function that are reversible with dietary restriction or pharmacotherapy.
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MESH Headings
- Animals
- Calorimetry, Indirect
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/physiopathology
- Diabetes Mellitus, Type 2/prevention & control
- Glucose/metabolism
- Glucose Tolerance Test
- Insulin Resistance/physiology
- Insulin-Secreting Cells/physiology
- Iron Chelating Agents/pharmacology
- Iron, Dietary/administration & dosage
- Iron, Dietary/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Obese
- Mitochondria, Heart/metabolism
- Oxygen Consumption/physiology
- Regression Analysis
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Affiliation(s)
- Robert C Cooksey
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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31
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Beger RD, Hansen DK, Schnackenberg LK, Cross BM, Fatollahi JJ, Lagunero FT, Sarnyai Z, Boros LG. Single valproic acid treatment inhibits glycogen and RNA ribose turnover while disrupting glucose-derived cholesterol synthesis in liver as revealed by the [U-C(6)]-d-glucose tracer in mice. Metabolomics 2009; 5:336-345. [PMID: 19718458 PMCID: PMC2731156 DOI: 10.1007/s11306-009-0159-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Accepted: 03/04/2009] [Indexed: 11/26/2022]
Abstract
Previous genetic and proteomic studies identified altered activity of various enzymes such as those of fatty acid metabolism and glycogen synthesis after a single toxic dose of valproic acid (VPA) in rats. In this study, we demonstrate the effect of VPA on metabolite synthesis flux rates and the possible use of abnormal (13)C labeled glucose-derived metabolites in plasma or urine as early markers of toxicity. Female CD-1 mice were injected subcutaneously with saline or 600 mg/kg) VPA. Twelve hours later, the mice were injected with an intraperitoneal load of 1 g/kg [U-(13)C]-d-glucose. (13)C isotopomers of glycogen glucose and RNA ribose in liver, kidney and brain tissue, as well as glucose disposal via cholesterol and glucose in the plasma and urine were determined. The levels of all of the positional (13)C isotopomers of glucose were similar in plasma, suggesting that a single VPA dose does not disturb glucose absorption, uptake or hepatic glucose metabolism. Three-hour urine samples showed an increase in the injected tracer indicating a decreased glucose re-absorption via kidney tubules. (13)C labeled glucose deposited as liver glycogen or as ribose of RNA were decreased by VPA treatment; incorporation of (13)C via acetyl-CoA into plasma cholesterol was significantly lower at 60 min. The severe decreases in glucose-derived carbon flux into plasma and kidney-bound cholesterol, liver glycogen and RNA ribose synthesis, as well as decreased glucose re-absorption and an increased disposal via urine all serve as early flux markers of VPA-induced adverse metabolic effects in the host.
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Affiliation(s)
- Richard D. Beger
- National Center for Toxicological Research (NCTR), United States Food and Drug Administration, Jefferson, AR USA
| | - Deborah K. Hansen
- National Center for Toxicological Research (NCTR), United States Food and Drug Administration, Jefferson, AR USA
| | - Laura K. Schnackenberg
- National Center for Toxicological Research (NCTR), United States Food and Drug Administration, Jefferson, AR USA
| | | | | | | | - Zoltan Sarnyai
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Laszlo G. Boros
- SiDMAP, LLC., Los Angeles, CA USA
- UCLA School of Medicine, University of California, Los Angeles, CA USA
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32
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Villafuerte BC, Barati MT, Song Y, Moore JP, Epstein PN, Portillo J. Transgenic expression of insulin-response element binding protein-1 in beta-cells reproduces type 2 diabetes. Endocrinology 2009; 150:2611-7. [PMID: 19213832 PMCID: PMC2689803 DOI: 10.1210/en.2008-1294] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recent evidence supports the idea that insulin signaling through the insulin receptor substrate/phosphatidyl-inositol 3-kinase/Akt pathway is involved in the maintenance of beta-cell mass and function. We previously identified the insulin-response element binding protein-1 (IRE-BP1) as an effector of insulin-induced Akt signaling in the liver, and showed that the 50-kDa carboxyl fragment confers the transcriptional activity of this factor. In this investigation we found that IRE-BP1 is expressed in the alpha, beta, and delta-cells of the islets of Langerhans, and is localized to the cytoplasm in beta-cells in normal rats, but is reduced and redistributed to the islet cell nuclei in obese Zucker rats. To test whether IRE-BP1 modulates beta-cell function and insulin secretion, we used the rat insulin II promoter to drive expression of the carboxyl fragment in beta-cells. Transgenic expression of IRE-BP1 in FVB mice increases nuclear IRE-BP1 expression, and produces a phenotype similar to that of type 2 diabetes, with hyperinsulinemia, hyperglycemia, and increased body weight. IRE-BP1 increased islet type I IGF receptor expression, potentially contributing to the development of islet hypertrophy. Our findings suggest that increased gene transcription mediated through IRE-BP1 may contribute to beta-cell dysfunction in insulin resistance, and allow for the hypothesis that IRE-BP1 plays a role in the pathophysiology of type 2 diabetes.
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Affiliation(s)
- Betty C Villafuerte
- Department of Medicine, Division of Endocrinology & Metabolism, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA.
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33
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Gross DR. Other Transgenic Animal Models Used in Cardiovascular Studies. ANIMAL MODELS IN CARDIOVASCULAR RESEARCH 2009. [PMCID: PMC7121723 DOI: 10.1007/978-0-387-95962-7_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Previous chapters have described a large number of transgenic animal models used to study specific cardiovascular syndromes. This chapter will fill in some gaps. Many of these transgenic animals were developed to study normal and/or abnormal physiological responses in other organ systems, or to study basic biochemical and molecular reactions or pathways. These models were then discovered to also have effects on the cardiovascular system, some of them unanticipated. A word of caution, particularly when highly inbred mouse strains are used to develop transgenic models - not all strains of a particular species are created equal. When cardiovascular parameters of age- and sex-matched A/J and C57BL/6J inbred mice were compared the C57BL/6J mice demonstrated eccentric physiologic ventricular hypertrophy, increased ventricular function, lower heart rates, and increased exercise endurance.1
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34
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Jouihan HA, Cobine PA, Cooksey RC, Hoagland EA, Boudina S, Abel ED, Winge DR, McClain DA. Iron-mediated inhibition of mitochondrial manganese uptake mediates mitochondrial dysfunction in a mouse model of hemochromatosis. Mol Med 2008; 14:98-108. [PMID: 18317567 DOI: 10.2119/2007-00114.jouihan] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Accepted: 12/28/2007] [Indexed: 12/14/2022] Open
Abstract
Previous phenotyping of glucose homeostasis and insulin secretion in a mouse model of hereditary hemochromatosis (Hfe(-/-)) and iron overload suggested mitochondrial dysfunction. Mitochondria from Hfe(-/-) mouse liver exhibited decreased respiratory capacity and increased lipid peroxidation. Although the cytosol contained excess iron, Hfe(-/-) mitochondria contained normal iron but decreased copper, manganese, and zinc, associated with reduced activities of copper-dependent cytochrome c oxidase and manganese-dependent superoxide dismutase (MnSOD). The attenuation in MnSOD activity was due to substantial levels of unmetallated apoprotein. The oxidative damage in Hfe(-/-) mitochondria is due to diminished MnSOD activity, as manganese supplementation of Hfe(-/-) mice led to enhancement of MnSOD activity and suppressed lipid peroxidation. Manganese supplementation also resulted in improved insulin secretion and glucose tolerance associated with increased MnSOD activity and decreased lipid peroxidation in islets. These data suggest a novel mechanism of iron-induced cellular dysfunction, namely altered mitochondrial uptake of other metal ions.
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Affiliation(s)
- Hani A Jouihan
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA
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