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Lotan A, Luza S, Opazo CM, Ayton S, Lane DJR, Mancuso S, Pereira A, Sundram S, Weickert CS, Bousman C, Pantelis C, Everall IP, Bush AI. Perturbed iron biology in the prefrontal cortex of people with schizophrenia. Mol Psychiatry 2023; 28:2058-2070. [PMID: 36750734 PMCID: PMC10575779 DOI: 10.1038/s41380-023-01979-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 01/10/2023] [Accepted: 01/20/2023] [Indexed: 02/09/2023]
Abstract
Despite loss of grey matter volume and emergence of distinct cognitive deficits in young adults diagnosed with schizophrenia, current treatments for schizophrenia do not target disruptions in late maturational reshaping of the prefrontal cortex. Iron, the most abundant transition metal in the brain, is essential to brain development and function, but in excess, it can impair major neurotransmission systems and lead to lipid peroxidation, neuroinflammation and accelerated aging. However, analysis of cortical iron biology in schizophrenia has not been reported in modern literature. Using a combination of inductively coupled plasma-mass spectrometry and western blots, we quantified iron and its major-storage protein, ferritin, in post-mortem prefrontal cortex specimens obtained from three independent, well-characterised brain tissue resources. Compared to matched controls (n = 85), among schizophrenia cases (n = 86) we found elevated tissue iron, unlikely to be confounded by demographic and lifestyle variables, by duration, dose and type of antipsychotic medications used or by copper and zinc levels. We further observed a loss of physiologic age-dependent iron accumulation among people with schizophrenia, in that the iron level among cases was already high in young adulthood. Ferritin, which stores iron in a redox-inactive form, was paradoxically decreased in individuals with the disorder. Such iron-ferritin uncoupling could alter free, chemically reactive, tissue iron in key reasoning and planning areas of the young-adult schizophrenia cortex. Using a prediction model based on iron and ferritin, our data provide a pathophysiologic link between perturbed cortical iron biology and schizophrenia and indicate that achievement of optimal cortical iron homeostasis could offer a new therapeutic target.
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Affiliation(s)
- Amit Lotan
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, 3010, Australia
- Department of Psychiatry and the Biological Psychiatry Laboratory, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Sandra Luza
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, 3010, Australia
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne & Melbourne Health, Carlton, VIC, Australia
| | - Carlos M Opazo
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, 3010, Australia.
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne & Melbourne Health, Carlton, VIC, Australia.
| | - Scott Ayton
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Darius J R Lane
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Serafino Mancuso
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne & Melbourne Health, Carlton, VIC, Australia
| | - Avril Pereira
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, 3010, Australia
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne & Melbourne Health, Carlton, VIC, Australia
| | - Suresh Sundram
- Department of Psychiatry, School of Clinical Sciences, Monash University, Melbourne, VIC, Australia
- Mental Health Program, Monash Health, Melbourne, VIC, Australia
| | - Cynthia Shannon Weickert
- Schizophrenia Research Laboratory, Neuroscience Research Australia, Randwick, NSW, Australia
- School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Chad Bousman
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne & Melbourne Health, Carlton, VIC, Australia
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Departments of Medical Genetics, Psychiatry, Physiology & Pharmacology, University of Calgary, Calgary, AB, Canada
- The Cooperative Research Centre (CRC) for Mental Health, Melbourne, VIC, Australia
| | - Christos Pantelis
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne & Melbourne Health, Carlton, VIC, Australia
- North Western Mental Health, Melbourne, VIC, Australia
| | - Ian P Everall
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne & Melbourne Health, Carlton, VIC, Australia
- North Western Mental Health, Melbourne, VIC, Australia
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Ashley I Bush
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, 3010, Australia.
- The Cooperative Research Centre (CRC) for Mental Health, Melbourne, VIC, Australia.
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Hyeun JA, Kim JY, Kim CH, Kim JH, Lee EY, Seo JH. Iron is Responsible for Production of Reactive Oxygen Species Regulating Vasopressin Expression in the Mouse Paraventricular Nucleus. Neurochem Res 2019; 44:1201-1213. [PMID: 30830595 DOI: 10.1007/s11064-019-02764-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 02/12/2019] [Accepted: 02/25/2019] [Indexed: 11/24/2022]
Abstract
Reactive oxygen species (ROS) act as signaling molecules for maintaining homeostasis, particularly in the regulation of body-fluid balance in the paraventricular nucleus (PVN) of the hypothalamus. However, there has been little discussion regarding the source of ROS generation in this hypothalamic region. Because iron is the most abundant metal in the brain, we hypothesized that iron may act as a source of ROS, which regulate vasopressin (VP) expression. In the present study, we compared the amount of iron in the PVN to that in other forebrain regions of normal ICR mice, and examined the relationship among iron, ROS, and VP in the PVN of the iron-overloaded with iron dextran and iron-chelated mice with deferoxamine. The amount of iron in the PVN was significantly higher than in any of the forebrain regions we examined. The amount of iron in the PVN was significantly increased in iron-overloaded mice, although not in iron-chelated mice. These results suggest that the PVN exhibits high iron affinity. Both ROS production and VP expression in the PVN of iron-overloaded mice were significantly increased relative to levels observed in control mice. VP concentration in blood of iron-overloaded mice was also significantly higher than that of control mice. Interestingly, iron overload did not alter the expression of nitric oxide synthase, another modulator of VP expression. Taken together, our results suggest that high levels of iron in the PVN induce the production of ROS, which regulate VP expression, independent of nitric oxide signaling.
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Affiliation(s)
- Jong-A Hyeun
- Department of Anatomy, Chungbuk National University College of Medicine, Chungdae-ro 1, Seowon-gu, Cheongju, Chungbuk, 28644, Republic of Korea.,Department of Biochemistry, Chungbuk National University College of Medicine, Cheongju, Chungbuk, 28644, Republic of Korea
| | - Ji Young Kim
- Department of Anatomy, Chungbuk National University College of Medicine, Chungdae-ro 1, Seowon-gu, Cheongju, Chungbuk, 28644, Republic of Korea
| | - Chan Hyung Kim
- Department of Pharmacology, Chungbuk National University College of Medicine, Cheongju, Chungbuk, 28644, Republic of Korea
| | - Jin-Hee Kim
- Department of Biomedical Laboratory Science, College of Health Science, Cheongju University, Cheongju, Chungbuk, 28503, Republic of Korea
| | - Eun Young Lee
- Department of Anatomy, Chungbuk National University College of Medicine, Chungdae-ro 1, Seowon-gu, Cheongju, Chungbuk, 28644, Republic of Korea
| | - Je Hoon Seo
- Department of Anatomy, Chungbuk National University College of Medicine, Chungdae-ro 1, Seowon-gu, Cheongju, Chungbuk, 28644, Republic of Korea.
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Masaldan S, Bush AI, Devos D, Rolland AS, Moreau C. Striking while the iron is hot: Iron metabolism and ferroptosis in neurodegeneration. Free Radic Biol Med 2019; 133:221-233. [PMID: 30266679 DOI: 10.1016/j.freeradbiomed.2018.09.033] [Citation(s) in RCA: 291] [Impact Index Per Article: 58.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/19/2018] [Accepted: 09/20/2018] [Indexed: 02/07/2023]
Abstract
Perturbations in iron homeostasis and iron accumulation feature in several neurodegenerative disorders including Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic lateral sclerosis (ALS). Proteins such as α-synuclein, tau and amyloid precursor protein that are pathologically associated with neurodegeneration are involved in molecular crosstalk with iron homeostatic proteins. Quantitative susceptibility mapping, an MRI based non-invasive technique, offers proximal evaluations of iron load in regions of the brain and powerfully predicts cognitive decline. Further, small molecules that target elevated iron have shown promise against PD and AD in preclinical studies and clinical trials. Despite these strong links between altered iron homeostasis and neurodegeneration the molecular biology to describe the association between enhanced iron levels and neuron death, synaptic impairment and cognitive decline is ill defined. In this review we discuss the current understanding of brain iron homeostasis and how it may be perturbed under pathological conditions. Further, we explore the ramifications of a novel cell death pathway called ferroptosis that has provided a fresh impetus to the "metal hypothesis" of neurodegeneration. While lipid peroxidation plays a central role in the execution of this cell death modality the removal of iron through chelation or genetic modifications appears to extinguish the ferroptotic pathway. Conversely, tissues that harbour elevated iron may be predisposed to ferroptotic damage. These emerging findings are of relevance to neurodegeneration where ferroptotic signalling may offer new targets to mitigate cell death and dysfunction.
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Affiliation(s)
- Shashank Masaldan
- Melbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Ashley I Bush
- Melbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia.
| | - David Devos
- Department of Neurology, ALS Center, Lille University, INSERM UMRS_1171, University Hospital Center, LICEND COEN Center, Lille, France; Department of Medical Pharmacology, Lille University, INSERM UMRS_1171, University Hospital Center, LICEND COEN Center, Lille, France
| | - Anne Sophie Rolland
- Department of Medical Pharmacology, Lille University, INSERM UMRS_1171, University Hospital Center, LICEND COEN Center, Lille, France
| | - Caroline Moreau
- Department of Neurology, ALS Center, Lille University, INSERM UMRS_1171, University Hospital Center, LICEND COEN Center, Lille, France; Department of Medical Pharmacology, Lille University, INSERM UMRS_1171, University Hospital Center, LICEND COEN Center, Lille, France
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Connor DE, Chaitanya GV, Chittiboina P, McCarthy P, Scott LK, Schrott L, Minagar A, Nanda A, Alexander JS. Variations in the cerebrospinal fluid proteome following traumatic brain injury and subarachnoid hemorrhage. PATHOPHYSIOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY FOR PATHOPHYSIOLOGY 2017; 24:169-183. [PMID: 28549769 PMCID: PMC7303909 DOI: 10.1016/j.pathophys.2017.04.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 04/06/2017] [Accepted: 04/28/2017] [Indexed: 12/19/2022]
Abstract
BACKGROUND Proteomic analysis of cerebrospinal fluid (CSF) has shown great promise in identifying potential markers of injury in neurodegenerative diseases [1-13]. Here we compared CSF proteomes in healthy individuals, with patients diagnosed with traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) in order to characterize molecular biomarkers which might identify these different clinical states and describe different molecular mechanisms active in each disease state. METHODS Patients presenting to the Neurosurgery service at the Louisiana State University Hospital-Shreveport with an admitting diagnosis of TBI or SAH were prospectively enrolled. Patients undergoing CSF sampling for diagnostic procedures were also enrolled as controls. CSF aliquots were subjected to 2-dimensional gel electrophoresis (2D GE) and spot percentage densities analyzed. Increased or decreased spot expression (compared to controls) was defined in terms of in spot percentages, with spots showing consistent expression change across TBI or SAH specimens being followed up by Matrix-Assisted Laser Desorption/Ionization mass spectrometry (MALDI-MS). Polypeptide masses generated were matched to known standards using a search of the NCBI and/or GenPept databases for protein matches. Eight hundred fifteen separately identifiable polypeptide migration spots were identified on 2D GE gels. MALDI-MS successfully identified 13 of 22 selected 2D GE spots as recognizable polypeptides. RESULTS Statistically significant changes were noted in the expression of fibrinogen, carbonic anhydrase-I (CA-I), peroxiredoxin-2 (Prx-2), both α and β chains of hemoglobin, serotransferrin (Tf) and N-terminal haptoglobin (Hp) in TBI and SAH specimens, as compared to controls. The greatest mean fold change among all specimens was seen in CA-I and Hp at 30.7 and -25.7, respectively. TBI specimens trended toward greater mean increases in CA-I and Prx-2 and greater mean decreases in Hp and Tf. CONCLUSIONS Consistent CSF elevation of CA-I and Prx-2 with concurrent depletion of Hp and Tf may represent a useful combination of biomarkers for the prediction of severity and prognosis following brain injury.
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Affiliation(s)
- David E Connor
- Baptist Health Neurosurgery Arkansas, Little Rock, AR, United States.
| | - Ganta V Chaitanya
- Cardiovascular Research Center, University of Virginia, Charlottesville, VA, United States.
| | - Prashant Chittiboina
- Surgical Neurology Branch, National Institute of Neurological Diseases and Stroke, Bethesda, MD, United States.
| | - Paul McCarthy
- Department of Medicine, Sect. of Nephrology, University of Maryland, Baltimore, MD, United States.
| | - L Keith Scott
- Department of Critical Care Medicine, Louisiana State University Health Sciences Center-Shreveport, LA, United States.
| | - Lisa Schrott
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport, LA, United States.
| | - Alireza Minagar
- Department of Neurology, Louisiana State University Health Sciences Center-Shreveport, LA, United States.
| | - Anil Nanda
- Department of Neurosurgery, Louisiana State University Health Sciences Center-Shreveport, LA, United States.
| | - J Steven Alexander
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, LA, United States.
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The Complex Role of Apolipoprotein E in Alzheimer's Disease: an Overview and Update. J Mol Neurosci 2016; 60:325-335. [PMID: 27647307 DOI: 10.1007/s12031-016-0839-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 09/05/2016] [Indexed: 10/21/2022]
Abstract
Apolipoprotein E (ApoE) plays a crucial role in the homeostatic control of lipids in both the periphery and the central nervous system (CNS). In humans, ApoE exists in three different isoforms: ε2, ε3 and ε4. ApoE ε3 is the most common isoform, while the ε4 isoform confers the greatest genetic risk for Alzheimer's disease (AD). However, the mechanisms underlying how ApoE contributes to the pathogenesis of AD are still debated. ApoE has been shown to impact amyloid β (Aβ) deposition and clearance in the brain. ApoE also has Aβ-independent pathways in AD, which has led to the discovery of new roles of ApoE ranging from mitochondria dysfunction to, most recently, iron metabolism. Here, we review the role of ApoE in health and in AD, with the view of identifying therapeutic approaches that could prevent the risk associated with the ε4 isoform.
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Li K, Reichmann H. Role of iron in neurodegenerative diseases. J Neural Transm (Vienna) 2016; 123:389-99. [PMID: 26794939 DOI: 10.1007/s00702-016-1508-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 01/12/2016] [Indexed: 01/01/2023]
Abstract
Currently, we still lack effective measures to modify disease progression in neurodegenerative diseases. Iron-containing proteins play an essential role in many fundamental biological processes in the central nervous system. In addition, iron is a redox-active ion and can induce oxidative stress in the cell. Although the causes and pathology hallmarks of different neurodegenerative diseases vary, iron dyshomeostasis, oxidative stress and mitochondrial injury constitute a common pathway to cell death in several neurodegenerative diseases. MRI is capable of depicting iron content in the brain, and serves as a potential biomarker for early and differential diagnosis, tracking disease progression and evaluating the effectiveness of neuroprotective therapy. Iron chelators have shown their efficacy against neurodegeneration in a series of animal models, and been applied in several clinical trials. In this review, we summarize recent developments on iron dyshomeostasis in Parkinson's disease, Alzheimer's disease, Friedreich ataxia, and Huntington's disease.
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Affiliation(s)
- Kai Li
- Center of Clinical Neuroscience, University Hospital Carl Gustav Carus, Dresden University of Technology, Fetscherstr. 74, 01307, Dresden, Germany.
| | - Heinz Reichmann
- Department of Neurology, University Hospital Carl Gustav Carus, Dresden University of Technology, Fetscherstr. 74, 01307, Dresden, Germany
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Thomsen MS, Andersen MV, Christoffersen PR, Jensen MD, Lichota J, Moos T. Neurodegeneration with inflammation is accompanied by accumulation of iron and ferritin in microglia and neurons. Neurobiol Dis 2015; 81:108-18. [DOI: 10.1016/j.nbd.2015.03.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Revised: 03/03/2015] [Accepted: 03/12/2015] [Indexed: 12/22/2022] Open
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Ferritin levels in the cerebrospinal fluid predict Alzheimer's disease outcomes and are regulated by APOE. Nat Commun 2015; 6:6760. [PMID: 25988319 PMCID: PMC4479012 DOI: 10.1038/ncomms7760] [Citation(s) in RCA: 218] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 02/25/2015] [Indexed: 12/22/2022] Open
Abstract
Brain iron elevation is implicated in Alzheimer's disease (AD) pathogenesis, but the impact of iron on disease outcomes has not been previously explored in a longitudinal study. Ferritin is the major iron storage protein of the body; by using cerebrospinal fluid (CSF) levels of ferritin as an index, we explored whether brain iron status impacts longitudinal outcomes in the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. We show that baseline CSF ferritin levels were negatively associated with cognitive performance over 7 years in 91 cognitively normal, 144 mild cognitive impairment (MCI) and 67 AD subjects, and predicted MCI conversion to AD. Ferritin was strongly associated with CSF apolipoprotein E levels and was elevated by the Alzheimer's risk allele, APOE-ɛ4. These findings reveal that elevated brain iron adversely impacts on AD progression, and introduce brain iron elevation as a possible mechanism for APOE-ɛ4 being the major genetic risk factor for AD.
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Kim HJ, Jung J, Park JH, Kim JH, Ko KN, Kim CW. Extremely low-frequency electromagnetic fields induce neural differentiation in bone marrow derived mesenchymal stem cells. Exp Biol Med (Maywood) 2013; 238:923-31. [DOI: 10.1177/1535370213497173] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Extremely low-frequency electromagnetic fields (ELF-EMF) affect numerous biological functions such as gene expression, cell fate determination and even cell differentiation. To investigate the correlation between ELF-EMF exposure and differentiation, bone marrow derived mesenchymal stem cells (BM-MSCs) were subjected to a 50-Hz electromagnetic field during in vitro expansion. The influence of ELF-EMF on BM-MSCs was analysed by a range of different analytical methods to understand its role in the enhancement of neural differentiation. ELF-EMF exposure significantly decreased the rate of proliferation, which in turn caused an increase in neuronal differentiation. The ELF-EMF-treated cells showed increased levels of neuronal differentiation marker (MAP2), while early neuronal marker (Nestin) was down-regulated. In addition, eight differentially expressed proteins were detected in two-dimensional electrophoresis maps, and were identified using ESI-Q-TOF LC/MS/MS. Among them, ferritin light chain, thioredoxin-dependent peroxide reductase, and tubulin β-6 chain were up-regulated in the ELF-EMF-stimulated group. Ferritin and thioredoxin-dependent peroxide reductase are involved in a wide variety of functions, including Ca2+ regulation, which is a critical component of neurodegeneration. We also observed that the intracellular Ca2+ content was significantly elevated after ELF-EMF exposure, which strengthens the modulatory role of ferritin and thioredoxin-dependent peroxide reductase, during differentiation. Notably, western blot analysis indicated significantly increased expression of the ferritin light chain in the ELF-EMF-stimulated group (0.60 vs. 1.08; P < 0.01). These proteins may help understand the effect of ELF-EMF stimulation on BM-MSCs during neural differentiation and its potential use as a clinically therapeutic option for treating neurodegenerative diseases.
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Affiliation(s)
- Hyun-Jung Kim
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
| | - Jessica Jung
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
| | - Jee-Hye Park
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
| | - Jin-Hee Kim
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
| | - Kyung-Nam Ko
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
| | - Chan-Wha Kim
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
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Skjørringe T, Møller LB, Moos T. Impairment of interrelated iron- and copper homeostatic mechanisms in brain contributes to the pathogenesis of neurodegenerative disorders. Front Pharmacol 2012; 3:169. [PMID: 23055972 PMCID: PMC3456798 DOI: 10.3389/fphar.2012.00169] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 08/29/2012] [Indexed: 01/01/2023] Open
Abstract
Iron and copper are important co-factors for a number of enzymes in the brain, including enzymes involved in neurotransmitter synthesis and myelin formation. Both shortage and an excess of iron or copper will affect the brain. The transport of iron and copper into the brain from the circulation is strictly regulated, and concordantly protective barriers, i.e., the blood-brain barrier (BBB) and the blood-cerebrospinal fluid (CSF) barrier (BCB) have evolved to separate the brain environment from the circulation. The uptake mechanisms of the two metals interact. Both iron deficiency and overload lead to altered copper homeostasis in the brain. Similarly, changes in dietary copper affect the brain iron homeostasis. Moreover, the uptake routes of iron and copper overlap each other which affect the interplay between the concentrations of the two metals in the brain. The divalent metal transporter-1 (DMT1) is involved in the uptake of both iron and copper. Furthermore, copper is an essential co-factor in numerous proteins that are vital for iron homeostasis and affects the binding of iron-response proteins to iron-response elements in the mRNA of the transferrin receptor, DMT1, and ferroportin, all highly involved in iron transport. Iron and copper are mainly taken up at the BBB, but the BCB also plays a vital role in the homeostasis of the two metals, in terms of sequestering, uptake, and efflux of iron and copper from the brain. Inside the brain, iron and copper are taken up by neurons and glia cells that express various transporters.
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Affiliation(s)
- Tina Skjørringe
- Section of Neurobiology, Biomedicine Group, Institute of Medicine and Health Technology, Aalborg University Aalborg, Denmark ; Center for Applied Human Molecular Genetics, Department of Kennedy Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
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Heterogenous distribution of ferroportin-containing neurons in mouse brain. Biometals 2011; 24:357-75. [PMID: 21213119 DOI: 10.1007/s10534-010-9405-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Accepted: 12/22/2010] [Indexed: 12/27/2022]
Abstract
Iron is crucial for a variety of cellular functions in neuronal cells. Neuronal iron uptake is reflected in a robust and consistent expression of transferrin receptors and divalent metal transporter 1 (DMT 1). Conversely, the mechanisms by which neurons neutralize and possibly excrete iron are less clear. Studies indicate that neurons express ferroportin which could reflect a mechanism for iron export. We mapped the distribution of ferroportin in the adult mouse brain using an antibody prepared from a peptide representing amino acid sequences 223-303 of mouse ferroportin. The antibody specifically detected ferroportin in brain homogenates, whereas homogenates of cultured endothelial cells were devoid of immunoreactivity. In brain sections, ferroportin was confined to neuronal cell bodies and peripheral processes of cerebral cortex, hippocampus, thalamus, brain stem, and cerebellum. In brain stem ferroportin-labeling was particularly high in neurons of cranial nerve nuclei and reticular formation. Ferroportin was hardly detectable in striatum, pallidum, or hypothalamus. Among non-neuronal cells, ferroportin was detected in oligodendrocytes and choroid plexus epithelial cells. A comparison with previous studies on the distribution of transferrin receptors in neurons shows that many neuronal pools coincide with those expressing ferroportin. The data therefore indicate that neuronal iron homeostasis consists of a delicate balance between transferrin receptor-mediated uptake of iron-transferrin and ferroportin-related iron excretion. The findings also suggest a particular high turnover of iron in neuronal regions, such as habenula, hippocampus, reticular formation and cerebellum, as several neurons in these regions exhibit a prominent co-expression of transferrin receptors and ferroportin.
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12
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Moos T, Bernth N, Courtois Y, Morgan EH. Developmental iron uptake and axonal transport in the retina of the rat. Mol Cell Neurosci 2011; 46:607-13. [PMID: 21211566 DOI: 10.1016/j.mcn.2010.12.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 12/24/2010] [Accepted: 12/27/2010] [Indexed: 10/18/2022] Open
Abstract
We examined differently aged postnatal (P) rats for the distribution and uptake of iron in the eye with the main emphasis on iron uptake in the retina. The concentration of iron in the eye was 48 μg/g in rats aged one postnatal day (P1). Then concentration fell to approximately 12 μg/g at P30 and rose to 35 μg/g at P70. Perls' stain which labels both ferrous and ferric iron was found to exhibit a weak labeling in the retina at P1 contrasted by a robust labeling of macrophages found in the choroid of the retina. In older aged rats, the labeling of cells of the retina was much more intense and confined to cells widespread in the layers of the retina. In both P16 and adult rats injected intravenously with [(59)Fe-(125)I]transferrin, the uptake of (59)Fe, estimated as the volume of distribution, was significantly higher than that of [(125)I]transferrin, and uptake of both compounds was higher than that of simultaneously injected [(131)I]albumin. In the P16 rat, the uptake of (59)Fe expressed as the volume of distribution, V(D), rose linearly reaching approximately 2500 nl at 60 min. In the adult rat, the uptake of (59)Fe was of the same magnitude. Comparing P1 and P16 rats, the uptake of (59)Fe, [(125)I]transferrin and [(131)I]albumin was higher at P1 in both eyeball and retina. Emulsion autoradiography of retinas from P16 and adult rats injected with [(55)Fe]transferrin into the vitreous body showed uptake mainly in photoreceptor cells and retinal ganglion cells. Adult rats injected into the vitreous body with [(59)Fe]transferrin showed anterograde axonal transport from the retina into the optic nerve, optic tract, and superior colliculus. Immunoprecipitates of homogenates of the optic nerve revealed that (59)Fe was precipitable with an antibody raised against ferritin, indicative of detachment of iron from transferrin within the axons of the retinal ganglion cells. The data demonstrate an age-dependent but continuous iron uptake by the retina, and are indicative of anterograde axonal transport of transferrin by retinal ganglion cells.
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Affiliation(s)
- T Moos
- Section of Neurobiology, Biomedicine, Aalborg University, Denmark.
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Apotransferrin protects cortical neurons from hemoglobin toxicity. Neuropharmacology 2010; 60:423-31. [PMID: 21034753 DOI: 10.1016/j.neuropharm.2010.10.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Revised: 10/18/2010] [Accepted: 10/19/2010] [Indexed: 11/23/2022]
Abstract
The protective effect of iron chelators in experimental models of intracerebral hemorrhage suggests that nonheme iron may contribute to injury to perihematomal cells. Therapy with high affinity iron chelators is limited by their toxicity, which may be due in part to sequestration of metals in an inaccessible complex. Transferrin is unique in chelating iron with very high affinity while delivering it to cells as needed via receptor-mediated endocytosis. However, its efficacy against iron-mediated neuronal injury has never been described, and was therefore evaluated in this study using an established cell culture model of hemoglobin neurotoxicity. At concentrations similar to that of CSF transferrin (50-100 micrograms/ml), both iron-saturated holotransferrin and apotransferrin were nontoxic per se. Overnight exposure to 3 μM purified human hemoglobin in serum-free culture medium resulted in death, as measured by lactate dehydrogenase release assay, of about three-quarters of neurons. Significant increases in culture iron, malondialdehyde, protein carbonyls, ferritin and heme oxygenase-1 were also observed. Holotransferrin had no effect on these parameters, but all were attenuated by 50-100 micrograms/ml apotransferrin. The effect of apotransferrin was very similar to that of deferoxamine at a concentration that provided equivalent iron binding capacity, and was not antagonized by concomitant treatment with holotransferrin. Transferrin receptor-1 expression was localized to neurons and was not altered by hemoglobin or transferrin treatment. These results suggest that apotransferrin may mitigate the neurotoxicity of hemoglobin after intracerebral hemorrhage. Increasing its concentration in perihematomal tissue may be beneficial.
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14
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Rivera-Mancía S, Pérez-Neri I, Ríos C, Tristán-López L, Rivera-Espinosa L, Montes S. The transition metals copper and iron in neurodegenerative diseases. Chem Biol Interact 2010; 186:184-99. [DOI: 10.1016/j.cbi.2010.04.010] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 01/22/2010] [Accepted: 04/08/2010] [Indexed: 12/14/2022]
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15
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George JL, Mok S, Moses D, Wilkins S, Bush AI, Cherny RA, Finkelstein DI. Targeting the progression of Parkinson's disease. Curr Neuropharmacol 2010; 7:9-36. [PMID: 19721815 PMCID: PMC2724666 DOI: 10.2174/157015909787602814] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 08/15/2008] [Accepted: 09/09/2008] [Indexed: 02/07/2023] Open
Abstract
By the time a patient first presents with symptoms of Parkinson's disease at the clinic, a significant proportion (50-70%) of the cells in the substantia nigra (SN) has already been destroyed. This degeneration progresses until, within a few years, most of the cells have died. Except for rare cases of familial PD, the initial trigger for cell loss is unknown. However, we do have some clues as to why the damage, once initiated, progresses unabated. It would represent a major advance in therapy to arrest cell loss at the stage when the patient first presents at the clinic. Current therapies for Parkinson's disease focus on relieving the motor symptoms of the disease, these unfortunately lose their effectiveness as the neurodegeneration and symptoms progress. Many experimental approaches are currently being investigated attempting to alter the progression of the disease. These range from replacement of the lost neurons to neuroprotective therapies; each of these will be briefly discussed in this review. The main thrust of this review is to explore the interactions between dopamine, alpha synuclein and redox-active metals. There is abundant evidence suggesting that destruction of SN cells occurs as a result of a self-propagating series of reactions involving dopamine, alpha synuclein and redox-active metals. A potent reducing agent, the neurotransmitter dopamine has a central role in this scheme, acting through redox metallo-chemistry to catalyze the formation of toxic oligomers of alpha-synuclein and neurotoxic metabolites including 6-hydroxydopamine. It has been hypothesized that these feed the cycle of neurodegeneration by generating further oxidative stress. The goal of dissecting and understanding the observed pathological changes is to identify therapeutic targets to mitigate the progression of this debilitating disease.
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Affiliation(s)
- J L George
- The Mental Health Research Institute of Victoria , 155 Oak Street, Parkville, Victoria 3052, Australia
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16
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Youdim MBH. Brain iron deficiency and excess; cognitive impairment and neurodegeneration with involvement of striatum and hippocampus. Neurotox Res 2009; 14:45-56. [PMID: 18790724 DOI: 10.1007/bf03033574] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
While iron deficiency is not perceived as a life threatening disorder, it is the most prevalent nutritional abnormality in the world, and a better understanding of modes and sites of action, can help devise better treatment programs for those who suffer from it. Nowhere is this more important than in infants and children that make up the bulk of iron deficiency in society. Although the effects of iron deficiency have been extensively studied in systemic organs, until very recently little attention was paid to its effects on brain function. The studies of Oski at Johns Hopkin Medical School in 1974, demonstrating the impairment of learning in young school children with iron deficiency, prompted us to study its relevance to brain biochemistry and function in an animal model of iron deficiency. Indeed, rats made iron deficient have lowered brain iron and impaired behaviours including learning. This can become irreversible especially in newborns, even after long-term iron supplementation. We have shown that in this condition it is the brain striatal dopaminergic-opiate system which becomes defective, resulting in alterations in circadian behaviours, cognitive impairment and neurochemical changes closely associated with them. More recently we have extended these studies and have established that cognitive impairment may be closely associated with neuroanatomical damage and zinc metabolism in the hippocampus due to iron deficiency, and which may result from abnormal cholinergic function. The hippocampus is the focus of many studies today, since this brain structure has high zinc concentration and is highly involved in many forms of cognitive deficits as a consequence of cholinergic deficiency and has achieved prominence because of dementia in ageing and Alzheimer's disease. Thus, it is now apparent that cognitive impairment may not be attributed to a single neurotransmitter, but rather, alterations and interactions of several systems in different brain regions. In animal models of iron deficiency it is apparent that dopaminergic interaction with the opiate system and cholinergic neurotransmission may be defective.
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Affiliation(s)
- M B H Youdim
- Eve Topf and USA National Parkinson Foundation, Centers of Excellence for Neurodegenerative Diseases Research and Department of Pharmacology, Rappaport Family Research Institute, Technion-Faculty of Medicine, Haifa, Israel.
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17
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Regan RF, Chen M, Li Z, Zhang X, Benvenisti-Zarom L, Chen-Roetling J. Neurons lacking iron regulatory protein-2 are highly resistant to the toxicity of hemoglobin. Neurobiol Dis 2008; 31:242-9. [PMID: 18571425 DOI: 10.1016/j.nbd.2008.04.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 04/07/2008] [Accepted: 04/25/2008] [Indexed: 10/22/2022] Open
Abstract
The effect of iron regulatory protein-2 (IRP2) on ferritin expression and neuronal vulnerability to hemoglobin was assessed in primary cortical cell cultures prepared from wild-type and IRP2 knockout mice. Baseline levels of H and L-ferritin subunits were significantly increased in IRP2 knockout neurons and astrocytes. Hemoglobin was toxic to wild-type neurons in mixed neuron-astrocyte cultures, with an LC(50) near 3 microM for a 24 h exposure. Neuronal death was reduced by 85-95% in knockout cultures, and also in cultures containing knockout neurons plated on wild-type astrocytes. Protein carbonylation, reactive oxygen species formation, and heme oxygenase-1 expression after hemoglobin treatment were also attenuated by IRP2 gene deletion. These results suggest that IRP2 binding activity increases the vulnerability of neurons to hemoglobin, possibly by reducing ferritin expression. Therapeutic strategies that target this regulatory mechanism may be beneficial after hemorrhagic CNS injuries.
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Affiliation(s)
- Raymond F Regan
- Department of Emergency Medicine, Thomas Jefferson University, 1020 Sansom Street, Thompson Building Room 239, Philadelphia, PA 19107, USA.
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18
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Abstract
Iron, an essential element for all cells of the body, including those of the brain, is transported bound to transferrin in the blood and the general extracellular fluid of the body. The demonstration of transferrin receptors on brain capillary endothelial cells (BCECs) more than 20 years ago provided the evidence for the now accepted view that the first step in blood to brain transport of iron is receptor-mediated endocytosis of transferrin. Subsequent steps are less clear. However, recent investigations which form the basis of this review have shed some light on them and also indicate possible fruitful avenues for future research. They provide new evidence on how iron is released from transferrin on the abluminal surface of BCECs, including the role of astrocytes in this process, how iron is transported in brain extracellular fluid, and how iron is taken up by neurons and glial cells. We propose that the divalent metal transporter 1 is not involved in iron transport through the BCECs. Instead, iron is probably released from transferrin on the abluminal surface of these cells by the action of citrate and ATP that are released by astrocytes, which form a very close relationship with BCECs. Complexes of iron with citrate and ATP can then circulate in brain extracellular fluid and may be taken up in these low-molecular weight forms by all types of brain cells or be bound by transferrin and taken up by cells which express transferrin receptors. Some iron most likely also circulates bound to transferrin, as neurons contain both transferrin receptors and divalent metal transporter 1 and can take up transferrin-bound iron. The most likely source for transferrin in the brain interstitium derives from diffusion from the ventricles. Neurons express the iron exporting carrier, ferroportin, which probably allows them to excrete unneeded iron. Astrocytes lack transferrin receptors. Their source of iron is probably that released from transferrin on the abluminal surface of BCECs. They probably to export iron by a mechanism involving a membrane-bound form of the ferroxidase, ceruloplasmin. Oligodendrocytes also lack transferrin receptors. They probably take up non-transferrin bound iron that gets incorporated in newly synthesized transferrin, which may play an important role for intracellular iron transport.
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Affiliation(s)
- Torben Moos
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
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19
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Simmons DA, Casale M, Alcon B, Pham N, Narayan N, Lynch G. Ferritin accumulation in dystrophic microglia is an early event in the development of Huntington's disease. Glia 2007; 55:1074-84. [PMID: 17551926 DOI: 10.1002/glia.20526] [Citation(s) in RCA: 197] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Huntington's Disease (HD) is characterized primarily by neuropathological changes in the striatum, including loss of medium-spiny neurons, nuclear inclusions of the huntingtin protein, gliosis, and abnormally high iron levels. Information about how these conditions interact, or about the temporal order in which they appear, is lacking. This study investigated if, and when, iron-related changes occur in the R6/2 transgenic mouse model of HD and compared the results with those from HD patients. Relative to wild-type mice, R6/2 mice had increased immunostaining for ferritin, an iron storage protein, in the striatum beginning at 2-4 weeks postnatal and in cortex and hippocampus starting at 5-7 weeks. The ferritin staining was found primarily in microglia, and became more pronounced as the mice matured. Ferritin-labeled microglia in R6/2 mice appeared dystrophic in that they had thick, twisted processes with cytoplasmic breaks; some of these cells also contained the mutant huntingtin protein. Brains from HD patients (Vonsattel grades 0-4) also had increased numbers of ferritin-containing microglia, some of which were dystrophic. The cells were positive for Perl's stain, indicating that they contained abnormally high levels of iron. These results provide the first evidence that perturbations to iron metabolism in HD are predominately associated with microglia and occur early enough to be important contributors to HD progression.
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Affiliation(s)
- Danielle A Simmons
- Department of Psychiatry and Human Behavior, University of California, Irvine, California 92697-4292, USA.
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20
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Moos T, Rosengren Nielsen T. Ferroportin in the postnatal rat brain: implications for axonal transport and neuronal export of iron. Semin Pediatr Neurol 2006; 13:149-57. [PMID: 17101453 DOI: 10.1016/j.spen.2006.08.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study mapped the distribution of ferroportin in the developing rat brain using Wistar rats aged postnatal (P) days P7, P21, and P70 (adult). Ferroportin immunoreactivity was observed in neurons throughout the CNS regardless of the age of the animals studied. The neuronal labeling was detected in both perikarya, and axons and dendrites. The labeling intensity within the neurons varied among the different ages of the rats with an overall higher ferroportin immunoreactivity seen at P21, particularly in axons and white matter tracts. The neuronal labeling was high in the neocortex, striatum, hippocampus, brain stem nuclei, deep cerebellar nuclei, catecholaminergic neurons, and reticular nuclei, and particularly high in neurons of the mesencephalic trigeminal nucleus and medial habenular nucleus. In axonal tracts, ferroportin immunoreactivity was high in fibers of the internal capsule, fimbria, mamillothalamic tract and the habenulo-interpedunculo pathway. Slight ferroportin immunoreactivity was observed in oligodendrocytes and differentiating macrophages that invade the postnatal brain. The finding of a pronounced content of ferroportin in axons of the developing brain are in keeping with the idea of elevated axonal transport and export of iron possibly because of higher metabolic needs.
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Affiliation(s)
- Torben Moos
- Department of Medical Anatomy, The Panum Institute, The University of Copenhagen, Copenhagen, Denmark.
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21
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Salazar J, Mena N, Núñez MT. Iron dyshomeostasis in Parkinson's disease. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2006:205-13. [PMID: 17447431 DOI: 10.1007/978-3-211-33328-0_22] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Owing to its ability to undergo one-electron reactions, iron transforms the mild oxidant hydrogen peroxide into hydroxyl radical, one of the most reactive species in nature. Deleterious effects of iron accumulation are dramatically evidenced in several neurodegenerative diseases. The work of Youdim and collaborators has been fundamental in describing the accumulation of iron confined to the substantia nigra (SN) in Parkinson's disease (PD) and to clarify iron toxicity pathways and oxidative damage in dopaminergic neurons. Nevertheless, how the mechanisms involved in normal neuronal iron homeostasis are surpassed, remain largely undetermined. How nigral neurons survive or succumb to iron-induced oxidative stress are relevant questions both to know about the etiology of the disease and to design neuroprotective strategies. In this work, we review the components of neural iron homeostasis and we summarize evidence from recent studies aimed to unravel the molecular basis of iron accumulation and dyshomeostasis in PD.
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Affiliation(s)
- J Salazar
- Department of Biology, and Cell Dynamic and Biotechnology Research Center, Faculty of Sciences, University of Chile, Santiago, Chile
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22
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Moos T, Morgan EH. The metabolism of neuronal iron and its pathogenic role in neurological disease: review. Ann N Y Acad Sci 2004; 1012:14-26. [PMID: 15105252 DOI: 10.1196/annals.1306.002] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Neurons need iron, which is reflected in their expression of the transferrin receptor. The concurrent expression of the ferrous iron transporter, divalent metal transporter I (DMT1), in neurons suggests that the internalization of transferrin is followed by detachment of iron within recycling endosomes and transport into the cytosol via DMT1. To enable DMT1-mediated export of iron from the endosome to the cytosol, ferric iron must be reduced to its ferrous form, which could be mediated by a ferric reductase. The presence of nontransferrin-bound iron in brain extracellular fluids suggests that neurons can also take up iron in a transferrin-free form. Neurons are thought to be devoid of ferritin in many brain regions in which there is an association between iron accumulation and cellular damage, for example, neurons of the substantia nigra pars compacta. The general lack of ferritin together with the prevailing expression of the transferrin receptor indicates that iron acquired by activity of transferrin receptors is directed toward immediate use in relevant metabolic processes, is exported, or is incorporated into complexes other than ferritin. Iron has long been considered to play a significant role in exacerbating degradation processes in brain tissue subjected to acute damage and neurodegenerative disorders. In brain ischemia, the damaging role of iron may depend on the inhibition of detoxifying enzymes responsible for catalyzing the oxidation of ferrous iron. Brain ischemia may also lead to an increase in iron supply to neurons as transferrin receptor expression by brain capillary endothelial cells is increased. Pharmacological blockage of the transferrin receptor/DMT1-mediated uptake could be a target to prevent further iron uptake. In chronic neurodegenerative settings, a deleterious role of iron is suggested since cases of Alzheimer's disease, Parkinson's disease, and Huntington's disease have a significantly higher accumulation of iron in affected regions. Dopaminergic neurons are rich in neuromelanin, shown to be more redox-active in Parkinson's disease cases. Iron-containing inflammatory cells may, however, account for the main portion of iron present in neurodegenerative disorders. More knowledge about iron metabolism in normal and diseased neurons is warranted as this may identify pharmaceutical targets to improve neuronal iron management.
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Affiliation(s)
- Torben Moos
- Department of Medical Anatomy, University of Copenhagen, Copenhagen, Denmark.
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23
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Morath DJ, Mayer-Pröschel M. Iron deficiency during embryogenesis and consequences for oligodendrocyte generation in vivo. Dev Neurosci 2003; 24:197-207. [PMID: 12401959 DOI: 10.1159/000065688] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
One of the hallmarks of the pathology of iron deficiency in children is neurological disabilities that are often associated with hypomyelination. It has been hypothesized that this amyelination is mainly due to a disruption of myelin generation during the early postnatal stages when oligodendrocytes mature to generate myelin producing cell. In addition to these suggestions, we have previously provided in vitro data showing that iron affects both the proliferation and differentiation of glial precursor cells leading to a disruption in the generation of oligodendrocytes. We now present evidence demonstrating in vivo that iron deficiency during pregnancy affects the iron levels of various brain tissues in the developing fetus and disrupts not only the proliferation of their glial precursor cells but also disturbs the generation of oligodendrocytes from these precursor cells. In addition, we show that iron deficiency during embryogenesis affects glial lineage cells in a tissue-specific manner. Our studies offer the possibility to begin to comprehend whether any effects that occur during embryogenesis might have an influence on the establishment of the pathological defects that occur as a consequence of iron deficiency.
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Affiliation(s)
- Daniel J Morath
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA
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24
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Moos T, Morgan EH. A morphological study of the developmentally regulated transport of iron into the brain. Dev Neurosci 2003; 24:99-105. [PMID: 12401947 DOI: 10.1159/000065702] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The distribution of transferrin, transferrin receptor, ferritin and ferric iron was studied in the developing rat brain. Transferrin immunoreactivity (IR) was observed diffusely in the brain from E16 until P10 from where it gradually decreased. The subcellular distribution of transferrin-IR in neurons was compatible with receptor-mediated uptake from P21 and onwards. Transferrin receptor-IR was observed prenatally on cells of neuroectodermal origin in the ventricular zone and in brain capillary endothelial cells (BCECs). In postnatal rats, transferrin receptor-IR in BCECs was most pronounced in rats aged P10-P21 but thereafter decreased in intensity. The neuronal transferrin-receptor IR in postnatal brains was not consistently expressed on neurons until from P21 and onwards. Transferrin receptor-IR was not observed in astrocytes, oligodendrocytes or ramified microglial cells at any age. Ferric iron and ferritin were present in BCECs already from E16, declined from P3-P5, and was absent by P10. There results are discussed with emphasis on the age-dependent transport of transferrin into the developing brain. The upregulated expression of transferrin receptors on BCECs in the second and third postnatal week is compatible with a high need for iron at this age. The neuronal transferrin receptor expression by P21 coincides with a drop in transferrin-IR and iron transport into the brain at this age, suggesting that neuronal transferrin receptor mRNA is posttranscriptionally regulated by the lowered iron availability from this developmental stage onwards.
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Affiliation(s)
- Torben Moos
- Department of Medical Anatomy, Panum Institute, University of Copenhagen, Denmark.
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Han J, Day JR, Connor JR, Beard JL. H and L ferritin subunit mRNA expression differs in brains of control and iron-deficient rats. J Nutr 2002; 132:2769-74. [PMID: 12221243 DOI: 10.1093/jn/132.9.2769] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The mRNA expression of ferritin subunits has not been studied thoroughly in the brain regions of iron-deficient rats. Sprague-Dawley rats (n = 26; 21 d old) were randomly assigned to an iron-deficient (3.5 mg Fe/kg diet) or a control diet (35 mg Fe/kg diet) for 6 wk. Ferritin protein and mRNA contents were quantified and the cellular expression of ferritin subunits in brain was determined. H and L ferritin had the same mRNA locations in nearly all brain regions. Both ferritin subunit mRNAs had heterogeneous distributions and there was a regional effect across brain regions. Iron deficiency did not affect the amount of ferritin mRNA in most brain regions, suggesting the post-transcriptional regulation of messengers by iron status. H ferritin protein was predominant in neurons and oligodendrocytes, whereas L ferritin protein and iron predominated in microglia cells and astrocytes as well as in oligodendrocytes and neurons. Ferritin mRNA was detectable only in neurons. Iron deficiency did not induce new types of cells containing either ferritin protein or mRNA. The fact that ferritin protein was found in four types of cells whereas mRNA was found in only one type of cell suggests that the site of ferritin synthesis is different from protein location in the brain. All of these data suggest that regulation of ferritin subunits is cellular and/or regional specific.
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Affiliation(s)
- Jian Han
- Department of Nutrition, The Pennsylvania State University, University Park, PA 16802, USA
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26
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Cairo G, Ronchi R, Buccellato FR, Veber D, Santambrogio P, Scalabrino G. Regulation of the ferritin H subunit by vitamin B12 (cobalamin) in rat spinal cord. J Neurosci Res 2002; 69:117-24. [PMID: 12111823 DOI: 10.1002/jnr.10267] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cobalamin-deficient (Cbl-D) central neuropathy is a pure myelinolytic disease, in which gliosis is also observed. Iron is abundant in the mammalian central nervous system, where it is required for various essential functions including myelinogenesis. It is predominantly located in the white matter and oligodendrocytes, which also actively synthesize the major iron proteins (e.g., ferritin, transferrin). We investigated the expression of the main proteins of iron metabolism in the spinal cord (SC) of totally gastrectomized Cbl-D rats 2 months after surgery (i.e., when the Cbl-D status has become severe). There were no significant changes in iron content, the activity of iron regulatory proteins, or the expression of transferrin or its receptor in the SC. We observed a significant decrease in the levels of both H and L ferritin subunits, with a more marked reduction in the latter. Post-operative cobalamin replacement therapy normalized only the H-ferritin subunits, and only in the SC. Our results therefore suggest that permanent cobalamin deficiency affects iron metabolism in the rat SC preferentially from a functional point of view, because H-ferritin is known to be involved in the uptake and release of iron.
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Affiliation(s)
- Gaetano Cairo
- Institute of General Pathology, Center for Excellence on Neurodegenerative Diseases, University of Milan, Milan, Italy
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Koszyca B, Manavis J, Cornish RJ, Blumbergs PC. Patterns of immunocytochemical staining for ferritin and transferrin in the human spinal cord following traumatic injury. J Clin Neurosci 2002; 9:298-301. [PMID: 12093138 DOI: 10.1054/jocn.2001.0969] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Normally Fe(2+) is strictly controlled within the central nervous system (CNS) because of its potential to react with oxygen and form free radicals.(1,2) Traumatic spinal cord injury (TSCI) leads to cell damage and haemorrhage, both of which may increase the pool of free iron.(3) The aim of this study was to examine the response to TSCI of the iron storage protein ferritin (Ft) and the iron transport protein transferrin (Tf). The study found a significant increase in Ft positive cells compared to controls and a significant correlation between the number of Ft positive cells and the severity of injury. Significantly fewer Tf positive cells were seen in the trauma cases compared to the control and there was no relation with the severity of injury. These observations suggest a disturbance in normal iron metabolism within the spinal cord following injury, with possible implications for free radical mediated secondary damage.
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Affiliation(s)
- B Koszyca
- Department of Pathology, Adelaide University, Adelaide, SA, 5005, Australia
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Abstract
Mammalian cells and organisms coordinate to regulate expression of numerous proteins involved in the uptake, sequestration, and export of iron. When cells in the systemic circulation are depleted of iron, they increase synthesis of the transferrin receptor and decrease synthesis of the iron sequestration protein, ferritin. In iron-depleted animals, expression of duodenal iron transporters markedly increases and intestinal iron uptake increases accordingly. The major proteins of iron metabolism in the systemic circulation are also expressed in the central nervous system. However, the mechanisms by which iron is transported and distributed throughout the central nervous system are not well understood. Iron accumulation in specific regions of the brain is observed in several neurodegenerative diseases. It is likely that misregulation of iron metabolism is important in the pathophysiology of several human neurodegenerative diseases.
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Affiliation(s)
- T A Rouault
- Section on Human Iron Metabolism, Cell Biology and Metabolism Branch, National Institute of Child Health and Human Disease, Bethesda, Maryland 20892, USA
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Chi SI, Wang CK, Chen JJ, Chau LY, Lin TN. Differential regulation of H- and L-ferritin messenger RNA subunits, ferritin protein and iron following focal cerebral ischemia-reperfusion. Neuroscience 2001; 100:475-84. [PMID: 11098110 DOI: 10.1016/s0306-4522(00)00317-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Iron may catalyse the production of reactive oxygen species during post-ischemic reoxygenation and subsequently lead to brain damage. Ferritin, an iron sequestering and storage protein, can also be a source of iron after ischemic insult. However, its role in ischemia-reperfusion has not been carefully investigated. In the present study, we examined the temporal and spatial induction profiles of both H- and L-ferritin messenger RNA and protein in a well-defined focal cerebral ischemia model. Results of northern blot analysis showed a delayed and prolonged induction of both H- and L-ferritin messenger RNA in the ischemic cortex of rats subjected to 60min ischemic insult. A significant induction of both H- and L-ferritin messenger RNA was observed at 12h and remained elevated for up to 336h after the onset of reperfusion. At the peak level, quantitative analysis of the blot indicated a 2.5-fold and a six-fold increase in H- and L-ferritin messenger RNA, respectively, compared with the sham-operated controls. No apparent change in the levels of either messenger RNA was observed in the contralateral side. Results of in situ hybridization studies revealed constitutive expression of both H- and L-ferritin messenger RNA throughout the brain in sham-operated animals, in particular the hippocampus and the piriform cortex. Nevertheless, the signal intensity of H-ferritin messenger RNA was much higher than that of L-ferritin messenger RNA. Seventy-two hours after 60min ischemia, marked expression of H-ferritin messenger RNA was observed in the area surrounding the middle cerebral artery irrigated cortex, the medial part of the caudoputamen and in the subfield of the CA1 hippocampal region of the ipsilateral hemisphere. Similarly, a large induction of L-ferritin messenger RNA was also noted in several areas, including the middle cerebral artery irrigated cortex, the lateral part of the caudoputamen and the stratum pyramidale of the CA1 hippocampal region, which were totally different from areas where H-ferritin messenger RNA was found. At 336h after ischemia, increased expression of H-ferritin messenger RNA was observed in the peri-necrosis and ipsilateral thalamus regions, while L-ferritin messenger RNA was noted exclusively at the edge within the necrosis. Results of immunohistochemical study further revealed that ferritin immunoreactivity was present in the same areas where increased ferritin messenger RNA was found. Sixty-minute ischemia also led to iron deposition in discrete areas. Iron deposition was highly associated with the induction of ferritin, particularly in the macrophage- and microglia-positive areas where cell death or tissue necrosis was noted.In summary, our initial findings indicate that ischemic insult leads to induction of both H- and L-ferritin messenger RNA. In the present study, although the temporal induction profiles were similar, the major expression areas for these two genes were totally different. Ferritin immunoreactivity was observed in the same areas where increased ferritin messenger RNA was found. Ischemia also resulted in iron deposition, which highly associated with the ferritin immunoreactivity. The exact regulatory mechanism and pathological significance for the differential expression of H- and L-ferritin genes following ischemia/reperfusion remain to be clarified.
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Affiliation(s)
- S I Chi
- Division of Neuroscience Research, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
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Mirza B, Hadberg H, Thomsen P, Moos T. The absence of reactive astrocytosis is indicative of a unique inflammatory process in Parkinson's disease. Neuroscience 2000; 95:425-32. [PMID: 10658622 DOI: 10.1016/s0306-4522(99)00455-8] [Citation(s) in RCA: 227] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Virtually any neurological disorder leads to activation of resident microglia and invasion of blood-borne macrophages, which are accompanied by an increase in number and change in phenotype of astrocytes, a phenomenon generally termed reactive astrocytosis. One of the functions attributed to activation of astrocytes is thought to involve restoration of tissue damage. Hitherto, the role of astrocytes in the inflammatory reaction occurring in Parkinson's disease has not received much attention. In the present study, we examined the inflammatory events in autopsies of the substantia nigra and putamen from Parkinson's disease patients using age-matched autopsies from normal patients as controls. In the substantia nigra, activation of microglia was consistently observed in all Parkinson's disease autopsies as verified from immunohistochemical detection of CR3/43 and ferritin. Activation of resident microglia was not observed in the putamen. No differences were observed between controls and Parkinson's disease autopsies from the substantia nigra and putamen, in terms of distribution, cellular density or cellular morphology of astrocytes stained for glial fibrillary acidic protein or metallothioneins I and II, the latter sharing high affinity for metal ions and known to be induced in reactive astrocytes, possibly to exert anti-oxidative effects. Together, these findings indicate that the inflammatory process in Parkinson's disease is characterized by activation of resident microglia without reactive astrocytosis, suggesting that the progressive loss of dopaminergic neurons in Parkinson's disease is an ongoing neurodegenerative process with a minimum of involvement of the surrounding nervous tissue. The absence of reactive astrocytosis in Parkinson's disease contrasts what follows in virtually any other neurological disorder and may indicate that the inflammatory process in Parkinson's disease is a unique phenomenon.
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Affiliation(s)
- B Mirza
- Department of Medical Anatomy, The Panum Institute, University of Copenhagen, Denmark
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31
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Moos T, Oates PS, Morgan EH. Iron-independent neuronal expression of transferrin receptor mRNA in the rat. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 72:231-4. [PMID: 10529482 DOI: 10.1016/s0169-328x(99)00226-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Neuronal transferrin receptor protein expression is highly upregulated widely in CNS following iron deficiency. Using the medial habenular nucleus as a model of neuronal transferrin receptor mRNA expression, the present study examined 17-day-old rats subjected to variations in dietary iron. Changing the iron availability resulted in alterations in plasma and cerebrospinal fluid (CSF) levels of transferrin and iron. The iron-binding capacity of transferrin in CSF was exceeded in normal and iron-overloaded rats. In spite of a lowering of the concentration of brain iron by approximately 22% in iron-deficient rats, neuronal transferrin receptor mRNA was not affected when measured by quantitative densitometry. Brain iron and neuronal transferrin receptor mRNA expression was unaltered in iron overloaded rats. The absence of a rise in transferrin receptor mRNA during iron deficiency suggests that neuronal transferrin receptor mRNA expression is regulated by another mechanism than the post-transcriptional regulation mechanism, which has been attributed to cells of non-neural tissue.
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Affiliation(s)
- T Moos
- Department of Medical Anatomy, Section C, The Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
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