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García-Beltrán O, Mena NP, Aguirre P, Barriga-González G, Galdámez A, Nagles E, Adasme T, Hidalgo C, Núñez MT. Development of an iron-selective antioxidant probe with protective effects on neuronal function. PLoS One 2017; 12:e0189043. [PMID: 29228015 PMCID: PMC5724820 DOI: 10.1371/journal.pone.0189043] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 11/19/2017] [Indexed: 12/19/2022] Open
Abstract
Iron accumulation, oxidative stress and calcium signaling dysregulation are common pathognomonic signs of several neurodegenerative diseases, including Parkinson´s and Alzheimer’s diseases, Friedreich ataxia and Huntington’s disease. Given their therapeutic potential, the identification of multifunctional compounds that suppress these damaging features is highly desirable. Here, we report the synthesis and characterization of N-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)-2-(7-hydroxy-2-oxo-2H-chromen-4-yl)acetamide, named CT51, which exhibited potent free radical neutralizing activity both in vitro and in cells. CT51 bound Fe2+ with high selectivity and Fe3+ with somewhat lower affinity. Cyclic voltammetric analysis revealed irreversible binding of Fe3+ to CT51, an important finding since stopping Fe2+/Fe3+ cycling in cells should prevent hydroxyl radical production resulting from the Fenton-Haber-Weiss cycle. When added to human neuroblastoma cells, CT51 freely permeated the cell membrane and distributed to both mitochondria and cytoplasm. Intracellularly, CT51 bound iron reversibly and protected against lipid peroxidation. Treatment of primary hippocampal neurons with CT51 reduced the sustained calcium release induced by an agonist of ryanodine receptor-calcium channels. These protective properties of CT51 on cellular function highlight its possible therapeutic use in diseases with significant oxidative, iron and calcium dysregulation.
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Affiliation(s)
- Olimpo García-Beltrán
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Natalia P. Mena
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile
| | - Pabla Aguirre
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile
| | - Germán Barriga-González
- Universidad Metropolitana de Ciencias de la Educación, Facultad de Ciencias Básicas, Departamento de Química, Santiago, Chile
| | - Antonio Galdámez
- Department of Chemistry, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Edgar Nagles
- Facultad de Ciencias Naturales y Matemáticas, Universidad de Ibagué, Ibagué, Colombia
| | - Tatiana Adasme
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Integrative Center for Applied Biology and Chemistry (CIBQA), Universidad Bernardo O’Higgins, Santiago, Chile
| | - Cecilia Hidalgo
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Department of Neuroscience, CEMC and ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile
- * E-mail: (CH); (MTN)
| | - Marco T. Núñez
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile
- * E-mail: (CH); (MTN)
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Urrutia PJ, Aguirre P, Tapia V, Carrasco CM, Mena NP, Núñez MT. Cell death induced by mitochondrial complex I inhibition is mediated by Iron Regulatory Protein 1. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2202-2209. [DOI: 10.1016/j.bbadis.2017.05.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 04/18/2017] [Accepted: 05/10/2017] [Indexed: 01/14/2023]
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Bulteau AL, Mena NP, Auchère F, Lee I, Prigent A, Lobsiger CS, Camadro JM, Hirsch EC. Dysfunction of mitochondrial Lon protease and identification of oxidized protein in mouse brain following exposure to MPTP: Implications for Parkinson disease. Free Radic Biol Med 2017; 108:236-246. [PMID: 28365360 DOI: 10.1016/j.freeradbiomed.2017.03.036] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 03/19/2017] [Accepted: 03/22/2017] [Indexed: 10/19/2022]
Abstract
Compelling evidence suggests that mitochondrial dysfunction leading to reactive oxygen species (ROS) production and protein oxidation could represent a critical event in the pathogenesis of Parkinson's disease (PD). Pioneering studies have shown that the mitochondrial matrix contains the Lon protease, which degrades oxidized, dysfunctional, and misfolded protein. Using the PD animal model of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) intoxication in mice, we showed that Lon protease expression increased in the ventral mesencephalon of intoxicated animals, concomitantly with the appearance of oxidized proteins and dopaminergic cell loss. In addition, we report that Lon is inactivated by ROS. Moreover, proteomic experiments provide evidence of carbonylation in α-ketoglutarate dehydrogenase (KGDH), aconitase or subunits of respiratory chain complexes. Lon protease inactivation upon MPTP treatment in mice raises the possibility that Lon protease dysfunction is an early event in the pathogenesis of PD.
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Affiliation(s)
- Anne-Laure Bulteau
- INSERM, U1127, The Brain and Spinal Cord Institute (ICM), Hôpital de la Salpêtrière, 75013 Paris, France; CNRS, UMR 7225, Centre de Recherche en neurosciences, ICM, Thérapeutique expérimentale de la neurodégénérescence, Hôpital de la Salpêtrière, Paris, F-75005 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, 75005 Paris, France.
| | - Natalia P Mena
- INSERM, U1127, The Brain and Spinal Cord Institute (ICM), Hôpital de la Salpêtrière, 75013 Paris, France; CNRS, UMR 7225, Centre de Recherche en neurosciences, ICM, Thérapeutique expérimentale de la neurodégénérescence, Hôpital de la Salpêtrière, Paris, F-75005 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, 75005 Paris, France; Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile; Millennium Institute of Cell Dynamics and Biotechnology, Santiago, Chile
| | - Françoise Auchère
- Laboratoire Mitochondries, Métaux et Stress Oxydatif, Département de Pathologie Moléculaire et Cellulaire, Institut Jacques Monod, Université Paris-Diderot/CNRS, Paris, France
| | - Irene Lee
- Case Western Reserve University Department of Chemistry, Cleveland, OH 44106, USA
| | - Annick Prigent
- INSERM, U1127, The Brain and Spinal Cord Institute (ICM), Hôpital de la Salpêtrière, 75013 Paris, France; CNRS, UMR 7225, Centre de Recherche en neurosciences, ICM, Thérapeutique expérimentale de la neurodégénérescence, Hôpital de la Salpêtrière, Paris, F-75005 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, 75005 Paris, France
| | - Christian S Lobsiger
- INSERM, U1127, The Brain and Spinal Cord Institute (ICM), Hôpital de la Salpêtrière, 75013 Paris, France; CNRS, UMR 7225, Centre de Recherche en neurosciences, ICM, Thérapeutique expérimentale de la neurodégénérescence, Hôpital de la Salpêtrière, Paris, F-75005 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, 75005 Paris, France
| | - Jean-Michel Camadro
- Laboratoire Mitochondries, Métaux et Stress Oxydatif, Département de Pathologie Moléculaire et Cellulaire, Institut Jacques Monod, Université Paris-Diderot/CNRS, Paris, France
| | - Etienne C Hirsch
- INSERM, U1127, The Brain and Spinal Cord Institute (ICM), Hôpital de la Salpêtrière, 75013 Paris, France; CNRS, UMR 7225, Centre de Recherche en neurosciences, ICM, Thérapeutique expérimentale de la neurodégénérescence, Hôpital de la Salpêtrière, Paris, F-75005 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, 75005 Paris, France.
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Mena NP, García-Beltrán O, Lourido F, Urrutia PJ, Mena R, Castro-Castillo V, Cassels BK, Núñez MT. Corrigendum to "The novel mitochondrial iron chelator 5-((methylamino)methyl)-8-hydroxyquinoline protects against mitochondrial-induced oxidative damage and neuronal death" [Biochem. Biophys. Res. Commun. 463 (4) (2015) 787-792]. Biochem Biophys Res Commun 2016; 473:361. [PMID: 27087027 DOI: 10.1016/j.bbrc.2016.03.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- Natalia P Mena
- Iron and Biology of Aging Laboratory, Department of Biology, Faculty of Sciences, University of Chile, Chile.
| | - Olimpo García-Beltrán
- Facultad de Ciencias Naturales y Matemáticas, Universidad de Ibagué, Ibagué, 730001, Colombia
| | - Fernanda Lourido
- Iron and Biology of Aging Laboratory, Department of Biology, Faculty of Sciences, University of Chile, Chile
| | - Pamela J Urrutia
- Iron and Biology of Aging Laboratory, Department of Biology, Faculty of Sciences, University of Chile, Chile
| | - Raúl Mena
- Iron and Biology of Aging Laboratory, Department of Biology, Faculty of Sciences, University of Chile, Chile
| | - Vicente Castro-Castillo
- Faculty of Basic Sciences, Universidad Metropolitana de Ciencias de la Educación, Santiago, Chile
| | - Bruce K Cassels
- Department of Chemistry, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Marco T Núñez
- Iron and Biology of Aging Laboratory, Department of Biology, Faculty of Sciences, University of Chile, Chile
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Aguirre P, Mena NP, Carrasco CM, Muñoz Y, Pérez-Henríquez P, Morales RA, Cassels BK, Méndez-Gálvez C, García-Beltrán O, González-Billault C, Núñez MT. Iron Chelators and Antioxidants Regenerate Neuritic Tree and Nigrostriatal Fibers of MPP+/MPTP-Lesioned Dopaminergic Neurons. PLoS One 2015; 10:e0144848. [PMID: 26658949 PMCID: PMC4684383 DOI: 10.1371/journal.pone.0144848] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/24/2015] [Indexed: 01/08/2023] Open
Abstract
Neuronal death in Parkinson’s disease (PD) is often preceded by axodendritic tree retraction and loss of neuronal functionality. The presence of non-functional but live neurons opens therapeutic possibilities to recover functionality before clinical symptoms develop. Considering that iron accumulation and oxidative damage are conditions commonly found in PD, we tested the possible neuritogenic effects of iron chelators and antioxidant agents. We used three commercial chelators: DFO, deferiprone and 2.2’-dypyridyl, and three 8-hydroxyquinoline-based iron chelators: M30, 7MH and 7DH, and we evaluated their effects in vitro using a mesencephalic cell culture treated with the Parkinsonian toxin MPP+ and in vivo using the MPTP mouse model. All chelators tested promoted the emergence of new tyrosine hydroxylase (TH)-positive processes, increased axodendritic tree length and protected cells against lipoperoxidation. Chelator treatment resulted in the generation of processes containing the presynaptic marker synaptophysin. The antioxidants N-acetylcysteine and dymetylthiourea also enhanced axodendritic tree recovery in vitro, an indication that reducing oxidative tone fosters neuritogenesis in MPP+-damaged neurons. Oral administration to mice of the M30 chelator for 14 days after MPTP treatment resulted in increased TH- and GIRK2-positive nigra cells and nigrostriatal fibers. Our results support a role for oral iron chelators as good candidates for the early treatment of PD, at stages of the disease where there is axodendritic tree retraction without neuronal death.
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Affiliation(s)
- Pabla Aguirre
- Iron and Biology of Aging Laboratory, Biology Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
- Research Ring on Oxidative Stress in the Nervous System, Santiago, Chile
| | - Natalia P. Mena
- Iron and Biology of Aging Laboratory, Biology Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
| | - Carlos M. Carrasco
- Iron and Biology of Aging Laboratory, Biology Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
- Research Ring on Oxidative Stress in the Nervous System, Santiago, Chile
| | - Yorka Muñoz
- Iron and Biology of Aging Laboratory, Biology Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
- Research Ring on Oxidative Stress in the Nervous System, Santiago, Chile
| | - Patricio Pérez-Henríquez
- Iron and Biology of Aging Laboratory, Biology Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
| | - Rodrigo A. Morales
- Iron and Biology of Aging Laboratory, Biology Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
| | - Bruce K. Cassels
- Chemobiodynamics Laboratory, Chemistry Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
| | - Carolina Méndez-Gálvez
- Chemobiodynamics Laboratory, Chemistry Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
| | - Olimpo García-Beltrán
- Chemobiodynamics Laboratory, Chemistry Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
- Facultad de Ciencias Naturales y Matemáticas, Universidad de Ibagué, Ibagué, Colombia
| | - Christian González-Billault
- Research Ring on Oxidative Stress in the Nervous System, Santiago, Chile
- Neuronal and Cellular Dynamics Laboratory, Biology Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
| | - Marco T. Núñez
- Iron and Biology of Aging Laboratory, Biology Department, Faculty of Sciences, Universidad de Chile, Santiago, Chile
- Research Ring on Oxidative Stress in the Nervous System, Santiago, Chile
- * E-mail:
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Mena NP, Urrutia PJ, Lourido F, Carrasco CM, Núñez MT. Mitochondrial iron homeostasis and its dysfunctions in neurodegenerative disorders. Mitochondrion 2015; 21:92-105. [PMID: 25667951 DOI: 10.1016/j.mito.2015.02.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 01/13/2015] [Accepted: 02/02/2015] [Indexed: 12/17/2022]
Abstract
Synthesis of the iron-containing prosthetic groups-heme and iron-sulfur clusters-occurs in mitochondria. The mitochondrion is also an important producer of reactive oxygen species (ROS), which are derived from electrons leaking from the electron transport chain. The coexistence of both ROS and iron in the secluded space of the mitochondrion makes this organelle particularly prone to oxidative damage. Here, we review the elements that configure mitochondrial iron homeostasis and discuss the principles of iron-mediated ROS generation in mitochondria. We also review the evidence for mitochondrial dysfunction and iron accumulation in Alzheimer's disease, Huntington Disease, Friedreich's ataxia, and in particular Parkinson's disease. We postulate that a positive feedback loop of mitochondrial dysfunction, iron accumulation, and ROS production accounts for the process of cell death in various neurodegenerative diseases in which these features are present.
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Affiliation(s)
- Natalia P Mena
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile; Research Ring on Oxidative Stress in the Nervous System, Universidad de Chile, Santiago, Chile
| | - Pamela J Urrutia
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile; Research Ring on Oxidative Stress in the Nervous System, Universidad de Chile, Santiago, Chile
| | - Fernanda Lourido
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile; Research Ring on Oxidative Stress in the Nervous System, Universidad de Chile, Santiago, Chile
| | - Carlos M Carrasco
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile; Research Ring on Oxidative Stress in the Nervous System, Universidad de Chile, Santiago, Chile
| | - Marco T Núñez
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile; Research Ring on Oxidative Stress in the Nervous System, Universidad de Chile, Santiago, Chile.
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Urrutia PJ, Mena NP, Núñez MT. The interplay between iron accumulation, mitochondrial dysfunction, and inflammation during the execution step of neurodegenerative disorders. Front Pharmacol 2014; 5:38. [PMID: 24653700 PMCID: PMC3948003 DOI: 10.3389/fphar.2014.00038] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 02/19/2014] [Indexed: 12/21/2022] Open
Abstract
A growing set of observations points to mitochondrial dysfunction, iron accumulation, oxidative damage and chronic inflammation as common pathognomonic signs of a number of neurodegenerative diseases that includes Alzheimer’s disease, Huntington disease, amyotrophic lateral sclerosis, Friedrich’s ataxia and Parkinson’s disease. Particularly relevant for neurodegenerative processes is the relationship between mitochondria and iron. The mitochondrion upholds the synthesis of iron–sulfur clusters and heme, the most abundant iron-containing prosthetic groups in a large variety of proteins, so a fraction of incoming iron must go through this organelle before reaching its final destination. In turn, the mitochondrial respiratory chain is the source of reactive oxygen species (ROS) derived from leaks in the electron transport chain. The co-existence of both iron and ROS in the secluded space of the mitochondrion makes this organelle particularly prone to hydroxyl radical-mediated damage. In addition, a connection between the loss of iron homeostasis and inflammation is starting to emerge; thus, inflammatory cytokines like TNF-alpha and IL-6 induce the synthesis of the divalent metal transporter 1 and promote iron accumulation in neurons and microglia. Here, we review the recent literature on mitochondrial iron homeostasis and the role of inflammation on mitochondria dysfunction and iron accumulation on the neurodegenerative process that lead to cell death in Parkinson’s disease. We also put forward the hypothesis that mitochondrial dysfunction, iron accumulation and inflammation are part of a synergistic self-feeding cycle that ends in apoptotic cell death, once the antioxidant cellular defense systems are finally overwhelmed.
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Affiliation(s)
- Pamela J Urrutia
- Department of Biology and Research Ring on Oxidative Stress in the Nervous System, Faculty of Sciences, University of Chile Santiago, Chile
| | - Natalia P Mena
- Department of Biology and Research Ring on Oxidative Stress in the Nervous System, Faculty of Sciences, University of Chile Santiago, Chile
| | - Marco T Núñez
- Department of Biology and Research Ring on Oxidative Stress in the Nervous System, Faculty of Sciences, University of Chile Santiago, Chile
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Urrutia P, Aguirre P, Esparza A, Tapia V, Mena NP, Arredondo M, González-Billault C, Núñez MT. Inflammation alters the expression of DMT1, FPN1 and hepcidin, and it causes iron accumulation in central nervous system cells. J Neurochem 2013; 126:541-9. [PMID: 23506423 DOI: 10.1111/jnc.12244] [Citation(s) in RCA: 252] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 02/27/2013] [Accepted: 03/01/2013] [Indexed: 12/23/2022]
Abstract
Inflammation and iron accumulation are present in a variety of neurodegenerative diseases that include Alzheimer's disease and Parkinson's disease. The study of the putative association between inflammation and iron accumulation in central nervous system cells is relevant to understand the contribution of these processes to the progression of neuronal death. In this study, we analyzed the effects of the inflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) and of lipopolysaccharide on total cell iron content and on the expression and abundance of the iron transporters divalent metal transporter 1 (DMT1) and Ferroportin 1 (FPN1) in neurons, astrocytes and microglia obtained from rat brain. Considering previous reports indicating that inflammatory stimuli induce the systemic synthesis of the master iron regulator hepcidin, we identified brain cells that produce hepcidin in response to inflammatory stimuli, as well as hepcidin-target cells. We found that inflammatory stimuli increased the expression of DMT1 in neurons, astrocytes, and microglia. Inflammatory stimuli also induced the expression of hepcidin in astrocytes and microglia, but not in neurons. Incubation with hepcidin decreased the expression of FPN1 in the three cell types. The net result of these changes was increased iron accumulation in neurons and microglia but not in astrocytes. The data presented here establish for the first time a causal association between inflammation and iron accumulation in brain cells, probably promoted by changes in DMT1 and FPN1 expression and mediated in part by hepcidin. This connection may potentially contribute to the progression of neurodegenerative diseases by enhancing iron-induced oxidative damage.
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Affiliation(s)
- Pamela Urrutia
- Department of Biology, Faculty of Sciences, Universidad de Chile and Research Ring on Oxidative Stress in the Nervous System, Santiago, Chile
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Mena NP, Bulteau AL, Salazar J, Hirsch EC, Núñez MT. Effect of mitochondrial complex I inhibition on Fe-S cluster protein activity. Biochem Biophys Res Commun 2011; 409:241-6. [PMID: 21570952 DOI: 10.1016/j.bbrc.2011.04.137] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 04/28/2011] [Indexed: 11/26/2022]
Abstract
Iron-sulfur (Fe-S) clusters are small inorganic cofactors formed by tetrahedral coordination of iron atoms with sulfur groups. Present in numerous proteins, these clusters are involved in key biological processes such as electron transfer, metabolic and regulatory processes, DNA synthesis and repair and protein structure stabilization. Fe-S clusters are synthesized mainly in the mitochondrion, where they are directly incorporated into mitochondrial Fe-S cluster-containing proteins or exported for cytoplasmic and nuclear cluster-protein assembly. In this study, we tested the hypothesis that inhibition of mitochondrial complex I by rotenone decreases Fe-S cluster synthesis and cluster content and activity of Fe-S cluster-containing enzymes. Inhibition of complex I resulted in decreased activity of three Fe-S cluster-containing enzymes: mitochondrial and cytosolic aconitases and xanthine oxidase. In addition, the Fe-S cluster content of glutamine phosphoribosyl pyrophosphate amidotransferase and mitochondrial aconitase was dramatically decreased. The reduction in cytosolic aconitase activity was associated with an increase in iron regulatory protein (IRP) mRNA binding activity and with an increase in the cytoplasmic labile iron pool. Since IRP activity post-transcriptionally regulates the expression of iron import proteins, Fe-S cluster inhibition may result in a false iron deficiency signal. Given that inhibition of complex I and iron accumulation are hallmarks of idiopathic Parkinson's disease, the findings reported here may have relevance for understanding the pathophysiology of this disease.
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Affiliation(s)
- Natalia P Mena
- Department of Biology, Faculty of Sciences, Universidad de Chile, Las Palmeras 3425, Santiago, Chile
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Abstract
Hepcidin (Hepc) is considered a key mediator in iron trafficking. Although the mechanism of Hepc action in macrophages is fairly well established, much less is known about its action in intestinal cells, one of the main targets of Hepc. The current study investigated the effects of physiologically generated Hepc on iron transport in Caco-2 cell monolayers and rat duodenal segments compared with the effects on the J774 macrophage cell line. Addition of Hepc to Caco-2 cells or rat duodenal segments strongly inhibited apical (55)Fe uptake without apparent effects on the transfer of (55)Fe from the cells to the basolateral medium. Concurrently, the levels of divalent metal transporter 1 (DMT1) mRNA and protein in Caco-2 cells decreased while the mRNA and protein levels of the iron export transporter ferroportin did not change. Plasma membrane localization of ferroportin was studied by selective biotinylation of apical and basolateral membrane domains; Hepc induced rapid internalization of ferroportin in J774 cells but not in Caco-2 cells These results indicate that the effect of Hepc is cell dependent: in macrophages it inhibits iron export by inducing ferroportin degradation, whereas in enterocytes it inhibits apical iron uptake by inhibiting DMT1 transcription. Our results highlight the crucial role of Hepc in the control of intestinal iron absorption.
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Affiliation(s)
- Natalia P Mena
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago, Chile
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Abstract
Hepcidin (Hepc) is a 25 amino acid cationic peptide with broad antibacterial and antifungal actions. A likely role for Hepc in iron metabolism was suggested by the observation that mice having disruption of the gene encoding the transcription factor USF2 failed to produce Hepc mRNA and developed spontaneous visceral iron overload. Lately, Hepc has been considered the "stores regulator," a putative factor that signals the iron content of the body to intestinal cells. In this work, we characterized the effect of Hepc produced by hepatoma cells on iron absorption by intestinal cells. To that end, human Hepc cDNA was cloned and overexpressed in HepG2 cells and conditioned media from Hepc-overexpressing cells was used to study the effects of Hepe on intestinal Caco-2 cells grown in bicameral inserts. The results indicate that Hepc released by HepG2 inhibited apical iron uptake by Caco-2 cells, probably by inhibiting the expression of the apical transporter DMT1. These results support a model in which Hepc released by the liver negatively regulates the expression of transporter DMT1 in the enterocyte.
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Affiliation(s)
- Natalia P Mena
- Biology Department and Cell Dynamics and Biotechnology Research Center, Faculty of Sciences, Universidad de Chile, Santiago
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