1
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Zhang DL, Ollivierre H, Rouault TA. Using Biotinylated Iron-Responsive Element to Analyze the Activity of Iron Regulatory Proteins. Int J Mol Sci 2024; 25:4852. [PMID: 38732071 PMCID: PMC11084215 DOI: 10.3390/ijms25094852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 04/26/2024] [Accepted: 04/27/2024] [Indexed: 05/13/2024] Open
Abstract
Iron regulatory proteins (IRP1 and IRP2) are the master regulators of mammalian iron homeostasis. They bind to the iron-responsive elements (IREs) of the transcripts of iron-related genes to regulate their expression, thereby maintaining cellular iron availability. The primary method to measure the IRE-binding activity of IRPs is the electrophoresis mobility shift assay (EMSA). This method is particularly useful for evaluating IRP1 activity, since IRP1 is a bifunctional enzyme and its protein levels remain similar during conversion between the IRE-binding protein and cytosolic aconitase forms. Here, we exploited a method of using a biotinylated-IRE probe to separate IRE-binding IRPs followed by immunoblotting to analyze the IRE-binding activity. This method allows for the successful measurement of IRP activity in cultured cells and mouse tissues under various iron conditions. By separating IRE-binding IRPs from the rest of the lysates, this method increases the specificity of IRP antibodies and verifies whether a band represents an IRP, thereby revealing some previously unrecognized information about IRPs. With this method, we showed that the S711-phosphorylated IRP1 was found only in the IRE-binding form in PMA-treated Hep3B cells. Second, we found a truncated IRE-binding IRP2 isoform that is generated by proteolytic cleavage on sites in the 73aa insert region of the IRP2 protein. Third, we found that higher levels of SDS, compared to 1-2% SDS in regular loading buffer, could dramatically increase the band intensity of IRPs in immunoblots, especially in HL-60 cells. Fourth, we found that the addition of SDS or LDS to cell lysates activated protein degradation at 37 °C or room temperature, especially in HL-60 cell lysates. As this method is more practical, sensitive, and cost-effective, we believe that its application will enhance future research on iron regulation and metabolism.
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Affiliation(s)
| | | | - Tracey A. Rouault
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA; (D.-L.Z.); (H.O.)
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2
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Pan S, Hale AT, Lemieux ME, Raval DK, Garton TP, Sadler B, Mahaney KB, Strahle JM. Iron homeostasis and post-hemorrhagic hydrocephalus: a review. Front Neurol 2024; 14:1287559. [PMID: 38283681 PMCID: PMC10811254 DOI: 10.3389/fneur.2023.1287559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Accepted: 11/21/2023] [Indexed: 01/30/2024] Open
Abstract
Iron physiology is regulated by a complex interplay of extracellular transport systems, coordinated transcriptional responses, and iron efflux mechanisms. Dysregulation of iron metabolism can result in defects in myelination, neurotransmitter synthesis, and neuronal maturation. In neonates, germinal matrix-intraventricular hemorrhage (GMH-IVH) causes iron overload as a result of blood breakdown in the ventricles and brain parenchyma which can lead to post-hemorrhagic hydrocephalus (PHH). However, the precise mechanisms by which GMH-IVH results in PHH remain elusive. Understanding the molecular determinants of iron homeostasis in the developing brain may lead to improved therapies. This manuscript reviews the various roles iron has in brain development, characterizes our understanding of iron transport in the developing brain, and describes potential mechanisms by which iron overload may cause PHH and brain injury. We also review novel preclinical treatments for IVH that specifically target iron. Understanding iron handling within the brain and central nervous system may provide a basis for preventative, targeted treatments for iron-mediated pathogenesis of GMH-IVH and PHH.
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Affiliation(s)
- Shelei Pan
- Department of Neurosurgery, Washington University School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
| | - Andrew T. Hale
- Department of Neurosurgery, University of Alabama at Birmingham School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Mackenzie E. Lemieux
- Department of Neurosurgery, Washington University School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
| | - Dhvanii K. Raval
- Department of Neurosurgery, Washington University School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
| | - Thomas P. Garton
- Department of Neurology, Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Brooke Sadler
- Department of Pediatrics, Washington University School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
- Department of Hematology and Oncology, Washington University School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
| | - Kelly B. Mahaney
- Department of Neurosurgery, Stanford University School of Medicine, Stanford University, Palo Alto, CA, United States
| | - Jennifer M. Strahle
- Department of Neurosurgery, Washington University School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
- Department of Pediatrics, Washington University School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
- Department of Orthopedic Surgery, Washington University School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
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3
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Zhang Z, Jiang W, Zhang C, Yin Y, Mu N, Wang Y, Yu L, Ma H. Frataxin inhibits the sensitivity of the myocardium to ferroptosis by regulating iron homeostasis. Free Radic Biol Med 2023; 205:305-317. [PMID: 37343689 DOI: 10.1016/j.freeradbiomed.2023.06.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/08/2023] [Accepted: 06/19/2023] [Indexed: 06/23/2023]
Abstract
RATIONALE Myocardial ischemia/reperfusion (I/R) injury is characterized by cell death via various cellular mechanisms upon reperfusion. As a new type of cell death, ferroptosis provides new opportunities to reduce myocardial cell death. Ferroptosis is known to be more active during reperfusion than ischemia. However, the mechanisms regulating ferroptosis during ischemia and reperfusion remain largely unknown. METHODS The contribution of ferroptosis in ischemic and reperfused myocardium were detected by administered of Fer-1, a ferroptosis inhibitor to C57BL/6 mice, followed by left anterior descending (LAD) ligation surgery. Ferroptosis was evaluated by measurement of cell viability, ptgs2 mRNA level, iron production, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels. H9C2 cells were exposed to hypoxia/reoxygenation to mimic in vivo I/R. We used LC-MS/MS to identify potential E3 ligases that interacted with frataxin in heart tissue. Cardiac-specific overexpression of frataxin in whole heart was achieved by intracardiac injection of frataxin, carried by adeno-associated virus serotype 9 (AAV9) containing cardiac troponin T (cTnT) promoter. RESULTS We showed that regulators of iron metabolism, especially iron regulatory protein activity, were increased in the ischemic myocardium or hypoxia cardiomyocytes. In addition, we found that frataxin, which is involved in iron metabolism, is differentially expressed in the ischemic and reperfused myocardium and involved in the regulation of cardiomyocytes ferroptosis. Furthermore, we identified an E3 ligase, NHL repeat-containing 1 (NHLRC1), that mediates frataxin ubiquitination degradation. Cardiac-specific overexpression of frataxin ameliorated myocardial I/R injury through ferroptosis inhibition. CONCLUSIONS Through a multi-level study from molecule to animal model, these findings uncover the key role of frataxin in inhibiting cardiomyocyte ferroptosis and provide new strategies and perspectives for the treatment of myocardial I/R injury.
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Affiliation(s)
- Zihui Zhang
- Xi'an Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
| | - Wenhua Jiang
- Xi'an Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
| | - Chan Zhang
- Xi'an Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
| | - Yue Yin
- Department of Physiology and Pathophysiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, Shaanxi, 710032, PR China
| | - Nan Mu
- Department of Physiology and Pathophysiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, Shaanxi, 710032, PR China
| | - Yishi Wang
- Department of Physiology and Pathophysiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, Shaanxi, 710032, PR China
| | - Lu Yu
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
| | - Heng Ma
- Xi'an Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China; Department of Physiology and Pathophysiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, Shaanxi, 710032, PR China.
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4
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Gehrer CM, Mitterstiller AM, Grubwieser P, Meyron-Holtz EG, Weiss G, Nairz M. Advances in Ferritin Physiology and Possible Implications in Bacterial Infection. Int J Mol Sci 2023; 24:4659. [PMID: 36902088 PMCID: PMC10003477 DOI: 10.3390/ijms24054659] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/17/2023] [Accepted: 02/25/2023] [Indexed: 03/04/2023] Open
Abstract
Due to its advantageous redox properties, iron plays an important role in the metabolism of nearly all life. However, these properties are not only a boon but also the bane of such life forms. Since labile iron results in the generation of reactive oxygen species by Fenton chemistry, iron is stored in a relatively safe form inside of ferritin. Despite the fact that the iron storage protein ferritin has been extensively researched, many of its physiological functions are hitherto unresolved. However, research regarding ferritin's functions is gaining momentum. For example, recent major discoveries on its secretion and distribution mechanisms have been made as well as the paradigm-changing finding of intracellular compartmentalization of ferritin via interaction with nuclear receptor coactivator 4 (NCOA4). In this review, we discuss established knowledge as well as these new findings and the implications they may have for host-pathogen interaction during bacterial infection.
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Affiliation(s)
- Clemens M. Gehrer
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Anna-Maria Mitterstiller
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Philipp Grubwieser
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Esther G. Meyron-Holtz
- Laboratory of Molecular Nutrition, Faculty of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Günter Weiss
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Medical University of Innsbruck, 6020 Innsbruck, Austria
- Christian Doppler Laboratory for Iron Metabolism and Anemia Research, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Manfred Nairz
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Medical University of Innsbruck, 6020 Innsbruck, Austria
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5
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Rethinking IRPs/IRE system in neurodegenerative disorders: Looking beyond iron metabolism. Ageing Res Rev 2022; 73:101511. [PMID: 34767973 DOI: 10.1016/j.arr.2021.101511] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/21/2021] [Accepted: 11/04/2021] [Indexed: 12/11/2022]
Abstract
Iron regulatory proteins (IRPs) and iron regulatory element (IRE) systems are well known in the progression of neurodegenerative disorders by regulating iron related proteins. IRPs are also regulated by iron homeostasis. However, an increasing number of studies have suggested a close relationship between the IRPs/IRE system and non-iron-related neurodegenerative disorders. In this paper, we reviewed that the IRPs/IRE system is not only controlled by iron ions, but also regulated by such factors as post-translational modification, oxygen, nitric oxide (NO), heme, interleukin-1 (IL-1), and metal ions. In addition, by regulating the transcription of non-iron related proteins, the IRPs/IRE system functioned in oxidative metabolism, cell cycle regulation, abnormal proteins aggregation, and neuroinflammation. Finally, by emphasizing the multiple regulations of IRPs/IRE system and its potential relationship with non-iron metabolic neurodegenerative disorders, we provided new strategies for disease treatment targeting IRPs/IRE system.
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6
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Gonzalez-Sanchez L, Cobos-Fernandez MA, Lopez-Nieva P, Villa-Morales M, Stamatakis K, Cuezva JM, Marin-Rubio JL, Vazquez-Dominguez I, Gonzalez-Vasconcellos I, Salido E, Llamas P, Lopez-Lorenzo JL, Santos J, Fernandez-Piqueras J. Exploiting the passenger ACO1-deficiency arising from 9p21 deletions to kill T-cell lymphoblastic neoplasia cells. Carcinogenesis 2021; 41:1113-1122. [PMID: 31734690 DOI: 10.1093/carcin/bgz185] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 10/17/2019] [Accepted: 11/12/2019] [Indexed: 11/14/2022] Open
Abstract
Precursor T-cell lymphoblastic neoplasms are aggressive malignancies in need for more effective and specific therapeutic treatments. A significant fraction of these neoplasms harbor deletions on the locus 9p21, targeting the tumor suppressor CDKN2A but also deleting the aconitase 1 (ACO1) gene, a neighboring housekeeping gene involved in cytoplasm and mitochondrial metabolism. Here we show that reducing the aconitase activity with fluorocitrate decreases the viability of T-cell lymphoblastic neoplasia cells in correlation to the differential aconitase expression. The consequences of the treatment were evidenced in vitro using T-cell lymphoblastic neoplasia cell lines exhibiting 9p21 deletions and variable levels of ACO1 expression or activity. Similar results were observed in melanoma cell lines, suggesting a true potential for fluorocitrate in different cancer types. Notably, ectopic expression of ACO1 alleviated the susceptibility of cell lines to fluorocitrate and, conversely, knockdown experiments increased susceptibility of resistant cell lines. These findings were confirmed in vivo on athymic nude mice by using tumor xenografts derived from two T-cell lines with different levels of ACO1. Taken together, our results indicate that the non-targeted ACO1 deficiency induced by common deletions exerts a collateral cellular lethality that can be used as a novel therapeutic strategy in the treatment of several types of cancer.
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Affiliation(s)
- Laura Gonzalez-Sanchez
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain.,Division of Hematology and Hemotherapy, IIS Fundación Jiménez Díaz, Madrid, Spain.,Consorcio de Investigación Biomédica de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Maria A Cobos-Fernandez
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain.,Division of Hematology and Hemotherapy, IIS Fundación Jiménez Díaz, Madrid, Spain
| | - Pilar Lopez-Nieva
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain.,Division of Hematology and Hemotherapy, IIS Fundación Jiménez Díaz, Madrid, Spain.,Consorcio de Investigación Biomédica de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Maria Villa-Morales
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain.,Division of Hematology and Hemotherapy, IIS Fundación Jiménez Díaz, Madrid, Spain.,Consorcio de Investigación Biomédica de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Konstantinos Stamatakis
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain
| | - Jose M Cuezva
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain.,Consorcio de Investigación Biomédica de Enfermedades Raras (CIBERER), Madrid, Spain.,Division of Cancer, Instituto de Investigación Hospital 12 de Octubre, Madrid, Spain
| | - Jose L Marin-Rubio
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain
| | - Irene Vazquez-Dominguez
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain
| | - Iria Gonzalez-Vasconcellos
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain
| | - Eduardo Salido
- Consorcio de Investigación Biomédica de Enfermedades Raras (CIBERER), Madrid, Spain.,Department of Pathology, Hospital Universitario de Canarias, ITB, Universidad de La Laguna, La Cuesta, Spain
| | - Pilar Llamas
- Division of Hematology and Hemotherapy, IIS Fundación Jiménez Díaz, Madrid, Spain
| | - Jose L Lopez-Lorenzo
- Division of Hematology and Hemotherapy, IIS Fundación Jiménez Díaz, Madrid, Spain
| | - Javier Santos
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain.,Division of Hematology and Hemotherapy, IIS Fundación Jiménez Díaz, Madrid, Spain.,Consorcio de Investigación Biomédica de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Jose Fernandez-Piqueras
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa (CBMSO), Madrid, Spain.,Division of Hematology and Hemotherapy, IIS Fundación Jiménez Díaz, Madrid, Spain.,Consorcio de Investigación Biomédica de Enfermedades Raras (CIBERER), Madrid, Spain
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7
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Terzi EM, Sviderskiy VO, Alvarez SW, Whiten GC, Possemato R. Iron-sulfur cluster deficiency can be sensed by IRP2 and regulates iron homeostasis and sensitivity to ferroptosis independent of IRP1 and FBXL5. SCIENCE ADVANCES 2021; 7:7/22/eabg4302. [PMID: 34039609 PMCID: PMC8153722 DOI: 10.1126/sciadv.abg4302] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 04/08/2021] [Indexed: 05/23/2023]
Abstract
Intracellular iron levels are strictly regulated to support homeostasis and avoid iron-mediated ROS production. Loss of iron-sulfur cluster (ISC) synthesis can increase iron loading and promote cell death by ferroptosis. Iron-responsive element-binding proteins IRP1 and IRP2 posttranscriptionally regulate iron homeostasis. IRP1 binding to target mRNAs is competitively regulated by ISC occupancy. However, IRP2 is principally thought to be regulated at the protein level via E3 ubiquitin ligase FBXL5-mediated degradation. Here, we show that ISC synthesis suppression can activate IRP2 and promote ferroptosis sensitivity via a previously unidentified mechanism. At tissue-level O2 concentrations, ISC deficiency enhances IRP2 binding to target mRNAs independent of IRP1, FBXL5, and changes in IRP2 protein level. Deletion of both IRP1 and IRP2 abolishes the iron-starvation response, preventing its activation by ISC synthesis inhibition. These findings will inform strategies to manipulate ferroptosis sensitivity and help illuminate the mechanism underlying ISC biosynthesis disorders, such as Friedreich's ataxia.
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Affiliation(s)
- Erdem M Terzi
- Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Laura and Isaac Perlmutter Cancer Center, New York, NY 10016, USA
| | - Vladislav O Sviderskiy
- Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Laura and Isaac Perlmutter Cancer Center, New York, NY 10016, USA
| | - Samantha W Alvarez
- Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Laura and Isaac Perlmutter Cancer Center, New York, NY 10016, USA
| | - Gabrielle C Whiten
- Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA
- Laura and Isaac Perlmutter Cancer Center, New York, NY 10016, USA
| | - Richard Possemato
- Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA.
- Laura and Isaac Perlmutter Cancer Center, New York, NY 10016, USA
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8
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Zhu L, Zhou Q, He L, Chen L. IRP2-Hif1α/Hif2α signaling: a novel mechanism of metabolic switch from aerobic glycolysis to oxidative phosphorylation. Acta Biochim Biophys Sin (Shanghai) 2020; 52:1175-1177. [PMID: 32813008 DOI: 10.1093/abbs/gmaa088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/22/2020] [Indexed: 01/18/2023] Open
Affiliation(s)
- Li Zhu
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang 421001, China
| | - Qionglin Zhou
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang 421001, China
| | - Lu He
- Department of Pharmacy, The First Affiliated Hospital, University of South China, Hengyang 421001, China
| | - Linxi Chen
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang 421001, China
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9
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Zhang Y, Feng X, Zhang J, Chen X. Iron Regulatory Protein 2 Exerts its Oncogenic Activities by Suppressing TAp63 Expression. Mol Cancer Res 2020; 18:1039-1049. [PMID: 32276991 DOI: 10.1158/1541-7786.mcr-19-1104] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 02/19/2020] [Accepted: 04/07/2020] [Indexed: 12/15/2022]
Abstract
Iron regulatory protein 2 (IRP2) is a key regulator of iron homeostasis and is found to be altered in several types of human cancer. However, how IRP2 contributes to tumorigenesis remains to be elucidated. In this study, we sought to investigate the role of IRP2 in tumorigenesis and found that IRP2 promotes cell growth by repressing TAp63, a member of p53 tumor suppressor family. Specifically, we found that IRP2 overexpression decreased, whereas IRP2 deficiency increased, TAp63 expression. We also showed that the repression of TAp63 by IRP2 was independent of tumor suppressor p53. To uncover the molecular basis, we found that IRP2 stabilized TAp63 mRNA by binding to an iron response element in the 3'UTR of p63 mRNA. To determine the biological significance of this regulation, we showed that IRP2 facilitates cell proliferation, at least in part, via repressing TAp63 expression. Moreover, we found that IRP2 deficiency markedly alleviated cellular senescence in TAp63-deficient mouse embryo fibroblasts. Together, we have uncovered a novel regulation of TAp63 by IRP2 and our data suggest that IRP2 exerts its oncogenic activities at least in part by repressing TAp63 expression. IMPLICATIONS: We have revealed a novel regulation of TAp63 by IRP2 and our data suggest that IRP2 exerts its oncogenic activities, at least in part, by repressing TAp63 expression.
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Affiliation(s)
- Yanhong Zhang
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California
| | - Xiuli Feng
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Jin Zhang
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California
| | - Xinbin Chen
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California.
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10
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Wang H, Shi H, Rajan M, Canarie ER, Hong S, Simoneschi D, Pagano M, Bush MF, Stoll S, Leibold EA, Zheng N. FBXL5 Regulates IRP2 Stability in Iron Homeostasis via an Oxygen-Responsive [2Fe2S] Cluster. Mol Cell 2020; 78:31-41.e5. [PMID: 32126207 DOI: 10.1016/j.molcel.2020.02.011] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 12/30/2019] [Accepted: 02/11/2020] [Indexed: 12/21/2022]
Abstract
Cellular iron homeostasis is dominated by FBXL5-mediated degradation of iron regulatory protein 2 (IRP2), which is dependent on both iron and oxygen. However, how the physical interaction between FBXL5 and IRP2 is regulated remains elusive. Here, we show that the C-terminal substrate-binding domain of FBXL5 harbors a [2Fe2S] cluster in the oxidized state. A cryoelectron microscopy (cryo-EM) structure of the IRP2-FBXL5-SKP1 complex reveals that the cluster organizes the FBXL5 C-terminal loop responsible for recruiting IRP2. Interestingly, IRP2 binding to FBXL5 hinges on the oxidized state of the [2Fe2S] cluster maintained by ambient oxygen, which could explain hypoxia-induced IRP2 stabilization. Steric incompatibility also allows FBXL5 to physically dislodge IRP2 from iron-responsive element RNA to facilitate its turnover. Taken together, our studies have identified an iron-sulfur cluster within FBXL5, which promotes IRP2 polyubiquitination and degradation in response to both iron and oxygen concentrations.
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Affiliation(s)
- Hui Wang
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Hui Shi
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Malini Rajan
- Division of Hematology and Hematologic Malignancies and Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
| | | | - Seoyeon Hong
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Daniele Simoneschi
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; NYU Perlmutter Cancer Center, New York University School of Medicine, New York, NY 10016, USA
| | - Michele Pagano
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; NYU Perlmutter Cancer Center, New York University School of Medicine, New York, NY 10016, USA; Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA
| | - Matthew F Bush
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Elizabeth A Leibold
- Division of Hematology and Hematologic Malignancies and Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
| | - Ning Zheng
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA.
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11
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Santos MCFD, Anderson CP, Neschen S, Zumbrennen-Bullough KB, Romney SJ, Kahle-Stephan M, Rathkolb B, Gailus-Durner V, Fuchs H, Wolf E, Rozman J, de Angelis MH, Cai WM, Rajan M, Hu J, Dedon PC, Leibold EA. Irp2 regulates insulin production through iron-mediated Cdkal1-catalyzed tRNA modification. Nat Commun 2020; 11:296. [PMID: 31941883 PMCID: PMC6962211 DOI: 10.1038/s41467-019-14004-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 12/06/2019] [Indexed: 12/12/2022] Open
Abstract
Regulation of cellular iron homeostasis is crucial as both iron excess and deficiency cause hematological and neurodegenerative diseases. Here we show that mice lacking iron-regulatory protein 2 (Irp2), a regulator of cellular iron homeostasis, develop diabetes. Irp2 post-transcriptionally regulates the iron-uptake protein transferrin receptor 1 (TfR1) and the iron-storage protein ferritin, and dysregulation of these proteins due to Irp2 loss causes functional iron deficiency in β cells. This impairs Fe-S cluster biosynthesis, reducing the function of Cdkal1, an Fe-S cluster enzyme that catalyzes methylthiolation of t6A37 in tRNALysUUU to ms2t6A37. As a consequence, lysine codons in proinsulin are misread and proinsulin processing is impaired, reducing insulin content and secretion. Iron normalizes ms2t6A37 and proinsulin lysine incorporation, restoring insulin content and secretion in Irp2-/- β cells. These studies reveal a previously unidentified link between insulin processing and cellular iron deficiency that may have relevance to type 2 diabetes in humans.
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Affiliation(s)
- Maria C Ferreira Dos Santos
- Department of Medicine, Division of Hematology, University of Utah, Salt Lake City, UT, 84112, USA.,Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Cole P Anderson
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA.,Department of Oncological Sciences, University of Utah, Salt Lake City, UT, 84112, USA.,Landstuhl Regional Medical Center, 66849, Landstuhl, Germany
| | - Susanne Neschen
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Kimberly B Zumbrennen-Bullough
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA.,Department of Oncological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Steven J Romney
- Department of Medicine, Division of Hematology, University of Utah, Salt Lake City, UT, 84112, USA.,Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA.,Thermo Fisher Scientific, Waltham, MA, 02451, USA
| | - Melanie Kahle-Stephan
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,Medizinische Hochschule Brandenburg Theodor Fontane Institut für Sozialmedizin und Epidemiologie, 14770, Brandenburg an der Havel, Germany
| | - Birgit Rathkolb
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen Strasse 25, 81377, Munich, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen Strasse 25, 81377, Munich, Germany
| | - Jan Rozman
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,Czech Centre for Phenogenomics, Institute of Molecular Genetics of the Czech Academy of Sciences, Prumyslova, 595, 252 50 Vestec, Czech Republic
| | - Martin Hrabe de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.,Chair of Experimental Genetics, School of Life Science Weihenstephan, Technische Universität München, Alte Akademie 8, 85354, Freising, Germany
| | - Weiling Maggie Cai
- Department of Microbiology, National University of Singapore, Singapore, Singapore, 119077.,Antimicrobial Resistance Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, Singapore, Singapore, 138602.,Agilent Technologies, 1 Yishun Ave 7, Singapore, Singapore, 768923
| | - Malini Rajan
- Department of Medicine, Division of Hematology, University of Utah, Salt Lake City, UT, 84112, USA.,Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Jennifer Hu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Celgene Corporation, 1616 Eastlake Ave East, Seattle, WA, 98102, USA
| | - Peter C Dedon
- Antimicrobial Resistance Interdisciplinary Research Group (IRG), Singapore-MIT Alliance for Research and Technology, 1 CREATE Way, Singapore, Singapore, 138602.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Elizabeth A Leibold
- Department of Medicine, Division of Hematology, University of Utah, Salt Lake City, UT, 84112, USA. .,Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112, USA. .,Department of Oncological Sciences, University of Utah, Salt Lake City, UT, 84112, USA.
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12
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Zhang Y, Feng X, Zhang J, Chen M, Huang E, Chen X. Iron regulatory protein 2 is a suppressor of mutant p53 in tumorigenesis. Oncogene 2019; 38:6256-6269. [PMID: 31332290 DOI: 10.1038/s41388-019-0876-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 06/12/2019] [Accepted: 06/25/2019] [Indexed: 01/20/2023]
Abstract
p53 is known to play a role in iron homeostasis and is required for FDXR-mediated iron metabolism via iron regulatory protein 2 (IRP2). Interestingly, p53 is frequently mutated in tumors wherein iron is often accumulated, suggesting that mutant p53 may exert its gain of function by altering iron metabolism. In this study, we found that FDXR deficiency decreased mutant p53 expression along with altered iron metabolism in p53R270H/- MEFs and cancer cells carrying mutant p53. Consistently, we found that decreased expression of mutant p53 by FDXR deficiency inhibited mutant p53-R270H to induce carcinoma and high grade pleomorphic sarcoma in FDXR+/-; p53R270H/- mice as compared with p53R270H/- mice. Moreover, we found that like its effect on wild-type p53, loss of IRP2 increased mutant p53 expression. However, unlike its effect to suppress cell growth in cells carrying wild-type p53, loss of IRP2 promoted cell growth in cancer cells expressing mutant p53. Finally, we found that ectopic expression of IRP2 suppressed cell growth in a mutant p53-dependent manner. Together, our data indicate that mutant p53 gain-of-function can be suppressed by IRP2 and FDXR deficiency, both of which may be explored to target tumors carrying mutant p53.
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Affiliation(s)
- Yanhong Zhang
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Xiuli Feng
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, 95616, USA.,College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jin Zhang
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, 95616, USA
| | - Minyi Chen
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Eric Huang
- Department of Pathology, University of Washington, Seattle, WA, 98104, USA
| | - Xinbin Chen
- Comparative Oncology Laboratory, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, CA, 95616, USA.
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13
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Balcerak A, Trebinska-Stryjewska A, Konopinski R, Wakula M, Grzybowska EA. RNA-protein interactions: disorder, moonlighting and junk contribute to eukaryotic complexity. Open Biol 2019; 9:190096. [PMID: 31213136 PMCID: PMC6597761 DOI: 10.1098/rsob.190096] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
RNA-protein interactions are crucial for most biological processes in all organisms. However, it appears that the complexity of RNA-based regulation increases with the complexity of the organism, creating additional regulatory circuits, the scope of which is only now being revealed. It is becoming apparent that previously unappreciated features, such as disordered structural regions in proteins or non-coding regions in DNA leading to higher plasticity and pliability in RNA-protein complexes, are in fact essential for complex, precise and fine-tuned regulation. This review addresses the issue of the role of RNA-protein interactions in generating eukaryotic complexity, focusing on the newly characterized disordered RNA-binding motifs, moonlighting of metabolic enzymes, RNA-binding proteins interactions with different RNA species and their participation in regulatory networks of higher order.
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Affiliation(s)
- Anna Balcerak
- 1 The Maria Sklodowska-Curie Institute-Oncology Center , Roentgena 5, 02-781 Warsaw , Poland
| | - Alicja Trebinska-Stryjewska
- 1 The Maria Sklodowska-Curie Institute-Oncology Center , Roentgena 5, 02-781 Warsaw , Poland.,2 Biomedical Engineering Centre, Institute of Optoelectronics, Military University of Technology , Sylwestra Kaliskiego 2, 00-908 Warsaw , Poland
| | - Ryszard Konopinski
- 1 The Maria Sklodowska-Curie Institute-Oncology Center , Roentgena 5, 02-781 Warsaw , Poland
| | - Maciej Wakula
- 1 The Maria Sklodowska-Curie Institute-Oncology Center , Roentgena 5, 02-781 Warsaw , Poland
| | - Ewa Anna Grzybowska
- 1 The Maria Sklodowska-Curie Institute-Oncology Center , Roentgena 5, 02-781 Warsaw , Poland
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14
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Dziegala M, Josiak K, Kasztura M, Kobak K, von Haehling S, Banasiak W, Anker SD, Ponikowski P, Jankowska E. Iron deficiency as energetic insult to skeletal muscle in chronic diseases. J Cachexia Sarcopenia Muscle 2018; 9:802-815. [PMID: 30178922 PMCID: PMC6204587 DOI: 10.1002/jcsm.12314] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 04/05/2018] [Accepted: 04/22/2018] [Indexed: 12/19/2022] Open
Abstract
Specific skeletal myopathy constitutes a common feature of heart failure, chronic obstructive pulmonary disease, and type 2 diabetes mellitus, where it can be characterized by the loss of skeletal muscle oxidative capacity. There is evidence from in vitro and animal studies that iron deficiency affects skeletal muscle functioning mainly in the context of its energetics by limiting oxidative metabolism in favour of glycolysis and by alterations in both carbohydrate and fat catabolic processing. In this review, we depict the possible molecular pathomechanisms of skeletal muscle energetic impairment and postulate iron deficiency as an important factor causally linked to loss of muscle oxidative capacity that contributes to skeletal myopathy seen in patients with heart failure, chronic obstructive pulmonary disease, and type 2 diabetes mellitus.
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Affiliation(s)
- Magdalena Dziegala
- Laboratory for Applied Research on Cardiovascular System, Department of Heart DiseasesWroclaw Medical University50‐981WroclawPoland
| | - Krystian Josiak
- Centre for Heart DiseasesMilitary Hospital50‐981WroclawPoland
- Department of Heart DiseasesWroclaw Medical University50‐367WroclawPoland
| | - Monika Kasztura
- Laboratory for Applied Research on Cardiovascular System, Department of Heart DiseasesWroclaw Medical University50‐981WroclawPoland
| | - Kamil Kobak
- Laboratory for Applied Research on Cardiovascular System, Department of Heart DiseasesWroclaw Medical University50‐981WroclawPoland
| | - Stephan von Haehling
- Department of Cardiology and PneumologyUniversity Medicine Göttingen (UMG)37075GöttingenGermany
| | | | - Stefan D. Anker
- Department of Cardiology and PneumologyUniversity Medicine Göttingen (UMG)37075GöttingenGermany
- Division of Cardiology and MetabolismCharité Universitätsmedizin10117BerlinGermany
- Department of Cardiology (CVK)Charité Universitätsmedizin10117BerlinGermany
- Berlin‐Brandenburg Center for Regenerative Therapies (BCRT)Charité Universitätsmedizin10117BerlinGermany
- German Centre for Cardiovascular Research (DZHK) partner site BerlinCharité Universitätsmedizin10117BerlinGermany
| | - Piotr Ponikowski
- Centre for Heart DiseasesMilitary Hospital50‐981WroclawPoland
- Department of Heart DiseasesWroclaw Medical University50‐367WroclawPoland
| | - Ewa Jankowska
- Laboratory for Applied Research on Cardiovascular System, Department of Heart DiseasesWroclaw Medical University50‐981WroclawPoland
- Centre for Heart DiseasesMilitary Hospital50‐981WroclawPoland
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15
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Mladěnka P, Hrdina R, Hübl M, Šimůnek T. The Fate of Iron in The Organism and Its Regulatory Pathways. ACTA MEDICA (HRADEC KRÁLOVÉ) 2018. [DOI: 10.14712/18059694.2018.40] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Iron is an essential element involved in many life-necessary processes. Interestingly, in mammals there is no active excretion mechanism for iron. Therefore iron kinetics has to be meticulously regulated. The most important step for regulation of iron kinetics is absorption. The absorption takes place in small intestine and it is implicated that it requires several proteins. Iron is then released from enterocytes into the circulation and delivered to the cells. Iron movement inside the cell is only partially elucidated and its traffic to mitochondia is not known. Surprisingly, the regulation of various proteins related to iron kinetics and energy metabolism at the molecular level is better described. On contrary, the complex control of iron absorption cannot be fully explicated with present knowledge.
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16
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Lumsden AL, Rogers JT, Majd S, Newman M, Sutherland GT, Verdile G, Lardelli M. Dysregulation of Neuronal Iron Homeostasis as an Alternative Unifying Effect of Mutations Causing Familial Alzheimer's Disease. Front Neurosci 2018; 12:533. [PMID: 30150923 PMCID: PMC6099262 DOI: 10.3389/fnins.2018.00533] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 07/16/2018] [Indexed: 12/12/2022] Open
Abstract
The overwhelming majority of dominant mutations causing early onset familial Alzheimer’s disease (EOfAD) occur in only three genes, PSEN1, PSEN2, and APP. An effect-in-common of these mutations is alteration of production of the APP-derived peptide, amyloid β (Aβ). It is this key fact that underlies the authority of the Amyloid Hypothesis that has informed Alzheimer’s disease research for over two decades. Any challenge to this authority must offer an alternative explanation for the relationship between the PSEN genes and APP. In this paper, we explore one possible alternative relationship – the dysregulation of cellular iron homeostasis as a common effect of EOfAD mutations in these genes. This idea is attractive since it provides clear connections between EOfAD mutations and major characteristics of Alzheimer’s disease such as dysfunctional mitochondria, vascular risk factors/hypoxia, energy metabolism, and inflammation. We combine our ideas with observations by others to describe a “Stress Threshold Change of State” model of Alzheimer’s disease that may begin to explain the existence of both EOfAD and late onset sporadic (LOsAD) forms of the disease. Directing research to investigate the role of dysregulation of iron homeostasis in EOfAD may be a profitable way forward in our struggle to understand this form of dementia.
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Affiliation(s)
- Amanda L Lumsden
- College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia.,South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Jack T Rogers
- Neurochemistry Laboratory, Department of Psychiatry-Neuroscience, Massachusetts General Hospital (East), Harvard Medical School, Harvard University, Charlestown, MA, United States
| | - Shohreh Majd
- Neuronal Injury and Repair Laboratory, Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Morgan Newman
- Centre for Molecular Pathology, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Greg T Sutherland
- Discipline of Pathology, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Giuseppe Verdile
- School of Pharmacy and Biomedical Sciences, Faculty of Health Sciences, Curtin Health Innovation Research Institute, Curtin University, Bentley, WA, Australia
| | - Michael Lardelli
- Centre for Molecular Pathology, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
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17
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Moore KS, von Lindern M. RNA Binding Proteins and Regulation of mRNA Translation in Erythropoiesis. Front Physiol 2018; 9:910. [PMID: 30087616 PMCID: PMC6066521 DOI: 10.3389/fphys.2018.00910] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 06/21/2018] [Indexed: 12/12/2022] Open
Abstract
Control of gene expression in erythropoiesis has to respond to signals that may emerge from intracellular processes or environmental factors. Control of mRNA translation allows for relatively rapid modulation of protein synthesis from the existing transcriptome. For instance, the protein synthesis rate needs to be reduced when reactive oxygen species or unfolded proteins accumulate in the cells, but also when iron supply is low or when growth factors are lacking in the environment. In addition, regulation of mRNA translation can be important as an additional layer of control on top of gene transcription, in which RNA binding proteins (RBPs) can modify translation of a set of transcripts to the cell’s actual protein requirement. The 5′ and 3′ untranslated regions of mRNA (5′UTR, 3′UTR) contain binding sites for general and sequence specific translation factors. They also contain secondary structures that may hamper scanning of the 5′UTR by translation complexes or may help to recruit translation factors. In addition, the term 5′UTR is not fully correct because many transcripts contain small open reading frames in their 5′UTR that are translated and contribute to regulation of mRNA translation. It is becoming increasingly clear that the transcriptome only partly predicts the proteome. The aim of this review is (i) to summarize how the availability of general translation initiation factors can selectively regulate transcripts because the 5′UTR contains secondary structures or short translated sequences, (ii) to discuss mechanisms that control the length of the mRNA poly(A) tail in relation to mRNA translation, and (iii) to give examples of sequence specific RBPs and their targets. We focused on transcripts and RBPs required for erythropoiesis. Whereas differentiation of erythroblasts to erythrocytes is orchestrated by erythroid transcription factors, the production of erythrocytes needs to respond to the availability of growth factors and nutrients, particularly the availability of iron.
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Affiliation(s)
- Kat S Moore
- Department of Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam UMC, Amsterdam, Netherlands
| | - Marieke von Lindern
- Department of Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam UMC, Amsterdam, Netherlands
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18
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LeBlanc RM, Longhini AP, Tugarinov V, Dayie TK. NMR probing of invisible excited states using selectively labeled RNAs. JOURNAL OF BIOMOLECULAR NMR 2018; 71:165-172. [PMID: 29858959 DOI: 10.1007/s10858-018-0184-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 04/05/2018] [Indexed: 06/08/2023]
Abstract
Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion NMR experiments are invaluable for probing sparsely and transiently populated biomolecular states that cannot be directly detected by traditional NMR experiments and that are invisible by other biophysical approaches. A notable gap for RNA is the absence of CPMG experiments for measurement of methine base 1H and methylene C5' chemical shifts of ribose moieties in the excited state, partly because of complications from homonuclear 13C-13C scalar couplings. Here we present site-specific 13C labeling that makes possible the design of pulse sequences for recording accurate 1H-13C MQ and SQ CPMG experiments for ribose methine H1'-C1' and H2'-C2', base and ribose 1H CPMG, as well as a new 1H-13C TROSY-detected methylene (CH2) C5' CPMG relaxation pulse schemes. We demonstrate the utility of these experiments for two RNAs, the A-Site RNA known to undergo exchange and the IRE RNA suspected of undergoing exchange on microseconds to millisecond time-scale. We anticipate the new labeling approaches will facilitate obtaining structures of invisible states and provide insights into the relevance of such states for RNA-drug interactions.
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Affiliation(s)
- Regan M LeBlanc
- Department of Chemistry & Biochemistry, University of Maryland, College Park, 8314 Paint Branch Dr, College Park, MD, 20782, USA
- Basic Research Laboratory, National Cancer Institute, Frederick, MD, USA
| | - Andrew P Longhini
- Department of Chemistry & Biochemistry, University of Maryland, College Park, 8314 Paint Branch Dr, College Park, MD, 20782, USA
- University of California, Santa Barbara, CA, 93106, USA
| | - Vitali Tugarinov
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-052, USA
| | - T Kwaku Dayie
- Department of Chemistry & Biochemistry, University of Maryland, College Park, 8314 Paint Branch Dr, College Park, MD, 20782, USA.
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19
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Holmes-Hampton GP, Ghosh MC, Rouault TA. Methods for Studying Iron Regulatory Protein 1: An Important Protein in Human Iron Metabolism. Methods Enzymol 2017; 599:139-155. [PMID: 29746238 DOI: 10.1016/bs.mie.2017.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Iron regulatory proteins 1 and 2 (IRP1 and IRP2) are two cytosolic proteins that maintain cellular iron homeostasis by regulating the expression of genes involved in iron metabolism. IRPs respond to cellular iron deficiency by binding to iron-responsive elements (IREs) found in the mRNAs of iron metabolism transcripts, enhancing iron import, and reducing iron storage, utilization, and export. IRP1, a bifunctional protein, exists in equilibrium between a [Fe4S4] cluster containing cytosolic aconitase, and an apoprotein that binds to IREs. At high cellular iron levels, this equilibrium is shifted more toward iron-sulfur cluster containing aconitase, whereas IRP2 undergoes proteasomal degradation by an E3 ubiquitin ligase complex that contains an F-box protein, FBXL5. Irp1-/- mice develop polycythemia and pulmonary hypertension, whereas Irp2-/- mice develop microcytic anemia and progressive neurodegeneration, indicating that Irp1 has important functions in the erythropoietic and pulmonary systems, and Irp2 has essential roles in supporting erythropoiesis and nervous system functions. Mice lacking both Irp1 and Irp2 die during embryogenesis, suggesting that functions of Irp1 and Irp2 are redundant. In this review, we will focus on the methods for studying IRP1 activities and function in cells and animals.
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Affiliation(s)
- Gregory P Holmes-Hampton
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, United States
| | - Manik C Ghosh
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, United States
| | - Tracey A Rouault
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, United States.
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20
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Thermodynamic and Kinetic Analyses of Iron Response Element (IRE)-mRNA Binding to Iron Regulatory Protein, IRP1. Sci Rep 2017; 7:8532. [PMID: 28819260 PMCID: PMC5561112 DOI: 10.1038/s41598-017-09093-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 07/21/2017] [Indexed: 11/08/2022] Open
Abstract
Comparison of kinetic and thermodynamic properties of IRP1 (iron regulatory protein1) binding to FRT (ferritin) and ACO2 (aconitase2) IRE-RNAs, with or without Mn2+, revealed differences specific to each IRE-RNA. Conserved among animal mRNAs, IRE-RNA structures are noncoding and bind Fe2+ to regulate biosynthesis rates of the encoded, iron homeostatic proteins. IRP1 protein binds IRE-RNA, inhibiting mRNA activity; Fe2+ decreases IRE-mRNA/IRP1 binding, increasing encoded protein synthesis. Here, we observed heat, 5 °C to 30 °C, increased IRP1 binding to IRE-RNA 4-fold (FRT IRE-RNA) or 3-fold (ACO2 IRE-RNA), which was enthalpy driven and entropy favorable. Mn2+ (50 µM, 25 °C) increased IRE-RNA/IRP1 binding (Kd) 12-fold (FRT IRE-RNA) or 6-fold (ACO2 IRE-RNA); enthalpic contributions decreased ~61% (FRT) or ~32% (ACO2), and entropic contributions increased ~39% (FRT) or ~68% (ACO2). IRE-RNA/IRP1 binding changed activation energies: FRT IRE-RNA 47.0 ± 2.5 kJ/mol, ACO2 IRE-RNA 35.0 ± 2.0 kJ/mol. Mn2+ (50 µM) decreased the activation energy of RNA-IRP1 binding for both IRE-RNAs. The observations suggest decreased RNA hydrogen bonding and changed RNA conformation upon IRP1 binding and illustrate how small, conserved, sequence differences among IRE-mRNAs selectively influence thermodynamic and kinetic selectivity of the protein/RNA interactions.
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21
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Rouault TA, Maio N. Biogenesis and functions of mammalian iron-sulfur proteins in the regulation of iron homeostasis and pivotal metabolic pathways. J Biol Chem 2017; 292:12744-12753. [PMID: 28615439 PMCID: PMC5546015 DOI: 10.1074/jbc.r117.789537] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fe-S cofactors are composed of iron and inorganic sulfur in various stoichiometries. A complex assembly pathway conducts their initial synthesis and subsequent binding to recipient proteins. In this minireview, we discuss how discovery of the role of the mammalian cytosolic aconitase, known as iron regulatory protein 1 (IRP1), led to the characterization of the function of its Fe-S cluster in sensing and regulating cellular iron homeostasis. Moreover, we present an overview of recent studies that have provided insights into the mechanism of Fe-S cluster transfer to recipient Fe-S proteins.
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Affiliation(s)
- Tracey A Rouault
- Molecular Medicine Branch, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892.
| | - Nunziata Maio
- Molecular Medicine Branch, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
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22
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Abstract
The regulation of iron metabolism in biological systems centers on providing adequate iron for cellular function while limiting iron toxicity. Because mammals cannot excrete iron, mechanisms have evolved to control iron acquisition, storage, and distribution at both systemic and cellular levels. Hepcidin, the master regulator of iron homeostasis, controls iron flows into plasma through inhibition of the only known mammalian cellular iron exporter ferroportin. Hepcidin is feedback-regulated by iron status and strongly modulated by inflammation and erythropoietic demand. This review highlights recent advances that have changed our understanding of iron metabolism and its regulation.
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Affiliation(s)
- Richard Coffey
- Departments of Medicine and Pathology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1690
| | - Tomas Ganz
- Departments of Medicine and Pathology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1690.
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23
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Garton T, Keep RF, Hua Y, Xi G. Brain iron overload following intracranial haemorrhage. Stroke Vasc Neurol 2016; 1:172-184. [PMID: 28959481 PMCID: PMC5435218 DOI: 10.1136/svn-2016-000042] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/01/2016] [Accepted: 11/02/2016] [Indexed: 12/15/2022] Open
Abstract
Intracranial haemorrhages, including intracerebral haemorrhage (ICH), intraventricular haemorrhage (IVH) and subarachnoid haemorrhage (SAH), are leading causes of morbidity and mortality worldwide. In addition, haemorrhage contributes to tissue damage in traumatic brain injury (TBI). To date, efforts to treat the long-term consequences of cerebral haemorrhage have been unsatisfactory. Incident rates and mortality have not showed significant improvement in recent years. In terms of secondary damage following haemorrhage, it is becoming increasingly apparent that blood components are of integral importance, with haemoglobin-derived iron playing a major role. However, the damage caused by iron is complex and varied, and therefore, increased investigation into the mechanisms by which iron causes brain injury is required. As ICH, IVH, SAH and TBI are related, this review will discuss the role of iron in each, so that similarities in injury pathologies can be more easily identified. It summarises important components of normal brain iron homeostasis and analyses the existing evidence on iron-related brain injury mechanisms. It further discusses treatment options of particular promise.
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Affiliation(s)
- Thomas Garton
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA
| | - Richard F Keep
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA
| | - Ya Hua
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA
| | - Guohua Xi
- Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan, USA
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24
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Stroh MA, Winter MK, Swerdlow RH, McCarson KE, Zhu H. Loss of NCB5OR in the cerebellum disturbs iron pathways, potentiates behavioral abnormalities, and exacerbates harmaline-induced tremor in mice. Metab Brain Dis 2016; 31:951-64. [PMID: 27188291 PMCID: PMC5929129 DOI: 10.1007/s11011-016-9834-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 05/01/2016] [Indexed: 12/13/2022]
Abstract
Iron dyshomeostasis has been implicated in many diseases, including a number of neurological conditions. Cytosolic NADH cytochrome b5 oxidoreductase (NCB5OR) is ubiquitously expressed in animal tissues and is capable of reducing ferric iron in vitro. We previously reported that global gene ablation of NCB5OR resulted in early-onset diabetes and altered iron homeostasis in mice. To further investigate the specific effects of NCB5OR deficiency on neural tissue without contributions from known phenotypes, we generated a conditional knockout (CKO) mouse that lacks NCB5OR only in the cerebellum and midbrain. Assessment of molecular markers in the cerebellum of CKO mice revealed changes in pathways associated with cellular and mitochondrial iron homeostasis. (59)Fe pulse-feeding experiments revealed cerebellum-specific increased or decreased uptake of iron by 7 and 16 weeks of age, respectively. Additionally, we characterized behavioral changes associated with loss of NCB5OR in the cerebellum and midbrain in the context of dietary iron deprivation-evoked generalized iron deficiency. Locomotor activity was reduced and complex motor task execution was altered in CKO mice treated with an iron deficient diet. A sucrose preference test revealed that the reward response was intact in CKO mice, but that iron deficient diet consumption altered sucrose preference in all mice. Detailed gait analysis revealed locomotor changes in CKO mice associated with dysfunctional proprioception and locomotor activation independent of dietary iron deficiency. Finally, we demonstrate that loss of NCB5OR in the cerebellum and midbrain exacerbated harmaline-induced tremor activity. Our findings suggest an essential role for NCB5OR in maintaining both iron homeostasis and the proper functioning of various locomotor pathways in the mouse cerebellum and midbrain.
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Affiliation(s)
- Matthew A Stroh
- Landon Center on Aging, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 1005, Kansas City, KS, 66160, USA
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3030, Kansas City, KS, 66160, USA
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3038, Kansas City, KS, 66160, USA
| | - Michelle K Winter
- Kansas Intellectual and Developmental Disabilities Research Center, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3051, Kansas City, KS, 66160, USA
| | - Russell H Swerdlow
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3030, Kansas City, KS, 66160, USA
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3038, Kansas City, KS, 66160, USA
- Department of Neurology, University of Kansas Medical Center, 3599 Rainbow Blvd., MSN 2012, Kansas City, KS, 66160, USA
| | - Kenneth E McCarson
- Kansas Intellectual and Developmental Disabilities Research Center, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3051, Kansas City, KS, 66160, USA
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 1018, Kansas City, KS, 66160, USA
| | - Hao Zhu
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3030, Kansas City, KS, 66160, USA.
- Neuroscience Graduate Program, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 3038, Kansas City, KS, 66160, USA.
- Department of Clinical Laboratory Sciences, University of Kansas Medical Center, 3901 Rainbow Blvd., MSN 4048G-Eaton, Kansas City, KS, 66160, USA.
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25
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Jiang H, Wang J, Rogers J, Xie J. Brain Iron Metabolism Dysfunction in Parkinson's Disease. Mol Neurobiol 2016; 54:3078-3101. [PMID: 27039308 DOI: 10.1007/s12035-016-9879-1] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 03/21/2016] [Indexed: 12/15/2022]
Abstract
Dysfunction of iron metabolism, which includes its uptake, storage, and release, plays a key role in neurodegenerative disorders, including Parkinson's disease (PD), Alzheimer's disease, and Huntington's disease. Understanding how iron accumulates in the substantia nigra (SN) and why it specifically targets dopaminergic (DAergic) neurons is particularly warranted for PD, as this knowledge may provide new therapeutic avenues for a more targeted neurotherapeutic strategy for this disease. In this review, we begin with a brief introduction describing brain iron metabolism and its regulation. We then provide a detailed description of how iron accumulates specifically in the SN and why DAergic neurons are especially vulnerable to iron in PD. Furthermore, we focus on the possible mechanisms involved in iron-induced cell death of DAergic neurons in the SN. Finally, we present evidence in support that iron chelation represents a plausable therapeutic strategy for PD.
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Affiliation(s)
- Hong Jiang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Medical College of Qingdao University, Qingdao, 266071, China.
| | - Jun Wang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Medical College of Qingdao University, Qingdao, 266071, China
| | - Jack Rogers
- Neurochemistry Laboratory, Division of Psychiatric Neurosciences and Genetics and Aging Research Unit, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Junxia Xie
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Medical College of Qingdao University, Qingdao, 266071, China.
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26
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Stugiewicz M, Tkaczyszyn M, Kasztura M, Banasiak W, Ponikowski P, Jankowska EA. The influence of iron deficiency on the functioning of skeletal muscles: experimental evidence and clinical implications. Eur J Heart Fail 2016; 18:762-73. [PMID: 26800032 DOI: 10.1002/ejhf.467] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/16/2015] [Accepted: 10/22/2015] [Indexed: 12/26/2022] Open
Abstract
Skeletal and respiratory myopathy not only constitutes an important pathophysiological feature of heart failure and chronic obstructive pulmonary disease, but also contributes to debilitating symptomatology and predicts worse outcomes in these patients. Accumulated evidence from laboratory experiments, animal models, and interventional studies in sports medicine suggests that undisturbed systemic iron homeostasis significantly contributes to the effective functioning of skeletal muscles. In this review, we discuss the role of iron status for the functioning of skeletal muscle tissue, and highlight iron deficiency as an emerging therapeutic target in chronic diseases accompanied by a marked muscle dysfunction.
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Affiliation(s)
- Magdalena Stugiewicz
- Students' Scientific Association, Laboratory for Applied Research on Cardiovascular System, Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
| | - Michał Tkaczyszyn
- Laboratory for Applied Research on Cardiovascular System, Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland.,Cardiology Department, Centre for Heart Diseases, Military Hospital, Wroclaw, Poland
| | - Monika Kasztura
- Laboratory for Applied Research on Cardiovascular System, Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
| | - Waldemar Banasiak
- Cardiology Department, Centre for Heart Diseases, Military Hospital, Wroclaw, Poland
| | - Piotr Ponikowski
- Cardiology Department, Centre for Heart Diseases, Military Hospital, Wroclaw, Poland.,Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
| | - Ewa A Jankowska
- Laboratory for Applied Research on Cardiovascular System, Department of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland.,Cardiology Department, Centre for Heart Diseases, Military Hospital, Wroclaw, Poland
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27
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Castello A, Hentze MW, Preiss T. Metabolic Enzymes Enjoying New Partnerships as RNA-Binding Proteins. Trends Endocrinol Metab 2015; 26:746-757. [PMID: 26520658 PMCID: PMC4671484 DOI: 10.1016/j.tem.2015.09.012] [Citation(s) in RCA: 183] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/26/2015] [Accepted: 09/28/2015] [Indexed: 12/21/2022]
Abstract
In the past century, few areas of biology advanced as much as our understanding of the pathways of intermediary metabolism. Initially considered unimportant in terms of gene regulation, crucial cellular fate changes, cell differentiation, or malignant transformation are now known to involve 'metabolic remodeling' with profound changes in the expression of many metabolic enzyme genes. This review focuses on the recent identification of RNA-binding activity of numerous metabolic enzymes. We discuss possible roles of this unexpected second activity in feedback gene regulation ('moonlighting') and/or in the control of enzymatic function. We also consider how metabolism-driven post-translational modifications could regulate enzyme-RNA interactions. Thus, RNA emerges as a new partner of metabolic enzymes with far-reaching possible consequences to be unraveled in the future.
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Affiliation(s)
- Alfredo Castello
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Matthias W Hentze
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
| | - Thomas Preiss
- EMBL-Australia Collaborating Group, Department of Genome Sciences, The John Curtin School of Medical Research, The Australian National University, Acton (Canberra), ACT 2601, Australia; Victor Chang Cardiac Research Institute, Darlinghurst (Sydney), New South Wales 2010, Australia
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28
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Figueroa-Angulo EE, Calla-Choque JS, Mancilla-Olea MI, Arroyo R. RNA-Binding Proteins in Trichomonas vaginalis: Atypical Multifunctional Proteins. Biomolecules 2015; 5:3354-95. [PMID: 26703754 PMCID: PMC4693282 DOI: 10.3390/biom5043354] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/07/2015] [Accepted: 11/12/2015] [Indexed: 01/08/2023] Open
Abstract
Iron homeostasis is highly regulated in vertebrates through a regulatory system mediated by RNA-protein interactions between the iron regulatory proteins (IRPs) that interact with an iron responsive element (IRE) located in certain mRNAs, dubbed the IRE-IRP regulatory system. Trichomonas vaginalis, the causal agent of trichomoniasis, presents high iron dependency to regulate its growth, metabolism, and virulence properties. Although T. vaginalis lacks IRPs or proteins with aconitase activity, possesses gene expression mechanisms of iron regulation at the transcriptional and posttranscriptional levels. However, only one gene with iron regulation at the transcriptional level has been described. Recently, our research group described an iron posttranscriptional regulatory mechanism in the T. vaginalis tvcp4 and tvcp12 cysteine proteinase mRNAs. The tvcp4 and tvcp12 mRNAs have a stem-loop structure in the 5'-coding region or in the 3'-UTR, respectively that interacts with T. vaginalis multifunctional proteins HSP70, α-Actinin, and Actin under iron starvation condition, causing translation inhibition or mRNA stabilization similar to the previously characterized IRE-IRP system in eukaryotes. Herein, we summarize recent progress and shed some light on atypical RNA-binding proteins that may participate in the iron posttranscriptional regulation in T. vaginalis.
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Affiliation(s)
- Elisa E Figueroa-Angulo
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Av. IPN # 2508, Col. San Pedro Zacatenco, CP 07360 México, D.F., Mexico.
| | - Jaeson S Calla-Choque
- Laboratorio de Inmunopatología en Neurocisticercosis, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, Urb. Ingeniería, S.M.P., Lima 15102, Peru.
| | - Maria Inocente Mancilla-Olea
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Av. IPN # 2508, Col. San Pedro Zacatenco, CP 07360 México, D.F., Mexico.
| | - Rossana Arroyo
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Av. IPN # 2508, Col. San Pedro Zacatenco, CP 07360 México, D.F., Mexico.
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29
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Abstract
Cellular iron homeostasis is regulated by post-transcriptional feedback mechanisms, which control the expression of proteins involved in iron uptake, release and storage. Two cytoplasmic proteins with mRNA-binding properties, iron regulatory proteins 1 and 2 (IRP1 and IRP2) play a central role in this regulation. Foremost, IRPs regulate ferritin H and ferritin L translation and thus iron storage, as well as transferrin receptor 1 (TfR1) mRNA stability, thereby adjusting receptor expression and iron uptake via receptor-mediated endocytosis of iron-loaded transferrin. In addition splice variants of iron transporters for import and export at the plasma-membrane, divalent metal transporter 1 (DMT1) and ferroportin are regulated by IRPs. These mechanisms have probably evolved to maintain the cytoplasmic labile iron pool (LIP) at an appropriate level. In certain tissues, the regulation exerted by IRPs influences iron homeostasis and utilization of the entire organism. In intestine, the control of ferritin expression limits intestinal iron absorption and, thus, whole body iron levels. In bone marrow, erythroid heme biosynthesis is coordinated with iron availability through IRP-mediated translational control of erythroid 5-aminolevulinate synthase mRNA. Moreover, the translational control of HIF2α mRNA in kidney by IRP1 coordinates erythropoietin synthesis with iron and oxygen supply. Besides IRPs, body iron absorption is negatively regulated by hepcidin. This peptide hormone, synthesized and secreted by the liver in response to high serum iron, downregulates ferroportin at the protein level and thereby limits iron absorption from the diet. Hepcidin will not be discussed in further detail here.
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Affiliation(s)
- Lukas C Kühn
- Ecole Polytechnique Fédérale de Lausanne (EPFL), ISREC - Swiss Institute for Experimental Cancer Research, EPFL_SV_ISREC, Room SV2516, Station 19, CH-1015 Lausanne, Switzerland.
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30
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Sands SA, Tsau S, LeVine SM. The habenula and iron metabolism in cerebral mouse models of multiple sclerosis. Neurosci Lett 2015; 606:204-8. [PMID: 26362814 DOI: 10.1016/j.neulet.2015.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 09/03/2015] [Accepted: 09/04/2015] [Indexed: 12/25/2022]
Abstract
Iron accumulates in the CNS of patients with multiple sclerosis, but our understanding of the mechanism accounting for this accumulation is unclear. Mouse models of cerebral experimental autoimmune encephalomyelitis (EAE) in C57BL/6 and SJL mice were used together with a histochemical stain for iron and immunohistochemical stains for transferrin receptor, synaptophysin, iron regulatory protein 1 (IRP1) and/or IRP2 to investigate the role of disease activity on CNS iron metabolism. The expression of transferrin receptor, but not IRP1 or IRP2, increased in the medial habenula, which is adjacent to the third ventricle, in response to both types of cerebral EAE. In the habenula, the elevated expression of transferrin receptor in C57BL/6 mice with cerebral EAE was generally restricted to the medial habenula while the expression in SJL mice with cerebral EAE was more diffusely expressed. Iron levels were increased in all regions of the habenula in C57BL/6 mice with cerebral EAE, and in the medial and medial lateral but not the lateral habenula in SJL mice with cerebral EAE. Synaptophysin, which has been observed previously in endocytic vesicles together with the transferrin receptor, was concentrated at the medial habenula, but its levels did not increase with disease in C57BL/6 mice with cerebral EAE. Our results support the model that the medial habenula responds to disease activity by upregulating transferrin receptor to facilitate the movement of iron into the brain from the third ventricle, raising the possibility that a similar mechanism accounts for iron accumulation in deep gray matter structures in patients with multiple sclerosis.
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Affiliation(s)
- Scott A Sands
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Sheila Tsau
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Steven M LeVine
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
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31
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Bresgen N, Eckl PM. Oxidative stress and the homeodynamics of iron metabolism. Biomolecules 2015; 5:808-47. [PMID: 25970586 PMCID: PMC4496698 DOI: 10.3390/biom5020808] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 04/21/2015] [Accepted: 04/22/2015] [Indexed: 12/12/2022] Open
Abstract
Iron and oxygen share a delicate partnership since both are indispensable for survival, but if the partnership becomes inadequate, this may rapidly terminate life. Virtually all cell components are directly or indirectly affected by cellular iron metabolism, which represents a complex, redox-based machinery that is controlled by, and essential to, metabolic requirements. Under conditions of increased oxidative stress—i.e., enhanced formation of reactive oxygen species (ROS)—however, this machinery may turn into a potential threat, the continued requirement for iron promoting adverse reactions such as the iron/H2O2-based formation of hydroxyl radicals, which exacerbate the initial pro-oxidant condition. This review will discuss the multifaceted homeodynamics of cellular iron management under normal conditions as well as in the context of oxidative stress.
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Affiliation(s)
- Nikolaus Bresgen
- Department of Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria.
| | - Peter M Eckl
- Department of Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria.
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32
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Abstract
Moonlighting proteins serve one or more novel functions in addition to their canonical roles. Moonlighting functions arise when an adventitious interaction between a protein and a new partner improves fitness of the organism. Selective pressure for improvement in the new function can result in two alternative outcomes. The gene encoding the newly bifunctional protein may duplicate and diverge so as to encode two proteins, each of which serves only one function. Alternatively, genetic changes that minimize adaptive conflict between the two functions and/or improve control over the time and place at which each function is served can lead to a moonlighting protein. Importantly, genetic changes that enhance a moonlighting function can occur in the gene encoding the moonlighting protein itself, in a gene that affects the structure of its new partner or in a gene encoding a transcription factor that controls expression of either partner. The evolutionary history of each moonlighting protein is complex, depending on the stochastic occurrence of genetic changes such as gene duplication and point mutations, and the effects of those changes on fitness. Population effects, particularly loss of promising individuals due to random genetic drift, also play a role in the emergence of a moonlighting protein. The ultimate outcome is not necessarily the 'optimal' solution to the problem of serving two functions, but may be 'good enough' so that fitness becomes limited by some other function.
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Affiliation(s)
- Shelley D Copley
- *Department of Molecular, Cellular and Developmental Biology and Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80027, U.S.A
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33
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Procházková P, Škanta F, Roubalová R, Šilerová M, Dvořák J, Bilej M. Involvement of the iron regulatory protein from Eisenia andrei earthworms in the regulation of cellular iron homeostasis. PLoS One 2014; 9:e109900. [PMID: 25279857 PMCID: PMC4184891 DOI: 10.1371/journal.pone.0109900] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/07/2014] [Indexed: 01/07/2023] Open
Abstract
Iron homeostasis in cells is regulated by iron regulatory proteins (IRPs) that exist in different organisms. IRPs are cytosolic proteins that bind to iron-responsive elements (IREs) of the 5′- or 3′-untranslated regions (UTR) of mRNAs that encode many proteins involved in iron metabolism. In this study, we have cloned and described a new regulatory protein belonging to the family of IRPs from the earthworm Eisenia andrei (EaIRP). The earthworm IRE site in 5′-UTR of ferritin mRNA most likely folds into a secondary structure that differs from the conventional IRE structures of ferritin due to the absence of a typically unpaired cytosine that participates in protein binding. Prepared recombinant EaIRP and proteins from mammalian liver extracts are able to bind both mammalian and Eisenia IRE structures of ferritin mRNA, although the affinity of the rEaIRP/Eisenia IRE structure is rather low. This result suggests the possible contribution of a conventional IRE structure. When IRP is supplemented with a Fe-S cluster, it can function as a cytosolic aconitase. Cellular cytosolic and mitochondrial fractions, as well as recombinant EaIRP, exhibit aconitase activity that can be abolished by the action of oxygen radicals. The highest expression of EaIRP was detected in parts of the digestive tract. We can assume that earthworms may possess an IRE/IRP regulatory network as a potential mechanism for maintaining cellular iron homeostasis, although the aconitase function of EaIRP is most likely more relevant.
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Affiliation(s)
- Petra Procházková
- Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic
- * E-mail:
| | - František Škanta
- Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic
| | - Radka Roubalová
- Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic
| | - Marcela Šilerová
- Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic
| | - Jiří Dvořák
- Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic
| | - Martin Bilej
- Laboratory of Cellular and Molecular Immunology, Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Prague 4, Czech Republic
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34
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Zumbrennen-Bullough KB, Becker L, Garrett L, Hölter SM, Calzada-Wack J, Mossbrugger I, Quintanilla-Fend L, Racz I, Rathkolb B, Klopstock T, Wurst W, Zimmer A, Wolf E, Fuchs H, Gailus-Durner V, de Angelis MH, Romney SJ, Leibold EA. Abnormal brain iron metabolism in Irp2 deficient mice is associated with mild neurological and behavioral impairments. PLoS One 2014; 9:e98072. [PMID: 24896637 PMCID: PMC4045679 DOI: 10.1371/journal.pone.0098072] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 04/27/2014] [Indexed: 01/13/2023] Open
Abstract
Iron Regulatory Protein 2 (Irp2, Ireb2) is a central regulator of cellular iron homeostasis in vertebrates. Two global knockout mouse models have been generated to explore the role of Irp2 in regulating iron metabolism. While both mouse models show that loss of Irp2 results in microcytic anemia and altered body iron distribution, discrepant results have drawn into question the role of Irp2 in regulating brain iron metabolism. One model shows that aged Irp2 deficient mice develop adult-onset progressive neurodegeneration that is associated with axonal degeneration and loss of Purkinje cells in the central nervous system. These mice show iron deposition in white matter tracts and oligodendrocyte soma throughout the brain. A contrasting model of global Irp2 deficiency shows no overt or pathological signs of neurodegeneration or brain iron accumulation, and display only mild motor coordination and balance deficits when challenged by specific tests. Explanations for conflicting findings in the severity of the clinical phenotype, brain iron accumulation and neuronal degeneration remain unclear. Here, we describe an additional mouse model of global Irp2 deficiency. Our aged Irp2−/− mice show marked iron deposition in white matter and in oligodendrocytes while iron content is significantly reduced in neurons. Ferritin and transferrin receptor 1 (TfR1, Tfrc), expression are increased and decreased, respectively, in the brain from Irp2−/− mice. These mice show impairments in locomotion, exploration, motor coordination/balance and nociception when assessed by neurological and behavioral tests, but lack overt signs of neurodegenerative disease. Ultrastructural studies of specific brain regions show no evidence of neurodegeneration. Our data suggest that Irp2 deficiency dysregulates brain iron metabolism causing cellular dysfunction that ultimately leads to mild neurological, behavioral and nociceptive impairments.
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Affiliation(s)
- Kimberly B. Zumbrennen-Bullough
- Program in Anemia Signaling Research, Division of Nephrology, Program in Membrane Biology, Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Lore Becker
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Experimental Genetics, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Lillian Garrett
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Development Genetics, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Sabine M. Hölter
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Development Genetics, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Julia Calzada-Wack
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Pathology, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Ilona Mossbrugger
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Pathology, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Leticia Quintanilla-Fend
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Pathology, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Ildiko Racz
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Molecular Psychiatry, Life & Brain Center, University of Bonn, Bonn, Germany
| | - Birgit Rathkolb
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universitat, Munich, Germany
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institute, Klinikum der Ludwig-Maximilians-Universitat, Munich, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen, Munich, Germany
- Munich Cluster for Systems Neurology, Munich, Germany
| | - Wolfgang Wurst
- Institute of Development Genetics, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Chair of Developmental Genetics, Technische Universitat München, Freising-Weihenstephan, Germany
- Max Planck Institute of Psychiatry, Munich, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen, Munich, Germany
- Munich Cluster for Systems Neurology, Munich, Germany
| | - Andreas Zimmer
- Institute of Molecular Psychiatry, Life & Brain Center, University of Bonn, Bonn, Germany
| | - Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universitat, Munich, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Experimental Genetics, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Experimental Genetics, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Martin Hrabě de Angelis
- German Mouse Clinic, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Experimental Genetics, Helmholtz-Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Chair of Experimental Genetics, Center of Life and Food Sciences Weihenstephan, Technische Universitat München, Freising, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Steven J. Romney
- University of Utah, Department of Medicine, Division of Hematology and Hematological Malignancies, Salt Lake City, Utah, United States of America
| | - Elizabeth A. Leibold
- University of Utah, Department of Medicine, Division of Hematology and Hematological Malignancies, Salt Lake City, Utah, United States of America
- * E-mail:
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Khan MA, Ma J, Walden WE, Merrick WC, Theil EC, Goss DJ. Rapid kinetics of iron responsive element (IRE) RNA/iron regulatory protein 1 and IRE-RNA/eIF4F complexes respond differently to metal ions. Nucleic Acids Res 2014; 42:6567-77. [PMID: 24728987 PMCID: PMC4041422 DOI: 10.1093/nar/gku248] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Metal ion binding was previously shown to destabilize IRE-RNA/IRP1 equilibria and enhanced IRE-RNA/eIF4F equilibria. In order to understand the relative importance of kinetics and stability, we now report rapid rates of protein/RNA complex assembly and dissociation for two IRE-RNAs with IRP1, and quantitatively different metal ion response kinetics that coincide with the different iron responses in vivo. kon, for FRT IRE-RNA binding to IRP1 was eight times faster than ACO2 IRE-RNA. Mn2+ decreased kon and increased koff for IRP1 binding to both FRT and ACO2 IRE-RNA, with a larger effect for FRT IRE-RNA. In order to further understand IRE-mRNA regulation in terms of kinetics and stability, eIF4F kinetics with FRT IRE-RNA were determined. kon for eIF4F binding to FRT IRE-RNA in the absence of metal ions was 5-times slower than the IRP1 binding to FRT IRE-RNA. Mn2+ increased the association rate for eIF4F binding to FRT IRE-RNA, so that at 50 µM Mn2+ eIF4F bound more than 3-times faster than IRP1. IRP1/IRE-RNA complex has a much shorter life-time than the eIF4F/IRE-RNA complex, which suggests that both rate of assembly and stability of the complexes are important, and that allows this regulatory system to respond rapidly to change in cellular iron.
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Affiliation(s)
- Mateen A Khan
- Department of Chemistry and Biochemistry, Hunter College, City University of New York, New York, NY 10065, USA
| | - Jia Ma
- Department of Chemistry and Biochemistry, Hunter College, City University of New York, New York, NY 10065, USA
| | - William E Walden
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL 60612-7334, USA
| | - William C Merrick
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Elizabeth C Theil
- Childeren's Hospital Oakland Research Institute, Oakland, CA 94609, USA
| | - Dixie J Goss
- Department of Chemistry and Biochemistry, Hunter College, City University of New York, New York, NY 10065, USA
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Guan P, Wang N. Mammalian target of rapamycin coordinates iron metabolism with iron-sulfur cluster assembly enzyme and tristetraprolin. Nutrition 2014; 30:968-74. [PMID: 24976419 DOI: 10.1016/j.nut.2013.12.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 12/13/2013] [Accepted: 12/15/2013] [Indexed: 01/07/2023]
Abstract
Both iron deficiency and excess are relatively common health concerns. Maintaining the body's levels of iron within precise boundaries is critical for cell functions. However, the difference between iron deficiency and overload is often a question of a scant few milligrams of iron. The mammalian target of rapamycin (mTOR), an atypical Ser/Thr protein kinase, is attracting significant amounts of interest due to its recently described role in iron homeostasis. Despite extensive study, a complete understanding of mTOR function has remained elusive. mTOR can form two multiprotein complexes that consist of mTOR complex 1 (mTORC1) and mTOR complex 2. Recent advances clearly demonstrate that mTORC1 can phosphorylate iron-sulfur cluster assembly enzyme ISCU and affect iron-sulfur clusters assembly. Moreover, mTOR is reported to control iron metabolism through modulation of tristetraprolin expression. It is now well appreciated that the hormonal hepcidin-ferroportin system and the cellular iron-responsive element/iron-regulatory protein regulatory network play important regulatory roles for systemic iron metabolism. Sustained ISCU protein levels enhanced by mTORC1 can inhibit iron-responsive element and iron-regulatory protein binding activities. In this study, hepcidin gene and protein expression in the livers of tristetraprolin knockout mice were dramatically reduced. Here, we highlight and summarize the current understanding of how mTOR pathways serve to modulate iron metabolism and homeostasis as the third iron-regulatory system.
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Affiliation(s)
- Peng Guan
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, Hebei Normal University, Hebei Province, China
| | - Na Wang
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, Hebei Normal University, Hebei Province, China; School of Basic Medical Sciences, Hebei University of Traditional Chinese Medicine, Hebei Province, China.
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Influence of microRNA on the maintenance of human iron metabolism. Nutrients 2013; 5:2611-28. [PMID: 23846788 PMCID: PMC3738991 DOI: 10.3390/nu5072611] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 06/19/2013] [Accepted: 06/24/2013] [Indexed: 12/21/2022] Open
Abstract
Iron is an essential nutrient critical for many cellular functions including DNA synthesis, ATP generation, and cellular proliferation. Though essential, excessive iron may contribute to the generation of free radicals capable of damaging cellular lipids, proteins, and nucleic acids. As such, the maintenance and control of cellular iron homeostasis is critical to prevent either iron deficiency or iron toxicity conditions. The maintenance of cellular iron homeostasis is largely coordinated by a family of cytosolic RNA binding proteins known as Iron Regulatory Proteins (IRP) that function to post-transcriptionally control the translation and/or stability of mRNA encoding proteins required for iron uptake, storage, transport, and utilization. More recently, a class of small non-coding RNA known as microRNA (miRNA) has also been implicated in the control of iron metabolism. To date, miRNA have been demonstrated to post-transcriptionally regulate the expression of genes associated with iron acquisition (transferrin receptor and divalent metal transporter), iron export (ferroportin), iron storage (ferritin), iron utilization (ISCU), and coordination of systemic iron homeostasis (HFE and hemojevelin). Given the diversity of miRNA and number of potential mRNA targets, characterizing factors that contribute to alterations in miRNA expression, biogenesis, and processing will enhance our understanding of mechanisms by which cells respond to changes in iron demand and/or iron availability to control cellular iron homeostasis.
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Freeman AAH, Mandilaras K, Missirlis F, Sanyal S. An emerging role for Cullin-3 mediated ubiquitination in sleep and circadian rhythm: insights from Drosophila. Fly (Austin) 2013; 7:39-43. [PMID: 23455037 DOI: 10.4161/fly.23506] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Although the neurophysiological correlates of sleep have been thoroughly described, genetic mechanisms that control sleep architecture, long surmised from ethological studies, family histories and clinical observations, have only been investigated during the past decade. Key contributions to the molecular understanding of sleep have come from studies in Drosophila, benefitting from a strong history of circadian rhythm research. For instance, a number of recent papers have highlighted the role of the E3 ubiquitin ligase Cullin-3 in the regulation of circadian rhythm and sleep. We propose that different Cullin-3 substrate adaptors may affect specific molecular pathways and diverse aspects of circadian rhythm and sleep. We have previously shown that mutations in BTBD9, a risk factor for Restless Legs Syndrome (RLS) encoding a Cullin-3 substrate adaptor, lead to reduced dopamine, increased locomotion and sleep fragmentation. Here, we propose that Cullin-3 acts together with BTBD9 to limit the accumulation of iron regulatory proteins in conditions of iron deficiency. Our model is consistent with clinical observations implicating iron homeostasis in the pathophysiology of RLS and predicts that lack of BTBD9 leads to misregulation of cellular iron storage, inactivating the critical biosynthetic enzyme Tyrosine Hydroxylase in dopaminergic neurons, with consequent phenotypic effects on sleep.
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Affiliation(s)
- Amanda A H Freeman
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA.
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Abstract
ABSTRACT Iron is an essential transition metal for mammalian cellular and tissue viability. It is critical to supplying oxygen through heme, the mitochondrial respiratory chain, and enzymes such as ribonucleotide reductase. Mammalian organisms have evolved with the means of regulating the metabolism of iron, because if left unregulated, the resulting excess amounts of iron may induce chronic toxicities affecting multiple organ systems. Several homeostatic mechanisms exist to control the amount of intestinal dietary iron uptake, cellular iron uptake, distribution, and export. Within these processes, numerous molecular participants have been identified because of advancements in basic cell biology and efforts in disease-based research of iron storage abnormalities. For example, dietary iron uptake across the intestinal duodenal mucosa is mediated by an intramembrane divalent metal transporter 1 (DMT1), and cellular iron efflux involves ferroportin, the only known iron exporter. In addition to duodenal enterocytes, ferroportin is present in other cell types, and exports iron into plasma. Ferroportin was recently discovered to be regulated by the expression of the circulating hormone hepcidin, a small peptide synthesized in hepatocytes. These recent studies on the role of hepcidin in the regulation of dietary, cellular, and extracellular iron have led to a better understanding of the pathways by which iron balance in humans is influenced, especially its involvement in human genetic diseases of iron overload. Other important molecular pathways include iron binding to transferrin in the bloodstream for cellular delivery through the plasma membrane transferrin receptor (TfR1). In the cytosol, iron regulatory proteins 1 and 2 (IRP1 and IRP2) play a prominent role in sensing the presence of iron in order to posttranscriptionally regulate the expression of TfR1 and ferritin, two important participants in iron metabolism. From a toxicological standpoint, posttranscriptional regulation of these genes aids in the sequestration, control, and hence prevention of cytotoxic effects from free-floating nontransferrin-bound iron. Given the importance of dietary iron in normal physiology, its potential to induce chronic toxicity, and recent discoveries in the regulation of human iron metabolism by hepcidin, this review will address the regulatory mechanisms of normal iron metabolism in mammals with emphasis on dietary exposure. It is the goal of this review that this information may provide in a concise format our current understanding of major pathways and mechanisms involved in mammalian iron metabolism, which is a basis for control of iron toxicity. Such a discussion is intended to facilitate the identification of deficiencies so that future metabolic or toxicological studies may be appropriately focused. A better knowledge of iron metabolism from normal to pathophysiological conditions will ultimately broaden the spectrum of the usefulness of this information in biomedical and toxicological sciences for improving and protecting human health.
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Affiliation(s)
- Luis G Valerio
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition,Office of Food Additive Safety, Division of Biotechnology and GRAS Notice Review, College Park, MD, 20470, USA
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40
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Anderson CP, Shen M, Eisenstein RS, Leibold EA. Mammalian iron metabolism and its control by iron regulatory proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1468-83. [PMID: 22610083 DOI: 10.1016/j.bbamcr.2012.05.010] [Citation(s) in RCA: 346] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 05/07/2012] [Accepted: 05/11/2012] [Indexed: 02/06/2023]
Abstract
Cellular iron homeostasis is maintained by iron regulatory proteins 1 and 2 (IRP1 and IRP2). IRPs bind to iron-responsive elements (IREs) located in the untranslated regions of mRNAs encoding protein involved in iron uptake, storage, utilization and export. Over the past decade, significant progress has been made in understanding how IRPs are regulated by iron-dependent and iron-independent mechanisms and the pathological consequences of IRP2 deficiency in mice. The identification of novel IREs involved in diverse cellular pathways has revealed that the IRP-IRE network extends to processes other than iron homeostasis. A mechanistic understanding of IRP regulation will likely yield important insights into the basis of disorders of iron metabolism. This article is part of a Special Issue entitled: Cell Biology of Metals.
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Affiliation(s)
- Cole P Anderson
- Department of Oncological Sciences, University of Utah, 15 N. 2030 E., Salt Lake City, UT 84112, USA
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41
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Siddique A, Kowdley KV. Review article: the iron overload syndromes. Aliment Pharmacol Ther 2012; 35:876-93. [PMID: 22385471 DOI: 10.1111/j.1365-2036.2012.05051.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 06/26/2011] [Accepted: 02/08/2012] [Indexed: 12/12/2022]
Abstract
BACKGROUND Iron overload syndromes encompass a wide range of hereditary and acquired conditions. Major developments in the field of genetics and the discovery of hepcidin as a central regulator of iron homeostasis have greatly increased our understanding of the pathophysiology of iron overload syndromes. AIM To review advances in iron regulation and iron overload syndrome with special emphasis on hereditary haemochromatosis, the prototype iron overload syndrome. METHODS A PubMed search using words such as 'iron overload', 'hemochromatosis', 'HFE', 'Non-HFE', 'secondary iron overload' was undertaken. RESULTS Iron overload is associated with significant morbidity and mortality. Sensitive diagnostic tests and effective therapy are widely available and can prevent complications associated with iron accumulation in end- organs. Therapeutic phlebotomy remains the cornerstone of therapy for removal of excess body iron, but novel therapeutic agents including oral iron chelators have been developed for iron overload associated with anaemia. CONCLUSIONS Iron overload disorders are common. Inexpensive screening tests as well as confirmatory diagnostic tests are widely available. Increased awareness of the causes and importance of early diagnosis and knowledge of the appropriate use of genetic testing are encouraged. The availability of novel treatments should increase therapeutic options for patients with iron overload disorders.
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Affiliation(s)
- A Siddique
- Department of Hepatology, Virginia Mason Medical Center, Seattle, WA, USA.
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42
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Thompson JW, Bruick RK. Protein degradation and iron homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1484-90. [PMID: 22349011 DOI: 10.1016/j.bbamcr.2012.02.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 02/01/2012] [Accepted: 02/03/2012] [Indexed: 12/21/2022]
Abstract
Regulation of both systemic and cellular iron homeostasis requires the capacity to sense iron levels and appropriately modify the expression of iron metabolism genes. These responses are coordinated through the efforts of several key regulatory factors including F-box and Leucine-rich Repeat Protein 5 (FBXL5), Iron Regulatory Proteins (IRPs), Hypoxia Inducible Factor (HIF), and ferroportin. Notably, the stability of each of these proteins is regulated in response to iron. Recent discoveries have greatly advanced our understanding of the molecular mechanisms governing iron-sensing and protein degradation within these pathways. It has become clear that iron's privileged roles in both enzyme catalysis and protein structure contribute to its regulation of protein stability. Moreover, these multiple pathways intersect with one another in larger regulatory networks to maintain iron homeostasis. This article is part of a Special Issue entitled: Cell Biology of Metals.
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Affiliation(s)
- Joel W Thompson
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390, USA
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Walden WE, Selezneva A, Volz K. Accommodating variety in iron-responsive elements: Crystal structure of transferrin receptor 1 B IRE bound to iron regulatory protein 1. FEBS Lett 2011; 586:32-5. [PMID: 22119729 DOI: 10.1016/j.febslet.2011.11.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 11/14/2011] [Accepted: 11/15/2011] [Indexed: 12/27/2022]
Abstract
Iron responsive elements (IREs) are short stem-loop structures found in several mRNAs encoding proteins involved in cellular iron metabolism. Iron regulatory proteins (IRPs) control iron homeostasis through differential binding to the IREs, accommodating any sequence or structural variations that the IREs may present. Here we report the structure of IRP1 in complex with transferrin receptor 1 B (TfR B) IRE, and compare it to the complex with ferritin H (Ftn H) IRE. The two IREs are bound to IRP1 through nearly identical protein-RNA contacts, although their stem conformations are significantly different. These results support the view that binding of different IREs with IRP1 depends both on protein and RNA conformational plasticity, adapting to RNA variation while retaining conserved protein-RNA contacts.
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Affiliation(s)
- William E Walden
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL 60612, USA
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44
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Ohno T, Hashimoto N, Mitsui K, Nishimura H, Hagiwara H. Iron overload inhibits calcification and differentiation of ATDC5 cells. J Biochem 2011; 151:109-14. [DOI: 10.1093/jb/mvr124] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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45
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Abstract
Manganese superoxide dismutase (MnSOD) is a nuclear encoded and mitochondrial matrix localized redox enzyme that is known to regulate cellular redox environment. Cellular redox environment changes during transitions between quiescent and proliferative cycles. Human MnSOD has two poly(A) sites resulting in two transcripts: 1.5 and 4.2 kb. The present study investigates if the 3'-untranslated region (UTR) of MnSOD regulates its expression during transitions between quiescent and proliferating cycles, and in response to radiation. A preferential increase in the 1.5 kb MnSOD transcript levels was observed in quiescent cells, while the abundance of the longer transcript showed a direct correlation with the percentage of S-phase cells. Log transformed expression ratio of the longer to shorter transcript was also higher in proliferating normal and cancer cells. Deletion and reporter assays showed a significant decrease in reporter activity in constructs carrying multiple AU-rich sequence that are present in the 3'-UTR of the longer MnSOD transcript. Overexpression of the MnSOD 3'-UTR representing the longer transcript enhanced endogenous MnSOD mRNA levels, which was associated with an increase in MnSOD protein levels and a decrease in the percentage of S-phase cells. Irradiation increases the mRNA levels of the 1.5 kb MnSOD transcript, which was consistent with a significant increase in reporter activity of the construct carrying the 3'-UTR of the shorter transcript. We conclude that the 3'-UTR of MnSOD regulates MnSOD expression in response to different growth states and radiation.
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46
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Procházková P, Dvořák J, Šilerová M, Roubalová R, Škanta F, Halada P, Bilej M. Molecular characterization of the iron binding protein ferritin in Eisenia andrei earthworms. Gene 2011; 485:73-80. [PMID: 21723382 DOI: 10.1016/j.gene.2011.06.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 06/02/2011] [Accepted: 06/07/2011] [Indexed: 10/18/2022]
Abstract
Ferritin is a storage protein that plays a key role in iron metabolism. In this study, we report on the sequence characterization of a ferritin-coding cDNA in Eisenia andrei earthworms isolated by RT-PCR using degenerated primers, and we suggest the presence of a putative IRE in the 5'-UTR of ferritin mRNA. The obtained ferritin sequence was compared with those of other animals showing sequence and structure homology in consensus sites, including the iron-responsive element (IRE) and ferroxidase centers. Despite the sequence homology in the E. andrei mRNA of ferritin with the sequences of other animals in consensus IRE sites, the presented cytosine in the IRE of E. andrei ferritin in the expected position does not form a conventional bulge. The presence of ferritin in the coelomic fluid of E. andrei was proven by iron staining assay. Moreover, aconitase activity in the coelomic fluid was assessed by aconitase assay, suggesting the presence of an iron regulatory protein. Quantitative analysis revealed changes in the gene expression levels of ferritin in coelomocytes in response to bacterial challenge, reaching the maximum level 8h after the stimulation with both Gram-positive and Gram-negative bacteria.
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Affiliation(s)
- Petra Procházková
- Institute of Microbiology of the Academy of Sciences of the Czech Republic, v. v. i., Videnska 1083, 142 20 Prague 4, Czech Republic.
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Chang AHK, Jeong J, Levine RL. Iron regulatory protein 2 turnover through a nonproteasomal pathway. J Biol Chem 2011; 286:23698-707. [PMID: 21558272 DOI: 10.1074/jbc.m110.216788] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Iron regulatory protein 2 (IRP2) controls the synthesis of many proteins involved in iron metabolism, and the level of IRP2 itself is regulated by varying the rate of its degradation. The proteasome is known to mediate degradation, with specificity conferred by an iron-sensing E3 ligase. Most studies on the degradation of IRP2 have employed cells overexpressing IRP2 and also rendered iron deficient to further increase IRP2 levels. We utilized a sensitive, quantitative assay for IRP2, which allowed study of endogenous IRP2 degradation in HEK293A cells under more physiologic conditions. We found that under these conditions, the proteasome plays only a minor role in the degradation of IRP2, with almost all the IRP2 being degraded by a nonproteasomal pathway. This new pathway is calcium-dependent but is not mediated by calpain. Elevating the cellular level of IRP2 by inducing iron deficiency or by transfection causes the proteasomal pathway to account for the major fraction of IRP2 degradation. We conclude that under physiological, iron-sufficient conditions, the steady-state level of IRP2 in HEK293A cells is regulated by the nonproteasomal pathway.
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Affiliation(s)
- Allen H K Chang
- Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892-8012, USA
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Regulation of neuronal ferritin heavy chain, a new player in opiate-induced chemokine dysfunction. J Neuroimmune Pharmacol 2011; 6:466-76. [PMID: 21465240 DOI: 10.1007/s11481-011-9278-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 03/21/2011] [Indexed: 12/19/2022]
Abstract
The heavy chain subunit of ferritin (FHC), a ubiquitous protein best known for its iron-sequestering activity as part of the ferritin complex, has recently been described as a novel inhibitor of signaling through the chemokine receptor CXCR4. Levels of FHC as well as its effects on CXCR4 activation increase in cortical neurons exposed to mu-opioid receptor agonists such as morphine, an effect likely specific to neurons. Major actions of CXCR4 signaling in the mature brain include a promotion of neurogenesis, activation of pro-survival signals, and modulation of excitotoxic pathways; thus, FHC up-regulation may contribute to the neuronal dysfunction often associated with opiate drug abuse. This review summarizes our knowledge of neuronal CXCR4 function, its regulation by opiates and the role of FHC in this process, and known mechanisms controlling FHC production. We speculate on the mechanism involved in FHC regulation by opiates and offer FHC as a new target in opioid-induced neuropathology.
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Benjamin JAM, Desnoyers G, Morissette A, Salvail H, Massé E. Dealing with oxidative stress and iron starvation in microorganisms: an overview. Can J Physiol Pharmacol 2011; 88:264-72. [PMID: 20393591 DOI: 10.1139/y10-014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Iron starvation and oxidative stress are 2 hurdles that bacteria must overcome to establish an infection. Pathogenic bacteria have developed many strategies to efficiently infect a broad range of hosts, including humans. The best characterized systems make use of regulatory proteins to sense the environment and adapt accordingly. For example, iron-sulfur clusters are critical for sensing the level and redox state of intracellular iron. The regulatory small RNA (sRNA) RyhB has recently been shown to play a central role in adaptation to iron starvation, while the sRNA OxyS coordinates cellular response to oxidative stress. These regulatory sRNAs are well conserved in many bacteria and have been shown to be essential for establishing a successful infection. An overview of the different strategies used by bacteria to cope with iron starvation and oxidative stress is presented here.
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Affiliation(s)
- Julie-Anna M Benjamin
- Department of Biochemistry, RNA Group, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
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50
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Gille G, Reichmann H. Iron-dependent functions of mitochondria--relation to neurodegeneration. J Neural Transm (Vienna) 2010; 118:349-59. [PMID: 21161302 DOI: 10.1007/s00702-010-0503-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 10/05/2010] [Indexed: 11/25/2022]
Abstract
A number of neurodegenerative diseases are associated with iron dyshomeostasis and mitochondrial dysfunction. However, the pathomechanistic interplay between iron and mitochondria varies. This review summarises the physiological role of iron in mitochondria and subsequently exemplifies two neurodegenerative diseases with disturbed iron function in mitochondria: inherited Friedreich ataxia (FRDA) and idiopathic Parkinson disease (PD). In eukaryotes, mitochondria are main consumers of iron. The respiratory chain relies on iron-containing redox systems in the form of complexes I-III with iron-sulphur clusters and cytochromes with haem as prosthetic groups. The bifunctional enzyme aconitase is not only important in the citric acid cycle, but also functions as a key regulator of cell iron metabolism. Haem biosynthesis occurs partially in mitochondria as well as the biogenesis of iron-sulphur clusters that are co-factors in numerous iron-sulphur proteins. FRDA is characterised by a mutation of the frataxin gene, the protein of which serves as an iron chaperone in iron-sulphur cluster assembly. The lack of frataxin expression leads to defective iron-sulphur cluster biogenesis with decreased respiratory and aconitase activity. The resulting mitochondrial iron overload might fuel reactive oxygen species formation and contribute to clinical signs of oxidative stress. PD is typically associated with an increased iron content of the substantia nigra, the causes of which are largely unknown. Recent research demonstrated raised iron levels in individual dopaminergic neurons of the substantia nigra. Moreover, transferrin/transferrin receptor 2 mediated transport of iron into the mitochondria of these neurons was identified together with increased transferrin immunoreactivity. Resulting accumulation of iron into mitochondria might lead to oxidative stress damaging iron-sulphur cluster-containing proteins.
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Affiliation(s)
- Gabriele Gille
- Klinik und Poliklinik für Neurologie, TU Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
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