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Fernandez S, Wofford JD, Shepherd RE, Vali SW, Dancis A, Lindahl PA. Yeast cells depleted of the frataxin homolog Yfh1 redistribute cellular iron: Studies using Mössbauer spectroscopy and mathematical modeling. J Biol Chem 2022; 298:101921. [PMID: 35413285 PMCID: PMC9130540 DOI: 10.1016/j.jbc.2022.101921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 11/27/2022] Open
Abstract
The neurodegenerative disease Friedreich's ataxia arises from a deficiency of frataxin, a protein that promotes iron-sulfur cluster (ISC) assembly in mitochondria. Here, primarily using Mössbauer spectroscopy, we investigated the iron content of a yeast strain in which expression of yeast frataxin homolog 1 (Yfh1), oxygenation conditions, iron concentrations, and metabolic modes were varied. We found that aerobic fermenting Yfh1-depleted cells grew slowly and accumulated FeIII nanoparticles, unlike WT cells. Under hypoxic conditions, the same mutant cells grew at rates similar to WT cells, had similar iron content, and were dominated by FeII rather than FeIII nanoparticles. Furthermore, mitochondria from mutant hypoxic cells contained approximately the same levels of ISCs as WT cells, confirming that Yfh1 is not required for ISC assembly. These cells also did not accumulate excessive iron, indicating that iron accumulation into yfh1-deficient mitochondria is stimulated by O2. In addition, in aerobic WT cells, we found that vacuoles stored FeIII, whereas under hypoxic fermenting conditions, vacuolar iron was reduced to FeII. Under respiring conditions, vacuoles of Yfh1-deficient cells contained FeIII, and nanoparticles accumulated only under aerobic conditions. Taken together, these results informed a mathematical model of iron trafficking and regulation in cells that could semiquantitatively simulate the Yfh1-deficiency phenotype. Simulations suggested partially independent regulation in which cellular iron import is regulated by ISC activity in mitochondria, mitochondrial iron import is regulated by a mitochondrial FeII pool, and vacuolar iron import is regulated by cytosolic FeII and mitochondrial ISC activity.
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Affiliation(s)
- Salvador Fernandez
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | - Joshua D Wofford
- Department of Chemistry, College of Science and Mathematics, Charleston Southern University, Charleston South Carolina, USA
| | - Rachel E Shepherd
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | - Shaik Waseem Vali
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Andrew Dancis
- Department of Medicine, Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Paul A Lindahl
- Department of Chemistry, Texas A&M University, College Station, Texas, USA; Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.
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2
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Morante S, Botticelli S, Chiaraluce R, Consalvi V, La Penna G, Novak L, Pasquo A, Petrosino M, Proux O, Rossi G, Salina G, Stellato F. Metal Ion Binding in Wild-Type and Mutated Frataxin: A Stability Study. Front Mol Biosci 2022; 9:878017. [PMID: 35712353 PMCID: PMC9195147 DOI: 10.3389/fmolb.2022.878017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/12/2022] [Indexed: 11/13/2022] Open
Abstract
This work studies the stability of wild-type frataxin and some of its variants found in cancer tissues upon Co2+ binding. Although the physiologically involved metal ion in the frataxin enzymatic activity is Fe2+, as it is customarily done, Co2+ is most often used in experiments because Fe2+ is extremely unstable owing to the fast oxidation reaction Fe2+ → Fe3+. Protein stability is monitored following the conformational changes induced by Co2+ binding as measured by circular dichroism, fluorescence spectroscopy, and melting temperature measurements. The stability ranking among the wild-type frataxin and its variants obtained in this way is confirmed by a detailed comparative analysis of the XAS spectra of the metal-protein complex at the Co K-edge. In particular, a fit to the EXAFS region of the spectrum allows positively identifying the frataxin acidic ridge as the most likely location of the metal-binding sites. Furthermore, we can explain the surprising feature emerging from a detailed analysis of the XANES region of the spectrum, showing that the longer 81-210 frataxin fragment has a smaller propensity for Co2+ binding than the shorter 90-210 one. This fact is explained by the peculiar role of the N-terminal disordered tail in modulating the protein ability to interact with the metal.
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Affiliation(s)
- S. Morante
- Dipartimento di Fisica, Universitá di Roma Tor Vergata, Rome, Italy
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
- *Correspondence: S. Morante ,
| | - S. Botticelli
- Dipartimento di Fisica, Universitá di Roma Tor Vergata, Rome, Italy
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
| | - R. Chiaraluce
- Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, Sapienza Universitá di Roma, Rome, Italy
| | - V. Consalvi
- Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, Sapienza Universitá di Roma, Rome, Italy
| | - G. La Penna
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
- CNR—Istituto di Chimica dei Composti Organometallici, Firenze, Italy
| | - L. Novak
- Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, Sapienza Universitá di Roma, Rome, Italy
| | - A. Pasquo
- ENEA CR Frascati, Diagnostics and Metrology Laboratory FSN-TECFIS-DIM, Frascati, Italy
| | - M. Petrosino
- Chair of Pharmacology, Section of Medicine, University of Fribourg, Fribourg, Switzerland
| | - O. Proux
- Observatoire des Sciences de L’Univers de Grenoble, UAR 832 CNRS, Université Grenoble Alpes, Grenoble, France
| | - G. Rossi
- Dipartimento di Fisica, Universitá di Roma Tor Vergata, Rome, Italy
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
- Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Roma, Italy
| | - G. Salina
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
| | - F. Stellato
- Dipartimento di Fisica, Universitá di Roma Tor Vergata, Rome, Italy
- INFN, Sezione di Roma Tor Vergata, Rome, Italy
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3
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Frataxins Emerge as New Players of the Intracellular Antioxidant Machinery. Antioxidants (Basel) 2021; 10:antiox10020315. [PMID: 33672495 PMCID: PMC7923443 DOI: 10.3390/antiox10020315] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 12/30/2022] Open
Abstract
Frataxin is a mitochondrial protein which deficiency causes Friedreich's ataxia, a cardio-neurodegenerative disease. The lack of frataxin induces the dysregulation of mitochondrial iron homeostasis and oxidative stress, which finally causes the neuronal death. The mechanism through which frataxin regulates the oxidative stress balance is rather complex and poorly understood. While the absence of human (Hfra) and yeast (Yfh1) frataxins turn out cells sensitive to oxidative stress, this does not occur when the frataxin gene is knocked-out in E. coli. To better understand the biological roles of Hfra and Yfh1 as endogenous antioxidants, we have studied their ability to inhibit the formation of reactive oxygen species (ROS) from Cu2+- and Fe3+-catalyzed degradation of ascorbic acid. Both proteins drastically reduce the formation of ROS, and during this process they are not oxidized. In addition, we have also demonstrated that merely the presence of Yfh1 or Hfra is enough to protect a highly oxidation-prone protein such as α-synuclein. This unspecific intervention (without a direct binding) suggests that frataxins could act as a shield to prevent the oxidation of a broad set of intracellular proteins, and reinforces that idea that frataxin can be used to prevent neurological pathologies linked to an enhanced oxidative stress.
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Smith FM, Kosman DJ. Molecular Defects in Friedreich's Ataxia: Convergence of Oxidative Stress and Cytoskeletal Abnormalities. Front Mol Biosci 2020; 7:569293. [PMID: 33263002 PMCID: PMC7686857 DOI: 10.3389/fmolb.2020.569293] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/10/2020] [Indexed: 01/18/2023] Open
Abstract
Friedreich’s ataxia (FRDA) is a multi-faceted disease characterized by progressive sensory–motor loss, neurodegeneration, brain iron accumulation, and eventual death by hypertrophic cardiomyopathy. FRDA follows loss of frataxin (FXN), a mitochondrial chaperone protein required for incorporation of iron into iron–sulfur cluster and heme precursors. After the discovery of the molecular basis of FRDA in 1996, over two decades of research have been dedicated to understanding the temporal manifestations of disease both at the whole body and molecular level. Early research indicated strong cellular iron dysregulation in both human and yeast models followed by onset of oxidative stress. Since then, the pathophysiology due to dysregulation of intracellular iron chaperoning has become central in FRDA relative to antioxidant defense and run-down in energy metabolism. At the same time, limited consideration has been given to changes in cytoskeletal organization, which was one of the first molecular defects noted. These alterations include both post-translational oxidative glutathionylation of actin monomers and differential DNA processing of a cytoskeletal regulator PIP5K1β. Currently unknown in respect to FRDA but well understood in the context of FXN-deficient cell physiology is the resulting impact on the cytoskeleton; this disassembly of actin filaments has a particularly profound effect on cell–cell junctions characteristic of barrier cells. With respect to a neurodegenerative disorder such as FRDA, this cytoskeletal and tight junction breakdown in the brain microvascular endothelial cells of the blood–brain barrier is likely a component of disease etiology. This review serves to outline a brief history of this research and hones in on pathway dysregulation downstream of iron-related pathology in FRDA related to actin dynamics. The review presented here was not written with the intent of being exhaustive, but to instead urge the reader to consider the essentiality of the cytoskeleton and appreciate the limited knowledge on FRDA-related cytoskeletal dysfunction as a result of oxidative stress. The review examines previous hypotheses of neurodegeneration with brain iron accumulation (NBIA) in FRDA with a specific biochemical focus.
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Affiliation(s)
- Frances M Smith
- Department of Biochemistry, State University of New York at Buffalo, Buffalo, NY, United States
| | - Daniel J Kosman
- Department of Biochemistry, State University of New York at Buffalo, Buffalo, NY, United States
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Li Y, Lou W, Grevel A, Böttinger L, Liang Z, Ji J, Patil VA, Liu J, Ye C, Hüttemann M, Becker T, Greenberg ML. Cardiolipin-deficient cells have decreased levels of the iron-sulfur biogenesis protein frataxin. J Biol Chem 2020; 295:11928-11937. [PMID: 32636300 PMCID: PMC7450130 DOI: 10.1074/jbc.ra120.013960] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 07/02/2020] [Indexed: 12/12/2022] Open
Abstract
Cardiolipin (CL) is the signature phospholipid of mitochondrial membranes, where it is synthesized locally and plays an important role in mitochondrial bioenergetics. Previous studies in the yeast model have indicated that CL is required for optimal iron homeostasis, which is disrupted by a mechanism not yet determined in the yeast CL mutant, crd1Δ. This finding has implications for the severe genetic disorder, Barth syndrome (BTHS), in which CL metabolism is perturbed because of mutations in the CL-remodeling enzyme, tafazzin. Here, we investigate the effects of tafazzin deficiency on iron homeostasis in the mouse myoblast model of BTHS tafazzin knockout (TAZ-KO) cells. Similarly to CL-deficient yeast cells, TAZ-KO cells exhibited elevated sensitivity to iron, as well as to H2O2, which was alleviated by the iron chelator deferoxamine. TAZ-KO cells exhibited increased expression of the iron exporter ferroportin and decreased expression of the iron importer transferrin receptor, likely reflecting a regulatory response to elevated mitochondrial iron. Reduced activities of mitochondrial iron-sulfur cluster enzymes suggested that the mechanism underlying perturbation of iron homeostasis was defective iron-sulfur biogenesis. We observed decreased levels of Yfh1/frataxin, an essential component of the iron-sulfur biogenesis machinery, in mitochondria from TAZ-KO mouse cells and in CL-deleted yeast crd1Δ cells, indicating that the role of CL in iron-sulfur biogenesis is highly conserved. Yeast crd1Δ cells exhibited decreased processing of the Yfh1 precursor upon import, which likely contributes to the iron homeostasis defects. Implications for understanding the pathogenesis of BTHS are discussed.
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Affiliation(s)
- Yiran Li
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Wenjia Lou
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Alexander Grevel
- Institute for Biochemistry and Molecular Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Lena Böttinger
- Institute for Biochemistry and Molecular Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Zhuqing Liang
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Jiajia Ji
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Vinay A Patil
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Jenney Liu
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Cunqi Ye
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Maik Hüttemann
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Thomas Becker
- Institute for Biochemistry and Molecular Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- CIBSS Centre for Integrative Biological Signaling Studies, University of Freiburg, Freiburg, Germany
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
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Castro IH, Pignataro MF, Sewell KE, Espeche LD, Herrera MG, Noguera ME, Dain L, Nadra AD, Aran M, Smal C, Gallo M, Santos J. Frataxin Structure and Function. Subcell Biochem 2019; 93:393-438. [PMID: 31939159 DOI: 10.1007/978-3-030-28151-9_13] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mammalian frataxin is a small mitochondrial protein involved in iron sulfur cluster assembly. Frataxin deficiency causes the neurodegenerative disease Friedreich's Ataxia. Valuable knowledge has been gained on the structural dynamics of frataxin, metal-ion-protein interactions, as well as on the effect of mutations on protein conformation, stability and internal motions. Additionally, laborious studies concerning the enzymatic reactions involved have allowed for understanding the capability of frataxin to modulate Fe-S cluster assembly function. Remarkably, frataxin biological function depends on its interaction with some proteins to form a supercomplex, among them NFS1 desulfurase and ISCU, the scaffolding protein. By combining multiple experimental tools including high resolution techniques like NMR and X-ray, but also SAXS, crosslinking and mass-spectrometry, it was possible to build a reliable model of the structure of the desulfurase supercomplex NFS1/ACP-ISD11/ISCU/frataxin. In this chapter, we explore these issues showing how the scientific view concerning frataxin structure-function relationships has evolved over the last years.
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Affiliation(s)
- Ignacio Hugo Castro
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
| | - María Florencia Pignataro
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
| | - Karl Ellioth Sewell
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
| | - Lucía Daniela Espeche
- Departamento de Diagnóstico Genético, Centro Nacional de Genética Médica "Dr. Eduardo E. Castilla"-A.N.L.I.S, Av. Las Heras 2670, C1425ASQ, C.A.B.A, Argentina
| | - María Georgina Herrera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
| | - Martín Ezequiel Noguera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, B1876BXD, Bernal, Provincia de Buenos Aires, Argentina
| | - Liliana Dain
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Departamento de Diagnóstico Genético, Centro Nacional de Genética Médica "Dr. Eduardo E. Castilla"-A.N.L.I.S, Av. Las Heras 2670, C1425ASQ, C.A.B.A, Argentina
| | - Alejandro Daniel Nadra
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Martín Aran
- Fundación Instituto Leloir E IIBBA-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
| | - Clara Smal
- Fundación Instituto Leloir E IIBBA-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
| | - Mariana Gallo
- IRBM Science Park S.p.A, Via Pontina km 30,600, 00071, Pomezia, RM, Italy
| | - Javier Santos
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina.
- Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD, C.A.B.A, Argentina.
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Pontieri P, Hartings H, Di Salvo M, Massardo DR, De Stefano M, Pizzolante G, Romano R, Troisi J, Del Giudice A, Alifano P, Del Giudice L. Mitochondrial ribosomal proteins involved in tellurite resistance in yeast Saccharomyces cerevisiae. Sci Rep 2018; 8:12022. [PMID: 30104660 PMCID: PMC6089990 DOI: 10.1038/s41598-018-30479-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 07/23/2018] [Indexed: 11/22/2022] Open
Abstract
A considerable body of evidence links together mitochondrial dysfunctions, toxic action of metalloid oxyanions, and system and neurodegenerative disorders. In this study we have used the model yeast Saccharomyces cerevisiae to investigate the genetic determinants associated with tellurite resistance/sensitivity. Nitrosoguanidine-induced K2TeO3-resistant mutants were isolated, and one of these mutants, named Sc57-Te5R, was characterized. Both random spore analysis and tetrad analysis and growth of heterozygous (TeS/Te5R) diploid from Sc57-Te5R mutant revealed that nuclear and recessive mutation(s) was responsible for the resistance. To get insight into the mechanisms responsible for K2TeO3-resistance, RNA microarray analyses were performed with K2TeO3-treated and untreated Sc57-Te5R cells. A total of 372 differentially expressed loci were identified corresponding to 6.37% of the S. cerevisiae transcriptome. Of these, 288 transcripts were up-regulated upon K2TeO3 treatment. About half of up-regulated transcripts were associated with the following molecular functions: oxidoreductase activity, structural constituent of cell wall, transporter activity. Comparative whole-genome sequencing allowed us to identify nucleotide variants distinguishing Sc57-Te5R from parental strain Sc57. We detected 15 CDS-inactivating mutations, and found that 3 of them affected genes coding mitochondrial ribosomal proteins (MRPL44 and NAM9) and mitochondrial ribosomal biogenesis (GEP3) pointing out to alteration of mitochondrial ribosome as main determinant of tellurite resistance.
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Affiliation(s)
- Paola Pontieri
- Istituto di Bioscienze e BioRisorse-UOS Portici-CNR c/o Dipartimento di Biologia, Sezione di Igiene, Via Mezzocannone 16, Napoli, 80134, Italy
| | - Hans Hartings
- Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Via Stezzano 24, Bergamo, 24126, Italy
| | - Marco Di Salvo
- Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, Università del Salento, Lecce, 73100, Italy
| | - Domenica R Massardo
- Istituto di Bioscienze e BioRisorse-UOS Portici-CNR c/o Dipartimento di Biologia, Sezione di Igiene, Via Mezzocannone 16, Napoli, 80134, Italy
| | - Mario De Stefano
- Dipartimento di Scienze Ambientali, Seconda Università degli Studi di Napoli, Via A. Vivaldi 43, Caserta, 81100, Italy
| | - Graziano Pizzolante
- ZooPlantLab, Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Piazza della Scienza 2, Milano, 20126, Italy
| | - Roberta Romano
- Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali (DICAM), Università di Bologna, Via Terracini 28, Bologna, 40131, Italy
| | - Jacopo Troisi
- Theoreo srl - Spin off dell' Università di Salerno, Via Salvatore Derenzi 50, Montecorvino Pugliano, 84125, (SA), Italy
| | - Angelica Del Giudice
- Amb di allergologia Osp Martini asl città di Torino, via Tofane 71, Torino, 10171, Italy
| | - Pietro Alifano
- Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, Università del Salento, Lecce, 73100, Italy
| | - Luigi Del Giudice
- Istituto di Bioscienze e BioRisorse-UOS Portici-CNR c/o Dipartimento di Biologia, Sezione di Igiene, Via Mezzocannone 16, Napoli, 80134, Italy.
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8
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Chiang S, Kalinowski DS, Jansson PJ, Richardson DR, Huang MLH. Mitochondrial dysfunction in the neuro-degenerative and cardio-degenerative disease, Friedreich's ataxia. Neurochem Int 2018; 117:35-48. [PMID: 28782591 DOI: 10.1016/j.neuint.2017.08.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 07/25/2017] [Accepted: 08/03/2017] [Indexed: 01/09/2023]
Abstract
Mitochondrial homeostasis is essential for maintaining healthy cellular function and survival. The detrimental involvement of mitochondrial dysfunction in neuro-degenerative diseases has recently been highlighted in human conditions, such as Parkinson's, Alzheimer's and Huntington's disease. Friedreich's ataxia (FA) is another neuro-degenerative, but also cardio-degenerative condition, where mitochondrial dysfunction plays a crucial role in disease progression. Deficient expression of the mitochondrial protein, frataxin, is the primary cause of FA, which leads to adverse alterations in whole cell and mitochondrial iron metabolism. Dys-regulation of iron metabolism in these compartments, results in the accumulation of inorganic iron deposits in the mitochondrial matrix that is thought to potentiate oxidative damage observed in FA. Therefore, the maintenance of mitochondrial homeostasis is crucial in the progression of neuro-degenerative conditions, particularly in FA. In this review, vital mitochondrial homeostatic processes and their roles in FA pathogenesis will be discussed. These include mitochondrial iron processing, mitochondrial dynamics (fusion and fission processes), mitophagy, mitochondrial biogenesis, mitochondrial energy production and calcium metabolism.
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Affiliation(s)
- Shannon Chiang
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Danuta S Kalinowski
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Patric J Jansson
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Des R Richardson
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia.
| | - Michael L-H Huang
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia.
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9
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Chiang S, Kovacevic Z, Sahni S, Lane DJR, Merlot AM, Kalinowski DS, Huang MLH, Richardson DR. Frataxin and the molecular mechanism of mitochondrial iron-loading in Friedreich's ataxia. Clin Sci (Lond) 2016; 130:853-70. [PMID: 27129098 DOI: 10.1042/cs20160072] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/16/2016] [Indexed: 12/19/2022]
Abstract
The mitochondrion is a major site for the metabolism of the transition metal, iron, which is necessary for metabolic processes critical for cell vitality. The enigmatic mitochondrial protein, frataxin, is known to play a significant role in both cellular and mitochondrial iron metabolism due to its iron-binding properties and its involvement in iron-sulfur cluster (ISC) and heme synthesis. The inherited neuro- and cardio-degenerative disease, Friedreich's ataxia (FA), is caused by the deficient expression of frataxin that leads to deleterious alterations in iron metabolism. These changes lead to the accumulation of inorganic iron aggregates in the mitochondrial matrix that are presumed to play a key role in the oxidative damage and subsequent degenerative features of this disease. Furthermore, the concurrent dys-regulation of cellular antioxidant defense, which coincides with frataxin deficiency, exacerbates oxidative stress. Hence, the pathogenesis of FA underscores the importance of the integrated homeostasis of cellular iron metabolism and the cytoplasmic and mitochondrial redox environments. This review focuses on describing the pathogenesis of the disease, the molecular mechanisms involved in mitochondrial iron-loading and the dys-regulation of cellular antioxidant defense due to frataxin deficiency. In turn, current and emerging therapeutic strategies are also discussed.
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Affiliation(s)
- Shannon Chiang
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Zaklina Kovacevic
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Sumit Sahni
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Darius J R Lane
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Angelica M Merlot
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Danuta S Kalinowski
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Michael L-H Huang
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia )
| | - Des R Richardson
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia )
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10
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Friedrich T, Dekovic DK, Burschel S. Assembly of the Escherichia coli NADH:ubiquinone oxidoreductase (respiratory complex I). BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:214-23. [PMID: 26682761 DOI: 10.1016/j.bbabio.2015.12.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 12/03/2015] [Accepted: 12/07/2015] [Indexed: 12/13/2022]
Abstract
Energy-converting NADH:ubiquinone oxidoreductase, respiratory complex I, couples the electron transfer from NADH to ubiquinone with the translocation of four protons across the membrane. The Escherichia coli complex I is made up of 13 different subunits encoded by the so-called nuo-genes. The electron transfer is catalyzed by nine cofactors, a flavin mononucleotide and eight iron-sulfur (Fe/S)-clusters. The individual subunits and the cofactors have to be assembled together in a coordinated way to guarantee the biogenesis of the active holoenzyme. Only little is known about the assembly of the bacterial complex compared to the mitochondrial one. Due to the presence of so many Fe/S-clusters the assembly of complex I is intimately connected with the systems responsible for the biogenesis of these clusters. In addition, a few other proteins have been reported to be required for an effective assembly of the complex in other bacteria. The proposed role of known bacterial assembly factors is discussed and the information from other bacterial species is used in this review to draw an as complete as possible model of bacterial complex I assembly. In addition, the supramolecular organization of the complex in E. coli is briefly described. This article is part of a Special Issue entitled Organization and dynamics of bioenergetic systems in bacteria, edited by Prof. Conrad Mullineaux.
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Affiliation(s)
- Thorsten Friedrich
- Albert-Ludwigs-Universität Freiburg, Institut für Biochemie, 79104 Freiburg i. Br., Germany; Spemann Graduate School of Biology and Medicine, Albertstr. 19A, 79104 Freiburg i. Br., Germany.
| | - Doris Kreuzer Dekovic
- Albert-Ludwigs-Universität Freiburg, Institut für Biochemie, 79104 Freiburg i. Br., Germany; Spemann Graduate School of Biology and Medicine, Albertstr. 19A, 79104 Freiburg i. Br., Germany
| | - Sabrina Burschel
- Albert-Ludwigs-Universität Freiburg, Institut für Biochemie, 79104 Freiburg i. Br., Germany
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11
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Roche B, Agrebi R, Huguenot A, Ollagnier de Choudens S, Barras F, Py B. Turning Escherichia coli into a Frataxin-Dependent Organism. PLoS Genet 2015; 11:e1005134. [PMID: 25996492 PMCID: PMC4440780 DOI: 10.1371/journal.pgen.1005134] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 03/10/2015] [Indexed: 01/01/2023] Open
Abstract
Fe-S bound proteins are ubiquitous and contribute to most basic cellular processes. A defect in the ISC components catalyzing Fe-S cluster biogenesis leads to drastic phenotypes in both eukaryotes and prokaryotes. In this context, the Frataxin protein (FXN) stands out as an exception. In eukaryotes, a defect in FXN results in severe defects in Fe-S cluster biogenesis, and in humans, this is associated with Friedreich's ataxia, a neurodegenerative disease. In contrast, prokaryotes deficient in the FXN homolog CyaY are fully viable, despite the clear involvement of CyaY in ISC-catalyzed Fe-S cluster formation. The molecular basis of the differing importance in the contribution of FXN remains enigmatic. Here, we have demonstrated that a single mutation in the scaffold protein IscU rendered E. coli viability strictly dependent upon a functional CyaY. Remarkably, this mutation changed an Ile residue, conserved in prokaryotes at position 108, into a Met residue, conserved in eukaryotes. We found that in the double mutant IscUIM ΔcyaY, the ISC pathway was completely abolished, becoming equivalent to the ΔiscU deletion strain and recapitulating the drastic phenotype caused by FXN deletion in eukaryotes. Biochemical analyses of the "eukaryotic-like" IscUIM scaffold revealed that it exhibited a reduced capacity to form Fe-S clusters. Finally, bioinformatic studies of prokaryotic IscU proteins allowed us to trace back the source of FXN-dependency as it occurs in present-day eukaryotes. We propose an evolutionary scenario in which the current mitochondrial Isu proteins originated from the IscUIM version present in the ancestor of the Rickettsiae. Subsequent acquisition of SUF, the second Fe-S cluster biogenesis system, in bacteria, was accompanied by diminished contribution of CyaY in prokaryotic Fe-S cluster biogenesis, and increased tolerance to change in the amino acid present at the 108th position of the scaffold.
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Affiliation(s)
- Béatrice Roche
- Laboratoire de Chimie Bactérienne, UMR 7283, Aix-Marseille Université-CNRS, Institut de Microbiologie de la Méditerranée, Marseille, France
| | - Rym Agrebi
- De Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Allison Huguenot
- Laboratoire de Chimie Bactérienne, UMR 7283, Aix-Marseille Université-CNRS, Institut de Microbiologie de la Méditerranée, Marseille, France
| | | | - Frédéric Barras
- Laboratoire de Chimie Bactérienne, UMR 7283, Aix-Marseille Université-CNRS, Institut de Microbiologie de la Méditerranée, Marseille, France
| | - Béatrice Py
- Laboratoire de Chimie Bactérienne, UMR 7283, Aix-Marseille Université-CNRS, Institut de Microbiologie de la Méditerranée, Marseille, France
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12
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Roche B, Huguenot A, Barras F, Py B. The iron-binding CyaY and IscX proteins assist the ISC-catalyzed Fe-S biogenesis in Escherichia coli. Mol Microbiol 2015; 95:605-23. [PMID: 25430730 DOI: 10.1111/mmi.12888] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2014] [Indexed: 01/18/2023]
Abstract
In eukaryotes, frataxin deficiency (FXN) causes severe phenotypes including loss of iron-sulfur (Fe-S) cluster protein activity, accumulation of mitochondrial iron and leads to the neurodegenerative disease Friedreich's ataxia. In contrast, in prokaryotes, deficiency in the FXN homolog, CyaY, was reported not to cause any significant phenotype, questioning both its importance and its actual contribution to Fe-S cluster biogenesis. Because FXN is conserved between eukaryotes and prokaryotes, this surprising discrepancy prompted us to reinvestigate the role of CyaY in Escherichia coli. We report that CyaY (i) potentiates E. coli fitness, (ii) belongs to the ISC pathway catalyzing the maturation of Fe-S cluster-containing proteins and (iii) requires iron-rich conditions for its contribution to be significant. A genetic interaction was discovered between cyaY and iscX, the last gene of the isc operon. Deletion of both genes showed an additive effect on Fe-S cluster protein maturation, which led, among others, to increased resistance to aminoglycosides and increased sensitivity to lambda phage infection. Together, these in vivo results establish the importance of CyaY as a member of the ISC-mediated Fe-S cluster biogenesis pathway in E. coli, like it does in eukaryotes, and validate IscX as a new bona fide Fe-S cluster biogenesis factor.
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Affiliation(s)
- Béatrice Roche
- Laboratoire de Chimie Bactérienne, UMR 7283, Aix-Marseille Université-CNRS, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13009, Marseille, France
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13
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Isaya G. Mitochondrial iron-sulfur cluster dysfunction in neurodegenerative disease. Front Pharmacol 2014; 5:29. [PMID: 24624085 PMCID: PMC3939683 DOI: 10.3389/fphar.2014.00029] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 02/15/2014] [Indexed: 12/21/2022] Open
Abstract
Growing evidence supports a role for mitochondrial iron metabolism in the pathophysiology of neurodegenerative disorders such as Friedreich ataxia (FRDA) and Parkinson disease (PD) as well as in the motor and cognitive decline associated with the aging process. Iron-sulfur enzyme deficits and regional iron accumulation have been observed in each of these conditions. In spite of significant etiological, clinical and pathological differences that exist between FRDA and PD, it is possible that defects in mitochondrial iron-sulfur clusters (ISCs) biogenesis represent a common underlying mechanism leading to abnormal intracellular iron distribution with mitochondrial iron accumulation, oxidative phosphorylation deficits and oxidative stress in susceptible cells and specific regions of the nervous system. Moreover, a similar mechanism may contribute to the age-dependent iron accumulation that occurs in certain brain regions such as the globus pallidus and the substantia nigra. Targeting chelatable iron and reactive oxygen species appear as possible therapeutic options for FRDA and PD, and possibly other age-related neurodegenerative conditions. However, new technology to interrogate ISC synthesis in humans is needed to (i) assess how defects in this pathway contribute to the natural history of neurodegenerative disorders and (ii) develop treatments to correct those defects early in the disease process, before they cause irreversible neuronal cell damage.
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Affiliation(s)
- Grazia Isaya
- Department of Pediatric & Adolescent Medicine and Mayo Clinic Children's Center Mayo Clinic, Rochester, MN, USA
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14
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Pandey A, Gordon DM, Pain J, Stemmler TL, Dancis A, Pain D. Frataxin directly stimulates mitochondrial cysteine desulfurase by exposing substrate-binding sites, and a mutant Fe-S cluster scaffold protein with frataxin-bypassing ability acts similarly. J Biol Chem 2013; 288:36773-86. [PMID: 24217246 PMCID: PMC3873537 DOI: 10.1074/jbc.m113.525857] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 11/09/2013] [Indexed: 01/17/2023] Open
Abstract
For iron-sulfur (Fe-S) cluster synthesis in mitochondria, the sulfur is derived from the amino acid cysteine by the cysteine desulfurase activity of Nfs1. The enzyme binds the substrate cysteine in the pyridoxal phosphate-containing site, and a persulfide is formed on the active site cysteine in a manner depending on the accessory protein Isd11. The persulfide is then transferred to the scaffold Isu, where it combines with iron to form the Fe-S cluster intermediate. Frataxin is implicated in the process, although it is unclear where and how, and deficiency causes Friedreich ataxia. Using purified proteins and isolated mitochondria, we show here that the yeast frataxin homolog (Yfh1) directly and specifically stimulates cysteine binding to Nfs1 by exposing substrate-binding sites. This novel function of frataxin does not require iron, Isu1, or Isd11. Once bound to Nfs1, the substrate cysteine is the source of the Nfs1 persulfide, but this step is independent of frataxin and strictly dependent on Isd11. Recently, a point mutation in Isu1 was found to bypass many frataxin functions. The data presented here show that the Isu1 suppressor mimics the frataxin effects on Nfs1, explaining the bypassing activity. We propose a regulatory mechanism for the Nfs1 persulfide-forming activity. Specifically, at least two separate conformational changes must occur in the enzyme for optimum activity as follows: one is mediated by frataxin interaction that exposes the "buried" substrate-binding sites, and the other is mediated by Isd11 interaction that brings the bound substrate cysteine and the active site cysteine in proximity for persulfide formation.
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Affiliation(s)
- Alok Pandey
- From the Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers University, Newark, New Jersey 07101
| | - Donna M. Gordon
- From the Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers University, Newark, New Jersey 07101
| | - Jayashree Pain
- From the Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers University, Newark, New Jersey 07101
| | - Timothy L. Stemmler
- the Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201, and
| | - Andrew Dancis
- the Department of Medicine, Division of Hematology-Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Debkumar Pain
- From the Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers University, Newark, New Jersey 07101
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15
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Jain A, Connolly EL. Mitochondrial iron transport and homeostasis in plants. FRONTIERS IN PLANT SCIENCE 2013; 4:348. [PMID: 24046773 PMCID: PMC3764374 DOI: 10.3389/fpls.2013.00348] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 08/18/2013] [Indexed: 05/20/2023]
Abstract
Iron (Fe) is an essential nutrient for plants and although the mechanisms controlling iron uptake from the soil are relatively well understood, comparatively little is known about subcellular trafficking of iron in plant cells. Mitochondria represent a significant iron sink within cells, as iron is required for the proper functioning of respiratory chain protein complexes. Mitochondria are a site of Fe-S cluster synthesis, and possibly heme synthesis as well. Here we review recent insights into the molecular mechanisms controlling mitochondrial iron transport and homeostasis. We focus on the recent identification of a mitochondrial iron uptake transporter in rice and a possible role for metalloreductases in iron uptake by mitochondria. In addition, we highlight recent advances in mitochondrial iron homeostasis with an emphasis on the roles of frataxin and ferritin in iron trafficking and storage within mitochondria.
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Affiliation(s)
| | - Erin L. Connolly
- *Correspondence: Erin L. Connolly, University of South Carolina, 715 Sumter Street, Columbia, SC 29208, USA e-mail:
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16
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Mitochondrial DNA instability in cells lacking aconitase correlates with iron citrate toxicity. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2013; 2013:493536. [PMID: 24066190 PMCID: PMC3770056 DOI: 10.1155/2013/493536] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 07/12/2013] [Accepted: 07/24/2013] [Indexed: 02/06/2023]
Abstract
Aconitase, the second enzyme of the tricarboxylic acid cycle encoded by ACO1 in the budding yeast Saccharomyces cerevisiae, catalyzes the conversion of citrate to isocitrate. aco1Δ results in mitochondrial DNA (mtDNA) instability. It has been proposed that Aco1 binds to mtDNA and mediates its maintenance. Here we propose an alternative mechanism to account for mtDNA loss in aco1Δ mutant cells. We found that aco1Δ activated the RTG pathway, resulting in increased expression of genes encoding citrate synthase. By deleting RTG1, RTG3, or genes encoding citrate synthase, mtDNA instability was prevented in aco1Δ mutant cells. Increased activity of citrate synthase leads to iron accumulation in the mitochondria. Mutations in MRS3 and MRS4, encoding two mitochondrial iron transporters, also prevented mtDNA loss due to aco1Δ. Mitochondria are the main source of superoxide radicals, which are converted to H2O2 through two superoxide dismutases, Sod1 and Sod2. H2O2 in turn reacts with Fe2+ to generate very active hydroxyl radicals. We found that loss of Sod1, but not Sod2, prevents mtDNA loss in aco1Δ mutant cells. We propose that mtDNA loss in aco1Δ mutant cells is caused by the activation of the RTG pathway and subsequent iron citrate accumulation and toxicity.
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17
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González-Cabo P, Palau F. Mitochondrial pathophysiology in Friedreich's ataxia. J Neurochem 2013; 126 Suppl 1:53-64. [PMID: 23859341 DOI: 10.1111/jnc.12303] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/09/2013] [Accepted: 05/08/2013] [Indexed: 12/01/2022]
Abstract
Neurological examination indicates that Friedreich's ataxia corresponds to a mixed sensory and cerebellar ataxia, which affects the proprioceptive pathways. Neuropathology and pathophysiology of Friedreich's ataxia involves the peripheral sensory nerves, dorsal root ganglia, posterior columns, the spinocerebellar, and corticospinal tracts of the spinal cord, gracile and cuneate nuclei, dorsal nuclei of Clarke, and the dentate nucleus. Involvement of the myocardium and pancreatic islets of Langerhans indicates that it is also a systemic disease. The pathophysiology of the disease is the consequence of frataxin deficiency in the mitochondria and cells. Some of the biological consequences are currently recognized such as the effects on iron-sulfur cluster biogenesis or the oxidative status, but others deserve to be studied in depth. Among physiological aspects of mitochondria that have been associated with neurodegeneration and may be interesting to investigate in Friedreich's ataxia we can include mitochondrial dynamics and movement, communication with other organelles especially the endoplasmic reticulum, calcium homeostasis, apoptosis, and mitochondrial biogenesis and quality control. Changes in the mitochondrial physiology and transport in peripheral and central axons and mitochondrial metabolic functions such as bioenergetics and energy delivery in the synapses are also relevant functions to be considered. Thus, to understand the general pathophysiology of the disease and fundamental pathogenic mechanisms such as dying-back axonopathy, and determine molecular, cellular and tissue therapeutic targets, we need to discover the effect of frataxin depletion on mitochondrial properties and on specific cell susceptibility in the nervous system and other affected organs.
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Affiliation(s)
- Pilar González-Cabo
- Program in Rare and Genetic Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
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18
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Cotticelli MG, Crabbe AM, Wilson RB, Shchepinov MS. Insights into the role of oxidative stress in the pathology of Friedreich ataxia using peroxidation resistant polyunsaturated fatty acids. Redox Biol 2013; 1:398-404. [PMID: 25499576 PMCID: PMC4802835 DOI: 10.1016/j.redox.2013.06.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 06/19/2013] [Accepted: 06/20/2013] [Indexed: 12/22/2022] Open
Abstract
Friedreich ataxia is an autosomal recessive, inherited neuro- and cardio-degenerative disorder characterized by progressive ataxia of all four limbs, dysarthria, areflexia, sensory loss, skeletal deformities, and hypertrophic cardiomyopathy. Most disease alleles have a trinucleotide repeat expansion in the first intron of the FXN gene, which decreases expression of the encoded protein frataxin. Frataxin is involved in iron–sulfur-cluster (ISC) assembly in the mitochondrial matrix, and decreased frataxin is associated with ISC-enzyme and mitochondrial dysfunction, mitochondrial iron accumulation, and increased oxidative stress. To assess the role of oxidative stress in lipid peroxidation in Friedreich ataxia we used the novel approach of treating Friedreich ataxia cell models with polyunsaturated fatty acids (PUFAs) deuterated at bis-allylic sites. In ROS-driven oxidation of PUFAs, the rate-limiting step is hydrogen abstraction from a bis-allylic site; isotopic reinforcement (deuteration) of bis-allylic sites slows down their peroxidation. We show that linoleic and α-linolenic acids deuterated at the peroxidation-prone bis-allylic positions actively rescue oxidative-stress-challenged Friedreich ataxia cells. The protective effect of the deuterated PUFAs is additive in our models with the protective effect of the CoQ10 analog idebenone, which is thought to decrease the production of free radicals. Moreover, the administration of deuterated PUFAs resulted in decreased lipid peroxidation as measured by the fluorescence of the fatty acid analog C11-BODIPY (581/591) probe. Our results are consistent with a role for lipid peroxidation in Friedreich ataxia pathology, and suggest that the novel approach of oral delivery of isotope-reinforced PUFAs may have therapeutic potential in Friedreich ataxia and other disorders involving oxidative stress and lipid peroxidation. We test deuterated polyunsaturated fatty acids in cell models of Friedreich ataxia. Linoleic and α-linolenic acids exacerbate oxidative-stress toxicity in these cells. Deuterated linoleic and α-linolenic acids protect these cells from oxidative stress. Cell rescue correlates with decreased lipid peroxidation. Deuterated polyunsaturated fatty acids might be a therapeutic for Friedreich ataxia.
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Affiliation(s)
- M Grazia Cotticelli
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andrew M Crabbe
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Robert B Wilson
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA 19104, USA.
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19
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Vaubel RA, Isaya G. Iron-sulfur cluster synthesis, iron homeostasis and oxidative stress in Friedreich ataxia. Mol Cell Neurosci 2013; 55:50-61. [PMID: 22917739 PMCID: PMC3530001 DOI: 10.1016/j.mcn.2012.08.003] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 08/01/2012] [Accepted: 08/05/2012] [Indexed: 12/21/2022] Open
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive, multi-systemic degenerative disease that results from reduced synthesis of the mitochondrial protein frataxin. Frataxin has been intensely studied since its deficiency was linked to FRDA in 1996. The defining properties of frataxin - (i) the ability to bind iron, (ii) the ability to interact with, and donate iron to, other iron-binding proteins, and (iii) the ability to oligomerize, store iron and control iron redox chemistry - have been extensively characterized with different frataxin orthologs and their interacting protein partners. This very large body of biochemical and structural data [reviewed in (Bencze et al., 2006)] supports equally extensive biological evidence that frataxin is critical for mitochondrial iron metabolism and overall cellular iron homeostasis and antioxidant protection [reviewed in (Wilson, 2006)]. However, the precise biological role of frataxin remains a matter of debate. Here, we review seminal and recent data that strongly link frataxin to the synthesis of iron-sulfur cluster cofactors (ISC), as well as controversial data that nevertheless link frataxin to additional iron-related processes. Finally, we discuss how defects in ISC synthesis could be a major (although likely not unique) contributor to the pathophysiology of FRDA via (i) loss of ISC-dependent enzymes, (ii) mitochondrial and cellular iron dysregulation, and (iii) enhanced iron-mediated oxidative stress. This article is part of a Special Issue entitled 'Mitochondrial function and dysfunction in neurodegeneration'.
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Affiliation(s)
- Rachael A Vaubel
- Department of Pediatric & Adolescent Medicine and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, MN 55905, USA
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20
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Soriano S, Llorens JV, Blanco-Sobero L, Gutiérrez L, Calap-Quintana P, Morales MP, Moltó MD, Martínez-Sebastián MJ. Deferiprone and idebenone rescue frataxin depletion phenotypes in a Drosophila model of Friedreich's ataxia. Gene 2013; 521:274-81. [PMID: 23542074 DOI: 10.1016/j.gene.2013.02.049] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 02/22/2013] [Accepted: 02/25/2013] [Indexed: 11/17/2022]
Abstract
Friedreich's ataxia (FRDA), the most common inherited ataxia, is a neurodegenerative disease caused by a reduction in the levels of the mitochondrial protein frataxin, the function of which remains a controversial matter. Several therapeutic approaches are being developed to increase frataxin expression and reduce the intramitochondrial iron aggregates and oxidative damage found in this disease. In this study, we tested separately the response of a Drosophila RNAi model of FRDA (Llorens et al., 2007) to treatment with the iron chelator deferiprone (DFP) and the antioxidant idebenone (IDE), which are both in clinical trials. The FRDA flies have a shortened life span and impaired motor coordination, and these phenotypes are more pronounced in oxidative stress conditions. In addition, under hyperoxia, the activity of the mitochondrial enzyme aconitase is strongly reduced in the FRDA flies. This study reports that DFP and IDE improve the life span and motor ability of frataxin-depleted flies. We show that DFP eliminates the excess of labile iron in the mitochondria and thus prevents the toxicity induced by iron accumulation. IDE treatment rescues aconitase activity in hyperoxic conditions. These results validate the use of our Drosophila model of FRDA to screen for therapeutic molecules to treat this disease.
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Affiliation(s)
- Sirena Soriano
- Departament de Genètica, Universitat de València, Burjassot, Valencia, Spain
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21
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Li H, Gakh O, Smith DY, Ranatunga WK, Isaya G. Missense mutations linked to friedreich ataxia have different but synergistic effects on mitochondrial frataxin isoforms. J Biol Chem 2013; 288:4116-27. [PMID: 23269675 PMCID: PMC3567662 DOI: 10.1074/jbc.m112.435263] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 12/21/2012] [Indexed: 12/25/2022] Open
Abstract
Friedreich ataxia is an early-onset multisystemic disease linked to a variety of molecular defects in the nuclear gene FRDA. This gene normally encodes the iron-binding protein frataxin (FXN), which is critical for mitochondrial iron metabolism, global cellular iron homeostasis, and antioxidant protection. In most Friedreich ataxia patients, a large GAA-repeat expansion is present within the first intron of both FRDA alleles, that results in transcriptional silencing ultimately leading to insufficient levels of FXN protein in the mitochondrial matrix and probably other cellular compartments. The lack of FXN in turn impairs incorporation of iron into iron-sulfur cluster and heme cofactors, causing widespread enzymatic deficits and oxidative damage catalyzed by excess labile iron. In a minority of patients, a typical GAA expansion is present in only one FRDA allele, whereas a missense mutation is found in the other allele. Although it is known that the disease course for these patients can be as severe as for patients with two expanded FRDA alleles, the underlying pathophysiological mechanisms are not understood. Human cells normally contain two major mitochondrial isoforms of FXN (FXN(42-210) and FXN(81-210)) that have different biochemical properties and functional roles. Using cell-free systems and different cellular models, we show that two of the most clinically severe FXN point mutations, I154F and W155R, have unique direct and indirect effects on the stability, biogenesis, or catalytic activity of FXN(42-210) and FXN(81-210) under physiological conditions. Our data indicate that frataxin point mutations have complex biochemical effects that synergistically contribute to the pathophysiology of Friedreich ataxia.
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Affiliation(s)
- Hongqiao Li
- From the Department of Pediatric and Adolescent Medicine and the Department of Biochemistry and Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, Minnesota 55905
| | - Oleksandr Gakh
- From the Department of Pediatric and Adolescent Medicine and the Department of Biochemistry and Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, Minnesota 55905
| | - Douglas Y. Smith
- From the Department of Pediatric and Adolescent Medicine and the Department of Biochemistry and Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, Minnesota 55905
| | - Wasantha K. Ranatunga
- From the Department of Pediatric and Adolescent Medicine and the Department of Biochemistry and Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, Minnesota 55905
| | - Grazia Isaya
- From the Department of Pediatric and Adolescent Medicine and the Department of Biochemistry and Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, Minnesota 55905
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22
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Gabrielli N, Ayté J, Hidalgo E. Cells lacking pfh1, a fission yeast homolog of mammalian frataxin protein, display constitutive activation of the iron starvation response. J Biol Chem 2012; 287:43042-51. [PMID: 23115244 PMCID: PMC3522298 DOI: 10.1074/jbc.m112.421735] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 10/27/2012] [Indexed: 11/06/2022] Open
Abstract
Friedreich ataxia is a genetic disease caused by deficiencies in frataxin. This protein has homologs not only in higher eukaryotes but also in bacteria, fungi, and plants. The function of this protein is still controversial. We have identified a frataxin homolog in fission yeast, and we have analyzed whether its depletion leads to any of the phenotypes observed in other organisms. Cells deleted in pfh1 are sensitive to growth under aerobic conditions, display increased levels of total iron, hallmarks of oxidative stress such as protein carbonylation, decreased aconitase activity, and lower levels of oxygen consumption compared with wild-type cells. This mitochondrial protein seems to be important for iron and/or reactive oxygen species homeostasis. We have analyzed the proteome of cells devoid of Pfh1, and we determined that gene products up- and down-regulated upon iron depletion in wild-type cells are constitutively misregulated in this mutant. Because of the particular signaling pathway components governing the iron starvation response in fission yeast, our experiments suggest that cells lacking Pfh1 display a decrease of cytosolic available iron that triggers activation of Grx4, the common regulator of the iron starvation gene expression program. Our Schizosaccharomyces pombe Δpfh1 strain constitutes a new and useful model system to study Friedreich ataxia.
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Affiliation(s)
- Natalia Gabrielli
- From the Oxidative Stress and Cell Cycle Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003 Barcelona, Spain
| | - José Ayté
- From the Oxidative Stress and Cell Cycle Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Elena Hidalgo
- From the Oxidative Stress and Cell Cycle Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003 Barcelona, Spain
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23
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Patil VA, Fox JL, Gohil VM, Winge DR, Greenberg ML. Loss of cardiolipin leads to perturbation of mitochondrial and cellular iron homeostasis. J Biol Chem 2012. [PMID: 23192348 DOI: 10.1074/jbc.m112.428938] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Cardiolipin (CL) is the signature phospholipid of mitochondrial membranes, where it is synthesized locally and plays a critical role in mitochondrial bioenergetic functions. The importance of CL in human health is underscored by the observation that perturbation of CL biosynthesis causes the severe genetic disorder Barth syndrome. To fully understand the cellular response to the loss of CL, we carried out genome-wide expression profiling of the yeast CL mutant crd1Δ. Our results show that the loss of CL in this mutant leads to increased expression of iron uptake genes accompanied by elevated levels of mitochondrial iron and increased sensitivity to iron and hydrogen peroxide. Previous studies have shown that increased mitochondrial iron levels result from perturbations in iron-sulfur (Fe-S) cluster biogenesis. Consistent with an Fe-S defect, deletion of ISU1, one of two ISU genes that encode the mitochondrial Fe-S scaffolding protein essential for the synthesis of Fe-S clusters, led to synthetic growth defects with the crd1Δ mutant. We further show that crd1Δ cells have reduced activities of mitochondrial Fe-S enzymes (aconitase, succinate dehydrogenase, and ubiquinol-cytochrome c oxidoreductase), as well as cytosolic Fe-S enzymes (sulfite reductase and isopropylmalate isomerase). Increased expression of ATM1 or YAP1 did not rescue the Fe-S defects in crd1Δ. These findings show for the first time that CL is required for Fe-S biogenesis to maintain mitochondrial and cellular iron homeostasis.
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Affiliation(s)
- Vinay A Patil
- Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202, USA
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24
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Abstract
Friedreich ataxia is an inherited, severe, progressive neuro- and cardiodegenerative disorder for which there currently is no approved therapy. Friedreich ataxia is caused by the decreased expression and/or function of frataxin, a mitochondrial matrix protein that binds iron and is involved in the formation of iron-sulfur clusters. Decreased frataxin function leads to decreased iron-sulfur cluster formation, mitochondrial iron accumulation, cytosolic iron depletion, oxidative stress, and mitochondrial dysfunction. Cloning of the disease gene for Friedreich ataxia and elucidation of many aspects of the biochemical defects underlying the disorder have led to several major therapeutic initiatives aimed at increasing frataxin expression, reversing mitochondrial iron accumulation, and alleviating oxidative stress. These initiatives are in preclinical and clinical development and are reviewed herein.
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Affiliation(s)
- Robert B Wilson
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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25
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Stehling O, Vashisht AA, Mascarenhas J, Jonsson ZO, Sharma T, Netz DJA, Pierik AJ, Wohlschlegel JA, Lill R. MMS19 assembles iron-sulfur proteins required for DNA metabolism and genomic integrity. Science 2012; 337:195-9. [PMID: 22678362 DOI: 10.1126/science.1219723] [Citation(s) in RCA: 201] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Instability of the nuclear genome is a hallmark of cancer and aging. MMS19 protein has been linked to maintenance of genomic integrity, but the molecular basis of this connection is unknown. Here, we identify MMS19 as a member of the cytosolic iron-sulfur protein assembly (CIA) machinery. MMS19 functions as part of the CIA targeting complex that specifically interacts with and facilitates iron-sulfur cluster insertion into apoproteins involved in methionine biosynthesis, DNA replication, DNA repair, and telomere maintenance. MMS19 thus serves as an adapter between early-acting CIA components and a subset of cellular iron-sulfur proteins. The function of MMS19 in the maturation of crucial components of DNA metabolism may explain the sensitivity of MMS19 mutants to DNA damage and the presence of extended telomeres.
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Affiliation(s)
- Oliver Stehling
- Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Robert-Koch-Str. 6, 35033 Marburg, Germany
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26
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Cotticelli MG, Rasmussen L, Kushner NL, McKellip S, Sosa MI, Manouvakhova A, Feng S, White EL, Maddry JA, Heemskerk J, Oldt RJ, Surrey LF, Ochs R, Wilson RB. Primary and secondary drug screening assays for Friedreich ataxia. JOURNAL OF BIOMOLECULAR SCREENING 2012; 17:303-13. [PMID: 22086726 DOI: 10.1177/1087057111427949] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive neuro- and cardiodegenerative disorder for which there are no proven effective treatments. FRDA is caused by decreased expression and/or function of the protein frataxin. Frataxin chaperones iron in the mitochondrial matrix for the assembly of iron-sulfur clusters (ISCs), which are prosthetic groups critical for the function of the Krebs cycle and the mitochondrial electron transport chain (ETC). Decreased expression of frataxin or the yeast frataxin orthologue, Yfh1p, is associated with decreased ISC assembly, mitochondrial iron accumulation, and increased oxidative stress, all of which contribute to mitochondrial dysfunction. Using yeast depleted of Yfh1p, a high-throughput screening (HTS) assay was developed in which mitochondrial function was monitored by reduction of the tetrazolium dye WST-1 in a growth medium with a respiration-only carbon source. Of 101 200 compounds screened, 302 were identified that effectively rescue mitochondrial function. To confirm activities in mammalian cells and begin understanding mechanisms of action, secondary screening assays were developed using murine C2C12 cells and yeast mutants lacking specific complexes of the ETC, respectively. The compounds identified in this study have potential relevance for other neurodegenerative disorders associated with mitochondrial dysfunction, such as Parkinson disease.
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Affiliation(s)
- M Grazia Cotticelli
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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27
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Marmolino D. Friedreich's ataxia: past, present and future. BRAIN RESEARCH REVIEWS 2011; 67:311-30. [PMID: 21550666 DOI: 10.1016/j.brainresrev.2011.04.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 03/29/2011] [Accepted: 04/12/2011] [Indexed: 01/26/2023]
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive inherited disorder characterized by progressive gait and limb ataxia, dysarthria, areflexia, loss of vibratory and position sense, and a progressive motor weakness of central origin. Additional features include hypertrophic cardiomyopathy and diabetes. Large GAA repeat expansions in the first intron of the FXN gene are the most common mutation underlying FRDA. Patients show severely reduced levels of a FXN-encoded mitochondrial protein called frataxin. Frataxin deficiency is associated with abnormalities of iron metabolism: decreased iron-sulfur cluster (ISC) biogenesis, accumulation of iron in mitochondria and depletion in the cytosol, enhanced cellular iron uptake. Some models have also shown reduced heme synthesis. Evidence for oxidative stress has been reported. Respiratory chain dysfunction aggravates oxidative stress by increasing leakage of electrons and the formation of superoxide. In vitro studies have demonstrated that Frataxin deficient cells not only generate more free radicals, but also show a reduced capacity to mobilize antioxidant defenses. The search for experimental drugs increasing the amount of frataxin is a very active and timely area of investigation. In cellular and in animal model systems, the replacement of frataxin function seems to alleviate the symptoms or even completely reverse the phenotype. Therefore, drugs increasing the amount of frataxin are attractive candidates for novel therapies. This review will discuss recent findings on FRDA pathogenesis, frataxin function, new treatments, as well as recent animal and cellular models. Controversial aspects are also discussed.
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Affiliation(s)
- Daniele Marmolino
- Laboratoire de Neurologie experimentale, Universite Libre de Bruxeles, Route de Lennik 808, Campus Erasme, 1070 Bruxelles, Belgium.
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28
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Qi W, Cowan JA. Structural, Mechanistic and Coordination Chemistry of Relevance to the Biosynthesis of Iron-Sulfur and Related Iron Cofactors. Coord Chem Rev 2011; 255:688-699. [PMID: 21499539 DOI: 10.1016/j.ccr.2010.10.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Iron-sulfur clusters are an important class of protein-bound prosthetic center that find wide utility in nature. Roles include electron transfer, enzyme catalysis, protein structure stabilization, and regulation of gene expression as transcriptional and translational sensors. In eukaryotes their biosynthesis requires a complex molecular machinery that is located within the mitochondrion, while bacteria exhibit up to three independent cluster assembly pathways. All of these paths share common themes. This review summarizes some key structural and functional properties of three central proteins dedicated to the Fe-S cluster assembly process: namely, the sulfide donor (cysteine desulfurase); iron donor (frataxin), and the iron-sulfur cluster scaffold protein (IscU/ISU).
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Affiliation(s)
- Wenbin Qi
- Ohio State Biochemistry Program, The Ohio State University
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29
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Moreno-Cermeño A, Obis È, Bellí G, Cabiscol E, Ros J, Tamarit J. Frataxin depletion in yeast triggers up-regulation of iron transport systems before affecting iron-sulfur enzyme activities. J Biol Chem 2010; 285:41653-64. [PMID: 20956517 PMCID: PMC3009893 DOI: 10.1074/jbc.m110.149443] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 10/07/2010] [Indexed: 11/06/2022] Open
Abstract
The primary function of frataxin, a mitochondrial protein involved in iron homeostasis, remains controversial. Using a yeast model of conditional expression of the frataxin homologue YFH1, we analyzed the primary effects of YFH1 depletion. The main conclusion unambiguously points to the up-regulation of iron transport systems as a primary effect of YFH1 down-regulation. We observed that inactivation of aconitase, an iron-sulfur enzyme, occurs long after the iron uptake system has been activated. Decreased aconitase activity should be considered part of a group of secondary events promoted by iron overloading, which includes decreased superoxide dismutase activity and increased protein carbonyl formation. Impaired manganese uptake, which contributes to superoxide dismutase deficiency, has also been observed in YFH1-deficient cells. This low manganese content can be attributed to the down-regulation of the metal ion transporter Smf2. Low Smf2 levels were not observed in AFT1/YFH1 double mutants, indicating that high iron levels could be responsible for the Smf2 decline. In summary, the results presented here indicate that decreased iron-sulfur enzyme activities in YFH1-deficient cells are the consequence of the oxidative stress conditions suffered by these cells.
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Affiliation(s)
- Armando Moreno-Cermeño
- From the Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida, Universitat de Lleida, 25008 Lleida, Spain
| | - Èlia Obis
- From the Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida, Universitat de Lleida, 25008 Lleida, Spain
| | - Gemma Bellí
- From the Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida, Universitat de Lleida, 25008 Lleida, Spain
| | - Elisa Cabiscol
- From the Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida, Universitat de Lleida, 25008 Lleida, Spain
| | - Joaquim Ros
- From the Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida, Universitat de Lleida, 25008 Lleida, Spain
| | - Jordi Tamarit
- From the Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, Institut de Recerca Biomèdica de Lleida, Universitat de Lleida, 25008 Lleida, Spain
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30
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Santos R, Lefevre S, Sliwa D, Seguin A, Camadro JM, Lesuisse E. Friedreich ataxia: molecular mechanisms, redox considerations, and therapeutic opportunities. Antioxid Redox Signal 2010; 13:651-90. [PMID: 20156111 PMCID: PMC2924788 DOI: 10.1089/ars.2009.3015] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 02/08/2010] [Accepted: 02/14/2010] [Indexed: 12/14/2022]
Abstract
Mitochondrial dysfunction and oxidative damage are at the origin of numerous neurodegenerative diseases like Friedreich ataxia and Alzheimer and Parkinson diseases. Friedreich ataxia (FRDA) is the most common hereditary ataxia, with one individual affected in 50,000. This disease is characterized by progressive degeneration of the central and peripheral nervous systems, cardiomyopathy, and increased incidence of diabetes mellitus. FRDA is caused by a dynamic mutation, a GAA trinucleotide repeat expansion, in the first intron of the FXN gene. Fewer than 5% of the patients are heterozygous and carry point mutations in the other allele. The molecular consequences of the GAA triplet expansion is transcription silencing and reduced expression of the encoded mitochondrial protein, frataxin. The precise cellular role of frataxin is not known; however, it is clear now that several mitochondrial functions are not performed correctly in patient cells. The affected functions include respiration, iron-sulfur cluster assembly, iron homeostasis, and maintenance of the redox status. This review highlights the molecular mechanisms that underlie the disease phenotypes and the different hypothesis about the function of frataxin. In addition, we present an overview of the most recent therapeutic approaches for this severe disease that actually has no efficient treatment.
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Affiliation(s)
- Renata Santos
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
| | - Sophie Lefevre
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
- University Pierre et Marie Curie, Paris, France
| | - Dominika Sliwa
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
| | - Alexandra Seguin
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
| | - Jean-Michel Camadro
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
| | - Emmanuel Lesuisse
- Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod (UMR 7592 CNRS–University Paris-Diderot), Paris, France
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31
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Abstract
Friedreich ataxia is an inherited neurodegenerative disease caused by frataxin deficiency. Frataxin is a conserved mitochondrial protein that plays a role in FeS cluster assembly in mitochondria. FeS clusters are modular cofactors that perform essential functions throughout the cell. They are synthesized by a multistep and multisubunit mitochondrial machinery that includes the scaffold protein Isu for assembling a protein-bound FeS cluster intermediate. Frataxin interacts with Isu, iron, and the cysteine desulfurase Nfs1, which supplies sulfide, thus placing it at the center of mitochondrial FeS cluster biosynthesis.
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Affiliation(s)
- Timothy L Stemmler
- Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, Michigan 48201, France
| | - Emmanuel Lesuisse
- Laboratoire Mitochondrie, Metaux et Stress Oxydant, Institut Jacques Monod, CNRS-Universite Paris Diderot, 75205 Paris, France
| | - Debkumar Pain
- Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07101
| | - Andrew Dancis
- Department of Medicine, Division of Hematology-Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
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32
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Richardson DR, Lane DJR, Becker EM, Huang MLH, Whitnall M, Rahmanto YS, Sheftel AD, Ponka P. Mitochondrial iron trafficking and the integration of iron metabolism between the mitochondrion and cytosol. Proc Natl Acad Sci U S A 2010; 107:10775-82. [PMID: 20495089 PMCID: PMC2890738 DOI: 10.1073/pnas.0912925107] [Citation(s) in RCA: 368] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The mitochondrion is well known for its key role in energy transduction. However, it is less well appreciated that it is also a focal point of iron metabolism. Iron is needed not only for heme and iron sulfur cluster (ISC)-containing proteins involved in electron transport and oxidative phosphorylation, but also for a wide variety of cytoplasmic and nuclear functions, including DNA synthesis. The mitochondrial pathways involved in the generation of both heme and ISCs have been characterized to some extent. However, little is known concerning the regulation of iron uptake by the mitochondrion and how this is coordinated with iron metabolism in the cytosol and other organelles (e.g., lysosomes). In this article, we discuss the burgeoning field of mitochondrial iron metabolism and trafficking that has recently been stimulated by the discovery of proteins involved in mitochondrial iron storage (mitochondrial ferritin) and transport (mitoferrin-1 and -2). In addition, recent work examining mitochondrial diseases (e.g., Friedreich's ataxia) has established that communication exists between iron metabolism in the mitochondrion and the cytosol. This finding has revealed the ability of the mitochondrion to modulate whole-cell iron-processing to satisfy its own requirements for the crucial processes of heme and ISC synthesis. Knowledge of mitochondrial iron-processing pathways and the interaction between organelles and the cytosol could revolutionize the investigation of iron metabolism.
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Affiliation(s)
- Des R. Richardson
- Iron Metabolism and Chelation Program, Discipline of Pathology, University of Sydney, NSW 2006, Australia
| | - Darius J. R. Lane
- Iron Metabolism and Chelation Program, Discipline of Pathology, University of Sydney, NSW 2006, Australia
| | - Erika M. Becker
- Iron Metabolism and Chelation Program, Discipline of Pathology, University of Sydney, NSW 2006, Australia
| | - Michael L.-H. Huang
- Iron Metabolism and Chelation Program, Discipline of Pathology, University of Sydney, NSW 2006, Australia
| | - Megan Whitnall
- Iron Metabolism and Chelation Program, Discipline of Pathology, University of Sydney, NSW 2006, Australia
| | - Yohan Suryo Rahmanto
- Iron Metabolism and Chelation Program, Discipline of Pathology, University of Sydney, NSW 2006, Australia
| | - Alex D. Sheftel
- Institut für Zytobiologie, Philipps-Universität Marburg, Marburg 35037, Germany
| | - Prem Ponka
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada H3T 1E2; and
- Departments of Physiology and Medicine, McGill University, Montreal, QC, Canada H3A 2T5
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33
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Leidgens S, De Smet S, Foury F. Frataxin interacts with Isu1 through a conserved tryptophan in its beta-sheet. Hum Mol Genet 2010; 19:276-86. [PMID: 19884169 DOI: 10.1093/hmg/ddp495] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Friedreich's ataxia is a neurodegenerative disease caused by the low expression of frataxin, a mitochondrial iron-binding protein which plays an important, but non-essential, role in the formation of iron-sulfur (Fe/S) clusters. It has been shown that Yfh1, the yeast frataxin homologue, interacts functionally and physically with Isu1, the scaffold protein on which the Fe/S clusters are assembled. The large beta-sheet platform of frataxin is a good ligand candidate for this interaction. We have generated 12 yeast mutants in conserved residues of the beta-sheet protruding at the surface or buried in the protein core. The Q129A, I130A, W131A(F) and R141A mutations, which reside in surface exposed residues of the fourth and fifth beta-strands, result in severe cell growth inhibition on high-iron media and low aconitase activity, indicating that Fe/S cluster biosynthesis is impaired. The null phenotype of the I130A mutant results from the high instability of the protein, pointing that this buried residue is essential for folding. In contrast, Gln-129, Trp-131 and Arg-141 residues which are spatially closely clustered define a patch important for protein function. Co-immunoprecipitation experiments using cell extracts show that W131A, unlike W131F, is the sole mutation that strongly decreases the interaction with Isu1. Therefore, Trp-131, which is the only strictly conserved frataxin residue in all sequenced species, appears as a major contributor to the interaction with Isu1 through its surface-exposed aromatic side chain.
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Affiliation(s)
- Sébastien Leidgens
- Unité de Biochimie Physiologique, Institut des Sciences de la Vie, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
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34
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Huang MLH, Becker EM, Whitnall M, Rahmanto YS, Ponka P, Richardson DR. Elucidation of the mechanism of mitochondrial iron loading in Friedreich's ataxia by analysis of a mouse mutant. Proc Natl Acad Sci U S A 2009; 106:16381-6. [PMID: 19805308 PMCID: PMC2752539 DOI: 10.1073/pnas.0906784106] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Indexed: 12/12/2022] Open
Abstract
We used the muscle creatine kinase (MCK) conditional frataxin knockout mouse to elucidate how frataxin deficiency alters iron metabolism. This is of significance because frataxin deficiency leads to Friedreich's ataxia, a disease marked by neurologic and cardiologic degeneration. Using cardiac tissues, we demonstrate that frataxin deficiency leads to down-regulation of key molecules involved in 3 mitochondrial utilization pathways: iron-sulfur cluster (ISC) synthesis (iron-sulfur cluster scaffold protein1/2 and the cysteine desulferase Nfs1), mitochondrial iron storage (mitochondrial ferritin), and heme synthesis (5-aminolevulinate dehydratase, coproporphyrinogen oxidase, hydroxymethylbilane synthase, uroporphyrinogen III synthase, and ferrochelatase). This marked decrease in mitochondrial iron utilization and resultant reduced release of heme and ISC from the mitochondrion could contribute to the excessive mitochondrial iron observed. This effect is compounded by increased iron availability for mitochondrial uptake through (i) transferrin receptor1 up-regulation, increasing iron uptake from transferrin; (ii) decreased ferroportin1 expression, limiting iron export; (iii) increased expression of the heme catabolism enzyme heme oxygenase1 and down-regulation of ferritin-H and -L, both likely leading to increased "free iron" for mitochondrial uptake; and (iv) increased expression of the mammalian exocyst protein Sec15l1 and the mitochondrial iron importer mitoferrin-2 (Mfrn2), which facilitate cellular iron uptake and mitochondrial iron influx, respectively. Our results enable the construction of a model explaining the cytosolic iron deficiency and mitochondrial iron loading in the absence of frataxin, which is important for understanding the pathogenesis of Friedreich's ataxia.
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Affiliation(s)
- Michael Li-Hsuan Huang
- Iron Metabolism and Chelation Program, Discipline of Pathology and Bosch Institute, Blackburn Building, D06, University of Sydney, NSW, 2006 Australia and
| | - Erika M. Becker
- Iron Metabolism and Chelation Program, Discipline of Pathology and Bosch Institute, Blackburn Building, D06, University of Sydney, NSW, 2006 Australia and
| | - Megan Whitnall
- Iron Metabolism and Chelation Program, Discipline of Pathology and Bosch Institute, Blackburn Building, D06, University of Sydney, NSW, 2006 Australia and
| | - Yohan Suryo Rahmanto
- Iron Metabolism and Chelation Program, Discipline of Pathology and Bosch Institute, Blackburn Building, D06, University of Sydney, NSW, 2006 Australia and
| | - Prem Ponka
- Lady Davis Institute for Medical Research, 3755 Côte Ste-Catherine Road, Montreal, Quebec, H3T 1E2, Canada
| | - Des R. Richardson
- Iron Metabolism and Chelation Program, Discipline of Pathology and Bosch Institute, Blackburn Building, D06, University of Sydney, NSW, 2006 Australia and
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35
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Pandolfo M, Pastore A. The pathogenesis of Friedreich ataxia and the structure and function of frataxin. J Neurol 2009; 256 Suppl 1:9-17. [PMID: 19283345 DOI: 10.1007/s00415-009-1003-2] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Understanding the role of frataxin in mitochondria is key to an understanding of the pathogenesis of Friedreich ataxia. Frataxins are small essential proteins whose deficiency causes a range of metabolic disturbances, which include oxidative stress, deficit of iron-sulphur clusters, and defects in heme synthesis, sulfur amino acid and energy metabolism, stress response, and mitochondrial function. Structural studies carried out on different orthologues have shown that the frataxin fold consists of a flexible N-terminal region present only in eukaryotes and in a highly conserved C-terminal globular domain. Frataxins bind iron directly but with very unusual properties: iron coordination is achieved solely by glutamates and aspartates exposed on the protein surface. It has been suggested that frataxin function is that of a ferritin-like protein, an iron chaperone of the iron sulphur cluster machinery and heme metabolism and/or a controller of cellular oxidative stress. To understand FRDA pathogenesis and to design novel therapeutic strategies, we must first precisely identify the cellular role of frataxin.
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Affiliation(s)
- Massimo Pandolfo
- Service de Neurologie, Hôpital Erasme - Université Libre de Bruxelles, Brussels, Belgium.
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González-Cabo P, Llorens JV, Palau F, Moltó MD. Friedreich ataxia: an update on animal models, frataxin function and therapies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 652:247-61. [PMID: 20225031 DOI: 10.1007/978-90-481-2813-6_17] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive progressively debilitating degenerative disease that principally affects the nervous system and the heart. Although FRDA is considered a rare disease, is the most common inherited ataxia. It is caused by loss-of-function mutations in the FXN gene, mainly an expanded GAA triplet repeat in the intron 1. The genetic defect results in the reduction of frataxin levels, a protein targeted to the mitochondria. Frataxin deficiency leads to mitochondrial dysfunction, oxidative damage and iron accumulation. Studies of the yeast and animal models of the disease have led to propose several different roles for frataxin. Animal models have also been important for dissecting the steps of pathogenesis in FRDA and they are essential for the development of effective therapies. Currently, antioxidant and iron chelation therapies are under evaluation in clinical trials. Gene reactivation, gene therapy and protein replacement strategies for FRDA are promising approaches. This review focuses on the current models developed for FRDA, the different roles proposed for frataxin and the progress of potential treatment strategies for the disease.
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Affiliation(s)
- Pilar González-Cabo
- Laboratory of Genetics and Molecular Medicine, Instituto de Biomedicina de Valencia, CSIC, C/Jaume Roig 11, Valencia, Spain.
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Kakhlon O, Manning H, Breuer W, Melamed-Book N, Lu C, Cortopassi G, Munnich A, Cabantchik ZI. Cell functions impaired by frataxin deficiency are restored by drug-mediated iron relocation. Blood 2008; 112:5219-27. [PMID: 18796625 DOI: 10.1182/blood-2008-06-161919] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Various human disorders are associated with misdistribution of iron within or across cells. Friedreich ataxia (FRDA), a deficiency in the mitochondrial iron-chaperone frataxin, results in defective use of iron and its misdistribution between mitochondria and cytosol. We assessed the possibility of functionally correcting the cellular properties affected by frataxin deficiency with a siderophore capable of relocating iron and facilitating its metabolic use. Adding the chelator deferiprone at clinical concentrations to inducibly frataxin-deficient HEK-293 cells resulted in chelation of mitochondrial labile iron involved in oxidative stress and in reactivation of iron-depleted aconitase. These led to (1) restoration of impaired mitochondrial membrane and redox potentials, (2) increased adenosine triphosphate production and oxygen consumption, and (3) attenuation of mitochondrial DNA damage and reversal of hypersensitivity to staurosporine-induced apoptosis. Permeant chelators of higher affinity than deferiprone were not as efficient in restoring affected functions. Thus, although iron chelation might protect cells from iron toxicity, rendering the chelated iron bioavailable might underlie the capacity of deferiprone to restore cell functions affected by frataxin deficiency, as also observed in FRDA patients. The siderophore-like properties of deferiprone provide a rational basis for treating diseases of iron misdistribution, such as FRDA, anemia of chronic disease, and X-linked sideroblastic anemia with ataxia.
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Affiliation(s)
- Or Kakhlon
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
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Gakh O, Smith DY, Isaya G. Assembly of the iron-binding protein frataxin in Saccharomyces cerevisiae responds to dynamic changes in mitochondrial iron influx and stress level. J Biol Chem 2008; 283:31500-10. [PMID: 18784075 PMCID: PMC2581586 DOI: 10.1074/jbc.m805415200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Revised: 09/08/2008] [Indexed: 11/06/2022] Open
Abstract
Defects in frataxin result in Friedreich ataxia, a genetic disease characterized by early onset of neurodegeneration, cardiomyopathy, and diabetes. Frataxin is a conserved mitochondrial protein that controls iron needed for iron-sulfur cluster assembly and heme synthesis and also detoxifies excess iron. Studies in vitro have shown that either monomeric or oligomeric frataxin delivers iron to other proteins, whereas ferritin-like frataxin particles convert redox-active iron to an inert mineral. We have investigated how these different forms of frataxin are regulated in vivo. In Saccharomyces cerevisiae, only monomeric yeast frataxin (Yfh1) was detected in unstressed cells when mitochondrial iron uptake was maintained at a steady, low nanomolar level. Increments in mitochondrial iron uptake induced stepwise assembly of Yfh1 species ranging from trimer to > or = 24-mer, independent of interactions between Yfh1 and its major iron-binding partners, Isu1/Nfs1 or aconitase. The rate-limiting step in Yfh1 assembly was a structural transition that preceded conversion of monomer to trimer. This step was induced, independently or synergistically, by mitochondrial iron increments, overexpression of wild type Yfh1 monomer, mutations that stabilize Yfh1 trimer, or heat stress. Faster assembly kinetics correlated with reduced oxidative damage and higher levels of aconitase activity, respiratory capacity, and cell survival. However, deregulation of Yfh1 assembly resulted in Yfh1 aggregation, aconitase sequestration, and mitochondrial DNA depletion. The data suggest that Yfh1 assembly responds to dynamic changes in mitochondrial iron uptake or stress exposure in a highly controlled fashion and that this may enable frataxin to simultaneously promote respiratory function and stress tolerance.
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Affiliation(s)
- Oleksandr Gakh
- Department of Pediatric and Adolescent Medicine, Mayo Clinic, College of Medicine, Rochester, Minnesota 55905, USA
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Willis JH, Isaya G, Gakh O, Capaldi RA, Marusich MF. Lateral-flow immunoassay for the frataxin protein in Friedreich's ataxia patients and carriers. Mol Genet Metab 2008; 94:491-497. [PMID: 18485778 PMCID: PMC2692602 DOI: 10.1016/j.ymgme.2008.03.019] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Accepted: 03/29/2008] [Indexed: 11/18/2022]
Abstract
Friedreich's Ataxia (FA) is an inherited neurodegenerative disease caused by reduction in levels of the mitochondrial protein frataxin. Currently there are no simple, reliable methods to accurately measure the concentrations of frataxin protein. We designed a lateral-flow immunoassay that quantifies frataxin protein levels in a variety of sample materials. Using recombinant frataxin we evaluated the accuracy and reproducibility of the assay. The assay measured recombinant human frataxin concentrations between 40 and 4000 pg/test or approximately 0.1-10 nM of sample. The intra and inter-assay error was <10% throughout the working range. To evaluate clinical utility of the assay we used genetically defined lymphoblastoid cells derived from FA patients, FA carriers and controls. Mean frataxin concentrations in FA patients and carriers were significantly different from controls and from one another (p=0.0001, p=0.003, p=0.005, respectively) with levels, on average, 29% (patients) and 64% (carriers) of the control group. As predicted, we observed an inverse relationship between GAA repeat number and frataxin protein concentrations within the FA patient cohort. The lateral flow immunoassay provides a simple, accurate and reproducible method to quantify frataxin protein in whole cell and tissue extracts, including primary samples obtained by non-invasive means, such as cheek swabs and whole blood. The assay is a novel tool for FA research that may facilitate improved diagnostic and prognostic evaluation of FA patients and could also be used to evaluate efficacy of therapies designed to cure FA by increasing frataxin protein levels.
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Affiliation(s)
| | - Grazia Isaya
- Mayo Clinic College of Medicine, Rochester, MN 55905
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Calabrese V, Cornelius C, Mancuso C, Pennisi G, Calafato S, Bellia F, Bates TE, Giuffrida Stella AM, Schapira T, Dinkova Kostova AT, Rizzarelli E. Cellular stress response: a novel target for chemoprevention and nutritional neuroprotection in aging, neurodegenerative disorders and longevity. Neurochem Res 2008; 33:2444-71. [PMID: 18629638 DOI: 10.1007/s11064-008-9775-9] [Citation(s) in RCA: 196] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Accepted: 06/09/2008] [Indexed: 12/30/2022]
Abstract
The predominant molecular symptom of aging is the accumulation of altered gene products. Moreover, several conditions including protein, lipid or glucose oxidation disrupt redox homeostasis and lead to accumulation of unfolded or misfolded proteins in the aging brain. Alzheimer's and Parkinson's diseases or Friedreich ataxia are neurological diseases sharing, as a common denominator, production of abnormal proteins, mitochondrial dysfunction and oxidative stress, which contribute to the pathogenesis of these so called "protein conformational diseases". The central nervous system has evolved the conserved mechanism of unfolded protein response to cope with the accumulation of misfolded proteins. As one of the main intracellular redox systems involved in neuroprotection, the vitagene system is emerging as a neurohormetic potential target for novel cytoprotective interventions. Vitagenes encode for cytoprotective heat shock proteins (Hsp) Hsp70 and heme oxygenase-1, as well as thioredoxin reductase and sirtuins. Nutritional studies show that ageing in animals can be significantly influenced by dietary restriction. Thus, the impact of dietary factors on health and longevity is an increasingly appreciated area of research. Reducing energy intake by controlled caloric restriction or intermittent fasting increases lifespan and protects various tissues against disease. Genetics has revealed that ageing may be controlled by changes in intracellular NAD/NADH ratio regulating sirtuin, a group of proteins linked to aging, metabolism and stress tolerance in several organisms. Recent findings suggest that several phytochemicals exhibit biphasic dose responses on cells with low doses activating signaling pathways that result in increased expression of vitagenes encoding survival proteins, as in the case of the Keap1/Nrf2/ARE pathway activated by curcumin and NAD/NADH-sirtuin-1 activated by resveratrol. Consistently, the neuroprotective roles of dietary antioxidants including curcumin, acetyl-L-carnitine and carnosine have been demonstrated through the activation of these redox-sensitive intracellular pathways. Although the notion that stress proteins are neuroprotective is broadly accepted, still much work needs to be done in order to associate neuroprotection with specific pattern of stress responses. In this review the importance of vitagenes in the cellular stress response and the potential use of dietary antioxidants in the prevention and treatment of neurodegenerative disorders is discussed.
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Affiliation(s)
- Vittorio Calabrese
- Section of Biochemistry and Molecular Biology, Department of Chemistry, Faculty of Medicine, University of Catania, Viale Andrea Doria 6, 95100, Catania, Italy.
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Huang J, Dizin E, Cowan JA. Mapping iron binding sites on human frataxin: implications for cluster assembly on the ISU Fe-S cluster scaffold protein. J Biol Inorg Chem 2008; 13:825-36. [PMID: 18425540 DOI: 10.1007/s00775-008-0369-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 03/26/2008] [Indexed: 02/07/2023]
Abstract
Frataxin is an iron binding mitochondrial matrix protein that has been shown to mediate iron delivery during iron-sulfur cluster and heme biosynthesis. There is a high degree of structural homology for frataxin proteins from diverse sources, and all possess an anionic surface defined by acidic residues. In the human protein these residues principally lie on a surface defined by the alpha1 helix and beta1 sheet and the impact of multiple substitutions of these carboxylate residues on iron binding is described. Full-length human frataxin has previously been shown to undergo self-cleavage to produce a truncated form both in vitro and in vivo. This truncated protein has been shown to bind approximately seven iron centers that are presumably associated with the acidic patch. Relative to this native protein, the stoichiometry decreases according to the number and sites of mutations. Nevertheless, the iron-dependent binding affinity of each frataxin derivative to the iron-sulfur cluster scaffold protein ISU is found to be similar to that of native frataxin, as defined by isothermal titration calorimetry experiments, requiring only one iron center to promote nanomolar binding. While frataxins from various cell types appear to bind differing numbers of iron centers, the physiologically relevant number of bound irons appears to be small, with significantly higher binding affinity following complex formation with partner proteins (micromolar compared with nanomolar binding). By contrast, in reconstitution assays for frataxin-promoted [2Fe-2S](2+) cluster assembly on ISU, one derivative does display a modestly lower reconstitution rate. The overall consensus from these data is to consider a pool of potential sites that can stably bind an iron center when bridged to a variety of physiological targets.
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Affiliation(s)
- Jia Huang
- Evans Laboratory of Chemistry, Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, USA
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42
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Anderson PR, Kirby K, Orr WC, Hilliker AJ, Phillips JP. Hydrogen peroxide scavenging rescues frataxin deficiency in a Drosophila model of Friedreich's ataxia. Proc Natl Acad Sci U S A 2008; 105:611-6. [PMID: 18184803 PMCID: PMC2206584 DOI: 10.1073/pnas.0709691105] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Indexed: 11/18/2022] Open
Abstract
Friedreich's ataxia (FRDA) is a neurodegenerative disorder arising from a deficit of the mitochondrial iron chaperone, frataxin. Evidence primarily from yeast and mammalian cells is consistent with the hypothesis that a toxic hydroxyl radical generated from hydrogen peroxide (H2O2) via iron-catalyzed Fenton chemistry at least partially underlies the pathology associated with this disease. However, no whole-organism studies have been presented that directly test this hypothesis. We recently developed a Drosophila model that recapitulates the principal hallmarks of FRDA [Anderson PR, Kirby K, Hilliker A, Phillips JP (2005) Hum Mol Genet 14:3397-3405]. Using the Drosophila FRDA model, we now report that ectopic expression of enzymes that scavenge H2O2 suppresses the deleterious phenotypes associated with frataxin deficiency. In contrast, genetic augmentation with enzymes that scavenge superoxide is without effect. Augmentation of endogenous catalase restores the activity of the reactive oxygen species (ROS)-sensitive mitochondrial enzyme, aconitase and enhances resistance to H2O2 exposure, both of which are diminished by frataxin deficiency. Collectively, these data argue that H2O2 is an important pathogenic substrate underlying the phenotypes arising from frataxin deficiency in Drosophila and that interventions that reduce this specific ROS can effectively ameliorate these phenotypes. The therapeutic implications of these findings are clear and we believe warrant immediate clinical investigation.
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Affiliation(s)
- Peter R. Anderson
- *Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Kim Kirby
- *Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - William C. Orr
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75205; and
| | | | - John P. Phillips
- *Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
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Mitochondrial Iba57p is required for Fe/S cluster formation on aconitase and activation of radical SAM enzymes. Mol Cell Biol 2007; 28:1851-61. [PMID: 18086897 DOI: 10.1128/mcb.01963-07] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
A genome-wide screen for Saccharomyces cerevisiae iron-sulfur (Fe/S) cluster assembly mutants identified the gene IBA57. The encoded protein Iba57p is located in the mitochondrial matrix and is essential for mitochondrial DNA maintenance. The growth phenotypes of an iba57Delta mutant and extensive functional studies in vivo and in vitro indicate a specific role for Iba57p in the maturation of mitochondrial aconitase-type and radical SAM Fe/S proteins (biotin and lipoic acid synthases). Maturation of other Fe/S proteins occurred normally in the absence of Iba57p. These observations identify Iba57p as a novel dedicated maturation factor with specificity for a subset of Fe/S proteins. The Iba57p primary sequence is distinct from any known Fe/S assembly factor but is similar to certain tetrahydrofolate-binding enzymes, adding a surprising new function to this protein family. Iba57p physically interacts with the mitochondrial ISC assembly components Isa1p and Isa2p. Since all three proteins are conserved in eukaryotes and bacteria, the specificity of the Iba57/Isa complex may represent a biosynthetic concept that is universally used in nature. In keeping with this idea, the human IBA57 homolog C1orf69 complements the iba57Delta growth defects, demonstrating its conserved function throughout the eukaryotic kingdom.
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44
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Bedekovics T, Gajdos GB, Kispal G, Isaya G. Partial conservation of functions between eukaryotic frataxin and the Escherichia coli frataxin homolog CyaY. FEMS Yeast Res 2007; 7:1276-84. [PMID: 17727661 DOI: 10.1111/j.1567-1364.2007.00296.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Frataxin is a mitochondrial protein structurally conserved from bacteria to humans. Eukaryotic frataxins are known to be involved in the maintenance of mitochondrial iron balance via roles in iron delivery and iron detoxification. The prokaryotic frataxin homolog, CyaY, has been shown to bind and donate iron for the assembly of [2Fe-2S] clusters in vitro. However, in contrast to the severe phenotypes associated with the partial or complete loss of frataxin in humans and other eukaryotes, deletion of the cyaY gene does not cause any obvious alteration of iron balance in bacterial cells, an effect that probably reflects functional redundancy between CyaY and other bacterial proteins. To study CyaY function in a nonredundant setting, we have expressed a mitochondria-targeted form of CyaY in a Saccharomyces cerevisiae strain depleted of the endogenous yeast frataxin protein (yfh1Delta). We show that in this strain CyaY complements to a large extent the loss of iron-sulfur cluster enzyme activities and heme synthesis, and thereby maintains a nearly normal respiratory growth. In addition, CyaY effectively protects yfh1Delta from oxidative damage during treatment with hydrogen peroxide but is less efficient in detoxifying excess labile iron during aerobic growth.
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Affiliation(s)
- Tibor Bedekovics
- Department of Biochemistry and Medical Chemistry, Faculty of Medicine, University of Pécs, Pécs, Hungary.
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Abstract
The discovery that expansion of unstable repeats can cause a variety of neurological disorders has changed the landscape of disease-oriented research for several forms of mental retardation, Huntington disease, inherited ataxias, and muscular dystrophy. The dynamic nature of these mutations provided an explanation for the variable phenotype expressivity within a family. Beyond diagnosis and genetic counseling, the benefits from studying these disorders have been noted in both neurobiology and cell biology. Examples include insight about the role of translational control in synaptic plasticity, the role of RNA processing in the integrity of muscle and neuronal function, the importance of Fe-S-containing enzymes for cellular energy, and the dramatic effects of altering protein conformations on neuronal function and survival. It is exciting that within a span of 15 years, pathogenesis studies of this class of disorders are beginning to reveal pathways that are potential therapeutic targets.
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Affiliation(s)
- Harry T Orr
- Institute of Human Genetics, Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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46
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Jauslin ML, Vertuani S, Durini E, Buzzoni L, Ciliberti N, Verdecchia S, Palozza P, Meier T, Manfredini S. Protective effects of Fe-Aox29, a novel antioxidant derived from a molecular combination of Idebenone and vitamin E, in immortalized fibroblasts and fibroblasts from patients with Friedreich Ataxia. Mol Cell Biochem 2007; 302:79-85. [PMID: 17476463 DOI: 10.1007/s11010-007-9429-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Accepted: 02/09/2007] [Indexed: 12/15/2022]
Abstract
Friedreich Ataxia (FRDA), the most frequent inherited ataxia, is not only characterized by progressive gait and limb ataxia, but in most cases is also accompanied by a severe hypertrophic cardiomyopathy. This life threatening symptom can be ameliorated by the administration of idebenone, a short chain quinone antioxidant, supporting additional evidence that oxidative stress plays a major role in the pathogenesis of this disease. In this study we analyze the combinatorial effect of different antioxidants on cell viability of FRDA fibroblasts and of RAT-1 immortalized fibroblasts exposed to oxidative stress. We find that an equimolar mixture of idebenone and vitamin E is more potent than each of the compound alone. Increased potency was also obtained with a novel synthetic antioxidant (Fe-Aox29) combining the active groups from both idebenone and vitamin E. These results indicate, that idebenone and vitamin E might act synergistically to counteract oxidative stress in fibroblasts from FRDA patients.
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Shan Y, Napoli E, Cortopassi G. Mitochondrial frataxin interacts with ISD11 of the NFS1/ISCU complex and multiple mitochondrial chaperones. Hum Mol Genet 2007; 16:929-41. [PMID: 17331979 DOI: 10.1093/hmg/ddm038] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The neurodegenerative disorder Friedreich's ataxia (FRDA) is caused by mutations in frataxin, a mitochondrial protein whose function remains controversial. Using co-immunoprecipitation and mass spectrometry we identified multiple interactors of mitochondrial frataxin in mammalian cells. One interactor was mortalin/GRP75, a homolog of the yeast ssq1 chaperone that integrates iron-sulfur clusters into imported mitochondrial proteins. Another interactor was ISD11, recently identified as a component of the eukaryotic complex Nfs1/ISCU, an essential component of iron-sulfur cluster biogenesis. Interactions between frataxin and ISD11, and frataxin and GRP75 were confirmed by co-immunoprecipitation experiments in both directions. Immunofluorescence analysis demonstrated that ISD11 co-localized with both frataxin and with mitochondria. The point mutations I154F and W155R in frataxin cause FRDA and are clustered to one surface of the protein, and these mutations decrease the interaction of frataxin with ISD11. The frataxin/ISD11 interaction was also decreased by the chelator EDTA, and was increased by supplementation with nickel but not other metal ions. Nickel supplementation rescued the defective interaction of mutant frataxin I154F and W155R with ISD11. Upon ISD11 depletion by siRNA in HEK293T cells, the amount of the Nfs1/ISCU protein complex declined, as did the activity of the iron-sulfur cluster enzyme aconitase, while the cellular iron content was increased, as seen in tissues from FRDA patients. Furthermore, ISD11 mRNA levels were decreased in FRDA patient cells. These data suggest that frataxin binds the iron-sulfur biogenesis Nfs1/ISCU complex through ISD11, that the interaction is nickel-dependent, and that multiple consequences of frataxin deficiency are duplicated by ISD11 deficiency.
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Affiliation(s)
- Yuxi Shan
- VM:Molecular Biosciences, 1311 Haring Hall, Davis, CA 95616, USA
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48
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Cooper JM, Schapira AHV. Friedreich's ataxia: coenzyme Q10 and vitamin E therapy. Mitochondrion 2007; 7 Suppl:S127-35. [PMID: 17485244 DOI: 10.1016/j.mito.2007.04.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 03/30/2007] [Accepted: 04/01/2007] [Indexed: 11/29/2022]
Abstract
Since the identification of the genetic mutation causing Friedreich's ataxia (FRDA) our understanding of the mechanisms underlying disease pathogenesis have improved markedly. The genetic abnormality results in the deficiency of frataxin, a protein targeted to the mitochondrion. There is extensive evidence that mitochondrial respiratory chain dysfunction, oxidative damage and iron accumulation play significant roles in the disease mechanism. There remains considerable debate as to the normal function of frataxin, but it is likely to be involved in mitochondrial iron handling, antioxidant regulation, and/or iron sulphur centre regulation. Therapeutic avenues for patients with FRDA are beginning to be explored in particular targeting antioxidant protection, enhancement of mitochondrial oxidative phosphorylation, iron chelation and more recently increasing FRDA transcription. The use of quinone therapy has been the most extensively studied to date with clear benefits demonstrated using evaluations of both disease biomarkers and clinical symptoms, and this is the topic that will be covered in this review.
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Affiliation(s)
- J M Cooper
- University Department of Clinical Neurosciences, Royal Free and University College Medical School, University College London, Rowland Hill Street, London NW3 2PF, UK.
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49
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Foury F, Pastore A, Trincal M. Acidic residues of yeast frataxin have an essential role in Fe-S cluster assembly. EMBO Rep 2007; 8:194-9. [PMID: 17186026 PMCID: PMC1796776 DOI: 10.1038/sj.embor.7400881] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 11/17/2006] [Accepted: 11/17/2006] [Indexed: 11/09/2022] Open
Abstract
Friedreich ataxia is caused by decreased levels of frataxin, a mitochondrial acidic protein that is assumed to act as chaperone in the assembly of Fe-S clusters on the scaffold Isu protein. Frataxin has the in vitro capacity to form iron-loaded multimers, which also suggests an iron storage function. It has been reported that alanine substitution of residues in an acidic ridge of yeast frataxin (Yfh1) elicits loss of iron binding in vitro but has no effect on Fe-S cluster synthesis in vivo. Here, we show that a marked change in the electrostatic properties of a specific region of Yfh1 surface - by substituting two or four acidic residues by lysine or alanine, respectively - impairs Fe-S cluster assembly, weakens the interaction between Yfh1 and Isu1, and increases oxidative damage. Therefore, the acidic ridge is essential for the Yfh1 function and is likely to be involved in iron-mediated protein-protein interactions.
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Affiliation(s)
- Françoise Foury
- Unité de Biochimie Physiologique, Universite Catholique de Louvain, Croix du Sud, 5-15, 1348 Louvain-la-Neuve, Belgium.
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50
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Abstract
Although the pathophysiology underlying a number of neurodegenerative diseases is complex and, in many aspects, only partly understood, increased iron levels in pathologically relevant brain areas and iron-mediated oxidative stress seem to play a central role in many of them. Much has been learned from monogenetically caused disturbances of brain iron metabolism including pantothenate kinase-associated neurodegeneration type 2, hereditary ferritinopathies affecting the basal ganglia, and aceruloplasminemia that may well be applied to the most common neurodegenerative disorders associated with brain iron accumulation including Parkinson disease and Alzheimer disease. Iron-mediated oxidative stress in neurodegenerative diseases caused by other genetic pathways like Huntington disease and Friedreich ataxia underscore the complex interaction of this trace metal and genetic variations. Therapeutical strategies derived from application of iron chelators in monogenetically caused disturbances of brain iron metabolism and new iron and oxidative stress diminishing substances in animal models of Parkinson disease are promising and warrant further investigational effort.
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Affiliation(s)
- Daniela Berg
- Center of Neurology, Department of Neurodegeneration and Hertie Institute of Clinical Brain, University of Tübingen, Tübingen, Germany
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