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Duncan RS, Keightley A, Lopez AA, Hall CW, Koulen P. Proteome changes in a human retinal pigment epithelial cell line during oxidative stress and following antioxidant treatment. Front Immunol 2023; 14:1138519. [PMID: 37153596 PMCID: PMC10154683 DOI: 10.3389/fimmu.2023.1138519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 03/27/2023] [Indexed: 05/09/2023] Open
Abstract
Age related macular degeneration (AMD) is the most common cause of blindness in the elderly. Oxidative stress contributes to retinal pigment epithelium (RPE) dysfunction and cell death thereby leading to AMD. Using improved RPE cell model systems, such as human telomerase transcriptase-overexpressing (hTERT) RPE cells (hTERT-RPE), pathophysiological changes in RPE during oxidative stress can be better understood. Using this model system, we identified changes in the expression of proteins involved in the cellular antioxidant responses after induction of oxidative stress. Some antioxidants such as vitamin E (tocopherols and tocotrienols) are powerful antioxidants that can reduce oxidative damage in cells. Alpha-tocopherol (α-Toc or αT) and gamma-tocopherol (γ-Toc or γT) are well-studied tocopherols, but signaling mechanisms underlying their respective cytoprotective properties may be distinct. Here, we determined what effect oxidative stress, induced by extracellularly applied tBHP in the presence and absence of αT and/or γT, has on the expression of antioxidant proteins and related signaling networks. Using proteomics approaches, we identified differential protein expression in cellular antioxidant response pathways during oxidative stress and after tocopherol treatment. We identified three groups of proteins based on biochemical function: glutathione metabolism/transfer, peroxidases and redox-sensitive proteins involved in cytoprotective signaling. We found that oxidative stress and tocopherol treatment resulted in unique changes in these three groups of antioxidant proteins indicate that αT and γT independently and by themselves can induce the expression of antioxidant proteins in RPE cells. These results provide novel rationales for potential therapeutic strategies to protect RPE cells from oxidative stress.
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Affiliation(s)
- R. Scott Duncan
- Vision Research Center, Department of Ophthalmology, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
| | - Andrew Keightley
- Vision Research Center, Department of Ophthalmology, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
| | - Adam A. Lopez
- Vision Research Center, Department of Ophthalmology, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
| | - Conner W. Hall
- Vision Research Center, Department of Ophthalmology, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
| | - Peter Koulen
- Vision Research Center, Department of Ophthalmology, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
- Department of Biomedical Sciences, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
- *Correspondence: Peter Koulen,
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Terenzi A, Pagani MA, Gomez-Casati DF, Busi MV. Structural and Functional Characterization of CreFH1, the Frataxin Homolog from Chlamydomonas reinhardtii. PLANTS 2022; 11:plants11151931. [PMID: 35893635 PMCID: PMC9331050 DOI: 10.3390/plants11151931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/14/2022] [Accepted: 07/19/2022] [Indexed: 11/29/2022]
Abstract
Frataxin plays a key role in cellular iron homeostasis of different organisms. It has been implicated in iron storage, detoxification, delivery for Fe-S cluster assembly and heme biosynthesis. However, its specific role in iron metabolism remains unclear, especially in photosynthetic organisms. To gain insight into the role and properties of frataxin in algae, we identified the gene CreFH1, which codes for the frataxin homolog from Chlamydomonas reinhardtii. We performed the cloning, expression and biochemical characterization of CreFH1. This protein has a predicted mitochondrial transit peptide and a significant structural similarity to other members of the frataxin family. In addition, CreFH1 was able to form a dimer in vitro, and this effect was increased by the addition of Cu2+ and also attenuated the Fenton reaction in the presence of a mixture of Fe2+ and H2O2. Bacterial cells with overexpression of CreFH1 showed increased growth in the presence of different metals, such as Fe, Cu, Zn and Ni and H2O2. Thus, results indicated that CreFH1 is a functional protein that shows some distinctive features compared to its more well-known counterparts, and would play an important role in response to oxidative stress in C. reinhardtii.
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Gomez-Casati DF, Busi MV, Barchiesi J, Pagani MA, Marchetti-Acosta NS, Terenzi A. Fe-S Protein Synthesis in Green Algae Mitochondria. PLANTS 2021; 10:plants10020200. [PMID: 33494487 PMCID: PMC7911964 DOI: 10.3390/plants10020200] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/13/2021] [Accepted: 01/18/2021] [Indexed: 12/28/2022]
Abstract
Iron and sulfur are two essential elements for all organisms. These elements form the Fe-S clusters that are present as cofactors in numerous proteins and protein complexes related to key processes in cells, such as respiration and photosynthesis, and participate in numerous enzymatic reactions. In photosynthetic organisms, the ISC and SUF Fe-S cluster synthesis pathways are located in organelles, mitochondria, and chloroplasts, respectively. There is also a third biosynthetic machinery in the cytosol (CIA) that is dependent on the mitochondria for its function. The genes and proteins that participate in these assembly pathways have been described mainly in bacteria, yeasts, humans, and recently in higher plants. However, little is known about the proteins that participate in these processes in algae. This review work is mainly focused on releasing the information on the existence of genes and proteins of green algae (chlorophytes) that could participate in the assembly process of Fe-S groups, especially in the mitochondrial ISC and CIA pathways.
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Affiliation(s)
- Diego F. Gomez-Casati
- Correspondence: (D.F.G.-C.); (M.V.B.); Tel.: +54-341-4391955 (ext. 113) (D.F.G.-C. & M.V.B.)
| | - Maria V. Busi
- Correspondence: (D.F.G.-C.); (M.V.B.); Tel.: +54-341-4391955 (ext. 113) (D.F.G.-C. & M.V.B.)
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Agrò M, Díaz-Nido J. Effect of Mitochondrial and Cytosolic FXN Isoform Expression on Mitochondrial Dynamics and Metabolism. Int J Mol Sci 2020; 21:E8251. [PMID: 33158039 PMCID: PMC7662637 DOI: 10.3390/ijms21218251] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 10/27/2020] [Accepted: 11/02/2020] [Indexed: 02/07/2023] Open
Abstract
Friedreich's ataxia (FRDA) is a neurodegenerative disease caused by recessive mutations in the frataxin gene that lead to a deficiency of the mitochondrial frataxin (FXN) protein. Alternative forms of frataxin have been described, with different cellular localization and tissue distribution, including a cerebellum-specific cytosolic isoform called FXN II. Here, we explored the functional roles of FXN II in comparison to the mitochondrial FXN I isoform, highlighting the existence of potential cross-talk between cellular compartments. To achieve this, we transduced two human cell lines of patient and healthy subjects with lentiviral vectors overexpressing the mitochondrial or the cytosolic FXN isoforms and studied their effect on the mitochondrial network and metabolism. We confirmed the cytosolic localization of FXN isoform II in our in vitro models. Interestingly, both cytosolic and mitochondrial isoforms have an effect on mitochondrial dynamics, affecting different parameters. Accordingly, increases of mitochondrial respiration were detected after transduction with FXN I or FXN II in both cellular models. Together, these results point to the existence of a potential cross-talk mechanism between the cytosol and mitochondria, mediated by FXN isoforms. A more thorough knowledge of the mechanisms of action behind the extra-mitochondrial FXN II isoform could prove useful in unraveling FRDA physiopathology.
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Affiliation(s)
| | - Javier Díaz-Nido
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, Nicolás Cabrera, 1, 28049 Madrid, Spain;
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Armas AM, Balparda M, Terenzi A, Busi MV, Pagani MA, Gomez-Casati DF. Iron-Sulfur Cluster Complex Assembly in the Mitochondria of Arabidopsis thaliana. PLANTS (BASEL, SWITZERLAND) 2020; 9:plants9091171. [PMID: 32917022 PMCID: PMC7570111 DOI: 10.3390/plants9091171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/21/2020] [Accepted: 09/08/2020] [Indexed: 05/02/2023]
Abstract
In plants, the cysteine desulfurase (AtNFS1) and frataxin (AtFH) are involved in the formation of Fe-S groups in mitochondria, specifically, in Fe and sulfur loading onto scaffold proteins, and the subsequent formation of the mature Fe-S cluster. We found that the small mitochondrial chaperone, AtISD11, and AtFH are positive regulators for AtNFS1 activity in Arabidopsis. Moreover, when the three proteins were incubated together, a stronger attenuation of the Fenton reaction was observed compared to that observed with AtFH alone. Using pull-down assays, we found that these three proteins physically interact, and sequence alignment and docking studies showed that several amino acid residues reported as critical for the interaction of their human homologous are conserved. Our results suggest that AtFH, AtNFS1 and AtISD11 form a multiprotein complex that could be involved in different stages of the iron-sulfur cluster (ISC) pathway in plant mitochondria.
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Affiliation(s)
- Alejandro M. Armas
- Instituto de Biologia Molecular y Celular de Rosario (IBR-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina;
| | - Manuel Balparda
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina; (M.B.); (A.T.); (M.V.B.); (M.A.P.)
| | - Agustina Terenzi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina; (M.B.); (A.T.); (M.V.B.); (M.A.P.)
| | - Maria V. Busi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina; (M.B.); (A.T.); (M.V.B.); (M.A.P.)
| | - Maria A. Pagani
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina; (M.B.); (A.T.); (M.V.B.); (M.A.P.)
| | - Diego F. Gomez-Casati
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina; (M.B.); (A.T.); (M.V.B.); (M.A.P.)
- Correspondence: ; Tel.: +54-341-4391955 (ext. 113)
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6
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Monnier V, Llorens JV, Navarro JA. Impact of Drosophila Models in the Study and Treatment of Friedreich's Ataxia. Int J Mol Sci 2018; 19:E1989. [PMID: 29986523 PMCID: PMC6073496 DOI: 10.3390/ijms19071989] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 06/26/2018] [Accepted: 07/03/2018] [Indexed: 02/07/2023] Open
Abstract
Drosophila melanogaster has been for over a century the model of choice of several neurobiologists to decipher the formation and development of the nervous system as well as to mirror the pathophysiological conditions of many human neurodegenerative diseases. The rare disease Friedreich’s ataxia (FRDA) is not an exception. Since the isolation of the responsible gene more than two decades ago, the analysis of the fly orthologue has proven to be an excellent avenue to understand the development and progression of the disease, to unravel pivotal mechanisms underpinning the pathology and to identify genes and molecules that might well be either disease biomarkers or promising targets for therapeutic interventions. In this review, we aim to summarize the collection of findings provided by the Drosophila models but also to go one step beyond and propose the implications of these discoveries for the study and cure of this disorder. We will present the physiological, cellular and molecular phenotypes described in the fly, highlighting those that have given insight into the pathology and we will show how the ability of Drosophila to perform genetic and pharmacological screens has provided valuable information that is not easily within reach of other cellular or mammalian models.
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Affiliation(s)
- Véronique Monnier
- Unité de Biologie Fonctionnelle et Adaptative (BFA), Sorbonne Paris Cité, Université Paris Diderot, UMR8251 CNRS, 75013 Paris, France.
| | - Jose Vicente Llorens
- Department of Genetics, University of Valencia, Campus of Burjassot, 96100 Valencia, Spain.
| | - Juan Antonio Navarro
- Lehrstuhl für Entwicklungsbiologie, Universität Regensburg, 93040 Regensburg, Germany.
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Cai K, Frederick RO, Tonelli M, Markley JL. Interactions of iron-bound frataxin with ISCU and ferredoxin on the cysteine desulfurase complex leading to Fe-S cluster assembly. J Inorg Biochem 2018; 183:107-116. [PMID: 29576242 PMCID: PMC5951399 DOI: 10.1016/j.jinorgbio.2018.03.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 03/08/2018] [Accepted: 03/12/2018] [Indexed: 12/15/2022]
Abstract
Frataxin (FXN) is involved in mitochondrial iron‑sulfur (Fe-S) cluster biogenesis and serves to accelerate Fe-S cluster formation. FXN deficiency is associated with Friedreich ataxia, a neurodegenerative disease. We have used a combination of isothermal titration calorimetry and multinuclear NMR spectroscopy to investigate interactions among the components of the biological machine that carries out the assembly of iron‑sulfur clusters in human mitochondria. Our results show that FXN tightly binds a single Fe2+ but not Fe3+. While FXN (with or without bound Fe2+) does not bind the scaffold protein ISCU directly, the two proteins interact mutually when each is bound to the cysteine desulfurase complex ([NFS1]2:[ISD11]2:[Acp]2), abbreviated as (NIA)2, where "N" represents the cysteine desulfurase (NFS1), "I" represents the accessory protein (ISD11), and "A" represents acyl carrier protein (Acp). FXN binds (NIA)2 weakly in the absence of ISCU but more strongly in its presence. Fe2+-FXN binds to the (NIA)2-ISCU2 complex without release of iron. However, upon the addition of both l-cysteine and a reductant (either reduced FDX2 or DTT), Fe2+ is released from FXN as consistent with Fe2+-FXN being the proximal source of iron for Fe-S cluster assembly.
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Affiliation(s)
- Kai Cai
- National Magnetic Resonance Facility at Madison and Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, United States
| | - Ronnie O Frederick
- National Magnetic Resonance Facility at Madison and Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, United States
| | - Marco Tonelli
- National Magnetic Resonance Facility at Madison and Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, United States
| | - John L Markley
- National Magnetic Resonance Facility at Madison and Biochemistry Department, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, United States.
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8
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Wachnowsky C, Fidai I, Cowan JA. Iron-sulfur cluster biosynthesis and trafficking - impact on human disease conditions. Metallomics 2018; 10:9-29. [PMID: 29019354 PMCID: PMC5783746 DOI: 10.1039/c7mt00180k] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Iron-sulfur clusters (Fe-S) are one of the most ancient, ubiquitous and versatile classes of metal cofactors found in nature. Proteins that contain Fe-S clusters constitute one of the largest families of proteins, with varied functions that include electron transport, regulation of gene expression, substrate binding and activation, radical generation, and, more recently discovered, DNA repair. Research during the past two decades has shown that mitochondria are central to the biogenesis of Fe-S clusters in eukaryotic cells via a conserved cluster assembly machinery (ISC assembly machinery) that also controls the synthesis of Fe-S clusters of cytosolic and nuclear proteins. Several key steps for synthesis and trafficking have been determined for mitochondrial Fe-S clusters, as well as the cytosol (CIA - cytosolic iron-sulfur protein assembly), but detailed mechanisms of cluster biosynthesis, transport, and exchange are not well established. Genetic mutations and the instability of certain steps in the biosynthesis and maturation of mitochondrial, cytosolic and nuclear Fe-S cluster proteins affects overall cellular iron homeostasis and can lead to severe metabolic, systemic, neurological and hematological diseases, often resulting in fatality. In this review we briefly summarize the current molecular understanding of both mitochondrial ISC and CIA assembly machineries, and present a comprehensive overview of various associated inborn human disease states.
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Affiliation(s)
- C Wachnowsky
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
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Lin H, Magrane J, Rattelle A, Stepanova A, Galkin A, Clark EM, Dong YN, Halawani SM, Lynch DR. Early cerebellar deficits in mitochondrial biogenesis and respiratory chain complexes in the KIKO mouse model of Friedreich ataxia. Dis Model Mech 2017; 10:1343-1352. [PMID: 29125827 PMCID: PMC5719255 DOI: 10.1242/dmm.030502] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/11/2017] [Indexed: 12/14/2022] Open
Abstract
Friedreich ataxia (FRDA), the most common recessive inherited ataxia, results from deficiency of frataxin, a small mitochondrial protein crucial for iron-sulphur cluster formation and ATP production. Frataxin deficiency is associated with mitochondrial dysfunction in FRDA patients and animal models; however, early mitochondrial pathology in FRDA cerebellum remains elusive. Using frataxin knock-in/knockout (KIKO) mice and KIKO mice carrying the mitoDendra transgene, we show early cerebellar deficits in mitochondrial biogenesis and respiratory chain complexes in this FRDA model. At asymptomatic stages, the levels of PGC-1α (PPARGC1A), the mitochondrial biogenesis master regulator, are significantly decreased in cerebellar homogenates of KIKO mice compared with age-matched controls. Similarly, the levels of the PGC-1α downstream effectors, NRF1 and Tfam, are significantly decreased, suggesting early impaired cerebellar mitochondrial biogenesis pathways. Early mitochondrial deficiency is further supported by significant reduction of the mitochondrial markers GRP75 (HSPA9) and mitofusin-1 in the cerebellar cortex. Moreover, the numbers of Dendra-labeled mitochondria are significantly decreased in cerebellar cortex, confirming asymptomatic cerebellar mitochondrial biogenesis deficits. Functionally, complex I and II enzyme activities are significantly reduced in isolated mitochondria and tissue homogenates from asymptomatic KIKO cerebella. Structurally, levels of the complex I core subunit NUDFB8 and complex II subunits SDHA and SDHB are significantly lower than those in age-matched controls. These results demonstrate complex I and II deficiency in KIKO cerebellum, consistent with defects identified in FRDA patient tissues. Thus, our findings identify early cerebellar mitochondrial biogenesis deficits as a potential mediator of cerebellar dysfunction and ataxia, thereby providing a potential therapeutic target for early intervention of FRDA.
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Affiliation(s)
- Hong Lin
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Jordi Magrane
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA
| | - Amy Rattelle
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Anna Stepanova
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Alexander Galkin
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Elisia M Clark
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yi Na Dong
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Sarah M Halawani
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - David R Lynch
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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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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Mohammadpour M, Behjati M, Sadeghi A, Fassihi A. Wound healing by topical application of antioxidant iron chelators: kojic acid and deferiprone. Int Wound J 2012; 10:260-4. [PMID: 22621771 DOI: 10.1111/j.1742-481x.2012.00971.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Kojic acid and deferiprone are iron chelators used for skin lightening and iron-overload treatment, respectively. As iron chelation and free radical scavenging are principal factors for wound healing, it was hypothesised that the local application of these compounds might accelerate wound healing in rats. Ointments of 3%, 6% and 9% of deferiprone and kojic acid were prepared and topical treatment was performed on in vivo wound models for 12 days twice in day for test and control groups. Topical treatment with 3%, 6% and 9% showed significant improvement in wound healing after 4 days (P < 0·001). Topical application of 3% and 6% deferiprone enhanced wound healing after 8 days (P < 0·026 and P < 0·001, respectively). Accelerated wound healing was seen using 3% and 6% deferiprone after 12 days (P = 0·003 and P < 0·001, respectively). DPPH scavenging assay was also performed to compare the antioxidant potencies of kojic acid and deferiprone. Deferiprone had more free radical scavenging power than kojic acid. Generally, deferiprone topical treatment, accelerated wound healing more than kojic acid because of its higher antioxidant and iron chelation abilities.
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Affiliation(s)
- Mehrdad Mohammadpour
- Department of Medicinal Chemistry, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
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Massive Uterine Leiomyoma in a Patient with Friedreich's Ataxia: Is There a Possible Association? Case Rep Med 2011; 2011:648217. [PMID: 21869894 PMCID: PMC3159311 DOI: 10.1155/2011/648217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 06/24/2011] [Indexed: 11/18/2022] Open
Abstract
A possible association between Friedreich's ataxia (FA) and neoplastic development has been recognized. FA patients have low frataxin levels and insufficient response to oxidative stress. In these patients fibroblasts are characterized by a high rate of mutations. Herein, a case of a 39-year-old woman with FA tetraplegia, who was admitted in our department with intestinal obstruction due to a huge uterine tumor, is described. An abdominal CT revealed a huge intra-abdominal mass originating from the right cornu of the uterus. Tumor excision and adhesionlysis were performed. The histological examination of the tumor revealed a leiomyoma. FA patients seem to present with a variety of neoplasms uncommon for their young age. This is the first report of a leiomyoma originating from the genital system in a female patient with FA tetraplegia. Therefore it is important to identify neoplasms at an early stage in patients with FA and start immediate therapy.
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Armstrong JS, Khdour O, Hecht SM. Does oxidative stress contribute to the pathology of Friedreich's ataxia? A radical question. FASEB J 2010; 24:2152-63. [PMID: 20219987 DOI: 10.1096/fj.09-143222] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Friedreich's ataxia (FRDA) is a hereditary neurodegenerative disease that frequently culminates in cardiac failure at an early age. FRDA is believed to arise from reduced synthesis of the mitochondrial iron chaperone frataxin due to impaired gene transcription, which leads to mitochondrial iron accumulation, dysfunction of mitochondrial Fe-S containing enzymes, and increased Fenton-mediated free radical production. Recent reports have challenged this generally accepted hypothesis, by suggesting that the oxidative stress component in FRDA is minimal and thereby questioning the benefit of antioxidant therapeutic strategies. We suggest that this apparent paradox results from the radically divergent chemistries of the participating reactive oxygen species (ROS), the major cellular subcompartments involved and the overall cellular responses to ROS. In this review, we consider these factors and conclude that oxidative stress does constitute a major contributing factor to FRDA pathology. This reaffirms the idea that the rational design of specific small molecule multifunctional antioxidants will benefit FRDA patients.
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Affiliation(s)
- Jeffrey S Armstrong
- Center for BioEnergetics, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA.
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Abstract
Friedreich ataxia (FA) is a progressive genetic neurological disorder associated with degeneration of the dorsal columns, spinocerebellar tracts and other regions of the nervous system. The disorder results from mutations in the gene referred to as FXN. Almost all mutations are expansions of an intronic GAA repeat in this gene, which gives rise to decreased transcription of the gene product (called frataxin). Following these discoveries, drug discovery has moved at a rapid pace. Therapeutic trials in the next 5 years are expected to address amelioration of the effects of frataxin deficiency and methods for increasing frataxin expression. These therapies are directed at all levels of biochemical dysfunction in FA. Agents such as idebenone potentially improve mitochondrial function and decrease production of reactive oxygen species. Idebenone is presently in a phase III trial in the US and in Europe, with the primary outcome measure being neurological function. Deferiprone, an atypical iron chelator, may decrease build-up of toxic iron in the mitochondria in patients. It has entered a phase II trial in Europe, Australia and Canada directed toward improvement of neurological abilities. Finally, targeted histone deacetylase (HDAC) inhibitors and erythropoietin increase levels of frataxin when used in vitro, suggesting that they may provide methods for increasing frataxin levels in patients. Erythropoietin has been tested in a small phase II trial in Austria, while HDAC inhibitors are still at a preclinical stage. Symptomatic therapies are also in use for specific symptoms such as spasticity (baclofen). Thus, there is substantial optimism for development of new therapies for FA in the near future, and we suggest that one or several may be available over the next few years. However, continued development of new therapies will require creation of new, more sensitive measures for neurological dysfunction in FA, and clinically relevant measures of cardiac dysfunction.
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Affiliation(s)
- Amy Y Tsou
- Department of Neurology, University of Pennsylvania School of Medicine, and Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104-4318, USA
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15
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Paupe V, Dassa EP, Goncalves S, Auchère F, Lönn M, Holmgren A, Rustin P. Impaired nuclear Nrf2 translocation undermines the oxidative stress response in Friedreich ataxia. PLoS One 2009; 4:e4253. [PMID: 19158945 PMCID: PMC2617762 DOI: 10.1371/journal.pone.0004253] [Citation(s) in RCA: 164] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 12/15/2008] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Friedreich ataxia originates from a decrease in mitochondrial frataxin, which causes the death of a subset of neurons. The biochemical hallmarks of the disease include low activity of the iron sulfur cluster-containing proteins (ISP) and impairment of antioxidant defense mechanisms that may play a major role in disease progression. METHODOLOGY/PRINCIPAL FINDINGS We thus investigated signaling pathways involved in antioxidant defense mechanisms. We showed that cultured fibroblasts from patients with Friedreich ataxia exhibited hypersensitivity to oxidative insults because of an impairment in the Nrf2 signaling pathway, which led to faulty induction of antioxidant enzymes. This impairment originated from previously reported actin remodeling by hydrogen peroxide. CONCLUSIONS/SIGNIFICANCE Thus, the defective machinery for ISP synthesis by causing mitochondrial iron dysmetabolism increases hydrogen peroxide production that accounts for the increased susceptibility to oxidative stress.
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Affiliation(s)
- Vincent Paupe
- Inserm, U676, Hôpital Robert Debré, Bât. Ecran, Paris, France
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16
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Lavin MF, Gueven N, Grattan-Smith P. Defective responses to DNA single- and double-strand breaks in spinocerebellar ataxia. DNA Repair (Amst) 2008; 7:1061-76. [PMID: 18467193 DOI: 10.1016/j.dnarep.2008.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Failure to maintain the integrity of DNA/chromatin can result in genome instability and an increased risk of cancer. The description of a number of human genetic disorders characterised not only by cancer predisposition but by a broader phenotype including neurodegeneration suggests that maintaining genome stability is also important for preserving post-mitotic neurons. The identification of genes associated with other neurodegenerative disorders provides further evidence for the importance of DNA damage response and DNA repair genes in protecting against neurodegeneration. This theme is further developed in this review.
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Affiliation(s)
- Martin F Lavin
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia.
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17
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Popescu BFG, Pickering IJ, George GN, Nichol H. The chemical form of mitochondrial iron in Friedreich’s ataxia. J Inorg Biochem 2007; 101:957-66. [PMID: 17475338 DOI: 10.1016/j.jinorgbio.2007.03.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 03/09/2007] [Accepted: 03/14/2007] [Indexed: 01/08/2023]
Abstract
Friedreich's ataxia (FRDA) results from cellular damage caused by a deficiency in the mitochondrial matrix protein frataxin. To address the effect of frataxin deficiency on mitochondrial iron chemistry, the heavy mitochondrial fraction (HMF) was isolated from primary fibroblasts from FRDA affected and unaffected individuals. X-ray absorption spectroscopy was used to characterize the chemical form of iron. Near K-edge spectra were fitted with a series of model iron compounds to determine the proportion of each iron species. Most of the iron in both affected and unaffected fibroblasts was ferrihydrite. The iron K-edge from unaffected HMFs were best fitted with poorly organized ferrihydrite modeled by frataxin whereas HMFs from affected cells were best fitted with highly organized ferrihydrite modeled by ferritin. Both had several minor iron species but these did not differ consistently with disease. Since the iron K-edge spectra of ferritin and frataxin are very similar, we present additional evidence for the presence of ferritin-bound iron in HMF. The predominant ferritin subunit in HMFs from affected cells resembled mitochondrial ferritin (MtFt) in size and antigenicity. Western blotting of native gels showed that HMF from affected cells had 3-fold more holoferritin containing stainable iron. We conclude that most of the iron in fibroblast HMF from both affected and unaffected cells is ferrihydrite but only FRDA affected cells mineralize significant iron in mitochondrial ferritin.
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Affiliation(s)
- Bogdan F Gh Popescu
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, Canada S7N5E5
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18
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Simpkins JW, Dykens JA. Mitochondrial mechanisms of estrogen neuroprotection. ACTA ACUST UNITED AC 2007; 57:421-30. [PMID: 17512984 DOI: 10.1016/j.brainresrev.2007.04.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Revised: 04/20/2007] [Accepted: 04/21/2007] [Indexed: 11/19/2022]
Abstract
Oxidative stress, bioenergetic failure and mitochondrial dysfunction are all implicated in the etiology of neurodegenerative diseases such as Alzheimer's disease (AD). The mitochondrial involvement in neurodegenerative diseases reflects the regulatory role mitochondrial failure plays in both necrotic cell death and apoptosis. The potent feminizing hormone, 17 beta-estradiol (E2), is neuroprotective in a host of cell and animal models of stroke and neurodegenerative diseases. The discovery that 17alpha-estradiol, an isomer of E2, is equally as neuroprotective as E2 yet is >200-fold less active as a hormone, has permitted development of novel, more potent analogs where neuroprotection is independent of hormonal potency. Studies of structure-activity relationships and mitochondrial function have led to a mechanistic model in which these steroidal phenols intercalate into cell membranes where they block lipid peroxidation reactions, and are in turn recycled. Indeed, the parental estrogens and novel analogs stabilize mitochondria under Ca(2+) loading otherwise sufficient to collapse membrane potential. The neuroprotective and mitoprotective potencies for a series of estrogen analogs are significantly correlated, suggesting that these compounds prevent cell death in large measure by maintaining functionally intact mitochondria. This therapeutic strategy is germane not only to sudden mitochondrial failure in acute circumstances, such as during a stroke or myocardial infarction, but also to gradual mitochondrial dysfunction associated with chronic degenerative disorders such as AD.
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Affiliation(s)
- James W Simpkins
- Department of Pharmacology and Neuroscience, Institute for Aging and Alzheimer's Disease Research, University of North Texas Health Science Center, 3500 Camp Bowie Boul., Fort Worth, TX 76102, USA.
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Zarse K, Schulz TJ, Birringer M, Ristow M. Impaired respiration is positively correlated with decreased life span in Caenorhabditis elegans models of Friedreich Ataxia. FASEB J 2007; 21:1271-5. [PMID: 17215485 DOI: 10.1096/fj.06-6994com] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Impaired expression of mitochondrial genes causes alterations in life span of the nematode Caenorhabditis elegans. Intriguingly, although some of these genes have been shown to extend life expectancy and reduce aging processes, others are known to shorten life span in the same model organism. Reduced expression of a mitochondrial protein called frataxin causes a neurodegenerative disorder named Friedreich Ataxia, which decreases life span in humans. Surprisingly, reduced expression of the C. elegans frataxin homologue frh-1 has been associated with both increased as well as decreased life span by different laboratories. To further elucidate these conflicting findings, here we show that different RNA interference (RNAi) constructs directed against frh-1 reduce C. elegans life span. Moreover, we show that frh-1-inhibiting RNAi impairs oxygen consumption and that respiratory rate is positively correlated with life span in this multicellular eukaryote (r=0.8566), suggesting that >73% of life span variance in C. elegans is explained by changes in respiratory rate. Taken together, impaired mitochondrial metabolism due to RNAi-mediated inhibition of the frataxin homologue frh-1 causes both impaired respiration as well as decreased life span in the multicellular eukaryote C. elegans.
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Affiliation(s)
- Kim Zarse
- Department of Human Nutrition, Inst. of Nutrition, University of Jena, 29 Dornburger St., Jena D-07743, Germany
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20
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Alves R, Sorribas A. In silico pathway reconstruction: Iron-sulfur cluster biogenesis in Saccharomyces cerevisiae. BMC SYSTEMS BIOLOGY 2007; 1:10. [PMID: 17408500 PMCID: PMC1839888 DOI: 10.1186/1752-0509-1-10] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Accepted: 01/31/2007] [Indexed: 01/17/2023]
Abstract
Background Current advances in genomics, proteomics and other areas of molecular biology make the identification and reconstruction of novel pathways an emerging area of great interest. One such class of pathways is involved in the biogenesis of Iron-Sulfur Clusters (ISC). Results Our goal is the development of a new approach based on the use and combination of mathematical, theoretical and computational methods to identify the topology of a target network. In this approach, mathematical models play a central role for the evaluation of the alternative network structures that arise from literature data-mining, phylogenetic profiling, structural methods, and human curation. As a test case, we reconstruct the topology of the reaction and regulatory network for the mitochondrial ISC biogenesis pathway in S. cerevisiae. Predictions regarding how proteins act in ISC biogenesis are validated by comparison with published experimental results. For example, the predicted role of Arh1 and Yah1 and some of the interactions we predict for Grx5 both matches experimental evidence. A putative role for frataxin in directly regulating mitochondrial iron import is discarded from our analysis, which agrees with also published experimental results. Additionally, we propose a number of experiments for testing other predictions and further improve the identification of the network structure. Conclusion We propose and apply an iterative in silico procedure for predictive reconstruction of the network topology of metabolic pathways. The procedure combines structural bioinformatics tools and mathematical modeling techniques that allow the reconstruction of biochemical networks. Using the Iron Sulfur cluster biogenesis in S. cerevisiae as a test case we indicate how this procedure can be used to analyze and validate the network model against experimental results. Critical evaluation of the obtained results through this procedure allows devising new wet lab experiments to confirm its predictions or provide alternative explanations for further improving the models.
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Affiliation(s)
- Rui Alves
- Departament de Ciencies Mediques Basiques, Universidad de Lleida, Montserrat Roig 2, 25008 Lleida, Spain
| | - Albert Sorribas
- Departament de Ciencies Mediques Basiques, Universidad de Lleida, Montserrat Roig 2, 25008 Lleida, Spain
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Thierbach R, Schulz TJ, Isken F, Voigt A, Mietzner B, Drewes G, von Kleist-Retzow JC, Wiesner RJ, Magnuson MA, Puccio H, Pfeiffer AFH, Steinberg P, Ristow M. Targeted disruption of hepatic frataxin expression causes impaired mitochondrial function, decreased life span and tumor growth in mice. Hum Mol Genet 2005; 14:3857-64. [PMID: 16278235 DOI: 10.1093/hmg/ddi410] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We have disrupted expression of the mitochondrial Friedreich ataxia protein frataxin specifically in murine hepatocytes to generate mice with impaired mitochondrial function and decreased oxidative phosphorylation. These animals have a reduced life span and develop multiple hepatic tumors. Livers also show increased oxidative stress, impaired respiration and reduced ATP levels paralleled by reduced activity of iron-sulfur cluster (Fe/S) containing proteins (ISP), which all leads to increased hepatocyte turnover by promoting both apoptosis and proliferation. Accordingly, phosphorylation of the stress-inducible p38 MAP kinase was found to be specifically impaired following disruption of frataxin. Taken together, these findings indicate that frataxin may act as a mitochondrial tumor suppressor protein in mammals.
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Affiliation(s)
- René Thierbach
- German Institute of Human Nutrition Potsdam-Rehbrücke, Nuthetal-Berlin, and Charité University Medicine, Berlin, Germany
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22
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Bou-Abdallah F, Santambrogio P, Levi S, Arosio P, Chasteen ND. Unique Iron Binding and Oxidation Properties of Human Mitochondrial Ferritin: A Comparative Analysis with Human H-chain Ferritin. J Mol Biol 2005; 347:543-54. [PMID: 15755449 DOI: 10.1016/j.jmb.2005.01.007] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Revised: 12/17/2004] [Accepted: 01/03/2005] [Indexed: 11/20/2022]
Abstract
Ferritins are ubiquitous iron mineralizing and storage proteins that play an important role in iron homeostasis. Although excess iron is stored in the cytoplasm, most of the metabolically active iron is processed in the mitochondria of the cell. Little is known about how these organelles regulate iron homeostasis and toxicity. The recently discovered human mitochondrial ferritin (MtF), unlike other mammalian ferritins, is a homopolymer of 24 subunits that has a high degree of sequence homology with human H-chain ferritin (HuHF). Parallel experiments with MtF and HuHF reported here reveal striking differences in their iron oxidation and hydrolysis chemistry despite their similar diFe ferroxidase centers. In contrast to HuHF, MtF does not regenerate its ferroxidase activity after oxidation of its initial complement of Fe(II) and generally has considerably slower ferroxidation and mineralization activities as well. MtF exhibits sigmoidal kinetics of mineralization more characteristic of an L-chain than an H-chain ferritin. Site-directed mutagenesis reveals that serine 144, a residue situated near the ferroxidase center in MtF but absent from HuHF, is one player in this impairment of activity. Additionally only one-half of the 24 ferroxidase centers of MtF are functional, further contributing to its lower activity. Stopped-flow absorption spectrometry of Fe(II) oxidation by O(2) in MtF shows the formation of a transient diiron(III) mu-peroxo species (lambda(max) = 650 nm) as observed in HuHF. Also, as for HuHF, minimal hydroxyl radical is produced during the oxidative deposition of iron in MtF using O(2) as the oxidant. However, the 2Fe(II) + H(2)O(2) detoxification reaction found in HuHF does not occur in MtF. The structural differences and the physiological implications of the unique iron oxidation properties of MtF are discussed in light of these results.
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Affiliation(s)
- Fadi Bou-Abdallah
- Department of Chemistry, University of New Hampshire, Durham, NH 03824, USA.
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Wong CSM, Kwok JC, Richardson DR. PCTH: a novel orally active chelator of the aroylhydrazone class that induces iron excretion from mice. Biochim Biophys Acta Mol Basis Dis 2004; 1739:70-80. [PMID: 15607119 DOI: 10.1016/j.bbadis.2004.09.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2004] [Revised: 08/29/2004] [Accepted: 09/01/2004] [Indexed: 11/26/2022]
Abstract
beta-Thalassaemia major is an inherited blood disorder which is complicated by repeated blood transfusion and excessive gastrointestinal iron (Fe) absorption, which leads to toxic Fe overload. Current treatment using the chelator, desferrioxamine (DFO), is expensive and cumbersome since the drug requires long subcutaneous infusions and it is not orally active. A novel chelator, 2-pyridylcarboxaldehyde 2-thiophenecarboxyl hydrazone (PCTH), was recently designed and shown to have high Fe chelation efficacy in vitro. The aim of this investigation was to examine the Fe chelation efficacy of PCTH in vitro implementing primary cultures of cardiomyocytes and in vivo using mice. We showed that PCTH was significantly (P<0.005) more effective than DFO at mobilising (59)Fe from prelabelled cardiomyocytes. Moreover, PCTH prevented the incorporation of (59)Fe into ferritin during Fe uptake from (59)Fe-labelled transferrin. These effects were important to assess as cardiac complications caused by Fe deposition are a major cause of death in beta-thalassaemia major patients. Further studies showed that PCTH was orally active and well tolerated by mice at doses ranging from 50 to 200 mg/kg, twice daily (bd), for 2 days. A dose-dependent increase in faecal (59)Fe excretion was observed in the PCTH-treated group. This level of Fe excretion at 200 mg/kg was similar to the same dose of the orally effective chelators, pyridoxal isonicotinoyl hydrazone (PIH) and deferiprone (L1). Effective Fe chelation in the liver by PCTH was shown via its ability to reduce ferritin-(59)Fe accumulation. Mice treated for 3 weeks with PCTH at doses of 50 and 100 mg/kg/bd showed no overt signs of toxicity as determined by weight loss and a range of biochemical and haematological indices. In subchronic Fe excretion studies over 3 weeks, PIH and PCTH at 75 mg/kg/bd for 5 days/week increased faecal (59)Fe excretion to 140% and 145% of the vehicle control, respectively. This study showed that PCTH was well tolerated at 100 mg/kg/bd and induced considerable Fe excretion by the oral route, suggesting its potential as a candidate to replace DFO.
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Affiliation(s)
- C S M Wong
- Iron Metabolism and Chelation Program, Children's Cancer Institute Australia for Medical Research, PO Box 81, High St, Randwick, Sydney, New South Wales 2031, Australia
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