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Shen MM, Rummey C, Lynch DR. Phenotypic variation of FXN compound heterozygotes in a Friedreich ataxia cohort. Ann Clin Transl Neurol 2024; 11:1110-1121. [PMID: 38396238 PMCID: PMC11093247 DOI: 10.1002/acn3.52027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/24/2024] [Accepted: 02/09/2024] [Indexed: 02/25/2024] Open
Abstract
OBJECTIVE Most individuals with Friedreich ataxia (FRDA) have homozygous GAA triplet repeat expansions in the FXN gene, correlating with a typical phenotype of ataxia and cardiomyopathy. A minority are compound heterozygotes carrying a GAA expansion on one allele and a mutation on the other. The study aim was to examine phenotypic variation among compound heterozygotes. METHODS Data on FXN mutations were obtained from the Friedreich Ataxia Clinical Outcome Measures Study (FA-COMS). We compared clinical features in a single-site FA-COMS cohort of 51 compound heterozygous and 358 homozygous patients, including quantitative measures of cardiac, neurologic, and visual disease progression. RESULTS Non-GAA repeat mutations were associated with reduced cardiac disease, and patients with minimal/no function mutations otherwise had a typical FRDA phenotype but with significantly more severe progression. The partial function mutation group was characterized by relative sparing of bulbar and upper limb function, as well as particularly low cardiac involvement. Other clinical features in this group, including optic atrophy and diabetes mellitus, varied widely depending on the specific type of partial function mutation. INTERPRETATION These data support that the typical FRDA phenotype is driven by frataxin deficiency, especially severe in compound heterozygotes with minimal/no function mutations, whereas the heterogeneous presentations of those with partial function mutations may indicate other contributing factors to FRDA pathogenesis.
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Affiliation(s)
- Megan M. Shen
- Division of NeurologyThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
- Perelman School of Medicine, University of Pennsylvania.PhiladelphiaPennsylvaniaUSA
| | | | - David R. Lynch
- Division of NeurologyThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
- Perelman School of Medicine, University of Pennsylvania.PhiladelphiaPennsylvaniaUSA
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2
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Krasilnikova MM, Humphries CL, Shinsky EM. Friedreich's ataxia: new insights. Emerg Top Life Sci 2023; 7:313-323. [PMID: 37698160 DOI: 10.1042/etls20230017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/09/2023] [Accepted: 08/29/2023] [Indexed: 09/13/2023]
Abstract
Friedreich ataxia (FRDA) is an inherited disease that is typically caused by GAA repeat expansion within the first intron of the FXN gene coding for frataxin. This results in the frataxin deficiency that affects mostly muscle, nervous, and cardiovascular systems with progressive worsening of the symptoms over the years. This review summarizes recent progress that was achieved in understanding of molecular mechanism of the disease over the last few years and latest treatment strategies focused on overcoming the frataxin deficiency.
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Affiliation(s)
- Maria M Krasilnikova
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, U.S.A
| | - Casey L Humphries
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, U.S.A
| | - Emily M Shinsky
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, U.S.A
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3
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Phenotype and management of neurologic intronic repeat disorders (NIRDs). Rev Neurol (Paris) 2023; 179:173-182. [PMID: 36371266 DOI: 10.1016/j.neurol.2022.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 09/15/2022] [Accepted: 09/20/2022] [Indexed: 11/11/2022]
Abstract
During recent years an increasing number of neurologic disorders due to expanded tri-, tetra-, penta-, or hexa-nucleotide repeat motifs in introns of various genes have been described (neurologic intronic repeat disorders (NIRDs)). The repeat may be pathogenic in the heterozygous or homozygous form. Repeat lengths vary considerably and can be stable or unstable during transmission to the next generation. The most well-known NIRDs are Friedreich ataxia, spinocerebellar ataxia types-10, -31, and -36, CANVAS, C9Orf72 familial amyotrophic lateral sclerosis (fALS), and myotonic dystrophy-2 (MD2). Phenotypically, NIRDs manifest as mono-organ (e.g. spinocerebellar ataxia type 31) or multi-organ disease (e.g. Friedreich ataxia, myotonic dystrophy-2). A number of other more rare NIRDs have been recently detected. This review aims at summarising and discussing previous findings and recent advances concerning the etiology, pathophysiology, clinical presentation, and therapeutic management of the most common NIRDs.
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4
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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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5
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Fichera M, Castaldo A, Mongelli A, Marchini G, Gellera C, Nanetti L, Mariotti C. Comorbidities in Friedreich ataxia: incidence and manifestations from early to advanced disease stages. Neurol Sci 2022; 43:6831-6838. [DOI: 10.1007/s10072-022-06360-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/18/2022] [Indexed: 11/24/2022]
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6
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Kelekçi S, Yıldız AB, Sevinç K, Çimen DU, Önder T. Perspectives on current models of Friedreich’s ataxia. Front Cell Dev Biol 2022; 10:958398. [PMID: 36036008 PMCID: PMC9403045 DOI: 10.3389/fcell.2022.958398] [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: 05/31/2022] [Accepted: 07/13/2022] [Indexed: 11/13/2022] Open
Abstract
Friedreich’s ataxia (FRDA, OMIM#229300) is the most common hereditary ataxia, resulting from the reduction of frataxin protein levels due to the expansion of GAA repeats in the first intron of the FXN gene. Why the triplet repeat expansion causes a decrease in Frataxin protein levels is not entirely known. Generation of effective FRDA disease models is crucial for answering questions regarding the pathophysiology of this disease. There have been considerable efforts to generate in vitro and in vivo models of FRDA. In this perspective article, we highlight studies conducted using FRDA animal models, patient-derived materials, and particularly induced pluripotent stem cell (iPSC)-derived models. We discuss the current challenges in using FRDA animal models and patient-derived cells. Additionally, we provide a brief overview of how iPSC-based models of FRDA were used to investigate the main pathways involved in disease progression and to screen for potential therapeutic agents for FRDA. The specific focus of this perspective article is to discuss the outlook and the remaining challenges in the context of FRDA iPSC-based models.
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Affiliation(s)
| | | | | | | | - Tamer Önder
- *Correspondence: Simge Kelekçi, , ; Tamer Önder,
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7
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Abeti R, Jasoliya M, Al-Mahdawi S, Pook M, Gonzalez-Robles C, Hui CK, Cortopassi G, Giunti P. A Drug Combination Rescues Frataxin-Dependent Neural and Cardiac Pathophysiology in FA Models. Front Mol Biosci 2022; 9:830650. [PMID: 35664670 PMCID: PMC9160322 DOI: 10.3389/fmolb.2022.830650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 03/17/2022] [Indexed: 11/22/2022] Open
Abstract
Friedreich’s ataxia (FA) is an inherited multisystemic neuro- and cardio-degenerative disorder. Seventy-four clinical trials are listed for FA (including past and present), but none are considered FDA/EMA-approved therapy. To date, FA therapeutic strategies have focused along two main lines using a single-drug approach: a) increasing frataxin and b) enhancing downstream pathways, including antioxidant levels and mitochondrial function. Our novel strategy employed a combinatorial approach to screen approved compounds to determine if a combination of molecules provided an additive or synergistic benefit to FA cells and/or animal models. Eight single drug molecules were administered to FA fibroblast patient cells: nicotinamide riboside, hemin, betamethasone, resveratrol, epicatechin, histone deacetylase inhibitor 109, methylene blue, and dimethyl fumarate. We measured their individual ability to induce FXN transcription and mitochondrial biogenesis in patient cells. Single-drug testing highlighted that dimethyl fumarate and resveratrol increased these two parameters. In addition, the simultaneous administration of these two drugs was the most effective in terms of FXN mRNA and mitobiogenesis increase. Interestingly, this combination also improved mitochondrial functions and reduced reactive oxygen species in neurons and cardiomyocytes. Behavioral tests in an FA mouse model treated with dimethyl fumarate and resveratrol demonstrated improved rotarod performance. Our data suggest that dimethyl fumarate is effective as a single agent, and the addition of resveratrol provides further benefit in some assays without showing toxicity. Therefore, they could be a valuable combination to counteract FA pathophysiology. Further studies will help fully understand the potential of a combined therapeutic strategy in FA pathophysiology.
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Affiliation(s)
- Rosella Abeti
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL, Institute of Neurology, London, United Kingdom
- *Correspondence: Rosella Abeti, ; Paola Giunti,
| | - Mittal Jasoliya
- Department of Molecular Biosciences, School of Veterinary Medicine, UC Davis, Davis, CA, United States
| | - Sahar Al-Mahdawi
- Department of Life Sciences, Institute of Environment, Health, and Societies, College of Health and Life Sciences, Division of Biosciences, Brunel University London, Uxbridge, United Kingdom
| | - Mark Pook
- Department of Life Sciences, Institute of Environment, Health, and Societies, College of Health and Life Sciences, Division of Biosciences, Brunel University London, Uxbridge, United Kingdom
| | - Cristina Gonzalez-Robles
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL, Institute of Neurology, London, United Kingdom
| | - Chun Kiu Hui
- Department of Molecular Biosciences, School of Veterinary Medicine, UC Davis, Davis, CA, United States
| | - Gino Cortopassi
- Department of Molecular Biosciences, School of Veterinary Medicine, UC Davis, Davis, CA, United States
| | - Paola Giunti
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL, Institute of Neurology, London, United Kingdom
- *Correspondence: Rosella Abeti, ; Paola Giunti,
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8
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Wang Q, Laboureur L, Weng L, Eskenazi NM, Hauser LA, Mesaros C, Lynch DR, Blair IA. Simultaneous Quantification of Mitochondrial Mature Frataxin and Extra-Mitochondrial Frataxin Isoform E in Friedreich’s Ataxia Blood. Front Neurosci 2022; 16:874768. [PMID: 35573317 PMCID: PMC9098139 DOI: 10.3389/fnins.2022.874768] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 03/22/2022] [Indexed: 11/25/2022] Open
Abstract
Friedreich’s ataxia (FRDA) is an autosomal recessive disease caused by an intronic guanine-adenine-adenine (GAA) triplet expansion in the frataxin (FXN) gene, which leads to reduced expression of full-length frataxin (1–210) also known as isoform 1. Full-length frataxin has a mitochondrial targeting sequence, which facilitates its translocation into mitochondria where it is processed through cleavage at G41-L42 and K80-S81 by mitochondrial processing (MPP) to release mitochondrial mature frataxin (81–210). Alternative splicing of FXN also leads to expression of N-terminally acetylated extra-mitochondrial frataxin (76–210) named isoform E because it was discovered in erythrocytes. Frataxin isoforms are undetectable in serum or plasma, and originally whole blood could not be used as a biomarker in brief therapeutic trials because it is present in erythrocytes, which have a half-life of 115-days and so frataxin levels would remain unaltered. Therefore, an assay was developed for analyzing frataxin in platelets, which have a half-life of only 10-days. However, our discovery that isoform E is only present in erythrocytes, whereas, mature frataxin is present primarily in short-lived peripheral blood mononuclear cells (PBMCs), granulocytes, and platelets, meant that both proteins could be quantified in whole blood samples. We now report a quantitative assay for frataxin proteoforms in whole blood from healthy controls and FRDA patients. The assay is based on stable isotope dilution coupled with immunoprecipitation (IP) and two-dimensional-nano-ultrahigh performance liquid chromatography/parallel reaction monitoring/high resolution mass spectrometry (2D-nano-UHPLC-PRM/HRMS). The lower limit of quantification was 0.5 ng/mL for each proteoform and the assays had 100% sensitivity and specificity for discriminating between healthy controls (n = 11) and FRDA cases (N = 100 in year-1, N = 22 in year-2,3). The mean levels of mature frataxin in whole blood from healthy controls and homozygous FRDA patients were significantly different (p < 0.0001) at 7.5 ± 1.5 ng/mL and 2.1 ± 1.2 ng/mL, respectively. The mean levels of isoform E in whole blood from healthy controls and homozygous FRDA patients were significantly different (p < 0.0001) at 26.8 ± 4.1 ng/mL and 4.7 ± 3.3 ng/mL, respectively. The mean levels of total frataxin in whole blood from healthy controls and homozygous FRDA patients were significantly different (p < 0.0001) at 34.2 ± 4.3 ng/mL and 6.8 ± 4.0 ng/mL, respectively. The assay will make it possible to rigorously monitor the natural history of the disease and explore the potential role of isoform E in etiology of the disease. It will also facilitate the assessment of therapeutic interventions (including gene therapy approaches) that attempt to increase frataxin protein expression as a treatment for this devastating disease.
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Affiliation(s)
- Qingqing Wang
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
| | - Laurent Laboureur
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
| | - Liwei Weng
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
| | - Nicolas M. Eskenazi
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
| | - Lauren A. Hauser
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA, United States
- Departments of Pediatrics and Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Clementina Mesaros
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
| | - David R. Lynch
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA, United States
- Departments of Pediatrics and Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Ian A. Blair
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
- *Correspondence: Ian A. Blair,
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9
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Saveri P, Magri S, Maderna E, Balistreri F, Lombardi R, Ciano C, Moda F, Garavaglia B, Reale C, Lauria Pinter G, Taroni F, Pareyson D, Pisciotta C. DNAJB2-related CMT2: Pathomechanism insights and phenotypic spectrum widening. Eur J Neurol 2022; 29:2056-2065. [PMID: 35286755 PMCID: PMC9314055 DOI: 10.1111/ene.15326] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 02/14/2022] [Accepted: 03/09/2022] [Indexed: 11/29/2022]
Abstract
Background and purpose Mutations in DNAJB2 are associated with autosomal recessive hereditary motor neuropathies/ Charcot‐Marie‐Tooth disease type 2 (CMT2). We describe an Italian family with CMT2 due to a homozygous DNAJB2 mutation and provide insight into the pathomechanisms. Methods Patients with DNAJB2 mutations were characterized clinically, electrophysiologically and by means of skin biopsy. mRNA and protein levels were studied in lymphoblastoid cells (LCLs) from patients and controls. Results Three affected siblings were found to carry a homozygous DNAJB2 null mutation segregating with the disease. The disease manifested in the second to third decade of life. Clinical examination showed severe weakness of the thigh muscles and complete loss of movement in the foot and leg muscles. Sensation was reduced in the lower limbs. All patients had severe hearing loss and the proband also had Parkinson’s disease (PD). Nerve conduction studies showed an axonal motor and sensory length‐dependent polyneuropathy. DNAJB2 expression studies revealed reduced mRNA levels and the absence of the protein in the homozygous subject in both LCLs and skin biopsy. Interestingly, we detected phospho‐alpha‐synuclein deposits in the proband, as already seen in PD patients, and demonstrated TDP‐43 accumulation in patients’ skin. Conclusions Our results broaden the clinical spectrum of DNAJB2‐related neuropathies and provide evidence that DNAJB2 mutations should be taken into account as another causative gene of CMT2 with hearing loss and parkinsonism. The mutation likely acts through a loss‐of‐function mechanism, leading to toxic protein aggregation such as TDP‐43. The associated parkinsonism resembles the classic PD form with the addition of abnormal accumulation of phospho‐alpha‐synuclein.
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Affiliation(s)
- Paola Saveri
- Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Stefania Magri
- Department of Diagnostics and Applied Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Emanuela Maderna
- Department of Diagnostics and Applied Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Francesca Balistreri
- Department of Diagnostics and Applied Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Raffaella Lombardi
- Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Claudia Ciano
- Department of Diagnostics and Applied Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Fabio Moda
- Department of Diagnostics and Applied Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Barbara Garavaglia
- Department of Diagnostics and Applied Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Chiara Reale
- Department of Diagnostics and Applied Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Giuseppe Lauria Pinter
- Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.,Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Franco Taroni
- Department of Diagnostics and Applied Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Davide Pareyson
- Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Chiara Pisciotta
- Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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10
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Huichalaf C, Perfitt TL, Kuperman A, Gooch R, Kovi RC, Brenneman KA, Chen X, Hirenallur-Shanthappa D, Ma T, Assaf BT, Pardo I, Franks T, Monarski L, Cheng TW, Le K, Su C, Somanathan S, Whiteley LO, Bulawa C, Pregel MJ, Martelli A. In vivo overexpression of frataxin causes toxicity mediated by iron-sulfur cluster deficiency. Mol Ther Methods Clin Dev 2022; 24:367-378. [PMID: 35252470 PMCID: PMC8866050 DOI: 10.1016/j.omtm.2022.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 02/04/2022] [Indexed: 12/25/2022]
Abstract
Friedreich's ataxia is a rare disorder resulting from deficiency of frataxin, a mitochondrial protein implicated in the synthesis of iron-sulfur clusters. Preclinical studies in mice have shown that gene therapy is a promising approach to treat individuals with Friedreich's ataxia. However, a recent report provided evidence that AAVrh10-mediated overexpression of frataxin could lead to cardiotoxicity associated with mitochondrial dysfunction. While evaluating an AAV9-based frataxin gene therapy using a chicken β-actin promoter, we showed that toxic overexpression of frataxin could be reached in mouse liver and heart with doses between 1 × 1013 and 1 × 1014 vg/kg. In a mouse model of cardiac disease, these doses only corrected cardiac dysfunction partially and transiently and led to adverse findings associated with iron-sulfur cluster deficiency in liver. We demonstrated that toxicity required frataxin's primary function by using a frataxin construct bearing the N146K mutation, which impairs binding to the iron-sulfur cluster core complex. At the lowest tested dose, we observed moderate liver toxicity that was accompanied by progressive loss of transgene expression and liver regeneration. Together, our data provide insights into the toxicity of frataxin overexpression that should be considered in the development of a gene therapy approach for Friedreich's ataxia.
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Affiliation(s)
- Claudia Huichalaf
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Tyler L Perfitt
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Anna Kuperman
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Renea Gooch
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Ramesh C Kovi
- Drug Safety Research and Development, Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Karrie A Brenneman
- Drug Safety Research and Development, Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Xian Chen
- Comparative Medicine, Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | | | - Tiffany Ma
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Basel T Assaf
- Drug Safety Research and Development, Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Ingrid Pardo
- Drug Safety Research and Development, Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Tania Franks
- Drug Safety Research and Development, Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Laura Monarski
- Drug Safety Research and Development, Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Ting-Wen Cheng
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Kevin Le
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Chunyan Su
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Suryanarayan Somanathan
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Laurence O Whiteley
- Drug Safety Research and Development, Worldwide Research, Development and Medical, Pfizer Inc., Cambridge, MA 02139, USA
| | - Christine Bulawa
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Marko J Pregel
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
| | - Alain Martelli
- Rare Disease Research Unit, Worldwide Research, Development and Medical, Pfizer Inc., 610 Main Street, Cambridge, MA 02139, USA
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11
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Puglisi R. Protein Mutations and Stability, a Link with Disease: The Case Study of Frataxin. Biomedicines 2022; 10:biomedicines10020425. [PMID: 35203634 PMCID: PMC8962269 DOI: 10.3390/biomedicines10020425] [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: 12/28/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 11/16/2022] Open
Abstract
Protein mutations may lead to pathologies by causing protein misfunction or propensity to degradation. For this reason, several studies have been performed over the years to determine the capability of proteins to retain their native conformation under stress condition as well as factors to explain protein stabilization and the mechanisms behind unfolding. In this review, we explore the paradigmatic example of frataxin, an iron binding protein involved in Fe–S cluster biogenesis, and whose impairment causes a neurodegenerative disease called Friedreich’s Ataxia (FRDA). We summarize what is known about most common point mutations identified so far in heterozygous FRDA patients, their effects on frataxin structure and function and the consequences of its binding with partners.
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Affiliation(s)
- Rita Puglisi
- UK Dementia Research Institute at the Wohl Institute of King's College London, London SE59RT, UK
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12
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Cheng R, Dhorajia VV, Kim J, Kim Y. Mitochondrial iron metabolism and neurodegenerative diseases. Neurotoxicology 2022; 88:88-101. [PMID: 34748789 PMCID: PMC8748425 DOI: 10.1016/j.neuro.2021.11.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 11/01/2021] [Accepted: 11/03/2021] [Indexed: 01/03/2023]
Abstract
Iron is a key element for mitochondrial function and homeostasis, which is also crucial for maintaining the neuronal system, but too much iron promotes oxidative stress. A large body of evidence has indicated that abnormal iron accumulation in the brain is associated with various neurodegenerative diseases such as Huntington's disease, Alzheimer's disease, Parkinson's disease, and Friedreich's ataxia. However, it is still unclear how irregular iron status contributes to the development of neuronal disorders. Hence, the current review provides an update on the causal effects of iron overload in the development and progression of neurodegenerative diseases and discusses important roles of mitochondrial iron homeostasis in these disease conditions. Furthermore, this review discusses potential therapeutic targets for the treatments of iron overload-linked neurodegenerative diseases.
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Affiliation(s)
- Ruiying Cheng
- Department of Biomedical and Nutritional Sciences, University of Massachusetts Lowell, USA
| | | | - Jonghan Kim
- Department of Biomedical and Nutritional Sciences, University of Massachusetts Lowell, USA.
| | - Yuho Kim
- Department of Physical Therapy and Kinesiology, University of Massachusetts Lowell, USA.
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13
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Brown AF, Parkinson MH, Garcia-Moreno H, Mudanohwo E, Labrum R, Sweeney M, Giunti P. Friedreich's Ataxia Frequency in a Large Cohort of Genetically Undetermined Ataxia Patients. Front Neurol 2021; 12:736253. [PMID: 34956042 PMCID: PMC8697107 DOI: 10.3389/fneur.2021.736253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Accepted: 10/19/2021] [Indexed: 11/25/2022] Open
Abstract
Background: Patients with suspected genetic ataxia are often tested for Friedreich's ataxia (FRDA) and/or a variety of spinocerebellar ataxias (SCAs). FRDA can present with atypical, late-onset forms and so may be missed in the diagnostic process. We aimed to determine FRDA-positive subjects among two cohorts of patients referred to a specialist ataxia centre either for FRDA or SCA testing to determine the proportion of FRDA cases missed in the diagnostic screening process. Methods: 2000 SCA-negative ataxia patients, not previously referred for FRDA testing (group A), were tested for FRDA expansions and mutations. This group was compared with 1768 ataxia patients who had been previously referred for FRDA testing (group B) and were therefore more likely to have a typical presentation. The phenotypes of positive cases were assessed through review of the clinical case notes. Results: Three patients (0.2%) in group A had the FRDA expansion on both alleles, compared with 207 patients (11.7%) in group B. The heterozygous carrier rate across both cohorts was of 41 out of 3,768 cases (1.1%). The size of the expansions in the three FRDA-positive cases in group A was small, and their presentation atypical with late-onset. Conclusions: This study demonstrates that FRDA is very rare among patients who were referred purely for SCA testing without the clinical suspicion of FRDA. Such cases should be referred to specialist ataxia centres for more extensive testing to improve patient management and outcomes.
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Affiliation(s)
- Alexander F. Brown
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London, United Kingdom
| | - Michael H. Parkinson
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London, United Kingdom
| | - Hector Garcia-Moreno
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London, United Kingdom
| | - Ese Mudanohwo
- Neurogenetics Unit, National Hospital for Neurology & Neurosurgery, University College London Hospitals, Queen Square, London, United Kingdom
| | - Robyn Labrum
- Neurogenetics Unit, National Hospital for Neurology & Neurosurgery, University College London Hospitals, Queen Square, London, United Kingdom
| | - Mary Sweeney
- Neurogenetics Unit, National Hospital for Neurology & Neurosurgery, University College London Hospitals, Queen Square, London, United Kingdom
| | - Paola Giunti
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London, United Kingdom
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14
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Doni D, Meggiolaro M, Santos J, Audran G, Marque SRA, Costantini P, Bortolus M, Carbonera D. A Combined Spectroscopic and In Silico Approach to Evaluate the Interaction of Human Frataxin with Mitochondrial Superoxide Dismutase. Biomedicines 2021; 9:biomedicines9121763. [PMID: 34944579 PMCID: PMC8698469 DOI: 10.3390/biomedicines9121763] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 11/15/2021] [Accepted: 11/22/2021] [Indexed: 11/23/2022] Open
Abstract
Frataxin (FXN) is a highly conserved mitochondrial protein whose deficiency causes Friedreich’s ataxia, a neurodegenerative disease. The precise physiological function of FXN is still unclear; however, there is experimental evidence that the protein is involved in biosynthetic iron–sulfur cluster machinery, redox imbalance, and iron homeostasis. FXN is synthesized in the cytosol and imported into the mitochondria, where it is proteolytically cleaved to the mature form. Its involvement in the redox imbalance suggests that FXN could interact with mitochondrial superoxide dismutase (SOD2), a key enzyme in antioxidant cellular defense. In this work, we use site-directed spin labelling coupled to electron paramagnetic resonance spectroscopy (SDSL-EPR) and fluorescence quenching experiments to investigate the interaction between human FXN and SOD2 in vitro. Spectroscopic data are combined with rigid body protein–protein docking to assess the potential structure of the FXN-SOD2 complex, which leaves the metal binding region of FXN accessible to the solvent. We provide evidence that human FXN interacts with human SOD2 in vitro and that the complex is in fast exchange. This interaction could be relevant during the assembly of iron-sulfur (FeS) clusters and/or their incorporation in proteins when FeS clusters are potentially susceptible to attacks by reactive oxygen species.
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Affiliation(s)
- Davide Doni
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy; (D.D.); (M.M.); (P.C.)
| | - Marta Meggiolaro
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy; (D.D.); (M.M.); (P.C.)
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy;
| | - Javier Santos
- Instituto de Biociencias, Biotecnología y Biología Traslacional (iB3), Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Buenos Aires C1428EGA, Argentina;
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Buenos Aires C1428EGA, Argentina
| | - Gérard Audran
- Aix Marseille Universitè, CNRS, ICR, UMR 7273, case 551, Ave Escadrille Normandie Niemen, CEDEX 20, 13397 Marseille, France; (G.A.); (S.R.A.M.)
| | - Sylvain R. A. Marque
- Aix Marseille Universitè, CNRS, ICR, UMR 7273, case 551, Ave Escadrille Normandie Niemen, CEDEX 20, 13397 Marseille, France; (G.A.); (S.R.A.M.)
| | - Paola Costantini
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy; (D.D.); (M.M.); (P.C.)
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy;
- Correspondence:
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy;
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15
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Dietz JV, Fox JL, Khalimonchuk O. Down the Iron Path: Mitochondrial Iron Homeostasis and Beyond. Cells 2021; 10:cells10092198. [PMID: 34571846 PMCID: PMC8468894 DOI: 10.3390/cells10092198] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 08/22/2021] [Accepted: 08/23/2021] [Indexed: 12/20/2022] Open
Abstract
Cellular iron homeostasis and mitochondrial iron homeostasis are interdependent. Mitochondria must import iron to form iron–sulfur clusters and heme, and to incorporate these cofactors along with iron ions into mitochondrial proteins that support essential functions, including cellular respiration. In turn, mitochondria supply the cell with heme and enable the biogenesis of cytosolic and nuclear proteins containing iron–sulfur clusters. Impairment in cellular or mitochondrial iron homeostasis is deleterious and can result in numerous human diseases. Due to its reactivity, iron is stored and trafficked through the body, intracellularly, and within mitochondria via carefully orchestrated processes. Here, we focus on describing the processes of and components involved in mitochondrial iron trafficking and storage, as well as mitochondrial iron–sulfur cluster biogenesis and heme biosynthesis. Recent findings and the most pressing topics for future research are highlighted.
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Affiliation(s)
- Jonathan V. Dietz
- Department of Biochemistry, University of Nebraska, Lincoln, NE 68588, USA;
| | - Jennifer L. Fox
- Department of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424, USA;
| | - Oleh Khalimonchuk
- Department of Biochemistry, University of Nebraska, Lincoln, NE 68588, USA;
- Nebraska Redox Biology Center, University of Nebraska, Lincoln, NE 68588, USA
- Fred and Pamela Buffett Cancer Center, Omaha, NE 68198, USA
- Correspondence:
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16
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Doni D, Rigoni G, Palumbo E, Baschiera E, Peruzzo R, De Rosa E, Caicci F, Passerini L, Bettio D, Russo A, Szabò I, Soriano ME, Salviati L, Costantini P. The displacement of frataxin from the mitochondrial cristae correlates with abnormal respiratory supercomplexes formation and bioenergetic defects in cells of Friedreich ataxia patients. FASEB J 2021; 35:e21362. [PMID: 33629768 DOI: 10.1096/fj.202000524rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 12/09/2020] [Accepted: 12/28/2020] [Indexed: 12/23/2022]
Abstract
Friedreich ataxia (FRDA) is a neurodegenerative disease resulting from a severe decrease of frataxin (FXN). Most patients carry a GAA repeat expansion in both alleles of the FXN gene, whereas a small fraction of them are compound heterozygous for the expansion and a point mutation in the other allele. FXN is involved in the mitochondrial biogenesis of the FeS-clusters. Distinctive feature of FRDA patient cells is an impaired cellular respiration, likely due to a deficit of key redox cofactors working as electrons shuttles through the respiratory chain. However, a definite relationship between FXN levels, FeS-clusters assembly dysregulation and bioenergetics failure has not been established. In this work, we performed a comparative analysis of the mitochondrial phenotype of cell lines from FRDA patients, either homozygous for the expansion or compound heterozygotes for the G130V mutation. We found that, in healthy cells, FXN and two key proteins of the FeS-cluster assembly machinery are enriched in mitochondrial cristae, the dynamic subcompartment housing the respiratory chain. On the contrary, FXN widely redistributes to the matrix in FRDA cells with defects in respiratory supercomplexes assembly and altered respiratory function. We propose that this could be relevant for the early mitochondrial defects afflicting FRDA cells and that perturbation of mitochondrial morphodynamics could in turn be critical in terms of disease mechanisms.
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Affiliation(s)
- Davide Doni
- Department of Biology, University of Padova, Padova, Italy
| | | | - Elisa Palumbo
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Elisa Baschiera
- Clinical Genetics Unit, Department of Women's and Children's Health, University of Padova, Padova, Italy
- Istituto di Ricerca Pediatrica (IRP) Città della Speranza, Padova, Italy
| | | | - Edith De Rosa
- Department of Biology, University of Padova, Padova, Italy
| | | | | | - Daniela Bettio
- Clinical Genetics Unit, Department of Women's and Children's Health, University of Padova, Padova, Italy
- Istituto di Ricerca Pediatrica (IRP) Città della Speranza, Padova, Italy
| | - Antonella Russo
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Ildiko Szabò
- Department of Biology, University of Padova, Padova, Italy
| | | | - Leonardo Salviati
- Clinical Genetics Unit, Department of Women's and Children's Health, University of Padova, Padova, Italy
- Istituto di Ricerca Pediatrica (IRP) Città della Speranza, Padova, Italy
- Myology Center, University of Padova, Padova, Italy
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17
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Doni D, Passerini L, Audran G, Marque SRA, Schulz M, Santos J, Costantini P, Bortolus M, Carbonera D. Effects of Fe 2+/Fe 3+ Binding to Human Frataxin and Its D122Y Variant, as Revealed by Site-Directed Spin Labeling (SDSL) EPR Complemented by Fluorescence and Circular Dichroism Spectroscopies. Int J Mol Sci 2020; 21:E9619. [PMID: 33348670 PMCID: PMC7766144 DOI: 10.3390/ijms21249619] [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: 11/14/2020] [Revised: 12/11/2020] [Accepted: 12/15/2020] [Indexed: 12/17/2022] Open
Abstract
Frataxin is a highly conserved protein whose deficiency results in the neurodegenerative disease Friederich's ataxia. Frataxin's actual physiological function has been debated for a long time without reaching a general agreement; however, it is commonly accepted that the protein is involved in the biosynthetic iron-sulphur cluster (ISC) machinery, and several authors have pointed out that it also participates in iron homeostasis. In this work, we use site-directed spin labeling coupled to electron paramagnetic resonance (SDSL EPR) to add new information on the effects of ferric and ferrous iron binding on the properties of human frataxin in vitro. Using SDSL EPR and relating the results to fluorescence experiments commonly performed to study iron binding to FXN, we produced evidence that ferric iron causes reversible aggregation without preferred interfaces in a concentration-dependent fashion, starting at relatively low concentrations (micromolar range), whereas ferrous iron binds without inducing aggregation. Moreover, our experiments show that the ferrous binding does not lead to changes of protein conformation. The data reported in this study reveal that the currently reported binding stoichiometries should be taken with caution. The use of a spin label resistant to reduction, as well as the comparison of the binding effect of Fe2+ in wild type and in the pathological D122Y variant of frataxin, allowed us to characterize the Fe2+ binding properties of different protein sites and highlight the effect of the D122Y substitution on the surrounding residues. We suggest that both Fe2+ and Fe3+ might play a relevant role in the context of the proposed FXN physiological functions.
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Affiliation(s)
- Davide Doni
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy; (D.D.); (P.C.)
| | - Leonardo Passerini
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (L.P.); (D.C.)
| | - Gérard Audran
- Institut de Chimie Radicalaire, Aix Marseille Universitè, CNRS, ICR, UMR 7273, Case 551, Ave Escadrille Normandie Niemen, CEDEX 20, 13397 Marseille, France; (G.A.); (S.R.A.M.); (M.S.)
| | - Sylvain R. A. Marque
- Institut de Chimie Radicalaire, Aix Marseille Universitè, CNRS, ICR, UMR 7273, Case 551, Ave Escadrille Normandie Niemen, CEDEX 20, 13397 Marseille, France; (G.A.); (S.R.A.M.); (M.S.)
| | - Marvin Schulz
- Institut de Chimie Radicalaire, Aix Marseille Universitè, CNRS, ICR, UMR 7273, Case 551, Ave Escadrille Normandie Niemen, CEDEX 20, 13397 Marseille, France; (G.A.); (S.R.A.M.); (M.S.)
| | - Javier Santos
- Departamento de Química Biológica, Instituto de Biociencias, Biotecnología y Biomedicina (iB3-UBA), Facultad de Ciencia Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160—Ciudad Universitaria, 1428EGA CONICET, Godoy Cruz 2290, Buenos Aires C1425FQB, Argentina;
- Instituto de Química y Fisicoquímica Biológicas Dr. Alejandro Paladini, Universidad de Buenos Aires, CONICET, Junín 956, Buenos Aires 1113AAD, Argentina
| | - Paola Costantini
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy; (D.D.); (P.C.)
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (L.P.); (D.C.)
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (L.P.); (D.C.)
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18
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Candayan A, Yunisova G, Çakar A, Durmuş H, Başak AN, Parman Y, Battaloğlu E. The first biallelic missense mutation in the FXN gene in a consanguineous Turkish family with Charcot-Marie-Tooth-like phenotype. Neurogenetics 2020; 21:73-78. [PMID: 31673878 DOI: 10.1007/s10048-019-00594-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 10/05/2019] [Indexed: 11/28/2022]
Abstract
Charcot-Marie-Tooth (CMT) disease is the most common inherited neuropathy with a prevalence of 1 in 2500 individuals worldwide. Here, we report three Turkish siblings from consanguineous parents presenting with a CMT-like phenotype who carry a homozygous c.493C>T, p.Arg165Cys mutation in the FXN gene that is the only known causative gene for Friedreich's ataxia (FRDA). The identified missense mutation has been reported previously in two FRDA cases in compound heterozygosity with the common GAA repeat expansion in the first intron of the FXN gene. Analysis of skin biopsy samples from our family indicated that the mutation does not affect the expression levels of the frataxin, pointing to functional impairment of the corresponding protein. The CMT phenotype in the siblings was associated with visual impairment, optic nerve atrophy, and dysarthria. To the best of our knowledge, this family represents the first FXN missense mutation in homozygosity and challenges the notion that missense mutations have not been reported yet due to their embryonic lethality. Furthermore, this finding poses an interesting genetic overlap between autosomal recessive CMT and FRDA that we believe may have important implications on understanding the pathogenesis of these neurological disorders.
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Affiliation(s)
- Ayşe Candayan
- Department of Molecular Biology and Genetics, Bogaziçi University, Istanbul, Turkey
| | - Gulshan Yunisova
- Neuromuscular Unit, Istanbul Faculty of Medicine, Department of Neurology, Istanbul University, Istanbul, Turkey
| | - Arman Çakar
- Neuromuscular Unit, Istanbul Faculty of Medicine, Department of Neurology, Istanbul University, Istanbul, Turkey
| | - Hacer Durmuş
- Neuromuscular Unit, Istanbul Faculty of Medicine, Department of Neurology, Istanbul University, Istanbul, Turkey
| | - A Nazlı Başak
- School of Medicine, Department of Molecular Biology and Genetics, KUTTAM-NDAL, Koç University, Topkapı, Istanbul, Turkey
| | - Yeşim Parman
- Neuromuscular Unit, Istanbul Faculty of Medicine, Department of Neurology, Istanbul University, Istanbul, Turkey
| | - Esra Battaloğlu
- Department of Molecular Biology and Genetics, Bogaziçi University, Istanbul, Turkey.
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19
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Bellanda M, Maso L, Doni D, Bortolus M, De Rosa E, Lunardi F, Alfonsi A, Noguera ME, Herrera MG, Santos J, Carbonera D, Costantini P. Exploring iron-binding to human frataxin and to selected Friedreich ataxia mutants by means of NMR and EPR spectroscopies. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2019; 1867:140254. [PMID: 31344531 DOI: 10.1016/j.bbapap.2019.07.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/12/2019] [Accepted: 07/18/2019] [Indexed: 11/23/2022]
Abstract
The neurodegenerative disease Friedreich ataxia results from a deficiency of frataxin, a mitochondrial protein. Most patients have a GAA expansion in the first intron of both alleles of frataxin gene, whereas a minority of them are heterozygous for the expansion and contain a mutation in the other allele. Frataxin has been claimed to participate in iron homeostasis and biosynthesis of FeS clusters, however its role in both pathways is not unequivocally defined. In this work we combined different advanced spectroscopic analyses to explore the iron-binding properties of human frataxin, as isolated and at the FeS clusters assembly machinery. For the first time we used EPR spectroscopy to address this key issue providing clear evidence of the formation of a complex with a low symmetry coordination of the metal ion. By 2D NMR, we confirmed that iron can be bound in both oxidation states, a controversial issue, and, in addition, we were able to point out a transient interaction of frataxin with a N-terminal 6his-tagged variant of ISCU, the scaffold protein of the FeS clusters assembly machinery. To obtain insights on structure/function relationships relevant to understand the disease molecular mechanism(s), we extended our studies to four clinical frataxin mutants. All variants showed a moderate to strong impairment in their ability to activate the FeS cluster assembly machinery in vitro, while keeping the same iron-binding features of the wild type protein. This supports the multifunctional nature of frataxin and the complex biochemical consequences of its mutations.
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Affiliation(s)
- Massimo Bellanda
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy
| | - Lorenzo Maso
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy
| | - Davide Doni
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy
| | - Edith De Rosa
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy
| | - Federica Lunardi
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy
| | - Arianna Alfonsi
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy
| | - Martín Ezequiel Noguera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Universidad de Buenos Aires, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), 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
| | - Maria Georgina Herrera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Universidad de Buenos Aires, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), 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
| | - Javier Santos
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Universidad de Buenos Aires, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), 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
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy.
| | - Paola Costantini
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy.
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20
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Gottesfeld JM. Molecular Mechanisms and Therapeutics for the GAA·TTC Expansion Disease Friedreich Ataxia. Neurotherapeutics 2019; 16:1032-1049. [PMID: 31317428 PMCID: PMC6985418 DOI: 10.1007/s13311-019-00764-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Friedreich ataxia (FRDA), the most common inherited ataxia, is caused by transcriptional silencing of the nuclear FXN gene, encoding the essential mitochondrial protein frataxin. Currently, there is no approved therapy for this fatal disorder. Gene silencing in FRDA is due to hyperexpansion of the triplet repeat sequence GAA·TTC in the first intron of the FXN gene, which results in chromatin histone modifications consistent with heterochromatin formation. Frataxin is involved in mitochondrial iron homeostasis and the assembly and transfer of iron-sulfur clusters to various mitochondrial enzymes and components of the electron transport chain. Frataxin insufficiency leads to progressive spinocerebellar neurodegeneration, causing symptoms of gait and limb ataxia, slurred speech, muscle weakness, sensory loss, and cardiomyopathy in many patients, resulting in death in early adulthood. Numerous approaches are being taken to find a treatment for FRDA, including excision or correction of the repeats by genome engineering methods, gene activation with small molecules or artificial transcription factors, delivery of frataxin to affected cells by protein replacement therapy, gene therapy, or small molecules to increase frataxin protein levels, and therapies aimed at countering the cellular consequences of reduced frataxin. This review will summarize the mechanisms involved in repeat-mediated gene silencing and recent efforts aimed at development of therapeutics.
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Affiliation(s)
- Joel M Gottesfeld
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, 92037, USA.
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21
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Clay A, Hearle P, Schadt K, Lynch DR. New developments in pharmacotherapy for Friedreich ataxia. Expert Opin Pharmacother 2019; 20:1855-1867. [PMID: 31311349 DOI: 10.1080/14656566.2019.1639671] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Introduction: Friedreich ataxia (FRDA), a rare disease caused by the deficiency of the mitochondrial matrix protein frataxin, affects roughly 1 in 50,000 individuals worldwide. Current and emerging therapies focus on reversing the deleterious effects of such deficiency including mitochondrial augmentation and increasing frataxin levels, providing the possibility of treatment options for this physiologically complex, multisystem disorder. Areas covered: In this review article, the authors discuss the current and prior in vivo and in vitro research studies related to the treatment of FRDA, with a particular interest in future implications of each therapy. Expert opinion: Since the discovery of FXN in 1996, multiple clinical trials have occurred or are currently occurring; at a rapid pace for a rare disease. These trials have been directed at the augmentation of mitochondrial function and/or alleviation of symptoms and are not regarded as potential cures in FRDA. Either a combination of therapies or a drug that replaces or increases the pathologically low levels of frataxin better represent potential cures in FRDA.
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Affiliation(s)
- Alexandra Clay
- Division of Neurology, Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - Patrick Hearle
- Division of Neurology, Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - Kim Schadt
- Division of Neurology, Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - David R Lynch
- Division of Neurology, Children's Hospital of Philadelphia , Philadelphia , PA , USA
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22
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Peluzzo TM, Bonadia LC, Donatti A, Molck MC, Jardim LB, Marques W, Lopes-Cendes IT, França MC. Frequency and Genetic Profile of Compound Heterozygous Friedreich's Ataxia Patients-the Brazilian Experience. THE CEREBELLUM 2019; 18:1143-1146. [PMID: 31243663 DOI: 10.1007/s12311-019-01055-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Friedreich ataxia (FRDA) is the most common autosomal recessive ataxia in Caucasian populations. It is caused by a homozygous GAA expansion in the first intron of the frataxin gene (FXN) (OMIM: 606829) in 96% of the affected individuals. The remaining patients have a GAA expansion in one allele and a point mutation in the other. Little is known about compound heterozygous patients outside Europe and North America. We have thus designed a study to determine the frequency and mutational profile of these patients in Brazil. To accomplish that, we recruited all patients with ataxia and at least one expanded GAA allele at FXN from 3 national reference centers. We identified those subjects with a single expansion and proceeded with further genetic testing (Sanger sequencing and CGH arrays) for those. There were 143 unrelated patients (128 families), five of which had a single expanded allele. We identified point mutations in three out of these five (3/128 = 2.34%). Two patients had the c.157delC variant, whereas one individual had the novel variant c.482+1G>T. These results indicate that FXN point mutations are rare, but exist in Brazilian patients with FRDA. This has obvious implications for diagnostic testing and genetic counseling.
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Affiliation(s)
- Thiago Mazzo Peluzzo
- Department of Medical Genetics and Genomic Medicine, School of Medicine, University of Campinas - UNICAMP, Rua Tessália Vieira de Camargo, 126, Cidade Universitaria "Zeferino Vaz", Campinas, SP, 13083-887, Brazil
| | - Luciana Cardoso Bonadia
- Department of Medical Genetics and Genomic Medicine, School of Medicine, University of Campinas - UNICAMP, Rua Tessália Vieira de Camargo, 126, Cidade Universitaria "Zeferino Vaz", Campinas, SP, 13083-887, Brazil
| | - Amanda Donatti
- Department of Medical Genetics and Genomic Medicine, School of Medicine, University of Campinas - UNICAMP, Rua Tessália Vieira de Camargo, 126, Cidade Universitaria "Zeferino Vaz", Campinas, SP, 13083-887, Brazil
| | - Miriam Coelho Molck
- Department of Medical Genetics and Genomic Medicine, School of Medicine, University of Campinas - UNICAMP, Rua Tessália Vieira de Camargo, 126, Cidade Universitaria "Zeferino Vaz", Campinas, SP, 13083-887, Brazil
| | - Laura Bannach Jardim
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos, 2350, Porto Alegre, RS, 90035-003, Brazil
| | - Wilson Marques
- Department of Neurosciences and Behavior Sciences, Ribeirão Preto School of Medicine, University of São Paulo (HCFMRP-USP), Campus Universitário s/n Monte Alegre, Ribeirão Preto, SP, 14048-900, Brazil
| | - Iscia Teresinha Lopes-Cendes
- Department of Medical Genetics and Genomic Medicine, School of Medicine, University of Campinas - UNICAMP, Rua Tessália Vieira de Camargo, 126, Cidade Universitaria "Zeferino Vaz", Campinas, SP, 13083-887, Brazil
| | - Marcondes C França
- Department of Neurology, School of Medicine, University of Campinas - UNICAMP, Rua Tessália Vieira de Camargo, 126, Cidade Universitaria "Zeferino Vaz", Campinas, SP, 13083-887, Brazil.
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23
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Magri S, Fracasso V, Plumari M, Alfei E, Ghezzi D, Gellera C, Rusmini P, Poletti A, Di Bella D, Elia AE, Pantaleoni C, Taroni F. Concurrent AFG3L2 and SPG7 mutations associated with syndromic parkinsonism and optic atrophy with aberrant OPA1 processing and mitochondrial network fragmentation. Hum Mutat 2018; 39:2060-2071. [PMID: 30252181 DOI: 10.1002/humu.23658] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 09/03/2018] [Accepted: 09/22/2018] [Indexed: 01/26/2023]
Abstract
Mitochondrial dynamics and quality control are crucial for neuronal survival and their perturbation is a major cause of neurodegeneration. m-AAA complex is an ATP-dependent metalloprotease located in the inner mitochondrial membrane and involved in protein quality control. Mutations in the m-AAA subunits AFG3L2 and paraplegin are associated with autosomal dominant spinocerebellar ataxia (SCA28) and autosomal recessive hereditary spastic paraplegia (SPG7), respectively. We report a novel m-AAA-associated phenotype characterized by early-onset optic atrophy with spastic ataxia and L-dopa-responsive parkinsonism. The proband carried a de novo AFG3L2 heterozygous mutation (p.R468C) along with a heterozygous maternally inherited intragenic deletion of SPG7. Functional analysis in yeast demonstrated the pathogenic role of AFG3L2 p.R468C mutation shedding light on its pathogenic mechanism. Analysis of patient's fibroblasts showed an abnormal processing pattern of OPA1, a dynamin-related protein essential for mitochondrial fusion and responsible for most cases of hereditary optic atrophy. Consistently, assessment of mitochondrial morphology revealed a severe fragmentation of the mitochondrial network, not observed in SCA28 and SPG7 patients' cells. This case suggests that coincidental mutations in both components of the mitochondrial m-AAA protease may result in a complex phenotype and reveals a crucial role for OPA1 processing in the pathogenesis of neurodegenerative disease caused by m-AAA defects.
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Affiliation(s)
- Stefania Magri
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Valentina Fracasso
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Massimo Plumari
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Enrico Alfei
- Unit of Developmental Neurology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Daniele Ghezzi
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.,Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milan, Italy
| | - Cinzia Gellera
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Paola Rusmini
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Angelo Poletti
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Daniela Di Bella
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Antonio E Elia
- Unit of Neurology 1, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Chiara Pantaleoni
- Unit of Developmental Neurology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Franco Taroni
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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24
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Vavla M, Arrigoni F, Nordio A, De Luca A, Pizzighello S, Petacchi E, Paparella G, D'Angelo MG, Brighina E, Russo E, Fantin M, Colombo P, Martinuzzi A. Functional and Structural Brain Damage in Friedreich's Ataxia. Front Neurol 2018; 9:747. [PMID: 30237783 PMCID: PMC6135889 DOI: 10.3389/fneur.2018.00747] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 08/17/2018] [Indexed: 11/13/2022] Open
Abstract
Friedreich's ataxia (FRDA) is a rare hereditary neurodegenerative disorder caused by a GAA repeat expansion in the FXN gene. There is still no cure or quantitative biomarkers reliaby correlating with the progression rate and disease severity. Investigation of functional and structural alterations characterizing white (WM) and gray matter (GM) in FRDA are needed prerequisite to monitor progression and response to treatment. Here we report the results of a multimodal cross-sectional MRI study of FRDA including Voxel-Based Morphometry (VBM), diffusion-tensor imaging (DTI), functional MRI (fMRI), and a correlation analysis with clinical severity scores. Twenty-one early-onset FRDA patients and 18 age-matched healthy controls (HCs) were imaged at 3T. All patients underwent a complete cognitive and clinical assessment with ataxia scales. VBM analysis showed GM volume reduction in FRDA compared to HCs bilaterally in lobules V, VI, VIII (L>R), as well as in the crus of cerebellum, posterior lobe of the vermis, in the flocculi and in the left tonsil. Voxel-wise DTI analysis showed a diffuse fractional anisotropy reduction and mean, radial, axial (AD) diffusivity increase in both infratentorial and supratentorial WM. ROI-based analysis confirmed the results showing differences of the same DTI metrics in cortico-spinal-tracts, forceps major, corpus callosum, posterior thalamic radiations, cerebellar penduncles. Additionally, we observed increased AD in superior (SCP) and middle cerebellar peduncles. The WM findings correlated with age at onset (AAO), short-allelle GAA, and disease severity. The intragroup analysis of fMRI data from right-handed 14 FRDA and 15 HCs showed similar findings in both groups, including activation in M1, insula and superior cerebellar hemisphere (lobules V-VIII). Significant differences emerged only during the non-dominant hand movement, with HCs showing a stronger activation in the left superior cerebellar hemisphere compared to FRDA. Significant correlations were found between AAO and the fMRI activation in cerebellar anterior and posterior lobes, insula and temporal lobe. Our multimodal neuroimaging protocol suggests that MRI is a useful tool to document the extension of the neurological impairment in FRDA.
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Affiliation(s)
- Marinela Vavla
- Severe Developmental Disabilities Unit, Scientific Institute, IRCCS "Eugenio Medea", Conegliano, Italy
| | - Filippo Arrigoni
- Neuroimaging Lab, Scientific Institute IRCCS "Eugenio Medea", Bosisio Parini, Italy
| | - Andrea Nordio
- Neuroimaging Lab, Scientific Institute IRCCS "Eugenio Medea", Bosisio Parini, Italy.,Department of Information Engineering, University of Padova, Padova, Italy
| | - Alberto De Luca
- Neuroimaging Lab, Scientific Institute IRCCS "Eugenio Medea", Bosisio Parini, Italy
| | - Silvia Pizzighello
- Severe Developmental Disabilities Unit, Scientific Institute, IRCCS "Eugenio Medea", Conegliano, Italy
| | - Elisa Petacchi
- Severe Developmental Disabilities Unit, Scientific Institute, IRCCS "Eugenio Medea", Conegliano, Italy
| | - Gabriella Paparella
- Severe Developmental Disabilities Unit, Scientific Institute, IRCCS "Eugenio Medea", Conegliano, Italy
| | - Maria Grazia D'Angelo
- NeuroMuscular Unit, Department of NeuroRehabilitation, IRCCS "Eugenio Medea", Bosisio Parini, Italy
| | - Erika Brighina
- NeuroMuscular Unit, Department of NeuroRehabilitation, IRCCS "Eugenio Medea", Bosisio Parini, Italy
| | - Emanuela Russo
- Severe Developmental Disabilities Unit, Scientific Institute, IRCCS "Eugenio Medea", Conegliano, Italy
| | - Marianna Fantin
- Severe Developmental Disabilities Unit, Scientific Institute, IRCCS "Eugenio Medea", Conegliano, Italy
| | - Paola Colombo
- Neuroimaging Lab, Scientific Institute IRCCS "Eugenio Medea", Bosisio Parini, Italy
| | - Andrea Martinuzzi
- Severe Developmental Disabilities Unit, Scientific Institute, IRCCS "Eugenio Medea", Conegliano, Italy
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25
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Friedreich's Ataxia: Clinical Presentation of a Compound Heterozygote Child with a Rare Nonsense Mutation and Comparison with Previously Published Cases. Case Rep Neurol Med 2018; 2018:8587203. [PMID: 30159187 PMCID: PMC6106966 DOI: 10.1155/2018/8587203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 07/18/2018] [Indexed: 11/17/2022] Open
Abstract
Friedreich's ataxia is a neurodegenerative disorder associated with a GAA trinucleotide repeat expansion in intron 1 of the frataxin (FXN) gene. It is the most common autosomal recessive cerebellar ataxia, with a mean age of onset at 16 years. Nearly 95-98% of patients are homozygous for a 90-1300 GAA repeat expansion with only 2-5% demonstrating compound heterozygosity. Compound heterozygous individuals have a repeat expansion in one allele and a point mutation/deletion/insertion in the other. Compound heterozygosity and point mutations are very rare causes of Friedreich's ataxia and nonsense mutations are a further rarity among point mutations. We report a rare compound heterozygous Friedrich's ataxia patient who was found to have one expanded GAA FXN allele and a nonsense point mutation in the other. We summarize the four previously published cases of nonsense mutations and compare the phenotype to that of our patient. We compared clinical information from our patient with other nonsense FXN mutations reported in the literature. This nonsense mutation, to our knowledge, has only been described once previously; interestingly the individual was also of Cuban ancestry. A comparison with previously published cases of nonsense mutations demonstrates some common clinical characteristics.
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26
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Pilotto F, Saxena S. Epidemiology of inherited cerebellar ataxias and challenges in clinical research. CLINICAL AND TRANSLATIONAL NEUROSCIENCE 2018. [DOI: 10.1177/2514183x18785258] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Federica Pilotto
- Department of Neurology, Inselspital University Hospital, University of Bern, Bern, Switzerland
- Department for BioMedical Research, University of Bern, Bern, Switzerland
- Regenerative Neuroscience Cluster, University of Bern, Bern, Switzerland
| | - Smita Saxena
- Department of Neurology, Inselspital University Hospital, University of Bern, Bern, Switzerland
- Department for BioMedical Research, University of Bern, Bern, Switzerland
- Regenerative Neuroscience Cluster, University of Bern, Bern, Switzerland
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27
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Clinical and genetic aspects of defects in the mitochondrial iron-sulfur cluster synthesis pathway. J Biol Inorg Chem 2018; 23:495-506. [PMID: 29623423 PMCID: PMC6006192 DOI: 10.1007/s00775-018-1550-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 02/26/2018] [Indexed: 12/12/2022]
Abstract
Iron-sulfur clusters are evolutionarily conserved biological structures which play an important role as cofactor for multiple enzymes in eukaryotic cells. The biosynthesis pathways of the iron-sulfur clusters are located in the mitochondria and in the cytosol. The mitochondrial iron-sulfur cluster biosynthesis pathway (ISC) can be divided into at least twenty enzymatic steps. Since the description of frataxin deficiency as the cause of Friedreich's ataxia, multiple other deficiencies in ISC biosynthesis pathway have been reported. In this paper, an overview is given of the clinical, biochemical and genetic aspects reported in humans affected by a defect in iron-sulfur cluster biosynthesis.
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28
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Selvadurai LP, Harding IH, Corben LA, Georgiou-Karistianis N. Cerebral abnormalities in Friedreich ataxia: A review. Neurosci Biobehav Rev 2018; 84:394-406. [DOI: 10.1016/j.neubiorev.2017.08.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 06/06/2017] [Accepted: 08/10/2017] [Indexed: 12/31/2022]
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29
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Clark E, Butler JS, Isaacs CJ, Napierala M, Lynch DR. Selected missense mutations impair frataxin processing in Friedreich ataxia. Ann Clin Transl Neurol 2017; 4:575-584. [PMID: 28812047 PMCID: PMC5553228 DOI: 10.1002/acn3.433] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/23/2017] [Accepted: 05/24/2017] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVE Frataxin (FXN) is a highly conserved mitochondrial protein. Reduced FXN levels cause Friedreich ataxia, a recessive neurodegenerative disease. Typical patients carry GAA repeat expansions on both alleles, while a subgroup of patients carry a missense mutation on one allele and a GAA repeat expansion on the other. Here, we report that selected disease-related FXN missense mutations impair FXN localization, interaction with mitochondria processing peptidase, and processing. METHODS Immunocytochemical studies and subcellular fractionation were performed to study FXN import into the mitochondria and examine the mechanism by which mutations impair FXN processing. Coimmunoprecipitation was performed to study the interaction between FXN and mitochondrial processing peptidase. A proteasome inhibitor was used to model traditional therapeutic strategies. In addition, clinical profiles of subjects with and without point mutations were compared in a large natural history study. RESULTS FXNI154F and FXNG130V missense mutations decrease FXN 81-210 levels compared with FXNWT, FXNR165C, and FXNW155R, but do not block its association with mitochondria. FXNI154F and FXNG130V also impair FXN maturation and enhance the binding between FXN 42-210 and mitochondria processing peptidase. Furthermore, blocking proteosomal degradation does not increase FXN 81-210 levels. Additionally, impaired FXN processing also occurs in fibroblasts from patients with FXNG130V. Finally, clinical data from patients with FXNG130V and FXNI154F mutations demonstrates a lower severity compared with other individuals with Friedreich ataxia. INTERPRETATION These data suggest that the effects on processing associated with FXNG130V and FXNI154F mutations lead to higher levels of partially processed FXN, which may contribute to the milder clinical phenotypes in these patients.
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Affiliation(s)
- Elisia Clark
- University of Pennsylvania Philadelphia Pennsylvania.,Children's Hospital of Philadelphia Philadelphia Pennsylvania
| | - Jill S Butler
- University of Alabama at Birmingham Birmingham Alabama
| | | | | | - David R Lynch
- University of Pennsylvania Philadelphia Pennsylvania.,Children's Hospital of Philadelphia Philadelphia Pennsylvania
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30
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Bürk K. Friedreich Ataxia: current status and future prospects. CEREBELLUM & ATAXIAS 2017; 4:4. [PMID: 28405347 PMCID: PMC5383992 DOI: 10.1186/s40673-017-0062-x] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/24/2017] [Indexed: 01/23/2023]
Abstract
Friedreich ataxia (FA) represents the most frequent type of inherited ataxia. Most patients carry homozygous GAA expansions in the first intron of the frataxin gene on chromosome 9. Due to epigenetic alterations, frataxin expression is significantly reduced. Frataxin is a mitochondrial protein. Its deficiency leads to mitochondrial iron overload, defective energy supply and generation of reactive oxygen species. This review gives an overview over clinical and genetic aspects of FA and discusses current concepts of frataxin biogenesis and function as well as new therapeutic strategies.
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Affiliation(s)
- Katrin Bürk
- University of Marburg, and Paracelsus-Elena Klinik, Klinikstr. 16, 34128 Kassel, Germany
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31
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Stable isotopes and LC-MS for monitoring metabolic disturbances in Friedreich's ataxia platelets. Bioanalysis 2016; 7:1843-55. [PMID: 26295986 DOI: 10.4155/bio.15.118] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Friedreich's ataxia (FRDA) is an autosomal recessive disease with metabolic abnormalities that have been proposed to play an important role in the resulting neurodegeneration and cardiomyopathy. The inability to access the highly affected neuronal and cardiac tissues has hampered metabolic evaluation and biomarker development. METHODS Employment of a LC-MS-based method to determine whether platelets isolated from patients with FRDA exhibit differentiable metabolism compared with healthy controls. RESULTS Isotopologue analysis showed a marked decrease in glucose incorporation with a concomitant increase in palmitate-derived acyl-CoA thioesters in FRDA platelets compared with controls. CONCLUSION Our findings demonstrate that platelets can be used as a surrogate tissue for in vivo biomarker studies to monitor new therapeutic approaches for the treatment of FRDA.
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32
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Galea CA, Huq A, Lockhart PJ, Tai G, Corben LA, Yiu EM, Gurrin LC, Lynch DR, Gelbard S, Durr A, Pousset F, Parkinson M, Labrum R, Giunti P, Perlman SL, Delatycki MB, Evans-Galea MV. Compound heterozygous FXN mutations and clinical outcome in friedreich ataxia. Ann Neurol 2016; 79:485-95. [PMID: 26704351 DOI: 10.1002/ana.24595] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 02/01/2023]
Abstract
OBJECTIVE Friedreich ataxia (FRDA) is an inherited neurodegenerative disease characterized by ataxia and cardiomyopathy. Homozygous GAA trinucleotide repeat expansions in the first intron of FXN occur in 96% of affected individuals and reduce frataxin expression. Remaining individuals are compound heterozygous for a GAA expansion and a FXN point/insertion/deletion mutation. We examined disease-causing mutations and the impact on frataxin structure/function and clinical outcome in FRDA. METHODS We compared clinical information from 111 compound heterozygotes and 131 individuals with homozygous expansions. Frataxin mutations were examined using structural modeling, stability analyses and systematic literature review, and categorized into four groups: (1) homozygous expansions, and three compound heterozygote groups; (2) null (no frataxin produced); (3) moderate/strong impact; and (4) minimal impact. Mean age of onset and the presence of cardiomyopathy and diabetes mellitus were compared using regression analyses. RESULTS Mutations in the hydrophobic core of frataxin affected stability whereas surface residue mutations affected interactions with iron sulfur cluster assembly and heme biosynthetic proteins. The null group of compound heterozygotes had significantly earlier age of onset and increased diabetes mellitus, compared to the homozygous expansion group. There were no significant differences in mean age of onset between homozygotes and the minimal and moderate/strong impact groups. INTERPRETATION In compound heterozygotes, expression of partially functional mutant frataxin delays age of onset and reduces diabetes mellitus, compared to those with no frataxin expression from the non-expanded allele. This integrated analysis of categorized frataxin mutations and their correlation with clinical outcome provide a definitive resource for investigating disease pathogenesis in FRDA.
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Affiliation(s)
- Charles A Galea
- Medicinal Chemistry and Drug Delivery, Disposition and Dynamics (D4), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Aamira Huq
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Paul J Lockhart
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Geneieve Tai
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Louise A Corben
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- School of Psychological Sciences, Monash University, Clayton, Victoria, Australia
| | - Eppie M Yiu
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Neurology, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Lyle C Gurrin
- Center for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - David R Lynch
- Departments of Neurology and Pediatrics, University of Pennsylvania School of Medicine and The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Sarah Gelbard
- Departments of Neurology and Pediatrics, University of Pennsylvania School of Medicine and The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Alexandra Durr
- APHP, Department of Genetics and Cytogenetics, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
- Institut du Cerveau et de la Moelle épinière (ICM), Pitié-Salpêtrière University Hospital, Paris, France
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S_1127, ICM, F-75013, France
| | - Francoise Pousset
- APHP, Cardiology Department, AP-HP Pitie-Salpétrière Hospital, Paris, France
| | - Michael Parkinson
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Robyn Labrum
- Department of Neurogenetics, University College London Hospital, Institute of Neurology, London, United Kingdom
| | - Paola Giunti
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
- Department of Neurogenetics, University College London Hospital, Institute of Neurology, London, United Kingdom
| | - Susan L Perlman
- Ataxia Center and Huntington Disease Center of Excellence, Department of Neurology, David Geffen School of Medicine at the University of California at Los Angeles, CA
| | - Martin B Delatycki
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- School of Psychological Sciences, Monash University, Clayton, Victoria, Australia
- Clinical Genetics, Austin Health, Heidelberg, Victoria, Australia
| | - Marguerite V Evans-Galea
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
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33
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Faggianelli N, Puglisi R, Veneziano L, Romano S, Frontali M, Vannocci T, Fortuni S, Testi R, Pastore A. Analyzing the Effects of a G137V Mutation in the FXN Gene. Front Mol Neurosci 2015; 8:66. [PMID: 26635519 PMCID: PMC4658817 DOI: 10.3389/fnmol.2015.00066] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 10/23/2015] [Indexed: 12/15/2022] Open
Abstract
Reduced levels of frataxin, an essential mitochondrial protein involved in the regulation of iron-sulfur cluster biogenesis, are responsible for the recessive neurodegenerative Friedreich Ataxia (FRDA). Expansion of a GAA triplet in the first intron of the FRDA is essential for disease development which causes partial silencing of frataxin. In the vast majority of cases, patients are homozygotes for the expansion, but a small number of FRDA patients are heterozygotes for expansion and point mutations in the frataxin coding frame. In this study, we analyze the effects of a point mutation G137V. The patient P94–2, with a history of alcohol and drug abuse, showed a FRDA onset at the border between the classic and late onset phenotype. We applied a combination of biophysical and biochemical methods to characterize its effects on the structure, folding and activity of frataxin. Our study reveals no impairment of the structure or activity of the protein but a reduced folding stability. We suggest that the mutation causes misfolding of the native chain with consequent reduction of the protein concentration in the patient and discuss the possible mechanism of disease.
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Affiliation(s)
- Nathalie Faggianelli
- Department of Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London London, UK
| | - Rita Puglisi
- Department of Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London London, UK
| | | | - Silvia Romano
- Sant'Andrea Hospital, University of Rome La Sapienza Rome, Italy
| | | | - Tommaso Vannocci
- Department of Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London London, UK
| | - Silvia Fortuni
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata" Rome, Italy
| | - Roberto Testi
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata" Rome, Italy
| | - Annalisa Pastore
- Department of Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London London, UK
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Zeng J, Wang J, Zeng S, He M, Zeng X, Zhou Y, Liu Z, Jiang H, Tang B. Friedreich's Ataxia (FRDA) is an extremely rare cause of autosomal recessive ataxia in Chinese Han population. J Neurol Sci 2015; 351:124-126. [PMID: 25765228 DOI: 10.1016/j.jns.2015.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/01/2015] [Indexed: 10/23/2022]
Abstract
Friedreich's Ataxia (FRDA) is a very common cause of hereditary autosomal recessive ataxia among western Europeans. We aim to define the frequency of FRDA in Chinese Han population due to the lack of reports of FRDA in China. The GAA trinucleotide repeats in the FXN gene were analyzed by triplet repeat-primed PCR (TP-PCR) in 122 unrelated hereditary ataxia (HA) and 114 unrelated hereditary spastic paraplegia (HSP) patients. The GAA copy numbers in the FXN gene of all the subjects ranged from 5 to 16. There were no FRDA patients that could be diagnosed base on the results of TP-PCR. It suggests that FRDA is a very rare cause of inheritance ataxia and FRDA genetic analysis should not be used as a routine genetic diagnosis test in China.
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Affiliation(s)
- Junsheng Zeng
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, PR China
| | - Junling Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, PR China; Key Laboratory of Hunan Province in Neurodegenerative Disorders, Changsha, Hunan, PR China; State Key Laboratory of Medical Genetics, Changsha, Hunan, PR China
| | - Sheng Zeng
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, PR China
| | - Miao He
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, PR China
| | - Xianfeng Zeng
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, PR China
| | - Yao Zhou
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, PR China
| | - Zhen Liu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, PR China
| | - Hong Jiang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, PR China; Key Laboratory of Hunan Province in Neurodegenerative Disorders, Changsha, Hunan, PR China; State Key Laboratory of Medical Genetics, Changsha, Hunan, PR China
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, PR China; Key Laboratory of Hunan Province in Neurodegenerative Disorders, Changsha, Hunan, PR China; State Key Laboratory of Medical Genetics, Changsha, Hunan, PR China.
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Abstract
Heredoataxias are a group of genetic disorders with a cerebellar syndrome as the leading clinical manifestation. The current classification distinguishes heredoataxias according to the trait of inheritance into autosomal dominant, autosomal recessive, X-linked, and maternally inherited heredoataxias. The autosomal dominant heredoataxias are separated into spinocerebellar ataxias (SCA1-8, 10-15, 17-23, 25-30, and dentato-rubro-pallido-luysian atrophy), episodic ataxias (EA1-7), and autosomal dominant mitochondrial heredoataxias (Leigh syndrome, MIRAS, ADOAD, and AD-CPEO). The autosomal recessive ataxias are separated into Friedreich ataxia, ataxia due to vitamin E deficiency, ataxia due to Abeta-lipoproteinemia, Refsum disease, late-onset Tay-Sachs disease, cerebrotendineous xanthomatosis, spinocerebellar ataxia with axonal neuropathy, ataxia telangiectasia, ataxia telangiectasia-like disorder, ataxia with oculomotor apraxia 1 and 2, spastic ataxia of Charlevoix-Saguenay, Cayman ataxia, Marinesco-Sjögren syndrome, and autosomal recessive mitochondrial ataxias (AR-CPEO, SANDO, SCAE, AHS, IOSCA, MEMSA, LBSL CoQ-deficiency, PDC-deficiency). Only two of the heredoataxias, fragile X/tremor/ataxia syndrome, and XLSA/A are transmitted via an X-linked trait. Maternally inherited heredoataxias are due to point mutations in genes encoding for tRNAs, rRNAs, respiratory chain subunits or single large scale deletions/duplications of the mitochondrial DNA and include MELAS, MERRF, KSS, PS, MILS, NARP, and non-syndromic mitochondrial disorders. Treatment of heredoataxias is symptomatic and supportive and may have a beneficial effect in single patients.**Please see page 424 for abbreviation list.
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Maio N, Rouault TA. Iron-sulfur cluster biogenesis in mammalian cells: New insights into the molecular mechanisms of cluster delivery. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1493-512. [PMID: 25245479 DOI: 10.1016/j.bbamcr.2014.09.009] [Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 09/07/2014] [Indexed: 01/19/2023]
Abstract
Iron-sulfur (Fe-S) clusters are ancient, ubiquitous cofactors composed of iron and inorganic sulfur. The combination of the chemical reactivity of iron and sulfur, together with many variations of cluster composition, oxidation states and protein environments, enables Fe-S clusters to participate in numerous biological processes. Fe-S clusters are essential to redox catalysis in nitrogen fixation, mitochondrial respiration and photosynthesis, to regulatory sensing in key metabolic pathways (i.e. cellular iron homeostasis and oxidative stress response), and to the replication and maintenance of the nuclear genome. Fe-S cluster biogenesis is a multistep process that involves a complex sequence of catalyzed protein-protein interactions and coupled conformational changes between the components of several dedicated multimeric complexes. Intensive studies of the assembly process have clarified key points in the biogenesis of Fe-S proteins. However several critical questions still remain, such as: what is the role of frataxin? Why do some defects of Fe-S cluster biogenesis cause mitochondrial iron overload? How are specific Fe-S recipient proteins recognized in the process of Fe-S transfer? This review focuses on the basic steps of Fe-S cluster biogenesis, drawing attention to recent advances achieved on the identification of molecular features that guide selection of specific subsets of nascent Fe-S recipients by the cochaperone HSC20. Additionally, it outlines the distinctive phenotypes of human diseases due to mutations in the components of the basic pathway. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases.
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Affiliation(s)
- Nunziata Maio
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 9000 Rockville Pike, 20892 Bethesda, MD, USA
| | - Tracey A Rouault
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 9000 Rockville Pike, 20892 Bethesda, MD, USA.
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Ygland E, Taroni F, Gellera C, Caldarazzo S, Duno M, Soller M, Puschmann A. Atypical Friedreich ataxia in patients with FXN p.R165P point mutation or comorbid hemochromatosis. Parkinsonism Relat Disord 2014; 20:919-23. [PMID: 24816001 DOI: 10.1016/j.parkreldis.2014.04.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 03/28/2014] [Accepted: 04/14/2014] [Indexed: 11/29/2022]
Abstract
BACKGROUND Compound heterozygosity for a trinucleotide repeat expansion and a point mutation in the FXN gene is a rare cause of Friedreich ataxia (FRDA). METHODS We identified three Swedish FRDA patients with an FXN p.R165P missense mutation and compared their clinical features with six homozygote trinucleotide repeat expansion carriers. Patients were assessed clinically. Trinucleotide expansion length was determined and lymphocyte frataxin levels measured. RESULTS p.R165P mutation carriers became wheelchair bound early, but had retained reflexes, better arm function, milder dysarthria, and were more independent in activities of daily living. One p.R165P mutation carrier developed psychosis. Frataxin levels were higher than in homozygous trinucleotide expansion patients. One patient with homozygous trinucleotide repeat expansions and comorbid hemochromatosis had more severe FRDA symptoms than his sibling without hemochromatosis. CONCLUSION p.R165P patients progress to a less disabling disease state than typical FRDA. Comorbid hemochromatosis may worsen FRDA symptoms through additive effects on iron metabolism.
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Affiliation(s)
- Emil Ygland
- Department of Neurology, Skåne University Hospital, Lund, Sweden; Department of Neurology, Clinical Sciences, Lund University, Lund, Sweden
| | - Franco Taroni
- Unit of Genetics of Neurodegenerative and Metabolic Disease, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Cinzia Gellera
- Unit of Genetics of Neurodegenerative and Metabolic Disease, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Serena Caldarazzo
- Unit of Genetics of Neurodegenerative and Metabolic Disease, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Morten Duno
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Maria Soller
- Department of Clinical Genetics, Skåne University Hospital, University and Regional Laboratories, Lund University, Lund, Sweden
| | - Andreas Puschmann
- Department of Neurology, Skåne University Hospital, Lund, Sweden; Department of Neurology, Clinical Sciences, Lund University, Lund, Sweden.
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Martelli A, Puccio H. Dysregulation of cellular iron metabolism in Friedreich ataxia: from primary iron-sulfur cluster deficit to mitochondrial iron accumulation. Front Pharmacol 2014; 5:130. [PMID: 24917819 PMCID: PMC4042101 DOI: 10.3389/fphar.2014.00130] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 05/14/2014] [Indexed: 01/25/2023] Open
Abstract
Friedreich ataxia (FRDA) is the most common recessive ataxia in the Caucasian population and is characterized by a mixed spinocerebellar and sensory ataxia frequently associating cardiomyopathy. The disease results from decreased expression of the FXN gene coding for the mitochondrial protein frataxin. Early histological and biochemical study of the pathophysiology in patient's samples revealed that dysregulation of iron metabolism is a key feature of the disease, mainly characterized by mitochondrial iron accumulation and by decreased activity of iron-sulfur cluster enzymes. In the recent past years, considerable progress in understanding the function of frataxin has been provided through cellular and biochemical approaches, pointing to the primary role of frataxin in iron-sulfur cluster biogenesis. However, why and how the impact of frataxin deficiency on this essential biosynthetic pathway leads to mitochondrial iron accumulation is still poorly understood. Herein, we review data on both the primary function of frataxin and the nature of the iron metabolism dysregulation in FRDA. To date, the pathophysiological implication of the mitochondrial iron overload in FRDA remains to be clarified.
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Affiliation(s)
- Alain Martelli
- Department of Translational Medecine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire Illkirch, France ; INSERM, U596 Illkirch, France ; CNRS, UMR7104 Illkirch, France ; Université de Strasbourg Strasbourg, France ; Chaire de Génétique Humaine, Collège de France Illkirch, France
| | - Hélène Puccio
- Department of Translational Medecine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire Illkirch, France ; INSERM, U596 Illkirch, France ; CNRS, UMR7104 Illkirch, France ; Université de Strasbourg Strasbourg, France ; Chaire de Génétique Humaine, Collège de France Illkirch, France
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Puccio H, Anheim M, Tranchant C. Pathophysiogical and therapeutic progress in Friedreich ataxia. Rev Neurol (Paris) 2014; 170:355-65. [PMID: 24792433 DOI: 10.1016/j.neurol.2014.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/25/2014] [Accepted: 03/26/2014] [Indexed: 01/10/2023]
Abstract
Friedreich ataxia (FRDA) is the most common hereditary autosomal recessive ataxia, but is also a multisystemic condition with frequent presence of cardiomyopathy or diabetes. It has been linked to expansion of a GAA-triplet repeat in the first intron of the FXN gene, leading to a reduced level of frataxin, a mitochondrial protein which, by controlling both iron entry and/or sulfide production, is essential to properly assemble and protect the Fe-S cluster during the initial stage of biogenesis. Several data emphasize the role of oxidative damage in FRDA, but better understanding of pathophysiological consequences of FXN mutations has led to develop animal models. Conditional knockout models recapitulate important features of the human disease but lack the genetic context, GAA repeat expansion-based knock-in and transgenic models carry a GAA repeat expansion but they only show a very mild phenotype. Cells derived from FRDA patients constitute the most relevant frataxin-deficient cell model as they carry the complete frataxin locus together with GAA repeat expansions and regulatory sequences. Induced pluripotent stem cell (iPSC)-derived neurons present a maturation delay and lower mitochondrial membrane potential, while cardiomyocytes exhibit progressive mitochondrial degeneration, with frequent dark mitochondria and proliferation/accumulation of normal mitochondria. Efforts in developing therapeutic strategies can be divided into three categories: iron chelators, antioxidants and/or stimulants of mitochondrial biogenesis, and frataxin level modifiers. A promising therapeutic strategy that is currently the subject of intense research is to directly target the heterochromatin state of the GAA repeat expansion with histone deacytelase inhibitors (HDACi) to restore frataxin levels.
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Affiliation(s)
- H Puccio
- Translational medicine and neurogenetics, institut de génétique et de biologie moléculaire et cellulaire (IGBMC), 1, rue Laurent-Fries, BP 10142, 67404 Illkirch cedex, France; Inserm, U596, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; CNRS, UMR7104, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; Université de Strasbourg, 4, rue Blaise-Pascal, 67400 Strasbourg, France; Collège de France, chaire de génétique humaine, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France
| | - M Anheim
- Translational medicine and neurogenetics, institut de génétique et de biologie moléculaire et cellulaire (IGBMC), 1, rue Laurent-Fries, BP 10142, 67404 Illkirch cedex, France; Inserm, U596, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; CNRS, UMR7104, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; Université de Strasbourg, 4, rue Blaise-Pascal, 67400 Strasbourg, France; Service de neurologie, unité des pathologies du mouvement, hôpital de Hautepierre, hôpital universitaire, 1, place de l'Hôpital, 67000 Strasbourg, France
| | - C Tranchant
- Translational medicine and neurogenetics, institut de génétique et de biologie moléculaire et cellulaire (IGBMC), 1, rue Laurent-Fries, BP 10142, 67404 Illkirch cedex, France; Inserm, U596, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; CNRS, UMR7104, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; Université de Strasbourg, 4, rue Blaise-Pascal, 67400 Strasbourg, France; Service de neurologie, unité des pathologies du mouvement, hôpital de Hautepierre, hôpital universitaire, 1, place de l'Hôpital, 67000 Strasbourg, France.
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Sandi C, Sandi M, Jassal H, Ezzatizadeh V, Anjomani-Virmouni S, Al-Mahdawi S, Pook MA. Generation and characterisation of Friedreich ataxia YG8R mouse fibroblast and neural stem cell models. PLoS One 2014; 9:e89488. [PMID: 24586819 PMCID: PMC3931792 DOI: 10.1371/journal.pone.0089488] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 01/20/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused by GAA repeat expansion in the first intron of the FXN gene, which encodes frataxin, an essential mitochondrial protein. To further characterise the molecular abnormalities associated with FRDA pathogenesis and to hasten drug screening, the development and use of animal and cellular models is considered essential. Studies of lower organisms have already contributed to understanding FRDA disease pathology, but mammalian cells are more related to FRDA patient cells in physiological terms. METHODOLOGY/PRINCIPAL FINDINGS We have generated fibroblast cells and neural stem cells (NSCs) from control Y47R mice (9 GAA repeats) and GAA repeat expansion YG8R mice (190+120 GAA repeats). We then differentiated the NSCs in to neurons, oligodendrocytes and astrocytes as confirmed by immunocytochemical analysis of cell specific markers. The three YG8R mouse cell types (fibroblasts, NSCs and differentiated NSCs) exhibit GAA repeat stability, together with reduced expression of frataxin and reduced aconitase activity compared to control Y47R cells. Furthermore, YG8R cells also show increased sensitivity to oxidative stress and downregulation of Pgc-1α and antioxidant gene expression levels, especially Sod2. We also analysed various DNA mismatch repair (MMR) gene expression levels and found that YG8R cells displayed significant reduction in expression of several MMR genes, which may contribute to the GAA repeat stability. CONCLUSIONS/SIGNIFICANCE We describe the first fibroblast and NSC models from YG8R FRDA mice and we confirm that the NSCs can be differentiated into neurons and glia. These novel FRDA mouse cell models, which exhibit a FRDA-like cellular and molecular phenotype, will be valuable resources to further study FRDA molecular pathogenesis. They will also provide very useful tools for preclinical testing of frataxin-increasing compounds for FRDA drug therapy, for gene therapy, and as a source of cells for cell therapy testing in FRDA mice.
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Affiliation(s)
- Chiranjeevi Sandi
- Ataxia Research Group, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Madhavi Sandi
- Ataxia Research Group, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Harvinder Jassal
- Ataxia Research Group, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Vahid Ezzatizadeh
- Ataxia Research Group, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Sara Anjomani-Virmouni
- Ataxia Research Group, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Sahar Al-Mahdawi
- Ataxia Research Group, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Mark A. Pook
- Ataxia Research Group, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
- * E-mail:
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Beilschmidt LK, Puccio HM. Mammalian Fe-S cluster biogenesis and its implication in disease. Biochimie 2014; 100:48-60. [PMID: 24440636 DOI: 10.1016/j.biochi.2014.01.009] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 01/07/2014] [Indexed: 10/25/2022]
Abstract
Iron-sulfur (Fe-S) clusters are inorganic cofactors that are ubiquitous and essential. Due to their chemical versatility, Fe-S clusters are implicated in a wide range of protein functions including mitochondrial respiration and DNA repair. Composed of iron and sulfur, they are sensible to oxygen and their biogenesis requires a highly conserved protein machinery that facilitates assembly of the cluster as well as its insertion into apoproteins. Mitochondria are the central cellular compartment for Fe-S cluster biogenesis in eukaryotic cells and the importance of proper function of this biogenesis for life is highlighted by a constantly increasing number of human genetic diseases that are associated with dysfunction of this Fe-S cluster biogenesis pathway. Although these disorders are rare and appear dissimilar, common aspects are found among them. This review will give an overview on what is known on mammalian Fe-S cluster biogenesis today, by putting it into the context of what is known from studies from lower model organisms, and focuses on the associated diseases, by drawing attention to the respective mutations. Finally, it outlines the importance of adequate cellular and murine models to uncover not only each protein function, but to resolve their role and requirement throughout the mammalian organism.
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Affiliation(s)
- Lena K Beilschmidt
- Translational Medicine and Neurogenetics, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Illkirch, France; Inserm, U596, Illkirch, France; CNRS, UMR7104, Illkirch, France; Université de Strasbourg, Strasbourg, France; Collège de France, Chaire de génétique humaine, Illkirch, France
| | - Hélène M Puccio
- Translational Medicine and Neurogenetics, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Illkirch, France; Inserm, U596, Illkirch, France; CNRS, UMR7104, Illkirch, France; Université de Strasbourg, Strasbourg, France; Collège de France, Chaire de génétique humaine, Illkirch, France.
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Abruzzo PM, Marini M, Bolotta A, Malisardi G, Manfredini S, Ghezzo A, Pini A, Tasco G, Casadio R. Frataxin mRNA isoforms in FRDA patients and normal subjects: effect of tocotrienol supplementation. BIOMED RESEARCH INTERNATIONAL 2013; 2013:276808. [PMID: 24175286 PMCID: PMC3794619 DOI: 10.1155/2013/276808] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 08/06/2013] [Accepted: 08/17/2013] [Indexed: 11/22/2022]
Abstract
Friedreich's ataxia (FRDA) is caused by deficient expression of the mitochondrial protein frataxin involved in the formation of iron-sulphur complexes and by consequent oxidative stress. We analysed low-dose tocotrienol supplementation effects on the expression of the three splice variant isoforms (FXN-1, FXN-2, and FXN-3) in mononuclear blood cells of FRDA patients and healthy subjects. In FRDA patients, tocotrienol leads to a specific and significant increase of FXN-3 expression while not affecting FXN-1 and FXN-2 expression. Since no structural and functional details were available for FNX-2 and FXN-3, 3D models were built. FXN-1, the canonical isoform, was then docked on the human iron-sulphur complex, and functional interactions were computed; when FXN-1 was replaced by FXN-2 or FNX-3, we found that the interactions were maintained, thus suggesting a possible biological role for both isoforms in human cells. Finally, in order to evaluate whether tocotrienol enhancement of FXN-3 was mediated by an increase in peroxisome proliferator-activated receptor-γ (PPARG), PPARG expression was evaluated. At a low dose of tocotrienol, the increase of FXN-3 expression appeared to be independent of PPARG expression. Our data show that it is possible to modulate the mRNA expression of the minor frataxin isoforms and that they may have a functional role.
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Affiliation(s)
- Provvidenza Maria Abruzzo
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, 40126 Bologna, Italy
| | - Marina Marini
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, 40126 Bologna, Italy
| | - Alessandra Bolotta
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, 40126 Bologna, Italy
| | - Gemma Malisardi
- Department of Pharmaceutical Sciences, University of Ferrara, 44100 Ferrara, Italy
| | - Stefano Manfredini
- Department of Pharmaceutical Sciences, University of Ferrara, 44100 Ferrara, Italy
| | - Alessandro Ghezzo
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, 40126 Bologna, Italy
- ANFFAS ONLUS Macerata, 62100 Macerata, Italy
| | - Antonella Pini
- Child Neurology and Psychiatry Unit, IRCCS Institute of Neurological Sciences of Bologna, Bologna, 40100 Bologna, Italy
| | - Gianluca Tasco
- Biocomputing Group, CIRI-Health Science and Technology, Department of Biology, Bologna 40126, Italy
| | - Rita Casadio
- Biocomputing Group, CIRI-Health Science and Technology, Department of Biology, Bologna 40126, Italy
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Parkinson MH, Boesch S, Nachbauer W, Mariotti C, Giunti P. Clinical features of Friedreich's ataxia: classical and atypical phenotypes. J Neurochem 2013; 126 Suppl 1:103-17. [PMID: 23859346 DOI: 10.1111/jnc.12317] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 05/15/2013] [Accepted: 05/15/2013] [Indexed: 11/27/2022]
Abstract
One hundred and fifty years since Nikolaus Friedreich's first description of the degenerative ataxic syndrome which bears his name, his description remains at the core of the classical clinical phenotype of gait and limb ataxia, poor balance and coordination, leg weakness, sensory loss, areflexia, impaired walking, dysarthria, dysphagia, eye movement abnormalities, scoliosis, foot deformities, cardiomyopathy and diabetes. Onset is typically around puberty with slow progression and shortened life-span often related to cardiac complications. Inheritance is autosomal recessive with the vast majority of cases showing an unstable intronic GAA expansion in both alleles of the frataxin gene on chromosome 9q13. A small number of cases are caused by a compound heterozygous expansion with a point mutation or deletion. Understanding of the underlying molecular biology has enabled identification of atypical phenotypes with late onset, or atypical features such as retained reflexes. Late-onset cases tend to have slower progression and are associated with smaller GAA expansions. Early-onset cases tend to have more rapid progression and a higher frequency of non-neurological features such as diabetes, cardiomyopathy, scoliosis and pes cavus. Compound heterozygotes, including those with large deletions, often have atypical features. In this paper, we review the classical and atypical clinical phenotypes of Friedreich's ataxia.
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Affiliation(s)
- Michael H Parkinson
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
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Perdomini M, Hick A, Puccio H, Pook MA. Animal and cellular models of Friedreich ataxia. J Neurochem 2013; 126 Suppl 1:65-79. [PMID: 23859342 DOI: 10.1111/jnc.12219] [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: 12/19/2012] [Revised: 02/01/2013] [Accepted: 02/04/2013] [Indexed: 11/30/2022]
Abstract
The development and use of animal and cellular models of Friedreich ataxia (FRDA) are essential requirements for the understanding of FRDA disease mechanisms and the investigation of potential FRDA therapeutic strategies. Although animal and cellular models of lower organisms have provided valuable information on certain aspects of FRDA disease and therapy, it is intuitive that the most useful models are those of mammals and mammalian cells, which are the closest in physiological terms to FRDA patients. To date, there have been considerable efforts put into the development of several different FRDA mouse models and relevant FRDA mouse and human cell line systems. We summarize the principal mammalian FRDA models, discuss the pros and cons of each system, and describe the ways in which such models have been used to address two of the fundamental, as yet unanswered, questions regarding FRDA. Namely, what is the exact pathophysiology of FRDA and what is the detailed genetic and epigenetic basis of FRDA?
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Affiliation(s)
- Morgane Perdomini
- Translational Medecine and Neurogenetics, IGBMC-Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
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Gomes CM, Santos R. Neurodegeneration in Friedreich's ataxia: from defective frataxin to oxidative stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2013; 2013:487534. [PMID: 23936609 PMCID: PMC3725840 DOI: 10.1155/2013/487534] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Accepted: 06/14/2013] [Indexed: 02/08/2023]
Abstract
Friedreich's ataxia is the most common inherited autosomal recessive ataxia and is characterized by progressive degeneration of the peripheral and central nervous systems and cardiomyopathy. This disease is caused by the silencing of the FXN gene and reduced levels of the encoded protein, frataxin. Frataxin is a mitochondrial protein that functions primarily in iron-sulfur cluster synthesis. This small protein with an α / β sandwich fold undergoes complex processing and imports into the mitochondria, generating isoforms with distinct N-terminal lengths which may underlie different functionalities, also in respect to oligomerization. Missense mutations in the FXN coding region, which compromise protein folding, stability, and function, are found in 4% of FRDA heterozygous patients and are useful to understand how loss of functional frataxin impacts on FRDA physiopathology. In cells, frataxin deficiency leads to pleiotropic phenotypes, including deregulation of iron homeostasis and increased oxidative stress. Increasing amount of data suggest that oxidative stress contributes to neurodegeneration in Friedreich's ataxia.
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Affiliation(s)
- Cláudio M. Gomes
- Instituto Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, 2784-505 Oeiras, Portugal
| | - Renata Santos
- Development of the Nervous System, IBENS, Ecole Normale Supérieure, 46 rue d'Ulm, 75230 Paris Cedex 05, France
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Epigenetics in Friedreich's Ataxia: Challenges and Opportunities for Therapy. GENETICS RESEARCH INTERNATIONAL 2013; 2013:852080. [PMID: 23533785 PMCID: PMC3590757 DOI: 10.1155/2013/852080] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 01/10/2013] [Indexed: 11/17/2022]
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disorder caused by homozygous expansion of a GAA·TTC trinucleotide repeat within the first intron of the FXN gene, leading to reduced FXN transcription and decreased levels of frataxin protein. Recent advances in FRDA research have revealed the presence of several epigenetic modifications that are either directly or indirectly involved in this FXN gene silencing. Although epigenetic marks may be inherited from one generation to the next, modifications of DNA and histones can be reversed, indicating that they are suitable targets for epigenetic-based therapy. Unlike other trinucleotide repeat disorders, such as Huntington disease, the large expansions of GAA·TTC repeats in FRDA do not produce a change in the frataxin amino acid sequence, but they produce reduced levels of normal frataxin. Therefore, transcriptional reactivation of the FXN gene provides a good therapeutic option. The present paper will initially focus on the epigenetic changes seen in FRDA patients and their role in the silencing of FXN gene and will be concluded by considering the potential epigenetic therapies.
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47
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Martelli A, Friedman LS, Reutenauer L, Messaddeq N, Perlman SL, Lynch DR, Fedosov K, Schulz JB, Pandolfo M, Puccio H. Clinical data and characterization of the liver conditional mouse model exclude neoplasia as a non-neurological manifestation associated with Friedreich's ataxia. Dis Model Mech 2012; 5:860-9. [PMID: 22736457 PMCID: PMC3484868 DOI: 10.1242/dmm.009829] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 06/06/2012] [Indexed: 01/01/2023] Open
Abstract
Friedreich's ataxia (FRDA) is the most common hereditary ataxia in the caucasian population and is characterized by a mixed spinocerebellar and sensory ataxia, hypertrophic cardiomyopathy and increased incidence of diabetes. FRDA is caused by impaired expression of the FXN gene coding for the mitochondrial protein frataxin. During the past ten years, the development of mouse models of FRDA has allowed better understanding of the pathophysiology of the disease. Among the mouse models of FRDA, the liver conditional mouse model pointed to a tumor suppressor activity of frataxin leading to the hypothesis that individuals with FRDA might be predisposed to cancer. In the present work, we investigated the presence and the incidence of neoplasia in the largest FRDA patient cohorts from the USA, Australia and Europe. As no predisposition to cancer could be observed in both cohorts, we revisited the phenotype of the liver conditional mouse model. Our results show that frataxin-deficient livers developed early mitochondriopathy, iron-sulfur cluster deficits and intramitochondrial dense deposits, classical hallmarks observed in frataxin-deficient tissues and cells. With age, a minority of mice developed structures similar to the ones previously associated with tumor formation. However, these peripheral structures contained dying, frataxin-deficient hepatocytes, whereas the inner liver structure was composed of a pool of frataxin-positive cells, due to inefficient Cre-mediated recombination of the Fxn gene, that contributed to regeneration of a functional liver. Together, our data demonstrate that frataxin deficiency and tumorigenesis are not associated.
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Affiliation(s)
- Alain Martelli
- Translational Medecine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), 67404 Illkirch, France
- INSERM, U596, 67404 Illkirch, France
- CNRS, UMR7104, 67404 Illkirch, France
- Université de Strasbourg, 67404 Illkirch, France
- Collège de France, Chaire de génétique humaine, 67404 Illkirch, France
| | - Lisa S. Friedman
- Department of Neurology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Pediatrics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Division of Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Laurence Reutenauer
- Translational Medecine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), 67404 Illkirch, France
- INSERM, U596, 67404 Illkirch, France
- CNRS, UMR7104, 67404 Illkirch, France
- Université de Strasbourg, 67404 Illkirch, France
- Collège de France, Chaire de génétique humaine, 67404 Illkirch, France
| | - Nadia Messaddeq
- Translational Medecine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), 67404 Illkirch, France
- INSERM, U596, 67404 Illkirch, France
- CNRS, UMR7104, 67404 Illkirch, France
- Université de Strasbourg, 67404 Illkirch, France
- Collège de France, Chaire de génétique humaine, 67404 Illkirch, France
| | - Susan L. Perlman
- University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - David R. Lynch
- Department of Neurology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Pediatrics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Division of Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Kathrin Fedosov
- Department of Neurology, University Hospital Aachen, 52074 Aachen, Germany
| | - Jörg B. Schulz
- Department of Neurology, University Hospital Aachen, 52074 Aachen, Germany
| | - Massimo Pandolfo
- Laboratoire de Neurologie Expérimentale, Hôpital Erasme, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Hélène Puccio
- Translational Medecine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), 67404 Illkirch, France
- INSERM, U596, 67404 Illkirch, France
- CNRS, UMR7104, 67404 Illkirch, France
- Université de Strasbourg, 67404 Illkirch, France
- Collège de France, Chaire de génétique humaine, 67404 Illkirch, France
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Roman EA, Faraj SE, Gallo M, Salvay AG, Ferreiro DU, Santos J. Protein stability and dynamics modulation: the case of human frataxin. PLoS One 2012; 7:e45743. [PMID: 23049850 PMCID: PMC3458073 DOI: 10.1371/journal.pone.0045743] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 08/24/2012] [Indexed: 01/06/2023] Open
Abstract
Frataxin (FXN) is an α/β protein that plays an essential role in iron homeostasis. Apparently, the function of human FXN (hFXN) depends on the cooperative formation of crucial interactions between helix α1, helix α2, and the C-terminal region (CTR) of the protein. In this work we quantitatively explore these relationships using a purified recombinant fragment hFXN90-195. This variant shows the hydrodynamic behavior expected for a monomeric globular domain. Circular dichroism, fluorescence, and NMR spectroscopies show that hFXN90-195 presents native-like secondary and tertiary structure. However, chemical and temperature induced denaturation show that CTR truncation significantly destabilizes the overall hFXN fold. Accordingly, limited proteolysis experiments suggest that the native-state dynamics of hFXN90-195 and hFXN90-210 are indeed different, being the former form much more sensitive to the protease at specific sites. The overall folding dynamics of hFXN fold was further explored with structure-based protein folding simulations. These suggest that the native ensemble of hFXN can be decomposed in at least two substates, one with consolidation of the CTR and the other without consolidation of the CTR. Explicit-solvent all atom simulations identify some of the proteolytic target sites as flexible regions of the protein. We propose that the local unfolding of CTR may be a critical step for the global unfolding of hFXN, and that modulation of the CTR interactions may strongly affect hFXN physiological function.
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Affiliation(s)
- Ernesto A. Roman
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Buenos Aires, Argentina
- Protein Physiology Laboratory, Departamento de Química Biológica-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Santiago E. Faraj
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Mariana Gallo
- Fundación Instituto Leloir and IIBBA-CONICET, Buenos Aires, Argentina
| | - Andres G. Salvay
- Instituto de Física de Líquidos y Sistemas Biológicos, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
- Departamento de Ciencia y Tecnología, Universidad Nacional Quilmes, Bernal, Provincia de Buenos Aires, Argentina
| | - Diego U. Ferreiro
- Protein Physiology Laboratory, Departamento de Química Biológica-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Javier Santos
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Buenos Aires, Argentina
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Martelli A, Napierala M, Puccio H. Understanding the genetic and molecular pathogenesis of Friedreich's ataxia through animal and cellular models. Dis Model Mech 2012; 5:165-76. [PMID: 22382366 PMCID: PMC3291638 DOI: 10.1242/dmm.008706] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In 1996, a link was identified between Friedreich's ataxia (FRDA), the most common inherited ataxia in men, and alterations in the gene encoding frataxin (FXN). Initial studies revealed that the disease is caused by a unique, most frequently biallelic, expansion of the GAA sequence in intron 1 of FXN. Since the identification of this link, there has been tremendous progress in understanding frataxin function and the mechanism of FRDA pathology, as well as in developing diagnostics and therapeutic approaches for the disease. These advances were the subject of the 4th International Friedreich's Ataxia Conference held on 5th-7th May in the Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France. More than 200 scientists gathered from all over the world to present the results of research spanning all areas of investigation into FRDA (including clinical aspects, FRDA pathogenesis, genetics and epigenetics of the disease, development of new models of FRDA, and drug discovery). This review provides an update on the understanding of frataxin function, developments of animal and cellular models of the disease, and recent advances in trying to uncover potential molecules for therapy.
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Affiliation(s)
- Alain Martelli
- Translational Medicine and Neurogenetics, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), 67404, Illkirch, France
- Inserm, U596, 67400, Illkirch, France
- CNRS, UMR7104, 67400, Illkirch, France
- Université de Strasbourg, 67000, Strasbourg, France
- Collège de France, Chaire de génétique humaine, 67400, Illkirch, France
| | - Marek Napierala
- The Department of Molecular Carcinogenesis, Center for Cancer Epigenetics, University of Texas MD Anderson Cancer Center Science Park, Smithville, TX, USA
| | - Hélène Puccio
- Translational Medicine and Neurogenetics, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), 67404, Illkirch, France
- Inserm, U596, 67400, Illkirch, France
- CNRS, UMR7104, 67400, Illkirch, France
- Université de Strasbourg, 67000, Strasbourg, France
- Collège de France, Chaire de génétique humaine, 67400, Illkirch, France
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50
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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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