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Scott V, Delatycki MB, Tai G, Corben LA. New and Emerging Drug and Gene Therapies for Friedreich Ataxia. CNS Drugs 2024; 38:791-805. [PMID: 39115603 PMCID: PMC11377510 DOI: 10.1007/s40263-024-01113-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/18/2024] [Indexed: 09/06/2024]
Abstract
The life shortening nature of Friedreich Ataxia (FRDA) demands the search for therapies that can delay, stop or reverse its relentless trajectory. This review provides a contemporary position of drug and gene therapies for FRDA currently in phase 1 clinical trials and beyond. Despite significant scientific advances in the specificity of both compounds and targets developed and investigated, challenges remain for the advancement of treatments in a limited recruitment population. Currently therapies focus on reducing oxidative stress and improving mitochondrial function, modulating frataxin controlled metabolic pathways and gene replacement and editing. Approval of omaveloxolone, the first treatment for individuals with FRDA aged 16 years and over, has created much excitement for both those living with FRDA and those that care for them. The process of approval of omaveloxolone by the US Food and Drug Administration highlighted the importance of sensitive outcome measures and the significant role of data from natural history studies.
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Affiliation(s)
- Varlli Scott
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Parkville, VIC, 3052, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Martin B Delatycki
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Parkville, VIC, 3052, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
- Victorian Clinical Genetics Service, Parkville, VIC, Australia
| | - Geneieve Tai
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Parkville, VIC, 3052, Australia
| | - Louise A Corben
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Parkville, VIC, 3052, Australia.
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, VIC, Australia.
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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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Pathak D, Srivastava AK, Padma MV, Gulati S, Rajeswari MR. Quantitative Proteomic and Network Analysis of Differentially Expressed Proteins in PBMC of Friedreich's Ataxia (FRDA) Patients. Front Neurosci 2019; 13:1054. [PMID: 31680804 PMCID: PMC6802492 DOI: 10.3389/fnins.2019.01054] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 09/19/2019] [Indexed: 11/23/2022] Open
Abstract
Friedreich’s ataxia (FRDA) is an autosomal recessive neurodegenerative disorder caused by an expanded (GAA) trinucleotide repeat in the FXN gene. The extended repeats expansion results in reduced transcription and, thereby, decreased expression of the mitochondrial protein, frataxin. Given the ongoing drug trials, identification of reliable and easily accessible biomarkers for monitoring disease progression and therapeutic intervention is a foremost requirement. In this study, comparative proteomic profiling of PBMC proteins from FRDA patients and age- and gender-matched healthy controls was done using 2D-Differential in-Gel Electrophoresis (2D-DIGE). Protein–protein interaction (PPI) was analyzed using BioGRID and STRING pathway analysis tools. Using biological variance analysis (BVA) and LC/MS, we found eight differentially expressed proteins with fold change ≥1.5; p ≤ 0.05. Based on their cellular function, the identified proteins showed a strong pathological role in neuroinflammation, cardiomyopathy, compromised glucose metabolism, and iron transport, which are the major clinical manifestations of FRDA. Protein–protein network analysis of differentially expressed proteins with frataxin further supports their involvement in the pathophysiology of FRDA. Considering their crucial role in the cardiac and neurological complications, respectively, the two down-regulated proteins, actin α cardiac muscle 1 (ACTC1) and pyruvate dehydrogenase E1 component subunit β (PDHE1), are suggested as potential prognostic markers for FRDA.
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Affiliation(s)
- Deepti Pathak
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, New Delhi, India
| | - Achal Kumar Srivastava
- Department of Neurology, All India Institute of Medical Sciences, New Delhi, New Delhi, India
| | - M V Padma
- Department of Neurology, All India Institute of Medical Sciences, New Delhi, New Delhi, India
| | - Sheffali Gulati
- Department of Paediatrics, All India Institute of Medical Sciences, New Delhi, New Delhi, India
| | - Moganty R Rajeswari
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, New Delhi, India
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Steinkellner H, Singh HN, Muckenthaler MU, Goldenberg H, Moganty RR, Scheiber-Mojdehkar B, Sturm B. No changes in heme synthesis in human Friedreich´s ataxia erythroid progenitor cells. Gene 2017; 621:5-11. [PMID: 28412459 DOI: 10.1016/j.gene.2017.04.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 04/03/2017] [Accepted: 04/04/2017] [Indexed: 12/28/2022]
Abstract
Friedreich's ataxia (FRDA) is a neurodegenerative disease caused by reduced expression of the protein frataxin. Frataxin is thought to play a role in iron-sulfur cluster biogenesis and heme synthesis. In this study, we used erythroid progenitor stem cells obtained from FRDA patients and healthy donors to investigate the putative role, if any, of frataxin deficiency in heme synthesis. We used electrochemiluminescence and qRT-PCR for frataxin protein and mRNA quantification. We used atomic absorption spectrophotometry for iron levels and a photometric assay for hemoglobin levels. Protoporphyrin IX and Ferrochelatase were analyzed using auto-fluorescence. An "IronChip" microarray analysis followed by a protein-protein interaction analysis was performed. FRDA patient cells showed no significant changes in iron levels, hemoglobin synthesis, protoporphyrin IX levels, and ferrochelatase activity. Microarray analysis presented 11 genes that were significantly changed in all patients compared to controls. The genes are especially involved in oxidative stress, iron homeostasis and angiogenesis. The mystery about the involvement of frataxin on iron metabolism raises the question why frataxin deficiency in primary FRDA cells did not lead to changes in biochemical parameters of heme synthesis. It seems that alternative pathways can circumvent the impact of frataxin deficiency on heme synthesis. We show for the first time in primary FRDA patient cells that reduced frataxin levels are still sufficient for heme synthesis and possibly other mechanisms can overcome reduced frataxin levels in this process. Our data strongly support the fact that so far no anemia in FRDA patients was reported.
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Affiliation(s)
- Hannes Steinkellner
- Department of Medical Chemistry and Pathobiochemistry, Medical University of Vienna, Vienna, Austria; Department of Medical Genetics, Medical University of Vienna, Vienna, Austria
| | - Himanshu Narayan Singh
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India
| | | | - Hans Goldenberg
- Department of Medical Chemistry and Pathobiochemistry, Medical University of Vienna, Vienna, Austria
| | - Rajeswari R Moganty
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India
| | | | - Brigitte Sturm
- Department of Medical Chemistry and Pathobiochemistry, Medical University of Vienna, Vienna, Austria.
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Wedding IM, Kroken M, Henriksen SP, Selmer KK, Fiskerstrand T, Knappskog PM, Berge T, Tallaksen CME. Friedreich ataxia in Norway - an epidemiological, molecular and clinical study. Orphanet J Rare Dis 2015; 10:108. [PMID: 26338206 PMCID: PMC4559212 DOI: 10.1186/s13023-015-0328-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 08/25/2015] [Indexed: 01/06/2023] Open
Abstract
Background Friedreich ataxia is an autosomal recessive hereditary spinocerebellar disorder, characterized by progressive limb and gait ataxia due to proprioceptive loss, often complicated by cardiomyopathy, diabetes and skeletal deformities. Friedreich ataxia is the most common hereditary ataxia, with a reported prevalence of 1:20 000 – 1:50 000 in Central Europe. Previous reports from south Norway have found a prevalence varying from 1:100 000 – 1:1 350 000; no studies are previously done in the rest of the country. Methods In this cross-sectional study, Friedreich ataxia patients were identified through colleagues in neurological, pediatric and genetic departments, hospital archives searches, patients’ associations, and National Centre for Rare Disorders. All included patients, carriers and controls were investigated clinically and molecularly with genotype characterization including size determination of GAA repeat expansions and frataxin measurements. 1376 healthy blood donors were tested for GAA repeat expansion for carrier frequency analysis. Results Twenty-nine Friedreich ataxia patients were identified in Norway, of which 23 were ethnic Norwegian, corresponding to a prevalence of 1:176 000 and 1:191 000, respectively. The highest prevalence was seen in the north. Carrier frequency of 1:196 (95 % CI = [1:752–1:112]) was found. Homozygous GAA repeat expansions in the FXN gene were found in 27/29, while two patients were compound heterozygous with c.467 T < C, L157P and the deletion (g.120032_122808del) including exon 5a. Two additional patients were heterozygous for GAA repeat expansions only. Significant differences in the level of frataxin were found between the included patients (N = 27), carriers (N = 37) and controls (N = 27). Conclusions In this first thorough study of a complete national cohort of Friedreich ataxia patients, and first nation-wide study of Friedreich ataxia in Norway, the prevalence of Friedreich ataxia in Norway is lower than in Central Europe, but higher than in the last Norwegian report, and as expected from migration studies. A south–north prevalence gradient is present. Based on Hardy Weinberg’s equilibrium, the carrier frequency of 1:196 is consistent with the observed prevalence. All genotypes, and typical and atypical phenotypes were present in the Norwegian population. The patients were phenotypically similar to European cohorts. Frataxin was useful in the diagnostic work-up of heterozygous symptomatic cases. Electronic supplementary material The online version of this article (doi:10.1186/s13023-015-0328-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Iselin Marie Wedding
- Department of Neurology, Oslo University Hospital, Ullevaal, 0407, Oslo, Norway. .,University of Oslo, Faculty of Medicine, Oslo, Norway.
| | - Mette Kroken
- Department of Medical Genetics, Oslo University Hospital, Ullevaal, 0407, Oslo, Norway
| | | | - Kaja Kristine Selmer
- Department of Medical Genetics, Oslo University Hospital, Ullevaal, 0407, Oslo, Norway.,University of Oslo, Faculty of Medicine, Oslo, Norway
| | - Torunn Fiskerstrand
- Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Per Morten Knappskog
- Department of Clinical Science, University of Bergen, Bergen, Norway.,Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Tone Berge
- Department of Neurology, Oslo University Hospital, Ullevaal, 0407, Oslo, Norway
| | - Chantal M E Tallaksen
- Department of Neurology, Oslo University Hospital, Ullevaal, 0407, Oslo, Norway.,University of Oslo, Faculty of Medicine, Oslo, Norway
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Swarup V, Srivastava AK, Padma MV, Rajeswari MR. Quantitative profiling and identification of differentially expressed plasma proteins in friedreich's ataxia. J Neurosci Res 2013; 91:1483-91. [DOI: 10.1002/jnr.23262] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 05/11/2013] [Accepted: 05/21/2013] [Indexed: 12/11/2022]
Affiliation(s)
- Vishnu Swarup
- Department of Biochemistry; All India Institute of Medical Sciences; New Delhi India
| | - Achal K. Srivastava
- Department of Neurology; All India Institute of Medical Sciences; New Delhi India
| | - Madakasira V. Padma
- Department of Neurology; All India Institute of Medical Sciences; New Delhi India
| | - Moganty R. Rajeswari
- Department of Biochemistry; All India Institute of Medical Sciences; New Delhi India
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Yandim C, Natisvili T, Festenstein R. Gene regulation and epigenetics in Friedreich's ataxia. J Neurochem 2013; 126 Suppl 1:21-42. [PMID: 23859339 DOI: 10.1111/jnc.12254] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 02/05/2013] [Accepted: 03/06/2013] [Indexed: 12/20/2022]
Abstract
This is an exciting time in the study of Friedreich's ataxia. Over the last 10 years much progress has been made in uncovering the mechanisms, whereby the Frataxin gene is silenced by (GAA)n repeat expansions and several of the findings are now ripe for testing in the clinic. The discovery that the Frataxin gene is heterochromatinised and that this can be antagonised in vivo has led to the tantalizing possibility that the disease might be amenable to a more radical therapeutic approach involving epigenetic modifiers. Here, we set out to review progress in the understanding of the fundamental mechanisms whereby genes are regulated at this level and how these findings have been applied to achieve a deeper understanding of the dysregulation that occurs as the primary genetic lesion in Friedreich's ataxia.
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Affiliation(s)
- Cihangir Yandim
- Gene Control Mechanisms and Disease, Department of Medicine and MRC Clinical Sciences Centre, Imperial College London, London, UK
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Hasuike Y, Nagai T, Yorifuji S, Tanaka S, Matsumoto A, Yahiro M, Kaibe S, Kida A, Tokuyama M, Nagasawa Y, Otaki Y, Kuragano T, Nakanishi T. The mitochondrial protein frataxin is downregulated in hemodialysis patients. Clin Exp Nephrol 2013; 17:424-30. [PMID: 23180044 DOI: 10.1007/s10157-012-0737-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 11/04/2012] [Indexed: 10/27/2022]
Abstract
BACKGROUND The mitochondrial protein frataxin regulates iron metabolism for heme and iron sulfur cluster synthesis in the mitochondria and could be associated with the regulation of oxidative stress. To clarify the expression of frataxin and its association with uremia, we evaluated the mRNA and protein levels of frataxin in the polymorphonuclear leukocytes (PMNLs) of patients on hemodialysis (HD). METHODS Uremic patients on HD (n = 18) and healthy control subjects (n = 18) were investigated. PMNLs were isolated by differential centrifugation. The mRNA levels of frataxin in isolated leukocytes were quantified by TaqMan real-time polymerase chain reaction. Frataxin protein expression in the cell lysate was evaluated using SDS-polyacrylamide gel electrophoresis and Western blotting. RESULTS The frataxin/glyceraldehyde-3-phosphate dehydrogenase mRNA ratio in PMNLs from uremic patients was significantly lower than that in control subjects. Frataxin protein expression in uremic patients was also significantly lower than that in controls. Multiple regression analysis showed that frataxin mRNA levels were independently associated with the serum levels of both the oxidative stress marker malondialdehyde and the proinflammatory cytokine tumor necrosis factor-α. CONCLUSION The downregulation of frataxin seems to be linked with uremic status, which is usually associated with chronic inflammation and the acceleration of oxidative stress. Mitochondrial iron regulation may play a role in several comorbidities and in the poor prognosis in uremic patients. Further investigation is needed to elucidate whether reduced frataxin levels are linked to the pathological status of uremic patients and whether uremic substances affect frataxin expression.
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Affiliation(s)
- Yukiko Hasuike
- Division of Kidney and Dialysis, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, 663-8501, Japan.
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Bandiera S, Cartault F, Jannot AS, Hatem E, Girard M, Rifai L, Loiseau C, Munnich A, Lyonnet S, Henrion-Caude A. Genetic variations creating microRNA target sites in the FXN 3'-UTR affect frataxin expression in Friedreich ataxia. PLoS One 2013; 8:e54791. [PMID: 23382970 PMCID: PMC3559822 DOI: 10.1371/journal.pone.0054791] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 12/14/2012] [Indexed: 11/18/2022] Open
Abstract
Friedreich's ataxia (FRDA) is a severe neurodegenerative disease caused by GAA repeat expansion within the first intron of the frataxin gene. It has been suggested that the repeat is responsible for the disease severity due to impaired transcription thereby reducing expression of the protein. However, genotype-phenotype correlation is imperfect, and the influence of other gene regions of the frataxin gene is unknown. We hypothesized that FRDA patients may harbor specific regulatory variants in the 3'-UTR. We sequenced the 3'-UTR region of the frataxin gene in a cohort of 57 FRDA individuals and 58 controls. Seven single nucleotide polymorphisms (SNPs) out of 19 were polymorphic in our case-control sample. These SNPs defined several haplotypes with one reaching 89% of homozygosity in patients versus 24% in controls. In another cohort of 47 FRDA Reunionese patients, 94% patients were found to be homozygous for this haplotype. We found that this FRDA 3'-UTR conferred a 1.2-fold decrease in the expression of a reporter gene versus the alternative haplotype configuration. We established that differential targeting by miRNA could account for this functional variability. We specifically demonstrated the involvement of miR-124 (i.e hsa-mir-124-3p) in the down-regulation of FRDA-3'-UTR. Our results suggest for the first time that post-transcriptional regulation of frataxin occurs through the 3'-UTR and involves miRNA targeting. We propose that the involvement of miRNAs in a FRDA-specific regulation of frataxin may provide a rationale to increase residual levels of frataxin through miRNA-inhibitory molecules.
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Affiliation(s)
- Simonetta Bandiera
- INSERM U781 Hôpital Necker–Enfants Malades, Université Paris Descartes-Sorbonne Cité, Institut Imagine, Paris, France
| | - François Cartault
- INSERM U781 Hôpital Necker–Enfants Malades, Paris, France
- Département de Génétique, Centre Hospitalier Régional de La Réunion, Saint-Denis, La Réunion, France
| | - Anne-Sophie Jannot
- INSERM U781 Hôpital Necker–Enfants Malades, Université Paris Descartes-Sorbonne Cité, Institut Imagine, Paris, France
| | - Elie Hatem
- INSERM U781 Hôpital Necker–Enfants Malades, Paris, France
| | - Muriel Girard
- INSERM U781 Hôpital Necker–Enfants Malades, Université Paris Descartes-Sorbonne Cité, Institut Imagine, Paris, France
| | - Laila Rifai
- Department of Medical Genetics, National Institute of Health, Rabat, Morocco
| | | | - Arnold Munnich
- INSERM U781 Hôpital Necker–Enfants Malades, Université Paris Descartes-Sorbonne Cité, Institut Imagine, Paris, France
| | - Stanislas Lyonnet
- INSERM U781 Hôpital Necker–Enfants Malades, Université Paris Descartes-Sorbonne Cité, Institut Imagine, Paris, France
| | - Alexandra Henrion-Caude
- INSERM U781 Hôpital Necker–Enfants Malades, Université Paris Descartes-Sorbonne Cité, Institut Imagine, Paris, France
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Xia H, Cao Y, Dai X, Marelja Z, Zhou D, Mo R, Al-Mahdawi S, Pook MA, Leimkühler S, Rouault TA, Li K. Novel frataxin isoforms may contribute to the pathological mechanism of Friedreich ataxia. PLoS One 2012; 7:e47847. [PMID: 23082224 PMCID: PMC3474739 DOI: 10.1371/journal.pone.0047847] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 09/21/2012] [Indexed: 12/12/2022] Open
Abstract
Friedreich ataxia (FRDA) is an inherited neurodegenerative disease caused by frataxin (FXN) deficiency. The nervous system and heart are the most severely affected tissues. However, highly mitochondria-dependent tissues, such as kidney and liver, are not obviously affected, although the abundance of FXN is normally high in these tissues. In this study we have revealed two novel FXN isoforms (II and III), which are specifically expressed in affected cerebellum and heart tissues, respectively, and are functional in vitro and in vivo. Increasing the abundance of the heart-specific isoform III significantly increased the mitochondrial aconitase activity, while over-expression of the cerebellum-specific isoform II protected against oxidative damage of Fe-S cluster-containing aconitase. Further, we observed that the protein level of isoform III decreased in FRDA patient heart, while the mRNA level of isoform II decreased more in FRDA patient cerebellum compared to total FXN mRNA. Our novel findings are highly relevant to understanding the mechanism of tissue-specific pathology in FRDA.
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Affiliation(s)
- Haiyan Xia
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
| | - Yun Cao
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Xiaoman Dai
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Zvonimir Marelja
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Di Zhou
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Ran Mo
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
| | - Sahar Al-Mahdawi
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Mark A. Pook
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, United Kingdom
| | - Silke Leimkühler
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Tracey A. Rouault
- Molecular Medicine Program, National Institute of Child Health and Human Development, Bethesda, Maryland, United States of America
| | - Kuanyu Li
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, China
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
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11
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Corben LA, Georgiou-Karistianis N, Bradshaw JL, Evans-Galea MV, Churchyard AJ, Delatycki MB. Characterising the neuropathology and neurobehavioural phenotype in Friedreich ataxia: a systematic review. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 769:169-84. [PMID: 23560311 DOI: 10.1007/978-1-4614-5434-2_11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Friedreich ataxia (FRDA), the most common of the hereditary ataxias, is an autosomal recessive, multisystem disorder characterised by progressive ataxia, sensory symptoms, weakness, scoliosis and cardiomyopathy. FRDA is caused by a GAA expansion in intron one of the FXN gene, leading to reduced levels of the encoded protein frataxin, which is thought to regulate cellular iron homeostasis. The cerebellar and spinocerebellar dysfunction seen in FRDA has known effects on motor function; however until recently slowed information processing has been the main feature consistently reported by the limited studies addressing cognitive function in FRDA. This chapter will systematically review the current literature regarding the neuropathological and neurobehavioural phenotype associated with FRDA. It will evaluate more recent evidence adopting systematic experimental methodologies that postulate that the neurobehavioural phenotype associated with FRDA is likely to involve impairment in cerebello-cortico connectivity.
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Affiliation(s)
- Louise A Corben
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, The Royal Children's Hospital, Parkville, Victoria, Australia.
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Kim E, Napierala M, Dent SYR. Hyperexpansion of GAA repeats affects post-initiation steps of FXN transcription in Friedreich's ataxia. Nucleic Acids Res 2011; 39:8366-77. [PMID: 21745819 PMCID: PMC3201871 DOI: 10.1093/nar/gkr542] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 06/12/2011] [Accepted: 06/13/2011] [Indexed: 12/19/2022] Open
Abstract
Friedreich's ataxia (FRDA) is caused by biallelic expansion of GAA repeats leading to the transcriptional silencing of the frataxin (FXN) gene. The exact molecular mechanism of inhibition of FXN expression is unclear. Herein, we analyze the effects of hyperexpanded GAA repeats on transcription status and chromatin modifications proximal and distal to the GAA repeats. Using chromatin immunoprecipitation and quantitative PCR we detected significant changes in the chromatin landscape in FRDA cells relative to control cells downstream of the promoter, especially in the vicinity of the GAA tract. In this region, hyperexpanded GAAs induced a particular constellation of histone modifications typically associated with heterochromatin-like structures. Similar epigenetic changes were observed in GFP reporter construct containing 560 GAA repeats. Furthermore, we observed similar levels of FXN pre-mRNA at a region upstream of hyperexpanded GAA repeats in FRDA and control cells, indicating similar efficiency of transcription initiation. We also demonstrated that histone modifications associated with hyperexpanded GAA repeats are independent of initiation and progression of transcription. Our data provide strong evidence that FXN deficiency in FRDA patients results from a block of transition from initiation to a productive elongation of FXN transcription due to heterochromatin-like structures formed in the proximity of the hyperexpanded GAAs.
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Affiliation(s)
- Eunah Kim
- The Department of Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center Science Park, Smithville, Texas 78957 and The Genes and Development Program, Graduate School of Biomedical Sciences and the Center for Cancer Epigenetics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Marek Napierala
- The Department of Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center Science Park, Smithville, Texas 78957 and The Genes and Development Program, Graduate School of Biomedical Sciences and the Center for Cancer Epigenetics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Sharon Y. R. Dent
- The Department of Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center Science Park, Smithville, Texas 78957 and The Genes and Development Program, Graduate School of Biomedical Sciences and the Center for Cancer Epigenetics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
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Tsai CL, Bridwell-Rabb J, Barondeau DP. Friedreich's ataxia variants I154F and W155R diminish frataxin-based activation of the iron-sulfur cluster assembly complex. Biochemistry 2011; 50:6478-87. [PMID: 21671584 PMCID: PMC3319458 DOI: 10.1021/bi200666h] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease that has been linked to defects in the protein frataxin (Fxn). Most FRDA patients have a GAA expansion in the first intron of their Fxn gene that decreases protein expression. Some FRDA patients have a GAA expansion on one allele and a missense mutation on the other allele. Few functional details are known for the ∼15 different missense mutations identified in FRDA patients. Here in vitro evidence is presented that indicates the FRDA I154F and W155R variants bind more weakly to the complex of Nfs1, Isd11, and Isu2 and thereby are defective in forming the four-component SDUF complex that constitutes the core of the Fe-S cluster assembly machine. The binding affinities follow the trend Fxn ∼ I154F > W155F > W155A ∼ W155R. The Fxn variants also have diminished ability to function as part of the SDUF complex to stimulate the cysteine desulfurase reaction and facilitate Fe-S cluster assembly. Four crystal structures, including the first for a FRDA variant, reveal specific rearrangements associated with the loss of function and lead to a model for Fxn-based activation of the Fe-S cluster assembly complex. Importantly, the weaker binding and lower activity for FRDA variants correlate with the severity of disease progression. Together, these results suggest that Fxn facilitates sulfur transfer from Nfs1 to Isu2 and that these in vitro assays are sensitive and appropriate for deciphering functional defects and mechanistic details for human Fe-S cluster biosynthesis.
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Saccà F, Puorro G, Antenora A, Marsili A, Denaro A, Piro R, Sorrentino P, Pane C, Tessa A, Brescia Morra V, Cocozza S, De Michele G, Santorelli FM, Filla A. A combined nucleic acid and protein analysis in Friedreich ataxia: implications for diagnosis, pathogenesis and clinical trial design. PLoS One 2011; 6:e17627. [PMID: 21412413 PMCID: PMC3055871 DOI: 10.1371/journal.pone.0017627] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 02/03/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Friedreich's ataxia (FRDA) is the most common hereditary ataxia among caucasians. The molecular defect in FRDA is the trinucleotide GAA expansion in the first intron of the FXN gene, which encodes frataxin. No studies have yet reported frataxin protein and mRNA levels in a large cohort of FRDA patients, carriers and controls. METHODOLOGY/PRINCIPAL FINDINGS We enrolled 24 patients with classic FRDA phenotype (cFA), 6 late onset FRDA (LOFA), all homozygous for GAA expansion, 5 pFA cases who harbored the GAA expansion in compound heterozygosis with FXN point mutations (namely, p.I154F, c.482+3delA, p.R165P), 33 healthy expansion carriers, and 29 healthy controls. DNA was genotyped for GAA expansion, mRNA/FXN was quantified in real-time, and frataxin protein was measured using lateral-flow immunoassay in peripheral blood mononuclear cells (PBMCs). Mean residual levels of frataxin, compared to controls, were 35.8%, 65.6%, 33%, and 68.7% in cFA, LOFA, pFA and healthy carriers, respectively. Comparison of both cFA and pFA with controls resulted in 100% sensitivity and specificity, but there was overlap between LOFA, carriers and controls. Frataxin levels correlated inversely with GAA1 and GAA2 expansions, and directly with age at onset. Messenger RNA expression was reduced to 19.4% in cFA, 50.4% in LOFA, 52.7% in pFA, 53.0% in carriers, as compared to controls (p<0.0001). mRNA levels proved to be diagnostic when comparing cFA with controls resulting in 100% sensitivity and specificity. In cFA and LOFA patients mRNA levels correlated directly with protein levels and age at onset, and inversely with GAA1 and GAA2. CONCLUSION/SIGNIFICANCE We report the first explorative study on combined frataxin and mRNA levels in PBMCs from a cohort of FRDA patients, carriers and healthy individuals. Lateral-flow immunoassay differentiated cFA and pFA patients from controls, whereas determination of mRNA in q-PCR was sensitive and specific only in cFA.
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Affiliation(s)
- Francesco Saccà
- Department of Neurological Sciences, University Federico II, Naples, Italy.
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