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Dong YN, Mercado-Ayón E, Coulman J, Flatley L, Ngaba LV, Adeshina MW, Lynch DR. The Regulation of the Disease-Causing Gene FXN. Cells 2024; 13:1040. [PMID: 38920668 PMCID: PMC11202134 DOI: 10.3390/cells13121040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 06/10/2024] [Accepted: 06/13/2024] [Indexed: 06/27/2024] Open
Abstract
Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease caused in almost all patients by expanded guanine-adenine-adenine (GAA) trinucleotide repeats within intron 1 of the FXN gene. This results in a relative deficiency of frataxin, a small nucleus-encoded mitochondrial protein crucial for iron-sulfur cluster biogenesis. Currently, there is only one medication, omaveloxolone, available for FRDA patients, and it is limited to patients 16 years of age and older. This necessitates the development of new medications. Frataxin restoration is one of the main strategies in potential treatment options as it addresses the root cause of the disease. Comprehending the control of frataxin at the transcriptional, post-transcriptional, and post-translational stages could offer potential therapeutic approaches for addressing the illness. This review aims to provide a general overview of the regulation of frataxin and its implications for a possible therapeutic treatment of FRDA.
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Affiliation(s)
- Yi Na Dong
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Jennifer Coulman
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Liam Flatley
- The Wharton School, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lucie Vanessa Ngaba
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Miniat W. Adeshina
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - David R. Lynch
- Departments of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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2
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Kojak N, Kuno J, Fittipaldi KE, Khan A, Wenger D, Glasser M, Donnianni RA, Tang Y, Zhang J, Huling K, Ally R, Mujica AO, Turner T, Magardino G, Huang PY, Kerk SY, Droguett G, Prissette M, Rojas J, Gomez T, Gagliardi A, Hunt C, Rabinowitz JS, Gong G, Poueymirou W, Chiao E, Zambrowicz B, Siao CJ, Kajimura D. Somatic and intergenerational G4C2 hexanucleotide repeat instability in a human C9orf72 knock-in mouse model. Nucleic Acids Res 2024; 52:5732-5755. [PMID: 38597682 PMCID: PMC11162798 DOI: 10.1093/nar/gkae250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 03/19/2024] [Accepted: 03/28/2024] [Indexed: 04/11/2024] Open
Abstract
Expansion of a G4C2 repeat in the C9orf72 gene is associated with familial Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD). To investigate the underlying mechanisms of repeat instability, which occurs both somatically and intergenerationally, we created a novel mouse model of familial ALS/FTD that harbors 96 copies of G4C2 repeats at a humanized C9orf72 locus. In mouse embryonic stem cells, we observed two modes of repeat expansion. First, we noted minor increases in repeat length per expansion event, which was dependent on a mismatch repair pathway protein Msh2. Second, we found major increases in repeat length per event when a DNA double- or single-strand break (DSB/SSB) was artificially introduced proximal to the repeats, and which was dependent on the homology-directed repair (HDR) pathway. In mice, the first mode primarily drove somatic repeat expansion. Major changes in repeat length, including expansion, were observed when SSB was introduced in one-cell embryos, or intergenerationally without DSB/SSB introduction if G4C2 repeats exceeded 400 copies, although spontaneous HDR-mediated expansion has yet to be identified. These findings provide a novel strategy to model repeat expansion in a non-human genome and offer insights into the mechanism behind C9orf72 G4C2 repeat instability.
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Affiliation(s)
- Nada Kojak
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | - Junko Kuno
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | | | - David Wenger
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | | | - Yajun Tang
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | - Jade Zhang
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | - Katie Huling
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | - Roxanne Ally
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | | | | | - Pei Yi Huang
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | - Sze Yen Kerk
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | | | - Jose Rojas
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | | | | | | | - Guochun Gong
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | - Eric Chiao
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
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Currò R, Dominik N, Facchini S, Vegezzi E, Sullivan R, Galassi Deforie V, Fernández-Eulate G, Traschütz A, Rossi S, Garibaldi M, Kwarciany M, Taroni F, Brusco A, Good JM, Cavalcanti F, Hammans S, Ravenscroft G, Roxburgh RH, Parolin Schnekenberg R, Rugginini B, Abati E, Manini A, Quartesan I, Ghia A, Lòpez de Munaìn A, Manganelli F, Kennerson M, Santorelli FM, Infante J, Marques W, Jokela M, Murphy SM, Mandich P, Fabrizi GM, Briani C, Gosal D, Pareyson D, Ferrari A, Prados F, Yousry T, Khurana V, Kuo SH, Miller J, Troakes C, Jaunmuktane Z, Giunti P, Hartmann A, Basak N, Synofzik M, Stojkovic T, Hadjivassiliou M, Reilly MM, Houlden H, Cortese A. Role of the repeat expansion size in predicting age of onset and severity in RFC1 disease. Brain 2024; 147:1887-1898. [PMID: 38193360 PMCID: PMC11068103 DOI: 10.1093/brain/awad436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/04/2023] [Accepted: 12/10/2023] [Indexed: 01/10/2024] Open
Abstract
RFC1 disease, caused by biallelic repeat expansion in RFC1, is clinically heterogeneous in terms of age of onset, disease progression and phenotype. We investigated the role of the repeat size in influencing clinical variables in RFC1 disease. We also assessed the presence and role of meiotic and somatic instability of the repeat. In this study, we identified 553 patients carrying biallelic RFC1 expansions and measured the repeat expansion size in 392 cases. Pearson's coefficient was calculated to assess the correlation between the repeat size and age at disease onset. A Cox model with robust cluster standard errors was adopted to describe the effect of repeat size on age at disease onset, on age at onset of each individual symptoms, and on disease progression. A quasi-Poisson regression model was used to analyse the relationship between phenotype and repeat size. We performed multivariate linear regression to assess the association of the repeat size with the degree of cerebellar atrophy. Meiotic stability was assessed by Southern blotting on first-degree relatives of 27 probands. Finally, somatic instability was investigated by optical genome mapping on cerebellar and frontal cortex and unaffected peripheral tissue from four post-mortem cases. A larger repeat size of both smaller and larger allele was associated with an earlier age at neurological onset [smaller allele hazard ratio (HR) = 2.06, P < 0.001; larger allele HR = 1.53, P < 0.001] and with a higher hazard of developing disabling symptoms, such as dysarthria or dysphagia (smaller allele HR = 3.40, P < 0.001; larger allele HR = 1.71, P = 0.002) or loss of independent walking (smaller allele HR = 2.78, P < 0.001; larger allele HR = 1.60; P < 0.001) earlier in disease course. Patients with more complex phenotypes carried larger expansions [smaller allele: complex neuropathy rate ratio (RR) = 1.30, P = 0.003; cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) RR = 1.34, P < 0.001; larger allele: complex neuropathy RR = 1.33, P = 0.008; CANVAS RR = 1.31, P = 0.009]. Furthermore, larger repeat expansions in the smaller allele were associated with more pronounced cerebellar vermis atrophy (lobules I-V β = -1.06, P < 0.001; lobules VI-VII β = -0.34, P = 0.005). The repeat did not show significant instability during vertical transmission and across different tissues and brain regions. RFC1 repeat size, particularly of the smaller allele, is one of the determinants of variability in RFC1 disease and represents a key prognostic factor to predict disease onset, phenotype and severity. Assessing the repeat size is warranted as part of the diagnostic test for RFC1 expansion.
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Affiliation(s)
- Riccardo Currò
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
| | - Natalia Dominik
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Stefano Facchini
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
| | | | - Roisin Sullivan
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | | | - Gorka Fernández-Eulate
- Nord/Est/Ile-de-France Neuromuscular Reference Center, Institute of Myology, Pitié-Salpêtrière Hospital, APHP, 75013 Paris, France
| | - Andreas Traschütz
- Research Division ‘Translational Genomics of Neurodegenerative Diseases’, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, 72076 Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, 72076 Tübingen, Germany
| | - Salvatore Rossi
- Dipartimento di Scienze dell'Invecchiamento, Neurologiche, Ortopediche e della Testa-Collo, UOC Neurologia, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy
- Facoltà di Medicina e Chirurgia, Dipartimento di Neuroscienze, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Matteo Garibaldi
- Neuromuscular and Rare Disease Center, Department of Neuroscience, Mental Health and Sensory Organs (NESMOS), Sant'Andrea Hospital, Sapienza University of Rome, 00189 Rome, Italy
| | - Mariusz Kwarciany
- Department of Adult Neurology, Medical University of Gdańsk, 80-952 Gdańsk, Poland
| | - Franco Taroni
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | - Alfredo Brusco
- Department of Medical Sciences, University of Torino, 10124 Turin, Italy
| | - Jean-Marc Good
- Division of Genetic Medicine, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
| | - Francesca Cavalcanti
- Institute for Biomedical Research and Innovation (IRIB), Italian National Research Council (CNR), 87050 Mangone, Italy
| | - Simon Hammans
- Wessex Neurological Centre, Southampton General Hospital, Southampton, SO16 6YD, UK
| | - Gianina Ravenscroft
- Neurogenetic Diseases Group, Centre for Medical Research, QEII Medical Centre, University of Western Australia, Nedland, WA 6009, Australia
| | - Richard H Roxburgh
- Neurology Department, Auckland City Hospital, New Zealand and the Centre for Brain Research, University of Auckland, Auckland 1142, New Zealand
| | | | - Bianca Rugginini
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
| | - Elena Abati
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
- Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy
| | - Arianna Manini
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
- Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy
| | - Ilaria Quartesan
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
| | - Arianna Ghia
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
| | - Adolfo Lòpez de Munaìn
- Neurology Department, Donostia University Hospital, University of the Basque Country-Osakidetza-CIBERNED-Biodonostia, 20014 Donostia-San Sebastián, Spain
| | - Fiore Manganelli
- Department of Neuroscience and Reproductive and Odontostomatological Sciences, University of Naples Federico II, 80131 Naples, Italy
| | - Marina Kennerson
- Sydney Medical School, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2050, Australia
| | - Filippo Maria Santorelli
- IRCCS Stella Maris Foundation, Molecular Medicine for Neurodegenerative and Neuromuscular Disease Unit, 56128 Pisa, Italy
| | - Jon Infante
- University Hospital Marquès de Valdecilla-IDIVAL, University of Cantabria, 39008 Santander, Spain
| | - Wilson Marques
- Department of Neurology, School of Medicine of Ribeirão Preto, University of São Paulo, 2650 Ribeirão Preto, Brazil
| | - Manu Jokela
- Neuromuscular Research Center, Department of Neurology, Tampere University and University Hospital, 33520 Tampere, Finland
- Neurocenter, Department of Neurology, Clinical Neurosciences, Turku University Hospital and University of Turku, 20014 Turku, Finland
| | - Sinéad M Murphy
- Department of Neurology, Tallaght University Hospital, D24 NR0A Dublin, Ireland
- Academic Unit of Neurology, Trinity College Dublin, D02 R590 Dublin, Ireland
| | - Paola Mandich
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, 16132 Genoa, Italy
- IRCCS Ospedale Policlinico San Martino-UOC Genetica Medica, 16132 Genova, Italy
| | - Gian Maria Fabrizi
- Department of Neurosciences, Biomedicine, and Movement Sciences, University of Verona, 37134 Verona, Italy
| | - Chiara Briani
- Department of Neurosciences, ERN Neuromuscular Unit, University of Padova, 35100 Padova, Italy
| | - David Gosal
- Manchester Centre for Clinical Neurosciences, Salford Royal Hospital, Northern Care Alliance NHS Foundation Trust, Greater Manchester, M6 8HD, UK
| | - Davide Pareyson
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan 20133, Italy
| | | | - Ferran Prados
- Centre for Medical Image Computing (CMIC), Department of Medical Physics and Biomedical Engineering, University College London, London, WC1V 6LJ, UK
- NMR Research Unit, Institute of Neurology, University College London (UCL), London, WC1N 3BG, UK
- e-Health Centre, Universitat Oberta de Catalunya, 08018 Barcelona, Spain
| | - Tarek Yousry
- Neuroradiological Academic Unit, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Vikram Khurana
- Division of Movement Disorders and Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Sheng-Han Kuo
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - James Miller
- Department of Neurology, Royal Victoria Hospitals, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle, NE1 4LP, UK
| | - Claire Troakes
- London Neurodegenerative Diseases Brain Bank, Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, SE21 8EA, UK
| | - Zane Jaunmuktane
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Paola Giunti
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Annette Hartmann
- Division of General Psychiatry, Medical University of Vienna, 1090 Vienna, Austria
| | - Nazli Basak
- Koç University, School of Medicine, Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Research Center for Translational Medicine, 34010 Istanbul, Turkey
| | - Matthis Synofzik
- Research Division ‘Translational Genomics of Neurodegenerative Diseases’, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, 72076 Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, 72076 Tübingen, Germany
| | - Tanya Stojkovic
- Nord/Est/Ile-de-France Neuromuscular Reference Center, Institute of Myology, Pitié-Salpêtrière Hospital, APHP, 75013 Paris, France
| | - Marios Hadjivassiliou
- Academic Department of Neurosciences, Sheffield Teaching Hospitals NHS Trust and University of Sheffield, Sheffield, S10 2JF, UK
| | - Mary M Reilly
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Henry Houlden
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Andrea Cortese
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
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4
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Lynch DR, Rojsajjakul T, Subramony SH, Perlman SL, Keita M, Mesaros C, Blair IA. Frataxin analysis using triple quadrupole mass spectrometry: application to a large heterogeneous clinical cohort. J Neurol 2024; 271:1844-1849. [PMID: 38063871 DOI: 10.1007/s00415-023-12118-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 01/23/2024]
Abstract
BACKGROUND Friedreich ataxia is a progressive multisystem disorder caused by deficiency of the protein frataxin; a small mitochondrial protein involved in iron sulfur cluster synthesis. Two types of frataxin exist: FXN-M, found in most cells, and FXN-E, found almost exclusively in red blood cells. Treatments in clinical trials include frataxin restoration by gene therapy, protein replacement, and epigenetic therapies, all of which necessitate sensitive assays for assessing frataxin levels. METHODS In the present study, we have used a triple quadrupole mass spectrometry-based assay to examine the features of both types of frataxin levels in blood in a large heterogenous cohort of 106 patients with FRDA. RESULTS Frataxin levels (FXN-E and FXN M) were predicted by GAA repeat length in regression models (R2 values = 0.51 and 0.27, respectively), and conversely frataxin levels predicted clinical status as determined by modified Friedreich Ataxia Rating scale scores and by disability status (R2 values = 0.13-0.16). There was no significant change in frataxin levels in individual subjects over time, and apart from start codon mutations, FXN-E and FXN-M levels were roughly equal. Accounting for hemoglobin levels in a smaller sub-cohort improved prediction of both FXN-E and FXN-M levels from R2 values of (0.3-0.38 to 0.20-0.51). CONCLUSION The present data show that assay of FXN-M and FXN-E levels in blood provides an appropriate biofluid for assessing their repletion in particular clinical contexts.
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Affiliation(s)
- David R Lynch
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, 502F Abramson Research Center, 3615 Civic Center Blvd, Philadelphia, PA, 19104-4318, USA.
| | - Teerapat Rojsajjakul
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - S H Subramony
- Department of Neurology, University of Florida, Gainesville, FL, 32608, USA
| | - Susan L Perlman
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, 90095, USA
| | - Medina Keita
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Clementina Mesaros
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ian A Blair
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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5
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Mätlik K, Baffuto M, Kus L, Deshmukh AL, Davis DA, Paul MR, Carroll TS, Caron MC, Masson JY, Pearson CE, Heintz N. Cell-type-specific CAG repeat expansions and toxicity of mutant Huntingtin in human striatum and cerebellum. Nat Genet 2024; 56:383-394. [PMID: 38291334 PMCID: PMC10937393 DOI: 10.1038/s41588-024-01653-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 12/28/2023] [Indexed: 02/01/2024]
Abstract
Brain region-specific degeneration and somatic expansions of the mutant Huntingtin (mHTT) CAG tract are key features of Huntington's disease (HD). However, the relationships among CAG expansions, death of specific cell types and molecular events associated with these processes are not established. Here, we used fluorescence-activated nuclear sorting (FANS) and deep molecular profiling to gain insight into the properties of cell types of the human striatum and cerebellum in HD and control donors. CAG expansions arise at mHTT in striatal medium spiny neurons (MSNs), cholinergic interneurons and cerebellar Purkinje neurons, and at mutant ATXN3 in MSNs from SCA3 donors. CAG expansions in MSNs are associated with higher levels of MSH2 and MSH3 (forming MutSβ), which can inhibit nucleolytic excision of CAG slip-outs by FAN1. Our data support a model in which CAG expansions are necessary but may not be sufficient for cell death and identify transcriptional changes associated with somatic CAG expansions and striatal toxicity.
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Affiliation(s)
- Kert Mätlik
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Matthew Baffuto
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Laura Kus
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Amit Laxmikant Deshmukh
- Program of Genetics & Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - David A Davis
- Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Matthew R Paul
- Bioinformatics Resource Center, The Rockefeller University, New York, NY, USA
| | - Thomas S Carroll
- Bioinformatics Resource Center, The Rockefeller University, New York, NY, USA
| | - Marie-Christine Caron
- CHU de Québec Research Center, Oncology Division, Laval University Cancer Research Center, Quebec City, Quebec, Canada
| | - Jean-Yves Masson
- CHU de Québec Research Center, Oncology Division, Laval University Cancer Research Center, Quebec City, Quebec, Canada
| | - Christopher E Pearson
- Program of Genetics & Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Nathaniel Heintz
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA.
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6
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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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7
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Rastokina A, Cebrián J, Mozafari N, Mandel NH, Smith CI, Lopes M, Zain R, Mirkin S. Large-scale expansions of Friedreich's ataxia GAA•TTC repeats in an experimental human system: role of DNA replication and prevention by LNA-DNA oligonucleotides and PNA oligomers. Nucleic Acids Res 2023; 51:8532-8549. [PMID: 37216608 PMCID: PMC10484681 DOI: 10.1093/nar/gkad441] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 05/02/2023] [Accepted: 05/20/2023] [Indexed: 05/24/2023] Open
Abstract
Friedreich's ataxia (FRDA) is caused by expansions of GAA•TTC repeats in the first intron of the human FXN gene that occur during both intergenerational transmissions and in somatic cells. Here we describe an experimental system to analyze large-scale repeat expansions in cultured human cells. It employs a shuttle plasmid that can replicate from the SV40 origin in human cells or be stably maintained in S. cerevisiae utilizing ARS4-CEN6. It also contains a selectable cassette allowing us to detect repeat expansions that accumulated in human cells upon plasmid transformation into yeast. We indeed observed massive expansions of GAA•TTC repeats, making it the first genetically tractable experimental system to study large-scale repeat expansions in human cells. Further, GAA•TTC repeats stall replication fork progression, while the frequency of repeat expansions appears to depend on proteins implicated in replication fork stalling, reversal, and restart. Locked nucleic acid (LNA)-DNA mixmer oligonucleotides and peptide nucleic acid (PNA) oligomers, which interfere with triplex formation at GAA•TTC repeats in vitro, prevented the expansion of these repeats in human cells. We hypothesize, therefore, that triplex formation by GAA•TTC repeats stall replication fork progression, ultimately leading to repeat expansions during replication fork restart.
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Affiliation(s)
| | - Jorge Cebrián
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Negin Mozafari
- Department of Laboratory Medicine, Translational Research Center Karolinska (TRACK), Karolinska Institutet, Karolinska University Hospital, SE-171 77 Stockholm, Sweden
| | | | - C I Edvard Smith
- Department of Laboratory Medicine, Translational Research Center Karolinska (TRACK), Karolinska Institutet, Karolinska University Hospital, SE-171 77 Stockholm, Sweden
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zurich, Zurich 8057, Switzerland
| | - Rula Zain
- Department of Laboratory Medicine, Translational Research Center Karolinska (TRACK), Karolinska Institutet, Karolinska University Hospital, SE-171 77 Stockholm, Sweden
- Center for Rare Diseases, Karolinska University Hospital, SE-17176 Stockholm, Sweden
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02155, USA
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8
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Mätlik K, Baffuto M, Kus L, Deshmukh AL, Davis DA, Paul MR, Carroll TS, Caron MC, Masson JY, Pearson CE, Heintz N. Cell Type Specific CAG Repeat Expansions and Toxicity of Mutant Huntingtin in Human Striatum and Cerebellum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.24.538082. [PMID: 37333326 PMCID: PMC10274669 DOI: 10.1101/2023.04.24.538082] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Brain region-specific degeneration and somatic expansions of the mutant Huntingtin (mHTT) CAG tract are key features of Huntington's disease (HD). However, the relationships between CAG expansions, death of specific cell types, and molecular events associated with these processes are not established. Here we employed fluorescence-activated nuclear sorting (FANS) and deep molecular profiling to gain insight into the properties of cell types of the human striatum and cerebellum in HD and control donors. CAG expansions arise in striatal medium spiny neurons (MSNs) and cholinergic interneurons, in cerebellar Purkinje neurons, and at mATXN3 in MSNs from SCA3 donors. CAG expansions in MSNs are associated with higher levels of MSH2 and MSH3 (forming MutSβ), which can inhibit nucleolytic excision of CAG slip-outs by FAN1 in a concentration-dependent manner. Our data indicate that ongoing CAG expansions are not sufficient for cell death, and identify transcriptional changes associated with somatic CAG expansions and striatal toxicity.
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9
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Rodden LN, Rummey C, Kessler S, Wilson RB, Lynch DR. A Novel Metric for Predicting Severity of Disease Features in Friedreich's Ataxia. Mov Disord 2023. [PMID: 36928898 DOI: 10.1002/mds.29370] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 01/25/2023] [Accepted: 02/16/2023] [Indexed: 03/18/2023] Open
Abstract
BACKGROUND Friedreich's ataxia (FRDA), most commonly caused by a GAA triplet repeat (GAA-TR) expansion in intron 1 of the FXN gene, is characterized by deficiency of frataxin protein and clinical features such as progressive ataxia, dysarthria, impaired proprioception and vibration, abolished deep tendon reflexes, Babinski sign, and vision loss in association with non-neurological features such as skeletal anomalies, hearing loss, cardiomyopathy, and diabetes. Pathogenic GAA-TRs range in size from 60 to 1500 triplets and negatively correlate with age of onset. Clinical severity is predicted by a combination of GAA-TR length and disease duration (DD) via multivariable regressions, which cannot typically be used for the small sample sizes in most studies on this rare disease. OBJECTIVE We aimed to develop a single metric, which we call "disease burden" (DB), that encompasses both GAA-TR length and DD for predicting disease features of FRDA in small sample sizes. METHODS Linear regression and multivariable regression analysis was used to determine correlation coefficients between different disease features of FRDA. RESULTS Using large datasets for validation, we found that DB predicts measures of neurological dysfunction in FRDA better than GAA-TR length or DD. Analogous results were found using small datasets. CONCLUSIONS FRDA DB is a novel metric of disease severity that has utility in small datasets to demonstrate correlations that would not otherwise be evident with either GAA-TR or DD alone. This is important for discovering new biomarkers, as well as improving the prediction of severity of disease features in FRDA. © 2023 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Layne N Rodden
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Sudha Kessler
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Robert B Wilson
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - David R Lynch
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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10
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Kalef-Ezra E, Edzeamey FJ, Valle A, Khonsari H, Kleine P, Oggianu C, Al-Mahdawi S, Pook MA, Anjomani Virmouni S. A new FRDA mouse model [ Fxn null:YG8s(GAA) > 800] with more than 800 GAA repeats. Front Neurosci 2023; 17:930422. [PMID: 36777637 PMCID: PMC9909538 DOI: 10.3389/fnins.2023.930422] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 01/04/2023] [Indexed: 01/27/2023] Open
Abstract
Introduction Friedreich's ataxia (FRDA) is an inherited recessive neurodegenerative disorder caused by a homozygous guanine-adenine-adenine (GAA) repeat expansion within intron 1 of the FXN gene, which encodes the essential mitochondrial protein frataxin. There is still no effective therapy for FRDA, therefore the development of optimal cell and animal models of the disease is one of the priorities for preclinical therapeutic testing. Methods We obtained the latest FRDA humanized mouse model that was generated on the basis of our previous YG8sR, by Jackson laboratory [YG8JR, Fxn null:YG8s(GAA) > 800]. We characterized the behavioral, cellular, molecular and epigenetics properties of the YG8JR model, which has the largest GAA repeat sizes compared to all the current FRDA mouse models. Results We found statistically significant behavioral deficits, together with reduced levels of frataxin mRNA and protein, and aconitase activity in YG8JR mice compared with control Y47JR mice. YG8JR mice exhibit intergenerational GAA repeat instability by the analysis of parent and offspring tissue samples. Somatic GAA repeat instability was also detected in individual brain and cerebellum tissue samples. In addition, increased DNA methylation of CpG U13 was identified in FXN GAA repeat region in the brain, cerebellum, and heart tissues. Furthermore, we show decreased histone H3K9 acetylation and increased H3K9 methylation of YG8JR cerebellum tissues within the FXN gene, upstream and downstream of the GAA repeat region compared to Y47JR controls. Discussion These studies provide a detailed characterization of the GAA repeat expansion-based YG8JR transgenic mouse models that will help investigations of FRDA disease mechanisms and therapy.
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Affiliation(s)
- Ester Kalef-Ezra
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Fred Jonathan Edzeamey
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Adamo Valle
- Energy Metabolism and Nutrition, Research Institute of Health Sciences (IUNICS), University of Balearic Islands, Palma, Spain,Health Research Institute of Balearic Islands (IdISBa), Palma, Spain,Biomedical Research Networking Center for Physiopathology of Obesity and Nutrition (CIBERobn CB06/03/0043), Instituto de Salud Carlos III, Madrid, Spain
| | - Hassan Khonsari
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Paula Kleine
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Carlo Oggianu
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Sahar Al-Mahdawi
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Mark A. Pook
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Sara Anjomani Virmouni
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom,*Correspondence: Sara Anjomani Virmouni,
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11
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Ashraf M, Kazmi SU, Tariq H, Munır A, Rehman R. Association of trinucleotide repeat polymorphisms CAG and GGC in exon 1 of the androgen receptor gene with male infertility: a cross-sectional study. Turk J Med Sci 2022; 52:1793-1801. [PMID: 36945970 PMCID: PMC10390128 DOI: 10.55730/1300-0144.5525] [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: 05/06/2020] [Accepted: 09/10/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND : Infertility is a global problem that brings about serious sexual and social consequences that strain the health sector and society. The expansion of CAG and GGC repeats in androgen receptor (AR) gene (Ensembl number ENSG00000169083) may lead to reduced fertility. Our objective was to determine the association of CAG and GGC repeats with altered sperm parameters in male infertile subjects. METHODS This was a cross-sectional study conducted at Aga Khan University, Karachi, Pakistan. A total of 376 males were recruited, out of which group A (N = 208) and group B (N = 168) were comprised of subjects with normal and altered sperm parameters, respectively, from 18 to 60 years. The numbers of CAG and GGC repeats were determined by using PCR amplification and sequence analysis using the Molecular Evolutionary Genetic Analysis (MEGA) software version 6.0. Statistical analysis was performed using the SPSS version 20 and the P-value of <0.05 was considered significant. RESULTS The mean androgen receptor gene CAG repeats were significantly longer in males with altered sperm parameters as compared to male subjects with normal sperm parameters (P < 0.001). There was no significant difference found for GGC repeats for subjects with altered sperm parameters. DISCUSSION Longer CAG length corresponded to greater severity of spermatogenic defect and may lead to subfertility recommendations.
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Affiliation(s)
- Mussarat Ashraf
- Department of Biological and Biomedical Sciences, Medical College, Aga Khan University, Karachi, Pakistan
| | - Shahana Urooj Kazmi
- Department of Clinical Microbiology and Immunology, Faculty of Science, Dadabhoy Institute of Higher Education, Karachi, Pakistan
| | - Hemaila Tariq
- Department of Biological and Biomedical Sciences, Medical College, Aga Khan University, Karachi, Pakistan
| | - Adnan Munır
- Department of Urology, Medical College, Liaquat National Hospital, Karachi, Pakistan
| | - Rehana Rehman
- Department of Biological and Biomedical Sciences, Medical College, Aga Khan University, Karachi, Pakistan
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12
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Angulo MB, Bertalovitz A, Argenziano MA, Yang J, Patel A, Zesiewicz T, McDonald TV. Frataxin deficiency alters gene expression in Friedreich ataxia derived IPSC-neurons and cardiomyocytes. Mol Genet Genomic Med 2022; 11:e2093. [PMID: 36369844 PMCID: PMC9834160 DOI: 10.1002/mgg3.2093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 09/16/2022] [Accepted: 10/27/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Friedreich's ataxia (FRDA) is an autosomal recessive disease, whereby homozygous inheritance of an expanded GAA trinucleotide repeat expansion in the first intron of the FXN gene leads to transcriptional repression of the encoded protein frataxin. FRDA is a progressive neurodegenerative disorder, but the primary cause of death is heart disease which occurs in 60% of the patients. Several functions of frataxin have been proposed, but none of them fully explain why its deficiency causes the FRDA phenotypes nor why the most affected cell types are neurons and cardiomyocytes. METHODS To investigate, we generated iPSC-derived neurons (iNs) and cardiomyocytes (iCMs) from an FRDA patient and upregulated FXN expression via lentivirus without altering genomic GAA repeats at the FXN locus. RESULTS RNA-seq and differential gene expression enrichment analyses demonstrated that frataxin deficiency affected the expression of glycolytic pathway genes in neurons and extracellular matrix pathway genes in cardiomyocytes. Genes in these pathways were differentially expressed when compared to a control and restored to control levels when FRDA cells were supplemented with frataxin. CONCLUSIONS These results offer novel insight into specific roles of frataxin deficiency pathogenesis in neurons and cardiomyocytes.
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Affiliation(s)
- Mariana B. Angulo
- Heart Institute, Morsani College of Medicine, University of South FloridaTampaFloridaUSA,Department of Molecular Pharmacology & PhysiologyMorsani College of Medicine, University of South FloridaTampaFloridaUSA
| | - Alexander Bertalovitz
- Heart Institute, Morsani College of Medicine, University of South FloridaTampaFloridaUSA,Department of Medicine (Cardiology)Morsani College of Medicine, University of South FloridaTampaFloridaUSA
| | - Mariana A. Argenziano
- Heart Institute, Morsani College of Medicine, University of South FloridaTampaFloridaUSA
| | - Jiajia Yang
- Heart Institute, Morsani College of Medicine, University of South FloridaTampaFloridaUSA,Department of Molecular Pharmacology & PhysiologyMorsani College of Medicine, University of South FloridaTampaFloridaUSA
| | - Aarti Patel
- Department of Medicine (Cardiology)Morsani College of Medicine, University of South FloridaTampaFloridaUSA
| | - Theresa Zesiewicz
- Department of NeurologyMorsani College of Medicine, University of South FloridaTampaFloridaUSA
| | - Thomas V. McDonald
- Heart Institute, Morsani College of Medicine, University of South FloridaTampaFloridaUSA,Department of Molecular Pharmacology & PhysiologyMorsani College of Medicine, University of South FloridaTampaFloridaUSA,Department of Medicine (Cardiology)Morsani College of Medicine, University of South FloridaTampaFloridaUSA
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13
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Li Y, Li J, Wang J, Zhang S, Giles K, Prakash TP, Rigo F, Napierala JS, Napierala M. Premature transcription termination at the expanded GAA repeats and aberrant alternative polyadenylation contributes to the Frataxin transcriptional deficit in Friedreich's ataxia. Hum Mol Genet 2022; 31:3539-3557. [PMID: 35708503 PMCID: PMC9558844 DOI: 10.1093/hmg/ddac134] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/12/2022] [Accepted: 06/05/2022] [Indexed: 11/18/2022] Open
Abstract
Frataxin deficiency in Friedreich's ataxia results from transcriptional downregulation of the FXN gene caused by expansion of the intronic trinucleotide guanine-adenine-adenine (GAA) repeats. We used multiple transcriptomic approaches to determine the molecular mechanism of transcription inhibition caused by long GAAs. We uncovered that transcription of FXN in patient cells is prematurely terminated upstream of the expanded repeats leading to the formation of a novel, truncated and stable RNA. This FXN early terminated transcript (FXN-ett) undergoes alternative, non-productive splicing and does not contribute to the synthesis of functional frataxin. The level the FXN-ett RNA directly correlates with the length of the longer of the two expanded GAA tracts. Targeting GAAs with antisense oligonucleotides or excision of the repeats eliminates the transcription impediment, diminishes expression of the aberrant FXN-ett, while increasing levels of FXN mRNA and frataxin. Non-productive transcription may represent a common phenomenon and attractive therapeutic target in diseases caused by repeat-mediated transcription aberrations.
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Affiliation(s)
- Yanjie Li
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Jixue Li
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Jun Wang
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Siyuan Zhang
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Keith Giles
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Thazha P Prakash
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Frank Rigo
- Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Jill S Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
- Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA
| | - Marek Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
- Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA
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14
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Masnovo C, Lobo AF, Mirkin SM. Replication dependent and independent mechanisms of GAA repeat instability. DNA Repair (Amst) 2022; 118:103385. [PMID: 35952488 PMCID: PMC9675320 DOI: 10.1016/j.dnarep.2022.103385] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/28/2022] [Accepted: 07/30/2022] [Indexed: 11/20/2022]
Abstract
Trinucleotide repeat instability is a driver of human disease. Large expansions of (GAA)n repeats in the first intron of the FXN gene are the cause Friedreich's ataxia (FRDA), a progressive degenerative disorder which cannot yet be prevented or treated. (GAA)n repeat instability arises during both replication-dependent processes, such as cell division and intergenerational transmission, as well as in terminally differentiated somatic tissues. Here, we provide a brief historical overview on the discovery of (GAA)n repeat expansions and their association to FRDA, followed by recent advances in the identification of triplex H-DNA formation and replication fork stalling. The main body of this review focuses on the last decade of progress in understanding the mechanism of (GAA)n repeat instability during DNA replication and/or DNA repair. We propose that the discovery of additional mechanisms of (GAA)n repeat instability can be achieved via both comparative approaches to other repeat expansion diseases and genome-wide association studies. Finally, we discuss the advances towards FRDA prevention or amelioration that specifically target (GAA)n repeat expansions.
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Affiliation(s)
- Chiara Masnovo
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Ayesha F Lobo
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02155, USA.
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15
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Payne RM. Cardiovascular Research in Friedreich Ataxia: Unmet Needs and Opportunities. JACC Basic Transl Sci 2022; 7:1267-1283. [PMID: 36644283 PMCID: PMC9831864 DOI: 10.1016/j.jacbts.2022.04.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/18/2022] [Accepted: 04/18/2022] [Indexed: 01/18/2023]
Abstract
Friedreich Ataxia (FRDA) is an autosomal recessive disease in which a mitochondrial protein, frataxin, is severely decreased in its expression. In addition to progressive ataxia, patients with FRDA often develop a cardiomyopathy that can be hypertrophic. This cardiomyopathy is unlike the sarcomeric hypertrophic cardiomyopathies in that the hypertrophy is associated with massive mitochondrial proliferation within the cardiomyocyte rather than contractile protein overexpression. This is associated with atrial arrhythmias, apoptosis, and fibrosis over time, and patients often develop heart failure leading to premature death. The differences between this mitochondrial cardiomyopathy and the more common contractile protein hypertrophic cardiomyopathies can be a source of misunderstanding in the management of these patients. Although imaging studies have revealed much about the structure and function of the heart in this disease, we still lack an understanding of many important clinical and fundamental molecular events that determine outcome of the heart in FRDA. This review will describe the current basic and clinical understanding of the FRDA heart, and most importantly, identify major gaps in our knowledge that represent new directions and opportunities for research.
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Affiliation(s)
- R. Mark Payne
- Address for correspondence: Dr R. Mark Payne, Division of Pediatric Cardiology, Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 West Walnut, R4 302b, Indianapolis, Indiana 46202, USA.
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16
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Quiat D, Kim SW, Zhang Q, Morton SU, Pereira AC, DePalma SR, Willcox JAL, McDonough B, DeLaughter DM, Gorham JM, Curran JJ, Tumblin M, Nicolau Y, Artunduaga MA, Quintanilla-Dieck L, Osorno G, Serrano L, Hamdan U, Eavey RD, Seidman CE, Seidman JG. An ancient founder mutation located between ROBO1 and ROBO2 is responsible for increased microtia risk in Amerindigenous populations. Proc Natl Acad Sci U S A 2022; 119:e2203928119. [PMID: 35584116 PMCID: PMC9173816 DOI: 10.1073/pnas.2203928119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 04/12/2022] [Indexed: 01/14/2023] Open
Abstract
Microtia is a congenital malformation that encompasses mild hypoplasia to complete loss of the external ear, or pinna. Although the contribution of genetic variation and environmental factors to microtia remains elusive, Amerindigenous populations have the highest reported incidence. Here, using both transmission disequilibrium tests and association studies in microtia trios (parents and affected child) and microtia cohorts enrolled in Latin America, we map an ∼10-kb microtia locus (odds ratio = 4.7; P = 6.78e-18) to the intergenic region between Roundabout 1 (ROBO1) and Roundabout 2 (ROBO2) (chr3: 78546526 to 78555137). While alleles at the microtia locus significantly increase the risk of microtia, their penetrance is low (<1%). We demonstrate that the microtia locus contains a polymorphic complex repeat element that is expanded in affected individuals. The locus is located near a chromatin loop region that regulates ROBO1 and ROBO2 expression in induced pluripotent stem cell–derived neural crest cells. Furthermore, we use single nuclear RNA sequencing to demonstrate ROBO1 and ROBO2 expression in both fibroblasts and chondrocytes of the mature human pinna. Because the microtia allele is enriched in Amerindigenous populations and is shared by some East Asian subjects with craniofacial malformations, we propose that both populations share a mutation that arose in a common ancestor prior to the ancient migration of Eurasian populations into the Americas and that the high incidence of microtia among Amerindigenous populations reflects the population bottleneck that occurred during the migration out of Eurasia.
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Affiliation(s)
- Daniel Quiat
- Department of Cardiology, Boston Children’s Hospital, Boston, MA 02115
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115
- Department of Genetics, Harvard Medical School, Boston, MA 02115
| | - Seong Won Kim
- Department of Genetics, Harvard Medical School, Boston, MA 02115
| | - Qi Zhang
- Department of Genetics, Harvard Medical School, Boston, MA 02115
| | - Sarah U. Morton
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115
- Department of Genetics, Harvard Medical School, Boston, MA 02115
- Division of Newborn Medicine, Department of Medicine, Boston Children’s Hospital, Boston, MA 02115
| | - Alexandre C. Pereira
- Department of Genetics, Harvard Medical School, Boston, MA 02115
- Laboratory of Genetics and Molecular Cardiology, Heart Institute, Medical School of University of Sao Paulo, Sao Paulo, 05508-060, Brazil
| | | | | | | | | | - Joshua M. Gorham
- Department of Genetics, Harvard Medical School, Boston, MA 02115
| | - Justin J. Curran
- Department of Genetics, Harvard Medical School, Boston, MA 02115
| | | | | | | | - Lourdes Quintanilla-Dieck
- Department of Otolaryngology Head and Neck Surgery, Oregon Health & Science University, Portland, OR 97239
| | - Gabriel Osorno
- Facultad de Medicina, Universidad Nacional de Colombia, Bogotá, 111321, Colombia
| | | | | | - Roland D. Eavey
- Department of Otolaryngology Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Christine E. Seidman
- Department of Genetics, Harvard Medical School, Boston, MA 02115
- Cardiovascular Division, Brigham and Women’s Hospital, Boston, MA 02115
- HHMI, Chevy Chase, MD 20815
| | - J. G. Seidman
- Department of Genetics, Harvard Medical School, Boston, MA 02115
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17
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Rodden LN, Gilliam KM, Lam C, Rojsajjakul T, Mesaros C, Dionisi C, Pook M, Pandolfo M, Lynch DR, Blair IA, Bidichandani SI. DNA methylation in Friedreich ataxia silences expression of frataxin isoform E. Sci Rep 2022; 12:5031. [PMID: 35322126 PMCID: PMC8943190 DOI: 10.1038/s41598-022-09002-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 03/14/2022] [Indexed: 11/15/2022] Open
Abstract
Epigenetic silencing in Friedreich ataxia (FRDA), induced by an expanded GAA triplet-repeat in intron 1 of the FXN gene, results in deficiency of the mitochondrial protein, frataxin. A lesser known extramitochondrial isoform of frataxin detected in erythrocytes, frataxin-E, is encoded via an alternate transcript (FXN-E) originating in intron 1 that lacks a mitochondrial targeting sequence. We show that FXN-E is deficient in FRDA, including in patient-derived cell lines, iPS-derived proprioceptive neurons, and tissues from a humanized mouse model. In a series of FRDA patients, deficiency of frataxin-E protein correlated with the length of the expanded GAA triplet-repeat, and with repeat-induced DNA hypermethylation that occurs in close proximity to the intronic origin of FXN-E. CRISPR-induced epimodification to mimic DNA hypermethylation seen in FRDA reproduced FXN-E transcriptional deficiency. Deficiency of frataxin E is a consequence of FRDA-specific epigenetic silencing, and therapeutic strategies may need to address this deficiency.
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Affiliation(s)
- Layne N Rodden
- Department of Pediatrics, University of Oklahoma Health Sciences Center, OU Children's Physician Building, Suite 12100, 1200 Children's Avenue, Oklahoma City, OK, 73104, USA
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Kaitlyn M Gilliam
- Department of Pediatrics, University of Oklahoma Health Sciences Center, OU Children's Physician Building, Suite 12100, 1200 Children's Avenue, Oklahoma City, OK, 73104, USA
| | - Christina Lam
- Department of Pediatrics, University of Oklahoma Health Sciences Center, OU Children's Physician Building, Suite 12100, 1200 Children's Avenue, Oklahoma City, OK, 73104, USA
| | - Teerapat Rojsajjakul
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Clementina Mesaros
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Mark Pook
- Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UK
| | - Massimo Pandolfo
- Université Libre de Bruxelles (ULB), Brussels, Belgium
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - David R Lynch
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Ian A Blair
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sanjay I Bidichandani
- Department of Pediatrics, University of Oklahoma Health Sciences Center, OU Children's Physician Building, Suite 12100, 1200 Children's Avenue, Oklahoma City, OK, 73104, USA.
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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18
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Kilikevicius A, Wang J, Shen X, Rigo F, Prakash TP, Napierala M, Corey DR. Difficulties translating antisense-mediated activation of Frataxin expression from cell culture to mice. RNA Biol 2021; 19:364-372. [PMID: 35289725 PMCID: PMC8928816 DOI: 10.1080/15476286.2022.2043650] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 02/11/2022] [Indexed: 11/09/2022] Open
Abstract
Friedreich's ataxia (FA) is an inherited neurodegenerative disorder caused by decreased expression of frataxin (FXN) protein. Previous studies have shown that antisense oligonucleotides (ASOs) and single-stranded silencing RNAs can be used to increase expression of frataxin in cultured patient-derived cells. In this study, we investigate the potential for oligonucleotides to increase frataxin expression in a mouse model for FA. After confirming successful in vivo delivery of oligonucleotides using a benchmark gapmer targeting the nuclear noncoding RNA Malat1, we tested anti-FXN oligonucleotides designed to function by various mechanisms. None of these strategies yielded enhanced expression of FXN in the model mice. Our inability to translate activation of FXN expression from cell culture to mice may be due to inadequate potency of our compounds or differences in the molecular mechanisms governing FXN gene repression and activation in FA model mice.
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Affiliation(s)
- Audrius Kilikevicius
- Department of Pharmacology and Biochemistry, UT Southwestern Medical Center, Dallas, Texas, United States
| | - Jun Wang
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd, Birmingham, Alabama, USA
| | - Xiulong Shen
- Department of Pharmacology and Biochemistry, UT Southwestern Medical Center, Dallas, Texas, United States
| | - Frank Rigo
- Ionis Pharmaceuticals, Medicinal Chemistry and Antisense Research, Carlsbad, California, USA
| | - Thahza P. Prakash
- Ionis Pharmaceuticals, Medicinal Chemistry and Antisense Research, Carlsbad, California, USA
| | - Marek Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd, Birmingham, Alabama, USA
- Department of Neurology, UT Southwestern Medical Center, Dallas, Texas, USA
| | - David R. Corey
- Department of Pharmacology and Biochemistry, UT Southwestern Medical Center, Dallas, Texas, United States
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19
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Wieben ED, Aleff RA, Rinkoski TA, Baratz KH, Basu S, Patel SV, Maguire LJ, Fautsch MP. Comparison of TCF4 repeat expansion length in corneal endothelium and leukocytes of patients with Fuchs endothelial corneal dystrophy. PLoS One 2021; 16:e0260837. [PMID: 34855896 PMCID: PMC8638873 DOI: 10.1371/journal.pone.0260837] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 11/17/2021] [Indexed: 12/13/2022] Open
Abstract
Expansion of CTG trinucleotide repeats (TNR) in the transcription factor 4 (TCF4) gene is highly associated with Fuchs Endothelial Corneal Dystrophy (FECD). Due to limitations in the availability of DNA from diseased corneal endothelium, sizing of CTG repeats in FECD patients has typically been determined using DNA samples isolated from peripheral blood leukocytes. However, it is non-feasible to extract enough DNA from surgically isolated FECD corneal endothelial tissue to determine repeat length based on current technology. To circumvent this issue, total RNA was isolated from FECD corneal endothelium and sequenced using long-read sequencing. Southern blotting of DNA samples isolated from primary cultures of corneal endothelium from these same affected individuals was also assessed. Both long read sequencing and Southern blot analysis showed significantly longer CTG TNR expansion (>1000 repeats) in the corneal endothelium from FECD patients than those characterized in leukocytes from the same individuals (<90 repeats). Our findings suggest that the TCF4 CTG repeat expansions in the FECD corneal endothelium are much longer than those found in leukocytes.
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Affiliation(s)
- Eric D. Wieben
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Ross A. Aleff
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Tommy A. Rinkoski
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Keith H. Baratz
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Shubham Basu
- Division of Biostatistics and Bioinformatics and Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Sanjay V. Patel
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Leo J. Maguire
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Michael P. Fautsch
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United states of America
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20
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Replication-independent instability of Friedreich's ataxia GAA repeats during chronological aging. Proc Natl Acad Sci U S A 2021; 118:2013080118. [PMID: 33495349 PMCID: PMC7865128 DOI: 10.1073/pnas.2013080118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The inheritance of long (GAA)n repeats in the frataxin gene causes the debilitating neurodegenerative disease Friedreich’s ataxia. Subsequent expansions of these repeats throughout a patient’s lifetime in the affected tissues, like the nervous system, may contribute to disease onset. We developed an experimental model to characterize the mechanisms of repeat instability in nondividing cells to better understand how mutations can occur as cells age chronologically. We show that repeats can expand in nondividing cells. Notably, however, large deletions are the major type of repeat-mediated genome instability in nondividing cells, implicating the loss of important genetic material with aging in the progression of Friedreich’s ataxia. Nearly 50 hereditary diseases result from the inheritance of abnormally long repetitive DNA microsatellites. While it was originally believed that the size of inherited repeats is the key factor in disease development, it has become clear that somatic instability of these repeats throughout an individual’s lifetime strongly contributes to disease onset and progression. Importantly, somatic instability is commonly observed in terminally differentiated, postmitotic cells, such as neurons. To unravel the mechanisms of repeat instability in nondividing cells, we created an experimental system to analyze the mutability of Friedreich’s ataxia (GAA)n repeats during chronological aging of quiescent Saccharomyces cerevisiae. Unexpectedly, we found that the predominant repeat-mediated mutation in nondividing cells is large-scale deletions encompassing parts, or the entirety, of the repeat and adjacent regions. These deletions are caused by breakage at the repeat mediated by mismatch repair (MMR) complexes MutSβ and MutLα and DNA endonuclease Rad1, followed by end-resection by Exo1 and repair of the resulting double-strand breaks (DSBs) via nonhomologous end joining. We also observed repeat-mediated gene conversions as a result of DSB repair via ectopic homologous recombination during chronological aging. Repeat expansions accrue during chronological aging as well—particularly in the absence of MMR-induced DSBs. These expansions depend on the processivity of DNA polymerase δ while being counteracted by Exo1 and MutSβ, implicating nick repair. Altogether, these findings show that the mechanisms and types of (GAA)n repeat instability differ dramatically between dividing and nondividing cells, suggesting that distinct repeat-mediated mutations in terminally differentiated somatic cells might influence Friedreich’s ataxia pathogenesis.
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21
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Generation of a Friedreich's Ataxia patient-derived iPSC line USFi001-A. Stem Cell Res 2021; 54:102399. [PMID: 34034220 DOI: 10.1016/j.scr.2021.102399] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 11/21/2022] Open
Abstract
Friedreich's Ataxia (FA) is an autosomal recessive disorder with an incidence of 1 in 50,000 in Caucasians. Most cases are caused by a biallelic GAA expansion in the first intron of the Frataxin (FXN) gene. FA is a neurodegenerative disease, but the leading cause of death is hypertrophic cardiomyopathy (HCM) that develops in 60% of the patients. We generated an induced pluripotent stem cell (iPSC) line from an FA patient with a homozygous GAA expansion in intron 1 of the FXN gene. The IPSCs display pluripotent cell morphology, expression of pluripotency markers, normal karyotype, and the capability to differentiate into all three germ layers.
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22
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Ocana-Santero G, Díaz-Nido J, Herranz-Martín S. Future Prospects of Gene Therapy for Friedreich's Ataxia. Int J Mol Sci 2021; 22:1815. [PMID: 33670433 PMCID: PMC7918362 DOI: 10.3390/ijms22041815] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/04/2021] [Accepted: 02/06/2021] [Indexed: 12/18/2022] Open
Abstract
Friedreich's ataxia is an autosomal recessive neurogenetic disease that is mainly associated with atrophy of the spinal cord and progressive neurodegeneration in the cerebellum. The disease is caused by a GAA-expansion in the first intron of the frataxin gene leading to a decreased level of frataxin protein, which results in mitochondrial dysfunction. Currently, there is no effective treatment to delay neurodegeneration in Friedreich's ataxia. A plausible therapeutic approach is gene therapy. Indeed, Friedreich's ataxia mouse models have been treated with viral vectors en-coding for either FXN or neurotrophins, such as brain-derived neurotrophic factor showing promising results. Thus, gene therapy is increasingly consolidating as one of the most promising therapies. However, several hurdles have to be overcome, including immunotoxicity and pheno-toxicity. We review the state of the art of gene therapy in Friedreich's ataxia, addressing the main challenges and the most feasible solutions for them.
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Affiliation(s)
- Gabriel Ocana-Santero
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Departamento de Biología Molecular, Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain; (G.O.-S.); (J.D.-N.)
- Department of Physiology, Anatomy and Genetics, Sherrington Building, Parks Road, University of Oxford, Oxford OX1 3PT, UK
| | - Javier Díaz-Nido
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Departamento de Biología Molecular, Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain; (G.O.-S.); (J.D.-N.)
| | - Saúl Herranz-Martín
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Departamento de Biología Molecular, Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain; (G.O.-S.); (J.D.-N.)
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23
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Zhao X, Kumari D, Miller CJ, Kim GY, Hayward B, Vitalo AG, Pinto RM, Usdin K. Modifiers of Somatic Repeat Instability in Mouse Models of Friedreich Ataxia and the Fragile X-Related Disorders: Implications for the Mechanism of Somatic Expansion in Huntington's Disease. J Huntingtons Dis 2021; 10:149-163. [PMID: 33579860 PMCID: PMC7990428 DOI: 10.3233/jhd-200423] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Huntington's disease (HD) is one of a large group of human disorders that are caused by expanded DNA repeats. These repeat expansion disorders can have repeat units of different size and sequence that can be located in any part of the gene and, while the pathological consequences of the expansion can differ widely, there is evidence to suggest that the underlying mutational mechanism may be similar. In the case of HD, the expanded repeat unit is a CAG trinucleotide located in exon 1 of the huntingtin (HTT) gene, resulting in an expanded polyglutamine tract in the huntingtin protein. Expansion results in neuronal cell death, particularly in the striatum. Emerging evidence suggests that somatic CAG expansion, specifically expansion occurring in the brain during the lifetime of an individual, contributes to an earlier disease onset and increased severity. In this review we will discuss mouse models of two non-CAG repeat expansion diseases, specifically the Fragile X-related disorders (FXDs) and Friedreich ataxia (FRDA). We will compare and contrast these models with mouse and patient-derived cell models of various other repeat expansion disorders and the relevance of these findings for somatic expansion in HD. We will also describe additional genetic factors and pathways that modify somatic expansion in the FXD mouse model for which no comparable data yet exists in HD mice or humans. These additional factors expand the potential druggable space for diseases like HD where somatic expansion is a significant contributor to disease impact.
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Affiliation(s)
- Xiaonan Zhao
- Laboratory of Cell and Molecular Biology, National Institutes of Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Daman Kumari
- Laboratory of Cell and Molecular Biology, National Institutes of Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Carson J Miller
- Laboratory of Cell and Molecular Biology, National Institutes of Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Geum-Yi Kim
- Laboratory of Cell and Molecular Biology, National Institutes of Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Bruce Hayward
- Laboratory of Cell and Molecular Biology, National Institutes of Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Antonia G Vitalo
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Ricardo Mouro Pinto
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.,Department of Neurology, Harvard Medical School, Boston, MA, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Karen Usdin
- Laboratory of Cell and Molecular Biology, National Institutes of Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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24
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Sabitha KR, Shetty AK, Upadhya D. Patient-derived iPSC modeling of rare neurodevelopmental disorders: Molecular pathophysiology and prospective therapies. Neurosci Biobehav Rev 2020; 121:201-219. [PMID: 33370574 DOI: 10.1016/j.neubiorev.2020.12.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 12/18/2020] [Accepted: 12/19/2020] [Indexed: 12/12/2022]
Abstract
The pathological alterations that manifest during the early embryonic development due to inherited and acquired factors trigger various neurodevelopmental disorders (NDDs). Besides major NDDs, there are several rare NDDs, exhibiting specific characteristics and varying levels of severity triggered due to genetic and epigenetic anomalies. The rarity of subjects, paucity of neural tissues for detailed analysis, and the unavailability of disease-specific animal models have hampered detailed comprehension of rare NDDs, imposing heightened challenge to the medical and scientific community until a decade ago. The generation of functional neurons and glia through directed differentiation protocols for patient-derived iPSCs, CRISPR/Cas9 technology, and 3D brain organoid models have provided an excellent opportunity and vibrant resource for decoding the etiology of brain development for rare NDDs caused due to monogenic as well as polygenic disorders. The present review identifies cellular and molecular phenotypes demonstrated from patient-derived iPSCs and possible therapeutic opportunities identified for these disorders. New insights to reinforce the existing knowledge of the pathophysiology of these disorders and prospective therapeutic applications are discussed.
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Affiliation(s)
- K R Sabitha
- Centre for Molecular Neurosciences, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | - Ashok K Shetty
- Institute for Regenerative Medicine, Department of Molecular and Cellular Medicine, Texas A&M University College of Medicine, College Station, TX, USA.
| | - Dinesh Upadhya
- Centre for Molecular Neurosciences, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India.
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25
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Smith FM, Kosman DJ. Molecular Defects in Friedreich's Ataxia: Convergence of Oxidative Stress and Cytoskeletal Abnormalities. Front Mol Biosci 2020; 7:569293. [PMID: 33263002 PMCID: PMC7686857 DOI: 10.3389/fmolb.2020.569293] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/10/2020] [Indexed: 01/18/2023] Open
Abstract
Friedreich’s ataxia (FRDA) is a multi-faceted disease characterized by progressive sensory–motor loss, neurodegeneration, brain iron accumulation, and eventual death by hypertrophic cardiomyopathy. FRDA follows loss of frataxin (FXN), a mitochondrial chaperone protein required for incorporation of iron into iron–sulfur cluster and heme precursors. After the discovery of the molecular basis of FRDA in 1996, over two decades of research have been dedicated to understanding the temporal manifestations of disease both at the whole body and molecular level. Early research indicated strong cellular iron dysregulation in both human and yeast models followed by onset of oxidative stress. Since then, the pathophysiology due to dysregulation of intracellular iron chaperoning has become central in FRDA relative to antioxidant defense and run-down in energy metabolism. At the same time, limited consideration has been given to changes in cytoskeletal organization, which was one of the first molecular defects noted. These alterations include both post-translational oxidative glutathionylation of actin monomers and differential DNA processing of a cytoskeletal regulator PIP5K1β. Currently unknown in respect to FRDA but well understood in the context of FXN-deficient cell physiology is the resulting impact on the cytoskeleton; this disassembly of actin filaments has a particularly profound effect on cell–cell junctions characteristic of barrier cells. With respect to a neurodegenerative disorder such as FRDA, this cytoskeletal and tight junction breakdown in the brain microvascular endothelial cells of the blood–brain barrier is likely a component of disease etiology. This review serves to outline a brief history of this research and hones in on pathway dysregulation downstream of iron-related pathology in FRDA related to actin dynamics. The review presented here was not written with the intent of being exhaustive, but to instead urge the reader to consider the essentiality of the cytoskeleton and appreciate the limited knowledge on FRDA-related cytoskeletal dysfunction as a result of oxidative stress. The review examines previous hypotheses of neurodegeneration with brain iron accumulation (NBIA) in FRDA with a specific biochemical focus.
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Affiliation(s)
- Frances M Smith
- Department of Biochemistry, State University of New York at Buffalo, Buffalo, NY, United States
| | - Daniel J Kosman
- Department of Biochemistry, State University of New York at Buffalo, Buffalo, NY, United States
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26
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Santoro M, Perna A, La Rosa P, Petrillo S, Piemonte F, Rossi S, Riso V, Nicoletti TF, Modoni A, Pomponi MG, Chiurazzi P, Silvestri G. Compound heterozygosity for an expanded (GAA) and a (GAAGGA) repeat at FXN locus: from a diagnostic pitfall to potential clues to the pathogenesis of Friedreich ataxia. Neurogenetics 2020; 21:279-287. [PMID: 32638185 DOI: 10.1007/s10048-020-00620-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/14/2020] [Indexed: 12/23/2022]
Abstract
Friedreich's ataxia (FRDA) is usually due to a homozygous GAA expansion in intron 1 of the frataxin (FXN) gene. Rarely, uncommon molecular rearrangements at the FXN locus can cause pitfalls in the molecular diagnosis of FRDA. Here we describe a family whose proband was affected by late-onset Friedreich's ataxia (LOFA); long-range PCR (LR-PCR) documented two small expanded GAA alleles both in the proband and in her unaffected younger sister, who therefore received a diagnosis of pre-symptomatic LOFA. Later studies, however, revealed that the proband's unaffected sister, as well as their healthy mother, were both carriers of an expanded GAA allele and an uncommon (GAAGGA)66-67 repeat mimicking a GAA expansion at the LR-PCR that was the cause of the wrong initial diagnosis of pre-symptomatic LOFA. Extensive studies in tissues from all the family members, including LR-PCR, assessment of methylation status of FXN locus, MboII restriction analysis and direct sequencing of LR-PCR products, analysis of FXN mRNA, and frataxin protein expression, support the virtual lack of pathogenicity of the rare (GAAGGA)66-67 repeat, also providing significant data about the modulation of epigenetic modifications at the FXN locus. Overall, this report highlights a rare but possible pitfall in FRDA molecular diagnosis, emphasizing the need of further analysis in case of discrepancy between clinical and molecular data.
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Affiliation(s)
- Massimo Santoro
- IRCCS Fondazione Don Carlo Gnocchi, Piazzale Morandi, 6, 20121, Milan, Italy
| | - Alessia Perna
- Dept of Neuroscience, Faculty of Medicine and Surgery, Università Cattolica del Scaro Cuore, L.go F. Vito 1, 000168, Rome, Italy
| | - Piergiorgio La Rosa
- Unit of Muscular and Neurodegenerative Diseases, Ospedale Pediatrico Bambino Gesù, IRCCS, Viale San Paolo, 15, 00146, Rome, Italy
| | - Sara Petrillo
- Unit of Muscular and Neurodegenerative Diseases, Ospedale Pediatrico Bambino Gesù, IRCCS, Viale San Paolo, 15, 00146, Rome, Italy
| | - Fiorella Piemonte
- Unit of Muscular and Neurodegenerative Diseases, Ospedale Pediatrico Bambino Gesù, IRCCS, Viale San Paolo, 15, 00146, Rome, Italy
| | - Salvatore Rossi
- Dept of Neuroscience, Faculty of Medicine and Surgery, Università Cattolica del Scaro Cuore, L.go F. Vito 1, 000168, Rome, Italy
| | - Vittorio Riso
- Dept of Neuroscience, Faculty of Medicine and Surgery, Università Cattolica del Scaro Cuore, L.go F. Vito 1, 000168, Rome, Italy
- Institute of Neurology, Neuroscience Area, Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy
| | - Tommaso Filippo Nicoletti
- Dept of Neuroscience, Faculty of Medicine and Surgery, Università Cattolica del Scaro Cuore, L.go F. Vito 1, 000168, Rome, Italy
- Institute of Neurology, Neuroscience Area, Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy
| | - Anna Modoni
- Institute of Neurology, Neuroscience Area, Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy
| | - Maria Grazia Pomponi
- Institute of Genomic Medicine, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy
| | - Pietro Chiurazzi
- Institute of Genomic Medicine, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy
| | - Gabriella Silvestri
- Dept of Neuroscience, Faculty of Medicine and Surgery, Università Cattolica del Scaro Cuore, L.go F. Vito 1, 000168, Rome, Italy.
- Institute of Neurology, Neuroscience Area, Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli, 8, 00168, Rome, Italy.
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27
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Fazal S, Danzi MC, Cintra VP, Bis-Brewer DM, Dolzhenko E, Eberle MA, Zuchner S. Large scale in silico characterization of repeat expansion variation in human genomes. Sci Data 2020; 7:294. [PMID: 32901039 PMCID: PMC7479135 DOI: 10.1038/s41597-020-00633-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 08/13/2020] [Indexed: 11/21/2022] Open
Abstract
Significant progress has been made in elucidating single nucleotide polymorphism diversity in the human population. However, the majority of the variation space in the genome is structural and remains partially elusive. One form of structural variation is tandem repeats (TRs). Expansion of TRs are responsible for over 40 diseases, but we hypothesize these represent only a fraction of the pathogenic repeat expansions that exist. Here we characterize long or expanded TR variation in 1,115 human genomes as well as a replication cohort of 2,504 genomes, identified using ExpansionHunter Denovo. We found that individual genomes typically harbor several rare, large TRs, generally in non-coding regions of the genome. We noticed that these large TRs are enriched in their proximity to Alu elements. The vast majority of these large TRs seem to be expansions of smaller TRs that are already present in the reference genome. We are providing this TR profile as a resource for comparison to undiagnosed rare disease genomes in order to detect novel disease-causing repeat expansions.
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Affiliation(s)
- Sarah Fazal
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Matt C Danzi
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Vivian P Cintra
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Dana M Bis-Brewer
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | | | | | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA.
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28
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Bizzoca A, Caracciolo M, Corsi P, Magrone T, Jirillo E, Gennarini G. Molecular and Cellular Substrates for the Friedreich Ataxia. Significance of Contactin Expression and of Antioxidant Administration. Molecules 2020; 25:E4085. [PMID: 32906751 PMCID: PMC7570916 DOI: 10.3390/molecules25184085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 08/28/2020] [Accepted: 09/02/2020] [Indexed: 11/16/2022] Open
Abstract
In this study, the neural phenotype is explored in rodent models of the spinocerebellar disorder known as the Friedreich Ataxia (FA), which results from mutations within the gene encoding the Frataxin mitochondrial protein. For this, the M12 line, bearing a targeted mutation, which disrupts the Frataxin gene exon 4 was used, together with the M02 line, which, in addition, is hemizygous for the human Frataxin gene mutation (Pook transgene), implying the occurrence of 82-190 GAA repeats within its first intron. The mutant mice phenotype was compared to the one of wild type littermates in regions undergoing differential profiles of neurogenesis, including the cerebellar cortex and the spinal cord by using neuronal (β-tubulin) and glial (Glial Fibrillary Acidic Protein) markers as well as the Contactin 1 axonal glycoprotein, involved in neurite growth control. Morphological/morphometric analyses revealed that while in Frataxin mutant mice the neuronal phenotype was significantly counteracted, a glial upregulation occurred at the same time. Furthermore, Contactin 1 downregulation suggested that changes in the underlying gene contributed to the disorder pathogenesis. Therefore, the FA phenotype implies an alteration of the developmental profile of neuronal and glial precursors. Finally, epigallocatechin gallate polyphenol administration counteracted the disorder, indicating protective effects of antioxidant administration.
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Affiliation(s)
| | | | | | | | | | - Gianfranco Gennarini
- Department of Basic Medical Sciences, Neurosciences and Sensory Organs, Medical School, University of Bari, Piazza Giulio Cesare, 11. I-70124 Bari, Italy; (A.B.); (M.C.); (P.C.); (T.M.); (E.J.)
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29
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Indelicato E, Nachbauer W, Eigentler A, Amprosi M, Matteucci Gothe R, Giunti P, Mariotti C, Arpa J, Durr A, Klopstock T, Schöls L, Giordano I, Bürk K, Pandolfo M, Didszdun C, Schulz JB, Boesch S. Onset features and time to diagnosis in Friedreich's Ataxia. Orphanet J Rare Dis 2020; 15:198. [PMID: 32746884 PMCID: PMC7397644 DOI: 10.1186/s13023-020-01475-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 07/21/2020] [Indexed: 12/21/2022] Open
Abstract
Background In rare disorders diagnosis may be delayed due to limited awareness and unspecific presenting symptoms. Herein, we address the issue of diagnostic delay in Friedreich’s Ataxia (FRDA), a genetic disorder usually caused by homozygous GAA-repeat expansions. Methods Six hundred eleven genetically confirmed FRDA patients were recruited within a multicentric natural history study conducted by the EFACTS (European FRDA Consortium for Translational Studies, ClinicalTrials.gov-Identifier NCT02069509). Age at first symptoms as well as age at first suspicion of FRDA by a physician were collected retrospectively at the baseline visit. Results In 554 of cases (90.7%), disease presented with gait or coordination disturbances. In the others (n = 57, 9.3%), non-neurological features such as scoliosis or cardiomyopathy predated ataxia. Before the discovery of the causal mutation in 1996, median time to diagnosis was 4(IQR = 2–9) years and it improved significantly after the introduction of genetic testing (2(IQR = 1–5) years, p < 0.001). Still, after 1996, time to diagnosis was longer in patients with a) non-neurological presentation (mean 6.7, 95%CI [5.5,7.9] vs 4.5, [4.2,5] years in those with neurological presentation, p = 0.001) as well as in b) patients with late-onset (3(IQR = 1–7) vs 2(IQR = 1–5) years compared to typical onset < 25 years of age, p = 0.03). Age at onset significantly correlated with the length of the shorter GAA repeat (GAA1) in case of neurological onset (r = − 0,6; p < 0,0001), but not in patients with non-neurological presentation (r = − 0,1; p = 0,4). Across 54 siblings’ pairs, differences in age at onset did not correlate with differences in GAA-repeat length (r = − 0,14, p = 0,3). Conclusions In the genetic era, presentation with non-neurological features or in the adulthood still leads to a significant diagnostic delay in FRDA. Well-known correlations between GAA1 repeat length and disease milestones are not valid in case of atypical presentations or positive family history.
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Affiliation(s)
- Elisabetta Indelicato
- Department of Neurology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Wolfgang Nachbauer
- Department of Neurology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Andreas Eigentler
- Department of Neurology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Matthias Amprosi
- Department of Neurology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Raffaella Matteucci Gothe
- Department of Public Health, Health Services Research and Health Technology Assessment, UMIT - University of Health Sciences, Medical Informatics and Technology, Hall in Tirol, Austria
| | - Paola Giunti
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Caterina Mariotti
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Javier Arpa
- Reference Unit of Hereditary Ataxias and Paraplegias, Department of Neurology, IdiPAZ, Hospital Universitario La Paz, Madrid, Spain
| | - Alexandra Durr
- Sorbonne Université, Institut du Cerveau et de la Moelle épinière (ICM), AP-HP, Inserm U 1127, CNRS UMR 7225, University Hospital Pitié-Salpêtrière, Paris, France
| | - Thomas Klopstock
- Department of Neurology with Friedrich-Baur-Institute, University of Munich, Munich, Germany.,German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Ludger Schöls
- Department of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Ilaria Giordano
- Department of Neurology, University Hospital of Bonn, Bonn, Germany.,German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Katrin Bürk
- Department of Neurology, Philipps University of Marburg, Marburg, Germany
| | - Massimo Pandolfo
- Laboratory of Experimental Neurology, Université Libre de Bruxelles, Brussels, Belgium
| | - Claire Didszdun
- Department of Neurology, RWTH Aachen University, Aachen, Germany.,JARA-BRAIN Institute of Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Jörg B Schulz
- Department of Neurology, RWTH Aachen University, Aachen, Germany.,JARA-BRAIN Institute of Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
| | - Sylvia Boesch
- Department of Neurology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
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Fautsch MP, Wieben ED, Baratz KH, Bhattacharyya N, Sadan AN, Hafford-Tear NJ, Tuft SJ, Davidson AE. TCF4-mediated Fuchs endothelial corneal dystrophy: Insights into a common trinucleotide repeat-associated disease. Prog Retin Eye Res 2020; 81:100883. [PMID: 32735996 PMCID: PMC7988464 DOI: 10.1016/j.preteyeres.2020.100883] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/24/2020] [Accepted: 07/04/2020] [Indexed: 12/13/2022]
Abstract
Fuchs endothelial corneal dystrophy (FECD) is a common cause for heritable visual loss in the elderly. Since the first description of an association between FECD and common polymorphisms situated within the transcription factor 4 (TCF4) gene, genetic and molecular studies have implicated an intronic CTG trinucleotide repeat (CTG18.1) expansion as a causal variant in the majority of FECD patients. To date, several non-mutually exclusive mechanisms have been proposed that drive and/or exacerbate the onset of disease. These mechanisms include (i) TCF4 dysregulation; (ii) toxic gain-of-function from TCF4 repeat-containing RNA; (iii) toxic gain-of-function from repeat-associated non-AUG dependent (RAN) translation; and (iv) somatic instability of CTG18.1. However, the relative contribution of these proposed mechanisms in disease pathogenesis is currently unknown. In this review, we summarise research implicating the repeat expansion in disease pathogenesis, define the phenotype-genotype correlations between FECD and CTG18.1 expansion, and provide an update on research tools that are available to study FECD as a trinucleotide repeat expansion disease. Furthermore, ongoing international research efforts to develop novel CTG18.1 expansion-mediated FECD therapeutics are highlighted and we provide a forward-thinking perspective on key unanswered questions that remain in the field. FECD is a common, age-related corneal dystrophy. The majority of cases are associated with expansion of a CTG repeat (CTG18.1). FECD is the most common trinucleotide repeat expansion disease in humans. Evidence supports multiple molecular mechanisms underlying the pathophysiology. Novel CTG18.1-targeted therapeutics are in development.
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Affiliation(s)
- Michael P Fautsch
- Department of Ophthalmology, 200 1st St SW, Mayo Clinic, Rochester, MN, 55905, USA.
| | - Eric D Wieben
- Department of Biochemistry and Molecular Biology, 200 1st St SW, Mayo Clinic, Rochester, MN, USA.
| | - Keith H Baratz
- Department of Ophthalmology, 200 1st St SW, Mayo Clinic, Rochester, MN, 55905, USA.
| | | | - Amanda N Sadan
- University College London Institute of Ophthalmology, London, ECIV 9EL, UK.
| | | | - Stephen J Tuft
- University College London Institute of Ophthalmology, London, ECIV 9EL, UK; Moorfields Eye Hospital, London, EC1V 2PD, UK.
| | - Alice E Davidson
- University College London Institute of Ophthalmology, London, ECIV 9EL, UK.
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Fil D, Chacko BK, Conley R, Ouyang X, Zhang J, Darley-Usmar VM, Zuberi AR, Lutz CM, Napierala M, Napierala JS. Mitochondrial damage and senescence phenotype of cells derived from a novel frataxin G127V point mutation mouse model of Friedreich's ataxia. Dis Model Mech 2020; 13:dmm045229. [PMID: 32586831 PMCID: PMC7406325 DOI: 10.1242/dmm.045229] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/16/2020] [Indexed: 12/11/2022] Open
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused by reduced expression of the mitochondrial protein frataxin (FXN). Most FRDA patients are homozygous for large expansions of GAA repeat sequences in intron 1 of FXN, whereas a fraction of patients are compound heterozygotes, with a missense or nonsense mutation in one FXN allele and expanded GAAs in the other. A prevalent missense mutation among FRDA patients changes a glycine at position 130 to valine (G130V). Herein, we report generation of the first mouse model harboring an Fxn point mutation. Changing the evolutionarily conserved glycine 127 in mouse Fxn to valine results in a failure-to-thrive phenotype in homozygous animals and a substantially reduced number of offspring. Like G130V in FRDA, the G127V mutation results in a dramatic decrease of Fxn protein without affecting transcript synthesis or splicing. FxnG127V mouse embryonic fibroblasts exhibit significantly reduced proliferation and increased cell senescence. These defects are evident in early passage cells and are exacerbated at later passages. Furthermore, increased frequency of mitochondrial DNA lesions and fragmentation are accompanied by marked amplification of mitochondrial DNA in FxnG127V cells. Bioenergetics analyses demonstrate higher sensitivity and reduced cellular respiration of FxnG127V cells upon alteration of fatty acid availability. Importantly, substitution of FxnWT with FxnG127V is compatible with life, and cellular proliferation defects can be rescued by mitigation of oxidative stress via hypoxia or induction of the NRF2 pathway. We propose FxnG127V cells as a simple and robust model for testing therapeutic approaches for FRDA.
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Affiliation(s)
- Daniel Fil
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
| | - Balu K Chacko
- Department of Pathology, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA
- Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Robbie Conley
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
| | - Xiaosen Ouyang
- Department of Pathology, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA
- Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Department of Veteran Affairs Medical Center, Birmingham, AL 35294, USA
| | - Jianhua Zhang
- Department of Pathology, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA
- Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Department of Veteran Affairs Medical Center, Birmingham, AL 35294, USA
| | - Victor M Darley-Usmar
- Department of Pathology, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA
- Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Aamir R Zuberi
- The Rare and Orphan Disease Center, JAX Center for Precision Genetics, 600 Main Street, Bar Harbor, ME 04609, USA
| | - Cathleen M Lutz
- The Rare and Orphan Disease Center, JAX Center for Precision Genetics, 600 Main Street, Bar Harbor, ME 04609, USA
| | - Marek Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
| | - Jill S Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
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Proukakis C. Somatic mutations in neurodegeneration: An update. Neurobiol Dis 2020; 144:105021. [PMID: 32712267 DOI: 10.1016/j.nbd.2020.105021] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 06/12/2020] [Accepted: 07/13/2020] [Indexed: 12/20/2022] Open
Abstract
Mosaicism, the presence of genomic differences between cells due to post-zygotic somatic mutations, is widespread in the human body, including within the brain. A role for this in neurodegenerative diseases has long been hypothesised, and technical developments are now allowing the question to be addressed in detail. The rapidly accumulating evidence is discussed in this review, with a focus on recent developments. Somatic mutations of numerous types may occur, including single nucleotide variants (SNVs), copy number variants (CNVs), and retrotransposon insertions. They could act as initiators or risk factors, especially if they arise in development, although they could also result from the disease process, potentially contributing to progression. In common sporadic neurodegenerative disorders, relevant mutations have been reported in synucleinopathies, comprising somatic gains of SNCA in Parkinson's disease and multiple system atrophy, and in Alzheimer's disease, where a novel recombination mechanism leading to somatic variants of APP, as well as an excess of somatic SNVs affecting tau phosphorylation, have been reported. In Mendelian repeat expansion disorders, mosaicism due to somatic instability, first detected 25 years ago, has come to the forefront. Brain somatic SNVs occur in DNA repair disorders, and there is evidence for a role of several ALS genes in DNA repair. While numerous challenges, and need for further validation, remain, this new, or perhaps rediscovered, area of research has the potential to transform our understanding of neurodegeneration.
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Affiliation(s)
- Christos Proukakis
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, London, UK.
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Flower M, Lomeikaite V, Holmans P, Jones L, Tabrizi SJ, Monckton DG. Reply: The repeat variant in MSH3 is not a genetic modifier for spinocerebellar ataxia type 3 and Friedreich's ataxia. Brain 2020; 143:e26. [PMID: 32154840 DOI: 10.1093/brain/awaa044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Michael Flower
- Department of Neurodegenerative Disease and Dementia Research Institute, UCL, UK
| | - Vilija Lomeikaite
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
| | - Peter Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, UK
| | - Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, UK
| | - Sarah J Tabrizi
- Department of Neurodegenerative Disease and Dementia Research Institute, UCL, UK
| | - Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
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Legrand L, Diallo A, Monin ML, Ewenczyk C, Charles P, Isnard R, Vicaut E, Montalescot G, Durr A, Pousset F. Predictors of Left Ventricular Dysfunction in Friedreich's Ataxia in a 16-Year Observational Study. Am J Cardiovasc Drugs 2020; 20:209-216. [PMID: 31650522 DOI: 10.1007/s40256-019-00375-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Friedreich's ataxia (FRDA) is a cerebellar ataxia due to GAA repeat expansions in the FXN gene, and in affected patients, lower left ventricular ejection fraction (LVEF) leads to poorer prognosis. We aimed to identify patients likely to develop worsening LVEF at an early stage. METHODS We included 115 FRDA patients aged 30 ± 10 years with 620 ± 238 GAA repeats on the shorter allele and disease onset of 15 ± 7 years. RESULTS At baseline, left ventricular (LV) hypertrophy was present in 53%, with LVEF 65 ± 7%, LV end diastolic diameter (LVEDD) 43 ± 5 mm, septal wall thickness (SWT) 11.8 ± 2.7 mm, and posterior wall thickness 11.1 ± 2.5 mm. After a mean follow-up of 13 ± 6 years, LVEF ≤ 50% was observed in 12 patients. The main determinants of LVEF ≤ 50% were GAA repeat number on the shorter allele (odds ratio [OR] 1.007, 95% confidence interval [CI] 1.003-1.012, p = 0.002), LVEDD (OR 1.217, 95% CI 1.058-1.399, p = 0.006), and SWT (OR 1.352, 95% CI 1.016-1.799, p = 0.04). High-risk patients were predicted 5 years before LVEF ≤ 50% occurred: area under the curve of 0.91, 95% CI 0.85-0.97. Patients with GAA repeats > 800 were categorized as high risk, patients with 500 < GAA < 800 were high risk if LVEDD was ≥ 52.6 mm and SWT was ≥ 13.3 mm, and patients with GAA < 500 were low risk if LVEDD was < 52.6 mm and SWT was < 13.3 mm. CONCLUSIONS Echocardiographic follow-up combined with size assessment of GAA repeat expansions is a powerful tool to identify patients at high risk of developing LV systolic dysfunction up to 5 years before clinical symptoms. Further studies are mandatory to investigate if these patients would benefit from cardiac interventions.
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Affiliation(s)
- Lise Legrand
- Cardiology Department, AP-HP, Pitié-Salpêtrière University Hospital, Sorbonne Université, Paris, France
- ICAN (Institute for Cardiometabolism and Nutrition), Pitié-Salpêtrière University Hospital, Paris, France
| | - Abdourahmane Diallo
- ACTION (Allies in Cardiovascular Trials Initiatives and Organized Networks) Group, URC Lariboisière University Hospital, Paris, France
| | - Marie-Lorraine Monin
- Cardiology Department, AP-HP, Pitié-Salpêtrière University Hospital, Sorbonne Université, Paris, France
- Genetics Department, AP-HP, Pitié-Salpêtrière University Hospital, Sorbonne Université, Paris, France
| | - Claire Ewenczyk
- Genetics Department, AP-HP, Pitié-Salpêtrière University Hospital, Sorbonne Université, Paris, France
| | - Perrine Charles
- Genetics Department, AP-HP, Pitié-Salpêtrière University Hospital, Sorbonne Université, Paris, France
| | - Richard Isnard
- Cardiology Department, AP-HP, Pitié-Salpêtrière University Hospital, Sorbonne Université, Paris, France
- ICAN (Institute for Cardiometabolism and Nutrition), Pitié-Salpêtrière University Hospital, Paris, France
- ACTION (Allies in Cardiovascular Trials Initiatives and Organized Networks) Group, URC Lariboisière University Hospital, Paris, France
| | - Eric Vicaut
- ACTION (Allies in Cardiovascular Trials Initiatives and Organized Networks) Group, URC Lariboisière University Hospital, Paris, France
| | - Gilles Montalescot
- Cardiology Department, AP-HP, Pitié-Salpêtrière University Hospital, Sorbonne Université, Paris, France
- ACTION (Allies in Cardiovascular Trials Initiatives and Organized Networks) Group, URC Lariboisière University Hospital, Paris, France
| | - Alexandra Durr
- Genetics Department, AP-HP, Pitié-Salpêtrière University Hospital, Sorbonne Université, Paris, France
- ICM (Brain and Spine Institute), INSERM, CNRS, Pitié-Salpêtrière University Hospital, Sorbonne Université, Paris, France
| | - Francoise Pousset
- Cardiology Department, AP-HP, Pitié-Salpêtrière University Hospital, Sorbonne Université, Paris, France.
- ICAN (Institute for Cardiometabolism and Nutrition), Pitié-Salpêtrière University Hospital, Paris, France.
- Département de Cardiologie, Hôpital de la Salpêtrière, 47 boulevard de l'Hôpital, 75651, Paris Cedex 13, France.
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Arcuria G, Marcotulli C, Amuso R, Dattilo G, Galasso C, Pierelli F, Casali C. Developing an objective evaluating system to quantify the degree of upper limb movement impairment in patients with severe Friedreich's ataxia. Neurol Sci 2020; 41:1577-1587. [PMID: 31993871 DOI: 10.1007/s10072-020-04249-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 01/09/2020] [Indexed: 12/26/2022]
Abstract
BACKGROUND The use of standardized tools and objective measurements is essential to test the effectiveness of new drugs or rehabilitative protocols. Friedreich's ataxia (FRDA) patients with severe disease are often unable to perform the quantitative measurement tests currently used. AIM The purpose of our study was to develop an easy-to-use application, for touchscreen devices, able to quantify the degree of upper limb movement impairment in patients with severe Friedreich's ataxia. The APP, which we named "Twelve-Red-Squares App-Coo-Test" (12-RSACT), assesses the upper limb ataxia by measuring the test execution time. METHODS All patients were clinically evaluated using the Composite Cerebellar Functional Severity (CCFS) and the Scale for the Assessment and Rating of Ataxia (SARA). We recruited 92 healthy subjects and 36 FRDA patients with a SARA mean value of 28.8.1 ± 8.2. All participants in our study underwent upper limb movement assessment using the new 12-RSACT, the Click Test, and a well-established system, i.e., the Nine-Hole Peg Test (9HPT). RESULTS We observed a strong linear correlation between the measurements obtained with the 12-RSACT and those obtained with 9HPT, Click Test, CCFS, and SARA. The 12-RSACT was characterized by excellent internal consistency and intra-rater and test-retest reliability. The minimal detectable change (MDC%) was excellent too. Additionally, the 12-RSACT turned out to be faster and easier to perform compared with the 9HPT. CONCLUSION The 12-RSACT is an inexpensive test and is easy to use, which can be administered quickly. Therefore, 12-RSACT is a promising tool to assess the upper limb ataxia in FRDA patients and even those with severe diseases.
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Affiliation(s)
- Giuseppe Arcuria
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza - University of Rome - Polo Pontino, Via Faggiana 34, 40100, Latina, Italy.
| | - Christian Marcotulli
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza - University of Rome - Polo Pontino, Via Faggiana 34, 40100, Latina, Italy
| | - Raffaele Amuso
- Department of Science and Information Technology, I.I.S. Ettore Majorana, Piazza Sen. Marescalchi 2, Piazza Armerina, EN, Italy
| | - Giuliano Dattilo
- Department of Mathematical, Physical and Natural Sciences, University of Rome "Sapienza", Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Claudio Galasso
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza - University of Rome - Polo Pontino, Via Faggiana 34, 40100, Latina, Italy
| | | | - Carlo Casali
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza - University of Rome - Polo Pontino, Via Faggiana 34, 40100, Latina, Italy
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Bilgel M, Jedynak BM. Predicting time to dementia using a quantitative template of disease progression. ALZHEIMER'S & DEMENTIA (AMSTERDAM, NETHERLANDS) 2019; 11:205-215. [PMID: 30859120 PMCID: PMC6396328 DOI: 10.1016/j.dadm.2019.01.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Characterization of longitudinal trajectories of biomarkers implicated in sporadic Alzheimer's disease (AD) in decades before clinical diagnosis is important for disease prevention and monitoring. METHODS We used a multivariate Bayesian model to temporally align 1369 Alzheimer's disease Neuroimaging Initiative participants based on the similarity of their longitudinal biomarker measures and estimated a quantitative template of the temporal evolution of cerebrospinal fluid Aβ 1 - 42 , p- ta u 181 p , and t-tau and hippocampal volume, brain glucose metabolism, and cognitive measurements. We computed biomarker trajectories as a function of time to AD dementia and predicted AD dementia onset age in a disjoint sample. RESULTS Quantitative template showed early changes in verbal memory, cerebrospinal fluid Aβ1-42 and p-tau181p, and hippocampal volume. Mean error in predicted AD dementia onset age was < 1.5 years. DISCUSSION Our method provides a quantitative approach for characterizing the natural history of AD starting at preclinical stages despite the lack of individual-level longitudinal data spanning the entire disease timeline.
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Affiliation(s)
- Murat Bilgel
- Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Bruno M. Jedynak
- Dept. of Mathematics and Statistics, Portland State University, Portland, OR, USA
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Li J, Rozwadowska N, Clark A, Fil D, Napierala JS, Napierala M. Excision of the expanded GAA repeats corrects cardiomyopathy phenotypes of iPSC-derived Friedreich's ataxia cardiomyocytes. Stem Cell Res 2019; 40:101529. [PMID: 31446150 PMCID: PMC6853280 DOI: 10.1016/j.scr.2019.101529] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 08/02/2019] [Accepted: 08/05/2019] [Indexed: 02/06/2023] Open
Abstract
Friedreich's ataxia is caused by large homozygous, intronic expansions of GAA repeats in the frataxin (FXN) gene, resulting in severe downregulation of its expression. Pathogenic repeats are located in intron one, hence patients express unaffected FXN protein, albeit in low quantities. Although FRDA symptoms typically afflict the nervous system, hypertrophic cardiomyopathy is the predominant cause of death. Our studies were conducted using cardiomyocytes differentiated from induced pluripotent stem cells derived from control individuals, FRDA patients, and isogenic cells corrected by zinc finger nucleases-mediated excision of pathogenic expanded GAA repeats. This correction of the FXN gene removed the primary trigger of the transcription defect, upregulated frataxin expression, reduced pathological lipid accumulation observed in patient cardiomyocytes, and reversed gene expression signatures of FRDA cardiomyocytes. Transcriptome analyses revealed hypertrophy-specific expression signatures unique to FRDA cardiomyocytes, and emphasized similarities between unaffected and ZFN-corrected FRDA cardiomyocytes. Thus, the iPSC-derived FRDA cardiomyocytes exhibit various molecular defects characteristic for cellular models of cardiomyopathy that can be corrected by genome editing of the expanded GAA repeats. These results underscore the utility of genome editing in generating isogenic cellular models of FRDA and the potential of this approach as a future therapy for this disease.
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Affiliation(s)
- Jixue Li
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Natalia Rozwadowska
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Amanda Clark
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Daniel Fil
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA
| | - Jill S Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA.
| | - Marek Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL 35294, USA.
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Albright J. Forecasting the progression of Alzheimer's disease using neural networks and a novel preprocessing algorithm. ALZHEIMER'S & DEMENTIA (NEW YORK, N. Y.) 2019; 5:483-491. [PMID: 31650004 PMCID: PMC6804703 DOI: 10.1016/j.trci.2019.07.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
INTRODUCTION There is a 99.6% failure rate of clinical trials for drugs to treat Alzheimer's disease, likely because Alzheimer's disease (AD) patients cannot be easily identified at early stages. This study investigated machine learning approaches to use clinical data to predict the progression of AD in future years. METHODS Data from 1737 patients were processed using the "All-Pairs" technique, a novel methodology created for this study involving the comparison of all possible pairs of temporal data points for each patient. Machine learning models were trained on these processed data and evaluated using a separate testing data set (110 patients). RESULTS A neural network model was effective (mAUC = 0.866) at predicting the progression of AD, both in patients who were initially cognitively normal and in patients suffering from mild cognitive impairment. DISCUSSION Such a model could be used to identify patients at early stages of AD and who are therefore good candidates for clinical trials for AD therapeutics.
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Affiliation(s)
- Jack Albright
- Corresponding author. Tel.: (650) 434-3518; Fax: (650) 471-6048.
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Delatycki MB, Bidichandani SI. Friedreich ataxia- pathogenesis and implications for therapies. Neurobiol Dis 2019; 132:104606. [PMID: 31494282 DOI: 10.1016/j.nbd.2019.104606] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/08/2019] [Accepted: 09/04/2019] [Indexed: 01/01/2023] Open
Abstract
Friedreich ataxia is the most common of the hereditary ataxias. It is due to homozygous/compound heterozygous mutations in FXN. This gene encodes frataxin, a protein largely localized to mitochondria. In about 96% of affected individuals there is homozygosity for a GAA repeat expansion in intron 1 of the FXN gene. Studies of people with Friedreich ataxia and of animal and cell models, have provided much insight into the pathogenesis of this disorder. The expanded GAA repeat leads to transcriptional deficiency of the FXN gene. The consequent deficiency of frataxin protein leads to reduced iron-sulfur cluster biogenesis and mitochondrial ATP production, elevated mitochondrial iron, and oxidative stress. More recently, a role for inflammation has emerged as being important in the pathogenesis of Friedreich ataxia. These findings have led to a number of potential therapies that have been subjected to clinical trials or are being developed toward human studies. Therapies that have been proposed include pharmaceuticals that increase frataxin levels, protein and gene replacement therapies, antioxidants, iron chelators and modulators of inflammation. Whilst no therapies have yet been approved for Friedreich ataxia, there is much optimism that the advances in the understanding of the pathogenesis of this disorder since the discovery its genetic basis, will result in approved disease modifying therapies in the near future.
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Affiliation(s)
- Martin B Delatycki
- Bruce Lefroy Centre, Murdoch Children's Research Institute, Parkville, Victoria, Australia; Victorian Clinical Genetics Services, Parkville, Victoria, Australia; Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia.
| | - Sanjay I Bidichandani
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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Creigh PD, Mountain J, Sowden JE, Eichinger K, Ravina B, Larkindale J, Herrmann DN. Measuring peripheral nerve involvement in Friedreich's ataxia. Ann Clin Transl Neurol 2019; 6:1718-1727. [PMID: 31414727 PMCID: PMC6764626 DOI: 10.1002/acn3.50865] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 07/22/2019] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVE Experimental therapies under development for Friedreich's Ataxia (FRDA) require validated biomarkers. In-vivo reflectance confocal microscopy (RCM) of skin is a noninvasive way to quantify Meissner's corpuscle (MC) density and has emerged as a sensitive measure of sensory polyneuropathies. We conducted a prospective, cross-sectional study evaluating RCM of MCs and conventional peripheral nerve measures as candidate peripheral nerve markers in FRDA. METHODS Sixteen individuals with FRDA and 16 age- and gender-matched controls underwent RCM of MC density and morphology, skin biopsies for epidermal nerve fiber density (ENFD), nerve conduction studies (NCS), and quantitative sensory testing (QST) including touch, vibration, and cooling thresholds. RESULTS MC densities were measurable in all participants with FRDA, and were lower at digit V (hand), thenar eminence, and arch (foot) compared to controls. By contrast, sensory NCS showed floor effects and were obtainable in only 13% of FRDA participants. QST thresholds for touch, vibration, and cooling were higher at the hand and foot in FRDA than controls. Reductions in ENFDs were present in more severely affected individuals with FRDA (Friedreich's Ataxia Rating Scale (FARS) >60) compared to matched controls, although skin biopsies were not well tolerated in children. MC densities, ENFDs, and touch and vibration thresholds were associated with clinical disease severity (FARS and modified FARS) and duration since symptom onset. INTERPRETATION MC density, ENFD, and QST thresholds provide structural and physiologic markers of sensory involvement in FRDA. Longitudinal evaluation is needed to determine whether these measures can identify changes associated with disease progression or treatment.
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Affiliation(s)
- Peter D. Creigh
- Department of NeurologyUniversity of Rochester School of Medicine and DentistryRochesterNew York
| | - Joan Mountain
- Department of NeurologyUniversity of Rochester School of Medicine and DentistryRochesterNew York
| | - Janet E. Sowden
- Department of NeurologyUniversity of Rochester School of Medicine and DentistryRochesterNew York
| | - Katy Eichinger
- Department of NeurologyUniversity of Rochester School of Medicine and DentistryRochesterNew York
| | - Bernard Ravina
- Department of NeurologyUniversity of Rochester School of Medicine and DentistryRochesterNew York
- Praxis Precision MedicinesCambridgeMassachusetts
| | - Jane Larkindale
- Friedreich’s Ataxia Research AllianceDowningtownPennsylvania
| | - David N. Herrmann
- Department of NeurologyUniversity of Rochester School of Medicine and DentistryRochesterNew York
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Quesada MP, García-Bernal D, Pastor D, Estirado A, Blanquer M, García-Hernández AM, Moraleda JM, Martínez S. Safety and Biodistribution of Human Bone Marrow-Derived Mesenchymal Stromal Cells Injected Intrathecally in Non-Obese Diabetic Severe Combined Immunodeficiency Mice: Preclinical Study. Tissue Eng Regen Med 2019; 16:525-538. [PMID: 31624707 DOI: 10.1007/s13770-019-00202-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 12/13/2022] Open
Abstract
Background Mesenchymal stromal cells (MSCs) have potent immunomodulatory and neuroprotective properties, and have been tested in neurodegenerative diseases resulting in meaningful clinical improvements. Regulatory guidelines specify the need to perform preclinical studies prior any clinical trial, including biodistribution assays and tumourigenesis exclusion. We conducted a preclinical study of human bone marrow MSCs (hBM-MSCs) injected by intrathecal route in Non-Obese Diabetic Severe Combined Immunodeficiency mice, to explore cellular biodistribution and toxicity as a privileged administration method for cell therapy in Friedreich's Ataxia. Methods For this purpose, 3 × 105 cells were injected by intrathecal route in 12 animals (experimental group) and the same volume of culture media in 6 animals (control group). Blood samples were collected at 24 h (n = 9) or 4 months (n = 9) to assess toxicity, and nine organs were harvested for histology and safety studies. Genomic DNA was isolated from all tissues, and mouse GAPDH and human β2M and β-actin genes were amplified by qPCR to analyze hBM-MSCs biodistribution. Results There were no deaths nor acute or chronic toxicity. Hematology, biochemistry and body weight were in the range of normal values in all groups. At 24 h hBM-MSCs were detected in 4/6 spinal cords and 1/6 hearts, and at 4 months in 3/6 hearts and 1/6 brains of transplanted mice. No tumours were found. Conclusion This study demonstrated that intrathecal injection of hBM-MSCs is safe, non toxic and do not produce tumors. These results provide further evidence that hBM-MSCs might be used in a clinical trial in patients with FRDA.
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Affiliation(s)
- Mari Paz Quesada
- 1Cellular Therapy and Hematopoietic Transplant Unit, Hematology Department, Virgen de la Arrixaca Clinical University Hospital, Biomedical Research Institute of Murcia, IMIB-Arrixaca, Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Carretera Acceso Urbanización Buenavista (1ªizda), 30120 El Palmar, Murcia, Spain
| | - David García-Bernal
- 1Cellular Therapy and Hematopoietic Transplant Unit, Hematology Department, Virgen de la Arrixaca Clinical University Hospital, Biomedical Research Institute of Murcia, IMIB-Arrixaca, Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Carretera Acceso Urbanización Buenavista (1ªizda), 30120 El Palmar, Murcia, Spain.,2Internal Medicine Department, Medicine School, University of Murcia, Virgen de la Arrixaca Clinical University Hospital, Ctra. Madrid-Cartagena, s/n, 30120 El Palmar, Murcia, Spain
| | - Diego Pastor
- 3Sport Research Center, University Miguel Hernández of Elche, Av. de la Universidad s/n, 03202 Elche, Alicante, Spain
| | - Alicia Estirado
- 4Neuroscience Institute UMH-CSIC, University Miguel Hernández of Elche, Carretera de Valencia, Km 18, 03550 San Juan, Alicante, Spain
| | - Miguel Blanquer
- 1Cellular Therapy and Hematopoietic Transplant Unit, Hematology Department, Virgen de la Arrixaca Clinical University Hospital, Biomedical Research Institute of Murcia, IMIB-Arrixaca, Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Carretera Acceso Urbanización Buenavista (1ªizda), 30120 El Palmar, Murcia, Spain.,2Internal Medicine Department, Medicine School, University of Murcia, Virgen de la Arrixaca Clinical University Hospital, Ctra. Madrid-Cartagena, s/n, 30120 El Palmar, Murcia, Spain
| | - Ana Mª García-Hernández
- 1Cellular Therapy and Hematopoietic Transplant Unit, Hematology Department, Virgen de la Arrixaca Clinical University Hospital, Biomedical Research Institute of Murcia, IMIB-Arrixaca, Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Carretera Acceso Urbanización Buenavista (1ªizda), 30120 El Palmar, Murcia, Spain
| | - José M Moraleda
- 1Cellular Therapy and Hematopoietic Transplant Unit, Hematology Department, Virgen de la Arrixaca Clinical University Hospital, Biomedical Research Institute of Murcia, IMIB-Arrixaca, Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Carretera Acceso Urbanización Buenavista (1ªizda), 30120 El Palmar, Murcia, Spain.,2Internal Medicine Department, Medicine School, University of Murcia, Virgen de la Arrixaca Clinical University Hospital, Ctra. Madrid-Cartagena, s/n, 30120 El Palmar, Murcia, Spain
| | - Salvador Martínez
- 4Neuroscience Institute UMH-CSIC, University Miguel Hernández of Elche, Carretera de Valencia, Km 18, 03550 San Juan, Alicante, Spain.,CIBERSAM-ISCIII, Avenida Blasco Ibáñez 15, 46010 Valencia, Spain.,6Human Anatomy Department, Medicine School, University Miguel Hernández of Elche, Carretera de Valencia, Km 18, 03550 San Juan, Alicante, Spain
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Abstract
Nucleotide repeat disorders encompass more than 30 diseases, most of which show dominant inheritance, such as Huntington's disease, spinocerebellar ataxias, and myotonic dystrophies. Yet others, including Friedreich's ataxia, are recessively inherited. A common feature is the presence of a DNA tandem repeat in the disease-associated gene and the propensity of the repeats to expand in germ and in somatic cells, with ensuing neurological and frequently also neuromuscular defects. Repeat expansion is the most frequent event in these diseases; however, sequence contractions, deletions, and mutations have also been reported. Nucleotide repeat sequences are predisposed to adopt non-B-DNA conformations, such as hairpins, cruciform, and intramolecular triple-helix structures (triplexes), also known as H-DNA. For gain-of-function disorders, oligonucleotides can be used to target either transcripts or duplex DNA and in diseases with recessive inheritance oligonucleotides may be used to alter repressive DNA or RNA conformations. Most current treatment strategies are aimed at altering transcript levels, but therapies directed against DNA are also emerging, and novel strategies targeting DNA, instead of RNA, are described. Different mechanisms using modified oligonucleotides are discussed along with the structural aspects of repeat sequences, which can influence binding modes and efficiencies.
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Affiliation(s)
- Rula Zain
- Department of Laboratory Medicine, Centre for Advanced Therapies, Karolinska Institutet, Karolinska University Hospital, SE-141 86, Stockholm, Sweden.
- Department of Clinical Genetics, Centre for Rare Diseases, Karolinska University Hospital, SE-171 76, Stockholm, Sweden.
| | - C I Edvard Smith
- Department of Laboratory Medicine, Centre for Advanced Therapies, Karolinska Institutet, Karolinska University Hospital, SE-141 86, Stockholm, Sweden
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Schreiber AM, Misiorek JO, Napierala JS, Napierala M. Progress in understanding Friedreich's ataxia using human induced pluripotent stem cells. Expert Opin Orphan Drugs 2019; 7:81-90. [PMID: 30828501 DOI: 10.1080/21678707.2019.1562334] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Introduction Friedreich's ataxia (FRDA) is an autosomal recessive multisystem disease mainly affecting the peripheral and central nervous systems, and heart. FRDA is caused by a GAA repeat expansion in the first intron of the frataxin (FXN) gene, that leads to reduced expression of FXN mRNA and frataxin protein. Neuronal and cardiac cells are primary targets of frataxin deficiency and generating models via differentiation of induced pluripotent stem cells (iPSCs) into these cell types is essential for progress towards developing therapies for FRDA. Areas covered This review is focused on modeling FRDA using human iPSCs and various iPSC-differentiated cell types. We emphasized the importance of patient and corrected isogenic cell line pairs to minimize effects caused by biological variability between individuals. Expert opinion The versatility of iPSC-derived cellular models of FRDA is advantageous for developing new therapeutic strategies, and rigorous testing in such models will be critical for approval of the first treatment for FRDA. Creating a well-characterized and diverse set of iPSC lines, including appropriate isogenic controls, will facilitate achieving this goal. Also, improvement of differentiation protocols, especially towards proprioceptive sensory neurons and organoid generation, is necessary to utilize the full potential of iPSC technology in the drug discovery process.
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Affiliation(s)
- Anna M Schreiber
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
| | - Julia O Misiorek
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
| | - Jill S Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham AL, United States
| | - Marek Napierala
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland.,Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham AL, United States
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Peverill RE, Donelan L, Corben LA, Delatycki MB. Differences in the determinants of right ventricular and regional left ventricular long-axis dysfunction in Friedreich ataxia. PLoS One 2018; 13:e0209410. [PMID: 30596685 PMCID: PMC6312254 DOI: 10.1371/journal.pone.0209410] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 12/05/2018] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative condition which also has effects on the heart. In 96% of affected individuals FRDA is due to homozygosity of a GAA repeat expansion in intron 1 of the frataxin (FXN) gene. The number of GAA repeats have been shown to relate to disease severity in FRDA, this thought to be via an inverse relationship of GAA repeat number and cellular frataxin levels. We investigated the effects of FRDA on regional long axis function of the left and right ventricles, and also the relationship of long axis systolic (s`) and early diastolic (e`) peak velocities with GAA repeat number on the shorter (GAA1) and longer FXN alleles (GAA2). METHODS The study group of 78 adult subjects (age 32±9 years) with FRDA and normal left ventricular (LV) ejection fraction were compared to 54 healthy control subjects of similar age, sex and body size. Tissue Doppler imaging (TDI) signals were recorded at the mitral annulus for measurement of s`and e`of the septal, lateral, anterior and inferior walls and at the tricuspid annulus for measurement of right ventricular (RV) s`and e`. RESULTS All the regional LV s`and e`, and both RV s`and RV e`, were lower in individuals with FRDA compared to controls (p<0.001 for all). On multivariate analysis, which included LV septal wall thickness (SWT), RV s`and RV e`were both inversely correlated with GAA1 (β = -0.32 & -0.33, respectively, p = 0.01), but not with GAA2, whereas anterior and lateral s`were both inversely correlated with GAA2 (β = -0.25 and β = -0.28, p = 0.02) but not with GAA1. Increasing SWT was the most consistent LV structural correlate of lower s`and e`, whereas age was a consistent inverse correlate of e`but not of s`. CONCLUSION There are generalized abnormalities of both LV regional and RV long axis function in FRDA, but there are also regional differences in the association of this dysfunction with the smaller and larger GAA repeats in the FXN gene.
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Affiliation(s)
- Roger E. Peverill
- Monash Cardiovascular Research Centre, MonashHeart and Department of Medicine (School of Clinical Sciences at Monash Health), Monash University and Monash Health, Clayton, Victoria, Australia
| | - Lesley Donelan
- Monash Cardiovascular Research Centre, MonashHeart and Department of Medicine (School of Clinical Sciences at Monash Health), Monash University and Monash Health, Clayton, Victoria, Australia
| | - Louise A. Corben
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children’s Research Institute, Parkville, Victoria, Australia
| | - Martin B. Delatycki
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children’s Research Institute, Parkville, Victoria, Australia
- Victorian Clinical Genetics Services, Parkville, Victoria, Australia
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Yau WY, O'Connor E, Sullivan R, Akijian L, Wood NW. DNA repair in trinucleotide repeat ataxias. FEBS J 2018; 285:3669-3682. [PMID: 30152109 DOI: 10.1111/febs.14644] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/15/2018] [Accepted: 08/23/2018] [Indexed: 12/21/2022]
Abstract
The inherited cerebellar ataxias comprise of a genetic heterogeneous group of disorders. Pathogenic expansions of cytosine-adenine-guanine (CAG) encoding polyglutamine tracts account for the largest proportion of autosomal dominant cerebellar ataxias, while GAA expansion in the first introns of frataxin gene is the commonest cause of autosomal recessive cerebellar ataxias. Currently, there is no available treatment to alter the disease trajectory, with devastating consequences for affected individuals. Inter- and Intrafamily phenotypic variability suggest the existence of genetic modifiers, which may become targets amendable to treatment. Recent studies have demonstrated the importance of DNA repair pathways in modifying spinocerebellar ataxia with CAG repeat expansions. In this review, we discuss the mechanisms in which DNA repair pathways, epigenetics and other genetic factors may act as modifiers in cerebellar ataxias due to trinucleotide repeat expansions.
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Affiliation(s)
- Wai Yan Yau
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK
| | - Emer O'Connor
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK
| | - Roisin Sullivan
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK
| | - Layan Akijian
- Department of Neurology, The National Hospital for Neurology and Neurosurgery, London, UK
| | - Nicholas W Wood
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK.,Neurogenetics laboratory, The National Hospital for Neurology and Neurosurgery, London, UK
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