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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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Pilotto F, Del Bondio A, Puccio H. Hereditary Ataxias: From Bench to Clinic, Where Do We Stand? Cells 2024; 13:319. [PMID: 38391932 PMCID: PMC10886822 DOI: 10.3390/cells13040319] [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: 12/01/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 02/24/2024] Open
Abstract
Cerebellar ataxias are a wide heterogeneous group of movement disorders. Within this broad umbrella of diseases, there are both genetics and sporadic forms. The clinical presentation of these conditions can exhibit a diverse range of symptoms across different age groups, spanning from pure cerebellar manifestations to sensory ataxia and multisystemic diseases. Over the last few decades, advancements in our understanding of genetics and molecular pathophysiology related to both dominant and recessive ataxias have propelled the field forward, paving the way for innovative therapeutic strategies aimed at preventing and arresting the progression of these diseases. Nevertheless, the rarity of certain forms of ataxia continues to pose challenges, leading to limited insights into the etiology of the disease and the identification of target pathways. Additionally, the lack of suitable models hampers efforts to comprehensively understand the molecular foundations of disease's pathophysiology and test novel therapeutic interventions. In the following review, we describe the epidemiology, symptomatology, and pathological progression of hereditary ataxia, including both the prevalent and less common forms of these diseases. Furthermore, we illustrate the diverse molecular pathways and therapeutic approaches currently undergoing investigation in both pre-clinical studies and clinical trials. Finally, we address the existing and anticipated challenges within this field, encompassing both basic research and clinical endeavors.
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Affiliation(s)
- Federica Pilotto
- Institut Neuromyogène, Pathophysiology and Genetics of Neuron and Muscle, Inserm U1315, CNRS-Université Claude Bernard Lyon 1 UMR5261, 69008 Lyon, France
| | - Andrea Del Bondio
- Institut Neuromyogène, Pathophysiology and Genetics of Neuron and Muscle, Inserm U1315, CNRS-Université Claude Bernard Lyon 1 UMR5261, 69008 Lyon, France
| | - Hélène Puccio
- Institut Neuromyogène, Pathophysiology and Genetics of Neuron and Muscle, Inserm U1315, CNRS-Université Claude Bernard Lyon 1 UMR5261, 69008 Lyon, France
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3
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Edzeamey FJ, Ramchunder Z, Pourzand C, Anjomani Virmouni S. Emerging antioxidant therapies in Friedreich's ataxia. Front Pharmacol 2024; 15:1359618. [PMID: 38379897 PMCID: PMC10876797 DOI: 10.3389/fphar.2024.1359618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 01/25/2024] [Indexed: 02/22/2024] Open
Abstract
Friedreich's ataxia (FRDA) is a rare childhood neurologic disorder, affecting 1 in 50,000 Caucasians. The disease is caused by the abnormal expansion of the GAA repeat sequence in intron 1 of the FXN gene, leading to the reduced expression of the mitochondrial protein frataxin. The disease is characterised by progressive neurodegeneration, hypertrophic cardiomyopathy, diabetes mellitus and musculoskeletal deformities. The reduced expression of frataxin has been suggested to result in the downregulation of endogenous antioxidant defence mechanisms and mitochondrial bioenergetics, and the increase in mitochondrial iron accumulation thereby leading to oxidative stress. The confirmation of oxidative stress as one of the pathological signatures of FRDA led to the search for antioxidants which can be used as therapeutic modality. Based on this observation, antioxidants with different mechanisms of action have been explored for FRDA therapy since the last two decades. In this review, we bring forth all antioxidants which have been investigated for FRDA therapy and have been signed off for clinical trials. We summarise their various target points in FRDA disease pathway, their performances during clinical trials and possible factors which might have accounted for their failure or otherwise during clinical trials. We also discuss the limitation of the studies completed and propose possible strategies for combinatorial therapy of antioxidants to generate synergistic effect in FRDA patients.
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Affiliation(s)
- Fred Jonathan Edzeamey
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, College of Health, Medicine, and Life Sciences (CHMLS), Brunel University London, Uxbridge, United Kingdom
| | - Zenouska Ramchunder
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, College of Health, Medicine, and Life Sciences (CHMLS), Brunel University London, Uxbridge, United Kingdom
| | - Charareh Pourzand
- Department of Life Sciences, University of Bath, Bath, United Kingdom
- Centre for Therapeutic Innovation, University of Bath, Bath, United Kingdom
| | - Sara Anjomani Virmouni
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, College of Health, Medicine, and Life Sciences (CHMLS), Brunel University London, Uxbridge, United Kingdom
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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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5
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Xiao S, Kai Z, Murphy D, Li D, Patel D, Bielowka AM, Bernabeu-Herrero ME, Abdulmogith A, Mumford AD, Westbury SK, Aldred MA, Vargesson N, Caulfield MJ, Shovlin CL. Functional filter for whole-genome sequencing data identifies HHT and stress-associated non-coding SMAD4 polyadenylation site variants >5 kb from coding DNA. Am J Hum Genet 2023; 110:1903-1918. [PMID: 37816352 PMCID: PMC10645545 DOI: 10.1016/j.ajhg.2023.09.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 09/01/2023] [Accepted: 09/08/2023] [Indexed: 10/12/2023] Open
Abstract
Despite whole-genome sequencing (WGS), many cases of single-gene disorders remain unsolved, impeding diagnosis and preventative care for people whose disease-causing variants escape detection. Since early WGS data analytic steps prioritize protein-coding sequences, to simultaneously prioritize variants in non-coding regions rich in transcribed and critical regulatory sequences, we developed GROFFFY, an analytic tool that integrates coordinates for regions with experimental evidence of functionality. Applied to WGS data from solved and unsolved hereditary hemorrhagic telangiectasia (HHT) recruits to the 100,000 Genomes Project, GROFFFY-based filtration reduced the mean number of variants/DNA from 4,867,167 to 21,486, without deleting disease-causal variants. In three unsolved cases (two related), GROFFFY identified ultra-rare deletions within the 3' untranslated region (UTR) of the tumor suppressor SMAD4, where germline loss-of-function alleles cause combined HHT and colonic polyposis (MIM: 175050). Sited >5.4 kb distal to coding DNA, the deletions did not modify or generate microRNA binding sites, but instead disrupted the sequence context of the final cleavage and polyadenylation site necessary for protein production: By iFoldRNA, an AAUAAA-adjacent 16-nucleotide deletion brought the cleavage site into inaccessible neighboring secondary structures, while a 4-nucleotide deletion unfolded the downstream RNA polymerase II roadblock. SMAD4 RNA expression differed to control-derived RNA from resting and cycloheximide-stressed peripheral blood mononuclear cells. Patterns predicted the mutational site for an unrelated HHT/polyposis-affected individual, where a complex insertion was subsequently identified. In conclusion, we describe a functional rare variant type that impacts regulatory systems based on RNA polyadenylation. Extension of coding sequence-focused gene panels is required to capture these variants.
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Affiliation(s)
- Sihao Xiao
- National Heart and Lung Institute, Imperial College London, W12 ONN London, UK; National Institute for Health Research (NIHR) Imperial Biomedical Research Centre, W2 1NY London, UK.
| | - Zhentian Kai
- Topgen Biopharm Technology Co. Ltd., Shanghai 201203, China
| | - Daniel Murphy
- National Institute for Health Research (NIHR) Imperial Biomedical Research Centre, W2 1NY London, UK; Women's, Children's & Clinical Support (Pharmacy), Imperial College Healthcare NHS Trust, W2 1NY London, UK
| | - Dongyang Li
- National Heart and Lung Institute, Imperial College London, W12 ONN London, UK; National Institute for Health Research (NIHR) Imperial Biomedical Research Centre, W2 1NY London, UK
| | - Dilip Patel
- National Heart and Lung Institute, Imperial College London, W12 ONN London, UK; National Institute for Health Research (NIHR) Imperial Biomedical Research Centre, W2 1NY London, UK
| | - Adrianna M Bielowka
- National Heart and Lung Institute, Imperial College London, W12 ONN London, UK; National Institute for Health Research (NIHR) Imperial Biomedical Research Centre, W2 1NY London, UK
| | - Maria E Bernabeu-Herrero
- National Heart and Lung Institute, Imperial College London, W12 ONN London, UK; National Institute for Health Research (NIHR) Imperial Biomedical Research Centre, W2 1NY London, UK
| | - Awatif Abdulmogith
- National Heart and Lung Institute, Imperial College London, W12 ONN London, UK; National Institute for Health Research (NIHR) Imperial Biomedical Research Centre, W2 1NY London, UK
| | - Andrew D Mumford
- School of Cellular and Molecular Medicine, University of Bristol, BS8 1QU Bristol, UK
| | - Sarah K Westbury
- School of Cellular and Molecular Medicine, University of Bristol, BS8 1QU Bristol, UK
| | - Micheala A Aldred
- Division of Pulmonary, Critical Care, Sleep & Occupational Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Neil Vargesson
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, AB25 2ZD Aberdeen, UK
| | - Mark J Caulfield
- William Harvey Research Institute, Queen Mary University of London, E1 4NS London, UK
| | - Claire L Shovlin
- National Heart and Lung Institute, Imperial College London, W12 ONN London, UK; National Institute for Health Research (NIHR) Imperial Biomedical Research Centre, W2 1NY London, UK; Specialist Medicine, Imperial College Healthcare NHS Trust, W12 OHS London, UK.
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6
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Yaméogo P, Gérard C, Majeau N, Tremblay JP. Removal of the GAA repeat in the heart of a Friedreich's ataxia mouse model using CjCas9. Gene Ther 2023; 30:612-619. [PMID: 36781946 DOI: 10.1038/s41434-023-00387-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/12/2023] [Accepted: 01/27/2023] [Indexed: 02/15/2023]
Abstract
Most Friedreich ataxia (FRDA) cases are caused by the elongation of the GAA repeat (GAAr) sequence in the first intron of the FXN gene, leading to a decrease of the frataxin protein expression. Deletion of this GAAr with CRISPR/Cas9 technology leads to an increase in frataxin expression in vitro. We are therefore aiming to develop FRDA treatment based on the deletion of GAAr with CRISPR/Cas9 technology using a single AAV expressing a small Cas9 (CjCas9) and two single guide RNAs (sgRNAs) targeting the FXN gene. This AAV was intraperitoneally administrated to YG8sR (250-300 GAAr) and to YG8-800 (800 GAAr) mice. DNA and RNA were extracted from different organs a month later. PCR amplification of part of intron 1 of the FXN gene detected some GAAr deletion in some cells in heart and liver of both mouse models, but the editing rate was not sufficient to cause an increase in frataxin mRNA in the heart. However, the correlation observed between the editing rate and the distribution of AAV suggests a possible therapy based on the removal of the GAAr with a better delivery tool of the CRISPR/Cas9 system.
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Affiliation(s)
- Pouiré Yaméogo
- Centre de Recherche du CHU de Québec-Université Laval, Québec city, QC, Canada
- Département de Médecine Moléculaire, Université Laval, Québec city, QC, Canada
| | - Catherine Gérard
- Centre de Recherche du CHU de Québec-Université Laval, Québec city, QC, Canada
- Département de Médecine Moléculaire, Université Laval, Québec city, QC, Canada
| | - Nathalie Majeau
- Centre de Recherche du CHU de Québec-Université Laval, Québec city, QC, Canada
- Département de Médecine Moléculaire, Université Laval, Québec city, QC, Canada
| | - Jacques P Tremblay
- Centre de Recherche du CHU de Québec-Université Laval, Québec city, QC, Canada.
- Département de Médecine Moléculaire, Université Laval, Québec city, QC, Canada.
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