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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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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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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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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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Ho KH, Patrizi A. Assessment of common housekeeping genes as reference for gene expression studies using RT-qPCR in mouse choroid plexus. Sci Rep 2021; 11:3278. [PMID: 33558629 PMCID: PMC7870894 DOI: 10.1038/s41598-021-82800-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 01/25/2021] [Indexed: 01/30/2023] Open
Abstract
Choroid plexus (ChP), a vascularized secretory epithelium located in all brain ventricles, plays critical roles in development, homeostasis and brain repair. Reverse transcription quantitative real-time PCR (RT-qPCR) is a popular and useful technique for measuring gene expression changes and also widely used in ChP studies. However, the reliability of RT-qPCR data is strongly dependent on the choice of reference genes, which are supposed to be stable across all samples. In this study, we validated the expression of 12 well established housekeeping genes in ChP in 2 independent experimental paradigms by using popular stability testing algorithms: BestKeeper, DeltaCq, geNorm and NormFinder. Rer1 and Rpl13a were identified as the most stable genes throughout mouse ChP development, while Hprt1 and Rpl27 were the most stable genes across conditions in a mouse sensory deprivation experiment. In addition, Rpl13a, Rpl27 and Tbp were mutually among the top five most stable genes in both experiments. Normalisation of Ttr and Otx2 expression levels using different housekeeping gene combinations demonstrated the profound effect of reference gene choice on target gene expression. Our study emphasized the importance of validating and selecting stable housekeeping genes under specific experimental conditions.
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Affiliation(s)
- Kim Hoa Ho
- Schaller Research Group, German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Annarita Patrizi
- Schaller Research Group, German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany.
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Li J, Li Y, Wang J, Gonzalez TJ, Asokan A, Napierala JS, Napierala M. Defining Transcription Regulatory Elements in the Human Frataxin Gene: Implications for Gene Therapy. Hum Gene Ther 2020; 31:839-851. [PMID: 32527155 PMCID: PMC7462031 DOI: 10.1089/hum.2020.053] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 05/26/2020] [Indexed: 12/20/2022] Open
Abstract
Friedreich's ataxia (FRDA) is the most common inherited form of ataxia in humans. It is caused by severe downregulation of frataxin (FXN) expression instigated by hyperexpansion of the GAA repeats located in intron 1 of the FXN gene. Despite numerous studies focused on identifying compounds capable of stimulating FXN expression, current knowledge regarding cis-regulatory elements involved in FXN gene expression is lacking. Using a combination of episomal and genome-integrated constructs, we defined a minimal endogenous promoter sequence required to efficiently drive FXN expression in human cells. We generated 19 constructs varying in length of the DNA sequences upstream and downstream of the ATG start codon. Using transient transfection, we evaluated the capability of these constructs to drive FXN expression. These analyses allowed us to identify a region of the gene indispensable for FXN expression. Subsequently, selected constructs containing the FXN expression control regions of varying lengths were site specifically integrated into the genome of HEK293T and human-induced pluripotent stem cells (iPSCs). FXN expression was detected in iPSCs and persisted after differentiation to neuronal and cardiac cells, indicating lineage independent function of defined regulatory DNA sequences. Finally, based on these results, we generated AAV encoding miniFXN genes and demonstrated in vivo FXN expression in mice. Results of these studies identified FXN sequences necessary to express FXN in human and mouse cells and provided rationale for potential use of endogenous FXN sequence in gene therapy strategies for FRDA.
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Affiliation(s)
- Jixue Li
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Yanjie Li
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jun Wang
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Trevor J. Gonzalez
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Aravind Asokan
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Surgery, Duke University School of Medicine, Durham, North Carolina, USA
| | - Jill S. Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Marek Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Gottesfeld JM. Molecular Mechanisms and Therapeutics for the GAA·TTC Expansion Disease Friedreich Ataxia. Neurotherapeutics 2019; 16:1032-1049. [PMID: 31317428 PMCID: PMC6985418 DOI: 10.1007/s13311-019-00764-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Friedreich ataxia (FRDA), the most common inherited ataxia, is caused by transcriptional silencing of the nuclear FXN gene, encoding the essential mitochondrial protein frataxin. Currently, there is no approved therapy for this fatal disorder. Gene silencing in FRDA is due to hyperexpansion of the triplet repeat sequence GAA·TTC in the first intron of the FXN gene, which results in chromatin histone modifications consistent with heterochromatin formation. Frataxin is involved in mitochondrial iron homeostasis and the assembly and transfer of iron-sulfur clusters to various mitochondrial enzymes and components of the electron transport chain. Frataxin insufficiency leads to progressive spinocerebellar neurodegeneration, causing symptoms of gait and limb ataxia, slurred speech, muscle weakness, sensory loss, and cardiomyopathy in many patients, resulting in death in early adulthood. Numerous approaches are being taken to find a treatment for FRDA, including excision or correction of the repeats by genome engineering methods, gene activation with small molecules or artificial transcription factors, delivery of frataxin to affected cells by protein replacement therapy, gene therapy, or small molecules to increase frataxin protein levels, and therapies aimed at countering the cellular consequences of reduced frataxin. This review will summarize the mechanisms involved in repeat-mediated gene silencing and recent efforts aimed at development of therapeutics.
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Affiliation(s)
- Joel M Gottesfeld
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, 92037, USA.
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Clay A, Hearle P, Schadt K, Lynch DR. New developments in pharmacotherapy for Friedreich ataxia. Expert Opin Pharmacother 2019; 20:1855-1867. [PMID: 31311349 DOI: 10.1080/14656566.2019.1639671] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Introduction: Friedreich ataxia (FRDA), a rare disease caused by the deficiency of the mitochondrial matrix protein frataxin, affects roughly 1 in 50,000 individuals worldwide. Current and emerging therapies focus on reversing the deleterious effects of such deficiency including mitochondrial augmentation and increasing frataxin levels, providing the possibility of treatment options for this physiologically complex, multisystem disorder. Areas covered: In this review article, the authors discuss the current and prior in vivo and in vitro research studies related to the treatment of FRDA, with a particular interest in future implications of each therapy. Expert opinion: Since the discovery of FXN in 1996, multiple clinical trials have occurred or are currently occurring; at a rapid pace for a rare disease. These trials have been directed at the augmentation of mitochondrial function and/or alleviation of symptoms and are not regarded as potential cures in FRDA. Either a combination of therapies or a drug that replaces or increases the pathologically low levels of frataxin better represent potential cures in FRDA.
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Affiliation(s)
- Alexandra Clay
- Division of Neurology, Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - Patrick Hearle
- Division of Neurology, Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - Kim Schadt
- Division of Neurology, Children's Hospital of Philadelphia , Philadelphia , PA , USA
| | - David R Lynch
- Division of Neurology, Children's Hospital of Philadelphia , Philadelphia , PA , USA
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Chiang S, Kalinowski DS, Jansson PJ, Richardson DR, Huang MLH. Mitochondrial dysfunction in the neuro-degenerative and cardio-degenerative disease, Friedreich's ataxia. Neurochem Int 2018; 117:35-48. [PMID: 28782591 DOI: 10.1016/j.neuint.2017.08.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 07/25/2017] [Accepted: 08/03/2017] [Indexed: 01/09/2023]
Abstract
Mitochondrial homeostasis is essential for maintaining healthy cellular function and survival. The detrimental involvement of mitochondrial dysfunction in neuro-degenerative diseases has recently been highlighted in human conditions, such as Parkinson's, Alzheimer's and Huntington's disease. Friedreich's ataxia (FA) is another neuro-degenerative, but also cardio-degenerative condition, where mitochondrial dysfunction plays a crucial role in disease progression. Deficient expression of the mitochondrial protein, frataxin, is the primary cause of FA, which leads to adverse alterations in whole cell and mitochondrial iron metabolism. Dys-regulation of iron metabolism in these compartments, results in the accumulation of inorganic iron deposits in the mitochondrial matrix that is thought to potentiate oxidative damage observed in FA. Therefore, the maintenance of mitochondrial homeostasis is crucial in the progression of neuro-degenerative conditions, particularly in FA. In this review, vital mitochondrial homeostatic processes and their roles in FA pathogenesis will be discussed. These include mitochondrial iron processing, mitochondrial dynamics (fusion and fission processes), mitophagy, mitochondrial biogenesis, mitochondrial energy production and calcium metabolism.
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Affiliation(s)
- Shannon Chiang
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Danuta S Kalinowski
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Patric J Jansson
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Des R Richardson
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia.
| | - Michael L-H Huang
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia.
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Cherif K, Gérard C, Rousseau J, Ouellet DL, Chapdelaine P, Tremblay JP. Increased Frataxin Expression Induced in Friedreich Ataxia Cells by Platinum TALE-VP64s or Platinum TALE-SunTag. MOLECULAR THERAPY-NUCLEIC ACIDS 2018; 12:19-32. [PMID: 30195758 PMCID: PMC6019861 DOI: 10.1016/j.omtn.2018.04.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/24/2018] [Accepted: 04/24/2018] [Indexed: 11/28/2022]
Abstract
Frataxin gene (FXN) expression is reduced in Friedreich’s ataxia patients due to an increase in the number of GAA trinucleotides in intron 1. The frataxin protein, encoded by that gene, plays an important role in mitochondria’s iron metabolism. Platinum TALE (plTALE) proteins targeting the regulatory region of the FXN gene, fused with a transcriptional activator (TA) such as VP64 or P300, were used to increase the expression of that gene. Many effectors, plTALEVP64, plTALEp300, and plTALESunTag, targeting 14 sequences of the FXN gene promoter or intron 1 were produced. This permitted selection of 3 plTALEVP64s and 2 plTALESunTag that increased FXN gene expression by up to 19-fold in different Friedreich ataxia (FRDA) primary fibroblasts. Adeno-associated viruses were used to deliver the best effectors to the YG8R mouse model to validate their efficiencies in vivo. Our results showed that these selected plTALEVP64s or plTALESunTag induced transcriptional activity of the endogenous FXN gene as well as expression of the frataxin protein in YG8R mouse heart by 10-fold and in skeletal muscles by up to 35-fold. The aconitase activity was positively modulated by the frataxin level in mitochondria, and it was, thus, increased in vitro and in vivo by the increased frataxin expression.
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Affiliation(s)
- Khadija Cherif
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada
| | - Catherine Gérard
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada
| | - Joël Rousseau
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada
| | - Dominique L Ouellet
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada
| | - Pierre Chapdelaine
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada
| | - Jacques P Tremblay
- Centre de Recherche du CHU, Québec-Université Laval, Québec, QC, Canada; Département de Médecine Moléculaire, l'Université Laval Québec, Québec, QC, Canada.
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Lupoli F, Vannocci T, Longo G, Niccolai N, Pastore A. The role of oxidative stress in Friedreich's ataxia. FEBS Lett 2018; 592:718-727. [PMID: 29197070 PMCID: PMC5887922 DOI: 10.1002/1873-3468.12928] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 11/24/2017] [Accepted: 11/27/2017] [Indexed: 12/12/2022]
Abstract
Oxidative stress and an increase in the levels of free radicals are important markers associated with several pathologies, including Alzheimer's disease, cancer and diabetes. Friedreich's ataxia (FRDA) is an excellent paradigmatic example of a disease in which oxidative stress plays an important, albeit incompletely understood, role. FRDA is a rare genetic neurodegenerative disease that involves the partial silencing of frataxin, a small mitochondrial protein that was completely overlooked before being linked to FRDA. More than 20 years later, we now know how important this protein is in terms of being an essential and vital part of the machinery that produces iron-sulfur clusters in the cell. In this review, we revisit the most important steps that have brought us to our current understanding of the function of frataxin and its role in disease. We discuss the current hypotheses on the role of oxidative stress in FRDA and review some of the existing animal and cellular models. We also evaluate new techniques that can assist in the study of the disease mechanisms, as well as in our understanding of the interplay between primary and secondary phenotypes.
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Affiliation(s)
- Federica Lupoli
- Department of Biotechnology, Chemistry and PharmacyUniversity of SienaItaly
| | - Tommaso Vannocci
- The Maurice Wohl InstituteDementia Research CentreKing's College LondonUK
| | | | - Neri Niccolai
- Department of Biotechnology, Chemistry and PharmacyUniversity of SienaItaly
| | - Annalisa Pastore
- The Maurice Wohl InstituteDementia Research CentreKing's College LondonUK
- Department of Molecular MedicineUniversity of PaviaItaly
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Lin H, Magrane J, Rattelle A, Stepanova A, Galkin A, Clark EM, Dong YN, Halawani SM, Lynch DR. Early cerebellar deficits in mitochondrial biogenesis and respiratory chain complexes in the KIKO mouse model of Friedreich ataxia. Dis Model Mech 2017; 10:1343-1352. [PMID: 29125827 PMCID: PMC5719255 DOI: 10.1242/dmm.030502] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/11/2017] [Indexed: 12/14/2022] Open
Abstract
Friedreich ataxia (FRDA), the most common recessive inherited ataxia, results from deficiency of frataxin, a small mitochondrial protein crucial for iron-sulphur cluster formation and ATP production. Frataxin deficiency is associated with mitochondrial dysfunction in FRDA patients and animal models; however, early mitochondrial pathology in FRDA cerebellum remains elusive. Using frataxin knock-in/knockout (KIKO) mice and KIKO mice carrying the mitoDendra transgene, we show early cerebellar deficits in mitochondrial biogenesis and respiratory chain complexes in this FRDA model. At asymptomatic stages, the levels of PGC-1α (PPARGC1A), the mitochondrial biogenesis master regulator, are significantly decreased in cerebellar homogenates of KIKO mice compared with age-matched controls. Similarly, the levels of the PGC-1α downstream effectors, NRF1 and Tfam, are significantly decreased, suggesting early impaired cerebellar mitochondrial biogenesis pathways. Early mitochondrial deficiency is further supported by significant reduction of the mitochondrial markers GRP75 (HSPA9) and mitofusin-1 in the cerebellar cortex. Moreover, the numbers of Dendra-labeled mitochondria are significantly decreased in cerebellar cortex, confirming asymptomatic cerebellar mitochondrial biogenesis deficits. Functionally, complex I and II enzyme activities are significantly reduced in isolated mitochondria and tissue homogenates from asymptomatic KIKO cerebella. Structurally, levels of the complex I core subunit NUDFB8 and complex II subunits SDHA and SDHB are significantly lower than those in age-matched controls. These results demonstrate complex I and II deficiency in KIKO cerebellum, consistent with defects identified in FRDA patient tissues. Thus, our findings identify early cerebellar mitochondrial biogenesis deficits as a potential mediator of cerebellar dysfunction and ataxia, thereby providing a potential therapeutic target for early intervention of FRDA.
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Affiliation(s)
- Hong Lin
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Jordi Magrane
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA
| | - Amy Rattelle
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Anna Stepanova
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Alexander Galkin
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Elisia M Clark
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yi Na Dong
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Sarah M Halawani
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - David R Lynch
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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13
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Ouellet DL, Cherif K, Rousseau J, Tremblay JP. Deletion of the GAA repeats from the human frataxin gene using the CRISPR-Cas9 system in YG8R-derived cells and mouse models of Friedreich ataxia. Gene Ther 2017; 24:265-274. [PMID: 28024081 DOI: 10.1038/gt.2016.89] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 12/19/2016] [Indexed: 02/07/2023]
Abstract
The Friedreich ataxia is a monogenic disease due to a hyperexpanded GAA triplet located within the first intron of the frataxin gene that causes transcriptional issues. The resulting frataxin protein deficiency leads to a Fe-S cluster biosynthesis dysfunction in the mitochondria and to oxidative stress and cell death. Here we use the CRISPR-Cas9 system to remove the mutated GAA expansion and restore the frataxin gene transcriptional activity and protein level. Both YG8R and YG8sR mouse models and cell lines derived from these mice were used to CRISPR-edited successfully the GAA expansion in vitro and in vivo. Nevertheless, our results suggest the YG8sR as a better and more suitable model for the study of the CRISPR-Cas9 edition of the mutated frataxin gene.
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Affiliation(s)
- D L Ouellet
- Centre de Recherche, Centre Hospitalier, Universitaire de Québec, Quebec City, QC, Canada
- Département de Médecine Moléculaire, Faculté de Médecine, CHU de Québec, Université Laval, Québec City, QC, Canada
| | - K Cherif
- Centre de Recherche, Centre Hospitalier, Universitaire de Québec, Quebec City, QC, Canada
- Département de Médecine Moléculaire, Faculté de Médecine, CHU de Québec, Université Laval, Québec City, QC, Canada
| | - J Rousseau
- Centre de Recherche, Centre Hospitalier, Universitaire de Québec, Quebec City, QC, Canada
- Département de Médecine Moléculaire, Faculté de Médecine, CHU de Québec, Université Laval, Québec City, QC, Canada
| | - J P Tremblay
- Centre de Recherche, Centre Hospitalier, Universitaire de Québec, Quebec City, QC, Canada
- Département de Médecine Moléculaire, Faculté de Médecine, CHU de Québec, Université Laval, Québec City, QC, Canada
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14
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Abstract
INTRODUCTION Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused by expansion of a GAA·TTC triplet in the first intron of the FXN gene, encoding the essential mitochondrial protein frataxin. Repeat expansion results in transcriptional silencing through an epigenetic mechanism, resulting in significant decreases in frataxin protein in affected individuals. Since the FXN protein coding sequence is unchanged in FRDA, an attractive therapeutic approach for this disease would be to increase transcription of pathogenic alleles with small molecules that target the silencing mechanism. AREAS COVERED We review the evidence that histone postsynthetic modifications and heterochromatin formation are responsible for FXN gene silencing in FRDA, along with efforts to reverse silencing with drugs that target histone modifying enzymes. Chemical and pharmacological properties of histone deacetylase (HDAC) inhibitors, which reverse silencing, together with enzyme target profiles and kinetics of inhibition, are discussed. Two HDAC inhibitors have been studied in human clinical trials and the properties of these compounds are compared and contrasted. Efforts to improve on bioavailability, metabolic stability, and target activity are reviewed. EXPERT OPINION 2-aminobenzamide class I HDAC inhibitors are attractive therapeutic small molecules for FRDA. These molecules increase FXN gene expression in human neuronal cells derived from patient induced pluripotent stem cells, and in two mouse models for the disease, as well as in circulating lymphocytes in patients treated in a phase Ib clinical trial. Medicinal chemistry efforts have identified compounds with improved brain penetration, metabolic stability and efficacy in the human neuronal cell model. A clinical candidate will soon be identified for further human testing.
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Affiliation(s)
- Elisabetta Soragni
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037 USA
| | - Joel M Gottesfeld
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037 USA
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15
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Chutake YK, Lam CC, Costello WN, Anderson MP, Bidichandani SI. Reversal of epigenetic promoter silencing in Friedreich ataxia by a class I histone deacetylase inhibitor. Nucleic Acids Res 2016; 44:5095-104. [PMID: 26896803 PMCID: PMC4914082 DOI: 10.1093/nar/gkw107] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 02/13/2016] [Accepted: 02/15/2016] [Indexed: 12/27/2022] Open
Abstract
Friedreich ataxia, the most prevalent inherited ataxia, is caused by an expanded GAA triplet-repeat sequence in intron 1 of the FXN gene. Repressive chromatin spreads from the expanded GAA triplet-repeat sequence to cause epigenetic silencing of the FXN promoter via altered nucleosomal positioning and reduced chromatin accessibility. Indeed, deficient transcriptional initiation is the predominant cause of transcriptional deficiency in Friedreich ataxia. Treatment with 109, a class I histone deacetylase (HDAC) inhibitor, resulted in increased level of FXN transcript both upstream and downstream of the expanded GAA triplet-repeat sequence, without any change in transcript stability, suggesting that it acts via improvement of transcriptional initiation. Quantitative analysis of transcriptional initiation via metabolic labeling of nascent transcripts in patient-derived cells revealed a >3-fold increase (P < 0.05) in FXN promoter function. A concomitant 3-fold improvement (P < 0.001) in FXN promoter structure and chromatin accessibility was observed via Nucleosome Occupancy and Methylome Sequencing, a high-resolution in vivo footprint assay for detecting nucleosome occupancy in individual chromatin fibers. No such improvement in FXN promoter function or structure was observed upon treatment with a chemically-related inactive compound (966). Thus epigenetic promoter silencing in Friedreich ataxia is reversible, and the results implicate class I HDACs in repeat-mediated promoter silencing.
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Affiliation(s)
- Yogesh K Chutake
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104, USA
| | - Christina C Lam
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104, USA
| | - Whitney N Costello
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104, USA
| | - Michael P Anderson
- Department of Biochemistry & Molecular Biology, University of Oklahoma College of Medicine, Oklahoma City, OK 73104, USA
| | - Sanjay I Bidichandani
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104, USA Department of Biostatistics & Epidemiology, University of Oklahoma College of Public Health, Oklahoma City, OK 73104, USA
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