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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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2
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Chang JC, Ryan MR, Stark MC, Liu S, Purushothaman P, Bolan F, Johnson CA, Champe M, Meng H, Lawlor MW, Halawani S, Ngaba LV, Lynch DR, Davis C, Gonzalo-Gil E, Lutz C, Urbinati F, Medicherla B, Fonck C. AAV8 gene therapy reverses cardiac pathology and prevents early mortality in a mouse model of Friedreich's ataxia. Mol Ther Methods Clin Dev 2024; 32:101193. [PMID: 38352270 PMCID: PMC10862410 DOI: 10.1016/j.omtm.2024.101193] [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: 06/22/2023] [Accepted: 01/18/2024] [Indexed: 02/16/2024]
Abstract
Friedreich's ataxia (FRDA) is an autosomal-recessive disorder primarily attributed to biallelic GAA repeat expansions that reduce expression of the mitochondrial protein frataxin (FXN). FRDA is characterized by progressive neurodegeneration, with many patients developing cardiomyopathy that progresses to heart failure and death. The potential to reverse or prevent progression of the cardiac phenotype of FRDA was investigated in a mouse model of FRDA, using an adeno-associated viral vector (AAV8) containing the coding sequence of the FXN gene. The Fxnflox/null::MCK-Cre conditional knockout mouse (FXN-MCK) has an FXN gene ablation that prevents FXN expression in cardiac and skeletal muscle, leading to cardiac insufficiency, weight loss, and morbidity. FXN-MCK mice received a single intravenous injection of an AAV8 vector containing human (hFXN) or mouse (mFXN) FXN genes under the control of a phosphoglycerate kinase promoter. Compared to vehicle-treated FXN-MCK control mice, AAV-treated FXN-MCK mice displayed increases in body weight, reversal of cardiac deficits, and increases in survival without apparent toxicity in the heart or liver for up to 12 weeks postdose. FXN protein expression in heart tissue was detected in a dose-dependent manner, exhibiting wide distribution throughout the heart similar to wild type, but more speckled. These results support an AAV8-based approach to treat FRDA-associated cardiomyopathy.
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Affiliation(s)
- Joshua C. Chang
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Molly R. Ryan
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Marie C. Stark
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Su Liu
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | | | - Fria Bolan
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | | | - Mark Champe
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Hui Meng
- Diverge Translational Science Laboratory, Milwaukee, WI 53204, USA
- Medical College of Wisconsin, Department of Pathology and Laboratory Medicine, Milwaukee, WI 53226, USA
| | - Michael W. Lawlor
- Diverge Translational Science Laboratory, Milwaukee, WI 53204, USA
- Medical College of Wisconsin, Department of Pathology and Laboratory Medicine, Milwaukee, WI 53226, USA
| | - Sarah Halawani
- Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Lucie V. Ngaba
- Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - David R. Lynch
- Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | | | | | | | - Fabrizia Urbinati
- Formerly of Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Bala Medicherla
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Carlos Fonck
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
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3
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Clayton R, Galas T, Scherer N, Farmer J, Ruiz N, Hamdani M, Schecter D, Bettoun D. Safety, pharmacokinetics, and pharmacodynamics of nomlabofusp (CTI-1601) in Friedreich's ataxia. Ann Clin Transl Neurol 2024; 11:540-553. [PMID: 38311797 PMCID: PMC10963286 DOI: 10.1002/acn3.51971] [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: 04/13/2023] [Revised: 10/19/2023] [Accepted: 11/05/2023] [Indexed: 02/06/2024] Open
Abstract
OBJECTIVE Current treatments for Friedreich's ataxia, a neurodegenerative disorder characterized by decreased intramitochondrial frataxin, do not address low frataxin concentrations. Nomlabofusp (previously CTI-1601) is a frataxin replacement therapy with a unique mechanism of action that directly addresses this underlying frataxin deficiency. Phase 1 studies assessed the safety, pharmacokinetic, and pharmacodynamic profiles of subcutaneously administered nomlabofusp in adults with Friedreich's ataxia. METHODS Patients were enrolled in two Phase 1, double-blind, placebo-controlled studies. The single ascending-dose (SAD) study (NCT04176991) evaluated single doses of nomlabofusp (25, 50, 75, or 100 mg) or placebo. The multiple ascending-dose (MAD) study (NCT04519567) evaluated nomlabofusp (25 mg daily for 4 days then every third day, 50 mg daily for 7 days then every 2 days, or 100 mg daily) or placebo for 13 days. RESULTS Patients aged 19-69 years were enrolled (SAD, N = 28; MAD, N = 27). Nomlabofusp was generally well tolerated through 13 days. Most adverse events were mild and resolved quickly. No serious adverse events or deaths were reported. Peak nomlabofusp plasma concentrations occurred 15 min after subcutaneous administration. Nomlabofusp plasma exposures increased with increasing doses and daily administration and decreased with reduced dosing frequency. Increased frataxin concentrations were observed in buccal cells, skin, and platelets with higher and more frequent nomlabofusp administration. INTERPRETATION Results from this study support a favorable safety profile for nomlabofusp. Subcutaneous nomlabofusp injections were quickly absorbed; higher doses and daily administration resulted in increased tissue frataxin concentrations. Future studies will evaluate longer-term safety and possible efficacy of nomlabofusp.
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Affiliation(s)
| | - Teresa Galas
- Larimar Therapeutics, Inc.Bala CynwydPennsylvaniaUSA
| | | | - Jennifer Farmer
- Friedreich's Ataxia Research Alliance (FARA)DowningtownPennsylvaniaUSA
| | - Nancy Ruiz
- Larimar Therapeutics, Inc.Bala CynwydPennsylvaniaUSA
| | | | | | - David Bettoun
- Larimar Therapeutics, Inc.Bala CynwydPennsylvaniaUSA
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Wang Q, Laboureur L, Weng L, Eskenazi NM, Hauser LA, Mesaros C, Lynch DR, Blair IA. Simultaneous Quantification of Mitochondrial Mature Frataxin and Extra-Mitochondrial Frataxin Isoform E in Friedreich’s Ataxia Blood. Front Neurosci 2022; 16:874768. [PMID: 35573317 PMCID: PMC9098139 DOI: 10.3389/fnins.2022.874768] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 03/22/2022] [Indexed: 11/25/2022] Open
Abstract
Friedreich’s ataxia (FRDA) is an autosomal recessive disease caused by an intronic guanine-adenine-adenine (GAA) triplet expansion in the frataxin (FXN) gene, which leads to reduced expression of full-length frataxin (1–210) also known as isoform 1. Full-length frataxin has a mitochondrial targeting sequence, which facilitates its translocation into mitochondria where it is processed through cleavage at G41-L42 and K80-S81 by mitochondrial processing (MPP) to release mitochondrial mature frataxin (81–210). Alternative splicing of FXN also leads to expression of N-terminally acetylated extra-mitochondrial frataxin (76–210) named isoform E because it was discovered in erythrocytes. Frataxin isoforms are undetectable in serum or plasma, and originally whole blood could not be used as a biomarker in brief therapeutic trials because it is present in erythrocytes, which have a half-life of 115-days and so frataxin levels would remain unaltered. Therefore, an assay was developed for analyzing frataxin in platelets, which have a half-life of only 10-days. However, our discovery that isoform E is only present in erythrocytes, whereas, mature frataxin is present primarily in short-lived peripheral blood mononuclear cells (PBMCs), granulocytes, and platelets, meant that both proteins could be quantified in whole blood samples. We now report a quantitative assay for frataxin proteoforms in whole blood from healthy controls and FRDA patients. The assay is based on stable isotope dilution coupled with immunoprecipitation (IP) and two-dimensional-nano-ultrahigh performance liquid chromatography/parallel reaction monitoring/high resolution mass spectrometry (2D-nano-UHPLC-PRM/HRMS). The lower limit of quantification was 0.5 ng/mL for each proteoform and the assays had 100% sensitivity and specificity for discriminating between healthy controls (n = 11) and FRDA cases (N = 100 in year-1, N = 22 in year-2,3). The mean levels of mature frataxin in whole blood from healthy controls and homozygous FRDA patients were significantly different (p < 0.0001) at 7.5 ± 1.5 ng/mL and 2.1 ± 1.2 ng/mL, respectively. The mean levels of isoform E in whole blood from healthy controls and homozygous FRDA patients were significantly different (p < 0.0001) at 26.8 ± 4.1 ng/mL and 4.7 ± 3.3 ng/mL, respectively. The mean levels of total frataxin in whole blood from healthy controls and homozygous FRDA patients were significantly different (p < 0.0001) at 34.2 ± 4.3 ng/mL and 6.8 ± 4.0 ng/mL, respectively. The assay will make it possible to rigorously monitor the natural history of the disease and explore the potential role of isoform E in etiology of the disease. It will also facilitate the assessment of therapeutic interventions (including gene therapy approaches) that attempt to increase frataxin protein expression as a treatment for this devastating disease.
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Affiliation(s)
- Qingqing Wang
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
| | - Laurent Laboureur
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
| | - Liwei Weng
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
| | - Nicolas M. Eskenazi
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
| | - Lauren A. Hauser
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA, United States
- Departments of Pediatrics and Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Clementina Mesaros
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
| | - David R. Lynch
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA, United States
- Departments of Pediatrics and Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Ian A. Blair
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, PA, United States
- *Correspondence: Ian A. Blair,
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5
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Recessive cerebellar and afferent ataxias - clinical challenges and future directions. Nat Rev Neurol 2022; 18:257-272. [PMID: 35332317 DOI: 10.1038/s41582-022-00634-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/17/2022] [Indexed: 02/07/2023]
Abstract
Cerebellar and afferent ataxias present with a characteristic gait disorder that reflects cerebellar motor dysfunction and sensory loss. These disorders are a diagnostic challenge for clinicians because of the large number of acquired and inherited diseases that cause cerebellar and sensory neuron damage. Among such conditions that are recessively inherited, Friedreich ataxia and RFC1-associated cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) include the characteristic clinical, neuropathological and imaging features of ganglionopathies, a distinctive non-length-dependent type of sensory involvement. In this Review, we discuss the typical and atypical phenotypes of Friedreich ataxia and CANVAS, along with the features of other recessive ataxias that present with a ganglionopathy or polyneuropathy, with an emphasis on recently described clinical features, natural history and genotype-phenotype correlations. We review the main developments in understanding the complex pathology that affects the sensory neurons and cerebellum, which seem to be most vulnerable to disorders that affect mitochondrial function and DNA repair mechanisms. Finally, we discuss disease-modifying therapeutic advances in Friedreich ataxia, highlighting the most promising candidate molecules and lessons learned from previous clinical trials.
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6
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Rodden LN, Gilliam KM, Lam C, Lynch DR, Bidichandani SI. Epigenetic Heterogeneity in Friedreich Ataxia Underlies Variable FXN Reactivation. Front Neurosci 2021; 15:752921. [PMID: 34899161 PMCID: PMC8655727 DOI: 10.3389/fnins.2021.752921] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
Friedreich ataxia (FRDA) is typically caused by homozygosity for an expanded GAA triplet-repeat in intron 1 of the FXN gene. The expanded repeat induces repressive histone changes and DNA hypermethylation, which result in epigenetic silencing and FXN transcriptional deficiency. A class I histone deacetylase inhibitor (HDACi-109) reactivates the silenced FXN gene, although with considerable inter-individual variability, which remains etiologically unexplained. Because HDAC inhibitors work by reversing epigenetic silencing, we reasoned that epigenetic heterogeneity among patients may help to explain this inter-individual variability. As a surrogate measure for epigenetic heterogeneity, a highly quantitative measurement of DNA hypermethylation via bisulfite deep sequencing, with single molecule resolution, was used to assess the prevalence of unmethylated, partially methylated, and fully methylated somatic FXN molecules in PBMCs from a prospective cohort of 50 FRDA patients. Treatment of the same PBMCs from this cohort with HDACi-109 significantly increased FXN transcript to levels seen in asymptomatic heterozygous carriers, albeit with the expected inter-individual variability. Response to HDACi-109 correlated significantly with the prevalence of unmethylated and partially methylated FXN molecules, supporting the model that FXN reactivation involves a proportion of genes that are amenable to correction in non-dividing somatic cells, and that heavily methylated FXN molecules are relatively resistant to reactivation. FXN reactivation is a promising therapeutic strategy in FRDA, and inter-individual variability is explained, at least in part, by somatic epigenetic heterogeneity.
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Affiliation(s)
- Layne N Rodden
- Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Oklahoma Center for Neuroscience, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Kaitlyn M Gilliam
- Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Christina Lam
- Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - David R Lynch
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Sanjay I Bidichandani
- Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Oklahoma Center for Neuroscience, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Biochemistry and Molecular Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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7
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Igoillo-Esteve M, Oliveira AF, Cosentino C, Fantuzzi F, Demarez C, Toivonen S, Hu A, Chintawar S, Lopes M, Pachera N, Cai Y, Abdulkarim B, Rai M, Marselli L, Marchetti P, Tariq M, Jonas JC, Boscolo M, Pandolfo M, Eizirik DL, Cnop M. Exenatide induces frataxin expression and improves mitochondrial function in Friedreich ataxia. JCI Insight 2020; 5:134221. [PMID: 31877117 PMCID: PMC7098728 DOI: 10.1172/jci.insight.134221] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 12/18/2019] [Indexed: 12/26/2022] Open
Abstract
Friedreich ataxia is an autosomal recessive neurodegenerative disease associated with a high diabetes prevalence. No treatment is available to prevent or delay disease progression. Friedreich ataxia is caused by intronic GAA trinucleotide repeat expansions in the frataxin-encoding FXN gene that reduce frataxin expression, impair iron-sulfur cluster biogenesis, cause oxidative stress, and result in mitochondrial dysfunction and apoptosis. Here we examined the metabolic, neuroprotective, and frataxin-inducing effects of glucagon-like peptide-1 (GLP-1) analogs in in vivo and in vitro models and in patients with Friedreich ataxia. The GLP-1 analog exenatide improved glucose homeostasis of frataxin-deficient mice through enhanced insulin content and secretion in pancreatic β cells. Exenatide induced frataxin and iron-sulfur cluster-containing proteins in β cells and brain and was protective to sensory neurons in dorsal root ganglia. GLP-1 analogs also induced frataxin expression, reduced oxidative stress, and improved mitochondrial function in Friedreich ataxia patients' induced pluripotent stem cell-derived β cells and sensory neurons. The frataxin-inducing effect of exenatide was confirmed in a pilot trial in Friedreich ataxia patients, showing modest frataxin induction in platelets over a 5-week treatment course. Taken together, GLP-1 analogs improve mitochondrial function in frataxin-deficient cells and induce frataxin expression. Our findings identify incretin receptors as a therapeutic target in Friedreich ataxia.
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Affiliation(s)
| | | | | | - Federica Fantuzzi
- ULB Center for Diabetes Research and
- Endocrinology and Metabolism, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | | | | | - Amélie Hu
- Laboratory of Experimental Neurology, Université Libre de Bruxelles, Brussels, Belgium
| | - Satyan Chintawar
- Laboratory of Experimental Neurology, Université Libre de Bruxelles, Brussels, Belgium
| | | | | | - Ying Cai
- ULB Center for Diabetes Research and
| | | | - Myriam Rai
- Laboratory of Experimental Neurology, Université Libre de Bruxelles, Brussels, Belgium
| | - Lorella Marselli
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Mohammad Tariq
- Pole of Endocrinology, Diabetes and Nutrition, Institute of Experimental and Clinical Research, Université Catholique de Louvain, Brussels, Belgium
| | - Jean-Christophe Jonas
- Pole of Endocrinology, Diabetes and Nutrition, Institute of Experimental and Clinical Research, Université Catholique de Louvain, Brussels, Belgium
| | - Marina Boscolo
- Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Massimo Pandolfo
- Laboratory of Experimental Neurology, Université Libre de Bruxelles, Brussels, Belgium
| | - Décio L. Eizirik
- ULB Center for Diabetes Research and
- Indiana Biosciences Research Institute, Indianapolis, Indiana, USA
| | - Miriam Cnop
- ULB Center for Diabetes Research and
- Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
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8
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Fedotova E, Abramycheva N, Nuzhny E, Ershova M, Klyushnikov S, Illarioshkin S. Friedreich ataxia: FXN gene expression and its relationship with DNA methylation pattern. BULLETIN OF RUSSIAN STATE MEDICAL UNIVERSITY 2019. [DOI: 10.24075/brsmu.2019.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Friedreich ataxia (FRDA) is the most common autosomal recessive ataxia associated with the non-coding GAA tandem repeats expansion in the FXN gene. Transcription impairment and frataxin protein deficiency are the key features of the disease pathogenesis. Our research was aimed to study the FXN gene mRNA expression as well as to carry out the clinical, genetic and epigenetic correlation analysis in a group of patients with homozygous expansion, in a group of their relatives with heterozygous expansion and in a control group. The FXN mRNA level was determined using the real-time polymerase chain reaction. Methylation pattern of CpG sites was evaluated by direct bisulfite sequencing. As a result of the study, the threshold values were obtained between the FRDA patients group, the group of heterozygous carriers and the control group (15 and 79%, respectively). The clinical and genetic features comparison with the FXN expression level revealed no significant correlation. When comparing gene expression with an epigenetic profile, it was found that hypermethylation of a number of CpG sites upstream of the trinucleotide repeats and some non-CpG sites downstream of the region of repeats inhibited expression. Thus, the identified methylated sites may be considered as a target for epigenome editing to increase the FXN transcription and, consequently, for target therapy of the disease.
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Affiliation(s)
| | | | - E.P. Nuzhny
- Research Center of Neurology, Moscow, Russia
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9
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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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10
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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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The current state of biomarker research for Friedreich's ataxia: a report from the 2018 FARA biomarker meeting. Future Sci OA 2019; 5:FSO398. [PMID: 31285843 PMCID: PMC6609901 DOI: 10.2144/fsoa-2019-0026] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The 2018 FARA Biomarker Meeting highlighted the current state of development of biomarkers for Friedreich’s ataxia. A mass spectroscopy assay to sensitively measure mature frataxin (reduction of which is the root cause of disease) is being developed. Biomarkers to monitor neurological disease progression include imaging, electrophysiological measures and measures of nerve function, which may be measured either in serum and/or through imaging-based technologies. Potential pharmacodynamic biomarkers include metabolic and protein biomarkers and markers of nerve damage. Cardiac imaging and serum biomarkers may reflect cardiac disease progression. Considerable progress has been made in the development of biomarkers for various contexts of use, but further work is needed in terms of larger longitudinal multisite studies, and identification of novel biomarkers for additional use cases Biomarkers are characteristics that can be objectively measured, evaluated and used as indicators of disease progression or the effect of a therapy. Friedreich’s ataxia is a progressive multisystem neuromuscular disease with no treatment. Current clinical measures cannot robustly detect disease progression in less than a year, meaning that clinical trials are long and drug development is slow. The Friedreich’s Ataxia Research Alliance and the scientific community are looking for biomarkers that show change in shorter time frames that can accelerate drug development. The 2018 FARA Biomarker Meeting summarized the exciting findings that represent the current state of the field.
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Guo L, Wang Q, Weng L, Hauser LA, Strawser CJ, Mesaros C, Lynch DR, Blair IA. Characterization of a new N-terminally acetylated extra-mitochondrial isoform of frataxin in human erythrocytes. Sci Rep 2018; 8:17043. [PMID: 30451920 PMCID: PMC6242848 DOI: 10.1038/s41598-018-35346-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 11/02/2018] [Indexed: 01/18/2023] Open
Abstract
Frataxin is a highly conserved protein encoded by the frataxin (FXN) gene. The full-length 210-amino acid form of protein frataxin (1-210; isoform A) expressed in the cytosol of cells rapidly translocates to the mitochondria, where it is converted to the mature form (81-210) by mitochondrial processing peptidase. Mature frataxin (81-210) is a critically important protein because it facilitates the assembly of mitochondrial iron-sulfur cluster protein complexes such as aconitase, lipoate synthase, and succinate dehydrogenases. Decreased expression of frataxin protein is responsible for the devastating rare genetic disease of Friedreich's ataxia. The mitochondrial form of frataxin has long been thought to be present in erythrocytes even though paradoxically, erythrocytes lack mitochondria. We have discovered that erythrocyte frataxin is in fact a novel isoform of frataxin (isoform E) with 135-amino acids and an N-terminally acetylated methionine residue. There is three times as much isoform E in erythrocytes (20.9 ± 6.4 ng/mL) from the whole blood of healthy volunteers (n = 10) when compared with the mature mitochondrial frataxin present in other blood cells (7.1 ± 1.0 ng/mL). Isoform E lacks a mitochondrial targeting sequence and so is distributed to both cytosol and the nucleus when expressed in cultured cells. When extra-mitochondrial frataxin isoform E is expressed in HEK 293 cells, it is converted to a shorter isoform identical to the mature frataxin found in mitochondria, which raises the possibility that it is involved in disease etiology. The ability to specifically quantify extra-mitochondrial and mitochondrial isoforms of frataxin in whole blood will make it possible to readily follow the natural history of diseases such as Friedreich's ataxia and monitor the efficacy of therapeutic interventions.
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Affiliation(s)
- Lili Guo
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, United States
- Penn/CHOP Center of Excellence in Friedreich's ataxia, Philadelphia, PA, 19104, United States
| | - Qingqing Wang
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, United States
- Penn/CHOP Center of Excellence in Friedreich's ataxia, Philadelphia, PA, 19104, United States
| | - Liwei Weng
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, United States
| | - Lauren A Hauser
- Penn/CHOP Center of Excellence in Friedreich's ataxia, Philadelphia, PA, 19104, United States
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, United States
- Departments of Pediatrics and Neurology Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, United States
| | - Cassandra J Strawser
- Penn/CHOP Center of Excellence in Friedreich's ataxia, Philadelphia, PA, 19104, United States
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, United States
- Departments of Pediatrics and Neurology Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, United States
| | - Clementina Mesaros
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, United States
- Penn/CHOP Center of Excellence in Friedreich's ataxia, Philadelphia, PA, 19104, United States
| | - David R Lynch
- Penn/CHOP Center of Excellence in Friedreich's ataxia, Philadelphia, PA, 19104, United States
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, United States
- Departments of Pediatrics and Neurology Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, United States
| | - Ian A Blair
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, United States.
- Penn/CHOP Center of Excellence in Friedreich's ataxia, Philadelphia, PA, 19104, United States.
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Wang Q, Guo L, Strawser CJ, Hauser LA, Hwang WT, Snyder NW, Lynch DR, Mesaros C, Blair IA. Low apolipoprotein A-I levels in Friedreich's ataxia and in frataxin-deficient cells: Implications for therapy. PLoS One 2018; 13:e0192779. [PMID: 29447225 PMCID: PMC5813973 DOI: 10.1371/journal.pone.0192779] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 01/30/2018] [Indexed: 12/21/2022] Open
Abstract
Friedreich's ataxia (FA) is an autosomal recessive neurodegenerative disorder, which results primarily from reduced expression of the mitochondrial protein frataxin. FA has an estimated prevalence of one in 50,000 in the population, making it the most common hereditary ataxia. Paradoxically, mortality arises most frequently from cardiomyopathy and cardiac failure rather than from neurological effects. Decreased high-density lipoprotein (HDL) and apolipoprotein A-I (ApoA-l) levels in the general population are associated with an increased risk of mortality from cardiomyopathy and heart failure. However, the pathophysiology of heart disease in FA is non-vascular and there are conflicting data on HDL-cholesterol in FA. Two studies have shown a decrease in HDL-cholesterol compared with controls and two have shown there was no difference between FA and controls. One also showed that there was no difference in serum Apo-A-I levels in FA when compared with controls. Using a highly specific stable isotope dilution mass spectrometry-based assay, we demonstrated a 21.6% decrease in serum ApoA-I in FA patients (134.8 mg/dL, n = 95) compared with non-affected controls (172.1 mg/dL, n = 95). This is similar to the difference in serum ApoA-I levels between non-smokers and tobacco smokers. Knockdown of frataxin by > 70% in human hepatoma HepG2 cells caused a 20% reduction in secreted ApoA-I. Simvastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor caused a 200% increase in HMG-CoA in the control HepG2 cells with a similar increase in the frataxin knockdown HepG2 cells, back to levels found in the control cells. There was a concomitant 20% increase in secreted ApoA-I to levels found in the control cells that were treated with simvastatin. This study provides compelling evidence that ApoA-I levels are reduced in FA patients compared with controls and suggest that statin treatment would normalize the ApoA-I levels.
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Affiliation(s)
- QingQing Wang
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Lili Guo
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Cassandra J. Strawser
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Division of Neurology, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Lauren A. Hauser
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Division of Neurology, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Wei-Ting Hwang
- Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Nathaniel W. Snyder
- AJ Drexel Autism Institute, Drexel University, Philadelphia, Pennsylvania, United States of America
| | - David R. Lynch
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Division of Neurology, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Clementina Mesaros
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Ian A. Blair
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania Philadelphia, Philadelphia, Pennsylvania, United States of America
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Guo L, Wang Q, Weng L, Hauser LA, Strawser CJ, Rocha AG, Dancis A, Mesaros C, Lynch DR, Blair IA. Liquid Chromatography-High Resolution Mass Spectrometry Analysis of Platelet Frataxin as a Protein Biomarker for the Rare Disease Friedreich's Ataxia. Anal Chem 2018; 90:2216-2223. [PMID: 29272104 PMCID: PMC5817373 DOI: 10.1021/acs.analchem.7b04590] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Friedreich's ataxia (FA) is an autosomal recessive disease caused by an intronic GAA triplet expansion in the FXN gene, leading to reduced expression of the mitochondrial protein frataxin. FA is estimated to affect 1 in 50 000 with a mean age of death in the fourth decade of life. There are no approved treatments for FA, although experimental approaches, which involve up-regulation or replacement of frataxin protein, are being tested. Frataxin is undetectable in serum or plasma, and whole blood cannot be used because it is present in long-lived erythrocytes. Therefore, an assay was developed for analyzing frataxin in platelets, which have a half-life of 10 days. The assay is based on stable isotope dilution immunopurification two-dimensional nano-ultra high performance liquid chromatography/parallel reaction monitoring/mass spectrometry. The lower limit of quantification was 0.078 pg frataxin/μg protein, and the assay had 100% sensitivity and specificity for discriminating between controls and FA cases. The mean levels of control and FA platelet frataxin were 9.4 ± 2.6 and 2.4 ± 0.6 pg/μg protein, respectively. The assay should make it possible to rigorously monitor the effects of therapeutic interventions on frataxin expression in this devastating disease.
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Affiliation(s)
- Lili Guo
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, Pennsylvania 19104, United States
| | - Qingqing Wang
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, Pennsylvania 19104, United States
| | - Liwei Weng
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Lauren A. Hauser
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, Pennsylvania 19104, United States
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, United States
- Departments of Pediatrics and Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Cassandra J. Strawser
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, Pennsylvania 19104, United States
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, United States
- Departments of Pediatrics and Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Agostinho G. Rocha
- Department of Medicine, Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Andrew Dancis
- Department of Medicine, Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Clementina Mesaros
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, Pennsylvania 19104, United States
| | - David R. Lynch
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, Pennsylvania 19104, United States
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, United States
- Departments of Pediatrics and Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Ian A. Blair
- Penn SRP Center and Center of Excellence in Environmental Toxicology Center, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Penn/CHOP Center of Excellence in Friedreich’s Ataxia, Philadelphia, Pennsylvania 19104, United States
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Qin HT, Li HQ, Liu F. Selective histone deacetylase small molecule inhibitors: recent progress and perspectives. Expert Opin Ther Pat 2016; 27:621-636. [PMID: 28033734 DOI: 10.1080/13543776.2017.1276565] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
INTRODUCTION Since the first pan-HDAC inhibitor SAHA was approved by U.S. FDA 10 years ago, HDACs including SIRT1-7 have received significant attention due to the fact that aberrant histone deacetylase activtiy has been implicated in a variety of human diseases, such as cancers, virus infection, and neurodegenerative diseases. During the past years, a considerable achievement of development of isoform- or class-selective HDAC inhibitors has been made, yielding many drug candidates for further clinical studies, which represents a state-of-the-art technology in the drug discovery arena. Areas covered: This review covers new patents and articles about isoform- or class-selective HDAC inhibitors during the last four years, as well as the therapeutic potential of these compounds. Expert opinion: HDACs represent one of the most promising therapeutic targets, particularly for tumor therapy though their roles in cancer are still blurry. From 2012 to present, along with the advances of structural biology and homology models, lots of isoform- or class-selective HDAC inhibitors, such as hydroxamic acids and benzamides with various capping groups were found, providing a promising way to circumvent drug toxicity and side-effect issues, as well as providing chemical probes for further better understanding of the biological process related to specific isoform.
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Affiliation(s)
- Hai-Tao Qin
- a Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases and Department of Medicinal Chemistry , College of Pharmaceutical Sciences, Soochow University , Suzhou , PR China
| | - Huan-Qiu Li
- b Department of Medicinal Chemistry , College of Pharmaceutical Sciences, Soochow University , Suzhou , PR China
| | - Feng Liu
- a Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases and Department of Medicinal Chemistry , College of Pharmaceutical Sciences, Soochow University , Suzhou , PR China
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Codazzi F, Hu A, Rai M, Donatello S, Salerno Scarzella F, Mangiameli E, Pelizzoni I, Grohovaz F, Pandolfo M. Friedreich ataxia-induced pluripotent stem cell-derived neurons show a cellular phenotype that is corrected by a benzamide HDAC inhibitor. Hum Mol Genet 2016; 25:4847-4855. [PMID: 28175303 DOI: 10.1093/hmg/ddw308] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/07/2016] [Accepted: 08/26/2016] [Indexed: 01/08/2023] Open
Abstract
We employed induced pluripotent stem cell (iPSC)-derived neurons obtained from Friedreich ataxia (FRDA) patients and healthy subjects, FRDA neurons and CT neurons, respectively, to unveil phenotypic alterations related to frataxin (FXN) deficiency and investigate if they can be reversed by treatments that upregulate FXN. FRDA and control iPSCs were equally capable of differentiating into a neuronal or astrocytic phenotype. FRDA neurons showed lower levels of iron–sulfur (Fe–S) and lipoic acid-containing proteins, higher labile iron pool (LIP), higher expression of mitochondrial superoxide dismutase (SOD2), increased reactive oxygen species (ROS) and lower reduced glutathione (GSH) levels, and enhanced sensitivity to oxidants compared with CT neurons, indicating deficient Fe–S cluster biogenesis, altered iron metabolism, and oxidative stress. Treatment with the benzamide HDAC inhibitor 109 significantly upregulated FXN expression and increased Fe–S and lipoic acid-containing protein levels, downregulated SOD2 levels, normalized LIP and ROS levels, and almost fully protected FRDA neurons from oxidative stress-mediated cell death. Our findings suggest that correction of FXN deficiency may not only stop disease progression, but also lead to clinical improvement by rescuing still surviving, but dysfunctional neurons.
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Affiliation(s)
- Franca Codazzi
- IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Vita-Salute San Raffaele University, Milan, Italy
| | - Amelié Hu
- Laboratoire de Neurologie Expérimentale, Université Libre de Bruxelles (ULB), 1070 Brussels, Belgium
| | - Myriam Rai
- Laboratoire de Neurologie Expérimentale, Université Libre de Bruxelles (ULB), 1070 Brussels, Belgium
| | - Simona Donatello
- Laboratoire de Neurologie Expérimentale, Université Libre de Bruxelles (ULB), 1070 Brussels, Belgium
| | | | | | | | - Fabio Grohovaz
- IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Vita-Salute San Raffaele University, Milan, Italy
| | - Massimo Pandolfo
- Laboratoire de Neurologie Expérimentale, Université Libre de Bruxelles (ULB), 1070 Brussels, Belgium
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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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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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Abrahao A, Pedroso JL, de Carvalho Aguiar PM, Barsottini OGP. Gene Expression Profile in Peripheral Blood Cells of Friedreich Ataxia Patients. CEREBELLUM (LONDON, ENGLAND) 2016; 15:306-13. [PMID: 26170003 DOI: 10.1007/s12311-015-0700-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Friedreich ataxia (FRDA) is the most common autosomal recessive ataxia characterized by a combination of neurological involvement, cardiomyopathy, and skeletal and glucose metabolism disturbances. FRDA is caused by mutations in FXN gene that results in reduction of mRNA and protein levels of frataxin. Previous microarray and real-time quantitative PCR (qPCR) studies showed that the downregulation of FXN is associated with a complex gene expression profile. However, these studies showed a wide variability in the subset of genes with altered expression among tissues and models. Genes differentially expressed in peripheral blood cells (PBC) could potentially help in the understanding of FRDA pathophysiology and also function as reliable disease biomarkers obtained from an easily accessible tissue, which could have implications in clinical practice. This study aimed to validate by qPCR the expression of 26 genes, revealed as differentially expressed by other studies, using peripheral blood cells (PBC) of 11 FRDA patients compared to 11 healthy controls. We found a robust downregulation of FXN, but no statistically significant differences were found between FRDA and controls for the remaining genes. Except for FXN, our study did not find a differential gene expression profile in PBC of FRDA patients and a reliable gene expression profile biomarker in a clinical relevant and noninvasive tissue remains unclear.
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Affiliation(s)
- Agessandro Abrahao
- Division of General Neurology and Ataxia Unit, Department of Neurology and Neurosurgery, Universidade Federal de São Paulo - UNIFESP, São Paulo, SP, Brazil
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
| | - Jose Luiz Pedroso
- Division of General Neurology and Ataxia Unit, Department of Neurology and Neurosurgery, Universidade Federal de São Paulo - UNIFESP, São Paulo, SP, Brazil
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
| | - Patricia Maria de Carvalho Aguiar
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil.
- Division of Movement Disorders, Department of Neurology and Neurosurgery, Universidade Federal de São Paulo - UNIFESP, Rua Pedro de Toledo 650, Vila Clementino, São Paulo, SP, 04039-002, Brazil.
| | - Orlando Graziani Povoas Barsottini
- Division of General Neurology and Ataxia Unit, Department of Neurology and Neurosurgery, Universidade Federal de São Paulo - UNIFESP, São Paulo, SP, Brazil
- Hospital Israelita Albert Einstein, São Paulo, SP, Brazil
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Stable isotopes and LC-MS for monitoring metabolic disturbances in Friedreich's ataxia platelets. Bioanalysis 2016; 7:1843-55. [PMID: 26295986 DOI: 10.4155/bio.15.118] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Friedreich's ataxia (FRDA) is an autosomal recessive disease with metabolic abnormalities that have been proposed to play an important role in the resulting neurodegeneration and cardiomyopathy. The inability to access the highly affected neuronal and cardiac tissues has hampered metabolic evaluation and biomarker development. METHODS Employment of a LC-MS-based method to determine whether platelets isolated from patients with FRDA exhibit differentiable metabolism compared with healthy controls. RESULTS Isotopologue analysis showed a marked decrease in glucose incorporation with a concomitant increase in palmitate-derived acyl-CoA thioesters in FRDA platelets compared with controls. CONCLUSION Our findings demonstrate that platelets can be used as a surrogate tissue for in vivo biomarker studies to monitor new therapeutic approaches for the treatment of FRDA.
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Lazaropoulos M, Dong Y, Clark E, Greeley NR, Seyer LA, Brigatti KW, Christie C, Perlman SL, Wilmot GR, Gomez CM, Mathews KD, Yoon G, Zesiewicz T, Hoyle C, Subramony SH, Brocht AF, Farmer JM, Wilson RB, Deutsch EC, Lynch DR. Frataxin levels in peripheral tissue in Friedreich ataxia. Ann Clin Transl Neurol 2015; 2:831-42. [PMID: 26339677 PMCID: PMC4554444 DOI: 10.1002/acn3.225] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 05/29/2015] [Accepted: 06/01/2015] [Indexed: 12/30/2022] Open
Abstract
Objective Friedreich ataxia (FRDA) is an autosomal recessive ataxia resulting from mutations in the frataxin gene (FXN). Such mutations, usually expanded guanine–adenine–adenine (GAA) repeats, give rise to decreased levels of frataxin protein in both affected and unaffected tissues. The goal was to understand the relationship of frataxin levels in peripheral tissues to disease status. Methods Frataxin levels were measured in buccal cells and blood, and analyzed in relation to disease features. Site-directed mutant frataxin was also transfected into human embryonic kidney cells to model results from specific point mutations. Results There was no evidence for change in frataxin levels over time with repeated measures analysis, although linear regression analysis of cross-sectional data predicted a small increase over decades. GAA repeat length predicted frataxin levels in both tissues, and frataxin levels themselves predicted neurological ratings (accounting for age). Compound heterozygous patients for a GAA expansion and a point mutation in FXN generally had lower levels of frataxin than those homozygous for the presence of two GAA repeat expansions, though levels varied dramatically between tissues in some compound heterozygotes for point mutations. The G130V mutation led to decreased levels of frataxin in vitro as well as in vivo, while the R165C mutation produced normal immunoreactive levels of frataxin both in vitro and in vivo. Start codon mutations led to low levels of frataxin in buccal cells but preserved immunoreactive frataxin levels in blood. Interpretation The present data show that peripheral frataxin levels reflect disease features in FRDA, but emphasize the need for interpretation of such levels in the context of specific mutations.
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Affiliation(s)
- Michael Lazaropoulos
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
| | - Yina Dong
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
| | - Elisia Clark
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
| | - Nathaniel R Greeley
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
| | - Lauren A Seyer
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
| | - Karlla W Brigatti
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
| | - Carlton Christie
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
| | - Susan L Perlman
- Department of Neurology, University of California Los Angeles Los Angeles, California
| | | | | | | | - Grace Yoon
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto Toronto, Ontario, Canada
| | | | - Chad Hoyle
- Department of Neurology, The Ohio State University Columbus, Ohio
| | - Sub H Subramony
- Department of Neurology, University of Florida Gainesville, Florida
| | - Alicia F Brocht
- Department of Neurology, University of Rochester Rochester, New York
| | - Jennifer M Farmer
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
| | - Robert B Wilson
- Department of Pathology and Lab Medicine, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
| | - Eric C Deutsch
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
| | - David R Lynch
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19104
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Abrahão A, Pedroso JL, Braga-Neto P, Bor-Seng-Shu E, de Carvalho Aguiar P, Barsottini OGP. Milestones in Friedreich ataxia: more than a century and still learning. Neurogenetics 2015; 16:151-60. [PMID: 25662948 DOI: 10.1007/s10048-015-0439-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 01/20/2015] [Indexed: 10/24/2022]
Abstract
Friedreich ataxia (FRDA) is the most common autosomal recessive ataxia worldwide. This review highlights the main clinical features, pathophysiological mechanisms, and therapeutic approaches for FRDA patients. The disease is characterized by a combination of neurological involvement (ataxia and neuropathy), cardiomyopathy, skeletal abnormalities, and glucose metabolism disturbances. FRDA is caused by expanded guanine-adenine-adenine (GAA) triplet repeats in the first intron of the frataxin gene (FXN), resulting in reduction of messenger RNA and protein levels of frataxin in different tissues. The molecular and metabolic disturbances, including iron accumulation, lead to pathological changes characterized by spinal cord and dorsal root ganglia atrophy, dentate nucleus atrophy without global cerebellar volume reduction, and hypertrophic cardiomyopathy. DNA analysis is the hallmark for the diagnosis of FRDA. There is no specific treatment to stop the disease progression in FRDA patients. However, a number of drugs are under investigation. Therapeutic approaches intend to improve mitochondrial functioning and to increase FXN expression.
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Affiliation(s)
- Agessandro Abrahão
- Division of General Neurology and Ataxia Unit, Department of Neurology and Neurosurgery, Universidade Federal de São Paulo, Rua Pedro de Toledo 650 Vila Clementino, São Paulo, 04039-002, SP, Brazil,
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23
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De Michele G, Filla A. Friedreich ataxia today—preparing for the final battle. Nat Rev Neurol 2015; 11:188-90. [DOI: 10.1038/nrneurol.2015.33] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Thaler F, Mercurio C. Towards selective inhibition of histone deacetylase isoforms: what has been achieved, where we are and what will be next. ChemMedChem 2014; 9:523-6. [PMID: 24730063 DOI: 10.1002/cmdc.201300413] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Histone deacetylases (HDACs) are widely studied targets for the treatment of cancer and other diseases. Up to now, over twenty HDAC inhibitors have entered clinical studies and two of them have already reached the market, namely the hydroxamic acid derivative SAHA (vorinostat, Zolinza) and the cyclic depsipeptide FK228 (romidepsin, Istodax) that have been approved for the treatment of cutaneous T-cell lymphoma (CTCL). A common aspect of the first HDAC inhibitors is the absence of any particular selectivity towards specific isozymes. Some of molecules resulted to be “pan”-HDAC inhibitors, while others are class I selective. In the meantime, the knowledge of HDAC biology has continuously progressed. Key advances in the structural biology of various isozymes, reliable molecular homology models as well as suitable biological assays have provided new tools for drug discovery activities. This Minireview aims at surveying these recent developments as well as the design, synthesis and biological characterization of isoform-selective derivatives.
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25
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Soragni E, Miao W, Iudicello M, Jacoby D, De Mercanti S, Clerico M, Longo F, Piga A, Ku S, Campau E, Du J, Penalver P, Rai M, Madara JC, Nazor K, O'Connor M, Maximov A, Loring JF, Pandolfo M, Durelli L, Gottesfeld JM, Rusche JR. Epigenetic therapy for Friedreich ataxia. Ann Neurol 2014; 76:489-508. [PMID: 25159818 PMCID: PMC4361037 DOI: 10.1002/ana.24260] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 12/12/2022]
Abstract
OBJECTIVE To investigate whether a histone deacetylase inhibitor (HDACi) would be effective in an in vitro model for the neurodegenerative disease Friedreich ataxia (FRDA) and to evaluate safety and surrogate markers of efficacy in a phase I clinical trial in patients. METHODS We used a human FRDA neuronal cell model, derived from patient induced pluripotent stem cells, to determine the efficacy of a 2-aminobenzamide HDACi (109) as a modulator of FXN gene expression and chromatin histone modifications. FRDA patients were dosed in 4 cohorts, ranging from 30mg/day to 240mg/day of the formulated drug product of HDACi 109, RG2833. Patients were monitored for adverse effects as well as for increases in FXN mRNA, frataxin protein, and chromatin modification in blood cells. RESULTS In the neuronal cell model, HDACi 109/RG2833 increases FXN mRNA levels and frataxin protein, with concomitant changes in the epigenetic state of the gene. Chromatin signatures indicate that histone H3 lysine 9 is a key residue for gene silencing through methylation and reactivation through acetylation, mediated by the HDACi. Drug treatment in FRDA patients demonstrated increased FXN mRNA and H3 lysine 9 acetylation in peripheral blood mononuclear cells. No safety issues were encountered. INTERPRETATION Drug exposure inducing epigenetic changes in neurons in vitro is comparable to the exposure required in patients to see epigenetic changes in circulating lymphoid cells and increases in gene expression. These findings provide a proof of concept for the development of an epigenetic therapy for this fatal neurological disease.
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Affiliation(s)
- Elisabetta Soragni
- Departments of Cell and Molecular Biology, Scripps Research Institute, La Jolla, CA
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26
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Chutake YK, Lam C, Costello WN, Anderson M, Bidichandani SI. Epigenetic promoter silencing in Friedreich ataxia is dependent on repeat length. Ann Neurol 2014; 76:522-8. [PMID: 25112975 PMCID: PMC4191993 DOI: 10.1002/ana.24249] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/05/2014] [Accepted: 07/21/2014] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Friedreich ataxia (FRDA) is caused by an expanded GAA triplet-repeat (GAA-TR) mutation in the FXN gene. Patients are typically homozygous for expanded alleles containing 100 to 1,300 triplets, and phenotypic severity is significantly correlated with the length of the shorter of the 2 expanded alleles. Patients have a severe deficiency of FXN transcript, which is predominantly caused by epigenetic silencing of the FXN promoter. We sought to determine whether the severity of FXN promoter silencing is related to the length of the expanded GAA-TR mutation in FRDA. METHODS Patient-derived lymphoblastoid cell lines bearing a range of expanded alleles (200-1,122 triplets) were evaluated for FXN transcript levels by quantitative reverse transcriptase polymerase chain reaction. FXN promoter function was directly measured by quantitative analysis of transcriptional initiation via metabolic labeling of newly synthesized transcripts in living cells. RESULTS FXN transcriptional deficiency was significantly correlated with the length of the shorter of the 2 expanded alleles, which was noted both upstream (R(2) = 0.84, p = 0.014) and downstream (R(2) = 0.89, p = 0.002) of the expanded GAA-TR mutation, suggesting that FXN promoter silencing in FRDA is related to repeat length. A bilinear regression model revealed that length dependence was strongest when the shorter of the 2 expanded alleles contained <400 triplets. Direct measurement of FXN promoter activity in patients with expanded alleles containing <400 versus >400 triplets in the shorter of the 2 expanded alleles revealed a significantly greater deficiency in individuals with longer GAA-TR alleles (p < 0.05). INTERPRETATION FXN promoter silencing in FRDA is dependent on the length of the expanded GAA-TR mutation.
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Affiliation(s)
- Yogesh K. Chutake
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104
| | - Christina Lam
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104
| | - Whitney N. Costello
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104
| | - Michael Anderson
- Department of Biostatistics & Epidemiology, University of Oklahoma College of Public Health, Oklahoma City, OK 73104
| | - Sanjay I. Bidichandani
- Department of Pediatrics, University of Oklahoma College of Medicine, Oklahoma City, OK 73104
- Department of Biochemistry & Molecular Biology, University of Oklahoma College of Medicine, Oklahoma City, OK 73104
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27
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Wang Y, Wang Y, Marcus S, Busenlehner LS. The role of frataxin in fission yeast iron metabolism: implications for Friedreich's ataxia. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1840:3022-33. [PMID: 24997422 DOI: 10.1016/j.bbagen.2014.06.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 06/25/2014] [Accepted: 06/26/2014] [Indexed: 01/01/2023]
Abstract
BACKGROUND The neurodegenerative disease Friedreich's ataxia is the result of frataxin deficiency. Frataxin is a mitochondrial protein involved in iron-sulfur cluster (Fe-S) cofactor biogenesis, but its functional role in this pathway is debated. This is due to the interconnectivity of iron metabolic and oxidative stress response pathways that make distinguishing primary effects of frataxin deficiency challenging. Since Fe-S cluster assembly is conserved, frataxin overexpression phenotypes in a simple eukaryotic organism will provide additional insight into frataxin function. METHODS The Schizosaccharomyces pombe frataxin homologue (fxn1) was overexpressed from a plasmid under a thiamine repressible promoter. The S. pombe transformants were characterized at several expression strengths for cellular growth, mitochondrial organization, iron levels, oxidative stress, and activities of Fe-S cluster containing enzymes. RESULTS Observed phenotypes were dependent on the amount of Fxn1 overexpression. High Fxn1 overexpression severely inhibited S. pombe growth, impaired mitochondrial membrane integrity and cellular respiration, and led to Fxn1 aggregation. Cellular iron accumulation was observed at moderate Fxn1 overexpression but was most pronounced at high levels of Fxn1. All levels of Fxn1 overexpression up-regulated oxidative stress defense and mitochondrial Fe-S cluster containing enzyme activities. CONCLUSIONS Despite the presence of oxidative stress and accumulated iron, activation of Fe-S cluster enzymes was common to all levels of Fxn1 overexpression; therefore, Fxn1 may regulate the efficiency of Fe-S cluster biogenesis in S. pombe. GENERAL SIGNIFICANCE We provide evidence that suggests that dysregulated Fe-S cluster biogenesis is a primary effect of both frataxin overexpression and deficiency as in Friedreich's ataxia.
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Affiliation(s)
- Yu Wang
- Department of Chemistry, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Yiwei Wang
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - S Marcus
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA.
| | - L S Busenlehner
- Department of Chemistry, The University of Alabama, Tuscaloosa, AL 35487, USA.
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28
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Lynch DR, Seyer L. Friedreich ataxia: new findings, new challenges. Ann Neurol 2014; 76:487-8. [PMID: 25159691 DOI: 10.1002/ana.24259] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/25/2014] [Accepted: 08/25/2014] [Indexed: 11/11/2022]
Affiliation(s)
- David R Lynch
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, and Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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29
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Deutsch EC, Oglesbee D, Greeley NR, Lynch DR. Usefulness of frataxin immunoassays for the diagnosis of Friedreich ataxia. J Neurol Neurosurg Psychiatry 2014; 85:994-1002. [PMID: 24463479 DOI: 10.1136/jnnp-2013-306788] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Friedreich ataxia (FRDA) is a neurodegenerative disease caused by mutations in the frataxin (FXN) gene, resulting in reduced expression of the mitochondrial protein frataxin. Improved understanding of the pathophysiology of the disease has led to a growing need for informative biomarkers to assess disease progression and response to therapeutic intervention. OBJECTIVE To evaluate the performance of frataxin measurements as a diagnostic tool using two different immunoassays. METHODS Clinical and demographic information was provided through an ongoing longitudinal natural history study on FRDA. Frataxin protein levels from multiple cell types in controls, carriers and FRDA patients were measured and compared using a lateral flow immunoassay and a Luminex xMAP-based immunoassay. Receiver operating characteristic curve analyses were then performed to evaluate the sensitivity, specificity, and positive and negative predictive values for each immunoassay. RESULTS For whole blood and buccal cells, analysing FRDA patients and carriers together in a cohort resulted in higher sensitivities and positive predictive values compared with analyzing controls and carriers together, with similar results between each tissue type. We then compared the usefulness of a lateral flow immunoassay with a multianalyte Luminex xMAP-based immunoassay, and showed that both assays demonstrate high positive predictive values with low rates of false negatives and false positives. CONCLUSIONS Frataxin measurements from peripheral tissues can be used to identify FRDA patients and carriers. While multiple cell types and assays may be useful for diagnostic purposes, each assay and cell type used has its advantages and disadvantages depending on study design and scope.
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Affiliation(s)
- Eric C Deutsch
- Department of Pharmacology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Devin Oglesbee
- Department of Laboratory Medicine and Pathology, Department of Molecular Genetics, Mayo Clinic School of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Nathaniel R Greeley
- Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - David R Lynch
- Department of Pharmacology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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Evans-Galea MV, Pébay A, Dottori M, Corben LA, Ong SH, Lockhart PJ, Delatycki MB. Cell and gene therapy for Friedreich ataxia: progress to date. Hum Gene Ther 2014; 25:684-93. [PMID: 24749505 DOI: 10.1089/hum.2013.180] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Neurodegenerative disorders such as Friedreich ataxia (FRDA) present significant challenges in developing effective therapeutic intervention. Current treatments aim to manage symptoms and thus improve quality of life, but none can cure, nor are proven to slow, the neurodegeneration inherent to this disease. The primary clinical features of FRDA include progressive ataxia and shortened life span, with complications of cardiomyopathy being the major cause of death. FRDA is most commonly caused by an expanded GAA trinucleotide repeat in the first intron of FXN that leads to reduced levels of frataxin, a mitochondrial protein important for iron metabolism. The GAA expansion in FRDA does not alter the coding sequence of FXN. It results in reduced production of structurally normal frataxin, and hence any increase in protein level is expected to be therapeutically beneficial. Recently, there has been increased interest in developing novel therapeutic applications like cell and/or gene therapies, and these cutting-edge applications could provide effective treatment options for FRDA. Importantly, since individuals with FRDA produce frataxin at low levels, increased expression should not elicit an immune response. Here we review the advances to date and highlight the future potential for cell and gene therapy to treat this debilitating disease.
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Affiliation(s)
- Marguerite V Evans-Galea
- 1 Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute , Parkville Victoria 3052, Australia
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Chutake YK, Costello WN, Lam C, Bidichandani SI. Altered nucleosome positioning at the transcription start site and deficient transcriptional initiation in Friedreich ataxia. J Biol Chem 2014; 289:15194-202. [PMID: 24737321 PMCID: PMC4140879 DOI: 10.1074/jbc.m114.566414] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 04/14/2014] [Indexed: 11/06/2022] Open
Abstract
Most individuals with Friedreich ataxia (FRDA) are homozygous for an expanded GAA triplet repeat (GAA-TR) mutation in intron 1 of the FXN gene, which results in deficiency of FXN transcript. Consistent with the expanded GAA-TR sequence as a cause of variegated gene silencing, evidence for heterochromatin has been detected in intron 1 in the immediate vicinity of the expanded GAA-TR mutation in FRDA. Transcriptional deficiency in FRDA is thought to result from deficient elongation through the expanded GAA-TR sequence because of repeat-proximal heterochromatin and abnormal DNA structures adopted by the expanded repeat. There is also evidence for deficient transcriptional initiation in FRDA, but its relationship to the expanded GAA-TR mutation remains unclear. We show that repressive chromatin extends from the expanded GAA-TR in intron 1 to the upstream regions of the FXN gene, involving the FXN transcriptional start site. Using a chromatin accessibility assay and a high-resolution nucleosome occupancy assay, we found that the major FXN transcriptional start site, which is normally in a nucleosome-depleted region, is rendered inaccessible by altered nucleosome positioning in FRDA. Consistent with the altered epigenetic landscape the FXN gene promoter, a typical CpG island promoter, was found to be in a transcriptionally non-permissive state in FRDA. Both metabolic labeling of nascent transcripts and an unbiased whole transcriptome analysis revealed a severe deficiency of transcriptional initiation in FRDA. Deficient transcriptional initiation, and not elongation, is the major cause of FXN transcriptional deficiency in FRDA, and it is related to the spread of repressive chromatin from the expanded GAA-TR mutation.
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Affiliation(s)
| | | | | | - Sanjay I Bidichandani
- From the Departments of Pediatrics and Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
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