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Kalef-Ezra E, Edzeamey FJ, Valle A, Khonsari H, Kleine P, Oggianu C, Al-Mahdawi S, Pook MA, Anjomani Virmouni S. A new FRDA mouse model [ Fxn null:YG8s(GAA) > 800] with more than 800 GAA repeats. Front Neurosci 2023; 17:930422. [PMID: 36777637 PMCID: PMC9909538 DOI: 10.3389/fnins.2023.930422] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 01/04/2023] [Indexed: 01/27/2023] Open
Abstract
Introduction Friedreich's ataxia (FRDA) is an inherited recessive neurodegenerative disorder caused by a homozygous guanine-adenine-adenine (GAA) repeat expansion within intron 1 of the FXN gene, which encodes the essential mitochondrial protein frataxin. There is still no effective therapy for FRDA, therefore the development of optimal cell and animal models of the disease is one of the priorities for preclinical therapeutic testing. Methods We obtained the latest FRDA humanized mouse model that was generated on the basis of our previous YG8sR, by Jackson laboratory [YG8JR, Fxn null:YG8s(GAA) > 800]. We characterized the behavioral, cellular, molecular and epigenetics properties of the YG8JR model, which has the largest GAA repeat sizes compared to all the current FRDA mouse models. Results We found statistically significant behavioral deficits, together with reduced levels of frataxin mRNA and protein, and aconitase activity in YG8JR mice compared with control Y47JR mice. YG8JR mice exhibit intergenerational GAA repeat instability by the analysis of parent and offspring tissue samples. Somatic GAA repeat instability was also detected in individual brain and cerebellum tissue samples. In addition, increased DNA methylation of CpG U13 was identified in FXN GAA repeat region in the brain, cerebellum, and heart tissues. Furthermore, we show decreased histone H3K9 acetylation and increased H3K9 methylation of YG8JR cerebellum tissues within the FXN gene, upstream and downstream of the GAA repeat region compared to Y47JR controls. Discussion These studies provide a detailed characterization of the GAA repeat expansion-based YG8JR transgenic mouse models that will help investigations of FRDA disease mechanisms and therapy.
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Affiliation(s)
- Ester Kalef-Ezra
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Fred Jonathan Edzeamey
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Adamo Valle
- Energy Metabolism and Nutrition, Research Institute of Health Sciences (IUNICS), University of Balearic Islands, Palma, Spain,Health Research Institute of Balearic Islands (IdISBa), Palma, Spain,Biomedical Research Networking Center for Physiopathology of Obesity and Nutrition (CIBERobn CB06/03/0043), Instituto de Salud Carlos III, Madrid, Spain
| | - Hassan Khonsari
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Paula Kleine
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Carlo Oggianu
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Sahar Al-Mahdawi
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Mark A. Pook
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Sara Anjomani Virmouni
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, Brunel University London, Uxbridge, United Kingdom,*Correspondence: Sara Anjomani Virmouni,
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Zhang L, Fang Y, Zhao X, Zheng Y, Ma Y, Li S, Huang Z, Li L. BRUCE silencing leads to axonal dystrophy by repressing autophagosome-lysosome fusion in Alzheimer's disease. Transl Psychiatry 2021; 11:421. [PMID: 34354038 PMCID: PMC8342531 DOI: 10.1038/s41398-021-01427-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/24/2021] [Accepted: 05/06/2021] [Indexed: 11/10/2022] Open
Abstract
Axonal dystrophy is a swollen and tortuous neuronal process that contributes to synaptic alterations occurring in Alzheimer's disease (AD). Previous study identified that brain-derived neurotrophic factor (BDNF) binds to tropomyosin-related kinase B (TrkB) at the axon terminal and then the signal is propagated along the axon to the cell body and affects neuronal function through retrograde transport. Therefore, this study was designed to identify a microRNA (miRNA) that alters related components of the transport machinery to affect BDNF retrograde signaling deficits in AD. Hippocampus tissues were isolated from APP/PS1 transgenic (AD-model) mice and C57BL/6J wild-type mice and subject to nicotinamide adenine dinucleotide phosphate and immunohistochemical staining. Autophagosome-lysosome fusion and nuclear translocation of BDNF was detected using immunofluorescence in HT22 cells. The interaction among miR-204, BIR repeat containing ubiquitin-conjugating enzyme (BRUCE) and Syntaxin 17 (STX17) was investigated using dual luciferase reporter gene assay and co-immunoprecipitation assay. The expression of relevant genes and proteins were determined by RT-qPCR and Western blot analysis. Knockdown of STX17 or BRUCE inhibited autophagosome-lysosome fusion and impacted axon growth in HT22 cells. STX17 immunoprecipitating with BRUCE and co-localization of them demonstrated BRUCE interacted with STX17. BRUCE was the target of miR-204, and partial loss of miR-204 by inhibitor promoted autophagosome-lysosome fusion to prevent axon dystrophy and accumulated BDNF nuclear translocation to rescue BDNF/TrkB signaling deficits in HT22 cells. The overall results demonstrated that inhibition of miR-204 prevents axonal dystrophy by blocking BRUCE interaction with STX17, which unraveled potential novel therapeutic targets for delaying AD.
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Affiliation(s)
- Lu Zhang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, P.R. China.
| | - Yu Fang
- grid.412633.1ICU, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 P.R. China
| | - Xinyu Zhao
- grid.412633.1Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 P.R. China
| | - Yake Zheng
- grid.412633.1Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 P.R. China
| | - Yunqing Ma
- grid.412633.1Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 P.R. China
| | - Shuang Li
- grid.412633.1Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 P.R. China
| | - Zhi Huang
- grid.412633.1Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 P.R. China
| | - Lihao Li
- grid.412633.1Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052 P.R. China
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Rodríguez-Pascau L, Britti E, Calap-Quintana P, Dong YN, Vergara C, Delaspre F, Medina-Carbonero M, Tamarit J, Pallardó FV, Gonzalez-Cabo P, Ros J, Lynch DR, Martinell M, Pizcueta P. PPAR gamma agonist leriglitazone improves frataxin-loss impairments in cellular and animal models of Friedreich Ataxia. Neurobiol Dis 2021; 148:105162. [PMID: 33171227 DOI: 10.1016/j.nbd.2020.105162] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/14/2020] [Accepted: 11/03/2020] [Indexed: 01/08/2023] Open
Abstract
Friedreich ataxia (FRDA), the most common autosomal recessive ataxia, is characterized by degeneration of the large sensory neurons and spinocerebellar tracts, cardiomyopathy, and increased incidence in diabetes. The underlying pathophysiological mechanism of FRDA, driven by a significantly decreased expression of frataxin (FXN), involves increased oxidative stress, reduced activity of enzymes containing iron‑sulfur clusters (ISC), defective energy production, calcium dyshomeostasis, and impaired mitochondrial biogenesis, leading to mitochondrial dysfunction. The peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcriptional factor playing a key role in mitochondrial function and biogenesis, fatty acid storage, energy metabolism, and antioxidant defence. It has been previously shown that the PPARγ/PPARγ coactivator 1 alpha (PGC-1α) pathway is dysregulated when there is frataxin deficiency, thus contributing to FRDA pathogenesis and supporting the PPARγ pathway as a potential therapeutic target. Here we assess whether MIN-102 (INN: leriglitazone), a novel brain penetrant and orally bioavailable PPARγ agonist with an improved profile for central nervous system (CNS) diseases, rescues phenotypic features in cellular and animal models of FRDA. In frataxin-deficient dorsal root ganglia (DRG) neurons, leriglitazone increased frataxin protein levels, reduced neurite degeneration and α-fodrin cleavage mediated by calpain and caspase 3, and increased survival. Leriglitazone also restored mitochondrial membrane potential and partially reversed decreased levels of mitochondrial Na+/Ca2+ exchanger (NCLX), resulting in an improvement of mitochondrial functions and calcium homeostasis. In frataxin-deficient primary neonatal cardiomyocytes, leriglitazone prevented lipid droplet accumulation without increases in frataxin levels. Furthermore, leriglitazone improved motor function deficit in YG8sR mice, a FRDA mouse model. In agreement with the role of PPARγ in mitochondrial biogenesis, leriglitazone significantly increased markers of mitochondrial biogenesis in FRDA patient cells. Overall, these results suggest that targeting the PPARγ pathway by leriglitazone may provide an efficacious therapy for FRDA increasing the mitochondrial function and biogenesis that could increase frataxin levels in compromised frataxin-deficient DRG neurons. Alternately, leriglitazone improved the energy metabolism by increasing the fatty acid β-oxidation in frataxin-deficient cardiomyocytes without elevation of frataxin levels. This could be linked to a lack of significant mitochondrial biogenesis and cardiac hypertrophy. The results reinforced the different tissue requirement in FRDA and the pleiotropic effects of leriglitazone that could be a promising therapy for FRDA.
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Affiliation(s)
| | - Elena Britti
- Departament de Ciències Mèdiques Bàsiques, IRBLleida. Universitat de Lleida, Lleida 25198, Spain
| | - Pablo Calap-Quintana
- Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia-INCLIVA, Valencia 46010, Spain; CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
| | - Yi Na Dong
- Department of Pediatrics and Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | | | - Fabien Delaspre
- Departament de Ciències Mèdiques Bàsiques, IRBLleida. Universitat de Lleida, Lleida 25198, Spain
| | - Marta Medina-Carbonero
- Departament de Ciències Mèdiques Bàsiques, IRBLleida. Universitat de Lleida, Lleida 25198, Spain
| | - Jordi Tamarit
- Departament de Ciències Mèdiques Bàsiques, IRBLleida. Universitat de Lleida, Lleida 25198, Spain
| | - Federico V Pallardó
- Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia-INCLIVA, Valencia 46010, Spain; CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
| | - Pilar Gonzalez-Cabo
- Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia-INCLIVA, Valencia 46010, Spain; CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
| | - Joaquim Ros
- Departament de Ciències Mèdiques Bàsiques, IRBLleida. Universitat de Lleida, Lleida 25198, Spain
| | - David R Lynch
- Department of Pediatrics and Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Marc Martinell
- Minoryx Therapeutics SL., Mataró 08302, Barcelona, Spain; Minoryx Therapeutics BE., Gosselies 6041, Charleroi, Belgium
| | - Pilar Pizcueta
- Minoryx Therapeutics SL., Mataró 08302, Barcelona, Spain.
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Rodríguez LR, Calap-Quintana P, Lapeña-Luzón T, Pallardó FV, Schneuwly S, Navarro JA, Gonzalez-Cabo P. Oxidative stress modulates rearrangement of endoplasmic reticulum-mitochondria contacts and calcium dysregulation in a Friedreich's ataxia model. Redox Biol 2020; 37:101762. [PMID: 33128998 PMCID: PMC7585950 DOI: 10.1016/j.redox.2020.101762] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 10/07/2020] [Accepted: 10/12/2020] [Indexed: 12/13/2022] Open
Abstract
Friedreich ataxia (FRDA) is a neurodegenerative disorder characterized by neuromuscular and neurological manifestations. It is caused by mutations in the FXN gene, which results in loss of the mitochondrial protein frataxin. Endoplasmic Reticulum-mitochondria associated membranes (MAMs) are inter-organelle structures involved in the regulation of essential cellular processes, including lipid metabolism and calcium signaling. In the present study, we have analyzed in both, unicellular and multicellular models of FRDA, calcium management and integrity of MAMs. We observed that function of MAMs is compromised in our cellular model of FRDA, which was improved upon treatment with antioxidants. In agreement, promoting mitochondrial calcium uptake was sufficient to restore several defects caused by frataxin deficiency in Drosophila Melanogaster. Remarkably, our findings describe for the first time frataxin as a member of the protein network of MAMs, where interacts with two of the main proteins implicated in endoplasmic reticulum-mitochondria communication. These results suggest a new role of frataxin, indicate that FRDA goes beyond mitochondrial defects and highlight MAMs as novel therapeutic candidates to improve patient's conditions.
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Affiliation(s)
- Laura R Rodríguez
- Department of Physiology, Faculty of Medicine and Dentistry. University of Valencia-INCLIVA, Valencia, 46010, Spain; Associated Unit for Rare Diseases INCLIVA-CIPF, Valencia, Spain
| | - Pablo Calap-Quintana
- Department of Physiology, Faculty of Medicine and Dentistry. University of Valencia-INCLIVA, Valencia, 46010, Spain; Associated Unit for Rare Diseases INCLIVA-CIPF, Valencia, Spain; CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
| | - Tamara Lapeña-Luzón
- Department of Physiology, Faculty of Medicine and Dentistry. University of Valencia-INCLIVA, Valencia, 46010, Spain; Associated Unit for Rare Diseases INCLIVA-CIPF, Valencia, Spain; CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
| | - Federico V Pallardó
- Department of Physiology, Faculty of Medicine and Dentistry. University of Valencia-INCLIVA, Valencia, 46010, Spain; Associated Unit for Rare Diseases INCLIVA-CIPF, Valencia, Spain; CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
| | - Stephan Schneuwly
- Institute of Zoology, Universitaetsstrasse 31, University of Regensburg, 93040, Regensburg, Germany
| | - Juan A Navarro
- Institute of Zoology, Universitaetsstrasse 31, University of Regensburg, 93040, Regensburg, Germany; INCLIVA Biomedial Research Institute, Valencia, Spain
| | - Pilar Gonzalez-Cabo
- Department of Physiology, Faculty of Medicine and Dentistry. University of Valencia-INCLIVA, Valencia, 46010, Spain; Associated Unit for Rare Diseases INCLIVA-CIPF, Valencia, Spain; CIBER de Enfermedades Raras (CIBERER), Valencia, Spain.
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5
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Weng L, Laboureur L, Wang Q, Guo L, Xu P, Gottlieb L, Lynch DR, Mesaros C, Blair IA. Extra-mitochondrial mouse frataxin and its implications for mouse models of Friedreich's ataxia. Sci Rep 2020; 10:15788. [PMID: 32978498 PMCID: PMC7519113 DOI: 10.1038/s41598-020-72884-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 08/28/2020] [Indexed: 01/04/2023] Open
Abstract
Mature frataxin is essential for the assembly of iron-sulfur cluster proteins including a number of mitochondrial enzymes. Reduced levels of mature frataxin (81-20) in human subjects caused by the genetic disease Friedreich's ataxia results in decreased mitochondrial function, neurodegeneration, and cardiomyopathy. Numerous studies of mitochondrial dysfunction have been conducted using mouse models of frataxin deficiency. However, mouse frataxin that is reduced in these models, is assumed to be mature frataxin (78-207) by analogy with human mature frataxin (81-210). Using immunoaffinity purification coupled with liquid chromatography-high resolution tandem mass spectrometry, we have discovered that mature frataxin in mouse heart (77%), brain (86%), and liver (47%) is predominantly a 129-amino acid truncated mature frataxin (79-207) in which the N-terminal lysine residue has been lost. Mature mouse frataxin (78-207) only contributes 7-15% to the total frataxin protein present in mouse tissues. We have also found that truncated mature frataxin (79-207) is present primarily in the cytosol of mouse liver; whereas, frataxin (78-207) is primarily present in the mitochondria. These findings, which provide support for the role of extra-mitochondrial frataxin in the etiology of Friedreich's ataxia, also have important implications for studies of mitochondrial dysfunction conducted in mouse models of frataxin deficiency.
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Affiliation(s)
- Liwei Weng
- Penn Medicine/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Laurent Laboureur
- Penn Medicine/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Qingqing Wang
- Penn Medicine/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Lili Guo
- Penn Medicine/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Peining Xu
- Penn Medicine/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Leah Gottlieb
- Penn Medicine/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - David R Lynch
- Penn Medicine/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Departments of Pediatrics and Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Clementina Mesaros
- Penn Medicine/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ian A Blair
- Penn Medicine/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Muñoz-Lasso DC, Mollá B, Calap-Quintana P, García-Giménez JL, Pallardo FV, Palau F, Gonzalez-Cabo P. Cofilin dysregulation alters actin turnover in frataxin-deficient neurons. Sci Rep 2020; 10:5207. [PMID: 32251310 PMCID: PMC7090085 DOI: 10.1038/s41598-020-62050-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 03/04/2020] [Indexed: 01/04/2023] Open
Abstract
Abnormalities in actin cytoskeleton have been linked to Friedreich's ataxia (FRDA), an inherited peripheral neuropathy characterised by an early loss of neurons in dorsal root ganglia (DRG) among other clinical symptoms. Despite all efforts to date, we still do not fully understand the molecular events that contribute to the lack of sensory neurons in FRDA. We studied the adult neuronal growth cone (GC) at the cellular and molecular level to decipher the connection between frataxin and actin cytoskeleton in DRG neurons of the well-characterised YG8R Friedreich's ataxia mouse model. Immunofluorescence studies in primary cultures of DRG from YG8R mice showed neurons with fewer and smaller GCs than controls, associated with an inhibition of neurite growth. In frataxin-deficient neurons, we also observed an increase in the filamentous (F)-actin/monomeric (G)-actin ratio (F/G-actin ratio) in axons and GCs linked to dysregulation of two crucial modulators of filamentous actin turnover, cofilin-1 and the actin-related protein (ARP) 2/3 complex. We show how the activation of cofilin is due to the increase in chronophin (CIN), a cofilin-activating phosphatase. Thus cofilin emerges, for the first time, as a link between frataxin deficiency and actin cytoskeleton alterations.
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Affiliation(s)
- Diana C Muñoz-Lasso
- CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
- Department of Physiology, Faculty of Medicine and Dentistry. University of Valencia-INCLIVA, Valencia, 46010, Spain
- Associated Unit for Rare Diseases INCLIVA-CIPF, Valencia, Spain
| | - Belén Mollá
- CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
- Instituto de Biomedicina de Valencia (IBV), CSIC, Valencia, 46010, Spain
| | - Pablo Calap-Quintana
- CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
- Department of Physiology, Faculty of Medicine and Dentistry. University of Valencia-INCLIVA, Valencia, 46010, Spain
- Associated Unit for Rare Diseases INCLIVA-CIPF, Valencia, Spain
| | - José Luis García-Giménez
- CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
- Department of Physiology, Faculty of Medicine and Dentistry. University of Valencia-INCLIVA, Valencia, 46010, Spain
- Associated Unit for Rare Diseases INCLIVA-CIPF, Valencia, Spain
| | - Federico V Pallardo
- CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
- Department of Physiology, Faculty of Medicine and Dentistry. University of Valencia-INCLIVA, Valencia, 46010, Spain
- Associated Unit for Rare Diseases INCLIVA-CIPF, Valencia, Spain
| | - Francesc Palau
- CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
- Institut de Recerca Sant Joan de Déu and Department of Genetic & Molecular Medicine and IPER, Hospital Sant Joan de Déu, Barcelona, 08950, Spain
- Hospital Clínic and Division of Pediatrics, University of Barcelona School of Medicine and Health Sciences, Barcelona, Spain
| | - Pilar Gonzalez-Cabo
- CIBER de Enfermedades Raras (CIBERER), Valencia, Spain.
- Department of Physiology, Faculty of Medicine and Dentistry. University of Valencia-INCLIVA, Valencia, 46010, Spain.
- Associated Unit for Rare Diseases INCLIVA-CIPF, Valencia, Spain.
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Stepanova A, Magrané J. Mitochondrial dysfunction in neurons in Friedreich's ataxia. Mol Cell Neurosci 2020; 102:103419. [PMID: 31770591 DOI: 10.1016/j.mcn.2019.103419] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 11/05/2019] [Accepted: 11/08/2019] [Indexed: 12/20/2022] Open
Abstract
Friedreich's ataxia is a multisystemic genetic disorder within the family of mitochondrial diseases that is characterized by reduced levels of the essential mitochondrial protein frataxin. Based on clinical evidence, the peripheral nervous system is affected early, neuronal dysfunction progresses towards the central nervous system, and other organs (such as heart and pancreas) are affected later. However, little attention has been given to the specific aspects of mitochondria function altered by frataxin depletion in the nervous system. For years, commonly accepted views on mitochondria dysfunction in Friedreich's ataxia stemmed from studies using non-neuronal systems and may not apply to neurons, which have their own bioenergetic needs and present a unique, extensive neurite network. Moreover, the basis of the selective neuronal vulnerability, which primarily affects large sensory neurons in the dorsal root ganglia, large principal neurons in the dentate nuclei of the cerebellum, and pyramidal neurons in the cerebral cortex, remains elusive. In order to identify potential misbeliefs in the field and highlight controversies, we reviewed current knowledge on frataxin expression in different tissues, discussed the molecular function of frataxin, and the consequences of its deficiency for mitochondria structural and functional properties, with a focus on the nervous system.
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Affiliation(s)
- Anna Stepanova
- Department of Pediatrics, Columbia University Medical Center, New York, NY, United States of America.
| | - Jordi Magrané
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, United States of America.
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Gottesfeld JM. Molecular Mechanisms and Therapeutics for the GAA·TTC Expansion Disease Friedreich Ataxia. Neurotherapeutics 2019; 16:1032-1049. [PMID: 31317428 PMCID: PMC6985418 DOI: 10.1007/s13311-019-00764-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Friedreich ataxia (FRDA), the most common inherited ataxia, is caused by transcriptional silencing of the nuclear FXN gene, encoding the essential mitochondrial protein frataxin. Currently, there is no approved therapy for this fatal disorder. Gene silencing in FRDA is due to hyperexpansion of the triplet repeat sequence GAA·TTC in the first intron of the FXN gene, which results in chromatin histone modifications consistent with heterochromatin formation. Frataxin is involved in mitochondrial iron homeostasis and the assembly and transfer of iron-sulfur clusters to various mitochondrial enzymes and components of the electron transport chain. Frataxin insufficiency leads to progressive spinocerebellar neurodegeneration, causing symptoms of gait and limb ataxia, slurred speech, muscle weakness, sensory loss, and cardiomyopathy in many patients, resulting in death in early adulthood. Numerous approaches are being taken to find a treatment for FRDA, including excision or correction of the repeats by genome engineering methods, gene activation with small molecules or artificial transcription factors, delivery of frataxin to affected cells by protein replacement therapy, gene therapy, or small molecules to increase frataxin protein levels, and therapies aimed at countering the cellular consequences of reduced frataxin. This review will summarize the mechanisms involved in repeat-mediated gene silencing and recent efforts aimed at development of therapeutics.
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Affiliation(s)
- Joel M Gottesfeld
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, 92037, USA.
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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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