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Mosbach V, Puccio H. A multiple animal and cellular models approach to study frataxin deficiency in Friedreich Ataxia. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119809. [PMID: 39134123 DOI: 10.1016/j.bbamcr.2024.119809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 08/01/2024] [Accepted: 08/02/2024] [Indexed: 08/15/2024]
Abstract
Friedreich's ataxia (FA) is one of the most frequent inherited recessive ataxias characterized by a progressive sensory and spinocerebellar ataxia. The main causative mutation is a GAA repeat expansion in the first intron of the frataxin (FXN) gene which leads to a transcriptional silencing of the gene resulting in a deficit in FXN protein. The nature of the mutation (an unstable GAA expansion), as well as the multi-systemic nature of the disease (with neural and non-neural sites affected) make the generation of models for Friedreich's ataxia quite challenging. Over the years, several cellular and animal models for FA have been developed. These models are all complementary and possess their own strengths to investigate different aspects of the disease, such as the epigenetics of the locus or the pathophysiology of the disease, as well as being used to developed novel therapeutic approaches. This review will explore the recent advancements in the different mammalian models developed for FA.
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Affiliation(s)
- Valentine Mosbach
- Institut NeuroMyoGene-PGNM UCBL-CNRS UMR5261 INSERM U1315, Lyon, France
| | - Hélène Puccio
- Institut NeuroMyoGene-PGNM UCBL-CNRS UMR5261 INSERM U1315, Lyon, France.
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2
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Da Conceição LMA, Cabral LM, Pereira GRC, De Mesquita JF. An In Silico Analysis of Genetic Variants and Structural Modeling of the Human Frataxin Protein in Friedreich's Ataxia. Int J Mol Sci 2024; 25:5796. [PMID: 38891993 PMCID: PMC11172458 DOI: 10.3390/ijms25115796] [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: 04/17/2024] [Revised: 05/15/2024] [Accepted: 05/20/2024] [Indexed: 06/21/2024] Open
Abstract
Friedreich's Ataxia (FRDA) stands out as the most prevalent form of hereditary ataxias, marked by progressive movement ataxia, loss of vibratory sensitivity, and skeletal deformities, severely affecting daily functioning. To date, the only medication available for treating FRDA is Omaveloxolone (Skyclarys®), recently approved by the FDA. Missense mutations within the human frataxin (FXN) gene, responsible for intracellular iron homeostasis regulation, are linked to FRDA development. These mutations induce FXN dysfunction, fostering mitochondrial iron accumulation and heightened oxidative stress, ultimately triggering neuronal cell death pathways. This study amalgamated 226 FXN genetic variants from the literature and database searches, with only 18 previously characterized. Predictive analyses revealed a notable prevalence of detrimental and destabilizing predictions for FXN mutations, predominantly impacting conserved residues crucial for protein function. Additionally, an accurate, comprehensive three-dimensional model of human FXN was constructed, serving as the basis for generating genetic variants I154F and W155R. These variants, selected for their severe clinical implications, underwent molecular dynamics (MD) simulations, unveiling flexibility and essential dynamic alterations in their N-terminal segments, encompassing FXN42, FXN56, and FXN78 domains pivotal for protein maturation. Thus, our findings indicate potential interaction profile disturbances in the FXN42, FXN56, and FXN78 domains induced by I154F and W155R mutations, aligning with the existing literature.
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Affiliation(s)
- Loiane Mendonça Abrantes Da Conceição
- Laboratory of Bioinformatics and Computational Biology, Federal University of the State of Rio de Janeiro (UNIRIO), Avenida Pasteur, 296, Urca, Rio de Janeiro 22290-250, Brazil (J.F.D.M.)
| | - Lucio Mendes Cabral
- Pharmaceutical Industrial Technology Laboratory, Federal University of Rio de Janeiro (UFRJ), Avenida Carlos Chagas Filho, 373, Cidade Universitária, Rio de Janeiro 21941-590, Brazil
| | - Gabriel Rodrigues Coutinho Pereira
- Pharmaceutical Industrial Technology Laboratory, Federal University of Rio de Janeiro (UFRJ), Avenida Carlos Chagas Filho, 373, Cidade Universitária, Rio de Janeiro 21941-590, Brazil
- Laboratory of Molecular Modeling & QSAR, Federal University of Rio de Janeiro (UFRJ), Avenida Carlos Chagas Filho, 373, Cidade Universitária, Rio de Janeiro 21941-590, Brazil
| | - Joelma Freire De Mesquita
- Laboratory of Bioinformatics and Computational Biology, Federal University of the State of Rio de Janeiro (UNIRIO), Avenida Pasteur, 296, Urca, Rio de Janeiro 22290-250, Brazil (J.F.D.M.)
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3
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Rojsajjakul T, Selvan N, De B, Rosenberg JB, Kaminsky SM, Sondhi D, Janki P, Crystal RG, Mesaros C, Khanna R, Blair IA. Expression and processing of mature human frataxin after gene therapy in mice. Sci Rep 2024; 14:8391. [PMID: 38600238 PMCID: PMC11006666 DOI: 10.1038/s41598-024-59060-0] [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: 12/21/2023] [Accepted: 04/06/2024] [Indexed: 04/12/2024] Open
Abstract
Friedreich's ataxia is a degenerative and progressive multisystem disorder caused by mutations in the highly conserved frataxin (FXN) gene that results in FXN protein deficiency and mitochondrial dysfunction. While gene therapy approaches are promising, consistent induction of therapeutic FXN protein expression that is sub-toxic has proven challenging, and numerous therapeutic approaches are being tested in animal models. FXN (hFXN in humans, mFXN in mice) is proteolytically modified in mitochondria to produce mature FXN. However, unlike endogenous hFXN, endogenous mFXN is further processed into N-terminally truncated, extra-mitochondrial mFXN forms of unknown function. This study assessed mature exogenous hFXN expression levels in the heart and liver of C57Bl/6 mice 7-10 months after intravenous administration of a recombinant adeno-associated virus encoding hFXN (AAVrh.10hFXN) and examined the potential for hFXN truncation in mice. AAVrh.10hFXN induced dose-dependent expression of hFXN in the heart and liver. Interestingly, hFXN was processed into truncated forms, but found at lower levels than mature hFXN. However, the truncations were at different positions than mFXN. AAVrh.10hFXN induced mature hFXN expression in mouse heart and liver at levels that approximated endogenous mFXN levels. These results suggest that AAVrh.10hFXN can likely induce expression of therapeutic levels of mature hFXN in mice.
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Affiliation(s)
- Teerapat Rojsajjakul
- Department of Systems Pharmacology and Translational Therapeutics Perelman School of Medicine, Penn/CHOP Friedreich's Ataxia Center of Excellence, Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Bishnu De
- Department of Genetic Medicine, Weill Cornell College of Medicine, New York, NY, USA
| | - Jonathan B Rosenberg
- Department of Genetic Medicine, Weill Cornell College of Medicine, New York, NY, USA
| | - Stephen M Kaminsky
- Department of Genetic Medicine, Weill Cornell College of Medicine, New York, NY, USA
| | - Dolan Sondhi
- Department of Genetic Medicine, Weill Cornell College of Medicine, New York, NY, USA
| | | | - Ronald G Crystal
- Department of Genetic Medicine, Weill Cornell College of Medicine, New York, NY, USA
| | - Clementina Mesaros
- Department of Systems Pharmacology and Translational Therapeutics Perelman School of Medicine, Penn/CHOP Friedreich's Ataxia Center of Excellence, Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Ian A Blair
- Department of Systems Pharmacology and Translational Therapeutics Perelman School of Medicine, Penn/CHOP Friedreich's Ataxia Center of Excellence, Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, USA.
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4
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Rojsajjakul T, Selvan N, De B, Rosenberg JB, Kaminsky SM, Sondhi D, Janki P, Crystal RG, Mesaros C, Khanna R, Blair IA. Expression and processing of mature human frataxin after gene therapy in mice. RESEARCH SQUARE 2023:rs.3.rs-3788652. [PMID: 38234818 PMCID: PMC10793484 DOI: 10.21203/rs.3.rs-3788652/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Friedreich's ataxia is a degenerative and progressive multisystem disorder caused by mutations in the highly conserved frataxin (FXN) gene that results in FXN protein deficiency and mitochondrial dysfunction. While gene therapy approaches are promising, consistent induction of therapeutic FXN protein expression that is sub-toxic has proven challenging, and numerous therapeutic approaches are being tested in animal models. FXN (hFXN in humans, mFXN in mice) is proteolytically modified in mitochondria to produce mature FXN. However, unlike endogenous hFXN, endogenous mFXN is further processed into N-terminally truncated, extra-mitochondrial mFXN forms of unknown function. This study assessed mature exogenous hFXN expression levels in the heart and liver of C57Bl/6 mice 7-10 months after intravenous administration of a recombinant adeno-associated virus encoding hFXN (AAVrh.10hFXN) and examined the potential for hFXN truncation in mice. AAVrh.10hFXN induced dose-dependent expression of hFXN in the heart and liver. Interestingly, hFXN was processed into truncated forms, but found at lower levels than mature hFXN. However, the truncations were at different positions than mFXN. AAVrh.10hFXN induced mature hFXN expression in mouse heart and liver at levels that approximated endogenous mFXN levels. These results demonstrate that AAVrh.10hFXN may induce expression of therapeutic levels of mature hFXN in mice.
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Rojsajjakul T, Hordeaux JJ, Choudhury GR, Hinderer CJ, Mesaros C, Wilson JM, Blair IA. Quantification of human mature frataxin protein expression in nonhuman primate hearts after gene therapy. Commun Biol 2023; 6:1093. [PMID: 37891254 PMCID: PMC10611776 DOI: 10.1038/s42003-023-05472-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
Deficiency in human mature frataxin (hFXN-M) protein is responsible for the devastating neurodegenerative and cardiodegenerative disease of Friedreich's ataxia (FRDA). It results primarily through epigenetic silencing of the FXN gene by GAA triplet repeats on intron 1 of both alleles. GAA repeat lengths are most commonly between 600 and 1200 but can reach 1700. A subset of approximately 3% of FRDA patients have GAA repeats on one allele and a mutation on the other. FRDA patients die most commonly in their 30s from heart disease. Therefore, increasing expression of heart hFXN-M using gene therapy offers a way to prevent early mortality in FRDA. We used rhesus macaque monkeys to test the pharmacology of an adeno-associated virus (AAV)hu68.CB7.hFXN therapy. The advantage of using non-human primates for hFXN-M gene therapy studies is that hFXN-M and monkey FXN-M (mFXN-M) are 98.5% identical, which limits potential immunologic side-effects. However, this presented a formidable bioanalytical challenge in quantification of proteins with almost identical sequences. This could be overcome by the development of a species-specific quantitative mass spectrometry-based method, which has revealed for the first time, robust transgene-specific human protein expression in monkey heart tissue. The dose response is non-linear resulting in a ten-fold increase in monkey heart hFXN-M protein expression with only a three-fold increase in dose of the vector.
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Affiliation(s)
- Teerapat Rojsajjakul
- Penn/CHOP Friedreich's Ataxia Center of Excellence and Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Juliette J Hordeaux
- Gene Therapy Program, Departments of Medicine and Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Gourav R Choudhury
- Gene Therapy Program, Departments of Medicine and Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Christian J Hinderer
- Gene Therapy Program, Departments of Medicine and Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Clementina Mesaros
- Penn/CHOP Friedreich's Ataxia Center of Excellence and Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - James M Wilson
- Gene Therapy Program, Departments of Medicine and Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Ian A Blair
- Penn/CHOP Friedreich's Ataxia Center of Excellence and Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Zhang Z, Jiang W, Zhang C, Yin Y, Mu N, Wang Y, Yu L, Ma H. Frataxin inhibits the sensitivity of the myocardium to ferroptosis by regulating iron homeostasis. Free Radic Biol Med 2023; 205:305-317. [PMID: 37343689 DOI: 10.1016/j.freeradbiomed.2023.06.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/08/2023] [Accepted: 06/19/2023] [Indexed: 06/23/2023]
Abstract
RATIONALE Myocardial ischemia/reperfusion (I/R) injury is characterized by cell death via various cellular mechanisms upon reperfusion. As a new type of cell death, ferroptosis provides new opportunities to reduce myocardial cell death. Ferroptosis is known to be more active during reperfusion than ischemia. However, the mechanisms regulating ferroptosis during ischemia and reperfusion remain largely unknown. METHODS The contribution of ferroptosis in ischemic and reperfused myocardium were detected by administered of Fer-1, a ferroptosis inhibitor to C57BL/6 mice, followed by left anterior descending (LAD) ligation surgery. Ferroptosis was evaluated by measurement of cell viability, ptgs2 mRNA level, iron production, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels. H9C2 cells were exposed to hypoxia/reoxygenation to mimic in vivo I/R. We used LC-MS/MS to identify potential E3 ligases that interacted with frataxin in heart tissue. Cardiac-specific overexpression of frataxin in whole heart was achieved by intracardiac injection of frataxin, carried by adeno-associated virus serotype 9 (AAV9) containing cardiac troponin T (cTnT) promoter. RESULTS We showed that regulators of iron metabolism, especially iron regulatory protein activity, were increased in the ischemic myocardium or hypoxia cardiomyocytes. In addition, we found that frataxin, which is involved in iron metabolism, is differentially expressed in the ischemic and reperfused myocardium and involved in the regulation of cardiomyocytes ferroptosis. Furthermore, we identified an E3 ligase, NHL repeat-containing 1 (NHLRC1), that mediates frataxin ubiquitination degradation. Cardiac-specific overexpression of frataxin ameliorated myocardial I/R injury through ferroptosis inhibition. CONCLUSIONS Through a multi-level study from molecule to animal model, these findings uncover the key role of frataxin in inhibiting cardiomyocyte ferroptosis and provide new strategies and perspectives for the treatment of myocardial I/R injury.
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Affiliation(s)
- Zihui Zhang
- Xi'an Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
| | - Wenhua Jiang
- Xi'an Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
| | - Chan Zhang
- Xi'an Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
| | - Yue Yin
- Department of Physiology and Pathophysiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, Shaanxi, 710032, PR China
| | - Nan Mu
- Department of Physiology and Pathophysiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, Shaanxi, 710032, PR China
| | - Yishi Wang
- Department of Physiology and Pathophysiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, Shaanxi, 710032, PR China
| | - Lu Yu
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
| | - Heng Ma
- Xi'an Key Laboratory of Stem Cell and Regenerative Medicine, Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China; Department of Physiology and Pathophysiology, School of Basic Medicine, Fourth Military Medical University, Xi'an, Shaanxi, 710032, PR China.
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7
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Blair I, Rojsajjakul T, Hordeaux J, Chaudhary G, Hinderer C, Mesaros C, Wilson J. Quantification of human mature frataxin protein expression in nonhuman primate hearts after gene therapy. RESEARCH SQUARE 2023:rs.3.rs-3121549. [PMID: 37461697 PMCID: PMC10350221 DOI: 10.21203/rs.3.rs-3121549/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Deficiency in human mature frataxin (hFXN-M) protein is responsible for the devastating neurodegenerative and cardiodegenerative disease of Friedreich's ataxia (FRDA). It results primarily by epigenetic silencing the FXN gene due to up to 1400 GAA triplet repeats in intron 1 of both alleles of the gene; a subset of approximately 3% of FRDA patients have a mutation on one allele. FRDA patients die most commonly in their 30s from heart disease. Therefore, increasing expression of heart hFXN-M using gene therapy offers a way to prevent early mortality in FRDA. We used rhesus macaque monkeys to test the pharmacology of an adeno-associated virus (AAV)hu68.CB7.hFXN therapy. The advantage of using non-human primates for hFXN-M gene therapy studies is that hFXN-M and monkey FXN-M (mFXN-M) are 98.5% identical, which limits potential immunologic side-effects. However, this presented a formidable bioanalytical challenge in quantification of proteins with almost identical sequences. This was overcome by development of a species-specific quantitative mass spectrometry-based method, which revealed for the first time, robust transgene-specific human protein expression in monkey heart tissue. The dose response was non-linear resulting in a ten-fold increase in monkey heart hFXN-M protein expression with only a three-fold increase in dose of the vector.
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8
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Rojsajjakul T, Wu L, Grady CB, Hwang WT, Mesaros C, Lynch DR, Blair IA. Liquid Chromatography-Mass Spectrometry Analysis of Frataxin Proteoforms in Whole Blood as Biomarkers of the Genetic Disease Friedreich's Ataxia. Anal Chem 2023; 95:4251-4260. [PMID: 36800320 PMCID: PMC9979142 DOI: 10.1021/acs.analchem.3c00091] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Friedreich's ataxia (FRDA) is caused primarily by expanded GAA repeats in intron 1 of both alleles of the FXN gene, which causes transcriptional silencing and reduced expression of frataxin mRNA and protein. FRDA is characterized by slowly progressive ataxia and cardiomyopathy. Symptoms generally appear during adolescence, and patients slowly progress to wheelchair dependency usually in the late teens or early twenties with death on average in the 4th decade. There are two known mature proteoforms of frataxin. Mitochondrial frataxin (frataxin-M) is a 130-amino acid protein with a molecular weight of 14,268 Da, and there is an alternatively spliced N-terminally acetylated 135-amino acid form (frataxin-E) with a molecular weight of 14,953 Da found in erythrocytes. There is reduced expression of frataxin in the heart and brain, but frataxin is not secreted into the systemic circulation, so it cannot be analyzed in serum or plasma. Blood is a readily accessible biofluid that contains numerous different cell types that express frataxin. We have found that pig blood can serve as an excellent surrogate matrix to validate an assay for frataxin proteoforms because pig frataxin is lost during the immunoprecipitation step used to isolate human frataxin. Frataxin-M is expressed in blood cells that contain mitochondria, whereas extra-mitochondrial frataxin-E is found in erythrocytes. This means that the analysis of frataxin in whole blood provides information on the concentration of both proteoforms without having to isolate the individual cell types. In the current study, we observed that the distributions of frataxin levels for a sample of 25 healthy controls and 50 FRDA patients were completely separated from each other, suggesting 100% specificity and 100% sensitivity for distinguishing healthy controls from FRDA cases, a very unusual finding for a biomarker assay. Additionally, frataxin levels were significantly correlated with the GAA repeat length and age of onset with higher correlations for extra-mitochondrial frataxin-E than those for mitochondrial frataxin-M. These findings auger well for using frataxin levels measured by the validated stable isotope dilution ultrahigh-performance liquid chromatography-multiple reaction monitoring/mass spectrometry assay to monitor therapeutic interventions and the natural history of FRDA. Our study also illustrates the utility of using whole blood for protein disease biomarker discovery and validation.
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Affiliation(s)
- Teerapat Rojsajjakul
- Penn/CHOP
Friedreich’s Ataxia Center of Excellence, Philadelphia, Pennsylvania 19104, United States,Center
of Excellence in Environmental Toxicology, Department of Systems Pharmacology
and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Linfeng Wu
- Agilent
Technologies Inc., 5301
Stevens Creek Blvd., Santa Clara, California 95051, United States
| | - Connor B. Grady
- Center
for Clinical Epidemiology and Biostatistics, Department of Biostatistics,
Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, United States
| | - Wei-Ting Hwang
- Center
for Clinical Epidemiology and Biostatistics, Department of Biostatistics,
Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, United States
| | - Clementina Mesaros
- Penn/CHOP
Friedreich’s Ataxia Center of Excellence, Philadelphia, Pennsylvania 19104, United States,Center
of Excellence in Environmental Toxicology, Department of Systems Pharmacology
and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - David R. Lynch
- Penn/CHOP
Friedreich’s Ataxia Center of Excellence, Philadelphia, Pennsylvania 19104, United States,Departments
of Pediatrics and Neurology, Children’s
Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Ian A. Blair
- Penn/CHOP
Friedreich’s Ataxia Center of Excellence, Philadelphia, Pennsylvania 19104, United States,Center
of Excellence in Environmental Toxicology, Department of Systems Pharmacology
and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States,. Phone: +1-610-529-0610. Fax: +1-215-573-9889
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Mandal AK. Mitochondrial targeting of potent nanoparticulated drugs in combating diseases. J Biomater Appl 2022; 37:614-633. [PMID: 35790487 DOI: 10.1177/08853282221111656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Mitochondrial dysfunction, characterized by the electron transport chain (ETC) leakage and reduced adenosine tri-phosphate synthesis, occurs primarily due to free radicals -induced mutations in either the mitochondrial deoxyribonucleic acid (mtDNA) or nuclear (n) DNA caused by pathogenic infections, toxicant exposures, adverse drug-effects, or other environmental exposures, leading to secondary dysfunction affecting ischemic, diabetic, cancerous, and degenerative diseases. In these concerns, mitochondria-targeted remedies may include a significant role in the protection and treatment of mitochondrial function to enhance its activity. Coenzyme Q10 pyridinol and pyrimidinol antioxidant analogues and other potent drug-compounds for their multifunctional radical quencher and other anti-toxic activities may take a significant therapeutic effectivity for ameliorating mitochondrial dysfunction. Moreover, the encapsulation of these bioactive ligands-attached potent compounds in vesicular system may enable them a superb biological effective for the treatment of mitochondria-targeted dysfunction-related diseases with least side effects. This review depicts mainly on mitochondrial enzymatic dysfunction and their amelioration by potent drugs with the usages of nanoparticulated delivery system against mitochondria-affected diseases.
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10
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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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11
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Rodden LN, Gilliam KM, Lam C, Rojsajjakul T, Mesaros C, Dionisi C, Pook M, Pandolfo M, Lynch DR, Blair IA, Bidichandani SI. DNA methylation in Friedreich ataxia silences expression of frataxin isoform E. Sci Rep 2022; 12:5031. [PMID: 35322126 PMCID: PMC8943190 DOI: 10.1038/s41598-022-09002-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 03/14/2022] [Indexed: 11/15/2022] Open
Abstract
Epigenetic silencing in Friedreich ataxia (FRDA), induced by an expanded GAA triplet-repeat in intron 1 of the FXN gene, results in deficiency of the mitochondrial protein, frataxin. A lesser known extramitochondrial isoform of frataxin detected in erythrocytes, frataxin-E, is encoded via an alternate transcript (FXN-E) originating in intron 1 that lacks a mitochondrial targeting sequence. We show that FXN-E is deficient in FRDA, including in patient-derived cell lines, iPS-derived proprioceptive neurons, and tissues from a humanized mouse model. In a series of FRDA patients, deficiency of frataxin-E protein correlated with the length of the expanded GAA triplet-repeat, and with repeat-induced DNA hypermethylation that occurs in close proximity to the intronic origin of FXN-E. CRISPR-induced epimodification to mimic DNA hypermethylation seen in FRDA reproduced FXN-E transcriptional deficiency. Deficiency of frataxin E is a consequence of FRDA-specific epigenetic silencing, and therapeutic strategies may need to address this deficiency.
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Affiliation(s)
- Layne N Rodden
- Department of Pediatrics, University of Oklahoma Health Sciences Center, OU Children's Physician Building, Suite 12100, 1200 Children's Avenue, Oklahoma City, OK, 73104, USA
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Kaitlyn M Gilliam
- Department of Pediatrics, University of Oklahoma Health Sciences Center, OU Children's Physician Building, Suite 12100, 1200 Children's Avenue, Oklahoma City, OK, 73104, USA
| | - Christina Lam
- Department of Pediatrics, University of Oklahoma Health Sciences Center, OU Children's Physician Building, Suite 12100, 1200 Children's Avenue, Oklahoma City, OK, 73104, USA
| | - Teerapat Rojsajjakul
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Clementina Mesaros
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Mark Pook
- Division of Biosciences, Department of Life Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UK
| | - Massimo Pandolfo
- Université Libre de Bruxelles (ULB), Brussels, Belgium
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - David R Lynch
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Ian A Blair
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sanjay I Bidichandani
- Department of Pediatrics, University of Oklahoma Health Sciences Center, OU Children's Physician Building, Suite 12100, 1200 Children's Avenue, Oklahoma City, OK, 73104, USA.
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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12
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Monfort B, Want K, Gervason S, D’Autréaux B. Recent Advances in the Elucidation of Frataxin Biochemical Function Open Novel Perspectives for the Treatment of Friedreich’s Ataxia. Front Neurosci 2022; 16:838335. [PMID: 35310092 PMCID: PMC8924461 DOI: 10.3389/fnins.2022.838335] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/28/2022] [Indexed: 12/25/2022] Open
Abstract
Friedreich’s ataxia (FRDA) is the most prevalent autosomic recessive ataxia and is associated with a severe cardiac hypertrophy and less frequently diabetes. It is caused by mutations in the gene encoding frataxin (FXN), a small mitochondrial protein. The primary consequence is a defective expression of FXN, with basal protein levels decreased by 70–98%, which foremost affects the cerebellum, dorsal root ganglia, heart and liver. FXN is a mitochondrial protein involved in iron metabolism but its exact function has remained elusive and highly debated since its discovery. At the cellular level, FRDA is characterized by a general deficit in the biosynthesis of iron-sulfur (Fe-S) clusters and heme, iron accumulation and deposition in mitochondria, and sensitivity to oxidative stress. Based on these phenotypes and the proposed ability of FXN to bind iron, a role as an iron storage protein providing iron for Fe-S cluster and heme biosynthesis was initially proposed. However, this model was challenged by several other studies and it is now widely accepted that FXN functions primarily in Fe-S cluster biosynthesis, with iron accumulation, heme deficiency and oxidative stress sensitivity appearing later on as secondary defects. Nonetheless, the biochemical function of FXN in Fe-S cluster biosynthesis is still debated. Several roles have been proposed for FXN: iron chaperone, gate-keeper of detrimental Fe-S cluster biosynthesis, sulfide production stimulator and sulfur transfer accelerator. A picture is now emerging which points toward a unique function of FXN as an accelerator of a key step of sulfur transfer between two components of the Fe-S cluster biosynthetic complex. These findings should foster the development of new strategies for the treatment of FRDA. We will review here the latest discoveries on the biochemical function of frataxin and the implication for a potential therapeutic treatment of FRDA.
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13
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Rufini A, Malisan F, Condò I, Testi R. Drug Repositioning in Friedreich Ataxia. Front Neurosci 2022; 16:814445. [PMID: 35221903 PMCID: PMC8863941 DOI: 10.3389/fnins.2022.814445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 01/07/2022] [Indexed: 12/14/2022] Open
Abstract
Friedreich ataxia is a rare neurodegenerative disorder caused by insufficient levels of the essential mitochondrial protein frataxin. It is a severely debilitating disease that significantly impacts the quality of life of affected patients and reduces their life expectancy, however, an adequate cure is not yet available for patients. Frataxin function, although not thoroughly elucidated, is associated with assembly of iron-sulfur cluster and iron metabolism, therefore insufficient frataxin levels lead to reduced activity of many mitochondrial enzymes involved in the electron transport chain, impaired mitochondrial metabolism, reduced ATP production and inefficient anti-oxidant response. As a consequence, neurons progressively die and patients progressively lose their ability to coordinate movement and perform daily activities. Therapeutic strategies aim at restoring sufficient frataxin levels or at correcting some of the downstream consequences of frataxin deficiency. However, the classical pathways of drug discovery are challenging, require a significant amount of resources and time to reach the final approval, and present a high failure rate. Drug repositioning represents a viable alternative to boost the identification of a therapy, particularly for rare diseases where resources are often limited. In this review we will describe recent efforts aimed at the identification of a therapy for Friedreich ataxia through drug repositioning, and discuss the limitation of such strategies.
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Affiliation(s)
- Alessandra Rufini
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, Rome, Italy
- Fratagene Therapeutics, Rome, Italy
- Saint Camillus International University of Health and Medical Sciences, Rome, Italy
- *Correspondence: Alessandra Rufini,
| | - Florence Malisan
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, Rome, Italy
| | - Ivano Condò
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, Rome, Italy
| | - Roberto Testi
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, Rome, Italy
- Fratagene Therapeutics, Rome, Italy
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14
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Doni D, Meggiolaro M, Santos J, Audran G, Marque SRA, Costantini P, Bortolus M, Carbonera D. A Combined Spectroscopic and In Silico Approach to Evaluate the Interaction of Human Frataxin with Mitochondrial Superoxide Dismutase. Biomedicines 2021; 9:biomedicines9121763. [PMID: 34944579 PMCID: PMC8698469 DOI: 10.3390/biomedicines9121763] [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: 10/23/2021] [Revised: 11/15/2021] [Accepted: 11/22/2021] [Indexed: 11/23/2022] Open
Abstract
Frataxin (FXN) is a highly conserved mitochondrial protein whose deficiency causes Friedreich’s ataxia, a neurodegenerative disease. The precise physiological function of FXN is still unclear; however, there is experimental evidence that the protein is involved in biosynthetic iron–sulfur cluster machinery, redox imbalance, and iron homeostasis. FXN is synthesized in the cytosol and imported into the mitochondria, where it is proteolytically cleaved to the mature form. Its involvement in the redox imbalance suggests that FXN could interact with mitochondrial superoxide dismutase (SOD2), a key enzyme in antioxidant cellular defense. In this work, we use site-directed spin labelling coupled to electron paramagnetic resonance spectroscopy (SDSL-EPR) and fluorescence quenching experiments to investigate the interaction between human FXN and SOD2 in vitro. Spectroscopic data are combined with rigid body protein–protein docking to assess the potential structure of the FXN-SOD2 complex, which leaves the metal binding region of FXN accessible to the solvent. We provide evidence that human FXN interacts with human SOD2 in vitro and that the complex is in fast exchange. This interaction could be relevant during the assembly of iron-sulfur (FeS) clusters and/or their incorporation in proteins when FeS clusters are potentially susceptible to attacks by reactive oxygen species.
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Affiliation(s)
- Davide Doni
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy; (D.D.); (M.M.); (P.C.)
| | - Marta Meggiolaro
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy; (D.D.); (M.M.); (P.C.)
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy;
| | - Javier Santos
- Instituto de Biociencias, Biotecnología y Biología Traslacional (iB3), Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Buenos Aires C1428EGA, Argentina;
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Buenos Aires C1428EGA, Argentina
| | - Gérard Audran
- Aix Marseille Universitè, CNRS, ICR, UMR 7273, case 551, Ave Escadrille Normandie Niemen, CEDEX 20, 13397 Marseille, France; (G.A.); (S.R.A.M.)
| | - Sylvain R. A. Marque
- Aix Marseille Universitè, CNRS, ICR, UMR 7273, case 551, Ave Escadrille Normandie Niemen, CEDEX 20, 13397 Marseille, France; (G.A.); (S.R.A.M.)
| | - Paola Costantini
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy; (D.D.); (M.M.); (P.C.)
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy;
- Correspondence:
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy;
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15
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Doni D, Rigoni G, Palumbo E, Baschiera E, Peruzzo R, De Rosa E, Caicci F, Passerini L, Bettio D, Russo A, Szabò I, Soriano ME, Salviati L, Costantini P. The displacement of frataxin from the mitochondrial cristae correlates with abnormal respiratory supercomplexes formation and bioenergetic defects in cells of Friedreich ataxia patients. FASEB J 2021; 35:e21362. [PMID: 33629768 DOI: 10.1096/fj.202000524rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 12/09/2020] [Accepted: 12/28/2020] [Indexed: 12/23/2022]
Abstract
Friedreich ataxia (FRDA) is a neurodegenerative disease resulting from a severe decrease of frataxin (FXN). Most patients carry a GAA repeat expansion in both alleles of the FXN gene, whereas a small fraction of them are compound heterozygous for the expansion and a point mutation in the other allele. FXN is involved in the mitochondrial biogenesis of the FeS-clusters. Distinctive feature of FRDA patient cells is an impaired cellular respiration, likely due to a deficit of key redox cofactors working as electrons shuttles through the respiratory chain. However, a definite relationship between FXN levels, FeS-clusters assembly dysregulation and bioenergetics failure has not been established. In this work, we performed a comparative analysis of the mitochondrial phenotype of cell lines from FRDA patients, either homozygous for the expansion or compound heterozygotes for the G130V mutation. We found that, in healthy cells, FXN and two key proteins of the FeS-cluster assembly machinery are enriched in mitochondrial cristae, the dynamic subcompartment housing the respiratory chain. On the contrary, FXN widely redistributes to the matrix in FRDA cells with defects in respiratory supercomplexes assembly and altered respiratory function. We propose that this could be relevant for the early mitochondrial defects afflicting FRDA cells and that perturbation of mitochondrial morphodynamics could in turn be critical in terms of disease mechanisms.
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Affiliation(s)
- Davide Doni
- Department of Biology, University of Padova, Padova, Italy
| | | | - Elisa Palumbo
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Elisa Baschiera
- Clinical Genetics Unit, Department of Women's and Children's Health, University of Padova, Padova, Italy
- Istituto di Ricerca Pediatrica (IRP) Città della Speranza, Padova, Italy
| | | | - Edith De Rosa
- Department of Biology, University of Padova, Padova, Italy
| | | | | | - Daniela Bettio
- Clinical Genetics Unit, Department of Women's and Children's Health, University of Padova, Padova, Italy
- Istituto di Ricerca Pediatrica (IRP) Città della Speranza, Padova, Italy
| | - Antonella Russo
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Ildiko Szabò
- Department of Biology, University of Padova, Padova, Italy
| | | | - Leonardo Salviati
- Clinical Genetics Unit, Department of Women's and Children's Health, University of Padova, Padova, Italy
- Istituto di Ricerca Pediatrica (IRP) Città della Speranza, Padova, Italy
- Myology Center, University of Padova, Padova, Italy
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16
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Doni D, Passerini L, Audran G, Marque SRA, Schulz M, Santos J, Costantini P, Bortolus M, Carbonera D. Effects of Fe 2+/Fe 3+ Binding to Human Frataxin and Its D122Y Variant, as Revealed by Site-Directed Spin Labeling (SDSL) EPR Complemented by Fluorescence and Circular Dichroism Spectroscopies. Int J Mol Sci 2020; 21:E9619. [PMID: 33348670 PMCID: PMC7766144 DOI: 10.3390/ijms21249619] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 12/11/2020] [Accepted: 12/15/2020] [Indexed: 12/17/2022] Open
Abstract
Frataxin is a highly conserved protein whose deficiency results in the neurodegenerative disease Friederich's ataxia. Frataxin's actual physiological function has been debated for a long time without reaching a general agreement; however, it is commonly accepted that the protein is involved in the biosynthetic iron-sulphur cluster (ISC) machinery, and several authors have pointed out that it also participates in iron homeostasis. In this work, we use site-directed spin labeling coupled to electron paramagnetic resonance (SDSL EPR) to add new information on the effects of ferric and ferrous iron binding on the properties of human frataxin in vitro. Using SDSL EPR and relating the results to fluorescence experiments commonly performed to study iron binding to FXN, we produced evidence that ferric iron causes reversible aggregation without preferred interfaces in a concentration-dependent fashion, starting at relatively low concentrations (micromolar range), whereas ferrous iron binds without inducing aggregation. Moreover, our experiments show that the ferrous binding does not lead to changes of protein conformation. The data reported in this study reveal that the currently reported binding stoichiometries should be taken with caution. The use of a spin label resistant to reduction, as well as the comparison of the binding effect of Fe2+ in wild type and in the pathological D122Y variant of frataxin, allowed us to characterize the Fe2+ binding properties of different protein sites and highlight the effect of the D122Y substitution on the surrounding residues. We suggest that both Fe2+ and Fe3+ might play a relevant role in the context of the proposed FXN physiological functions.
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Affiliation(s)
- Davide Doni
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy; (D.D.); (P.C.)
| | - Leonardo Passerini
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (L.P.); (D.C.)
| | - Gérard Audran
- Institut de Chimie Radicalaire, Aix Marseille Universitè, CNRS, ICR, UMR 7273, Case 551, Ave Escadrille Normandie Niemen, CEDEX 20, 13397 Marseille, France; (G.A.); (S.R.A.M.); (M.S.)
| | - Sylvain R. A. Marque
- Institut de Chimie Radicalaire, Aix Marseille Universitè, CNRS, ICR, UMR 7273, Case 551, Ave Escadrille Normandie Niemen, CEDEX 20, 13397 Marseille, France; (G.A.); (S.R.A.M.); (M.S.)
| | - Marvin Schulz
- Institut de Chimie Radicalaire, Aix Marseille Universitè, CNRS, ICR, UMR 7273, Case 551, Ave Escadrille Normandie Niemen, CEDEX 20, 13397 Marseille, France; (G.A.); (S.R.A.M.); (M.S.)
| | - Javier Santos
- Departamento de Química Biológica, Instituto de Biociencias, Biotecnología y Biomedicina (iB3-UBA), Facultad de Ciencia Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160—Ciudad Universitaria, 1428EGA CONICET, Godoy Cruz 2290, Buenos Aires C1425FQB, Argentina;
- Instituto de Química y Fisicoquímica Biológicas Dr. Alejandro Paladini, Universidad de Buenos Aires, CONICET, Junín 956, Buenos Aires 1113AAD, Argentina
| | - Paola Costantini
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy; (D.D.); (P.C.)
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (L.P.); (D.C.)
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; (L.P.); (D.C.)
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17
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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: 18] [Impact Index Per Article: 4.5] [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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18
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The Ubiquitin Proteasome System in Neuromuscular Disorders: Moving Beyond Movement. Int J Mol Sci 2020; 21:ijms21176429. [PMID: 32899400 PMCID: PMC7503226 DOI: 10.3390/ijms21176429] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/30/2020] [Accepted: 08/31/2020] [Indexed: 12/12/2022] Open
Abstract
Neuromuscular disorders (NMDs) affect 1 in 3000 people worldwide. There are more than 150 different types of NMDs, where the common feature is the loss of muscle strength. These disorders are classified according to their neuroanatomical location, as motor neuron diseases, peripheral nerve diseases, neuromuscular junction diseases, and muscle diseases. Over the years, numerous studies have pointed to protein homeostasis as a crucial factor in the development of these fatal diseases. The ubiquitin-proteasome system (UPS) plays a fundamental role in maintaining protein homeostasis, being involved in protein degradation, among other cellular functions. Through a cascade of enzymatic reactions, proteins are ubiquitinated, tagged, and translocated to the proteasome to be degraded. Within the ubiquitin system, we can find three main groups of enzymes: E1 (ubiquitin-activating enzymes), E2 (ubiquitin-conjugating enzymes), and E3 (ubiquitin-protein ligases). Only the ubiquitinated proteins with specific chain linkages (such as K48) will be degraded by the UPS. In this review, we describe the relevance of this system in NMDs, summarizing the UPS proteins that have been involved in pathological conditions and neuromuscular disorders, such as Spinal Muscular Atrophy (SMA), Charcot-Marie-Tooth disease (CMT), or Duchenne Muscular Dystrophy (DMD), among others. A better knowledge of the processes involved in the maintenance of proteostasis may pave the way for future progress in neuromuscular disorder studies and treatments.
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19
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Rodríguez LR, Lapeña T, Calap-Quintana P, Moltó MD, Gonzalez-Cabo P, Navarro Langa JA. Antioxidant Therapies and Oxidative Stress in Friedreich´s Ataxia: The Right Path or Just a Diversion? Antioxidants (Basel) 2020; 9:E664. [PMID: 32722309 PMCID: PMC7465446 DOI: 10.3390/antiox9080664] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/17/2020] [Accepted: 07/19/2020] [Indexed: 12/12/2022] Open
Abstract
Friedreich´s ataxia is the commonest autosomal recessive ataxia among population of European descent. Despite the huge advances performed in the last decades, a cure still remains elusive. One of the most studied hallmarks of the disease is the increased production of oxidative stress markers in patients and models. This feature has been the motivation to develop treatments that aim to counteract such boost of free radicals and to enhance the production of antioxidant defenses. In this work, we present and critically review those "antioxidant" drugs that went beyond the disease´s models and were approved for its application in clinical trials. The evaluation of these trials highlights some crucial aspects of the FRDA research. On the one hand, the analysis contributes to elucidate whether oxidative stress plays a central role or whether it is only an epiphenomenon. On the other hand, it comments on some limitations in the current trials that complicate the analysis and interpretation of their outcome. We also include some suggestions that will be interesting to implement in future studies and clinical trials.
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Affiliation(s)
- Laura R. Rodríguez
- Department of Physiology, Faculty of Medicine and Dentistry, Universitat de València-INCLIVA, 46010 Valencia, Spain; (L.R.R.); (T.L.); (P.C.-Q.)
- Associated Unit for Rare Diseases INCLIVA-CIPF, 46010 Valencia, Spain
| | - Tamara Lapeña
- Department of Physiology, Faculty of Medicine and Dentistry, Universitat de València-INCLIVA, 46010 Valencia, Spain; (L.R.R.); (T.L.); (P.C.-Q.)
- Associated Unit for Rare Diseases INCLIVA-CIPF, 46010 Valencia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 46010 Valencia, Spain
| | - Pablo Calap-Quintana
- Department of Physiology, Faculty of Medicine and Dentistry, Universitat de València-INCLIVA, 46010 Valencia, Spain; (L.R.R.); (T.L.); (P.C.-Q.)
- Associated Unit for Rare Diseases INCLIVA-CIPF, 46010 Valencia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 46010 Valencia, Spain
| | - María Dolores Moltó
- Department of Genetics, Universitat de València-INCLIVA, 46100 Valencia, Spain;
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), 46100 Valencia, Spain
| | - Pilar Gonzalez-Cabo
- Department of Physiology, Faculty of Medicine and Dentistry, Universitat de València-INCLIVA, 46010 Valencia, Spain; (L.R.R.); (T.L.); (P.C.-Q.)
- Associated Unit for Rare Diseases INCLIVA-CIPF, 46010 Valencia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 46010 Valencia, Spain
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20
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La Rosa P, Petrillo S, Bertini ES, Piemonte F. Oxidative Stress in DNA Repeat Expansion Disorders: A Focus on NRF2 Signaling Involvement. Biomolecules 2020; 10:biom10050702. [PMID: 32369911 PMCID: PMC7277112 DOI: 10.3390/biom10050702] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/13/2022] Open
Abstract
DNA repeat expansion disorders are a group of neuromuscular and neurodegenerative diseases that arise from the inheritance of long tracts of nucleotide repetitions, located in the regulatory region, introns, or inside the coding sequence of a gene. Although loss of protein expression and/or the gain of function of its transcribed mRNA or translated product represent the major pathogenic effect of these pathologies, mitochondrial dysfunction and imbalance in redox homeostasis are reported as common features in these disorders, deeply affecting their severity and progression. In this review, we examine the role that the redox imbalance plays in the pathological mechanisms of DNA expansion disorders and the recent advances on antioxidant treatments, particularly focusing on the expression and the activity of the transcription factor NRF2, the main cellular regulator of the antioxidant response.
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21
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Tiano F, Amati F, Cherubini F, Morini E, Vancheri C, Maletta S, Fortuni S, Serio D, Quatrana A, Luffarelli R, Benini M, Alfedi G, Panarello L, Rufini A, Toschi N, Frontali M, Romano S, Marcotulli C, Casali C, Gioiosa S, Mariotti C, Mongelli A, Fichera M, Condò I, Novelli G, Testi R, Malisan F. Frataxin deficiency in Friedreich's ataxia is associated with reduced levels of HAX-1, a regulator of cardiomyocyte death and survival. Hum Mol Genet 2020; 29:471-482. [PMID: 31943004 DOI: 10.1093/hmg/ddz306] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 11/29/2019] [Accepted: 12/10/2019] [Indexed: 12/31/2022] Open
Abstract
Frataxin deficiency, responsible for Friedreich's ataxia (FRDA), is crucial for cell survival since it critically affects viability of neurons, pancreatic beta cells and cardiomyocytes. In FRDA, the heart is frequently affected with typical manifestation of hypertrophic cardiomyopathy, which can progress to heart failure and cause premature death. A microarray analysis performed on FRDA patient's lymphoblastoid cells stably reconstituted with frataxin, indicated HS-1-associated protein X-1 (HAX-1) as the most significantly upregulated transcript (FC = +2, P < 0.0006). quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) and western blot analysis performed on (I) HEK293 stably transfected with empty vector compared to wild-type frataxin and (II) lymphoblasts from FRDA patients show that low frataxin mRNA and protein expression correspond to reduced levels of HAX-1. Frataxin overexpression and silencing were also performed in the AC16 human cardiomyocyte cell line. HAX-1 protein levels are indeed regulated through frataxin modulation. Moreover, correlation between frataxin and HAX-1 was further evaluated in peripheral blood mononuclear cells (PBMCs) from FRDA patients and from non-related healthy controls. A regression model for frataxin which included HAX-1, group membership and group* HAX-1 interaction revealed that frataxin and HAX-1 are associated both at mRNA and protein levels. Additionally, a linked expression of FXN, HAX-1 and antioxidant defence proteins MnSOD and Nrf2 was observed both in PBMCs and AC16 cardiomyocytes. Our results suggest that HAX-1 could be considered as a potential biomarker of cardiac disease in FRDA and the evaluation of its expression might provide insights into its pathogenesis as well as improving risk stratification strategies.
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Affiliation(s)
- Francesca Tiano
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
| | - Francesca Amati
- Section of Medical Genetics, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
- Department of Human Sciences and Quality of Life Promotion, University San Raffaele, 00166 Rome, Italy
| | - Fabio Cherubini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
| | - Elena Morini
- Section of Medical Genetics, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
| | - Chiara Vancheri
- Section of Medical Genetics, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
| | - Sara Maletta
- Section of Medical Genetics, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
| | - Silvia Fortuni
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
| | - Dario Serio
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
| | - Andrea Quatrana
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
| | - Riccardo Luffarelli
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
- Fratagene Therapeutics Srl, 00133 Rome, Italy
| | - Monica Benini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
- Fratagene Therapeutics Srl, 00133 Rome, Italy
| | - Giulia Alfedi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
- Fratagene Therapeutics Srl, 00133 Rome, Italy
| | - Luca Panarello
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
| | - Alessandra Rufini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
- Fratagene Therapeutics Srl, 00133 Rome, Italy
| | - Nicola Toschi
- Medical Physics Section, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
- A.A. Martinos Center for Biomedical Imaging, Harvard Medical School, Charlestown, MA 02129, USA
| | - Marina Frontali
- CNR Institute of Translational Pharmacology, 00133 Rome, Italy
| | - Silvia Romano
- Neurosciences, Mental Health and Sensory Organs (NESMOS) Department, Faculty of Medicine and Psychology, Sapienza University, 00189 Rome, Italy
| | - Christian Marcotulli
- Department of Medical Surgical Sciences and Biotechnologies, Polo Pontino-Sapienza University of Rome, 04100 Latina, Italy
| | - Carlo Casali
- Department of Medical Surgical Sciences and Biotechnologies, Polo Pontino-Sapienza University of Rome, 04100 Latina, Italy
| | - Silvia Gioiosa
- SCAI (Super Computing Applications and Innovations) CINECA, 00185 Rome, Italy
| | - Caterina Mariotti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy
| | - Alessia Mongelli
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy
| | - Mario Fichera
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy
| | - Ivano Condò
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
| | - Giuseppe Novelli
- Section of Medical Genetics, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
- Neuromed Institute, IRCCS, 86077 Pozzilli, Italy
| | - Roberto Testi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
- Fratagene Therapeutics Srl, 00133 Rome, Italy
| | - Florence Malisan
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy
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22
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Bon C, Luffarelli R, Russo R, Fortuni S, Pierattini B, Santulli C, Fimiani C, Persichetti F, Cotella D, Mallamaci A, Santoro C, Carninci P, Espinoza S, Testi R, Zucchelli S, Condò I, Gustincich S. SINEUP non-coding RNAs rescue defective frataxin expression and activity in a cellular model of Friedreich's Ataxia. Nucleic Acids Res 2019; 47:10728-10743. [PMID: 31584077 PMCID: PMC6847766 DOI: 10.1093/nar/gkz798] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 08/08/2019] [Accepted: 09/28/2019] [Indexed: 12/16/2022] Open
Abstract
Friedreich's ataxia (FRDA) is an untreatable disorder with neuro- and cardio-degenerative progression. This monogenic disease is caused by the hyper-expansion of naturally occurring GAA repeats in the first intron of the FXN gene, encoding for frataxin, a protein implicated in the biogenesis of iron-sulfur clusters. As the genetic defect interferes with FXN transcription, FRDA patients express a normal frataxin protein but at insufficient levels. Thus, current therapeutic strategies are mostly aimed to restore physiological FXN expression. We have previously described SINEUPs, natural and synthetic antisense long non-coding RNAs, which promote translation of partially overlapping mRNAs through the activity of an embedded SINEB2 domain. Here, by in vitro screening, we have identified a number of SINEUPs targeting human FXN mRNA and capable to up-regulate frataxin protein to physiological amounts acting at the post-transcriptional level. Furthermore, FXN-specific SINEUPs promote the recovery of disease-associated mitochondrial aconitase defects in FRDA-derived cells. In summary, we provide evidence that SINEUPs may be the first gene-specific therapeutic approach to activate FXN translation in FRDA and, more broadly, a novel scalable platform to develop new RNA-based therapies for haploinsufficient diseases.
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Affiliation(s)
- Carlotta Bon
- Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), Genova, Italy
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Riccardo Luffarelli
- Department of Biomedicine and Prevention, Laboratory of Signal Transduction, University of Rome Tor Vergata, Rome, Italy
| | - Roberta Russo
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Silvia Fortuni
- Department of Biomedicine and Prevention, Laboratory of Signal Transduction, University of Rome Tor Vergata, Rome, Italy
| | - Bianca Pierattini
- Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), Genova, Italy
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Chiara Santulli
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Cristina Fimiani
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Francesca Persichetti
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), University of Piemonte Orientale (UPO), Novara, Italy
| | - Diego Cotella
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), University of Piemonte Orientale (UPO), Novara, Italy
| | - Antonello Mallamaci
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
| | - Claudio Santoro
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), University of Piemonte Orientale (UPO), Novara, Italy
| | - Piero Carninci
- RIKEN Center for Life Science Technologies, Division of Genomic Technologies, Yokohama, Kanagawa, Japan
| | - Stefano Espinoza
- Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), Genova, Italy
| | - Roberto Testi
- Department of Biomedicine and Prevention, Laboratory of Signal Transduction, University of Rome Tor Vergata, Rome, Italy
| | - Silvia Zucchelli
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
- Department of Health Sciences and Interdisciplinary Research Center of Autoimmune Diseases (IRCAD), University of Piemonte Orientale (UPO), Novara, Italy
| | - Ivano Condò
- Department of Biomedicine and Prevention, Laboratory of Signal Transduction, University of Rome Tor Vergata, Rome, Italy
| | - Stefano Gustincich
- Central RNA Laboratory, Istituto Italiano di Tecnologia (IIT), Genova, Italy
- Area of Neuroscience, International School for Advanced Studies (SISSA), Italy
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23
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Weng L, Wang Q, Yu S, Yang X, Lynch DR, Mesaros C, Blair IA. Evaluation of antibodies for western blot analysis of frataxin protein isoforms. J Immunol Methods 2019; 474:112629. [PMID: 31279523 PMCID: PMC6829029 DOI: 10.1016/j.jim.2019.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/21/2019] [Accepted: 07/03/2019] [Indexed: 12/12/2022]
Abstract
Frataxin is the protein that is down-regulated in Friedreich ataxia (FRDA), an autosomal recessive genetic disease caused by an intronic GAA repeat expansion in intron-1 of the FXN gene. The GAA repeats result in epigenetic silencing of the FXN gene and reduced expression of the cytosolic full-length frataxin (1-210) protein. Full length frataxin translocates to the mitochondria, leading to formation of mature frataxin (81-210) formed by cleavage of the mitochondrial targeting sequence at K-80 of the full-length protein. There are currently no approved treatments for FRDA, although experimental approaches involving up-regulation or replacement of mature frataxin protein through numerous approaches are being tested. Many of the pre-clinical studies of these experimental approaches are conducted in mouse and monkey models as well as in human cell lines. Consequently, well-validated antibodies are required for use in western blot analysis to determine whether levels of various forms of frataxin have been increased. Here we examined the specificity of five commercially available anti-frataxin antibodies and determined whether they detect mature frataxin in mouse heart tissue. Four protein standards of monkey, human, and mouse frataxin as well as mouse heart tissue were examined using polyacrylamide gel electrophoresis (PAGE) in combination with western blot analysis. One antibody failed to detect any of the frataxin standards or endogenous frataxin in mouse heart tissue. Three of the antibodies detected a protein in mouse heart tissue that ran slightly faster on PAGE (at 23.4 kDa) to that predicted for full-length frataxin (23.9 kDa). One antibody detected all four frataxin standards as well as endogenous mouse mature frataxin in mouse tissue. Significantly, this antibody, which will be useful for monitoring mature frataxin levels in monkey, human, and mouse tissues, did not detect a protein in mouse heart tissue at 23.4 kDa. Therefore, antibodies detecting the immunoreactive protein at 23.4 kDa could be misleading when testing for the up-regulation of frataxin in animal models.
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Affiliation(s)
- Liwei Weng
- Penn/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA 19104, USA; Penn SRP Center and 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/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA 19104, USA; Penn SRP Center and Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sixiang Yu
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Xiaolu Yang
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - David R Lynch
- Penn/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Pediatrics and Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Clementina Mesaros
- Penn/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA 19104, USA; Penn SRP Center and Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ian A Blair
- Penn/CHOP Center of Excellence in Friedreich's Ataxia, University of Pennsylvania, Philadelphia, PA 19104, USA; Penn SRP Center and Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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24
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Bellanda M, Maso L, Doni D, Bortolus M, De Rosa E, Lunardi F, Alfonsi A, Noguera ME, Herrera MG, Santos J, Carbonera D, Costantini P. Exploring iron-binding to human frataxin and to selected Friedreich ataxia mutants by means of NMR and EPR spectroscopies. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2019; 1867:140254. [PMID: 31344531 DOI: 10.1016/j.bbapap.2019.07.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/12/2019] [Accepted: 07/18/2019] [Indexed: 11/23/2022]
Abstract
The neurodegenerative disease Friedreich ataxia results from a deficiency of frataxin, a mitochondrial protein. Most patients have a GAA expansion in the first intron of both alleles of frataxin gene, whereas a minority of them are heterozygous for the expansion and contain a mutation in the other allele. Frataxin has been claimed to participate in iron homeostasis and biosynthesis of FeS clusters, however its role in both pathways is not unequivocally defined. In this work we combined different advanced spectroscopic analyses to explore the iron-binding properties of human frataxin, as isolated and at the FeS clusters assembly machinery. For the first time we used EPR spectroscopy to address this key issue providing clear evidence of the formation of a complex with a low symmetry coordination of the metal ion. By 2D NMR, we confirmed that iron can be bound in both oxidation states, a controversial issue, and, in addition, we were able to point out a transient interaction of frataxin with a N-terminal 6his-tagged variant of ISCU, the scaffold protein of the FeS clusters assembly machinery. To obtain insights on structure/function relationships relevant to understand the disease molecular mechanism(s), we extended our studies to four clinical frataxin mutants. All variants showed a moderate to strong impairment in their ability to activate the FeS cluster assembly machinery in vitro, while keeping the same iron-binding features of the wild type protein. This supports the multifunctional nature of frataxin and the complex biochemical consequences of its mutations.
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Affiliation(s)
- Massimo Bellanda
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy
| | - Lorenzo Maso
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy
| | - Davide Doni
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy
| | - Edith De Rosa
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy; Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy
| | - Federica Lunardi
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy
| | - Arianna Alfonsi
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy
| | - Martín Ezequiel Noguera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Universidad de Buenos Aires, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Intendente Güiraldes 2160 - Ciudad Universitaria, 1428EGA C.A.B.A., Argentina; Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini, Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD C.A.B.A., Argentina
| | - Maria Georgina Herrera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Universidad de Buenos Aires, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Intendente Güiraldes 2160 - Ciudad Universitaria, 1428EGA C.A.B.A., Argentina; Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini, Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD C.A.B.A., Argentina
| | - Javier Santos
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Universidad de Buenos Aires, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Intendente Güiraldes 2160 - Ciudad Universitaria, 1428EGA C.A.B.A., Argentina; Intituto de Química y Fisicoquímica Biológicas, Dr. Alejandro Paladini, Universidad de Buenos Aires, CONICET, Junín 956, 1113AAD C.A.B.A., Argentina
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy.
| | - Paola Costantini
- Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy.
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25
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Castro L, Tórtora V, Mansilla S, Radi R. Aconitases: Non-redox Iron-Sulfur Proteins Sensitive to Reactive Species. Acc Chem Res 2019; 52:2609-2619. [PMID: 31287291 DOI: 10.1021/acs.accounts.9b00150] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mammalian aconitases (mitochondrial and cytosolic isoenzymes) are unique iron-sulfur cluster-containing proteins in which the metallic center participates in the catalysis of a non-redox reaction. Within the cubane iron-sulfur cluster of aconitases only three of the four iron ions have cysteine thiolate ligands; the fourth iron ion (Feα) is solvent exposed within the active-site pocket and bound to oxygen atoms from either water or substrates to be dehydrated. The catalyzed reaction is the reversible isomerization of citrate to isocitrate with an intermediate metabolite, cis-aconitate. The cytosolic isoform of aconitase is a moonlighting enzyme; when intracellular iron is scarce, the complete disassembly of the iron-sulfur cluster occurs and apo-aconitase acquires the function of an iron responsive protein and regulates the translation of proteins involved in iron metabolism. In the late 1980s and during the 1990s, cumulative experimental evidence pointed out that aconitases are main targets of reactive oxygen and nitrogen species such as superoxide radical (O2•-), hydrogen peroxide (H2O2), nitric oxide (•NO), and peroxynitrite (ONOO-). These intermediates are capable of oxidizing the cluster, which leads to iron release and consequent loss of the catalytic activity of aconitase. As the reaction of the Fe-S cluster with O2•- is fast (∼107 M-1 s-1), quite specific, and reversible in vivo, quantification of active aconitase has been used to evaluate O2•- formation in cells. While •NO is modestly reactive with aconitase, its reaction with O2•- yields ONOO-, a strong oxidant that readily leads to the disruption of the Fe-S cluster. In the case of cytosolic aconitase, it has been seen that H2O2 and •NO promote activation of iron responsive protein activity in cells. Proteomic advances in the 2000s confirmed that aconitases are main targets of reactive species in cellular models and in vivo, and other post-translational oxidative modifications such as protein nitration and carbonylation have been detected. Herein, we (1) outline the particular structural features of aconitase that make these proteins specific targets of reactive species, (2) characterize the reactions of O2•-, H2O2, •NO, and ONOO- and related species with aconitases, (3) discuss how different oxidative post-translational modifications of aconitase impact the different functions of aconitases, and (4) argue how these proteins might function as redox sensors within different cellular compartments, regulating citrate concentration and efflux from mitochondria, iron availability in the cytosol, and cellular oxidant production.
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Affiliation(s)
- Laura Castro
- Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Av. General Flores 2125, 11800 Montevideo, Uruguay
- Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Av. General Flores 2125, 11800 Montevideo, Uruguay
| | - Verónica Tórtora
- Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Av. General Flores 2125, 11800 Montevideo, Uruguay
- Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Av. General Flores 2125, 11800 Montevideo, Uruguay
- Departamento de Educación Médica, Facultad de Medicina, Universidad de la República, Av. General Flores 2125, 11800, Montevideo, Uruguay
| | - Santiago Mansilla
- Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Av. General Flores 2125, 11800 Montevideo, Uruguay
- Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Av. General Flores 2125, 11800 Montevideo, Uruguay
| | - Rafael Radi
- Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Av. General Flores 2125, 11800 Montevideo, Uruguay
- Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Av. General Flores 2125, 11800 Montevideo, Uruguay
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26
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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: 74] [Impact Index Per Article: 14.8] [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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27
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Alfedi G, Luffarelli R, Condò I, Pedini G, Mannucci L, Massaro DS, Benini M, Toschi N, Alaimo G, Panarello L, Pacini L, Fortuni S, Serio D, Malisan F, Testi R, Rufini A. Drug repositioning screening identifies etravirine as a potential therapeutic for friedreich's ataxia. Mov Disord 2019; 34:323-334. [PMID: 30624801 DOI: 10.1002/mds.27604] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 10/31/2018] [Accepted: 11/05/2018] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Friedreich's ataxia is an autosomal-recessive cerebellar ataxia caused by mutation of the frataxin gene, resulting in decreased frataxin expression, mitochondrial dysfunction, and oxidative stress. Currently, no treatment is available for Friedreich's ataxia patients. Given that levels of residual frataxin critically affect disease severity, the main goal of a specific therapy for Friedreich's ataxia is to increase frataxin levels. OBJECTIVES With the aim to accelerate the development of a new therapy for Friedreich's ataxia, we took a drug repositioning approach to identify market-available drugs able to increase frataxin levels. METHODS Using a cell-based reporter assay to monitor variation in frataxin amount, we performed a high-throughput screening of a library containing 853 U.S. Food and Drug Administration-approved drugs. RESULTS Among the potentially interesting candidates isolated from the screening, we focused our attention on etravirine, an antiviral drug currently in use as an anti-human immunodeficiency virus therapy. Here, we show that etravirine can promote a significant increase in frataxin levels in cells derived from Friedreich's ataxia patients, by enhancing frataxin messenger RNA translation. Importantly, frataxin accumulation in treated patient cell lines is comparable to frataxin levels in unaffected carrier cells, suggesting that etravirine could be therapeutically relevant. Indeed, etravirine treatment restores the activity of the iron-sulphur cluster containing enzyme aconitase and confers resistance to oxidative stress in cells derived from Friedreich's ataxia patients. CONCLUSIONS Considering its excellent safety profile along with its ability to increase frataxin levels and correct some of the disease-related defects, etravirine represents a promising candidate as a therapeutic for Friedreich's ataxia. © 2019 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Giulia Alfedi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Riccardo Luffarelli
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Ivano Condò
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Giorgia Pedini
- Laboratory of Molecular Neurobiology, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Liliana Mannucci
- Laboratory of Molecular Neurobiology, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Damiano S Massaro
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Monica Benini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
- Fratagene Therapeutics Srl, Rome, Italy
| | - Nicola Toschi
- Medical Physics Section, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging and Harvard Medical School, Boston, Massachusetts, USA
| | - Giorgia Alaimo
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
- Fratagene Therapeutics Srl, Rome, Italy
| | - Luca Panarello
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Laura Pacini
- Laboratory of Molecular Neurobiology, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Silvia Fortuni
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Dario Serio
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Florence Malisan
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Roberto Testi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
- Fratagene Therapeutics Srl, Rome, Italy
| | - Alessandra Rufini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
- Fratagene Therapeutics Srl, Rome, Italy
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28
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Llorens JV, Soriano S, Calap-Quintana P, Gonzalez-Cabo P, Moltó MD. The Role of Iron in Friedreich's Ataxia: Insights From Studies in Human Tissues and Cellular and Animal Models. Front Neurosci 2019; 13:75. [PMID: 30833885 PMCID: PMC6387962 DOI: 10.3389/fnins.2019.00075] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 01/23/2019] [Indexed: 12/12/2022] Open
Abstract
Friedreich's ataxia (FRDA) is a rare early-onset degenerative disease that affects both the central and peripheral nervous systems, and other extraneural tissues, mainly the heart and endocrine pancreas. This disorder progresses as a mixed sensory and cerebellar ataxia, primarily disturbing the proprioceptive pathways in the spinal cord, peripheral nerves and nuclei of the cerebellum. FRDA is an inherited disease with an autosomal recessive pattern caused by an insufficient amount of the nuclear-encoded mitochondrial protein frataxin, which is an essential and highly evolutionary conserved protein whose deficit results in iron metabolism dysregulation and mitochondrial dysfunction. The first experimental evidence connecting frataxin with iron homeostasis came from Saccharomyces cerevisiae; iron accumulates in the mitochondria of yeast with deletion of the frataxin ortholog gene. This finding was soon linked to previous observations of iron deposits in the hearts of FRDA patients and was later reported in animal models of the disease. Despite advances made in the understanding of FRDA pathophysiology, the role of iron in this disease has not yet been completely clarified. Some of the questions still unresolved include the molecular mechanisms responsible for the iron accumulation and iron-mediated toxicity. Here, we review the contribution of the cellular and animal models of FRDA and relevance of the studies using FRDA patient samples to gain knowledge about these issues. Mechanisms of mitochondrial iron overload are discussed considering the potential roles of frataxin in the major mitochondrial metabolic pathways that use iron. We also analyzed the effect of iron toxicity on neuronal degeneration in FRDA by reactive oxygen species (ROS)-dependent and ROS-independent mechanisms. Finally, therapeutic strategies based on the control of iron toxicity are considered.
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Affiliation(s)
- José Vicente Llorens
- Department of Genetics, Faculty of Biological Sciences, University of Valencia, Valencia, Spain
- Unit for Psychiatry and Neurodegenerative Diseases, Biomedical Research Institute INCLIVA, Valencia, Spain
| | - Sirena Soriano
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX, United States
| | - Pablo Calap-Quintana
- Department of Genetics, Faculty of Biological Sciences, University of Valencia, Valencia, Spain
- Unit for Psychiatry and Neurodegenerative Diseases, Biomedical Research Institute INCLIVA, Valencia, Spain
| | - Pilar Gonzalez-Cabo
- Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain
- Center of Biomedical Network Research on Rare Diseases CIBERER, Valencia, Spain
- Associated Unit for Rare Diseases INCLIVA-CIPF, Biomedical Research Institute INCLIVA, Valencia, Spain
| | - María Dolores Moltó
- Department of Genetics, Faculty of Biological Sciences, University of Valencia, Valencia, Spain
- Unit for Psychiatry and Neurodegenerative Diseases, Biomedical Research Institute INCLIVA, Valencia, Spain
- Center of Biomedical Network Research on Mental Health CIBERSAM, Valencia, Spain
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Abstract
Friedreich's ataxia (FRDA) is a degenerative disease that affects both the central and the peripheral nervous systems and non-neural tissues including, mainly, heart, and endocrine pancreas. It is an autosomal recessive disease caused by a GAA triplet-repeat localized within an Alu sequence element in intron 1 of frataxin (FXN) gene, which encodes a mitochondrial protein FXN. This protein is essential for mitochondrial function by the involvement of iron-sulfur cluster biogenesis. The effects of its deficiency also include disruption of cellular, particularly mitochondrial, iron homeostasis, i.e., relatively more iron accumulated in mitochondria and less iron presented in cytosol. Though iron toxicity is commonly thought to be mediated via Fenton reaction, oxidative stress seems not to be the main problem to result in detrimental effects on cell survival, particularly neuron survival. Therefore, the basic research on FXN function is urgently demanded to understand the disease. This chapter focuses on the outcome of FXN expression, regulation, and function in cellular or animal models of FRDA and on iron pathophysiology in the affected tissues. Finally, therapeutic strategies based on the control of iron toxicity and iron cellular redistribution are considered. The combination of multiple therapeutic targets including iron, oxidative stress, mitochondrial function, and FXN regulation is also proposed.
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Affiliation(s)
- Kuanyu Li
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, People's Republic of China.
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30
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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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31
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Alsina D, Purroy R, Ros J, Tamarit J. Iron in Friedreich Ataxia: A Central Role in the Pathophysiology or an Epiphenomenon? Pharmaceuticals (Basel) 2018; 11:E89. [PMID: 30235822 PMCID: PMC6161073 DOI: 10.3390/ph11030089] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 09/15/2018] [Accepted: 09/17/2018] [Indexed: 12/16/2022] Open
Abstract
Friedreich ataxia is a neurodegenerative disease with an autosomal recessive inheritance. In most patients, the disease is caused by the presence of trinucleotide GAA expansions in the first intron of the frataxin gene. These expansions cause the decreased expression of this mitochondrial protein. Many evidences indicate that frataxin deficiency causes the deregulation of cellular iron homeostasis. In this review, we will discuss several hypotheses proposed for frataxin function, their caveats, and how they could provide an explanation for the deregulation of iron homeostasis found in frataxin-deficient cells. We will also focus on the potential mechanisms causing cellular dysfunction in Friedreich Ataxia and on the potential use of the iron chelator deferiprone as a therapeutic agent for this disease.
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Affiliation(s)
- David Alsina
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, 25198 Lleida, Spain.
| | - Rosa Purroy
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, 25198 Lleida, Spain.
| | - Joaquim Ros
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, 25198 Lleida, Spain.
| | - Jordi Tamarit
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, 25198 Lleida, Spain.
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32
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Khdour OM, Bandyopadhyay I, Visavadiya NP, Roy Chowdhury S, Hecht SM. Phenothiazine antioxidants increase mitochondrial biogenesis and frataxin levels in Friedreich's ataxia cells. MEDCHEMCOMM 2018; 9:1491-1501. [PMID: 30288223 DOI: 10.1039/c8md00274f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 07/25/2018] [Indexed: 12/13/2022]
Abstract
Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease that is linked to transcriptional repression of the nuclear FXN gene encoding the essential mitochondrial protein frataxin (FXN). Compounds that increase frataxin levels may enable effective therapeutic intervention for blunting disease progression. Recently, we showed that lipophilic methylene violet (MV) and methylene blue (MB) analogues both conferred benefit to cultured FRDA cells in several regards, including ROS suppression, maintenance of mitochondrial membrane potential and increased ATP production. Some of the MB analogues were also shown to promote increased frataxin levels and mitochondrial biogenesis. Presently, we report that two of the MV analogues studied previously (1 and 2) also increased frataxin levels and mitochondrial biogenesis significantly. Because the substitution pattern in the two series of compounds was not the same, we also prepared new MV derivatives having the same substitution pattern as the original MB derivatives studied to enable a more direct comparison. Two of the new MV compounds, 4b and 6b, exhibited enhanced antioxidant capability, increased frataxin levels and mitochondrial biogenesis, and improved aconitase activity. These encouraging findings demonstrated that the MV analogues had better overall activity with less cytotoxicity.
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Affiliation(s)
- Omar M Khdour
- Biodesign Center for BioEnergetics , Arizona State University , Tempe , AZ 85287 , USA .
| | - Indrajit Bandyopadhyay
- Biodesign Center for BioEnergetics , Arizona State University , Tempe , AZ 85287 , USA . .,School of Molecular Sciences , Arizona State University , Tempe , AZ 85287 , USA
| | - Nishant P Visavadiya
- Biodesign Center for BioEnergetics , Arizona State University , Tempe , AZ 85287 , USA .
| | - Sandipan Roy Chowdhury
- Biodesign Center for BioEnergetics , Arizona State University , Tempe , AZ 85287 , USA . .,School of Molecular Sciences , Arizona State University , Tempe , AZ 85287 , USA
| | - Sidney M Hecht
- Biodesign Center for BioEnergetics , Arizona State University , Tempe , AZ 85287 , USA . .,School of Molecular Sciences , Arizona State University , Tempe , AZ 85287 , USA
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33
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Khdour OM, Bandyopadhyay I, Chowdhury SR, Visavadiya NP, Hecht SM. Lipophilic methylene blue analogues enhance mitochondrial function and increase frataxin levels in a cellular model of Friedreich's ataxia. Bioorg Med Chem 2018; 26:3359-3369. [PMID: 29773347 DOI: 10.1016/j.bmc.2018.05.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 04/25/2018] [Accepted: 05/03/2018] [Indexed: 01/31/2023]
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disorder resulting from reduced expression of the protein frataxin (FXN). Although its function is not fully understood, frataxin appears to help assemble iron sulfur clusters; these are critical for the function of many proteins, including those needed for mitochondrial energy production. Finding ways to increase FXN levels has been a major therapeutic strategy for this disease. Previously, we described a novel series of methylene violet analogues and their structural optimization as potential therapeutic agents for neurodegenerative and mitochondrial disorders. Presently, a series of methylene blue analogues has been synthesized and characterized for their in vitro biochemical and biological properties in cultured Friedreich's ataxia lymphocytes. Favorable methylene blue analogues were shown to increase frataxin levels and mitochondrial biogenesis, and to improve aconitase activity. The analogues were found to be good ROS scavengers, and able to protect cultured FRDA lymphocytes from oxidative stress resulting from inhibition of complex I and from glutathione depletion. The analogues also preserved mitochondrial membrane potential and augmented ATP production. Our results suggest that analogue 5, emerging from the initial structure of the parent compound methylene blue (MB), represents a promising lead structure and lacks the cytotoxicity associated with the parent compound MB.
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Affiliation(s)
- Omar M Khdour
- Biodesign Center for BioEnergetics, and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA.
| | - Indrajit Bandyopadhyay
- Biodesign Center for BioEnergetics, and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Sandipan Roy Chowdhury
- Biodesign Center for BioEnergetics, and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Nishant P Visavadiya
- Biodesign Center for BioEnergetics, and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Sidney M Hecht
- Biodesign Center for BioEnergetics, and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
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34
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Monnier V, Llorens JV, Navarro JA. Impact of Drosophila Models in the Study and Treatment of Friedreich's Ataxia. Int J Mol Sci 2018; 19:E1989. [PMID: 29986523 PMCID: PMC6073496 DOI: 10.3390/ijms19071989] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 06/26/2018] [Accepted: 07/03/2018] [Indexed: 02/07/2023] Open
Abstract
Drosophila melanogaster has been for over a century the model of choice of several neurobiologists to decipher the formation and development of the nervous system as well as to mirror the pathophysiological conditions of many human neurodegenerative diseases. The rare disease Friedreich’s ataxia (FRDA) is not an exception. Since the isolation of the responsible gene more than two decades ago, the analysis of the fly orthologue has proven to be an excellent avenue to understand the development and progression of the disease, to unravel pivotal mechanisms underpinning the pathology and to identify genes and molecules that might well be either disease biomarkers or promising targets for therapeutic interventions. In this review, we aim to summarize the collection of findings provided by the Drosophila models but also to go one step beyond and propose the implications of these discoveries for the study and cure of this disorder. We will present the physiological, cellular and molecular phenotypes described in the fly, highlighting those that have given insight into the pathology and we will show how the ability of Drosophila to perform genetic and pharmacological screens has provided valuable information that is not easily within reach of other cellular or mammalian models.
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Affiliation(s)
- Véronique Monnier
- Unité de Biologie Fonctionnelle et Adaptative (BFA), Sorbonne Paris Cité, Université Paris Diderot, UMR8251 CNRS, 75013 Paris, France.
| | - Jose Vicente Llorens
- Department of Genetics, University of Valencia, Campus of Burjassot, 96100 Valencia, Spain.
| | - Juan Antonio Navarro
- Lehrstuhl für Entwicklungsbiologie, Universität Regensburg, 93040 Regensburg, Germany.
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35
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Belevich G, Belevich N, Knuuti J, Verkhovskaya M. Ca2+ stabilization of respiratory complex I from Escherichia coli. FEMS Microbiol Lett 2018; 365:4969679. [PMID: 29668960 DOI: 10.1093/femsle/fny097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/11/2018] [Indexed: 11/13/2022] Open
Abstract
Stability of the membrane-bound and purified H+-translocating NADH:ubiquinone oxidoreductase, Complex I, was studied. The loss of the enzyme activity is strongly increased by alkaline pH and dilution of the sample. Complex I inactivation is prevented specifically by a low concentration of Ca2+ and/or an intracellular stabilization factor (ISF). The action of both, Ca2+ and ISF, on Complex I stability is interdependent. The data are discussed in terms of a release of structural Ca2+ as a reason for Complex I decay and an effect of ISF on the affinity and/or accessibility of Ca2+-binding site.
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Affiliation(s)
- Galina Belevich
- Institute of Biotechnology, University of Helsinki, PO Box 65, Helsinki FIN-00014, Finland
| | - Nikolai Belevich
- Institute of Biotechnology, University of Helsinki, PO Box 65, Helsinki FIN-00014, Finland
| | - Juho Knuuti
- Institute of Biotechnology, University of Helsinki, PO Box 65, Helsinki FIN-00014, Finland
| | - Marina Verkhovskaya
- Institute of Biotechnology, University of Helsinki, PO Box 65, Helsinki FIN-00014, Finland
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36
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Calap-Quintana P, Navarro JA, González-Fernández J, Martínez-Sebastián MJ, Moltó MD, Llorens JV. Drosophila melanogaster Models of Friedreich's Ataxia. BIOMED RESEARCH INTERNATIONAL 2018; 2018:5065190. [PMID: 29850527 PMCID: PMC5907503 DOI: 10.1155/2018/5065190] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 01/29/2018] [Accepted: 02/28/2018] [Indexed: 11/17/2022]
Abstract
Friedreich's ataxia (FRDA) is a rare inherited recessive disorder affecting the central and peripheral nervous systems and other extraneural organs such as the heart and pancreas. This incapacitating condition usually manifests in childhood or adolescence, exhibits an irreversible progression that confines the patient to a wheelchair, and leads to early death. FRDA is caused by a reduced level of the nuclear-encoded mitochondrial protein frataxin due to an abnormal GAA triplet repeat expansion in the first intron of the human FXN gene. FXN is evolutionarily conserved, with orthologs in essentially all eukaryotes and some prokaryotes, leading to the development of experimental models of this disease in different organisms. These FRDA models have contributed substantially to our current knowledge of frataxin function and the pathogenesis of the disease, as well as to explorations of suitable treatments. Drosophila melanogaster, an organism that is easy to manipulate genetically, has also become important in FRDA research. This review describes the substantial contribution of Drosophila to FRDA research since the characterization of the fly frataxin ortholog more than 15 years ago. Fly models have provided a comprehensive characterization of the defects associated with frataxin deficiency and have revealed genetic modifiers of disease phenotypes. In addition, these models are now being used in the search for potential therapeutic compounds for the treatment of this severe and still incurable disease.
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Affiliation(s)
- P. Calap-Quintana
- Department of Genetics, University of Valencia, Campus of Burjassot, Valencia, Spain
| | - J. A. Navarro
- Institute of Zoology, University of Regensburg, Regensburg, Germany
| | - J. González-Fernández
- Department of Genetics, University of Valencia, Campus of Burjassot, Valencia, Spain
- Biomedical Research Institute INCLIVA, Valencia, Spain
| | | | - M. D. Moltó
- Department of Genetics, University of Valencia, Campus of Burjassot, Valencia, Spain
- Biomedical Research Institute INCLIVA, Valencia, Spain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain
| | - J. V. Llorens
- Department of Genetics, University of Valencia, Campus of Burjassot, Valencia, Spain
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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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Castro IH, Ferrari A, Herrera MG, Noguera ME, Maso L, Benini M, Rufini A, Testi R, Costantini P, Santos J. Biophysical characterisation of the recombinant human frataxin precursor. FEBS Open Bio 2018; 8:390-405. [PMID: 29511616 PMCID: PMC5832983 DOI: 10.1002/2211-5463.12376] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/25/2017] [Accepted: 12/27/2017] [Indexed: 11/10/2022] Open
Abstract
Friedreich's ataxia is a disease caused by a decrease in the levels of expression or loss of functionality of the mitochondrial protein frataxin (FXN). The development of an active and stable recombinant variant of FXN is important for protein replacement therapy. Although valuable data about the mature form FXN81-210 has been collected, not enough information is available about the conformation of the frataxin precursor (FXN1-210). We investigated the conformation, stability and function of a recombinant precursor variant (His6-TAT-FXN1-210), which includes a TAT peptide in the N-terminal region to assist with transport across cell membranes. His6-TAT-FXN1-210 was expressed in Escherichia coli and conditions were found for purifying folded protein free of aggregation, oxidation or degradation, even after freezing and thawing. The protein was found to be stable and monomeric, with the N-terminal stretch (residues 1-89) mostly unstructured and the C-terminal domain properly folded. The experimental data suggest a complex picture for the folding process of full-length frataxin in vitro: the presence of the N-terminal region increased the tendency of FXN to aggregate at high temperatures but this could be avoided by the addition of low concentrations of GdmCl. The purified precursor was translocated through cell membranes. In addition, immune response against His6-TAT-FXN1-210 was measured, suggesting that the C-terminal fragment was not immunogenic at the assayed protein concentrations. Finally, the recognition of recombinant FXN by cellular proteins was studied to evaluate its functionality. In this regard, cysteine desulfurase NFS1/ISD11/ISCU was activated in vitro by His6-TAT-FXN1-210. Moreover, the results showed that His6-TAT-FXN1-210 can be ubiquitinated in vitro by the recently identified frataxin E3 ligase RNF126, in a similar way as the FXN1-210, suggesting that the His6-TAT extension does not interfere with the ubiquitination machinery.
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Affiliation(s)
- Ignacio Hugo Castro
- Institute of Biological Chemistry and Physicochemistry Dr Alejandro Paladini (UBA-CONICET) University of Buenos Aires Argentina
| | - Alejandro Ferrari
- Institute of Biological Chemistry and Physicochemistry Dr Alejandro Paladini (UBA-CONICET) University of Buenos Aires Argentina
| | - María Georgina Herrera
- Institute of Biological Chemistry and Physicochemistry Dr Alejandro Paladini (UBA-CONICET) University of Buenos Aires Argentina
| | - Martín Ezequiel Noguera
- Institute of Biological Chemistry and Physicochemistry Dr Alejandro Paladini (UBA-CONICET) University of Buenos Aires Argentina
| | - Lorenzo Maso
- Department of Biology University of Padova Italy
| | - Monica Benini
- Laboratory of Signal Transduction Department of Biomedicine and Prevention University of Rome ''Tor Vergata'' Italy.,Fratagene Therapeutics srl Rome Italy
| | - Alessandra Rufini
- Laboratory of Signal Transduction Department of Biomedicine and Prevention University of Rome ''Tor Vergata'' Italy.,Fratagene Therapeutics srl Rome Italy
| | - Roberto Testi
- Laboratory of Signal Transduction Department of Biomedicine and Prevention University of Rome ''Tor Vergata'' Italy.,Fratagene Therapeutics srl Rome Italy
| | | | - Javier Santos
- Institute of Biological Chemistry and Physicochemistry Dr Alejandro Paladini (UBA-CONICET) University of Buenos Aires Argentina
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Ahlgren EC, Fekry M, Wiemann M, Söderberg CA, Bernfur K, Gakh O, Rasmussen M, Højrup P, Emanuelsson C, Isaya G, Al-Karadaghi S. Iron-induced oligomerization of human FXN81-210 and bacterial CyaY frataxin and the effect of iron chelators. PLoS One 2017; 12:e0188937. [PMID: 29200434 PMCID: PMC5714350 DOI: 10.1371/journal.pone.0188937] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 11/15/2017] [Indexed: 12/12/2022] Open
Abstract
Patients suffering from the progressive neurodegenerative disease Friedreich's ataxia have reduced expression levels of the protein frataxin. Three major isoforms of human frataxin have been identified, FXN42-210, FXN56-210 and FXN81-210, of which FXN81-210 is considered to be the mature form. Both long forms, FXN42-210 and FXN56-210, have been shown to spontaneously form oligomeric particles stabilized by the extended N-terminal sequence. The short variant FXN81-210, on other hand, has only been observed in the monomeric state. However, a highly homologous E. coli frataxin CyaY, which also lacks an N-terminal extension, has been shown to oligomerize in the presence of iron. To explore the mechanisms of stabilization of short variant frataxin oligomers we compare here the effect of iron on the oligomerization of CyaY and FXN81-210. Using dynamic light scattering, small-angle X-ray scattering, electron microscopy (EM) and cross linking mass spectrometry (MS), we show that at aerobic conditions in the presence of iron both FXN81-210 and CyaY form oligomers. However, while CyaY oligomers are stable over time, FXN81-210 oligomers are unstable and dissociate into monomers after about 24 h. EM and MS studies suggest that within the oligomers FXN81-210 and CyaY monomers are packed in a head-to-tail fashion in ring-shaped structures with potential iron-binding sites located at the interface between monomers. The higher stability of CyaY oligomers can be explained by a higher number of acidic residues at the interface between monomers, which may result in a more stable iron binding. We also show that CyaY oligomers may be dissociated by ferric iron chelators deferiprone and DFO, as well as by the ferrous iron chelator BIPY. Surprisingly, deferiprone and DFO stimulate FXN81-210 oligomerization, while BIPY does not show any effect on oligomerization in this case. The results suggest that FXN81-210 oligomerization is primarily driven by ferric iron, while both ferric and ferrous iron participate in CyaY oligomer stabilization. Analysis of the amino acid sequences of bacterial and eukaryotic frataxins suggests that variations in the position of the acidic residues in helix 1, β-strand 1 and the loop between them may control the mode of frataxin oligomerization.
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Affiliation(s)
- Eva-Christina Ahlgren
- Center for Molecular Protein Science, Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Mostafa Fekry
- Center for Molecular Protein Science, Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
- Biophysics Department, Faculty of Science, Cairo University, Giza, Egypt
| | - Mathias Wiemann
- Center for Molecular Protein Science, Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Christopher A. Söderberg
- Center for Molecular Protein Science, Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Katja Bernfur
- Center for Molecular Protein Science, Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Olex Gakh
- Departments of Pediatric and Adolescent Medicine and Biochemistry and Molecular Biology, Mayo Clinic, College of Medicine, Rochester, Minnesota, United States of America
| | - Morten Rasmussen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Peter Højrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Cecilia Emanuelsson
- Center for Molecular Protein Science, Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Grazia Isaya
- Departments of Pediatric and Adolescent Medicine and Biochemistry and Molecular Biology, Mayo Clinic, College of Medicine, Rochester, Minnesota, United States of America
| | - Salam Al-Karadaghi
- Center for Molecular Protein Science, Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
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SAXS and stability studies of iron-induced oligomers of bacterial frataxin CyaY. PLoS One 2017; 12:e0184961. [PMID: 28931050 PMCID: PMC5607177 DOI: 10.1371/journal.pone.0184961] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 09/04/2017] [Indexed: 01/19/2023] Open
Abstract
Frataxin is a highly conserved protein found in both prokaryotes and eukaryotes. It is involved in several central functions in cells, which include iron delivery to biochemical processes, such as heme synthesis, assembly of iron-sulfur clusters (ISC), storage of surplus iron in conditions of iron overload, and repair of ISC in aconitase. Frataxin from different organisms has been shown to undergo iron-dependent oligomerization. At least two different classes of oligomers, with different modes of oligomer packing and stabilization, have been identified. Here, we continue our efforts to explore the factors that control the oligomerization of frataxin from different organisms, and focus on E. coli frataxin CyaY. Using small-angle X-ray scattering (SAXS), we show that higher iron-to-protein ratios lead to larger oligomeric species, and that oligomerization proceeds in a linear fashion as a results of iron oxidation. Native mass spectrometry and online size-exclusion chromatography combined with SAXS show that a dimer is the most common form of CyaY in the presence of iron at atmospheric conditions. Modeling of the dimer using the SAXS data confirms the earlier proposed head-to-tail packing arrangement of monomers. This packing mode brings several conserved acidic residues into close proximity to each other, creating an environment for metal ion binding and possibly even mineralization. Together with negative-stain electron microscopy, the experiments also show that trimers, tetramers, pentamers, and presumably higher-order oligomers may exist in solution. Nano-differential scanning fluorimetry shows that the oligomers have limited stability and may easily dissociate at elevated temperatures. The factors affecting the possible oligomerization mode are discussed.
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42
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Circulating miR-323-3p is a biomarker for cardiomyopathy and an indicator of phenotypic variability in Friedreich's ataxia patients. Sci Rep 2017; 7:5237. [PMID: 28701783 PMCID: PMC5507909 DOI: 10.1038/s41598-017-04996-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 05/23/2017] [Indexed: 11/12/2022] Open
Abstract
MicroRNAs (miRNAs) are noncoding RNAs that contribute to gene expression modulation by regulating important cellular pathways. In this study, we used small RNA sequencing to identify a series of circulating miRNAs in blood samples taken from Friedreich’s ataxia patients. We were thus able to develop a miRNA biomarker signature to differentiate Friedreich’s ataxia (FRDA) patients from healthy people. Most research on FDRA has focused on understanding the role of frataxin in the mitochondria, and a whole molecular view of pathological pathways underlying FRDA therefore remains to be elucidated. We found seven differentially expressed miRNAs, and we propose that these miRNAs represent key mechanisms in the modulation of several signalling pathways that regulate the physiopathology of FRDA. If this is the case, miRNAs can be used to characterize phenotypic variation in FRDA and stratify patients’ risk of cardiomyopathy. In this study, we identify miR-323-3p as a candidate marker for phenotypic differentiation in FRDA patients suffering from cardiomyopathy. We propose the use of dynamic miRNAs as biomarkers for phenotypic characterization and prognosis of FRDA.
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Benini M, Fortuni S, Condò I, Alfedi G, Malisan F, Toschi N, Serio D, Massaro DS, Arcuri G, Testi R, Rufini A. E3 Ligase RNF126 Directly Ubiquitinates Frataxin, Promoting Its Degradation: Identification of a Potential Therapeutic Target for Friedreich Ataxia. Cell Rep 2017; 18:2007-2017. [PMID: 28228265 PMCID: PMC5329121 DOI: 10.1016/j.celrep.2017.01.079] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 12/14/2016] [Accepted: 01/29/2017] [Indexed: 12/21/2022] Open
Abstract
Friedreich ataxia (FRDA) is a severe genetic neurodegenerative disease caused by reduced expression of the mitochondrial protein frataxin. To date, there is no therapy to treat this condition. The amount of residual frataxin critically affects the severity of the disease; thus, attempts to restore physiological frataxin levels are considered therapeutically relevant. Frataxin levels are controlled by the ubiquitin-proteasome system; therefore, inhibition of the frataxin E3 ligase may represent a strategy to achieve an increase in frataxin levels. Here, we report the identification of the RING E3 ligase RNF126 as the enzyme that specifically mediates frataxin ubiquitination and targets it for degradation. RNF126 interacts with frataxin and promotes its ubiquitination in a catalytic activity-dependent manner, both in vivo and in vitro. Most importantly, RNF126 depletion results in frataxin accumulation in cells derived from FRDA patients, highlighting the relevance of RNF126 as a new therapeutic target for Friedreich ataxia.
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Affiliation(s)
- Monica Benini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy; Fratagene Therapeutics Srl, Viale dei Campioni 8, 00144 Rome, Italy
| | - Silvia Fortuni
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Ivano Condò
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Giulia Alfedi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Florence Malisan
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Nicola Toschi
- Medical Physics Section, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy; Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging and Harvard Medical School, Boston, MA 02115, USA
| | - Dario Serio
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy; Fratagene Therapeutics Srl, Viale dei Campioni 8, 00144 Rome, Italy
| | - Damiano Sergio Massaro
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Gaetano Arcuri
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy
| | - Roberto Testi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy; Fratagene Therapeutics Srl, Viale dei Campioni 8, 00144 Rome, Italy
| | - Alessandra Rufini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, 00133 Rome, Italy; Fratagene Therapeutics Srl, Viale dei Campioni 8, 00144 Rome, Italy.
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Marcus D, Lichtenstein M, Cohen N, Hadad R, Erlich-Hadad T, Greif H, Lorberboum-Galski H. Heterologous mitochondrial targeting sequences can deliver functional proteins into mitochondria. Int J Biochem Cell Biol 2016; 81:48-56. [PMID: 27771440 DOI: 10.1016/j.biocel.2016.10.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 10/13/2016] [Accepted: 10/18/2016] [Indexed: 01/23/2023]
Abstract
Mitochondrial Targeting Sequences (MTSs) are responsible for trafficking nuclear-encoded proteins into mitochondria. Once entering the mitochondria, the MTS is recognized and cleaved off. Some MTSs are long and undergo two-step processing, as in the case of the human frataxin (FXN) protein (80aa), implicated in Friedreich's ataxia (FA). Therefore, we chose the FXN protein to examine whether nuclear-encoded mitochondrial proteins can efficiently be targeted via a heterologous MTS (hMTS) and deliver a functional protein into mitochondria. We examined three hMTSs; that of citrate synthase (cs), lipoamide deydrogenase (LAD) and C6ORF66 (ORF), as classically MTS sequences, known to be removed by one-step processing, to deliver FXN into mitochondria, in the form of fusion proteins. We demonstrate that using hMTSs for delivering FXN results in the production of 4-5-fold larger amounts of the fusion proteins, and at 4-5-fold higher concentrations. Moreover, hMTSs delivered a functional FXN protein into the mitochondria even more efficiently than the native MTSfxn, as evidenced by the rescue of FA patients' cells from oxidative stress; demonstrating a 18%-54% increase in cell survival; and a 13%-33% increase in ATP levels, as compared to the fusion protein carrying the native MTS. One fusion protein with MTScs increased aconitase activity within patients' cells, by 400-fold. The implications form our studies are of vast importance for both basic and translational research of mitochondrial proteins as any mitochondrial protein can be delivered efficiently by an hMTS. Moreover, effective targeting of functional proteins is important for restoration of mitochondrial function and treatment of related disorders.
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Affiliation(s)
- Dana Marcus
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Michal Lichtenstein
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Natali Cohen
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Rita Hadad
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Tal Erlich-Hadad
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | | | - Haya Lorberboum-Galski
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel.
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Tamarit J, Obis È, Ros J. Oxidative stress and altered lipid metabolism in Friedreich ataxia. Free Radic Biol Med 2016; 100:138-146. [PMID: 27296838 DOI: 10.1016/j.freeradbiomed.2016.06.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 06/07/2016] [Accepted: 06/10/2016] [Indexed: 12/31/2022]
Abstract
Friedreich ataxia is a genetic disease caused by the deficiency of frataxin, a mitochondrial protein. Frataxin deficiency impacts in the cell physiology at several levels. One of them is oxidative stress with consequences in terms of protein dysfunctions and metabolic alterations. Among others, alterations in lipid metabolism have been observed in several models of the disease. In this review we summarize the current knowledge of the molecular basis of the disease, the relevance of oxidative stress and the therapeutic strategies based on reduction of mitochondrial reactive oxygen species production. Finally, we will focus the interest in alterations of lipid metabolism as a consequence of mitochondrial dysfunction and describe the therapeutic approaches based on targeting lipid metabolism.
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Affiliation(s)
- Jordi Tamarit
- Departament de Ciències Mèdiques Bàsiques, IRB-Lleida, Universitat de Lleida, Lleida, Spain
| | - Èlia Obis
- Departament de Ciències Mèdiques Bàsiques, IRB-Lleida, Universitat de Lleida, Lleida, Spain
| | - Joaquim Ros
- Departament de Ciències Mèdiques Bàsiques, IRB-Lleida, Universitat de Lleida, Lleida, Spain.
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46
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Galea CA, Huq A, Lockhart PJ, Tai G, Corben LA, Yiu EM, Gurrin LC, Lynch DR, Gelbard S, Durr A, Pousset F, Parkinson M, Labrum R, Giunti P, Perlman SL, Delatycki MB, Evans-Galea MV. Compound heterozygous FXN mutations and clinical outcome in friedreich ataxia. Ann Neurol 2016; 79:485-95. [PMID: 26704351 DOI: 10.1002/ana.24595] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 02/01/2023]
Abstract
OBJECTIVE Friedreich ataxia (FRDA) is an inherited neurodegenerative disease characterized by ataxia and cardiomyopathy. Homozygous GAA trinucleotide repeat expansions in the first intron of FXN occur in 96% of affected individuals and reduce frataxin expression. Remaining individuals are compound heterozygous for a GAA expansion and a FXN point/insertion/deletion mutation. We examined disease-causing mutations and the impact on frataxin structure/function and clinical outcome in FRDA. METHODS We compared clinical information from 111 compound heterozygotes and 131 individuals with homozygous expansions. Frataxin mutations were examined using structural modeling, stability analyses and systematic literature review, and categorized into four groups: (1) homozygous expansions, and three compound heterozygote groups; (2) null (no frataxin produced); (3) moderate/strong impact; and (4) minimal impact. Mean age of onset and the presence of cardiomyopathy and diabetes mellitus were compared using regression analyses. RESULTS Mutations in the hydrophobic core of frataxin affected stability whereas surface residue mutations affected interactions with iron sulfur cluster assembly and heme biosynthetic proteins. The null group of compound heterozygotes had significantly earlier age of onset and increased diabetes mellitus, compared to the homozygous expansion group. There were no significant differences in mean age of onset between homozygotes and the minimal and moderate/strong impact groups. INTERPRETATION In compound heterozygotes, expression of partially functional mutant frataxin delays age of onset and reduces diabetes mellitus, compared to those with no frataxin expression from the non-expanded allele. This integrated analysis of categorized frataxin mutations and their correlation with clinical outcome provide a definitive resource for investigating disease pathogenesis in FRDA.
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Affiliation(s)
- Charles A Galea
- Medicinal Chemistry and Drug Delivery, Disposition and Dynamics (D4), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Aamira Huq
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Paul J Lockhart
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Geneieve Tai
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Louise A Corben
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- School of Psychological Sciences, Monash University, Clayton, Victoria, Australia
| | - Eppie M Yiu
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Neurology, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Lyle C Gurrin
- Center for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - David R Lynch
- Departments of Neurology and Pediatrics, University of Pennsylvania School of Medicine and The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Sarah Gelbard
- Departments of Neurology and Pediatrics, University of Pennsylvania School of Medicine and The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Alexandra Durr
- APHP, Department of Genetics and Cytogenetics, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
- Institut du Cerveau et de la Moelle épinière (ICM), Pitié-Salpêtrière University Hospital, Paris, France
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S_1127, ICM, F-75013, France
| | - Francoise Pousset
- APHP, Cardiology Department, AP-HP Pitie-Salpétrière Hospital, Paris, France
| | - Michael Parkinson
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Robyn Labrum
- Department of Neurogenetics, University College London Hospital, Institute of Neurology, London, United Kingdom
| | - Paola Giunti
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
- Department of Neurogenetics, University College London Hospital, Institute of Neurology, London, United Kingdom
| | - Susan L Perlman
- Ataxia Center and Huntington Disease Center of Excellence, Department of Neurology, David Geffen School of Medicine at the University of California at Los Angeles, CA
| | - Martin B Delatycki
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- School of Psychological Sciences, Monash University, Clayton, Victoria, Australia
- Clinical Genetics, Austin Health, Heidelberg, Victoria, Australia
| | - Marguerite V Evans-Galea
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
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47
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Faraj SE, González-Lebrero RM, Roman EA, Santos J. Human Frataxin Folds Via an Intermediate State. Role of the C-Terminal Region. Sci Rep 2016; 6:20782. [PMID: 26856628 PMCID: PMC4746760 DOI: 10.1038/srep20782] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/12/2016] [Indexed: 11/30/2022] Open
Abstract
The aim of this study is to investigate the folding reaction of human frataxin, whose deficiency causes the neurodegenerative disease Friedreich's Ataxia (FRDA). The characterization of different conformational states would provide knowledge about how frataxin can be stabilized without altering its functionality. Wild-type human frataxin and a set of mutants, including two highly destabilized FRDA-associated variants were studied by urea-induced folding/unfolding in a rapid mixing device and followed by circular dichroism. The analysis clearly indicates the existence of an intermediate state (I) in the folding route with significant secondary structure content but relatively low compactness, compared with the native ensemble. However, at high NaCl concentrations I-state gains substantial compaction, and the unfolding barrier is strongly affected, revealing the importance of electrostatics in the folding mechanism. The role of the C-terminal region (CTR), the key determinant of frataxin stability, was also studied. Simulations consistently with experiments revealed that this stretch is essentially unstructured, in the most compact transition state ensemble (TSE2). The complete truncation of the CTR drastically destabilizes the native state without altering TSE2. Results presented here shed light on the folding mechanism of frataxin, opening the possibility of mutating it to generate hyperstable variants without altering their folding kinetics.
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Affiliation(s)
- Santiago E. Faraj
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Junín 956, 1113AAD, Buenos Aires, Argentina
| | - Rodolfo M. González-Lebrero
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Junín 956, 1113AAD, Buenos Aires, Argentina
| | - Ernesto A. Roman
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Junín 956, 1113AAD, Buenos Aires, Argentina
| | - Javier Santos
- Instituto de Química y Físico-Química Biológicas, Universidad de Buenos Aires, Junín 956, 1113AAD, Buenos Aires, Argentina
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48
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Faggianelli N, Puglisi R, Veneziano L, Romano S, Frontali M, Vannocci T, Fortuni S, Testi R, Pastore A. Analyzing the Effects of a G137V Mutation in the FXN Gene. Front Mol Neurosci 2015; 8:66. [PMID: 26635519 PMCID: PMC4658817 DOI: 10.3389/fnmol.2015.00066] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 10/23/2015] [Indexed: 12/15/2022] Open
Abstract
Reduced levels of frataxin, an essential mitochondrial protein involved in the regulation of iron-sulfur cluster biogenesis, are responsible for the recessive neurodegenerative Friedreich Ataxia (FRDA). Expansion of a GAA triplet in the first intron of the FRDA is essential for disease development which causes partial silencing of frataxin. In the vast majority of cases, patients are homozygotes for the expansion, but a small number of FRDA patients are heterozygotes for expansion and point mutations in the frataxin coding frame. In this study, we analyze the effects of a point mutation G137V. The patient P94–2, with a history of alcohol and drug abuse, showed a FRDA onset at the border between the classic and late onset phenotype. We applied a combination of biophysical and biochemical methods to characterize its effects on the structure, folding and activity of frataxin. Our study reveals no impairment of the structure or activity of the protein but a reduced folding stability. We suggest that the mutation causes misfolding of the native chain with consequent reduction of the protein concentration in the patient and discuss the possible mechanism of disease.
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Affiliation(s)
- Nathalie Faggianelli
- Department of Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London London, UK
| | - Rita Puglisi
- Department of Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London London, UK
| | | | - Silvia Romano
- Sant'Andrea Hospital, University of Rome La Sapienza Rome, Italy
| | | | - Tommaso Vannocci
- Department of Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London London, UK
| | - Silvia Fortuni
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata" Rome, Italy
| | - Roberto Testi
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata" Rome, Italy
| | - Annalisa Pastore
- Department of Basic and Clinical Neuroscience, Maurice Wohl Institute, King's College London London, UK
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49
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Cherubini F, Serio D, Guccini I, Fortuni S, Arcuri G, Condò I, Rufini A, Moiz S, Camerini S, Crescenzi M, Testi R, Malisan F. Src inhibitors modulate frataxin protein levels. Hum Mol Genet 2015; 24:4296-305. [PMID: 25948553 DOI: 10.1093/hmg/ddv162] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 04/30/2015] [Indexed: 12/19/2022] Open
Abstract
Defective expression of frataxin is responsible for the inherited, progressive degenerative disease Friedreich's Ataxia (FRDA). There is currently no effective approved treatment for FRDA and patients die prematurely. Defective frataxin expression causes critical metabolic changes, including redox imbalance and ATP deficiency. As these alterations are known to regulate the tyrosine kinase Src, we investigated whether Src might in turn affect frataxin expression. We found that frataxin can be phosphorylated by Src. Phosphorylation occurs primarily on Y118 and promotes frataxin ubiquitination, a signal for degradation. Accordingly, Src inhibitors induce accumulation of frataxin but are ineffective on a non-phosphorylatable frataxin-Y118F mutant. Importantly, all the Src inhibitors tested, some of them already in the clinic, increase frataxin expression and rescue the aconitase defect in frataxin-deficient cells derived from FRDA patients. Thus, Src inhibitors emerge as a new class of drugs able to promote frataxin accumulation, suggesting their possible use as therapeutics in FRDA.
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Affiliation(s)
- Fabio Cherubini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome, Italy
| | - Dario Serio
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome, Italy
| | - Ilaria Guccini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome, Italy
| | - Silvia Fortuni
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome, Italy, Fratagene Therapeutics Ltd, 22 Northumberland Rd, Dublin, Ireland and
| | - Gaetano Arcuri
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome, Italy
| | - Ivano Condò
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome, Italy
| | - Alessandra Rufini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome, Italy, Fratagene Therapeutics Ltd, 22 Northumberland Rd, Dublin, Ireland and
| | - Shadman Moiz
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome, Italy
| | - Serena Camerini
- Department of Cell Biology and Neurosciences, Italian National Institute of Health, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Marco Crescenzi
- Department of Cell Biology and Neurosciences, Italian National Institute of Health, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Roberto Testi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome, Italy, Fratagene Therapeutics Ltd, 22 Northumberland Rd, Dublin, Ireland and
| | - Florence Malisan
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Via Montpellier 1, 00133 Rome, Italy,
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50
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Rufini A, Cavallo F, Condò I, Fortuni S, De Martino G, Incani O, Di Venere A, Benini M, Massaro DS, Arcuri G, Serio D, Malisan F, Testi R. Highly specific ubiquitin-competing molecules effectively promote frataxin accumulation and partially rescue the aconitase defect in Friedreich ataxia cells. Neurobiol Dis 2015; 75:91-9. [PMID: 25549872 PMCID: PMC4358773 DOI: 10.1016/j.nbd.2014.12.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 12/09/2014] [Accepted: 12/11/2014] [Indexed: 11/30/2022] Open
Abstract
Friedreich ataxia is an inherited neurodegenerative disease that leads to progressive disability. There is currently no effective treatment and patients die prematurely. The underlying genetic defect leads to reduced expression of the mitochondrial protein frataxin. Frataxin insufficiency causes mitochondrial dysfunction and ultimately cell death, particularly in peripheral sensory ganglia. There is an inverse correlation between the amount of residual frataxin and the severity of disease progression; therefore, therapeutic approaches aiming at increasing frataxin levels are expected to improve patients' conditions. We previously discovered that a significant amount of frataxin precursor is degraded by the ubiquitin/proteasome system before its functional mitochondrial maturation. We also provided evidence for the therapeutic potential of small molecules that increase frataxin levels by docking on the frataxin ubiquitination site, thus preventing frataxin ubiquitination and degradation. We called these compounds ubiquitin-competing molecules (UCM). By extending our search for effective UCM, we identified a set of new and more potent compounds that more efficiently promote frataxin accumulation. Here we show that these compounds directly interact with frataxin and prevent its ubiquitination. Interestingly, these UCM are not effective on the ubiquitin-resistant frataxin mutant, indicating their specific action on preventing frataxin ubiquitination. Most importantly, these compounds are able to promote frataxin accumulation and aconitase rescue in cells derived from patients, strongly supporting their therapeutic potential.
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Affiliation(s)
- Alessandra Rufini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy; Fratagene Therapeutics Ltd., 22 Northumberland Rd., Dublin, Ireland
| | - Francesca Cavallo
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy
| | - Ivano Condò
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy
| | - Silvia Fortuni
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy; Fratagene Therapeutics Ltd., 22 Northumberland Rd., Dublin, Ireland
| | - Gabriella De Martino
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy
| | - Ottaviano Incani
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy
| | - Almerinda Di Venere
- Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy
| | - Monica Benini
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy
| | - Damiano Sergio Massaro
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy
| | - Gaetano Arcuri
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy
| | - Dario Serio
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy
| | - Florence Malisan
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy
| | - Roberto Testi
- Laboratory of Signal Transduction, Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Via Montpellier 1, Rome 00133, Italy; Fratagene Therapeutics Ltd., 22 Northumberland Rd., Dublin, Ireland.
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