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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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Lynch DR, Rojsajjakul T, Subramony SH, Perlman SL, Keita M, Mesaros C, Blair IA. Frataxin analysis using triple quadrupole mass spectrometry: application to a large heterogeneous clinical cohort. J Neurol 2024; 271:1844-1849. [PMID: 38063871 DOI: 10.1007/s00415-023-12118-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 01/23/2024]
Abstract
BACKGROUND Friedreich ataxia is a progressive multisystem disorder caused by deficiency of the protein frataxin; a small mitochondrial protein involved in iron sulfur cluster synthesis. Two types of frataxin exist: FXN-M, found in most cells, and FXN-E, found almost exclusively in red blood cells. Treatments in clinical trials include frataxin restoration by gene therapy, protein replacement, and epigenetic therapies, all of which necessitate sensitive assays for assessing frataxin levels. METHODS In the present study, we have used a triple quadrupole mass spectrometry-based assay to examine the features of both types of frataxin levels in blood in a large heterogenous cohort of 106 patients with FRDA. RESULTS Frataxin levels (FXN-E and FXN M) were predicted by GAA repeat length in regression models (R2 values = 0.51 and 0.27, respectively), and conversely frataxin levels predicted clinical status as determined by modified Friedreich Ataxia Rating scale scores and by disability status (R2 values = 0.13-0.16). There was no significant change in frataxin levels in individual subjects over time, and apart from start codon mutations, FXN-E and FXN-M levels were roughly equal. Accounting for hemoglobin levels in a smaller sub-cohort improved prediction of both FXN-E and FXN-M levels from R2 values of (0.3-0.38 to 0.20-0.51). CONCLUSION The present data show that assay of FXN-M and FXN-E levels in blood provides an appropriate biofluid for assessing their repletion in particular clinical contexts.
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Affiliation(s)
- David R Lynch
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, 502F Abramson Research Center, 3615 Civic Center Blvd, Philadelphia, PA, 19104-4318, USA.
| | - Teerapat Rojsajjakul
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - S H Subramony
- Department of Neurology, University of Florida, Gainesville, FL, 32608, USA
| | - Susan L Perlman
- Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, 90095, USA
| | - Medina Keita
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Clementina Mesaros
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ian A Blair
- Penn/CHOP Friedreich Ataxia Center of Excellence, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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Chang JC, Ryan MR, Stark MC, Liu S, Purushothaman P, Bolan F, Johnson CA, Champe M, Meng H, Lawlor MW, Halawani S, Ngaba LV, Lynch DR, Davis C, Gonzalo-Gil E, Lutz C, Urbinati F, Medicherla B, Fonck C. AAV8 gene therapy reverses cardiac pathology and prevents early mortality in a mouse model of Friedreich's ataxia. Mol Ther Methods Clin Dev 2024; 32:101193. [PMID: 38352270 PMCID: PMC10862410 DOI: 10.1016/j.omtm.2024.101193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 01/18/2024] [Indexed: 02/16/2024]
Abstract
Friedreich's ataxia (FRDA) is an autosomal-recessive disorder primarily attributed to biallelic GAA repeat expansions that reduce expression of the mitochondrial protein frataxin (FXN). FRDA is characterized by progressive neurodegeneration, with many patients developing cardiomyopathy that progresses to heart failure and death. The potential to reverse or prevent progression of the cardiac phenotype of FRDA was investigated in a mouse model of FRDA, using an adeno-associated viral vector (AAV8) containing the coding sequence of the FXN gene. The Fxnflox/null::MCK-Cre conditional knockout mouse (FXN-MCK) has an FXN gene ablation that prevents FXN expression in cardiac and skeletal muscle, leading to cardiac insufficiency, weight loss, and morbidity. FXN-MCK mice received a single intravenous injection of an AAV8 vector containing human (hFXN) or mouse (mFXN) FXN genes under the control of a phosphoglycerate kinase promoter. Compared to vehicle-treated FXN-MCK control mice, AAV-treated FXN-MCK mice displayed increases in body weight, reversal of cardiac deficits, and increases in survival without apparent toxicity in the heart or liver for up to 12 weeks postdose. FXN protein expression in heart tissue was detected in a dose-dependent manner, exhibiting wide distribution throughout the heart similar to wild type, but more speckled. These results support an AAV8-based approach to treat FRDA-associated cardiomyopathy.
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Affiliation(s)
- Joshua C. Chang
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Molly R. Ryan
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Marie C. Stark
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Su Liu
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | | | - Fria Bolan
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | | | - Mark Champe
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Hui Meng
- Diverge Translational Science Laboratory, Milwaukee, WI 53204, USA
- Medical College of Wisconsin, Department of Pathology and Laboratory Medicine, Milwaukee, WI 53226, USA
| | - Michael W. Lawlor
- Diverge Translational Science Laboratory, Milwaukee, WI 53204, USA
- Medical College of Wisconsin, Department of Pathology and Laboratory Medicine, Milwaukee, WI 53226, USA
| | - Sarah Halawani
- Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Lucie V. Ngaba
- Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - David R. Lynch
- Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | | | | | | | - Fabrizia Urbinati
- Formerly of Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Bala Medicherla
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
| | - Carlos Fonck
- Astellas Gene Therapies, Inc., South San Francisco, CA 94080, USA
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Edzeamey FJ, Ramchunder Z, Pourzand C, Anjomani Virmouni S. Emerging antioxidant therapies in Friedreich's ataxia. Front Pharmacol 2024; 15:1359618. [PMID: 38379897 PMCID: PMC10876797 DOI: 10.3389/fphar.2024.1359618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 01/25/2024] [Indexed: 02/22/2024] Open
Abstract
Friedreich's ataxia (FRDA) is a rare childhood neurologic disorder, affecting 1 in 50,000 Caucasians. The disease is caused by the abnormal expansion of the GAA repeat sequence in intron 1 of the FXN gene, leading to the reduced expression of the mitochondrial protein frataxin. The disease is characterised by progressive neurodegeneration, hypertrophic cardiomyopathy, diabetes mellitus and musculoskeletal deformities. The reduced expression of frataxin has been suggested to result in the downregulation of endogenous antioxidant defence mechanisms and mitochondrial bioenergetics, and the increase in mitochondrial iron accumulation thereby leading to oxidative stress. The confirmation of oxidative stress as one of the pathological signatures of FRDA led to the search for antioxidants which can be used as therapeutic modality. Based on this observation, antioxidants with different mechanisms of action have been explored for FRDA therapy since the last two decades. In this review, we bring forth all antioxidants which have been investigated for FRDA therapy and have been signed off for clinical trials. We summarise their various target points in FRDA disease pathway, their performances during clinical trials and possible factors which might have accounted for their failure or otherwise during clinical trials. We also discuss the limitation of the studies completed and propose possible strategies for combinatorial therapy of antioxidants to generate synergistic effect in FRDA patients.
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Affiliation(s)
- Fred Jonathan Edzeamey
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, College of Health, Medicine, and Life Sciences (CHMLS), Brunel University London, Uxbridge, United Kingdom
| | - Zenouska Ramchunder
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, College of Health, Medicine, and Life Sciences (CHMLS), Brunel University London, Uxbridge, United Kingdom
| | - Charareh Pourzand
- Department of Life Sciences, University of Bath, Bath, United Kingdom
- Centre for Therapeutic Innovation, University of Bath, Bath, United Kingdom
| | - Sara Anjomani Virmouni
- Ataxia Research Group, Division of Biosciences, Department of Life Sciences, College of Health, Medicine, and Life Sciences (CHMLS), Brunel University London, Uxbridge, United Kingdom
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5
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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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6
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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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7
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Bustamante-Barrientos FA, Luque-Campos N, Araya MJ, Lara-Barba E, de Solminihac J, Pradenas C, Molina L, Herrera-Luna Y, Utreras-Mendoza Y, Elizondo-Vega R, Vega-Letter AM, Luz-Crawford P. Mitochondrial dysfunction in neurodegenerative disorders: Potential therapeutic application of mitochondrial transfer to central nervous system-residing cells. J Transl Med 2023; 21:613. [PMID: 37689642 PMCID: PMC10493034 DOI: 10.1186/s12967-023-04493-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 08/30/2023] [Indexed: 09/11/2023] Open
Abstract
Mitochondrial dysfunction is reiteratively involved in the pathogenesis of diverse neurodegenerative diseases. Current in vitro and in vivo approaches support that mitochondrial dysfunction is branded by several molecular and cellular defects, whose impact at different levels including the calcium and iron homeostasis, energetic balance and/or oxidative stress, makes it difficult to resolve them collectively given their multifactorial nature. Mitochondrial transfer offers an overall solution since it contains the replacement of damage mitochondria by healthy units. Therefore, this review provides an introducing view on the structure and energy-related functions of mitochondria as well as their dynamics. In turn, we summarize current knowledge on how these features are deregulated in different neurodegenerative diseases, including frontotemporal dementia, multiple sclerosis, amyotrophic lateral sclerosis, Friedreich ataxia, Alzheimer´s disease, Parkinson´s disease, and Huntington's disease. Finally, we analyzed current advances in mitochondrial transfer between diverse cell types that actively participate in neurodegenerative processes, and how they might be projected toward developing novel therapeutic strategies.
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Affiliation(s)
- Felipe A Bustamante-Barrientos
- Laboratorio de Inmunología Celular y Molecular, Facultad de Medicina, Universidad de los Andes, Santiago, Chile.
- Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Mons. Álvaro del Portillo 12455, Las Condes, Santiago, Chile.
- IMPACT, Center of Interventional Medicine for Precision and Advanced Cellular Therapy, Santiago, Chile.
| | - Noymar Luque-Campos
- Laboratorio de Inmunología Celular y Molecular, Facultad de Medicina, Universidad de los Andes, Santiago, Chile
- Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Mons. Álvaro del Portillo 12455, Las Condes, Santiago, Chile
- IMPACT, Center of Interventional Medicine for Precision and Advanced Cellular Therapy, Santiago, Chile
| | - María Jesús Araya
- Laboratorio de Inmunología Celular y Molecular, Facultad de Medicina, Universidad de los Andes, Santiago, Chile
- Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Mons. Álvaro del Portillo 12455, Las Condes, Santiago, Chile
- IMPACT, Center of Interventional Medicine for Precision and Advanced Cellular Therapy, Santiago, Chile
| | - Eliana Lara-Barba
- Laboratorio de Inmunología Celular y Molecular, Facultad de Medicina, Universidad de los Andes, Santiago, Chile
- Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Mons. Álvaro del Portillo 12455, Las Condes, Santiago, Chile
- IMPACT, Center of Interventional Medicine for Precision and Advanced Cellular Therapy, Santiago, Chile
| | - Javiera de Solminihac
- Laboratorio de Inmunología Celular y Molecular, Facultad de Medicina, Universidad de los Andes, Santiago, Chile
- Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Mons. Álvaro del Portillo 12455, Las Condes, Santiago, Chile
| | - Carolina Pradenas
- Laboratorio de Inmunología Celular y Molecular, Facultad de Medicina, Universidad de los Andes, Santiago, Chile
- Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Mons. Álvaro del Portillo 12455, Las Condes, Santiago, Chile
- IMPACT, Center of Interventional Medicine for Precision and Advanced Cellular Therapy, Santiago, Chile
| | - Luis Molina
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Puerto Montt, Chile
| | - Yeimi Herrera-Luna
- Laboratorio de Inmunología Celular y Molecular, Facultad de Medicina, Universidad de los Andes, Santiago, Chile
- Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Mons. Álvaro del Portillo 12455, Las Condes, Santiago, Chile
- IMPACT, Center of Interventional Medicine for Precision and Advanced Cellular Therapy, Santiago, Chile
| | | | - Roberto Elizondo-Vega
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Ana María Vega-Letter
- Escuela de Ingeniería Bioquímica, Pontificia Universidad Católica de Valparaiso, Valparaiso, Chile
| | - Patricia Luz-Crawford
- Laboratorio de Inmunología Celular y Molecular, Facultad de Medicina, Universidad de los Andes, Santiago, Chile.
- Centro de Investigación e Innovación Biomédica (CiiB), Universidad de los Andes, Mons. Álvaro del Portillo 12455, Las Condes, Santiago, Chile.
- IMPACT, Center of Interventional Medicine for Precision and Advanced Cellular Therapy, Santiago, Chile.
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8
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Gillespie KP, Pirnie R, Mesaros C, Blair IA. Cisplatin Dependent Secretion of Immunomodulatory High Mobility Group Box 1 (HMGB1) Protein from Lung Cancer Cells. Biomolecules 2023; 13:1335. [PMID: 37759736 PMCID: PMC10526420 DOI: 10.3390/biom13091335] [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: 07/12/2023] [Revised: 08/25/2023] [Accepted: 08/26/2023] [Indexed: 09/29/2023] Open
Abstract
High mobility group box 1 (HMGB1) is secreted from activated immune cells, necrotic cells, and certain cancers. Previous studies have reported that different patterns of post-translational modification, particularly acetylation and oxidation, mediate HMGB1 release and confer distinct extracellular HMGB1 signaling activity. Here we report that cisplatin but not carboplatin induces secretion of HMGB1 from human A549 non-small cell lung cancer (NSCLC) cells. Cisplatin-mediated HMGB1 secretion was dose-dependent and was regulated by nuclear exportin 1 (XPO1) also known as chromosomal maintenance 1 (CRM1) rather than adenosine diphosphate (ADP)-ribosylation, acetylation, or oxidation. HMGB1, as well as lysine acetylation and cysteine disulfide oxidation of secreted HMGB1, were monitored by sensitive and specific assays using immunoprecipitation, stable isotope dilution, differential alkylation, and nano liquid chromatography parallel reaction monitoring/high-resolution mass spectrometry (nano-LC-PRM/HRMS). A major fraction of the HMGB1 secreted by low-dose cisplatin treatment of A549 NSCLC cells was found to be in the fully reduced form. In contrast, mainly oxidized forms of HMGB1 were secreted by dimethyl sulfoxide (DMSO)-mediated apoptosis. These findings suggest that inhibition of XPO1 could potentiate the anti-tumor activity of cisplatin by increasing the nuclear accumulation of HMGB1 protein, an inhibitor of cisplatin DNA-adduct repair. Furthermore, low-dose cisplatin therapy could modulate the immune response in NSCLC through the established chemokine activity of extracellular reduced HMGB1. This could potentially enhance the efficacy of subsequent immunotherapy treatment.
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Affiliation(s)
| | | | | | - Ian A. Blair
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
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Van-Duyne G, Blair IA, Sprenger C, Moiseenkova-Bell V, Plymate S, Penning TM. The androgen receptor. VITAMINS AND HORMONES 2023; 123:439-481. [PMID: 37717994 DOI: 10.1016/bs.vh.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
The Androgen Receptor (AR) is a ligand (androgen) activated transcription factor and a member of the nuclear receptor (NR) superfamily. It is required for male sex hormone function. AR-FL (full-length) has the domain structure of NRs, an N-terminal domain (NTD) required for transactivation, a DNA-binding domain (DBD), a nuclear localization signal (NLS) and a ligand-binding domain (LBD). Paradoxes exist in that endogenous ligands testosterone (T) and 5α-dihydrotestosterone (DHT) have differential effects on male sexual development while binding to the same receptor and transcriptional specificity is achieved even though the androgen response elements (AREs) are identical to those seen for the progesterone, glucocorticoid and mineralocorticoid receptors. A high resolution 3-dimensional structure of AR-FL by either cryo-EM or X-ray crystallography has remained elusive largely due to the intrinsic disorder of the NTD. AR function is regulated by post-translational modification leading to a large number of proteoforms. The interaction of these proteoforms in multiprotein complexes with co-activators and co-repressors driven by interdomain coupling mediates the AR transcriptional output. The AR is a drug target for selective androgen receptor modulators (SARMS) that either have anabolic or androgenic effects. Protstate cancer is treated with androgen deprivation therapy or by the use of AR antagonists that bind to the LBD. Drug resistance occurs due to adaptive AR upregulation and the appearance of splice variants that lack the LBD and become constitutively active. Bipolar T treatment and NTD-antagonists could surmount these resistance mechanisms, respectively. These recent advances in AR signaling are described.
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Affiliation(s)
- Greg Van-Duyne
- Department of Biophysics & Biochemistry, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, United States
| | - Ian A Blair
- Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, United States
| | - Cynthia Sprenger
- Division of Gerontology & Geriatric Medicine, Department of Medicine, University of Washington and GRECC, Seattle, WA, United States
| | - Vera Moiseenkova-Bell
- Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, United States
| | - Stephen Plymate
- Division of Gerontology & Geriatric Medicine, Department of Medicine, University of Washington and GRECC, Seattle, WA, United States
| | - Trevor M Penning
- Department of Systems Pharmacology & Translational Therapeutics, Perelman School of Medicine University of Pennsylvania, Philadelphia, PA, United States.
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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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11
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Lynch DR, Mathews KD, Perlman S, Zesiewicz T, Subramony S, Omidvar O, Vogel AP, Krtolica A, Litterman N, van der Ploeg L, Heerinckx F, Milner P, Midei M. Double blind trial of a deuterated form of linoleic acid (RT001) in Friedreich ataxia. J Neurol 2023; 270:1615-1623. [PMID: 36462055 DOI: 10.1007/s00415-022-11501-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 11/20/2022] [Accepted: 11/22/2022] [Indexed: 12/05/2022]
Abstract
OBJECTIVES Friedreich ataxia is (FRDA) an autosomal recessive neurodegenerative disorder associated with intrinsic oxidative damage, suggesting that decreasing lipid peroxidation (LPO) might ameliorate disease progression. The present study tested the ability of RT001, a deuterated form of linoleic acid (D2-LA), to alter disease severity in patients with FRDA in a double-blind placebo-controlled trial. METHODS Sixty-five subjects were recruited across six sites and received either placebo or active drug for an 11-month study. Subjects were evaluated at 0, 4, 9, and 11 months, with the primary outcome measure being maximum oxygen consumption (MVO2) during cardiopulmonary exercise testing (CPET). A key secondary outcome measure was a composite statistical test using results from the timed 1-min walk (T1MW), peak workload, and MVO2. RESULTS Forty-five subjects completed the protocol. RT001 was well tolerated, with no serious adverse events related to drug. Plasma and red blood cell (RBC) membrane levels of D2-LA and its primary metabolite deuterated arachidonic acid (D2-AA) achieved steady-state concentrations by 4 months. No significant changes in MVO2 were observed for RT001 compared to placebo. Similarly, no differences between the groups were found in secondary or exploratory outcome measures. Post hoc evaluations also suggested minimal effects of RT001 at the dosages used in this study. INTERPRETATIONS The results of this study provide no evidence for a significant benefit of RT001 at the dosages tested in this Friedreich ataxia patient population.
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Affiliation(s)
- David R Lynch
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA. .,Departments of Pediatrics and Neurology, The Children's Hospital of Philadelphia, 502F Abramson Research Center, 3615 Civic Center Blvd, Philadelphia, PA, 19104, USA.
| | - Katherine D Mathews
- Departments of Pediatrics and Neurology, University of Iowa Carver College of Medicine, Iowa City, USA
| | - Susan Perlman
- University of California Los Angeles, Los Angeles, USA
| | - Theresa Zesiewicz
- USF Ataxia Research Center, University of South Florida, James A. Haley Veteran's Hospital, Tampa, FL, USA
| | - Sub Subramony
- Norman Fixel Center for Neurological Disorders, University of Florida College of Medicine, Gainesville, USA
| | - Omid Omidvar
- University of California Los Angeles, Los Angeles, USA
| | - Adam P Vogel
- University of Melbourne, Parkville, Australia.,Redenlab Inc, Melbourne, Australia
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12
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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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13
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Alves R, Pazos-Gil M, Medina-Carbonero M, Sanz-Alcázar A, Delaspre F, Tamarit J. Evolution of an Iron-Detoxifying Protein: Eukaryotic and Rickettsia Frataxins Contain a Conserved Site Which Is Not Present in Their Bacterial Homologues. Int J Mol Sci 2022; 23:13151. [PMID: 36361939 PMCID: PMC9658677 DOI: 10.3390/ijms232113151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/21/2022] [Accepted: 10/27/2022] [Indexed: 01/07/2024] Open
Abstract
Friedreich's ataxia is a neurodegenerative disease caused by mutations in the frataxin gene. Frataxin homologues, including bacterial CyaY proteins, can be found in most species and play a fundamental role in mitochondrial iron homeostasis, either promoting iron assembly into metaloproteins or contributing to iron detoxification. While several lines of evidence suggest that eukaryotic frataxins are more effective than bacterial ones in iron detoxification, the residues involved in this gain of function are unknown. In this work, we analyze conservation of amino acid sequence and protein structure among frataxins and CyaY proteins to identify four highly conserved residue clusters and group them into potential functional clusters. Clusters 1, 2, and 4 are present in eukaryotic frataxins and bacterial CyaY proteins. Cluster 3, containing two serines, a tyrosine, and a glutamate, is only present in eukaryotic frataxins and on CyaY proteins from the Rickettsia genus. Residues from cluster 3 are blocking a small cavity of about 40 Å present in E. coli's CyaY. The function of this cluster is unknown, but we hypothesize that its tyrosine may contribute to prevent formation of reactive oxygen species during iron detoxification. This cluster provides an example of gain of function during evolution in a protein involved in iron homeostasis, as our results suggests that Cluster 3 was present in the endosymbiont ancestor of mitochondria and was conserved in eukaryotic frataxins.
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Affiliation(s)
| | | | | | | | | | - Jordi Tamarit
- Departament de Ciències Mèdiques Bàsiques, Facultat de Medicina, IRBLleida, Universitat de Lleida, 25001 Lleida, Spain
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14
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Payne RM. Cardiovascular Research in Friedreich Ataxia: Unmet Needs and Opportunities. JACC Basic Transl Sci 2022; 7:1267-1283. [PMID: 36644283 PMCID: PMC9831864 DOI: 10.1016/j.jacbts.2022.04.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/18/2022] [Accepted: 04/18/2022] [Indexed: 01/18/2023]
Abstract
Friedreich Ataxia (FRDA) is an autosomal recessive disease in which a mitochondrial protein, frataxin, is severely decreased in its expression. In addition to progressive ataxia, patients with FRDA often develop a cardiomyopathy that can be hypertrophic. This cardiomyopathy is unlike the sarcomeric hypertrophic cardiomyopathies in that the hypertrophy is associated with massive mitochondrial proliferation within the cardiomyocyte rather than contractile protein overexpression. This is associated with atrial arrhythmias, apoptosis, and fibrosis over time, and patients often develop heart failure leading to premature death. The differences between this mitochondrial cardiomyopathy and the more common contractile protein hypertrophic cardiomyopathies can be a source of misunderstanding in the management of these patients. Although imaging studies have revealed much about the structure and function of the heart in this disease, we still lack an understanding of many important clinical and fundamental molecular events that determine outcome of the heart in FRDA. This review will describe the current basic and clinical understanding of the FRDA heart, and most importantly, identify major gaps in our knowledge that represent new directions and opportunities for research.
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Affiliation(s)
- R. Mark Payne
- Address for correspondence: Dr R. Mark Payne, Division of Pediatric Cardiology, Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 West Walnut, R4 302b, Indianapolis, Indiana 46202, USA.
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15
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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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16
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Gupta R, Sahu M, Srivastava D, Tiwari S, Ambasta RK, Kumar P. Post-translational modifications: Regulators of neurodegenerative proteinopathies. Ageing Res Rev 2021; 68:101336. [PMID: 33775891 DOI: 10.1016/j.arr.2021.101336] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 03/10/2021] [Accepted: 03/22/2021] [Indexed: 12/14/2022]
Abstract
One of the hallmark features in the neurodegenerative disorders (NDDs) is the accumulation of aggregated and/or non-functional protein in the cellular milieu. Post-translational modifications (PTMs) are an essential regulator of non-functional protein aggregation in the pathogenesis of NDDs. Any alteration in the post-translational mechanism and the protein quality control system, for instance, molecular chaperone, ubiquitin-proteasome system, autophagy-lysosomal degradation pathway, enhances the accumulation of misfolded protein, which causes neuronal dysfunction. Post-translational modification plays many roles in protein turnover rate, accumulation of aggregate and can also help in the degradation of disease-causing toxic metabolites. PTMs such as acetylation, glycosylation, phosphorylation, ubiquitination, palmitoylation, SUMOylation, nitration, oxidation, and many others regulate protein homeostasis, which includes protein structure, functions and aggregation propensity. Different studies demonstrated the involvement of PTMs in the regulation of signaling cascades such as PI3K/Akt/GSK3β, MAPK cascade, AMPK pathway, and Wnt signaling pathway in the pathogenesis of NDDs. Further, mounting evidence suggests that targeting different PTMs with small chemical molecules, which acts as an inhibitor or activator, reverse misfolded protein accumulation and thus enhances the neuroprotection. Herein, we briefly discuss the protein aggregation and various domain structures of different proteins involved in the NDDs, indicating critical amino acid residues where PTMs occur. We also describe the implementation and involvement of various PTMs on signaling cascade and cellular processes in NDDs. Lastly, we implement our current understanding of the therapeutic importance of PTMs in neurodegeneration, along with emerging techniques targeting various PTMs.
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17
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Mitochondrial and metabolic dysfunction in Friedreich ataxia: update on pathophysiological relevance and clinical interventions. Neuronal Signal 2021; 5:NS20200093. [PMID: 34046211 PMCID: PMC8132591 DOI: 10.1042/ns20200093] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/29/2021] [Accepted: 04/30/2021] [Indexed: 02/07/2023] Open
Abstract
Friedreich ataxia (FRDA) is a recessive disorder resulting from relative deficiency of the mitochondrial protein frataxin. Frataxin functions in the process of iron–sulfur (Fe–S) cluster synthesis. In this review, we update some of the processes downstream of frataxin deficiency that may mediate the pathophysiology. Based on cellular models, in vivo models and observations of patients, ferroptosis may play a major role in the pathogenesis of FRDA along with depletion of antioxidant reserves and abnormalities of mitochondrial biogenesis. Ongoing clinical trials with ferroptosis inhibitors and nuclear factor erythroid 2-related factor 2 (Nrf2) activators are now targeting each of the processes. In addition, better understanding of the mitochondrial events in FRDA may allow the development of improved imaging methodology for assessing the disorder. Though not technologically feasible at present, metabolic imaging approaches may provide a direct methodology to understand the mitochondrial changes occurring in FRDA and provide a methodology to monitor upcoming trials of frataxin restoration.
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18
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Agrò M, Díaz-Nido J. Effect of Mitochondrial and Cytosolic FXN Isoform Expression on Mitochondrial Dynamics and Metabolism. Int J Mol Sci 2020; 21:E8251. [PMID: 33158039 PMCID: PMC7662637 DOI: 10.3390/ijms21218251] [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: 10/07/2020] [Revised: 10/27/2020] [Accepted: 11/02/2020] [Indexed: 02/07/2023] Open
Abstract
Friedreich's ataxia (FRDA) is a neurodegenerative disease caused by recessive mutations in the frataxin gene that lead to a deficiency of the mitochondrial frataxin (FXN) protein. Alternative forms of frataxin have been described, with different cellular localization and tissue distribution, including a cerebellum-specific cytosolic isoform called FXN II. Here, we explored the functional roles of FXN II in comparison to the mitochondrial FXN I isoform, highlighting the existence of potential cross-talk between cellular compartments. To achieve this, we transduced two human cell lines of patient and healthy subjects with lentiviral vectors overexpressing the mitochondrial or the cytosolic FXN isoforms and studied their effect on the mitochondrial network and metabolism. We confirmed the cytosolic localization of FXN isoform II in our in vitro models. Interestingly, both cytosolic and mitochondrial isoforms have an effect on mitochondrial dynamics, affecting different parameters. Accordingly, increases of mitochondrial respiration were detected after transduction with FXN I or FXN II in both cellular models. Together, these results point to the existence of a potential cross-talk mechanism between the cytosol and mitochondria, mediated by FXN isoforms. A more thorough knowledge of the mechanisms of action behind the extra-mitochondrial FXN II isoform could prove useful in unraveling FRDA physiopathology.
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Affiliation(s)
| | - Javier Díaz-Nido
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid, Nicolás Cabrera, 1, 28049 Madrid, Spain;
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