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Krasilnikova MM, Humphries CL, Shinsky EM. Friedreich's ataxia: new insights. Emerg Top Life Sci 2023; 7:313-323. [PMID: 37698160 DOI: 10.1042/etls20230017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/09/2023] [Accepted: 08/29/2023] [Indexed: 09/13/2023]
Abstract
Friedreich ataxia (FRDA) is an inherited disease that is typically caused by GAA repeat expansion within the first intron of the FXN gene coding for frataxin. This results in the frataxin deficiency that affects mostly muscle, nervous, and cardiovascular systems with progressive worsening of the symptoms over the years. This review summarizes recent progress that was achieved in understanding of molecular mechanism of the disease over the last few years and latest treatment strategies focused on overcoming the frataxin deficiency.
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Affiliation(s)
- Maria M Krasilnikova
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, U.S.A
| | - Casey L Humphries
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, U.S.A
| | - Emily M Shinsky
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, U.S.A
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Doni D, Cavion F, Bortolus M, Baschiera E, Muccioli S, Tombesi G, d'Ettorre F, Ottaviani D, Marchesan E, Leanza L, Greggio E, Ziviani E, Russo A, Bellin M, Sartori G, Carbonera D, Salviati L, Costantini P. Human frataxin, the Friedreich ataxia deficient protein, interacts with mitochondrial respiratory chain. Cell Death Dis 2023; 14:805. [PMID: 38062036 PMCID: PMC10703789 DOI: 10.1038/s41419-023-06320-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 11/14/2023] [Accepted: 11/16/2023] [Indexed: 12/18/2023]
Abstract
Friedreich ataxia (FRDA) is a rare, inherited neurodegenerative disease caused by an expanded GAA repeat in the first intron of the FXN gene, leading to transcriptional silencing and reduced expression of frataxin. Frataxin participates in the mitochondrial assembly of FeS clusters, redox cofactors of the respiratory complexes I, II and III. To date it is still unclear how frataxin deficiency culminates in the decrease of bioenergetics efficiency in FRDA patients' cells. We previously demonstrated that in healthy cells frataxin is closely attached to the mitochondrial cristae, which contain both the FeS cluster assembly machinery and the respiratory chain complexes, whereas in FRDA patients' cells with impaired respiration the residual frataxin is largely displaced in the matrix. To gain novel insights into the function of frataxin in the mitochondrial pathophysiology, and in the upstream metabolic defects leading to FRDA disease onset and progression, here we explored the potential interaction of frataxin with the FeS cluster-containing respiratory complexes I, II and III. Using healthy cells and different FRDA cellular models we found that frataxin interacts with these three respiratory complexes. Furthermore, by EPR spectroscopy, we observed that in mitochondria from FRDA patients' cells the decreased level of frataxin specifically affects the FeS cluster content of complex I. Remarkably, we also found that the frataxin-like protein Nqo15 from T. thermophilus complex I ameliorates the mitochondrial respiratory phenotype when expressed in FRDA patient's cells. Our data point to a structural and functional interaction of frataxin with complex I and open a perspective to explore therapeutic rationales for FRDA targeted to this respiratory complex.
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Affiliation(s)
- Davide Doni
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Federica Cavion
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, 35131, Padova, Italy
| | - Elisa Baschiera
- Clinical Genetics Unit, Department of Women's and Children Health, University of Padova, 35128, Padova, Italy
- Istituto di Ricerca Pediatrica (IRP) Città della Speranza, 35127, Padova, Italy
| | - Silvia Muccioli
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Giulia Tombesi
- Department of Biology, University of Padova, 35121, Padova, Italy
| | | | | | - Elena Marchesan
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Luigi Leanza
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Elisa Greggio
- Department of Biology, University of Padova, 35121, Padova, Italy
- Centro Studi per la Neurodegenerazione (CESNE), University of Padova, Padova, Italy
| | - Elena Ziviani
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Antonella Russo
- Department of Molecular Medicine, University of Padova, 35121, Padova, Italy
| | - Milena Bellin
- Department of Biology, University of Padova, 35121, Padova, Italy
- Veneto Institute of Molecular Medicine, 35129, Padova, Italy
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333, ZA, Leiden, The Netherlands
| | - Geppo Sartori
- Department of Biomedical Sciences, University of Padova, 35121, Padova, Italy
| | | | - Leonardo Salviati
- Clinical Genetics Unit, Department of Women's and Children Health, University of Padova, 35128, Padova, Italy.
- Istituto di Ricerca Pediatrica (IRP) Città della Speranza, 35127, Padova, Italy.
| | - Paola Costantini
- Department of Biology, University of Padova, 35121, Padova, Italy.
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Sayles NM, Napierala JS, Anrather J, Diedhiou N, Li J, Napierala M, Puccio H, Manfredi G. Comparative multi-omic analyses of cardiac mitochondrial stress in three mouse models of frataxin deficiency. Dis Model Mech 2023; 16:dmm050114. [PMID: 37691621 PMCID: PMC10581388 DOI: 10.1242/dmm.050114] [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: 01/30/2023] [Accepted: 09/05/2023] [Indexed: 09/12/2023] Open
Abstract
Cardiomyopathy is often fatal in Friedreich ataxia (FA). However, FA hearts maintain adequate function until advanced disease stages, suggesting initial adaptation to the loss of frataxin (FXN). Conditional cardiac knockout mouse models of FXN show transcriptional and metabolic profiles of the mitochondrial integrated stress response (ISRmt), which could play an adaptive role. However, the ISRmt has not been investigated in models with disease-relevant, partial decrease in FXN. We characterized the heart transcriptomes and metabolomes of three mouse models with varying degrees of FXN depletion: YG8-800, KIKO-700 and FXNG127V. Few metabolites were changed in YG8-800 mice, which did not provide a signature of cardiomyopathy or ISRmt; several metabolites were altered in FXNG127V and KIKO-700 hearts. Transcriptional changes were found in all models, but differentially expressed genes consistent with cardiomyopathy and ISRmt were only identified in FXNG127V hearts. However, these changes were surprisingly mild even at advanced age (18 months), despite a severe decrease in FXN levels to 1% of those of wild type. These findings indicate that the mouse heart has low reliance on FXN, highlighting the difficulty in modeling genetically relevant FA cardiomyopathy.
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Affiliation(s)
- Nicole M. Sayles
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA
- Neuroscience Graduate Program, Will Cornell Graduate School of Medical Sciences, 1300 York Ave, New York, NY 10065, USA
| | - Jill S. Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Josef Anrather
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA
| | - Nadège Diedhiou
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS/Université de Strasbourg UMR7104, Inserm U1258, B. P. 163, 67404 Illkirch, France
| | - Jixue Li
- Department of Neurology, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Marek Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Hélène Puccio
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS/Université de Strasbourg UMR7104, Inserm U1258, B. P. 163, 67404 Illkirch, France
| | - Giovanni Manfredi
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA
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Ast T, Wang H, Marutani E, Nagashima F, Malhotra R, Ichinose F, Mootha VK. Continuous, but not intermittent, regimens of hypoxia prevent and reverse ataxia in a murine model of Friedreich's ataxia. Hum Mol Genet 2023; 32:2600-2610. [PMID: 37260376 PMCID: PMC10407700 DOI: 10.1093/hmg/ddad091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 05/08/2023] [Accepted: 05/22/2023] [Indexed: 06/02/2023] Open
Abstract
Friedreich's ataxia (FA) is a devastating, multi-systemic neurodegenerative disease affecting thousands of people worldwide. We previously reported that oxygen is a key environmental variable that can modify FA pathogenesis. In particular, we showed that chronic, continuous normobaric hypoxia (11% FIO2) prevents ataxia and neurological disease in a murine model of FA, although it did not improve cardiovascular pathology or lifespan. Here, we report the pre-clinical evaluation of seven 'hypoxia-inspired' regimens in the shFxn mouse model of FA, with the long-term goal of designing a safe, practical and effective regimen for clinical translation. We report three chief results. First, a daily, intermittent hypoxia regimen (16 h 11% O2/8 h 21% O2) conferred no benefit and was in fact harmful, resulting in elevated cardiac stress and accelerated mortality. The detrimental effect of this regimen is likely owing to transient tissue hyperoxia that results when daily exposure to 21% O2 combines with chronic polycythemia, as we could blunt this toxicity by pharmacologically inhibiting polycythemia. Second, we report that more mild regimens of chronic hypoxia (17% O2) confer a modest benefit by delaying the onset of ataxia. Third, excitingly, we show that initiating chronic, continuous 11% O2 breathing once advanced neurological disease has already started can rapidly reverse ataxia. Our studies showcase both the promise and limitations of candidate hypoxia-inspired regimens for FA and underscore the need for additional pre-clinical optimization before future translation into humans.
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Affiliation(s)
- Tslil Ast
- Broad Institute, Cambridge, MA 02142, USA
- Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Hong Wang
- Broad Institute, Cambridge, MA 02142, USA
- Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Eizo Marutani
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Fumiaki Nagashima
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Rajeev Malhotra
- Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Fumito Ichinose
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Vamsi K Mootha
- Broad Institute, Cambridge, MA 02142, USA
- Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
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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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Medina-Carbonero M, Sanz-Alcázar A, Britti E, Delaspre F, Cabiscol E, Ros J, Tamarit J. Mice harboring the FXN I151F pathological point mutation present decreased frataxin levels, a Friedreich ataxia-like phenotype, and mitochondrial alterations. Cell Mol Life Sci 2022; 79:74. [PMID: 35038030 PMCID: PMC8763788 DOI: 10.1007/s00018-021-04100-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/21/2021] [Accepted: 12/16/2021] [Indexed: 12/13/2022]
Abstract
Friedreich Ataxia (FA) is a rare neuro-cardiodegenerative disease caused by mutations in the frataxin (FXN) gene. The most prevalent mutation is a GAA expansion in the first intron of the gene causing decreased frataxin expression. Some patients present the GAA expansion in one allele and a missense mutation in the other allele. One of these mutations, FXNI154F, was reported to result in decreased content of mature frataxin and increased presence of an insoluble intermediate proteoform in cellular models. By introducing this mutation into the murine Fxn gene (I151F, equivalent to human I154F) we have now analyzed the consequences of this pathological point mutation in vivo. We have observed that FXNI151F homozygous mice present low frataxin levels in all tissues, with no evidence of insoluble proteoforms. Moreover, they display neurological deficits resembling those observed in FA patients. Biochemical analysis of heart, cerebrum and cerebellum have revealed decreased content of components from OXPHOS complexes I and II, decreased aconitase activity, and alterations in antioxidant defenses. These mitochondrial alterations are more marked in the nervous system than in heart, precede the appearance of neurological symptoms, and are similar to those observed in other FA models. We conclude that the primary pathological mechanism underlying the I151F mutation is frataxin deficiency, like in patients carrying GAA expansions. Therefore, patients carrying the I154F mutation would benefit from frataxin replacement therapies. Furthermore, our results also show that the FXNI151F mouse is an excellent tool for analyzing tissue-specific consequences of frataxin deficiency and for testing new therapies.
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Affiliation(s)
- Marta Medina-Carbonero
- Dept. Ciències Mèdiques Bàsiques, Fac. Medicina, IRBLleida, Universitat de Lleida, Av. Rovira Roure, 80, 25198, Lleida, Spain
| | - Arabela Sanz-Alcázar
- Dept. Ciències Mèdiques Bàsiques, Fac. Medicina, IRBLleida, Universitat de Lleida, Av. Rovira Roure, 80, 25198, Lleida, Spain
| | - Elena Britti
- Dept. Ciències Mèdiques Bàsiques, Fac. Medicina, IRBLleida, Universitat de Lleida, Av. Rovira Roure, 80, 25198, Lleida, Spain
| | - Fabien Delaspre
- Dept. Ciències Mèdiques Bàsiques, Fac. Medicina, IRBLleida, Universitat de Lleida, Av. Rovira Roure, 80, 25198, Lleida, Spain
| | - Elisa Cabiscol
- Dept. Ciències Mèdiques Bàsiques, Fac. Medicina, IRBLleida, Universitat de Lleida, Av. Rovira Roure, 80, 25198, Lleida, Spain
| | - Joaquim Ros
- Dept. Ciències Mèdiques Bàsiques, Fac. Medicina, IRBLleida, Universitat de Lleida, Av. Rovira Roure, 80, 25198, Lleida, Spain
| | - Jordi Tamarit
- Dept. Ciències Mèdiques Bàsiques, Fac. Medicina, IRBLleida, Universitat de Lleida, Av. Rovira Roure, 80, 25198, Lleida, Spain.
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Lynch DR, Johnson J. Omaveloxolone: potential new agent for Friedreich ataxia. Neurodegener Dis Manag 2021; 11:91-98. [PMID: 33430645 DOI: 10.2217/nmt-2020-0057] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Friedreich ataxia is a slowly progressive neurodegenerative disorder leading to ataxia, dyscoordination, dysarthria and in many individuals vision and hearing loss. It is associated with cardiomyopathy, the leading cause of death in Friedreich ataxia (FRDA), diabetes and scoliosis. There are no approved therapies, but elucidation of the pathophysiology of FRDA suggest that agents that increase the activity of the transcription factor Nrf2 may provide a mechanism for ameliorating disease progression or severity. In this work, we review the evidence for use of omaveloxolone in FRDA from recent clinical trials. Though not at present approved for any indication, the present data suggest that this agent acting though increases in Nrf2 activity may provide a novel therapy for FRDA.
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Affiliation(s)
- David R Lynch
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.,Department of Neurology & Pediatrics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Joseph Johnson
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.,Department of Systems Pharmacology & Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
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