1
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Shen MM, Rummey C, Lynch DR. Phenotypic variation of FXN compound heterozygotes in a Friedreich ataxia cohort. Ann Clin Transl Neurol 2024; 11:1110-1121. [PMID: 38396238 DOI: 10.1002/acn3.52027] [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: 12/13/2023] [Revised: 01/24/2024] [Accepted: 02/09/2024] [Indexed: 02/25/2024] Open
Abstract
OBJECTIVE Most individuals with Friedreich ataxia (FRDA) have homozygous GAA triplet repeat expansions in the FXN gene, correlating with a typical phenotype of ataxia and cardiomyopathy. A minority are compound heterozygotes carrying a GAA expansion on one allele and a mutation on the other. The study aim was to examine phenotypic variation among compound heterozygotes. METHODS Data on FXN mutations were obtained from the Friedreich Ataxia Clinical Outcome Measures Study (FA-COMS). We compared clinical features in a single-site FA-COMS cohort of 51 compound heterozygous and 358 homozygous patients, including quantitative measures of cardiac, neurologic, and visual disease progression. RESULTS Non-GAA repeat mutations were associated with reduced cardiac disease, and patients with minimal/no function mutations otherwise had a typical FRDA phenotype but with significantly more severe progression. The partial function mutation group was characterized by relative sparing of bulbar and upper limb function, as well as particularly low cardiac involvement. Other clinical features in this group, including optic atrophy and diabetes mellitus, varied widely depending on the specific type of partial function mutation. INTERPRETATION These data support that the typical FRDA phenotype is driven by frataxin deficiency, especially severe in compound heterozygotes with minimal/no function mutations, whereas the heterogeneous presentations of those with partial function mutations may indicate other contributing factors to FRDA pathogenesis.
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Affiliation(s)
- Megan M Shen
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Perelman School of Medicine, University of Pennsylvania., Philadelphia, Pennsylvania, USA
| | | | - David R Lynch
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Perelman School of Medicine, University of Pennsylvania., Philadelphia, Pennsylvania, USA
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2
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Doni D, Cavallari E, Noguera ME, Gentili HG, Cavion F, Parisi G, Fornasari MS, Sartori G, Santos J, Bellanda M, Carbonera D, Costantini P, Bortolus M. Searching for Frataxin Function: Exploring the Analogy with Nqo15, the Frataxin-like Protein of Respiratory Complex I from Thermus thermophilus. Int J Mol Sci 2024; 25:1912. [PMID: 38339189 PMCID: PMC10855754 DOI: 10.3390/ijms25031912] [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: 12/23/2023] [Revised: 01/26/2024] [Accepted: 02/02/2024] [Indexed: 02/12/2024] Open
Abstract
Nqo15 is a subunit of respiratory complex I of the bacterium Thermus thermophilus, with strong structural similarity to human frataxin (FXN), a protein involved in the mitochondrial disease Friedreich's ataxia (FRDA). Recently, we showed that the expression of recombinant Nqo15 can ameliorate the respiratory phenotype of FRDA patients' cells, and this prompted us to further characterize both the Nqo15 solution's behavior and its potential functional overlap with FXN, using a combination of in silico and in vitro techniques. We studied the analogy of Nqo15 and FXN by performing extensive database searches based on sequence and structure. Nqo15's folding and flexibility were investigated by combining nuclear magnetic resonance (NMR), circular dichroism, and coarse-grained molecular dynamics simulations. Nqo15's iron-binding properties were studied using NMR, fluorescence, and specific assays and its desulfurase activation by biochemical assays. We found that the recombinant Nqo15 isolated from complex I is monomeric, stable, folded in solution, and highly dynamic. Nqo15 does not share the iron-binding properties of FXN or its desulfurase activation function.
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Affiliation(s)
- Davide Doni
- Department of Biology, University of Padova, 35121 Padova, Italy; (D.D.); (F.C.)
| | - Eva Cavallari
- Department of Biology, University of Padova, 35121 Padova, Italy; (D.D.); (F.C.)
- Grenoble Alpes University, CNRS, CEA, INRAE, IRIG-LPCV, 38000 Grenoble, France
| | - Martin Ezequiel Noguera
- Department of Physiology and Molecular and Cellular Biology, Institute of Biosciences, Biotechnology and Translational Biology (iB3), Faculty of Exact and Natural Sciences, University of Buenos Aires, Intendente Güiraldes 2160, Buenos Aires C1428EG, Argentina; (M.E.N.); (H.G.G.); (J.S.)
- Institute of Biological Chemistry and Physical Chemistry, Dr Alejandro Paladini (UBA-CONICET), University of Buenos Aires, Junín 956, Buenos Aires 1113AAD, Argentina
- Department of Science and Technology, National University of Quilmes, Roque Saenz Peña 352, Bernal B1876BXD, Argentina; (G.P.); (M.S.F.)
| | - Hernan Gustavo Gentili
- Department of Physiology and Molecular and Cellular Biology, Institute of Biosciences, Biotechnology and Translational Biology (iB3), Faculty of Exact and Natural Sciences, University of Buenos Aires, Intendente Güiraldes 2160, Buenos Aires C1428EG, Argentina; (M.E.N.); (H.G.G.); (J.S.)
| | - Federica Cavion
- Department of Biology, University of Padova, 35121 Padova, Italy; (D.D.); (F.C.)
| | - Gustavo Parisi
- Department of Science and Technology, National University of Quilmes, Roque Saenz Peña 352, Bernal B1876BXD, Argentina; (G.P.); (M.S.F.)
| | - Maria Silvina Fornasari
- Department of Science and Technology, National University of Quilmes, Roque Saenz Peña 352, Bernal B1876BXD, Argentina; (G.P.); (M.S.F.)
| | - Geppo Sartori
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy;
| | - Javier Santos
- Department of Physiology and Molecular and Cellular Biology, Institute of Biosciences, Biotechnology and Translational Biology (iB3), Faculty of Exact and Natural Sciences, University of Buenos Aires, Intendente Güiraldes 2160, Buenos Aires C1428EG, Argentina; (M.E.N.); (H.G.G.); (J.S.)
| | - Massimo Bellanda
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy; (M.B.); (D.C.)
- Consiglio Nazionale delle Ricerche Institute of Biomolecular Chemistry, 35131 Padova, Italy
| | - Donatella Carbonera
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy; (M.B.); (D.C.)
| | - Paola Costantini
- Department of Biology, University of Padova, 35121 Padova, Italy; (D.D.); (F.C.)
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy; (M.B.); (D.C.)
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3
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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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Indelicato E, Faserl K, Amprosi M, Nachbauer W, Schneider R, Wanschitz J, Sarg B, Boesch S. Skeletal muscle proteome analysis underpins multifaceted mitochondrial dysfunction in Friedreich's ataxia. Front Neurosci 2023; 17:1289027. [PMID: 38027498 PMCID: PMC10644315 DOI: 10.3389/fnins.2023.1289027] [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: 09/05/2023] [Accepted: 10/11/2023] [Indexed: 12/01/2023] Open
Abstract
Friedreich's ataxia (FRDA) is a severe multisystemic disorder caused by a deficiency of the mitochondrial protein frataxin. While some aspects of FRDA pathology are developmental, the causes underlying the steady progression are unclear. The inaccessibility of key affected tissues to sampling is a main hurdle. Skeletal muscle displays a disease phenotype and may be sampled in vivo to address open questions on FRDA pathophysiology. Thus, we performed a quantitative mass spectrometry-based proteomics analysis in gastrocnemius skeletal muscle biopsies from genetically confirmed FRDA patients (n = 5) and controls. Obtained data files were processed using Proteome Discoverer and searched by Sequest HT engine against a UniProt human reference proteome database. Comparing skeletal muscle proteomics profiles between FRDA and controls, we identified 228 significant differentially expressed (DE) proteins, of which 227 were downregulated in FRDA. Principal component analysis showed a clear separation between FRDA and control samples. Interactome analysis revealed clustering of DE proteins in oxidative phosphorylation, ribosomal elements, mitochondrial architecture control, and fission/fusion pathways. DE findings in the muscle-specific proteomics suggested a shift toward fast-twitching glycolytic fibers. Notably, most DE proteins (169/228, 74%) are target of the transcription factor nuclear factor-erythroid 2. Our data corroborate a mitochondrial biosignature of FRDA, which extends beyond a mere oxidative phosphorylation failure. Skeletal muscle proteomics highlighted a derangement of mitochondrial architecture and maintenance pathways and a likely adaptive metabolic shift of contractile proteins. The present findings are relevant for the design of future therapeutic strategies and highlight the value of skeletal muscle-omics as disease state readout in FRDA.
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Affiliation(s)
- Elisabetta Indelicato
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Klaus Faserl
- Institute of Medical Biochemistry, Protein Core Facility, Medical University of Innsbruck, Innsbruck, Austria
| | - Matthias Amprosi
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Wolfgang Nachbauer
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Rainer Schneider
- Institute of Biochemistry, Center of Molecular Biosciences Innsbruck (CMBI), Leopold-Franzens University Innsbruck, Innsbruck, Austria
| | - Julia Wanschitz
- Laboratory of Tissue Diagnostics, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Bettina Sarg
- Institute of Medical Biochemistry, Protein Core Facility, Medical University of Innsbruck, Innsbruck, Austria
| | - Sylvia Boesch
- Center for Rare Movement Disorders Innsbruck, Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
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5
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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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6
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Terenzi A, Pagani MA, Gomez-Casati DF, Busi MV. Structural and Functional Characterization of CreFH1, the Frataxin Homolog from Chlamydomonas reinhardtii. PLANTS 2022; 11:plants11151931. [PMID: 35893635 PMCID: PMC9331050 DOI: 10.3390/plants11151931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/14/2022] [Accepted: 07/19/2022] [Indexed: 11/29/2022]
Abstract
Frataxin plays a key role in cellular iron homeostasis of different organisms. It has been implicated in iron storage, detoxification, delivery for Fe-S cluster assembly and heme biosynthesis. However, its specific role in iron metabolism remains unclear, especially in photosynthetic organisms. To gain insight into the role and properties of frataxin in algae, we identified the gene CreFH1, which codes for the frataxin homolog from Chlamydomonas reinhardtii. We performed the cloning, expression and biochemical characterization of CreFH1. This protein has a predicted mitochondrial transit peptide and a significant structural similarity to other members of the frataxin family. In addition, CreFH1 was able to form a dimer in vitro, and this effect was increased by the addition of Cu2+ and also attenuated the Fenton reaction in the presence of a mixture of Fe2+ and H2O2. Bacterial cells with overexpression of CreFH1 showed increased growth in the presence of different metals, such as Fe, Cu, Zn and Ni and H2O2. Thus, results indicated that CreFH1 is a functional protein that shows some distinctive features compared to its more well-known counterparts, and would play an important role in response to oxidative stress in C. reinhardtii.
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7
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Puglisi R. Protein Mutations and Stability, a Link with Disease: The Case Study of Frataxin. Biomedicines 2022; 10:biomedicines10020425. [PMID: 35203634 PMCID: PMC8962269 DOI: 10.3390/biomedicines10020425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 11/16/2022] Open
Abstract
Protein mutations may lead to pathologies by causing protein misfunction or propensity to degradation. For this reason, several studies have been performed over the years to determine the capability of proteins to retain their native conformation under stress condition as well as factors to explain protein stabilization and the mechanisms behind unfolding. In this review, we explore the paradigmatic example of frataxin, an iron binding protein involved in Fe–S cluster biogenesis, and whose impairment causes a neurodegenerative disease called Friedreich’s Ataxia (FRDA). We summarize what is known about most common point mutations identified so far in heterozygous FRDA patients, their effects on frataxin structure and function and the consequences of its binding with partners.
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Affiliation(s)
- Rita Puglisi
- UK Dementia Research Institute at the Wohl Institute of King's College London, London SE59RT, UK
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8
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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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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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Marde VS, Tiwari PL, Wankhede NL, Taksande BG, Upaganlawar AB, Umekar MJ, Kale MB. Neurodegenerative disorders associated with genes of mitochondria. FUTURE JOURNAL OF PHARMACEUTICAL SCIENCES 2021. [DOI: 10.1186/s43094-021-00215-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023] Open
Abstract
Abstract
Background
Over the last decade, aggregating evidences suggested that there is a causative link between mutation in gene associated with mitochondrial dysfunction and development of several neurodegenerative disorders.
Main text
Recent structural and functional studies associated with mitochondrial genes have shown that mitochondrial abnormalities possibly lead to mitochondrial dysfunction. Several studies on animal models of neurodegenerative diseases and mitochondrial genes have provided compelling evidence that mitochondria is involved in the initiation as well as progression of diseases such as Parkinson’s disease (PD), Alzheimer’s disease (AD), Huntington’s disease (HD), and Friedreich ataxia (FA).
Conclusion
In this mini-review, we have discussed the different etiologic and pathogenesis connected with the mitochondrial dysfunction and relevant neurodegenerative diseases that underlie the dominant part of mitochondrial genes in the disease development and its progress.
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11
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Petronek MS, Spitz DR, Allen BG. Iron-Sulfur Cluster Biogenesis as a Critical Target in Cancer. Antioxidants (Basel) 2021; 10:1458. [PMID: 34573089 PMCID: PMC8465902 DOI: 10.3390/antiox10091458] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/03/2021] [Accepted: 09/08/2021] [Indexed: 11/30/2022] Open
Abstract
Cancer cells preferentially accumulate iron (Fe) relative to non-malignant cells; however, the underlying rationale remains elusive. Iron-sulfur (Fe-S) clusters are critical cofactors that aid in a wide variety of cellular functions (e.g., DNA metabolism and electron transport). In this article, we theorize that a differential need for Fe-S biogenesis in tumor versus non-malignant cells underlies the Fe-dependent cell growth demand of cancer cells to promote cell division and survival by promoting genomic stability via Fe-S containing DNA metabolic enzymes. In this review, we outline the complex Fe-S biogenesis process and its potential upregulation in cancer. We also discuss three therapeutic strategies to target Fe-S biogenesis: (i) redox manipulation, (ii) Fe chelation, and (iii) Fe mimicry.
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Affiliation(s)
- Michael S. Petronek
- Department of Radiation Oncology, Division of Free Radical and Radiation Biology, The University of Iowa Hospitals and Clinics, Iowa City, IA 52242-1181, USA;
- Holden Comprehensive Cancer Center, Free Radical and Radiation Biology Program, Department of Radiation Oncology, University of Iowa, Iowa City, IA 52242-1181, USA
| | - Douglas R. Spitz
- Department of Radiation Oncology, Division of Free Radical and Radiation Biology, The University of Iowa Hospitals and Clinics, Iowa City, IA 52242-1181, USA;
- Holden Comprehensive Cancer Center, Free Radical and Radiation Biology Program, Department of Radiation Oncology, University of Iowa, Iowa City, IA 52242-1181, USA
| | - Bryan G. Allen
- Department of Radiation Oncology, Division of Free Radical and Radiation Biology, The University of Iowa Hospitals and Clinics, Iowa City, IA 52242-1181, USA;
- Holden Comprehensive Cancer Center, Free Radical and Radiation Biology Program, Department of Radiation Oncology, University of Iowa, Iowa City, IA 52242-1181, USA
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12
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Das M, Dewan A, Shee S, Singh A. The Multifaceted Bacterial Cysteine Desulfurases: From Metabolism to Pathogenesis. Antioxidants (Basel) 2021; 10:antiox10070997. [PMID: 34201508 PMCID: PMC8300815 DOI: 10.3390/antiox10070997] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/01/2021] [Accepted: 05/06/2021] [Indexed: 12/02/2022] Open
Abstract
Living cells have developed a relay system to efficiently transfer sulfur (S) from cysteine to various thio-cofactors (iron-sulfur (Fe-S) clusters, thiamine, molybdopterin, lipoic acid, and biotin) and thiolated tRNA. The presence of such a transit route involves multiple protein components that allow the flux of S to be precisely regulated as a function of environmental cues to avoid the unnecessary accumulation of toxic concentrations of soluble sulfide (S2−). The first enzyme in this relay system is cysteine desulfurase (CSD). CSD catalyzes the release of sulfane S from L-cysteine by converting it to L-alanine by forming an enzyme-linked persulfide intermediate on its conserved cysteine residue. The persulfide S is then transferred to diverse acceptor proteins for its incorporation into the thio-cofactors. The thio-cofactor binding-proteins participate in essential and diverse cellular processes, including DNA repair, respiration, intermediary metabolism, gene regulation, and redox sensing. Additionally, CSD modulates pathogenesis, antibiotic susceptibility, metabolism, and survival of several pathogenic microbes within their hosts. In this review, we aim to comprehensively illustrate the impact of CSD on bacterial core metabolic processes and its requirement to combat redox stresses and antibiotics. Targeting CSD in human pathogens can be a potential therapy for better treatment outcomes.
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13
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Campbell CJ, Pall AE, Naik AR, Thompson LN, Stemmler TL. Molecular Details of the Frataxin-Scaffold Interaction during Mitochondrial Fe-S Cluster Assembly. Int J Mol Sci 2021; 22:6006. [PMID: 34199378 PMCID: PMC8199681 DOI: 10.3390/ijms22116006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 12/23/2022] Open
Abstract
Iron-sulfur clusters are essential to almost every life form and utilized for their unique structural and redox-targeted activities within cells during many cellular pathways. Although there are three different Fe-S cluster assembly pathways in prokaryotes (the NIF, SUF and ISC pathways) and two in eukaryotes (CIA and ISC pathways), the iron-sulfur cluster (ISC) pathway serves as the central mechanism for providing 2Fe-2S clusters, directly and indirectly, throughout the entire cell in eukaryotes. Proteins central to the eukaryotic ISC cluster assembly complex include the cysteine desulfurase, a cysteine desulfurase accessory protein, the acyl carrier protein, the scaffold protein and frataxin (in humans, NFS1, ISD11, ACP, ISCU and FXN, respectively). Recent molecular details of this complex (labeled NIAUF from the first letter from each ISC protein outlined earlier), which exists as a dimeric pentamer, have provided real structural insight into how these partner proteins arrange themselves around the cysteine desulfurase, the core dimer of the (NIAUF)2 complex. In this review, we focus on both frataxin and the scaffold within the human, fly and yeast model systems to provide a better understanding of the biophysical characteristics of each protein alone and within the FXN/ISCU complex as it exists within the larger NIAUF construct. These details support a complex dynamic interaction between the FXN and ISCU proteins when both are part of the NIAUF complex and this provides additional insight into the coordinated mechanism of Fe-S cluster assembly.
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Affiliation(s)
| | | | | | | | - Timothy L. Stemmler
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USA; (C.J.C.); (A.E.P.); (A.R.N.); (L.N.T.)
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14
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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: 8] [Impact Index Per Article: 2.7] [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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15
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Gomez-Casati DF, Busi MV, Barchiesi J, Pagani MA, Marchetti-Acosta NS, Terenzi A. Fe-S Protein Synthesis in Green Algae Mitochondria. PLANTS 2021; 10:plants10020200. [PMID: 33494487 PMCID: PMC7911964 DOI: 10.3390/plants10020200] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/13/2021] [Accepted: 01/18/2021] [Indexed: 12/28/2022]
Abstract
Iron and sulfur are two essential elements for all organisms. These elements form the Fe-S clusters that are present as cofactors in numerous proteins and protein complexes related to key processes in cells, such as respiration and photosynthesis, and participate in numerous enzymatic reactions. In photosynthetic organisms, the ISC and SUF Fe-S cluster synthesis pathways are located in organelles, mitochondria, and chloroplasts, respectively. There is also a third biosynthetic machinery in the cytosol (CIA) that is dependent on the mitochondria for its function. The genes and proteins that participate in these assembly pathways have been described mainly in bacteria, yeasts, humans, and recently in higher plants. However, little is known about the proteins that participate in these processes in algae. This review work is mainly focused on releasing the information on the existence of genes and proteins of green algae (chlorophytes) that could participate in the assembly process of Fe-S groups, especially in the mitochondrial ISC and CIA pathways.
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Affiliation(s)
- Diego F. Gomez-Casati
- Correspondence: (D.F.G.-C.); (M.V.B.); Tel.: +54-341-4391955 (ext. 113) (D.F.G.-C. & M.V.B.)
| | - Maria V. Busi
- Correspondence: (D.F.G.-C.); (M.V.B.); Tel.: +54-341-4391955 (ext. 113) (D.F.G.-C. & M.V.B.)
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16
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Smith FM, Kosman DJ. Molecular Defects in Friedreich's Ataxia: Convergence of Oxidative Stress and Cytoskeletal Abnormalities. Front Mol Biosci 2020; 7:569293. [PMID: 33263002 PMCID: PMC7686857 DOI: 10.3389/fmolb.2020.569293] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/10/2020] [Indexed: 01/18/2023] Open
Abstract
Friedreich’s ataxia (FRDA) is a multi-faceted disease characterized by progressive sensory–motor loss, neurodegeneration, brain iron accumulation, and eventual death by hypertrophic cardiomyopathy. FRDA follows loss of frataxin (FXN), a mitochondrial chaperone protein required for incorporation of iron into iron–sulfur cluster and heme precursors. After the discovery of the molecular basis of FRDA in 1996, over two decades of research have been dedicated to understanding the temporal manifestations of disease both at the whole body and molecular level. Early research indicated strong cellular iron dysregulation in both human and yeast models followed by onset of oxidative stress. Since then, the pathophysiology due to dysregulation of intracellular iron chaperoning has become central in FRDA relative to antioxidant defense and run-down in energy metabolism. At the same time, limited consideration has been given to changes in cytoskeletal organization, which was one of the first molecular defects noted. These alterations include both post-translational oxidative glutathionylation of actin monomers and differential DNA processing of a cytoskeletal regulator PIP5K1β. Currently unknown in respect to FRDA but well understood in the context of FXN-deficient cell physiology is the resulting impact on the cytoskeleton; this disassembly of actin filaments has a particularly profound effect on cell–cell junctions characteristic of barrier cells. With respect to a neurodegenerative disorder such as FRDA, this cytoskeletal and tight junction breakdown in the brain microvascular endothelial cells of the blood–brain barrier is likely a component of disease etiology. This review serves to outline a brief history of this research and hones in on pathway dysregulation downstream of iron-related pathology in FRDA related to actin dynamics. The review presented here was not written with the intent of being exhaustive, but to instead urge the reader to consider the essentiality of the cytoskeleton and appreciate the limited knowledge on FRDA-related cytoskeletal dysfunction as a result of oxidative stress. The review examines previous hypotheses of neurodegeneration with brain iron accumulation (NBIA) in FRDA with a specific biochemical focus.
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Affiliation(s)
- Frances M Smith
- Department of Biochemistry, State University of New York at Buffalo, Buffalo, NY, United States
| | - Daniel J Kosman
- Department of Biochemistry, State University of New York at Buffalo, Buffalo, NY, United States
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17
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Armas AM, Balparda M, Terenzi A, Busi MV, Pagani MA, Gomez-Casati DF. Iron-Sulfur Cluster Complex Assembly in the Mitochondria of Arabidopsis thaliana. PLANTS (BASEL, SWITZERLAND) 2020; 9:plants9091171. [PMID: 32917022 PMCID: PMC7570111 DOI: 10.3390/plants9091171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/21/2020] [Accepted: 09/08/2020] [Indexed: 05/02/2023]
Abstract
In plants, the cysteine desulfurase (AtNFS1) and frataxin (AtFH) are involved in the formation of Fe-S groups in mitochondria, specifically, in Fe and sulfur loading onto scaffold proteins, and the subsequent formation of the mature Fe-S cluster. We found that the small mitochondrial chaperone, AtISD11, and AtFH are positive regulators for AtNFS1 activity in Arabidopsis. Moreover, when the three proteins were incubated together, a stronger attenuation of the Fenton reaction was observed compared to that observed with AtFH alone. Using pull-down assays, we found that these three proteins physically interact, and sequence alignment and docking studies showed that several amino acid residues reported as critical for the interaction of their human homologous are conserved. Our results suggest that AtFH, AtNFS1 and AtISD11 form a multiprotein complex that could be involved in different stages of the iron-sulfur cluster (ISC) pathway in plant mitochondria.
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Affiliation(s)
- Alejandro M. Armas
- Instituto de Biologia Molecular y Celular de Rosario (IBR-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina;
| | - Manuel Balparda
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina; (M.B.); (A.T.); (M.V.B.); (M.A.P.)
| | - Agustina Terenzi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina; (M.B.); (A.T.); (M.V.B.); (M.A.P.)
| | - Maria V. Busi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina; (M.B.); (A.T.); (M.V.B.); (M.A.P.)
| | - Maria A. Pagani
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina; (M.B.); (A.T.); (M.V.B.); (M.A.P.)
| | - Diego F. Gomez-Casati
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Rosario 2000, Argentina; (M.B.); (A.T.); (M.V.B.); (M.A.P.)
- Correspondence: ; Tel.: +54-341-4391955 (ext. 113)
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18
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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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19
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Delatycki MB, Bidichandani SI. Friedreich ataxia- pathogenesis and implications for therapies. Neurobiol Dis 2019; 132:104606. [PMID: 31494282 DOI: 10.1016/j.nbd.2019.104606] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/08/2019] [Accepted: 09/04/2019] [Indexed: 01/01/2023] Open
Abstract
Friedreich ataxia is the most common of the hereditary ataxias. It is due to homozygous/compound heterozygous mutations in FXN. This gene encodes frataxin, a protein largely localized to mitochondria. In about 96% of affected individuals there is homozygosity for a GAA repeat expansion in intron 1 of the FXN gene. Studies of people with Friedreich ataxia and of animal and cell models, have provided much insight into the pathogenesis of this disorder. The expanded GAA repeat leads to transcriptional deficiency of the FXN gene. The consequent deficiency of frataxin protein leads to reduced iron-sulfur cluster biogenesis and mitochondrial ATP production, elevated mitochondrial iron, and oxidative stress. More recently, a role for inflammation has emerged as being important in the pathogenesis of Friedreich ataxia. These findings have led to a number of potential therapies that have been subjected to clinical trials or are being developed toward human studies. Therapies that have been proposed include pharmaceuticals that increase frataxin levels, protein and gene replacement therapies, antioxidants, iron chelators and modulators of inflammation. Whilst no therapies have yet been approved for Friedreich ataxia, there is much optimism that the advances in the understanding of the pathogenesis of this disorder since the discovery its genetic basis, will result in approved disease modifying therapies in the near future.
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Affiliation(s)
- Martin B Delatycki
- Bruce Lefroy Centre, Murdoch Children's Research Institute, Parkville, Victoria, Australia; Victorian Clinical Genetics Services, Parkville, Victoria, Australia; Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia.
| | - Sanjay I Bidichandani
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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20
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Coelho MP, Correia J, Dias A, Nogueira C, Bandeira A, Martins E, Vilarinho L. Iron-sulfur cluster ISD11 deficiency ( LYRM4 gene) presenting as cardiorespiratory arrest and 3-methylglutaconic aciduria. JIMD Rep 2019; 49:11-16. [PMID: 31497476 PMCID: PMC6718106 DOI: 10.1002/jmd2.12058] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 04/23/2019] [Accepted: 05/27/2019] [Indexed: 11/08/2022] Open
Abstract
In the era of genomics, the number of genes linked to mitochondrial disease has been quickly growing, producing massive knowledge on mitochondrial biochemistry. LYRM4 gene codifies for ISD11, a small protein (11 kDa) acting as an iron-sulfur cluster, that has been recently confirmed as a disease-causing gene for mitochondrial disorders. We present a 4-year-old girl patient, born from non-consanguineous healthy parents, with two episodes of cardiorespiratory arrest after respiratory viral illness with progressive decreased activity and lethargy, at the age of 2 and 3 years. She was asymptomatic between crisis with regular growth and normal development. During acute events of illness, she had hyperlactacidemia (maximum lactate 5.2 mmol/L) and urinary excretion of ketone bodies and 3-methylglutaconic acid, which are normalized after recovery. A Next Generation Sequence approach with a broad gene panel designed for mitochondrial disorders revealed a novel probably pathogenic variant in homozygosity in the LYRM4 gene [p.Tyr31Cys (c.92A>G)] with Mendelian segregation. Functional studies in the skeletal muscle confirmed a combined deficiency of the mitochondrial respiratory chain (I, II, and IV complexes). To our knowledge, this is the third case of LYRM4 deficiency worldwide and the first with 3-methylglutaconic aciduria, not reported in any Fe-S cluster deficiency. Remarkably, it appears to be no neurological involvement so far, only with life-threating acute crisis triggered by expectably benign autolimited illnesses. Respiratory chain cofactors and chaperones are a new field of knowledge and can play a remarkable effect in system homeostasis.
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Affiliation(s)
- Margarida Paiva Coelho
- Reference Center for Metabolic DisordersCentro Hospitalar Universitário do PortoPortoPortugal
| | - Joana Correia
- Reference Center for Metabolic DisordersCentro Hospitalar Universitário do PortoPortoPortugal
| | - Aureliano Dias
- Newborn Screening, Metabolism and Genetics Unit, Human Genetics DepartmentNational Institute of Health Doutor Ricardo JorgeLisboaPortugal
| | - Célia Nogueira
- Newborn Screening, Metabolism and Genetics Unit, Human Genetics DepartmentNational Institute of Health Doutor Ricardo JorgeLisboaPortugal
| | - Anabela Bandeira
- Reference Center for Metabolic DisordersCentro Hospitalar Universitário do PortoPortoPortugal
| | - Esmeralda Martins
- Reference Center for Metabolic DisordersCentro Hospitalar Universitário do PortoPortoPortugal
| | - Laura Vilarinho
- Newborn Screening, Metabolism and Genetics Unit, Human Genetics DepartmentNational Institute of Health Doutor Ricardo JorgeLisboaPortugal
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21
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Masud AJ, Kastaniotis AJ, Rahman MT, Autio KJ, Hiltunen JK. Mitochondrial acyl carrier protein (ACP) at the interface of metabolic state sensing and mitochondrial function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:118540. [PMID: 31473256 DOI: 10.1016/j.bbamcr.2019.118540] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/23/2019] [Accepted: 08/27/2019] [Indexed: 12/20/2022]
Abstract
Acyl carrier protein (ACP) is a principal partner in the cytosolic and mitochondrial fatty acid synthesis (FAS) pathways. The active form holo-ACP serves as FAS platform, using its 4'-phosphopantetheine group to present covalently attached FAS intermediates to the enzymes responsible for the acyl chain elongation process. Mitochondrial unacylated holo-ACP is a component of mammalian mitoribosomes, and acylated ACP species participate as interaction partners in several ACP-LYRM (leucine-tyrosine-arginine motif)-protein heterodimers that act either as assembly factors or subunits of the electron transport chain and Fe-S cluster assembly complexes. Moreover, octanoyl-ACP provides the C8 backbone for endogenous lipoic acid synthesis. Accumulating evidence suggests that mtFAS-generated acyl-ACPs act as signaling molecules in an intramitochondrial metabolic state sensing circuit, coordinating mitochondrial acetyl-CoA levels with mitochondrial respiration, Fe-S cluster biogenesis and protein lipoylation.
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Affiliation(s)
- Ali J Masud
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | | | - M Tanvir Rahman
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Kaija J Autio
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - J Kalervo Hiltunen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland.
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22
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Alfadhel M, Nashabat M, Abu Ali Q, Hundallah K. Mitochondrial iron-sulfur cluster biogenesis from molecular understanding to clinical disease. ACTA ACUST UNITED AC 2019; 22:4-13. [PMID: 28064324 PMCID: PMC5726836 DOI: 10.17712/nsj.2017.1.20160542] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Iron–sulfur clusters (ISCs) are known to play a major role in various protein functions. Located in the mitochondria, cytosol, endoplasmic reticulum and nucleus, they contribute to various core cellular functions. Until recently, only a few human diseases related to mitochondrial ISC biogenesis defects have been described. Such diseases include Friedreich ataxia, combined oxidative phosphorylation deficiency 19, infantile complex II/III deficiency defect, hereditary myopathy with lactic acidosis and mitochondrial muscle myopathy, lipoic acid biosynthesis defects, multiple mitochondrial dysfunctions syndromes and non ketotic hyperglycinemia due to glutaredoxin 5 gene defect. Disorders of mitochondrial import, export and translation, including sideroblastic anemia with ataxia, EVEN-PLUS syndrome and mitochondrial complex I deficiency due to nucleotide-binding protein-like protein gene defect, have also been implicated in ISC biogenesis defects. With advances in next generation sequencing technologies, more disorders related to ISC biogenesis defects are expected to be elucidated. In this article, we aim to shed the light on mitochondrial ISC biogenesis, related proteins and their function, pathophysiology, clinical phenotypes of related disorders, diagnostic approach, and future implications.
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Affiliation(s)
- Majid Alfadhel
- Division of Genetics, Department of Pediatrics, King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Riyadh, Kingdom of Saudi Arabia
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Fox NG, Yu X, Feng X, Bailey HJ, Martelli A, Nabhan JF, Strain-Damerell C, Bulawa C, Yue WW, Han S. Structure of the human frataxin-bound iron-sulfur cluster assembly complex provides insight into its activation mechanism. Nat Commun 2019; 10:2210. [PMID: 31101807 PMCID: PMC6525205 DOI: 10.1038/s41467-019-09989-y] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 04/05/2019] [Indexed: 12/13/2022] Open
Abstract
The core machinery for de novo biosynthesis of iron-sulfur clusters (ISC), located in the mitochondria matrix, is a five-protein complex containing the cysteine desulfurase NFS1 that is activated by frataxin (FXN), scaffold protein ISCU, accessory protein ISD11, and acyl-carrier protein ACP. Deficiency in FXN leads to the loss-of-function neurodegenerative disorder Friedreich's ataxia (FRDA). Here the 3.2 Å resolution cryo-electron microscopy structure of the FXN-bound active human complex, containing two copies of the NFS1-ISD11-ACP-ISCU-FXN hetero-pentamer, delineates the interactions of FXN with other component proteins of the complex. FXN binds at the interface of two NFS1 and one ISCU subunits, modifying the local environment of a bound zinc ion that would otherwise inhibit NFS1 activity in complexes without FXN. Our structure reveals how FXN facilitates ISC production through stabilizing key loop conformations of NFS1 and ISCU at the protein-protein interfaces, and suggests how FRDA clinical mutations affect complex formation and FXN activation.
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Affiliation(s)
- Nicholas G Fox
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7DQ, UK
- Merck & Co, 2000 Galloping Hill Rd, Kenilworth, NJ, 07033, USA
| | - Xiaodi Yu
- Discovery Sciences, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
- SMPS, Janssen Research and Development, 1400 McKean Rd, Spring House, PA, 19477, USA
| | - Xidong Feng
- Discovery Sciences, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Henry J Bailey
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7DQ, UK
| | - Alain Martelli
- Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, USA
| | - Joseph F Nabhan
- Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, USA
| | - Claire Strain-Damerell
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7DQ, UK
| | - Christine Bulawa
- Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, USA
| | - Wyatt W Yue
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7DQ, UK.
| | - Seungil Han
- Discovery Sciences, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA.
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Dong YN, McMillan E, Clark EM, Lin H, Lynch DR. GRP75 overexpression rescues frataxin deficiency and mitochondrial phenotypes in Friedreich ataxia cellular models. Hum Mol Genet 2019; 28:1594-1607. [PMID: 30590615 PMCID: PMC6494971 DOI: 10.1093/hmg/ddy448] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 11/19/2018] [Accepted: 12/14/2018] [Indexed: 12/13/2022] Open
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused by the deficiency of frataxin, a mitochondrial protein crucial for iron-sulfur cluster biogenesis and adenosine triphosphate (ATP) production. Currently, there is no therapy to slow down the progression of FRDA. Recent evidence indicates that posttranslational regulation of residual frataxin levels can rescue some of the functional deficit of FRDA, raising the possibility of enhancing levels of residual frataxin as a treatment for FRDA. Here, we present evidence that mitochondrial molecular chaperone GRP75, also known as mortalin/mthsp70/PBP74, directly interacts with frataxin both in vivo in mouse cortex and in vitro in cortical neurons. Overexpressing GRP75 increases the levels of both wild-type frataxin and clinically relevant missense frataxin variants in human embryonic kidney 293 cells, while clinical GRP75 variants such as R126W, A476T and P509S impair the binding of GRP75 with frataxin and the effect of GRP75 on frataxin levels. In addition, GRP75 overexpression rescues frataxin deficiency and abnormal cellular phenotypes such as the abnormal mitochondrial network and decreased ATP levels in FRDA patient-derived cells. The effect of GRP75 on frataxin might be in part mediated by the physical interaction between GRP75 and mitochondrial processing peptidase (MPP), which makes frataxin more accessible to MPP. As GRP75 levels are decreased in multiple cell types of FRDA patients, restoring GRP75 might be effective in treating both typical FRDA patients with two guanine-adenine-adenine repeat expansions and compound heterozygous patients with point mutations.
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Affiliation(s)
- Yi Na Dong
- Department of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Emily McMillan
- Department of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Elisia M Clark
- Department of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Hong Lin
- Department of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David R Lynch
- Department of Pediatrics and Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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25
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Boesch S, Indelicato E. Erythropoietin and Friedreich Ataxia: Time for a Reappraisal? Front Neurosci 2019; 13:386. [PMID: 31105516 PMCID: PMC6491891 DOI: 10.3389/fnins.2019.00386] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 04/04/2019] [Indexed: 12/24/2022] Open
Abstract
Friedreich ataxia (FRDA) is a rare neurological disorder due to deficiency of the mitochondrial protein frataxin. Frataxin deficiency results in impaired mitochondrial function and iron deposition in affected tissues. Erythropoietin (EPO) is a cytokine which was mostly known as a key regulator of erythropoiesis until cumulative evidence showed additional neurotrophic and neuroprotective properties. These features offered the rationale for advancement of EPO in clinical trials in different neurological disorders in the past years, including FRDA. Several mechanisms of action of EPO may be beneficial in FRDA. First of all, EPO exposure results in frataxin upregulation in vitro and in vivo. By promoting erythropoiesis, EPO influences iron metabolism and induces shifts in iron pool which may ameliorate conditions of free iron excess and iron accumulation. Furthermore, EPO signaling is crucial for mitochondrial gene activation and mitochondrial biogenesis. Up to date nine clinical trials investigated the effects of EPO and derivatives in FRDA. The majority of these studies had a proof-of-concept design. Considering the natural history of FRDA, all of them were too short in duration and not powered for clinical changes. However, these studies addressed significant issues in the treatment with EPO, such as (1) the challenge of the dose finding, (2) stability of frataxin up-regulation, (3) continuous versus intermittent stimulation with EPO/regimen, or (4) tissue changes after EPO exposure in humans in vivo (muscle biopsy, brain imaging). Despite several clinical trials in the past, no treatment is available for the treatment of FRDA. Current lines of research focus on gene therapy, frataxin replacement strategies and on regulation of key metabolic checkpoints such as NrF2. Due to potential crosstalk with all these mechanisms, interventions on the EPO pathway still represent a valuable research field. The recent development of small EPO mimetics which maintain cytoprotective properties without erythropoietic action may open a new era in EPO research for the treatment of FRDA.
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Affiliation(s)
- Sylvia Boesch
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
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26
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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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27
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Ferrochelatase activity of plant frataxin. Biochimie 2019; 156:118-122. [DOI: 10.1016/j.biochi.2018.10.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 10/12/2018] [Indexed: 11/21/2022]
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28
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Role of frataxin protein deficiency and metabolic dysfunction in Friedreich ataxia, an autosomal recessive mitochondrial disease. Neuronal Signal 2018; 2:NS20180060. [PMID: 32714592 PMCID: PMC7373238 DOI: 10.1042/ns20180060] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 10/08/2018] [Accepted: 10/10/2018] [Indexed: 01/04/2023] Open
Abstract
Friedreich ataxia (FRDA) is a progressive neurodegenerative disease with developmental features caused by a genetic deficiency of frataxin, a small, nuclear-encoded mitochondrial protein. Frataxin deficiency leads to impairment of iron–sulphur cluster synthesis, and consequently, ATP production abnormalities. Based on the involvement of such processes in FRDA, initial pathophysiological hypotheses focused on reactive oxygen species (ROS) production as a key component of the mechanism. With further study, a variety of other events appear to be involved, including abnormalities of mitochondrially related metabolism and dysfunction in mitochondrial biogenesis. Consequently, present therapies focus not only on free radical damage, but also on control of metabolic abnormalities and correction of mitochondrial biogenesis. Understanding the multitude of abnormalities in FRDA thus offers possibilities for treatment of this disorder.
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29
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Fox NG, Martelli A, Nabhan JF, Janz J, Borkowska O, Bulawa C, Yue WW. Zinc(II) binding on human wild-type ISCU and Met140 variants modulates NFS1 desulfurase activity. Biochimie 2018; 152:211-218. [PMID: 30031876 PMCID: PMC6098246 DOI: 10.1016/j.biochi.2018.07.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 07/18/2018] [Indexed: 12/01/2022]
Abstract
Human de novo iron-sulfur (Fe-S) assembly complex consists of cysteine desulfurase NFS1, accessory protein ISD11, acyl carrier protein ACP, scaffold protein ISCU, and allosteric activator frataxin (FXN). FXN binds the NFS1-ISD11-ACP-ISCU complex (SDAU), to activate the desulfurase activity and Fe-S cluster biosynthesis. In the absence of FXN, the NFS1-ISD11-ACP (SDA) complex was reportedly inhibited by binding of recombinant ISCU. Recent studies also reported a substitution at position Met141 on the yeast ISCU orthologue Isu, to Ile, Leu, Val, or Cys, could bypass the requirement of FXN for Fe-S cluster biosynthesis and cell viability. Here, we show that recombinant human ISCU binds zinc(II) ion, as previously demonstrated with the E. coli orthologue IscU. Surprisingly, the relative proportion between zinc-bound and zinc-depleted forms varies among purification batches. Importantly the presence of zinc in ISCU impacts SDAU desulfurase activity. Indeed, removal of zinc(II) ion from ISCU causes a moderate but significant increase in activity compared to SDA alone, and FXN can activate both zinc-depleted and zinc-bound forms of ISCU complexed to SDA. Taking into consideration the inhibition of desulfurase activity by zinc-bound ISCU, we characterized wild type ISCU and the M140I, M140L, and M140V variants under both zinc-bound and zinc-depleted conditions, and did not observe significant differences in the biochemical and biophysical properties between wild-type and variants. Importantly, in the absence of FXN, ISCU variants behaved like wild-type and did not stimulate the desulfurase activity of the SDA complex. This study therefore identifies an important regulatory role for zinc-bound ISCU in modulation of the human Fe-S assembly system in vitro and reports no 'FXN bypass' effect on mutations at position Met140 in human ISCU. Furthermore, this study also calls for caution in interpreting studies involving recombinant ISCU by taking into consideration the influence of the bound zinc(II) ion on SDAU complex activity.
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Affiliation(s)
- Nicholas G Fox
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, OX3 7DQ, UK
| | - Alain Martelli
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, United States
| | - Joseph F Nabhan
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, United States
| | - Jay Janz
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, United States
| | - Oktawia Borkowska
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, OX3 7DQ, UK
| | - Christine Bulawa
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., 610 Main Street, Cambridge, MA, 02139, United States.
| | - Wyatt W Yue
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, OX3 7DQ, UK.
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30
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Chiang S, Kalinowski DS, Jansson PJ, Richardson DR, Huang MLH. Mitochondrial dysfunction in the neuro-degenerative and cardio-degenerative disease, Friedreich's ataxia. Neurochem Int 2018; 117:35-48. [PMID: 28782591 DOI: 10.1016/j.neuint.2017.08.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 07/25/2017] [Accepted: 08/03/2017] [Indexed: 01/09/2023]
Abstract
Mitochondrial homeostasis is essential for maintaining healthy cellular function and survival. The detrimental involvement of mitochondrial dysfunction in neuro-degenerative diseases has recently been highlighted in human conditions, such as Parkinson's, Alzheimer's and Huntington's disease. Friedreich's ataxia (FA) is another neuro-degenerative, but also cardio-degenerative condition, where mitochondrial dysfunction plays a crucial role in disease progression. Deficient expression of the mitochondrial protein, frataxin, is the primary cause of FA, which leads to adverse alterations in whole cell and mitochondrial iron metabolism. Dys-regulation of iron metabolism in these compartments, results in the accumulation of inorganic iron deposits in the mitochondrial matrix that is thought to potentiate oxidative damage observed in FA. Therefore, the maintenance of mitochondrial homeostasis is crucial in the progression of neuro-degenerative conditions, particularly in FA. In this review, vital mitochondrial homeostatic processes and their roles in FA pathogenesis will be discussed. These include mitochondrial iron processing, mitochondrial dynamics (fusion and fission processes), mitophagy, mitochondrial biogenesis, mitochondrial energy production and calcium metabolism.
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Affiliation(s)
- Shannon Chiang
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Danuta S Kalinowski
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Patric J Jansson
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Des R Richardson
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia.
| | - Michael L-H Huang
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006, Australia.
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31
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Gomez-Casati DF, Busi MV, Pagani MA. Plant Frataxin in Metal Metabolism. FRONTIERS IN PLANT SCIENCE 2018; 9:1706. [PMID: 30519254 PMCID: PMC6258813 DOI: 10.3389/fpls.2018.01706] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 11/02/2018] [Indexed: 05/08/2023]
Abstract
Frataxin is a highly conserved protein from prokaryotes to eukaryotes. Several functions related to iron metabolism have been postulated for this protein, including Fe-S cluster and heme synthesis, response to oxidative damage and oxidative phosphorylation. In plants, the presence of one or two isoforms of this protein with dual localization in mitochondria and chloroplasts has been reported. Frataxin deficiency affects iron metabolism in both organelles, leading to an impairment of mitochondrial respiration, and chlorophyll and photosynthetic electron transport deficiency in chloroplasts. In addition, plant frataxins can react with Cu2+ ions and dimerize, which causes the reduction of free Cu ions. This could provide an additional defense mechanism against the oxidation of Fe-S groups by Cu ions. While there is a consensus on the involvement of frataxin in iron homeostasis in most organisms, the interaction of plant frataxins with Cu ions, the presence of different isoforms, and/or the localization in two plant organelles suggest that this protein might have additional functions in vegetal tissues.
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32
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Affiliation(s)
| | - Sylvia Bösch
- Neurology Department, Innsbruck Medical University, Innsbruck, Austria
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33
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Abstract
Iron-sulfur clusters (Fe/S clusters) are essential cofactors required throughout the clades of biology for performing a myriad of unique functions including nitrogen fixation, ribosome assembly, DNA repair, mitochondrial respiration, and metabolite catabolism. Although Fe/S clusters can be synthesized in vitro and transferred to a client protein without enzymatic assistance, biology has evolved intricate mechanisms to assemble and transfer Fe/S clusters within the cellular environment. In eukaryotes, the foundation of all cellular clusters starts within the mitochondria. The focus of this review is to detail the mitochondrial Fe/S biogenesis (ISC) pathway along with the Fe/S cluster transfer steps necessary to mature Fe/S proteins. New advances in our understanding of the mitochondrial Fe/S biogenesis machinery will be highlighted. Additionally, we will address various experimental approaches that have been successful in the identification and characterization of components of the ISC pathway.
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Affiliation(s)
- Andrew Melber
- University of Utah Health Sciences Center, Salt Lake City, Utah, United States
| | - Dennis R Winge
- University of Utah Health Sciences Center, Salt Lake City, Utah, United States.
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34
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Jasoliya MJ, McMackin MZ, Henderson CK, Perlman SL, Cortopassi GA. Frataxin deficiency impairs mitochondrial biogenesis in cells, mice and humans. Hum Mol Genet 2017; 26:2627-2633. [PMID: 28444186 PMCID: PMC6251520 DOI: 10.1093/hmg/ddx141] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 04/01/2017] [Accepted: 04/10/2017] [Indexed: 12/14/2022] Open
Abstract
Friedreich's ataxia (FRDA) is a neurodegenerative disease caused by inherited deficiency of the mitochondrial protein Frataxin (FXN), which has no approved therapy and is an area in which biomarkers are needed for clinical development. Here, we investigated the consequences of FXN deficiency in patient-derived FRDA fibroblast cell models, the FRDA mouse model KIKO, and in whole blood collected from patients with FRDA. We observed decreased mitochondrial copy number in all the three FRDA models tested: cells, mice and patient blood. In addition, we observed 40% residual mitochondrial gene expression in FRDA patient blood. These deficiencies of mitochondrial biogenesis in FRDA cells and patient blood are significantly correlated with FXN expression, consistent with the idea that the decreased mitochondrial biogenesis is a consequence of FXN deficiency. The observations appear relevant to the FRDA pathophysiological mechanism, as FXN-dependent deficiency in mitochondrial biogenesis and consequent mitochondrial bioenergetic defect could contribute to the neurodegenerative process. The observations may also have translational potential, as mitochondrial biogenesis could now be followed as a clinical biomarker of FRDA as a correlate of disease severity, progression, and therapeutic effect. Also, mitochondrial copy number in blood is objective, scalar and more investigator-independent than clinical-neurological patient rating scales. Thus, FXN deficiency causes mitochondrial deficiency in FRDA cells, the KIKO mouse model, and in whole blood of patients with FRDA, and this deficiency could potentially be used in clinical trial design.
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Affiliation(s)
- Mittal J. Jasoliya
- Department of Molecular Biosciences, University of California School of Veterinary Medicine, Davis, CA 95616, USA
| | - Marissa Z. McMackin
- Department of Molecular Biosciences, University of California School of Veterinary Medicine, Davis, CA 95616, USA
| | - Chelsea K. Henderson
- Department of Molecular Biosciences, University of California School of Veterinary Medicine, Davis, CA 95616, USA
| | - Susan L. Perlman
- Department of Neurology, University of California School of Medicine, Los Angeles, CA 90095, USA
| | - Gino A. Cortopassi
- Department of Molecular Biosciences, University of California School of Veterinary Medicine, Davis, CA 95616, USA
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35
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Dong Y, Zhang D, Yu Q, Zhao Q, Xiao C, Zhang K, Jia C, Chen S, Zhang B, Zhang B, Li M. Loss of Ssq1 leads to mitochondrial dysfunction, activation of autophagy and cell cycle arrest due to iron overload triggered by mitochondrial iron-sulfur cluster assembly defects in Candida albicans. Int J Biochem Cell Biol 2017; 85:44-55. [PMID: 28163187 DOI: 10.1016/j.biocel.2017.01.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 12/30/2016] [Accepted: 01/29/2017] [Indexed: 01/10/2023]
Abstract
Iron-sulfur clusters perform essential functions in enzymatic catalysis and homeostatic regulation. Here we for the first time identified Ssq1 as an essential component for iron-sulfur cluster assembly in Candida albicans. Ssq1 played an important role in cell growth. Shutting off SSQ1 led to accumulation of intracellular iron, especially in mitochondria, and disorder of intracellular iron regulation. In tetO-SSQ1, iron overloading triggered the oxidative damage of mitochondrial function. Surprisingly, disruption of SSQ1 activated autophagic pathway. The mitochondrial dysfunction was further aggravated when CCZ1 (which is essential for autophagy) and SSQ1 was simultaneously deleted, suggesting that autophagy played a critical role in maintenance of mitochondrial function in tetO-SSQ1. In addition, double deletion of SSQ1 and CCZ1 further elevated cellular iron levels in comparison with tetO-SSQ1, indicating that autophagy participated in maintenance of iron homeostasis. Furthermore, we found that loss of SSQ1 led to increasing protein expression of Rnr1 and redistribution of Rnr2 from the nucleus to cytoplasm, and further resulted in cell cycle arrest. The results implied that cell cycle arrest was caused by activating the checkpoint pathway because of impairing the iron-sulfur cluster assembly in tetO-SSQ1. Shutting off SSQ1 led to a significant defect in filamentous development. Interestingly, the tetO-SSQ1ccz1Δ/Δ growth was inhibited on hyphae-inducing solid media. Both tetO-SSQ1 and tetO-SSQ1ccz1Δ/Δ exhibited extremely attenuated virulence, indicating that Ssq1 might provide a promising target for antifungal drugs development. In summary, our findings provide new insights into the understanding of iron-sulfur cluster assembly-related gene in C. albicans.
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Affiliation(s)
- Yijie Dong
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China; The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, PR China
| | - Dan Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Qilin Yu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Qiang Zhao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Chenpeng Xiao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Kai Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Chang Jia
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Sijia Chen
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Bing Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China
| | - Biao Zhang
- Tianjin University of Traditional Chinese Medicine, Tianjin, PR China
| | - Mingchun Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, PR China.
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36
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Mitochondrial Protein Interaction Mapping Identifies Regulators of Respiratory Chain Function. Mol Cell 2016; 63:621-632. [PMID: 27499296 DOI: 10.1016/j.molcel.2016.06.033] [Citation(s) in RCA: 196] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 03/25/2016] [Accepted: 06/21/2016] [Indexed: 12/23/2022]
Abstract
Mitochondria are essential for numerous cellular processes, yet hundreds of their proteins lack robust functional annotation. To reveal functions for these proteins (termed MXPs), we assessed condition-specific protein-protein interactions for 50 select MXPs using affinity enrichment mass spectrometry. Our data connect MXPs to diverse mitochondrial processes, including multiple aspects of respiratory chain function. Building upon these observations, we validated C17orf89 as a complex I (CI) assembly factor. Disruption of C17orf89 markedly reduced CI activity, and its depletion is found in an unresolved case of CI deficiency. We likewise discovered that LYRM5 interacts with and deflavinates the electron-transferring flavoprotein that shuttles electrons to coenzyme Q (CoQ). Finally, we identified a dynamic human CoQ biosynthetic complex involving multiple MXPs whose topology we map using purified components. Collectively, our data lend mechanistic insight into respiratory chain-related activities and prioritize hundreds of additional interactions for further exploration of mitochondrial protein function.
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37
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Chen K, Lin G, Haelterman NA, Ho TSY, Li T, Li Z, Duraine L, Graham BH, Jaiswal M, Yamamoto S, Rasband MN, Bellen HJ. Loss of Frataxin induces iron toxicity, sphingolipid synthesis, and Pdk1/Mef2 activation, leading to neurodegeneration. eLife 2016; 5:e16043. [PMID: 27343351 PMCID: PMC4956409 DOI: 10.7554/elife.16043] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 06/24/2016] [Indexed: 12/22/2022] Open
Abstract
Mutations in Frataxin (FXN) cause Friedreich's ataxia (FRDA), a recessive neurodegenerative disorder. Previous studies have proposed that loss of FXN causes mitochondrial dysfunction, which triggers elevated reactive oxygen species (ROS) and leads to the demise of neurons. Here we describe a ROS independent mechanism that contributes to neurodegeneration in fly FXN mutants. We show that loss of frataxin homolog (fh) in Drosophila leads to iron toxicity, which in turn induces sphingolipid synthesis and ectopically activates 3-phosphoinositide dependent protein kinase-1 (Pdk1) and myocyte enhancer factor-2 (Mef2). Dampening iron toxicity, inhibiting sphingolipid synthesis by Myriocin, or reducing Pdk1 or Mef2 levels, all effectively suppress neurodegeneration in fh mutants. Moreover, increasing dihydrosphingosine activates Mef2 activity through PDK1 in mammalian neuronal cell line suggesting that the mechanisms are evolutionarily conserved. Our results indicate that an iron/sphingolipid/Pdk1/Mef2 pathway may play a role in FRDA.
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Affiliation(s)
- Kuchuan Chen
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Guang Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Nele A Haelterman
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Tammy Szu-Yu Ho
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Tongchao Li
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Zhihong Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Lita Duraine
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Brett H Graham
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Manish Jaiswal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Shinya Yamamoto
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, United States
| | - Matthew N Rasband
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Hugo J Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, United States
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38
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Chiang S, Kovacevic Z, Sahni S, Lane DJR, Merlot AM, Kalinowski DS, Huang MLH, Richardson DR. Frataxin and the molecular mechanism of mitochondrial iron-loading in Friedreich's ataxia. Clin Sci (Lond) 2016; 130:853-70. [PMID: 27129098 DOI: 10.1042/cs20160072] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/16/2016] [Indexed: 12/19/2022]
Abstract
The mitochondrion is a major site for the metabolism of the transition metal, iron, which is necessary for metabolic processes critical for cell vitality. The enigmatic mitochondrial protein, frataxin, is known to play a significant role in both cellular and mitochondrial iron metabolism due to its iron-binding properties and its involvement in iron-sulfur cluster (ISC) and heme synthesis. The inherited neuro- and cardio-degenerative disease, Friedreich's ataxia (FA), is caused by the deficient expression of frataxin that leads to deleterious alterations in iron metabolism. These changes lead to the accumulation of inorganic iron aggregates in the mitochondrial matrix that are presumed to play a key role in the oxidative damage and subsequent degenerative features of this disease. Furthermore, the concurrent dys-regulation of cellular antioxidant defense, which coincides with frataxin deficiency, exacerbates oxidative stress. Hence, the pathogenesis of FA underscores the importance of the integrated homeostasis of cellular iron metabolism and the cytoplasmic and mitochondrial redox environments. This review focuses on describing the pathogenesis of the disease, the molecular mechanisms involved in mitochondrial iron-loading and the dys-regulation of cellular antioxidant defense due to frataxin deficiency. In turn, current and emerging therapeutic strategies are also discussed.
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Affiliation(s)
- Shannon Chiang
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Zaklina Kovacevic
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Sumit Sahni
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Darius J R Lane
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Angelica M Merlot
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Danuta S Kalinowski
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Michael L-H Huang
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia )
| | - Des R Richardson
- Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia )
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39
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Turowski VR, Aknin C, Maliandi MV, Buchensky C, Leaden L, Peralta DA, Busi MV, Araya A, Gomez-Casati DF. Frataxin Is Localized to Both the Chloroplast and Mitochondrion and Is Involved in Chloroplast Fe-S Protein Function in Arabidopsis. PLoS One 2015; 10:e0141443. [PMID: 26517126 PMCID: PMC4636843 DOI: 10.1371/journal.pone.0141443] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/07/2015] [Indexed: 11/19/2022] Open
Abstract
Frataxin plays a key role in eukaryotic cellular iron metabolism, particularly in mitochondrial heme and iron-sulfur (Fe-S) cluster biosynthesis. However, its precise role has yet to be elucidated. In this work, we studied the subcellular localization of Arabidopsis frataxin, AtFH, using confocal microscopy, and found a novel dual localization for this protein. We demonstrate that plant frataxin is targeted to both the mitochondria and the chloroplast, where it may play a role in Fe-S cluster metabolism as suggested by functional studies on nitrite reductase (NIR) and ferredoxin (Fd), two Fe-S containing chloroplast proteins, in AtFH deficient plants. Our results indicate that frataxin deficiency alters the normal functioning of chloroplasts by affecting the levels of Fe, chlorophyll, and the photosynthetic electron transport chain in this organelle.
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Affiliation(s)
- Valeria R. Turowski
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Cindy Aknin
- UMR5234 Microbiologie Fondamentale et Pathogénicité, Centre National de la Recherche Scientifique and Université Bordeaux-Segalen, 146 rue Léo Saignat, 33076, Bordeaux cedex, France
| | - Maria V. Maliandi
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH) CONICET/UNSAM, Camino de Circunvaación Km 6, 7130, Chascomús, Argentina
| | - Celeste Buchensky
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Laura Leaden
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Diego A. Peralta
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Maria V. Busi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Alejandro Araya
- Centre National de la Recherche Scientifique & UMR 1332 –Biologie du Fruit et Pathologie, Institute National de la Recherche Agronomique (INRA) Bordeaux Aquitaine, 71 avenue Edouard Bourlaux, 33882, Villenave D’Ornon, France
| | - Diego F. Gomez-Casati
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
- * E-mail:
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40
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Abstract
Mitochondrial dysfunction underlies many human disorders, including those that affect the visual system. The retinal ganglion cells, whose axons form the optic nerve, are often damaged by mitochondrial-related diseases which result in blindness. Both mitochondrial DNA (mtDNA) and nuclear gene mutations impacting many different mitochondrial processes can result in optic nerve disease. Of particular importance are mutations that impair mitochondrial network dynamics (fusion and fission), oxidative phosphorylation (OXPHOS), and formation of iron-sulfur complexes. Current genetic knowledge can inform genetic counseling and suggest strategies for novel gene-based therapies. Identifying new optic neuropathy-causing genes and defining the role of current and novel genes in disease will be important steps toward the development of effective and potentially neuroprotective therapies.
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Affiliation(s)
- Janey L Wiggs
- Department of Ophthalmology, Harvard Medical School and Massachusetts Eye and Ear, Boston, Massachusetts 02114;
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41
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Saha PP, Srivastava S, Kumar S K P, Sinha D, D'Silva P. Mapping Key Residues of ISD11 Critical for NFS1-ISD11 Subcomplex Stability: IMPLICATIONS IN THE DEVELOPMENT OF MITOCHONDRIAL DISORDER, COXPD19. J Biol Chem 2015; 290:25876-90. [PMID: 26342079 DOI: 10.1074/jbc.m115.678508] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Indexed: 11/06/2022] Open
Abstract
Biogenesis of the iron-sulfur (Fe-S) cluster is an indispensable process in living cells. In mammalian mitochondria, the initial step of the Fe-S cluster assembly process is assisted by the NFS1-ISD11 complex, which delivers sulfur to scaffold protein ISCU during Fe-S cluster synthesis. Although ISD11 is an essential protein, its cellular role in Fe-S cluster biogenesis is still not defined. Our study maps the important ISD11 amino acid residues belonging to putative helix 1 (Phe-40), helix 3 (Leu-63, Arg-68, Gln-69, Ile-72, Tyr-76), and C-terminal segment (Leu-81, Glu-84) are critical for in vivo Fe-S cluster biogenesis. Importantly, mutation of these conserved ISD11 residues into alanine leads to its compromised interaction with NFS1, resulting in reduced stability and enhanced aggregation of NFS1 in the mitochondria. Due to altered interaction with ISD11 mutants, the levels of NFS1 and Isu1 were significantly depleted, which affects Fe-S cluster biosynthesis, leading to reduced electron transport chain complex (ETC) activity and mitochondrial respiration. In humans, a clinically relevant ISD11 mutation (R68L) has been associated in the development of a mitochondrial genetic disorder, COXPD19. Our findings highlight that the ISD11 R68A/R68L mutation display reduced affinity to form a stable subcomplex with NFS1, and thereby fails to prevent NFS1 aggregation resulting in impairment of the Fe-S cluster biogenesis. The prime affected machinery is the ETC complex, which showed compromised redox properties, causing diminished mitochondrial respiration. Furthermore, the R68L ISD11 mutant displayed accumulation of mitochondrial iron and reactive oxygen species, leading to mitochondrial dysfunction, which correlates with the phenotype observed in COXPD19 patients.
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Affiliation(s)
- Prasenjit Prasad Saha
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, Karnataka and
| | - Shubhi Srivastava
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, Karnataka and
| | - Praveen Kumar S K
- the Department of Biochemistry, Karnatak University, Dharwad 580003, Karnataka, India
| | - Devanjan Sinha
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, Karnataka and
| | - Patrick D'Silva
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, Karnataka and
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42
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Zaidi A, Singh KP, Anwar S, Suman SS, Equbal A, Singh K, Dikhit MR, Bimal S, Pandey K, Das P, Ali V. Interaction of frataxin, an iron binding protein, with IscU of Fe-S clusters biogenesis pathway and its upregulation in AmpB resistant Leishmania donovani. Biochimie 2015; 115:120-35. [PMID: 26032732 DOI: 10.1016/j.biochi.2015.05.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 05/19/2015] [Indexed: 01/10/2023]
Abstract
Leishmania donovani is a unicellular protozoon parasite that causes visceral leishmaniasis (VL), which is a fatal disease if left untreated. Certain Fe-S proteins of the TCA cycle and respiratory chain have been found in the Leishmania parasite but the precise mechanisms for their biogenesis and the maturation of Fe-S clusters remains unknown. Fe-S clusters are ubiquitous cofactors of proteins that perform critical cellular functions. The clusters are biosynthesized by the mitochondrial Iron-Sulphur Cluster (ISC) machinery with core protein components that include the catalytic cysteine desulphurase IscS, the scaffold proteins IscU and IscA, and frataxin as an iron carrier/donor. However, no information regarding frataxin, its regulation, or its role in drug resistance is available for the Leishmania parasite. In this study, we characterized Ld-frataxin to investigate its role in the ISC machinery of L. donovani. We expressed and purified the recombinant Ld-frataxin protein and observed its interaction with Ld-IscU by co-purification and pull-down assay. Furthermore, we observed that the cysteine desulphurase activity of the purified Ld-IscS protein was stimulated in the presence of Ld-frataxin and Ld-IscU, particularly in the presence of iron; neither Ld-frataxin nor Ld-IscU alone had significant effects on Ld-IscS activity. Interestingly, RT-PCR and western blotting showed that Ld-frataxin is upregulated in AmpB-resistant isolates compared to sensitive strains, which may support higher Fe-S protein activity in AmpB-resistant L. donovani. Additionally, Ld-frataxin was localized in the mitochondria, as revealed by digitonin fractionation and indirect immunofluorescence. Thus, our results suggest the role of Ld-frataxin as an iron binding/carrier protein for Fe-S cluster biogenesis that physically interacts with other core components of the ISC machinery within the mitochondria.
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Affiliation(s)
- Amir Zaidi
- Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna 800007, India
| | - Krishn Pratap Singh
- Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna 800007, India
| | - Shadab Anwar
- Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna 800007, India
| | - Shashi S Suman
- Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna 800007, India
| | - Asif Equbal
- Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna 800007, India
| | - Kuljit Singh
- Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna 800007, India
| | - Manas R Dikhit
- Biomedical Informatic Centre, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna, India
| | - Sanjeeva Bimal
- Department of Immunology, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna, India
| | - Krishna Pandey
- Department of Clinical Medicine, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna, India
| | - Pradeep Das
- Department of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna, India
| | - Vahab Ali
- Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), Agamkuan, Patna 800007, India.
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43
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Angerer H. Eukaryotic LYR Proteins Interact with Mitochondrial Protein Complexes. BIOLOGY 2015; 4:133-50. [PMID: 25686363 PMCID: PMC4381221 DOI: 10.3390/biology4010133] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 02/04/2015] [Indexed: 01/18/2023]
Abstract
In eukaryotic cells, mitochondria host ancient essential bioenergetic and biosynthetic pathways. LYR (leucine/tyrosine/arginine) motif proteins (LYRMs) of the Complex1_LYR-like superfamily interact with protein complexes of bacterial origin. Many LYR proteins function as extra subunits (LYRM3 and LYRM6) or novel assembly factors (LYRM7, LYRM8, ACN9 and FMC1) of the oxidative phosphorylation (OXPHOS) core complexes. Structural insights into complex I accessory subunits LYRM6 and LYRM3 have been provided by analyses of EM and X-ray structures of complex I from bovine and the yeast Yarrowia lipolytica, respectively. Combined structural and biochemical studies revealed that LYRM6 resides at the matrix arm close to the ubiquinone reduction site. For LYRM3, a position at the distal proton-pumping membrane arm facing the matrix space is suggested. Both LYRMs are supposed to anchor an acyl-carrier protein (ACPM) independently to complex I. The function of this duplicated protein interaction of ACPM with respiratory complex I is still unknown. Analysis of protein-protein interaction screens, genetic analyses and predicted multi-domain LYRMs offer further clues on an interaction network and adaptor-like function of LYR proteins in mitochondria.
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Affiliation(s)
- Heike Angerer
- Goethe University Frankfurt, Medical School, Institute of Biochemistry II, Structural Bioenergetics Group, Max-von-Laue Street 9, Frankfurt am Main 60438, Germany.
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44
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Sahdeo S, Scott BD, McMackin MZ, Jasoliya M, Brown B, Wulff H, Perlman SL, Pook MA, Cortopassi GA. Dyclonine rescues frataxin deficiency in animal models and buccal cells of patients with Friedreich's ataxia. Hum Mol Genet 2014; 23:6848-62. [PMID: 25113747 PMCID: PMC4245046 DOI: 10.1093/hmg/ddu408] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/02/2014] [Accepted: 08/04/2014] [Indexed: 12/18/2022] Open
Abstract
Inherited deficiency in the mitochondrial protein frataxin (FXN) causes the rare disease Friedreich's ataxia (FA), for which there is no successful treatment. We identified a redox deficiency in FA cells and used this to model the disease. We screened a 1600-compound library to identify existing drugs, which could be of therapeutic benefit. We identified the topical anesthetic dyclonine as protective. Dyclonine increased FXN transcript and FXN protein dose-dependently in FA cells and brains of animal models. Dyclonine also rescued FXN-dependent enzyme deficiencies in the iron-sulfur enzymes, aconitase and succinate dehydrogenase. Dyclonine induces the Nrf2 [nuclear factor (erythroid-derived 2)-like 2] transcription factor, which we show binds an upstream response element in the FXN locus. Additionally, dyclonine also inhibited the activity of histone methyltransferase G9a, known to methylate histone H3K9 to silence FA chromatin. Chronic dosing in a FA mouse model prevented a performance decline in balance beam studies. A human clinical proof-of-concept study was completed in eight FA patients dosed twice daily using a 1% dyclonine rinse for 1 week. Six of the eight patients showed an increase in buccal cell FXN levels, and fold induction was significantly correlated with disease severity. Dyclonine represents a novel therapeutic strategy that can potentially be repurposed for the treatment of FA.
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Affiliation(s)
- Sunil Sahdeo
- Department of Molecular Biosciences, School of Veterinary Medicine
| | - Brian D Scott
- Department of Molecular Biosciences, School of Veterinary Medicine
| | | | - Mittal Jasoliya
- Department of Molecular Biosciences, School of Veterinary Medicine
| | - Brandon Brown
- Department of Pharmacology, School of Medicine, University of California, Davis, CA 95616, USA
| | - Heike Wulff
- Department of Pharmacology, School of Medicine, University of California, Davis, CA 95616, USA
| | - Susan L Perlman
- Department of Neurology, University of California School of Medicine, Los Angeles, CA 90095, USA and
| | - Mark A Pook
- School of Health Sciences and Social Care, Brunel University, Uxbridge UB8 3PH, UK
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45
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Kim JH, Bothe JR, Alderson TR, Markley JL. Tangled web of interactions among proteins involved in iron-sulfur cluster assembly as unraveled by NMR, SAXS, chemical crosslinking, and functional studies. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1416-28. [PMID: 25450980 DOI: 10.1016/j.bbamcr.2014.11.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 10/18/2014] [Accepted: 11/13/2014] [Indexed: 12/26/2022]
Abstract
Proteins containing iron-sulfur (Fe-S) clusters arose early in evolution and are essential to life. Organisms have evolved machinery consisting of specialized proteins that operate together to assemble Fe-S clusters efficiently so as to minimize cellular exposure to their toxic constituents: iron and sulfide ions. To date, the best studied system is the iron-sulfur cluster (isc) operon of Escherichia coli, and the eight ISC proteins it encodes. Our investigations over the past five years have identified two functional conformational states for the scaffold protein (IscU) and have shown that the other ISC proteins that interact with IscU prefer to bind one conformational state or the other. From analyses of the NMR spectroscopy-derived network of interactions of ISC proteins, small-angle X-ray scattering (SAXS) data, chemical crosslinking experiments, and functional assays, we have constructed working models for Fe-S cluster assembly and delivery. Future work is needed to validate and refine what has been learned about the E. coli system and to extend these findings to the homologous Fe-S cluster biosynthetic machinery of yeast and human mitochondria. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases.
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Affiliation(s)
- Jin Hae Kim
- Biochemistry Department, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jameson R Bothe
- Biochemistry Department, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - T Reid Alderson
- Biochemistry Department, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - John L Markley
- Biochemistry Department, University of Wisconsin-Madison, Madison, WI 53706, USA.
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46
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Song L, Cortopassi G. Mitochondrial complex I defects increase ubiquitin in substantia nigra. Brain Res 2014; 1594:82-91. [PMID: 25446449 DOI: 10.1016/j.brainres.2014.11.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 10/16/2014] [Accepted: 11/07/2014] [Indexed: 11/18/2022]
Abstract
Parkinson׳s disease (PD) is the second most common neurodegenerative disorder in the developed world, and is characterized by the loss of dopaminergic (DA) neurons in the substantia nigra (SN) of midbrain. Mitochondrial complex I dysfunction has been implicated in PD pathophysiology, yet the molecular mechanism by which complex I defects may cause DA neurodegeneration remain unclear. Using Ndufs4 mouse model of mitochondrial complex I deficiency, we observed a remarkable ubiquitin protein increase in SN of Ndufs4-/- (KO) mice. By contrast, neurofilaments were significantly decreased in SN of KO mice. Furthermore, mass spectrometry and co-immunoprecipitation (Co-IP) analysis indicated an increase in ubiquitinated neurofilaments in midbrain of KO mice, whereas 20S proteasome activities were decreased, which could potentially explain the buildup of ubiquitin protein. Collectively, these data suggest that mitochondrial complex I defects cause proteasome inhibition, a consequent increase in ubiquitinated neurofilaments and other proteins, and decrease the expression of neurofilaments that could be relevant to the mechanism of DA neuronal death in PD.
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Affiliation(s)
- Lanying Song
- Department of Molecular Biosciences, University of California, Davis, CA 95616, USA
| | - Gino Cortopassi
- Department of Molecular Biosciences, University of California, Davis, CA 95616, USA.
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47
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Manicki M, Majewska J, Ciesielski S, Schilke B, Blenska A, Kominek J, Marszalek J, Craig EA, Dutkiewicz R. Overlapping binding sites of the frataxin homologue assembly factor and the heat shock protein 70 transfer factor on the Isu iron-sulfur cluster scaffold protein. J Biol Chem 2014; 289:30268-30278. [PMID: 25228696 PMCID: PMC4215211 DOI: 10.1074/jbc.m114.596726] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/12/2014] [Indexed: 11/06/2022] Open
Abstract
In mitochondria FeS clusters, prosthetic groups critical for the activity of many proteins, are first assembled on Isu, a 14-kDa scaffold protein, and then transferred to recipient apoproteins. The assembly process involves interaction of Isu with both Nfs1, the cysteine desulfurase serving as a sulfur donor, and the yeast frataxin homolog (Yfh1) serving as a regulator of desulfurase activity and/or iron donor. Here, based on the results of biochemical experiments with purified wild-type and variant proteins, we report that interaction of Yfh1 with both Nfs1 and Isu are required for formation of a stable tripartite assembly complex. Disruption of either Yfh1-Isu or Nfs1-Isu interactions destabilizes the complex. Cluster transfer to recipient apoprotein is known to require the interaction of Isu with the J-protein/Hsp70 molecular chaperone pair, Jac1 and Ssq1. Here we show that the Yfh1 interaction with Isu involves the PVK sequence motif, which is also the site key for the interaction of Isu with Hsp70 Ssq1. Coupled with our previous observation that Nfs1 and Jac1 binding to Isu is mutually exclusive due to partially overlapping binding sites, we propose that such mutual exclusivity of cluster assembly factor (Nfs1/Yfh1) and cluster transfer factor (Jac1/Ssq1) binding to Isu has functional consequences for the transition from the assembly process to the transfer process, and thus regulation of the biogenesis of FeS cluster proteins.
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Affiliation(s)
- Mateusz Manicki
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk 80822, Poland and
| | - Julia Majewska
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk 80822, Poland and; Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Szymon Ciesielski
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Brenda Schilke
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Anna Blenska
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk 80822, Poland and
| | - Jacek Kominek
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk 80822, Poland and
| | - Jaroslaw Marszalek
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk 80822, Poland and; Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706.
| | - Elizabeth A Craig
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706.
| | - Rafal Dutkiewicz
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk 80822, Poland and
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48
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Bridwell-Rabb J, Fox N, Tsai CL, Winn AM, Barondeau DP. Human frataxin activates Fe-S cluster biosynthesis by facilitating sulfur transfer chemistry. Biochemistry 2014; 53:4904-13. [PMID: 24971490 PMCID: PMC4215901 DOI: 10.1021/bi500532e] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 06/26/2014] [Indexed: 01/11/2023]
Abstract
Iron-sulfur clusters are ubiquitous protein cofactors with critical cellular functions. The mitochondrial Fe-S assembly complex, which consists of the cysteine desulfurase NFS1 and its accessory protein (ISD11), the Fe-S assembly protein (ISCU2), and frataxin (FXN), converts substrates l-cysteine, ferrous iron, and electrons into Fe-S clusters. The physiological function of FXN has received a tremendous amount of attention since the discovery that its loss is directly linked to the neurodegenerative disease Friedreich's ataxia. Previous in vitro results revealed a role for human FXN in activating the cysteine desulfurase and Fe-S cluster biosynthesis activities of the Fe-S assembly complex. Here we present radiolabeling experiments that indicate FXN accelerates the accumulation of sulfur on ISCU2 and that the resulting persulfide species is viable in the subsequent synthesis of Fe-S clusters. Additional mutagenesis, enzyme kinetic, UV-visible, and circular dichroism spectroscopic studies suggest conserved ISCU2 residue C104 is critical for FXN activation, whereas C35, C61, and C104 are all essential for Fe-S cluster formation on the assembly complex. These results cannot be fully explained by the hypothesis that FXN functions as an iron donor for Fe-S cluster biosynthesis, and further support an allosteric regulator role for FXN. Together, these results lead to an activation model in which FXN accelerates persulfide formation on NFS1 and favors a helix-to-coil interconversion on ISCU2 that facilitates the transfer of sulfur from NFS1 to ISCU2 as an initial step in Fe-S cluster biosynthesis.
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Affiliation(s)
- Jennifer Bridwell-Rabb
- Department of Chemistry, Texas A&M
University, College Station, Texas 77842, United States
| | - Nicholas
G. Fox
- Department of Chemistry, Texas A&M
University, College Station, Texas 77842, United States
| | - Chi-Lin Tsai
- Department of Chemistry, Texas A&M
University, College Station, Texas 77842, United States
| | - Andrew M. Winn
- Department of Chemistry, Texas A&M
University, College Station, Texas 77842, United States
| | - David P. Barondeau
- Department of Chemistry, Texas A&M
University, College Station, Texas 77842, United States
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Martelli A, Puccio H. Dysregulation of cellular iron metabolism in Friedreich ataxia: from primary iron-sulfur cluster deficit to mitochondrial iron accumulation. Front Pharmacol 2014; 5:130. [PMID: 24917819 PMCID: PMC4042101 DOI: 10.3389/fphar.2014.00130] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 05/14/2014] [Indexed: 01/25/2023] Open
Abstract
Friedreich ataxia (FRDA) is the most common recessive ataxia in the Caucasian population and is characterized by a mixed spinocerebellar and sensory ataxia frequently associating cardiomyopathy. The disease results from decreased expression of the FXN gene coding for the mitochondrial protein frataxin. Early histological and biochemical study of the pathophysiology in patient's samples revealed that dysregulation of iron metabolism is a key feature of the disease, mainly characterized by mitochondrial iron accumulation and by decreased activity of iron-sulfur cluster enzymes. In the recent past years, considerable progress in understanding the function of frataxin has been provided through cellular and biochemical approaches, pointing to the primary role of frataxin in iron-sulfur cluster biogenesis. However, why and how the impact of frataxin deficiency on this essential biosynthetic pathway leads to mitochondrial iron accumulation is still poorly understood. Herein, we review data on both the primary function of frataxin and the nature of the iron metabolism dysregulation in FRDA. To date, the pathophysiological implication of the mitochondrial iron overload in FRDA remains to be clarified.
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Affiliation(s)
- Alain Martelli
- Department of Translational Medecine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire Illkirch, France ; INSERM, U596 Illkirch, France ; CNRS, UMR7104 Illkirch, France ; Université de Strasbourg Strasbourg, France ; Chaire de Génétique Humaine, Collège de France Illkirch, France
| | - Hélène Puccio
- Department of Translational Medecine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire Illkirch, France ; INSERM, U596 Illkirch, France ; CNRS, UMR7104 Illkirch, France ; Université de Strasbourg Strasbourg, France ; Chaire de Génétique Humaine, Collège de France Illkirch, France
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50
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Puccio H, Anheim M, Tranchant C. Pathophysiogical and therapeutic progress in Friedreich ataxia. Rev Neurol (Paris) 2014; 170:355-65. [PMID: 24792433 DOI: 10.1016/j.neurol.2014.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/25/2014] [Accepted: 03/26/2014] [Indexed: 01/10/2023]
Abstract
Friedreich ataxia (FRDA) is the most common hereditary autosomal recessive ataxia, but is also a multisystemic condition with frequent presence of cardiomyopathy or diabetes. It has been linked to expansion of a GAA-triplet repeat in the first intron of the FXN gene, leading to a reduced level of frataxin, a mitochondrial protein which, by controlling both iron entry and/or sulfide production, is essential to properly assemble and protect the Fe-S cluster during the initial stage of biogenesis. Several data emphasize the role of oxidative damage in FRDA, but better understanding of pathophysiological consequences of FXN mutations has led to develop animal models. Conditional knockout models recapitulate important features of the human disease but lack the genetic context, GAA repeat expansion-based knock-in and transgenic models carry a GAA repeat expansion but they only show a very mild phenotype. Cells derived from FRDA patients constitute the most relevant frataxin-deficient cell model as they carry the complete frataxin locus together with GAA repeat expansions and regulatory sequences. Induced pluripotent stem cell (iPSC)-derived neurons present a maturation delay and lower mitochondrial membrane potential, while cardiomyocytes exhibit progressive mitochondrial degeneration, with frequent dark mitochondria and proliferation/accumulation of normal mitochondria. Efforts in developing therapeutic strategies can be divided into three categories: iron chelators, antioxidants and/or stimulants of mitochondrial biogenesis, and frataxin level modifiers. A promising therapeutic strategy that is currently the subject of intense research is to directly target the heterochromatin state of the GAA repeat expansion with histone deacytelase inhibitors (HDACi) to restore frataxin levels.
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Affiliation(s)
- H Puccio
- Translational medicine and neurogenetics, institut de génétique et de biologie moléculaire et cellulaire (IGBMC), 1, rue Laurent-Fries, BP 10142, 67404 Illkirch cedex, France; Inserm, U596, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; CNRS, UMR7104, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; Université de Strasbourg, 4, rue Blaise-Pascal, 67400 Strasbourg, France; Collège de France, chaire de génétique humaine, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France
| | - M Anheim
- Translational medicine and neurogenetics, institut de génétique et de biologie moléculaire et cellulaire (IGBMC), 1, rue Laurent-Fries, BP 10142, 67404 Illkirch cedex, France; Inserm, U596, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; CNRS, UMR7104, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; Université de Strasbourg, 4, rue Blaise-Pascal, 67400 Strasbourg, France; Service de neurologie, unité des pathologies du mouvement, hôpital de Hautepierre, hôpital universitaire, 1, place de l'Hôpital, 67000 Strasbourg, France
| | - C Tranchant
- Translational medicine and neurogenetics, institut de génétique et de biologie moléculaire et cellulaire (IGBMC), 1, rue Laurent-Fries, BP 10142, 67404 Illkirch cedex, France; Inserm, U596, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; CNRS, UMR7104, 1, rue Laurent-Fries, 67400 Illkirch Graffenstaden, France; Université de Strasbourg, 4, rue Blaise-Pascal, 67400 Strasbourg, France; Service de neurologie, unité des pathologies du mouvement, hôpital de Hautepierre, hôpital universitaire, 1, place de l'Hôpital, 67000 Strasbourg, France.
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