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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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Rodden LN, Rummey C, Dong YN, Lagedrost S, Regner S, Brocht A, Bushara K, Delatycki MB, Gomez CM, Mathews K, Murray S, Perlman S, Ravina B, Subramony SH, Wilmot G, Zesiewicz T, Bolotta A, Domissy A, Jespersen C, Ji B, Soragni E, Gottesfeld JM, Lynch DR. A non-synonymous single nucleotide polymorphism in SIRT6 predicts neurological severity in Friedreich ataxia. Front Mol Biosci 2022; 9:933788. [PMID: 36133907 PMCID: PMC9483148 DOI: 10.3389/fmolb.2022.933788] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 07/26/2022] [Indexed: 11/25/2022] Open
Abstract
Introduction: Friedreich ataxia (FRDA) is a recessive neurodegenerative disease characterized by progressive ataxia, dyscoordination, and loss of vision. The variable length of the pathogenic GAA triplet repeat expansion in the FXN gene in part explains the interindividual variability in the severity of disease. The GAA repeat expansion leads to epigenetic silencing of FXN; therefore, variability in properties of epigenetic effector proteins could also regulate the severity of FRDA. Methods: In an exploratory analysis, DNA from 88 individuals with FRDA was analyzed to determine if any of five non-synonymous SNPs in HDACs/SIRTs predicted FRDA disease severity. Results suggested the need for a full analysis at the rs352493 locus in SIRT6 (p.Asn46Ser). In a cohort of 569 subjects with FRDA, disease features were compared between subjects homozygous for the common thymine SIRT6 variant (TT) and those with the less common cytosine variant on one allele and thymine on the other (CT). The biochemical properties of both variants of SIRT6 were analyzed and compared. Results: Linear regression in the exploratory cohort suggested that an SNP (rs352493) in SIRT6 correlated with neurological severity in FRDA. The follow-up analysis in a larger cohort agreed with the initial result that the genotype of SIRT6 at the locus rs352493 predicted the severity of disease features of FRDA. Those in the CT SIRT6 group performed better on measures of neurological and visual function over time than those in the more common TT SIRT6 group. The Asn to Ser amino acid change resulting from the SNP in SIRT6 did not alter the expression or enzymatic activity of SIRT6 or frataxin, but iPSC-derived neurons from people with FRDA in the CT SIRT6 group showed whole transcriptome differences compared to those in the TT SIRT6 group. Conclusion: People with FRDA in the CT SIRT6 group have less severe neurological and visual dysfunction than those in the TT SIRT6 group. Biochemical analyses indicate that the benefit conferred by T to C SNP in SIRT6 does not come from altered expression or enzymatic activity of SIRT6 or frataxin but is associated with changes in the transcriptome.
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Affiliation(s)
- Layne N. Rodden
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | | | - Yi Na Dong
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Sarah Lagedrost
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Sean Regner
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Alicia Brocht
- University of Rochester, Rochester, NY, United States
| | | | - Martin B. Delatycki
- Murdoch Children’s Research Institute, Victorian Clinical Genetics Services, Melbourne, VIC, Australia
| | | | - Katherine Mathews
- Departments of Pediatrics and Neurology, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Sarah Murray
- Department of Pathology, School of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Susan Perlman
- Department of Neurology, University of California, Los Angeles, Los Angeles, CA, United States
| | | | - S. H. Subramony
- Department of Neurology, University of Florida, College of Medicine, Gainesville, FL, United States
| | - George Wilmot
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, United States
| | - Theresa Zesiewicz
- Department of Neurology, University of South Florida, Tampa, FL, United States
| | | | - Alain Domissy
- The Scripps Research Institute, La Jolla, CA, United States
| | | | - Baohu Ji
- The Scripps Research Institute, La Jolla, CA, United States
| | | | | | - David R. Lynch
- Departments of Pediatrics and Neurology, Children’s Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- *Correspondence: David R. Lynch,
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Heidorn-Czarna M, Maziak A, Janska H. Protein Processing in Plant Mitochondria Compared to Yeast and Mammals. FRONTIERS IN PLANT SCIENCE 2022; 13:824080. [PMID: 35185991 PMCID: PMC8847149 DOI: 10.3389/fpls.2022.824080] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 01/12/2022] [Indexed: 05/02/2023]
Abstract
Limited proteolysis, called protein processing, is an essential post-translational mechanism that controls protein localization, activity, and in consequence, function. This process is prevalent for mitochondrial proteins, mainly synthesized as precursor proteins with N-terminal sequences (presequences) that act as targeting signals and are removed upon import into the organelle. Mitochondria have a distinct and highly conserved proteolytic system that includes proteases with sole function in presequence processing and proteases, which show diverse mitochondrial functions with limited proteolysis as an additional one. In virtually all mitochondria, the primary processing of N-terminal signals is catalyzed by the well-characterized mitochondrial processing peptidase (MPP). Subsequently, a second proteolytic cleavage occurs, leading to more stabilized residues at the newly formed N-terminus. Lately, mitochondrial proteases, intermediate cleavage peptidase 55 (ICP55) and octapeptidyl protease 1 (OCT1), involved in proteolytic cleavage after MPP and their substrates have been described in the plant, yeast, and mammalian mitochondria. Mitochondrial proteins can also be processed by removing a peptide from their N- or C-terminus as a maturation step during insertion into the membrane or as a regulatory mechanism in maintaining their function. This type of limited proteolysis is characteristic for processing proteases, such as IMP and rhomboid proteases, or the general mitochondrial quality control proteases ATP23, m-AAA, i-AAA, and OMA1. Identification of processing protease substrates and defining their consensus cleavage motifs is now possible with the help of large-scale quantitative mass spectrometry-based N-terminomics, such as combined fractional diagonal chromatography (COFRADIC), charge-based fractional diagonal chromatography (ChaFRADIC), or terminal amine isotopic labeling of substrates (TAILS). This review summarizes the current knowledge on the characterization of mitochondrial processing peptidases and selected N-terminomics techniques used to uncover protease substrates in the plant, yeast, and mammalian mitochondria.
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Benincá C, Zanette V, Brischigliaro M, Johnson M, Reyes A, Valle DAD, J Robinson A, Degiorgi A, Yeates A, Telles BA, Prudent J, Baruffini E, S F Santos ML, R de Souza RL, Fernandez-Vizarra E, Whitworth AJ, Zeviani M. Mutation in the MICOS subunit gene APOO (MIC26) associated with an X-linked recessive mitochondrial myopathy, lactic acidosis, cognitive impairment and autistic features. J Med Genet 2021; 58:155-167. [PMID: 32439808 PMCID: PMC7116790 DOI: 10.1136/jmedgenet-2020-106861] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/13/2020] [Accepted: 04/12/2020] [Indexed: 02/02/2023]
Abstract
BACKGROUND Mitochondria provide ATP through the process of oxidative phosphorylation, physically located in the inner mitochondrial membrane (IMM). The mitochondrial contact site and organising system (MICOS) complex is known as the 'mitoskeleton' due to its role in maintaining IMM architecture. APOO encodes MIC26, a component of MICOS, whose exact function in its maintenance or assembly has still not been completely elucidated. METHODS We have studied a family in which the most affected subject presented progressive developmental delay, lactic acidosis, muscle weakness, hypotonia, weight loss, gastrointestinal and body temperature dysautonomia, repetitive infections, cognitive impairment and autistic behaviour. Other family members showed variable phenotype presentation. Whole exome sequencing was used to screen for pathological variants. Patient-derived skin fibroblasts were used to confirm the pathogenicity of the variant found in APOO. Knockout models in Drosophila melanogaster and Saccharomyces cerevisiae were employed to validate MIC26 involvement in MICOS assembly and mitochondrial function. RESULTS A likely pathogenic c.350T>C transition was found in APOO predicting an I117T substitution in MIC26. The mutation caused impaired processing of the protein during import and faulty insertion into the IMM. This was associated with altered MICOS assembly and cristae junction disruption. The corresponding mutation in MIC26 or complete loss was associated with mitochondrial structural and functional deficiencies in yeast and D. melanogaster models. CONCLUSION This is the first case of pathogenic mutation in APOO, causing altered MICOS assembly and neuromuscular impairment. MIC26 is involved in the assembly or stability of MICOS in humans, yeast and flies.
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Affiliation(s)
- Cristiane Benincá
- Medical Research Council, Mitochondrial Biology Unit, Cambridge, Cambridgeshire, UK
- Department of Genetics, Federal University of Parana, Curitiba, Paraná, Brazil
| | - Vanessa Zanette
- Department of Genetics, Federal University of Parana, Curitiba, Paraná, Brazil
| | | | - Mark Johnson
- Medical Research Council, Mitochondrial Biology Unit, Cambridge, Cambridgeshire, UK
| | - Aurelio Reyes
- Medical Research Council, Mitochondrial Biology Unit, Cambridge, Cambridgeshire, UK
| | | | - Alan J Robinson
- Medical Research Council, Mitochondrial Biology Unit, Cambridge, Cambridgeshire, UK
| | - Andrea Degiorgi
- Department of Chemistry, University of Parma, Parma, Emilia-Romagna, Italy
| | - Anna Yeates
- Medical Research Council, Laboratory of Molecular Biology, Cambridge, Cambridgeshire, UK
| | | | - Julien Prudent
- Medical Research Council, Mitochondrial Biology Unit, Cambridge, Cambridgeshire, UK
| | - Enrico Baruffini
- Department of Chemistry, University of Parma, Parma, Emilia-Romagna, Italy
| | | | | | | | | | - Massimo Zeviani
- Medical Research Council, Mitochondrial Biology Unit, Cambridge, Cambridgeshire, UK
- Department of Neurosciences, University of Padova, Padova, Veneto, Italy
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5
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Gomez-Fabra Gala M, Vögtle FN. Mitochondrial proteases in human diseases. FEBS Lett 2021; 595:1205-1222. [PMID: 33453058 DOI: 10.1002/1873-3468.14039] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 12/15/2022]
Abstract
Mitochondria contain more than 1000 different proteins, including several proteolytic enzymes. These mitochondrial proteases form a complex system that performs limited and terminal proteolysis to build the mitochondrial proteome, maintain, and control its functions or degrade mitochondrial proteins and peptides. During protein biogenesis, presequence proteases cleave and degrade mitochondrial targeting signals to obtain mature functional proteins. Processing by proteases also exerts a regulatory role in modulation of mitochondrial functions and quality control enzymes degrade misfolded, aged, or superfluous proteins. Depending on their different functions and substrates, defects in mitochondrial proteases can affect the majority of the mitochondrial proteome or only a single protein. Consequently, mutations in mitochondrial proteases have been linked to several human diseases. This review gives an overview of the components and functions of the mitochondrial proteolytic machinery and highlights the pathological consequences of dysfunctional mitochondrial protein processing and turnover.
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Affiliation(s)
- Maria Gomez-Fabra Gala
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Germany.,Faculty of Biology, University of Freiburg, Germany.,Spemann Graduate School of Biology and Medicine, University of Freiburg, Germany
| | - Friederike-Nora Vögtle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Germany.,CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Germany
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6
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Kücükköse C, Taskin AA, Marada A, Brummer T, Dennerlein S, Vögtle FN. Functional coupling of presequence processing and degradation in human mitochondria. FEBS J 2021; 288:600-613. [PMID: 32491259 DOI: 10.1111/febs.15358] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 03/31/2020] [Accepted: 05/04/2020] [Indexed: 12/31/2022]
Abstract
The mitochondrial proteome is built and maintained mainly by import of nuclear-encoded precursor proteins. Most of these precursors use N-terminal presequences as targeting signals that are removed by mitochondrial matrix proteases. The essential mitochondrial processing protease MPP cleaves presequences after import into the organelle thereby enabling protein folding and functionality. The cleaved presequences are subsequently degraded by peptidases. While most of these processes have been discovered in yeast, characterization of the human enzymes is still scarce. As the matrix presequence peptidase PreP has been reported to play a role in Alzheimer's disease, analysis of impaired peptide turnover in human cells is of huge interest. Here, we report the characterization of HEK293T PreP knockout cells. Loss of PreP causes severe defects in oxidative phosphorylation and changes in nuclear expression of stress response marker genes. The mitochondrial defects upon lack of PreP result from the accumulation of presequence peptides that trigger feedback inhibition of MPP and accumulation of nonprocessed precursor proteins. Also, the mitochondrial intermediate peptidase MIP that cleaves eight residues from a subset of precursors after MPP processing is compromised upon loss of PreP suggesting that PreP also degrades MIP generated octapeptides. Investigation of the PrePR183Q patient mutation associated with neurological disorders revealed that the mutation destabilizes the protein making it susceptible to enhanced degradation and aggregation upon heat shock. Taken together, our data reveal a functional coupling between precursor processing by MPP and MIP and presequence degradation by PreP in human mitochondria that is crucial to maintain a functional organellar proteome.
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Affiliation(s)
- Cansu Kücükköse
- Faculty of Medicine, Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, Germany
- Faculty of Biology, University of Freiburg, Germany
| | - Asli Aras Taskin
- Faculty of Medicine, Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, Germany
- CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg, Germany
| | - Adinarayana Marada
- Faculty of Medicine, Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, Germany
| | - Tilman Brummer
- Faculty of Medicine, Institute of Molecular Medicine and Cell Research, University of Freiburg, Germany
- Centre for Biological Signalling Studies BIOSS, University of Freiburg, Germany
- Comprehensive Cancer Centre Freiburg, University of Freiburg, Germany
- DKTK Partner Site Freiburg and DKFZ, Heidelberg, Germany
| | - Sven Dennerlein
- Department of Cellular Biochemistry, University Medical Center Göttingen, Germany
| | - Friederike-Nora Vögtle
- Faculty of Medicine, Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, Germany
- CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg, Germany
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7
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Fil D, Chacko BK, Conley R, Ouyang X, Zhang J, Darley-Usmar VM, Zuberi AR, Lutz CM, Napierala M, Napierala JS. Mitochondrial damage and senescence phenotype of cells derived from a novel frataxin G127V point mutation mouse model of Friedreich's ataxia. Dis Model Mech 2020; 13:dmm045229. [PMID: 32586831 PMCID: PMC7406325 DOI: 10.1242/dmm.045229] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/16/2020] [Indexed: 12/11/2022] Open
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused by reduced expression of the mitochondrial protein frataxin (FXN). Most FRDA patients are homozygous for large expansions of GAA repeat sequences in intron 1 of FXN, whereas a fraction of patients are compound heterozygotes, with a missense or nonsense mutation in one FXN allele and expanded GAAs in the other. A prevalent missense mutation among FRDA patients changes a glycine at position 130 to valine (G130V). Herein, we report generation of the first mouse model harboring an Fxn point mutation. Changing the evolutionarily conserved glycine 127 in mouse Fxn to valine results in a failure-to-thrive phenotype in homozygous animals and a substantially reduced number of offspring. Like G130V in FRDA, the G127V mutation results in a dramatic decrease of Fxn protein without affecting transcript synthesis or splicing. FxnG127V mouse embryonic fibroblasts exhibit significantly reduced proliferation and increased cell senescence. These defects are evident in early passage cells and are exacerbated at later passages. Furthermore, increased frequency of mitochondrial DNA lesions and fragmentation are accompanied by marked amplification of mitochondrial DNA in FxnG127V cells. Bioenergetics analyses demonstrate higher sensitivity and reduced cellular respiration of FxnG127V cells upon alteration of fatty acid availability. Importantly, substitution of FxnWT with FxnG127V is compatible with life, and cellular proliferation defects can be rescued by mitigation of oxidative stress via hypoxia or induction of the NRF2 pathway. We propose FxnG127V cells as a simple and robust model for testing therapeutic approaches for FRDA.
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Affiliation(s)
- Daniel Fil
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
| | - Balu K Chacko
- Department of Pathology, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA
- Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Robbie Conley
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
| | - Xiaosen Ouyang
- Department of Pathology, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA
- Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Department of Veteran Affairs Medical Center, Birmingham, AL 35294, USA
| | - Jianhua Zhang
- Department of Pathology, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA
- Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Department of Veteran Affairs Medical Center, Birmingham, AL 35294, USA
| | - Victor M Darley-Usmar
- Department of Pathology, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA
- Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Aamir R Zuberi
- The Rare and Orphan Disease Center, JAX Center for Precision Genetics, 600 Main Street, Bar Harbor, ME 04609, USA
| | - Cathleen M Lutz
- The Rare and Orphan Disease Center, JAX Center for Precision Genetics, 600 Main Street, Bar Harbor, ME 04609, USA
| | - Marek Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
| | - Jill S Napierala
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham, AL 35294, USA
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Stepanova A, Magrané J. Mitochondrial dysfunction in neurons in Friedreich's ataxia. Mol Cell Neurosci 2020; 102:103419. [PMID: 31770591 DOI: 10.1016/j.mcn.2019.103419] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 11/05/2019] [Accepted: 11/08/2019] [Indexed: 12/20/2022] Open
Abstract
Friedreich's ataxia is a multisystemic genetic disorder within the family of mitochondrial diseases that is characterized by reduced levels of the essential mitochondrial protein frataxin. Based on clinical evidence, the peripheral nervous system is affected early, neuronal dysfunction progresses towards the central nervous system, and other organs (such as heart and pancreas) are affected later. However, little attention has been given to the specific aspects of mitochondria function altered by frataxin depletion in the nervous system. For years, commonly accepted views on mitochondria dysfunction in Friedreich's ataxia stemmed from studies using non-neuronal systems and may not apply to neurons, which have their own bioenergetic needs and present a unique, extensive neurite network. Moreover, the basis of the selective neuronal vulnerability, which primarily affects large sensory neurons in the dorsal root ganglia, large principal neurons in the dentate nuclei of the cerebellum, and pyramidal neurons in the cerebral cortex, remains elusive. In order to identify potential misbeliefs in the field and highlight controversies, we reviewed current knowledge on frataxin expression in different tissues, discussed the molecular function of frataxin, and the consequences of its deficiency for mitochondria structural and functional properties, with a focus on the nervous system.
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Affiliation(s)
- Anna Stepanova
- Department of Pediatrics, Columbia University Medical Center, New York, NY, United States of America.
| | - Jordi Magrané
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, United States of America.
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Currier RB, Ulrich K, Leroux AE, Dirdjaja N, Deambrosi M, Bonilla M, Ahmed YL, Adrian L, Antelmann H, Jakob U, Comini MA, Krauth-Siegel RL. An essential thioredoxin-type protein of Trypanosoma brucei acts as redox-regulated mitochondrial chaperone. PLoS Pathog 2019; 15:e1008065. [PMID: 31557263 PMCID: PMC6783113 DOI: 10.1371/journal.ppat.1008065] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 10/08/2019] [Accepted: 09/02/2019] [Indexed: 12/22/2022] Open
Abstract
Most known thioredoxin-type proteins (Trx) participate in redox pathways, using two highly conserved cysteine residues to catalyze thiol-disulfide exchange reactions. Here we demonstrate that the so far unexplored Trx2 from African trypanosomes (Trypanosoma brucei) lacks protein disulfide reductase activity but functions as an effective temperature-activated and redox-regulated chaperone. Immunofluorescence microscopy and fractionated cell lysis revealed that Trx2 is located in the mitochondrion of the parasite. RNA-interference and gene knock-out approaches showed that depletion of Trx2 impairs growth of both mammalian bloodstream and insect stage procyclic parasites. Procyclic cells lacking Trx2 stop proliferation under standard culture conditions at 27°C and are unable to survive prolonged exposure to 37°C, indicating that Trx2 plays a vital role that becomes augmented under heat stress. Moreover, we found that Trx2 contributes to the in vivo infectivity of T. brucei. Remarkably, a Trx2 version, in which all five cysteines were replaced by serine residues, complements for the wildtype protein in conditional knock-out cells and confers parasite infectivity in the mouse model. Characterization of the recombinant protein revealed that Trx2 can coordinate an iron sulfur cluster and is highly sensitive towards spontaneous oxidation. Moreover, we discovered that both wildtype and mutant Trx2 protect other proteins against thermal aggregation and preserve their ability to refold upon return to non-stress conditions. Activation of the chaperone function of Trx2 appears to be triggered by temperature-mediated structural changes and inhibited by oxidative disulfide bond formation. Our studies indicate that Trx2 acts as a novel chaperone in the unique single mitochondrion of T. brucei and reveal a new perspective regarding the physiological function of thioredoxin-type proteins in trypanosomes.
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Affiliation(s)
- Rachel B. Currier
- Biochemie-Zentrum der Universität Heidelberg (BZH), Heidelberg, Germany
| | - Kathrin Ulrich
- Biochemie-Zentrum der Universität Heidelberg (BZH), Heidelberg, Germany
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | | | - Natalie Dirdjaja
- Biochemie-Zentrum der Universität Heidelberg (BZH), Heidelberg, Germany
| | - Matías Deambrosi
- Group Redox Biology of Trypanosomes, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Mariana Bonilla
- Group Redox Biology of Trypanosomes, Institut Pasteur de Montevideo, Montevideo, Uruguay
- Laboratorio de Fisicoquímica Biológica, Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | | | - Lorenz Adrian
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research–UFZ, Leipzig, Germany
- Fachgebiet Geobiotechnologie, Technische Universität Berlin, Berlin, Germany
| | - Haike Antelmann
- Institut für Biologie-Mikrobiologie, Freie Universität Berlin, Berlin, Germany
| | - Ursula Jakob
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Marcelo A. Comini
- Group Redox Biology of Trypanosomes, Institut Pasteur de Montevideo, Montevideo, Uruguay
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10
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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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11
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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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12
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Ciofi-Baffoni S, Nasta V, Banci L. Protein networks in the maturation of human iron-sulfur proteins. Metallomics 2019; 10:49-72. [PMID: 29219157 DOI: 10.1039/c7mt00269f] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The biogenesis of iron-sulfur (Fe-S) proteins in humans is a multistage process occurring in different cellular compartments. The mitochondrial iron-sulfur cluster (ISC) assembly machinery composed of at least 17 proteins assembles mitochondrial Fe-S proteins. A cytosolic iron-sulfur assembly (CIA) machinery composed of at least 13 proteins has been more recently identified and shown to be responsible for the Fe-S cluster incorporation into cytosolic and nuclear Fe-S proteins. Cytosolic and nuclear Fe-S protein maturation requires not only the CIA machinery, but also the components of the mitochondrial ISC assembly machinery. An ISC export machinery, composed of a protein transporter located in the mitochondrial inner membrane, has been proposed to act in mediating the export process of a still unknown component that is required for the CIA machinery. Several functional and molecular aspects of the protein networks operative in the three machineries are still largely obscure. This Review focuses on the Fe-S protein maturation processes in humans with the specific aim of providing a molecular picture of the currently known protein-protein interaction networks. The human ISC and CIA machineries are presented, and the ISC export machinery is discussed with respect to possible molecules being the substrates of the mitochondrial protein transporter.
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Affiliation(s)
- Simone Ciofi-Baffoni
- Magnetic Resonance Center-CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy.
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13
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Castro IH, Pignataro MF, Sewell KE, Espeche LD, Herrera MG, Noguera ME, Dain L, Nadra AD, Aran M, Smal C, Gallo M, Santos J. Frataxin Structure and Function. Subcell Biochem 2019; 93:393-438. [PMID: 31939159 DOI: 10.1007/978-3-030-28151-9_13] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mammalian frataxin is a small mitochondrial protein involved in iron sulfur cluster assembly. Frataxin deficiency causes the neurodegenerative disease Friedreich's Ataxia. Valuable knowledge has been gained on the structural dynamics of frataxin, metal-ion-protein interactions, as well as on the effect of mutations on protein conformation, stability and internal motions. Additionally, laborious studies concerning the enzymatic reactions involved have allowed for understanding the capability of frataxin to modulate Fe-S cluster assembly function. Remarkably, frataxin biological function depends on its interaction with some proteins to form a supercomplex, among them NFS1 desulfurase and ISCU, the scaffolding protein. By combining multiple experimental tools including high resolution techniques like NMR and X-ray, but also SAXS, crosslinking and mass-spectrometry, it was possible to build a reliable model of the structure of the desulfurase supercomplex NFS1/ACP-ISD11/ISCU/frataxin. In this chapter, we explore these issues showing how the scientific view concerning frataxin structure-function relationships has evolved over the last years.
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Affiliation(s)
- Ignacio Hugo Castro
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, 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
| | - María Florencia Pignataro
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, 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
| | - Karl Ellioth Sewell
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, 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
| | - Lucía Daniela Espeche
- Departamento de Diagnóstico Genético, Centro Nacional de Genética Médica "Dr. Eduardo E. Castilla"-A.N.L.I.S, Av. Las Heras 2670, C1425ASQ, C.A.B.A, Argentina
| | - María Georgina Herrera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
| | - Martín Ezequiel Noguera
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, 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
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, B1876BXD, Bernal, Provincia de Buenos Aires, Argentina
| | - Liliana Dain
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Departamento de Diagnóstico Genético, Centro Nacional de Genética Médica "Dr. Eduardo E. Castilla"-A.N.L.I.S, Av. Las Heras 2670, C1425ASQ, C.A.B.A, Argentina
| | - Alejandro Daniel Nadra
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160-Ciudad Universitaria, 1428EGA, C.A.B.A, Argentina
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Martín Aran
- Fundación Instituto Leloir E IIBBA-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
| | - Clara Smal
- Fundación Instituto Leloir E IIBBA-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
| | - Mariana Gallo
- IRBM Science Park S.p.A, Via Pontina km 30,600, 00071, Pomezia, RM, Italy
| | - Javier Santos
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biomedicina (iB3), Universidad de Buenos Aires, 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.
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14
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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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15
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Alsina D, Purroy R, Ros J, Tamarit J. Iron in Friedreich Ataxia: A Central Role in the Pathophysiology or an Epiphenomenon? Pharmaceuticals (Basel) 2018; 11:E89. [PMID: 30235822 PMCID: PMC6161073 DOI: 10.3390/ph11030089] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 09/15/2018] [Accepted: 09/17/2018] [Indexed: 12/16/2022] Open
Abstract
Friedreich ataxia is a neurodegenerative disease with an autosomal recessive inheritance. In most patients, the disease is caused by the presence of trinucleotide GAA expansions in the first intron of the frataxin gene. These expansions cause the decreased expression of this mitochondrial protein. Many evidences indicate that frataxin deficiency causes the deregulation of cellular iron homeostasis. In this review, we will discuss several hypotheses proposed for frataxin function, their caveats, and how they could provide an explanation for the deregulation of iron homeostasis found in frataxin-deficient cells. We will also focus on the potential mechanisms causing cellular dysfunction in Friedreich Ataxia and on the potential use of the iron chelator deferiprone as a therapeutic agent for this disease.
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Affiliation(s)
- David Alsina
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, 25198 Lleida, Spain.
| | - Rosa Purroy
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, 25198 Lleida, Spain.
| | - Joaquim Ros
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, 25198 Lleida, Spain.
| | - Jordi Tamarit
- Departament de Ciències Mèdiques Bàsiques, IRBLleida, Universitat de Lleida, 25198 Lleida, Spain.
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16
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Vögtle FN, Brändl B, Larson A, Pendziwiat M, Friederich MW, White SM, Basinger A, Kücükköse C, Muhle H, Jähn JA, Keminer O, Helbig KL, Delto CF, Myketin L, Mossmann D, Burger N, Miyake N, Burnett A, van Baalen A, Lovell MA, Matsumoto N, Walsh M, Yu HC, Shinde DN, Stephani U, Van Hove JLK, Müller FJ, Helbig I. Mutations in PMPCB Encoding the Catalytic Subunit of the Mitochondrial Presequence Protease Cause Neurodegeneration in Early Childhood. Am J Hum Genet 2018; 102:557-573. [PMID: 29576218 PMCID: PMC5985287 DOI: 10.1016/j.ajhg.2018.02.014] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 02/19/2018] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial disorders causing neurodegeneration in childhood are genetically heterogeneous, and the underlying genetic etiology remains unknown in many affected individuals. We identified biallelic variants in PMPCB in individuals of four families including one family with two affected siblings with neurodegeneration and cerebellar atrophy. PMPCB encodes the catalytic subunit of the essential mitochondrial processing protease (MPP), which is required for maturation of the majority of mitochondrial precursor proteins. Mitochondria isolated from two fibroblast cell lines and induced pluripotent stem cells derived from one affected individual and differentiated neuroepithelial stem cells showed reduced PMPCB levels and accumulation of the processing intermediate of frataxin, a sensitive substrate for MPP dysfunction. Introduction of the identified PMPCB variants into the homologous S. cerevisiae Mas1 protein resulted in a severe growth and MPP processing defect leading to the accumulation of mitochondrial precursor proteins and early impairment of the biogenesis of iron-sulfur clusters, which are indispensable for a broad range of crucial cellular functions. Analysis of biopsy materials of an affected individual revealed changes and decreased activity in iron-sulfur cluster-containing respiratory chain complexes and dysfunction of mitochondrial and cytosolic Fe-S cluster-dependent enzymes. We conclude that biallelic mutations in PMPCB cause defects in MPP proteolytic activity leading to dysregulation of iron-sulfur cluster biogenesis and triggering a complex neurological phenotype of neurodegeneration in early childhood.
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Affiliation(s)
- F-Nora Vögtle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany.
| | - Björn Brändl
- Department of Psychiatry and Psychotherapy, University Hospital Schleswig Holstein, Kiel 24105, Germany
| | - Austin Larson
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, CO 80045, USA
| | - Manuela Pendziwiat
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany
| | - Marisa W Friederich
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, CO 80045, USA
| | - Susan M White
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, VIC 3052, Australia; Department of Paediatrics, University of Melbourne, Melbourne, VIC 3052, Australia
| | - Alice Basinger
- Cook Children's Physician Network, Department of Genetics, Fort Worth, TX 76102, USA
| | - Cansu Kücükköse
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany; Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Hiltrud Muhle
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany
| | - Johanna A Jähn
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany
| | - Oliver Keminer
- Fraunhofer-Institut für Molekularbiologie und Angewandte Ökologie IME, ScreeningPort, Hamburg 22525, Germany
| | - Katherine L Helbig
- Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Carolyn F Delto
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg 97080, Germany
| | - Lisa Myketin
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany
| | - Dirk Mossmann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany
| | - Nils Burger
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany
| | - Noriko Miyake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan
| | - Audrey Burnett
- Cook Children's Physician Network, Department of Genetics, Fort Worth, TX 76102, USA
| | - Andreas van Baalen
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany
| | - Mark A Lovell
- Department of Pathology, University of Colorado, Aurora, CO 80045, USA
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan
| | - Maie Walsh
- Adult Genetic Medicine, Royal Melbourne Hospital, Melbourne, VIC 3052, Australia
| | - Hung-Chun Yu
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, CO 80045, USA
| | - Deepali N Shinde
- Division of Clinical Genomics, Ambry Genetics, Aliso Viejo, CA 92656, USA
| | - Ulrich Stephani
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany
| | - Johan L K Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, CO 80045, USA
| | - Franz-Josef Müller
- Department of Psychiatry and Psychotherapy, University Hospital Schleswig Holstein, Kiel 24105, Germany; Max Planck Institute for Molecular Genetics, Berlin 14195, Germany
| | - Ingo Helbig
- Department of Neuropediatrics, Christian-Albrechts-University of Kiel, Kiel 24105, Germany; Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
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17
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Britti E, Delaspre F, Feldman A, Osborne M, Greif H, Tamarit J, Ros J. Frataxin-deficient neurons and mice models of Friedreich ataxia are improved by TAT-MTScs-FXN treatment. J Cell Mol Med 2018; 22:834-848. [PMID: 28980774 PMCID: PMC5783845 DOI: 10.1111/jcmm.13365] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 07/28/2017] [Indexed: 01/02/2023] Open
Abstract
Friedreich ataxia (FA) is a rare disease caused by deficiency of frataxin, a mitochondrial protein. As there is no cure available for this disease, many strategies have been developed to reduce the deleterious effects of such deficiency. One of these approaches is based on delivering frataxin to the tissues by coupling the protein to trans-activator of transcription (TAT) peptides, which enables cell membranes crossing. In this study, we tested the efficiency of TAT-MTScs-FXN fusion protein to decrease neurodegeneration markers on frataxin-depleted neurons obtained from dorsal root ganglia (DRG), one of the most affected tissues. In mice models of the disease, we tested the ability of TAT-MTScs-FXN to penetrate the mitochondria and its effect on lifespan. In DRG neurons, treatment with TAT-MTScs-FXN increased cell survival, decreased neurite degeneration and reduced apoptotic markers, such as α-fodrin cleavage and caspase 9 activation. Also, we show that heat-shock protein 60 (HSP60), a molecular chaperone targeted to mitochondria, suffered an impaired processing in frataxin-deficient neurons that was relieved by TAT-MTScs-FXN addition. In mice models of the disease, administration of TAT-MTScs-FXN was able to reach muscle mitochondria, restore the activity of the succinate dehydrogenase and produce a significant lifespan increase. These results support the use of TAT-MTScs-FXN as a treatment for Friedreich ataxia.
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Affiliation(s)
- Elena Britti
- Departament de Ciències Mèdiques BàsiquesIRBLleidaUniversitat de LleidaLleidaSpain
| | - Fabien Delaspre
- Departament de Ciències Mèdiques BàsiquesIRBLleidaUniversitat de LleidaLleidaSpain
| | | | | | | | - Jordi Tamarit
- Departament de Ciències Mèdiques BàsiquesIRBLleidaUniversitat de LleidaLleidaSpain
| | - Joaquim Ros
- Departament de Ciències Mèdiques BàsiquesIRBLleidaUniversitat de LleidaLleidaSpain
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18
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Buchensky C, Sánchez M, Carrillo M, Palacios O, Capdevila M, Domínguez-Vera JM, Busi MV, Atrian S, Pagani MA, Gomez-Casati DF. Identification of two frataxin isoforms in Zea mays: Structural and functional studies. Biochimie 2017; 140:34-47. [PMID: 28630009 DOI: 10.1016/j.biochi.2017.06.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 06/15/2017] [Indexed: 11/19/2022]
Abstract
Frataxin is a ubiquitous protein that plays a role in Fe-S cluster biosynthesis and iron and heme metabolism, although its molecular functions are not entirely clear. In non-photosynthetic eukaryotes, frataxin is encoded by a single gene, and the protein localizes to mitochondria. Here we report the presence of two functional frataxin isoforms in Zea mays, ZmFH-1 and ZmFH-2. We confirmed our previous findings regarding plant frataxins: both proteins have dual localization in mitochondria and chloroplasts. Physiological, biochemical and biophysical studies show some differences in the expression pattern, protection against oxidants and in the aggregation state of both isoforms, suggesting that the two frataxin homologs would play similar but not identical roles in plant cell metabolism. In addition, two specific features of plant frataxins were evidenced: their ability to form dimers and their tendency to undergo conformational change under oxygen exposure.
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Affiliation(s)
- Celeste Buchensky
- CEFOBI - CONICET, Centro de Estudios Fotosintéticos y Bioquímicos - Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Manuel Sánchez
- Departamento de Química Inorgánica, Facultad de Ciencias. Instituto de Biotecnología, Universidad de Granada, 18071, Granada, Spain
| | - Martin Carrillo
- CEFOBI - CONICET, Centro de Estudios Fotosintéticos y Bioquímicos - Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Oscar Palacios
- Departament de Química, Facultat de Ciènces, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
| | - Mercè Capdevila
- Departament de Química, Facultat de Ciènces, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Barcelona, Spain
| | - Jose M Domínguez-Vera
- Departamento de Química Inorgánica, Facultad de Ciencias. Instituto de Biotecnología, Universidad de Granada, 18071, Granada, Spain
| | - Maria V Busi
- CEFOBI - CONICET, Centro de Estudios Fotosintéticos y Bioquímicos - Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Sílvia Atrian
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain
| | - Maria A Pagani
- CEFOBI - CONICET, Centro de Estudios Fotosintéticos y Bioquímicos - Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Diego F Gomez-Casati
- CEFOBI - CONICET, Centro de Estudios Fotosintéticos y Bioquímicos - Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina.
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19
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Gakh O, Ranatunga W, Galeano BK, Smith DS, Thompson JR, Isaya G. Defining the Architecture of the Core Machinery for the Assembly of Fe-S Clusters in Human Mitochondria. Methods Enzymol 2017; 595:107-160. [PMID: 28882199 DOI: 10.1016/bs.mie.2017.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Although Fe-S clusters may assemble spontaneously from elemental iron and sulfur in protein-free systems, the potential toxicity of free Fe2+, Fe3+, and S2- ions in aerobic environments underscores the requirement for specialized proteins to oversee the safe assembly of Fe-S clusters in living cells. Prokaryotes first developed multiprotein systems for Fe-S cluster assembly, from which mitochondria later derived their own system and became the main Fe-S cluster suppliers for eukaryotic cells. Early studies in yeast and human mitochondria indicated that Fe-S cluster assembly in eukaryotes is centered around highly conserved Fe-S proteins (human ISCU) that serve as scaffolds upon which new Fe-S clusters are assembled from (i) elemental sulfur, provided by a pyridoxal phosphate-dependent cysteine desulfurase (human NFS1) and its stabilizing-binding partner (human ISD11), and (ii) elemental iron, provided by an iron-binding protein of the frataxin family (human FXN). Further studies revealed that all of these proteins could form stable complexes that could reach molecular masses of megadaltons. However, the protein-protein interaction surfaces, catalytic mechanisms, and overall architecture of these macromolecular machines remained undefined for quite some time. The delay was due to difficulties inherent in reconstituting these very large multiprotein complexes in vitro or isolating them from cells in sufficient quantities to enable biochemical and structural studies. Here, we describe approaches we developed to reconstitute the human Fe-S cluster assembly machinery in Escherichia coli and to define its remarkable architecture.
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Affiliation(s)
| | | | - Belinda K Galeano
- Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN, United States
| | | | | | - Grazia Isaya
- Mayo Clinic, Rochester, MN, United States; Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN, United States; Mayo Clinic Children's Research Center, Rochester, MN, United States.
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20
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Steinkellner H, Singh HN, Muckenthaler MU, Goldenberg H, Moganty RR, Scheiber-Mojdehkar B, Sturm B. No changes in heme synthesis in human Friedreich´s ataxia erythroid progenitor cells. Gene 2017; 621:5-11. [PMID: 28412459 DOI: 10.1016/j.gene.2017.04.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 04/03/2017] [Accepted: 04/04/2017] [Indexed: 12/28/2022]
Abstract
Friedreich's ataxia (FRDA) is a neurodegenerative disease caused by reduced expression of the protein frataxin. Frataxin is thought to play a role in iron-sulfur cluster biogenesis and heme synthesis. In this study, we used erythroid progenitor stem cells obtained from FRDA patients and healthy donors to investigate the putative role, if any, of frataxin deficiency in heme synthesis. We used electrochemiluminescence and qRT-PCR for frataxin protein and mRNA quantification. We used atomic absorption spectrophotometry for iron levels and a photometric assay for hemoglobin levels. Protoporphyrin IX and Ferrochelatase were analyzed using auto-fluorescence. An "IronChip" microarray analysis followed by a protein-protein interaction analysis was performed. FRDA patient cells showed no significant changes in iron levels, hemoglobin synthesis, protoporphyrin IX levels, and ferrochelatase activity. Microarray analysis presented 11 genes that were significantly changed in all patients compared to controls. The genes are especially involved in oxidative stress, iron homeostasis and angiogenesis. The mystery about the involvement of frataxin on iron metabolism raises the question why frataxin deficiency in primary FRDA cells did not lead to changes in biochemical parameters of heme synthesis. It seems that alternative pathways can circumvent the impact of frataxin deficiency on heme synthesis. We show for the first time in primary FRDA patient cells that reduced frataxin levels are still sufficient for heme synthesis and possibly other mechanisms can overcome reduced frataxin levels in this process. Our data strongly support the fact that so far no anemia in FRDA patients was reported.
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Affiliation(s)
- Hannes Steinkellner
- Department of Medical Chemistry and Pathobiochemistry, Medical University of Vienna, Vienna, Austria; Department of Medical Genetics, Medical University of Vienna, Vienna, Austria
| | - Himanshu Narayan Singh
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India
| | | | - Hans Goldenberg
- Department of Medical Chemistry and Pathobiochemistry, Medical University of Vienna, Vienna, Austria
| | - Rajeswari R Moganty
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India
| | | | - Brigitte Sturm
- Department of Medical Chemistry and Pathobiochemistry, Medical University of Vienna, Vienna, Austria.
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21
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Clark E, Butler JS, Isaacs CJ, Napierala M, Lynch DR. Selected missense mutations impair frataxin processing in Friedreich ataxia. Ann Clin Transl Neurol 2017; 4:575-584. [PMID: 28812047 PMCID: PMC5553228 DOI: 10.1002/acn3.433] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/23/2017] [Accepted: 05/24/2017] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVE Frataxin (FXN) is a highly conserved mitochondrial protein. Reduced FXN levels cause Friedreich ataxia, a recessive neurodegenerative disease. Typical patients carry GAA repeat expansions on both alleles, while a subgroup of patients carry a missense mutation on one allele and a GAA repeat expansion on the other. Here, we report that selected disease-related FXN missense mutations impair FXN localization, interaction with mitochondria processing peptidase, and processing. METHODS Immunocytochemical studies and subcellular fractionation were performed to study FXN import into the mitochondria and examine the mechanism by which mutations impair FXN processing. Coimmunoprecipitation was performed to study the interaction between FXN and mitochondrial processing peptidase. A proteasome inhibitor was used to model traditional therapeutic strategies. In addition, clinical profiles of subjects with and without point mutations were compared in a large natural history study. RESULTS FXNI154F and FXNG130V missense mutations decrease FXN 81-210 levels compared with FXNWT, FXNR165C, and FXNW155R, but do not block its association with mitochondria. FXNI154F and FXNG130V also impair FXN maturation and enhance the binding between FXN 42-210 and mitochondria processing peptidase. Furthermore, blocking proteosomal degradation does not increase FXN 81-210 levels. Additionally, impaired FXN processing also occurs in fibroblasts from patients with FXNG130V. Finally, clinical data from patients with FXNG130V and FXNI154F mutations demonstrates a lower severity compared with other individuals with Friedreich ataxia. INTERPRETATION These data suggest that the effects on processing associated with FXNG130V and FXNI154F mutations lead to higher levels of partially processed FXN, which may contribute to the milder clinical phenotypes in these patients.
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Affiliation(s)
- Elisia Clark
- University of Pennsylvania Philadelphia Pennsylvania.,Children's Hospital of Philadelphia Philadelphia Pennsylvania
| | - Jill S Butler
- University of Alabama at Birmingham Birmingham Alabama
| | | | | | - David R Lynch
- University of Pennsylvania Philadelphia Pennsylvania.,Children's Hospital of Philadelphia Philadelphia Pennsylvania
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22
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Two proteomic methodologies for defining N-termini of mature human mitochondrial aminoacyl-tRNA synthetases. Methods 2017; 113:111-119. [DOI: 10.1016/j.ymeth.2016.10.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 10/21/2016] [Accepted: 10/24/2016] [Indexed: 11/21/2022] Open
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23
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Raja V, Joshi AS, Li G, Maddipati KR, Greenberg ML. Loss of Cardiolipin Leads to Perturbation of Acetyl-CoA Synthesis. J Biol Chem 2016; 292:1092-1102. [PMID: 27941023 DOI: 10.1074/jbc.m116.753624] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 12/08/2016] [Indexed: 11/06/2022] Open
Abstract
Cardiolipin (CL), the signature phospholipid of mitochondrial membranes, plays an important role in mitochondrial processes and bioenergetics. CL is synthesized de novo and undergoes remodeling in the mitochondrial membranes. Perturbation of CL remodeling leads to the rare X-linked genetic disorder Barth syndrome, which shows disparities in clinical presentation. To uncover biochemical modifiers that exacerbate CL deficiency, we carried out a synthetic genetic array screen to identify synthetic lethal interactions with the yeast CL synthase mutant crd1Δ. The results indicated that crd1Δ is synthetically lethal with mutants in pyruvate dehydrogenase (PDH), which catalyzes the conversion of pyruvate to acetyl-CoA. Acetyl-CoA levels were decreased in the mutant. The synthesis of acetyl-CoA depends primarily on the PDH-catalyzed conversion of pyruvate in the mitochondria and on the PDH bypass in the cytosol, which synthesizes acetyl-CoA from acetate. Consistent with perturbation of the PDH bypass, crd1Δ cells grown on acetate as the sole carbon source exhibited decreased growth, decreased acetyl-CoA, and increased intracellular acetate levels resulting from decreased acetyl-CoA synthetase activity. PDH mRNA and protein levels were up-regulated in crd1Δ cells, but PDH enzyme activity was not increased, indicating that PDH up-regulation did not compensate for defects in the PDH bypass. These findings demonstrate for the first time that CL is required for acetyl-CoA synthesis, which is decreased in CL-deficient cells as a result of a defective PDH bypass pathway.
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Affiliation(s)
- Vaishnavi Raja
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and
| | - Amit S Joshi
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and
| | - Guiling Li
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and
| | - Krishna Rao Maddipati
- the Department of Pathology, Bioactive Lipids Research Program, Wayne State University School of Medicine, Karmanos Cancer Institute, Detroit, Michigan 48202
| | - Miriam L Greenberg
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and
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24
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Marcus D, Lichtenstein M, Cohen N, Hadad R, Erlich-Hadad T, Greif H, Lorberboum-Galski H. Heterologous mitochondrial targeting sequences can deliver functional proteins into mitochondria. Int J Biochem Cell Biol 2016; 81:48-56. [PMID: 27771440 DOI: 10.1016/j.biocel.2016.10.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 10/13/2016] [Accepted: 10/18/2016] [Indexed: 01/23/2023]
Abstract
Mitochondrial Targeting Sequences (MTSs) are responsible for trafficking nuclear-encoded proteins into mitochondria. Once entering the mitochondria, the MTS is recognized and cleaved off. Some MTSs are long and undergo two-step processing, as in the case of the human frataxin (FXN) protein (80aa), implicated in Friedreich's ataxia (FA). Therefore, we chose the FXN protein to examine whether nuclear-encoded mitochondrial proteins can efficiently be targeted via a heterologous MTS (hMTS) and deliver a functional protein into mitochondria. We examined three hMTSs; that of citrate synthase (cs), lipoamide deydrogenase (LAD) and C6ORF66 (ORF), as classically MTS sequences, known to be removed by one-step processing, to deliver FXN into mitochondria, in the form of fusion proteins. We demonstrate that using hMTSs for delivering FXN results in the production of 4-5-fold larger amounts of the fusion proteins, and at 4-5-fold higher concentrations. Moreover, hMTSs delivered a functional FXN protein into the mitochondria even more efficiently than the native MTSfxn, as evidenced by the rescue of FA patients' cells from oxidative stress; demonstrating a 18%-54% increase in cell survival; and a 13%-33% increase in ATP levels, as compared to the fusion protein carrying the native MTS. One fusion protein with MTScs increased aconitase activity within patients' cells, by 400-fold. The implications form our studies are of vast importance for both basic and translational research of mitochondrial proteins as any mitochondrial protein can be delivered efficiently by an hMTS. Moreover, effective targeting of functional proteins is important for restoration of mitochondrial function and treatment of related disorders.
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Affiliation(s)
- Dana Marcus
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Michal Lichtenstein
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Natali Cohen
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Rita Hadad
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Tal Erlich-Hadad
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | | | - Haya Lorberboum-Galski
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel.
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25
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Gakh O, Ranatunga W, Smith DY, Ahlgren EC, Al-Karadaghi S, Thompson JR, Isaya G. Architecture of the Human Mitochondrial Iron-Sulfur Cluster Assembly Machinery. J Biol Chem 2016; 291:21296-21321. [PMID: 27519411 PMCID: PMC5076535 DOI: 10.1074/jbc.m116.738542] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 08/10/2016] [Indexed: 11/06/2022] Open
Abstract
Fe-S clusters, essential cofactors needed for the activity of many different enzymes, are assembled by conserved protein machineries inside bacteria and mitochondria. As the architecture of the human machinery remains undefined, we co-expressed in Escherichia coli the following four proteins involved in the initial step of Fe-S cluster synthesis: FXN42-210 (iron donor); [NFS1]·[ISD11] (sulfur donor); and ISCU (scaffold upon which new clusters are assembled). We purified a stable, active complex consisting of all four proteins with 1:1:1:1 stoichiometry. Using negative staining transmission EM and single particle analysis, we obtained a three-dimensional model of the complex with ∼14 Å resolution. Molecular dynamics flexible fitting of protein structures docked into the EM map of the model revealed a [FXN42-210]24·[NFS1]24·[ISD11]24·[ISCU]24 complex, consistent with the measured 1:1:1:1 stoichiometry of its four components. The complex structure fulfills distance constraints obtained from chemical cross-linking of the complex at multiple recurring interfaces, involving hydrogen bonds, salt bridges, or hydrophobic interactions between conserved residues. The complex consists of a central roughly cubic [FXN42-210]24·[ISCU]24 sub-complex with one symmetric ISCU trimer bound on top of one symmetric FXN42-210 trimer at each of its eight vertices. Binding of 12 [NFS1]2·[ISD11]2 sub-complexes to the surface results in a globular macromolecule with a diameter of ∼15 nm and creates 24 Fe-S cluster assembly centers. The organization of each center recapitulates a previously proposed conserved mechanism for sulfur donation from NFS1 to ISCU and reveals, for the first time, a path for iron donation from FXN42-210 to ISCU.
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Affiliation(s)
- Oleksandr Gakh
- From the Departments of Pediatric and Adolescent Medicine and Biochemistry Molecular Biology, Mayo Clinic Children's Research Center, and
| | - Wasantha Ranatunga
- From the Departments of Pediatric and Adolescent Medicine and Biochemistry Molecular Biology, Mayo Clinic Children's Research Center, and
| | - Douglas Y Smith
- From the Departments of Pediatric and Adolescent Medicine and Biochemistry Molecular Biology, Mayo Clinic Children's Research Center, and
| | - Eva-Christina Ahlgren
- the Center for Molecular Protein Science, Institute for Chemistry and Chemical Engineering, Lund University, P. O. Box 124, SE-221 00 Lund, Sweden
| | - Salam Al-Karadaghi
- the Center for Molecular Protein Science, Institute for Chemistry and Chemical Engineering, Lund University, P. O. Box 124, SE-221 00 Lund, Sweden
| | - James R Thompson
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota 55905 and
| | - Grazia Isaya
- From the Departments of Pediatric and Adolescent Medicine and Biochemistry Molecular Biology, Mayo Clinic Children's Research Center, and
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26
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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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27
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Stable isotopes and LC-MS for monitoring metabolic disturbances in Friedreich's ataxia platelets. Bioanalysis 2016; 7:1843-55. [PMID: 26295986 DOI: 10.4155/bio.15.118] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Friedreich's ataxia (FRDA) is an autosomal recessive disease with metabolic abnormalities that have been proposed to play an important role in the resulting neurodegeneration and cardiomyopathy. The inability to access the highly affected neuronal and cardiac tissues has hampered metabolic evaluation and biomarker development. METHODS Employment of a LC-MS-based method to determine whether platelets isolated from patients with FRDA exhibit differentiable metabolism compared with healthy controls. RESULTS Isotopologue analysis showed a marked decrease in glucose incorporation with a concomitant increase in palmitate-derived acyl-CoA thioesters in FRDA platelets compared with controls. CONCLUSION Our findings demonstrate that platelets can be used as a surrogate tissue for in vivo biomarker studies to monitor new therapeutic approaches for the treatment of FRDA.
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28
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Joshi M, Anselm I, Shi J, Bale TA, Towne M, Schmitz-Abe K, Crowley L, Giani FC, Kazerounian S, Markianos K, Lidov HG, Folkerth R, Sankaran VG, Agrawal PB. Mutations in the substrate binding glycine-rich loop of the mitochondrial processing peptidase-α protein (PMPCA) cause a severe mitochondrial disease. Cold Spring Harb Mol Case Stud 2016; 2:a000786. [PMID: 27148589 PMCID: PMC4853520 DOI: 10.1101/mcs.a000786] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We describe a large Lebanese family with two affected members, a young female proband and her male cousin, who had multisystem involvement including profound global developmental delay, severe hypotonia and weakness, respiratory insufficiency, blindness, and lactic acidemia—findings consistent with an underlying mitochondrial disorder. Whole-exome sequencing was performed on DNA from the proband and both parents. The proband and her cousin carried compound heterozygous mutations in the PMPCA gene that encodes for α-mitochondrial processing peptidase (α-MPP), a protein likely involved in the processing of mitochondrial proteins. The variants were located close to and postulated to affect the substrate binding glycine-rich loop of the α-MPP protein. Functional assays including immunofluorescence and western blot analysis on patient's fibroblasts revealed that these variants reduced α-MPP levels and impaired frataxin production and processing. We further determined that those defects could be rescued through the expression of exogenous wild-type PMPCA cDNA. Our findings link defective α-MPP protein to a severe mitochondrial disease.
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Affiliation(s)
- Mugdha Joshi
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA;; Division of Newborn Medicine, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA;; Gene Discovery Core, Manton Center for Orphan Disease Research, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Irina Anselm
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Jiahai Shi
- Whitehead Institute for Biomedical Research, MIT, Cambridge, Massachusetts 02142, USA;; Department of Biomedical Sciences, City University of Hong Kong, Hong Kong SAR, China
| | - Tejus A Bale
- Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Meghan Towne
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA;; Gene Discovery Core, Manton Center for Orphan Disease Research, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Klaus Schmitz-Abe
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Laura Crowley
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA;; Gene Discovery Core, Manton Center for Orphan Disease Research, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Felix C Giani
- Division of Hematology/Oncology, Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, Massachusetts 02115, USA;; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Shideh Kazerounian
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Kyriacos Markianos
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Hart G Lidov
- Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Rebecca Folkerth
- Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Vijay G Sankaran
- Division of Hematology/Oncology, Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, Massachusetts 02115, USA;; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Pankaj B Agrawal
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA;; Division of Newborn Medicine, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA;; Gene Discovery Core, Manton Center for Orphan Disease Research, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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29
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Choquet K, Zurita-Rendón O, La Piana R, Yang S, Dicaire MJ, Boycott KM, Majewski J, Shoubridge EA, Brais B, Tétreault M. Autosomal recessive cerebellar ataxia caused by a homozygous mutation in PMPCA. Brain 2016; 139:e19. [PMID: 26657514 DOI: 10.1093/brain/awv362] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 10/26/2015] [Indexed: 12/16/2023] Open
Affiliation(s)
- Karine Choquet
- 1 Montreal Neurological Institute, McGill University, Montreal, Québec, Canada 2 Department of Human Genetics, McGill University, Montreal, Québec, Canada
| | - Olga Zurita-Rendón
- 1 Montreal Neurological Institute, McGill University, Montreal, Québec, Canada
| | - Roberta La Piana
- 1 Montreal Neurological Institute, McGill University, Montreal, Québec, Canada
| | - Sharon Yang
- 1 Montreal Neurological Institute, McGill University, Montreal, Québec, Canada
| | - Marie-Josée Dicaire
- 1 Montreal Neurological Institute, McGill University, Montreal, Québec, Canada
| | - Kym M Boycott
- 3 Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Jacek Majewski
- 2 Department of Human Genetics, McGill University, Montreal, Québec, Canada 4 McGill University and Genome Quebec Innovation Centre, Montreal, Québec, Canada
| | - Eric A Shoubridge
- 1 Montreal Neurological Institute, McGill University, Montreal, Québec, Canada 2 Department of Human Genetics, McGill University, Montreal, Québec, Canada
| | - Bernard Brais
- 1 Montreal Neurological Institute, McGill University, Montreal, Québec, Canada 2 Department of Human Genetics, McGill University, Montreal, Québec, Canada
| | - Martine Tétreault
- 2 Department of Human Genetics, McGill University, Montreal, Québec, Canada 4 McGill University and Genome Quebec Innovation Centre, Montreal, Québec, Canada
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30
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Galea CA, Huq A, Lockhart PJ, Tai G, Corben LA, Yiu EM, Gurrin LC, Lynch DR, Gelbard S, Durr A, Pousset F, Parkinson M, Labrum R, Giunti P, Perlman SL, Delatycki MB, Evans-Galea MV. Compound heterozygous FXN mutations and clinical outcome in friedreich ataxia. Ann Neurol 2016; 79:485-95. [PMID: 26704351 DOI: 10.1002/ana.24595] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 02/01/2023]
Abstract
OBJECTIVE Friedreich ataxia (FRDA) is an inherited neurodegenerative disease characterized by ataxia and cardiomyopathy. Homozygous GAA trinucleotide repeat expansions in the first intron of FXN occur in 96% of affected individuals and reduce frataxin expression. Remaining individuals are compound heterozygous for a GAA expansion and a FXN point/insertion/deletion mutation. We examined disease-causing mutations and the impact on frataxin structure/function and clinical outcome in FRDA. METHODS We compared clinical information from 111 compound heterozygotes and 131 individuals with homozygous expansions. Frataxin mutations were examined using structural modeling, stability analyses and systematic literature review, and categorized into four groups: (1) homozygous expansions, and three compound heterozygote groups; (2) null (no frataxin produced); (3) moderate/strong impact; and (4) minimal impact. Mean age of onset and the presence of cardiomyopathy and diabetes mellitus were compared using regression analyses. RESULTS Mutations in the hydrophobic core of frataxin affected stability whereas surface residue mutations affected interactions with iron sulfur cluster assembly and heme biosynthetic proteins. The null group of compound heterozygotes had significantly earlier age of onset and increased diabetes mellitus, compared to the homozygous expansion group. There were no significant differences in mean age of onset between homozygotes and the minimal and moderate/strong impact groups. INTERPRETATION In compound heterozygotes, expression of partially functional mutant frataxin delays age of onset and reduces diabetes mellitus, compared to those with no frataxin expression from the non-expanded allele. This integrated analysis of categorized frataxin mutations and their correlation with clinical outcome provide a definitive resource for investigating disease pathogenesis in FRDA.
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Affiliation(s)
- Charles A Galea
- Medicinal Chemistry and Drug Delivery, Disposition and Dynamics (D4), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Aamira Huq
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Paul J Lockhart
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Geneieve Tai
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Louise A Corben
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- School of Psychological Sciences, Monash University, Clayton, Victoria, Australia
| | - Eppie M Yiu
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Neurology, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Lyle C Gurrin
- Center for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - David R Lynch
- Departments of Neurology and Pediatrics, University of Pennsylvania School of Medicine and The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Sarah Gelbard
- Departments of Neurology and Pediatrics, University of Pennsylvania School of Medicine and The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Alexandra Durr
- APHP, Department of Genetics and Cytogenetics, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
- Institut du Cerveau et de la Moelle épinière (ICM), Pitié-Salpêtrière University Hospital, Paris, France
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Université Paris 06 UMR S_1127, ICM, F-75013, France
| | - Francoise Pousset
- APHP, Cardiology Department, AP-HP Pitie-Salpétrière Hospital, Paris, France
| | - Michael Parkinson
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Robyn Labrum
- Department of Neurogenetics, University College London Hospital, Institute of Neurology, London, United Kingdom
| | - Paola Giunti
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
- Department of Neurogenetics, University College London Hospital, Institute of Neurology, London, United Kingdom
| | - Susan L Perlman
- Ataxia Center and Huntington Disease Center of Excellence, Department of Neurology, David Geffen School of Medicine at the University of California at Los Angeles, CA
| | - Martin B Delatycki
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- School of Psychological Sciences, Monash University, Clayton, Victoria, Australia
- Clinical Genetics, Austin Health, Heidelberg, Victoria, Australia
| | - Marguerite V Evans-Galea
- Bruce Lefroy Centre, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
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Nabhan JF, Gooch RL, Piatnitski Chekler EL, Pierce B, Bulawa CE. Perturbation of cellular proteostasis networks identifies pathways that modulate precursor and intermediate but not mature levels of frataxin. Sci Rep 2015; 5:18251. [PMID: 26671574 PMCID: PMC4680912 DOI: 10.1038/srep18251] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 11/16/2015] [Indexed: 11/08/2022] Open
Abstract
Friedreich's Ataxia is a genetic disease caused by expansion of an intronic trinucleotide repeat in the frataxin (FXN) gene yielding diminished FXN expression and consequently disease. Since increasing FXN protein levels is desirable to ameliorate pathology, we explored the role of major cellular proteostasis pathways and mitochondrial proteases in FXN processing and turnover. We targeted p97/VCP, the ubiquitin proteasome pathway (UPP), and autophagy with chemical inhibitors in cell lines and patient-derived cells. p97 inhibition by DBeQ increased precursor FXN levels, while UPP and autophagic flux modulators had variable effects predominantly on intermediate FXN. Our data suggest that these pathways cannot be modulated to influence mature functional FXN levels. We also targeted known mitochondrial proteases by RNA interference and discovered a novel protease PITRM1 that regulates intermediate FXN levels. Treatment with the aforementioned chemical and genetic modulators did not have a differential effect in patient cells containing lower amounts of FXN. Interestingly, a number of treatments caused a change in total amount of FXN protein, without an effect on mature FXN. Our results imply that regulation of FXN protein levels is complex and that total amounts can be modulated chemically and genetically without altering the absolute amount of mature FXN protein.
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Affiliation(s)
- Joseph F. Nabhan
- Rare Disease Research Unit, Worldwide Research and Development, Pfizer, 610 Main Street, Cambridge, MA 02139, USA
| | - Renea L. Gooch
- Rare Disease Research Unit, Worldwide Research and Development, Pfizer, 610 Main Street, Cambridge, MA 02139, USA
| | | | - Betsy Pierce
- Worldwide Medicinal Chemistry, Pfizer, Eastern Point Road, Groton, CT 06340, USA
| | - Christine E. Bulawa
- Rare Disease Research Unit, Worldwide Research and Development, Pfizer, 610 Main Street, Cambridge, MA 02139, USA
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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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Abstract
Friedreich ataxia (FRDA) is caused by the expansion of a GAA triplet repeat in the first intron of the FXN gene. This disease was named after Nicholaus Friedreich, Germany, who depicted the essential finding. Among ataxias, FRDA is the most common hereditary ataxia. It has the autosomal recessive pattern of inheritance. The expansion of the GAA triplet repeat hinders the transcription, thereby reducing the level of the FXN transcript and consequently reducing the level of frataxin, a 210-amino acid protein. The disease pathogenesis is fundamentally due to a lack of frataxin, which is claimed to play a role in iron-sulfur cluster synthesis. Oxidative stress builds up as a result of Fe accumulation in the mitochondria, causing degeneration of the cells, which primarily occurs in the neurons and later in the cardiac tissues, and to some extent in the pancreas. The therapeutic interventions are at infancy; however, current treatments are targeted toward the reduction of iron overload and its effects.
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Affiliation(s)
- Srinivasan Muthuswamy
- Department of Medical Genetics, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
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Jobling RK, Assoum M, Gakh O, Blaser S, Raiman JA, Mignot C, Roze E, Dürr A, Brice A, Lévy N, Prasad C, Paton T, Paterson AD, Roslin NM, Marshall CR, Desvignes JP, Roëckel-Trevisiol N, Scherer SW, Rouleau GA, Mégarbané A, Isaya G, Delague V, Yoon G. PMPCA mutations cause abnormal mitochondrial protein processing in patients with non-progressive cerebellar ataxia. Brain 2015; 138:1505-17. [PMID: 25808372 PMCID: PMC4542620 DOI: 10.1093/brain/awv057] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 12/09/2014] [Accepted: 01/06/2015] [Indexed: 11/13/2022] Open
Abstract
Non-progressive cerebellar ataxias are a rare group of disorders that comprise approximately 10% of static infantile encephalopathies. We report the identification of mutations in PMPCA in 17 patients from four families affected with cerebellar ataxia, including the large Lebanese family previously described with autosomal recessive cerebellar ataxia and short stature of Norman type and localized to chromosome 9q34 (OMIM #213200). All patients present with non-progressive cerebellar ataxia, and the majority have intellectual disability of variable severity. PMPCA encodes α-MPP, the alpha subunit of mitochondrial processing peptidase, the primary enzyme responsible for the maturation of the vast majority of nuclear-encoded mitochondrial proteins, which is necessary for life at the cellular level. Analysis of lymphoblastoid cells and fibroblasts from patients homozygous for the PMPCA p.Ala377Thr mutation and carriers demonstrate that the mutation impacts both the level of the alpha subunit encoded by PMPCA and the function of mitochondrial processing peptidase. In particular, this mutation impacts the maturation process of frataxin, the protein which is depleted in Friedreich ataxia. This study represents the first time that defects in PMPCA and mitochondrial processing peptidase have been described in association with a disease phenotype in humans.
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Affiliation(s)
- Rebekah K Jobling
- 1 Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Mirna Assoum
- 2 Inserm, UMR_S 910, 13385, Marseille, France 3 Aix Marseille Université, GMGF, 13385, Marseille, France
| | - Oleksandr Gakh
- 4 Department of Paediatric and Adolescent Medicine and Mayo Clinic Children's Centre, Mayo Clinic, Rochester, MN, USA
| | - Susan Blaser
- 5 Division of Neuroradiology, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Julian A Raiman
- 1 Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Cyril Mignot
- 6 Département de Génétique, Unité de Génétique Clinique, APHP, Groupe Hospitalier Pitié-Salpêtrière; Centre de Référence Maladies Rares 'Déficiences Intellectuelles de Causes Rares'; Groupe de Recherche Clinique UPMC Univ Paris 06; Paris, France
| | - Emmanuel Roze
- 7 Sorbonne Université, UPMC Univ Paris 06, UM 75, ICM, F-75013 Paris, France 8 Inserm, U 1127, ICM, F-75013 Paris, France 9 Cnrs, UMR 7225, ICM, F-75013 Paris, France 10 ICM, Paris, F-75013 Paris, France 11 AP-HP, Hôpital de la Salpêtrière, Département de Neurologie, F-75013, Paris, France
| | - Alexandra Dürr
- 7 Sorbonne Université, UPMC Univ Paris 06, UM 75, ICM, F-75013 Paris, France 8 Inserm, U 1127, ICM, F-75013 Paris, France 9 Cnrs, UMR 7225, ICM, F-75013 Paris, France 10 ICM, Paris, F-75013 Paris, France 12 AP-HP, Hôpital de la Salpêtrière, Département de Génétique et Cytogénétique, F-75013, Paris, France
| | - Alexis Brice
- 7 Sorbonne Université, UPMC Univ Paris 06, UM 75, ICM, F-75013 Paris, France 8 Inserm, U 1127, ICM, F-75013 Paris, France 9 Cnrs, UMR 7225, ICM, F-75013 Paris, France 10 ICM, Paris, F-75013 Paris, France 12 AP-HP, Hôpital de la Salpêtrière, Département de Génétique et Cytogénétique, F-75013, Paris, France
| | - Nicolas Lévy
- 2 Inserm, UMR_S 910, 13385, Marseille, France 3 Aix Marseille Université, GMGF, 13385, Marseille, France 13 Département de Génétique Médicale, Hôpital d'Enfants de la Timone, AP-HM, Marseille, France
| | - Chitra Prasad
- 14 Medical Genetics Program, Department of Pediatrics, London Health Sciences Centre, London, Ontario, Canada
| | - Tara Paton
- 15 The Centre for Applied Genomics and Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Andrew D Paterson
- 15 The Centre for Applied Genomics and Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Nicole M Roslin
- 15 The Centre for Applied Genomics and Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Christian R Marshall
- 15 The Centre for Applied Genomics and Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Jean-Pierre Desvignes
- 2 Inserm, UMR_S 910, 13385, Marseille, France 3 Aix Marseille Université, GMGF, 13385, Marseille, France
| | - Nathalie Roëckel-Trevisiol
- 2 Inserm, UMR_S 910, 13385, Marseille, France 3 Aix Marseille Université, GMGF, 13385, Marseille, France
| | - Stephen W Scherer
- 15 The Centre for Applied Genomics and Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada 16 McLaughlin Centre and Department of Molecular Genetics, University of Toronto
| | - Guy A Rouleau
- 17 Montreal Neurological Institute and Hospital and Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - André Mégarbané
- 18 Unité de Génétique Médicale and Laboratoire Associé Inserm UMR S_910, Faculté de Médecine, Université Saint Joseph, Beirut, Lebanon 19 Institut Jérôme Lejeune, Paris, France
| | - Grazia Isaya
- 4 Department of Paediatric and Adolescent Medicine and Mayo Clinic Children's Centre, Mayo Clinic, Rochester, MN, USA
| | - Valérie Delague
- 2 Inserm, UMR_S 910, 13385, Marseille, France 3 Aix Marseille Université, GMGF, 13385, Marseille, France
| | - Grace Yoon
- 1 Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada 20 Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
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Gentry LE, Thacker MA, Doughty R, Timkovich R, Busenlehner LS. His86 from the N-terminus of frataxin coordinates iron and is required for Fe-S cluster synthesis. Biochemistry 2013; 52:6085-96. [PMID: 23909240 PMCID: PMC3871887 DOI: 10.1021/bi400443n] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Human frataxin has a vital role in the biosynthesis of iron-sulfur (Fe-S) clusters in mitochondria, and its deficiency causes the neurodegenerative disease Friedreich's ataxia. Proposed functions for frataxin in the Fe-S pathway include iron donation to the Fe-S cluster machinery and regulation of cysteine desulfurase activity to control the rate of Fe-S production, although further molecular detail is required to distinguish these two possibilities. It is well established that frataxin can coordinate iron using glutamate and aspartate side chains on the protein surface; however, in this work we identify a new iron coordinating residue in the N-terminus of human frataxin using complementary spectroscopic and structural approaches. Further, we demonstrate that His86 in this N-terminal region is required for high affinity iron coordination and iron assembly of Fe-S clusters by ISCU as part of the Fe-S cluster biosynthetic complex. If a binding site that includes His86 is important for Fe-S cluster synthesis as part of its chaperone function, this raises the possibility that either iron binding at the acidic surface of frataxin may be spurious or that it is required for protein-protein interactions with the Fe-S biosynthetic quaternary complex. Our data suggest that iron coordination to frataxin may be significant to the Fe-S cluster biosynthesis pathway in mitochondria.
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Affiliation(s)
- Leslie E. Gentry
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0336, United States
| | - Matthew A. Thacker
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0336, United States
| | | | - Russell Timkovich
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0336, United States
| | - Laura S. Busenlehner
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0336, United States
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36
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Lane DJR, Huang MLH, Ting S, Sivagurunathan S, Richardson DR. Biochemistry of cardiomyopathy in the mitochondrial disease Friedreich's ataxia. Biochem J 2013; 453:321-36. [PMID: 23849057 DOI: 10.1042/bj20130079] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
FRDA (Friedreich's ataxia) is a debilitating mitochondrial disorder leading to neural and cardiac degeneration, which is caused by a mutation in the frataxin gene that leads to decreased frataxin expression. The most common cause of death in FRDA patients is heart failure, although it is not known how the deficiency in frataxin potentiates the observed cardiomyopathy. The major proposed biochemical mechanisms for disease pathogenesis and the origins of heart failure in FRDA involve metabolic perturbations caused by decreased frataxin expression. Additionally, recent data suggest that low frataxin expression in heart muscle of conditional frataxin knockout mice activates an integrated stress response that contributes to and/or exacerbates cardiac hypertrophy and the loss of cardiomyocytes. The elucidation of these potential mechanisms will lead to a more comprehensive understanding of the pathogenesis of FRDA, and will contribute to the development of better treatments and therapeutics.
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Affiliation(s)
- Darius J R Lane
- Molecular Pharmacology and Pathology Program, Department of Pathology and Bosch Institute, Blackburn Building, D06, University of Sydney, Sydney, NSW 2006, Australia
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37
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Pastore A, Puccio H. Frataxin: a protein in search for a function. J Neurochem 2013; 126 Suppl 1:43-52. [PMID: 23859340 DOI: 10.1111/jnc.12220] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 01/18/2013] [Accepted: 01/23/2013] [Indexed: 01/01/2023]
Abstract
Reduced levels of the protein frataxin cause the neurodegenerative disease Friedreich's ataxia. Pathology is associated with disruption of iron-sulfur cluster biosynthesis, mitochondrial iron overload, and oxidative stress. Frataxin is a highly conserved iron-binding protein present in most organisms. Despite the intense interest generated since the determination of its pathology, identification of the cellular function of frataxin has so far remained elusive. In this review, we revisit the most significant milestones that have led us to our current understanding of frataxin and its functions. The picture that emerges is that frataxin is a crucial element of one of the most essential cellular machines specialized in iron-sulfur cluster biogenesis. Future developments, therefore, can be expected from further advancements in our comprehension of this machine.
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38
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Gomes CM, Santos R. Neurodegeneration in Friedreich's ataxia: from defective frataxin to oxidative stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2013; 2013:487534. [PMID: 23936609 PMCID: PMC3725840 DOI: 10.1155/2013/487534] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Accepted: 06/14/2013] [Indexed: 02/08/2023]
Abstract
Friedreich's ataxia is the most common inherited autosomal recessive ataxia and is characterized by progressive degeneration of the peripheral and central nervous systems and cardiomyopathy. This disease is caused by the silencing of the FXN gene and reduced levels of the encoded protein, frataxin. Frataxin is a mitochondrial protein that functions primarily in iron-sulfur cluster synthesis. This small protein with an α / β sandwich fold undergoes complex processing and imports into the mitochondria, generating isoforms with distinct N-terminal lengths which may underlie different functionalities, also in respect to oligomerization. Missense mutations in the FXN coding region, which compromise protein folding, stability, and function, are found in 4% of FRDA heterozygous patients and are useful to understand how loss of functional frataxin impacts on FRDA physiopathology. In cells, frataxin deficiency leads to pleiotropic phenotypes, including deregulation of iron homeostasis and increased oxidative stress. Increasing amount of data suggest that oxidative stress contributes to neurodegeneration in Friedreich's ataxia.
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Affiliation(s)
- Cláudio M. Gomes
- Instituto Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, 2784-505 Oeiras, Portugal
| | - Renata Santos
- Development of the Nervous System, IBENS, Ecole Normale Supérieure, 46 rue d'Ulm, 75230 Paris Cedex 05, France
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Vaubel RA, Isaya G. Iron-sulfur cluster synthesis, iron homeostasis and oxidative stress in Friedreich ataxia. Mol Cell Neurosci 2013; 55:50-61. [PMID: 22917739 PMCID: PMC3530001 DOI: 10.1016/j.mcn.2012.08.003] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 08/01/2012] [Accepted: 08/05/2012] [Indexed: 12/21/2022] Open
Abstract
Friedreich ataxia (FRDA) is an autosomal recessive, multi-systemic degenerative disease that results from reduced synthesis of the mitochondrial protein frataxin. Frataxin has been intensely studied since its deficiency was linked to FRDA in 1996. The defining properties of frataxin - (i) the ability to bind iron, (ii) the ability to interact with, and donate iron to, other iron-binding proteins, and (iii) the ability to oligomerize, store iron and control iron redox chemistry - have been extensively characterized with different frataxin orthologs and their interacting protein partners. This very large body of biochemical and structural data [reviewed in (Bencze et al., 2006)] supports equally extensive biological evidence that frataxin is critical for mitochondrial iron metabolism and overall cellular iron homeostasis and antioxidant protection [reviewed in (Wilson, 2006)]. However, the precise biological role of frataxin remains a matter of debate. Here, we review seminal and recent data that strongly link frataxin to the synthesis of iron-sulfur cluster cofactors (ISC), as well as controversial data that nevertheless link frataxin to additional iron-related processes. Finally, we discuss how defects in ISC synthesis could be a major (although likely not unique) contributor to the pathophysiology of FRDA via (i) loss of ISC-dependent enzymes, (ii) mitochondrial and cellular iron dysregulation, and (iii) enhanced iron-mediated oxidative stress. This article is part of a Special Issue entitled 'Mitochondrial function and dysfunction in neurodegeneration'.
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Affiliation(s)
- Rachael A Vaubel
- Department of Pediatric & Adolescent Medicine and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, MN 55905, USA
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40
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Lavecchia A, Di Giovanni C, Cerchia C, Russo A, Russo G, Novellino E. Discovery of a novel small molecule inhibitor targeting the frataxin/ubiquitin interaction via structure-based virtual screening and bioassays. J Med Chem 2013; 56:2861-73. [PMID: 23506486 DOI: 10.1021/jm3017199] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive neuro- and cardiodegenerative disorder for which there are no proven effective treatments. FRDA is caused by decreased expression and/or function of the mitochondrial protein frataxin. Here, we report findings that frataxin is degraded via the ubiquitin-proteasomal pathway and that it is ubiquitinated at residue K(147) in Calu-6 cells. A theoretical model of the frataxin-K(147)/Ub complex, constructed by combining bioinformatics interface predictions with information-driven docking, revealed a hitherto unnoticed, potential ubiquitin-binding domain in frataxin. Through structure-based virtual screening and cell-based assays, we discovered a novel small molecule (compound (+)-11) able to prevent frataxin ubiquitination and degradation. (+)-11 was synthesized and tested for specific binding to frataxin by an UF-LC/MS based ligand-binding assay. Follow-up scaffold-based searches resulted in the identification of a lead series with micromolar activity in disrupting the frataxin/Ub interaction. This study also suggests that frataxin could be a potential target for FRDA drug development.
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Affiliation(s)
- Antonio Lavecchia
- Dipartimento di Chimica Farmaceutica e Tossicologica, Drug Discovery Laboratory, Università di Napoli Federico II, Via Domenico Montesano 49, 80131 Napoli, Italy.
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41
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Lionaki E, Tavernarakis N. Oxidative stress and mitochondrial protein quality control in aging. J Proteomics 2013; 92:181-94. [PMID: 23563202 DOI: 10.1016/j.jprot.2013.03.022] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 02/22/2013] [Accepted: 03/25/2013] [Indexed: 12/17/2022]
Abstract
Mitochondrial protein quality control incorporates an elaborate network of chaperones and proteases that survey the organelle for misfolded or unfolded proteins and toxic aggregates. Repair of misfolded or aggregated protein and proteolytic removal of irreversibly damaged proteins are carried out by the mitochondrial protein quality control system. Initial maturation and folding of the nuclear or mitochondrial-encoded mitochondrial proteins are mediated by processing peptidases and chaperones that interact with the protein translocation machinery. Mitochondrial proteins are subjected to cumulative oxidative damage. Thus, impairment of quality control processes may cause mitochondrial dysfunction. Aging has been associated with a marked decline in the effectiveness of mitochondrial protein quality control. Here, we present an overview of the chaperones and proteases involved in the initial folding and maturation of new, incoming precursor molecules, and the subsequent repair and removal of oxidized aggregated proteins. In addition, we highlight the link between mitochondrial protein quality control mechanisms and the aging process. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.
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Affiliation(s)
- Eirini Lionaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 71110, Crete, Greece
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42
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Landry AP, Cheng Z, Ding H. Iron binding activity is essential for the function of IscA in iron-sulphur cluster biogenesis. Dalton Trans 2013; 42:3100-6. [PMID: 23258274 PMCID: PMC3569480 DOI: 10.1039/c2dt32000b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Iron-sulphur cluster biogenesis requires coordinated delivery of iron and sulphur to scaffold proteins, followed by transfer of the assembled clusters from scaffold proteins to target proteins. This complex process is accomplished by a group of dedicated iron-sulphur cluster assembly proteins that are conserved from bacteria to humans. While sulphur in iron-sulphur clusters is provided by L-cysteine via cysteine desulfurase, the iron donor(s) for iron-sulphur cluster assembly remains largely elusive. Here we report that among the primary iron-sulphur cluster assembly proteins, IscA has a unique and strong binding activity for mononuclear iron in vitro and in vivo. Furthermore, the ferric iron centre tightly bound in IscA can be readily extruded by l-cysteine, followed by reduction to ferrous iron for iron-sulphur cluster biogenesis. Substitution of the highly conserved residue tyrosine 40 with phenylalanine (Y40F) in IscA results in a mutant protein that has a diminished iron binding affinity but retains the iron-sulphur cluster binding activity. Genetic complementation studies show that the IscA Y40F mutant is inactive in vivo, suggesting that the iron binding activity is essential for the function of IscA in iron-sulphur cluster biogenesis.
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Affiliation(s)
- Aaron P Landry
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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43
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Li H, Gakh O, Smith DY, Ranatunga WK, Isaya G. Missense mutations linked to friedreich ataxia have different but synergistic effects on mitochondrial frataxin isoforms. J Biol Chem 2013; 288:4116-27. [PMID: 23269675 PMCID: PMC3567662 DOI: 10.1074/jbc.m112.435263] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 12/21/2012] [Indexed: 12/25/2022] Open
Abstract
Friedreich ataxia is an early-onset multisystemic disease linked to a variety of molecular defects in the nuclear gene FRDA. This gene normally encodes the iron-binding protein frataxin (FXN), which is critical for mitochondrial iron metabolism, global cellular iron homeostasis, and antioxidant protection. In most Friedreich ataxia patients, a large GAA-repeat expansion is present within the first intron of both FRDA alleles, that results in transcriptional silencing ultimately leading to insufficient levels of FXN protein in the mitochondrial matrix and probably other cellular compartments. The lack of FXN in turn impairs incorporation of iron into iron-sulfur cluster and heme cofactors, causing widespread enzymatic deficits and oxidative damage catalyzed by excess labile iron. In a minority of patients, a typical GAA expansion is present in only one FRDA allele, whereas a missense mutation is found in the other allele. Although it is known that the disease course for these patients can be as severe as for patients with two expanded FRDA alleles, the underlying pathophysiological mechanisms are not understood. Human cells normally contain two major mitochondrial isoforms of FXN (FXN(42-210) and FXN(81-210)) that have different biochemical properties and functional roles. Using cell-free systems and different cellular models, we show that two of the most clinically severe FXN point mutations, I154F and W155R, have unique direct and indirect effects on the stability, biogenesis, or catalytic activity of FXN(42-210) and FXN(81-210) under physiological conditions. Our data indicate that frataxin point mutations have complex biochemical effects that synergistically contribute to the pathophysiology of Friedreich ataxia.
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Affiliation(s)
- Hongqiao Li
- From the Department of Pediatric and Adolescent Medicine and the Department of Biochemistry and Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, Minnesota 55905
| | - Oleksandr Gakh
- From the Department of Pediatric and Adolescent Medicine and the Department of Biochemistry and Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, Minnesota 55905
| | - Douglas Y. Smith
- From the Department of Pediatric and Adolescent Medicine and the Department of Biochemistry and Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, Minnesota 55905
| | - Wasantha K. Ranatunga
- From the Department of Pediatric and Adolescent Medicine and the Department of Biochemistry and Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, Minnesota 55905
| | - Grazia Isaya
- From the Department of Pediatric and Adolescent Medicine and the Department of Biochemistry and Molecular Biology and the Mayo Clinic Children's Center, Mayo Clinic, Rochester, Minnesota 55905
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Abstract
Friedreich ataxia is the most common human ataxia and results from inadequate production of the frataxin protein, most often the result of a triplet expansion in the nuclear FXN gene. The gene cannot be transcribed to generate the messenger ribonucleic acid for frataxin. Frataxin is an iron-binding protein targeted to the mitochondrial matrix. In its absence, multiple iron-sulfur-dependent proteins in mitochondria and the cytosol lack proper assembly, destroying mitochondrial and nuclear function. Mitochondrial oxidant stress may also participate in ongoing cellular injury. Although progressive and debilitative ataxia is the most prominent clinical finding, hypertrophic cardiomyopathy with heart failure is the most common cause of early death in this disease. There is no cure. In this review the authors cover recent basic and clinical findings regarding the heart in Friedreich ataxia, offer recommendations for clinical management of the cardiomyopathy in this disease, and point out new research directions to advance the field.
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Affiliation(s)
- R Mark Payne
- Department of Medical & Molecular Genetics, Riley Heart Research Center, Wells Center for Pediatric Research, Indianapolis, IN 46202, USA.
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45
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Teixeira PF, Glaser E. Processing peptidases in mitochondria and chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:360-70. [PMID: 22495024 DOI: 10.1016/j.bbamcr.2012.03.012] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 03/21/2012] [Accepted: 03/22/2012] [Indexed: 12/12/2022]
Abstract
Most of the mitochondrial and chloroplastic proteins are nuclear encoded and synthesized in the cytosol as precursor proteins with N-terminal extensions called targeting peptides. Targeting peptides function as organellar import signals, they are recognized by the import receptors and route precursors through the protein translocons across the organellar membranes. After the fulfilled function, targeting peptides are proteolytically cleaved off inside the organelles by different processing peptidases. The processing of mitochondrial precursors is catalyzed in the matrix by the Mitochondrial Processing Peptidase, MPP, the Mitochondrial Intermediate Peptidase, MIP (recently called Octapeptidyl aminopeptidase 1, Oct1) and the Intermediate cleaving peptidase of 55kDa, Icp55. Furthermore, different inner membrane peptidases (Inner Membrane Proteases, IMPs, Atp23, rhomboids and AAA proteases) catalyze additional processing functions, resulting in intra-mitochondrial sorting of proteins, the targeting to the intermembrane space or in the assembly of proteins into inner membrane complexes. Chloroplast targeting peptides are cleaved off in the stroma by the Stromal Processing Peptidase, SPP. If the protein is further translocated to the thylakoid lumen, an additional thylakoid-transfer sequence is removed by the Thylakoidal Processing Peptidase, TPP. Proper function of the D1 protein of Photosystem II reaction center requires its C-terminal processing by Carboxy-terminal processing protease, CtpA. Both in mitochondria and in chloroplasts, the cleaved targeting peptides are finally degraded by the Presequence Protease, PreP. The organellar proteases involved in precursor processing and targeting peptide degradation constitute themselves a quality control system ensuring the correct maturation and localization of proteins as well as assembly of protein complexes, contributing to sustenance of organelle functions. Dysfunctions of several mitochondrial processing proteases have been shown to be associated with human diseases. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
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Affiliation(s)
- Pedro Filipe Teixeira
- Department of Biochemistry and Biophysics, Stockholm University, Arrhenius Laboratories for Natural Sciences, SE-106 91 Stockholm, Sweden
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Vyas PM, Tomamichel WJ, Pride PM, Babbey CM, Wang Q, Mercier J, Martin EM, Payne RM. A TAT-frataxin fusion protein increases lifespan and cardiac function in a conditional Friedreich's ataxia mouse model. Hum Mol Genet 2012; 21:1230-47. [PMID: 22113996 PMCID: PMC3284115 DOI: 10.1093/hmg/ddr554] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 11/21/2011] [Indexed: 11/14/2022] Open
Abstract
Friedreich's ataxia (FRDA) is the most common inherited human ataxia and results from a deficiency of the mitochondrial protein, frataxin (FXN), which is encoded in the nucleus. This deficiency is associated with an iron-sulfur (Fe-S) cluster enzyme deficit leading to progressive ataxia and a frequently fatal cardiomyopathy. There is no cure. To determine whether exogenous replacement of the missing FXN protein in mitochondria would repair the defect, we used the transactivator of transcription (TAT) protein transduction domain to deliver human FXN protein to mitochondria in both cultured patient cells and a severe mouse model of FRDA. A TAT-FXN fusion protein bound iron in vitro, transduced into mitochondria of FRDA deficient fibroblasts and reduced caspase-3 activation in response to an exogenous iron-oxidant stress. Injection of TAT-FXN protein into mice with a conditional loss of FXN increased their growth velocity and mean lifespan by 53% increased their mean heart rate and cardiac output, increased activity of aconitase and reversed abnormal mitochondrial proliferation and ultrastructure in heart. These results show that a cell-penetrant peptide is capable of delivering a functional mitochondrial protein in vivo to rescue a very severe disease phenotype, and present the possibility of TAT-FXN as a protein replacement therapy.
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Affiliation(s)
- Piyush M. Vyas
- Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Wendy J. Tomamichel
- Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - P. Melanie Pride
- Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Clifford M. Babbey
- Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Qiujuan Wang
- Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Jennifer Mercier
- Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Elizabeth M. Martin
- Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - R. Mark Payne
- Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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47
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Mossmann D, Meisinger C, Vögtle FN. Processing of mitochondrial presequences. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1819:1098-106. [PMID: 22172993 DOI: 10.1016/j.bbagrm.2011.11.007] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Revised: 11/07/2011] [Accepted: 11/17/2011] [Indexed: 11/15/2022]
Abstract
Mitochondrial proteins are synthesized as precursor proteins on either cytosolic or mitochondrial ribosomes. The synthesized precursors from both translation origins possess targeting signals that guide the protein to its final destination in one of the four subcompartments of the organelle. The majority of nuclear-encoded mitochondrial precursors and also mitochondrial-encoded preproteins have an N-terminal presequence that serves as a targeting sequence. Specific presequence peptidases that are found in the matrix, inner membrane and intermembrane space of mitochondria proteolytically remove the signal sequence upon import or sorting. Besides the classical presequence peptidases MPP, IMP and Oct1, several novel proteases have recently been described to possess precursor processing activity, and analysis of their functional relevance revealed a tight connection between precursor processing, mitochondrial dynamics and protein quality control. This article is part of a Special Issue entitled: Mitochondrial Gene Expression.
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Affiliation(s)
- Dirk Mossmann
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Universität Freiburg, Freiburg, Germany
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Tsai CL, Bridwell-Rabb J, Barondeau DP. Friedreich's ataxia variants I154F and W155R diminish frataxin-based activation of the iron-sulfur cluster assembly complex. Biochemistry 2011; 50:6478-87. [PMID: 21671584 PMCID: PMC3319458 DOI: 10.1021/bi200666h] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease that has been linked to defects in the protein frataxin (Fxn). Most FRDA patients have a GAA expansion in the first intron of their Fxn gene that decreases protein expression. Some FRDA patients have a GAA expansion on one allele and a missense mutation on the other allele. Few functional details are known for the ∼15 different missense mutations identified in FRDA patients. Here in vitro evidence is presented that indicates the FRDA I154F and W155R variants bind more weakly to the complex of Nfs1, Isd11, and Isu2 and thereby are defective in forming the four-component SDUF complex that constitutes the core of the Fe-S cluster assembly machine. The binding affinities follow the trend Fxn ∼ I154F > W155F > W155A ∼ W155R. The Fxn variants also have diminished ability to function as part of the SDUF complex to stimulate the cysteine desulfurase reaction and facilitate Fe-S cluster assembly. Four crystal structures, including the first for a FRDA variant, reveal specific rearrangements associated with the loss of function and lead to a model for Fxn-based activation of the Fe-S cluster assembly complex. Importantly, the weaker binding and lower activity for FRDA variants correlate with the severity of disease progression. Together, these results suggest that Fxn facilitates sulfur transfer from Nfs1 to Isu2 and that these in vitro assays are sensitive and appropriate for deciphering functional defects and mechanistic details for human Fe-S cluster biosynthesis.
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49
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Marmolino D. Friedreich's ataxia: past, present and future. BRAIN RESEARCH REVIEWS 2011; 67:311-30. [PMID: 21550666 DOI: 10.1016/j.brainresrev.2011.04.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 03/29/2011] [Accepted: 04/12/2011] [Indexed: 01/26/2023]
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive inherited disorder characterized by progressive gait and limb ataxia, dysarthria, areflexia, loss of vibratory and position sense, and a progressive motor weakness of central origin. Additional features include hypertrophic cardiomyopathy and diabetes. Large GAA repeat expansions in the first intron of the FXN gene are the most common mutation underlying FRDA. Patients show severely reduced levels of a FXN-encoded mitochondrial protein called frataxin. Frataxin deficiency is associated with abnormalities of iron metabolism: decreased iron-sulfur cluster (ISC) biogenesis, accumulation of iron in mitochondria and depletion in the cytosol, enhanced cellular iron uptake. Some models have also shown reduced heme synthesis. Evidence for oxidative stress has been reported. Respiratory chain dysfunction aggravates oxidative stress by increasing leakage of electrons and the formation of superoxide. In vitro studies have demonstrated that Frataxin deficient cells not only generate more free radicals, but also show a reduced capacity to mobilize antioxidant defenses. The search for experimental drugs increasing the amount of frataxin is a very active and timely area of investigation. In cellular and in animal model systems, the replacement of frataxin function seems to alleviate the symptoms or even completely reverse the phenotype. Therefore, drugs increasing the amount of frataxin are attractive candidates for novel therapies. This review will discuss recent findings on FRDA pathogenesis, frataxin function, new treatments, as well as recent animal and cellular models. Controversial aspects are also discussed.
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Affiliation(s)
- Daniele Marmolino
- Laboratoire de Neurologie experimentale, Universite Libre de Bruxeles, Route de Lennik 808, Campus Erasme, 1070 Bruxelles, Belgium.
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50
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Napoli E, Ross-Inta C, Wong S, Omanska-Klusek A, Barrow C, Iwahashi C, Garcia-Arocena D, Sakaguchi D, Berry-Kravis E, Hagerman R, Hagerman PJ, Giulivi C. Altered zinc transport disrupts mitochondrial protein processing/import in fragile X-associated tremor/ataxia syndrome. Hum Mol Genet 2011; 20:3079-92. [PMID: 21558427 DOI: 10.1093/hmg/ddr211] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder that affects individuals who are carriers of small CGG premutation expansions in the fragile X mental retardation 1 (FMR1) gene. Mitochondrial dysfunction was observed as an incipient pathological process occurring in individuals who do not display overt features of FXTAS (1). Fibroblasts from premutation carriers had lower oxidative phosphorylation capacity (35% of controls) and Complex IV activity (45%), and higher precursor-to-mature ratios (P:M) of nDNA-encoded mitochondrial proteins (3.1-fold). However, fibroblasts from carriers with FXTAS symptoms presented higher FMR1 mRNA expression (3-fold) and lower Complex V (38%) and aconitase activities (43%). Higher P:M of ATPase β-subunit (ATPB) and frataxin were also observed in cortex from patients that died with FXTAS symptoms. Biochemical findings observed in FXTAS cells (lower mature frataxin, lower Complex IV and aconitase activities) along with common phenotypic traits shared by Friedreich's ataxia and FXTAS carriers (e.g. gait ataxia, loss of coordination) are consistent with a defective iron homeostasis in both diseases. Higher P:M, and lower ZnT6 and mature frataxin protein expression suggested defective zinc and iron metabolism arising from altered ZnT protein expression, which in turn impairs the activity of mitochondrial Zn-dependent proteases, critical for the import and processing of cytosolic precursors, such as frataxin. In support of this hypothesis, Zn-treated fibroblasts showed a significant recovery of ATPB P:M, ATPase activity and doubling time, whereas Zn and desferrioxamine extended these recoveries and rescued Complex IV activity.
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Affiliation(s)
- Eleonora Napoli
- Department of Molecular Biosciences, School of Veterinary Medicine, School of Medicine, University of California Davis, Davis, CA 95616, USA
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