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Povea-Cabello S, Brischigliaro M, Fernández-Vizarra E. Emerging mechanisms in the redox regulation of mitochondrial cytochrome c oxidase assembly and function. Biochem Soc Trans 2024; 52:873-885. [PMID: 38526156 DOI: 10.1042/bst20231183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/12/2024] [Accepted: 03/14/2024] [Indexed: 03/26/2024]
Abstract
In eukaryotic cells, mitochondria perform cellular respiration through a series of redox reactions ultimately reducing molecular oxygen to water. The system responsible for this process is the respiratory chain or electron transport system (ETS) composed of complexes I-IV. Due to its function, the ETS is the main source of reactive oxygen species (ROS), generating them on both sides of the mitochondrial inner membrane, i.e. the intermembrane space (IMS) and the matrix. A correct balance between ROS generation and scavenging is important for keeping the cellular redox homeostasis and other important aspects of cellular physiology. However, ROS generated in the mitochondria are important signaling molecules regulating mitochondrial biogenesis and function. The IMS contains a large number of redox sensing proteins, containing specific Cys-rich domains, that are involved in ETS complex biogenesis. The large majority of these proteins function as cytochrome c oxidase (COX) assembly factors, mainly for the handling of copper ions necessary for the formation of the redox reactive catalytic centers. A particular case of ROS-regulated COX assembly factor is COA8, whose intramitochondrial levels are increased by oxidative stress, promoting COX assembly and/or protecting the enzyme from oxidative damage. In this review, we will discuss the current knowledge concerning the role played by ROS in regulating mitochondrial activity and biogenesis, focusing on the COX enzyme and with a special emphasis on the functional role exerted by the redox sensitive Cys residues contained in the COX assembly factors.
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Affiliation(s)
- Suleva Povea-Cabello
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
- Veneto Institute of Molecular Medicine, 35129 Padova, Italy
| | - Michele Brischigliaro
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
- Veneto Institute of Molecular Medicine, 35129 Padova, Italy
| | - Erika Fernández-Vizarra
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
- Veneto Institute of Molecular Medicine, 35129 Padova, Italy
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2
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Rimoldi M, Magri F, Antognozzi S, Ripolone M, Salani S, Piga D, Bertolasi L, Zanotti S, Ciscato P, Fortunato F, Moggio M, Corti S, Comi GP, Ronchi D. Prominent muscle involvement in a familial form of mitochondrial disease due to a COA8 variant. Front Genet 2023; 14:1278572. [PMID: 38098475 PMCID: PMC10720436 DOI: 10.3389/fgene.2023.1278572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 11/20/2023] [Indexed: 12/17/2023] Open
Abstract
Isolated mitochondrial respiratory chain Complex IV (Cytochrome c Oxidase or COX) deficiency is the second most frequent isolated respiratory chain defect. Causative mutations are mainly identified in structural COX subunits or in proteins involved in the maturation and assembly of the COX holocomplex. We describe an Italian familial case of mitochondrial myopathy due to a variant in the COX assembly factor 8 gene (COA8). Patient 1 is a 52-year-old woman who presented generalized epilepsy and retinitis pigmentosa at 10 years of age. From her early adulthood she complained about cramps and myalgia after exercise, and bilateral hearing loss emerged. Last neurological examination (52 years of age) showed bilateral ptosis, muscle weakness, peripheral neuropathy, mild dysarthria and dysphonia, cognitive impairment. Muscle biopsy had shown the presence of ragged-red fibers. Patient 2 (Patient 1's sister) is a 53-year-old woman presenting fatigability, myalgia, and hearing loss. Neurological examination showed ptosis and muscle weakness. Muscle biopsy displayed a diffuse reduction of COX activity staining and ragged-red fibers. Both sisters presented secondary amenorrhea. After ruling out mtDNA mutations, Whole Exome Sequencing analysis identified the novel homozygous COA8 defect c.170_173dupGACC, p.(Pro59fs) in the probands. Loss-of-function COA8 mutations have been associated with cavitating leukoencephalopathy with COX deficiency in 9 reported individuals. Disease course shows an early-onset rapid clinical deterioration, affecting both cognitive and motor functions over months, followed by stabilization and slow improvement over several years. Our findings expand the clinical spectrum of COA8-related disease. We confirm the benign course of this rare disorder, highlighting its (intrafamilial) clinical variability.
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Affiliation(s)
- Martina Rimoldi
- Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Francesca Magri
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Sara Antognozzi
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Michela Ripolone
- Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Sabrina Salani
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Daniela Piga
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Letizia Bertolasi
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Simona Zanotti
- Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Patrizia Ciscato
- Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Francesco Fortunato
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Maurizio Moggio
- Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Stefania Corti
- Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Giacomo Pietro Comi
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Dario Ronchi
- Neurology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
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3
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Chapleau A, Boucher RM, Pastinen T, Thiffault I, Gould PV, Bernard G. Neuropathological characterization of the cavitating leukoencephalopathy caused by COA8 cytochrome c oxidase deficiency: a case report. Front Cell Neurosci 2023; 17:1216487. [PMID: 37601282 PMCID: PMC10436302 DOI: 10.3389/fncel.2023.1216487] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 07/17/2023] [Indexed: 08/22/2023] Open
Abstract
COA8-related leukoencephalopathy is a recently described rare cavitating leukoencephalopathy caused by biallelic variants in the COA8 gene. Clinically, it presents heterogeneously and usually follows a bi-phasic clinical course with a period of acute onset and regression, followed by stabilization, and in some cases, even subtle improvement. We present a 4-year-old boy with a homozygous 2.5 kilobase pair deletion in the COA8 gene following a severe neurological deterioration resulting in death weeks after onset. Brain MRI revealed a distinctive pattern of cavitating leukodystrophy predominantly involving the posterior cerebral white matter which improved upon a follow-up MRI a month later. Brain pathology displayed overall white matter destruction with gliosis and infiltration by macrophages. There was preservation of astrocytes around blood vessels and axons around the zones of demyelination. This study is the first neuropathological examination of COA8-related leukoencephalopathy and provides further characterization of the clinical and MRI phenotype.
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Affiliation(s)
- Alexandra Chapleau
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - Renée-Myriam Boucher
- Centre Hospitalier Universitaire de Québec-Université Laval, Québec City, QC, Canada
| | - Tomi Pastinen
- Genomic Medicine Center, Children’s Mercy Hospital, Kansas City, MO, United States
- Kansas City School of Medicine, University of Missouri, Kansas City, MO, United States
| | - Isabelle Thiffault
- Genomic Medicine Center, Children’s Mercy Hospital, Kansas City, MO, United States
- Kansas City School of Medicine, University of Missouri, Kansas City, MO, United States
- Department of Pathology and Laboratory Medicine, Children’s Mercy Hospital, Kansas City, MO, United States
| | - Peter V. Gould
- Service d’anatomopathologie Hôpital de l’Enfant-Jésus du CHU de Québec-Université Laval, Québec City, QC, Canada
| | - Geneviève Bernard
- Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Department of Pediatrics, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
- Division of Medical Genetics, Department of Specialized Medicine, McGill University Health Centre, Montreal, QC, Canada
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Tonduti D, Zambon AA, Ghezzi D, Lamantea E, Izzo R, Parazzini C, Baldoli C, van der Knaap MS, Fumagalli F. Expanding the Spectrum of NUBPL-Related Leukodystrophy. Neuropediatrics 2023; 54:161-166. [PMID: 36868263 DOI: 10.1055/s-0043-1764214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Mitochondrial leukodystrophies constitute a group of different conditions presenting with a wide range of clinical presentation but with some shared neuroradiological features. Genetic defects in NUBPL have been recognized as cause of a pediatric onset mitochondrial leukodystrophy characterized by onset at the end of the first year of life with motor delay or regression and cerebellar signs, followed by progressive spasticity. Early magnetic resonance imagings (MRIs) show white matter abnormalities with predominant involvement of frontoparietal regions and corpus callosum. A striking cerebellar involvement is usually observed. Later MRIs show spontaneous improvement of white matter abnormalities but worsening of the cerebellar involvement evolving to global atrophy and progressive involvement of brainstem. After the 7 cases initially described, 11 more subjects were reported. Some of them were similar to patients from the original series while few others broadened the phenotypic spectrum. We performed a literature review and report on a new patient who further expand the spectrum of NUBPL-related leukodystrophy. With our study we confirm that the association of cerebral white matter and cerebellar cortex abnormalities is a feature commonly observed in early stages of the disease but beside the original and so far prevalent presentation, there are also uncommon phenotypes: clinical onset can be earlier and more severe than previously thought and signs of extraneurological involvement can be observed. Brain white matter can be diffusely abnormal without anteroposterior gradient, can progressively worsen, and cystic degeneration can be present. Thalami can be involved. Basal ganglia can also become involved during disease evolution.
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Affiliation(s)
- Davide Tonduti
- Unit of Pediatric Neurology, C.O.A.L.A (Center for Diagnosis and Treatment of Leukodystrophies), V. Buzzi Children's Hospital, Milan, Italy.,Department of Biomedical and Clinical Sciences, L. Sacco University Hospital, Università degli Studi di Milano, Milan, Italy
| | - Alberto A Zambon
- Neuromuscular Repair Unit, Division of Neuroscience, Institute of Experimental Neurology (InSpe), IRCCS Ospedale San Raffaele, Milan, Italy
| | - Daniele Ghezzi
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.,Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Eleonora Lamantea
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Rossella Izzo
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Cecilia Parazzini
- Pediatric Radiology and Neuroradiology Unit, C.O.A.L.A (Center for Diagnosis and Treatment of Leukodystrophies), V. Buzzi Children's Hospital, Milan, Italy
| | - Cristina Baldoli
- Neuroradiology Unit and CERMAC, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Marjo S van der Knaap
- Department of Child Neurology, Emma Children's Hospital, Amsterdam Leukodystrophy Center, Amsterdam University Medical Centers, Vrije Universiteit, Amsterdam, Netherlands.,Amsterdam Neuroscience, Cellular & Molecular Mechanisms, Vrije Universiteit, Amsterdam, Netherlands.,Center for Neurogenomics and Cognitive Research, Integrative Neurophysiology, Vrije Universiteit, Amsterdam, Netherlands
| | - Francesca Fumagalli
- Units of Neurology and Neurophysiology, IRCCS San Raffaele Scientific Institute, Milan, Italy.,San Raffaele Telethon Institute for Gene Therapy (SR-Tiget) and Pediatric Immunohematology and Bone Marrow Transplantation Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
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Protein Transduction Domain-Mediated Delivery of Recombinant Proteins and In Vitro Transcribed mRNAs for Protein Replacement Therapy of Human Severe Genetic Mitochondrial Disorders: The Case of Sco2 Deficiency. Pharmaceutics 2023; 15:pharmaceutics15010286. [PMID: 36678915 PMCID: PMC9861957 DOI: 10.3390/pharmaceutics15010286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/31/2022] [Accepted: 01/09/2023] [Indexed: 01/19/2023] Open
Abstract
Mitochondrial disorders represent a heterogeneous group of genetic disorders with variations in severity and clinical outcomes, mostly characterized by respiratory chain dysfunction and abnormal mitochondrial function. More specifically, mutations in the human SCO2 gene, encoding the mitochondrial inner membrane Sco2 cytochrome c oxidase (COX) assembly protein, have been implicated in the mitochondrial disorder fatal infantile cardioencephalomyopathy with COX deficiency. Since an effective treatment is still missing, a protein replacement therapy (PRT) was explored using protein transduction domain (PTD) technology. Therefore, the human recombinant full-length mitochondrial protein Sco2, fused to TAT peptide (a common PTD), was produced (fusion Sco2 protein) and successfully transduced into fibroblasts derived from a SCO2/COX-deficient patient. This PRT contributed to effective COX assembly and partial recovery of COX activity. In mice, radiolabeled fusion Sco2 protein was biodistributed in the peripheral tissues of mice and successfully delivered into their mitochondria. Complementary to that, an mRNA-based therapeutic approach has been more recently considered as an innovative treatment option. In particular, a patented, novel PTD-mediated IVT-mRNA delivery platform was developed and applied in recent research efforts. PTD-IVT-mRNA of full-length SCO2 was successfully transduced into the fibroblasts derived from a SCO2/COX-deficient patient, translated in host ribosomes into a nascent chain of human Sco2, imported into mitochondria, and processed to the mature protein. Consequently, the recovery of reduced COX activity was achieved, thus suggesting the potential of this mRNA-based technology for clinical translation as a PRT for metabolic/genetic disorders. In this review, such research efforts will be comprehensibly presented and discussed to elaborate their potential in clinical application and therapeutic usefulness.
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Pei J, Zhang J, Cong Q. Human mitochondrial protein complexes revealed by large-scale coevolution analysis and deep learning-based structure modeling. Bioinformatics 2022; 38:4301-4311. [PMID: 35881696 DOI: 10.1093/bioinformatics/btac527] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 05/27/2022] [Accepted: 07/22/2022] [Indexed: 12/24/2022] Open
Abstract
MOTIVATION Recent development of deep-learning methods has led to a breakthrough in the prediction accuracy of 3D protein structures. Extending these methods to protein pairs is expected to allow large-scale detection of protein-protein interactions (PPIs) and modeling protein complexes at the proteome level. RESULTS We applied RoseTTAFold and AlphaFold, two of the latest deep-learning methods for structure predictions, to analyze coevolution of human proteins residing in mitochondria, an organelle of vital importance in many cellular processes including energy production, metabolism, cell death and antiviral response. Variations in mitochondrial proteins have been linked to a plethora of human diseases and genetic conditions. RoseTTAFold, with high computational speed, was used to predict the coevolution of about 95% of mitochondrial protein pairs. Top-ranked pairs were further subject to modeling of the complex structures by AlphaFold, which also produced contact probability with high precision and in many cases consistent with RoseTTAFold. Most top-ranked pairs with high contact probability were supported by known PPIs and/or similarities to experimental structural complexes. For high-scoring pairs without experimental complex structures, our coevolution analyses and structural models shed light on the details of their interfaces, including CHCHD4-AIFM1, MTERF3-TRUB2, FMC1-ATPAF2 and ECSIT-NDUFAF1. We also identified novel PPIs (PYURF-NDUFAF5, LYRM1-MTRF1L and COA8-COX10) for several proteins without experimentally characterized interaction partners, leading to predictions of their molecular functions and the biological processes they are involved in. AVAILABILITY AND IMPLEMENTATION Data of mitochondrial proteins and their interactions are available at: http://conglab.swmed.edu/mitochondria. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Jimin Pei
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jing Zhang
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Qian Cong
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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7
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Fernandez-Vizarra E, Zeviani M. Mitochondrial disorders of the OXPHOS system. FEBS Lett 2020; 595:1062-1106. [PMID: 33159691 DOI: 10.1002/1873-3468.13995] [Citation(s) in RCA: 109] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/21/2020] [Accepted: 11/01/2020] [Indexed: 12/13/2022]
Abstract
Mitochondrial disorders are among the most frequent inborn errors of metabolism, their primary cause being the dysfunction of the oxidative phosphorylation system (OXPHOS). OXPHOS is composed of the electron transport chain (ETC), formed by four multimeric enzymes and two mobile electron carriers, plus an ATP synthase [also called complex V (cV)]. The ETC performs the redox reactions involved in cellular respiration while generating the proton motive force used by cV to synthesize ATP. OXPHOS biogenesis involves multiple steps, starting from the expression of genes encoded in physically separated genomes, namely the mitochondrial and nuclear DNA, to the coordinated assembly of components and cofactors building each individual complex and eventually the supercomplexes. The genetic cause underlying around half of the diagnosed mitochondrial disease cases is currently known. Many of these cases result from pathogenic variants in genes encoding structural subunits or additional factors directly involved in the assembly of the ETC complexes. Here, we review the historical and most recent findings concerning the clinical phenotypes and the molecular pathological mechanisms underlying this particular group of disorders.
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Affiliation(s)
- Erika Fernandez-Vizarra
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, UK
| | - Massimo Zeviani
- Venetian Institute of Molecular Medicine, Padova, Italy.,Department of Neurosciences, University of Padova, Italy
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Cytochrome c oxidase deficiency. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148335. [PMID: 33171185 DOI: 10.1016/j.bbabio.2020.148335] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/31/2020] [Accepted: 11/03/2020] [Indexed: 12/23/2022]
Abstract
Cytochrome c oxidase (COX) deficiency is characterized by a high degree of genetic and phenotypic heterogeneity, partly reflecting the extreme structural complexity, multiple post-translational modification, variable, tissue-specific composition, and the high number of and intricate connections among the assembly factors of this enzyme. In fact, decreased COX specific activity can manifest with different degrees of severity, affect the whole organism or specific tissues, and develop a wide spectrum of disease natural history, including disease onsets ranging from birth to late adulthood. More than 30 genes have been linked to COX deficiency, but the list is still incomplete and in fact constantly updated. We here discuss the current knowledge about COX in health and disease, focusing on genetic aetiology and link to clinical manifestations. In addition, information concerning either fundamental biological features of the enzymes or biochemical signatures of its defects have been provided by experimental in vivo models, including yeast, fly, mouse and fish, which expanded our knowledge on the functional features and the phenotypical consequences of different forms of COX deficiency.
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Hedberg-Oldfors C, Darin N, Thomsen C, Lindberg C, Oldfors A. COX deficiency and leukoencephalopathy due to a novel homozygous APOPT1/COA8 mutation. NEUROLOGY-GENETICS 2020; 6:e464. [PMID: 32637636 PMCID: PMC7323480 DOI: 10.1212/nxg.0000000000000464] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/18/2020] [Indexed: 12/03/2022]
Abstract
Objective To describe the long-term follow-up and pathogenesis in a child with leukoencephalopathy and cytochrome c oxidase (COX) deficiency due to a novel homozygous nonsense mutation in APOPT1/COA8. Methods The patient was clinically investigated at 3, 5, 9, and 25 years of age. Brain MRI, repeat muscle biopsies with biochemical, morphologic, and protein expression analyses were performed, and whole-genome sequencing was used for genetic analysis. Results Clinical investigation revealed dysarthria, dysphagia, and muscle weakness following pneumonia at age 3 years. There was clinical regression leading to severe loss of ambulation, speech, swallowing, hearing, and vision. The clinical course stabilized after 2.5 years and improved over time. The MRI pattern in the patient demonstrated cavitating leukoencephalopathy, and muscle mitochondrial investigations showed COX deficiency with loss of complex IV subunits and ultrastructural abnormalities. Genetic analysis revealed a novel homozygous mutation in the APOPT1/COA8 gene, c.310T>C; p.(Gln104*). Conclusions We describe a novel nonsense mutation in APOPT1/COA8 and provide additional experimental evidence for a COX assembly defect in human muscle causing the complex IV deficiency. The long-term outcome of the disease seems in general to be favorable, and the characteristic MRI pattern with cavitating leukoencephalopathy in combination with COX deficiency should prompt for testing of the APOPT1/COA8 gene.
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Affiliation(s)
- Carola Hedberg-Oldfors
- Department of Pathology and Genetics (C.H.-O., C.T., A.O.) and Department of Pediatrics (N.D.), Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg; and Department of Neurology (C.L.), Neuromuscular Centre, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Niklas Darin
- Department of Pathology and Genetics (C.H.-O., C.T., A.O.) and Department of Pediatrics (N.D.), Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg; and Department of Neurology (C.L.), Neuromuscular Centre, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Christer Thomsen
- Department of Pathology and Genetics (C.H.-O., C.T., A.O.) and Department of Pediatrics (N.D.), Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg; and Department of Neurology (C.L.), Neuromuscular Centre, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Christopher Lindberg
- Department of Pathology and Genetics (C.H.-O., C.T., A.O.) and Department of Pediatrics (N.D.), Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg; and Department of Neurology (C.L.), Neuromuscular Centre, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Anders Oldfors
- Department of Pathology and Genetics (C.H.-O., C.T., A.O.) and Department of Pediatrics (N.D.), Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg; and Department of Neurology (C.L.), Neuromuscular Centre, Sahlgrenska University Hospital, Gothenburg, Sweden
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10
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Mukherjee S, Ghosh A. Molecular mechanism of mitochondrial respiratory chain assembly and its relation to mitochondrial diseases. Mitochondrion 2020; 53:1-20. [PMID: 32304865 DOI: 10.1016/j.mito.2020.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 03/28/2020] [Accepted: 04/07/2020] [Indexed: 12/17/2022]
Abstract
The mitochondrial respiratory chain (MRC) is comprised of ~92 nuclear and mitochondrial DNA-encoded protein subunits that are organized into five different multi-subunit respiratory complexes. These complexes produce 90% of the ATP required for cell sustenance. Specific sets of subunits are assembled in a modular or non-modular fashion to construct the MRC complexes. The complete assembly process is gradually chaperoned by a myriad of assembly factors that must coordinate with several other prosthetic groups to reach maturity, makingthe entire processextensively complicated. Further, the individual respiratory complexes can be integrated intovarious giant super-complexes whose functional roles have yet to be explored. Mutations in the MRC subunits and in the related assembly factors often give rise to defects in the proper assembly of the respiratory chain, which then manifests as a group of disorders called mitochondrial diseases, the most common inborn errors of metabolism. This review summarizes the current understanding of the biogenesis of individual MRC complexes and super-complexes, and explores how mutations in the different subunits and assembly factors contribute to mitochondrial disease pathology.
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Affiliation(s)
- Soumyajit Mukherjee
- Department of Biochemistry, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, India
| | - Alok Ghosh
- Department of Biochemistry, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, India.
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11
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Brischigliaro M, Corrà S, Tregnago C, Fernandez-Vizarra E, Zeviani M, Costa R, De Pittà C. Knockdown of APOPT1/COA8 Causes Cytochrome c Oxidase Deficiency, Neuromuscular Impairment, and Reduced Resistance to Oxidative Stress in Drosophila melanogaster. Front Physiol 2019; 10:1143. [PMID: 31555154 PMCID: PMC6742693 DOI: 10.3389/fphys.2019.01143] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Accepted: 08/22/2019] [Indexed: 12/31/2022] Open
Abstract
Cytochrome c oxidase (COX) deficiency is the biochemical hallmark of several mitochondrial disorders, including subjects affected by mutations in apoptogenic-1 (APOPT1), recently renamed as COA8 (HGNC:20492). Loss-of-function mutations are responsible for a specific infantile or childhood-onset mitochondrial leukoencephalopathy with a chronic clinical course. Patients deficient in COA8 show specific COX deficiency with distinctive neuroimaging features, i.e., cavitating leukodystrophy. In human cells, COA8 is rapidly degraded by the ubiquitin-proteasome system, but oxidative stress stabilizes the protein, which is then involved in COX assembly, possibly by protecting the complex from oxidative damage. However, its precise function remains unknown. The CG14806 gene (dCOA8) is the Drosophila melanogaster ortholog of human COA8 encoding a highly conserved COA8 protein. We report that dCOA8 knockdown (KD) flies show locomotor defects, and other signs of neurological impairment, reduced COX enzymatic activity, and reduced lifespan under oxidative stress conditions. Our data indicate that KD of dCOA8 in Drosophila phenocopies several features of the human disease, thus being a suitable model to characterize the molecular function/s of this protein in vivo and the pathogenic mechanisms associated with its defects.
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Affiliation(s)
| | - Samantha Corrà
- Department of Biology, University of Padova, Padua, Italy
| | - Claudia Tregnago
- Department of Women and Children's Health, University of Padova, Padua, Italy
| | | | - Massimo Zeviani
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom.,Department of Neurosciences, University of Padova, Padua, Italy
| | - Rodolfo Costa
- Department of Biology, University of Padova, Padua, Italy
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Signes A, Cerutti R, Dickson AS, Benincá C, Hinchy EC, Ghezzi D, Carrozzo R, Bertini E, Murphy MP, Nathan JA, Viscomi C, Fernandez-Vizarra E, Zeviani M. APOPT1/COA8 assists COX assembly and is oppositely regulated by UPS and ROS. EMBO Mol Med 2019; 11:e9582. [PMID: 30552096 PMCID: PMC6328941 DOI: 10.15252/emmm.201809582] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 02/02/2023] Open
Abstract
Loss-of-function mutations in APOPT1, a gene exclusively found in higher eukaryotes, cause a characteristic type of cavitating leukoencephalopathy associated with mitochondrial cytochrome c oxidase (COX) deficiency. Although the genetic association of APOPT1 pathogenic variants with isolated COX defects is now clear, the biochemical link between APOPT1 function and COX has remained elusive. We investigated the molecular role of APOPT1 using different approaches. First, we generated an Apopt1 knockout mouse model which shows impaired motor skills, e.g., decreased motor coordination and endurance, associated with reduced COX activity and levels in multiple tissues. In addition, by achieving stable expression of wild-type APOPT1 in control and patient-derived cultured cells we ruled out a role of this protein in apoptosis and established instead that this protein is necessary for proper COX assembly and function. On the other hand, APOPT1 steady-state levels were shown to be controlled by the ubiquitination-proteasome system (UPS). Conversely, in conditions of increased oxidative stress, APOPT1 is stabilized, increasing its mature intramitochondrial form and thereby protecting COX from oxidatively induced degradation.
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Affiliation(s)
- Alba Signes
- MRC-Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Raffaele Cerutti
- MRC-Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Anna S Dickson
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Cristiane Benincá
- MRC-Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | | | - Daniele Ghezzi
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico "Carlo Besta", Milan, Italy
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Rosalba Carrozzo
- Unit of Neuromuscular and Neurodegenerative Disorders, Bambino Gesù Children's Research Hospital, IRCCS, Rome, Italy
| | - Enrico Bertini
- Unit of Neuromuscular and Neurodegenerative Disorders, Bambino Gesù Children's Research Hospital, IRCCS, Rome, Italy
| | - Michael P Murphy
- MRC-Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - James A Nathan
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Carlo Viscomi
- MRC-Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | | | - Massimo Zeviani
- MRC-Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
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