1
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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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Caron-Godon CA, Collington E, Wolf JL, Coletta G, Glerum DM. More than Just Bread and Wine: Using Yeast to Understand Inherited Cytochrome Oxidase Deficiencies in Humans. Int J Mol Sci 2024; 25:3814. [PMID: 38612624 PMCID: PMC11011759 DOI: 10.3390/ijms25073814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 03/26/2024] [Accepted: 03/28/2024] [Indexed: 04/14/2024] Open
Abstract
Inherited defects in cytochrome c oxidase (COX) are associated with a substantial subset of diseases adversely affecting the structure and function of the mitochondrial respiratory chain. This multi-subunit enzyme consists of 14 subunits and numerous cofactors, and it requires the function of some 30 proteins to assemble. COX assembly was first shown to be the primary defect in the majority of COX deficiencies 36 years ago. Over the last three decades, most COX assembly genes have been identified in the yeast Saccharomyces cerevisiae, and studies in yeast have proven instrumental in testing the impact of mutations identified in patients with a specific COX deficiency. The advent of accessible genome-wide sequencing capabilities has led to more patient mutations being identified, with the subsequent identification of several new COX assembly factors. However, the lack of genotype-phenotype correlations and the large number of genes involved in generating a functional COX mean that functional studies must be undertaken to assign a genetic variant as being causal. In this review, we provide a brief overview of the use of yeast as a model system and briefly compare the COX assembly process in yeast and humans. We focus primarily on the studies in yeast that have allowed us to both identify new COX assembly factors and to demonstrate the pathogenicity of a subset of the mutations that have been identified in patients with inherited defects in COX. We conclude with an overview of the areas in which studies in yeast are likely to continue to contribute to progress in understanding disease arising from inherited COX deficiencies.
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Affiliation(s)
- Chenelle A. Caron-Godon
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada; (C.A.C.-G.); (E.C.); (J.L.W.); (G.C.)
| | - Emma Collington
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada; (C.A.C.-G.); (E.C.); (J.L.W.); (G.C.)
| | - Jessica L. Wolf
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada; (C.A.C.-G.); (E.C.); (J.L.W.); (G.C.)
| | - Genna Coletta
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada; (C.A.C.-G.); (E.C.); (J.L.W.); (G.C.)
| | - D. Moira Glerum
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada; (C.A.C.-G.); (E.C.); (J.L.W.); (G.C.)
- Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
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3
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Sun Q, Shi L, Li S, Li J, Zhang R, Huang X, Shao Y, Feng Z, Peng Y, Yang Z, Liu J, Liu H, Long J. PET117 assembly factor stabilizes translation activator TACO1 thereby upregulates mitochondria-encoded cytochrome C oxidase 1 synthesis. Free Radic Biol Med 2023; 205:13-24. [PMID: 37247699 DOI: 10.1016/j.freeradbiomed.2023.05.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 05/19/2023] [Accepted: 05/19/2023] [Indexed: 05/31/2023]
Abstract
Cytochrome c oxidase, also known as complex IV, facilitates the transfer of electrons from cytochrome c to molecular oxygen, resulting in the production of ATP. The assembly of complex IV is a tightly regulated and intricate process that entails the coordinated synthesis and integration of subunits encoded by the mitochondria and nucleus into a functional complex. Accurate regulation of translation is crucial for maintaining proper mitochondrial function, and defects in this process can lead to a wide range of mitochondrial disorders and diseases. However, the mechanisms governing mRNA translation by mitoribosomes in mammals remain largely unknown. In this study, we elucidate the critical role of PET117, a chaperone protein involved in complex IV assembly, in the regulation of mitochondria-encoded cytochrome c oxidase 1 (COX1) protein synthesis in human cells. Depletion of PET117 reduced mitochondrial oxygen consumption rate and impaired mitochondrial function. PET117 was found to interact with and stabilize translational activator of COX1 (TACO1) and prevent its ubiquitination. TACO1 overexpression rescued the inhibitory effects on mitochondria caused by PET117 deficiency. These findings provide evidence for a novel PET117-TACO1 axis in the regulation of mitochondrial protein expression, and revealed a previously unknown role of PET117 in human cells.
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Affiliation(s)
- Qiong Sun
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Le Shi
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Shuaijun Li
- School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China
| | - Jialu Li
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Ruifen Zhang
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Xinghuai Huang
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Yongping Shao
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Zhihui Feng
- Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Yunhua Peng
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Zhiwei Yang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Jiankang Liu
- School of Health and Life Sciences, University of Health and Rehabilitation Sciences, Qingdao, Shandong, 266071, China
| | - Huadong Liu
- School of Health and Life Sciences, University of Health and Rehabilitation Sciences, Qingdao, Shandong, 266071, China.
| | - Jiangang Long
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China.
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4
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Anderson AJ, Crameri JJ, Ang C, Malcolm TR, Kang Y, Baker MJ, Palmer CS, Sharpe AJ, Formosa LE, Ganio K, Baker MJ, McDevitt CA, Ryan MT, Maher MJ, Stojanovski D. Human Tim8a, Tim8b and Tim13 are auxiliary assembly factors of mature Complex IV. EMBO Rep 2023; 24:e56430. [PMID: 37272231 PMCID: PMC10398661 DOI: 10.15252/embr.202256430] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 05/11/2023] [Accepted: 05/16/2023] [Indexed: 06/06/2023] Open
Abstract
Human Tim8a and Tim8b are paralogous intermembrane space proteins of the small TIM chaperone family. Yeast small TIMs function in the trafficking of proteins to the outer and inner mitochondrial membranes. This putative import function for hTim8a and hTim8b has been challenged in human models, but their precise molecular function(s) remains undefined. Likewise, the necessity for human cells to encode two Tim8 proteins and whether any potential redundancy exists is unclear. We demonstrate that hTim8a and hTim8b function in the assembly of cytochrome c oxidase (Complex IV). Using affinity enrichment mass spectrometry, we define the interaction network of hTim8a, hTim8b and hTim13, identifying subunits and assembly factors of the Complex IV COX2 module. hTim8-deficient cells have a COX2 and COX3 module defect and exhibit an accumulation of the Complex IV S2 subcomplex. These data suggest that hTim8a and hTim8b function in assembly of Complex IV via interactions with intermediate-assembly subcomplexes. We propose that hTim8-hTim13 complexes are auxiliary assembly factors involved in the formation of the Complex IV S3 subcomplex during assembly of mature Complex IV.
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Affiliation(s)
- Alexander J Anderson
- Department of Biochemistry and PharmacologyThe University of MelbourneParkvilleVicAustralia
- The Bio21 Molecular Science and Biotechnology InstituteThe University of MelbourneParkvilleVicAustralia
| | - Jordan J Crameri
- Department of Biochemistry and PharmacologyThe University of MelbourneParkvilleVicAustralia
- The Bio21 Molecular Science and Biotechnology InstituteThe University of MelbourneParkvilleVicAustralia
| | - Ching‐Seng Ang
- The Bio21 Molecular Science and Biotechnology InstituteThe University of MelbourneParkvilleVicAustralia
| | - Tess R Malcolm
- The Bio21 Molecular Science and Biotechnology InstituteThe University of MelbourneParkvilleVicAustralia
- School of ChemistryThe University of MelbourneParkvilleVicAustralia
| | - Yilin Kang
- Department of Biochemistry and PharmacologyThe University of MelbourneParkvilleVicAustralia
- The Bio21 Molecular Science and Biotechnology InstituteThe University of MelbourneParkvilleVicAustralia
| | - Megan J Baker
- Department of Biochemistry and PharmacologyThe University of MelbourneParkvilleVicAustralia
- The Bio21 Molecular Science and Biotechnology InstituteThe University of MelbourneParkvilleVicAustralia
| | - Catherine S Palmer
- Department of Biochemistry and PharmacologyThe University of MelbourneParkvilleVicAustralia
- The Bio21 Molecular Science and Biotechnology InstituteThe University of MelbourneParkvilleVicAustralia
| | - Alice J Sharpe
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery InstituteMonash UniversityClaytonVicAustralia
| | - Luke E Formosa
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery InstituteMonash UniversityClaytonVicAustralia
| | - Katherine Ganio
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and ImmunityThe University of MelbourneParkvilleVicAustralia
| | - Michael J Baker
- Department of Biochemistry and PharmacologyThe University of MelbourneParkvilleVicAustralia
- The Bio21 Molecular Science and Biotechnology InstituteThe University of MelbourneParkvilleVicAustralia
| | - Christopher A McDevitt
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and ImmunityThe University of MelbourneParkvilleVicAustralia
| | - Michael T Ryan
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery InstituteMonash UniversityClaytonVicAustralia
| | - Megan J Maher
- The Bio21 Molecular Science and Biotechnology InstituteThe University of MelbourneParkvilleVicAustralia
- School of ChemistryThe University of MelbourneParkvilleVicAustralia
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular ScienceLa Trobe UniversityBundooraVicAustralia
| | - Diana Stojanovski
- Department of Biochemistry and PharmacologyThe University of MelbourneParkvilleVicAustralia
- The Bio21 Molecular Science and Biotechnology InstituteThe University of MelbourneParkvilleVicAustralia
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5
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Yang Y, Zhou Y, Nyholt DR, Yap CX, Tannenberg RK, Wang Y, Wu Y, Zhu Z, Taylor BV, Gratten J. The shared genetic landscape of blood cell traits and risk of neurological and psychiatric disorders. CELL GENOMICS 2023; 3:100249. [PMID: 36819664 PMCID: PMC9932996 DOI: 10.1016/j.xgen.2022.100249] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/03/2022] [Accepted: 12/20/2022] [Indexed: 01/27/2023]
Abstract
Phenotypic associations have been reported between blood cell traits (BCTs) and a range of neurological and psychiatric disorders (NPDs), but in most cases, it remains unclear whether these associations have a genetic basis and, if so, to what extent genetic correlations reflect causality. Here, we report genetic correlations and Mendelian randomization analyses between 11 NPDs and 29 BCTs, using genome-wide association study summary statistics. We found significant genetic correlations for four BCT-NPD pairs, all of which have prior evidence for a phenotypic correlation. We identified a previously unreported causal effect of increased platelet distribution width on susceptibility to Parkinson's disease. We identified multiple functional genes and regulatory elements for specific BCT-NPD pairs, some of which are targets of known drugs. These results enrich our understanding of the shared genetic landscape underlying BCTs and NPDs and provide a robust foundation for future work to improve prognosis and treatment of common NPDs.
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Affiliation(s)
- Yuanhao Yang
- Mater Research Institute, The University of Queensland, Woolloongabba, QLD 4102, Australia
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
- Corresponding author
| | - Yuan Zhou
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7000, Australia
| | - Dale R. Nyholt
- School of Biomedical Sciences, Faculty of Health, and Centre for Genomics and Personalised Health, Queensland University of Technology, Kelvin Grove, QLD 4059, Australia
| | - Chloe X. Yap
- Mater Research Institute, The University of Queensland, Woolloongabba, QLD 4102, Australia
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Rudolph K. Tannenberg
- Mater Research Institute, The University of Queensland, Woolloongabba, QLD 4102, Australia
| | - Ying Wang
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA 02114, USA
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Yang Wu
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Zhihong Zhu
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
- National Centre for Register-based Research, Aarhus University, Aarhus 8210, Denmark
| | - Bruce V. Taylor
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7000, Australia
| | - Jacob Gratten
- Mater Research Institute, The University of Queensland, Woolloongabba, QLD 4102, Australia
- Corresponding author
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6
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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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7
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Nývltová E, Dietz JV, Seravalli J, Khalimonchuk O, Barrientos A. Coordination of metal center biogenesis in human cytochrome c oxidase. Nat Commun 2022; 13:3615. [PMID: 35750769 PMCID: PMC9232578 DOI: 10.1038/s41467-022-31413-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 06/16/2022] [Indexed: 01/12/2023] Open
Abstract
Mitochondrial cytochrome c oxidase (CcO) or respiratory chain complex IV is a heme aa3-copper oxygen reductase containing metal centers essential for holo-complex biogenesis and enzymatic function that are assembled by subunit-specific metallochaperones. The enzyme has two copper sites located in the catalytic core subunits. The COX1 subunit harbors the CuB site that tightly associates with heme a3 while the COX2 subunit contains the binuclear CuA site. Here, we report that in human cells the CcO copper chaperones form macromolecular assemblies and cooperate with several twin CX9C proteins to control heme a biosynthesis and coordinate copper transfer sequentially to the CuA and CuB sites. These data on CcO illustrate a mechanism that regulates the biogenesis of macromolecular enzymatic assemblies with several catalytic metal redox centers and prevents the accumulation of cytotoxic reactive assembly intermediates.
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Affiliation(s)
- Eva Nývltová
- Department of Neurology, University of Miami Miller School of Medicine, 1420NW 9th Ave, Miami, FL, 33136, USA
| | - Jonathan V Dietz
- Department of Biochemistry, University of Nebraska-Lincoln, 1901 Vine St. Beadle Center, Lincoln, NE, 68588, USA
| | - Javier Seravalli
- Nebraska Redox Biology Center, University of Nebraska-Lincoln, 1901 Vine St. Beadle Center, Lincoln, NE, 68588, USA
| | - Oleh Khalimonchuk
- Department of Biochemistry, University of Nebraska-Lincoln, 1901 Vine St. Beadle Center, Lincoln, NE, 68588, USA
- Nebraska Redox Biology Center, University of Nebraska-Lincoln, 1901 Vine St. Beadle Center, Lincoln, NE, 68588, USA
| | - Antoni Barrientos
- Department of Neurology, University of Miami Miller School of Medicine, 1420NW 9th Ave, Miami, FL, 33136, USA.
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, 1420NW 9th Ave, Miami, FL, 33136, USA.
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8
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Swaminathan AB, Soma S, Vicary AC, Zulkifli M, Kaur H, Gohil VM. A yeast suppressor screen links Coa4 to the mitochondrial copper delivery pathway for cytochrome c oxidase. Genetics 2022; 221:6603117. [PMID: 35666203 DOI: 10.1093/genetics/iyac090] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/25/2022] [Indexed: 11/13/2022] Open
Abstract
Cytochrome c oxidase (CcO) is a multimeric copper-containing enzyme of the mitochondrial respiratory chain that powers cellular energy production. The two core subunits of CcO, Cox1 and Cox2, harbor the catalytic CuB and CuA sites, respectively. Biogenesis of each copper site occurs separately and requires multiple proteins that constitute the mitochondrial copper delivery pathway. Currently, the identity of all the members of the pathway is not known, though several evolutionarily conserved twin CX9C motif-containing proteins have been implicated in this process. Here, we performed a targeted yeast suppressor screen that placed Coa4, a twin CX9C motif-containing protein, in the copper delivery pathway to the Cox1 subunit. Specifically, we show that overexpression of Cox11, a copper metallochaperone required for the formation of CuB site, can restore Cox1 abundance, CcO assembly, and mitochondrial respiration in coa4Δ cells. This rescue is dependent on the copper-coordinating cysteines of Cox11. The abundance of Coa4 and Cox11 in mitochondria is reciprocally regulated, further linking Coa4 to the CuB site biogenesis. Additionally, we find that coa4Δ cells have reduced levels of copper and exogenous copper supplementation can partially ameliorate its respiratory-deficient phenotype, a finding that connects Coa4 to cellular copper homeostasis. Finally, we demonstrate that human COA4 can replace the function of yeast Coa4 indicating its evolutionarily conserved role. Our work provides genetic evidences for the role of Coa4 in the copper delivery pathway to the CuB site of CcO.
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Affiliation(s)
- Abhinav B Swaminathan
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Shivatheja Soma
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Alison C Vicary
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Mohammad Zulkifli
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Harman Kaur
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
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9
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Gayathri N, Deepha S, Sharma S. Diagnosis of primary mitochondrial disorders -Emphasis on myopathological aspects. Mitochondrion 2021; 61:69-84. [PMID: 34592422 DOI: 10.1016/j.mito.2021.09.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/03/2021] [Accepted: 09/22/2021] [Indexed: 12/29/2022]
Abstract
Mitochondrial disorders are one of the most common neurometabolic disorders affecting all age groups. The phenotype-genotype heterogeneity in these disorders can be attributed to the dual genetic control on mitochondrial functions, posing a challenge for diagnosis. Though the advancement in the high-throughput sequencing and other omics platforms resulted in a "genetics-first" approach, the muscle biopsy remains the benchmark in most of the mitochondrial disorders. This review focuses on the myopathological aspects of primary mitochondrial disorders. The utility of muscle biopsy is not limited to analyse the structural abnormalities; rather it also proves to be a potential tool to understand the deranged sub-cellular functions.
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Affiliation(s)
- Narayanappa Gayathri
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore 560 029, India.
| | - Sekar Deepha
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore 560 029, India
| | - Shivani Sharma
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore 560 029, India
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10
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Geldon S, Fernández-Vizarra E, Tokatlidis K. Redox-Mediated Regulation of Mitochondrial Biogenesis, Dynamics, and Respiratory Chain Assembly in Yeast and Human Cells. Front Cell Dev Biol 2021; 9:720656. [PMID: 34557489 PMCID: PMC8452992 DOI: 10.3389/fcell.2021.720656] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/04/2021] [Indexed: 12/24/2022] Open
Abstract
Mitochondria are double-membrane organelles that contain their own genome, the mitochondrial DNA (mtDNA), and reminiscent of its endosymbiotic origin. Mitochondria are responsible for cellular respiration via the function of the electron oxidative phosphorylation system (OXPHOS), located in the mitochondrial inner membrane and composed of the four electron transport chain (ETC) enzymes (complexes I-IV), and the ATP synthase (complex V). Even though the mtDNA encodes essential OXPHOS components, the large majority of the structural subunits and additional biogenetical factors (more than seventy proteins) are encoded in the nucleus and translated in the cytoplasm. To incorporate these proteins and the rest of the mitochondrial proteome, mitochondria have evolved varied, and sophisticated import machineries that specifically target proteins to the different compartments defined by the two membranes. The intermembrane space (IMS) contains a high number of cysteine-rich proteins, which are mostly imported via the MIA40 oxidative folding system, dependent on the reduction, and oxidation of key Cys residues. Several of these proteins are structural components or assembly factors necessary for the correct maturation and function of the ETC complexes. Interestingly, many of these proteins are involved in the metalation of the active redox centers of complex IV, the terminal oxidase of the mitochondrial ETC. Due to their function in oxygen reduction, mitochondria are the main generators of reactive oxygen species (ROS), on both sides of the inner membrane, i.e., in the matrix and the IMS. ROS generation is important due to their role as signaling molecules, but an excessive production is detrimental due to unwanted oxidation reactions that impact on the function of different types of biomolecules contained in mitochondria. Therefore, the maintenance of the redox balance in the IMS is essential for mitochondrial function. In this review, we will discuss the role that redox regulation plays in the maintenance of IMS homeostasis as well as how mitochondrial ROS generation may be a key regulatory factor for ETC biogenesis, especially for complex IV.
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Affiliation(s)
| | - Erika Fernández-Vizarra
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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11
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Zanfardino P, Doccini S, Santorelli FM, Petruzzella V. Tackling Dysfunction of Mitochondrial Bioenergetics in the Brain. Int J Mol Sci 2021; 22:8325. [PMID: 34361091 PMCID: PMC8348117 DOI: 10.3390/ijms22158325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/29/2021] [Accepted: 07/30/2021] [Indexed: 12/15/2022] Open
Abstract
Oxidative phosphorylation (OxPhos) is the basic function of mitochondria, although the landscape of mitochondrial functions is continuously growing to include more aspects of cellular homeostasis. Thanks to the application of -omics technologies to the study of the OxPhos system, novel features emerge from the cataloging of novel proteins as mitochondrial thus adding details to the mitochondrial proteome and defining novel metabolic cellular interrelations, especially in the human brain. We focussed on the diversity of bioenergetics demand and different aspects of mitochondrial structure, functions, and dysfunction in the brain. Definition such as 'mitoexome', 'mitoproteome' and 'mitointeractome' have entered the field of 'mitochondrial medicine'. In this context, we reviewed several genetic defects that hamper the last step of aerobic metabolism, mostly involving the nervous tissue as one of the most prominent energy-dependent tissues and, as consequence, as a primary target of mitochondrial dysfunction. The dual genetic origin of the OxPhos complexes is one of the reasons for the complexity of the genotype-phenotype correlation when facing human diseases associated with mitochondrial defects. Such complexity clinically manifests with extremely heterogeneous symptoms, ranging from organ-specific to multisystemic dysfunction with different clinical courses. Finally, we briefly discuss the future directions of the multi-omics study of human brain disorders.
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Affiliation(s)
- Paola Zanfardino
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy;
| | - Stefano Doccini
- IRCCS Fondazione Stella Maris, Calambrone, 56128 Pisa, Italy;
| | | | - Vittoria Petruzzella
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy;
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Edwards R, Eaglesfield R, Tokatlidis K. The mitochondrial intermembrane space: the most constricted mitochondrial sub-compartment with the largest variety of protein import pathways. Open Biol 2021; 11:210002. [PMID: 33715390 PMCID: PMC8061763 DOI: 10.1098/rsob.210002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The mitochondrial intermembrane space (IMS) is the most constricted sub-mitochondrial compartment, housing only about 5% of the mitochondrial proteome, and yet is endowed with the largest variability of protein import mechanisms. In this review, we summarize our current knowledge of the major IMS import pathway based on the oxidative protein folding pathway and discuss the stunning variability of other IMS protein import pathways. As IMS-localized proteins only have to cross the outer mitochondrial membrane, they do not require energy sources like ATP hydrolysis in the mitochondrial matrix or the inner membrane electrochemical potential which are critical for import into the matrix or insertion into the inner membrane. We also explore several atypical IMS import pathways that are still not very well understood and are guided by poorly defined or completely unknown targeting peptides. Importantly, many of the IMS proteins are linked to several human diseases, and it is therefore crucial to understand how they reach their normal site of function in the IMS. In the final part of this review, we discuss current understanding of how such IMS protein underpin a large spectrum of human disorders.
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Affiliation(s)
- Ruairidh Edwards
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
| | - Ross Eaglesfield
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
| | - Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
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Gladyck S, Aras S, Hüttemann M, Grossman LI. Regulation of COX Assembly and Function by Twin CX 9C Proteins-Implications for Human Disease. Cells 2021; 10:197. [PMID: 33498264 PMCID: PMC7909247 DOI: 10.3390/cells10020197] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 12/29/2022] Open
Abstract
Oxidative phosphorylation is a tightly regulated process in mammals that takes place in and across the inner mitochondrial membrane and consists of the electron transport chain and ATP synthase. Complex IV, or cytochrome c oxidase (COX), is the terminal enzyme of the electron transport chain, responsible for accepting electrons from cytochrome c, pumping protons to contribute to the gradient utilized by ATP synthase to produce ATP, and reducing oxygen to water. As such, COX is tightly regulated through numerous mechanisms including protein-protein interactions. The twin CX9C family of proteins has recently been shown to be involved in COX regulation by assisting with complex assembly, biogenesis, and activity. The twin CX9C motif allows for the import of these proteins into the intermembrane space of the mitochondria using the redox import machinery of Mia40/CHCHD4. Studies have shown that knockdown of the proteins discussed in this review results in decreased or completely deficient aerobic respiration in experimental models ranging from yeast to human cells, as the proteins are conserved across species. This article highlights and discusses the importance of COX regulation by twin CX9C proteins in the mitochondria via COX assembly and control of its activity through protein-protein interactions, which is further modulated by cell signaling pathways. Interestingly, select members of the CX9C protein family, including MNRR1 and CHCHD10, show a novel feature in that they not only localize to the mitochondria but also to the nucleus, where they mediate oxygen- and stress-induced transcriptional regulation, opening a new view of mitochondrial-nuclear crosstalk and its involvement in human disease.
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Affiliation(s)
- Stephanie Gladyck
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.G.); (S.A.); (M.H.)
| | - Siddhesh Aras
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.G.); (S.A.); (M.H.)
- Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland and Detroit, MI 48201, USA
| | - Maik Hüttemann
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.G.); (S.A.); (M.H.)
| | - Lawrence I. Grossman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.G.); (S.A.); (M.H.)
- Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland and Detroit, MI 48201, USA
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14
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Mitochondrial Structure and Bioenergetics in Normal and Disease Conditions. Int J Mol Sci 2021; 22:ijms22020586. [PMID: 33435522 PMCID: PMC7827222 DOI: 10.3390/ijms22020586] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/03/2021] [Accepted: 01/04/2021] [Indexed: 02/06/2023] Open
Abstract
Mitochondria are ubiquitous intracellular organelles found in almost all eukaryotes and involved in various aspects of cellular life, with a primary role in energy production. The interest in this organelle has grown stronger with the discovery of their link to various pathologies, including cancer, aging and neurodegenerative diseases. Indeed, dysfunctional mitochondria cannot provide the required energy to tissues with a high-energy demand, such as heart, brain and muscles, leading to a large spectrum of clinical phenotypes. Mitochondrial defects are at the origin of a group of clinically heterogeneous pathologies, called mitochondrial diseases, with an incidence of 1 in 5000 live births. Primary mitochondrial diseases are associated with genetic mutations both in nuclear and mitochondrial DNA (mtDNA), affecting genes involved in every aspect of the organelle function. As a consequence, it is difficult to find a common cause for mitochondrial diseases and, subsequently, to offer a precise clinical definition of the pathology. Moreover, the complexity of this condition makes it challenging to identify possible therapies or drug targets.
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15
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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: 112] [Impact Index Per Article: 28.0] [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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Human Mitochondrial Pathologies of the Respiratory Chain and ATP Synthase: Contributions from Studies of Saccharomyces cerevisiae. Life (Basel) 2020; 10:life10110304. [PMID: 33238568 PMCID: PMC7700678 DOI: 10.3390/life10110304] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 12/14/2022] Open
Abstract
The ease with which the unicellular yeast Saccharomyces cerevisiae can be manipulated genetically and biochemically has established this organism as a good model for the study of human mitochondrial diseases. The combined use of biochemical and molecular genetic tools has been instrumental in elucidating the functions of numerous yeast nuclear gene products with human homologs that affect a large number of metabolic and biological processes, including those housed in mitochondria. These include structural and catalytic subunits of enzymes and protein factors that impinge on the biogenesis of the respiratory chain. This article will review what is currently known about the genetics and clinical phenotypes of mitochondrial diseases of the respiratory chain and ATP synthase, with special emphasis on the contribution of information gained from pet mutants with mutations in nuclear genes that impair mitochondrial respiration. Our intent is to provide the yeast mitochondrial specialist with basic knowledge of human mitochondrial pathologies and the human specialist with information on how genes that directly and indirectly affect respiration were identified and characterized in yeast.
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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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18
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The ubiquitin-proteasome system and its crosstalk with mitochondria as therapeutic targets in medicine. Pharmacol Res 2020; 163:105248. [PMID: 33065283 DOI: 10.1016/j.phrs.2020.105248] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 12/12/2022]
Abstract
The ubiquitin-proteasome system constitutes a major pathway for protein degradation in the cell. Therefore the crosstalk of this pathway with mitochondria is a major topic with direct relevance to many mitochondrial diseases. Proteasome dysfunction triggers not only protein toxicity, but also mitochondrial dysfunction. The involvement of proteasomes in the regulation of protein transport into mitochondria contributes to an increase in mitochondrial function defects. On the other hand, mitochondrial impairment stimulates reactive oxygen species production, which increases protein damage, and protein misfolding and aggregation leading to proteasome overload. Concurrently, mitochondrial dysfunction compromises cellular ATP production leading to reduced protein ubiquitination and proteasome activity. In this review we discuss the complex relationship and interdependence of the ubiquitin-proteasome system and mitochondria. Furthermore, we describe pharmacological inhibition of proteasome activity as a novel strategy to treat a group of mitochondrial diseases.
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Functions of Cytochrome c oxidase Assembly Factors. Int J Mol Sci 2020; 21:ijms21197254. [PMID: 33008142 PMCID: PMC7582755 DOI: 10.3390/ijms21197254] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 09/23/2020] [Indexed: 12/22/2022] Open
Abstract
Cytochrome c oxidase is the terminal complex of eukaryotic oxidative phosphorylation in mitochondria. This process couples the reduction of electron carriers during metabolism to the reduction of molecular oxygen to water and translocation of protons from the internal mitochondrial matrix to the inter-membrane space. The electrochemical gradient formed is used to generate chemical energy in the form of adenosine triphosphate to power vital cellular processes. Cytochrome c oxidase and most oxidative phosphorylation complexes are the product of the nuclear and mitochondrial genomes. This poses a series of topological and temporal steps that must be completed to ensure efficient assembly of the functional enzyme. Many assembly factors have evolved to perform these steps for insertion of protein into the inner mitochondrial membrane, maturation of the polypeptide, incorporation of co-factors and prosthetic groups and to regulate this process. Much of the information about each of these assembly factors has been gleaned from use of the single cell eukaryote Saccharomyces cerevisiae and also mutations responsible for human disease. This review will focus on the assembly factors of cytochrome c oxidase to highlight some of the outstanding questions in the assembly of this vital enzyme complex.
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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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21
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Sacchetto C, Sequeira V, Bertero E, Dudek J, Maack C, Calore M. Metabolic Alterations in Inherited Cardiomyopathies. J Clin Med 2019; 8:E2195. [PMID: 31842377 PMCID: PMC6947282 DOI: 10.3390/jcm8122195] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 12/12/2022] Open
Abstract
The normal function of the heart relies on a series of complex metabolic processes orchestrating the proper generation and use of energy. In this context, mitochondria serve a crucial role as a platform for energy transduction by supplying ATP to the varying demand of cardiomyocytes, involving an intricate network of pathways regulating the metabolic flux of substrates. The failure of these processes results in structural and functional deficiencies of the cardiac muscle, including inherited cardiomyopathies. These genetic diseases are characterized by cardiac structural and functional anomalies in the absence of abnormal conditions that can explain the observed myocardial abnormality, and are frequently associated with heart failure. Since their original description, major advances have been achieved in the genetic and phenotype knowledge, highlighting the involvement of metabolic abnormalities in their pathogenesis. This review provides a brief overview of the role of mitochondria in the energy metabolism in the heart and focuses on metabolic abnormalities, mitochondrial dysfunction, and storage diseases associated with inherited cardiomyopathies.
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Affiliation(s)
- Claudia Sacchetto
- IMAiA—Institute for Molecular Biology and RNA Technology, Faculty of Health, Universiteitssingel 50, 6229ER Maastricht, The Netherlands;
- Medicine and Life Sciences, Faculty of Science and Engineering, Universiteitssingel 50, 6229ER Maastricht, The Netherlands
- Department of Biology, University of Padova, via Ugo Bassi 58B, 35121 Padova, Italy
| | - Vasco Sequeira
- Department of Translational Science, Comprehensive Heart Failure Center, University Clinic Würzburg, Am Schwarzenberg 15, 9708 Würzburg, Germany; (V.S.); (E.B.); (J.D.)
| | - Edoardo Bertero
- Department of Translational Science, Comprehensive Heart Failure Center, University Clinic Würzburg, Am Schwarzenberg 15, 9708 Würzburg, Germany; (V.S.); (E.B.); (J.D.)
| | - Jan Dudek
- Department of Translational Science, Comprehensive Heart Failure Center, University Clinic Würzburg, Am Schwarzenberg 15, 9708 Würzburg, Germany; (V.S.); (E.B.); (J.D.)
| | - Christoph Maack
- Department of Translational Science, Comprehensive Heart Failure Center, University Clinic Würzburg, Am Schwarzenberg 15, 9708 Würzburg, Germany; (V.S.); (E.B.); (J.D.)
| | - Martina Calore
- IMAiA—Institute for Molecular Biology and RNA Technology, Faculty of Health, Universiteitssingel 50, 6229ER Maastricht, The Netherlands;
- Medicine and Life Sciences, Faculty of Science and Engineering, Universiteitssingel 50, 6229ER Maastricht, The Netherlands
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Habich M, Salscheider SL, Riemer J. Cysteine residues in mitochondrial intermembrane space proteins: more than just import. Br J Pharmacol 2018; 176:514-531. [PMID: 30129023 DOI: 10.1111/bph.14480] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 06/20/2018] [Accepted: 06/26/2018] [Indexed: 12/13/2022] Open
Abstract
The intermembrane space (IMS) is a very small mitochondrial sub-compartment with critical relevance for many cellular processes. IMS proteins fulfil important functions in transport of proteins, lipids, metabolites and metal ions, in signalling, in metabolism and in defining the mitochondrial ultrastructure. Our understanding of the IMS proteome has become increasingly refined although we still lack information on the identity and function of many of its proteins. One characteristic of many IMS proteins are conserved cysteines. Different post-translational modifications of these cysteine residues can have critical roles in protein function, localization and/or stability. The close localization to different ROS-producing enzyme systems, a dedicated machinery for oxidative protein folding, and a unique equipment with antioxidative systems, render the careful balancing of the redox and modification states of the cysteine residues, a major challenge in the IMS. In this review, we discuss different functions of human IMS proteins, the involvement of cysteine residues in these functions, the consequences of cysteine modifications and the consequences of cysteine mutations or defects in the machinery for disulfide bond formation in terms of human health. LINKED ARTICLES: This article is part of a themed section on Chemical Biology of Reactive Sulfur Species. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.4/issuetoc.
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Affiliation(s)
- Markus Habich
- Department of Chemistry, Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | - Silja Lucia Salscheider
- Department of Chemistry, Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | - Jan Riemer
- Department of Chemistry, Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
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Vogt S, Ruppert V, Pankuweit S, Paletta JPJ, Rhiel A, Weber P, Irqsusi M, Cybulski P, Ramzan R. Myocardial insufficiency is related to reduced subunit 4 content of cytochrome c oxidase. J Cardiothorac Surg 2018; 13:95. [PMID: 30223867 PMCID: PMC6142347 DOI: 10.1186/s13019-018-0785-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 09/11/2018] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Treatment of heart failure remains one of the most challenging task for intensive care medicine, cardiology and cardiac surgery. New options and better indicators are always required. Understanding the basic mechanisms underlying heart failure promote the development of adjusted therapy e.g. assist devices and monitoring of recovery. If cardiac failure is related to compromised cellular respiration of the heart, remains unclear. Myocardial respiration depends on Cytochrome c- Oxidase (CytOx) activity representing the rate limiting step for the mitochondrial respiratory chain. The enzymatic activity as well as mRNA expression of enzyme's mitochondrial encoded catalytic subunit 2, nuclear encoded regulatory subunit 4 and protein contents were studied in biopsies of cardiac patients suffering from myocardial insufficiency and dilated cardiomyopathy (DCM). METHODS Fifty-four patients were enrolled in the study and underwent coronary angiography. Thirty male patients (mean age: 45 +/- 15 yrs.) had a reduced ejection fraction (EF) 35 ± 12% below 45% and a left ventricular end diastolic diameter (LVEDD) of 71 ± 10 mm bigger than 56 mm. They were diagnosed as having idiopathic dilated cardiomyopathy (DCM) without coronary heart disease and NYHA-class 3 and 4. Additionally, 24 male patients (mean age: 52 +/- 11 yrs.) after exclusion of secondary cardiomyopathies, coronary artery or valve disease, served as control (EF: 68 ± 7, LVEDD: 51 ± 7 mm). Total RNA was extracted from two biopsies of each person. Real-time PCR analysis was performed with specific primers followed by a melt curve analysis. Corresponding protein expression in the tissue was studied with immune-histochemistry while enzymatic activity was evaluated by spectroscopy. RESULTS Gene and protein expression analysis of patients showed a significant decrease of subunit 4 (1.1 vs. 0.6, p < 0.001; 7.7 ± 3.1% vs. 2.8 ± 1.4%, p < 0.0001) but no differences in subunit 2. Correlations were found between reduced subunit 2 expression, low EF (r = 0.766, p < 0.00045) and increased LVEDD (r = 0.492, p < 0.0068). In case of DCM less subunit 4 expression and reduced shortening fraction (r = 0.524, p < 0.017) was found, but enzymatic activity was higher (0.08 ± 0.06 vs. 0.26 ± 0.08 U/mg, p < 0.001) although myocardial oxygen consumption continued to the same extent. CONCLUSION In case of myocardial insufficiency and DCM, decreased expression of COX 4 results in an impaired CytOx activity. Higher enzymatic activity but equal oxygen consumption contribute to the pathophysiology of the myocardial insufficiency and appears as an indicator of oxidative stress. This kind of dysregulation should be in the focus for the development of diagnostic and therapy procedures.
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Affiliation(s)
- Sebastian Vogt
- Cardiovascular Research Laboratories at the Biochemical Pharmacological Center, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany. .,Heart Surgery, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany.
| | - Volker Ruppert
- Department for Internal Medicine- Cardiology, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany
| | - Sabine Pankuweit
- Department for Internal Medicine- Cardiology, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany
| | - Jürgen P J Paletta
- Clinic for Orthopedics and Rheumatology, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany
| | - Annika Rhiel
- Cardiovascular Research Laboratories at the Biochemical Pharmacological Center, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany
| | - Petra Weber
- Cardiovascular Research Laboratories at the Biochemical Pharmacological Center, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany
| | - Marc Irqsusi
- Heart Surgery, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany
| | - Pia Cybulski
- Cardiovascular Research Laboratories at the Biochemical Pharmacological Center, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany
| | - Rabia Ramzan
- Cardiovascular Research Laboratories at the Biochemical Pharmacological Center, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany.,Heart Surgery, Philipps-University Marburg and Universitätsklinikum Gießen and Marburg GmbH, Marburg, Germany
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Human diseases associated with defects in assembly of OXPHOS complexes. Essays Biochem 2018; 62:271-286. [PMID: 30030362 PMCID: PMC6056716 DOI: 10.1042/ebc20170099] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/13/2018] [Accepted: 05/02/2018] [Indexed: 02/02/2023]
Abstract
The structural biogenesis and functional proficiency of the multiheteromeric complexes forming the mitochondrial oxidative phosphorylation system (OXPHOS) require the concerted action of a number of chaperones and other assembly factors, most of which are specific for each complex. Mutations in a large number of these assembly factors are responsible for mitochondrial disorders, in most cases of infantile onset, typically characterized by biochemical defects of single specific complexes. In fact, pathogenic mutations in complex-specific assembly factors outnumber, in many cases, the repertoire of mutations found in structural subunits of specific complexes. The identification of patients with specific defects in assembly factors has provided an important contribution to the nosological characterization of mitochondrial disorders, and has also been a crucial means to identify a huge number of these proteins in humans, which play an essential role in mitochondrial bioenergetics. The wide use of next generation sequencing (NGS) has led to and will allow the identifcation of additional components of the assembly machinery of individual complexes, mutations of which are responsible for human disorders. The functional studies on patients' specimens, together with the creation and characterization of in vivo models, are fundamental to better understand the mechanisms of each of them. A new chapter in this field will be, in the near future, the discovery of mechanisms and actions underlying the formation of supercomplexes, molecular structures formed by the physical, and possibly functional, interaction of some of the individual respiratory complexes, particularly complex I (CI), III (CIII), and IV (CIV).
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Dubinski AF, Camasta R, Soule TGB, Reed BH, Glerum DM. Consequences of cytochrome c oxidase assembly defects for the yeast stationary phase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:445-458. [PMID: 29567354 DOI: 10.1016/j.bbabio.2018.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 03/13/2018] [Accepted: 03/19/2018] [Indexed: 12/24/2022]
Abstract
The assembly of cytochrome c oxidase (COX) is essential for a functional mitochondrial respiratory chain, although the consequences of a loss of assembled COX at yeast stationary phase, an excellent model for terminally differentiated cells in humans, remain largely unexamined. In this study, we show that a wild-type respiratory competent yeast strain at stationary phase is characterized by a decreased oxidative capacity, as seen by a reduction in the amount of assembled COX and by a decrease in protein levels of several COX assembly factors. In contrast, loss of assembled COX results in the decreased abundance of many mitochondrial proteins at stationary phase, which is likely due to decreased membrane potential and changes in mitophagy. In addition to an altered mitochondrial proteome, COX assembly mutants display unexpected changes in markers of cellular oxidative stress at stationary phase. Our results suggest that mitochondria may not be a major source of reactive oxygen species at stationary phase in cells lacking an intact respiratory chain.
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Affiliation(s)
- Alicia F Dubinski
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Raffaele Camasta
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Tyler G B Soule
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Bruce H Reed
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - D Moira Glerum
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada; Waterloo Institute of Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
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Bhattacharjee A, Chakraborty K, Shukla A. Cellular copper homeostasis: current concepts on its interplay with glutathione homeostasis and its implication in physiology and human diseases. Metallomics 2018; 9:1376-1388. [PMID: 28675215 DOI: 10.1039/c7mt00066a] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Copper is a trace element essential for almost all living organisms. But the level of intracellular copper needs to be tightly regulated. Dysregulation of cellular copper homeostasis leading to various diseases demonstrates the importance of this tight regulation. Copper homeostasis is regulated not only within the cell but also within individual intracellular compartments. Inactivation of export machinery results in excess copper being redistributed into various intracellular organelles. Recent evidence suggests the involvement of glutathione in playing an important role in regulating copper entry and intracellular copper homeostasis. Therefore interplay of both homeostases might play an important role within the cell. Similar to copper, glutathione balance is tightly regulated within individual cellular compartments. This review explores the existing literature on the role of glutathione in regulating cellular copper homeostasis. On the one hand, interplay of glutathione and copper homeostasis performs an important role in normal physiological processes, for example neuronal differentiation. On the other hand, perturbation of the interplay might play a key role in the pathogenesis of copper homeostasis disorders.
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Abstract
PURPOSE OF REVIEW Mitochondrial disorders are an increasingly recognized cause of heart dysfunction, with the primary manifestations being cardiomyopathy and conduction defects. This review focuses on the complex genetics of mitochondrial disease and recently discovered conditions that affect mitochondrial function. RECENT FINDINGS Next-generation sequencing techniques, especially whole-exome sequencing, have led to the discovery of a number of conditions that cause mitochondrial dysfunction and subsequent cardiac abnormalities. Nuclear DNA defects are the main cause of mitochondrial disease in children, with disease pathogenesis being related to either abnormalities in specific mitochondrial electron transport chain subunits or in proteins related to subunit or mitochondrial DNA maintenance, mitochondrial protein translation, lipid bilayer structure, or other aspects of mitochondrial function. SUMMARY Currently, symptomatic therapy using standard medications targeting relief of complications is the primary approach to treatment. There are no US Food and Drug Administration-approved therapies for the specific treatment of mitochondrial disease. However, on the basis of recent advances in understanding of the pathophysiology of these complex disorders, various novel approaches are either in clinical trials or in development.
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Affiliation(s)
- Gregory M Enns
- Department of Pediatrics, Stanford University, Stanford, California, USA
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Jett KA, Leary SC. Building the Cu A site of cytochrome c oxidase: A complicated, redox-dependent process driven by a surprisingly large complement of accessory proteins. J Biol Chem 2017; 293:4644-4652. [PMID: 28972150 DOI: 10.1074/jbc.r117.816132] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome c oxidase (COX) was initially purified more than 70 years ago. A tremendous amount of insight into its structure and function has since been gleaned from biochemical, biophysical, genetic, and molecular studies. As a result, we now appreciate that COX relies on its redox-active metal centers (heme a and a3, CuA and CuB) to reduce oxygen and pump protons in a reaction essential for most eukaryotic life. Questions persist, however, about how individual structural subunits are assembled into a functional holoenzyme. Here, we focus on what is known and what remains to be learned about the accessory proteins that facilitate CuA site maturation.
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Affiliation(s)
- Kimberly A Jett
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Scot C Leary
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
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Phadke R. Myopathology of Adult and Paediatric Mitochondrial Diseases. J Clin Med 2017; 6:jcm6070064. [PMID: 28677615 PMCID: PMC5532572 DOI: 10.3390/jcm6070064] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 06/21/2017] [Accepted: 06/28/2017] [Indexed: 01/09/2023] Open
Abstract
Mitochondria are dynamic organelles ubiquitously present in nucleated eukaryotic cells, subserving multiple metabolic functions, including cellular ATP generation by oxidative phosphorylation (OXPHOS). The OXPHOS machinery comprises five transmembrane respiratory chain enzyme complexes (RC). Defective OXPHOS gives rise to mitochondrial diseases (mtD). The incredible phenotypic and genetic diversity of mtD can be attributed at least in part to the RC dual genetic control (nuclear DNA (nDNA) and mitochondrial DNA (mtDNA)) and the complex interaction between the two genomes. Despite the increasing use of next-generation-sequencing (NGS) and various omics platforms in unravelling novel mtD genes and pathomechanisms, current clinical practice for investigating mtD essentially involves a multipronged approach including clinical assessment, metabolic screening, imaging, pathological, biochemical and functional testing to guide molecular genetic analysis. This review addresses the broad muscle pathology landscape including genotype–phenotype correlations in adult and paediatric mtD, the role of immunodiagnostics in understanding some of the pathomechanisms underpinning the canonical features of mtD, and recent diagnostic advances in the field.
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Affiliation(s)
- Rahul Phadke
- Division of Neuropathology, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, London WC1N 3BG, UK.
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
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Mutated PET117 causes complex IV deficiency and is associated with neurodevelopmental regression and medulla oblongata lesions. Hum Genet 2017; 136:759-769. [PMID: 28386624 PMCID: PMC5429353 DOI: 10.1007/s00439-017-1794-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/31/2017] [Indexed: 10/30/2022]
Abstract
The genetic basis of the many progressive, multi systemic, mitochondrial diseases that cause a lack of cellular ATP production is heterogeneous, with defects found both in the mitochondrial genome as well as in the nuclear genome. Many different mutations have been found in the genes encoding subunits of the enzyme complexes of the oxidative phosphorylation system. In addition, mutations in genes encoding proteins involved in the assembly of these complexes are known to cause mitochondrial disorders. Here we describe two sisters with a mitochondrial disease characterized by lesions in the medulla oblongata, as demonstrated by brain magnetic resonance imaging, and an isolated complex IV deficiency and reduced levels of individual complex IV subunits. Whole exome sequencing revealed a homozygous nonsense mutation resulting in a premature stop codon in the gene encoding Pet117, a small protein that has previously been predicted to be a complex IV assembly factor. PET117 has not been identified as a mitochondrial disease gene before. Lentiviral complementation of patient fibroblasts with wild-type PET117 restored the complex IV deficiency, proving that the gene defect is responsible for the complex IV deficiency in the patients, and indicating a pivotal role of this protein in the proper functioning of complex IV. Although previous studies had suggested a possible role of this protein in the insertion of copper into complex IV, studies in patient fibroblasts could not confirm this. This case presentation thus implicates mutations in PET117 as a novel cause of mitochondrial disease.
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Baertling F, Al-Murshedi F, Sánchez-Caballero L, Al-Senaidi K, Joshi NP, Venselaar H, van den Brand MAM, Nijtmans LGJ, Rodenburg RJT. Mutation in mitochondrial complex IV subunit COX5A causes pulmonary arterial hypertension, lactic acidemia, and failure to thrive. Hum Mutat 2017; 38:692-703. [DOI: 10.1002/humu.23210] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 02/14/2017] [Accepted: 02/25/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Fabian Baertling
- Department of Pediatrics; Radboud Centre for Mitochondrial Medicine; Radboud University Medical Centre; Nijmegen The Netherlands
- Department of General Pediatrics, Neonatology and Pediatric Cardiology; University Children's Hospital Duesseldorf; Heinrich Heine University; Düsseldorf Germany
| | - Fathiya Al-Murshedi
- Genetic and Developmental Medicine Clinic; Department of Genetics; Sultan Qaboos University Hospital; Sultan Qaboos University; Muscat Oman
| | - Laura Sánchez-Caballero
- Department of Pediatrics; Radboud Centre for Mitochondrial Medicine; Radboud University Medical Centre; Nijmegen The Netherlands
| | - Khalfan Al-Senaidi
- Pediatric Cardiology Unit; Department of Child Health; Sultan Qaboos University Hospital; Sultan Qaboos University; Muscat Oman
| | - Niranjan P Joshi
- Pediatric Cardiology Unit; Department of Child Health; Sultan Qaboos University Hospital; Sultan Qaboos University; Muscat Oman
| | - Hanka Venselaar
- Centre for Molecular and Biomolecular Informatics; Radboud University; Nijmegen The Netherlands
| | - Mariël AM van den Brand
- Department of Pediatrics; Radboud Centre for Mitochondrial Medicine; Radboud University Medical Centre; Nijmegen The Netherlands
| | - Leo GJ Nijtmans
- Department of Pediatrics; Radboud Centre for Mitochondrial Medicine; Radboud University Medical Centre; Nijmegen The Netherlands
| | - Richard JT Rodenburg
- Department of Pediatrics; Radboud Centre for Mitochondrial Medicine; Radboud University Medical Centre; Nijmegen The Netherlands
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32
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Alston CL, Rocha MC, Lax NZ, Turnbull DM, Taylor RW. The genetics and pathology of mitochondrial disease. J Pathol 2016; 241:236-250. [PMID: 27659608 PMCID: PMC5215404 DOI: 10.1002/path.4809] [Citation(s) in RCA: 263] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/15/2016] [Accepted: 09/16/2016] [Indexed: 12/30/2022]
Abstract
Mitochondria are double-membrane-bound organelles that are present in all nucleated eukaryotic cells and are responsible for the production of cellular energy in the form of ATP. Mitochondrial function is under dual genetic control - the 16.6-kb mitochondrial genome, with only 37 genes, and the nuclear genome, which encodes the remaining ∼1300 proteins of the mitoproteome. Mitochondrial dysfunction can arise because of defects in either mitochondrial DNA or nuclear mitochondrial genes, and can present in childhood or adulthood in association with vast clinical heterogeneity, with symptoms affecting a single organ or tissue, or multisystem involvement. There is no cure for mitochondrial disease for the vast majority of mitochondrial disease patients, and a genetic diagnosis is therefore crucial for genetic counselling and recurrence risk calculation, and can impact on the clinical management of affected patients. Next-generation sequencing strategies are proving pivotal in the discovery of new disease genes and the diagnosis of clinically affected patients; mutations in >250 genes have now been shown to cause mitochondrial disease, and the biochemical, histochemical, immunocytochemical and neuropathological characterization of these patients has led to improved diagnostic testing strategies and novel diagnostic techniques. This review focuses on the current genetic landscape associated with mitochondrial disease, before focusing on advances in studying associated mitochondrial pathology in two, clinically relevant organs - skeletal muscle and brain. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Mariana C Rocha
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Nichola Z Lax
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
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Rak M, Bénit P, Chrétien D, Bouchereau J, Schiff M, El-Khoury R, Tzagoloff A, Rustin P. Mitochondrial cytochrome c oxidase deficiency. Clin Sci (Lond) 2016; 130:393-407. [PMID: 26846578 PMCID: PMC4948581 DOI: 10.1042/cs20150707] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
As with other mitochondrial respiratory chain components, marked clinical and genetic heterogeneity is observed in patients with a cytochrome c oxidase deficiency. This constitutes a considerable diagnostic challenge and raises a number of puzzling questions. So far, pathological mutations have been reported in more than 30 genes, in both mitochondrial and nuclear DNA, affecting either structural subunits of the enzyme or proteins involved in its biogenesis. In this review, we discuss the possible causes of the discrepancy between the spectacular advances made in the identification of the molecular bases of cytochrome oxidase deficiency and the lack of any efficient treatment in diseases resulting from such deficiencies. This brings back many unsolved questions related to the frequent delay of clinical manifestation, variable course and severity, and tissue-involvement often associated with these diseases. In this context, we stress the importance of studying different models of these diseases, but also discuss the limitations encountered in most available disease models. In the future, with the possible exception of replacement therapy using genes, cells or organs, a better understanding of underlying mechanism(s) of these mitochondrial diseases is presumably required to develop efficient therapy.
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Affiliation(s)
- Malgorzata Rak
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France
| | - Paule Bénit
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France
| | - Dominique Chrétien
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France
| | - Juliette Bouchereau
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France
| | - Manuel Schiff
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Reference Center for Inherited Metabolic Diseases, Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris, 48 Boulevard Sérurier, 75019 Paris, France
| | - Riyad El-Khoury
- American University of Beirut Medical Center, Department of Pathology and Laboratory Medicine, Cairo Street, Hamra, Beirut, Lebanon
| | - Alexander Tzagoloff
- Biological Sciences Department, Columbia University, New York, NY 10027, U.S.A
| | - Pierre Rustin
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France
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Modjtahedi N, Tokatlidis K, Dessen P, Kroemer G. Mitochondrial Proteins Containing Coiled-Coil-Helix-Coiled-Coil-Helix (CHCH) Domains in Health and Disease. Trends Biochem Sci 2016; 41:245-260. [PMID: 26782138 DOI: 10.1016/j.tibs.2015.12.004] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 12/08/2015] [Accepted: 12/15/2015] [Indexed: 11/19/2022]
Abstract
Members of the coiled-coil-helix-coiled-coil-helix (CHCH) domain-containing protein family that carry (CX9C) type motifs are imported into the mitochondrion with the help of the disulfide relay-dependent MIA import pathway. These evolutionarily conserved proteins are emerging as new cellular factors that control mitochondrial respiration, redox regulation, lipid homeostasis, and membrane ultrastructure and dynamics. We discuss recent insights on the activity of known (CX9C) motif-carrying proteins in mammals and review current data implicating the Mia40/CHCHD4 import machinery in the regulation of their mitochondrial import. Recent findings and the identification of disease-associated mutations in specific (CX9C) motif-carrying proteins have highlighted members of this family of proteins as potential therapeutic targets in a variety of human disorders.
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Affiliation(s)
- Nazanine Modjtahedi
- Institut National de la Santé et de la Recherche Médicale, U1030, Villejuif, France; Gustave Roussy Cancer Campus, Villejuif, France; Faculty of Medicine, Université Paris-Saclay, Kremlin-Bicêtre, France.
| | - Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Philippe Dessen
- Gustave Roussy Cancer Campus, Villejuif, France; Faculty of Medicine, Université Paris-Saclay, Kremlin-Bicêtre, France; Groupe bioinformatique Gustave Roussy Cancer Campus, Villejuif, France
| | - Guido Kroemer
- Equipe 11 Labellisée Ligue Nationale Contre le Cancer, Centre de Recherche des Cordeliers, Paris, France; Institut National de la Santé et de la Recherche Médicale, U1138, Paris, France; Metabolomics and Cell Biology Platforms, Gustave Roussy Cancer Campus, Villejuif, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Université Pierre et Marie Curie, Paris, France; Pôle de Biologie, Hôpital Européen Georges Pompidou, Paris, AP-HP, France; Karolinska Institute, Department of Women's and Children's Health, Karolinska University Hospital, Stockholm, Sweden.
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Kovářová N, Pecina P, Nůsková H, Vrbacký M, Zeviani M, Mráček T, Viscomi C, Houštěk J. Tissue- and species-specific differences in cytochrome c oxidase assembly induced by SURF1 defects. Biochim Biophys Acta Mol Basis Dis 2016; 1862:705-715. [PMID: 26804654 PMCID: PMC4793088 DOI: 10.1016/j.bbadis.2016.01.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 12/08/2015] [Accepted: 01/08/2016] [Indexed: 12/17/2022]
Abstract
Mitochondrial protein SURF1 is a specific assembly factor of cytochrome c oxidase (COX), but its function is poorly understood. SURF1 gene mutations cause a severe COX deficiency manifesting as the Leigh syndrome in humans, whereas in mice SURF1−/− knockout leads only to a mild COX defect. We used SURF1−/− mouse model for detailed analysis of disturbed COX assembly and COX ability to incorporate into respiratory supercomplexes (SCs) in different tissues and fibroblasts. Furthermore, we compared fibroblasts from SURF1−/− mouse and SURF1 patients to reveal interspecies differences in kinetics of COX biogenesis using 2D electrophoresis, immunodetection, arrest of mitochondrial proteosynthesis and pulse-chase metabolic labeling. The crucial differences observed are an accumulation of abundant COX1 assembly intermediates, low content of COX monomer and preferential recruitment of COX into I–III2–IVn SCs in SURF1 patient fibroblasts, whereas SURF1−/− mouse fibroblasts were characterized by low content of COX1 assembly intermediates and milder decrease in COX monomer, which appeared more stable. This pattern was even less pronounced in SURF1−/− mouse liver and brain. Both the control and SURF1−/− mice revealed only negligible formation of the I–III2–IVn SCs and marked tissue differences in the contents of COX dimer and III2–IV SCs, also less noticeable in liver and brain than in heart and muscle. Our studies support the view that COX assembly is much more dependent on SURF1 in humans than in mice. We also demonstrate markedly lower ability of mouse COX to form I–III2–IVn supercomplexes, pointing to tissue-specific and species-specific differences in COX biogenesis. In SURF1 −/− mouse the decrease of COX amount and activity was tissue/cell specific. Assembly kinetics proceeded to the level of stable COX monomer in SURF1 −/− mouse. COX assembly intermediates were faster degraded/depleted in time in SURF1 −/− mouse. COX was preferentially recruited in supercomplex I–III2–IV1 in SURF1 patient cells. Newly synthesized COX monomer was unstable and rapidly degraded in SURF1 patient.
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Affiliation(s)
- Nikola Kovářová
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, Czech Republic
| | - Petr Pecina
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, Czech Republic
| | - Hana Nůsková
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, Czech Republic
| | - Marek Vrbacký
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, Czech Republic
| | - Massimo Zeviani
- Molecular Neurogenetics Unit, Instituto Neurologico "C. Besta", via Temolo 4, 20126 Milan, Italy; MRC-Mitochondrial Biology Unit, Wellcome Trust MRC Bldg, Addenbrookes Hospital Hills Rd, Cambridge CB2 0XY, UK
| | - Tomáš Mráček
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, Czech Republic
| | - Carlo Viscomi
- MRC-Mitochondrial Biology Unit, Wellcome Trust MRC Bldg, Addenbrookes Hospital Hills Rd, Cambridge CB2 0XY, UK
| | - Josef Houštěk
- Institute of Physiology of the Czech Academy of Sciences, Vídeňská 1083, Prague, Czech Republic.
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Ghosh A, Pratt AT, Soma S, Theriault SG, Griffin AT, Trivedi PP, Gohil VM. Mitochondrial disease genes COA6, COX6B and SCO2 have overlapping roles in COX2 biogenesis. Hum Mol Genet 2015; 25:660-71. [PMID: 26669719 DOI: 10.1093/hmg/ddv503] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 12/07/2015] [Indexed: 01/19/2023] Open
Abstract
Biogenesis of cytochrome c oxidase (CcO), the terminal enzyme of the mitochondrial respiratory chain, is a complex process facilitated by several assembly factors. Pathogenic mutations were recently reported in one such assembly factor, COA6, and our previous work linked Coa6 function to mitochondrial copper metabolism and expression of Cox2, a copper-containing subunit of CcO. However, the precise role of Coa6 in Cox2 biogenesis remained unknown. Here we show that yeast Coa6 is an orthologue of human COA6, and like Cox2, is regulated by copper availability, further implicating it in copper delivery to Cox2. In order to place Coa6 in the Cox2 copper delivery pathway, we performed a comprehensive genetic epistasis analysis in the yeast Saccharomyces cerevisiae and found that simultaneous deletion of Coa6 and Sco2, a mitochondrial copper metallochaperone, or Coa6 and Cox12/COX6B, a structural subunit of CcO, completely abrogates Cox2 biogenesis. Unlike Coa6 deficient cells, copper supplementation fails to rescue Cox2 levels of these double mutants. Overexpression of Cox12 or Sco proteins partially rescues the coa6Δ phenotype, suggesting their overlapping but non-redundant roles in copper delivery to Cox2. These genetic data are strongly corroborated by biochemical studies demonstrating physical interactions between Coa6, Cox2, Cox12 and Sco proteins. Furthermore, we show that patient mutations in Coa6 disrupt Coa6-Cox2 interaction, providing the biochemical basis for disease pathogenesis. Taken together, these results place COA6 in the copper delivery pathway to CcO and, surprisingly, link it to a previously unidentified function of CcO subunit Cox12 in Cox2 biogenesis.
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Affiliation(s)
- Alok Ghosh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Anthony T Pratt
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Shivatheja Soma
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Sarah G Theriault
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Aaron T Griffin
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Prachi P Trivedi
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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Brunel-Guitton C, Levtova A, Sasarman F. Mitochondrial Diseases and Cardiomyopathies. Can J Cardiol 2015; 31:1360-76. [DOI: 10.1016/j.cjca.2015.08.017] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/21/2015] [Accepted: 08/21/2015] [Indexed: 12/31/2022] Open
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Menazza S, Aponte A, Sun J, Gucek M, Steenbergen C, Murphy E. Molecular Signature of Nitroso-Redox Balance in Idiopathic Dilated Cardiomyopathies. J Am Heart Assoc 2015; 4:e002251. [PMID: 26396203 PMCID: PMC4599508 DOI: 10.1161/jaha.115.002251] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 08/19/2015] [Indexed: 12/28/2022]
Abstract
BACKGROUND Idiopathic dilated cardiomyopathy is one of the most common types of cardiomyopathy. It has been proposed that an increase in oxidative stress in heart failure leads to a decrease in nitric oxide signaling, leading to impaired nitroso-redox signaling. To test this hypothesis, we investigated the occurrence of protein S-nitrosylation (SNO) and oxidation in biopsies from explanted dilated cardiomyopathy and nonfailing donor male and female human hearts. METHODS AND RESULTS Redox-based resin-assisted capture for oxidation and SNO proteomic analysis was used to measure protein oxidation and SNO, respectively. In addition, 2-dimensional difference gel electrophoresis using maleimide sulfhydryl-reactive fluors was used to identify the SNO proteins. Protein oxidation increased in dilated cardiomyopathy biopsies in comparison with those from healthy donors. Interestingly, we did not find a consistent decrease in SNO in failing hearts; we found that some proteins showed an increase in SNO and others showed a decrease, and there were sex-specific differences in the response. We found 10 proteins with a significant decrease in SNO and 4 proteins with an increase in SNO in failing female hearts. Comparing nonfailing and failing male hearts, we found 9 proteins with a significant decrease and 12 proteins with a significant increase. We also found an increase in S-glutathionylation of endothelial nitric oxide synthase in failing female versus male hearts, suggesting an increase in uncoupled nitric oxide synthase in female hearts. CONCLUSION These findings highlight the importance of nitroso-redox signaling in both physiological and pathological conditions, suggesting a potential target to treat heart failure.
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Affiliation(s)
- Sara Menazza
- Systems Biology Center, National Heart Lung and Blood Institute, National Institutes of HealthBethesda, MD
| | - Angel Aponte
- Proteomic Core Facility, National Heart Lung and Blood Institute, National Institutes of HealthBethesda, MD
| | - Junhui Sun
- Systems Biology Center, National Heart Lung and Blood Institute, National Institutes of HealthBethesda, MD
| | - Marjan Gucek
- Proteomic Core Facility, National Heart Lung and Blood Institute, National Institutes of HealthBethesda, MD
| | | | - Elizabeth Murphy
- Systems Biology Center, National Heart Lung and Blood Institute, National Institutes of HealthBethesda, MD
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Dennerlein S, Oeljeklaus S, Jans D, Hellwig C, Bareth B, Jakobs S, Deckers M, Warscheid B, Rehling P. MITRAC7 Acts as a COX1-Specific Chaperone and Reveals a Checkpoint during Cytochrome c Oxidase Assembly. Cell Rep 2015; 12:1644-55. [PMID: 26321642 DOI: 10.1016/j.celrep.2015.08.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 07/16/2015] [Accepted: 08/03/2015] [Indexed: 11/29/2022] Open
Abstract
Cytochrome c oxidase, the terminal enzyme of the respiratory chain, is assembled from mitochondria- and nuclear-encoded subunits. The MITRAC complex represents the central assembly intermediate during this process as it receives imported subunits and regulates mitochondrial translation of COX1 mRNA. The molecular processes that promote and regulate the progression of assembly downstream of MITRAC are still unknown. Here, we identify MITRAC7 as a constituent of a late form of MITRAC and as a COX1-specific chaperone. MITRAC7 is required for cytochrome c oxidase biogenesis. Surprisingly, loss of MITRAC7 or an increase in its amount causes selective cytochrome c oxidase deficiency in human cells. We demonstrate that increased MITRAC7 levels stabilize and trap COX1 in MITRAC, blocking progression in the assembly process. In contrast, MITRAC7 deficiency leads to turnover of newly synthesized COX1. Accordingly, MITRAC7 affects the biogenesis pathway by stabilizing newly synthesized COX1 in assembly intermediates, concomitantly preventing turnover.
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Affiliation(s)
- Sven Dennerlein
- Department of Cellular Biochemistry, University of Göttingen, 37073 Göttingen, Germany
| | - Silke Oeljeklaus
- Department of Biochemistry and Functional Proteomics, Faculty of Biology and BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Daniel Jans
- Department of NanoBiophotonics, Mitochondrial Structure and Dynamics Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Christin Hellwig
- Department of Cellular Biochemistry, University of Göttingen, 37073 Göttingen, Germany
| | - Bettina Bareth
- Department of Cellular Biochemistry, University of Göttingen, 37073 Göttingen, Germany
| | - Stefan Jakobs
- Department of NanoBiophotonics, Mitochondrial Structure and Dynamics Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany; Department of Neurology, University of Göttingen, 37073 Göttingen, Germany
| | - Markus Deckers
- Department of Cellular Biochemistry, University of Göttingen, 37073 Göttingen, Germany
| | - Bettina Warscheid
- Department of Biochemistry and Functional Proteomics, Faculty of Biology and BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Peter Rehling
- Department of Cellular Biochemistry, University of Göttingen, 37073 Göttingen, Germany; Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
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40
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Wortmann SB, Koolen DA, Smeitink JA, van den Heuvel L, Rodenburg RJ. Whole exome sequencing of suspected mitochondrial patients in clinical practice. J Inherit Metab Dis 2015; 38:437-43. [PMID: 25735936 PMCID: PMC4432107 DOI: 10.1007/s10545-015-9823-y] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 12/04/2014] [Accepted: 02/06/2015] [Indexed: 11/25/2022]
Abstract
Mitochondrial disorders are characterized by a broad clinical spectrum. Identical clinical signs and symptoms can be caused by mutations in different mitochondrial or nuclear genes. Vice versa, the same mutation can lead to different phenotypes. Genetic syndromes and neuromuscular disorders mimicking mitochondrial disorders further complicate the diagnostic process. Whole exome sequencing (WES) is the state of the art next generation sequencing technique to identify genetic defects in mitochondrial disorders. Until recently it has mainly been used as a research tool. In this study, the use of WES in routine diagnostics is described. The WES data of 109 patients, referred under the suspicion of a mitochondrial disorder, were examined in two steps. First, the data were filtered using a virtual gene panel of genes known to be associated with mitochondrial disease. If negative, the entire exome was examined. A molecular diagnosis was achieved in 39% of the heterogeneous cohort, and in 57% of the subgroup of 42 patients with the highest suspicion for a mitochondrial disease. In addition to mutations in genes known to be associated with mitochondrial disorders (e.g. TUFM, MTFMT, FBXL4), in the subgroup of patients with the lowest suspicion for a mitochondrial disorder we found mutations in several genes associated with neuromuscular disorders (e.g. SEPN1, ACTA1) and genetic syndrome (e.g. SETBP1, ARID1B). Our results show that WES technology has been successfully implemented as a state-of-the-art, molecular diagnostic test for mitochondrial disorders as well as for the mimicking disorders in daily clinical practice. It also illustrates that clinical and biochemical phenotyping is essential for successful application of WES to diagnose individual patients.
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Affiliation(s)
- Saskia B. Wortmann
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
| | - David A. Koolen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jan A. Smeitink
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Lambert van den Heuvel
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Richard J. Rodenburg
- Department of Pediatrics, Radboudumc, Nijmegen Centre for Mitochondrial Disorders (NCMD), 774 Translational Metabolic Laboratory, P.O Box 9101, 6500 HB Nijmegen, The Netherlands
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41
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Ostergaard E, Weraarpachai W, Ravn K, Born AP, Jønson L, Duno M, Wibrand F, Shoubridge EA, Vissing J. Mutations in COA3 cause isolated complex IV deficiency associated with neuropathy, exercise intolerance, obesity, and short stature. J Med Genet 2015; 52:203-7. [PMID: 25604084 DOI: 10.1136/jmedgenet-2014-102914] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND We investigated a subject with an isolated cytochrome c oxidase (COX) deficiency presenting with an unusual phenotype characterised by neuropathy, exercise intolerance, obesity, and short stature. METHODS AND RESULTS Blue-native polyacrylamide gel electrophoresis (BN-PAGE) analysis showed an almost complete lack of COX assembly in subject fibroblasts, consistent with the very low enzymatic activity, and pulse-labelling mitochondrial translation experiments showed a specific decrease in synthesis of the COX1 subunit, the core catalytic subunit that nucleates assembly of the holoenzyme. Whole exome sequencing identified compound heterozygous mutations (c.199dupC, c.215A>G) in COA3, a small inner membrane COX assembly factor, resulting in a pronounced decrease in the steady-state levels of COA3 protein. Retroviral expression of a wild-type COA3 cDNA completely rescued the COX assembly and mitochondrial translation defects, confirming the pathogenicity of the mutations, and resulted in increased steady-state levels of COX1 in control cells, demonstrating a role for COA3 in the stabilisation of this subunit. COA3 exists in an early COX assembly complex that contains COX1 and other COX assembly factors including COX14 (C12orf62), another single pass transmembrane protein that also plays a role in coupling COX1 synthesis with holoenzyme assembly. Immunoblot analysis showed that COX14 was undetectable in COA3 subject fibroblasts, and that COA3 was undetectable in fibroblasts from a COX14 subject, demonstrating the interdependence of these two COX assembly factors. CONCLUSIONS The mild clinical course in this patient contrasts with nearly all other cases of severe COX assembly defects that are usually fatal early in life, and underscores the marked tissue-specific involvement in mitochondrial diseases.
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Affiliation(s)
- Elsebet Ostergaard
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Woranontee Weraarpachai
- Department of Human Genetics and Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada, Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Kirstine Ravn
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Alfred Peter Born
- Department of Pediatrics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Lars Jønson
- Department of Genomic Medicine, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Morten Duno
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Flemming Wibrand
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Eric A Shoubridge
- Department of Human Genetics and Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - John Vissing
- Department of Neurology and Neuromuscular Research Unit, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark
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42
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Dennerlein S, Rehling P. Human mitochondrial COX1 assembly into cytochrome c oxidase at a glance. J Cell Sci 2015; 128:833-7. [DOI: 10.1242/jcs.161729] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Mitochondria provide the main portion of cellular energy in form of ATP produced by the F1Fo ATP synthase, which uses the electrochemical gradient, generated by the mitochondrial respiratory chain (MRC). In human mitochondria, the MRC is composed of four multisubunit enzyme complexes, with the cytochrome c oxidase (COX, also known as complex IV) as the terminal enzyme. COX comprises 14 structural subunits, of nuclear or mitochondrial origin. Hence, mitochondria are faced with the predicament of organizing and controlling COX assembly with subunits that are synthesized by different translation machineries and that reach the inner membrane by alternative transport routes. An increasing number of COX assembly factors have been identified in recent years. Interestingly, mutations in several of these factors have been associated with human disorders leading to COX deficiency. Recently, studies have provided mechanistic insights into crosstalk between assembly intermediates, import processes and the synthesis of COX subunits in mitochondria, thus linking conceptually separated functions. This Cell Science at a Glance article and the accompanying poster will focus on COX assembly and discuss recent discoveries in the field, the molecular functions of known factors, as well as new players and control mechanisms. Furthermore, these findings will be discussed in the context of human COX-related disorders.
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43
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Baertling F, A M van den Brand M, Hertecant JL, Al-Shamsi A, P van den Heuvel L, Distelmaier F, Mayatepek E, Smeitink JA, Nijtmans LGJ, Rodenburg RJT. Mutations in COA6 cause cytochrome c oxidase deficiency and neonatal hypertrophic cardiomyopathy. Hum Mutat 2014; 36:34-8. [PMID: 25339201 DOI: 10.1002/humu.22715] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 10/16/2014] [Indexed: 01/18/2023]
Abstract
COA6/C1ORF31 is involved in cytochrome c oxidase (complex IV) biogenesis. We present a new pathogenic COA6 variant detected in a patient with neonatal hypertrophic cardiomyopathy and isolated complex IV deficiency. For the first time, clinical details about a COA6-deficient patient are given and patient fibroblasts are functionally characterized: COA6 protein is undetectable and steady-state levels of complex IV and several of its subunits are reduced. The monomeric COX1 assembly intermediate accumulates. Using pulse-chase experiments, we demonstrate an increased turnover of mitochondrial encoded complex IV subunits. Although monomeric complex IV is decreased in patient fibroblasts, the CI/CIII2 /CIVn -supercomplexes remain unaffected. Copper supplementation shows a partial rescue of complex IV deficiency in patient fibroblasts. We conclude that COA6 is required for complex IV subunit stability. Furthermore, the proposed role in the copper delivery pathway to complex IV subunits is substantiated and a therapeutic lead for COA6-deficient patients is provided.
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Affiliation(s)
- Fabian Baertling
- Department of Pediatrics, Nijmegen Centre for Mitochondrial Disorders, Radboud University Medical Centre, GA Nijmegen, The Netherlands; Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Heinrich-Heine-University Duesseldorf, Duesseldorf, Germany
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44
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A truncating PET100 variant causing fatal infantile lactic acidosis and isolated cytochrome c oxidase deficiency. Eur J Hum Genet 2014; 23:935-9. [PMID: 25293719 PMCID: PMC4305338 DOI: 10.1038/ejhg.2014.214] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 07/23/2014] [Accepted: 08/27/2014] [Indexed: 02/04/2023] Open
Abstract
Isolated mitochondrial complex IV (cytochrome c oxidase) deficiency is an important cause of mitochondrial disease in children and adults. It is genetically heterogeneous, given that both mtDNA-encoded and nuclear-encoded gene products contribute to structural components and assembly factors. Pathogenic variants within these proteins are associated with clinical variability ranging from isolated organ involvement to multisystem disease presentations. Defects in more than 10 complex IV assembly factors have been described including a recent Lebanese founder mutation in PET100 in patients presenting with Leigh syndrome. We report the clinical and molecular investigation of a patient with a fatal, neonatal-onset isolated complex IV deficiency associated with multiorgan involvement born to consanguineous, first-cousin British Asian parents. Exome sequencing revealed a homozygous truncating variant (c.142C>T, p.(Gln48*)) in the PET100 gene that results in a complete loss of enzyme activity and assembly of the holocomplex. Our report confirms PET100 mutation as an important cause of isolated complex IV deficiency outside of the Lebanese population, extending the phenotypic spectrum associated with abnormalities within this gene.
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45
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Ghosh A, Trivedi PP, Timbalia SA, Griffin AT, Rahn JJ, Chan SSL, Gohil VM. Copper supplementation restores cytochrome c oxidase assembly defect in a mitochondrial disease model of COA6 deficiency. Hum Mol Genet 2014; 23:3596-606. [PMID: 24549041 DOI: 10.1093/hmg/ddu069] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mitochondrial respiratory chain biogenesis is orchestrated by hundreds of assembly factors, many of which are yet to be discovered. Using an integrative approach based on clues from evolutionary history, protein localization and human genetics, we have identified a conserved mitochondrial protein, C1orf31/COA6, and shown its requirement for respiratory complex IV biogenesis in yeast, zebrafish and human cells. A recent next-generation sequencing study reported potential pathogenic mutations within the evolutionarily conserved Cx₉CxnCx₁₀C motif of COA6, implicating it in mitochondrial disease biology. Using yeast coa6Δ cells, we show that conserved residues in the motif, including the residue mutated in a patient with mitochondrial disease, are essential for COA6 function, thus confirming the pathogenicity of the patient mutation. Furthermore, we show that zebrafish embryos with zfcoa6 knockdown display reduced heart rate and cardiac developmental defects, recapitulating the observed pathology in the human mitochondrial disease patient who died of neonatal hypertrophic cardiomyopathy. The specific requirement of Coa6 for respiratory complex IV biogenesis, its intramitochondrial localization and the presence of the Cx₉CxnCx₁₀C motif suggested a role in mitochondrial copper metabolism. In support of this, we show that exogenous copper supplementation completely rescues respiratory and complex IV assembly defects in yeast coa6Δ cells. Taken together, our results establish an evolutionarily conserved role of Coa6 in complex IV assembly and support a causal role of the COA6 mutation in the human mitochondrial disease patient.
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Affiliation(s)
- Alok Ghosh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA and
| | - Prachi P Trivedi
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA and
| | - Shrishiv A Timbalia
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA and
| | - Aaron T Griffin
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA and
| | - Jennifer J Rahn
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Sherine S L Chan
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA and
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46
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Lim S, Smith K, Stroud D, Compton A, Tucker E, Dasvarma A, Gandolfo L, Marum J, McKenzie M, Peters H, Mowat D, Procopis P, Wilcken B, Christodoulou J, Brown G, Ryan M, Bahlo M, Thorburn D. A founder mutation in PET100 causes isolated complex IV deficiency in Lebanese individuals with Leigh syndrome. Am J Hum Genet 2014; 94:209-22. [PMID: 24462369 DOI: 10.1016/j.ajhg.2013.12.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 12/18/2013] [Indexed: 12/30/2022] Open
Abstract
Leigh syndrome (LS) is a severe neurodegenerative disorder with characteristic bilateral lesions, typically in the brainstem and basal ganglia. It usually presents in infancy and is genetically heterogeneous, but most individuals with mitochondrial complex IV (or cytochrome c oxidase) deficiency have mutations in the biogenesis factor SURF1. We studied eight complex IV-deficient LS individuals from six families of Lebanese origin. They differed from individuals with SURF1 mutations in having seizures as a prominent feature. Complementation analysis suggested they had mutation(s) in the same gene but targeted massively parallel sequencing (MPS) of 1,034 genes encoding known mitochondrial proteins failed to identify a likely candidate. Linkage and haplotype analyses mapped the location of the gene to chromosome 19 and targeted MPS of the linkage region identified a homozygous c.3G>C (p.Met1?) mutation in C19orf79. Abolishing the initiation codon could potentially still allow initiation at a downstream methionine residue but we showed that this would not result in a functional protein. We confirmed that mutation of this gene was causative by lentiviral-mediated phenotypic correction. C19orf79 was recently renamed PET100 and predicted to encode a complex IV biogenesis factor. We showed that it is located in the mitochondrial inner membrane and forms a ∼300 kDa subcomplex with complex IV subunits. Previous proteomic analyses of mitochondria had overlooked PET100 because its small size was below the cutoff for annotating bona fide proteins. The mutation was estimated to have arisen at least 520 years ago, explaining how the families could have different religions and different geographic origins within Lebanon.
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47
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Al-Hasan YM, Pinkas GA, Thompson LP. Prenatal Hypoxia Reduces Mitochondrial Protein Levels and Cytochrome c Oxidase Activity in Offspring Guinea Pig Hearts. Reprod Sci 2014; 21:883-891. [PMID: 24406790 DOI: 10.1177/1933719113518981] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Prenatal hypoxia (HPX) reduces mitochondrial cytochrome c oxidase (CCO and COX) activity in fetal guinea pig (GP) hearts. The aim of this study was to quantify the lasting effects of chronic prenatal HPX on cardiac mitochondrial enzyme activity and protein expression in offspring hearts. Pregnant GPs were exposed to either normoxia (NMX) or HPX (10.5%O2) during the last 14 days of pregnancy. Both NMX and HPX fetuses, delivered vaginally, were housed under NMX conditions until 90 days of age. Total RNA and mitochondrial fractions were isolated from hearts of anesthetized NMX and HPX offspring and showed decreased levels of CCO but not medium-chain acyl dehydrogenase activity, protein levels of nuclear- and mitochondrial-encoded COX4 and COX1, respectively, and messenger RNA expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha, COX5b, and 4.1 compared to NMX controls. Prenatal HPX may alter mitochondrial function in the offspring by disrupting protein expression associated with the respiratory chain.
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Affiliation(s)
- Yazan M Al-Hasan
- Department of Physiology (YMA), University of Maryland, Baltimore, MD, USA Department of Obstetrics, Gynecology and Reproductive Sciences (GAP, LPT), University of Maryland, Baltimore, MD, USA
| | - Gerard A Pinkas
- Department of Physiology (YMA), University of Maryland, Baltimore, MD, USA Department of Obstetrics, Gynecology and Reproductive Sciences (GAP, LPT), University of Maryland, Baltimore, MD, USA
| | - Loren P Thompson
- Department of Physiology (YMA), University of Maryland, Baltimore, MD, USA Department of Obstetrics, Gynecology and Reproductive Sciences (GAP, LPT), University of Maryland, Baltimore, MD, USA
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48
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Kemppainen KK, Rinne J, Sriram A, Lakanmaa M, Zeb A, Tuomela T, Popplestone A, Singh S, Sanz A, Rustin P, Jacobs HT. Expression of alternative oxidase in Drosophila ameliorates diverse phenotypes due to cytochrome oxidase deficiency. Hum Mol Genet 2013; 23:2078-93. [PMID: 24293544 PMCID: PMC3959817 DOI: 10.1093/hmg/ddt601] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Mitochondrial dysfunction is a significant factor in human disease, ranging from systemic disorders of childhood to cardiomyopathy, ischaemia and neurodegeneration. Cytochrome oxidase, the terminal enzyme of the mitochondrial respiratory chain, is a frequent target. Lower eukaryotes possess alternative respiratory-chain enzymes that provide non-proton-translocating bypasses for respiratory complexes I (single-subunit reduced nicotinamide adenine dinucleotide dehydrogenases, e.g. Ndi1 from yeast) or III + IV [alternative oxidase (AOX)], under conditions of respiratory stress or overload. In previous studies, it was shown that transfer of yeast Ndi1 or Ciona intestinalis AOX to Drosophila was able to overcome the lethality produced by toxins or partial knockdown of complex I or IV. Here, we show that AOX can provide a complete or substantial rescue of a range of phenotypes induced by global or tissue-specific knockdown of different cIV subunits, including integral subunits required for catalysis, as well as peripheral subunits required for multimerization and assembly. AOX was also able to overcome the pupal lethality produced by muscle-specific knockdown of subunit CoVb, although the rescued flies were short lived and had a motility defect. cIV knockdown in neurons was not lethal during development but produced a rapidly progressing locomotor and seizure-sensitivity phenotype, which was substantially alleviated by AOX. Expression of Ndi1 exacerbated the neuronal phenotype produced by cIV knockdown. Ndi1 expressed in place of essential cI subunits produced a distinct residual phenotype of delayed development, bang sensitivity and male sterility. These findings confirm the potential utility of alternative respiratory chain enzymes as tools to combat mitochondrial disease, while indicating important limitations thereof.
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Affiliation(s)
- Kia K Kemppainen
- Institute of Biomedical Technology and Tampere University Hospital, University of Tampere, FI-33014 Tampere, Finland
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49
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Ma X, Pietsch J, Wehland M, Schulz H, Saar K, Hübner N, Bauer J, Braun M, Schwarzwälder A, Segerer J, Birlem M, Horn A, Hemmersbach R, Waβer K, Grosse J, Infanger M, Grimm D. Differential gene expression profile and altered cytokine secretion of thyroid cancer cells in space. FASEB J 2013; 28:813-35. [DOI: 10.1096/fj.13-243287] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Xiao Ma
- Institute of BiomedicineDepartment of PharmacologyAarhus UniversityAarhusDenmark
| | - Jessica Pietsch
- Clinic for Plastic, Aesthetic, and Hand Surgery, Otto von Guericke University MagdeburgMagdeburgGermany
| | - Markus Wehland
- Clinic for Plastic, Aesthetic, and Hand Surgery, Otto von Guericke University MagdeburgMagdeburgGermany
| | - Herbert Schulz
- Max Delbrück Center for Molecular MedicineBerlin‐BuchGermany
| | - Katrin Saar
- Max Delbrück Center for Molecular MedicineBerlin‐BuchGermany
| | - Norbert Hübner
- Max Delbrück Center for Molecular MedicineBerlin‐BuchGermany
| | - Johann Bauer
- Max Planck Institute for BiochemistryMartinsriedGermany
| | - Markus Braun
- Institute for Molecular Physiology and Biotechnology of Plants (IMBIO)Gravitational Biology GroupUniversity of BonnBonnGermany
| | - Achim Schwarzwälder
- Life Science, Orbital Systems, and Space Exploration, Astrium/European Aeronautic Defense and Space (EADS)ImmenstaadGermany
| | - Jürgen Segerer
- Life Science, Orbital Systems, and Space Exploration, Astrium/European Aeronautic Defense and Space (EADS)ImmenstaadGermany
| | - Maria Birlem
- Life Science, Orbital Systems, and Space Exploration, Astrium/European Aeronautic Defense and Space (EADS)ImmenstaadGermany
| | - Astrid Horn
- Life Science, Orbital Systems, and Space Exploration, Astrium/European Aeronautic Defense and Space (EADS)ImmenstaadGermany
| | - Ruth Hemmersbach
- Institute of Aerospace MedicineDeutsches Zentrum für Luft‐ und Raumfahrt (DLR)CologneGermany
| | - Kai Waβer
- Institute of Aerospace MedicineDeutsches Zentrum für Luft‐ und Raumfahrt (DLR)CologneGermany
| | - Jirka Grosse
- Department of Nuclear MedicineUniversity of RegensburgRegensburgGermany
| | - Manfred Infanger
- Clinic for Plastic, Aesthetic, and Hand Surgery, Otto von Guericke University MagdeburgMagdeburgGermany
| | - Daniela Grimm
- Institute of BiomedicineDepartment of PharmacologyAarhus UniversityAarhusDenmark
- Clinic for Plastic, Aesthetic, and Hand Surgery, Otto von Guericke University MagdeburgMagdeburgGermany
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50
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Abstract
Mitochondrial diseases involve the respiratory chain, which is under the dual control of nuclear and mitochondrial DNA (mtDNA). The complexity of mitochondrial genetics provides one explanation for the clinical heterogeneity of mitochondrial diseases, but our understanding of disease pathogenesis remains limited. Classification of Mendelian mitochondrial encephalomyopathies has been laborious, but whole-exome sequencing studies have revealed unexpected molecular aetiologies for both typical and atypical mitochondrial disease phenotypes. Mendelian mitochondrial defects can affect five components of mitochondrial biology: subunits of respiratory chain complexes (direct hits); mitochondrial assembly proteins; mtDNA translation; phospholipid composition of the inner mitochondrial membrane; or mitochondrial dynamics. A sixth category-defects of mtDNA maintenance-combines features of Mendelian and mitochondrial genetics. Genetic defects in mitochondrial dynamics are especially important in neurology as they cause optic atrophy, hereditary spastic paraplegia, and Charcot-Marie-Tooth disease. Therapy is inadequate and mostly palliative, but promising new avenues are being identified. Here, we review current knowledge on the genetics and pathogenesis of the six categories of mitochondrial disorders outlined above, focusing on their salient clinical manifestations and highlighting novel clinical entities. An outline of diagnostic clues for the various forms of mitochondrial disease, as well as potential therapeutic strategies, is also discussed.
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