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Antolínez-Fernández Á, Esteban-Ramos P, Fernández-Moreno MÁ, Clemente P. Molecular pathways in mitochondrial disorders due to a defective mitochondrial protein synthesis. Front Cell Dev Biol 2024; 12:1410245. [PMID: 38855161 PMCID: PMC11157125 DOI: 10.3389/fcell.2024.1410245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 05/09/2024] [Indexed: 06/11/2024] Open
Abstract
Mitochondria play a central role in cellular metabolism producing the necessary ATP through oxidative phosphorylation. As a remnant of their prokaryotic past, mitochondria contain their own genome, which encodes 13 subunits of the oxidative phosphorylation system, as well as the tRNAs and rRNAs necessary for their translation in the organelle. Mitochondrial protein synthesis depends on the import of a vast array of nuclear-encoded proteins including the mitochondrial ribosome protein components, translation factors, aminoacyl-tRNA synthetases or assembly factors among others. Cryo-EM studies have improved our understanding of the composition of the mitochondrial ribosome and the factors required for mitochondrial protein synthesis and the advances in next-generation sequencing techniques have allowed for the identification of a growing number of genes involved in mitochondrial pathologies with a defective translation. These disorders are often multisystemic, affecting those tissues with a higher energy demand, and often present with neurodegenerative phenotypes. In this article, we review the known proteins required for mitochondrial translation, the disorders that derive from a defective mitochondrial protein synthesis and the animal models that have been established for their study.
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Affiliation(s)
- Álvaro Antolínez-Fernández
- Instituto de Investigaciones Biomédicas Sols-Morreale (IIBM), Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, Spain
- Departamento de Bioquímica, Universidad Autónoma de Madrid, Madrid, Spain
| | - Paula Esteban-Ramos
- Instituto de Investigaciones Biomédicas Sols-Morreale (IIBM), Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, Spain
- Departamento de Bioquímica, Universidad Autónoma de Madrid, Madrid, Spain
| | - Miguel Ángel Fernández-Moreno
- Instituto de Investigaciones Biomédicas Sols-Morreale (IIBM), Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, Spain
- Departamento de Bioquímica, Universidad Autónoma de Madrid, Madrid, Spain
| | - Paula Clemente
- Instituto de Investigaciones Biomédicas Sols-Morreale (IIBM), Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, Spain
- Departamento de Bioquímica, Universidad Autónoma de Madrid, Madrid, Spain
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Zhong BR, Zhou GF, Song L, Wen QX, Deng XJ, Ma YL, Hu LT, Chen GJ. TUFM is involved in Alzheimer's disease-like pathologies that are associated with ROS. FASEB J 2021; 35:e21445. [PMID: 33774866 DOI: 10.1096/fj.202002461r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/20/2021] [Accepted: 02/01/2021] [Indexed: 12/14/2022]
Abstract
Mitochondrial Tu translation elongation factor (TUFM or EF-Tu) is part of the mitochondrial translation machinery. It is reported that TUFM expression is reduced in the brain of Alzheimer's disease (AD), suggesting that TUFM might play a role in the pathophysiology. In this study, we found that TUFM protein level was decreased in the hippocampus and cortex especially in the aged APP/PS1 mice, an animal model of AD. In HEK cells that stably express full-length human amyloid-β precursor protein (HEK-APP), TUFM knockdown or overexpression increased or reduced the protein levels of β-amyloid protein (Aβ) and β-amyloid converting enzyme 1 (BACE1), respectively. TUFM-mediated reduction of BACE1 was attenuated by translation inhibitor cycloheximide (CHX) or α-[2-[4-(3,4-Dichlorophenyl)-2-thiazolyl]hydrazinylidene]-2-nitro-benzenepropanoic acid (4EGI1), and in cells overexpressing BACE1 constructs deleting the 5' untranslated region (5'UTR). TUFM silencing increased the half-life of BACE1 mRNA, suggesting that RNA stability was affected by TUFM. In support, transcription inhibitor Actinomycin D (ActD) and silencing of nuclear factor κB (NFκB) failed to abolish TUFM-mediated regulation of BACE1 protein and mRNA. We further found that the mitochondria-targeted antioxidant TEMPO diminished the effects of TUFM on BACE1, suggesting that reactive oxygen species (ROS) played an important role. Indeed, cellular ROS levels were affected by TUFM knockdown or overexpression, and TUFM-mediated regulation of apoptosis and Tau phosphorylation at selective sites was attenuated by TEMPO. Collectively, TUFM protein levels were decreased in APP/PS1 mice. TUFM is involved in AD pathology by regulating BACE1 translation, apoptosis, and Tau phosphorylation, in which ROS plays an important role.
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Affiliation(s)
- Bi-Rou Zhong
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Gui-Feng Zhou
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Li Song
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Qi-Xin Wen
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Xiao-Juan Deng
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Yuan-Lin Ma
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Li-Tian Hu
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China.,Department of Neurology, Nanchong Central Hospital, the Second Clinical College of North Sichuan Medical College, Nanchong, China
| | - Guo-Jun Chen
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
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Wang F, Zhang D, Zhang D, Li P, Gao Y. Mitochondrial Protein Translation: Emerging Roles and Clinical Significance in Disease. Front Cell Dev Biol 2021; 9:675465. [PMID: 34277617 PMCID: PMC8280776 DOI: 10.3389/fcell.2021.675465] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 06/09/2021] [Indexed: 12/28/2022] Open
Abstract
Mitochondria are one of the most important organelles in cells. Mitochondria are semi-autonomous organelles with their own genetic system, and can independently replicate, transcribe, and translate mitochondrial DNA. Translation initiation, elongation, termination, and recycling of the ribosome are four stages in the process of mitochondrial protein translation. In this process, mitochondrial protein translation factors and translation activators, mitochondrial RNA, and other regulatory factors regulate mitochondrial protein translation. Mitochondrial protein translation abnormalities are associated with a variety of diseases, including cancer, cardiovascular diseases, and nervous system diseases. Mutation or deletion of various mitochondrial protein translation factors and translation activators leads to abnormal mitochondrial protein translation. Mitochondrial tRNAs and mitochondrial ribosomal proteins are essential players during translation and mutations in genes encoding them represent a large fraction of mitochondrial diseases. Moreover, there is crosstalk between mitochondrial protein translation and cytoplasmic translation, and the imbalance between mitochondrial protein translation and cytoplasmic translation can affect some physiological and pathological processes. This review summarizes the regulation of mitochondrial protein translation factors, mitochondrial ribosomal proteins, mitochondrial tRNAs, and mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs) in the mitochondrial protein translation process and its relationship with diseases. The regulation of mitochondrial protein translation and cytoplasmic translation in multiple diseases is also summarized.
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Affiliation(s)
- Fei Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Deyu Zhang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Dejiu Zhang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Peifeng Li
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Yanyan Gao
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China.,Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, China
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4
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Rudorf S. Efficiency of protein synthesis inhibition depends on tRNA and codon compositions. PLoS Comput Biol 2019; 15:e1006979. [PMID: 31369559 PMCID: PMC6692046 DOI: 10.1371/journal.pcbi.1006979] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 08/13/2019] [Accepted: 07/15/2019] [Indexed: 11/19/2022] Open
Abstract
Regulation and maintenance of protein synthesis are vital to all organisms and are thus key targets of attack and defense at the cellular level. Here, we mathematically analyze protein synthesis for its sensitivity to the inhibition of elongation factor EF-Tu and/or ribosomes in dependence of the system’s tRNA and codon compositions. We find that protein synthesis reacts ultrasensitively to a decrease in the elongation factor’s concentration for systems with an imbalance between codon usages and tRNA concentrations. For well-balanced tRNA/codon compositions, protein synthesis is impeded more effectively by the inhibition of ribosomes instead of EF-Tu. Our predictions are supported by re-evaluated experimental data as well as by independent computer simulations. Not only does the described ultrasensitivity render EF-Tu a distinguished target of protein synthesis inhibiting antibiotics. It may also enable persister cell formation mediated by toxin-antitoxin systems. The strong impact of the tRNA/codon composition provides a basis for tissue-specificities of disorders caused by mutations of human mitochondrial EF-Tu as well as for the potential use of EF-Tu targeting drugs for tissue-specific treatments. We predict and analyze the response of differently composed protein synthesis systems to the inhibition of elongation factor EF-Tu and/or ribosomes. The study reveals a strong interdependency of a protein synthesis system’s composition and its susceptibility to inhibition. This interdependency defines a generic mechanism that provides a common basis for a variety of seemingly unrelated phenomena including, for example, persister cell formation and tissue-specificity of certain mitochondrial diseases. The described mechanism applies to simple artificial translation systems as well as to complex protein synthesis in vivo.
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Affiliation(s)
- Sophia Rudorf
- Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
- * E-mail:
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5
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Di Nottia M, Montanari A, Verrigni D, Oliva R, Torraco A, Fernandez-Vizarra E, Diodato D, Rizza T, Bianchi M, Catteruccia M, Zeviani M, Dionisi-Vici C, Francisci S, Bertini E, Carrozzo R. Novel mutation in mitochondrial Elongation Factor EF-Tu associated to dysplastic leukoencephalopathy and defective mitochondrial DNA translation. Biochim Biophys Acta Mol Basis Dis 2017; 1863:961-967. [PMID: 28132884 PMCID: PMC5335904 DOI: 10.1016/j.bbadis.2017.01.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/20/2016] [Accepted: 01/25/2017] [Indexed: 12/27/2022]
Abstract
The mitochondrial Elongation Factor Tu (EF-Tu), encoded by the TUFM gene, is a highly conserved GTPase, which is part of the mitochondrial protein translation machinery. In its activated form it delivers the aminoacyl-tRNAs to the A site of the mitochondrial ribosome. We report here on a baby girl with severe infantile macrocystic leukodystrophy with micropolygyria and a combined defect of complexes I and IV in muscle biopsy, caused by a novel mutation identified in TUFM. Using human mutant cells and the yeast model, we demonstrate the pathological role of the novel variant. Moreover, results of a molecular modeling study suggest that the mutant is inactive in mitochondrial polypeptide chain elongation, probably as a consequence of its reduced ability to bind mitochondrial aa-tRNAs. Four patients have so far been described with mutations in TUFM, and, following the first description of the disease in a single patient, we describe similar clinical and neuroradiological features in an additional patient.
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Affiliation(s)
- Michela Di Nottia
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Arianna Montanari
- Pasteur Institute Italy - Cenci Bolognetti Foundation, Italy; Department of Biology and Biotechnologies "Charles Darwin", Sapienza University of Rome, Rome, Italy
| | - Daniela Verrigni
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Romina Oliva
- Department of Sciences and Technologies, University Parthenope of Naples, Centro Direzionale Isola C4, I-80143 Naples, Italy
| | - Alessandra Torraco
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | | | - Daria Diodato
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Teresa Rizza
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Marzia Bianchi
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Michela Catteruccia
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Massimo Zeviani
- Mitochondrial Biology Unit, Medical Research Council, Cambridge, UK
| | - Carlo Dionisi-Vici
- Division of Metabolism, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Silvia Francisci
- Department of Biology and Biotechnologies "Charles Darwin", Sapienza University of Rome, Rome, Italy
| | - Enrico Bertini
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Rosalba Carrozzo
- Unit of Muscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy.
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6
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Cao X, Qin Y. Mitochondrial translation factors reflect coordination between organelles and cytoplasmic translation via mTOR signaling: Implication in disease. Free Radic Biol Med 2016; 100:231-237. [PMID: 27101739 DOI: 10.1016/j.freeradbiomed.2016.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 04/11/2016] [Accepted: 04/13/2016] [Indexed: 12/24/2022]
Abstract
Mitochondria are semi-autonomous organelle possessing their own translation machinery to biosynthesize mitochondrial DNA (mtDNA)-encoded polypeptides, which are the core subunits of oxidative phosphorylation (OXPHOS) complexes. Mitochondrial translation elongation factor 4 (mtEF4) is a key quality control factor in mitochondrial translation (mt-translation) that regulates mitochondrial tRNA translocation and modulates cellular responses by influencing cytoplasmic translation (ct-translation). In addition to mtEF4, mt-translational activators, mitochondrial microRNAs (mitomiRs), and MITRAC have been reported recently as crucial mt-translation regulators. Here, we focus on the novel ways how these factors regulate mt-translation, discuss the main cellular response of mammalian target of rapamycin (mTOR) signalling upon mt-translation defects, and summarize the related human diseases.
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Affiliation(s)
- Xintao Cao
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Qin
- Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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7
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Affiliation(s)
- Martin Ott
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
| | - Alexey Amunts
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden;
| | - Alan Brown
- Laboratory of Molecular Biology, Medical Research Council, Cambridge CB2 0QH, United Kingdom;
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8
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Liu J, Fang H, Chi Z, Wu Z, Wei D, Mo D, Niu K, Balajee AS, Hei TK, Nie L, Zhao Y. XPD localizes in mitochondria and protects the mitochondrial genome from oxidative DNA damage. Nucleic Acids Res 2015; 43:5476-88. [PMID: 25969448 PMCID: PMC4477675 DOI: 10.1093/nar/gkv472] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 04/28/2015] [Indexed: 01/12/2023] Open
Abstract
Xeroderma pigmentosum group D (XPD/ERCC2) encodes an ATP-dependent helicase that plays essential roles in both transcription and nucleotide excision repair of nuclear DNA, however, whether or not XPD exerts similar functions in mitochondria remains elusive. In this study, we provide the first evidence that XPD is localized in the inner membrane of mitochondria, and cells under oxidative stress showed an enhanced recruitment of XPD into mitochondrial compartment. Furthermore, mitochondrial reactive oxygen species production and levels of oxidative stress-induced mitochondrial DNA (mtDNA) common deletion were significantly elevated, whereas capacity for oxidative damage repair of mtDNA was markedly reduced in both XPD-suppressed human osteosarcoma (U2OS) cells and XPD-deficient human fibroblasts. Immunoprecipitation-mass spectrometry analysis was used to identify interacting factor(s) with XPD and TUFM, a mitochondrial Tu translation elongation factor was detected to be physically interacted with XPD. Similar to the findings in XPD-deficient cells, mitochondrial common deletion and oxidative damage repair capacity in U2OS cells were found to be significantly altered after TUFM knock-down. Our findings clearly demonstrate that XPD plays crucial role(s) in protecting mitochondrial genome stability by facilitating an efficient repair of oxidative DNA damage in mitochondria.
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Affiliation(s)
- Jing Liu
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongbo Fang
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhenfen Chi
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Zan Wu
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
| | - Di Wei
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China Hebei North University, Zhangjiakou 075000, China
| | - Dongliang Mo
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kaifeng Niu
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
| | - Adayabalam S Balajee
- REAC/TS, Oak Ridge Associated Universities, Oak Ridge Institute of Science and Engineering, Oak Ridge, TN 37830, USA
| | - Tom K Hei
- Center for Radiological Research, Department of Radiation Oncology, Columbia University Medical Center, New York, NY 10032, USA
| | - Linghu Nie
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yongliang Zhao
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
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9
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Mitochondrial EF4 links respiratory dysfunction and cytoplasmic translation in Caenorhabditis elegans. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1674-83. [PMID: 24837196 DOI: 10.1016/j.bbabio.2014.05.353] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 05/08/2014] [Accepted: 05/09/2014] [Indexed: 12/21/2022]
Abstract
How animals coordinate cellular bioenergetics in response to stress conditions is an essential question related to aging, obesity and cancer. Elongation factor 4 (EF4/LEPA) is a highly conserved protein that promotes protein synthesis under stress conditions, whereas its function in metazoans remains unknown. Here, we show that, in Caenorhabditis elegans, the mitochondria-localized CeEF4 (referred to as mtEF4) affects mitochondrial functions, especially at low temperature (15°C). At worms' optimum growing temperature (20°C), mtef4 deletion leads to self-brood size reduction, growth delay and mitochondrial dysfunction. Transcriptomic analyses show that mtef4 deletion induces retrograde pathways, including mitochondrial biogenesis and cytoplasmic translation reorganization. At low temperature (15°C), mtef4 deletion reduces mitochondrial translation and disrupts the assembly of respiratory chain supercomplexes containing complex IV. These observations are indicative of the important roles of mtEF4 in mitochondrial functions and adaptation to stressful conditions.
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10
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Multilevel functional and structural defects induced by two pathogenic mitochondrial tRNA mutations. Biochem J 2013; 453:455-65. [PMID: 23631826 DOI: 10.1042/bj20130294] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Point mutations in hmtRNAs (human mitochondrial tRNAs) can cause various disorders, such as CPEO (chronic progressive external ophthalmoplegia) and MM (mitochondrial myopathy). Mitochondrial tRNALeu, especially the UUR codon isoacceptor, is recognized as a hot spot for pathogenic mtDNA point mutations. Thus far, 40 mutations have been reported in hmtRNAsLeu. In the present paper, we describe the wide range of effects of two substitutions found in the TΨC arms of two hmtRNAsLeu isoacceptors. The G52A substitution, corresponding to the pathogenic G12315A mutation in tRNALeu(CUN), and G3283A in tRNALeu(UUR) exhibited structural changes in the outer corner of the tRNA shape as shown by RNase probing. These mutations also induced reductions in aminoacylation, 3'-end processing and base modification processes. The main effects of the A57G substitution, corresponding to mutations A12320G in tRNALeu(CUN) and A3288G in tRNALeu(UUR), were observed on the aminoacylation activity and binding to hmEF-Tu (human mitochondrial elongation factor Tu). These observations suggest that the wide range of effects may amplify the deleterious impact on mitochondrial protein synthesis in vivo. The findings also emphasize that an exact understanding of tRNA dysfunction is critical for the future development of therapies for mitochondrial diseases.
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11
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Pearce S, Nezich CL, Spinazzola A. Mitochondrial diseases: translation matters. Mol Cell Neurosci 2012; 55:1-12. [PMID: 22986124 DOI: 10.1016/j.mcn.2012.08.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 08/22/2012] [Accepted: 08/25/2012] [Indexed: 11/30/2022] Open
Abstract
Mitochondrial diseases comprise a heterogeneous group of disorders characterized by compromised energy production. Since the early days of mitochondrial medical genetics, it has been known that these can be caused by defects in mitochondrial protein synthesis. However, only in recent years have we begun to develop a broader picture of the array of proteins required for mitochondrial translation. With this new knowledge has come the realization that there are many more neurological and other, diseases attributable to impaired mitochondrial translation than previously thought. Perturbation of any part of this intricate machinery, from the primary sequence of transfer or ribosomal RNAs, to the proteolytic processing of ribosomal proteins, can cause mitochondrial dysfunction and disease. In this review we discuss the current understanding of the mechanisms and factors involved in mammalian mitochondrial translation, and the diverse pathologies resulting when it malfunctions. This article is part of a Special Issue entitled 'Mitochondrial function and dysfunction in neurodegeneration'.
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Affiliation(s)
- Sarah Pearce
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road Cambridge, CB2 0XY, UK
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12
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Zheleznova NN, Yang C, Ryan RP, Halligan BD, Liang M, Greene AS, Cowley AW. Mitochondrial proteomic analysis reveals deficiencies in oxygen utilization in medullary thick ascending limb of Henle in the Dahl salt-sensitive rat. Physiol Genomics 2012; 44:829-42. [PMID: 22805345 DOI: 10.1152/physiolgenomics.00060.2012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The renal medullary thick ascending limb (mTAL) of the Dahl salt-sensitive (SS) rat is the site of enhanced NaCl reabsorption and excess superoxide production. In the present studies we isolated mitochondria from mTAL of SS and salt-resistant control strain SS.13(BN) rats on 0.4 and 8% salt diet for 7 days and performed a proteomic analysis. Purity of mTAL and mitochondria isolations exceeded 93.6 and 55%, respectively. Using LC/MS spectral analysis techniques we identified 96 mitochondrial proteins in four biological mTAL mitochondria samples, run in duplicate, as defined by proteins with a false discovery rate <5% and scan count ≥2. Seven of these 96 proteins, including IDH2, ACADM, SCOT, Hsp60, ATPA, EFTu, and VDAC2 were differentially expressed between the two rat strains. Oxygen consumption and high-resolution respirometry analyses showed that mTAL cells and the mitochondria in the outer medulla of SS rats fed high-salt diet exhibited lower rates of oxygen utilization compared with those from SS.13(BN) rats. These studies advance the conventional proteomic paradigm of focusing exclusively upon whole tissue homogenates to a focus upon a single cell type and specific subcellular organelle. The results reveal the importance of a largely unexplored role for deficiencies of mTAL mitochondrial metabolism and oxygen utilization in salt-induced hypertension and renal medullary oxidative stress.
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Affiliation(s)
- Nadezhda N Zheleznova
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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13
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Christian BE, Spremulli LL. Mechanism of protein biosynthesis in mammalian mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1819:1035-54. [PMID: 22172991 DOI: 10.1016/j.bbagrm.2011.11.009] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 11/03/2011] [Accepted: 11/08/2011] [Indexed: 01/25/2023]
Abstract
Protein synthesis in mammalian mitochondria produces 13 proteins that are essential subunits of the oxidative phosphorylation complexes. This review provides a detailed outline of each phase of mitochondrial translation including initiation, elongation, termination, and ribosome recycling. The roles of essential proteins involved in each phase are described. All of the products of mitochondrial protein synthesis in mammals are inserted into the inner membrane. Several proteins that may help bind ribosomes to the membrane during translation are described, although much remains to be learned about this process. Mutations in mitochondrial or nuclear genes encoding components of the translation system often lead to severe deficiencies in oxidative phosphorylation, and a summary of these mutations is provided. This article is part of a Special Issue entitled: Mitochondrial Gene Expression.
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Affiliation(s)
- Brooke E Christian
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Abstract
Mitochondrial respiratory chain (RC) disorders (RCDs) are a group of genetically and clinically heterogeneous diseases because of the fact that protein components of the RC are encoded by both mitochondrial and nuclear genomes and are essential in all cells. In addition, the biogenesis, structure, and function of mitochondria, including DNA replication, transcription, and translation, all require nuclear-encoded genes. In this review, primary molecular defects in the mitochondrial genome and major classes of nuclear genes causing mitochondrial RCDs, including genes underlying mitochondrial DNA (mtDNA) depletion syndrome, as well as genes encoding RC subunits, complex assembly genes, and translation factors, are described. Diagnostic methodologies used to detect common point mutations, large deletions, and unknown point mutations in the mtDNA and to quantify mutation heteroplasmy are also discussed. Finally, the selection of nuclear genes for gold standard sequence analysis, application of novel technologies including oligonucleotide array comparative genomic hybridization, and massive parallel sequencing of target genes are reviewed.
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Affiliation(s)
- Lee-Jun C Wong
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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Shutt TE, Shadel GS. A compendium of human mitochondrial gene expression machinery with links to disease. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2010; 51:360-79. [PMID: 20544879 PMCID: PMC2886302 DOI: 10.1002/em.20571] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Mammalian mitochondrial DNA encodes 37 essential genes required for ATP production via oxidative phosphorylation, instability or misregulation of which is associated with human diseases and aging. Other than the mtDNA-encoded RNA species (13 mRNAs, 12S and 16S rRNAs, and 22 tRNAs), the remaining factors needed for mitochondrial gene expression (i.e., transcription, RNA processing/modification, and translation), including a dedicated set of mitochondrial ribosomal proteins, are products of nuclear genes that are imported into the mitochondrial matrix. Herein, we inventory the human mitochondrial gene expression machinery, and, while doing so, we highlight specific associations of these regulatory factors with human disease. Major new breakthroughs have been made recently in this burgeoning area that set the stage for exciting future studies on the key outstanding issue of how mitochondrial gene expression is regulated differentially in vivo. This should promote a greater understanding of why mtDNA mutations and dysfunction cause the complex and tissue-specific pathology characteristic of mitochondrial disease states and how mitochondrial dysfunction contributes to more common human pathology and aging.
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Affiliation(s)
- Timothy E. Shutt
- Department of Pathology, Yale University School of Medicine, 310 Cedar Street, P.O. Box 208023, New haven, CT 06520-8023
| | - Gerald S. Shadel
- Department of Pathology, Yale University School of Medicine, 310 Cedar Street, P.O. Box 208023, New haven, CT 06520-8023
- Department of Genetics, Yale University School of Medicine, 333 Cedar Street, P.O. Box 208005, New haven, CT 06520-8005
- corresponding author: Department of Pathology, Yale University School of Medicine, P.O. Box 208023, New Haven, CT 06520-8023 phone: (203) 785-2475 FAX: (203) 785-2628
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Akama K, Christian BE, Jones CN, Ueda T, Takeuchi N, Spremulli LL. Analysis of the functional consequences of lethal mutations in mitochondrial translational elongation factors. Biochim Biophys Acta Mol Basis Dis 2010; 1802:692-8. [PMID: 20435138 DOI: 10.1016/j.bbadis.2010.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 04/14/2010] [Accepted: 04/16/2010] [Indexed: 11/29/2022]
Abstract
Mammalian mitochondria synthesize a set of thirteen proteins that are essential for energy generation via oxidative phosphorylation. The genes for all of the factors required for synthesis of the mitochondrially encoded proteins are located in the nuclear genome. A number of disease-causing mutations have been identified in these genes. In this manuscript, we have elucidated the mechanisms of translational failure for two disease states characterized by lethal mutations in mitochondrial elongation factor Ts (EF-Ts(mt)) and elongation factor Tu (EF-Tu(mt)). EF-Tu(mt) delivers the aminoacyl-tRNA (aa-tRNA) to the ribosome during the elongation phase of protein synthesis. EF-Ts(mt) regenerates EF-Tu(mt):GTP from EF-Tu(mt):GDP. A mutation of EF-Ts(mt) (R325W) leads to a two-fold reduction in its ability to stimulate the activity of EF-Tu(mt) in poly(U)-directed polypeptide chain elongation. This loss of activity is caused by a significant reduction in the ability of EF-Ts(mt) R325W to bind EF-Tu(mt), leading to a defect in nucleotide exchange. A mutation of Arg336 to Gln in EF-Tu(mt) causes infantile encephalopathy caused by defects in mitochondrial translation. EF-Tu(mt) R336Q is as active as the wild-type protein in polymerization using Escherichia coli 70S ribosomes and E. coli [(14)C]Phe-tRNA but is inactive in polymerization with mitochondrial [(14)C]Phe-tRNA and mitochondrial 55S ribosomes. The R336Q mutation causes a two-fold decrease in ternary complex formation with E. coli aa-tRNA but completely inactivates EF-Tu(mt) for binding to mitochondrial aa-tRNA. Clearly the R336Q mutation in EF-Tu(mt) has a far more drastic effect on its interaction with mitochondrial aa-tRNAs than bacterial aa-tRNAs.
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Affiliation(s)
- Kenta Akama
- Department of Medical Genome Sciences, Graduate school of Frontier Sciences, University of Tokyo, Bunkyo, Tokyo113-8656, Japan
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Mitochondrial translation and beyond: processes implicated in combined oxidative phosphorylation deficiencies. J Biomed Biotechnol 2010; 2010:737385. [PMID: 20396601 PMCID: PMC2854570 DOI: 10.1155/2010/737385] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Accepted: 01/29/2010] [Indexed: 12/22/2022] Open
Abstract
Mitochondrial disorders are a heterogeneous group of often multisystemic and early fatal diseases, which are amongst the most common inherited human diseases. These disorders are caused by defects in the oxidative phosphorylation (OXPHOS) system, which comprises five multisubunit enzyme complexes encoded by both the nuclear and the mitochondrial genomes. Due to the multitude of proteins and intricacy of the processes required for a properly functioning OXPHOS system, identifying the genetic defect that underlies an OXPHOS deficiency is not an easy task, especially in the case of combined OXPHOS defects. In the present communication we give an extensive overview of the proteins and processes (in)directly involved in mitochondrial translation and the biogenesis of the OXPHOS system and their roles in combined OXPHOS deficiencies. This knowledge is important for further research into the genetic causes, with the ultimate goal to effectively prevent and cure these complex and often devastating disorders.
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