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Wang C, Hou X, Guan Q, Zhou H, Zhou L, Liu L, Liu J, Li F, Li W, Liu H. RNA modification in cardiovascular disease: implications for therapeutic interventions. Signal Transduct Target Ther 2023; 8:412. [PMID: 37884527 PMCID: PMC10603151 DOI: 10.1038/s41392-023-01638-7] [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: 11/23/2022] [Revised: 08/15/2023] [Accepted: 09/03/2023] [Indexed: 10/28/2023] Open
Abstract
Cardiovascular disease (CVD) is the leading cause of death in the world, with a high incidence and a youth-oriented tendency. RNA modification is ubiquitous and indispensable in cell, maintaining cell homeostasis and function by dynamically regulating gene expression. Accumulating evidence has revealed the role of aberrant gene expression in CVD caused by dysregulated RNA modification. In this review, we focus on nine common RNA modifications: N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), N4-acetylcytosine (ac4C), pseudouridine (Ψ), uridylation, adenosine-to-inosine (A-to-I) RNA editing, and modifications of U34 on tRNA wobble. We summarize the key regulators of RNA modification and their effects on gene expression, such as RNA splicing, maturation, transport, stability, and translation. Then, based on the classification of CVD, the mechanisms by which the disease occurs and progresses through RNA modifications are discussed. Potential therapeutic strategies, such as gene therapy, are reviewed based on these mechanisms. Herein, some of the CVD (such as stroke and peripheral vascular disease) are not included due to the limited availability of literature. Finally, the prospective applications and challenges of RNA modification in CVD are discussed for the purpose of facilitating clinical translation. Moreover, we look forward to more studies exploring the mechanisms and roles of RNA modification in CVD in the future, as there are substantial uncultivated areas to be explored.
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Affiliation(s)
- Cong Wang
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
- Clinical Center for Gene Diagnosis and Therapy, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Xuyang Hou
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
- Clinical Center for Gene Diagnosis and Therapy, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Qing Guan
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
- Clinical Center for Gene Diagnosis and Therapy, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Huiling Zhou
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
- Clinical Center for Gene Diagnosis and Therapy, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Li Zhou
- Department of Pathology, National Clinical Research Center for Geriatric Disorders, The Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Lijun Liu
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
- Clinical Center for Gene Diagnosis and Therapy, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Jijia Liu
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Feng Li
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Wei Li
- Department of Radiology, The Third Xiangya Hospital of Central South University, Changsha, Hunan, China.
| | - Haidan Liu
- Department of Cardiovascular Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China.
- Clinical Center for Gene Diagnosis and Therapy, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China.
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2
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Yu X, Luo B, Lin J, Zhu Y. Alternative splicing event associated with immunological features in bladder cancer. Front Oncol 2023; 12:966088. [PMID: 36686818 PMCID: PMC9851621 DOI: 10.3389/fonc.2022.966088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 11/30/2022] [Indexed: 01/07/2023] Open
Abstract
Bladder cancer (BLCA) is the most prevalent urinary tumor with few treatments. Alternative splicing (AS) is closely related to tumor development and tumor immune microenvironment. However, the comprehensive analysis of AS and prognosis and immunological features in BLCA is still lacking. In this study, we downloaded RNA-Seq data and clinical information from The Cancer Genome Atlas (TCGA) database, and AS events were acquired from the TCGA Splice-seq. A total of eight prognostic AS events (C19orf57|47943|ES, ANK3|11845|AP, AK9|77203|AT, GRIK2|77096|AT, DYM|45472|ES, PTGER3|3415|AT, ACTG1|44120|RI, and TRMU|62711|AA) were identified by univariate analysis and least absolute shrinkage and selection operator (LASSO) regression analysis to construct a risk score model. The Kaplan-Meier analysis revealed that the high-risk group had a worse prognosis compared with the low-risk group. The area under the receiver operating characteristic (ROC) curves (AUCs) for this risk score model in 1, 3, and 5 years were 0.698, 0.742, and 0.772, respectively. One of the prognostic AS event-related genes, TRMU, was differentially expressed between tumor and normal tissues in BLCA. The single-sample gene set enrichment analysis (ssGSEA) and CIBERSORT algorithm showed that both the risk score model and TRMU were significantly associated with tumor immune microenvironment and immune status (immune cells, immune-related pathway, and immune checkpoint) in BLCA patients. The TIMER database confirmed the relationship between the expression of TRMU and immune cells and checkpoint genes. Furthermore, Cytoscape software 3.8.0 was used to construct the regulatory network between AS and splicing factors (SFs). Our study demonstrated that AS events were powerful biomarkers to predict the prognosis and immune status in BLCA, which may be potential therapeutic targets in BLCA.
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Affiliation(s)
- Xinbo Yu
- Department of Urology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Bixian Luo
- Department of General Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jianwei Lin
- Department of General Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yu Zhu
- Department of Urology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China,*Correspondence: Yu Zhu,
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3
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Boutoual R, Jo H, Heckenbach I, Tiwari R, Kasler H, Lerner CA, Shah S, Schilling B, Calvanese V, Rardin MJ, Scheibye-Knudsen M, Verdin E. A novel splice variant of Elp3/Kat9 regulates mitochondrial tRNA modification and function. Sci Rep 2022; 12:14804. [PMID: 36045139 PMCID: PMC9433433 DOI: 10.1038/s41598-022-18114-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/05/2022] [Indexed: 12/03/2022] Open
Abstract
Post-translational modifications, such as lysine acetylation, regulate the activity of diverse proteins across many cellular compartments. Protein deacetylation in mitochondria is catalyzed by the enzymatic activity of the NAD+-dependent deacetylase sirtuin 3 (SIRT3), however it remains unclear whether corresponding mitochondrial acetyltransferases exist. We used a bioinformatics approach to search for mitochondrial proteins with an acetyltransferase catalytic domain, and identified a novel splice variant of ELP3 (mt-ELP3) of the elongator complex, which localizes to the mitochondrial matrix in mammalian cells. Unexpectedly, mt-ELP3 does not mediate mitochondrial protein acetylation but instead induces a post-transcriptional modification of mitochondrial-transfer RNAs (mt-tRNAs). Overexpression of mt-ELP3 leads to the protection of mt-tRNAs against the tRNA-specific RNase angiogenin, increases mitochondrial translation, and furthermore increases expression of OXPHOS complexes. This study thus identifies mt-ELP3 as a non-canonical mt-tRNA modifying enzyme.
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Affiliation(s)
- Rachid Boutoual
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA, 94945, USA.
| | - Hyunsun Jo
- Gladstone Institutes and University of California, San Francisco, San Francisco, CA, 94158, USA
| | - Indra Heckenbach
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA, 94945, USA.,Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Ritesh Tiwari
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA, 94945, USA
| | - Herbert Kasler
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA, 94945, USA
| | - Chad A Lerner
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA, 94945, USA
| | - Samah Shah
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA, 94945, USA
| | | | - Vincenzo Calvanese
- Gladstone Institutes and University of California, San Francisco, San Francisco, CA, 94158, USA
| | | | - Morten Scheibye-Knudsen
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Eric Verdin
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA, 94945, USA. .,Gladstone Institutes and University of California, San Francisco, San Francisco, CA, 94158, USA.
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4
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Human Mitochondrial RNA Processing and Modifications: Overview. Int J Mol Sci 2021; 22:ijms22157999. [PMID: 34360765 PMCID: PMC8348895 DOI: 10.3390/ijms22157999] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/23/2021] [Accepted: 07/24/2021] [Indexed: 01/29/2023] Open
Abstract
Mitochondria, often referred to as the powerhouses of cells, are vital organelles that are present in almost all eukaryotic organisms, including humans. They are the key energy suppliers as the site of adenosine triphosphate production, and are involved in apoptosis, calcium homeostasis, and regulation of the innate immune response. Abnormalities occurring in mitochondria, such as mitochondrial DNA (mtDNA) mutations and disturbances at any stage of mitochondrial RNA (mtRNA) processing and translation, usually lead to severe mitochondrial diseases. A fundamental line of investigation is to understand the processes that occur in these organelles and their physiological consequences. Despite substantial progress that has been made in the field of mtRNA processing and its regulation, many unknowns and controversies remain. The present review discusses the current state of knowledge of RNA processing in human mitochondria and sheds some light on the unresolved issues.
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Lian Y, Gòdia M, Castello A, Rodriguez-Gil JE, Balasch S, Sanchez A, Clop A. Characterization of the Impact of Density Gradient Centrifugation on the Profile of the Pig Sperm Transcriptome by RNA-Seq. Front Vet Sci 2021; 8:668158. [PMID: 34350225 PMCID: PMC8326511 DOI: 10.3389/fvets.2021.668158] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 06/22/2021] [Indexed: 12/18/2022] Open
Abstract
RNA-Seq data from human semen suggests that the study of the sperm transcriptome requires the previous elimination from the ejaculates of somatic cells carrying a larger load of RNA. Semen purification is also carried to study the sperm transcriptome in other species including swine and it is often done by density gradient centrifugation to obtain viable spermatozoa from fresh ejaculates or artificial insemination doses, thereby limiting the throughput and remoteness of the samples that can be processed in one study. The aim of this work was to evaluate the impact of purification with density gradient centrifugation by BoviPureTM on porcine sperm. Four boar ejaculates were purified with BoviPureTM and their transcriptome sequenced by RNA-Seq was compared with the RNA-Seq profiles of their paired non-purified sample. Seven thousand five hundred and nineteen protein coding genes were identified. Correlation, cluster, and principal component analysis indicated high—although not complete—similarity between the purified and the paired non-purified ejaculates. 372 genes displayed differentially abundant RNA levels between treatments. Most of these genes had lower abundances after purification and were mostly related to translation, transcription and metabolic processes. We detected a significant change in the proportion of genes of epididymal origin within the differentially abundant genes (1.3%) when compared with the catalog of unaltered genes (0.2%). In contrast, the proportion of testis-specific genes was higher in the group of unaltered genes (4%) when compared to the list of differentially abundant genes (0%). No proportion differences were identified for prostate, white blood, lymph node, tonsil, duodenum, skeletal muscle, liver, and mammary gland. Altogether, these results suggest that the purification impacts on the RNA levels of a small number of genes which are most likely caused by the removal of epididymal epithelial cells but also premature germinal cells, immature or abnormal spermatozoa or seminal exosomes with a distinct load of RNAs.
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Affiliation(s)
- Yu Lian
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Barcelona, Spain
| | - Marta Gòdia
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Barcelona, Spain
| | - Anna Castello
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Barcelona, Spain.,Unit of Animal Science, Department of Animal and Food Science, Autonomous University of Barcelona, Barcelona, Spain
| | - Joan Enric Rodriguez-Gil
- Unit of Animal Reproduction, Department of Animal Medicine and Surgery, Autonomous University of Barcelona, Barcelona, Spain
| | | | - Armand Sanchez
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Barcelona, Spain.,Unit of Animal Science, Department of Animal and Food Science, Autonomous University of Barcelona, Barcelona, Spain
| | - Alex Clop
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Barcelona, Spain.,Consejo Superior de Investigaciones Científicas, Barcelona, Spain
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6
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Peng GX, Zhang Y, Wang QQ, Li QR, Xu H, Wang ED, Zhou XL. The human tRNA taurine modification enzyme GTPBP3 is an active GTPase linked to mitochondrial diseases. Nucleic Acids Res 2021; 49:2816-2834. [PMID: 33619562 PMCID: PMC7969015 DOI: 10.1093/nar/gkab104] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 02/03/2021] [Accepted: 02/09/2021] [Indexed: 01/03/2023] Open
Abstract
GTPBP3 and MTO1 cooperatively catalyze 5-taurinomethyluridine (τm5U) biosynthesis at the 34th wobble position of mitochondrial tRNAs. Mutations in tRNAs, GTPBP3 or MTO1, causing τm5U hypomodification, lead to various diseases. However, efficient in vitro reconstitution and mechanistic study of τm5U modification have been challenging, in part due to the lack of pure and active enzymes. A previous study reported that purified human GTPBP3 (hGTPBP3) is inactive in GTP hydrolysis. Here, we identified the mature form of hGTPBP3 and showed that hGTPBP3 is an active GTPase in vitro that is critical for tRNA modification in vivo. Unexpectedly, the isolated G domain and a mutant with the N-terminal domain truncated catalyzed GTP hydrolysis to only a limited extent, exhibiting high Km values compared with that of the mature enzyme. We further described several important pathogenic mutations of hGTPBP3, associated with alterations in hGTPBP3 localization, structure and/or function in vitro and in vivo. Moreover, we discovered a novel cytoplasm-localized isoform of hGTPBP3, indicating an unknown potential noncanonical function of hGTPBP3. Together, our findings established, for the first time, the GTP hydrolysis mechanism of hGTPBP3 and laid a solid foundation for clarifying the τm5U modification mechanism and etiology of τm5U deficiency-related diseases.
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Affiliation(s)
- Gui-Xin Peng
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China.,School of Life Science and Technology, ShanghaiTech University, 393 Middle Hua Xia Road, Shanghai 201210, China
| | - Yong Zhang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Qin-Qin Wang
- School of Life Science and Technology, ShanghaiTech University, 393 Middle Hua Xia Road, Shanghai 201210, China
| | - Qing-Run Li
- CAS Key Laboratory of Systems Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
| | - Hong Xu
- Shanghai Key Laboratory of Embryo Original Diseases, Shanghai Municipal Key Clinical Specialty, the International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, 910 Heng Shan Road, Shanghai 200030, China
| | - En-Duo Wang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China.,School of Life Science and Technology, ShanghaiTech University, 393 Middle Hua Xia Road, Shanghai 201210, China
| | - Xiao-Long Zhou
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
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7
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Becker PH, Demir Z, Mozer Glassberg Y, Sevin C, Habes D, Imbard A, Mussini C, Rozenfeld Bar Lev M, Davit-Spraul A, Benoist JF, Thérond P, Slama A, Jacquemin E, Gonzales E, Gaignard P. Adenosine kinase deficiency: Three new cases and diagnostic value of hypermethioninemia. Mol Genet Metab 2021; 132:38-43. [PMID: 33309011 DOI: 10.1016/j.ymgme.2020.11.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/22/2020] [Accepted: 11/22/2020] [Indexed: 12/13/2022]
Abstract
Adenosine kinase (ADK) deficiency is characterized by liver disease, dysmorphic features, epilepsy and developmental delay. This defect disrupts the adenosine/AMP futile cycle and interferes with the upstream methionine cycle. We report the clinical, histological and biochemical courses of three ADK children carrying two new mutations and presenting with neonatal cholestasis and neurological disorders. One of them died of liver failure whereas the other two recovered from their liver damage. As the phenotype was consistent with a mitochondrial disorder, we studied liver mitochondrial respiratory chain activities in two patients and revealed a combined defect of several complexes. In addition, we retrospectively analyzed methionine plasma concentration, a hallmark of ADK deficiency, in a cohort of children and showed that methionine level in patients with ADK deficiency was strongly increased compared with patients with other liver diseases. ADK deficiency is a cause of neonatal or early infantile liver disease that may mimic primary mitochondrial disorders. In this context, an elevation of methionine plasma levels over twice the upper limit should not be considered as a nonspecific finding. ADK deficiency induced-liver dysfunction is most often transient, but could be life-threatening.
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Affiliation(s)
- Pierre-Hadrien Becker
- Department of Biochemistry, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France; Lip(Sys)2, University of Paris-Saclay, Chatenay-Malabry, France
| | - Zeynep Demir
- Pediatric Hepatology and Pediatric Liver Transplantation Unit, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - Yael Mozer Glassberg
- Institute of Gastroenterology, Nutrition, and Liver Disease, Schneider Children's Medical Center of Israel, Petah Tikva, Israel
| | - Caroline Sevin
- Pediatric Neurology Unit, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France; INSERM U1127, Institut du Cerveau et de la Moelle épinière (ICM), Pitié-Salpêtrière Hospital, Paris, France
| | - Dalila Habes
- Pediatric Hepatology and Pediatric Liver Transplantation Unit, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - Apolline Imbard
- Lip(Sys)2, University of Paris-Saclay, Chatenay-Malabry, France; Department of Metabolic Biochemistry, Necker Enfants Malades Hospital, University of Paris-Descartes, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Charlotte Mussini
- Department of Pathology, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - Michal Rozenfeld Bar Lev
- Institute of Gastroenterology, Nutrition, and Liver Disease, Schneider Children's Medical Center of Israel, Petah Tikva, Israel
| | - Anne Davit-Spraul
- Department of Biochemistry, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France; Inserm U1193, Hepatinov, University Paris-Saclay, Orsay, France
| | - Jean-François Benoist
- Lip(Sys)2, University of Paris-Saclay, Chatenay-Malabry, France; Department of Metabolic Biochemistry, Necker Enfants Malades Hospital, University of Paris-Descartes, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Patrice Thérond
- Department of Biochemistry, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France; Lip(Sys)2, University of Paris-Saclay, Chatenay-Malabry, France
| | - Abdelhamid Slama
- Department of Biochemistry, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France
| | - Emmanuel Jacquemin
- Pediatric Hepatology and Pediatric Liver Transplantation Unit, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France; Inserm U1193, Hepatinov, University Paris-Saclay, Orsay, France
| | - Emmanuel Gonzales
- Pediatric Hepatology and Pediatric Liver Transplantation Unit, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France; Inserm U1193, Hepatinov, University Paris-Saclay, Orsay, France
| | - Pauline Gaignard
- Department of Biochemistry, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, University of Paris-Saclay, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France; Lip(Sys)2, University of Paris-Saclay, Chatenay-Malabry, France.
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8
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Qin Z, Yang Q, Yi S, Huang L, Shen Y, Luo J. Whole-exome sequencing identified novel compound heterozygous variants in a Chinese neonate with liver failure and review of literature. Mol Genet Genomic Med 2020; 8:e1515. [PMID: 33205917 PMCID: PMC7767550 DOI: 10.1002/mgg3.1515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/23/2020] [Accepted: 09/10/2020] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Liver failure caused by TRMU is a rare hereditary disorder and clinically manifests into metabolic acidosis, hyperlactatemia, and hypoglycemia. Limited spectrum of TRMU pathogenic variants has been reported. METHODS Whole-exome sequencing was employed for the diagnosis of a 5-day-old female who suffered from severe neonatal hyperlactatemia and hypoglycemia since birth. Sanger sequencing was performed to confirm the origin of the variants subsequently. Variants classification was followed to ACMG guideline. RESULTS A compound heterozygosity of a frameshiftc.34_35dupTC (p.Gly13fs) and a missense c.244T>G (p.Phe82Val) in TRMU was detected, both variants are novel and pathogenic. Analysis of clinical and genetic information including patients reported previously indicated that there is no significant correlation between the genotype and the phenotype of TRMU-caused liver failure. CONCLUSION To the best of our knowledge, this is the first case report of TRMU-caused liver failure in China. Whole-exome sequencing is effective for conclusive diagnosis of this disorder and beneficial for its clinical management.
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Affiliation(s)
- Zailong Qin
- Genetic and Metabolic Central Laboratory, Guangxi Birth Defects Research and Prevention Institute, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China
| | - Qi Yang
- Genetic and Metabolic Central Laboratory, Guangxi Birth Defects Research and Prevention Institute, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China
| | - Shang Yi
- Genetic and Metabolic Central Laboratory, Guangxi Birth Defects Research and Prevention Institute, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China
| | - Limei Huang
- Genetic and Metabolic Central Laboratory, Guangxi Birth Defects Research and Prevention Institute, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China
| | - Yiping Shen
- Genetic and Metabolic Central Laboratory, Guangxi Birth Defects Research and Prevention Institute, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Jingsi Luo
- Genetic and Metabolic Central Laboratory, Guangxi Birth Defects Research and Prevention Institute, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China
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9
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Kwong S, Meyerson C, Zheng W, Kassardjian A, Stanzione N, Zhang K, Wang HL. Acute hepatitis and acute liver failure: Pathologic diagnosis and differential diagnosis. Semin Diagn Pathol 2019; 36:404-414. [PMID: 31405537 DOI: 10.1053/j.semdp.2019.07.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Acute hepatitis and acute liver failure are severe medical conditions that require early clinical intervention. Histopathologic findings on a liver biopsy or a liver explant may help identify the underlying etiology or provide an important direction for further clinical, laboratory and radiographical investigation. This review is divided into two main portions. The first portion concentrates on various etiologies and discusses unique histologic features that can be associated with specific etiologies. The second portion describes the general morphologic features based on which the diagnosis of acute hepatitis and acute liver failure are made. Histopathologic distinction between collapse and cirrhosis and limitations of histopathologic assessment for underlying etiologies are addressed in this portion. Another focus of this review is non-necrotic acute liver failure, which typically features diffuse microvesicular steatosis secondary to various etiologies causing mitochondrial dysfunction. Molecular testing serves an increasingly important role in the diagnosis and management of this group of disorders.
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Affiliation(s)
- Stanley Kwong
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095, United States.
| | - Cherise Meyerson
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095, United States
| | - Wei Zheng
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095, United States
| | - Ari Kassardjian
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095, United States
| | - Nicholas Stanzione
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095, United States
| | - Kuixing Zhang
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095, United States
| | - Hanlin L Wang
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA 90095, United States.
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10
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Meseguer S, Navarro-González C, Panadero J, Villarroya M, Boutoual R, Sánchez-Alcázar JA, Armengod ME. The MELAS mutation m.3243A>G alters the expression of mitochondrial tRNA fragments. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:1433-1449. [PMID: 31195049 DOI: 10.1016/j.bbamcr.2019.06.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 04/26/2019] [Accepted: 06/07/2019] [Indexed: 12/20/2022]
Abstract
Recent evidences highlight the importance of mitochondria-nucleus communication for the clinical phenotype of oxidative phosphorylation (OXPHOS) diseases. However, the participation of small non-coding RNAs (sncRNAs) in this communication has been poorly explored. We asked whether OXPHOS dysfunction alters the production of a new class of sncRNAs, mitochondrial tRNA fragments (mt tRFs), and, if so, whether mt tRFs play a physiological role and their accumulation is controlled by the action of mt tRNA modification enzymes. To address these questions, we used a cybrid model of MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes), an OXPHOS disease mostly caused by mutation m.3243A>G in the mitochondrial tRNALeu(UUR) gene. High-throughput analysis of small-RNA-Seq data indicated that m.3243A>G significantly changed the expression pattern of mt tRFs. A functional analysis of potential mt tRFs targets (performed under the assumption that these tRFs act as miRNAs) indicated an association with processes that involve the most common affected tissues in MELAS. We present evidences that mt tRFs may be biologically relevant, as one of them (mt i-tRF GluUUC), likely produced by the action of the nuclease Dicer and whose levels are Ago2 dependent, down-regulates the expression of mitochondrial pyruvate carrier 1 (MPC1), promoting the build-up of extracellular lactate. Therefore, our study underpins the idea that retrograde signaling from mitochondria is also mediated by mt tRFs. Finally, we show that accumulation of mt i-tRF GluUUC depends on the modification status of mt tRNAs, which is regulated by the action of stress-responsive miRNAs on mt tRNA modification enzymes.
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Affiliation(s)
- Salvador Meseguer
- RNA Modification and Mitochondrial Diseases Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Carrer d'Eduardo Primo Yúfera 3, Valencia 46012, Spain.
| | - Carmen Navarro-González
- RNA Modification and Mitochondrial Diseases Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Carrer d'Eduardo Primo Yúfera 3, Valencia 46012, Spain.
| | - Joaquin Panadero
- Unidad de Genómica, Instituto de Investigación Sanitaria La Fe, Avenida Fernando Abril Martorell, 106 Torre A 7ª planta, Valencia 46026, Spain.
| | - Magda Villarroya
- RNA Modification and Mitochondrial Diseases Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Carrer d'Eduardo Primo Yúfera 3, Valencia 46012, Spain.
| | - Rachid Boutoual
- RNA Modification and Mitochondrial Diseases Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Carrer d'Eduardo Primo Yúfera 3, Valencia 46012, Spain.
| | - Jose Antonio Sánchez-Alcázar
- Centro Andaluz de Biología del Desarrollo (CABD-CSIC-Universidad Pablo de Olavide), and Centro de Investigación Biomédica en Red Enfermedades Raras, Instituto de Salud Carlos III, Sevilla 41013, Spain.
| | - M-Eugenia Armengod
- RNA Modification and Mitochondrial Diseases Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Carrer d'Eduardo Primo Yúfera 3, Valencia 46012, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) node 721, Madrid 28029, Spain.
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11
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Soler-Alfonso C, Pillai N, Cooney E, Mysore KR, Boyer S, Scaglia F. L-Cysteine supplementation prevents liver transplantation in a patient with TRMU deficiency. Mol Genet Metab Rep 2019; 19:100453. [PMID: 30740308 PMCID: PMC6355510 DOI: 10.1016/j.ymgmr.2019.100453] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/22/2019] [Accepted: 01/23/2019] [Indexed: 12/13/2022] Open
Abstract
Early recognition of rare mitochondrial respiratory chain defects has become readily available with the routine use of whole exome sequencing. Patients with oxidative phosphorylation defects present with a heterogenous phenotype, often rapidly progressive, and lethal. Clinicians aim for prompt identification of the specific molecular defect to provide timely management, decrease morbidity, and potentially improve survival rates. More recently, bi-allelic pathogenic variants in the TRMU gene responsible for encoding the mitochondrial tRNA-specific 2-thiouridylase were found in a syndrome characterized by infantile hepatopathy due to a mitochondrial translation defect (OMIM# 613070). This nuclear encoded enzyme catalyzes the addition of a sulfur-containing thiol group to the wobble position of mitochondrial specific tRNAs. TRMU deficiency is characterized by a combined respiratory chain deficiency without associated mitochondrial DNA depletion. This mitochondrial tRNA-modifying enzyme requires sulfur for its activity. Previous cellular models have suggested supplementation with cysteine, one of the sulfur containing amino acids, may play a role in increasing thiouridylation levels of mt-tRNAs by increasing sulfur availability for TRMU activity. Cysteine is considered a conditional essential amino acid due to limited availability in infants caused by immature cystathionine gamma-lyase (cystathionase) enzyme activity. The potential benefit of L-cysteine supplementation in TRMU deficiency has been previously proposed to ameliorate the severity and insidious course of the disease. Here we report the clinical, biochemical, and genetic findings of two siblings presenting with hepatopathy associated with hyperlactatemia due to bi-allelic pathogenic variants in TRMU. One patient died due to related complications. The other case was diagnosed prenatally allowing early implementation of L-cysteine supplementation, recovery of liver function, and avoidance of liver transplantation.
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Affiliation(s)
- Claudia Soler-Alfonso
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States.,Texas Children's Hospital, Houston, TX, United States
| | - Nishita Pillai
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States.,Texas Children's Hospital, Houston, TX, United States
| | - Erin Cooney
- University of Texas Medical Branch, Galveston, TX, United States
| | - Krupa R Mysore
- Department of Pediatric Gastroenterology, Baylor College of Medicine, Houston, TX, United States
| | - Suzanne Boyer
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States.,Texas Children's Hospital, Houston, TX, United States
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States.,Texas Children's Hospital, Houston, TX, United States.,Joint BCM-CUHK Center of Medical Genetics, Prince of Wales Hospital, Hong Kong SAR
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12
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Zhang Q, Zhang L, Chen D, He X, Yao S, Zhang Z, Chen Y, Guan MX. Deletion of Mtu1 (Trmu) in zebrafish revealed the essential role of tRNA modification in mitochondrial biogenesis and hearing function. Nucleic Acids Res 2018; 46:10930-10945. [PMID: 30137487 PMCID: PMC6237746 DOI: 10.1093/nar/gky758] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 08/07/2018] [Accepted: 08/10/2018] [Indexed: 11/14/2022] Open
Abstract
Mtu1(Trmu) is a highly conserved tRNA modifying enzyme responsible for the biosynthesis of τm5s2U at the wobble position of tRNAGln, tRNAGlu and tRNALys. Our previous investigations showed that MTU1 mutation modulated the phenotypic manifestation of deafness-associated mitochondrial 12S rRNA mutation. However, the pathophysiology of MTU1 deficiency remains poorly understood. Using the mtu1 knock-out zebrafish generated by CRISPR/Cas9 system, we demonstrated the abolished 2-thiouridine modification of U34 of mitochondrial tRNALys, tRNAGlu and tRNAGln in the mtu1 knock-out zebrafish. The elimination of this post-transcriptional modification mediated mitochondrial tRNA metabolisms, causing the global decreases in the levels of mitochondrial tRNAs. The aberrant mitochondrial tRNA metabolisms led to the impairment of mitochondrial translation, respiratory deficiencies and reductions of mitochondrial ATP production. These mitochondria dysfunctions caused the defects in hearing organs. Strikingly, mtu1-/- mutant zebrafish displayed the abnormal startle response and swimming behaviors, significant decreases in the sizes of saccular otolith and numbers of hair cells in the auditory and vestibular organs. Furthermore, mtu1-/- mutant zebrafish exhibited the significant reductions in the hair bundle densities in utricle, saccule and lagena. Therefore, our findings may provide new insights into the pathophysiology of deafness, which was manifested by the deficient modifications at wobble position of mitochondrial tRNAs.
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Affiliation(s)
- Qinghai Zhang
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Luwen Zhang
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Danni Chen
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Xiao He
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Shihao Yao
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Zengming Zhang
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Ye Chen
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Min-Xin Guan
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Institute of Genetics, Zhejiang University and Department of Human Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Joint Institute of Genetics and Genome Medicine between Zhejiang University and University of Toronto, Hangzhou, Zhejiang 310058, China
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13
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RNA modification landscape of the human mitochondrial tRNA Lys regulates protein synthesis. Nat Commun 2018; 9:3966. [PMID: 30262910 PMCID: PMC6160436 DOI: 10.1038/s41467-018-06471-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 09/06/2018] [Indexed: 01/15/2023] Open
Abstract
Post-transcriptional RNA modifications play a critical role in the pathogenesis of human mitochondrial disorders, but the mechanisms by which specific modifications affect mitochondrial protein synthesis remain poorly understood. Here we used a quantitative RNA sequencing approach to investigate, at nucleotide resolution, the stoichiometry and methyl modifications of the entire mitochondrial tRNA pool, and establish the relevance to human disease. We discovered that a N1-methyladenosine (m1A) modification is missing at position 58 in the mitochondrial tRNALys of patients with the mitochondrial DNA mutation m.8344 A > G associated with MERRF (myoclonus epilepsy, ragged-red fibers). By restoring the modification on the mitochondrial tRNALys, we demonstrated the importance of the m1A58 to translation elongation and the stability of selected nascent chains. Our data indicates regulation of post-transcriptional modifications on mitochondrial tRNAs is finely tuned for the control of mitochondrial gene expression. Collectively, our findings provide novel insight into the regulation of mitochondrial tRNAs and reveal greater complexity to the molecular pathogenesis of MERRF.
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14
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Mitochondrial transcription and translation: overview. Essays Biochem 2018; 62:309-320. [PMID: 30030363 PMCID: PMC6056719 DOI: 10.1042/ebc20170102] [Citation(s) in RCA: 165] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/14/2018] [Accepted: 05/14/2018] [Indexed: 12/13/2022]
Abstract
Mitochondria are the major source of ATP in the cell. Five multi-subunit complexes in the inner membrane of the organelle are involved in the oxidative phosphorylation required for ATP production. Thirteen subunits of these complexes are encoded by the mitochondrial genome often referred to as mtDNA. For this reason, the expression of mtDNA is vital for the assembly and functioning of the oxidative phosphorylation complexes. Defects of the mechanisms regulating mtDNA gene expression have been associated with deficiencies in assembly of these complexes, resulting in mitochondrial diseases. Recently, numerous factors involved in these processes have been identified and characterized leading to a deeper understanding of the mechanisms that underlie mitochondrial diseases.
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15
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Bartsakoulia M, Mϋller JS, Gomez-Duran A, Yu-Wai-Man P, Boczonadi V, Horvath R. Cysteine Supplementation May be Beneficial in a Subgroup of Mitochondrial Translation Deficiencies. J Neuromuscul Dis 2018; 3:363-379. [PMID: 27854233 DOI: 10.3233/jnd-160178] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Mitochondrial encephalomyopathies are severe, relentlessly progressive conditions and there are very few effective therapies available to date. We have previously suggested that in two rare forms of reversible mitochondrial disease (reversible infantile respiratory chain deficiency and reversible infantile hepatopathy) supplementation with L-cysteine can improve mitochondrial protein synthesis, since cysteine is required for the 2-thiomodification of mitochondrial tRNAs. OBJECTIVES We studied whether supplementation with L-cysteine or N-acetyl-cysteine (NAC) results in any improvement of the mitochondrial function in vitro in fibroblasts of patients with different genetic forms of abnormal mitochondrial translation. METHODS We studied in vitro in fibroblasts of patients carrying the common m.3243A>G and m.8344A>G mutations or autosomal recessive mutations in genes affecting mitochondrial translation, whether L-cysteine or N-acetyl-cysteine supplementation have an effect on mitochondrial respiratory chain function. RESULTS Here we show that supplementation with L-cysteine, but not with N-acetyl-cysteine partially rescues the mitochondrial translation defect in vitro in fibroblasts of patients carrying the m.3243A>G and m.8344A>G mutations. In contrast, N-acetyl-cysteine had a beneficial effect on mitochondrial translation in TRMU and MTO1 deficient fibroblasts. CONCLUSIONS Our results suggest that L-cysteine or N-acetyl-cysteine supplementation may be a potential treatment for selected subgroups of patients with mitochondrial translation deficiencies. Further studies are needed to explore the full potential of cysteine supplementation as a treatment for patients with mitochondrial disease.
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Affiliation(s)
- Marina Bartsakoulia
- Wellcome Trust Mitochondrial Research Centre and the John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, UK
| | - Juliane S Mϋller
- Wellcome Trust Mitochondrial Research Centre and the John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, UK
| | - Aurora Gomez-Duran
- Wellcome Trust Mitochondrial Research Centre and the John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, UK.,Present address: Department of Clinical Neurosciences, Cambridge and MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Patrick Yu-Wai-Man
- Wellcome Trust Mitochondrial Research Centre and the John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, UK.,Newcastle Eye Centre, Royal Victoria Infirmary, Newcastle upon Tyne, UK.,NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
| | - Veronika Boczonadi
- Wellcome Trust Mitochondrial Research Centre and the John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, UK
| | - Rita Horvath
- Wellcome Trust Mitochondrial Research Centre and the John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne, UK
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16
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Aučynaitė A, Rutkienė R, Gasparavičiūtė R, Meškys R, Urbonavičius J. A gene encoding a DUF523 domain protein is involved in the conversion of 2-thiouracil into uracil. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:49-56. [PMID: 29194984 DOI: 10.1111/1758-2229.12605] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 11/17/2017] [Accepted: 11/19/2017] [Indexed: 06/07/2023]
Abstract
Modified nucleotides are present in many RNA species in all Domains of Life. While the biosynthetic pathways of such nucleotides are well studied, much less is known about the degradation of RNAs and the return to the metabolism of modified nucleotides, their respective nucleosides or heterocyclic bases. Using an E. coli uracil auxotroph, we screened the metagenomic libraries for genes, which would allow the conversion of 2-thiouracil to uracil and thereby lead to the growth on a defined synthetic medium. We show that a gene encoding a protein consisting of previously uncharacterized Domain of Unknown Function 523 (DUF523) is responsible for such phenotype. We have purified this recombinant protein and demonstrated that it contains a FeS cluster. The substitution of cysteines, which have been predicted to form such clusters, with alanines abolished the growth phenotype. We conclude that DUF523 is involved in the conversion of 2-thiouracil into uracil in vivo.
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Affiliation(s)
- Agota Aučynaitė
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Rasa Rutkienė
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Renata Gasparavičiūtė
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Rolandas Meškys
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Jaunius Urbonavičius
- Department of Molecular Microbiology and Biotechnology, Institute of Biochemistry, Life Sciences Center, Vilnius University, Vilnius, Lithuania
- Department of Chemistry and Bioengineering, Vilnius Gediminas Technical University, Vilnius, Lithuania
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17
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Defects in the mitochondrial-tRNA modification enzymes MTO1 and GTPBP3 promote different metabolic reprogramming through a HIF-PPARγ-UCP2-AMPK axis. Sci Rep 2018; 8:1163. [PMID: 29348686 PMCID: PMC5773609 DOI: 10.1038/s41598-018-19587-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/04/2018] [Indexed: 12/12/2022] Open
Abstract
Human proteins MTO1 and GTPBP3 are thought to jointly catalyze the modification of the wobble uridine in mitochondrial tRNAs. Defects in each protein cause infantile hypertrophic cardiomyopathy with lactic acidosis. However, the underlying mechanisms are mostly unknown. Using fibroblasts from an MTO1 patient and MTO1 silenced cells, we found that the MTO1 deficiency is associated with a metabolic reprogramming mediated by inactivation of AMPK, down regulation of the uncoupling protein 2 (UCP2) and transcription factor PPARγ, and activation of the hypoxia inducible factor 1 (HIF-1). As a result, glycolysis and oxidative phosphorylation are uncoupled, while fatty acid metabolism is altered, leading to accumulation of lipid droplets in MTO1 fibroblasts. Unexpectedly, this response is different from that triggered by the GTPBP3 defect, as GTPBP3-depleted cells exhibit AMPK activation, increased levels of UCP2 and PPARγ, and inactivation of HIF-1. In addition, fatty acid oxidation and respiration are stimulated in these cells. Therefore, the HIF-PPARγ-UCP2-AMPK axis is operating differently in MTO1- and GTPBP3-defective cells, which strongly suggests that one of these proteins has an additional role, besides mitochondrial-tRNA modification. This work provides new and useful information on the molecular basis of the MTO1 and GTPBP3 defects and on putative targets for therapeutic intervention.
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18
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O'Byrne JJ, Tarailo-Graovac M, Ghani A, Champion M, Deshpande C, Dursun A, Ozgul RK, Freisinger P, Garber I, Haack TB, Horvath R, Barić I, Husain RA, Kluijtmans LAJ, Kotzaeridou U, Morris AA, Ross CJ, Santra S, Smeitink J, Tarnopolsky M, Wortmann SB, Mayr JA, Brunner-Krainz M, Prokisch H, Wasserman WW, Wevers RA, Engelke UF, Rodenburg RJ, Ting TW, McFarland R, Taylor RW, Salvarinova R, van Karnebeek CDM. The genotypic and phenotypic spectrum of MTO1 deficiency. Mol Genet Metab 2018; 123:28-42. [PMID: 29331171 PMCID: PMC5780301 DOI: 10.1016/j.ymgme.2017.11.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 11/11/2017] [Accepted: 11/11/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND Mitochondrial diseases, a group of multi-systemic disorders often characterized by tissue-specific phenotypes, are usually progressive and fatal disorders resulting from defects in oxidative phosphorylation. MTO1 (Mitochondrial tRNA Translation Optimization 1), an evolutionarily conserved protein expressed in high-energy demand tissues has been linked to human early-onset combined oxidative phosphorylation deficiency associated with hypertrophic cardiomyopathy, often referred to as combined oxidative phosphorylation deficiency-10 (COXPD10). MATERIAL AND METHODS Thirty five cases of MTO1 deficiency were identified and reviewed through international collaboration. The cases of two female siblings, who presented at 1 and 2years of life with seizures, global developmental delay, hypotonia, elevated lactate and complex I and IV deficiency on muscle biopsy but without cardiomyopathy, are presented in detail. RESULTS For the description of phenotypic features, the denominator varies as the literature was insufficient to allow for complete ascertainment of all data for the 35 cases. An extensive review of all known MTO1 deficiency cases revealed the most common features at presentation to be lactic acidosis (LA) (21/34; 62% cases) and hypertrophic cardiomyopathy (15/34; 44% cases). Eventually lactic acidosis and hypertrophic cardiomyopathy are described in 35/35 (100%) and 27/34 (79%) of patients with MTO1 deficiency, respectively; with global developmental delay/intellectual disability present in 28/29 (97%), feeding difficulties in 17/35 (49%), failure to thrive in 12/35 (34%), seizures in 12/35 (34%), optic atrophy in 11/21 (52%) and ataxia in 7/34 (21%). There are 19 different pathogenic MTO1 variants identified in these 35 cases: one splice-site, 3 frameshift and 15 missense variants. None have bi-allelic variants that completely inactivate MTO1; however, patients where one variant is truncating (i.e. frameshift) while the second one is a missense appear to have a more severe, even fatal, phenotype. These data suggest that complete loss of MTO1 is not viable. A ketogenic diet may have exerted a favourable effect on seizures in 2/5 patients. CONCLUSION MTO1 deficiency is lethal in some but not all cases, and a genotype-phenotype relation is suggested. Aside from lactic acidosis and cardiomyopathy, developmental delay and other phenotypic features affecting multiple organ systems are often present in these patients, suggesting a broader spectrum than hitherto reported. The diagnosis should be suspected on clinical features and the presence of markers of mitochondrial dysfunction in body fluids, especially low residual complex I, III and IV activity in muscle. Molecular confirmation is required and targeted genomic testing may be the most efficient approach. Although subjective clinical improvement was observed in a small number of patients on therapies such as ketogenic diet and dichloroacetate, no evidence-based effective therapy exists.
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Affiliation(s)
- James J O'Byrne
- Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada
| | - Maja Tarailo-Graovac
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada; BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, Canada; Institute of Physiology and Biochemistry, Faculty of Biology, The University of Belgrade, Belgrade, Serbia
| | - Aisha Ghani
- Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada
| | - Michael Champion
- Department of Inherited Metabolic Disease, Guy's and St Thomas' NHS Foundation Trusts, Evelina London Children's Hospital, London, UK
| | - Charu Deshpande
- Clinical Genetics Unit, Guys and St Thomas' NHS Foundation Trust, London, UK
| | - Ali Dursun
- Hacettepe University, Faculty of Medicine, Institute of Child Health, Department of Pediatric Metabolism, Ankara, Turkey
| | - Riza K Ozgul
- Hacettepe University, Faculty of Medicine, Institute of Child Health, Department of Pediatric Metabolism, Ankara, Turkey
| | - Peter Freisinger
- Department of Pediatrics, Klinikum Reutlingen, Reutlingen, Germany
| | - Ian Garber
- BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada
| | - Tobias B Haack
- Institute of Human Genetics, Technische Universität München, Munich, Germany; Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
| | - Rita Horvath
- John Walton Muscular Dystrophy Research Centre, Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Ivo Barić
- University Hospital Center Zagreb & School of Medicine, University of Zagreb, Croatia
| | - Ralf A Husain
- Centre for Inborn Metabolic Disorders, Department of Neuropediatrics, Jena University Hospital, Jena, Germany
| | - Leo A J Kluijtmans
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Urania Kotzaeridou
- Department of General Pediatrics, Division of Neuropediatrics and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Andrew A Morris
- Willink Biochemical Genetics Unit, Manchester Centre for Genomic Medicine, Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - Colin J Ross
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Saikat Santra
- Department of Clinical Inherited Metabolic Disorders, Birmingham Children's Hospital, Steelhouse Lane, Birmingham, UK
| | - Jan Smeitink
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mark Tarnopolsky
- Department of Pediatrics, Division of Neuromuscular and Neurometabolic Diseases, McMaster University Medical Centre, Hamilton, ON, Canada
| | - Saskia B Wortmann
- Institute of Human Genetics, Technische Universität München, Munich, Germany; Institute of Human Genetics, Helmholtz Zentrum Munich, Neuherberg, Germany; Department of Pediatrics, Salzburger Landeskliniken (SALK), Paracelsus Medical University (PMU), Salzburg, Austria
| | - Johannes A Mayr
- Department of Pediatrics, Salzburger Landeskliniken (SALK), Paracelsus Medical University (PMU), Salzburg, Austria
| | | | - Holger Prokisch
- Institute of Human Genetics, Technische Universität München, Munich, Germany; Institute of Human Genetics, Helmholtz Zentrum Munich, Neuherberg, Germany
| | - Wyeth W Wasserman
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada; BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Ron A Wevers
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Udo F Engelke
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Richard J Rodenburg
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Teck Wah Ting
- Genetics Service, Department of Pediatrics, KK Women's and Children's Hospital, Singapore
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Ramona Salvarinova
- Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada; BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada; Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
| | - Clara D M van Karnebeek
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada; Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada; BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada; Departments of Pediatrics and Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands.
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19
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Meseguer S, Boix O, Navarro-González C, Villarroya M, Boutoual R, Emperador S, García-Arumí E, Montoya J, Armengod ME. microRNA-mediated differential expression of TRMU, GTPBP3 and MTO1 in cell models of mitochondrial-DNA diseases. Sci Rep 2017; 7:6209. [PMID: 28740091 PMCID: PMC5524753 DOI: 10.1038/s41598-017-06553-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/14/2017] [Indexed: 11/12/2022] Open
Abstract
Mitochondrial diseases due to mutations in the mitochondrial (mt) DNA are heterogeneous in clinical manifestations but usually include OXPHOS dysfunction. Mechanisms by which OXPHOS dysfunction contributes to the disease phenotype invoke, apart from cell energy deficit, maladaptive responses to mitochondria-to-nucleus retrograde signaling. Here we used five different cybrid models of mtDNA diseases to demonstrate that the expression of the nuclear-encoded mt-tRNA modification enzymes TRMU, GTPBP3 and MTO1 varies in response to specific pathological mtDNA mutations, thus altering the modification status of mt-tRNAs. Importantly, we demonstrated that the expression of TRMU, GTPBP3 and MTO1 is regulated by different miRNAs, which are induced by retrograde signals like ROS and Ca2+ via different pathways. Our data suggest that the up- or down-regulation of the mt-tRNA modification enzymes is part of a cellular response to cope with a stoichiometric imbalance between mtDNA- and nuclear-encoded OXPHOS subunits. However, this miRNA-mediated response fails to provide full protection from the OXPHOS dysfunction; rather, it appears to aggravate the phenotype since transfection of the mutant cybrids with miRNA antagonists improves the energetic state of the cells, which opens up options for new therapeutic approaches.
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Affiliation(s)
- Salvador Meseguer
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain.
| | - Olga Boix
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Carmen Navarro-González
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Magda Villarroya
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Rachid Boutoual
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Sonia Emperador
- Universidad de Zaragoza - CIBERER (node 727)-Instituto de Investigación Sanitaria de Aragón, Zaragoza, Spain
| | - Elena García-Arumí
- Hospital Universitario Vall d'Hebron (Barcelona, Spain) and Biomedical Research Networking Centre for Rare Diseases CIBERER, node 701, Barcelona, Spain
| | - Julio Montoya
- Universidad de Zaragoza - CIBERER (node 727)-Instituto de Investigación Sanitaria de Aragón, Zaragoza, Spain
| | - M-Eugenia Armengod
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain. .,CIBERER node 721, Valencia, Spain.
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20
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Mutations in the Caenorhabditis elegans orthologs of human genes required for mitochondrial tRNA modification cause similar electron transport chain defects but different nuclear responses. PLoS Genet 2017; 13:e1006921. [PMID: 28732077 PMCID: PMC5544249 DOI: 10.1371/journal.pgen.1006921] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 08/04/2017] [Accepted: 07/13/2017] [Indexed: 11/19/2022] Open
Abstract
Several oxidative phosphorylation (OXPHOS) diseases are caused by defects in the post-transcriptional modification of mitochondrial tRNAs (mt-tRNAs). Mutations in MTO1 or GTPBP3 impair the modification of the wobble uridine at position 5 of the pyrimidine ring and cause heart failure. Mutations in TRMU affect modification at position 2 and cause liver disease. Presently, the molecular basis of the diseases and why mutations in the different genes lead to such different clinical symptoms is poorly understood. Here we use Caenorhabditis elegans as a model organism to investigate how defects in the TRMU, GTPBP3 and MTO1 orthologues (designated as mttu-1, mtcu-1, and mtcu-2, respectively) exert their effects. We found that whereas the inactivation of each C. elegans gene is associated with a mild OXPHOS dysfunction, mutations in mtcu-1 or mtcu-2 cause changes in the expression of metabolic and mitochondrial stress response genes that are quite different from those caused by mttu-1 mutations. Our data suggest that retrograde signaling promotes defect-specific metabolic reprogramming, which is able to rescue the OXPHOS dysfunction in the single mutants by stimulating the oxidative tricarboxylic acid cycle flux through complex II. This adaptive response, however, appears to be associated with a biological cost since the single mutant worms exhibit thermosensitivity and decreased fertility and, in the case of mttu-1, longer reproductive cycle. Notably, mttu-1 worms also exhibit increased lifespan. We further show that mtcu-1; mttu-1 and mtcu-2; mttu-1 double mutants display severe growth defects and sterility. The animal models presented here support the idea that the pathological states in humans may initially develop not as a direct consequence of a bioenergetic defect, but from the cell’s maladaptive response to the hypomodification status of mt-tRNAs. Our work highlights the important association of the defect-specific metabolic rewiring with the pathological phenotype, which must be taken into consideration in exploring specific therapeutic interventions. Post-transcriptional modification of tRNAs is a universal process, thought to be essential for optimizing the functions of tRNAs. In humans, defects in the modification at position 2 (performed by protein TRMU) and 5 (carried out by proteins GTPBP3 and MTO1) of the uridine located at the wobble position of mitochondrial tRNAs (mt-tRNAs) cause oxidative phosphorylation (OXPHOS) dysfunction, and lead to liver and heart failure, respectively. However, the underlying mechanisms leading to pathogenesis are not well-known, and hence there is no molecular explanation for the different clinical phenotypes. We use Caenorhabditis elegans to compare in the same animal model and genetic background the effects of inactivating the TRMU, GTPBP3 and MTO1 orthologues on the phenotype and gene expression pattern of nuclear and mitochondrial DNA. Our data show that C. elegans responds to mt-tRNA hypomodification by changing in a defect-specific manner the expression of nuclear and mitochondrial genes, which leads, in all single mutants, to a rescue of the OXPHOS dysfunction that is associated with a biological cost. Our work suggests that pathology may develop as a consequence of the cell’s maladaptive response to the hypomodification status of mt-tRNAs.
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21
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Meng F, Cang X, Peng Y, Li R, Zhang Z, Li F, Fan Q, Guan AS, Fischel-Ghosian N, Zhao X, Guan MX. Biochemical Evidence for a Nuclear Modifier Allele (A10S) in TRMU (Methylaminomethyl-2-thiouridylate-methyltransferase) Related to Mitochondrial tRNA Modification in the Phenotypic Manifestation of Deafness-associated 12S rRNA Mutation. J Biol Chem 2017; 292:2881-2892. [PMID: 28049726 DOI: 10.1074/jbc.m116.749374] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 12/15/2016] [Indexed: 11/06/2022] Open
Abstract
Nuclear modifier gene(s) was proposed to modulate the phenotypic expression of mitochondrial DNA mutation(s). Our previous investigations revealed that a nuclear modifier allele (A10S) in TRMU (methylaminomethyl-2-thiouridylate-methyltransferase) related to tRNA modification interacts with 12S rRNA 1555A→G mutation to cause deafness. The A10S mutation resided at a highly conserved residue of the N-terminal sequence. It was hypothesized that the A10S mutation altered the structure and function of TRMU, thereby causing mitochondrial dysfunction. Using molecular dynamics simulations, we showed that the A10S mutation introduced the Ser10 dynamic electrostatic interaction with the Lys106 residue of helix 4 within the catalytic domain of TRMU. The Western blotting analysis displayed the reduced levels of TRMU in mutant cells carrying the A10S mutation. The thermal shift assay revealed the Tm value of mutant TRMU protein, lower than that of the wild-type counterpart. The A10S mutation caused marked decreases in 2-thiouridine modification of U34 of tRNALys, tRNAGlu and tRNAGln However, the A10S mutation mildly increased the aminoacylated efficiency of tRNAs. The altered 2-thiouridine modification worsened the impairment of mitochondrial translation associated with the m.1555A→G mutation. The defective translation resulted in the reduced activities of mitochondrial respiration chains. The respiratory deficiency caused the reduction of mitochondrial ATP production and elevated the production of reactive oxidative species. As a result, mutated TRMU worsened mitochondrial dysfunctions associated with m.1555A→G mutation, exceeding the threshold for expressing a deafness phenotype. Our findings provided new insights into the pathophysiology of maternally inherited deafness that was manifested by interaction between mtDNA mutation and nuclear modifier gene.
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Affiliation(s)
- Feilong Meng
- From the Division of Medical Genetics and Genomics, Zhejiang Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,the Institute of Genetics and
| | - Xiaohui Cang
- From the Division of Medical Genetics and Genomics, Zhejiang Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,the Institute of Genetics and
| | - Yanyan Peng
- the Institute of Genetics and.,the Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
| | - Ronghua Li
- the Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30307
| | | | | | | | - Anna S Guan
- the Ahmanson Department of Pediatrics, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California 90095, and
| | - Nathan Fischel-Ghosian
- the Ahmanson Department of Pediatrics, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California 90095, and
| | | | - Min-Xin Guan
- From the Division of Medical Genetics and Genomics, Zhejiang Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China, .,the Institute of Genetics and.,the Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, Zhejiang 310058, China.,the Joining Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Hangzhou, Zhejiang 310058, China
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22
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Wu Y, Wei FY, Kawarada L, Suzuki T, Araki K, Komohara Y, Fujimura A, Kaitsuka T, Takeya M, Oike Y, Suzuki T, Tomizawa K. Mtu1-Mediated Thiouridine Formation of Mitochondrial tRNAs Is Required for Mitochondrial Translation and Is Involved in Reversible Infantile Liver Injury. PLoS Genet 2016; 12:e1006355. [PMID: 27689697 PMCID: PMC5045200 DOI: 10.1371/journal.pgen.1006355] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 09/08/2016] [Indexed: 12/26/2022] Open
Abstract
Reversible infantile liver failure (RILF) is a unique heritable liver disease characterized by acute liver failure followed by spontaneous recovery at an early stage of life. Genetic mutations in MTU1 have been identified in RILF patients. MTU1 is a mitochondrial enzyme that catalyzes the 2-thiolation of 5-taurinomethyl-2-thiouridine (τm5s2U) found in the anticodon of a subset of mitochondrial tRNAs (mt-tRNAs). Although the genetic basis of RILF is clear, the molecular mechanism that drives the pathogenesis remains elusive. We here generated liver-specific knockout of Mtu1 (Mtu1LKO) mice, which exhibited symptoms of liver injury characterized by hepatic inflammation and elevated levels of plasma lactate and AST. Mechanistically, Mtu1 deficiency resulted in a loss of 2-thiolation in mt-tRNAs, which led to a marked impairment of mitochondrial translation. Consequently, Mtu1LKO mice exhibited severe disruption of mitochondrial membrane integrity and a broad decrease in respiratory complex activities in the hepatocytes. Interestingly, mitochondrial dysfunction induced signaling pathways related to mitochondrial proliferation and the suppression of oxidative stress. The present study demonstrates that Mtu1-dependent 2-thiolation of mt-tRNA is indispensable for mitochondrial translation and that Mtu1 deficiency is a primary cause of RILF. In addition, Mtu1 deficiency is associated with multiple cytoprotective pathways that might prevent catastrophic liver failure and assist in the recovery from liver injury. Mitochondrial transfer tRNA (mt-tRNA) contains a variety of chemical modifications that are introduced post-transcriptionally. Three mt-tRNAs for Lys, Gln and Glu contain 5-taurinomethyl-2-thiouridine (τm5s2U) in their anticodons. It is known that the loss of 2-thiolation of τm5s2U is strongly associated with the development of reversible infantile liver failure (RILF) because pathogenic mutations of RILF were found in the MTU1 gene, which encodes an enzyme responsible for the 2-thiolation of τm5s2U. However, the molecular mechanism underlying RILF pathogenesis associated with a lack of MTU1 remains elusive. To understand the physiological function of MTU1 and its association with liver failure, we generated liver-specific Mtu1-deficient (Mtu1LKO) mice. Mtu1 deficiency abolished 2-thiouridine formation in the three mt-tRNAs. Loss of the 2-thiouridine modification resulted in a marked impairment of mitochondrial translation and abnormal mitochondrial structure. Consequently, the Mtu1LKO mice exhibited liver injury, which resembles the symptoms of RILF patients. Furthermore, mitochondrial dysfunction in Mtu1LKO mice induced mitochondrial biogenesis and suppressed oxidative stress. These findings elucidate the cellular and physiological functions of Mtu1 and provide a mouse model for understanding RILF pathogenesis.
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Affiliation(s)
- Yong Wu
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Fan-Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Kawaguchi, Japan
| | - Layla Kawarada
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Takeo Suzuki
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Kimi Araki
- Division of Developmental Genetics, Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Japan
| | - Yoshihiro Komohara
- Department of Cell Pathology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Atsushi Fujimura
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Taku Kaitsuka
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Motohiro Takeya
- Department of Cell Pathology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Yuichi Oike
- Department of Molecular Genetics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
- * E-mail:
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23
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Duechler M, Leszczyńska G, Sochacka E, Nawrot B. Nucleoside modifications in the regulation of gene expression: focus on tRNA. Cell Mol Life Sci 2016; 73:3075-95. [PMID: 27094388 PMCID: PMC4951516 DOI: 10.1007/s00018-016-2217-y] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 03/25/2016] [Accepted: 04/04/2016] [Indexed: 01/10/2023]
Abstract
Both, DNA and RNA nucleoside modifications contribute to the complex multi-level regulation of gene expression. Modified bases in tRNAs modulate protein translation rates in a highly dynamic manner. Synonymous codons, which differ by the third nucleoside in the triplet but code for the same amino acid, may be utilized at different rates according to codon-anticodon affinity. Nucleoside modifications in the tRNA anticodon loop can favor the interaction with selected codons by stabilizing specific base pairs. Similarly, weakening of base pairing can discriminate against binding to near-cognate codons. mRNAs enriched in favored codons are translated in higher rates constituting a fine-tuning mechanism for protein synthesis. This so-called codon bias establishes a basic protein level, but sometimes it is necessary to further adjust the production rate of a particular protein to actual requirements, brought by, e.g., stages in circadian rhythms, cell cycle progression or exposure to stress. Such an adjustment is realized by the dynamic change of tRNA modifications resulting in the preferential translation of mRNAs coding for example for stress proteins to facilitate cell survival. Furthermore, tRNAs contribute in an entirely different way to another, less specific stress response consisting in modification-dependent tRNA cleavage that contributes to the general down-regulation of protein synthesis. In this review, we summarize control functions of nucleoside modifications in gene regulation with a focus on recent findings on protein synthesis control by tRNA base modifications.
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Affiliation(s)
- Markus Duechler
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland.
| | - Grażyna Leszczyńska
- Institute of Organic Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland
| | - Elzbieta Sochacka
- Institute of Organic Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland
| | - Barbara Nawrot
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland
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24
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He Z, Sun S, Waqas M, Zhang X, Qian F, Cheng C, Zhang M, Zhang S, Wang Y, Tang M, Li H, Chai R. Reduced TRMU expression increases the sensitivity of hair-cell-like HEI-OC-1 cells to neomycin damage in vitro. Sci Rep 2016; 6:29621. [PMID: 27405449 PMCID: PMC4942793 DOI: 10.1038/srep29621] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/20/2016] [Indexed: 12/13/2022] Open
Abstract
Aminoglycosides are ototoxic to the cochlear hair cells, and mitochondrial dysfunction is one of the major mechanisms behind ototoxic drug-induced hair cell death. TRMU (tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase) is a mitochondrial protein that participates in mitochondrial tRNA modifications, but the role of TRMU in aminoglycoside-induced ototoxicity remains to be elucidated. In this study, we took advantage of the HEI-OC-1 cell line to investigate the role of TRMU in aminoglycoside-induced cell death. We found that TRMU is expressed in both hair cells and HEI-OC-1 cells, and its expression is significantly decreased after 24 h neomycin treatment. We then downregulated TRMU expression with siRNA and found that cell death and apoptosis were significantly increased after neomycin injury. Furthermore, when we down-regulated TRMU expression, we observed significantly increased mitochondrial dysfunction and increased levels of reactive oxygen species (ROS) after neomycin injury, suggesting that TRMU regulates mitochondrial function and ROS levels. Lastly, the antioxidant N-acetylcysteine rescued the mitochondrial dysfunction and cell apoptosis that was induced by TRMU downregulation, suggesting that ROS accumulation contributed to the increased aminoglycosides sensitivity of HEI-OC-1 cells after TRMU downregulation. This study provides evidence that TRMU might be a new therapeutic target for the prevention of aminoglycoside-induced hair cell death.
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Affiliation(s)
- Zuhong He
- State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,MOE Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China
| | - Shan Sun
- Department of Otorhinolaryngology, Hearing Research Institute, Affiliated Eye and ENT Hospital of Fudan University, Shanghai 200031, China
| | - Muhammad Waqas
- State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,MOE Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China
| | - Xiaoli Zhang
- Department of Otolaryngology, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008, China
| | - Fuping Qian
- State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,MOE Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China
| | - Cheng Cheng
- State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,MOE Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China
| | - Mingshu Zhang
- Medical School, Southeast University, Nanjing 210096, China
| | - Shasha Zhang
- State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,MOE Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China
| | - Yongming Wang
- Institutes of Life Sciences, Fudan University, Shanghai 200032, China
| | - Mingliang Tang
- State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,MOE Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China
| | - Huawei Li
- Department of Otorhinolaryngology, Hearing Research Institute, Affiliated Eye and ENT Hospital of Fudan University, Shanghai 200031, China.,Institutes of Life Sciences, Fudan University, Shanghai 200032, China
| | - Renjie Chai
- State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,MOE Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing 210096, China.,Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China
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25
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Allele-specific PCR for detecting the deafness-associated mitochondrial 12S rRNA mutations. Gene 2016; 591:148-152. [PMID: 27397648 DOI: 10.1016/j.gene.2016.07.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/22/2016] [Accepted: 07/05/2016] [Indexed: 01/19/2023]
Abstract
Mutations in mitochondrial 12S rRNA (MT-RNR1) are the important causes of sensorineural hearing loss. Of these mutations, the homoplasmic m.1555A>G or m.1494C>T mutation in the highly conserved A-site of MT-RNR1 gene has been found to be associated with both aminoglycoside-induced and non-syndromic hearing loss in many families worldwide. Since the m.1555A>G and m.1494C>T mutations are sensitive to ototoxic drugs, therefore, screening for the presence of these mutations is important for early diagnosis and prevention of deafness. For this purpose, we recently developed a novel allele-specific PCR (AS-PCR) which is able to simultaneously detect these mutations. To assess its accuracy, in this study, we employed this method to screen the frequency of m.1555A>G and m.1494C>T mutations in 200 deafness patients and 120 healthy subjects. Consequently, four m.1555A>G and four m.1494C>T mutations were identified; among these, only one patient with the m.1494C>T mutation had an obvious family history of hearing loss. Strikingly, clinical evaluation showed that this family exhibited a high penetrance of hearing loss. In particular, the penetrances of hearing loss were 80% with the aminoglycoside included and 20% when excluded. PCR-Sanger sequencing of the mitochondrial genomes confirmed the presence of the m.1494C>T mutation and identified a set of polymorphisms belonging to mitochondrial haplogroup A. However, the lack of functional variants in mitochondrial and nuclear modified genes (GJB2 and TRMU) in this family indicated that mitochondrial haplogroup and nuclear genes may not play important roles in the phenotypic expression of the m.1494C>T mutation. Thus, other modification factors, such as environmental factor, aminoglycosides or epigenetic modification may have contributed to the high penetrance of hearing loss in this family. Taken together, our data showed that this assay is an effective approach that could be used for detection the deafness-associated MT-RNR1 mutations.
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26
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Shigi N. Sulfur Modifications in tRNA: Function and Implications for Human Disease. MODIFIED NUCLEIC ACIDS IN BIOLOGY AND MEDICINE 2016. [DOI: 10.1007/978-3-319-34175-0_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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27
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Martínez-Zamora A, Meseguer S, Esteve JM, Villarroya M, Aguado C, Enríquez JA, Knecht E, Armengod ME. Defective Expression of the Mitochondrial-tRNA Modifying Enzyme GTPBP3 Triggers AMPK-Mediated Adaptive Responses Involving Complex I Assembly Factors, Uncoupling Protein 2, and the Mitochondrial Pyruvate Carrier. PLoS One 2015; 10:e0144273. [PMID: 26642043 PMCID: PMC4671719 DOI: 10.1371/journal.pone.0144273] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/16/2015] [Indexed: 12/22/2022] Open
Abstract
GTPBP3 is an evolutionary conserved protein presumably involved in mitochondrial tRNA (mt-tRNA) modification. In humans, GTPBP3 mutations cause hypertrophic cardiomyopathy with lactic acidosis, and have been associated with a defect in mitochondrial translation, yet the pathomechanism remains unclear. Here we use a GTPBP3 stable-silencing model (shGTPBP3 cells) for a further characterization of the phenotype conferred by the GTPBP3 defect. We experimentally show for the first time that GTPBP3 depletion is associated with an mt-tRNA hypomodification status, as mt-tRNAs from shGTPBP3 cells were more sensitive to digestion by angiogenin than tRNAs from control cells. Despite the effect of stable silencing of GTPBP3 on global mitochondrial translation being rather mild, the steady-state levels and activity of Complex I, and cellular ATP levels were 50% of those found in the controls. Notably, the ATPase activity of Complex V increased by about 40% in GTPBP3 depleted cells suggesting that mitochondria consume ATP to maintain the membrane potential. Moreover, shGTPBP3 cells exhibited enhanced antioxidant capacity and a nearly 2-fold increase in the uncoupling protein UCP2 levels. Our data indicate that stable silencing of GTPBP3 triggers an AMPK-dependent retrograde signaling pathway that down-regulates the expression of the NDUFAF3 and NDUFAF4 Complex I assembly factors and the mitochondrial pyruvate carrier (MPC), while up-regulating the expression of UCP2. We also found that genes involved in glycolysis and oxidation of fatty acids are up-regulated. These data are compatible with a model in which high UCP2 levels, together with a reduction in pyruvate transport due to the down-regulation of MPC, promote a shift from pyruvate to fatty acid oxidation, and to an uncoupling of glycolysis and oxidative phosphorylation. These metabolic alterations, and the low ATP levels, may negatively affect heart function.
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Affiliation(s)
- Ana Martínez-Zamora
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Salvador Meseguer
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Juan M. Esteve
- Laboratory of Intracellular Protein Degradation and Rare Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Magda Villarroya
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Carmen Aguado
- Laboratory of Intracellular Protein Degradation and Rare Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
- Centro de Investigación Biomédica En Red de Enfermedades Raras (CIBERER), node U721, Valencia, Spain
| | - J. Antonio Enríquez
- Departamento de Desarrollo y Reparación Cardiovascular, Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Zaragoza, Spain
| | - Erwin Knecht
- Laboratory of Intracellular Protein Degradation and Rare Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
- Centro de Investigación Biomédica En Red de Enfermedades Raras (CIBERER), node U721, Valencia, Spain
| | - M.-Eugenia Armengod
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia, Spain
- Centro de Investigación Biomédica En Red de Enfermedades Raras (CIBERER), node U721, Valencia, Spain
- * E-mail:
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A mutation in MT-TW causes a tRNA processing defect and reduced mitochondrial function in a family with Leigh syndrome. Mitochondrion 2015; 25:113-9. [PMID: 26524491 DOI: 10.1016/j.mito.2015.10.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 09/29/2015] [Accepted: 10/26/2015] [Indexed: 01/10/2023]
Abstract
Leigh syndrome (LS) is a progressive mitochondrial neurodegenerative disorder, whose symptoms most commonly include psychomotor delay with regression, lactic acidosis and a failure to thrive. Here we describe three siblings with LS, but with additional manifestations including hypertrophic cardiomyopathy, hepatosplenomegaly, cholestatic hepatitis, and seizures. All three affected siblings were found to be homoplasmic for an m. 5559A>G mutation in the T stem of the mitochondrial DNA-encoded MT-TW by next generation sequencing. The m.5559A>G mutation causes a reduction in the steady state levels of tRNA(Trp) and this decrease likely affects the stability of other mitochondrial RNAs in the patient fibroblasts. We observe accumulation of an unprocessed transcript containing tRNA(Trp), decreased de novo protein synthesis and consequently lowered steady state levels of mitochondrial DNA-encoded proteins that compromise mitochondrial respiration. Our results show that the m.5559A>G mutation at homoplasmic levels causes LS in association with severe multi-organ disease (LS-plus) as a consequence of dysfunctional mitochondrial RNA metabolism.
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Armengod ME, Meseguer S, Villarroya M, Prado S, Moukadiri I, Ruiz-Partida R, Garzón MJ, Navarro-González C, Martínez-Zamora A. Modification of the wobble uridine in bacterial and mitochondrial tRNAs reading NNA/NNG triplets of 2-codon boxes. RNA Biol 2015; 11:1495-507. [PMID: 25607529 DOI: 10.4161/15476286.2014.992269] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Posttranscriptional modification of the uridine located at the wobble position (U34) of tRNAs is crucial for optimization of translation. Defects in the U34 modification of mitochondrial-tRNAs are associated with a group of rare diseases collectively characterized by the impairment of the oxidative phosphorylation system. Retrograde signaling pathways from mitochondria to nucleus are involved in the pathophysiology of these diseases. These pathways may be triggered by not only the disturbance of the mitochondrial (mt) translation caused by hypomodification of tRNAs, but also as a result of nonconventional roles of mt-tRNAs and mt-tRNA-modifying enzymes. The evolutionary conservation of these enzymes supports their importance for cell and organismal functions. Interestingly, bacterial and eukaryotic cells respond to stress by altering the expression or activity of these tRNA-modifying enzymes, which leads to changes in the modification status of tRNAs. This review summarizes recent findings about these enzymes and sets them within the previous data context.
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Affiliation(s)
- M Eugenia Armengod
- a Laboratory of RNA Modification and Mitochondrial Diseases ; Centro de Investigación Príncipe Felipe ; Valencia , Spain
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Boczonadi V, Bansagi B, Horvath R. Reversible infantile mitochondrial diseases. J Inherit Metab Dis 2015; 38:427-35. [PMID: 25407320 DOI: 10.1007/s10545-014-9784-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 10/09/2014] [Accepted: 10/14/2014] [Indexed: 11/30/2022]
Abstract
Mitochondrial diseases are usually severe and progressive conditions; however, there are rare forms that show remarkable spontaneous recoveries. Two homoplasmic mitochondrial tRNA mutations (m.14674T>C/G in mt-tRNA(Glu)) have been reported to cause severe infantile mitochondrial myopathy in the first months of life. If these patients survive the first year of life by extensive life-sustaining measures they usually recover and develop normally. Another mitochondrial disease due to deficiency of the 5-methylaminomethyl-2-thiouridylate methyltransferase (TRMU) causes severe liver failure in infancy, but similar to the reversible mitochondrial myopathy, within the first year of life these infants may also recover completely. Partial recovery has been noted in some other rare forms of mitochondrial disease due to deficiency of mitochondrial tRNA synthetases and mitochondrial tRNA modifying enzymes. Here we summarize the clinical presentation of these unique reversible mitochondrial diseases and discuss potential molecular mechanisms behind the reversibility. Understanding these mechanisms may provide the key to treatments of potential broader relevance in mitochondrial disease, where for the majority of the patients no effective treatment is currently available.
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Affiliation(s)
- Veronika Boczonadi
- Institute of Human Genetics, Newcastle University, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
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31
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Tischner C, Hofer A, Wulff V, Stepek J, Dumitru I, Becker L, Haack T, Kremer L, Datta AN, Sperl W, Floss T, Wurst W, Chrzanowska-Lightowlers Z, De Angelis MH, Klopstock T, Prokisch H, Wenz T. MTO1 mediates tissue specificity of OXPHOS defects via tRNA modification and translation optimization, which can be bypassed by dietary intervention. Hum Mol Genet 2015; 24:2247-66. [PMID: 25552653 PMCID: PMC4380071 DOI: 10.1093/hmg/ddu743] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 12/12/2014] [Accepted: 12/22/2014] [Indexed: 11/15/2022] Open
Abstract
Mitochondrial diseases often exhibit tissue-specific pathologies, but this phenomenon is poorly understood. Here we present regulation of mitochondrial translation by the Mitochondrial Translation Optimization Factor 1, MTO1, as a novel player in this scenario. We demonstrate that MTO1 mediates tRNA modification and controls mitochondrial translation rate in a highly tissue-specific manner associated with tissue-specific OXPHOS defects. Activation of mitochondrial proteases, aberrant translation products, as well as defects in OXPHOS complex assembly observed in MTO1 deficient mice further imply that MTO1 impacts translation fidelity. In our mouse model, MTO1-related OXPHOS deficiency can be bypassed by feeding a ketogenic diet. This therapeutic intervention is independent of the MTO1-mediated tRNA modification and involves balancing of mitochondrial and cellular secondary stress responses. Our results thereby establish mammalian MTO1 as a novel factor in the tissue-specific regulation of OXPHOS and fine tuning of mitochondrial translation accuracy.
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Affiliation(s)
- Christin Tischner
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany
| | - Annette Hofer
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany
| | - Veronika Wulff
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany
| | - Joanna Stepek
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany
| | - Iulia Dumitru
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany
| | - Lore Becker
- Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians-University, Munich 80336, Germany, German Mouse Clinic, Institute of Experimental Genetics
| | - Tobias Haack
- Institute of Human Genetics, German Network for Mitochondrial Disorders (mitoNET), Germany
| | - Laura Kremer
- Institute of Human Genetics, German Network for Mitochondrial Disorders (mitoNET), Germany
| | - Alexandre N Datta
- Division of Neuropediatrics and Developmental Medicine, University Children's Hospital Basel (UKBB), University of Basel, Basel 4031, Switzerland
| | - Wolfgang Sperl
- German Network for Mitochondrial Disorders (mitoNET), Germany, Department of Pediatrics, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Thomas Floss
- Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environment and Health (GmbH), Neuherberg 85764, Germany
| | - Wolfgang Wurst
- Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environment and Health (GmbH), Neuherberg 85764, Germany, Technical University Munich, Helmholtz Zentrum München, Neuherberg 85764, Germany, DZNE-German Center for Neurodegenerative Diseases, Munich, Germany, Max Planck Institute of Psychiatry, Munich 80804, Germany, German Center for Vertigo and Balance Disorders, Munich, Germany
| | - Zofia Chrzanowska-Lightowlers
- The Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, The Medical School, Newcastle upon Tyne NE2 4HH, UK
| | - Martin Hrabe De Angelis
- German Mouse Clinic, Institute of Experimental Genetics, German Center for Vertigo and Balance Disorders, Munich, Germany, Center of Life and Food Sciences Weihenstephan, Technische Universitat München, Freising 85350, Germany, German Center for Diabetes Research (DZD), Neuherberg 85764, Germany and Technische Universität München, Freising-Weihenstephan 85354, Germany
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians-University, Munich 80336, Germany, German Mouse Clinic, Institute of Experimental Genetics, German Network for Mitochondrial Disorders (mitoNET), Germany, DZNE-German Center for Neurodegenerative Diseases, Munich, Germany, German Center for Vertigo and Balance Disorders, Munich, Germany
| | - Holger Prokisch
- Institute of Human Genetics, Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environment and Health (GmbH), Neuherberg 85764, Germany
| | - Tina Wenz
- Institute for Genetics and Cluster of Excellence: Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Str. 47A, Cologne 50674, Germany, German Network for Mitochondrial Disorders (mitoNET), Germany,
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Mutation in MRPS34 compromises protein synthesis and causes mitochondrial dysfunction. PLoS Genet 2015; 11:e1005089. [PMID: 25816300 PMCID: PMC4376678 DOI: 10.1371/journal.pgen.1005089] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 02/23/2015] [Indexed: 01/20/2023] Open
Abstract
The evolutionary divergence of mitochondrial ribosomes from their bacterial and cytoplasmic ancestors has resulted in reduced RNA content and the acquisition of mitochondria-specific proteins. The mitochondrial ribosomal protein of the small subunit 34 (MRPS34) is a mitochondria-specific ribosomal protein found only in chordates, whose function we investigated in mice carrying a homozygous mutation in the nuclear gene encoding this protein. The Mrps34 mutation causes a significant decrease of this protein, which we show is required for the stability of the 12S rRNA, the small ribosomal subunit and actively translating ribosomes. The synthesis of all 13 mitochondrially-encoded polypeptides is compromised in the mutant mice, resulting in reduced levels of mitochondrial proteins and complexes, which leads to decreased oxygen consumption and respiratory complex activity. The Mrps34 mutation causes tissue-specific molecular changes that result in heterogeneous pathology involving alterations in fractional shortening of the heart and pronounced liver dysfunction that is exacerbated with age. The defects in mitochondrial protein synthesis in the mutant mice are caused by destabilization of the small ribosomal subunit that affects the stability of the mitochondrial ribosome with age. Mitochondria make most of the energy required by eukaryotic cells and therefore they are essential for their normal function and survival. Mitochondrial function is regulated by both the mitochondrial and nuclear genome. Mutations in nuclear genes encoding mitochondrial proteins lead to mitochondrial dysfunction and consequently diminished energy production, a major symptom of metabolic and mitochondrial diseases. The molecular mechanisms that regulate mitochondrial gene expression and how dysfunction of these processes causes the pathologies observed in these diseases are not well understood. Messenger RNAs encoded by mitochondrial genomes are translated on mitochondrial ribosomes that have unique structure and protein composition. Mitochondrial ribosomes are a patchwork of core proteins that share homology with prokaryotic ribosomal proteins and mitochondria-specific proteins, which can be unique to different organisms. Mitochondria-specific ribosomal proteins have key roles in disease however their functions within mitochondria are not known. Here we show that a point mutation in a mammalian-specific ribosomal protein causes mitochondrial dysfunction, heart abnormalities and progressive liver disease. This mouse provides a valuable model to elucidate the pathogenic mechanisms and progression of metabolic diseases with age, while enabling a more thorough understanding of mitochondrial ribosomes and protein synthesis.
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Powell CA, Nicholls TJ, Minczuk M. Nuclear-encoded factors involved in post-transcriptional processing and modification of mitochondrial tRNAs in human disease. Front Genet 2015; 6:79. [PMID: 25806043 PMCID: PMC4354410 DOI: 10.3389/fgene.2015.00079] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 02/16/2015] [Indexed: 11/29/2022] Open
Abstract
The human mitochondrial genome (mtDNA) encodes 22 tRNAs (mt-tRNAs) that are necessary for the intraorganellar translation of the 13 mtDNA-encoded subunits of the mitochondrial respiratory chain complexes. Maturation of mt-tRNAs involves 5′ and 3′ nucleolytic excision from precursor RNAs, as well as extensive post-transcriptional modifications. Recent data suggest that over 7% of all mt-tRNA residues in mammals undergo post-transcriptional modification, with over 30 different modified mt-tRNA positions so far described. These processing and modification steps are necessary for proper mt-tRNA function, and are performed by dedicated, nuclear-encoded enzymes. Recent growing evidence suggests that mutations in these nuclear genes (nDNA), leading to incorrect maturation of mt-tRNAs, are a cause of human mitochondrial disease. Furthermore, mtDNA mutations in mt-tRNA genes, which may also affect mt-tRNA function, processing, and modification, are also frequently associated with human disease. In theory, all pathogenic mt-tRNA variants should be expected to affect only a single process, which is mitochondrial translation, albeit to various extents. However, the clinical manifestations of mitochondrial disorders linked to mutations in mt-tRNAs are extremely heterogeneous, ranging from defects of a single tissue to complex multisystem disorders. This review focuses on the current knowledge of nDNA coding for proteins involved in mt-tRNA maturation that have been linked to human mitochondrial pathologies. We further discuss the possibility that tissue specific regulation of mt-tRNA modifying enzymes could play an important role in the clinical heterogeneity observed for mitochondrial diseases caused by mutations in mt-tRNA genes.
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Affiliation(s)
- Christopher A Powell
- Mitochondrial Genetics, Mitochondrial Biology Unit, Medical Research Council, Cambridge, UK
| | - Thomas J Nicholls
- Mitochondrial Genetics, Mitochondrial Biology Unit, Medical Research Council, Cambridge, UK
| | - Michal Minczuk
- Mitochondrial Genetics, Mitochondrial Biology Unit, Medical Research Council, Cambridge, UK
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Hepatic Copper Accumulation: A Novel Feature in Transient Infantile Liver Failure Due to TRMU Mutations? JIMD Rep 2015; 21:109-13. [PMID: 25665837 DOI: 10.1007/8904_2014_402] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Revised: 12/18/2014] [Accepted: 12/19/2014] [Indexed: 12/13/2022] Open
Abstract
Defects in the mitochondrial respiratory chain can induce a heterogeneous range of clinical and biochemical manifestations. Hepatic involvement includes acute fulminant hepatic failure, microvesicular steatosis, neonatal non-alloimmune haemochromatosis and cirrhosis. Recently pathogenic mutations in tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase (TRMU) gene (OMIM 610230) have been demonstrated to cause transient infantile liver failure (OMIM 613070). The human TRMU gene encodes a mitochondrial protein, 5-methylaminomethyl-2-thiouridylate methyltransferase, whose molecular function is that of mitochondrial tRNA modification.We report an infant who presented with acute liver failure, in whom we observed hepatic copper intoxication and cirrhosis on liver biopsy. We postulate that the hepatic copper intoxication observed in our patient is most likely a secondary event associated with cholangiopathy. Periportal copper accumulation has been implicated in causing secondary mitochondrial dysfunction; the impact of copper accumulation in patients with TRMU mutations is unclear and warrants long-term clinical follow-up.
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Meseguer S, Martínez-Zamora A, García-Arumí E, Andreu AL, Armengod ME. The ROS-sensitive microRNA-9/9* controls the expression of mitochondrial tRNA-modifying enzymes and is involved in the molecular mechanism of MELAS syndrome. Hum Mol Genet 2014; 24:167-84. [PMID: 25149473 DOI: 10.1093/hmg/ddu427] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mitochondrial dysfunction activates mitochondria-to-nucleus signaling pathways whose components are mostly unknown. Identification of these components is important to understand the molecular mechanisms underlying mitochondrial diseases and to discover putative therapeutic targets. MELAS syndrome is a rare neurodegenerative disease caused by mutations in mitochondrial (mt) DNA affecting mt-tRNA(Leu(UUR)). Patient and cybrid cells exhibit elevated oxidative stress. Moreover, mutant mt-tRNAs(Leu(UUR)) lack the taurine-containing modification normally present at the wobble uridine (U34) of wild-type mt-tRNA(Leu(UUR)), which is considered an etiology of MELAS. However, the molecular mechanism is still unclear. We found that MELAS cybrids exhibit a significant decrease in the steady-state levels of several mt-tRNA-modification enzymes, which is not due to transcriptional regulation. We demonstrated that oxidative stress mediates an NFkB-dependent induction of microRNA-9/9*, which acts as a post-transcriptional negative regulator of the mt-tRNA-modification enzymes GTPBP3, MTO1 and TRMU. Down-regulation of these enzymes by microRNA-9/9* affects the U34 modification status of non-mutant tRNAs and contributes to the MELAS phenotype. Anti-microRNA-9 treatments of MELAS cybrids reverse the phenotype, whereas miR-9 transfection of wild-type cells mimics the effects of siRNA-mediated down-regulation of GTPBP3, MTO1 and TRMU. Our data represent the first evidence that an mt-DNA disease can directly affect microRNA expression. Moreover, we demonstrate that the modification status of mt-tRNAs is dynamic and that cells respond to stress by modulating the expression of mt-tRNA-modifying enzymes. microRNA-9/9* is a crucial player in mitochondria-to-nucleus signaling as it regulates expression of nuclear genes in response to changes in the functional state of mitochondria.
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Affiliation(s)
- Salvador Meseguer
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia 46012, Spain
| | - Ana Martínez-Zamora
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia 46012, Spain
| | - Elena García-Arumí
- Hospital Universitari Vall d'Hebron, Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona 08035, Spain Biomedical Research Networking Centre for Rare Diseases (CIBERER) (node U701), Barcelona, Spain and
| | - Antonio L Andreu
- Hospital Universitari Vall d'Hebron, Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona 08035, Spain Biomedical Research Networking Centre for Rare Diseases (CIBERER) (node U701), Barcelona, Spain and
| | - M-Eugenia Armengod
- Laboratory of RNA Modification and Mitochondrial Diseases, Centro de Investigación Príncipe Felipe, Valencia 46012, Spain CIBERER (node U721), Valencia, Spain
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36
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Boczonadi V, Horvath R. Mitochondria: impaired mitochondrial translation in human disease. Int J Biochem Cell Biol 2014; 48:77-84. [PMID: 24412566 PMCID: PMC3988845 DOI: 10.1016/j.biocel.2013.12.011] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 11/13/2013] [Accepted: 12/26/2013] [Indexed: 10/28/2022]
Abstract
Defects of the mitochondrial protein synthesis cause a subgroup of mitochondrial diseases, which are usually associated with decreased activities of multiple respiratory chain (RC) enzymes. The clinical presentations of these disorders are often disabling, progressive or fatal, affecting the brain, liver, skeletal muscle, heart and other organs. Currently there are no effective cures for these disorders and treatment is at best symptomatic. The diagnosis in patients with multiple respiratory chain complex defects is particularly difficult because of the massive number of nuclear genes potentially involved in intra-mitochondrial protein synthesis. Many of these genes are not yet linked to human disease. Whole exome sequencing rapidly changed the diagnosis of these patients by identifying the primary defect in DNA, and preventing the need for invasive and complex biochemical testing. Better understanding of the mitochondrial protein synthesis apparatus will help us to explore disease mechanisms and will provide clues for developing novel therapies.
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Affiliation(s)
- Veronika Boczonadi
- Institute of Genetic Medicine, Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, UK
| | - Rita Horvath
- Institute of Genetic Medicine, Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, UK.
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37
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He X, Zhu X, Wang X, Wang W, Dai Y, Yan Q. Nuclear modifier MTO2 modulates the aminoglycoside-sensitivity of mitochondrial 15S rRNA C1477G mutation in Saccharomyces cerevisiae. PLoS One 2013; 8:e81490. [PMID: 24339937 PMCID: PMC3858254 DOI: 10.1371/journal.pone.0081490] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 10/14/2013] [Indexed: 12/23/2022] Open
Abstract
The phenotypic manifestations of mitochondrial DNA (mtDNA) mutations are modulated by mitochondrial DNA haplotypes, nuclear modifier genes and environmental factors. The yeast mitochondrial 15S rRNA C1477G (PR or PR454) mutation corresponds to the human 12S rRNA C1494T and A1555G mutations, which are well known as primary factors for aminoglycoside-induced nonsyndromic deafness. Here we report that the deletion of the nuclear modifier gene MTO2 suppressed the aminoglycoside-sensitivity of mitochondrial 15S rRNA C1477G mutation in Saccharomyces cerevisiae. First, the strain with a single mtDNA C1477G mutation exhibited hypersensitivity to neomycin. Functional assays indicated that the steady-state transcription level of mitochondrial DNA, the mitochondrial respiratory rate, and the membrane potential decreased significantly after neomycin treatment. The impaired mitochondria could not produce sufficient energy to maintain cell viability. Second, when the mto2 null and the mitochondrial C1477G mutations co-existed (mto2(PR)), the oxygen consumption rate in the double mutant decreased markedly compared to that of the control strains (MTO2(PS), mto2(PS) and MTO2(PR)). The expression levels of the key glycolytic genes HXK2, PFK1 and PYK1 in the mto2(PR) strain were stimulated by neomycin and up-regulated by 89%, 112% and 55%, respectively. The enhanced glycolysis compensated for the respiratory energy deficits, and could be inhibited by the glycolytic enzyme inhibitor. Our findings in yeast will provide a new insight into the pathogenesis of human deafness.
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Affiliation(s)
- Xiangyu He
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiaoyu Zhu
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xuexiang Wang
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Wei Wang
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yu Dai
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Qingfeng Yan
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang, China
- * E-mail:
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Moukadiri I, Garzón MJ, Björk GR, Armengod ME. The output of the tRNA modification pathways controlled by the Escherichia coli MnmEG and MnmC enzymes depends on the growth conditions and the tRNA species. Nucleic Acids Res 2013; 42:2602-23. [PMID: 24293650 PMCID: PMC3936742 DOI: 10.1093/nar/gkt1228] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
In Escherichia coli, the MnmEG complex modifies transfer RNAs (tRNAs) decoding NNA/NNG codons. MnmEG catalyzes two different modification reactions, which add an aminomethyl (nm) or carboxymethylaminomethyl (cmnm) group to position 5 of the anticodon wobble uridine using ammonium or glycine, respectively. In and , however, cmnm5 appears as the final modification, whereas in the remaining tRNAs, the MnmEG products are converted into 5-methylaminomethyl (mnm5) through the two-domain, bi-functional enzyme MnmC. MnmC(o) transforms cmnm5 into nm5, whereas MnmC(m) converts nm5 into mnm5, thus producing an atypical network of modification pathways. We investigate the activities and tRNA specificity of MnmEG and the MnmC domains, the ability of tRNAs to follow the ammonium or glycine pathway and the effect of mnmC mutations on growth. We demonstrate that the two MnmC domains function independently of each other and that and are substrates for MnmC(m), but not MnmC(o). Synthesis of mnm5s2U by MnmEG-MnmC in vivo avoids build-up of intermediates in . We also show that MnmEG can modify all the tRNAs via the ammonium pathway. Strikingly, the net output of the MnmEG pathways in vivo depends on growth conditions and tRNA species. Loss of any MnmC activity has a biological cost under specific conditions.
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Affiliation(s)
- Ismaïl Moukadiri
- Laboratory of RNA Modification and Mitochondrial Diseases, Príncipe Felipe Research Center, 46012-Valencia, Spain, Department of Molecular Biology, Umeå University, S90187, Sweden and Biomedical Research Networking Centre for Rare Diseases (CIBERER) (node U721), Spain
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Baruffini E, Dallabona C, Invernizzi F, Yarham JW, Melchionda L, Blakely EL, Lamantea E, Donnini C, Santra S, Vijayaraghavan S, Roper HP, Burlina A, Kopajtich R, Walther A, Strom TM, Haack TB, Prokisch H, Taylor RW, Ferrero I, Zeviani M, Ghezzi D. MTO1 mutations are associated with hypertrophic cardiomyopathy and lactic acidosis and cause respiratory chain deficiency in humans and yeast. Hum Mutat 2013; 34:1501-9. [PMID: 23929671 PMCID: PMC4028987 DOI: 10.1002/humu.22393] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/10/2013] [Accepted: 07/19/2013] [Indexed: 11/10/2022]
Abstract
We report three families presenting with hypertrophic cardiomyopathy, lactic acidosis, and multiple defects of mitochondrial respiratory chain (MRC) activities. By direct sequencing of the candidate gene MTO1, encoding the mitochondrial-tRNA modifier 1, or whole exome sequencing analysis, we identified novel missense mutations. All MTO1 mutations were predicted to be deleterious on MTO1 function. Their pathogenic role was experimentally validated in a recombinant yeast model, by assessing oxidative growth, respiratory activity, mitochondrial protein synthesis, and complex IV activity. In one case, we also demonstrated that expression of wt MTO1 could rescue the respiratory defect in mutant fibroblasts. The severity of the yeast respiratory phenotypes partly correlated with the different clinical presentations observed in MTO1 mutant patients, although the clinical outcome was highly variable in patients with the same mutation and seemed also to depend on timely start of pharmacological treatment, centered on the control of lactic acidosis by dichloroacetate. Our results indicate that MTO1 mutations are commonly associated with a presentation of hypertrophic cardiomyopathy, lactic acidosis, and MRC deficiency, and that ad hoc recombinant yeast models represent a useful system to test the pathogenic potential of uncommon variants, and provide insight into their effects on the expression of a biochemical phenotype.
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40
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Zhu Q, Zhou Y, Jin X, Lin X. The role of mitochondrial tRNAPhe C628T variant in deafness expression. ACTA ACUST UNITED AC 2013; 26:2-6. [PMID: 24021014 DOI: 10.3109/19401736.2013.823192] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mutations in mitochondrial genome are one of the most important causes of hearing loss, of these, mitochondrial tRNA (mt-tRNA) genes are the hot spots for mutations associated with deafness. Most recently, a novel mt-tRNA(Phe) C628T variant has been reported to be associated with non-syndromic and sensorineural hearing loss. To test this association, we characterized the C628T variant using a phylogenetic approach; in addition, we employed the bioinformatics tool to predict the thermodynamic change of the mt-tRNA(Phe) gene with and without this variant. Intriguingly, the C628T variant was not evolutionary conserved and had little effect on mt-tRNA(Phe) folding. Moreover, through the application of the pathogenicity scoring system, we classified the C628T variant as a "neutral polymorphism", suggesting that this variant currently lacked sufficient evident to support as a "pathogenic" mutation.
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Affiliation(s)
- Qingzhang Zhu
- Taizhou Hospital of Zhejiang Province, Wenzhou Medical University , Linhai , People's Republic of China
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41
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Boczonadi V, Smith PM, Pyle A, Gomez-Duran A, Schara U, Tulinius M, Chinnery PF, Horvath R. Altered 2-thiouridylation impairs mitochondrial translation in reversible infantile respiratory chain deficiency. Hum Mol Genet 2013; 22:4602-15. [PMID: 23814040 PMCID: PMC3889809 DOI: 10.1093/hmg/ddt309] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Childhood-onset mitochondrial encephalomyopathies are severe, relentlessly progressive conditions. However, reversible infantile respiratory chain deficiency (RIRCD), due to a homoplasmic mt-tRNAGlu mutation, and reversible infantile hepatopathy, due to tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase (TRMU) deficiency, stand out by showing spontaneous recovery, and provide the key to treatments of potential broader relevance. Modification of mt-tRNAGlu is a possible functional link between these two conditions, since TRMU is responsible for 2-thiouridylation of mt-tRNAGlu, mt-tRNALys and mt-tRNAGln. Here we show that down-regulation of TRMU in RIRCD impairs 2-thiouridylation and exacerbates the effect of the mt-tRNAGlu mutation by triggering a mitochondrial translation defect in vitro. Skeletal muscle of RIRCD patients in the symptomatic phase showed significantly reduced 2-thiouridylation. Supplementation with l-cysteine, which is required for optimal TRMU function, rescued respiratory chain enzyme activities in human cell lines of patients with RIRCD as well as deficient TRMU. Our results show that l-cysteine supplementation is a potential treatment for RIRCD and for TRMU deficiency, and is likely to have broader application for the growing group of intra-mitochondrial translation disorders.
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Affiliation(s)
- Veronika Boczonadi
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK
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42
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Gaignard P, Gonzales E, Ackermann O, Labrune P, Correia I, Therond P, Jacquemin E, Slama A. Mitochondrial Infantile Liver Disease due to TRMU Gene Mutations: Three New Cases. JIMD Rep 2013; 11:117-23. [PMID: 23625533 DOI: 10.1007/8904_2013_230] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 04/01/2013] [Accepted: 04/02/2013] [Indexed: 12/03/2022] Open
Abstract
Combined respiratory chain defect is a common feature in mitochondrial liver disease during early infancy. Mitochondrial DNA depletions, induced by mutations of the nuclear genes POLG, DGUOK, and MPV17, are the major causes of these combined deficiencies. More recently, mutations in TRMU gene encoding the mitochondrial tRNA-specific 2-thiouridylase were found in infantile hepatopathy related to mitochondrial translation defect. It is characterized by a combined defect of respiratory chain complexes without mitochondrial DNA depletion.We report here clinical, biochemical, and genetic findings from three unrelated children presenting with hepatopathy associated with hyperlactatemia and respiratory chain defect due to bi-allelic mutations in TRMU gene. Two patients recovered spontaneously in a few months, whereas the other one died of acute liver failure. Spontaneous remission is a rare feature in mitochondrial liver diseases, and early identification of TRMU mutations could impact on clinical management. Our results extend the small number of TRMU mutations reported in mitochondrial liver disorders and allowed accumulating data for genotype-phenotype correlation.
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Affiliation(s)
- Pauline Gaignard
- Laboratoire de biochimie, AP-HP, Hôpital Bicêtre, Hôpitaux Universitaires Paris-Sud, 78 rue du Général Leclerc, Le Kremlin-Bicêtre Cedex, 94275, France
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43
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Luo LF, Hou CC, Yang WX. Nuclear factors: roles related to mitochondrial deafness. Gene 2013; 520:79-89. [PMID: 23510774 DOI: 10.1016/j.gene.2013.03.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 03/08/2013] [Indexed: 12/16/2022]
Abstract
Hearing loss (HL) is a common disorder with mitochondrial dysfunction as one of the major causes leading to deafness. Mitochondrial dysfunction may be caused by either mutations in nuclear genes leading to defective nuclear-encoded proteins or mutations in mitochondrial genes leading to defective mitochondrial-encoded products. The specific nuclear genes involved in HL can be classified into two categories depending on whether mitochondrial gene mutations co-exist (modifier genes) or not (deafness-causing genes). TFB1M, MTO1, GTPBP3, and TRMU are modifier genes. A mutation in any of these modifier genes may lead to a deafness phenotype when accompanied by the mitochondrial gene mutation. OPA1, TIMM8A, SMAC/DIABLO, MPV17, PDSS1, BCS1L, SUCLA2, C10ORF2, COX10, PLOG1and RRM2B are deafness-causing genes. A mutation in any of these deafness-causing genes will directly induce variable phenotypic HL.
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Affiliation(s)
- Ling-Feng Luo
- Institute of Cell and Developmental Biology, Zhejiang University, Hangzhou 310058, China
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44
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Jackman JE, Alfonzo JD. Transfer RNA modifications: nature's combinatorial chemistry playground. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 4:35-48. [PMID: 23139145 DOI: 10.1002/wrna.1144] [Citation(s) in RCA: 222] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Following synthesis, tRNAs are peppered by numerous chemical modifications which may differentially affect a tRNA's structure and function. Although modifications affecting the business ends of a tRNA are predictably important for cell viability, a majority of modifications play more subtle structural roles that can affect tRNA stability and folding. The current trend is that modifications act in concert and it is in the context of the specific sequence of a given tRNA that they impart their differing effects. Recent developments in the modification field have highlighted the diversity of modifications in tRNA. From these, the combinatorial nature of modifications in explaining previously described phenotypes derived from their absence has emerged as a growing theme.
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Affiliation(s)
- Jane E Jackman
- The Ohio State Center for RNA Biology, The Ohio State University, Columbus, OH, USA.
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45
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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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46
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Ghezzi D, Baruffini E, Haack TB, Invernizzi F, Melchionda L, Dallabona C, Strom TM, Parini R, Burlina AB, Meitinger T, Prokisch H, Ferrero I, Zeviani M. Mutations of the mitochondrial-tRNA modifier MTO1 cause hypertrophic cardiomyopathy and lactic acidosis. Am J Hum Genet 2012; 90:1079-87. [PMID: 22608499 DOI: 10.1016/j.ajhg.2012.04.011] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 03/06/2012] [Accepted: 04/12/2012] [Indexed: 11/17/2022] Open
Abstract
Dysfunction of mitochondrial respiration is an increasingly recognized cause of isolated hypertrophic cardiomyopathy. To gain insight into the genetic origin of this condition, we used next-generation exome sequencing to identify mutations in MTO1, which encodes mitochondrial translation optimization 1. Two affected siblings carried a maternal c.1858dup (p.Arg620Lysfs(∗)8) frameshift and a paternal c.1282G>A (p.Ala428Thr) missense mutation. A third unrelated individual was homozygous for the latter change. In both humans and yeast, MTO1 increases the accuracy and efficiency of mtDNA translation by catalyzing the 5-carboxymethylaminomethylation of the wobble uridine base in three mitochondrial tRNAs (mt-tRNAs). Accordingly, mutant muscle and fibroblasts showed variably combined reduction in mtDNA-dependent respiratory chain activities. Reduced respiration in mutant cells was corrected by expressing a wild-type MTO1 cDNA. Conversely, defective respiration of a yeast mto1Δ strain failed to be corrected by an Mto1(Pro622∗) variant, equivalent to human MTO1(Arg620Lysfs∗8), whereas incomplete correction was achieved by an Mto1(Ala431Thr) variant, corresponding to human MTO1(Ala428Thr). The respiratory yeast phenotype was dramatically worsened in stress conditions and in the presence of a paromomycin-resistant (P(R)) mitochondrial rRNA mutation. Lastly, in vivo mtDNA translation was impaired in the mutant yeast strains.
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Affiliation(s)
- Daniele Ghezzi
- Unit of Molecular Neurogenetics, Fondazione IRCCS, Milan, Italy
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Sasarman F, Nishimura T, Thiffault I, Shoubridge EA. A novel mutation in YARS2 causes myopathy with lactic acidosis and sideroblastic anemia. Hum Mutat 2012; 33:1201-6. [PMID: 22504945 DOI: 10.1002/humu.22098] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 03/30/2012] [Indexed: 11/08/2022]
Abstract
Mutations in the mitochondrial aminoacyl-tRNA synthetases (ARSs) are associated with a strikingly broad range of clinical phenotypes, the molecular basis for which remains obscure. Here, we report a novel missense mutation (c.137G>A, p.Gly46Asp) in the catalytic domain of YARS2, which codes for the mitochondrial tyrosyl-tRNA synthetase, in a subject with myopathy, lactic acidosis, and sideroblastic anemia (MLASA). YARS2 was undetectable by immunoblot analysis in subject myoblasts, resulting in a generalized mitochondrial translation defect. Retroviral expression of a wild-type YARS2 complementary DNA completely rescued the translation defect. We previously demonstrated that the respiratory chain defect in this subject was only present in fully differentiated muscle, and we show here that this likely reflects an increased requirement for YARS2 as muscle cells differentiate. An additional, heterozygous mutation was detected in TRMU/MTU1, a gene encoding the mitochondrial 2-thiouridylase. Although subject myoblasts and myotubes contained half the normal levels of TRMU, thiolation of mitochondrial tRNAs was normal. YARS2 eluted as part of high-molecular-weight complexes of ∼250 kDa and 1 MDa by gel filtration. This study confirms mutations in YARS2 as a cause of MLASA and shows that, like some of the cytoplasmic ARSs, mitochondrial ARSs occur in high-molecular-weight complexes.
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Affiliation(s)
- Florin Sasarman
- Montreal Neurological Institute, McGill University, Montreal, Canada
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Armengod ME, Moukadiri I, Prado S, Ruiz-Partida R, Benítez-Páez A, Villarroya M, Lomas R, Garzón MJ, Martínez-Zamora A, Meseguer S, Navarro-González C. Enzymology of tRNA modification in the bacterial MnmEG pathway. Biochimie 2012; 94:1510-20. [PMID: 22386868 DOI: 10.1016/j.biochi.2012.02.019] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 02/16/2012] [Indexed: 10/28/2022]
Abstract
Among all RNAs, tRNA exhibits the largest number and the widest variety of post-transcriptional modifications. Modifications within the anticodon stem loop, mainly at the wobble position and purine-37, collectively contribute to stabilize the codon-anticodon pairing, maintain the translational reading frame, facilitate the engagement of the ribosomal decoding site and enable translocation of tRNA from the A-site to the P-site of the ribosome. Modifications at the wobble uridine (U34) of tRNAs reading two degenerate codons ending in purine are complex and result from the activity of two multi-enzyme pathways, the IscS-MnmA and MnmEG pathways, which independently work on positions 2 and 5 of the U34 pyrimidine ring, respectively, and from a third pathway, controlled by TrmL (YibK), that modifies the 2'-hydroxyl group of the ribose. MnmEG is the only common pathway to all the mentioned tRNAs, and involves the GTP- and FAD-dependent activity of the MnmEG complex and, in some cases, the activity of the bifunctional enzyme MnmC. The Escherichia coli MnmEG complex catalyzes the incorporation of an aminomethyl group into the C5 atom of U34 using methylene-tetrahydrofolate and glycine or ammonium as donors. The reaction requires GTP hydrolysis, probably to assemble the active site of the enzyme or to carry out substrate recognition. Inactivation of the evolutionarily conserved MnmEG pathway produces a pleiotropic phenotype in bacteria and mitochondrial dysfunction in human cell lines. While the IscS-MnmA pathway and the MnmA-mediated thiouridylation reaction are relatively well understood, we have limited information on the reactions mediated by the MnmEG, MnmC and TrmL enzymes and on the precise role of proteins MnmE and MnmG in the MnmEG complex activity. This review summarizes the present state of knowledge on these pathways and what we still need to know, with special emphasis on the MnmEG pathway.
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Affiliation(s)
- M-Eugenia Armengod
- Laboratorio de Genética Molecular, Centro de Investigación Príncipe Felipe, Molecular Genetics, Avenida Autopista del Saler, 16-3, 46012-Valencia, Spain.
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