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Ahmad RN, Zhang LT, Morita R, Tani H, Wu Y, Chujo T, Ogawa A, Harada R, Shigeta Y, Tomizawa K, Wei FY. Pathological mutations promote proteolysis of mitochondrial tRNA-specific 2-thiouridylase 1 (MTU1) via mitochondrial caseinolytic peptidase (CLPP). Nucleic Acids Res 2024; 52:1341-1358. [PMID: 38113276 PMCID: PMC10853782 DOI: 10.1093/nar/gkad1197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 11/22/2023] [Accepted: 12/01/2023] [Indexed: 12/21/2023] Open
Abstract
MTU1 controls intramitochondrial protein synthesis by catalyzing the 2-thiouridine modification of mitochondrial transfer RNAs (mt-tRNAs). Missense mutations in the MTU1 gene are associated with life-threatening reversible infantile hepatic failure. However, the molecular pathogenesis is not well understood. Here, we investigated 17 mutations associated with this disease, and our results showed that most disease-related mutations are partial loss-of-function mutations, with three mutations being particularly severe. Mutant MTU1 is rapidly degraded by mitochondrial caseinolytic peptidase (CLPP) through a direct interaction with its chaperone protein CLPX. Notably, knockdown of CLPP significantly increased mutant MTU1 protein expression and mt-tRNA 2-thiolation, suggesting that accelerated proteolysis of mutant MTU1 plays a role in disease pathogenesis. In addition, molecular dynamics simulations demonstrated that disease-associated mutations may lead to abnormal intermolecular interactions, thereby impairing MTU1 enzyme activity. Finally, clinical data analysis underscores a significant correlation between patient prognosis and residual 2-thiolation levels, which is partially consistent with the AlphaMissense predictions. These findings provide a comprehensive understanding of MTU1-related diseases, offering prospects for modification-based diagnostics and novel therapeutic strategies centered on targeting CLPP.
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Affiliation(s)
- Raja Norazireen Raja Ahmad
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Kumamoto, 860-8556, Japan
- Department of Modomics Biology and Medicine, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, 980-8575, Japan
| | - Long-Teng Zhang
- Department of Modomics Biology and Medicine, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, 980-8575, Japan
| | - Rikuri Morita
- Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8577, Japan
| | - Haruna Tani
- Department of Modomics Biology and Medicine, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, 980-8575, Japan
| | - Yong Wu
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Kumamoto, 860-8556, Japan
| | - Takeshi Chujo
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Kumamoto, 860-8556, Japan
| | - Akiko Ogawa
- Department of Modomics Biology and Medicine, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, 980-8575, Japan
| | - Ryuhei Harada
- Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8577, Japan
| | - Yasuteru Shigeta
- Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8577, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Kumamoto, 860-8556, Japan
| | - Fan-Yan Wei
- Department of Modomics Biology and Medicine, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, 980-8575, Japan
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2
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OUP accepted manuscript. Hum Mol Genet 2022; 31:3068-3082. [DOI: 10.1093/hmg/ddac096] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/28/2022] [Accepted: 04/20/2022] [Indexed: 11/14/2022] Open
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3
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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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Rebelo-Guiomar P, Powell CA, Van Haute L, Minczuk M. The mammalian mitochondrial epitranscriptome. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1862:429-446. [PMID: 30529456 PMCID: PMC6414753 DOI: 10.1016/j.bbagrm.2018.11.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/16/2018] [Accepted: 11/23/2018] [Indexed: 01/08/2023]
Abstract
Correct expression of the mitochondrially-encoded genes is critical for the production of the components of the oxidative phosphorylation machinery. Post-transcriptional modifications of mitochondrial transcripts have been emerging as an important regulatory feature of mitochondrial gene expression. Here we review the current knowledge on how the mammalian mitochondrial epitranscriptome participates in regulating mitochondrial homeostasis. In particular, we focus on the latest breakthroughs made towards understanding the roles of the modified nucleotides in mitochondrially-encoded ribosomal and transfer RNAs, the enzymes responsible for introducing these modifications and on recent transcriptome-wide studies reporting modifications to mitochondrial messenger RNAs. This article is part of a Special Issue entitled: mRNA modifications in gene expression control edited by Dr. Matthias Soller and Dr. Rupert Fray. Human mtDNA encodes 13 proteins and all the RNAs necessary for their expression Post-transcriptional modifications of RNA, the epitranscriptome, play a regulatory role in mitochondrial gene expression Several enzymes involved in the shaping of the mitochondrial epitranscriptome have recently been characterised. Our understanding of the extent and nature of mtRNA modifications is rapidly expanding. Recent transcriptome-wide studies suggest modifications in mitochondrial mRNAs
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Affiliation(s)
- Pedro Rebelo-Guiomar
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK; Graduate Program in Areas of Basic and Applied Biology (GABBA), University of Porto, Porto, Portugal
| | | | - Lindsey Van Haute
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
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5
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Kamps R, Szklarczyk R, Theunissen TE, Hellebrekers DMEI, Sallevelt SCEH, Boesten IB, de Koning B, van den Bosch BJ, Salomons GS, Simas-Mendes M, Verdijk R, Schoonderwoerd K, de Coo IFM, Vanoevelen JM, Smeets HJM. Genetic defects in mtDNA-encoded protein translation cause pediatric, mitochondrial cardiomyopathy with early-onset brain disease. Eur J Hum Genet 2018; 26:537-551. [PMID: 29440775 PMCID: PMC5891491 DOI: 10.1038/s41431-017-0058-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 11/17/2017] [Accepted: 11/23/2017] [Indexed: 01/10/2023] Open
Abstract
This study aims to identify gene defects in pediatric cardiomyopathy and early-onset brain disease with oxidative phosphorylation (OXPHOS) deficiencies. We applied whole-exome sequencing in three patients with pediatric cardiomyopathy and early-onset brain disease with OXPHOS deficiencies. The brain pathology was studied by MRI analysis. In consanguineous patient 1, we identified a homozygous intronic variant (c.850-3A > G) in the QRSL1 gene, which was predicted to cause abnormal splicing. The variant segregated with the disease and affected the protein function, which was confirmed by complementation studies, restoring OXPHOS function only with wild-type QRSL1. Patient 2 was compound heterozygous for two novel affected and disease-causing variants (c.[253G > A];[938G > A]) in the MTO1 gene. In patient 3, we detected one unknown affected and disease-causing variants (c.2872C > T) and one known disease-causing variant (c.1774C > T) in the AARS2 gene. The c.1774C > T variant was present in the paternal copy of the AARS2 gene, the c.2872C > T in the maternal copy. All genes were involved in translation of mtDNA-encoded proteins. Defects in mtDNA-encoded protein translation lead to severe pediatric cardiomyopathy and brain disease with OXPHOS abnormalities. This suggests that the heart and brain are particularly sensitive to defects in mitochondrial protein synthesis during late embryonic or early postnatal development, probably due to the massive mitochondrial biogenesis occurring at that stage. If both the heart and brain are involved, the prognosis is poor with a likely fatal outcome at young age.
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Affiliation(s)
- Rick Kamps
- Department of Genetics and Cell Biology, Maastricht University, Maastricht, The Netherlands
- School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Radek Szklarczyk
- Department of Genetics and Cell Biology, Maastricht University, Maastricht, The Netherlands
| | - Tom E Theunissen
- Department of Genetics and Cell Biology, Maastricht University, Maastricht, The Netherlands
| | | | | | - Iris B Boesten
- Department of Clinical Genetics, MUMC, Maastricht, The Netherlands
| | - Bart de Koning
- Department of Clinical Genetics, MUMC, Maastricht, The Netherlands
| | | | - Gajja S Salomons
- Department of Clinical Chemistry, VU University Medical Center/Neuroscience Campus Amsterdam, Amsterdam, The Netherlands
| | - Marisa Simas-Mendes
- Department of Clinical Chemistry, VU University Medical Center/Neuroscience Campus Amsterdam, Amsterdam, The Netherlands
| | - Rob Verdijk
- Department of Pathology, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Kees Schoonderwoerd
- Department of Clinical Genetics, Erasmus Medical Centre, Rotterdam, The Netherlands
| | | | - Jo M Vanoevelen
- Department of Genetics and Cell Biology, Maastricht University, Maastricht, The Netherlands
- Department of Clinical Genetics, MUMC, Maastricht, The Netherlands
| | - Hubert J M Smeets
- Department of Genetics and Cell Biology, Maastricht University, Maastricht, The Netherlands.
- School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands.
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6
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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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7
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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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8
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Alves RM, da Silva Costa SM, do Amôr Divino Miranda PM, Ramos PZ, Marconi TG, Santos Oliveira G, Castilho AM, Sartorato EL. Analysis of mitochondrial alterations in Brazilian patients with sensorineural hearing loss using MALDI-TOF mass spectrometry. BMC MEDICAL GENETICS 2016; 17:41. [PMID: 27230773 PMCID: PMC4880863 DOI: 10.1186/s12881-016-0303-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 05/20/2016] [Indexed: 02/06/2023]
Abstract
BACKGROUND Mutations in the mitochondrial DNA (mtDNA) have been associated with aminoglycoside-induced and nonsyndromic deafness in different populations. In the present study, we investigated the contribution of mutations in mitochondrial genes to the etiology of hearing loss in a Brazilian sample. METHODS Using mass spectrometry genotyping technology, combined with direct sequencing, 50 alterations previously described in 14 mitochondrial genes were screened in 152 patients with sensorineural hearing loss and in104 normal hearing controls. RESULTS Fifteen known mitochondrial alterations were detected (G709A, A735G, A827G, G988A, A1555G, T4363C, T5628C, T5655C, G5821A, C7462T, G8363A, T10454C, G12236A, T1291C, G15927A). Pathogenic mutations in MT-RNR1 and MT-TK genes were detected in 3 % (5/152) of the patients with hearing loss. CONCLUSIONS This study contributed to show the spectrum of mitochondrial variants in Brazilian patients with hearing loss. Frequency of A1555G was relatively high (2.6 %), indicating that this mutation is an important cause of hearing loss in our population. This work reports for the first time the investigation and the detection of the tRNA(Lys) G8363A mutation in Brazilian patients with maternally inherited sensorineural hearing loss.
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Affiliation(s)
- Rogério Marins Alves
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Sueli Matilde da Silva Costa
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Paulo Mauricio do Amôr Divino Miranda
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Priscila Zonzini Ramos
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Thiago Gibbin Marconi
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Gisele Santos Oliveira
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil
| | - Arthur Menino Castilho
- Otology, Audiology and Implantable Ear Prostheses, University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Campinas, São Paulo, Brazil
| | - Edi Lúcia Sartorato
- Center for Molecular and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Avenida Cândido Rondon 400, PO Box 6010, 13083-875, Campinas, São Paulo, Brazil.
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9
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Van Haute L, Pearce SF, Powell CA, D’Souza AR, Nicholls TJ, Minczuk M. Mitochondrial transcript maturation and its disorders. J Inherit Metab Dis 2015; 38:655-80. [PMID: 26016801 PMCID: PMC4493943 DOI: 10.1007/s10545-015-9859-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/27/2015] [Accepted: 04/29/2015] [Indexed: 11/03/2022]
Abstract
Mitochondrial respiratory chain deficiencies exhibit a wide spectrum of clinical presentations owing to defective mitochondrial energy production through oxidative phosphorylation. These defects can be caused by either mutations in the mitochondrial DNA (mtDNA) or mutations in nuclear genes coding for mitochondrially-targeted proteins. The underlying pathomechanisms can affect numerous pathways involved in mitochondrial biology including expression of mtDNA-encoded genes. Expression of the mitochondrial genes is extensively regulated at the post-transcriptional stage and entails nucleolytic cleavage of precursor RNAs, RNA nucleotide modifications, RNA polyadenylation, RNA quality and stability control. These processes ensure proper mitochondrial RNA (mtRNA) function, and are regulated by dedicated, nuclear-encoded enzymes. Recent growing evidence suggests that mutations in these nuclear genes, leading to incorrect maturation of RNAs, are a cause of human mitochondrial disease. Additionally, mutations in mtDNA-encoded genes may also affect RNA maturation and are frequently associated with human disease. We review the current knowledge on a subset of nuclear-encoded genes coding for proteins involved in mitochondrial RNA maturation, for which genetic variants impacting upon mitochondrial pathophysiology have been reported. Also, primary pathological mtDNA mutations with recognised effects upon RNA processing are described.
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Affiliation(s)
| | - Sarah F. Pearce
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
| | | | - Aaron R. D’Souza
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
| | - Thomas J. Nicholls
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY UK
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10
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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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11
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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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12
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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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13
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Abstract
Mutations in the human mitochondrial genome are known to cause an array of diverse disorders, most of which are maternally inherited, and all of which are associated with defects in oxidative energy metabolism. It is now emerging that somatic mutations in mitochondrial DNA (mtDNA) are also linked to other complex traits, including neurodegenerative diseases, ageing and cancer. Here we discuss insights into the roles of mtDNA mutations in a wide variety of diseases, highlighting the interesting genetic characteristics of the mitochondrial genome and challenges in studying its contribution to pathogenesis.
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14
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Christian BE, Spremulli LL. Mechanism of protein biosynthesis in mammalian mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1819:1035-54. [PMID: 22172991 DOI: 10.1016/j.bbagrm.2011.11.009] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 11/03/2011] [Accepted: 11/08/2011] [Indexed: 01/25/2023]
Abstract
Protein synthesis in mammalian mitochondria produces 13 proteins that are essential subunits of the oxidative phosphorylation complexes. This review provides a detailed outline of each phase of mitochondrial translation including initiation, elongation, termination, and ribosome recycling. The roles of essential proteins involved in each phase are described. All of the products of mitochondrial protein synthesis in mammals are inserted into the inner membrane. Several proteins that may help bind ribosomes to the membrane during translation are described, although much remains to be learned about this process. Mutations in mitochondrial or nuclear genes encoding components of the translation system often lead to severe deficiencies in oxidative phosphorylation, and a summary of these mutations is provided. This article is part of a Special Issue entitled: Mitochondrial Gene Expression.
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Affiliation(s)
- Brooke E Christian
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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15
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Schara U, von Kleist-Retzow JC, Lainka E, Gerner P, Pyle A, Smith PM, Lochmüller H, Czermin B, Abicht A, Holinski-Feder E, Horvath R. Acute liver failure with subsequent cirrhosis as the primary manifestation of TRMU mutations. J Inherit Metab Dis 2011; 34:197-201. [PMID: 21153446 DOI: 10.1007/s10545-010-9250-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 11/03/2010] [Accepted: 11/08/2010] [Indexed: 10/18/2022]
Abstract
Combined respiratory chain deficiency accounts for about 30% of mitochondrial respiratory chain deficiencies and is frequently associated with mtDNA depletion, deletions or point mutations. However combined respiratory chain deficiency may also be caused by mutations in nuclear genes affecting mitochondrial translation. Here we describe a 2-year-old girl, who developed an acute, isolated, severe liver failure with mitochondrial pathology and decreased respiratory chain enzyme activities both in liver and skeletal muscle at 4 months of age. Her liver function improved significantly within a month, liver function tests returned to normal. Liver cirrhosis remained without any further complications so far. Pathogenic compound heterozygous mutations were identified in the TRMU gene. This condition is one of the few mitochondrial disorders with a life-threatening onset showing recovery later in life, therefore a prompt diagnosis and treatment of these patients has great importance in clinical practice. We suggest that TRMU deficiency should be considered in infants with acute liver disease.
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Affiliation(s)
- Ulrike Schara
- Pediatric Neurology, University of Essen, Essen, Germany
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16
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Yan D, Liu XZ. Modifiers of hearing impairment in humans and mice. Curr Genomics 2010; 11:269-78. [PMID: 21119891 PMCID: PMC2930666 DOI: 10.2174/138920210791233054] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 04/03/2010] [Accepted: 04/07/2010] [Indexed: 02/04/2023] Open
Abstract
Lack of penetrance and variability of expression are common findings in nonsyndromic hearing loss with autosomal dominant mode of inheritance, but are also seen with recessive inheritance. Now we know that genotype cannot necessarily predict phenotype due to the complexity of the genome, the proteome interacting with the transcriptome, and the dynamically coupled systems that are involved. The contribution of genetic background to phenotypic diversity reflects the additive and interactive (epistasis) effects of multiple genes. Because, individual genes do not act alone but rather in concert with many other genes, it is not surprising that, modifier genes are common source of phenotypic variation in human populations. They can affect the phenotypic outcome of a given genotype by interacting in the same or in a parallel biological pathway as the disease gene. These modifier genes modulate penetrance, dominance, pleiotropy or expressivity in individuals with Mendelian traits and can also be exerted by influencing the severity, the penetrance, the age of onset and the progression of a disease. In this review, we focus on modifier genes that specifically affect hearing loss phenotypes in humans as well as those described in mice. We also include examples of digenic inheritance of deafness, because additive or interactive effects can also result from interaction between two mutant genes.
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Affiliation(s)
| | - Xue-Zhong Liu
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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17
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Bénit P, El-Khoury R, Schiff M, Sainsard-Chanet A, Rustin P. Genetic background influences mitochondrial function: modeling mitochondrial disease for therapeutic development. Trends Mol Med 2010; 16:210-7. [PMID: 20382561 DOI: 10.1016/j.molmed.2010.03.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 03/11/2010] [Accepted: 03/15/2010] [Indexed: 12/21/2022]
Abstract
Genetic background strongly influences the phenotype of human mitochondrial diseases. Mitochondrial biogenesis and function require up to 1500 nuclear genes, providing myriad opportunities for effects on disease expression. Phenotypic variability, combined with relative rarity, constitutes a major obstacle to establish cohorts for clinical trials. Animal models are, therefore, potentially valuable. However, several of these show no or very mild disease phenotypes compared with patients and can not be used for therapeutic studies. One reason might be the insufficient attention paid to the need for genetic diversity in order to capture the effects of genetic background on disease expression. Here, we use data from various models to emphasize the need to preserve genetic diversity when studying mitochondrial disease phenotypes or drug effects.
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18
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Bykhovskaya Y, Mengesha E, Fischel-Ghodsian N. Phenotypic expression of maternally inherited deafness is affected by RNA modification and cytoplasmic ribosomal proteins. Mol Genet Metab 2009; 97:297-304. [PMID: 19482502 PMCID: PMC2728627 DOI: 10.1016/j.ymgme.2009.05.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 04/30/2009] [Accepted: 05/02/2009] [Indexed: 01/06/2023]
Abstract
The homoplasmic mitochondrial A1555G mutation in the 12S rRNA gene leads to a mitochondrial translation disorder associated with deafness. The absence of disease in non-cochlear tissues in all patients, and in the cochlea in some patients, is not well understood. We used a system-based approach, including whole genome expression and biological function analysis, to elucidate the pathways underlying tissue specificity and clinical severity of this condition. Levels of over 48K RNA transcripts from EBV-transformed lymphoblasts of deaf and hearing individuals with the A1555G mutation and controls were obtained. Differentially expressed transcripts were functionally grouped using gene set enrichment analysis. Over 50 RNA binding proteins were differentially expressed between deaf and hearing individuals with the A1555G mutation (P-value of 2.56E-7), confirming previous genetic data implicating this pathway in the determination of the severity of hearing loss. Unexpectedly, the majority of cytoplasmic ribosomal genes were up-regulated in a coordinated fashion in individuals with the A1555G mutation versus controls (P-value of 3.91E-135). This finding was verified through real time RT-PCR, and through measuring of protein levels by flow cytometry. Analysis of expression levels of other differentially expressed genes suggests that this coordinated over-expression of cytoplasmic ribosomal proteins might occur through the Myc/Max pathway. We propose that expression levels of RNA binding proteins help determine the severity of the cochlear phenotype, and that coordinated up-regulation of the cytoplasmic translation apparatus operates as a compensation mechanism in unaffected tissues of patients with maternal deafness associated with the A1555G mutation.
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Affiliation(s)
- Yelena Bykhovskaya
- Medical Genetics Institute, Ahmanson Department of Pediatrics, Steven Spielberg Pediatric Research Center, Cedars-Sinai Medical Center and David Geffen School of Medicine at UCLA, 8700 Beverly Blvd, Los Angeles, California, 90048 USA
| | - Emebet Mengesha
- Medical Genetics Institute, Ahmanson Department of Pediatrics, Steven Spielberg Pediatric Research Center, Cedars-Sinai Medical Center and David Geffen School of Medicine at UCLA, 8700 Beverly Blvd, Los Angeles, California, 90048 USA
| | - Nathan Fischel-Ghodsian
- Medical Genetics Institute, Ahmanson Department of Pediatrics, Steven Spielberg Pediatric Research Center, Cedars-Sinai Medical Center and David Geffen School of Medicine at UCLA, 8700 Beverly Blvd, Los Angeles, California, 90048 USA
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19
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A South African family with the mitochondrial A1555G mutation on haplogroup L0d. Biochem Biophys Res Commun 2009; 382:390-4. [DOI: 10.1016/j.bbrc.2009.03.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 03/06/2009] [Indexed: 11/24/2022]
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20
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Zhu X, Peng X, Guan MX, Yan Q. Pathogenic mutations of nuclear genes associated with mitochondrial disorders. Acta Biochim Biophys Sin (Shanghai) 2009; 41:179-87. [PMID: 19280056 DOI: 10.1093/abbs/gmn021] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mitochondrial disorders are clinical phenotypes associated with mitochondrial dysfunction, which can be caused by mutations in mitochondrial DNA (mtDNA) or nuclear genes. In this review, we summarized the pathogenic mutations of nuclear genes associated with mitochondrial disorders. These nuclear genes encode, components of mitochondrial translational machinery and structural subunits and assembly factors of the oxidative phosphorylation, that complex. The molecular mechanisms, that nuclear modifier genes modulate the phenotypic expression of mtDNA mutations, are discussed in detail.
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Affiliation(s)
- Xiaoyu Zhu
- College of Life Science, Zhejiang University, Hangzhou 310058, Peopleos Republic of China
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21
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Study of modifiers factors associated to mitochondrial mutations in individuals with hearing impairment. Biochem Biophys Res Commun 2009; 381:210-3. [PMID: 19338775 DOI: 10.1016/j.bbrc.2009.02.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Accepted: 02/06/2009] [Indexed: 11/22/2022]
Abstract
Hearing impairment is the most prevalent sensorial deficit in the general population. Congenital deafness occurs in about 1 in 1000 live births, of which approximately 50% has hereditary cause in development countries. Non-syndromic deafness can be caused by mutations in both nuclear and mitochondrial genes. Mutations in mtDNA have been associated with aminoglycoside-induced and non-syndromic deafness in many families worldwide. However, the nuclear background influences the phenotypic expression of these pathogenic mutations. Indeed, it has been proposed that nuclear modifier genes modulate the phenotypic manifestation of the mitochondrial A1555G mutation in the MTRNR1 gene. The both putative nuclear modifiers genes TRMU and MTO1 encoding a highly conserved mitochondrial related to tRNA modification. It has been hypothesizes that human TRMU and also MTO1 nuclear genes may modulate the phenotypic manifestation of deafness-associated mitochondrial mutations. The aim of this work was to elucidate the contribution of mitochondrial mutations, nuclear modifier genes mutations and aminoglycoside exposure in the deafness phenotype. Our findings suggest that the genetic background of individuals may play an important role in the pathogenesis of deafness-associated with mitochondrial mutation and aminoglycoside-induced.
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22
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Bindu LH, Reddy PP. Genetics of aminoglycoside-induced and prelingual non-syndromic mitochondrial hearing impairment: a review. Int J Audiol 2009; 47:702-7. [PMID: 19031229 DOI: 10.1080/14992020802215862] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Pathogenic mitochondrial DNA mutations are most often implicated in inherited and acquired hearing impairment. The current review mainly focuses on the 12S rRNA mitochondrial gene mutations associated with non-syndromic deafness without or after aminoglycosides exposure. Aminoglycoside-induced and nonsyndromic deafness has been shown to have a genetic susceptibility and the pathogenic mitochondrial 12S rRNA A1555G mutation was identified as the primary factor underlying the hearing loss in many familial as well as in genetically unrelated cases, particularly in Asian populations where aminoglycoside antibiotics are commonly used even for minor infections. Many families were shown to transmit the aminoglycoside ototoxicity through matrilineal inheritance and the A1555G mutation in the 12S rRNA gene was frequently identified. The aminoglycoside antibiotics are believed to target the mitochondrial ribosome in the cochlea resulting in abnormal RNA processing or decreased efficiency of translation thereby leading to irreversible auditory dysfunction. Such cases may have a genetic predisposition to aminoglycoside ototoxicity following autosomal dominant, autosomal recessive, X-linked, or mitochondrial pattern of inheritance.
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Affiliation(s)
- L Hema Bindu
- Department of Environmental Toxicology, Institute of Genetics and Hospital for Genetic Diseases, Osmania University, Hyderabad, India
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23
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Characterization of human GTPBP3, a GTP-binding protein involved in mitochondrial tRNA modification. Mol Cell Biol 2008; 28:7514-31. [PMID: 18852288 DOI: 10.1128/mcb.00946-08] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human GTPBP3 is an evolutionarily conserved, multidomain protein involved in mitochondrial tRNA modification. Characterization of its biochemical properties and the phenotype conferred by GTPBP3 inactivation is crucial to understanding the role of this protein in tRNA maturation and its effects on mitochondrial respiration. We show that the two most abundant GTPBP3 isoforms exhibit moderate affinity for guanine nucleotides like their bacterial homologue, MnmE, although they hydrolyze GTP at a 100-fold lower rate. This suggests that regulation of the GTPase activity, essential for the tRNA modification function of MnmE, is different in GTPBP3. In fact, potassium-induced dimerization of the G domain leads to stimulation of the GTPase activity in MnmE but not in GTPBP3. The GTPBP3 N-terminal domain mediates a potassium-independent dimerization, which appears as an evolutionarily conserved property of the protein family, probably related to the construction of the binding site for the one-carbon-unit donor in the modification reaction. Partial inactivation of GTPBP3 by small interfering RNA reduces oxygen consumption, ATP production, and mitochondrial protein synthesis, while the degradation of these proteins slightly increases. It also results in mitochondria with defective membrane potential and increased superoxide levels. These phenotypic traits suggest that GTPBP3 defects contribute to the pathogenesis of some oxidative phosphorylation diseases.
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24
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Chaig MR, Zernotti ME, Soria NW, Romero OF, Romero MF, Gerez NM. A mutation in mitochondrial 12S rRNA, A827G, in Argentinean family with hearing loss after aminoglycoside treatment. Biochem Biophys Res Commun 2008; 368:631-6. [PMID: 18261986 DOI: 10.1016/j.bbrc.2008.01.143] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 01/24/2008] [Indexed: 10/22/2022]
Abstract
Mutations in mitochondrial DNA (mtDNA) have been found to be associated with sensorineural hearing loss. We report the clinical, genetic, and molecular characterization of one Argentinean family with aminoglycoside-induced impairment in two of their members. Clinical evaluation revealed the variable phenotype of hearing impairment including audiometric configuration in these subjects. Mutational analysis of the mtDNA in these pedigrees showed the presence of homoplasmic 12S rRNA A827G mutation, which has been associated with hearing impairment. The A827G mutation is located at the A-site of the mitochondrial 12S rRNA gene which is highly conserved in mammals. It is possible that the alteration of the tertiary or quaternary structure of this rRNA by the A827G mutation may lead to mitochondrial dysfunction, thereby playing a role in the pathogenesis of hearing loss and aminoglycoside hypersensitivity. However, incomplete penetrance of hearing impairment indicates that the A827G mutation itself is not sufficient to produce clinical phenotype.
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Affiliation(s)
- M R Chaig
- Cátedra de Bioquímica y Biología molecular, FCM-UNC, Haya de la Torre, S/N Ciudad Universitaria, 2do, Piso, Pabellón CP 5016, Argentina
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25
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Abstract
The human ear is a delicate sensory apparatus of hearing for normal communication, and its proper functioning is highly dependent on mitochondrial oxidative phosphorylation. The first mitochondrial point mutation for nonsyndromic and aminoglycoside-induced hearing loss was identified in 1993. Since then a number of inherited mitochondrial mutations have been implicated in hearing loss. Most of the molecular defects responsible for mitochondrial disorder-associated hearing loss are mutations in the 12S rRNA gene and tRNA genes. In this review, after a short description of normal hearing mechanisms and mitochondrial genetics, we outline the recent advances that have been made in the identification of deafness-associated mitochondrial mutations, and discuss how mitochondrial dysfunction contributes to hearing loss.
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Affiliation(s)
- Guangqian Xing
- Department of Otolaryngology, the First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
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26
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Xing G, Chen Z, Wei Q, Tian H, Li X, Zhou A, Bu X, Cao X. Mitochondrial 12S rRNA A827G mutation is involved in the genetic susceptibility to aminoglycoside ototoxicity. Biochem Biophys Res Commun 2006; 346:1131-5. [PMID: 16782057 DOI: 10.1016/j.bbrc.2006.05.208] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Accepted: 05/20/2006] [Indexed: 11/19/2022]
Abstract
We have analyzed the clinical and molecular characterization of a Chinese family with aminoglycoside-induced and non-syndromic hearing impairment. Clinical evaluations revealed that only those family members who had a history of exposure to aminoglycoside antibiotics subsequently developed hearing loss, suggesting mitochondrial genome involvement. Sequence analysis of the mitochondrial 12S rRNA and tRNA(Ser(UCN)) genes led to the identification of a homoplasmic A827G mutation in all maternal relatives, a mutation that was identified previously in a few sporadic patients and in another Chinese family with non-syndromic deafness. The pathogenicity of the A827G mutation is strongly supported by the occurrence of the same mutation in two independent families and several genetically unrelated subjects. The A827G mutation is located at the A-site of the mitochondrial 12S rRNA gene which is highly conserved in mammals. It is possible that the alteration of the tertiary or quaternary structure of this rRNA by the A827G mutation may lead to mitochondrial dysfunction, thereby playing a role in the pathogenesis of hearing loss and aminoglycoside hypersensitivity. However, incomplete penetrance of hearing impairment indicates that the A827G mutation itself is not sufficient to produce clinical phenotype but requires the involvement of modifier factors for the phenotypic expression. Indeed, aminoglycosides may contribute to the phenotypic manifestation of the A827G mutation in this family. In contrast with the congenital or early-onset hearing impairment in another Chinese family carrying the A827G mutation, three patients in this pedigree developed hearing loss only after use of aminoglycosides. This discrepancy likely reflects the difference of genetic backgrounds, either mitochondrial haplotypes or nuclear modifier genes, between two families.
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Affiliation(s)
- Guangqian Xing
- Department of Otolaryngology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
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27
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Guan MX, Yan Q, Li X, Bykhovskaya Y, Gallo-Teran J, Hajek P, Umeda N, Zhao H, Garrido G, Mengesha E, Suzuki T, del Castillo I, Peters JL, Li R, Qian Y, Wang X, Ballana E, Shohat M, Lu J, Estivill X, Watanabe K, Fischel-Ghodsian N. Mutation in TRMU related to transfer RNA modification modulates the phenotypic expression of the deafness-associated mitochondrial 12S ribosomal RNA mutations. Am J Hum Genet 2006; 79:291-302. [PMID: 16826519 PMCID: PMC1559489 DOI: 10.1086/506389] [Citation(s) in RCA: 193] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Accepted: 05/12/2006] [Indexed: 01/29/2023] Open
Abstract
The human mitochondrial 12S ribosomal RNA (rRNA) A1555G mutation has been associated with aminoglycoside-induced and nonsyndromic deafness in many families worldwide. Our previous investigation revealed that the A1555G mutation is a primary factor underlying the development of deafness but is not sufficient to produce a deafness phenotype. However, it has been proposed that nuclear-modifier genes modulate the phenotypic manifestation of the A1555G mutation. Here, we identified the nuclear-modifier gene TRMU, which encodes a highly conserved mitochondrial protein related to transfer RNA (tRNA) modification. Genotyping analysis of TRMU in 613 subjects from 1 Arab-Israeli kindred, 210 European (Italian pedigrees and Spanish pedigrees) families, and 31 Chinese pedigrees carrying the A1555G or the C1494T mutation revealed a missense mutation (G28T) altering an invariant amino acid residue (A10S) in the evolutionarily conserved N-terminal region of the TRMU protein. Interestingly, all 18 Arab-Israeli/Italian-Spanish matrilineal relatives carrying both the TRMU A10S and 12S rRNA A1555G mutations exhibited prelingual profound deafness. Functional analysis showed that this mutation did not affect importation of TRMU precursors into mitochondria. However, the homozygous A10S mutation leads to a marked failure in mitochondrial tRNA metabolisms, specifically reducing the steady-state levels of mitochondrial tRNA. As a consequence, these defects contribute to the impairment of mitochondrial-protein synthesis. Resultant biochemical defects aggravate the mitochondrial dysfunction associated with the A1555G mutation, exceeding the threshold for expressing the deafness phenotype. These findings indicate that the mutated TRMU, acting as a modifier factor, modulates the phenotypic manifestation of the deafness-associated 12S rRNA mutations.
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Affiliation(s)
- Min-Xin Guan
- Division and Program in Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA.
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28
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Xing G, Chen Z, Wei Q, Tian H, Li X, Zhou A, Bu X, Cao X. Maternally inherited non-syndromic hearing loss associated with mitochondrial 12S rRNA A827G mutation in a Chinese family. Biochem Biophys Res Commun 2006; 344:1253-7. [PMID: 16650816 DOI: 10.1016/j.bbrc.2006.04.033] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2006] [Accepted: 04/04/2006] [Indexed: 11/28/2022]
Abstract
We explored the clinical and molecular characterization of a Chinese family with non-syndromic hearing impairment. Clinical evaluations revealed a possible maternal inheritance pattern, and showed an extremely similar phenotype of hearing loss including the age of onset, severity, and audiometric configuration. Sequence analysis of the mitochondrial 12S rRNA and tRNA(Ser(UCN)) genes led to the identification of a homoplasmic A827G mutation in all maternal relatives, which was absent in other family members and 40 Chinese controls. This mutation has previously been reported sporadically in a few individuals with aminoglycoside-induced and non-syndromic hearing loss. The A827G mutation is located at the A-site of the mitochondrial 12S rRNA gene which is highly evolutionarily conserved in mammals. The occurrence of the A827G mutation in these genetically unrelated subjects strongly suggests that this mutation is involved in the pathogenesis of hearing impairment. However, incomplete penetrance of hearing loss indicates that the A827G mutation alone is not sufficient to produce clinical phenotype but requires the involvement of modifier factors for the phenotypic expression, even though aminoglycosides and GJB2 gene may not contribute to the penetrance of the A827G mutation in this Chinese family. In contrast with the variable phenotype of hearing loss associated with other mitochondrial mutations, all of the patients in our family exhibited strikingly similar clinical features. This discrepancy likely reflects the difference of genetic backgrounds between this pedigree and others.
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Affiliation(s)
- Guangqian Xing
- Department of Otolaryngology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
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