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Vikramdeo KS, Sudan SK, Singh AP, Singh S, Dasgupta S. Mitochondrial respiratory complexes: Significance in human mitochondrial disorders and cancers. J Cell Physiol 2022; 237:4049-4078. [PMID: 36074903 DOI: 10.1002/jcp.30869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 07/18/2022] [Accepted: 08/23/2022] [Indexed: 11/07/2022]
Abstract
Mitochondria are pivotal organelles that govern cellular energy production through the oxidative phosphorylation system utilizing five respiratory complexes. In addition, mitochondria also contribute to various critical signaling pathways including apoptosis, damage-associated molecular patterns, calcium homeostasis, lipid, and amino acid biosynthesis. Among these diverse functions, the energy generation program oversee by mitochondria represents an immaculate orchestration and functional coordination between the mitochondria and nuclear encoded molecules. Perturbation in this program through respiratory complexes' alteration results in the manifestation of various mitochondrial disorders and malignancy, which is alarmingly becoming evident in the recent literature. Considering the clinical relevance and importance of this emerging medical problem, this review sheds light on the timing and nature of molecular alterations in various respiratory complexes and their functional consequences observed in various mitochondrial disorders and human cancers. Finally, we discussed how this wealth of information could be exploited and tailored to develop respiratory complex targeted personalized therapeutics and biomarkers for better management of various incurable human mitochondrial disorders and cancers.
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Affiliation(s)
- Kunwar Somesh Vikramdeo
- Department of Pathology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.,Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - Sarabjeet Kour Sudan
- Department of Pathology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.,Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - Ajay P Singh
- Department of Pathology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.,Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.,Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Seema Singh
- Department of Pathology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.,Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.,Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
| | - Santanu Dasgupta
- Department of Pathology, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA.,Department of Pathology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.,Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama, USA
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Sundaramurthy S, SelvaKumar A, Ching J, Dharani V, Sarangapani S, Yu-Wai-Man P. Leber hereditary optic neuropathy-new insights and old challenges. Graefes Arch Clin Exp Ophthalmol 2021; 259:2461-2472. [PMID: 33185731 DOI: 10.1007/s00417-020-04993-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/16/2020] [Accepted: 10/23/2020] [Indexed: 12/20/2022] Open
Abstract
Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial DNA (mtDNA) disorder with the majority of patients harboring one of three primary mtDNA point mutations, namely, m.3460G>A (MTND1), m.11778G>A (MTND4), and m.14484T>C (MTND6). LHON is characterized by bilateral subacute loss of vision due to the preferential loss of retinal ganglion cells (RGCs) within the inner retina, resulting in optic nerve degeneration. This review describes the clinical features associated with mtDNA LHON mutations and recent insights gained into the disease mechanisms contributing to RGC loss in this mitochondrial disorder. Although treatment options remain limited, LHON research has now entered an active translational phase with ongoing clinical trials, including gene therapy to correct the underlying pathogenic mtDNA mutation.
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Affiliation(s)
- Srilekha Sundaramurthy
- 1SN Oil and Natural Gas Corporation (ONGC) Department of Genetics & Molecular Biology, Vision Research Foundation, Chennai, India.
| | - Ambika SelvaKumar
- Department of Neuro-Ophthalmology, Medical Research Foundation, Chennai, India
| | - Jared Ching
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK
- John Van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Vidhya Dharani
- Department of Neuro-Ophthalmology, Medical Research Foundation, Chennai, India
| | - Sripriya Sarangapani
- 1SN Oil and Natural Gas Corporation (ONGC) Department of Genetics & Molecular Biology, Vision Research Foundation, Chennai, India
| | - Patrick Yu-Wai-Man
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK
- John Van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
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Yokota Y, Hara M, Akimoto T, Mizoguchi T, Goto YI, Nishino I, Kamei S, Nakajima H. Late-onset MELAS syndrome with mtDNA 14453G→A mutation masquerading as an acute encephalitis: a case report. BMC Neurol 2020; 20:247. [PMID: 32552696 PMCID: PMC7298965 DOI: 10.1186/s12883-020-01818-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/03/2020] [Indexed: 02/06/2023] Open
Abstract
Background A unique patient with MELAS syndrome, who initially masqueraded as having acute encephalitis and was eventually diagnosed with MELAS syndrome harboring a mtDNA 14453G → A mutation, is described. Case presentation A 74-year-old Japanese man was admitted to another hospital due to acute onset of cognitive impairment and psychosis. After 7 days he was transferred to our hospital with seizures and deteriorating psychosis. The results of primary ancillary tests that included EEG, CSF findings, and brain MRI supported the diagnosis of an acute encephalitis. HSV-DNA and antibodies against neuronal surface antigens in the CSF were all negative. With the assistance of the lactate peak on the brain lesions in the magnetic resonance spectroscopy image and genetic analysis of the biopsied muscle, he was eventually diagnosed with MELAS syndrome harboring mtDNA 14453G → A mutation in the ND6 gene. Conclusions This case provides a caveat that MELAS syndrome can manifest in the symptoms and ancillary tests masquerading as an acute encephalitis caused by infection or autoimmunity. This is the first adult patient seen to harbor the mtDNA14453G → A with a unique onset, which broadens the phenotypic spectrum of MELAS syndrome associated with ND6 gene mutation.
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Affiliation(s)
- Yuki Yokota
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Makoto Hara
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan.
| | - Takayoshi Akimoto
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Tomotaka Mizoguchi
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Yu-Ichi Goto
- Medical Genome Center, National Center of Neurology and Psychiatry, Tokyo, Japan.,Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Satoshi Kamei
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan.,Center for Neuro-infection, Department of Neurology, Ageo Central General Hospital, Saitama, Japan
| | - Hideto Nakajima
- Division of Neurology, Department of Medicine, Nihon University School of Medicine, 30-1, Oyaguchi-Kamicyo, Itabashi-ku, Tokyo, 173-8610, Japan
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Novel Mutations of mtDNA m.14568G>A/m.14568C>T in MT-ND6 and m.7299A>G in MT-CO1: Evidence of Pathogenicity in Leber Hereditary Optic Neuropathy. J Neuroophthalmol 2020; 40:566-568. [PMID: 32358433 DOI: 10.1097/wno.0000000000000973] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Mitochondrial disorders and the eye. Surv Ophthalmol 2019; 65:294-311. [PMID: 31783046 DOI: 10.1016/j.survophthal.2019.11.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 11/16/2019] [Accepted: 11/18/2019] [Indexed: 01/27/2023]
Abstract
Mitochondria are cellular organelles that play a key role in energy metabolism and oxidative phosphorylation. Malfunctioning of mitochondria has been implicated as the cause of many disorders with variable inheritance, heterogeneity of systems involved, and varied phenotype. Metabolically active tissues are more likely to be affected, causing an anatomic and physiologic disconnect in the treating physicians' mind between presentation and underlying pathophysiology. We shall focus on disorders of mitochondrial metabolism relevant to an ophthalmologist. These disorders can affect all parts of the visual pathway (crystalline lens, extraocular muscles, retina, optic nerve, and retrochiasm). After the introduction reviewing mitochondrial structure and function, each disorder is reviewed in detail, including approaches to its diagnosis and most current management guidelines.
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Fiedorczuk K, Sazanov LA. Mammalian Mitochondrial Complex I Structure and Disease-Causing Mutations. Trends Cell Biol 2018; 28:835-867. [PMID: 30055843 DOI: 10.1016/j.tcb.2018.06.006] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 06/14/2018] [Accepted: 06/22/2018] [Indexed: 12/31/2022]
Abstract
Complex I has an essential role in ATP production by coupling electron transfer from NADH to quinone with translocation of protons across the inner mitochondrial membrane. Isolated complex I deficiency is a frequent cause of mitochondrial inherited diseases. Complex I has also been implicated in cancer, ageing, and neurodegenerative conditions. Until recently, the understanding of complex I deficiency on the molecular level was limited due to the lack of high-resolution structures of the enzyme. However, due to developments in single particle cryo-electron microscopy (cryo-EM), recent studies have reported nearly atomic resolution maps and models of mitochondrial complex I. These structures significantly add to our understanding of complex I mechanism and assembly. The disease-causing mutations are discussed here in their structural context.
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Affiliation(s)
- Karol Fiedorczuk
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria; Present address: The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria.
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Bi R, Logan I, Yao YG. Leber Hereditary Optic Neuropathy: A Mitochondrial Disease Unique in Many Ways. Handb Exp Pharmacol 2017; 240:309-336. [PMID: 27787713 DOI: 10.1007/164_2016_1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Leber hereditary optic neuropathy (LHON) was the first mitochondrial disease to be identified as being caused by mutations in the mitochondrial DNA (mtDNA). This disease has been studied extensively in the past two decades, particularly in Brazilian, Chinese and European populations; and many primary mutations have been reported. However, the disease is enigmatic with many unique features, and there still are several important questions to be resolved. The incomplete penetrance, the male-biased disease expression and the prevalence in young adults all defy a proper explanation. It has been reported that the development of LHON is affected by the interaction between mtDNA mutations, mtDNA haplogroup background, nuclear genes, environmental factors and epigenetics. Furthermore, with the help of new animal models for LHON that have been created in recent years, we are continuing to learn more about the mechanism of this disease. The stage has now been reached at which there is a good understanding of both the genetic basis of the disease and its epidemiology, but just how the blindness that follows from the death of cells in the optic nerve can be prevented remains to be a pharmacological challenge. In this chapter, we summarize the progress that has been made in various recent studies on LHON, focusing on the molecular pathogenic mechanisms, clinical features, biochemical effects, the pharmacology and its treatment.
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Affiliation(s)
- Rui Bi
- Division of Medical Genetics & Evolutionary Medicine, Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
| | | | - Yong-Gang Yao
- Division of Medical Genetics & Evolutionary Medicine, Key Laboratory of Animal Models and Human Disease Mechanisms, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China.
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Nardi F, Frati F, Liò P. Animal inference on human mitochondrial diseases. Comput Biol Chem 2016; 62:17-28. [PMID: 27023046 DOI: 10.1016/j.compbiolchem.2016.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 02/02/2016] [Indexed: 11/17/2022]
Abstract
Several pathological mutations in the human mitochondrial genome have been characterized based on medical, genetic and biochemical evidence. The observation that the structure and core functions of the mitochondrial genome are conserved from animals to man suggests that the analysis of animal variation may be informative to further characterize, and possibly predict, human pathological variants. We studied the distribution of sequence site-wise diversity and structural heterogeneity (based on several scales of hydrophobicity and supercomplex classification of mitochondrial genes) at different taxonomic levels in ∼15,000 human and animal genomes. We found that human pathological mutations tend to lay in regions of low diversity and that states that are pathological in humans appear to be extremely rare in animals, with two noticeable exceptions (T10663C and C14568T). Focusing on hydrophobicity, as possibly the most general site-wise functional parameter of a protein, we deploy the observed range of hydrophobicity in mammals as a proxy for the range of permissible states compatible with an efficient functioning of the mitochondrial machinery. We show that, while non pathological human variants tend to fall within the hypothesized range, pathological mutations generally fall outside this range. We further analyzed this distribution quantitatively to show that the estimated probability of observed states can indeed be used to predict the pathogenicity of a mutation in humans. This study provides a proof of principle that animal data can indeed be informative to predict the pathogenicity of a human mutation alongside, or in the absence of, additional evidence.
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Affiliation(s)
| | | | - Pietro Liò
- Computer Laboratory, University of Cambridge, Cambridge, UK.
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Eustace Ryan S, Ryan F, Barton D, O'Dwyer V, Neylan D. Development and validation of a novel PCR-RFLP based method for the detection of 3 primary mitochondrial mutations in Leber's hereditary optic neuropathy patients. EYE AND VISION 2015; 2:18. [PMID: 26605371 PMCID: PMC4657363 DOI: 10.1186/s40662-015-0028-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/06/2015] [Indexed: 11/28/2022]
Abstract
Background Leber’s Hereditary Optic Neuropathy (LHON; MIM 535000) is one of the most commonly inherited optic neuropathies and it results in significant visual morbidity among young adults with a peak age of onset between the ages of 15–30. The worldwide incidence of LHON is approximately 1 in 31,000. 95 % of LHON patients will have one of 3 primary mitochondrial mutations, G3460A (A52T of ND1), G11778A (R340H of ND4) and T14484C (M64V of ND6). There is incomplete penetrance and a marked gender bias in the development of visual morbidity with approximately 50 % of male carriers and 10 % of female carriers developing optic neuropathy. Visual recovery can occur but is dependent on the mutation present with the highest level of visual recovery seen in patients who have the T14484C mutation. The 3 primary mutations are typically identified by individual end-point PCR-restriction fragment length polymorphism (RFLP) or individual targeted bi-directional Sanger sequencing reactions. The purpose of this study was to design a simple multiplex PCR-RFLP that could detect these 3 primary LHON mutations in one assay. Methods PCR primers were designed to incorporate a MaeIII restriction site in the presence of 3460A and 14484C mutations with the 11778A mutation naturally incorporating a MaeIII site. A multiplex PCR-RFLP assay was developed to detect the 3 common mutations in a single assay. Synthetic LHON controls based on the mitochondrial genome harbouring the 3 common mutations were synthesized and cloned into plasmids to act as reliable assay controls. DNA from previously tested patients and the synthetic LHON controls were subjected to the multiplex PCR-RFLP assay. The RFLP products were detected by agarose gel electrophoresis. Results The novel PCR-RFLP assay accurately detects the 3 primary mutations both in patient DNA and in synthesized DNA control samples with a simple visual mutation detection procedure. The synthesized DNA was demonstrated to be a robust control for the detection of LHON Mutations. Conclusion In this paper, we describe a novel, robust and simple PCR-RFLP based method for the detection of mutations causing LHON, and report the generation of a series of LHON DNA controls suitable for all currently published assays. Electronic supplementary material The online version of this article (doi:10.1186/s40662-015-0028-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Siobhan Eustace Ryan
- National Optometry Centre, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland
| | - Fergus Ryan
- School of Biological Sciences, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland
| | - David Barton
- Centre for Medical Genetics, Our Lady's Hospital for Sick Children, Crumlin, Dublin 12, Ireland
| | - Veronica O'Dwyer
- National Optometry Centre, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland
| | - Derek Neylan
- School of Biological Sciences, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland
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Adaptation of the Mitochondrial Genome in Cephalopods: Enhancing Proton Translocation Channels and the Subunit Interactions. PLoS One 2015; 10:e0135405. [PMID: 26285039 PMCID: PMC4540416 DOI: 10.1371/journal.pone.0135405] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 07/21/2015] [Indexed: 01/25/2023] Open
Abstract
Mitochondrial protein-coding genes (mt genes) encode subunits forming complexes of crucial cellular pathways, including those involved in the vital process of oxidative phosphorylation (OXPHOS). Despite the vital role of the mitochondrial genome (mt genome) in the survival of organisms, little is known with respect to its adaptive implications within marine invertebrates. The molluscan Class Cephalopoda is represented by a marine group of species known to occupy contrasting environments ranging from the intertidal to the deep sea, having distinct metabolic requirements, varied body shapes and highly advanced visual and nervous systems that make them highly competitive and successful worldwide predators. Thus, cephalopods are valuable models for testing natural selection acting on their mitochondrial subunits (mt subunits). Here, we used concatenated mt genes from 17 fully sequenced mt genomes of diverse cephalopod species to generate a robust mitochondrial phylogeny for the Class Cephalopoda. We followed an integrative approach considering several branches of interest–covering cephalopods with distinct morphologies, metabolic rates and habitats–to identify sites under positive selection and localize them in the respective protein alignment and/or tridimensional structure of the mt subunits. Our results revealed significant adaptive variation in several mt subunits involved in the energy production pathway of cephalopods: ND5 and ND6 from Complex I, CYTB from Complex III, COX2 and COX3 from Complex IV, and in ATP8 from Complex V. Furthermore, we identified relevant sites involved in protein-interactions, lining proton translocation channels, as well as disease/deficiencies related sites in the aforementioned complexes. A particular case, revealed by this study, is the involvement of some positively selected sites, found in Octopoda lineage in lining proton translocation channels (site 74 from ND5) and in interactions between subunits (site 507 from ND5) of Complex I.
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Behbehani R, Melhem M, Alghanim G, Behbehani K, Alsmadi O. ND4L gene concurrent 10609T>C and 10663T>C mutations are associated with Leber's hereditary optic neuropathy in a large pedigree from Kuwait. Br J Ophthalmol 2014; 98:826-31. [PMID: 24568867 PMCID: PMC4033154 DOI: 10.1136/bjophthalmol-2013-304140] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Background Leber's hereditary optic neuropathy (LHON) is a condition characterised by a rapid bilateral central vision loss due to death of the retinal ganglion cells, leading to visual impairment commonly occurring during young adulthood. The disease manifests itself more in male patients than female patients. The mtDNA mutations m.11778G>A, m.3460G>A and m.14484T>C are by far more frequent in LHON than any other mutation. In this report, a multi-generational Arab family from Kuwait with 14 male members with LHON was investigated. Methods Complete mtDNA mutational analysis by direct Sanger's sequencing was carried out to detect pathogenic mutations, polymorphisms and haplogrouping. Results All maternally related subjects from this study who were examined expressed the L3 haplotype background, with two concurrent mtDNA mutations, 10609T>C and 10663T>C, that led to non-conservative amino acid changes of Ile47Thr and Val65Ala, respectively. The two variations were absent in 144 normal and ethnicity-matched controls. Conclusions The two identified mutations associated with LHON in this family may exert their pathogenicity through a cumulative or haplogroup effect. This is the first report of the presence of two concurrent mutations in the ND4L gene in individuals with LHON who carry the L3 haplogroup.
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Affiliation(s)
| | | | | | | | - Osama Alsmadi
- Dasman Genome Centre, Dasman Institute, Dasman, Kuwait
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Iommarini L, Calvaruso MA, Kurelac I, Gasparre G, Porcelli AM. Complex I impairment in mitochondrial diseases and cancer: Parallel roads leading to different outcomes. Int J Biochem Cell Biol 2013; 45:47-63. [DOI: 10.1016/j.biocel.2012.05.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 05/03/2012] [Accepted: 05/24/2012] [Indexed: 02/06/2023]
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Achilli A, Iommarini L, Olivieri A, Pala M, Hooshiar Kashani B, Reynier P, La Morgia C, Valentino ML, Liguori R, Pizza F, Barboni P, Sadun F, De Negri AM, Zeviani M, Dollfus H, Moulignier A, Ducos G, Orssaud C, Bonneau D, Procaccio V, Leo-Kottler B, Fauser S, Wissinger B, Amati-Bonneau P, Torroni A, Carelli V. Rare primary mitochondrial DNA mutations and probable synergistic variants in Leber's hereditary optic neuropathy. PLoS One 2012; 7:e42242. [PMID: 22879922 PMCID: PMC3411744 DOI: 10.1371/journal.pone.0042242] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 07/02/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Leber's hereditary optic neuropathy (LHON) is a maternally inherited blinding disorder, which in over 90% of cases is due to one of three primary mitochondrial DNA (mtDNA) point mutations (m.11778G>A, m.3460G>A and m.14484T>C, respectively in MT-ND4, MT-ND1 and MT-ND6 genes). However, the spectrum of mtDNA mutations causing the remaining 10% of cases is only partially and often poorly defined. METHODOLOGY/PRINCIPAL FINDINGS In order to improve such a list of pathological variants, we completely sequenced the mitochondrial genomes of suspected LHON patients from Italy, France and Germany, lacking the three primary common mutations. Phylogenetic and conservation analyses were performed. Sixteen mitochondrial genomes were found to harbor at least one of the following nine rare LHON pathogenic mutations in genes MT-ND1 (m.3700G>A/p.A132T, m.3733G>A-C/p.E143K-Q, m.4171C>A/p.L289M), MT-ND4L (m.10663T>C/p.V65A) and MT-ND6 (m.14459G>A/p.A72V, m.14495A>G/p.M64I, m.14482C>A/p.L60S, and m.14568C>T/p.G36S). Phylogenetic analyses revealed that these substitutions were due to independent events on different haplogroups, whereas interspecies comparisons showed that they affected conserved amino acid residues or domains in the ND subunit genes of complex I. CONCLUSIONS/SIGNIFICANCE Our findings indicate that these nine substitutions are all primary LHON mutations. Therefore, despite their relative low frequency, they should be routinely tested for in all LHON patients lacking the three common mutations. Moreover, our sequence analysis confirms the major role of haplogroups J1c and J2b (over 35% in our probands versus 6% in the general population of Western Europe) and other putative synergistic mtDNA variants in LHON expression.
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Affiliation(s)
- Alessandro Achilli
- Dipartimento di Biologia Cellulare e Ambientale, Università di Perugia, Perugia, Italy
| | - Luisa Iommarini
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Dipartimento di Scienze Neurologiche, Università di Bologna, Bologna, Italy
| | - Anna Olivieri
- Dipartimento di Biologia e Biotecnologie, Università di Pavia, Pavia, Italy
| | - Maria Pala
- Dipartimento di Biologia e Biotecnologie, Università di Pavia, Pavia, Italy
| | | | - Pascal Reynier
- UMR INSERM, U1083-CNRS6214, Angers, France
- University of Angers, School of Medicine, Angers, France
- University Hospital of Angers, Department of Biochemistry and Genetics, Angers, France
| | - Chiara La Morgia
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Dipartimento di Scienze Neurologiche, Università di Bologna, Bologna, Italy
| | - Maria Lucia Valentino
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Dipartimento di Scienze Neurologiche, Università di Bologna, Bologna, Italy
| | - Rocco Liguori
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Dipartimento di Scienze Neurologiche, Università di Bologna, Bologna, Italy
| | - Fabio Pizza
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Dipartimento di Scienze Neurologiche, Università di Bologna, Bologna, Italy
| | - Piero Barboni
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Dipartimento di Scienze Neurologiche, Università di Bologna, Bologna, Italy
- Studio Oculistico D’Azeglio, Bologna, Italy
| | | | | | - Massimo Zeviani
- Unit of Molecular Neurogenetics, Pierfranco and Luisa Mariani Center for the Study of Children’s Mitochondrial Disorders, Foundation “C. Besta” Neurological Institute-IRCCS, Milan, Italy
| | - Helene Dollfus
- Centre de référence pour les Affections Rares en Génétique Ophtalmologique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Antoine Moulignier
- Service de Neurologie, Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
| | - Ghislaine Ducos
- Department of Ophthalmology, Saint Jean Languedoc Clinic, Toulouse, France
| | - Christophe Orssaud
- Centre de Référence des Maladies Rares en Ophtalmologie, Consultationd ‘Ophtalmologie, HEGP, Assistance Publique – Hôpitaux de Paris, Paris, France
| | - Dominique Bonneau
- UMR INSERM, U1083-CNRS6214, Angers, France
- University of Angers, School of Medicine, Angers, France
- University Hospital of Angers, Department of Biochemistry and Genetics, Angers, France
| | - Vincent Procaccio
- UMR INSERM, U1083-CNRS6214, Angers, France
- University of Angers, School of Medicine, Angers, France
- University Hospital of Angers, Department of Biochemistry and Genetics, Angers, France
| | - Beate Leo-Kottler
- Centre for Ophthalmology, University Clinics Tuebingen, Tubingen, Germany
| | - Sascha Fauser
- Department of Vitreo-Retinal Surgery, Center of Ophthalmology, University of Cologne, Cologne, Germany
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University Clinics Tuebingen, Tuebingen, Germany
| | - Patrizia Amati-Bonneau
- UMR INSERM, U1083-CNRS6214, Angers, France
- University Hospital of Angers, Department of Biochemistry and Genetics, Angers, France
| | - Antonio Torroni
- Dipartimento di Biologia e Biotecnologie, Università di Pavia, Pavia, Italy
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Dipartimento di Scienze Neurologiche, Università di Bologna, Bologna, Italy
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Shidara K, Wakakura M. Leber's hereditary optic neuropathy with the 3434, 9011 mitochondrial DNA point mutation. Jpn J Ophthalmol 2011; 56:175-80. [PMID: 22183138 DOI: 10.1007/s10384-011-0106-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 09/28/2011] [Indexed: 11/24/2022]
Abstract
BACKGROUND Leber's hereditary optic neuropathy (LHON) contains several well-known mitochondrial DNA (mtDNA) point mutations. We report a case with characteristic clinical manifestations of LHON involving a possible new LHON point mutation. CASE A 34-year-old man was diagnosed with LHON. The patient exhibited (1) sudden onset of bilateral visual loss, (2) normal light reflex, and (3) swelling of the peripapillary nerve fiber layer. After subsequent development of bilateral optic disc pallor, we concluded that the patient had LHON. mtDNA analysis was conducted using non-radioisotopic single-strand conformational polymorphism followed by direct sequencing. There was no change in the patient's visual acuity during the 26-month follow-up period. OBSERVATIONS The mtDNA point mutations were found at T3434C, G3483A, and V9011A. The confirmed mtDNA substitutions included (1) A-G at nucleotide position 3434, (2) G-A at nucleotide position 3483, and (3) C-T at nucleotide position 9011. The amino acid code at the nucleotide positions 3434 and 9011 was phylogenetically highly conserved. CONCLUSION The 3434 and 9011 mtDNA point mutations are candidates for a new LHON mutation.
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Affiliation(s)
- Kyoko Shidara
- Inouye Eye Hospital, 4-3 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-0062, Japan.
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15
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Aberrant tyrosine transport across the fibroblast membrane in patients with schizophrenia--indications of maternal inheritance. J Psychiatr Res 2011; 45:519-25. [PMID: 20728902 DOI: 10.1016/j.jpsychires.2010.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Revised: 07/24/2010] [Accepted: 08/03/2010] [Indexed: 11/20/2022]
Abstract
BACKGROUND In previous studies of the present patients with schizophrenia, aberrant tyrosine transport across the fibroblast membrane was found. A low K(m), a kinetic factor indicating high affinity between tyrosine and the binding site at the cell membrane, was found to be associated with poor cognitive functions in patients. The present study aimed at investigating possible relationships between patients with schizophrenia and their first-degree relatives in aberrant tyrosine transport indicating that it may be a biological marker for the genetic susceptibility. METHODS Thirty-three parents, 13 fathers and 20 mothers, from 23 families with a schizophrenic patient agreed to enter the study. They underwent skin biopsies for fibroblast cultivation, neuropsychological and psychiatric investigations and were classified as family history positive or negative. Tyrosine transport kinetics (K(m) and V(max)) were calculated from in vitro trials of gradients of extracellular tyrosine concentrations in fibroblast cultures. RESULTS An association between patients with schizophrenia and their mothers were found for a low K(m) indicating maternal inheritance. Mothers displaying a low K(m) performed worse on the neuropsychological tests compared to mothers with normal K(m). Corresponding relationships between a low K(m) and neurocognitive dysfunction had previously been found for the patients. CONCLUSIONS An aberrant tyrosine transport across plasma membrane may constitute a biological marker for an endophenotype within the schizophrenia spectrum with low cognitive functioning. A plausible mode for genetic transmission is maternal inheritance.
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16
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Yu-Wai-Man P, Griffiths PG, Chinnery PF. Mitochondrial optic neuropathies - disease mechanisms and therapeutic strategies. Prog Retin Eye Res 2011; 30:81-114. [PMID: 21112411 PMCID: PMC3081075 DOI: 10.1016/j.preteyeres.2010.11.002] [Citation(s) in RCA: 431] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leber hereditary optic neuropathy (LHON) and autosomal-dominant optic atrophy (DOA) are the two most common inherited optic neuropathies in the general population. Both disorders share striking pathological similarities, marked by the selective loss of retinal ganglion cells (RGCs) and the early involvement of the papillomacular bundle. Three mitochondrial DNA (mtDNA) point mutations; m.3460G>A, m.11778G>A, and m.14484T>C account for over 90% of LHON cases, and in DOA, the majority of affected families harbour mutations in the OPA1 gene, which codes for a mitochondrial inner membrane protein. Optic nerve degeneration in LHON and DOA is therefore due to disturbed mitochondrial function and a predominantly complex I respiratory chain defect has been identified using both in vitro and in vivo biochemical assays. However, the trigger for RGC loss is much more complex than a simple bioenergetic crisis and other important disease mechanisms have emerged relating to mitochondrial network dynamics, mtDNA maintenance, axonal transport, and the involvement of the cytoskeleton in maintaining a differential mitochondrial gradient at sites such as the lamina cribosa. The downstream consequences of these mitochondrial disturbances are likely to be influenced by the local cellular milieu. The vulnerability of RGCs in LHON and DOA could derive not only from tissue-specific, genetically-determined biological factors, but also from an increased susceptibility to exogenous influences such as light exposure, smoking, and pharmacological agents with putative mitochondrial toxic effects. Our concept of inherited mitochondrial optic neuropathies has evolved over the past decade, with the observation that patients with LHON and DOA can manifest a much broader phenotypic spectrum than pure optic nerve involvement. Interestingly, these phenotypes are sometimes clinically indistinguishable from other neurodegenerative disorders such as Charcot-Marie-Tooth disease, hereditary spastic paraplegia, and multiple sclerosis, where mitochondrial dysfunction is also thought to be an important pathophysiological player. A number of vertebrate and invertebrate disease models has recently been established to circumvent the lack of human tissues, and these have already provided considerable insight by allowing direct RGC experimentation. The ultimate goal is to translate these research advances into clinical practice and new treatment strategies are currently being investigated to improve the visual prognosis for patients with mitochondrial optic neuropathies.
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MESH Headings
- Animals
- DNA, Mitochondrial/genetics
- Disease Models, Animal
- Humans
- Optic Atrophy, Autosomal Dominant/pathology
- Optic Atrophy, Autosomal Dominant/physiopathology
- Optic Atrophy, Autosomal Dominant/therapy
- Optic Atrophy, Hereditary, Leber/pathology
- Optic Atrophy, Hereditary, Leber/physiopathology
- Optic Atrophy, Hereditary, Leber/therapy
- Optic Nerve/pathology
- Phenotype
- Point Mutation
- Retinal Ganglion Cells/pathology
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Affiliation(s)
- Patrick Yu-Wai-Man
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, UK.
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17
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Leber's Hereditary Optic Neuropathy-Gene Therapy: From Benchtop to Bedside. J Ophthalmol 2010; 2011:179412. [PMID: 21253496 PMCID: PMC3021870 DOI: 10.1155/2011/179412] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 10/07/2010] [Accepted: 11/12/2010] [Indexed: 02/06/2023] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is a maternally transmitted disorder caused by point mutations in mitochondrial DNA (mtDNA). Most cases are due to mutations in genes encoding subunits of the NADH-ubiquinone oxidoreductase that is Complex I of the electron transport chain (ETC). These mutations are located at nucleotide positions 3460, 11778, or 14484 in the mitochondrial genome. The disease is characterized by apoplectic, bilateral, and severe visual loss. While the mutated mtDNA impairs generation of ATP by all mitochondria, there is only a selective loss of retinal ganglion cells and degeneration of optic nerve axons. Thus, blindness is typically permanent. Half of the men and 10% of females who harbor the pathogenic mtDNA mutation actually develop the phenotype. This incomplete penetrance and gender bias is not fully understood. Additional mitochondrial and/or nuclear genetic factors may modulate the phenotypic expression of LHON. In a population-based study, the mtDNA background of haplogroup J was associated with an inverse relationship of low-ATP generation and increased production of reactive oxygen species (ROS). Effective therapy for LHON has been elusive. In this paper, we describe the findings of pertinent published studies and discuss the controversies of potential strategies to ameliorate the disease.
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18
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Maciel-Guerra AT, Zanchetta LM, Amaral Fernandes MS, Andrade PB, do Amor Divino Miranda PM, Sartorato EL. Leber's hereditary optic neuropathy: clinical and molecular profile of a Brazilian sample. Ophthalmic Genet 2010; 31:126-8. [PMID: 20565249 DOI: 10.3109/13816810.2010.483721] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE The aim of this study was to describe clinical features and search for primary mitochondrial DNA (mtDNA) mutations in 13 unrelated Brazilian patients with Leber's hereditary optic neuropathy (LHON). METHODS Analysis of the G11778A, G3460A, and T14484C mutations was done by polymerase chain reaction and restriction fragment length polymorphism, and mutations were confirmed by direct sequencing. Mean age of onset was 24.5 years and all cases were bilateral. RESULTS Sex ratio (12M:1F) and frequency of simultaneous involvement (9/13) were higher than in other studies. In nine cases there was familial recurrence: 24 male and two female relatives. Ten patients had a mutation: G11778A in six, T14484C in three and one G3460A. The frequency of patients bearing a primary mutation was lower than that described in multicentric studies but similar to that observed among Asians. A higher frequency of the T14484C mutation was detected. CONCLUSIONS The contribution of Amerindians and Africans to the Brazilian mtDNA pool may account for differences in the type and frequency of primary LHON mutations.
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Affiliation(s)
- Andréa Trevas Maciel-Guerra
- Departamento de Genética Médica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, São Paulo, Brasil.
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19
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Potluri P, Davila A, Ruiz-Pesini E, Mishmar D, O'Hearn S, Hancock S, Simon M, Scheffler IE, Wallace DC, Procaccio V. A novel NDUFA1 mutation leads to a progressive mitochondrial complex I-specific neurodegenerative disease. Mol Genet Metab 2009; 96:189-95. [PMID: 19185523 PMCID: PMC2693342 DOI: 10.1016/j.ymgme.2008.12.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 12/09/2008] [Accepted: 12/09/2008] [Indexed: 10/21/2022]
Abstract
Mitochondrial diseases have been shown to result from mutations in mitochondrial genes located in either the nuclear DNA (nDNA) or mitochondrial DNA (mtDNA). Mitochondrial OXPHOS complex I has 45 subunits encoded by 38 nuclear and 7 mitochondrial genes. Two male patients in a putative X-linked pedigree exhibiting a progressive neurodegenerative disorder and a severe muscle complex I enzyme defect were analyzed for mutations in the 38 nDNA and seven mtDNA encoded complex I subunits. The nDNA X-linked NDUFA1 gene (MWFE polypeptide) was discovered to harbor a novel missense mutation which changed a highly conserved glycine at position 32 to an arginine, shown to segregate with the disease. When this mutation was introduced into a NDUFA1 null hamster cell line, a substantial decrease in the complex I assembly and activity was observed. When the mtDNA of the patient was analyzed, potentially relevant missense mutations were observed in the complex I genes. Transmitochondrial cybrids containing the patient's mtDNA resulted in a mild complex I deficiency. Interestingly enough, the nDNA encoded MWFE polypeptide has been shown to interact with various mtDNA encoded complex I subunits. Therefore, we hypothesize that the novel G32R mutation in NDUFA1 is causing complex I deficiency either by itself or in synergy with additional mtDNA variants.
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Affiliation(s)
- Prasanth Potluri
- Center for Molecular and Mitochondrial Medicine and Genetics (MAMMAG), University of California, 2034 Hewitt Hall, Irvine, CA 92697-3940, USA
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20
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Yu-Wai-Man P, Griffiths PG, Hudson G, Chinnery PF. Inherited mitochondrial optic neuropathies. J Med Genet 2009; 46:145-58. [PMID: 19001017 PMCID: PMC2643051 DOI: 10.1136/jmg.2007.054270] [Citation(s) in RCA: 287] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 09/08/2008] [Accepted: 10/07/2008] [Indexed: 02/02/2023]
Abstract
Leber hereditary optic neuropathy (LHON) and autosomal dominant optic atrophy (DOA) are the two most common inherited optic neuropathies and they result in significant visual morbidity among young adults. Both disorders are the result of mitochondrial dysfunction: LHON from primary mitochondrial DNA (mtDNA) mutations affecting the respiratory chain complexes; and the majority of DOA families have mutations in the OPA1 gene, which codes for an inner mitochondrial membrane protein critical for mtDNA maintenance and oxidative phosphorylation. Additional genetic and environmental factors modulate the penetrance of LHON, and the same is likely to be the case for DOA which has a markedly variable clinical phenotype. The selective vulnerability of retinal ganglion cells (RGCs) is a key pathological feature and understanding the fundamental mechanisms that underlie RGC loss in these disorders is a prerequisite for the development of effective therapeutic strategies which are currently limited.
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MESH Headings
- DNA, Mitochondrial
- Female
- GTP Phosphohydrolases/genetics
- Humans
- Male
- Optic Atrophy, Autosomal Dominant/diagnosis
- Optic Atrophy, Autosomal Dominant/epidemiology
- Optic Atrophy, Autosomal Dominant/genetics
- Optic Atrophy, Autosomal Dominant/pathology
- Optic Atrophy, Hereditary, Leber/diagnosis
- Optic Atrophy, Hereditary, Leber/epidemiology
- Optic Atrophy, Hereditary, Leber/genetics
- Optic Atrophy, Hereditary, Leber/pathology
- Point Mutation
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Affiliation(s)
- P Yu-Wai-Man
- Mitochondrial Research Group, The Medical School, Newcastle University, Newcastle upon Tyne, UK
- Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - P G Griffiths
- Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - G Hudson
- Mitochondrial Research Group, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - P F Chinnery
- Mitochondrial Research Group, The Medical School, Newcastle University, Newcastle upon Tyne, UK
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
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21
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Hudson G, Yu-Wai-Man P, Chinnery PF. Leber hereditary optic neuropathy. EXPERT OPINION ON MEDICAL DIAGNOSTICS 2008; 2:789-99. [PMID: 23495818 DOI: 10.1517/17530059.2.7.789] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Leber hereditary optic neuropathy (LHON) is a cause of inherited blindness that typically presents with bilateral, painless, subacute visual failure in young adult males. Males are about four times more likely to be affected than females and 95% of LHON carriers become affected before the age of 50. Affected patients may have characteristic ocular fundal appearances and have evidence of optic nerve dysfunction in the form of impaired colour vision (dyschromatopsia), dense visual field defects (central or caecocentral scotoma) and abnormal visual electrophysiology. OBJECTIVES To summarise the current clinical approach to the molecular diagnosis and clinical management of LHON. METHODS To review the literature and present a review of current understanding. RESULTS/CONCLUSIONS The diagnosis of LHON is usually confirmed by molecular genetic analysis for one of three common mitochondrial DNA (mtDNA) mutations that all affect genes coding for complex I subunits of the respiratory chain: m.3460G > A, m.11778G > A and m.14484T > C. Sequencing of the entire mitochondrial genome can reveal the underlying cause in the minority of patients (∼ 5%) who do not harbour one of these three primary mutations, but a molecular diagnosis is not always possible. A minority of LHON patients exhibit a more widespread multi-system involvement with extra neurological features such as dystonia or a multiple sclerosis-like illness. Management is largely supportive, with the provision of low-vision aids, registration with the relevant social services and an important role for genetic counselling.
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Affiliation(s)
- Gavin Hudson
- Newcastle University, Mitochondrial Research Group, M4014, The Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK +44 191 222 8233 ; +44 191 222 8553 ;
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22
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Zhang S, Wang L, Hao Y, Wang P, Hao P, Yin K, Wang QK, Liu M. T14484C and T14502C in the mitochondrial ND6 gene are associated with Leber's hereditary optic neuropathy in a Chinese family. Mitochondrion 2008; 8:205-10. [PMID: 18440284 DOI: 10.1016/j.mito.2008.02.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 02/02/2008] [Accepted: 02/26/2008] [Indexed: 11/25/2022]
Abstract
Leber's hereditary optic neuropathy (LHON) is a maternally inherited ocular disease which has been associated with three primary mitochondrial DNA mutations: G3640A, G11778A, and T14484C. In this study, we clinically characterized a Chinese family with complete penetrance of LHON. The patients in the family presented with variable clinical features. By direct DNA sequence analysis, we identified both T14484C mutation and a nearby T to C variant at nucleotide 14502 of mitochondria DNA. The T14502C variant altered I58 to V of the protein ND6, which was present in all patients of the family, but not in four unaffected family members and 200 normal controls. The co-existence of both T14484C mutation and T14502C substitution in all patients from the same LHON family suggests that T14502C may play a synergistic role with the primary mutation T14484C. The two variants together may account for the complete penetrance and absence of marked gender bias and visual recovery in the Chinese LHON family although we cannot exclude the possibility of simultaneous involvement of additional mitochondrial variant(s).
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Affiliation(s)
- Shirong Zhang
- Key Laboratory of Molecular Biophysics of Ministry of Education and Center for Human Genome Research, College of Life Science and Technology, Huazhong University of Science and Technology, 9500 Euclid Avenue, Wuhan 430074, China
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23
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Pätsi J, Kervinen M, Finel M, Hassinen IE. Leber hereditary optic neuropathy mutations in the ND6 subunit of mitochondrial complex I affect ubiquinone reduction kinetics in a bacterial model of the enzyme. Biochem J 2008; 409:129-37. [PMID: 17894548 DOI: 10.1042/bj20070866] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
LHON (Leber hereditary optic neuropathy) is a maternally inherited disease that leads to sudden loss of central vision at a young age. There are three common primary LHON mutations, occurring at positions 3460, 11778 and 14484 in the human mtDNA (mitochondrial DNA), leading to amino acid substitutions in mitochondrial complex I subunits ND1, ND4 and ND6 respectively. We have now examined the effects of ND6 mutations on the function of complex I using the homologous NuoJ subunit of Escherichia coli NDH-1 (NADH:quinone oxidoreductase) as a model system. The assembly level of the NDH-1 mutants was assessed using electron transfer from deamino-NADH to the 'shortcut' electron acceptor HAR (hexammine ruthenium), whereas ubiquinone reductase activity was determined using DB (decylubiquinone) as a substrate. Mutant growth in minimal medium with malate as the main carbon source was used for initial screening of the efficiency of energy conservation by NDH-1. The results indicated that NuoJ-M64V, the equivalent of the common LHON mutation in ND6, had a mild effect on E. coli NDH-1 activity, while nearby mutations, particularly NuoJ-Y59F, NuoJ-V65G and NuoJ-M72V, severely impaired the DB reduction rate and cell growth on malate. NuoJ-Met64 and NuoJ-Met72 position mutants lowered the affinity of NDH-1 for DB and explicit C-type inhibitors, whereas NuoJ-Y59C displayed substrate inhibition by oxidized DB. The results are compatible with the notion that the ND6 subunit delineates the binding cavity of ubiquinone substrate, but does not directly take part in the catalytic reaction. How these changes in the enzyme's catalytic properties contribute to LHON pathogenesis is discussed.
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Affiliation(s)
- Jukka Pätsi
- Department of Medical Biochemistry and Molecular Biology, University of Oulu, P.O. Box 5000, FIN-90014 Oulu, Finland
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24
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Oldfors A, Tulinius M. Mitochondrial encephalomyopathies. HANDBOOK OF CLINICAL NEUROLOGY 2007; 86:125-165. [PMID: 18808998 DOI: 10.1016/s0072-9752(07)86006-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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25
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Houshmand M, Mahmoudi T, Panahi MSS, Seyedena Y, Saber S, Ataei M. Identification of a new human mtDNA polymorphism (A14290G) in the NADH dehydrogenase subunit 6 gene. Braz J Med Biol Res 2006; 39:725-30. [PMID: 16751977 DOI: 10.1590/s0100-879x2006000600004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is a maternally inherited form of retinal ganglion cell degeneration leading to optic atrophy in young adults. Several mutations in different genes can cause LHON (heterogeneity). The ND6 gene is one of the mitochondrial genes that encodes subunit 6 of complex I of the respiratory chain. This gene is a hot spot gene. Fourteen Persian LHON patients were analyzed with single-strand conformational polymorphism and DNA sequencing techniques. None of these patients had four primary mutations, G3460A, G11788A, T14484C, and G14459A, related to this disease. We identified twelve nucleotide substitutions, G13702C, T13879C, T14110C, C14167T, G14199T, A14233G, G14272C, A14290G, G14365C, G14368C, T14766C, and T14798C. Eleven of twelve nucleotide substitutions had already been reported as polymorphism. One of the nucleotide substitutions (A14290G) has not been reported. The A14290G nucleotide substitution does not change its amino acid (glutamic acid). We looked for base conservation using DNA star software (MEGALIGN program) as a criterion for pathogenic or nonpathogenic nucleotide substitution in A14290G. The results of ND6 gene alignment in humans and in other species (mouse, cow, elegans worm, and Neurospora crassa mold) revealed that the 14290th base was not conserved. Fifty normal controls were also investigated for this polymorphism in the Iranian population and two had A14290G polymorphism (4%). This study provides evidence that the mtDNA A14290G allele is a new nonpathogenic polymorphism. We suggest follow-up studies regarding this polymorphism in different populations.
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Affiliation(s)
- M Houshmand
- Department of Medical Genetics, National Institute for Genetic Engineering and Biotechnology, Tehran, Iran.
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26
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Inagaki Y, Mashima Y, Fuse N, Ohtake Y, Fujimaki T, Fukuchi T. Mitochondrial DNA Mutations with Leber's Hereditary Optic Neuropathy in Japanese Patients with Open-Angle Glaucoma. Jpn J Ophthalmol 2006; 50:128-34. [PMID: 16604388 DOI: 10.1007/s10384-005-0290-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2004] [Accepted: 06/28/2005] [Indexed: 11/28/2022]
Abstract
PURPOSE Abnormal optic disc excavations are found in patients with Leber's hereditary optic neuropathy (LHON). The purpose of this study was to determine whether heteroplasmy for the major three LHON mutations or for the rare LHON mutations are risk factors for open-angle glaucoma. METHODS Blood samples from 835 Japanese subjects were screened with the Invader assay for ten LHON-associated mutations: three major mutations (G3460A, G11778A, T14484C) and seven rare mutations (T9101C, G9804A, C14482A, C14482G, G14459A, T14498C, and A14510G). Of the 835 subjects, 241 were patients with primary open-angle glaucoma (POAG), 310 were patients with normal-tension glaucoma (NTG), and 284 were healthy controls. RESULTS Five POAG patients and three NTG patients had one of five mutations, C9099A, T9101G, T9101C, G9804A, or G11778A, but none of these patients had LHON. The C9099A (Ile191Met) and T9101G (Ile192Ser) mutations were novel and identified within the probes by lack of signal in the assay. Two patients with the G11778A mutation showed heteroplasmy, with 15% mutant mtDNA in the male patient and 80% in the female patient. The remaining LHON-associated mutations were not detected in any of the subjects. A case-control study did not show a significant difference (P = 0.099): eight potentially disease-associated variants in 551 patients versus zero variants in the 284 controls. CONCLUSIONS Rare LHON-associated mitochondrial DNA mutations were found in Japanese patients with open-angle glaucoma (OAG). However, whether mitochondrial DNA mutations are risk factors for OAG is still open to question.
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MESH Headings
- Aged
- DNA Mutational Analysis
- DNA, Mitochondrial/genetics
- Female
- Genotype
- Glaucoma, Open-Angle/complications
- Glaucoma, Open-Angle/epidemiology
- Glaucoma, Open-Angle/genetics
- Humans
- Japan/epidemiology
- Male
- Middle Aged
- Mutation, Missense
- Optic Atrophy, Hereditary, Leber/complications
- Optic Atrophy, Hereditary, Leber/epidemiology
- Optic Atrophy, Hereditary, Leber/genetics
- Risk Factors
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Affiliation(s)
- Yoko Inagaki
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
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27
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Deng JH, Li Y, Park JS, Wu J, Hu P, Lechleiter J, Bai Y. Nuclear suppression of mitochondrial defects in cells without the ND6 subunit. Mol Cell Biol 2006; 26:1077-86. [PMID: 16428459 PMCID: PMC1347011 DOI: 10.1128/mcb.26.3.1077-1086.2006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previously, we characterized a mouse cell line, 4A, carrying a mitochondrial DNA mutation in the subunit for respiratory complex I, NADH dehydrogenase, in the ND6 gene. This mutation abolished the complex I assembly and disrupted the respiratory function of complex I. We now report here that a galactose-resistant clone, 4AR, was isolated from the cells carrying the ND6 mutation. 4AR still contained the homoplasmic mutation, and apparently there was no ND6 protein synthesis, whereas the assembly of other complex I subunits into complex I was recovered. Furthermore, the respiratory activity and mitochondrial membrane potential were fully recovered. To investigate the genetic origin of this compensation, the mitochondrial DNA (mtDNA) from 4AR was transferred to a new nuclear background. The transmitochondrial lines failed to grow in galactose medium. We further transferred mtDNA with a nonsense mutation at the ND5 gene to the 4AR nuclear background, and a suppression for mitochondrial deficiency was observed. Our results suggest that change(s) in the expression of a certain nucleus-encoded factor(s) can compensate for the absence of the ND6 or ND5 subunit.
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Affiliation(s)
- Jian-Hong Deng
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Youfen Li
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Jeong Soon Park
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Jun Wu
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Peiqing Hu
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - James Lechleiter
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
| | - Yidong Bai
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
- Corresponding author. Mailing address: Department of Cellular and Structural Biology, University of Texas Health Sciences Center at San Antonio, San Antonio, TX 78229. Phone: (210) 567-0561. Fax: (210) 567-3803. E-mail:
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Lee J, Kim CH, Simon DK, Aminova LR, Andreyev AY, Kushnareva YE, Murphy AN, Lonze BE, Kim KS, Ginty DD, Ferrante RJ, Ryu H, Ratan RR. Mitochondrial cyclic AMP response element-binding protein (CREB) mediates mitochondrial gene expression and neuronal survival. J Biol Chem 2005; 280:40398-401. [PMID: 16207717 PMCID: PMC2612541 DOI: 10.1074/jbc.c500140200] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyclic AMP response element-binding protein (CREB) is a widely expressed transcription factor whose role in neuronal protection is now well established. Here we report that CREB is present in the mitochondrial matrix of neurons and that it binds directly to cyclic AMP response elements (CREs) found within the mitochondrial genome. Disruption of CREB activity in the mitochondria decreases the expression of a subset of mitochondrial genes, including the ND5 subunit of complex I, down-regulates complex I-dependent mitochondrial respiration, and increases susceptibility to 3-nitropropionic acid, a mitochondrial toxin that induces a clinical and pathological phenotype similar to Huntington disease. These results demonstrate that regulation of mitochondrial gene expression by mitochondrial CREB, in part, underlies the protective effects of CREB and raise the possibility that decreased mitochondrial CREB activity contributes to the mitochondrial dysfunction and neuronal loss associated with neurodegenerative disorders.
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Affiliation(s)
- Junghee Lee
- Neurology, Pathology, and Psychiatry Departments, Boston University School of Medicine, Boston, Massachusetts 02118
- Geriatric Research Education and Clinical Center, Bedford Veterans Affairs Medical Center, Bedford, Massachusetts 01730
| | - Chun-Hyung Kim
- Molecular Neurobiology Laboratory, McLean Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - David K. Simon
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115
| | - Lyaylya R. Aminova
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115
| | | | | | - Anne N. Murphy
- Mitochondrial Biology, MitoKor, San Diego, California 92121
| | - Bonnie E. Lonze
- Department of Neuroscience and Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Kwang-Soo Kim
- Molecular Neurobiology Laboratory, McLean Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - David D. Ginty
- Department of Neuroscience and Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Robert J. Ferrante
- Neurology, Pathology, and Psychiatry Departments, Boston University School of Medicine, Boston, Massachusetts 02118
- Geriatric Research Education and Clinical Center, Bedford Veterans Affairs Medical Center, Bedford, Massachusetts 01730
| | - Hoon Ryu
- Neurology, Pathology, and Psychiatry Departments, Boston University School of Medicine, Boston, Massachusetts 02118
- Geriatric Research Education and Clinical Center, Bedford Veterans Affairs Medical Center, Bedford, Massachusetts 01730
- To whom correspondence should be addressed: GRECC 18B, Bedford Veterans Affairs Medical Center, 200 Springs Rd., Bedford, MA 01730. Tel.: 781-687-2922; Fax: 781-687-3515; E-mail:
| | - Rajiv R. Ratan
- Department of Neurology, Weill Medical College of Cornell University and Burke-Cornell Medical Research Institute, White Plains, New York 10605
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29
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Abstract
AIM To review the molecular genetic basis of primary inherited optic neuropathies. METHODS Medline and Embase search. RESULTS Inherited optic neuropathies are a genetically diverse group of disorders that present with reduced visual acuity and the clinical appearance of optic atrophy. The inherited optic neuropathies may be sporadic or familial, in which case the mode of inheritance may be Mendelian (autosomal dominant, autosomal recessive, X-linked recessive) or non-Mendelian (mitochondrial). Two genes for dominantly inherited optic atrophy have been mapped (OPA1 and OPA4), of which the gene has been identified in one (OPA1). A gene for recessive optic atrophy (OPA3) has also been identified. X-linked optic atrophy (OPA2) has been mapped but to date no gene has been identified. Mutations in mitochondrial DNA have been identified in Leber's hereditary optic neuropathy. CONCLUSIONS Mutations in genes from both the nuclear and mitochondrial genomes appear to be responsible. Mitochondrial dysfunction, in the broadest sense, is emerging as central to the pathogenesis of this group of conditions.
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Affiliation(s)
- M Votruba
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK.
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30
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Abstract
Mitochondria are increasingly recognized as central players in the life and death of cells and especially of neurons. The energy-dependence of retinal ganglion cells (RGC) and their axons, which form the optic nerve, is singularly skewed. In fact, while mitochondria are very abundant in the initial, unmyelinated part of the axons anterior to the lamina cribrosa, their number suddenly decreases as the myelin sheath begins more posteriorly. The vascular system also presents different blood-brain barrier properties anterior and posterior to the lamina, possibly reflecting the different metabolic needs of the optic nerve head (unmyelinated) and of the retrobulbar optic nerve (myelinated). Mitochondrial biogenesis occurs within the cellular somata of RGC in the retina. It needs the coordinated interaction of nuclear and mitochondrial genomes. Mitochondria are then transported down the axons and distributed where they are needed. These locations are along the unmyelinated portion of the nerve, under the nodes of Ranvier in the retrobulbar nerve, and at the synaptic terminals. Efficient transportation of mitochondria depends on multiple factors, including their own energy production, the integrity of the cytoskeleton and its protein components (tubulin, etc.), and adequate myelination of the axons. Any dysfunction of these systems may be of pathological relevance for optic neuropathies with primary or secondary involvement of mitochondria. Leber's hereditary optic neuropathy (LHON) is the paradigm of mitochondrial optic neuropathies where a primary role for mitochondrial dysfunction is certified by maternal inheritance and association with specific mutations in the mitochondrial DNA (mtDNA). Clinical phenocopies of this pathology are represented by the wide array of optic neuropathies associated with vitamin depletion, toxic exposures, alcohol and tobacco abuse, and use of certain drugs. Moreover, the recent identification of mutations in the nuclear gene OPA1 as the causative factor in dominant optic atrophy (DOA, Kjer's type) brought the unexpected finding that this gene encodes for a mitochondrial protein, suggesting that DOA and LHON may be linked by similar pathogenesis. Polymorphisms in this very same gene may be associated with normal tension glaucoma (NTG), which might be considered a genetically determined optic neuropathy that again shows similarities with both LHON and DOA. Exciting new developments come from first examples of mitochondrial optic neuropathies in animal models that are genetically determined or are the result of ingenious engineering of mitochondrial gene expression, or from biochemical manipulations of the respiratory complexes. Even more exciting is the first successful attempt to correct the LHON-related complex I dysfunction by the allotopic nuclear expression of the recoded mitochondrial gene. There is hope that the genetic complexities, biochemical dysfunctions, and integrated anatomical-physiological cellular relationships will soon be precisely delineated and that promising therapeutic and prophylactic strategies will be proposed.
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Affiliation(s)
- Valerio Carelli
- Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.
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31
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Fillmore PD, Brace M, Troutman SA, Blankenhorn EP, Diehl S, Rincon M, Teuscher C. Genetic analysis of the influence of neuroantigen-complete Freund's adjuvant emulsion structures on the sexual dimorphism and susceptibility to experimental allergic encephalomyelitis. THE AMERICAN JOURNAL OF PATHOLOGY 2003; 163:1623-32. [PMID: 14507669 DOI: 10.1016/s0002-9440(10)63519-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The induction of organ-specific autoimmune diseases, such as experimental allergic encephalomyelitis (EAE) the principal animal model of multiple sclerosis (MS), relies on the use of complete Freund's adjuvant (CFA) emulsions. In this study we report that the physical structure of the particles comprising neuroantigen-CFA emulsions significantly influences the genetic control of the incidence and sexual dimorphism seen in EAE. Immunization of (B10.S/SgMcdJ x SJL/J) F(2) mice segregating the quantitative trait loci (QTL) controlling EAE in susceptible SJL/J and resistant B10.S/SgMcdJ mice with emulsions consisting of particles where the Mycobacterium tuberculosis and neuroantigens are localized on the phase surfaces led to severe EAE in 98.8% of the mice, overriding all sex-specific and non-sex-specific genetic checkpoints. In contrast, F(2) mice immunized with emulsions where the bacterial products and encephalitogens are buried inside the water/oil vesicles exhibited a significant reduction in disease incidence (7.5%) and a sexual dimorphism (5% male versus 10% female). A genome scan identified QTL on chromosomes 7 and 11 controlling the sexual dimorphism as a function of the physical structure of the emulsion. The chromosome 11 QTL co-localizes with eae6b, and with Il12b and heptatitis A virus cellular receptor 2 (Havcr2, formerly known as Timd3), both of which are candidate genes for this QTL. Sequence analysis of the SJL/J and B10.S/SgMcdJ alleles indicates that both gene products are structurally monomorphic. Expression analysis also excluded both as candidates for this sex-specific QTL. These results reinforce the importance of gene-environment interactions in initiating and propagating autoimmune disease of the central nervous system, particularly in the context of susceptibility to MS and disease heterogeneity.
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Affiliation(s)
- Parley D Fillmore
- Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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32
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Butterfield RJ, Roper RJ, Rhein DM, Melvold RW, Haynes L, Ma RZ, Doerge RW, Teuscher C. Sex-specific quantitative trait loci govern susceptibility to Theiler's murine encephalomyelitis virus-induced demyelination. Genetics 2003; 163:1041-6. [PMID: 12663542 PMCID: PMC1462488 DOI: 10.1093/genetics/163.3.1041] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Susceptibility to Theiler's murine encephalomyelitis virus-induced demyelination (TMEVD), a mouse model for multiple sclerosis (MS), is genetically controlled. Through a mouse-human comparative mapping approach, identification of candidate susceptibility loci for MS based on the location of TMEVD susceptibility loci may be possible. Composite interval mapping (CIM) identified quantitative trait loci (QTL) controlling TMEVD severity in male and female backcross populations derived from susceptible DBA/2J and resistant BALBc/ByJ mice. We report QTL on chromosomes 1, 5, 15, and 16 affecting male mice. In addition, we identified two QTL in female mice located on chromosome 1. Our results support the existence of three linked sex-specific QTL on chromosome 1 with opposing effects on the severity of the clinical signs of TMEV-induced disease in male and female mice.
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Affiliation(s)
- Russell J Butterfield
- Department of Veterinary Pathobiology, University of Illinois, Urbana, Illinois 61802, USA
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33
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Abstract
The primary inherited optic neuropathies are a heterogeneous group of disorders that result in loss of retinal ganglion cells, leading to the clinical appearance of optic atrophy. They affect between 1:10,000 to 1:50,000 people. The main clinical features are a reduction in visual acuity, colour vision abnormalities, centro-caecal visual field defects and pallor of the optic nerve head. Electrophysiological testing shows a normal flash electroretinogram, absent or delayed pattern visually evoked potentials suggestive of a conduction deficit and N95 waveform reduction on the pattern electroretinogram, consistent with a primary ganglion cell pathology. The primary inherited optic neuropathies may be sporadic or familial. The mode of inheritance may be autosomal dominant, autosomal recessive, X-linked recessive or mitochondrial. Within each of these groups, the phenotypic characteristics vary in such features as the mode and age of onset, the severity of the visual loss, the colour deficit and the overall prognosis. A number of different genes (most as yet unidentified) in both nuclear and mitochondrial genomes, underlie these disorders. The elucidation of the role of the encoded proteins will improve our understanding of basic mechanisms of ganglion cell development, physiology and metabolism and further our understanding of the pathophysiology of optic nerve disease. It will also improve diagnosis, counselling and management of patients, and eventually lead to the development of new therapeutic modalities.
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Affiliation(s)
- M Votruba
- Department of Molecular Genetics, Institute of Ophthalmology, London, UK.
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34
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Valentino ML, Avoni P, Barboni P, Pallotti F, Rengo C, Torroni A, Bellan M, Baruzzi A, Carelli V. Mitochondrial DNA nucleotide changes C14482G and C14482A in the ND6 gene are pathogenic for Leber's hereditary optic neuropathy. Ann Neurol 2002; 51:774-8. [PMID: 12112086 DOI: 10.1002/ana.10193] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A novel mitochondrial DNA nucleotide transversion, C14482A (M64I), different from the previously reported C14482G (M64I), was found to cause Leber's hereditary optic neuropathy with visual recovery in an Italian family. These equivalent changes are the fifth pathogenic mutation for pure Leber's hereditary optic neuropathy. This confirms that the ND6 gene of complex I is a mutational hot spot and suggests that different amino acid substitutions at residue 64, as induced by C14482G or C14482A (M64I) and the common T14484C (M64V) mutations, are associated with visual recovery.
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Affiliation(s)
- Maria Lucia Valentino
- Dipartimento di Scienze Neurologiche, Università di Bologna, Via Ugo Foscolo 7, 40123 Bologna, Italy
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Abstract
Leber hereditary optic neuropathy (LHON) is a mitochondrial genetic disease that preferentially causes blindness in young adult males, affecting about 1 in 25 000 of the British population. It is characterised by bilateral subacute loss of central vision owing to focal degeneration of the retinal ganglion cell layer and optic nerve. Over 95% of LHON cases are primarily the result of one of three mitochondrial DNA (mtDNA) point mutations, G3460A, G11778A, and T14484C, which all involve genes encoding complex I subunits of the respiratory chain. An intriguing feature of LHON is that only approximately 50% of males and approximately 10% of females who harbour a pathogenic mtDNA mutation actually develop the optic neuropathy. This marked incomplete penetrance and gender bias imply that additional mitochondrial and/or nuclear genetic factors must be modulating the phenotypic expression of LHON. It is also likely that environmental factors contribute to the onset of visual failure. However, these secondary precipitating factors remain poorly defined at present. In this review, we describe the natural history of this optic nerve disorder and highlight issues relating to clinical diagnosis, management, and genetic counselling. We also discuss the findings of recently published studies and the light they shed on the complex aetiology and pathophysiology of LHON.
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Affiliation(s)
- P Yu-Wai-Man
- Department of Neurology, School of Neurosciences and Psychiatry, The Medical School, University of Newcastle Upon Tyne, UK
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36
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Carelli V. Chapter 4 Leber's Hereditary Optic Neuropathy. MITOCHONDRIAL DISORDERS IN NEUROLOGY 2 2002. [DOI: 10.1016/s1877-3419(09)70063-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Howell N, Kubacka I, McDonough B, Hodess AB, Harter DH. mtDNA analysis of Leber hereditary optic neuropathy associated with spondyloepiphyseal dysplasia. AMERICAN JOURNAL OF MEDICAL GENETICS 2001; 100:219-22. [PMID: 11343307 DOI: 10.1002/ajmg.1264] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A patient was diagnosed in 1974 with the unique combination of Leber hereditary optic neuropathy (LHON) and spondyloepiphyseal dysplasia. The entire mitochondrial DNA (mtDNA) sequence from this patient was determined in order to identify candidate pathogenic mutations. The patient's mtDNA carried the LHON mutation at nucleotide 14484, thus elucidating the etiology of his optic neuropathy. We also identified another ND6 mutation at nucleotide 14420. This latter mutation is probably a clinically benign private polymorphism, although a pathogenic role in his skeletal abnormalities or in his optic neuropathy cannot yet be ruled out.
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Affiliation(s)
- N Howell
- Department of Radiation Oncology, The University of Texas Medical Branch, Galveston, Texas 77555-0656, USA.
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38
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Wittig I, Augstein P, Brown GK, Fujii T, Rötig A, Rustin P, Munnich A, Seibel P, Thorburn D, Wissinger B, Tamboom K, Metspalu A, Lamantea E, Zeviani M, Wehnert MS. Sequence variations in the NDUFA1 gene encoding a subunit of complex I of the respiratory chain. J Inherit Metab Dis 2001; 24:15-27. [PMID: 11286378 DOI: 10.1023/a:1005638218246] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
NDUFA1 is one of the 36 nuclear genes encoding subunits of the mitochondrial complex I involved in the respiratory chain. The human NDUFA1 has been cloned, completely sequenced and mapped to Xq24. In the present study, we searched for sequence variations in NDUFA1 as causative defects in complex I deficiency using genomic DNA of 152 patients with various clinical phenotypes. The patient sample consisted of 54 patients (46 male and 8 female) with Leber heriditary optic neuropathy (LHON) from 48 unrelated families from Germany and 98 patients (72 male and 26 female) with biochemically proven complex I deficiency including Leigh syndrome. Patient DNA was used to amplify all three exons, including the exon/intron boundaries and the promoter region of NDUFA1 for heteroduplex analysis and direct sequencing. In the 152 patients tested, no mutation was found that could be related to any of the disease phenotypes included. However, three single-nucleotide polymorphisms (SNPs) located in the promoter region (SNP G/C at nt -71 and SNP T/C at nt -189) and in intron 1 (SNP T/G nt 1454) were discovered. Allele frequencies of the SNPs were estimated in a German and Estonian control population and compared to complex I-deficient patients. There was no significant difference between the control population, the LHON patients, or the severely affected patients with complex I deficiency, excluding an association of the polymorphisms with the diseases. Our results suggest that mutations in NDUFA1 do not cause the gender difference observed in clinically severe and complex phenotypes with complex I deficiency.
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Affiliation(s)
- I Wittig
- Institute of Human Genetics, Greifswald, Germany
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Chinnery PF, Brown DT, Andrews RM, Singh-Kler R, Riordan-Eva P, Lindley J, Applegarth DA, Turnbull DM, Howell N. The mitochondrial ND6 gene is a hot spot for mutations that cause Leber's hereditary optic neuropathy. Brain 2001; 124:209-18. [PMID: 11133798 DOI: 10.1093/brain/124.1.209] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is a common cause of bilateral optic nerve disease. The majority of LHON patients harbour one of three point mutations of the mitochondrial DNA (mtDNA) complex I, or NADH:ubiquinone oxidoreductase (ND) genes (G11778A in ND4, G3460A in ND1, T14484C in ND6). As a consequence, screening for these mutations has become part of the routine clinical investigation of young adults who present with bilateral optic neuropathy, and the absence of these mutations is interpreted as indicating there is a low likelihood that an optic neuropathy is LHON. However, there are many individuals who develop the clinical features of LHON but who do not harbour one of these primary LHON mutations. We describe two LHON pedigrees that harbour the same novel point mutation within the mtDNA ND6 gene (A14495G). This mutation was heteroplasmic in both families, and sequencing of the mitochondrial genome confirmed that the mutation arose on two independent occasions. This is the seventh mutation in the ND6 gene that causes optic neuropathy, indicating that this gene is a hot spot for LHON mutations. Protein modelling studies indicate that all of these pathogenic mutations lie within close proximity to one another in a hydrophobic cleft or pocket. This is the first evidence for a relationship between a specific disease phenotype and a specific structural domain within a mitochondrial respiratory chain subunit. These findings suggest that the mtDNA ND6 gene should be sequenced in all patients with LHON who do not harbour one of the three common LHON mutations.
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Affiliation(s)
- P F Chinnery
- Department of Neurology, The University of Newcastle upon Tyne, Newcastle upon Tyne, King's College Hospital, London, UK
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41
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Howell N. Human mitochondrial diseases: answering questions and questioning answers. INTERNATIONAL REVIEW OF CYTOLOGY 1998; 186:49-116. [PMID: 9770297 DOI: 10.1016/s0074-7696(08)61051-7] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Since the first identification in 1988 of pathogenic mitochondrial DNA (mtDNA) mutations, the mitochondrial diseases have emerged as a major clinical entity. The most striking feature of these disorders is their marked heterogeneity, which extends to their clinical, biochemical, and genetic characteristics. The major mitochondrial encephalomyopathies include MELAS (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes), MERRF (myoclonic epilepsy with ragged red fibers), KSS/CPEO (Kearns-Sayre syndrome/chronic progressive external ophthalmoplegia), and NARP/MILS (neuropathy, ataxia, and retinitis pigmentosum/maternally inherited Leigh syndrome) and they typically present highly variable multisystem defects that usually involve abnormalities of skeletal muscle and/or the CNS. The primary emphasis here is to review recent investigations of these mitochondrial diseases from the standpoint of how the complexities of mitochondrial genetics and biogenesis might determine their varied features. In addition, the mitochondrial encephalomyopathies are compared and contrasted to Leber hereditary optic neuropathy, a mitochondrial disease in which the pathogenic mtDNA mutations produce a more uniform and focal neuropathology. All of these disorders involve, at some level, a mitochondrial respiratory chain dysfunction. Because mitochondrial genetics differs so strikingly from the Mendelian inheritance of chromosomes, recent research on the origin and subsequent segregation and transmission of mtDNA mutations is reviewed.
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Affiliation(s)
- N Howell
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston 77555, USA.
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42
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Bai Y, Attardi G. The mtDNA-encoded ND6 subunit of mitochondrial NADH dehydrogenase is essential for the assembly of the membrane arm and the respiratory function of the enzyme. EMBO J 1998; 17:4848-58. [PMID: 9707444 PMCID: PMC1170814 DOI: 10.1093/emboj/17.16.4848] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Seven of the approximately 40 subunits of the mammalian respiratory NADH dehydrogenase (Complex I) are encoded in mitochondrial DNA (mtDNA). Their function is almost completely unknown. In this work, a novel selection scheme has led to the isolation of a mouse A9 cell derivative defective in NADH dehydrogenase activity. This cell line carries a near-homoplasmic frameshift mutation in the mtDNA gene for the ND6 subunit resulting in an almost complete absence of this polypeptide, while lacking any mutation in the other mtDNA-encoded subunits of the enzyme complex. Both the functional defect and the mutation were transferred with the mutant mitochondria into mtDNA-less (rho0) mouse LL/2-m21 cells, pointing to the pure mitochondrial genetic origin of the defect. A detailed biosynthetic and functional analysis of the original mutant and of the rho0 cell transformants revealed that the mutation causes a loss of assembly of the mtDNA-encoded subunits of the enzyme and, correspondingly, a reduction in malate/glutamate-dependent respiration in digitonin-permeabilized cells by approximately 90% and a decrease in NADH:Q1 oxidoreductase activity in mitochondrial extracts by approximately 99%. Furthermore, the ND6(-) cells, in contrast to the parental cells, completely fail to grow in a medium containing galactose instead of glucose, indicating a serious impairment in oxidative phosphorylation function. These observations provide the first evidence of the essential role of the ND6 subunit in the respiratory function of Complex I and give some insights into the pathogenic mechanism of the known disease-causing ND6 gene mutations.
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Affiliation(s)
- Y Bai
- Division of Biology, 156-29, California Institute of Technology, Pasadena, CA 91125, USA
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43
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Howell N, Bogolin C, Jamieson R, Marenda DR, Mackey DA. mtDNA mutations that cause optic neuropathy: how do we know? Am J Hum Genet 1998; 62:196-202. [PMID: 9443868 PMCID: PMC1376802 DOI: 10.1086/301675] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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