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Koludarova L, Battersby BJ. Mitochondrial protein synthesis quality control. Hum Mol Genet 2024; 33:R53-R60. [PMID: 38280230 PMCID: PMC11112378 DOI: 10.1093/hmg/ddae012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/05/2023] [Indexed: 01/29/2024] Open
Abstract
Human mitochondrial DNA is one of the most simplified cellular genomes and facilitates compartmentalized gene expression. Within the organelle, there is no physical barrier to separate transcription and translation, nor is there evidence that quality control surveillance pathways are active to prevent translation on faulty mRNA transcripts. Mitochondrial ribosomes synthesize 13 hydrophobic proteins that require co-translational insertion into the inner membrane of the organelle. To maintain the integrity of the inner membrane, which is essential for organelle function, requires responsive quality control mechanisms to recognize aberrations in protein synthesis. In this review, we explore how defects in mitochondrial protein synthesis can arise due to the culmination of inherent mistakes that occur throughout the steps of gene expression. In turn, we examine the stepwise series of quality control processes that are needed to eliminate any mistakes that would perturb organelle homeostasis. We aim to provide an integrated view on the quality control mechanisms of mitochondrial protein synthesis and to identify promising avenues for future research.
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Affiliation(s)
- Lidiia Koludarova
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki 00014, Finland
| | - Brendan J Battersby
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki 00014, Finland
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2
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Ali A, Esmaeil A, Behbehani R. Mitochondrial Chronic Progressive External Ophthalmoplegia. Brain Sci 2024; 14:135. [PMID: 38391710 PMCID: PMC10887352 DOI: 10.3390/brainsci14020135] [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: 12/25/2023] [Revised: 01/22/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024] Open
Abstract
BACKGROUND Chronic progressive external ophthalmoplegia (CPEO) is a rare disorder that can be at the forefront of several mitochondrial diseases. This review overviews mitochondrial CPEO encephalomyopathies to enhance accurate recognition and diagnosis for proper management. METHODS This study is conducted based on publications and guidelines obtained by selective review in PubMed. Randomized, double-blind, placebo-controlled trials, Cochrane reviews, and literature meta-analyses were particularly sought. DISCUSSION CPEO is a common presentation of mitochondrial encephalomyopathies, which can result from alterations in mitochondrial or nuclear DNA. Genetic sequencing is the gold standard for diagnosing mitochondrial encephalomyopathies, preceded by non-invasive tests such as fibroblast growth factor-21 and growth differentiation factor-15. More invasive options include a muscle biopsy, which can be carried out after uncertain diagnostic testing. No definitive treatment option is available for mitochondrial diseases, and management is mainly focused on lifestyle risk modification and supplementation to reduce mitochondrial load and symptomatic relief, such as ptosis repair in the case of CPEO. Nevertheless, various clinical trials and endeavors are still at large for achieving beneficial therapeutic outcomes for mitochondrial encephalomyopathies. KEY MESSAGES Understanding the varying presentations and genetic aspects of mitochondrial CPEO is crucial for accurate diagnosis and management.
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Affiliation(s)
- Ali Ali
- Neuro-Ophthalmology Unit, Ibn Sina Hospital, Al-Bahar Ophthalmology Center, Kuwait City 70035, Kuwait
| | - Ali Esmaeil
- Neuro-Ophthalmology Unit, Ibn Sina Hospital, Al-Bahar Ophthalmology Center, Kuwait City 70035, Kuwait
| | - Raed Behbehani
- Neuro-Ophthalmology Unit, Ibn Sina Hospital, Al-Bahar Ophthalmology Center, Kuwait City 70035, Kuwait
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3
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Shammas MK, Nie Y, Gilsrud A, Huang X, Narendra DP, Chinnery PF. CHCHD10 mutations induce tissue-specific mitochondrial DNA deletions with a distinct signature. Hum Mol Genet 2023; 33:91-101. [PMID: 37815936 PMCID: PMC10729859 DOI: 10.1093/hmg/ddad161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 09/11/2023] [Accepted: 09/19/2023] [Indexed: 10/12/2023] Open
Abstract
Mutations affecting the mitochondrial intermembrane space protein CHCHD10 cause human disease, but it is not known why different amino acid substitutions cause markedly different clinical phenotypes, including amyotrophic lateral sclerosis-frontotemporal dementia, spinal muscular atrophy Jokela-type, isolated autosomal dominant mitochondrial myopathy and cardiomyopathy. CHCHD10 mutations have been associated with deletions of mitochondrial DNA (mtDNA deletions), raising the possibility that these explain the clinical variability. Here, we sequenced mtDNA obtained from hearts, skeletal muscle, livers and spinal cords of WT and Chchd10 G58R or S59L knockin mice to characterise the mtDNA deletion signatures of the two mutant lines. We found that the deletion levels were higher in G58R and S59L mice than in WT mice in some tissues depending on the Chchd10 genotype, and the deletion burden increased with age. Furthermore, we observed that the spinal cord was less prone to the development of mtDNA deletions than the other tissues examined. Finally, in addition to accelerating the rate of naturally occurring deletions, Chchd10 mutations also led to the accumulation of a novel set of deletions characterised by shorter direct repeats flanking the deletion breakpoints. Our results indicate that Chchd10 mutations in mice induce tissue-specific deletions which may also contribute to the clinical phenotype associated with these mutations in humans.
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Affiliation(s)
- Mario K Shammas
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, United States
| | - Yu Nie
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
| | - Alexandra Gilsrud
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, United States
| | - Xiaoping Huang
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, United States
| | - Derek P Narendra
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, United States
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
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Ghosh Dastidar R, Banerjee S, Lal PB, Ghosh Dastidar S. Multifaceted Roles of AFG3L2, a Mitochondrial ATPase in Relation to Neurological Disorders. Mol Neurobiol 2023:10.1007/s12035-023-03768-z. [PMID: 38012514 DOI: 10.1007/s12035-023-03768-z] [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: 09/09/2023] [Accepted: 11/01/2023] [Indexed: 11/29/2023]
Abstract
AFG3L2 is a zinc metalloprotease and an ATPase localized in an inner mitochondrial membrane involved in mitochondrial quality control of several nuclear- and mitochondrial-encoded proteins. Mutations in AFG3L2 lead to diseases like slow progressive ataxia, which is a neurological disorder. This review delineates the cellular functions of AFG3L2 and its dysfunction that leads to major clinical outcomes, which include spinocerebellar ataxia type 28, spastic ataxia type 5, and optic atrophy type 12. It summarizes all relevant AFG3L2 mutations associated with the clinical outcomes to understand the detailed mechanisms attributable to its structure-related multifaceted roles in proteostasis and quality control. We face early diagnostic challenges of ataxia and optic neuropathy due to asymptomatic parents and variable clinical manifestations due to heterozygosity/homozygosity of AFG3L2 mutations. This review intends to promote AFG3L2 as a putative prognostic or diagnostic marker. Functions, mutations, and clinical manifestations in AFG3L2, a mitochondrial AAA + ATPases.
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Affiliation(s)
- Ranita Ghosh Dastidar
- Department of Biochemistry, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Madhava Nagar, Manipal, 576104, Karnataka, India.
| | - Saradindu Banerjee
- Centre for Molecular Neurosciences, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Madhava Nagar, Manipal, 576104, Karnataka, India
| | - Piyush Behari Lal
- Department of Microbiology, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Madhava Nagar, Manipal, 576104, Karnataka, India.
| | - Somasish Ghosh Dastidar
- Centre for Molecular Neurosciences, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Madhava Nagar, Manipal, 576104, Karnataka, India.
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Abstract
Progressive external ophthalmoplegia (PEO), characterized by ptosis and impaired eye movements, is a clinical syndrome with an expanding number of etiologically distinct subtypes. Advances in molecular genetics have revealed numerous pathogenic causes of PEO, originally heralded in 1988 by the detection of single large-scale deletions of mitochondrial DNA (mtDNA) in skeletal muscle of people with PEO and Kearns-Sayre syndrome. Since then, multiple point variants of mtDNA and nuclear genes have been identified to cause mitochondrial PEO and PEO-plus syndromes, including mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) and sensory ataxic neuropathy dysarthria ophthalmoplegia (SANDO). Intriguingly, many of those nuclear DNA pathogenic variants impair maintenance of the mitochondrial genome causing downstream mtDNA multiple deletions and depletion. In addition, numerous genetic causes of nonmitochondrial PEO have been identified.
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Affiliation(s)
- Michio Hirano
- H. Houston Merritt Neuromuscular Research Center, Neuromuscular Medicine Division, Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States.
| | - Robert D S Pitceathly
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom; NHS Highly Specialised Service for Rare Mitochondrial Disorders, Queen Square Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, United Kingdom
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Faria R, Albuquerque T, Neves AR, Sousa Â, Costa DRB. Nanotechnology to Correct Mitochondrial Disorders in Cancer Diseases. Cancer Nanotechnol 2023. [DOI: 10.1007/978-3-031-17831-3_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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232nd ENMC International Workshop: Recommendations for treatment of mitochondrial DNA maintenance disorders. 16 – 18 June 2017, Heemskerk, The Netherlands. Neuromuscul Disord 2022; 32:609-620. [DOI: 10.1016/j.nmd.2022.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 05/12/2022] [Indexed: 11/24/2022]
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Zeviani M, Carelli V. Mitochondrial Retinopathies. Int J Mol Sci 2021; 23:210. [PMID: 35008635 PMCID: PMC8745158 DOI: 10.3390/ijms23010210] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/14/2021] [Accepted: 12/18/2021] [Indexed: 12/13/2022] Open
Abstract
The retina is an exquisite target for defects of oxidative phosphorylation (OXPHOS) associated with mitochondrial impairment. Retinal involvement occurs in two ways, retinal dystrophy (retinitis pigmentosa) and subacute or chronic optic atrophy, which are the most common clinical entities. Both can present as isolated or virtually exclusive conditions, or as part of more complex, frequently multisystem syndromes. In most cases, mutations of mtDNA have been found in association with mitochondrial retinopathy. The main genetic abnormalities of mtDNA include mutations associated with neurogenic muscle weakness, ataxia and retinitis pigmentosa (NARP) sometimes with earlier onset and increased severity (maternally inherited Leigh syndrome, MILS), single large-scale deletions determining Kearns-Sayre syndrome (KSS, of which retinal dystrophy is a cardinal symptom), and mutations, particularly in mtDNA-encoded ND genes, associated with Leber hereditary optic neuropathy (LHON). However, mutations in nuclear genes can also cause mitochondrial retinopathy, including autosomal recessive phenocopies of LHON, and slowly progressive optic atrophy caused by dominant or, more rarely, recessive, mutations in the fusion/mitochondrial shaping protein OPA1, encoded by a nuclear gene on chromosome 3q29.
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Affiliation(s)
- Massimo Zeviani
- Department of Neurosciences, The Clinical School, University of Padova, 35128 Padova, Italy
- Veneto Institute of Molecular Medicine, Via Orus 2, 35128 Padova, Italy
| | - Valerio Carelli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40139 Bologna, Italy
- Programma di Neurogenetica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Via Altura 6, 40139 Bologna, Italy
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Liu X, Wang L, Chen J, Kang C, Li J. Spinocerebellar ataxia type 28 in a Chinese pedigree: A case report and literature review. Medicine (Baltimore) 2021; 100:e28008. [PMID: 34918652 PMCID: PMC8678014 DOI: 10.1097/md.0000000000028008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 11/11/2021] [Indexed: 01/05/2023] Open
Abstract
RATIONALE Spinocerebellar ataxia (SCA) is a common neurogenetic disease that mainly manifests as ataxia of posture, gait, and limbs, cerebellar dysarthria, and cerebellar and supranuclear eye movement disorders. SCA has been found to include many subtypes, which are mainly mapped to 2 genetic patterns: autosomal dominant cerebellar ataxia and autosomal recessive cerebellar ataxia. Molecular genetic diagnosis functions as a necessity in its clinical diagnosis and treatment. In preliminary clinical work, we identified a family of SCA28 with rare gene mutation. PATIENT CONCERNS There are 5 patients in this family. The proband is a 32 year-old male, he mainly manifest unsteady steps for more than 7 months. The daughter of his younger maternal uncle gradually had unsteady steps and unclear speech for 5 years. The proband's mother, uncle and grandfather had similar symptoms, but they all died. DIAGNOSIS After Brain magnetic resonance imaging, whole exome sequencing and Sanger validation, the patients presented a c.1852A > G missense mutation in the exon region of AFG3L2 gene. The other family members revealed no AFG3L2 mutations. SCA28 is the one uniquely caused by a pathogenic variation in the mitochondrial protein AFG3L2. Combined with the clinical manifestations, auxiliary examinations and sequencing results of the patients (III-3 and III-5), the diagnosis of SCA28 was suspected. INTERVENTIONS The patients did not receive any drug treatment and the proband receive rehabilitation treatment. OUTCOMES The symptoms of ataxia were still progressively aggravated. LESSONS Molecular genetic diagnosis is necessary for ataxia. We here report the case and review the literature.
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10
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Wilson D, Hallett M, Anderson T. An Eye on Movement Disorders. Mov Disord Clin Pract 2021; 8:1168-1180. [PMID: 34765682 DOI: 10.1002/mdc3.13317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/28/2021] [Accepted: 07/20/2021] [Indexed: 02/06/2023] Open
Abstract
Eye disorders spanning a range of ocular tissue are common in patients with movement disorders. Highlighting these ocular manifestations will benefit patients and may even aid in diagnosis. In this educational review we outline the anatomy and function of the ocular tissues with a focus on the tissues most affected in movement disorders. We review the movement disorders associated with ocular pathology and where possible explore the underlying cellular basis thought to be driving the pathology and provide a brief overview of ophthalmic investigations available to the neurologist. This review does not cover intracranial primary visual pathways, higher visual function, or the ocular motor system.
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Affiliation(s)
- Duncan Wilson
- Department of Neurology Christchurch Hospital Christchurch New Zealand.,New Zealand Brain Research Institute Christchurch New Zealand
| | - Mark Hallett
- Human Motor Control Section, NINDS, NIH Bethesda Maryland USA
| | - Tim Anderson
- Department of Neurology Christchurch Hospital Christchurch New Zealand.,New Zealand Brain Research Institute Christchurch New Zealand.,Department of Medicine Otago University Dunedin New Zealand
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11
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Ng KY, Richter U, Jackson CB, Seneca S, Battersby BJ. Translation of MT-ATP6 pathogenic variants reveals distinct regulatory consequences from the co-translational quality control of mitochondrial protein synthesis. Hum Mol Genet 2021; 31:1230-1241. [PMID: 34718584 PMCID: PMC9029222 DOI: 10.1093/hmg/ddab314] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 11/16/2022] Open
Abstract
Pathogenic variants that disrupt human mitochondrial protein synthesis are associated with a clinically heterogeneous group of diseases. Despite an impairment in oxidative phosphorylation being a common phenotype, the underlying molecular pathogenesis is more complex than simply a bioenergetic deficiency. Currently, we have limited mechanistic understanding on the scope by which a primary defect in mitochondrial protein synthesis contributes to organelle dysfunction. Since the proteins encoded in the mitochondrial genome are hydrophobic and need co-translational insertion into a lipid bilayer, responsive quality control mechanisms are required to resolve aberrations that arise with the synthesis of truncated and misfolded proteins. Here, we show that defects in the OXA1L-mediated insertion of MT-ATP6 nascent chains into the mitochondrial inner membrane are rapidly resolved by the AFG3L2 protease complex. Using pathogenic MT-ATP6 variants, we then reveal discrete steps in this quality control mechanism and the differential functional consequences to mitochondrial gene expression. The inherent ability of a given cell type to recognize and resolve impairments in mitochondrial protein synthesis may in part contribute at the molecular level to the wide clinical spectrum of these disorders.
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Affiliation(s)
- Kah Ying Ng
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Uwe Richter
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.,Wellcome Centre for Mitochondrial Research, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Christopher B Jackson
- Department of Biochemistry and Developmental Biology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Sara Seneca
- Center for Medical Genetics/Research Center Reproduction and Genetics, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
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12
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Chiang HL, Fuh JL, Tsai YS, Soong BW, Liao YC, Lee YC. Expanding the phenotype of AFG3L2 mutations: Late-onset autosomal recessive spinocerebellar ataxia. J Neurol Sci 2021; 428:117600. [PMID: 34333379 DOI: 10.1016/j.jns.2021.117600] [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: 04/18/2021] [Revised: 06/28/2021] [Accepted: 07/25/2021] [Indexed: 10/20/2022]
Abstract
The AFG3L2 gene encodes AFG3-like protein 2, which is a subunit of human mitochondrial ATPases associated with various cellular protease activities (m-AAA). The clinical spectrum of AFG3L2 mutations is broad. Dominant AFG3L2 mutations can cause autosomal dominant spinocerebellar ataxia type 28 (SCA28), whereas biallelic AFG3L2 mutations may lead to spastic ataxia 5 (SPAX5). However, the role of AFG3L2 mutations in autosomal recessive spinocerebellar ataxia (SCAR) remains elusive. The aim of this study is to delineate the clinical features and spectrum of AFG3L2 mutations in a Taiwanese cohort with cerebellar ataxia. Mutational analyses of AFG3L2 were carried out by targeted resequencing in a cohort of 133 unrelated patients with molecularly undetermined cerebellar ataxia. We identified one single patient carrying compound heterozygous mutations in AFG3L2, p.[R632*];[V723M] (c.[1894C > T];[2167G > A]). The patient has suffered from apparently sporadic and slowly progressive cerebellar ataxia, ptosis, and ophthalmoparesis since age 55 years. These findings expand the clinical spectrum of AFG3L2 mutations and suggest a new subtype of late-onset SCAR caused by biallelic AFG3L2 mutations.
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Affiliation(s)
- Han-Lin Chiang
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec.2, Shipai Rd., Beitou District, Taipei, Taiwan; School of Medicine, National Yang Ming Chiao Tung University College of Medicine, No.155, Sec.2, Linong Street, Taipei, Taiwan
| | - Jong-Ling Fuh
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec.2, Shipai Rd., Beitou District, Taipei, Taiwan; School of Medicine, National Yang Ming Chiao Tung University College of Medicine, No.155, Sec.2, Linong Street, Taipei, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University School of Medicine. No.155, Sec.2, Linong Street, Taipei, Taiwan
| | - Yu-Shuen Tsai
- Center for Systems and Synthetic Biology, National Yang Ming Chiao Tung University, No.155, Sec.2, Linong Street, Taipei, Taiwan
| | - Bing-Wen Soong
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec.2, Shipai Rd., Beitou District, Taipei, Taiwan; Department of Neurology, Shuang Ho Hospital, Taipei Medical University, No.291, Zhongzheng Rd., Zhonghe District, New Taipei 23561, Taiwan; Taipei Neuroscience Institute, Taipei Medical University, 250 Wu-Hsing Street, Taipei, Taiwan
| | - Yi-Chu Liao
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec.2, Shipai Rd., Beitou District, Taipei, Taiwan; School of Medicine, National Yang Ming Chiao Tung University College of Medicine, No.155, Sec.2, Linong Street, Taipei, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University School of Medicine. No.155, Sec.2, Linong Street, Taipei, Taiwan
| | - Yi-Chung Lee
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec.2, Shipai Rd., Beitou District, Taipei, Taiwan; School of Medicine, National Yang Ming Chiao Tung University College of Medicine, No.155, Sec.2, Linong Street, Taipei, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University School of Medicine. No.155, Sec.2, Linong Street, Taipei, Taiwan.
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Ramón J, Vila-Julià F, Molina-Granada D, Molina-Berenguer M, Melià MJ, García-Arumí E, Torres-Torronteras J, Cámara Y, Martí R. Therapy Prospects for Mitochondrial DNA Maintenance Disorders. Int J Mol Sci 2021; 22:6447. [PMID: 34208592 PMCID: PMC8234938 DOI: 10.3390/ijms22126447] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 02/07/2023] Open
Abstract
Mitochondrial DNA depletion and multiple deletions syndromes (MDDS) constitute a group of mitochondrial diseases defined by dysfunctional mitochondrial DNA (mtDNA) replication and maintenance. As is the case for many other mitochondrial diseases, the options for the treatment of these disorders are rather limited today. Some aggressive treatments such as liver transplantation or allogeneic stem cell transplantation are among the few available options for patients with some forms of MDDS. However, in recent years, significant advances in our knowledge of the biochemical pathomechanisms accounting for dysfunctional mtDNA replication have been achieved, which has opened new prospects for the treatment of these often fatal diseases. Current strategies under investigation to treat MDDS range from small molecule substrate enhancement approaches to more complex treatments, such as lentiviral or adenoassociated vector-mediated gene therapy. Some of these experimental therapies have already reached the clinical phase with very promising results, however, they are hampered by the fact that these are all rare disorders and so the patient recruitment potential for clinical trials is very limited.
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Affiliation(s)
- Javier Ramón
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Ferran Vila-Julià
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - David Molina-Granada
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Miguel Molina-Berenguer
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Maria Jesús Melià
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Elena García-Arumí
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Javier Torres-Torronteras
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Yolanda Cámara
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Ramon Martí
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
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Chapman J, Ng YS, Nicholls TJ. The Maintenance of Mitochondrial DNA Integrity and Dynamics by Mitochondrial Membranes. Life (Basel) 2020; 10:life10090164. [PMID: 32858900 PMCID: PMC7555930 DOI: 10.3390/life10090164] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/20/2020] [Accepted: 08/23/2020] [Indexed: 12/18/2022] Open
Abstract
Mitochondria are complex organelles that harbour their own genome. Mitochondrial DNA (mtDNA) exists in the form of a circular double-stranded DNA molecule that must be replicated, segregated and distributed around the mitochondrial network. Human cells typically possess between a few hundred and several thousand copies of the mitochondrial genome, located within the mitochondrial matrix in close association with the cristae ultrastructure. The organisation of mtDNA around the mitochondrial network requires mitochondria to be dynamic and undergo both fission and fusion events in coordination with the modulation of cristae architecture. The dysregulation of these processes has profound effects upon mtDNA replication, manifesting as a loss of mtDNA integrity and copy number, and upon the subsequent distribution of mtDNA around the mitochondrial network. Mutations within genes involved in mitochondrial dynamics or cristae modulation cause a wide range of neurological disorders frequently associated with defects in mtDNA maintenance. This review aims to provide an understanding of the biological mechanisms that link mitochondrial dynamics and mtDNA integrity, as well as examine the interplay that occurs between mtDNA, mitochondrial dynamics and cristae structure.
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Affiliation(s)
- James Chapman
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Correspondence: (J.C.); (T.J.N.)
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Thomas J. Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Correspondence: (J.C.); (T.J.N.)
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15
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Chen D, Zhao Q, Xiong J, Lou X, Han Q, Wei X, Xie J, Li X, Zhou H, Shen L, Yang Y, Fang H, Lyu J. Systematic analysis of a mitochondrial disease-causing ND6 mutation in mitochondrial deficiency. Mol Genet Genomic Med 2020; 8:e1199. [PMID: 32162843 PMCID: PMC7216815 DOI: 10.1002/mgg3.1199] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 02/07/2020] [Accepted: 02/14/2020] [Indexed: 12/24/2022] Open
Abstract
Background The m.14487T>C mutation is recognized as a diagnostic mutation of mitochondrial disease during the past 16 years, emerging evidence suggests that mutant loads of m.14487T>C and disease phenotype are not closely correlated. Methods Immortalized lymphocytes were generated by coculturing the Epstein–Barr virus and lymphocytes from m.14487T>C carrier Chinese patient with Leigh syndrome. Fifteen cytoplasmic hybrid (cybrid) cell lines were generated by fusing mtDNA lacking 143B cells with platelets donated by patients. Mitochondrial function was systematically analyzed at transcriptomic, metabolomic, and biochemical levels. Results Unlike previous reports, we found that the assembly of mitochondrial respiratory chain complexes, mitochondrial respiration, and mitochondrial OXPHOS function was barely affected in cybrid cells carrying homoplastic m.14487T>C mutation. Mitochondrial dysfunction associated transcriptomic and metabolomic reprogramming were not detected in cybrid carrying homoplastic m.14487T>C. However, we found that mitochondrial function was impaired in patient‐derived immortalized lymphocytes. Conclusion Our data revealed that m.14487T>C mutation is insufficient to cause mitochondrial deficiency; additional modifier genes may be involved in m.14487T>C‐associated mitochondrial disease. Our results further demonstrated that a caution should be taken by solely use of m.14487T>C mutation for molecular diagnosis of mitochondrial disease.
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Affiliation(s)
- Deyu Chen
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, China
| | - Qiongya Zhao
- Zhejiang Provincial People's Hospital, Affiliated People's Hospital of Hangzhou Medical College, College of Laboratory Medicine, Hangzhou Medical College, Hangzhou, China
| | - Jingting Xiong
- Department of Laboratory Medicine, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoting Lou
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, China
| | - Qinxia Han
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, China
| | - Xiujuan Wei
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, China
| | - Jie Xie
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, China
| | - Xueyun Li
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, China
| | - Huaibin Zhou
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, China
| | - Lijun Shen
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, China
| | - Yanling Yang
- Department of Pediatrics, Peking University First Hospital, Peking University, Beijing, China
| | - Hezhi Fang
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, China
| | - Jianxin Lyu
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou, China.,Zhejiang Provincial People's Hospital, Affiliated People's Hospital of Hangzhou Medical College, College of Laboratory Medicine, Hangzhou Medical College, Hangzhou, China
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16
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Hjelm BE, Rollins B, Morgan L, Sequeira A, Mamdani F, Pereira F, Damas J, Webb MG, Weber MD, Schatzberg AF, Barchas JD, Lee FS, Akil H, Watson SJ, Myers RM, Chao EC, Kimonis V, Thompson PM, Bunney WE, Vawter MP. Splice-Break: exploiting an RNA-seq splice junction algorithm to discover mitochondrial DNA deletion breakpoints and analyses of psychiatric disorders. Nucleic Acids Res 2019; 47:e59. [PMID: 30869147 PMCID: PMC6547454 DOI: 10.1093/nar/gkz164] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 02/28/2019] [Indexed: 12/20/2022] Open
Abstract
Deletions in the 16.6 kb mitochondrial genome have been implicated in numerous disorders that often display muscular and/or neurological symptoms due to the high-energy demands of these tissues. We describe a catalogue of 4489 putative mitochondrial DNA (mtDNA) deletions, including their frequency and relative read rate, using a combinatorial approach of mitochondria-targeted PCR, next-generation sequencing, bioinformatics, post-hoc filtering, annotation, and validation steps. Our bioinformatics pipeline uses MapSplice, an RNA-seq splice junction detection algorithm, to detect and quantify mtDNA deletion breakpoints rather than mRNA splices. Analyses of 93 samples from postmortem brain and blood found (i) the 4977 bp ‘common deletion’ was neither the most frequent deletion nor the most abundant; (ii) brain contained significantly more deletions than blood; (iii) many high frequency deletions were previously reported in MitoBreak, suggesting they are present at low levels in metabolically active tissues and are not exclusive to individuals with diagnosed mitochondrial pathologies; (iv) many individual deletions (and cumulative metrics) had significant and positive correlations with age and (v) the highest deletion burdens were observed in major depressive disorder brain, at levels greater than Kearns–Sayre Syndrome muscle. Collectively, these data suggest the Splice-Break pipeline can detect and quantify mtDNA deletions at a high level of resolution.
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Affiliation(s)
- Brooke E Hjelm
- Department of Psychiatry and Human Behavior, University of California-Irvine (UCI), Irvine, CA 92697, USA.,Department of Translational Genomics, Keck School of Medicine of USC, University of Southern California (USC), Los Angeles, CA 90033, USA
| | - Brandi Rollins
- Department of Psychiatry and Human Behavior, University of California-Irvine (UCI), Irvine, CA 92697, USA
| | - Ling Morgan
- Department of Psychiatry and Human Behavior, University of California-Irvine (UCI), Irvine, CA 92697, USA
| | - Adolfo Sequeira
- Department of Psychiatry and Human Behavior, University of California-Irvine (UCI), Irvine, CA 92697, USA
| | - Firoza Mamdani
- Department of Psychiatry and Human Behavior, University of California-Irvine (UCI), Irvine, CA 92697, USA
| | - Filipe Pereira
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Matosinhos 4050-123, Portugal
| | - Joana Damas
- The Genome Center, University of California-Davis, Davis, CA 95616, USA
| | - Michelle G Webb
- Department of Translational Genomics, Keck School of Medicine of USC, University of Southern California (USC), Los Angeles, CA 90033, USA
| | - Matthieu D Weber
- Department of Psychiatry and Human Behavior, University of California-Irvine (UCI), Irvine, CA 92697, USA
| | - Alan F Schatzberg
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Jack D Barchas
- Department of Psychiatry, Weill Cornell Medical College at Cornell University, New York, NY 10065, USA
| | - Francis S Lee
- Department of Psychiatry, Weill Cornell Medical College at Cornell University, New York, NY 10065, USA
| | - Huda Akil
- The Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Stanley J Watson
- The Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Richard M Myers
- HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - Elizabeth C Chao
- Division of Genetics and Genomic Medicine, Department of Pediatrics, UCI, Irvine, CA, USA
| | - Virginia Kimonis
- Division of Genetics and Genomic Medicine, Department of Pediatrics, UCI, Irvine, CA, USA
| | - Peter M Thompson
- Southwest Brain Bank, Department of Psychiatry, Texas Tech University Health Sciences Center (TTUHSC), El Paso, TX 79905, USA
| | - William E Bunney
- Department of Psychiatry and Human Behavior, University of California-Irvine (UCI), Irvine, CA 92697, USA
| | - Marquis P Vawter
- Department of Psychiatry and Human Behavior, University of California-Irvine (UCI), Irvine, CA 92697, USA
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17
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Battersby BJ, Richter U, Safronov O. Mitochondrial Nascent Chain Quality Control Determines Organelle Form and Function. ACS Chem Biol 2019; 14:2396-2405. [PMID: 31498990 DOI: 10.1021/acschembio.9b00518] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Proteotoxicity has long been considered a key factor in mitochondrial dysfunction and human disease. The origin of the endogenous offending toxic substrates and the regulatory pathways to deal with these insults, however, have remained unclear. Mitochondria maintain a compartmentalized gene expression system that in animals is only responsible for synthesis of 1% of the organelle proteome. Because of the relatively small contribution of the mitochondrial genome to the overall proteome, the synthesis and quality control of these nascent chains to maintain organelle proteostasis has long been overlooked. However, recent research has uncovered mechanisms by which defects to the quality control of mitochondrial gene expression are linked to a novel cellular stress response that impinges upon organelle form and function and cell fitness. In this review, we discuss the mechanisms for a key event in the response: activation of the metalloprotease OMA1. This severs the membrane tether of the dynamin-related GTPase OPA1, which is a critical determinant for mitochondrial morphology and function. We also highlight the evolutionary conservation from bacteria of these quality-control mechanisms to maintain membrane integrity, gene expression, and cell fitness.
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Affiliation(s)
| | - Uwe Richter
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
| | - Omid Safronov
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
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18
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Catania A, Legati A, Peverelli L, Nanetti L, Marchet S, Zanetti N, Lamperti C, Ghezzi D. Homozygous variant in OTX2 and possible genetic modifiers identified in a patient with combined pituitary hormone deficiency, ocular involvement, myopathy, ataxia, and mitochondrial impairment. Am J Med Genet A 2019; 179:827-831. [PMID: 30773800 DOI: 10.1002/ajmg.a.61092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 01/21/2019] [Accepted: 01/22/2019] [Indexed: 12/22/2022]
Abstract
Here we report on a singleton patient affected by a complicated congenital syndrome characterized by growth delay, retinal dystrophy, sensorineural deafness, myopathy, ataxia, combined pituitary hormone deficiency, associated with mitochondrial impairment. Targeted clinical exome sequencing led to the identification of a homozygous missense variant in OTX2. Since only dominant mutations within OTX2 have been associated with cases of syndromic microphthalmia, retinal dystrophy with or without pituitary dysfunctions, this represents the first report of an OTX2 recessive mutation. Part of the phenotype, including ataxia, myopathy and multiple mitochondrial respiratory chain defects, seemed not related to OTX2. Further analysis of next generation sequencing (NGS) data revealed additional candidate variants: a homozygous variant in LETM1, and heterozygous rare variants in AFG3L2 and POLG. All three genes encode mitochondrial proteins and the last two are known to be associated with ataxia, a neurological sign present also in the father of the proband. With our study, we aim to encourage the integration of NGS data with a detailed analysis of clinical description and family history in order to unravel composite genotypes sometimes associated with complicated phenotypes.
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Affiliation(s)
- Alessia Catania
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Andrea Legati
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Lorenzo Peverelli
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.,Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Lorenzo Nanetti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Silvia Marchet
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Nadia Zanetti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Costanza Lamperti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Daniele Ghezzi
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.,Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
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19
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Almomen M, Martens K, Quadir A, Pontifex CS, Hanson A, Korngut L, Pfeffer G. High diagnostic yield and novel variants in very late-onset spasticity. J Neurogenet 2019; 33:27-32. [PMID: 30747022 DOI: 10.1080/01677063.2019.1566326] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Hereditary spastic paraplegias (HSPs) are a diverse group of genetic conditions with variable severity and onset age. From a neurogenetic clinic, we identified 14 patients with very late-onset HSP, with symptoms starting after the age of 35. In this cohort, sequencing of known genetic causes was performed using clinically available HSP sequencing panels. We identified 4 patients with mutations in SPG7 and 3 patients with SPAST mutations, representing 50% of the cohort and indicating a very high diagnostic yield. In the SPG7 group, we identified novel variants in two patients. We have also identified two novel mutations in the SPAST group. We present sequencing data from cDNA and RT-qPCR to support the pathogenicity of these variants, and provide observations regarding the poor genotype-phenotype correlation in these conditions that should be the subject of future study.
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Affiliation(s)
- Momen Almomen
- a Section of Neurology, Department of Pediatrics , University of Calgary , Calgary , Canada
| | - Kristina Martens
- b Hotchkiss Brain Institute, University of Calgary , Calgary , Canada
| | - Asfia Quadir
- b Hotchkiss Brain Institute, University of Calgary , Calgary , Canada
| | | | - Alexandra Hanson
- c Department of Clinical Neurosciences , Cumming School of Medicine, University of Calgary , Calgary , Canada
| | - Lawrence Korngut
- b Hotchkiss Brain Institute, University of Calgary , Calgary , Canada.,c Department of Clinical Neurosciences , Cumming School of Medicine, University of Calgary , Calgary , Canada
| | - Gerald Pfeffer
- b Hotchkiss Brain Institute, University of Calgary , Calgary , Canada.,c Department of Clinical Neurosciences , Cumming School of Medicine, University of Calgary , Calgary , Canada
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20
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Richter U, Ng KY, Suomi F, Marttinen P, Turunen T, Jackson C, Suomalainen A, Vihinen H, Jokitalo E, Nyman TA, Isokallio MA, Stewart JB, Mancini C, Brusco A, Seneca S, Lombès A, Taylor RW, Battersby BJ. Mitochondrial stress response triggered by defects in protein synthesis quality control. Life Sci Alliance 2019; 2:2/1/e201800219. [PMID: 30683687 PMCID: PMC6348486 DOI: 10.26508/lsa.201800219] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 01/16/2019] [Accepted: 01/17/2019] [Indexed: 12/11/2022] Open
Abstract
Quality control defects of mitochondrial nascent chain synthesis trigger a sequential stress response characterized by OMA1 activation and ribosome decay, determining mitochondrial form and function. Mitochondria have a compartmentalized gene expression system dedicated to the synthesis of membrane proteins essential for oxidative phosphorylation. Responsive quality control mechanisms are needed to ensure that aberrant protein synthesis does not disrupt mitochondrial function. Pathogenic mutations that impede the function of the mitochondrial matrix quality control protease complex composed of AFG3L2 and paraplegin cause a multifaceted clinical syndrome. At the cell and molecular level, defects to this quality control complex are defined by impairment to mitochondrial form and function. Here, we establish the etiology of these phenotypes. We show how disruptions to the quality control of mitochondrial protein synthesis trigger a sequential stress response characterized first by OMA1 activation followed by loss of mitochondrial ribosomes and by remodelling of mitochondrial inner membrane ultrastructure. Inhibiting mitochondrial protein synthesis with chloramphenicol completely blocks this stress response. Together, our data establish a mechanism linking major cell biological phenotypes of AFG3L2 pathogenesis and show how modulation of mitochondrial protein synthesis can exert a beneficial effect on organelle homeostasis.
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Affiliation(s)
- Uwe Richter
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Kah Ying Ng
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Fumi Suomi
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Paula Marttinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Taina Turunen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Christopher Jackson
- Research Programs Unit-Molecular Neurology, University of Helsinki, Helsinki, Finland
| | - Anu Suomalainen
- Research Programs Unit-Molecular Neurology, University of Helsinki, Helsinki, Finland
| | - Helena Vihinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Eija Jokitalo
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Tuula A Nyman
- Department of Immunology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
| | | | - James B Stewart
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Cecilia Mancini
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Alfredo Brusco
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Sara Seneca
- Center for Medical Genetics/Research Center Reproduction and Genetics, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Anne Lombès
- Faculté de médecine Cochin, Institut Cochin Institut national de la santé et de la recherche médicale U1016, Centre national de la recherche scientifique Unités Mixtes de Recherche 8104, Université Paris 5, Paris, France
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
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21
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Muneer A, Shamsher Khan RM. Endoplasmic Reticulum Stress: Implications for Neuropsychiatric Disorders. Chonnam Med J 2019; 55:8-19. [PMID: 30740335 PMCID: PMC6351318 DOI: 10.4068/cmj.2019.55.1.8] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/11/2018] [Accepted: 11/09/2018] [Indexed: 11/06/2022] Open
Abstract
The Endoplasmic reticulum (ER), an indispensable sub-cellular component of the eukaryotic cell carries out essential functions, is critical to the survival of the organism. The chaperone proteins and the folding enzymes which are multi-domain ER effectors carry out 3-dimensional conformation of nascent polypeptides and check misfolded protein aggregation, easing the exit of functional proteins from the ER. Diverse conditions, for instance redox imbalance, alterations in ionic calcium levels, and inflammatory signaling can perturb the functioning of the ER, leading to a build-up of unfolded or misfolded proteins in the lumen. This results in ER stress, and aiming to reinstate protein homeostasis, a well conserved reaction called the unfolded protein response (UPR) is elicited. Equally, in protracted cellular stress or inadequate compensatory reaction, UPR pathway leads to cell loss. Dysfunctional ER mechanisms are responsible for neuronal degeneration in numerous human diseases, for instance Alzheimer's, Parkinson's and Huntington's diseases. In addition, mounting proof indicates that ER stress is incriminated in psychiatric diseases like major depressive disorder, bipolar disorder, and schizophrenia. Accumulating evidence suggests that pharmacological agents regulating the working of ER may have a role in diminishing advancing neuronal dysfunction in neuropsychiatric disorders. Here, new findings are examined which link the foremost mechanisms connecting ER stress and cell homeostasis. Furthermore, a supposed new pathogenic model of major neuropsychiatry disorders is provided, with ER stress proposed as the pivotal step in disease development.
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Affiliation(s)
- Ather Muneer
- Islamic International Medical College, Riphah International University, Rawalpindi, Pakistan
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22
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Neurocognitive Characterization of an SCA28 Family Caused by a Novel AFG3L2 Gene Mutation. THE CEREBELLUM 2018; 16:979-985. [PMID: 28660440 DOI: 10.1007/s12311-017-0870-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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23
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Mancini C, Giorgio E, Rubegni A, Pradotto L, Bagnoli S, Rubino E, Prontera P, Cavalieri S, Di Gregorio E, Ferrero M, Pozzi E, Riberi E, Ferrero P, Nigro P, Mauro A, Zibetti M, Tessa A, Barghigiani M, Antenora A, Sirchia F, Piacentini S, Silvestri G, De Michele G, Filla A, Orsi L, Santorelli FM, Brusco A. Prevalence and phenotype of the c.1529C>T SPG7 variant in adult-onset cerebellar ataxia in Italy. Eur J Neurol 2018; 26:80-86. [PMID: 30098094 DOI: 10.1111/ene.13768] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 08/07/2018] [Indexed: 12/17/2022]
Abstract
BACKGROUND AND PURPOSE Hereditary ataxias are heterogeneous groups of neurodegenerative disorders, characterized by cerebellar syndromes associated with dysarthria, oculomotor and corticospinal signs, neuropathy and cognitive impairment. Recent reports have suggested mutations in the SPG7 gene, causing the most common form of autosomal recessive spastic paraplegia (MIM#607259), as a main cause of ataxias. The majority of described patients were homozygotes or compound heterozygotes for the c.1529C>T (p.Ala510Val) change. We screened a cohort of 895 Italian patients with ataxia for p.Ala510Val in order to define the prevalence and genotype-phenotype correlation of this variant. METHODS We set up a rapid assay for c.1529C>T using restriction enzyme analysis after polymerase chain reaction amplification. We confirmed the diagnosis with Sanger sequencing. RESULTS We identified eight homozygotes and 13 compound heterozygotes, including two novel variants affecting splicing. Mutated patients showed a pure cerebellar ataxia at onset, evolving in mild spastic ataxia (alternatively) associated with dysarthria (~80% of patients), urinary urgency (~30%) and pyramidal signs (~70%). Comparing homozygotes and compound heterozygotes, we noted a difference in age at onset and Scale for the Assessment and Rating of Ataxia score between the two groups, supporting an earlier and more severe phenotype in compound heterozygotes versus homozygotes. CONCLUSIONS The SPG7 c.1529C>T (p.Ala510Val) mutants accounted for 2.3% of cerebellar ataxia cases in Italy, suggesting that this variant should be considered as a priority test in the presence of late-onset pure ataxia. Moreover, the heterozygous/homozygous genotype appeared to predict the onset of clinical manifestation and disease progression.
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Affiliation(s)
- C Mancini
- Department of Medical Sciences, University of Torino, Turin, Italy
| | - E Giorgio
- Department of Medical Sciences, University of Torino, Turin, Italy
| | - A Rubegni
- Molecular Medicine, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - L Pradotto
- Division of Neurology and Neurorehabilitation, San Giuseppe Hospital, IRCCS Istituto Auxologico Italiano, Piancavallo, Italy
| | - S Bagnoli
- Department of Neuroscience, Psychology, Drug Research and Child's Health, University of Florence, Florence, Italy
| | - E Rubino
- Department of Neuroscience and Mental Health, Città della Salute e della Scienza University Hospital, Turin, Italy
| | - P Prontera
- Medical Genetics Unit, Hospital S. Maria della Misericordia, Perugia, Italy
| | - S Cavalieri
- Department of Medical Sciences, University of Torino, Turin, Italy
| | - E Di Gregorio
- Department of Medical Sciences, University of Torino, Turin, Italy
| | - M Ferrero
- Department of Medical Sciences, University of Torino, Turin, Italy
| | - E Pozzi
- Department of Medical Sciences, University of Torino, Turin, Italy
| | - E Riberi
- Department of Medical Sciences, University of Torino, Turin, Italy
| | - P Ferrero
- Department of Neuroscience and Mental Health, Città della Salute e della Scienza University Hospital, Turin, Italy
| | - P Nigro
- Clinica Neurologica, Azienda Ospedaliera - Università di Perugia, Perugia, Italy
| | - A Mauro
- Department of Neurosciences, University of Torino, Turin, Italy
| | - M Zibetti
- Department of Neuroscience and Mental Health, Città della Salute e della Scienza University Hospital, Turin, Italy
| | - A Tessa
- Molecular Medicine, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - M Barghigiani
- Molecular Medicine, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - A Antenora
- Department of Neurosciences, Federico II University, Naples, Italy
| | - F Sirchia
- Institute for Maternal and Child Health - IRCCS Burlo Garofolo, Trieste, Italy
| | - S Piacentini
- Department of Neuroscience, Psychology, Drug Research and Child's Health, University of Florence, Florence, Italy
| | - G Silvestri
- Fondazione Policlinico Universitario IRCCS, A. Gemelli, Rome, Italy.,Università Cattolica del Sacro Cuore, Rome, Italy
| | - G De Michele
- Department of Neurosciences, Federico II University, Naples, Italy
| | - A Filla
- Department of Neurosciences, Federico II University, Naples, Italy
| | - L Orsi
- Department of Neuroscience and Mental Health, Città della Salute e della Scienza University Hospital, Turin, Italy
| | - F M Santorelli
- Molecular Medicine, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - A Brusco
- Department of Medical Sciences, University of Torino, Turin, Italy.,Medical Genetics Unit, Città della Salute e della Scienza Hospital, Turin, Italy
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24
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Hamedani AG, Gold DR. Eyelid Dysfunction in Neurodegenerative, Neurogenetic, and Neurometabolic Disease. Front Neurol 2017; 8:329. [PMID: 28769865 PMCID: PMC5513921 DOI: 10.3389/fneur.2017.00329] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/23/2017] [Indexed: 12/18/2022] Open
Abstract
Eye movement abnormalities are among the earliest clinical manifestations of inherited and acquired neurodegenerative diseases and play an integral role in their diagnosis. Eyelid movement is neuroanatomically linked to eye movement, and thus eyelid dysfunction can also be a distinguishing feature of neurodegenerative disease and complements eye movement abnormalities in helping us to understand their pathophysiology. In this review, we summarize the various eyelid abnormalities that can occur in neurodegenerative, neurogenetic, and neurometabolic diseases. We discuss eyelid disorders, such as ptosis, eyelid retraction, abnormal spontaneous and reflexive blinking, blepharospasm, and eyelid apraxia in the context of the neuroanatomic pathways that are affected. We also review the literature regarding the prevalence of eyelid abnormalities in different neurologic diseases as well as treatment strategies (Table 1).
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Affiliation(s)
- Ali G Hamedani
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, United States
| | - Daniel R Gold
- Department of Neurology, Johns Hopkins Hospital, Baltimore, MD, United States.,Department of Ophthalmology, Johns Hopkins Hospital, Baltimore, MD, United States.,Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, MD, United States.,Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins Hospital, Baltimore, MD, United States
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25
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Viscomi C, Zeviani M. MtDNA-maintenance defects: syndromes and genes. J Inherit Metab Dis 2017; 40:587-599. [PMID: 28324239 PMCID: PMC5500664 DOI: 10.1007/s10545-017-0027-5] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 02/10/2017] [Accepted: 02/13/2017] [Indexed: 02/02/2023]
Abstract
A large group of mitochondrial disorders, ranging from early-onset pediatric encephalopathic syndromes to late-onset myopathy with chronic progressive external ophthalmoplegia (CPEOs), are inherited as Mendelian disorders characterized by disturbed mitochondrial DNA (mtDNA) maintenance. These errors of nuclear-mitochondrial intergenomic signaling may lead to mtDNA depletion, accumulation of mtDNA multiple deletions, or both, in critical tissues. The genes involved encode proteins belonging to at least three pathways: mtDNA replication and maintenance, nucleotide supply and balance, and mitochondrial dynamics and quality control. In most cases, allelic mutations in these genes may lead to profoundly different phenotypes associated with either mtDNA depletion or multiple deletions.
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Affiliation(s)
- Carlo Viscomi
- MRC-Mitochondrial Biology Unit, MRC MBU, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
| | - Massimo Zeviani
- MRC-Mitochondrial Biology Unit, MRC MBU, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK.
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26
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Giannoccaro MP, La Morgia C, Rizzo G, Carelli V. Mitochondrial DNA and primary mitochondrial dysfunction in Parkinson's disease. Mov Disord 2017; 32:346-363. [PMID: 28251677 DOI: 10.1002/mds.26966] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 01/27/2017] [Accepted: 01/30/2017] [Indexed: 12/15/2022] Open
Abstract
In 1979, it was observed that parkinsonism could be induced by a toxin inhibiting mitochondrial respiratory complex I. This initiated the long-standing hypothesis that mitochondrial dysfunction may play a key role in the pathogenesis of Parkinson's disease (PD). This hypothesis evolved, with accumulating evidence pointing to complex I dysfunction, which could be caused by environmental or genetic factors. Attention was focused on the mitochondrial DNA, considering the occurrence of mutations, polymorphic haplogroup-specific variants, and defective mitochondrial DNA maintenance with the accumulation of multiple deletions and a reduction of copy number. Genetically determined diseases of mitochondrial DNA maintenance frequently manifest with parkinsonism, but the age-related accumulation of somatic mitochondrial DNA errors also represents a major driving mechanism for PD. Recently, the discovery of the genetic cause of rare inherited forms of PD highlighted an extremely complex homeostatic control over mitochondria, involving their dynamic fission/fusion cycle, the balancing of mitobiogenesis and mitophagy, and consequently the quality control surveillance that corrects faulty mitochondrial DNA maintenance. Many genes came into play, including the PINK1/parkin axis, but also OPA1, as pieces of the same puzzle, together with mitochondrial DNA damage, complex I deficiency and increased oxidative stress. The search for answers will drive future research to reach the understanding necessary to provide therapeutic options directed not only at limiting the clinical evolution of symptoms but also finally addressing the pathogenic mechanisms of neurodegeneration in PD. © 2017 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Maria Pia Giannoccaro
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Chiara La Morgia
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Giovanni Rizzo
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
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27
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A neurodegenerative perspective on mitochondrial optic neuropathies. Acta Neuropathol 2016; 132:789-806. [PMID: 27696015 PMCID: PMC5106504 DOI: 10.1007/s00401-016-1625-2] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 09/24/2016] [Accepted: 09/25/2016] [Indexed: 12/15/2022]
Abstract
Mitochondrial optic neuropathies constitute an important cause of chronic visual morbidity and registrable blindness in both the paediatric and adult population. It is a genetically heterogeneous group of disorders caused by both mitochondrial DNA (mtDNA) mutations and a growing list of nuclear genetic defects that invariably affect a critical component of the mitochondrial machinery. The two classical paradigms are Leber hereditary optic neuropathy (LHON), which is a primary mtDNA disorder, and autosomal dominant optic atrophy (DOA) secondary to pathogenic mutations within the nuclear gene OPA1 that encodes for a mitochondrial inner membrane protein. The defining neuropathological feature is the preferential loss of retinal ganglion cells (RGCs) within the inner retina but, rather strikingly, the smaller calibre RGCs that constitute the papillomacular bundle are particularly vulnerable, whereas melanopsin-containing RGCs are relatively spared. Although the majority of patients with LHON and DOA will present with isolated optic nerve involvement, some individuals will also develop additional neurological complications pointing towards a greater vulnerability of the central nervous system (CNS) in susceptible mutation carriers. These so-called “plus” phenotypes are mechanistically important as they put the loss of RGCs within the broader perspective of neuronal loss and mitochondrial dysfunction, highlighting common pathways that could be modulated to halt progressive neurodegeneration in other related CNS disorders. The management of patients with mitochondrial optic neuropathies still remains largely supportive, but the development of effective disease-modifying treatments is now within tantalising reach helped by major advances in drug discovery and delivery, and targeted genetic manipulation.
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Abstract
Mitochondrial diseases are a group of genetic disorders that are characterized by defects in oxidative phosphorylation and caused by mutations in genes in the nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) that encode structural mitochondrial proteins or proteins involved in mitochondrial function. Mitochondrial diseases are the most common group of inherited metabolic disorders and are among the most common forms of inherited neurological disorders. One of the challenges of mitochondrial diseases is the marked clinical variation seen in patients, which can delay diagnosis. However, advances in next-generation sequencing techniques have substantially improved diagnosis, particularly in children. Establishing a genetic diagnosis allows patients with mitochondrial diseases to have reproductive options, but this is more challenging for women with pathogenetic mtDNA mutations that are strictly maternally inherited. Recent advances in in vitro fertilization techniques, including mitochondrial donation, will offer a better reproductive choice for these women in the future. The treatment of patients with mitochondrial diseases remains a challenge, but guidelines are available to manage the complications of disease. Moreover, an increasing number of therapeutic options are being considered, and with the development of large cohorts of patients and biomarkers, several clinical trials are in progress.
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29
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Abstract
Ten years ago, there was an emerging view that the molecular basis for adult mitochondrial disorders was largely known and that the clinical phenotypes had been well described. Nothing could have been further from the truth. The establishment of large cohorts of patients has revealed new aspects of the clinical presentation that were not previously appreciated. Over time, this approach is starting to provide an accurate understanding of the natural history of mitochondrial disease in adults. Advances in molecular diagnostics, underpinned by next generation sequencing technology, have identified novel molecular mechanisms. Recently described mitochondrial disease phenotypes have disparate causes, and yet share common mechanistic themes. In particular, disorders of mtDNA maintenance have emerged as a major cause of mitochondrial disease in adults. Progressive mtDNA depletion and the accumulation of mtDNA mutations explain some of the clinical features, but the genetic and cellular processes responsible for the mtDNA abnormalities are not entirely clear in each instance. Unfortunately, apart from a few specific examples, treatments for adult mitochondrial disease have not been forthcoming. However, the establishment of international consortia, and the first multinational randomised controlled trial, have paved the way for major progress in the near future, underpinned by growing interest from the pharmaceutical industry. Adult mitochondrial medicine is, therefore, in its infancy, and the challenge is to harness the new understanding of its molecular and cellular basis to develop treatments of real benefit to patients.
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Affiliation(s)
- Patrick F Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK Medical Research Council - Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge, UK
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30
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Mignarri A, Rubegni A, Tessa A, Stefanucci S, Malandrini A, Cardaioli E, Meschini MC, Stromillo ML, Doccini S, Federico A, Santorelli FM, Dotti MT. Mitochondrial dysfunction in hereditary spastic paraparesis with mutations in DDHD1/SPG28. J Neurol Sci 2016; 362:287-91. [PMID: 26944165 DOI: 10.1016/j.jns.2016.02.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 01/12/2016] [Accepted: 02/02/2016] [Indexed: 12/22/2022]
Abstract
Mutations in DDHD1 cause the SPG28 subtype of hereditary spastic paraplegia (HSP). Recent studies suggested that mitochondrial dysfunction occurs in SPG28. Here we describe two siblings with SPG28, and report evidence of mitochondrial impairment in skeletal muscle and skin fibroblasts. Patient 1 (Pt1) was a 35-year-old man with spastic paraparesis and urinary incontinence, while his 25-year-old brother (Pt2) had gait spasticity and motor axonal neuropathy. In these patients we identified the novel homozygous c.1429C>T/p.R477* mutation in DDHD1, using a next-generation sequencing (NGS) approach. Histochemical analyses in muscle showed mitochondrial alterations, and multiple mitochondrial DNA (mtDNA) deletions were evident. In Pt1, respiratory chain enzyme activities were altered in skeletal muscle, mitochondrial ATP levels reduced, and analysis of skin fibroblasts revealed mitochondrial fragmentation. It seems possible that the novel nonsense mutation identified abolishes DDHD1 protein function thus altering oxidative metabolism. Qualitative alterations of mtDNA could have a pathogenetic significance. We suggest to perform DDHD1 analysis in patients with multiple mtDNA deletions.
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Affiliation(s)
- Andrea Mignarri
- Unit of Neurology and Neurometabolic Disorders, Department of Medicine, Surgery and Neurosciences, University of Siena, Italy
| | - Anna Rubegni
- Unit of Molecular Medicine, IRCCS Stella Maris, Pisa, Italy
| | | | | | - Alessandro Malandrini
- Unit of Neurology and Neurometabolic Disorders, Department of Medicine, Surgery and Neurosciences, University of Siena, Italy
| | - Elena Cardaioli
- Unit of Neurology and Neurometabolic Disorders, Department of Medicine, Surgery and Neurosciences, University of Siena, Italy
| | | | - Maria Laura Stromillo
- Unit of Neurology and Neurometabolic Disorders, Department of Medicine, Surgery and Neurosciences, University of Siena, Italy
| | | | - Antonio Federico
- Unit of Neurology and Neurometabolic Disorders, Department of Medicine, Surgery and Neurosciences, University of Siena, Italy
| | | | - Maria Teresa Dotti
- Unit of Neurology and Neurometabolic Disorders, Department of Medicine, Surgery and Neurosciences, University of Siena, Italy
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31
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Lightowlers RN, Taylor RW, Turnbull DM. Mutations causing mitochondrial disease: What is new and what challenges remain? Science 2015; 349:1494-9. [PMID: 26404827 DOI: 10.1126/science.aac7516] [Citation(s) in RCA: 211] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mitochondrial diseases are among the most common and most complex of all inherited genetic diseases. The involvement of both the mitochondrial and nuclear genome presents unique challenges, but despite this there have been some remarkable advances in our knowledge of mitochondrial diseases over the past few years. A greater understanding of mitochondrial genetics has led to improved diagnosis as well as novel ways to prevent transmission of severe mitochondrial disease. These and other advances have had a major impact on patient care, but considerable challenges remain, particularly in the areas of therapies for those patients manifesting clinical symptoms associated with mitochondrial dysfunction and the tissue specificity seen in many mitochondrial disorders. This review highlights some important recent advances in mitochondrial disease but also stresses the areas where progress is essential.
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Affiliation(s)
- Robert N Lightowlers
- Wellcome Trust Centre for Mitochondrial Research, Institute for Cell and Molecular Biosciences and Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute for Cell and Molecular Biosciences and Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Institute for Cell and Molecular Biosciences and Institute of Neuroscience, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
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32
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Mayr JA, Haack TB, Freisinger P, Karall D, Makowski C, Koch J, Feichtinger RG, Zimmermann FA, Rolinski B, Ahting U, Meitinger T, Prokisch H, Sperl W. Spectrum of combined respiratory chain defects. J Inherit Metab Dis 2015; 38:629-40. [PMID: 25778941 PMCID: PMC4493854 DOI: 10.1007/s10545-015-9831-y] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 02/20/2015] [Accepted: 02/23/2015] [Indexed: 01/22/2023]
Abstract
Inherited disorders of mitochondrial energy metabolism form a large and heterogeneous group of metabolic diseases. More than 250 gene defects have been reported to date and this number continues to grow. Mitochondrial diseases can be grouped into (1) disorders of oxidative phosphorylation (OXPHOS) subunits and their assembly factors, (2) defects of mitochondrial DNA, RNA and protein synthesis, (3) defects in the substrate-generating upstream reactions of OXPHOS, (4) defects in relevant cofactors and (5) defects in mitochondrial homeostasis. Deficiency of more than one respiratory chain enzyme is a common finding. Combined defects are found in 49 % of the known disease-causing genes of mitochondrial energy metabolism and in 57 % of patients with OXPHOS defects identified in our diagnostic centre. Combined defects of complexes I, III, IV and V are typically due to deficiency of mitochondrial DNA replication, RNA metabolism or translation. Defects in cofactors can result in combined defects of various combinations, and defects of mitochondrial homeostasis can result in a generalised decrease of all OXPHOS enzymes. Noteworthy, identification of combined defects can be complicated by different degrees of severity of each affected enzyme. Furthermore, even defects of single respiratory chain enzymes can result in combined defects due to aberrant formation of respiratory chain supercomplexes. Combined OXPHOS defects have a great variety of clinical manifestations in terms of onset, course severity and tissue involvement. They can present as classical encephalomyopathy but also with hepatopathy, nephropathy, haematologic findings and Perrault syndrome in a subset of disorders.
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Affiliation(s)
- Johannes A Mayr
- Department of Paediatrics, Paracelsus Medical University, SALK Salzburg, Salzburg, 5020, Austria,
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33
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Gorman GS, Schaefer AM, Ng Y, Gomez N, Blakely EL, Alston CL, Feeney C, Horvath R, Yu-Wai-Man P, Chinnery PF, Taylor RW, Turnbull DM, McFarland R. Prevalence of nuclear and mitochondrial DNA mutations related to adult mitochondrial disease. Ann Neurol 2015; 77:753-9. [PMID: 25652200 PMCID: PMC4737121 DOI: 10.1002/ana.24362] [Citation(s) in RCA: 586] [Impact Index Per Article: 65.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 11/30/2014] [Accepted: 01/08/2015] [Indexed: 01/17/2023]
Abstract
OBJECTIVE The prevalence of mitochondrial disease has proven difficult to establish, predominantly as a result of clinical and genetic heterogeneity. The phenotypic spectrum of mitochondrial disease has expanded significantly since the original reports that associated classic clinical syndromes with mitochondrial DNA (mtDNA) rearrangements and point mutations. The revolution in genetic technologies has allowed interrogation of the nuclear genome in a manner that has dramatically improved the diagnosis of mitochondrial disorders. We comprehensively assessed the prevalence of all forms of adult mitochondrial disease to include pathogenic mutations in both nuclear and mtDNA. METHODS Adults with suspected mitochondrial disease in the North East of England were referred to a single neurology center from 1990 to 2014. For the midyear period of 2011, we evaluated the minimum prevalence of symptomatic nuclear DNA mutations and symptomatic and asymptomatic mtDNA mutations causing mitochondrial diseases. RESULTS The minimum prevalence rate for mtDNA mutations was 1 in 5,000 (20 per 100,000), comparable with our previously published prevalence rates. In this population, nuclear mutations were responsible for clinically overt adult mitochondrial disease in 2.9 per 100,000 adults. INTERPRETATION Combined, our data confirm that the total prevalence of adult mitochondrial disease, including pathogenic mutations of both the mitochondrial and nuclear genomes (≈1 in 4,300), is among the commonest adult forms of inherited neurological disorders. These figures hold important implications for the evaluation of interventions, provision of evidence-based health policies, and planning of future services.
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Affiliation(s)
- Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; Institute of Neuroscience, Henry Wellcome Building for Neuroecology, Newcastle upon Tyne, United Kingdom
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