1
|
Gayathri N, Deepha S, Sharma S. Diagnosis of primary mitochondrial disorders -Emphasis on myopathological aspects. Mitochondrion 2021; 61:69-84. [PMID: 34592422 DOI: 10.1016/j.mito.2021.09.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/03/2021] [Accepted: 09/22/2021] [Indexed: 12/29/2022]
Abstract
Mitochondrial disorders are one of the most common neurometabolic disorders affecting all age groups. The phenotype-genotype heterogeneity in these disorders can be attributed to the dual genetic control on mitochondrial functions, posing a challenge for diagnosis. Though the advancement in the high-throughput sequencing and other omics platforms resulted in a "genetics-first" approach, the muscle biopsy remains the benchmark in most of the mitochondrial disorders. This review focuses on the myopathological aspects of primary mitochondrial disorders. The utility of muscle biopsy is not limited to analyse the structural abnormalities; rather it also proves to be a potential tool to understand the deranged sub-cellular functions.
Collapse
Affiliation(s)
- Narayanappa Gayathri
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore 560 029, India.
| | - Sekar Deepha
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore 560 029, India
| | - Shivani Sharma
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore 560 029, India
| |
Collapse
|
2
|
Lu JQ, Tarnopolsky MA. Mitochondrial neuropathy and neurogenic features in mitochondrial myopathy. Mitochondrion 2020; 56:52-61. [PMID: 33220502 DOI: 10.1016/j.mito.2020.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/25/2020] [Accepted: 11/02/2020] [Indexed: 01/21/2023]
Abstract
Mitochondrial diseases (MIDs) involve multiple organs including peripheral nerves and skeletal muscle. Mitochondrial neuropathy (MN) and mitochondrial myopathy (MM) are commonly associated and linked at the neuromuscular junction (NMJ). Herein we review MN in connection with neurogenic features of MM, and pathological evidence for the involvement of the peripheral nerve and NMJ in MID patients traditionally assumed to have predominantly MM. MN is not uncommon, but still likely under-reported, and muscle biopsies of MM commonly exhibit neurogenic features. Pathological examination remains the gold standard to assess the nerve and muscle changes in patients with MIDs. Ultrastructural studies by electron microscopy are often necessary to fully characterize the pathology of mitochondrial cytopathy in MN and MM.
Collapse
Affiliation(s)
- Jian-Qiang Lu
- Department of Pathology and Molecular Medicine/Neuropathology, McMaster University, Hamilton, Ontario, Canada.
| | - Mark A Tarnopolsky
- Department of Medicine/Neurology, McMaster University, Hamilton, Ontario, Canada; Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| |
Collapse
|
3
|
Kerr M, Hume S, Omar F, Koo D, Barnes H, Khan M, Aman S, Wei XC, Alfuhaid H, McDonald R, McDonald L, Newell C, Sparkes R, Hittel D, Khan A. MITO-FIND: A study in 390 patients to determine a diagnostic strategy for mitochondrial disease. Mol Genet Metab 2020; 131:66-82. [PMID: 32980267 DOI: 10.1016/j.ymgme.2020.08.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/29/2020] [Accepted: 08/30/2020] [Indexed: 12/14/2022]
Abstract
Mitochondrial diseases, due to nuclear or mitochondrial genome mutations causing mitochondrial dysfunction, have a wide range of clinical features involving neurologic, muscular, cardiac, hepatic, visual, and auditory symptoms. Making a diagnosis of a mitochondrial disease is often challenging since there is no gold standard and traditional testing methods have required tissue biopsy which presents technical challenges and most patients prefer a non-invasive approach. Since a diagnosis invariably involves finding a disease-causing DNA variant, new approaches such as next generation sequencing (NGS) have the potential to make it easier to make a diagnosis. We evaluated the ability of our traditional diagnostic pathway (metabolite analysis, tissue neuropathology and respiratory chain enzyme activity) in 390 patients. The traditional diagnostic pathway provided a diagnosis of mitochondrial disease in 115 patients (29.50%). Analysis of mtDNA, tissue neuropathology, skin electron microscopy, respiratory chain enzyme analysis using inhibitor assays, blue native polyacrylamide gel electrophoresis were all statistically significant in distinguishing patients between a mitochondrial and non-mitochondrial diagnosis. From these 390 patients who underwent traditional analysis, we recruited 116 patients for the NGS part of the study (36 patients who had a mitochondrial diagnosis (MITO) and 80 patients who had no diagnosis (No-Dx)). In the group of 36 MITO patients, nuclear whole exome sequencing (nWES) provided a second diagnosis in 2 cases who already had a pathogenic variant in mtDNA, and a revised diagnosis (GLUL) in one case that had abnormal pathology but no pathogenic mtDNA variant. In the 80 NO-Dx patients, nWES found non-mitochondrial diagnosis in 26 patients and a mitochondrial diagnosis in 1 patient. A genetic diagnosis was obtained in 53/116 (45.70%) cases that were recruited for NGS, but not in 11/116 (9.48%) of cases with abnormal mitochondrial neuropathology. Our results show that a non-invasive, bigenomic sequencing (BGS) approach (using both a nWES and optimized mtDNA analysis to include large deletions) should be the first step in investigating for mitochondrial diseases. There may still be a role for tissue biopsy in unsolved cases or when the diagnosis is still not clear after NGS studies.
Collapse
Affiliation(s)
- Marina Kerr
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Stacey Hume
- Department of Medical Genetics, University of Alberta, Edmonton, Canada
| | - Fadya Omar
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Desmond Koo
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Heather Barnes
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Maida Khan
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Suhaib Aman
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Xing-Chang Wei
- Department of Radiology, Alberta Children's Hospital, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada
| | - Hanen Alfuhaid
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Roman McDonald
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Liam McDonald
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Christopher Newell
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Rebecca Sparkes
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Dustin Hittel
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Aneal Khan
- Departments of Medical Genetics and Pediatrics, University of Calgary Cumming School of Medicine, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada.
| |
Collapse
|
4
|
Lu JQ, Monaco CMF, Hawke TJ, Yan C, Tarnopolsky MA. Increased intra-mitochondrial lipofuscin aggregates with spherical dense body formation in mitochondrial myopathy. J Neurol Sci 2020; 413:116816. [PMID: 32272361 DOI: 10.1016/j.jns.2020.116816] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/27/2020] [Accepted: 03/31/2020] [Indexed: 12/28/2022]
Abstract
Lipofuscin aggregation may result from incomplete degradation of damaged mitochondria by autophagy-lysosome pathway, and intra-mitochondrial lipofuscin aggregation may exacerbate mitochondrial abnormalities in mitochondrial myopathy (MM) and mitochondrial disease. We examined vastus lateralis muscle biopsies from 24 patients with pathologically diagnosed MM and clinically diagnosed chronic progressive external ophthalmoplegia, in comparison to the biopsies from 3 other groups:10 patients with inclusion body myositis (IBM), 11 younger adults, and 10 older subjects with no to minimal myopathic changes. Lipofuscin aggregation in muscle fibres was assessed on autofluorescence microscopy, some histochemical stains, and electron microscopy (EM). EM analyses demonstrated intra-mitochondrial lipofuscin aggregates, spherical dense bodies (SDBs), and paracrystalline inclusions (PCIs) which were semi-quantitatively assessed. Intra-mitochondrial lipofuscin aggregates showed no significant differences between groups of MM patients and older subjects or IBM patients, but significant differences between groups of younger adults and others with associated age-related changes. Intra-mitochondrial SDBs were significantly more in MM patients than in older subjects, IBM patients, and younger adults. There was a significant positive correlation between intra-mitochondrial lipofuscin aggregates and SDBs. These findings suggest that intra-mitochondrial formation of lipofuscin SDBs is more in MM and contributing to the pathophysiology of mitochondrial disease.
Collapse
Affiliation(s)
- Jian-Qiang Lu
- Department of Pathology and Molecular Medicine/Neuropathology, McMaster University, Hamilton, Ontario, Canada.
| | - Cynthia M F Monaco
- Department of Pathology and Molecular Medicine/Anatomy, McMaster University, Hamilton, Ontario, Canada
| | - Thomas J Hawke
- Department of Pathology and Molecular Medicine/Anatomy, McMaster University, Hamilton, Ontario, Canada
| | - Chuanzhu Yan
- Neuromuscular Center, Qilu Hospital, Shandong University, Shandong, China; Mitochondrial Medicine Laboratory, Qilu Hospital, Shandong University, Shandong, China
| | - Mark A Tarnopolsky
- Department of Medicine/Neurology, McMaster University, Hamilton, Ontario, Canada; Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
| |
Collapse
|
5
|
Sabouny R, Wong R, Lee-Glover L, Greenway SC, Sinasac DS, Khan A, Shutt TE. Characterization of the C584R variant in the mtDNA depletion syndrome gene FBXL4, reveals a novel role for FBXL4 as a regulator of mitochondrial fusion. Biochim Biophys Acta Mol Basis Dis 2019; 1865:165536. [PMID: 31442532 DOI: 10.1016/j.bbadis.2019.165536] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 07/16/2019] [Accepted: 08/18/2019] [Indexed: 12/16/2022]
Abstract
Mutations in FBXL4 (F-Box and Leucine rich repeat protein 4), a nuclear-encoded mitochondrial protein with an unknown function, cause mitochondrial DNA depletion syndrome. We report two siblings, from consanguineous parents, harbouring a previously uncharacterized homozygous variant in FBXL4 (c.1750 T > C; p.Cys584Arg). Both patients presented with encephalomyopathy, lactic acidosis and cardiac hypertrophy, which are reported features of FBXL4 impairment. Remarkably, dichloroacetate (DCA) administration to the younger sibling improved metabolic acidosis and reversed cardiac hypertrophy. Characterization of FBXL4 patient fibroblasts revealed severe bioenergetic defects, mtDNA depletion, fragmentation of mitochondrial networks, and abnormalities in mtDNA nucleoids. These phenotypes, observed with other pathogenic FBXL4 variants, confirm the pathogenicity of the p.Cys584Arg variant. Although treating FBXL4 fibroblasts with DCA improved extracellular acidification, in line with reduced lactate levels in patients, DCA treatment did not improve any of the other mitochondrial functions. Nonetheless, we highlight DCA as a potentially effective drug for the management of elevated lactate and cardiomyopathy in patients with pathogenic FBXL4 variants. Finally, as the exact mechanism through which FBXL4 mutations lead to mtDNA depletion was unknown, we tested the hypothesis that FBXL4 promotes mitochondrial fusion. Using a photo-activatable GFP fusion assay, we found reduced mitochondrial fusion rates in cells harbouring a pathogenic FBXL4 variant. Meanwhile, overexpression of wildtype FBXL4, but not the p.Cys584Arg variant, promoted mitochondrial hyperfusion. Thus, we have uncovered a novel function for FBXL4 in promoting mitochondrial fusion, providing important mechanistic insights into the pathogenic mechanism underlying FBXL4 dysfunction.
Collapse
Affiliation(s)
- Rasha Sabouny
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.
| | - Rachel Wong
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Laurie Lee-Glover
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Steven C Greenway
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada; Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - David S Sinasac
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | | | - Aneal Khan
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Timothy E Shutt
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
| |
Collapse
|
6
|
Abstract
RATIONALE Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) are thought to be rarely accompanied by macroangiopathy. We reported a case of MELAS that presented right distal internal carotid arterial (ICA) stenosis and reviewed 12 similar previously reported cases involving intracranial large blood vessels. PATIENT CONCERNS A 38-year-old man suffered from recurrent stroke-like episodes (SE) such as alternating hemiparesis (right lesion 3 years ago and current left lesion), cortical blindness and seizure for 3 years, and was previously misdiagnosed as cerebral infarction. Magnetic Resonance Angiography (MRA) and Digital Subtraction Angiography (DSA) revealed right distal ICA stenosis and sparse cortex blood vessels, which were related to the previous SE. DIAGNOSES He was diagnosed by genetic screening (a mitochondrial DNA A3243G point mutation) and presence of high lactic acidosis (4.03 mmol/L), which rose to 7.8 mmol/L after exercise. INTERVENTION The patient received Coenzyme Q10, vitamin C, L-arginine for 2 weeks and valproic acid sodium (400 mg bid) to prevent seizures till now. OUTCOMES He is currently less active and intelligent than his peers, with occasional seizures, and needs family care. LESSONS Till date, there are 12 reported cases of MELAS combined with major cerebral arteries abnormalities including stenosis, dissection, occlusion, reversible vasoconstriction, aneurysms, and atherosclerosis. Hence, macroangiopathy in MELAS is not very rare. There is correlation between the affected vessels and the lesions in some cases, but not in others, which may increase the misdiagnosis rate. Hence, mitochondrial diseases cannot be excluded due to concurrent macroangiopathic lesions.
Collapse
|
7
|
Zorova LD, Popkov VA, Plotnikov EY, Silachev DN, Pevzner IB, Jankauskas SS, Babenko VA, Zorov SD, Balakireva AV, Juhaszova M, Sollott SJ, Zorov DB. Mitochondrial membrane potential. Anal Biochem 2018; 552:50-59. [PMID: 28711444 PMCID: PMC5792320 DOI: 10.1016/j.ab.2017.07.009] [Citation(s) in RCA: 1073] [Impact Index Per Article: 178.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/06/2017] [Accepted: 07/07/2017] [Indexed: 01/13/2023]
Abstract
The mitochondrial membrane potential (ΔΨm) generated by proton pumps (Complexes I, III and IV) is an essential component in the process of energy storage during oxidative phosphorylation. Together with the proton gradient (ΔpH), ΔΨm forms the transmembrane potential of hydrogen ions which is harnessed to make ATP. The levels of ΔΨm and ATP in the cell are kept relatively stable although there are limited fluctuations of both these factors that can occur reflecting normal physiological activity. However, sustained changes in both factors may be deleterious. A long-lasting drop or rise of ΔΨm vs normal levels may induce unwanted loss of cell viability and be a cause of various pathologies. Among other factors, ΔΨm plays a key role in mitochondrial homeostasis through selective elimination of dysfunctional mitochondria. It is also a driving force for transport of ions (other than H+) and proteins which are necessary for healthy mitochondrial functioning. We propose additional potential mechanisms for which ΔΨm is essential for maintenance of cellular health and viability and provide recommendations how to accurately measure ΔΨm in a cell and discuss potential sources of artifacts.
Collapse
Affiliation(s)
- Ljubava D Zorova
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; International Laser Center, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Vasily A Popkov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Egor Y Plotnikov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Denis N Silachev
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Irina B Pevzner
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Stanislovas S Jankauskas
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Valentina A Babenko
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Savva D Zorov
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Anastasia V Balakireva
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russian Federation
| | - Magdalena Juhaszova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Dmitry B Zorov
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation; Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
| |
Collapse
|
8
|
Reversible Dilation of Cerebral Macrovascular Changes in MELAS Episodes. Clin Neuroradiol 2018; 29:321-329. [DOI: 10.1007/s00062-018-0662-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 01/02/2018] [Indexed: 01/12/2023]
|
9
|
Himori N, Kunikata H, Inoue M, Takeshita T, Nishiguchi KM, Nakazawa T. Optic nerve head microcirculation in autosomal dominant optic atrophy and normal-tension glaucoma. Acta Ophthalmol 2017; 95:e799-e800. [PMID: 28134500 DOI: 10.1111/aos.13353] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Noriko Himori
- Department of Ophthalmology; Tohoku University Graduate School of Medicine; Sendai Japan
| | - Hiroshi Kunikata
- Department of Ophthalmology; Tohoku University Graduate School of Medicine; Sendai Japan
- Department of Retinal Disease Control; Tohoku University Graduate School of Medicine; Sendai Japan
| | - Maki Inoue
- Department of Ophthalmology; Tohoku University Graduate School of Medicine; Sendai Japan
| | - Takayuki Takeshita
- Department of Ophthalmology; Tohoku University Graduate School of Medicine; Sendai Japan
| | - Koji M. Nishiguchi
- Department of Ophthalmology; Tohoku University Graduate School of Medicine; Sendai Japan
- Department of Advanced Ophthalmic Medicine; Tohoku University Graduate School of Medicine; Sendai Japan
| | - Toru Nakazawa
- Department of Ophthalmology; Tohoku University Graduate School of Medicine; Sendai Japan
- Department of Retinal Disease Control; Tohoku University Graduate School of Medicine; Sendai Japan
- Department of Advanced Ophthalmic Medicine; Tohoku University Graduate School of Medicine; Sendai Japan
- Department of Ophthalmic Imaging and Information Analytics; Tohoku University Graduate School of Medicine; Sendai Japan
| |
Collapse
|
10
|
Phadke R. Myopathology of Adult and Paediatric Mitochondrial Diseases. J Clin Med 2017; 6:jcm6070064. [PMID: 28677615 PMCID: PMC5532572 DOI: 10.3390/jcm6070064] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 06/21/2017] [Accepted: 06/28/2017] [Indexed: 01/09/2023] Open
Abstract
Mitochondria are dynamic organelles ubiquitously present in nucleated eukaryotic cells, subserving multiple metabolic functions, including cellular ATP generation by oxidative phosphorylation (OXPHOS). The OXPHOS machinery comprises five transmembrane respiratory chain enzyme complexes (RC). Defective OXPHOS gives rise to mitochondrial diseases (mtD). The incredible phenotypic and genetic diversity of mtD can be attributed at least in part to the RC dual genetic control (nuclear DNA (nDNA) and mitochondrial DNA (mtDNA)) and the complex interaction between the two genomes. Despite the increasing use of next-generation-sequencing (NGS) and various omics platforms in unravelling novel mtD genes and pathomechanisms, current clinical practice for investigating mtD essentially involves a multipronged approach including clinical assessment, metabolic screening, imaging, pathological, biochemical and functional testing to guide molecular genetic analysis. This review addresses the broad muscle pathology landscape including genotype–phenotype correlations in adult and paediatric mtD, the role of immunodiagnostics in understanding some of the pathomechanisms underpinning the canonical features of mtD, and recent diagnostic advances in the field.
Collapse
Affiliation(s)
- Rahul Phadke
- Division of Neuropathology, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, London WC1N 3BG, UK.
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
| |
Collapse
|
11
|
Abstract
BACKGROUND the maternally inherited MTTL1 A3243G mutation in the mitochondrial genome causes MelaS (Mitochondrial encephalopathy lactic acidosis with Stroke-like episodes), a condition that is multisystemic but affects primarily the nervous system. Significant intra-familial variation in phenotype and severity of disease is well recognized. METHODS retrospective and ongoing study of an extended family carrying the MTTL1 A3243G mutation with multiple symptomatic individuals. tissue heteroplasmy is reviewed based on the clinical presentations, imaging studies, laboratory findings in affected individuals and pathological material obtained at autopsy in two of the family members. RESULTS there were seven affected individuals out of thirteen members in this three generation family who each carried the MTTL1 A3243G mutation. the clinical presentations were varied with symptoms ranging from hearing loss, migraines, dementia, seizures, diabetes, visual manifestations, and stroke like episodes. three of the family members are deceased from MelaS or to complications related to MelaS. CONCLUSIONS the results of the clinical, pathological and radiological findings in this family provide strong support to the current concepts of maternal inheritance, tissue heteroplasmy and molecular pathogenesis in MelaS. neurologists (both adult and paediatric) are the most likely to encounter patients with MelaS in their practice. genetic counselling is complex in view of maternal inheritance and heteroplasmy. newer therapeutic options such as arginine are being used for acute and preventative management of stroke like episodes.
Collapse
|
12
|
Ryan TE, Schmidt CA, Green TD, Brown DA, Neufer PD, McClung JM. Mitochondrial Regulation of the Muscle Microenvironment in Critical Limb Ischemia. Front Physiol 2015; 6:336. [PMID: 26635622 PMCID: PMC4649016 DOI: 10.3389/fphys.2015.00336] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/02/2015] [Indexed: 01/11/2023] Open
Abstract
Critical limb ischemia (CLI) is the most severe clinical presentation of peripheral arterial disease and manifests as chronic limb pain at rest and/or tissue necrosis. Current clinical interventions are largely ineffective and therapeutic angiogenesis based trials have shown little efficacy, highlighting the dire need for new ideas and novel therapeutic approaches. Despite a decade of research related to skeletal muscle as a determinant of morbidity and mortality outcomes in CLI, very little progress has been made toward an effective therapy aimed directly at the muscle myopathies of this disease. Within the muscle cell, mitochondria are well positioned to modulate the ischemic cellular response, as they are the principal sites of cellular energy production and the major regulators of cellular redox charge and cell death. In this mini review, we update the crucial importance of skeletal muscle to CLI pathology and examine the evolving influence of muscle and endothelial cell mitochondria in the complex ischemic microenvironment. Finally, we discuss the novelty of muscle mitochondria as a therapeutic target for ischemic pathology in the context of the complex co-morbidities often associated with CLI.
Collapse
Affiliation(s)
- Terence E Ryan
- Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA ; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University Greenville, NC, USA
| | - Cameron A Schmidt
- Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA ; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University Greenville, NC, USA
| | - Tom D Green
- Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA ; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University Greenville, NC, USA
| | - David A Brown
- Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA ; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University Greenville, NC, USA
| | - P Darrell Neufer
- Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA ; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University Greenville, NC, USA
| | - Joseph M McClung
- Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA ; East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University Greenville, NC, USA
| |
Collapse
|
13
|
Zorov DB, Plotnikov EY, Silachev DN, Zorova LD, Pevzner IB, Zorov SD, Babenko VA, Jankauskas SS, Popkov VA, Savina PS. Microbiota and mitobiota. Putting an equal sign between mitochondria and bacteria. BIOCHEMISTRY (MOSCOW) 2015; 79:1017-31. [PMID: 25519061 DOI: 10.1134/s0006297914100046] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The recent revival of old theories and setting them on modern scientific rails to a large extent are also relevant to mitochondrial science. Given the widespread belief that mitochondria are symbionts of ancient bacterial origin, the processes inherent to mitochondrial physiology can be revised based on their comparative analysis with possible involvement of bacteria. Such comparison combined with discussion of the role of microbiota in pathogenesis allows discussion of the role of "mitobiota" (we introduce this term) as the combination of different phenotypic manifestations of mitochondria in the organism reflecting pathological changes in the mitochondrial genome. When putting an equal sign between mitochondria and bacteria, we find similarity between the mitochondrial and bacterial theories of cancer. The presence of the term "bacterial infection" suggests "mitochondrial infection", and mitochondrial (oxidative) theory of aging can in some way be transformed into a "bacterial theory of aging". The possible existence of such processes and the data confirming their presence are discussed in this review. If such a comparison has the right to exist, the homeostasis of "mitobiota" is of not lesser physiological importance than homeostasis of microbiota, which has been so intensively discussed recently.
Collapse
Affiliation(s)
- D B Zorov
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, 119991, Russia.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Skeletal muscle microvasculature in the diagnosis of neuromuscular disease. J Neuropathol Exp Neurol 2013; 72:906-18. [PMID: 24042201 DOI: 10.1097/nen.0b013e3182a7f0b8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Blood vessels are often overlooked in analyses of skeletal muscle biopsies. However, there are many vascular features in skeletal muscle biopsies that, when interpreted in the context of other histologic patterns and clinical history, provide useful information that allows muscle pathologists to narrow their differential diagnoses and provide more accurate guidance to treating physicians. Here, we provide a review of normal skeletal muscle vasculature with details of the ultrastructure of vessel walls. We discuss the vascular effects of factors common to many patients undergoing muscle biopsy, for example, diabetes mellitus, hypertension, and aging. We then discuss vascular findings relevant to diagnostic muscle biopsy evaluation, with current theories of pathogenesis and detailed descriptions of the important features.
Collapse
|
15
|
Adeva M, González-Lucán M, Seco M, Donapetry C. Enzymes involved in l-lactate metabolism in humans. Mitochondrion 2013; 13:615-29. [DOI: 10.1016/j.mito.2013.08.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 07/29/2013] [Accepted: 08/30/2013] [Indexed: 12/20/2022]
|
16
|
Abstract
BACKGROUND Repetitively discharging neurons in epileptic foci have a high energy requirement that might be demonstrated histochemically as increased mitochondrial enzymatic activity in brain resections for epilepsy in children. MATERIALS AND METHODS Frozen sections were studied histochemically of 10 brain resections from 7 epileptic children, 2 months to 17 years of age. None had mitochondrial disease. Three patients had tuberous sclerosis (TS) or hemimegalencephy (HME). Tissues included hippocampus and neocortex. Oxidative enzymes were studied for respiratory chain complexes I, II, IV, using the muscle biopsy protocol. In addition, immunoreactivities of α-B-crystallin and transmission electron microscopy (EM) were performed. RESULTS Oxidative activities were variable in adjacent neurons within a field: a minority were intense, adjacent to neurons with weaker mitochondrial activity exhibiting poor contrast of the soma because of similar oxidative activity in surrounding neuropil. Endothelium of vessels uniformly exhibits strong activity. Alpha-B-crystallin reactivity was strong at these foci. EM confirmed an abundance of neuronal mitochondria with normal cristae. In TS and HME, many dysplastic neurons showed intense activity; balloon cells had sparse activity. CONCLUSIONS Histochemistry of mitochondrial oxidative enzymes reveals scattered and clustered neurons with stronger activities than others at epileptic foci. Such intensely staining neurons may be functionally "hypermetabolic" but they do not signify mitochondrial disease. Individual intensely stained neurons might be epileptogenic, but do not denote an epileptogenic field in the same manner as α-B-crystallin, which also was strongly reactive in these foci.
Collapse
|