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Caon E, Martins M, Hodgetts H, Blanken L, Vilia MG, Levi A, Thanapirom K, Al-Akkad W, Abu-Hanna J, Baselli G, Hall AR, Luong TV, Taanman JW, Vacca M, Valenti L, Romeo S, Mazza G, Pinzani M, Rombouts K. Exploring the impact of the PNPLA3 I148M variant on primary human hepatic stellate cells using 3D extracellular matrix models. J Hepatol 2024:S0168-8278(24)00110-7. [PMID: 38365182 DOI: 10.1016/j.jhep.2024.01.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 01/24/2024] [Accepted: 01/27/2024] [Indexed: 02/18/2024]
Abstract
BACKGROUND & AIMS The PNPLA3 rs738409 C>G (encoding for I148M) variant is a risk locus for the fibrogenic progression of chronic liver diseases, a process driven by hepatic stellate cells (HSCs). We investigated how the PNPLA3 I148M variant affects HSC biology using transcriptomic data and validated findings in 3D-culture models. METHODS RNA sequencing was performed on 2D-cultured primary human HSCs and liver biopsies of individuals with obesity, genotyped for the PNPLA3 I148M variant. Data were validated in wild-type (WT) or PNPLA3 I148M variant-carrying HSCs cultured on 3D extracellular matrix (ECM) scaffolds from human healthy and cirrhotic livers, with/without TGFB1 or cytosporone B (Csn-B) treatment. RESULTS Transcriptomic analyses of liver biopsies and HSCs highlighted shared PNPLA3 I148M-driven dysregulated pathways related to mitochondrial function, antioxidant response, ECM remodelling and TGFB1 signalling. Analogous pathways were dysregulated in WT/PNPLA3-I148M HSCs cultured in 3D liver scaffolds. Mitochondrial dysfunction in PNPLA3-I148M cells was linked to respiratory chain complex IV insufficiency. Antioxidant capacity was lower in PNPLA3-I148M HSCs, while reactive oxygen species secretion was increased in PNPLA3-I148M HSCs and higher in bioengineered cirrhotic vs. healthy scaffolds. TGFB1 signalling followed the same trend. In PNPLA3-I148M cells, expression and activation of the endogenous TGFB1 inhibitor NR4A1 were decreased: treatment with the Csn-B agonist increased total NR4A1 in HSCs cultured in healthy but not in cirrhotic 3D scaffolds. NR4A1 regulation by TGFB1/Csn-B was linked to Akt signalling in PNPLA3-WT HSCs and to Erk signalling in PNPLA3-I148M HSCs. CONCLUSION HSCs carrying the PNPLA3 I148M variant have impaired mitochondrial function, antioxidant responses, and increased TGFB1 signalling, which dampens antifibrotic NR4A1 activity. These features are exacerbated by cirrhotic ECM, highlighting the dual impact of the PNPLA3 I148M variant and the fibrotic microenvironment in progressive chronic liver diseases. IMPACT AND IMPLICATIONS Hepatic stellate cells (HSCs) play a key role in the fibrogenic process associated with chronic liver disease. The PNPLA3 genetic mutation has been linked with increased risk of fibrogenesis, but its role in HSCs requires further investigation. Here, by using comparative transcriptomics and a novel 3D in vitro model, we demonstrate the impact of the PNPLA3 genetic mutation on primary human HSCs' behaviour, and we show that it affects the cell's mitochondrial function and antioxidant response, as well as the antifibrotic gene NR4A1. Our publicly available transcriptomic data, 3D platform and our findings on NR4A1 could facilitate the discovery of targets to develop more effective treatments for chronic liver diseases.
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Affiliation(s)
- Elisabetta Caon
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
| | - Maria Martins
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
| | - Harry Hodgetts
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
| | - Lieke Blanken
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
| | - Maria Giovanna Vilia
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
| | - Ana Levi
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
| | - Kessarin Thanapirom
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
| | - Walid Al-Akkad
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
| | - Jeries Abu-Hanna
- Research Department of Surgical Biotechnology, Division of Surgery and Interventional Science, University College London, London, UK
| | - Guido Baselli
- Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy
| | - Andrew R Hall
- Sheila Sherlock Liver Centre, Royal Free London NHS Foundation Trust, London, UK; Department of Cellular Pathology, Royal Free London NHS Foundation Trust, London, UK
| | - Tu Vinh Luong
- Sheila Sherlock Liver Centre, Royal Free London NHS Foundation Trust, London, UK; Department of Cellular Pathology, Royal Free London NHS Foundation Trust, London, UK
| | - Jan-Willem Taanman
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, London UK
| | - Michele Vacca
- Laboratory of Hepatic Metabolism and NAFLD, Roger Williams Institute of Hepatology, London, UK; Clinica Medica "Frugoni", Interdisciplinary Department of Medicine, University of Bari "Aldo Moro", Bari, Italy
| | - Luca Valenti
- Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy; Precision Medicine, Biological Resource Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Stefano Romeo
- Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden
| | - Giuseppe Mazza
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
| | - Massimo Pinzani
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK
| | - Krista Rombouts
- Regenerative Medicine and Fibrosis Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, UK.
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Neueder A, Kojer K, Gu Z, Wang Y, Hering T, Tabrizi S, Taanman JW, Orth M. Huntington disease affects mitochondrial network dynamics predisposing to pathogenic mtDNA mutations. Brain 2024:awae007. [PMID: 38195181 DOI: 10.1093/brain/awae007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 09/27/2023] [Accepted: 12/11/2023] [Indexed: 01/11/2024] Open
Abstract
Huntington disease (HD) predominantly affects the brain causing a mixed movement disorder, cognitive decline and behavioural abnormalities. It also causes a peripheral phenotype involving skeletal muscle. Mitochondrial dysfunction has been reported in tissues of HD models, including skeletal muscle, and lymphoblasts and fibroblasts cultures from HD patients. Mutant huntingtin protein (mutHTT) expression can impair mitochondrial quality control and accelerate mitochondrial ageing. Here we obtained fresh human skeletal muscle, a post-mitotic tissue expressing the mutated HTT allele at physiological levels since birth, and primary cell lines from HTT CAG repeat expansion mutation carriers and matched healthy volunteers to examine whether such a mitochondrial phenotype exists in human HD. Using ultra-deep mitochondrial DNA (mtDNA) sequencing, we show an accumulation of mtDNA mutations affecting oxidative phosphorylation. Tissue proteomics indicate impairments in mtDNA maintenance with increased mitochondrial biogenesis of less efficient oxidative phosphorylation (lower complex I and IV activity). In full-length mutHTT expressing primary human cell lines, fission inducing mitochondrial stress resulted in normal mitophagy. In contrast, expression of high levels of N-terminal mutHTT fragments promoted mitochondrial fission and resulted in slower, less dynamic mitophagy. Expression of high levels of mutHTT fragments due to somatic nuclear HTT CAG instability can thus affect mitochondrial network dynamics and mitophagy leading to pathogenic mtDNA mutations. We show that life-long expression of mutant HTT causes a mitochondrial phenotype indicative of mtDNA instability in fresh post-mitotic human skeletal muscle. Thus, genomic instability may not be limited to nuclear DNA where it results in somatic expansion of HTT CAG repeat length in particularly vulnerable cells, such as striatal neurons. In addition to efforts targeting the causative mutation promoting mitochondrial health may be a complementary strategy in treating diseases with DNA instability, such as HD.
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Affiliation(s)
| | - Kerstin Kojer
- Department of Neurology, Ulm University, Ulm, Germany
| | - Zhenglong Gu
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Yiqin Wang
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Tanja Hering
- Department of Neurology, Ulm University, Ulm, Germany
| | - Sarah Tabrizi
- UCL Huntington's disease Centre, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, WC1N 3BG, UK
- Dementia Research Institute at UCL, London, WC1N 3BG, UK
| | - Jan-Willem Taanman
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Rowland Hill Street, London, NW3 2PF, UK
| | - Michael Orth
- Department of Neurology, Ulm University, Ulm, Germany
- Swiss Huntington Centre, Siloah AG, 3073 Gümligen, Switzerland
- University Hospital of Old Age Psychiatry and Psychotherapy, Bern University, Switzerland
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Abu-Hanna J, Anastasakis E, Patel JA, Eddama MMR, Denton CP, Taanman JW, Abraham D, Clapp LH. Prostacyclin mimetics inhibit DRP1-mediated pro-proliferative mitochondrial fragmentation in pulmonary arterial hypertension. Vascul Pharmacol 2023; 151:107194. [PMID: 37442283 DOI: 10.1016/j.vph.2023.107194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/23/2023] [Accepted: 07/10/2023] [Indexed: 07/15/2023]
Abstract
Pulmonary arterial hypertension (PAH) is a rare cardiopulmonary disorder, involving the remodelling of the small pulmonary arteries. Underlying this remodelling is the hyper-proliferation of pulmonary arterial smooth muscle cells within the medial layers of these arteries and their encroachment on the lumen. Previous studies have demonstrated an association between excessive mitochondrial fragmentation, a consequence of increased expression and post-translational activation of the mitochondrial fission protein dynamin-related protein 1 (DRP1), and pathological proliferation in PASMCs derived from PAH patients. However, the impact of prostacyclin mimetics, widely used in the treatment of PAH, on this pathological mitochondrial fragmentation remains unexplored. We hypothesise that these agents, which are known to attenuate the proliferative phenotype of PAH PASMCs, do so in part by inhibiting mitochondrial fragmentation. In this study, we confirmed the previously reported increase in DRP1-mediated mitochondrial hyper-fragmentation in PAH PASMCs. We then showed that the prostacyclin mimetic treprostinil signals via either the Gs-coupled IP or EP2 receptor to inhibit mitochondrial fragmentation and the associated hyper-proliferation in a manner analogous to the DRP1 inhibitor Mdivi-1. We also showed that treprostinil recruits either the IP or EP2 receptor to activate PKA and induce the phosphorylation of DRP1 at the inhibitory residue S637 and inhibit that at the stimulatory residue S616, both of which are suggestive of reduced DRP1 fission activity. Like treprostinil, MRE-269, an IP receptor agonist, and butaprost, an EP2 receptor agonist, attenuated DRP1-mediated mitochondrial fragmentation through PKA. We conclude that prostacyclin mimetics produce their anti-proliferative effects on PAH PASMCs in part by inhibiting DRP1-mediated mitochondrial fragmentation.
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Affiliation(s)
- Jeries Abu-Hanna
- Centre for Cardiovascular Physiology and Pharmacology, Institute of Cardiovascular Science, University College London, London, United Kingdom; Centre for Rheumatology, Division of Medicine, University College London, London, United Kingdom
| | - Evangelos Anastasakis
- Centre for Cardiovascular Physiology and Pharmacology, Institute of Cardiovascular Science, University College London, London, United Kingdom; Centre for Rheumatology, Division of Medicine, University College London, London, United Kingdom
| | - Jigisha A Patel
- Centre for Cardiovascular Physiology and Pharmacology, Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Mohammad Mahmoud Rajab Eddama
- Department of Surgical Biotechnology, Division of Surgery and Interventional Science, University College London, London, United Kingdom
| | - Christopher P Denton
- Centre for Rheumatology, Division of Medicine, University College London, London, United Kingdom
| | - Jan-Willem Taanman
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - David Abraham
- Centre for Rheumatology, Division of Medicine, University College London, London, United Kingdom
| | - Lucie H Clapp
- Centre for Cardiovascular Physiology and Pharmacology, Institute of Cardiovascular Science, University College London, London, United Kingdom.
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Protasoni M, Taanman JW. Remodelling of the Mitochondrial Bioenergetic Pathways in Human Cultured Fibroblasts with Carbohydrates. Biology (Basel) 2023; 12:1002. [PMID: 37508431 PMCID: PMC10376623 DOI: 10.3390/biology12071002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/05/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023]
Abstract
Mitochondrial oxidative phosphorylation defects underlie many neurological and neuromuscular diseases. Patients' primary dermal fibroblasts are one of the most commonly used in vitro models to study mitochondrial pathologies. However, fibroblasts tend to rely more on glycolysis than oxidative phosphorylation for their energy when cultivated in standard high-glucose medium, rendering it difficult to expose mitochondrial dysfunctions. This study aimed to systematically investigate to which extent the use of galactose- or fructose-based medium switches the fibroblasts' energy metabolism to a more oxidative state. Highly proliferative cells depend more on glycolysis than less proliferative cells. Therefore, we investigated two primary dermal fibroblast cultures from healthy subjects: a highly proliferative neonatal culture and a slower-growing adult culture. Cells were cultured with 25 mM glucose, galactose or fructose, and 4 mM glutamine as carbon sources. Compared to glucose, both galactose and fructose reduce the cellular proliferation rate, but the galactose-induced drop in proliferation is much more profound than the one observed in cells cultivated in fructose. Both galactose and fructose result in a modest increase in mitochondrial content, including mitochondrial DNA, and a disproportionate increase in protein levels, assembly, and activity of the oxidative phosphorylation enzyme complexes. Galactose- and fructose-based media induce a switch of the prevalent biochemical pathway in cultured fibroblasts, enhancing aerobic metabolism when compared to glucose-based medium. While both galactose and fructose stimulate oxidative phosphorylation to a comparable degree, galactose decreases the cellular proliferation rate more than fructose, suggesting that a fructose-based medium is a better choice when studying partial oxidative phosphorylation defects in patients' fibroblasts.
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Affiliation(s)
- Margherita Protasoni
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, Royal Free Campus (M12), Rowland Hill Street, London NW3 2PF, UK
| | - Jan-Willem Taanman
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, Royal Free Campus (M12), Rowland Hill Street, London NW3 2PF, UK
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Cantanhede IG, Liu H, Liu H, Balbuena Rodriguez V, Shiwen X, Ong VH, Denton CP, Ponticos M, Xiong G, Lima-Filho JL, Abraham D, Abu-Hanna J, Taanman JW. Exploring metabolism in scleroderma reveals opportunities for pharmacological intervention for therapy in fibrosis. Front Immunol 2022; 13:1004949. [PMID: 36304460 PMCID: PMC9592691 DOI: 10.3389/fimmu.2022.1004949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 09/26/2022] [Indexed: 12/04/2022] Open
Abstract
Background Recent evidence has indicated that alterations in energy metabolism play a critical role in the pathogenesis of fibrotic diseases. Studies have suggested that ‘metabolic reprogramming’ involving the glycolysis and oxidative phosphorylation (OXPHOS) in cells lead to an enhanced generation of energy and biosynthesis. The aim of this study was to assess the molecular basis of changes in fibrotic metabolism in systemic sclerosis (Scleroderma; SSc) and highlight the most appropriate targets for anti-fibrotic therapies. Materials and methods Dermal fibroblasts were isolated from five SSc patients and five healthy donors. Cells were cultured in medium with/without TGF-β1 and with/without ALK5, pan-PIM or ATM kinase inhibitors. Extracellular flux analyses were performed to evaluate glycolytic and mitochondrial respiratory function. The mitochondrial network in TMRM-stained cells was visualized by confocal laser-scanning microscopy, followed by semi-automatic analysis on the ImageJ platform. Protein expression of ECM and fibroblast components, glycolytic enzymes, subunits of the five OXPHOS complexes, and dynamin-related GTPases and receptors involved in mitochondrial fission/fusion were assessed by western blotting. Results Enhanced mitochondrial respiration coupled to ATP production was observed in SSc fibroblasts at the expense of spare respiratory capacity. Although no difference was found in glycolysis when comparing SSc with healthy control fibroblasts, levels of phophofructokinase-1 isoform PFKM were significantly lower in SSc fibroblasts (P<0.05). Our results suggest that the number of respirasomes is decreased in the SSc mitochondria; however, the organelles formed a hyperfused network, which is thought to increase mitochondrial ATP production through complementation. The increased mitochondrial fusion correlated with a change in expression levels of regulators of mitochondrial morphology, including decreased levels of DRP1, increased levels of MIEF2 and changes in OPA1 isoform ratios. TGF-β1 treatment strongly stimulated glycolysis and mitochondrial respiration and induced the expression of fibrotic markers. The pan-PIM kinase inhibitor had no effect, whereas both ALK5 and ATM kinase inhibition abrogated TGF-β1-mediated fibroblast activation, and upregulation of glycolysis and respiration. Conclusions Our data provide evidence for a novel mechanism(s) by which SSc fibroblasts exhibit altered metabolic programs and highlight changes in respiration and dysregulated mitochondrial morphology and function, which can be selectively targeted by small molecule kinase inhibitors.
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Affiliation(s)
- Isabella Gomes Cantanhede
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London, London, United Kingdom
- Laboratory of Immunopathology Keizo Asami, Federal University of Pernambuco, Recife, Brazil
| | - Huan Liu
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London, London, United Kingdom
- Health Science Center, Xi’an Jiaotong University, Xi’an, China
| | - Huan Liu
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London, London, United Kingdom
| | - Vestaen Balbuena Rodriguez
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London, London, United Kingdom
| | - Xu Shiwen
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London, London, United Kingdom
| | - Voo H. Ong
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London, London, United Kingdom
| | - Christopher P. Denton
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London, London, United Kingdom
| | - Markella Ponticos
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London, London, United Kingdom
| | - Guo Xiong
- Health Science Center, Xi’an Jiaotong University, Xi’an, China
| | - José Luiz Lima-Filho
- Laboratory of Immunopathology Keizo Asami, Federal University of Pernambuco, Recife, Brazil
| | - David Abraham
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London, London, United Kingdom
- *Correspondence: David Abraham, ; Jan-Willem Taanman,
| | - Jeries Abu-Hanna
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London, London, United Kingdom
| | - Jan-Willem Taanman
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, London, United Kingdom
- *Correspondence: David Abraham, ; Jan-Willem Taanman,
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Yang SY, Taanman JW, Gegg M, Schapira AHV. Ambroxol reverses tau and α-synuclein accumulation in a cholinergic N370S GBA1 mutation model. Hum Mol Genet 2022; 31:2396-2405. [PMID: 35179198 PMCID: PMC9307316 DOI: 10.1093/hmg/ddac038] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 11/05/2021] [Accepted: 01/27/2022] [Indexed: 01/19/2023] Open
Abstract
Cognitive impairment is a common non-motor complication of Parkinson's disease (PD). Glucocerebrosidase gene (GBA1) variants are found in 10-15% of PD cases and are numerically the most important risk factor for PD and dementia with Lewy bodies. Accumulation of α-synuclein and tau pathology is thought to underlie cognitive impairment in PD and likely involves cholinergic as well as dopaminergic neurons. Neural crest stem cells were isolated from both PD patients with the common heterozygous N370S GBA1 mutation and normal subjects without GBA1 mutations. The stem cells were used to generate a cholinergic neuronal cell model. The effects of the GBA1 variant on glucocerebrosidase (GCase) protein and activity, and cathepsin D, tau and α-synuclein protein levels in cholinergic neurons were examined. Ambroxol, a GCase chaperone, was used to investigate whether GCase enhancement was able to reverse the effects of the GBA1 variant on cholinergic neurons. Significant reductions in GCase protein and activity, as well as in cathepsin D levels, were found in GBA1 mutant (N370S/WT) cholinergic neurons. Both tau and α-synuclein levels were significantly increased in GBA1 mutant (N370S/WT) cholinergic neurons. Ambroxol significantly enhanced GCase activity and decreased both tau and α-synuclein levels in cholinergic neurons. GBA1 mutations interfere with the metabolism of α-synuclein and tau proteins and induce higher levels of α-synuclein and tau proteins in cholinergic neurons. The GCase pathway provides a potential therapeutic target for neurodegenerative disorders related to pathological α-synuclein or tau accumulation.
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Affiliation(s)
- Shi Yu Yang
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, Royal Free Campus, London NW3 2PF, UK
| | - Jan-Willem Taanman
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, Royal Free Campus, London NW3 2PF, UK
| | - Matthew Gegg
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, Royal Free Campus, London NW3 2PF, UK
| | - Anthony H V Schapira
- To whom correspondence should be addressed at: Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, Royal Free Campus, London NW3 2PF, UK. Tel: +44 02078302021 (Ex: 68166);
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Bradshaw AV, Campbell P, Schapira AHV, Morris HR, Taanman JW. The PINK1-Parkin mitophagy signalling pathway is not functional in peripheral blood mononuclear cells. PLoS One 2021; 16:e0259903. [PMID: 34762687 PMCID: PMC8584748 DOI: 10.1371/journal.pone.0259903] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 10/28/2021] [Indexed: 12/25/2022] Open
Abstract
Mutations in the PINK1 and PRKN genes are the most common cause of early-onset familial Parkinson disease. These genes code for the PINK1 and Parkin proteins, respectively, which are involved in the degradation of dysfunctional mitochondria through mitophagy. An early step in PINK1 –Parkin mediated mitophagy is the ubiquitination of the mitofusin proteins MFN1 and -2. The ubiquitination of MFN1 and -2 in patient samples may therefore serve as a biomarker to determine the functional effects of PINK1 and PRKN mutations, and to screen idiopathic patients for potential mitophagy defects. We aimed to characterise the expression of the PINK1 –Parkin mitophagy machinery in peripheral blood mononuclear cells (PBMCs) and assess if these cells could serve as a platform to evaluate mitophagy via analysis of MFN1 and -2 ubiquitination. Mitophagy was induced through mitochondrial depolarisation by treatment with the protonophore CCCP and ubiquitinated MFN proteins were analysed by western blotting. In addition, PINK1 and PRKN mRNA and protein expression levels were characterised with reverse transcriptase quantitative PCR and western blotting, respectively. Whilst CCCP treatment led to MFN ubiquitination in primary fibroblasts, SH-SY5Y neuroblastoma cells and Jurkat leukaemic cells, treatment of PBMCs did not induce ubiquitination of MFN. PRKN mRNA and protein was readily detectable in PBMCs at comparable levels to those observed in Jurkat and fibroblast cells. In contrast, PINK1 protein was undetectable and PINK1 mRNA levels were remarkably low in control PBMCs. Our findings suggest that the PINK1 –Parkin mitophagy signalling pathway is not functional in PBMCs. Therefore, PBMCs are not a suitable biosample for analysis of mitophagy function in Parkinson disease patients.
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Affiliation(s)
- Aaron V. Bradshaw
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Philip Campbell
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Anthony H. V. Schapira
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Huw R. Morris
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Jan-Willem Taanman
- Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, London, United Kingdom
- * E-mail:
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Kojer K, Hering T, Bazenet C, Weiss A, Herrmann F, Taanman JW, Orth M. Huntingtin Aggregates and Mitochondrial Pathology in Skeletal Muscle but not Heart of Late-Stage R6/2 Mice. J Huntingtons Dis 2020; 8:145-159. [PMID: 30814364 DOI: 10.3233/jhd-180324] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Cell or tissue specific background may influence the consequences of expressing the Huntington's disease (HD) mutation. Aggregate formation is known to occur in skeletal muscle, but not heart of the R6/2 fragment HD model. OBJECTIVE We asked whether aggregate formation and the expression and subcellular localization of huntingtin species was associated with mitochondrial dysfunction. METHODS We analyzed levels of soluble HTT and HTT aggregates, as well as important fission and fusion proteins and mitochondrial respiratory chain activities, in quadriceps and heart of the R6/2 N-terminal fragment mouse model (12 weeks, 160±10 CAG repeats). RESULTS Soluble mutant HTT was present in both tissues with expression higher in cytoplasmic/mitochondrial than nuclear fractions. HTT aggregates were only detectable in R6/2 quadriceps, in association with increased levels of the pro-fission factor DRP1 and its phosphorylated active form, and decreased levels of the pro-fusion factor MFN2. In addition, respiratory chain complex activities were decreased. In heart that was without detectable HTT aggregates, we found no evidence for mitochondrial dysfunction. CONCLUSION Tissue specific factors may exist that protect the R6/2 heart from HTT aggregate formation and mitochondrial pathology.
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Affiliation(s)
- Kerstin Kojer
- Department of Neurology, Ulm University, Ulm, Germany
| | - Tanja Hering
- Department of Neurology, Ulm University, Ulm, Germany
| | | | | | | | - Jan-Willem Taanman
- Department of Clinical Neurosciences, UCL Institute of Neurology, London, UK
| | - Michael Orth
- Department of Neurology, Ulm University, Ulm, Germany
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Protasoni M, Kroon AM, Taanman JW. Mitochondria as oncotarget: a comparison between the tetracycline analogs doxycycline and COL-3. Oncotarget 2018; 9:33818-33831. [PMID: 30333912 PMCID: PMC6173462 DOI: 10.18632/oncotarget.26107] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 08/24/2018] [Indexed: 01/23/2023] Open
Abstract
Tetracyclines have anticancer properties in addition to their well-known antibacterial properties. It has been proposed that tetracyclines slow metastasis and angiogenesis through inhibition of matrix metalloproteinases. However, we believe that the anticancer effect of tetracyclines is due to their inhibition of mitochondrial protein synthesis, resulting in a decrease of the mitochondrial energy generating capacity. Several groups have developed analogs that are void of antibacterial action. An example is COL-3, which is currently tested for its anticancer effects in clinical trials. We have undertaken a comparative study of the tetracycline analogs COL-3 and doxycycline, which has an antibacterial function, to further investigate the role of the mitochondrial energy generating capacity in the anticancer mechanism and, thereby, evaluate the usefulness of mitochondria as an oncotarget. Our experiments with cultures of the human A549, COLO357 and HT29 cancer cells and fibroblasts indicated that COL-3 is significantly more cytotoxic than doxycycline. Mitochondrial translation assays demonstrated that COL-3 has retained its inhibitory effect on mitochondrial protein synthesis. Both drugs caused a severe decrease in the levels of mitochondrially encoded cytochrome-c oxidase subunits and cytochrome-c oxidase activity. In addition, COL-3 produced a marked drop in the level of nuclear-encoded succinate dehydrogenase subunit A and citrate synthase activity, indicating that COL-3 has multiple inhibitory effects. Contrary to COL-3, the anticancer action of doxycycline appears to be based specifically on inhibition of mitochondrial protein synthesis, which is thought to affect rapidly proliferating cancer cells more than healthy tissue. Doxycycline is likely to cause less side effects that COL-3.
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Affiliation(s)
- Margherita Protasoni
- Department of Clinical and Movement Neurosciences, Institute of Neurology, University College London, London, NW3 2PF, UK
| | - Albert M Kroon
- Department of Clinical and Movement Neurosciences, Institute of Neurology, University College London, London, NW3 2PF, UK
| | - Jan-Willem Taanman
- Department of Clinical and Movement Neurosciences, Institute of Neurology, University College London, London, NW3 2PF, UK
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Abstract
Groundbreaking work by Kadenbach and colleagues in the 1980s revealed the presence of 13 subunits in the mammalian mitochondrial cytochrome-c oxidase (COX; Complex IV). This observation stood the test of time until 2012 when it was demonstrated that NDUFA4, a polypeptide previously attributed to mitochondrial Complex I, was a 14th subunit of COX. In his recent opinion article, Kadenbach argued that NDUFA4 is not a subunit of COX. However, based on the findings that NDUFA4 deficiency results in a severe loss of COX activity and that NDUFA4 represents a stoichiometric component of the individual COX complex, we reason that NDUFA4 is a bona fide COX subunit and propose renaming it as COX subunit FA4 (COXFA4).
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Affiliation(s)
- Robert D S Pitceathly
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Jan-Willem Taanman
- Department of Clinical Neurosciences, UCL Institute of Neurology, London, UK.
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Mokretar K, Pease D, Taanman JW, Soenmez A, Ejaz A, Lashley T, Ling H, Gentleman S, Houlden H, Holton JL, Schapira AHV, Nacheva E, Proukakis C. Somatic copy number gains of α-synuclein (SNCA) in Parkinson’s disease and multiple system atrophy brains. Brain 2018; 141:2419-2431. [DOI: 10.1093/brain/awy157] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 04/16/2018] [Indexed: 12/18/2022] Open
Affiliation(s)
- Katya Mokretar
- Department of Clinical Neuroscience, UCL Institute of Neurology, University College London, London, UK
- Department of Academic Haematology, University College London, UK
| | - Daniel Pease
- Department of Clinical Neuroscience, UCL Institute of Neurology, University College London, London, UK
| | - Jan-Willem Taanman
- Department of Clinical Neuroscience, UCL Institute of Neurology, University College London, London, UK
| | - Aynur Soenmez
- Department of Clinical Neuroscience, UCL Institute of Neurology, University College London, London, UK
| | - Ayesha Ejaz
- Department of Clinical Neuroscience, UCL Institute of Neurology, University College London, London, UK
| | - Tammaryn Lashley
- Queen Square Brain Bank for Neurodegenerative diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Helen Ling
- Queen Square Brain Bank for Neurodegenerative diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | | | - Henry Houlden
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Janice L Holton
- Queen Square Brain Bank for Neurodegenerative diseases, Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Anthony H V Schapira
- Department of Clinical Neuroscience, UCL Institute of Neurology, University College London, London, UK
| | | | - Christos Proukakis
- Department of Clinical Neuroscience, UCL Institute of Neurology, University College London, London, UK
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12
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Khorsandi SE, Taanman JW, Heaton N. Subunit composition of respiratory chain complex 1 and its responses to oxygen in mitochondria from human donor livers. BMC Res Notes 2017; 10:547. [PMID: 29096719 PMCID: PMC5667463 DOI: 10.1186/s13104-017-2863-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/24/2017] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Donor liver function in transplantation is defined by mitochondrial function and the ability of mitochondria to recover from the sequence of warm and/or cold ischemia. Mitochondrial resilience maybe related to assembly and- subunit composition of Complex 1. The aim of this study was to determine if Complex 1 subunit composition was different in donor livers of varying quality and whether oxygen exposure had any effect. RESULTS Five human livers not suitable for transplant were split. One half placed in cold static storage and the other half exposed to 40% oxygen for 2 h. Protein was extracted for western blot. Membranes were probed with antibodies against β-actin and the following subunits of Complex 1: MTND1, NDUFA10, NDUFB6 and NDUFV2. No difference in steady state Complex 1 subunit composition was demonstrated between donor livers of varying quality, in terms of steatosis or mode of donation. Neither did exposure to oxygen influence Complex 1 subunit composition. This small observational study on subunit levels suggest that Complex 1 is fully assembled as no degradation of subunits associated with the different parts of the enzyme was seen.
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Affiliation(s)
- S E Khorsandi
- Institute of Liver Studies, King's College Hospital, Kings College London, London, SE5 9RS, UK
| | - J W Taanman
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London, UK
| | - N Heaton
- Institute of Liver Studies, King's College Hospital, Kings College London, London, SE5 9RS, UK.
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Bugiardini E, Poole OV, Manole A, Pittman AM, Horga A, Hargreaves I, Woodward CE, Sweeney MG, Holton JL, Taanman JW, Plant GT, Poulton J, Zeviani M, Ghezzi D, Taylor J, Smith C, Fratter C, Kanikannan MA, Paramasivam A, Thangaraj K, Spinazzola A, Holt IJ, Houlden H, Hanna MG, Pitceathly RDS. Clinicopathologic and molecular spectrum of RNASEH1-related mitochondrial disease. Neurol Genet 2017; 3:e149. [PMID: 28508084 PMCID: PMC5413961 DOI: 10.1212/nxg.0000000000000149] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/13/2017] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Pathologic ribonuclease H1 (RNase H1) causes aberrant mitochondrial DNA (mtDNA) segregation and is associated with multiple mtDNA deletions. We aimed to determine the prevalence of RNase H1 gene (RNASEH1) mutations among patients with mitochondrial disease and establish clinically meaningful genotype-phenotype correlations. METHODS RNASEH1 was analyzed in patients with (1) multiple deletions/depletion of muscle mtDNA and (2) mendelian progressive external ophthalmoplegia (PEO) with neuropathologic evidence of mitochondrial dysfunction, but no detectable multiple deletions/depletion of muscle mtDNA. Clinicopathologic and molecular evaluation of the newly identified and previously reported patients harboring RNASEH1 mutations was subsequently undertaken. RESULTS Pathogenic c.424G>A p.Val142Ile RNASEH1 mutations were detected in 3 pedigrees among the 74 probands screened. Given that all 3 families had Indian ancestry, RNASEH1 genetic analysis was undertaken in 50 additional Indian probands with variable clinical presentations associated with multiple mtDNA deletions, but no further RNASEH1 mutations were confirmed. RNASEH1-related mitochondrial disease was characterized by PEO (100%), cerebellar ataxia (57%), and dysphagia (50%). The ataxia neuropathy spectrum phenotype was observed in 1 patient. Although the c.424G>A p.Val142Ile mutation underpins all reported RNASEH1-related mitochondrial disease, haplotype analysis suggested an independent origin, rather than a founder event, for the variant in our families. CONCLUSIONS In our cohort, RNASEH1 mutations represent the fourth most common cause of adult mendelian PEO associated with multiple mtDNA deletions, following mutations in POLG, RRM2B, and TWNK. RNASEH1 genetic analysis should also be considered in all patients with POLG-negative ataxia neuropathy spectrum. The pathophysiologic mechanisms by which the c.424G>A p.Val142Ile mutation impairs human RNase H1 warrant further investigation.
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Affiliation(s)
- Enrico Bugiardini
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Olivia V Poole
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Andreea Manole
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Alan M Pittman
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Alejandro Horga
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Iain Hargreaves
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Cathy E Woodward
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Mary G Sweeney
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Janice L Holton
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Jan-Willem Taanman
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Gordon T Plant
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Joanna Poulton
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Massimo Zeviani
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Daniele Ghezzi
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - John Taylor
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Conrad Smith
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Carl Fratter
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Meena A Kanikannan
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Arumugam Paramasivam
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Kumarasamy Thangaraj
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Antonella Spinazzola
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Ian J Holt
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Henry Houlden
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Robert D S Pitceathly
- MRC Centre for Neuromuscular Diseases (E.B., O.V.P., A.M., A.H., J.L.H., H.H., M.G.H., R.D.S.P.), UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery; Department of Molecular Neuroscience (A.M., A.M.P., J.L.H., H.H., M.G.H.), Division of Neuropathology (J.L.H.), Department of Clinical Neuroscience (J.-W.T., A.S., I.J.H.), UCL Institute of Neurology; Neurometabolic Unit (I.H.), Neurogenetics Unit (C.E.W., M.G.S.), Department of Neuro-ophthalmology (G.T.P.), National Hospital for Neurology and Neurosurgery, London; Nuffield Department of Obstetrics and Gynaecology (J.P.), University of Oxford; MRC-Mitochondrial Biology Unit (M.Z.), Cambridge, UK; Unit of Molecular Neurogenetics (D.G.), Fondazione IRCCS Istituto Neurologico "Carlo Besta," Milan, Italy; Oxford Medical Genetics Laboratories (J.T., C.S., C.F.), Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, UK; Department of Neurology (M.A.K.), Nizam's Institute of Medical Sciences; CSIR-Centre for Cellular and Molecular Biology (A.P., K.T.), Hyderabad, Telangana, India; MRC Mill Hill Laboratory (I.J.H.), London, UK; Biodonostia Research Institute (I.J.H.), San Sebastián, Spain; and Department of Basic and Clinical Neuroscience (R.D.S.P.), Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
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Yang SY, Beavan M, Chau KY, Taanman JW, Schapira AHV. A Human Neural Crest Stem Cell-Derived Dopaminergic Neuronal Model Recapitulates Biochemical Abnormalities in GBA1 Mutation Carriers. Stem Cell Reports 2017; 8:728-742. [PMID: 28216145 PMCID: PMC5355624 DOI: 10.1016/j.stemcr.2017.01.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 01/13/2017] [Accepted: 01/16/2017] [Indexed: 12/22/2022] Open
Abstract
Numerically the most important risk factor for the development of Parkinson's disease (PD) is the presence of mutations in the glucocerebrosidase GBA1 gene. In vitro and in vivo studies show that GBA1 mutations reduce glucocerebrosidase (GCase) activity and are associated with increased α-synuclein levels, reflecting similar changes seen in idiopathic PD brain. We have developed a neural crest stem cell-derived dopaminergic neuronal model that recapitulates biochemical abnormalities in GBA1 mutation-associated PD. Cells showed reduced GCase protein and activity, impaired macroautophagy, and increased α-synuclein levels. Advantages of this approach include easy access to stem cells, no requirement to reprogram, and retention of the intact host genome. Treatment with a GCase chaperone increased GCase protein levels and activity, rescued the autophagic defects, and decreased α-synuclein levels. These results provide the basis for further investigation of GCase chaperones or similar drugs to slow the progression of PD. A neuronal model recapitulates biochemical abnormalities in GBA1 mutation PD Ambroxol rescued the autophagic defects in human GBA1 mutant neuronal cells Ambroxol decreased α-synuclein levels human GBA1 mutant neuronal cells
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Affiliation(s)
- Shi-Yu Yang
- Department of Clinical Neurosciences, UCL Institute of Neurology, Rowland Hill Street, London NW3 2PF, UK
| | - Michelle Beavan
- Department of Clinical Neurosciences, UCL Institute of Neurology, Rowland Hill Street, London NW3 2PF, UK
| | - Kai-Yin Chau
- Department of Clinical Neurosciences, UCL Institute of Neurology, Rowland Hill Street, London NW3 2PF, UK
| | - Jan-Willem Taanman
- Department of Clinical Neurosciences, UCL Institute of Neurology, Rowland Hill Street, London NW3 2PF, UK
| | - Anthony H V Schapira
- Department of Clinical Neurosciences, UCL Institute of Neurology, Rowland Hill Street, London NW3 2PF, UK.
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Kojer K, Hering T, Birth N, Lenk T, Hallitsch J, Parker J, Haider S, Heikkinen T, Kontkanen O, Tabrizi SJ, Taanman JW, Orth M. B25 Mitochondrial fission and fusion in skeletal muscle from HD patients and zQ175 mice. J Neurol Psychiatry 2016. [DOI: 10.1136/jnnp-2016-314597.56] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Wedatilake Y, Niazi R, Fassone E, Powell CA, Pearce S, Plagnol V, Saldanha JW, Kleta R, Chong WK, Footitt E, Mills PB, Taanman JW, Minczuk M, Clayton PT, Rahman S. TRNT1 deficiency: clinical, biochemical and molecular genetic features. Orphanet J Rare Dis 2016; 11:90. [PMID: 27370603 PMCID: PMC4930608 DOI: 10.1186/s13023-016-0477-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 06/24/2016] [Indexed: 11/10/2022] Open
Abstract
Background TRNT1 (CCA-adding transfer RNA nucleotidyl transferase) enzyme deficiency is a new metabolic disease caused by defective post-transcriptional modification of mitochondrial and cytosolic transfer RNAs (tRNAs). Results We investigated four patients from two families with infantile-onset cyclical, aseptic febrile episodes with vomiting and diarrhoea, global electrolyte imbalance during these episodes, sideroblastic anaemia, B lymphocyte immunodeficiency, retinitis pigmentosa, hepatosplenomegaly, exocrine pancreatic insufficiency and renal tubulopathy. Other clinical features found in children include sensorineural deafness, cerebellar atrophy, brittle hair, partial villous atrophy and nephrocalcinosis. Whole exome sequencing and bioinformatic filtering were utilised to identify recessive compound heterozygous TRNT1 mutations (missense mutation c.668T>C, p.Ile223Thr and a novel splice mutation c.342+5G>T) segregating with disease in the first family. The second family was found to have a homozygous TRNT1 mutation (c.569G>T), p.Arg190Ile, (previously published). We found normal mitochondrial translation products using passage matched controls and functional perturbation of 3’ CCA addition to mitochondrial tRNAs (tRNACys, tRNALeuUUR and tRNAHis) in fibroblasts from two patients, demonstrating a pathomechanism affecting the CCA addition to mt-tRNAs. Acute management of these patients included transfusion for anaemia, fluid and electrolyte replacement and immunoglobulin therapy. We also describe three-year follow-up findings after treatment by bone marrow transplantation in one patient, with resolution of fever and reversal of the abnormal metabolic profile. Conclusions Our report highlights that TRNT1 mutations cause a spectrum of disease ranging from a childhood-onset complex disease with manifestations in most organs to an adult-onset isolated retinitis pigmentosa presentation. Systematic review of all TRNT1 cases and mutations reported to date revealed a distinctive phenotypic spectrum and metabolic and other investigative findings, which will facilitate rapid clinical recognition of future cases.
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Affiliation(s)
- Yehani Wedatilake
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Rojeen Niazi
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Elisa Fassone
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | | | | | | | - José W Saldanha
- Division of Mathematical Biology, National Institute for Medical Research, Mill Hill, London, UK
| | - Robert Kleta
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK.,UCL Genetics Institute, London, UK.,Division of Medicine, UCL, London, UK
| | - W Kling Chong
- Radiology Department, Great Ormond Street Hospital, London, UK
| | - Emma Footitt
- Metabolic medicine department, Great Ormond Street Hospital, London, UK
| | - Philippa B Mills
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Jan-Willem Taanman
- Department of Clinical Neurosciences, UCL Institute of Neurology, London, UK
| | | | - Peter T Clayton
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK
| | - Shamima Rahman
- Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, UK. .,Mitochondrial Research Group, Genetics and Genomic Medicine Programme, UCL Institute of Child Health, 30, Guilford Street, London, WC1N 1EH, UK.
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Rajakulendran S, Pitceathly RDS, Taanman JW, Costello H, Sweeney MG, Woodward CE, Jaunmuktane Z, Holton JL, Jacques TS, Harding BN, Fratter C, Hanna MG, Rahman S. A Clinical, Neuropathological and Genetic Study of Homozygous A467T POLG-Related Mitochondrial Disease. PLoS One 2016; 11:e0145500. [PMID: 26735972 PMCID: PMC4703200 DOI: 10.1371/journal.pone.0145500] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/06/2015] [Indexed: 02/06/2023] Open
Abstract
Mutations in the nuclear gene POLG (encoding the catalytic subunit of DNA polymerase gamma) are an important cause of mitochondrial disease. The most common POLG mutation, A467T, appears to exhibit considerable phenotypic heterogeneity. The mechanism by which this single genetic defect results in such clinical diversity remains unclear. In this study we evaluate the clinical, neuropathological and mitochondrial genetic features of four unrelated patients with homozygous A467T mutations. One patient presented with the severe and lethal Alpers-Huttenlocher syndrome, which was confirmed on neuropathology, and was found to have a depletion of mitochondrial DNA (mtDNA). Of the remaining three patients, one presented with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), one with a phenotype in the Myoclonic Epilepsy, Myopathy and Sensory Ataxia (MEMSA) spectrum and one with Sensory Ataxic Neuropathy, Dysarthria and Ophthalmoplegia (SANDO). All three had secondary accumulation of multiple mtDNA deletions. Complete sequence analysis of muscle mtDNA using the MitoChip resequencing chip in all four cases demonstrated significant variation in mtDNA, including a pathogenic MT-ND5 mutation in one patient. These data highlight the variable and overlapping clinical and neuropathological phenotypes and downstream molecular defects caused by the A467T mutation, which may result from factors such as the mtDNA genetic background, nuclear genetic modifiers and environmental stressors.
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Affiliation(s)
- Sanjeev Rajakulendran
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery and the MRC Centre for Neuromuscular Diseases, Queen Square, London WC1N 3BG, United Kingdom
| | - Robert D. S. Pitceathly
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, United Kingdom and Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King’s College London SE5 8AF, United Kingdom
| | - Jan-Willem Taanman
- Department of Clinical Neurosciences, UCL Institute of Neurology, London NW3 2PF, United Kingdom
| | - Harry Costello
- Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 1EH, United Kingdom
| | - Mary G. Sweeney
- Department of Neurogenetics, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Cathy E. Woodward
- Department of Neurogenetics, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Zane Jaunmuktane
- Division of Neuropathology, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Janice L. Holton
- Division of Neuropathology, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, United Kingdom
| | - Thomas S. Jacques
- Developmental Biology and Cancer Programme, UCL Institute of Child Health and Department of Histopathology, Great Ormond Street Hospital for Children Foundation Trust, London WC1N 1EH, United Kingdom
| | - Brian N. Harding
- Division of Neuropathology, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Carl Fratter
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford OX3 7LE, United Kingdom
| | - Michael G. Hanna
- UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery and the MRC Centre for Neuromuscular Diseases, Queen Square, London WC1N 3BG, United Kingdom
| | - Shamima Rahman
- Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Institute of Child Health, London WC1N 1EH, United Kingdom
- Metabolic Unit, Great Ormond Street Hospital, London WC1N 3JH, United Kingdom
- * E-mail:
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18
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Shahni R, Cale CM, Anderson G, Osellame LD, Hambleton S, Jacques TS, Wedatilake Y, Taanman JW, Chan E, Qasim W, Plagnol V, Chalasani A, Duchen MR, Gilmour KC, Rahman S. Signal transducer and activator of transcription 2 deficiency is a novel disorder of mitochondrial fission. Brain 2015; 138:2834-46. [PMID: 26122121 PMCID: PMC5808733 DOI: 10.1093/brain/awv182] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/28/2015] [Indexed: 01/17/2023] Open
Abstract
Defects of mitochondrial dynamics are emerging causes of neurological disease. In two children presenting with severe neurological deterioration following viral infection we identified a novel homozygous STAT2 mutation, c.1836 C>A (p.Cys612Ter), using whole exome sequencing. In muscle and fibroblasts from these patients, and a third unrelated STAT2-deficient patient, we observed extremely elongated mitochondria. Western blot analysis revealed absence of the STAT2 protein and that the mitochondrial fission protein DRP1 (encoded by DNM1L) is inactive, as shown by its phosphorylation state. All three patients harboured decreased levels of DRP1 phosphorylated at serine residue 616 (P-DRP1(S616)), a post-translational modification known to activate DRP1, and increased levels of DRP1 phosphorylated at serine 637 (P-DRP1(S637)), associated with the inactive state of the DRP1 GTPase. Knockdown of STAT2 in SHSY5Y cells recapitulated the fission defect, with elongated mitochondria and decreased P-DRP1(S616) levels. Furthermore the mitochondrial fission defect in patient fibroblasts was rescued following lentiviral transduction with wild-type STAT2 in all three patients, with normalization of mitochondrial length and increased P-DRP1(S616) levels. Taken together, these findings implicate STAT2 as a novel regulator of DRP1 phosphorylation at serine 616, and thus of mitochondrial fission, and suggest that there are interactions between immunity and mitochondria. This is the first study to link the innate immune system to mitochondrial dynamics and morphology. We hypothesize that variability in JAK-STAT signalling may contribute to the phenotypic heterogeneity of mitochondrial disease, and may explain why some patients with underlying mitochondrial disease decompensate after seemingly trivial viral infections. Modulating JAK-STAT activity may represent a novel therapeutic avenue for mitochondrial diseases, which remain largely untreatable. This may also be relevant for more common neurodegenerative diseases, including Alzheimer's, Huntington's and Parkinson's diseases, in which abnormalities of mitochondrial morphology have been implicated in disease pathogenesis.
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Affiliation(s)
- Rojeen Shahni
- 1 Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Institute of Child Health, Guilford Street, London, UK
| | - Catherine M Cale
- 2 Molecular Immunology Unit, Great Ormond Street Hospital, London, UK
| | - Glenn Anderson
- 3 Histopathology Unit, Great Ormond Street Hospital, London, UK
| | - Laura D Osellame
- 4 Department of Biochemistry and Molecular Biology, Monash University, Melbourne 3800, Australia
| | - Sophie Hambleton
- 5 Primary Immunodeficiency Group, Institute of Cellular Medicine, Newcastle University, UK
| | - Thomas S Jacques
- 3 Histopathology Unit, Great Ormond Street Hospital, London, UK 6 Developmental Neurosciences, UCL Institute of Child Health, London, UK
| | - Yehani Wedatilake
- 1 Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Institute of Child Health, Guilford Street, London, UK
| | - Jan-Willem Taanman
- 7 Department of Clinical Neurosciences, UCL Institute of Neurology, Rowland Hill Street, London, UK
| | - Emma Chan
- 2 Molecular Immunology Unit, Great Ormond Street Hospital, London, UK
| | - Waseem Qasim
- 2 Molecular Immunology Unit, Great Ormond Street Hospital, London, UK
| | | | - Annapurna Chalasani
- 9 Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | - Michael R Duchen
- 10 Cell and Developmental Biology, University College London, UK
| | | | - Shamima Rahman
- 1 Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Institute of Child Health, Guilford Street, London, UK 1 Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Institute of Child Health, Guilford Street, London, UK
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19
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Fassone E, Duncan AJ, Taanman JW, Pagnamenta AT, Sadowski MI, Holand T, Qasim W, Rutland P, Calvo SE, Mootha VK, Bitner-Glindzicz M, Rahman S. FOXRED1, encoding an FAD-dependent oxidoreductase complex-I-specific molecular chaperone, is mutated in infantile-onset mitochondrial encephalopathy. Hum Mol Genet 2015; 24:4183. [PMID: 26022995 DOI: 10.1093/hmg/ddv164] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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20
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Kroon AM, Taanman JW. Clonal expansion of T cells in abdominal aortic aneurysm: a role for doxycycline as drug of choice? Int J Mol Sci 2015; 16:11178-95. [PMID: 25993290 PMCID: PMC4463695 DOI: 10.3390/ijms160511178] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 02/05/2015] [Indexed: 11/16/2022] Open
Abstract
Most reported studies with animal models of abdominal aortic aneurysm (AAA) and several studies with patients have suggested that doxycycline favourably modifies AAA; however, a recent large long-term clinical trial found that doxycycline did not limit aneurysm growth. Thus, there is currently no convincing evidence that doxycycline reduces AAA expansion. Here, we critically review the available experimental and clinical information about the effects of doxycycline when used as a pharmacological treatment for AAA. The view that AAA can be considered an autoimmune disease and the observation that AAA tissue shows clonal expansion of T cells is placed in the light of the well-known inhibition of mitochondrial protein synthesis by doxycycline. In T cell leukaemia animal models, this inhibitory effect of the antibiotic has been shown to impede T cell proliferation, resulting in complete tumour eradication. We suggest that the available evidence of doxycycline action on AAA is erroneously ascribed to its inhibition of matrix metalloproteinases (MMPs) by competitive binding of the zinc ion co-factor. Although competitive binding may explain the inhibition of proteolytic activity, it does not explain the observed decreases of MMP mRNA levels. We propose that the observed effects of doxycycline are secondary to inhibition of mitochondrial protein synthesis. Provided that serum doxycycline levels are kept at adequate levels, the inhibition will result in a proliferation arrest, especially of clonally expanding T cells. This, in turn, leads to the decrease of proinflammatory cytokines that are normally generated by these cells. The drastic change in cell type composition may explain the changes in MMP mRNA and protein levels in the tissue samples.
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Affiliation(s)
- Albert M Kroon
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London NW3 2PF, UK.
| | - Jan-Willem Taanman
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London NW3 2PF, UK.
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21
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Hering T, Birth N, Taanman JW, Orth M. Selective striatal mtDNA depletion in end-stage Huntington's disease R6/2 mice. Exp Neurol 2015; 266:22-9. [PMID: 25682918 DOI: 10.1016/j.expneurol.2015.02.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 01/20/2015] [Accepted: 02/05/2015] [Indexed: 12/21/2022]
Abstract
In Huntington's disease (HD) the striatum and cortex seem particularly vulnerable. Mitochondrial dysfunction can also cause neurodegeneration with prominent striatal involvement very similar to HD. We first examined if mitochondrial biogenesis, mitochondrial DNA (mtDNA) transcription, and the implications for mitochondrial respiratory chain (MRC) assembly and function differ between the striatum and cortex compared with the whole brain average in the healthy mouse brain. We then examined the effects of the mutant huntingtin transgene in end-stage R6/2 mice. In wild-type mice, mitochondrial mass (citrate synthase levels, mtDNA copy number) was higher in the striatum than in the cortex or whole brain average. PGC-1α and TFAM mRNA levels were also higher in the striatum than the whole brain average and cortex. mRNA reserve for MRC Complex proteins was higher in the striatum and cortex. In addition, in the cortex a greater part of mitochondrial mass was dedicated to the generation of ATP by oxidative phosphorylation than in the striatum or on average in the brain. In the HD transgenic striatum there was selective mtDNA depletion without evidence that this translated to abnormalities of steady-state MRC function. Our data indicate that in mice the striatum differs from the cortex, or whole brain average, in potentially important aspects of mitochondrial biology. This may contribute to the increased vulnerability of the striatum to insults such as the HD mutation, causing selective striatal mtDNA depletion in end-stage R6/2 mice.
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Affiliation(s)
- Tanja Hering
- Department of Neurology, Ulm University, Germany
| | | | - Jan-Willem Taanman
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London, UK
| | - Michael Orth
- Department of Neurology, Ulm University, Germany
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22
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Kroon AM, Taanman JW. Comment on "aneurysmal lesions of patients with abdominal aortic aneurysm contain clonally expanded T cells". J Immunol 2014; 193:2041. [PMID: 25128546 DOI: 10.4049/jimmunol.1401520] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Albert M Kroon
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London NW3 2PF, United Kingdom
| | - Jan-Willem Taanman
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London NW3 2PF, United Kingdom
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23
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Pitceathly RDS, Taanman JW, Rahman S, Meunier B, Sadowski M, Cirak S, Hargreaves I, Land JM, Nanji T, Polke JM, Woodward CE, Sweeney MG, Solanki S, Foley AR, Hurles ME, Stalker J, Blake J, Holton JL, Phadke R, Muntoni F, Reilly MM, Hanna MG. COX10 mutations resulting in complex multisystem mitochondrial disease that remains stable into adulthood. JAMA Neurol 2014; 70:1556-61. [PMID: 24100867 DOI: 10.1001/jamaneurol.2013.3242] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Isolated cytochrome-c oxidase (COX) deficiency is one of the most frequent respiratory chain defects seen in human mitochondrial disease. Typically, patients present with severe neonatal multisystem disease and have an early fatal outcome. We describe an adult patient with isolated COX deficiency associated with a relatively mild clinical phenotype comprising myopathy; demyelinating neuropathy; premature ovarian failure; short stature; hearing loss; pigmentary maculopathy; and renal tubular dysfunction. OBSERVATIONS Whole-exome sequencing detected 1 known pathogenic and 1 novel COX10 mutation: c.1007A>T; p.Asp336Val, previously associated with fatal infantile COX deficiency, and c.1015C>T; p.Arg339Trp. Muscle COX holoenzyme and subassemblies were undetectable on immunoblots of blue-native gels, whereas denaturing gels and immunocytochemistry showed reduced core subunit MTCO1. Heme absorption spectra revealed low heme aa3 compatible with heme A:farnesyltransferase deficiency due to COX10 dysfunction. Both mutations demonstrated respiratory deficiency in yeast, confirming pathogenicity. A COX10 protein model was used to predict the structural consequences of the novel Arg339Trp and all previously reported substitutions. CONCLUSIONS AND RELEVANCE These findings establish that COX10 mutations cause adult mitochondrial disease. Nuclear modifiers, epigenetic phenomenon, and/or environmental factors may influence the disease phenotype caused by reduced COX activity and contribute to the variable clinical severity related to COX10 dysfunction.
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Affiliation(s)
- Robert D S Pitceathly
- Medical Research Council Centre for Neuromuscular Diseases, University College London Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, England
| | - Jan-Willem Taanman
- Department of Clinical Neuroscience, University College London Institute of Neurology, London, England
| | - Shamima Rahman
- Medical Research Council Centre for Neuromuscular Diseases, University College London Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, England3Mitochondrial Research Group, Clinical and Molecular Genetics Unit, Universi
| | - Brigitte Meunier
- Centre de Génétique Moléculaire, UPR3404, Centre national de la recherche scientifique, Gif-sur-Yvette, France
| | - Michael Sadowski
- Division of Mathematical Biology, National Institute for Medical Research, London, England
| | - Sebahattin Cirak
- Dubowitz Neuromuscular Centre, University College London Institute of Child Health and Great Ormond Street Hospital for Children NHS Foundation Trust, London, England
| | - Iain Hargreaves
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London, England
| | - John M Land
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London, England
| | - Tina Nanji
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, London, England
| | - James M Polke
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, London, England
| | - Cathy E Woodward
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, London, England
| | - Mary G Sweeney
- Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, London, England
| | - Shyam Solanki
- Department of Clinical Neuroscience, University College London Institute of Neurology, London, England
| | - A Reghan Foley
- Dubowitz Neuromuscular Centre, University College London Institute of Child Health and Great Ormond Street Hospital for Children NHS Foundation Trust, London, England
| | - Matthew E Hurles
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, England
| | - Jim Stalker
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, England
| | - Julian Blake
- Department of Clinical Neurophysiology, University College London Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, England11Department of Clinical Neurophysiology, Norfolk and Norwich University Hospital, Norwich, Engla
| | - Janice L Holton
- Medical Research Council Centre for Neuromuscular Diseases, University College London Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, England12Division of Neuropathology, University College London Institute of Neurolog
| | - Rahul Phadke
- Dubowitz Neuromuscular Centre, University College London Institute of Child Health and Great Ormond Street Hospital for Children NHS Foundation Trust, London, England12Division of Neuropathology, University College London Institute of Neurology, London, E
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, University College London Institute of Child Health and Great Ormond Street Hospital for Children NHS Foundation Trust, London, England
| | - Mary M Reilly
- Medical Research Council Centre for Neuromuscular Diseases, University College London Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, England13Department of Molecular Neuroscience, University College London Institute o
| | - Michael G Hanna
- Medical Research Council Centre for Neuromuscular Diseases, University College London Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, England13Department of Molecular Neuroscience, University College London Institute o
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24
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Manzoni C, Mamais A, Dihanich S, McGoldrick P, Devine MJ, Zerle J, Kara E, Taanman JW, Healy DG, Marti-Masso JF, Schapira AH, Plun-Favreau H, Tooze S, Hardy J, Bandopadhyay R, Lewis PA. Pathogenic Parkinson's disease mutations across the functional domains of LRRK2 alter the autophagic/lysosomal response to starvation. Biochem Biophys Res Commun 2013; 441:862-6. [PMID: 24211199 PMCID: PMC3858825 DOI: 10.1016/j.bbrc.2013.10.159] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 10/29/2013] [Indexed: 11/16/2022]
Abstract
LRRK2 is one of the most important genetic contributors to Parkinson's disease (PD). Point mutations in this gene cause an autosomal dominant form of PD, but to date no cellular phenotype has been consistently linked with mutations in each of the functional domains (ROC, COR and Kinase) of the protein product of this gene. In this study, primary fibroblasts from individuals carrying pathogenic mutations in the three central domains of LRRK2 were assessed for alterations in the autophagy/lysosomal pathway using a combination of biochemical and cellular approaches. Mutations in all three domains resulted in alterations in markers for autophagy/lysosomal function compared to wild type cells. These data highlight the autophagy and lysosomal pathways as read outs for pathogenic LRRK2 function and as a marker for disease, and provide insight into the mechanisms linking LRRK2 function and mutations.
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Affiliation(s)
- Claudia Manzoni
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Adamantios Mamais
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
- Reta Lila Weston Institute and Queen Square Brain Bank, UCL Institute of Neurology, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Sybille Dihanich
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Phillip McGoldrick
- MRC Centre for Neuromuscular Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Michael J. Devine
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Julia Zerle
- Helmholtz Zentrum München, GmbH Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
| | - Eleanna Kara
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Jan-Willem Taanman
- Department of Clinical Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Daniel G. Healy
- Beaumont Hospital, 9 Beaumont Rd, Dublin 9, Co. Dublin, Ireland
| | | | - Anthony H. Schapira
- Department of Clinical Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Helene Plun-Favreau
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Sharon Tooze
- London Research Institute, Cancer Research UK, London WC2A 3LY, UK
| | - John Hardy
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
- Reta Lila Weston Institute and Queen Square Brain Bank, UCL Institute of Neurology, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Rina Bandopadhyay
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
- Reta Lila Weston Institute and Queen Square Brain Bank, UCL Institute of Neurology, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Patrick A. Lewis
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
- School of Pharmacy, University of Reading, Whiteknights, Reading RG6 6AP, UK
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25
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McNeill A, Healy DG, Schapira AHV, Taanman JW. Glucosylceramidase degradation in fibroblasts carrying bi-allelic Parkin mutations. Mol Genet Metab 2013; 109:402-3. [PMID: 23803291 DOI: 10.1016/j.ymgme.2013.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 06/02/2013] [Indexed: 11/19/2022]
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26
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Pitceathly R, Rahman S, Wedatilake Y, Polke J, Cirak S, Foley A, Sailer A, Hurles M, Stalker J, Hargreaves I, Woodward C, Sweeney M, Muntoni F, Houlden H, Taanman JW, Hanna M. NDUFA4 Mutations Underlie Dysfunction of a Cytochrome c Oxidase Subunit Linked to Human Neurological Disease. Cell Rep 2013. [PMCID: PMC3898082 DOI: 10.1016/j.celrep.2013.06.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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27
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Pitceathly RDS, Rahman S, Wedatilake Y, Polke JM, Cirak S, Foley AR, Sailer A, Hurles ME, Stalker J, Hargreaves I, Woodward CE, Sweeney MG, Muntoni F, Houlden H, Taanman JW, Hanna MG. NDUFA4 mutations underlie dysfunction of a cytochrome c oxidase subunit linked to human neurological disease. Cell Rep 2013; 3:1795-805. [PMID: 23746447 PMCID: PMC3701321 DOI: 10.1016/j.celrep.2013.05.005] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/29/2013] [Accepted: 05/03/2013] [Indexed: 11/15/2022] Open
Abstract
The molecular basis of cytochrome c oxidase (COX, complex IV) deficiency remains genetically undetermined in many cases. Homozygosity mapping and whole-exome sequencing were performed in a consanguineous pedigree with isolated COX deficiency linked to a Leigh syndrome neurological phenotype. Unexpectedly, affected individuals harbored homozygous splice donor site mutations in NDUFA4, a gene previously assigned to encode a mitochondrial respiratory chain complex I (NADH:ubiquinone oxidoreductase) subunit. Western blot analysis of denaturing gels and immunocytochemistry revealed undetectable steady-state NDUFA4 protein levels, indicating that the mutation causes a loss-of-function effect in the homozygous state. Analysis of one- and two-dimensional blue-native polyacrylamide gels confirmed an interaction between NDUFA4 and the COX enzyme complex in control muscle, whereas the COX enzyme complex without NDUFA4 was detectable with no abnormal subassemblies in patient muscle. These observations support recent work in cell lines suggesting that NDUFA4 is an additional COX subunit and demonstrate that NDUFA4 mutations cause human disease. Our findings support reassignment of the NDUFA4 protein to complex IV and suggest that patients with unexplained COX deficiency should be screened for NDUFA4 mutations.
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Affiliation(s)
- Robert D S Pitceathly
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
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28
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Wray S, Self M, Lewis PA, Taanman JW, Ryan NS, Mahoney CJ, Liang Y, Devine MJ, Sheerin UM, Houlden H, Morris HR, Healy D, Marti-Masso JF, Preza E, Barker S, Sutherland M, Corriveau RA, D'Andrea M, Schapira AHV, Uitti RJ, Guttman M, Opala G, Jasinska-Myga B, Puschmann A, Nilsson C, Espay AJ, Slawek J, Gutmann L, Boeve BF, Boylan K, Stoessl AJ, Ross OA, Maragakis NJ, Van Gerpen J, Gerstenhaber M, Gwinn K, Dawson TM, Isacson O, Marder KS, Clark LN, Przedborski SE, Finkbeiner S, Rothstein JD, Wszolek ZK, Rossor MN, Hardy J. Creation of an open-access, mutation-defined fibroblast resource for neurological disease research. PLoS One 2012; 7:e43099. [PMID: 22952635 PMCID: PMC3428297 DOI: 10.1371/journal.pone.0043099] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 07/19/2012] [Indexed: 12/12/2022] Open
Abstract
Our understanding of the molecular mechanisms of many neurological disorders has been greatly enhanced by the discovery of mutations in genes linked to familial forms of these diseases. These have facilitated the generation of cell and animal models that can be used to understand the underlying molecular pathology. Recently, there has been a surge of interest in the use of patient-derived cells, due to the development of induced pluripotent stem cells and their subsequent differentiation into neurons and glia. Access to patient cell lines carrying the relevant mutations is a limiting factor for many centres wishing to pursue this research. We have therefore generated an open-access collection of fibroblast lines from patients carrying mutations linked to neurological disease. These cell lines have been deposited in the National Institute for Neurological Disorders and Stroke (NINDS) Repository at the Coriell Institute for Medical Research and can be requested by any research group for use in in vitro disease modelling. There are currently 71 mutation-defined cell lines available for request from a wide range of neurological disorders and this collection will be continually expanded. This represents a significant resource that will advance the use of patient cells as disease models by the scientific community.
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Affiliation(s)
- Selina Wray
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Matthew Self
- Coriell Institute for Medical Research, Camden, New Jersey, United States of America
| | - NINDS Parkinson's Disease iPSC Consortium
- For a full list of the members of the NINDS Parkinson's Disease iPSC Consortium, NINDS Huntington's Disease iPSC Consortium, and NINDS ALS iPSC Consortium please see the Acknowledgments section
| | - NINDS Huntington's Disease iPSC Consortium
- For a full list of the members of the NINDS Parkinson's Disease iPSC Consortium, NINDS Huntington's Disease iPSC Consortium, and NINDS ALS iPSC Consortium please see the Acknowledgments section
| | - NINDS ALS iPSC Consortium
- For a full list of the members of the NINDS Parkinson's Disease iPSC Consortium, NINDS Huntington's Disease iPSC Consortium, and NINDS ALS iPSC Consortium please see the Acknowledgments section
| | - Patrick A. Lewis
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Jan-Willem Taanman
- Department of Clinical Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Natalie S. Ryan
- Dementia Research Centre, Department of Neurodegenerative Diseases, University College London Institute of Neurology, London, United Kingdom
| | - Colin J. Mahoney
- Dementia Research Centre, Department of Neurodegenerative Diseases, University College London Institute of Neurology, London, United Kingdom
| | - Yuying Liang
- Dementia Research Centre, Department of Neurodegenerative Diseases, University College London Institute of Neurology, London, United Kingdom
| | - Michael J. Devine
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Una-Marie Sheerin
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Henry Houlden
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Huw R. Morris
- Cardiff University School of Medicine, University of Cardiff, Cardiff, United Kingdom
| | - Daniel Healy
- Department of Clinical Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | | | - Elisavet Preza
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Suzanne Barker
- Dementia Research Centre, Department of Neurodegenerative Diseases, University College London Institute of Neurology, London, United Kingdom
| | - Margaret Sutherland
- National Institute for Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Roderick A. Corriveau
- National Institute for Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Michael D'Andrea
- Coriell Institute for Medical Research, Camden, New Jersey, United States of America
| | - Anthony H. V. Schapira
- Department of Clinical Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Ryan J. Uitti
- Departments of Neurology and Neuroscience, Mayo Clinic Jacksonville, Jacksonville, Florida, United States of America
| | - Mark Guttman
- Department of Neurology, Center for Movement Disorders, Ontario, Canada
| | - Grzegorz Opala
- Department of Neurology, Medical University of Silesia, Katowice, Poland
| | | | | | - Christer Nilsson
- Department of Geriatric Psychiatry, Lund University, Lund, Sweden
| | - Alberto J. Espay
- Department of Neurology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Jaroslaw Slawek
- Department of Neurological and Psychiatric Nursing, Medical University of Gdansk, Gdansk, Poland
| | - Ludwig Gutmann
- Department of Neurology , West Virginia University, West Virginia, United States of America
| | - Bradley F. Boeve
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Kevin Boylan
- Departments of Neurology and Neuroscience, Mayo Clinic Jacksonville, Jacksonville, Florida, United States of America
| | - A. Jon Stoessl
- Division of Neurology, Pacific Parkinson's Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Owen A. Ross
- Departments of Neurology and Neuroscience, Mayo Clinic Jacksonville, Jacksonville, Florida, United States of America
| | - Nicholas J. Maragakis
- Department of Neurology and Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Jay Van Gerpen
- Departments of Neurology and Neuroscience, Mayo Clinic Jacksonville, Jacksonville, Florida, United States of America
| | - Melissa Gerstenhaber
- Department of Psychiatry and Behavioural Sciences, John Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Katrina Gwinn
- Baylor College of Medicine, Department of Genetics, Houston, Texas, United States of America
| | - Ted M. Dawson
- Neuroregeneration Program, Institute of Cell Engineering, Department of Neurology and the Solomon H. Snyder Department of Neuroscience, John Hopkins University, Baltimore, Maryland, United States of America
| | - Ole Isacson
- Center for Neuroregeneration Research, Harvard Medical School, Belmont, Massachusetts, United States of America
| | - Karen S. Marder
- Department of Neurology, Psychiatry, Sergievsky Center, and Taub Institute, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
| | - Lorraine N. Clark
- Department of Neurology, Psychiatry, Sergievsky Center, and Taub Institute, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
| | - Serge E. Przedborski
- Center for Motor Neuron Biology and Diseases, Departments of Neurology, Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
| | - Steven Finkbeiner
- Gladstone Institute of Neurological Disease, Taube-Koret Center for Huntington's Disease Research, Departments of Neurology and Physiology, University of California San Francisco, San Francisco, California, United States of America
| | - Jeffrey D. Rothstein
- Department of Psychiatry and Behavioural Sciences, John Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Zbigniew K. Wszolek
- Departments of Neurology and Neuroscience, Mayo Clinic Jacksonville, Jacksonville, Florida, United States of America
| | - Martin N. Rossor
- Dementia Research Centre, Department of Neurodegenerative Diseases, University College London Institute of Neurology, London, United Kingdom
| | - John Hardy
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
- * E-mail:
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Fassone E, Taanman JW, Hargreaves IP, Sebire NJ, Cleary MA, Burch M, Rahman S. Mutations in the mitochondrial complex I assembly factor NDUFAF1 cause fatal infantile hypertrophic cardiomyopathy. J Med Genet 2011; 48:691-7. [PMID: 21931170 DOI: 10.1136/jmedgenet-2011-100340] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Hypertrophic cardiomyopathy (HCM) is frequently fatal in infancy. Mitochondrial disease causing infantile HCM is characterised by extreme biochemical and genetic heterogeneity, but deficiency of respiratory chain complex I is observed relatively frequently. Identification of the precise genetic basis has prognostic implications for the likelihood of neurological involvement. OBJECTIVE The authors' objective is to report two heterozygous missense mutations in the NDUFAF1 gene as a cause of fatal infantile HCM in a patient with isolated complex I deficiency. METHODS The authors investigated a cohort of 30 paediatric patients with complex I deficiency using biochemical and genetic approaches. The patients were clinically heterogeneous; phenotypes included HCM, Leigh syndrome, other encephalomyopathies and multisystem disease. Complex I assembly was evaluated using Blue Native polyacrylamide gel electrophoresis. RESULTS Sequence analysis of NDUFAF1 revealed compound heterozygous missense mutations (c.631C>T;p.Arg211Cys and c.733G>A;p.Gly245Arg) in one patient with fatal infantile HCM. These changes were absent in 240 ethnically matched control alleles. No NDUFAF1 mutations were observed in the remaining patients. Functional studies demonstrated a severe reduction in NDUFAF1 protein in Western blots of patient fibroblasts and accumulation of abnormal complex I assembly intermediates on Blue Native polyacrylamide gel electrophoresis. CONCLUSIONS The authors report a case of fatal infantile HCM caused by missense mutations in NDUFAF1 associated with complex I misassembly. Establishing a genetic diagnosis in mitochondrial cardiomyopathy is challenging and achieved in only a minority of cases because of complex genetics. A precise genetic diagnosis is important to provide accurate prognostic and genetic counselling advice regarding recurrence risks and to guide future reproductive options.
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Affiliation(s)
- Elisa Fassone
- Clinical and Molecular Genetics Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
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Devine MJ, Ryten M, Vodicka P, Thomson AJ, Burdon T, Houlden H, Cavaleri F, Nagano M, Drummond NJ, Taanman JW, Schapira AH, Gwinn K, Hardy J, Lewis PA, Kunath T. Parkinson's disease induced pluripotent stem cells with triplication of the α-synuclein locus. Nat Commun 2011; 2:440. [PMID: 21863007 PMCID: PMC3265381 DOI: 10.1038/ncomms1453] [Citation(s) in RCA: 349] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 07/22/2011] [Indexed: 12/18/2022] Open
Abstract
A major barrier to research on Parkinson's disease is inaccessibility of diseased tissue for study. One solution is to derive induced pluripotent stem cells from patients and differentiate them into neurons affected by disease. Triplication of SNCA, encoding α-synuclein, causes a fully penetrant, aggressive form of Parkinson's disease with dementia. α-Synuclein dysfunction is the critical pathogenic event in Parkinson's disease, multiple system atrophy and dementia with Lewy bodies. Here we produce multiple induced pluripotent stem cell lines from an SNCA triplication patient and an unaffected first-degree relative. When these cells are differentiated into midbrain dopaminergic neurons, those from the patient produce double the amount of α-synuclein protein as neurons from the unaffected relative, precisely recapitulating the cause of Parkinson's disease in these individuals. This model represents a new experimental system to identify compounds that reduce levels of α-synuclein, and to investigate the mechanistic basis of neurodegeneration caused by α-synuclein dysfunction. Pluripotent stem cells can be generated from the somatic cells of humans and are a useful model to study disease. Here, pluripotent stem cells are made from a patient with familial Parkinson's disease, and the resulting neurons exhibit elevated levels of α-synuclein, recapitulating the molecular features of the patient's disease.
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Affiliation(s)
- Michael J Devine
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, University of Edinburgh, Edinburgh EH9 3JQ, UK.
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31
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Devine MJ, Kaganovich A, Ryten M, Mamais A, Trabzuni D, Manzoni C, McGoldrick P, Chan D, Dillman A, Zerle J, Horan S, Taanman JW, Hardy J, Marti-Masso JF, Healey D, Schapira AH, Wolozin B, Bandopadhyay R, Cookson MR, van der Brug MP, Lewis PA. Pathogenic LRRK2 mutations do not alter gene expression in cell model systems or human brain tissue. PLoS One 2011; 6:e22489. [PMID: 21799870 PMCID: PMC3142158 DOI: 10.1371/journal.pone.0022489] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 06/28/2011] [Indexed: 11/19/2022] Open
Abstract
Point mutations in LRRK2 cause autosomal dominant Parkinson's disease. Despite extensive efforts to determine the mechanism of cell death in patients with LRRK2 mutations, the aetiology of LRRK2 PD is not well understood. To examine possible alterations in gene expression linked to the presence of LRRK2 mutations, we carried out a case versus control analysis of global gene expression in three systems: fibroblasts isolated from LRRK2 mutation carriers and healthy, non-mutation carrying controls; brain tissue from G2019S mutation carriers and controls; and HEK293 inducible LRRK2 wild type and mutant cell lines. No significant alteration in gene expression was found in these systems following correction for multiple testing. These data suggest that any alterations in basal gene expression in fibroblasts or cell lines containing mutations in LRRK2 are likely to be quantitatively small. This work suggests that LRRK2 is unlikely to play a direct role in modulation of gene expression, although it remains possible that this protein can influence mRNA expression under pathogenic cicumstances.
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Affiliation(s)
- Michael J. Devine
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, United Kingdom
| | - Alice Kaganovich
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mina Ryten
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, United Kingdom
| | - Adamantios Mamais
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, United Kingdom
- Rita Lila Weston Institute and Queen Square Brain Bank, UCL Institute of Neurology, London, United Kingdom
| | - Daniah Trabzuni
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, United Kingdom
| | - Claudia Manzoni
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, United Kingdom
| | - Philip McGoldrick
- MRC Centre for Neuromuscular Disease, UCL Institute of Neurology, London, United Kingdom
| | - Diane Chan
- Department of Pharmacology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Allissa Dillman
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Julia Zerle
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, United Kingdom
| | - Susannah Horan
- Department of Clinical Neuroscience, UCL Institute of Neurology, London, United Kingdom
| | - Jan-Willem Taanman
- Department of Clinical Neuroscience, UCL Institute of Neurology, London, United Kingdom
| | - John Hardy
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, United Kingdom
| | | | - Daniel Healey
- Department of Clinical Neuroscience, UCL Institute of Neurology, London, United Kingdom
| | - Anthony H. Schapira
- Department of Clinical Neuroscience, UCL Institute of Neurology, London, United Kingdom
| | - Benjamin Wolozin
- Department of Pharmacology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Rina Bandopadhyay
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, United Kingdom
- Rita Lila Weston Institute and Queen Square Brain Bank, UCL Institute of Neurology, London, United Kingdom
| | - Mark R. Cookson
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Marcel P. van der Brug
- The Scripps Research Institute, Jupiter, Florida, United States of America
- * E-mail: (MPvdB); (PAL)
| | - Patrick A. Lewis
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, United Kingdom
- * E-mail: (MPvdB); (PAL)
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Pitceathly RDS, Fassone E, Taanman JW, Sadowski M, Fratter C, Mudanohwo EE, Woodward CE, Sweeney MG, Holton JL, Hanna MG, Rahman S. Kearns-Sayre syndrome caused by defective R1/p53R2 assembly. J Med Genet 2011; 48:610-7. [PMID: 21378381 DOI: 10.1136/jmg.2010.088328] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Mutations in RRM2B encoding ribonucleotide reductase (RNR) p53R2 subunit usually cause paediatric-onset mitochondrial disease associated with mitochondrial DNA (mtDNA) depletion. The importance of RNR dysfunction in adult mitochondrial disease is unclear. OBJECTIVE To report the RRM2B mutation frequency in adults with multiple mtDNA deletions and examine RNR assembly in a patient with Kearns-Sayre syndrome (KSS) caused by two novel RRM2B mutations. METHODS 50 adult patients with multiple mtDNA deletions in skeletal muscle were studied. DNA sequencing of RRM2B was performed in patients without mutations in mtDNA maintenance genes POLG and C10orf2. RNR protein was studied using western blot and Blue-native polyacrylamide gel electrophoresis (BN-PAGE). RESULTS Four per cent (two unrelated cases) of this adult cohort harboured RRM2B mutations. Patient 1 had KSS and two novel missense mutations: c.122G→A; p.Arg41Gln and c.391G→A; p.Glu131Lys. BN-PAGE demonstrated reduced heterotetrameric R1/p53R2 RNR levels compared with controls, despite normal steady-state p53R2 levels on western blot, suggesting failed assembly of functional RNR as a potential disease mechanism. Patient 2 had late-onset progressive external ophthalmoplegia and fatigue. A heterozygous deletion c.253_255delGAG; p.Glu85del was identified. Muscle histology in both cases showed significant numbers of necrotic muscle fibres, possibly indicating enhanced apoptotic cell death. CONCLUSION These data indicate that 4% of adult mitochondrial disease with multiple deletions is caused by RNR dysfunction. KSS has not previously been linked to a nuclear gene defect. Evidence that disease pathogenesis may be caused by defective RNR assembly is given. RRM2B screening should be considered early in the differential diagnosis of adults with multiple mtDNA deletions.
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Affiliation(s)
- Robert D S Pitceathly
- 1MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
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Gegg ME, Cooper JM, Chau KY, Rojo M, Schapira AHV, Taanman JW. Mitofusin 1 and mitofusin 2 are ubiquitinated in a PINK1/parkin-dependent manner upon induction of mitophagy. Hum Mol Genet 2010; 19:4861-70. [PMID: 20871098 PMCID: PMC3583518 DOI: 10.1093/hmg/ddq419] [Citation(s) in RCA: 672] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 09/20/2010] [Accepted: 09/20/2010] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial dysfunction and perturbed degradation of proteins have been implicated in Parkinson's disease (PD) pathogenesis. Mutations in the Parkin and PINK1 genes are a cause of familial PD. PINK1 is a putative kinase associated with mitochondria, and loss of PINK1 expression leads to mitochondrial dysfunction, which increases with time. Parkin is suggested to be downstream of PINK1 and also mediates the removal of damaged mitochondria by macroautophagy (mitophagy). We investigated whether mitochondrial dysfunction in dopaminergic SH-SY5Y cells following decreased PINK1 expression by RNAi may in part be due to the inhibition of mitophagy. Reduced flux through the macroautophagy pathway was found to be coincident with the inhibition of ATP synthesis following 12 days of PINK1 silencing. Overexpression of parkin in these cells restored both autophagic flux and ATP synthesis. Overexpression and RNAi studies also indicated that PINK1 and parkin were required for mitophagy following CCCP-induced mitochondrial damage. The ubiquitination of several mitochondrial proteins, including mitofusin 1 and mitofusin 2, were detected within 3 h of CCCP treatment. These post-translational modifications were reduced following the silencing of parkin or PINK1. The ubiquitination of mitochondrial proteins appears to identify mitochondria for degradation and facilitate mitophagy. PINK1 and parkin are thus required for the removal of damaged mitochondria in dopaminergic cells, and inhibition of this pathway may lead to the accumulation of defective mitochondria which may contribute to PD pathogenesis.
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Affiliation(s)
- Matthew E Gegg
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London, UK.
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Hernandez MA, Schulz R, Chaplin T, Young BD, Perrett D, Champion MP, Taanman JW, Fensom A, Marinaki AM. The diagnosis of inherited metabolic diseases by microarray gene expression profiling. Orphanet J Rare Dis 2010; 5:34. [PMID: 21122112 PMCID: PMC3009951 DOI: 10.1186/1750-1172-5-34] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 12/01/2010] [Indexed: 02/04/2023] Open
Abstract
Background Inherited metabolic diseases (IMDs) comprise a diverse group of generally progressive genetic metabolic disorders of variable clinical presentations and severity. We have undertaken a study using microarray gene expression profiling of cultured fibroblasts to investigate 68 patients with a broad range of suspected metabolic disorders, including defects of lysosomal, mitochondrial, peroxisomal, fatty acid, carbohydrate, amino acid, molybdenum cofactor, and purine and pyrimidine metabolism. We aimed to define gene expression signatures characteristic of defective metabolic pathways. Methods Total mRNA extracted from cultured fibroblast cell lines was hybridized to Affymetrix U133 Plus 2.0 arrays. Expression data was analyzed for the presence of a gene expression signature characteristic of an inherited metabolic disorder and for genes expressing significantly decreased levels of mRNA. Results No characteristic signatures were found. However, in 16% of cases, disease-associated nonsense and frameshift mutations generating premature termination codons resulted in significantly decreased mRNA expression of the defective gene. The microarray assay detected these changes with high sensitivity and specificity. Conclusion In patients with a suspected familial metabolic disorder where initial screening tests have proven uninformative, microarray gene expression profiling may contribute significantly to the identification of the genetic defect, shortcutting the diagnostic cascade.
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Fassone E, Duncan AJ, Taanman JW, Pagnamenta AT, Sadowski MI, Holand T, Qasim W, Rutland P, Calvo SE, Mootha VK, Bitner-Glindzicz M, Rahman S. FOXRED1, encoding an FAD-dependent oxidoreductase complex-I-specific molecular chaperone, is mutated in infantile-onset mitochondrial encephalopathy. Hum Mol Genet 2010; 19:4837-47. [PMID: 20858599 DOI: 10.1093/hmg/ddq414] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Complex I is the first and largest enzyme in the respiratory chain and is located in the inner mitochondrial membrane. Complex I deficiency is the most commonly reported mitochondrial disorder presenting in childhood, but the molecular basis of most cases remains elusive. We describe a patient with complex I deficiency caused by mutation of the molecular chaperone FOXRED1. A combined homozygosity mapping and bioinformatics approach in a consanguineous Iranian-Jewish pedigree led to the identification of a homozygous mutation in FOXRED1 in a child who presented with infantile-onset encephalomyopathy. Silencing of FOXRED1 in human fibroblasts resulted in reduced complex I steady-state levels and activity, while lentiviral-mediated FOXRED1 transgene expression rescued complex I deficiency in the patient fibroblasts. This FAD-dependent oxidoreductase, which has never previously been associated with human disease, is now shown to be a complex I-specific molecular chaperone. The discovery of the c.1054C>T; p.R352W mutation in the FOXRED1 gene is a further contribution towards resolving the complex puzzle of the genetic basis of human mitochondrial disease.
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Affiliation(s)
- Elisa Fassone
- Clinical and Molecular Genetics Unit, UCL Institute of Child Health, London WC1N 1EH, UK
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Sagar J, Sales K, Taanman JW, Dijk S, Winslet M. Lowering the apoptotic threshold in colorectal cancer cells by targeting mitochondria. Cancer Cell Int 2010; 10:31. [PMID: 20819205 PMCID: PMC2940783 DOI: 10.1186/1475-2867-10-31] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Accepted: 09/06/2010] [Indexed: 11/16/2022] Open
Abstract
Background Colorectal cancer is the third most-common cancer and the second most-common cause of cancer related death in UK. Although chemotherapy plays significant role in the treatment of colorectal cancer, morbidity and mortality due to drug resistance and cancer metastasis are yet to be eliminated. Recently, doxycycline has been reported to have cytotoxic and anti-proliferating properties in various cancer cells. In this study, whether doxycycline was apoptosis threshold lowering agent in colorectal cancer cells by targeting mitochondria was answered. Results This study showed dose-dependent cytotoxic effects of cisplatin, oxaliplatin and doxycycline in HT29 colorectal cancer cells. Doxycycline showed inhibition of cytochrome-c-oxidase activity in these cells over a time-period. The pre-treatment of doxycycline reported statistically significant increased cytotoxicity of cisplatin and oxaliplatin compared to cisplatin and oxaliplatin alone. The caspase studies revealed significantly less expression and activity of caspase 3 in HT29 cells pre-treated with doxycycline compared to the cells treated with cisplatin and oxaliplatin alone. Conclusions It was concluded that doxycycline lowered the apoptotic threshold in HT 29 cells by targeting mitochondria. This also raised possible caspase-independent mechanisms of apoptosis in HT29 cells when pre-treated with doxycycline however this needs further research work.
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Affiliation(s)
- Jayesh Sagar
- Division of Surgery and Interventional Science, University College London, Gower Street, London, WC1E 6BT, UK.,Academic Department of Surgery, Royal Free & University College Medical School, Pond Street, London, NW3 2QG, UK
| | - Kevin Sales
- Division of Surgery and Interventional Science, University College London, Gower Street, London, WC1E 6BT, UK
| | - Jan-Willem Taanman
- Department of Clinical Neuroscience, Royal Free & University College Medical School, Pond Street, London, NW3 2QG, UK
| | - Sas Dijk
- Division of Surgery and Interventional Science, University College London, Gower Street, London, WC1E 6BT, UK
| | - Marc Winslet
- Division of Surgery and Interventional Science, University College London, Gower Street, London, WC1E 6BT, UK.,Academic Department of Surgery, Royal Free & University College Medical School, Pond Street, London, NW3 2QG, UK
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Ruhanen H, Borrie S, Szabadkai G, Tyynismaa H, Jones AW, Kang D, Taanman JW, Yasukawa T. Mitochondrial single-stranded DNA binding protein is required for maintenance of mitochondrial DNA and 7S DNA but is not required for mitochondrial nucleoid organisation. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2010; 1803:931-9. [DOI: 10.1016/j.bbamcr.2010.04.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 03/31/2010] [Accepted: 04/20/2010] [Indexed: 01/19/2023]
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Hafez TS, Glantzounis GK, Fusai G, Taanman JW, Wignarajah P, Parkes H, Fuller B, Davidson BR, Seifalian AM. Intracellular oxygenation and cytochrome oxidase C activity in ischemic preconditioning of steatotic rabbit liver. Am J Surg 2010; 200:507-18. [PMID: 20409534 DOI: 10.1016/j.amjsurg.2009.09.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2009] [Revised: 09/30/2009] [Accepted: 09/30/2009] [Indexed: 01/22/2023]
Abstract
BACKGROUND Mild to moderate steatotic livers are used as marginal donors in liver transplantation. Very little is known about the mechanisms of ischemia reperfusion (IR) injury (IRI) in fatty liver. This study aimed to establish whether cytochrome oxidase C (COX) activity is compromised by IRI in fatty liver and whether ischemic preconditioning (IPC) can protect COX activity. METHODS New Zealand rabbits were fed on a high-cholesterol diet for 8 weeks to induce moderate hepatic steatosis. Three groups were tested. The IR group underwent 60 minutes of ischemia, followed by 7 hours of reperfusion. The IPC group (IPC + IR) underwent 5 minutes of ischemia, followed by 10 minutes of reperfusion and then 60 minutes of ischemia and 7 hours of reperfusion. The control group (sham) underwent the same surgical procedure, but ischemia was not induced. Deoxyhemoglobin, oxyhemoglobin, and change in the redox state of COX was continuously monitored in vivo by near-infrared spectroscopy. COX and citrate synthase (CS) activity assays were carried out on liver biopsy specimens in vitro. Bile was collected continuously during the procedure and analyzed using proton nuclear magnetic resonance spectroscopy. RESULTS The IR group had decreased COX activity and tissue oxygenation represented by deoxyhemoglobin, oxyhemoglobin, COX, and elevated redox ratios of lactate/pyruvate and β-hydroxybutarate/acetoacetate in vivo and a decrease in COX and CS activity in vitro. The IPC + IR group showed higher levels of all measured parameters in vivo and showed a smaller decrease in COX and CS activity in vitro. CONCLUSION This study shows that IRI affects COX activity in fatty livers. This is attenuated by IPC.
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Affiliation(s)
- Tariq S Hafez
- UCL Division of Surgery and Interventional Science, University College London, London, United Kingdom
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Taanman JW, Heiske M, Letellier T. Measurement of kinetic parameters of human platelet DNA polymerase gamma. Methods 2010; 51:374-8. [PMID: 20227504 DOI: 10.1016/j.ymeth.2010.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 03/07/2010] [Accepted: 03/09/2010] [Indexed: 11/18/2022] Open
Abstract
Synthesis of mitochondrial DNA is performed by DNA polymerase gamma. Mutations in POLG, the gene encoding the catalytic subunit of DNA polymerase gamma, are a major cause of neurological disease. A large proportion of patients carry rare nucleotide substitutions leading to single amino acid changes. Confirming that these replacements are pathogenic can be problematic without biochemical evidence. Here, we provide a hands-on protocol for an in vitro kinetic assay of DNA polymerase gamma which allows assessment of the K(m) and V(max) for the incoming nucleotide of the polymerization reaction. To avoid measurement of contaminating nuclear DNA polymerases, platelet extracts are used since platelets do not contain a nucleus. Moreover, platelets have the advantage of being obtainable relatively non-invasively. Polymerization activity is determined by measurement of the incorporation of radioactive thymidine 5'-triphosphate (dTTP) on the homopolymeric RNA substrate poly(rA).oligo(dT)(12-18). To further minimize nuclear DNA polymerase activity, aphidicolin, an inhibitor of most nuclear DNA polymerases, is included in the reaction. In addition, reactions are carried out in the absence and presence of the competitive inhibitor of DNA polymerase gamma, 2',3'-dideoxythymidine 5'-triphosphate (ddTTP), to allow calculation of the ddTTP-sensitive incorporation. With this method, platelets from healthy control subjects extracted with 3% Triton X-100 showed a K(m) for dTTP of 1.42 microM and a V(max) of 0.83 pmol min(-1)mg(-1).
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Affiliation(s)
- Jan-Willem Taanman
- Department of Clinical Neurosciences, Institute of Neurology, University College London, Rowland Hill Street, London NW3 2PF, United Kingdom.
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Wolf NI, Rahman S, Schmitt B, Taanman JW, Duncan AJ, Harting I, Wohlrab G, Ebinger F, Rating D, Bast T. Status epilepticus in children with Alpers’ disease caused byPOLG1mutations: EEG and MRI features. Epilepsia 2009; 50:1596-607. [DOI: 10.1111/j.1528-1167.2008.01877.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bradley LJ, Taanman JW, Kallis C, Orrell RW. Increased sensitivity of myoblasts to oxidative stress in amyotrophic lateral sclerosis peripheral tissues. Exp Neurol 2009; 218:92-7. [PMID: 19379740 DOI: 10.1016/j.expneurol.2009.04.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 04/07/2009] [Accepted: 04/09/2009] [Indexed: 12/12/2022]
Abstract
We compared mitochondrial respiratory chain function, mitochondrial DNA (mtDNA) integrity, and oxidative stress levels in muscle, myoblasts, fibroblasts and cybrids, from 12 amyotrophic lateral sclerosis (ALS) patients with 28 control samples. Mitochondrial respiratory chain enzyme activities were normal in muscle, myoblast and fibroblast cultures from ALS patients, as were levels of mtDNA in muscle. Rearranged muscle mtDNA species were not detected by Southern blot hybridization in any of the samples and no difference was found in the number of deleted mtDNA species detected by long-range PCR. Platelet-derived cybrid studies confirmed the absence of a systemic mtDNA abnormality. Aconitase activity measurements did not indicate increased oxidative damage in muscle tissue, or in myoblasts or fibroblasts from ALS patients cultured under basal conditions. We did, however, find an increased sensitivity to oxidative stress in myoblasts from ALS patients exposed to paraquat. This altered sensitivity appears to be due to a nuclear rather than a mtDNA abnormality. Motor neurons have a large relative size and metabolic activity, and would be expected to be exposed to a greater degree of oxidative stress than most tissues throughout life. In addition, neurons are postmitotic cells, with poor regenerative potential. We do not have a ready method to study this in neural tissue of living patients, but the oxidative stress identified in myoblasts would translate into oxidative damage more readily in motor neurons than in other tissues.
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Affiliation(s)
- Lloyd J Bradley
- Department of Clinical Neurosciences, Institute of Neurology, University College London, Rowland Hill Street, London NW3 2PF, England, UK
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42
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Taanman JW, Rahman S, Pagnamenta AT, Morris AAM, Bitner-Glindzicz M, Wolf NI, Leonard JV, Clayton PT, Schapira AHV. Analysis of mutant DNA polymerase gamma in patients with mitochondrial DNA depletion. Hum Mutat 2009; 30:248-54. [PMID: 18828154 DOI: 10.1002/humu.20852] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We studied six unrelated children with depletion of mitochondrial DNA (mtDNA). They presented with Leigh syndrome, infantile hepatocerebral mtDNA depletion syndrome, or Alpers-Huttenlocher syndrome. Several genes have been implicated in mtDNA depletion. Screening of candidate genes indicated that all six patients were compound heterozygous for missense mutations in the gene for the catalytic subunit of DNA polymerase gamma (POLG). Three of the identified mutations, c.3328C>T (p.H1110Y), c.3401A>G (p.H1134R), and c.3406G>A (p.E1136K), have not been reported earlier. To investigate the functional consequences of the mutations, we carried out a series of biochemical assays in cultured fibroblasts. These studies revealed that fibroblast cultures from the patients with infantile hepatocerebral mtDNA depletion syndrome progressively lost their mtDNA during culturing, whereas fibroblast cultures from patients presenting with Leigh syndrome or Alpers-Huttenlocher syndrome had reduced but stable levels of mtDNA. DNA polymerase gamma activity was below the normal range in all patient cultures, except for one; however, this culture showed low levels of the heterodimeric enzyme and poor DNA polymerase gamma processivity. Parental fibroblast cultures had normal catalytic efficiency of DNA polymerase gamma, consistent with the observation that all carriers are asymptomatic. Thus, we report the first patient with Leigh syndrome caused by POLG mutations. The cell culture experiments established the pathogenicity of the identified POLG mutations and helped to define the molecular mechanisms responsible for mtDNA depletion in the patients' tissues. The assays may facilitate the identification of those patients in whom screening for POLG mutations would be most appropriate.
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Affiliation(s)
- Jan-Willem Taanman
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London, United Kingdom.
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Gegg ME, Cooper JM, Schapira AHV, Taanman JW. Silencing of PINK1 expression affects mitochondrial DNA and oxidative phosphorylation in dopaminergic cells. PLoS One 2009; 4:e4756. [PMID: 19270741 PMCID: PMC2649444 DOI: 10.1371/journal.pone.0004756] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Accepted: 02/08/2009] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Mitochondrial dysfunction has been implicated in the pathogenesis of Parkinson's disease (PD). Impairment of the mitochondrial electron transport chain (ETC) and an increased frequency in deletions of mitochondrial DNA (mtDNA), which encodes some of the subunits of the ETC, have been reported in the substantia nigra of PD brains. The identification of mutations in the PINK1 gene, which cause an autosomal recessive form of PD, has supported mitochondrial involvement in PD. The PINK1 protein is a serine/threonine kinase localized in mitochondria and the cytosol. Its precise function is unknown, but it is involved in neuroprotection against a variety of stress signalling pathways. METHODOLOGY/PRINCIPAL FINDINGS In this report we have investigated the effect of silencing PINK1 expression in human dopaminergic SH-SY5Y cells by siRNA on mtDNA synthesis and ETC function. Loss of PINK1 expression resulted in a decrease in mtDNA levels and mtDNA synthesis. We also report a concomitant loss of mitochondrial membrane potential and decreased mitochondrial ATP synthesis, with the activity of complex IV of the ETC most affected. This mitochondrial dysfunction resulted in increased markers of oxidative stress under basal conditions and increased cell death following treatment with the free radical generator paraquat. CONCLUSIONS This report highlights a novel function of PINK1 in mitochondrial biogenesis and a role in maintaining mitochondrial ETC activity. Dysfunction of both has been implicated in sporadic forms of PD suggesting that these may be key pathways in the development of the disease.
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Affiliation(s)
- Matthew E. Gegg
- Department of Clinical Neurosciences, Institute of Neurology, University College London, Queen Square, London, United Kingdom
| | - J. Mark Cooper
- Department of Clinical Neurosciences, Institute of Neurology, University College London, Queen Square, London, United Kingdom
| | - Anthony H. V. Schapira
- Department of Clinical Neurosciences, Institute of Neurology, University College London, Queen Square, London, United Kingdom
| | - Jan-Willem Taanman
- Department of Clinical Neurosciences, Institute of Neurology, University College London, Queen Square, London, United Kingdom
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Sagar J, Sales K, Dijk S, Taanman J, Seifalian A, Winslet M. Does doxycycline work in synergy with cisplatin and oxaliplatin in colorectal cancer? World J Surg Oncol 2009; 7:2. [PMID: 19126215 PMCID: PMC2628910 DOI: 10.1186/1477-7819-7-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Accepted: 01/06/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In recent years, apart from antibacterial properties, doxycycline is reported to have cytotoxic and anti-proliferative actions in various cancers including colorectal cancer. Colorectal cancer constitutes one of the most common cancers in the western population. Apart from surgery, chemotherapy plays crucial role in the treatment of colorectal cancer. Cisplatin and oxaliplatin are most commonly used platinum compounds for the cancer chemotherapy. This study has looked for any impact of doxycycline on the cytotoxic effects of platinum compounds in colorectal cancer including its mechanisms of actions. METHODS HT 29 colorectal cancer cells were used for this study. These cells were treated with cisplatin and oxaliplatin with or without doxycycline treatment. The caspase 3 gene expression was quantitated by gel electrophoresis and qualitated by real time polymerase chain reactions. The caspase 3 activity was assessed in HT 29 cells with fluorescence kit. RESULTS The results revealed increased caspase 3 gene expressions and activities in HT 29 cells treated with cisplatin, oxaliplatin and doxycycline; however the combination of doxycycline with cisplatin and oxaliplatin did not report increased caspase 3 gene expressions and activity compared to cisplatin and oxaliplatin alone. CONCLUSION We concluded that doxycycline has role in apoptosis induction in the colorectal cancer. However, it did not show any synergy with platinum compounds in the colorectal cancer cells. This study also pointed towards possible caspase-independent actions of doxycycline with cisplatin and oxaliplatin. However, further work is required to underpin the mechanisms of actions of doxycycline.
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Affiliation(s)
- Jayesh Sagar
- Division of Surgery and Interventional Science, University College London, Gower Street, London, WC1E 6BT, UK.
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Taanman JW, Daras M, Albrecht J, Davie CA, Mallam EA, Muddle JR, Weatherall M, Warner TT, Schapira AHV, Ginsberg L. Characterization of a novel TYMP splice site mutation associated with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). Neuromuscul Disord 2008; 19:151-4. [PMID: 19056268 DOI: 10.1016/j.nmd.2008.11.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 10/20/2008] [Accepted: 11/03/2008] [Indexed: 12/13/2022]
Abstract
Mitochondrial neurogastrointestinal encephalomyopathy is an autosomal recessive disorder caused by loss-of-function mutations in the thymidine phosphorylase gene (TYMP). We report here a patient compound heterozygous for two TYMP mutations: a novel g.4009G>A transition affecting the consensus splice donor site of intron 9, and a previously reported g.675G>C splice site mutation. The novel mutation causes exon 9 skipping but leaves the reading frame intact; however, TYMP protein was not detected by immunoblot analysis, suggesting that neither mutant allele is expressed as protein. The patient's fibroblasts showed gradual loss of the mitochondrial DNA-encoded subunit I of cytochrome-c oxidase, suggesting a progressive mitochondrial DNA defect in culture.
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Affiliation(s)
- Jan-Willem Taanman
- Department of Clinical Neurosciences, Institute of Neurology, University College London, Rowland Hill Street, London, United Kingdom.
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Misbahuddin A, Placzek M, Lennox G, Taanman JW, Warner TT. Myoclonus-dystonia syndrome with severe depression is caused by an exon-skipping mutation in the epsilon-sarcoglycan gene. Mov Disord 2007; 22:1173-5. [PMID: 17230465 DOI: 10.1002/mds.21297] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We describe two affected individuals in a family with myoclonus-dystonia syndrome complicated with severe depression. One individual committed suicide. Molecular genetic analysis revealed a heterozygous point mutation in the epsilon-sarcoglycan gene, which we show leads to skipping of exon 5. This report suggests that the psychiatric spectrum of MDS includes more severe depression.
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Affiliation(s)
- Anjum Misbahuddin
- Department of Clinical Neurosciences, Royal Free and University College Medical School, London, UK
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47
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Mousson de Camaret B, Taanman JW, Padet S, Chassagne M, Mayençon M, Clerc-Renaud P, Mandon G, Zabot MT, Lachaux A, Bozon D. Kinetic properties of mutant deoxyguanosine kinase in a case of reversible hepatic mtDNA depletion. Biochem J 2007; 402:377-85. [PMID: 17073823 PMCID: PMC1798436 DOI: 10.1042/bj20060705] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
DGUOK [dG (deoxyguanosine) kinase] is one of the two mitochondrial deoxynucleoside salvage pathway enzymes involved in precursor synthesis for mtDNA (mitochondrial DNA) replication. DGUOK is responsible for the initial rate-limiting phosphorylation of the purine deoxynucleosides, using a nucleoside triphosphate as phosphate donor. Mutations in the DGUOK gene are associated with the hepato-specific and hepatocerebral forms of MDS (mtDNA depletion syndrome). We identified two missense mutations (N46S and L266R) in the DGUOK gene of a previously reported child, now 10 years old, who presented with an unusual revertant phenotype of liver MDS. The kinetic properties of normal and mutant DGUOK were studied in mitochondrial preparations from cultured skin fibroblasts, using an optimized methodology. The N46S/L266R DGUOK showed 14 and 10% residual activity as compared with controls with dG and deoxyadenosine as phosphate acceptors respectively. Similar apparent negative co-operativity in the binding of the phosphate acceptors to the wild-type enzyme was found for the mutant. In contrast, abnormal bimodal kinetics were shown with ATP as the phosphate donor, suggesting an impairment of the ATP binding mode at the phosphate donor site. No kinetic behaviours were found for two other patients with splicing defects or premature stop codon. The present study represents the first characterization of the enzymatic kinetic properties of normal and mutant DGUOK in organello and our optimized protocol allowed us to demonstrate a residual activity in skin fibroblast mitochondria from a patient with a revertant phenotype of MDS. The residual DGUOK activity may play a crucial role in the phenotype reversal.
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48
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Affiliation(s)
- Lionel Ginsberg
- University Department of Clinical Neurosciences, Hampstead Campus, Royal Free and University College Medical School, University College London, UK.
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Pagnamenta AT, Hargreaves IP, Duncan AJ, Taanman JW, Heales SJ, Land JM, Bitner-Glindzicz M, Leonard JV, Rahman S. Phenotypic variability of mitochondrial disease caused by a nuclear mutation in complex II. Mol Genet Metab 2006; 89:214-21. [PMID: 16798039 DOI: 10.1016/j.ymgme.2006.05.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 05/09/2006] [Accepted: 05/09/2006] [Indexed: 01/18/2023]
Abstract
We report a patient with relatively mild Leigh syndrome and mitochondrial respiratory chain complex II deficiency caused by a homozygous G555E mutation in the nuclear encoded flavoprotein subunit of succinate dehydrogenase. This mutation has previously been reported in a lethal-infantile presentation of complex II deficiency. Such marked phenotypic heterogeneity, although typical of heteroplasmic mutations in the mitochondrial genome, is unusual for nuclear mutations. Comparable activities and stability of mitochondrial respiratory chain enzymes were demonstrated in both patients, so other reasons for the phenotypic variability are considered.
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Affiliation(s)
- Alistair T Pagnamenta
- Biochemistry, Endocrinology and Metabolism Unit, Institute of Child Health, University College London, UK
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Pagnamenta AT, Taanman JW, Wilson CJ, Anderson NE, Marotta R, Duncan AJ, Bitner-Glindzicz M, Taylor RW, Laskowski A, Thorburn DR, Rahman S. Dominant inheritance of premature ovarian failure associated with mutant mitochondrial DNA polymerase gamma. Hum Reprod 2006; 21:2467-73. [PMID: 16595552 DOI: 10.1093/humrep/del076] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Premature ovarian failure (POF) results in menopause before the age of 40. Recently, mutations in the catalytic subunit of mitochondrial DNA polymerase gamma (POLG) were shown to segregate with POF in families with progressive external ophthalmoplegia (PEO) and multiple large-scale rearrangements of mitochondrial DNA (mtDNA). METHODS AND RESULTS A patient, mother and maternal grandmother are described, all presenting with POF and PEO. The mother developed parkinsonism in her sixth decade. Normal mtDNA sequence excluded mitochondrial inheritance. Sequence analysis of polymerase gamma revealed a dominant Y955C mutation that segregated with disease. Southern blot analysis demonstrated mtDNA depletion in fibroblasts (43% of controls). In contrast, multiple rearrangements of mtDNA were seen in skeletal muscle, consistent with the relative sparing of nuclear-encoded complex II activity compared with other respiratory chain enzymes. Immunoblotting of native gels showed that DNA polymerase gamma stability was not affected, whereas a reverse-transcriptase primer-extension assay suggested a trend towards reduced polymerase activity in fibroblasts. CONCLUSIONS This study confirms that POLG mutations can segregate with POF and parkinsonism and demonstrates for the first time that the Y955C mutation can lead to mtDNA depletion. Future screening projects will determine the frequency with which POLG is involved in the aetiology of POF and its impact on reproductive counselling.
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Affiliation(s)
- Alistair T Pagnamenta
- Biochemistry, Endocrinology and Metabolism Unit, Institute of Child Health, London, WC1N 1EH, UK
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