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Li X, Shang J, Li S, Wang Y. Identification of a Novel Mitochondrial tRNA Mutation in Chinese Family with Type 2 Diabetes Mellitus. Pharmgenomics Pers Med 2024; 17:149-161. [PMID: 38645701 PMCID: PMC11032666 DOI: 10.2147/pgpm.s438978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Accepted: 01/29/2024] [Indexed: 04/23/2024] Open
Abstract
Background Mutations in mitochondrial tRNA (mt-tRNA) could be the origin of some type 2 diabetes mellitus (T2DM) cases, but the mechanism remained largely unknown. Aim The aim of this study was to assess the impact of a novel mitochondrial tRNACys/tRNATyr A5826G mutation on the development and progression of T2DM. Methods A four-generation Han Chinese family with maternally inherited diabetes underwent clinical, genetic and biochemical analyses. The mitochondrial DNA (mtDNA) mutations of three matrilineal relatives were screened by PCR-Sanger sequencing. Furthermore, to see whether m.A5826G mutations affected mitochondrial functions, the cybrid cell lines were derived from three subjects with m.A5826G mutation and three controls without this mutation. ATP was evaluated by luminescent cell viability assay, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) were determined by flow cytometry. The student's two-tailed, unpaired t-test was used to assess the statistical significance between the control and mutant results. Results The age at onset of diabetes in this pedigree varied from 40 to 63 years, with an average of 54 years. Mutational analysis of mitochondrial genomes revealed the presence of a novel m.A5826G mutation. Interestingly, the m.A5826G mutation occurred at the conjunction between tRNACys and tRNATyr, a very conserved position that was critical for tRNAs processing and functions. Using trans-mitochondrial cybrid cells, we found that mutant cells carrying the m.A5826G showed approximately 36.5% and 22.4% reductions in ATP and MMP, respectively. By contrast, mitochondrial ROS levels increased approximately 33.3%, as compared with the wild type cells. Conclusion A novel m.A5826G mutation was identified in a pedigree with T2DM, and this mutation would lead to mitochondrial dysfunction. Thus, the genetic spectrum of mitochondrial diabetes was expanded by including m.A5826G mutation in tRNACys/tRNATyr, our study provided novel insight into the molecular pathogenesis, early diagnosis, prevention and clinical treatment for mitochondrial diabetes.
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Affiliation(s)
- Xing Li
- Department of Endocrinology, Ordos Center Hospital, Ordos, Inner Mongolian, 017010, People’s Republic of China
| | - Jinyao Shang
- Department of Endocrinology, Ordos Center Hospital, Ordos, Inner Mongolian, 017010, People’s Republic of China
| | - Shuang Li
- Department of Endocrinology, Ordos Center Hospital, Ordos, Inner Mongolian, 017010, People’s Republic of China
| | - Yue Wang
- Department of Endocrinology, Ordos Center Hospital, Ordos, Inner Mongolian, 017010, People’s Republic of China
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Rahmadanthi FR, Maksum IP. Transfer RNA Mutation Associated with Type 2 Diabetes Mellitus. BIOLOGY 2023; 12:871. [PMID: 37372155 DOI: 10.3390/biology12060871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023]
Abstract
Transfer RNA (tRNA) genes in the mitochondrial DNA genome play an important role in protein synthesis. The 22 tRNA genes carry the amino acid that corresponds to that codon but changes in the genetic code often occur such as gene mutations that impact the formation of adenosine triphosphate (ATP). Insulin secretion does not occur because the mitochondria cannot work optimally. tRNA mutation may also be caused by insulin resistance. In addition, the loss of tRNA modification can cause pancreatic β cell dysfunction. Therefore, both can be indirectly associated with diabetes mellitus because diabetes mellitus, especially type 2, is caused by insulin resistance and the body cannot produce insulin. In this review, we will discuss tRNA in detail, several diseases related to tRNA mutations, how tRNA mutations can lead to type 2 diabetes mellitus, and one example of a point mutation that occurs in tRNA.
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Affiliation(s)
- Fanny Rizki Rahmadanthi
- Departement of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang 45363, Indonesia
| | - Iman Permana Maksum
- Departement of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang 45363, Indonesia
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Hayman J, Finsterer J. Diagnoses for Charles Darwin’s Illness: A Wealth of Inaccurate Differential Diagnoses. Cureus 2022; 14:e32065. [PMCID: PMC9711051 DOI: 10.7759/cureus.32065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2022] [Indexed: 12/02/2022] Open
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Li D, Liang C, Zhang T, Marley JL, Zou W, Lian M, Ji D. Pathogenic mitochondrial DNA 3243A>G mutation: From genetics to phenotype. Front Genet 2022; 13:951185. [PMID: 36276941 PMCID: PMC9582660 DOI: 10.3389/fgene.2022.951185] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 09/26/2022] [Indexed: 11/13/2022] Open
Abstract
The mitochondrial DNA (mtDNA) m.3243A>G mutation is one of the most common pathogenic mtDNA variants, showing complex genetics, pathogenic molecular mechanisms, and phenotypes. In recent years, the prevention of mtDNA-related diseases has trended toward precision medicine strategies, such as preimplantation genetic diagnosis (PGD) and mitochondrial replacement therapy (MRT). These techniques are set to allow the birth of healthy children, but clinical implementation relies on thorough insights into mtDNA genetics. The genotype and phenotype of m.3243A>G vary greatly from mother to offspring, which compromises genetic counseling for the disease. This review is the first to systematically elaborate on the characteristics of the m.3243A>G mutation, from genetics to phenotype and the relationship between them, as well as the related influencing factors and potential strategies for preventing disease. These perceptions will provide clarity for clinicians providing genetic counseling to m.3243A>G patients.
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Affiliation(s)
- Danyang Li
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, Anhui, China
| | - Chunmei Liang
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, Anhui, China
| | - Tao Zhang
- Department of Obstetrics and Gynecology, Faculty of Medicine, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Jordan Lee Marley
- Wellcome Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Weiwei Zou
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, Anhui, China
| | - Muqing Lian
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
| | - Dongmei Ji
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, Anhui, China
- *Correspondence: Dongmei Ji,
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Belal S, Goudenège D, Bocca C, Dumont F, Chao De La Barca JM, Desquiret-Dumas V, Gueguen N, Geffroy G, Benyahia R, Kane S, Khiati S, Bris C, Aranyi T, Stockholm D, Inisan A, Renaud A, Barth M, Simard G, Reynier P, Letournel F, Lenaers G, Bonneau D, Chevrollier A, Procaccio V. Glutamate-Induced Deregulation of Krebs Cycle in Mitochondrial Encephalopathy Lactic Acidosis Syndrome Stroke-Like Episodes (MELAS) Syndrome Is Alleviated by Ketone Body Exposure. Biomedicines 2022; 10:biomedicines10071665. [PMID: 35884972 PMCID: PMC9312837 DOI: 10.3390/biomedicines10071665] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/19/2022] [Accepted: 07/01/2022] [Indexed: 11/16/2022] Open
Abstract
(1) Background: The development of mitochondrial medicine has been severely impeded by a lack of effective therapies. (2) Methods: To better understand Mitochondrial Encephalopathy Lactic Acidosis Syndrome Stroke-like episodes (MELAS) syndrome, neuronal cybrid cells carrying different mutation loads of the m.3243A > G mitochondrial DNA variant were analysed using a multi-omic approach. (3) Results: Specific metabolomic signatures revealed that the glutamate pathway was significantly increased in MELAS cells with a direct correlation between glutamate concentration and the m.3243A > G heteroplasmy level. Transcriptomic analysis in mutant cells further revealed alterations in specific gene clusters, including those of the glutamate, gamma-aminobutyric acid pathways, and tricarboxylic acid (TCA) cycle. These results were supported by post-mortem brain tissue analysis from a MELAS patient, confirming the glutamate dysregulation. Exposure of MELAS cells to ketone bodies significantly reduced the glutamate level and improved mitochondrial functions, reducing the accumulation of several intermediate metabolites of the TCA cycle and alleviating the NADH-redox imbalance. (4) Conclusions: Thus, a multi-omic integrated approach to MELAS cells revealed glutamate as a promising disease biomarker, while also indicating that a ketogenic diet should be tested in MELAS patients.
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Affiliation(s)
- Sophie Belal
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
| | - David Goudenège
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
| | - Cinzia Bocca
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
| | - Florent Dumont
- Signalling and Cardiovascular Pathophysiology, INSERM UMR-S 1180, University of Paris-Saclay, 92296 Châtenay-Malabry, France;
| | - Juan Manuel Chao De La Barca
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
| | - Valérie Desquiret-Dumas
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
| | - Naïg Gueguen
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
| | - Guillaume Geffroy
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
| | - Rayane Benyahia
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
| | - Selma Kane
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
| | - Salim Khiati
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
| | - Céline Bris
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
| | - Tamas Aranyi
- Institute of Enzymology, Research Center for Natural Sciences, H-1519 Budapest, Hungary;
- Department of Molecular Biology, Semmelweis University of Medicine, H-1519 Budapest, Hungary
| | - Daniel Stockholm
- Ecole Pratique des Hautes Etudes, PSL Research University, 75014 Paris, France;
- Centre de Recherche Saint-Antoine, UMRS-938, INSERM, Sorbonne Université, F-75012 Paris, France
| | - Aurore Inisan
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
| | - Aurélie Renaud
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
| | - Magalie Barth
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
| | - Gilles Simard
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
| | - Pascal Reynier
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
| | - Franck Letournel
- Department of Neurobiology-Neuropathology, Angers Hospital, 49933 Angers, France;
- UMR INSERM 1066-CNRS 6021, MINT Laboratory, 49933 Angers, France
| | - Guy Lenaers
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
- Service de Neurologie, CHU d'Angers, 49933 Angers, France
| | - Dominique Bonneau
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
| | - Arnaud Chevrollier
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
| | - Vincent Procaccio
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (S.B.); (D.G.); (C.B.); (J.M.C.D.L.B.); (V.D.-D.); (N.G.); (G.G.); (R.B.); (S.K.); (S.K.); (C.B.); (A.I.); (A.R.); (P.R.); (G.L.); (D.B.); (A.C.)
- Biochemistry and Genetics Department, University Hospital of Angers, 49933 Angers, France; (M.B.); (G.S.)
- Correspondence:
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Hayman J, Finsterer J. Charles Darwin's Mitochondrial Disorder: Possible Neuroendocrine Involvement. Cureus 2021; 13:e20689. [PMID: 34966625 PMCID: PMC8710138 DOI: 10.7759/cureus.20689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/25/2021] [Indexed: 11/05/2022] Open
Abstract
Charles Darwin, the famous naturalist, suffered relapsing, debilitating illness for most of his adult life with a plethora of symptoms. The diagnosis favoured here for this illness is that of an adult-onset mitochondrial disorder due to a maternally inherited, pathological mitochondrial DNA mutation clinically manifesting as MELAS (mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes) syndrome. This diagnosis accounts for Darwin's primary symptoms; in addition, it accounts for the various unusual illnesses that afflicted his siblings and maternal (Wedgwood) ancestors. Symptoms of Darwin's illness may be related to dysfunction of cells with high energy requirements; this includes cells constituting the cardiac conduction system, cerebral endothelial cells, neurons, neuroepithelial cells of the vestibular apparatus, and, as proposed here, central and peripheral neuroendocrine cells. Although Darwin's episodes of sudden facial flushing, his nocturnal panic attacks, and his severe gastrointestinal symptoms are not readily explained, these symptoms may relate to neuroendocrine dysfunction, either an uncontrolled release of stimulatory hormone or impaired inhibitory control. It is also conceivable that the autonomic system had been involved. A study of Darwin's illness may benefit those who suffer from similar symptoms today.
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Affiliation(s)
- John Hayman
- Clinical Pathology, The University of Melbourne, Melbourne, AUS
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de Boer E, Ockeloen CW, Matalonga L, Horvath R, Rodenburg RJ, Coenen MJH, Janssen M, Henssen D, Gilissen C, Steyaert W, Paramonov I, Trimouille A, Kleefstra T, Verloes A, Vissers LELM. A MT-TL1 variant identified by whole exome sequencing in an individual with intellectual disability, epilepsy, and spastic tetraparesis. Eur J Hum Genet 2021; 29:1359-1368. [PMID: 34075211 PMCID: PMC8440635 DOI: 10.1038/s41431-021-00900-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 03/25/2021] [Accepted: 04/15/2021] [Indexed: 11/09/2022] Open
Abstract
The genetic etiology of intellectual disability remains elusive in almost half of all affected individuals. Within the Solve-RD consortium, systematic re-analysis of whole exome sequencing (WES) data from unresolved cases with (syndromic) intellectual disability (n = 1,472 probands) was performed. This re-analysis included variant calling of mitochondrial DNA (mtDNA) variants, although mtDNA is not specifically targeted in WES. We identified a functionally relevant mtDNA variant in MT-TL1 (NC_012920.1:m.3291T > C; NC_012920.1:n.62T > C), at a heteroplasmy level of 22% in whole blood, in a 23-year-old male with severe intellectual disability, epilepsy, episodic headaches with emesis, spastic tetraparesis, brain abnormalities, and feeding difficulties. Targeted validation in blood and urine supported pathogenicity, with heteroplasmy levels of 23% and 58% in index, and 4% and 17% in mother, respectively. Interestingly, not all phenotypic features observed in the index have been previously linked to this MT-TL1 variant, suggesting either broadening of the m.3291T > C-associated phenotype, or presence of a co-occurring disorder. Hence, our case highlights the importance of underappreciated mtDNA variants identifiable from WES data, especially for cases with atypical mitochondrial phenotypes and their relatives in the maternal line.
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Affiliation(s)
- Elke de Boer
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Charlotte W Ockeloen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Leslie Matalonga
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, John Van Geest Cambridge Centre for Brain Repair, Cambridge, UK
| | - Richard J Rodenburg
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marieke J H Coenen
- Department of Human Genetics, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mirian Janssen
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Dylan Henssen
- Department of Medical Imaging, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Christian Gilissen
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Wouter Steyaert
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ida Paramonov
- CNAG-CRG, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Aurélien Trimouille
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
- MRGM, Maladies Rares: Génétique et Métabolisme, lNSERM U1211, Université de Bordeaux, Bordeaux, France
| | - Tjitske Kleefstra
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Alain Verloes
- Département de Génétique, APHP Robert DEBRE University Hospital and INSERM U1141, Paris, France
| | - Lisenka E L M Vissers
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
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Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes (MELAS) Syndrome: Frequency, Clinical Features, Imaging, Histopathologic, and Molecular Genetic Findings in a Third-level Health Care Center in Mexico. Neurologist 2021; 26:143-148. [PMID: 34190208 DOI: 10.1097/nrl.0000000000000331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome, is a multisystemic entity of mitochondrial inheritance. To date, there is no epidemiological information on MELAS syndrome in Mexico. CASE SERIES A retrospective, cross-sectional design was employed to collect and analyze the data. The clinical records of patients with mitochondrial cytopathies in the period ranging from January 2018 to March 2020 were reviewed. Patients who met definitive Yatsuga diagnostic criteria for MELAS syndrome were included to describe frequency, clinical, imaging, histopathologic, and molecular studies. Of 56 patients diagnosed with mitochondrial cytopathy, 6 patients met definitive Yatsuga criterion for MELAS (10.7%). The median age at diagnosis was 34 years (30 to 34 y), 2 females and the median time from onset of symptoms at diagnosis 3.5 years (1 to 10 y). The median of the number of stroke-like episodes before the diagnosis was 3 (range, 2 to 3). The main findings in computed tomography were basal ganglia calcifications (33%), whereas in magnetic resonance imaging were a lactate peak in the spectroscopy sequence in 2 patients. Five patients (84%) had red-ragged fibers and phantom fibers in the Cox stain in the muscle biopsy. Four patients (67%) had presence of 3243A>G mutation in the mitochondrial MT-TL1 gene. One patient died because of status epilepticus. CONCLUSIONS MELAS syndrome represents a common diagnostic challenge for clinicians, often delaying definitive diagnosis. It should be suspected in young patients with stroke of undetermined etiology associated with other systemic and neurological features.
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Sanchez Caballero L, Gorgogietas V, Arroyo MN, Igoillo-Esteve M. Molecular mechanisms of β-cell dysfunction and death in monogenic forms of diabetes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 359:139-256. [PMID: 33832649 DOI: 10.1016/bs.ircmb.2021.02.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Monogenetic forms of diabetes represent 1%-5% of all diabetes cases and are caused by mutations in a single gene. These mutations, that affect genes involved in pancreatic β-cell development, function and survival, or insulin regulation, may be dominant or recessive, inherited or de novo. Most patients with monogenic diabetes are very commonly misdiagnosed as having type 1 or type 2 diabetes. The severity of their symptoms depends on the nature of the mutation, the function of the affected gene and, in some cases, the influence of additional genetic or environmental factors that modulate severity and penetrance. In some patients, diabetes is accompanied by other syndromic features such as deafness, blindness, microcephaly, liver and intestinal defects, among others. The age of diabetes onset may also vary from neonatal until early adulthood manifestations. Since the different mutations result in diverse clinical presentations, patients usually need different treatments that range from just diet and exercise, to the requirement of exogenous insulin or other hypoglycemic drugs, e.g., sulfonylureas or glucagon-like peptide 1 analogs to control their glycemia. As a consequence, awareness and correct diagnosis are crucial for the proper management and treatment of monogenic diabetes patients. In this chapter, we describe mutations causing different monogenic forms of diabetes associated with inadequate pancreas development or impaired β-cell function and survival, and discuss the molecular mechanisms involved in β-cell demise.
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Affiliation(s)
- Laura Sanchez Caballero
- ULB Center for Diabetes Research (UCDR), Université Libre de Bruxelles, Brussels, Belgium. http://www.ucdr.be/
| | - Vyron Gorgogietas
- ULB Center for Diabetes Research (UCDR), Université Libre de Bruxelles, Brussels, Belgium. http://www.ucdr.be/
| | - Maria Nicol Arroyo
- ULB Center for Diabetes Research (UCDR), Université Libre de Bruxelles, Brussels, Belgium. http://www.ucdr.be/
| | - Mariana Igoillo-Esteve
- ULB Center for Diabetes Research (UCDR), Université Libre de Bruxelles, Brussels, Belgium. http://www.ucdr.be/.
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Esterhuizen K, Lindeque JZ, Mason S, van der Westhuizen FH, Rodenburg RJ, de Laat P, Smeitink JAM, Janssen MCH, Louw R. One mutation, three phenotypes: novel metabolic insights on MELAS, MIDD and myopathy caused by the m.3243A > G mutation. Metabolomics 2021; 17:10. [PMID: 33438095 DOI: 10.1007/s11306-020-01769-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 12/31/2020] [Indexed: 12/19/2022]
Abstract
INTRODUCTION The m.3243A > G mitochondrial DNA mutation is one of the most common mitochondrial disease-causing mutations, with a carrier rate as high as 1:400. This point mutation affects the MT-TL1 gene, ultimately affecting the oxidative phosphorylation system and the cell's energy production. Strikingly, the m.3243A > G mutation is associated with different phenotypes, including mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), maternally inherited diabetes and deafness (MIDD) and myopathy. OBJECTIVES We investigated urine metabolomes of MELAS, MIDD and myopathy patients in order to identify affected metabolic pathways and possible treatment options. METHODS A multiplatform metabolomics approach was used to comprehensively analyze the metabolome and compare metabolic profiles of different phenotypes caused by the m.3243A > G mutation. Our analytical array consisted of NMR spectroscopy, LC-MS/MS and GC-TOF-MS. RESULTS The investigation revealed phenotypic specific metabolic perturbations, as well as metabolic similarities between the different phenotypes. We show that glucose metabolism is highly disturbed in the MIDD phenotype, but not in MELAS or myopathy, remodeled fatty acid oxidation is characteristic of the MELAS patients, while one-carbon metabolism is strongly modified in both MELAS and MIDD, but not in the myopathy group. Lastly we identified increased creatine in the urine of the myopathy patients, but not in MELAS or MIDD. CONCLUSION We conclude by giving novel insight on the phenotypes of the m.3243A > G mutation from a metabolomics point of view. Directives are also given for future investigations that could lead to better treatment options for patients suffering from this debilitating disease.
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Affiliation(s)
- Karien Esterhuizen
- Mitochondria Research Laboratory, Human Metabolomics, North-West University, Potchefstroom, South Africa
| | - J Zander Lindeque
- Mitochondria Research Laboratory, Human Metabolomics, North-West University, Potchefstroom, South Africa
| | - Shayne Mason
- Mitochondria Research Laboratory, Human Metabolomics, North-West University, Potchefstroom, South Africa
| | | | - Richard J Rodenburg
- Department of Pediatrics, Radboud Center for Mitochondrial Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Paul de Laat
- Department of Pediatrics, Radboud Center for Mitochondrial Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Jan A M Smeitink
- Department of Pediatrics, Radboud Center for Mitochondrial Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Mirian C H Janssen
- Department of Pediatrics, Radboud Center for Mitochondrial Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
- Department of Internal Medicine, Radboud Center for Mitochondrial Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Roan Louw
- Mitochondria Research Laboratory, Human Metabolomics, North-West University, Potchefstroom, South Africa.
- Human Metabolomics, Faculty of Natural and Agricultural Sciences, North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom, South Africa.
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Povea-Cabello S, Villanueva-Paz M, Suárez-Rivero JM, Álvarez-Córdoba M, Villalón-García I, Talaverón-Rey M, Suárez-Carrillo A, Munuera-Cabeza M, Sánchez-Alcázar JA. Advances in mt-tRNA Mutation-Caused Mitochondrial Disease Modeling: Patients' Brain in a Dish. Front Genet 2021; 11:610764. [PMID: 33510772 PMCID: PMC7835939 DOI: 10.3389/fgene.2020.610764] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 11/26/2020] [Indexed: 01/19/2023] Open
Abstract
Mitochondrial diseases are a heterogeneous group of rare genetic disorders that can be caused by mutations in nuclear (nDNA) or mitochondrial DNA (mtDNA). Mutations in mtDNA are associated with several maternally inherited genetic diseases, with mitochondrial dysfunction as a main pathological feature. These diseases, although frequently multisystemic, mainly affect organs that require large amounts of energy such as the brain and the skeletal muscle. In contrast to the difficulty of obtaining neuronal and muscle cell models, the development of induced pluripotent stem cells (iPSCs) has shed light on the study of mitochondrial diseases. However, it is still a challenge to obtain an appropriate cellular model in order to find new therapeutic options for people suffering from these diseases. In this review, we deepen the knowledge in the current models for the most studied mt-tRNA mutation-caused mitochondrial diseases, MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) and MERRF (myoclonic epilepsy with ragged red fibers) syndromes, and their therapeutic management. In particular, we will discuss the development of a novel model for mitochondrial disease research that consists of induced neurons (iNs) generated by direct reprogramming of fibroblasts derived from patients suffering from MERRF syndrome. We hypothesize that iNs will be helpful for mitochondrial disease modeling, since they could mimic patient’s neuron pathophysiology and give us the opportunity to correct the alterations in one of the most affected cellular types in these disorders.
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Affiliation(s)
- Suleva Povea-Cabello
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Marina Villanueva-Paz
- Instituto de Investigación Biomédica de Málaga, Departamento de Farmacología y Pediatría, Facultad de Medicina, Universidad de Málaga, Málaga, Spain
| | - Juan M Suárez-Rivero
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Mónica Álvarez-Córdoba
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Irene Villalón-García
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Marta Talaverón-Rey
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Alejandra Suárez-Carrillo
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - Manuel Munuera-Cabeza
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
| | - José A Sánchez-Alcázar
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, Seville, Spain
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Abstract
Maternally mitochondrial dysfunction includes a heterogeneous group of genetic disorders which leads to the impairment of the final common pathway of energy metabolism. Coronary heart disease and coronary venous disease are two important clinical manifestations of mitochondrial dysfunction due to abnormality in the setting of underlying pathways. Mitochondrial dysfunction can lead to cardiomyopathy, which is involved in the onset of acute cardiac and pulmonary failure. Mitochondrial diseases present other cardiac manifestations such as left ventricular noncompaction and cardiac conduction disease. Different clinical findings from mitochondrial dysfunction originate from different mtDNA mutations, and this variety of clinical symptoms poses a diagnostic challenge for cardiologists. Heart transplantation may be a good treatment, but it is not always possible, and other complications of the disease, such as mitochondrial encephalopathy, lactic acidosis, and stroke-like syndrome, should be considered. To diagnose and treat most mitochondrial disorders, careful cardiac, neurological, and molecular studies are needed. In this study, we looked at molecular genetics of MIDs and cardiac manifestations in patients with mitochondrial dysfunction.
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Hu C, Li X, Zhao L, Shi Y, Zhou S, Wu B, Wang Y. Clinical and molecular characterization of pediatric mitochondrial disorders in south of China. Eur J Med Genet 2020; 63:103898. [PMID: 32348839 DOI: 10.1016/j.ejmg.2020.103898] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 01/15/2020] [Accepted: 02/19/2020] [Indexed: 12/30/2022]
Abstract
Mitochondrial disorders (MDs) are genetic ailments affecting all age groups. Epidemiological data and frequencies of gene mutations in pediatric patients in China are scarce. This retrospective study assessed 101 patients with suspected MDs treated at the Neurology Department of Children's Hospital, Fudan University, in 2011-2017. Mitochondrial (mtDNA) and nuclear (nDNA) samples were assessed by long-range polymerase chain reaction (PCR)-based whole mtDNA sequencing and whole exome sequencing (WES) for identifying pathogenic mutations. Muscle samples underwent various staining protocols and immunofluorescence for detecting selected proteins. Seventeen mutations in the MT-TL1, MT-COX2, MT-ND4, MT, tRNA TRNE, MT-TN, MT-TK, MT-ATP6, MT-ND6, MT-ND3 and MT-CO3 genes were identified in 39 patients, of which m.3243A > G, m.3303C > T, m.8993T > C/G, m.9176T > C, and m.10191T > C were most common. Mitochondrial myopathy and MELAS were most common for m.3243A > G mutation. Four novel mutations were detected, including m.9478insT, m.5666T > C, m.8265T > C, and m.8380-13600 deletion mutations related to Leigh syndrome, mitochondrial myopathy and KSS, respectively. Thirty-three mutations in the TK2, POLG, IBA57, HADHB, FBXL4, ALDH5A1, FOXRED1, TPK1, NDUFAF5, NDUFAF7, NDUFV1, CARS2, PDHA1, and HIBCH genes were identified in 19 patients, including 23 currently unknown. Higher rates of TK2, POLG, IBA57, and HADHB mutations were found in nDNA-mutated MD compared with the remaining individuals. Besides, IBA57 c.286T > C (p.Y96H), TK2 c.497A > T (p.D166V) founder mutations critically contributed to MDs. Comprehensive genomic analysis plays a critical role in pediatric MD diagnosis. These data summarize the relative frequencies of different gene mutations in a large Chinese population, and identified 23 novel MD-associated nDNA and 4 novel mtDNA mutations.
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Affiliation(s)
- Chaoping Hu
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China
| | - Xihua Li
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China.
| | - Lei Zhao
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China
| | - Yiyun Shi
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China
| | - Shuizhen Zhou
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China
| | - Bingbing Wu
- Translational Research Center for Development and Disease, Children's Hospital of Fudan University, Shanghai, China
| | - Yi Wang
- Department of Neurology, Children's Hospital of Fudan University, Shanghai, China.
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Mitochondrial Dynamics Regulation in Skin Fibroblasts from Mitochondrial Disease Patients. Biomolecules 2020; 10:biom10030450. [PMID: 32183225 PMCID: PMC7175126 DOI: 10.3390/biom10030450] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/20/2020] [Accepted: 03/09/2020] [Indexed: 12/19/2022] Open
Abstract
Mitochondria are highly dynamic organelles that constantly fuse, divide, and move, and their function is regulated and maintained by their morphologic changes. Mitochondrial disease (MD) comprises a group of disorders involving mitochondrial dysfunction. However, it is not clear whether changes in mitochondrial morphology are related to MD. In this study, we examined mitochondrial morphology in fibroblasts from patients with MD (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and Leigh syndrome). We observed that MD fibroblasts exhibited significant mitochondrial fragmentation by upregulation of Drp1, which is responsible for mitochondrial fission. Interestingly, the inhibition of mitochondrial fragmentation by Drp1 knockdown enhanced cellular toxicity and led to cell death in MD fibroblasts. These results suggest that mitochondrial fission plays a critical role in the attenuation of mitochondrial damage in MD fibroblasts.
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Melchinger H, Jain K, Tyagi T, Hwa J. Role of Platelet Mitochondria: Life in a Nucleus-Free Zone. Front Cardiovasc Med 2019; 6:153. [PMID: 31737646 PMCID: PMC6828734 DOI: 10.3389/fcvm.2019.00153] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 10/08/2019] [Indexed: 12/19/2022] Open
Abstract
Platelets are abundant, small, anucleate circulating cells, serving many emerging pathophysiological roles beyond hemostasis; including active critical roles in thrombosis, injury response, and immunoregulation. In the absence of genomic DNA transcriptional regulation (no nucleus), platelets require strategic prepackaging of all the needed RNA and organelles from megakaryocytes, to sense stress (e.g., hyperglycemia), to protect themselves from stress (e.g., mitophagy), and to communicate a stress response to other cells (e.g., granule and microparticle release). Distinct from avian thrombocytes that have a nucleus, the absence of a nucleus allows the mammalian platelet to maintain its small size, permits morphological flexibility, and may improve speed and efficiency of protein expression in response to stress. In the absence of a nucleus, platelet lifespan of 7–10 days, is largely determined by the mitochondria. The packaging of 5–8 mitochondria is critical in aerobic respiration and yielding metabolic substrates needed for function and survival. Mitochondria damage or dysfunction, as observed with several disease processes, results in greatly attenuated platelet survival and increased risk for thrombovascular events. Here we provide insights into the emerging roles of platelets despite the lack of a nucleus, and the key role played by mitochondria in platelet function and survival both in health and disease.
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Affiliation(s)
- Hannah Melchinger
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale School of Medicine, New Haven, CT, United States
| | - Kanika Jain
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale School of Medicine, New Haven, CT, United States
| | - Tarun Tyagi
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale School of Medicine, New Haven, CT, United States
| | - John Hwa
- Department of Internal Medicine, Yale Cardiovascular Research Center, Yale School of Medicine, New Haven, CT, United States
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Cognitive impairment, clinical severity and MRI changes in MELAS syndrome. Mitochondrion 2019; 44:53-57. [DOI: 10.1016/j.mito.2017.12.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 12/05/2017] [Accepted: 12/27/2017] [Indexed: 11/17/2022]
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The accumulation of assembly intermediates of the mitochondrial complex I matrix arm is reduced by limiting glucose uptake in a neuronal-like model of MELAS syndrome. Biochim Biophys Acta Mol Basis Dis 2018; 1864:1596-1608. [PMID: 29454073 DOI: 10.1016/j.bbadis.2018.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 02/07/2018] [Accepted: 02/08/2018] [Indexed: 02/06/2023]
Abstract
Ketogenic diet (KD) which combined carbohydrate restriction and the addition of ketone bodies has emerged as an alternative metabolic intervention used as an anticonvulsant therapy or to treat different types of neurological or mitochondrial disorders including MELAS syndrome. MELAS syndrome is a severe mitochondrial disease mainly due to the m.3243A > G mitochondrial DNA mutation. The broad success of KD is due to multiple beneficial mechanisms with distinct effects of very low carbohydrates and ketones. To evaluate the metabolic part of carbohydrate restriction, transmitochondrial neuronal-like cybrid cells carrying the m.3243A > G mutation, shown to be associated with a severe complex I deficiency was exposed during 3 weeks to glucose restriction. Mitochondrial enzyme defects were combined with an accumulation of complex I (CI) matrix intermediates in the untreated mutant cells, leading to a drastic reduction in CI driven respiration. The severe reduction of CI was also paralleled in post-mortem brain tissue of a MELAS patient carrying high mutant load. Importantly, lowering significantly glucose concentration in cell culture improved CI assembly with a significant reduction of matrix assembly intermediates and respiration capacities were restored in a sequential manner. In addition, OXPHOS protein expression and mitochondrial DNA copy number were significantly increased in mutant cells exposed to glucose restriction. The accumulation of CI matrix intermediates appeared as a hallmark of MELAS pathophysiology highlighting a critical pathophysiological mechanism involving CI disassembly, which can be alleviated by lowering glucose fuelling and the induction of mitochondrial biogenesis, emphasizing the usefulness of metabolic interventions in MELAS syndrome.
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Zhang Z, Zhao D, Zhang X, Xiong H, Bao X, Yuan Y, Wang Z. Survival analysis of a cohort of Chinese patients with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) based on clinical features. J Neurol Sci 2018; 385:151-155. [DOI: 10.1016/j.jns.2017.12.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 11/22/2017] [Accepted: 12/27/2017] [Indexed: 12/15/2022]
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Hayman J, Álvarez G, Ceballos FC, Berra TM. The illnesses of Charles Darwin and his children: a lesson in consanguinity. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blw041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Schattner A. Farther than Fahr-reply. QJM 2017; 110:259. [PMID: 28173587 DOI: 10.1093/qjmed/hcx002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Xia CY, Liu Y, Liu H, Zhang YC, Ma YN, Qi Y. Clinical and Molecular Characteristics in 100 Chinese Pediatric Patients with m.3243A>G Mutation in Mitochondrial DNA. Chin Med J (Engl) 2017; 129:1945-9. [PMID: 27503020 PMCID: PMC4989426 DOI: 10.4103/0366-6999.187845] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background: Mitochondrial diseases are a group of energy metabolic disorders with multisystem involvements. Variable clinical features present a major challenge in pediatric diagnoses. We summarized the clinical spectrum of m.3243A>G mutation in Chinese pediatric patients, to define the common clinical manifestations and study the correlation between heteroplasmic degree of the mutation and clinical severity of the disease. Methods: Clinical data of one-hundred pediatric patients with symptomatic mitochondrial disease harboring m.3243A>G mutation from 2007 to 2013 were retrospectively reviewed. Detection of m.3243A>G mutation ratio was performed by polymerase chain reaction (PCR)-restriction fragment length polymorphism. Correlation between m.3243A>G mutation ratio and age was evaluated. The differences in clinical symptom frequency of patients with low, middle, and high levels of mutation ratio were analyzed by Chi-square test. Results: Sixty-six patients (66%) had suffered a delayed diagnosis for an average of 2 years. The most frequent symptoms were seizures (76%), short stature (73%), elevated plasma lactate (70%), abnormal magnetic resonance imaging/computed tomography (MRI/CT) changes (68%), vomiting (55%), decreased vision (52%), headache (50%), and muscle weakness (48%). The mutation ratio was correlated negatively with onset age (r = −0.470, P < 0.001). Myopathy was more frequent in patients with a high level of mutation ratio. However, patients with a low or middle level of m.3243A>G mutation ratio were more likely to suffer hearing loss, decreased vision, and gastrointestinal disturbance than patients with a high level of mutation ratio. Conclusions: Our study showed that half of Chinese pediatric patients with m.3243A>G mutation presented seizures, short stature, abnormal MRI/CT changes, elevated plasma lactate, vomiting, and headache. Pediatric patients with these recurrent symptoms should be considered for screening m.3243A>G mutation. Clinical manifestations and laboratory abnormalities should be carefully monitored in patients with this point mutation.
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Affiliation(s)
- Chang-Yu Xia
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
| | - Yu Liu
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
| | - Hui Liu
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
| | - Yan-Chun Zhang
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
| | - Yi-Nan Ma
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
| | - Yu Qi
- Department of Central Laboratory, Peking University First Hospital, Beijing 100034, China
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Wang W, Zhuang Q, Ji K, Wen B, Lin P, Zhao Y, Li W, Yan C. Identification of miRNA, lncRNA and mRNA-associated ceRNA networks and potential biomarker for MELAS with mitochondrial DNA A3243G mutation. Sci Rep 2017; 7:41639. [PMID: 28139706 PMCID: PMC5282567 DOI: 10.1038/srep41639] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 12/22/2016] [Indexed: 12/25/2022] Open
Abstract
Researchers in the field of mitochondrial biology are increasingly unveiling of the complex mechanisms between mitochondrial dysfunction and noncoding RNAs (ncRNAs). However, roles of ncRNAs underlying mitochondrial myopathy remain unexplored. The aim of this study was to elucidate the regulating networks of dysregulated ncRNAs in Mitochondrial myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like episodes (MELAS) with mitochondrial DNA (mtDNA) A3243G mutation, which might make contributions to the unveiling of the complex mechanisms underlying mitochondrial myopathy and, possibly, new tools applicable to clinical practice. Through high-throughput technology followed by quantitative real-time polymerase chain reaction (qRT-PCR) and bioinformatics analyses, for the first time, we found that the dysregulated muscle miRNAs and lncRNAs between 20 MELAS patients with mtDNA A3243G mutation and 20 controls formed complex regulation networks and participated in immune system, signal transduction, translation, muscle contraction and other pathways in discovery and training phase. Then, selected ncRNAs were validated in muscle and serum in independent validation cohorts by qRT-PCR. Finally, ROC curve analysis indicated reduced serum miR-27b-3p had the better diagnosis value than lactate and might serve as a novel, noninvasive biomarker for MELAS. Follow-up investigation is warranted to better understand roles of ncRNAs in mitochondrial myopathy pathogenesis.
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Affiliation(s)
- Wei Wang
- Laboratory of Neuromuscular Disorders and Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
| | - Qianqian Zhuang
- School of Bioengineering, Qilu University of Technology, Jinan, China
| | - Kunqian Ji
- Laboratory of Neuromuscular Disorders and Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
| | - Bing Wen
- Laboratory of Neuromuscular Disorders and Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
| | - Pengfei Lin
- Laboratory of Neuromuscular Disorders and Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
| | - Yuying Zhao
- Laboratory of Neuromuscular Disorders and Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
| | - Wei Li
- Laboratory of Neuromuscular Disorders and Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
| | - Chuanzhu Yan
- Laboratory of Neuromuscular Disorders and Department of Neurology, Qilu Hospital, Shandong University, Jinan, China.,Key Laboratory for Experimental Teratology of the Ministry of Education, Brain Science Research Institute, Department of Neurology, Qilu Hospital, Shandong University, Jinan, China
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Herst PM, Rowe MR, Carson GM, Berridge MV. Functional Mitochondria in Health and Disease. Front Endocrinol (Lausanne) 2017; 8:296. [PMID: 29163365 PMCID: PMC5675848 DOI: 10.3389/fendo.2017.00296] [Citation(s) in RCA: 177] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 10/16/2017] [Indexed: 01/10/2023] Open
Abstract
The ability to rapidly adapt cellular bioenergetic capabilities to meet rapidly changing environmental conditions is mandatory for normal cellular function and for cancer progression. Any loss of this adaptive response has the potential to compromise cellular function and render the cell more susceptible to external stressors such as oxidative stress, radiation, chemotherapeutic drugs, and hypoxia. Mitochondria play a vital role in bioenergetic and biosynthetic pathways and can rapidly adjust to meet the metabolic needs of the cell. Increased demand is met by mitochondrial biogenesis and fusion of individual mitochondria into dynamic networks, whereas a decrease in demand results in the removal of superfluous mitochondria through fission and mitophagy. Effective communication between nucleus and mitochondria (mito-nuclear cross talk), involving the generation of different mitochondrial stress signals as well as the nuclear stress response pathways to deal with these stressors, maintains bioenergetic homeostasis under most conditions. However, when mitochondrial DNA (mtDNA) mutations accumulate and mito-nuclear cross talk falters, mitochondria fail to deliver critical functional outputs. Mutations in mtDNA have been implicated in neuromuscular and neurodegenerative mitochondriopathies and complex diseases such as diabetes, cardiovascular diseases, gastrointestinal disorders, skin disorders, aging, and cancer. In some cases, drastic measures such as acquisition of new mitochondria from donor cells occurs to ensure cell survival. This review starts with a brief discussion of the evolutionary origin of mitochondria and summarizes how mutations in mtDNA lead to mitochondriopathies and other degenerative diseases. Mito-nuclear cross talk, including various stress signals generated by mitochondria and corresponding stress response pathways activated by the nucleus are summarized. We also introduce and discuss a small family of recently discovered hormone-like mitopeptides that modulate body metabolism. Under conditions of severe mitochondrial stress, mitochondria have been shown to traffic between cells, replacing mitochondria in cells with damaged and malfunctional mtDNA. Understanding the processes involved in cellular bioenergetics and metabolic adaptation has the potential to generate new knowledge that will lead to improved treatment of many of the metabolic, degenerative, and age-related inflammatory diseases that characterize modern societies.
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Affiliation(s)
- Patries M. Herst
- Cancer Cell Biology, Malaghan Institute of Medical Research, Wellington, New Zealand
- Department of Radiation Therapy, University of Otago, Wellington, New Zealand
- *Correspondence: Patries M. Herst, ; Michael V. Berridge,
| | - Matthew R. Rowe
- School of Biological Sciences, Victoria University, Wellington, New Zealand
| | - Georgia M. Carson
- Cancer Cell Biology, Malaghan Institute of Medical Research, Wellington, New Zealand
- School of Biological Sciences, Victoria University, Wellington, New Zealand
| | - Michael V. Berridge
- Cancer Cell Biology, Malaghan Institute of Medical Research, Wellington, New Zealand
- *Correspondence: Patries M. Herst, ; Michael V. Berridge,
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Hahn IK, Lim HT. A Case of Atypical Leber Hereditary Optic Neuropathy Associated with MT-TL1Gene Mutation Misdiagnosed with Glaucoma. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2017. [DOI: 10.3341/jkos.2017.58.1.117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- In Kyun Hahn
- Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Hyun Taek Lim
- Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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Pinto WBVR, Souza PVS, Oliveira ASB. Prognostication in MELAS syndrome and other m.3243A-G mutation-associated disorders. Eur J Neurol 2016; 24:231-232. [DOI: 10.1111/ene.13211] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- W. B. V. R. Pinto
- Division of Neuromuscular Diseases; Department of Neurology and Neurosurgery; Federal University of São Paulo (UNIFESP); São Paulo SP Brazil
| | - P. V. S. Souza
- Division of Neuromuscular Diseases; Department of Neurology and Neurosurgery; Federal University of São Paulo (UNIFESP); São Paulo SP Brazil
| | - A. S. B. Oliveira
- Division of Neuromuscular Diseases; Department of Neurology and Neurosurgery; Federal University of São Paulo (UNIFESP); São Paulo SP Brazil
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Lee HN, Eom S, Kim SH, Kang HC, Lee JS, Kim HD, Lee YM. Epilepsy Characteristics and Clinical Outcome in Patients With Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-Like Episodes (MELAS). Pediatr Neurol 2016; 64:59-65. [PMID: 27671241 DOI: 10.1016/j.pediatrneurol.2016.08.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Revised: 07/31/2016] [Accepted: 08/18/2016] [Indexed: 11/25/2022]
Abstract
BACKGROUND Epileptic seizures in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) are heterogeneous with no pathognomonic features. We reviewed epilepsy characteristics and clinical outcome exclusively in a pediatric population. METHODS Twenty-two children and adolescents (13 males) with confirmed mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes due to mitochondrial DNA A3243G mutation and epilepsy were recruited. Clinical data including seizure semiology, treatment response, neuroimaging findings, and electroencephalography were analyzed. We also examined the effect of the age at seizure onset and initial symptoms on the clinical variables. RESULTS Seizure semiology and electroencephalography abnormalities showed no syndrome-specific findings. Focal seizures occurred in 21 of 22 subjects (95.5%), whereas generalized seizures developed in seven of 22 subjects (31.8%). Twenty of 22 subjects (90.9%) achieved partial to complete reduction of clinical seizures for more than one year with a combination of more than two antiepileptic drugs. The subgroup with earlier seizure onset presented significantly earlier and showed significantly higher rates of drug-resistant epilepsy compared with the late onset group, although there were no significant differences in the initial symptoms. The subjects with severe epileptic conditions tended to have more severe clinical dysfunction and more severe organ involvement. CONCLUSIONS Both focal and generalized seizures occurred in patients with MELAS. Epilepsy in this population is drug resistant, but a certain degree of clinical seizure reduction was achievable with antiepileptic drugs, with more favorable outcomes than historically expected. Close observation and active epilepsy treatment of individuals with MELAS episodes and earlier seizure onset might improve the prognosis.
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Affiliation(s)
- Ha Neul Lee
- Department of Pediatrics, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea; Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Soyong Eom
- Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Se Hoon Kim
- Department of Pathology, Yonsei University College of Medicine, Seoul, Korea
| | - Hoon-Chul Kang
- Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea; Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Joon Soo Lee
- Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea; Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Heung Dong Kim
- Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea; Division of Pediatric Neurology, Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Young-Mock Lee
- Department of Pediatrics, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea; Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, Korea.
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Abstract
BACKGROUND the maternally inherited MTTL1 A3243G mutation in the mitochondrial genome causes MelaS (Mitochondrial encephalopathy lactic acidosis with Stroke-like episodes), a condition that is multisystemic but affects primarily the nervous system. Significant intra-familial variation in phenotype and severity of disease is well recognized. METHODS retrospective and ongoing study of an extended family carrying the MTTL1 A3243G mutation with multiple symptomatic individuals. tissue heteroplasmy is reviewed based on the clinical presentations, imaging studies, laboratory findings in affected individuals and pathological material obtained at autopsy in two of the family members. RESULTS there were seven affected individuals out of thirteen members in this three generation family who each carried the MTTL1 A3243G mutation. the clinical presentations were varied with symptoms ranging from hearing loss, migraines, dementia, seizures, diabetes, visual manifestations, and stroke like episodes. three of the family members are deceased from MelaS or to complications related to MelaS. CONCLUSIONS the results of the clinical, pathological and radiological findings in this family provide strong support to the current concepts of maternal inheritance, tissue heteroplasmy and molecular pathogenesis in MelaS. neurologists (both adult and paediatric) are the most likely to encounter patients with MelaS in their practice. genetic counselling is complex in view of maternal inheritance and heteroplasmy. newer therapeutic options such as arginine are being used for acute and preventative management of stroke like episodes.
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Abstract
PURPOSE OF REVIEW Cerebrovascular disease (CeVD) remains a major cause of death and a leading cause of disability worldwide. CeVD is a complex and multifactorial disease caused by the interaction of vascular risk factors, environment, and genetic factors. In the present article, we discussed genetic susceptibility to CeVD, with particular emphasis on genetic studies of the associations between lipid traits and CeVD. RECENT FINDINGS Several animal and clinical studies clearly defined genetic predisposition to atherosclerosis and CeVD, and particularly to ischemic stroke. Recent evidence has shown that traditional vascular risk factors explain only a small proportion of variance in atherosclerosis, suggesting that additional nontraditional factors and novel genetic determinants impact CeVD. With the help of genome-wide technology, novel genetic variants have been implicated in CeVD and lipid metabolism such as those in protein convertase subtilisin/kexin type 9 (PCSK9) gene in stroke and familial hypercholesterolemia. These studies are important as they contribute to our understanding of the genetic mechanisms underlying CeVD and to developing more effective CeVD prevention strategies. SUMMARY CeVD is a complex and multifactorial disease and genetics likely plays an important role in its pathogenesis. The gene-gene and gene-environment interactions of genes involved in biology of vascular disease, including the lipid metabolism are important factors for individual susceptibility to CeVD. Accounting for individual variation in genes, environment and lifestyle will bring us closer to precision medicine, which is an emerging and recently introduced new approach for disease treatment and prevention in clinical practice.
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Affiliation(s)
- David Della-Morte
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
- Department of Systems Medicine, School of Medicine, University of Rome Tor Vergata, Rome, Italy
- IRCCS San Raffaele Pisana, Rome, Italy
| | - Francesca Pacifici
- Department of Systems Medicine, School of Medicine, University of Rome Tor Vergata, Rome, Italy
| | - Tatjana Rundek
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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Lorenzoni PJ, Werneck LC, Kay CSK, Silvado CES, Scola RH. When should MELAS (Mitochondrial myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like episodes) be the diagnosis? ARQUIVOS DE NEURO-PSIQUIATRIA 2016; 73:959-67. [PMID: 26517220 DOI: 10.1590/0004-282x20150154] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 06/23/2015] [Indexed: 12/13/2022]
Abstract
Mitochondrial myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like episodes (MELAS) is a rare mitochondrial disorder. Diagnostic criteria for MELAS include typical manifestations of the disease: stroke-like episodes, encephalopathy, evidence of mitochondrial dysfunction (laboratorial or histological) and known mitochondrial DNA gene mutations. Clinical features of MELAS are not necessarily uniform in the early stages of the disease, and correlations between clinical manifestations and physiopathology have not been fully elucidated. It is estimated that point mutations in the tRNALeu(UUR) gene of the DNAmt, mainly A3243G, are responsible for more of 80% of MELAS cases. Morphological changes seen upon muscle biopsy in MELAS include a substantive proportion of ragged red fibers (RRF) and the presence of vessels with a strong reaction for succinate dehydrogenase. In this review, we discuss mainly diagnostic criterion, clinical and laboratory manifestations, brain images, histology and molecular findings as well as some differential diagnoses and current treatments.
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Affiliation(s)
- Paulo José Lorenzoni
- Departamento de Clínica Médica, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Lineu Cesar Werneck
- Departamento de Clínica Médica, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Cláudia Suemi Kamoi Kay
- Departamento de Clínica Médica, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | | | - Rosana Herminia Scola
- Departamento de Clínica Médica, Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
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30
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Keilland E, Rupar CA, Prasad AN, Tay KY, Downie A, Prasad C. The expanding phenotype of MELAS caused by the m.3291T > C mutation in the MT-TL1 gene. Mol Genet Metab Rep 2016; 6:64-9. [PMID: 27014580 PMCID: PMC4789386 DOI: 10.1016/j.ymgmr.2016.02.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 02/11/2016] [Accepted: 02/11/2016] [Indexed: 11/28/2022] Open
Abstract
m.3291T > C mutation in the MT-TL1 gene has been infrequently encountered in association with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS), however remains poorly characterized from a clinical perspective. In the following report we describe in detail the phenotypic features, long term follow up (> 7 years) and management in a Caucasian family with MELAS due to the m.3291T > C mutation and review the literature on m.3291T > C mutation. The clinical phenotype in the proposita included overlapping features of MELAS, MERRF (Myoclonic epilepsy and ragged-red fiber syndrome), MNGIE (Mitochondrial neurogastrointestinal encephalopathy), KSS (Kearns-Sayre Syndrome) and CPEO (Chronic progressive external ophthalmoplegia).
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Affiliation(s)
- E Keilland
- Department of Pediatrics, Children's Hospital London Health Sciences Centre, London, Ontario, Canada
| | - C A Rupar
- Department of Pediatrics, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Department of Biochemistry, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Department of Pathology and Laboratory Medicine, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Children's Health Research Institute, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Western University, Children's Hospital London Health Sciences Centre, London, Ontario, Canada
| | - Asuri N Prasad
- Department of Pediatrics, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Department of Neurology, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Children's Health Research Institute, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Western University, Children's Hospital London Health Sciences Centre, London, Ontario, Canada
| | - K Y Tay
- Medical Imaging, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Western University, Children's Hospital London Health Sciences Centre, London, Ontario, Canada
| | - A Downie
- Western University, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Paediatric Psychology, Children's Hospital London Health Sciences Centre, London, Ontario, Canada
| | - C Prasad
- Department of Pediatrics, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Children's Health Research Institute, Children's Hospital London Health Sciences Centre, London, Ontario, Canada; Western University, Children's Hospital London Health Sciences Centre, London, Ontario, Canada
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Baccarelli AA, Byun HM. Platelet mitochondrial DNA methylation: a potential new marker of cardiovascular disease. Clin Epigenetics 2015; 7:44. [PMID: 25901189 PMCID: PMC4404685 DOI: 10.1186/s13148-015-0078-0] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 04/01/2015] [Indexed: 01/29/2023] Open
Abstract
Background Platelets are critical in the etiology of cardiovascular disease (CVD), and the mitochondria in these cells serve as an energy source for platelet function. Epigenetic factors, especially DNA methylation, have been employed as markers of CVD. Unlike nuclear DNA methylation, mitochondrial DNA (mtDNA) methylation has not been widely studied, in part, due to debate about its existence and role. In this study, we examined platelet mtDNA methylation in relation to CVD. Results We measured mtDNA methylation in platelets by bisulfite-PCR pyrosequencing and examined associations of CVD with methylation in mitochondrial genes; cytochrome c oxidase (MT-CO1, MT-CO2, and MT-CO3); tRNA leucine 1 (MT-TL1); ATP synthase (MT-ATP6 and MT-ATP8); and NADH dehydrogenase (MT-MD5). We report that CVD patients have significantly higher mtDNA methylation than healthy controls in MT-CO1 (18.53%, P < 0.0001), MT-CO2 (3.33%, P = 0.0001), MT-CO3 (0.92%, P < 0.0001), and MT-TL1 (1.67%, P = 0.0001), which are involved in ATP synthesis. Platelet mtDNA methylation was not related with age, BMI, and race in this study. Conclusions Our results suggest that platelet mtDNA methylation, which could serve as non-invasive and easy-to-obtain markers, may be implicated in the etiology of CVD. Electronic supplementary material The online version of this article (doi:10.1186/s13148-015-0078-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrea A Baccarelli
- Laboratory of Environmental Epigenetics, Exposure Epidemiology and Risk Program, Department of Environmental Health, Harvard T.H. Chan School of Public Health, 677 Huntington Ave., Boston, MA 02115 USA
| | - Hyang-Min Byun
- Laboratory of Environmental Epigenetics, Exposure Epidemiology and Risk Program, Department of Environmental Health, Harvard T.H. Chan School of Public Health, 677 Huntington Ave., Boston, MA 02115 USA ; Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Biomedical Research Building, Campus for Ageing and Vitality, Newcastle upon Tyne, NE4 5PL UK
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Gallego-Delgado M, Cobo-Marcos M, Bornstein B, Hernández-Laín A, Alonso-Pulpón L, Garcia-Pavia P. Miocardiopatías mitocondriales asociadas a la mutación m.3243A>G en el gen MT-TL1: dos caras de la misma moneda. Rev Esp Cardiol 2015. [DOI: 10.1016/j.recesp.2014.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Gallego-Delgado M, Cobo-Marcos M, Bornstein B, Hernández-Laín A, Alonso-Pulpón L, Garcia-Pavia P. Mitochondrial cardiomyopathies associated with the m.3243A>G mutation in the MT-TL1 gene: two sides of the same coin. ACTA ACUST UNITED AC 2014; 68:153-5. [PMID: 25440178 DOI: 10.1016/j.rec.2014.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Accepted: 09/05/2014] [Indexed: 11/27/2022]
Affiliation(s)
- María Gallego-Delgado
- Unidad de Insuficiencia Cardiaca y Cardiopatías Familiares, Servicio de Cardiología, Hospital Universitario Puerta de Hierro, Majadahonda, Madrid, Spain
| | - Marta Cobo-Marcos
- Unidad de Insuficiencia Cardiaca y Cardiopatías Familiares, Servicio de Cardiología, Hospital Universitario Puerta de Hierro, Majadahonda, Madrid, Spain
| | - Belén Bornstein
- Servicio de Bioquímica, Hospital Universitario Puerta de Hierro, Majadahonda, Madrid, Spain; Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER), Madrid, Spain
| | - Aurelio Hernández-Laín
- Sección de Neuropatología, Servicio de Anatomía Patológica, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Luis Alonso-Pulpón
- Unidad de Insuficiencia Cardiaca y Cardiopatías Familiares, Servicio de Cardiología, Hospital Universitario Puerta de Hierro, Majadahonda, Madrid, Spain
| | - Pablo Garcia-Pavia
- Unidad de Insuficiencia Cardiaca y Cardiopatías Familiares, Servicio de Cardiología, Hospital Universitario Puerta de Hierro, Majadahonda, Madrid, Spain.
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Heterogeneous phenotypic manifestations of maternally inherited deafness associated with the mitochondrial A3243G mutation. Case report. Neurol Neurochir Pol 2014; 48:150-3. [DOI: 10.1016/j.pjnns.2013.12.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 12/23/2013] [Indexed: 11/21/2022]
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Zhu Y, Huang S, Kang D, Han M, Wang G, Yuan Y, Su Y, Yuan H, Zhai S, Dai P. Analysis of the heteroplasmy level and transmitted features in hearing-loss pedigrees with mitochondrial 12S rRNA A1555G mutation. BMC Genet 2014; 15:26. [PMID: 24533451 PMCID: PMC3933286 DOI: 10.1186/1471-2156-15-26] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Accepted: 02/12/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mitochondrial cytopathies are characterized by a large variability of clinical phenotypes and severity. The amount of mutant mitochondrial DNA (mtDNA) in a cell, called the heteroplasmy level, is an important determinant of the degree of mitochondrial dysfunction and therefore disease severity. Understanding the distribution of heteroplasmy levels across a group of offspring is an important step in understanding the inheritance of diseases. Recently, the mtDNA A1555G mutation was found to be associated with non-syndromic and drug-induced hearing loss. RESULTS Here, we report five pedigrees with multiple members having the A1555G mutation and showing diverse clinical manifestations and different heteroplasmy levels. Clinical evaluations revealed that the hearing impairment phenotypes varied with respect to the severity of hearing loss, age of onset of hearing loss, and pattern of audiometric configuration. These five Chinese pedigrees had different penetrance of hearing loss, ranging from 10-52%. A molecular study showed that the average heteroplasmy rates of the five pedigrees were 31.98% (0-91.35%), 78.28% (32.8-96.08%), 87.99% (82.32-94.65%), 93.34% (91.02-95.05%), and 93.57% (91.38-94.24%). There was no gradual tendency of heteroplasmy to increase or decrease along with transmission. A study of the relationship between clinical features and genetic background found that the percentage of deafness was 0 when the heteroplasmy level was less than 50%, 25% when the heteroplasmy level was 50-80%, 47.06% when the heteroplasmy level was 80-90%, and 57.58% when the heteroplasmy level exceeded 90%. The risk of deafness rose with the heteroplasmy level. CONCLUSIONS The results suggest that there are large random shifts in the heteroplasmy level between mothers and offspring with the A1555G mutation; heteroplasmy could disappear randomly when the heteroplasmy level of the pedigree was low enough, and no regular pattern was found. The heteroplasmy level may be one of the factors influencing the penetrance of deafness caused by the mtDNA A1555G mutation.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Suoqiang Zhai
- Department of Otorhinolaryngology, Head and Neck Surgery, PLA General Hospital, 28# Fuxing Road, Beijing 100853, P, R, China.
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Tenney JR, Prada CE, Hopkin RJ, Hallinan BE. Early spinal cord and brainstem involvement in infantile Leigh syndrome possibly caused by a novel variant. J Child Neurol 2013; 28:1681-5. [PMID: 23143729 DOI: 10.1177/0883073812464273] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leigh syndrome, due to a dysfunction of mitochondrial energy metabolism, is a genetically heterogeneous and progressive neurologic disorder that usually occurs in infancy and childhood. Its clinical presentation and neuroimaging findings can be variable, especially early in the course of the disease. This report presents a patient with infantile Leigh syndrome who had atypical radiologic findings on serial neuroimaging studies with early and severe involvement of the cervical spinal cord and brainstem and injury to the thalami and basal ganglia occurring only late in the clinical course. Postmortem microscopic examination supported this timing of injury within the central nervous system. In addition, mitochondrial deoxyribonucleic acid sequencing showed a novel homoplasmic variant that could be responsible for this unique lethal form of Leigh syndrome.
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Affiliation(s)
- Jeffrey R Tenney
- 1Department of Pediatrics, Division of Neurology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH, USA
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37
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Moreno-Loshuertos R, Pérez-Martos A, Fernández-Silva P, Enríquez JA. Length variation in the mouse mitochondrial tRNA(Arg) DHU loop size promotes oxidative phosphorylation functional differences. FEBS J 2013; 280:4983-98. [PMID: 23910637 DOI: 10.1111/febs.12466] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/07/2013] [Accepted: 07/22/2013] [Indexed: 01/24/2023]
Abstract
The efficiency of the cellular oxidative phosphorylation system was recently shown to be modulated by common mitochondrial tRNA(A) (rg) haplotypes. The molecular mechanism by which some mt-Tr haplotypes induce these functional differences remains undetermined. Common polymorphisms in mouse mt-Tr genes affect the size of the dihydrouridine loop in the mature tRNA, producing loops of between five and seven nucleotides, the largest being a rare variant among mammals. Here, we analyzed a new mt-Tr variant identified in C3H mice, and found that it is mitochondrial tRNA loop size, but not the specific sequence, that is responsible for the observed differences in cellular respiration. We further found that the sensitivity of mitochondrial protein synthesis to specific inhibitors is dependent on the mt-Tr gene haplotype, and confirmed that the differences in oxidative phosphorylation performance are masked by a reactive oxygen species-induced compensatory increase in mitochondrial biogenesis.
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38
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Jeppesen TD, Duno M, Risom L, Wibrand F, Rafiq J, Krag T, Jakobsen J, Andersen H, Vissing J. A novel de novo mutation of the mitochondrial tRNAlys gene mt.8340G>a associated with pure myopathy. Neuromuscul Disord 2013; 24:162-6. [PMID: 24161205 DOI: 10.1016/j.nmd.2013.08.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 07/15/2013] [Accepted: 08/12/2013] [Indexed: 11/19/2022]
Abstract
Most patients with mutations in the tRNA(lys) gene (MTTK) present with symptoms from the central nervous system (CNS). We describe a 41-year-old woman with pure myopathy associated with a novel de novo mtDNA mutation, mt.8340G>A, which was heteroplasmic in muscle (53%), blood, urine and mouth epithelial cells (<7%). No other family members, including her mother, carried the mutation. She presented with exercise intolerance from age 9, and since age 20 she experienced ptosis and reduced ocular motility. A muscle biopsy revealed ragged red fibres (10%), no COX negative fibres, and many fibres with central nuclei (30%), indicating ongoing damage and repair. The present case expands the mutational and phenotypic spectrum of diseases associated with mutations in MTTK.
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Affiliation(s)
- Tina Dysgaard Jeppesen
- Neuromuscular Research Unit, Section 3342, Rigshospitalet, University of Copenhagen, Denmark; Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark; Department of Neurology, Aarhus Hospital, University of Aarhus, Denmark.
| | - Morten Duno
- Department of Clinical Genetics, Rigshospitalet, University of Copenhagen, Denmark; Department of Neurology, Aarhus Hospital, University of Aarhus, Denmark
| | - Lotte Risom
- Department of Clinical Genetics, Rigshospitalet, University of Copenhagen, Denmark; Department of Neurology, Aarhus Hospital, University of Aarhus, Denmark
| | - Flemming Wibrand
- Department of Clinical Genetics, Rigshospitalet, University of Copenhagen, Denmark; Department of Neurology, Aarhus Hospital, University of Aarhus, Denmark
| | - Jabin Rafiq
- Neuromuscular Research Unit, Section 3342, Rigshospitalet, University of Copenhagen, Denmark
| | - Thomas Krag
- Neuromuscular Research Unit, Section 3342, Rigshospitalet, University of Copenhagen, Denmark; Department of Neurology, Aarhus Hospital, University of Aarhus, Denmark
| | - Johannes Jakobsen
- Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark; Department of Neurology, Aarhus Hospital, University of Aarhus, Denmark
| | - Henning Andersen
- Department of Clinical Genetics, Rigshospitalet, University of Copenhagen, Denmark; Department of Neurology, Aarhus Hospital, University of Aarhus, Denmark
| | - John Vissing
- Neuromuscular Research Unit, Section 3342, Rigshospitalet, University of Copenhagen, Denmark; Department of Neurology, Rigshospitalet, University of Copenhagen, Denmark; Department of Neurology, Aarhus Hospital, University of Aarhus, Denmark
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Mabalirajan U, Ghosh B. Mitochondrial dysfunction in metabolic syndrome and asthma. J Allergy (Cairo) 2013; 2013:340476. [PMID: 23840225 PMCID: PMC3687506 DOI: 10.1155/2013/340476] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 05/21/2013] [Indexed: 01/15/2023] Open
Abstract
Though severe or refractory asthma merely affects less than 10% of asthma population, it consumes significant health resources and contributes significant morbidity and mortality. Severe asthma does not fell in the routine definition of asthma and requires alternative treatment strategies. It has been observed that asthma severity increases with higher body mass index. The obese-asthmatics, in general, have the features of metabolic syndrome and are progressively causing a significant burden for both developed and developing countries thanks to the westernization of the world. As most of the features of metabolic syndrome seem to be originated from central obesity, the underlying mechanisms for metabolic syndrome could help us to understand the pathobiology of obese-asthma condition. While mitochondrial dysfunction is the common factor for most of the risk factors of metabolic syndrome, such as central obesity, dyslipidemia, hypertension, insulin resistance, and type 2 diabetes, the involvement of mitochondria in obese-asthma pathogenesis seems to be important as mitochondrial dysfunction has recently been shown to be involved in airway epithelial injury and asthma pathogenesis. This review discusses current understanding of the overlapping features between metabolic syndrome and asthma in relation to mitochondrial structural and functional alterations with an aim to uncover mechanisms for obese-asthma.
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Affiliation(s)
- Ulaganathan Mabalirajan
- Molecular Immunogenetics Laboratory and Centre of Excellence for Translational Research in Asthma & Lung Disease, CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
| | - Balaram Ghosh
- Molecular Immunogenetics Laboratory and Centre of Excellence for Translational Research in Asthma & Lung Disease, CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
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Abstract
Charles Darwin's long-term illness has been the subject of much speculation. His numerous symptoms have led to conclusions that his illness was essentially psychogenic in nature. These diagnoses have never been fully convincing, however, particularly in regard to the proposed underlying psychological background causes of the illness. Similarly, two proposed somatic causes of illness, Chagas disease and arsenic poisoning, lack credibility and appear inconsistent with the lifetime history of the illness. Other physical explanations are simply too incomplete to explain the range of symptoms. Here, a very different sort of explanation will be offered. We now know that mitochondrial mutations producing impaired mitochondrial function may result in a wide range of differing symptoms, including symptoms thought to be primarily psychological. Examination of Darwin's maternal family history supports the contention that his illness was mitochondrial in nature; his mother and one maternal uncle had strange illnesses and the youngest maternal sibling died of an infirmity with symptoms characteristic of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS syndrome), a condition rooted in mitochondrial dysfunction. Darwin's own symptoms are described here and are in accord with the hypothesis that he had the mtDNA mutation commonly associated with the MELAS syndrome.
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Garrido-Maraver J, Cordero MD, Moñino ID, Pereira-Arenas S, Lechuga-Vieco AV, Cotán D, De la Mata M, Oropesa-Ávila M, De Miguel M, Bautista Lorite J, Rivas Infante E, Alvarez-Dolado M, Navas P, Jackson S, Francisci S, Sánchez-Alcázar JA. Screening of effective pharmacological treatments for MELAS syndrome using yeasts, fibroblasts and cybrid models of the disease. Br J Pharmacol 2013; 167:1311-28. [PMID: 22747838 DOI: 10.1111/j.1476-5381.2012.02086.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE MELAS (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes) is a mitochondrial disease most usually caused by point mutations in tRNA genes encoded by mitochondrial DNA (mtDNA). Approximately 80% of cases of MELAS syndrome are associated with a m.3243A > G mutation in the MT-TL1 gene, which encodes the mitochondrial tRNALeu (UUR). Currently, no effective treatments are available for this chronic progressive disorder. Treatment strategies in MELAS and other mitochondrial diseases consist of several drugs that diminish the deleterious effects of the abnormal respiratory chain function, reduce the presence of toxic agents or correct deficiencies in essential cofactors. EXPERIMENTAL APPROACH We evaluated the effectiveness of some common pharmacological agents that have been utilized in the treatment of MELAS, in yeast, fibroblast and cybrid models of the disease. The yeast model harbouring the A14G mutation in the mitochondrial tRNALeu(UUR) gene, which is equivalent to the A3243G mutation in humans, was used in the initial screening. Next, the most effective drugs that were able to rescue the respiratory deficiency in MELAS yeast mutants were tested in fibroblasts and cybrid models of MELAS disease. KEY RESULTS According to our results, supplementation with riboflavin or coenzyme Q(10) effectively reversed the respiratory defect in MELAS yeast and improved the pathologic alterations in MELAS fibroblast and cybrid cell models. CONCLUSIONS AND IMPLICATIONS Our results indicate that cell models have great potential for screening and validating the effects of novel drug candidates for MELAS treatment and presumably also for other diseases with mitochondrial impairment.
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Affiliation(s)
- Juan Garrido-Maraver
- Centro Andaluz de Biología del Desarrollo (CABD) and Centro de Investigación Biomédica en Red: Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas-Junta de Andalucía, Sevilla, Spain
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Vivero RJ, Ouyang X, Kim YG, Liu W, Du L, Yan D, Liu XZ. Audiologic and genetic features of the A3243G mtDNA mutation. Genet Test Mol Biomarkers 2013; 17:383-9. [PMID: 23477312 DOI: 10.1089/gtmb.2012.0403] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Mitochondrial mutations have been shown to be responsible for syndromic and nonsyndromic hearing impairment. AIM To assess the genotypic-phenotypic correlation of mitochondrial DNA mutations in three generations of a single family. METHODS A single family with maternally inherited diabetes and hearing loss was recruited. Genomic DNA was subject to polymerase chain reaction-restriction fragment length polymorphism analysis (ApaI) for A3243G mutation detection and confirmation with direct DNA sequencing. The degree of heteroplasmy for the A3243G mutation in blood DNA samples was quantified. In addition, we reviewed audiological data of A3243G-associated hearing loss cases from the literature to provide details of audiologic features. RESULTS Six of 11 family members were recruited. All affected members harbored the A3243G mutation. Four of six members had diabetes. Five of five affected members demonstrated hearing loss ranging from mild to severe. The degree of heteroplasmy ranged from 5.51% to 27.74%. CONCLUSIONS Patients with a greater percentage of heteroplasmy have a trend toward more severe phenotypic presentations. Hearing loss is bilateral, sensorineural, and symmetric. The main audiogram shapes found were sloping. Additional studies are necessary to clarify the relationship between degree of heteroplasmy and phenotypic presentation.
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Affiliation(s)
- Richard J Vivero
- Department of Otolaryngology, University of Miami Ear Institute, Miami, Florida 33136, USA
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Raap AK, Jahangir Tafrechi RS, van de Rijke FM, Pyle A, Wählby C, Szuhai K, Ravelli RBG, de Coo RFM, Rajasimha HK, Nilsson M, Chinnery PF, Samuels DC, Janssen GMC. Non-random mtDNA segregation patterns indicate a metastable heteroplasmic segregation unit in m.3243A>G cybrid cells. PLoS One 2012; 7:e52080. [PMID: 23272214 PMCID: PMC3525564 DOI: 10.1371/journal.pone.0052080] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 11/08/2012] [Indexed: 01/07/2023] Open
Abstract
Many pathogenic mitochondrial DNA mutations are heteroplasmic, with a mixture of mutated and wild-type mtDNA present within individual cells. The severity and extent of the clinical phenotype is largely due to the distribution of mutated molecules between cells in different tissues, but mechanisms underpinning segregation are not fully understood. To facilitate mtDNA segregation studies we developed assays that measure m.3243A>G point mutation loads directly in hundreds of individual cells to determine the mechanisms of segregation over time. In the first study of this size, we observed a number of discrete shifts in cellular heteroplasmy between periods of stable heteroplasmy. The observed patterns could not be parsimoniously explained by random mitotic drift of individual mtDNAs. Instead, a genetically metastable, heteroplasmic mtDNA segregation unit provides the likely explanation, where stable heteroplasmy is maintained through the faithful replication of segregating units with a fixed wild-type/m.3243A>G mutant ratio, and shifts occur through the temporary disruption and re-organization of the segregation units. While the nature of the physical equivalent of the segregation unit remains uncertain, the factors regulating its organization are of major importance for the pathogenesis of mtDNA diseases.
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Affiliation(s)
- Anton K. Raap
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands
| | | | - Frans M. van de Rijke
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Angela Pyle
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Carolina Wählby
- Imaging Platform, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Centre for Image Analysis, Uppsala University, Uppsala, Sweden
| | - Karoly Szuhai
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Raimond B. G. Ravelli
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands
| | - René F. M. de Coo
- Department of Neurology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Harsha K. Rajasimha
- Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Mats Nilsson
- Department of Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Patrick F. Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David C. Samuels
- Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - George M. C. Janssen
- Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, The Netherlands
- * E-mail:
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Postlingual hearing loss as a mitochondrial 3243A>G mutation phenotype. PLoS One 2012; 7:e44054. [PMID: 23133508 PMCID: PMC3485002 DOI: 10.1371/journal.pone.0044054] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 07/30/2012] [Indexed: 11/19/2022] Open
Abstract
Background The prevalence of isolated hearing loss (HL) associated with the m.3243A>G mutation is unknown. The aim of this study was to assess the frequency and heteroplasmy level of the m.3243A>G mutation in a large group of Polish patients with postlingual bilateral sensorineural HL of unidentified cause. Methodology/Principal Findings A molecular search was undertaken in the archival blood DNA of 1482 unrelated patients with isolated HL that had begun at ages between 5 and 40 years. Maternal relatives of the probands were subsequently investigated and all carriers underwent audiological tests. The m.3243A>G mutation was found in 16 of 1482 probands (an incidence of 1.08%) and 18 family members. Of these 34 individuals, hearing impairment was detected in 29 patients and the mean onset of HL was at 26 years. Some 42% of the identified m.3243A>G carriers did not develop multisystem symptomatology over the following 10 years. Mean heteroplasmy level of m.3243A>G was lowest in blood at a level of 14% and highest in urine at 58%. These values were independent of the manifested clinical severity of the disease. Conclusions A single m.3243A>G carrier can usually be found among each 100 individuals who have postlingual hearing loss of unknown cause. Urine samples are best for detecting the m.3243A>G mutation and diagnosing mitochondrially inherited hearing loss.
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Koga Y, Povalko N, Nishioka J, Katayama K, Yatsuga S, Matsuishi T. Molecular pathology of MELAS and l-arginine effects. Biochim Biophys Acta Gen Subj 2012; 1820:608-14. [DOI: 10.1016/j.bbagen.2011.09.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 07/07/2011] [Accepted: 09/07/2011] [Indexed: 11/30/2022]
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Perazzo JC, Tallis S, Delfante A, Souto PA, Lemberg A, Eizayaga FX, Romay S. Hepatic encephalopathy: An approach to its multiple pathophysiological features. World J Hepatol 2012; 4:50-65. [PMID: 22489256 PMCID: PMC3321490 DOI: 10.4254/wjh.v4.i3.50] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Revised: 11/19/2011] [Accepted: 02/24/2012] [Indexed: 02/06/2023] Open
Abstract
Hepatic encephalopathy (HE) is a neuropsychiatric complex syndrome, ranging from subtle behavioral abnormalities to deep coma and death. Hepatic encephalopathy emerges as the major complication of acute or chronic liver failure. Multiplicity of factors are involved in its pathophysiology, such as central and neuromuscular neurotransmission disorder, alterations in sleep patterns and cognition, changes in energy metabolism leading to cell injury, an oxidative/nitrosative state and a neuroinflammatory condition. Moreover, in acute HE, a condition of imminent threat of death is present due to a deleterious astrocyte swelling. In chronic HE, changes in calcium signaling, mitochondrial membrane potential and long term potential expression, N-methyl-D-aspartate-cGMP and peripheral benzodiazepine receptors alterations, and changes in the mRNA and protein expression and redistribution in the cerebral blood flow can be observed. The main molecule indicated as responsible for all these changes in HE is ammonia. There is no doubt that ammonia, a neurotoxic molecule, triggers or at least facilitates most of these changes. Ammonia plasma levels are increased two- to three-fold in patients with mild to moderate cirrhotic HE and up to ten-fold in patients with acute liver failure. Hepatic and inter-organ trafficking of ammonia and its metabolite, glutamine (GLN), lead to hyperammonemic conditions. Removal of hepatic ammonia is a differentiated work that includes the hepatocyte, through the urea cycle, converting ammonia into GLN via glutamine synthetase. Under pathological conditions, such as liver damage or liver blood by-pass, the ammonia plasma level starts to rise and the risk of HE developing is high. Knowledge of the pathophysiology of HE is rapidly expanding and identification of focally localized triggers has led the development of new possibilities for HE to be considered. This editorial will focus on issues where, to the best of our knowledge, more research is needed in order to clarify, at least partially, controversial topics.
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Affiliation(s)
- Juan Carlos Perazzo
- Juan Carlos Perazzo, Silvina Tallis, Amalia Delfante, Pablo Andrés Souto, Abraham Lemberg, Francisco Xavier Eizayaga, Salvador Romay, Laboratory of Portal Hypertension and Hepatic Encephalopathy, Pathophysiology, School of Pharmacy and Biochemistry, University of Buenos Aires, Junin 950, CP 1113, Buenos Aires, Argentina
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Lease RA, Arluison V, Lavelle C. Twins, quadruplexes, and more: functional aspects of native and engineered RNA self-assembly in vivo.. FRONTIERS IN LIFE SCIENCE 2012; 6:19-32. [PMID: 23914307 PMCID: PMC3725660 DOI: 10.1080/21553769.2012.761163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 12/18/2012] [Indexed: 11/23/2022]
Abstract
The primacy and power of RNA in governing many processes of life has begun to be more fully appreciated in both the discovery and inventive sciences. A variety of RNA interactions regulate gene expression, and structural self-assembly underlies many of these processes. The understanding sparked by these discoveries has inspired and informed the engineering of novel RNA structures, control elements, and genetic circuits in cells. Many of these engineered systems are built up fundamentally from RNA–RNA interactions, often combining modular, rational design with functional selection and screening. It is therefore useful to review the particular class of RNA-based regulatory mechanisms that rely on RNA self-assembly either through homomeric (self–self) or heteromeric (self–nonself) RNA–RNA interactions. Structures and sequence elements within individual RNAs create a basis for the pairing interactions, and in some instances can even lead to the formation of RNA polymers. Example systems of dimers, multimers, and polymers are reviewed in this article in the context of natural systems, wherein the function and impact of self-assemblies are understood. Following this, a brief overview is presented of specific engineered RNA self-assembly systems implemented in vivo, with lessons learned from both discovery and engineering approaches to RNA–RNA self-assembly.
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Affiliation(s)
- Richard A Lease
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio, USA
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Abstract
Mutations that arise in mitochondrial DNA (mtDNA) may be sporadic, maternally inherited, or Mendelian in character and include mtDNA rearrangements such as deletions, inversions or duplications, point mutations, or copy number depletion. Primary mtDNA mutations occur sporadically or exhibit maternal inheritance and arise due in large part to the high mutation rate of mtDNA. mtDNA mutations may also occur because of defects in the biogenesis or maintenance of mtDNA, reflecting the contribution of nuclear-encoded genes to these processes, and in this case exhibit Mendelian inheritance. Whether maternally inherited, sporadic, or Mendelian, mtDNA mutations can exhibit a complex and broad spectrum of disease manifestations due to the central role mitochondria play in a variety of cellular functions. In addition, because there exist hundreds to thousands of copies of mtDNA in each cell, the proportion of mutant mtDNA molecules can have a profound effect on the cellular and clinical phenotype. This chapter reviews the classification of mtDNA mutations and the clinical features that determine the diagnosis of a primary mtDNA disorder.
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Affiliation(s)
- William J Craigen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
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