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Li D, Sun Y, Zhuang Q, Song Y, Wu B, Jia Z, Pan H, Zhou H, Hu S, Zhang B, Qiu Y, Dai Y, Chen S, Xu X, Zhu X, Lin A, Huang W, Liu Z, Yan Q. Mitochondrial dysfunction caused by m.2336T>C mutation with hypertrophic cardiomyopathy in cybrid cell lines. Mitochondrion 2018; 46:313-320. [PMID: 30196098 DOI: 10.1016/j.mito.2018.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 08/09/2018] [Accepted: 08/28/2018] [Indexed: 10/28/2022]
Abstract
Hypertrophic cardiomyopathy (HCM), affecting approximately 1 in 500 in the general population, is the most prominent cause of sudden heart disease-related mortality in the young. Mitochondrial DNA (mtDNA) mutations are among the primary causes of HCM. We previously identified a novel m.2336T>C homoplasmic mutation in the mitochondrial 16S rRNA gene (MT-RNR2) in a Chinese maternally inherited HCM family. However, the molecular mechanisms by which m.2336T>C mutation contributes to HCM remain elusive. Here we generated transferring mitochondria cell lines (cybrids) with a constant nuclear background by transferring mitochondria from immortalized lymphoblastoid cell lines carrying the HCM-associated m.2336T>C mutation into human mtDNA-less (ρ°) cells. Functional assays showed a decreased stability for 16S rRNA and the steady-state levels of its binding proteins in the mutant cybrids. This mutation impaired the mitochondrial translation capacity and resulted in many mitochondrial dysfunctions, including elevation of ROS generation, reduction of ATP production and impairment of mitochondrial membrane potential. Moreover, the mutant cybrids had poor physiological status and decreased survival ability. These results confirm that the m.2336T>C mutation leads to mitochondrial dysfunction and strongly suggest that this mutation may play a role in the pathogenesis of HCM.
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Affiliation(s)
- Dan Li
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China; Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, China
| | - Yaping Sun
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Qianqian Zhuang
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yanrui Song
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Bifeng Wu
- The First Affiliated Hospital, School of Medicine Zhejiang University, Hangzhou, Zhejiang 310003, China
| | - Zexiao Jia
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Huaye Pan
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Hui Zhou
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Shuangyi Hu
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Bingtao Zhang
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yue Qiu
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yu Dai
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Siyuan Chen
- Stomatology Hospital, School of Medicine Zhejiang University, Hangzhou, Zhejiang 310016, China
| | - Xuejun Xu
- Stomatology Hospital, School of Medicine Zhejiang University, Hangzhou, Zhejiang 310016, China
| | - Xufen Zhu
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Aifu Lin
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Wendong Huang
- Departmentof Diabetes Complications and Metabolism, The Beckman Research Institute, City of Hope National Medical Center, Duarte, CA 91010, USA
| | - Zhong Liu
- The First Affiliated Hospital, School of Medicine Zhejiang University, Hangzhou, Zhejiang 310003, China.
| | - Qingfeng Yan
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China; The First Affiliated Hospital, School of Medicine Zhejiang University, Hangzhou, Zhejiang 310003, China; Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang 310058, China; Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Hangzhou, Zhejiang 310058, China.
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2
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Cellular Metabolism and Induced Pluripotency. Cell 2016; 166:1371-1385. [PMID: 27610564 DOI: 10.1016/j.cell.2016.08.008] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 08/02/2016] [Accepted: 08/03/2016] [Indexed: 01/19/2023]
Abstract
The discovery of induced pluripotent stem cells (iPSCs) a decade ago, which we are celebrating in this issue of Cell, represents a landmark discovery in biomedical research. Together with somatic cell nuclear transfer, iPSC generation reveals the remarkable plasticity associated with differentiated cells and provides an unprecedented means for modeling diseases using patient samples. In addition to transcriptional and epigenetic remodeling, cellular reprogramming to pluripotency is also accompanied by a rewiring of metabolic pathways, which ultimately leads to changes in cell identities.
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Darbandi S, Darbandi M, Khorshid HRK, Sadeghi MR, Al-Hasani S, Agarwal A, Shirazi A, Heidari M, Akhondi MM. Experimental strategies towards increasing intracellular mitochondrial activity in oocytes: A systematic review. Mitochondrion 2016; 30:8-17. [PMID: 27234976 DOI: 10.1016/j.mito.2016.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 04/04/2016] [Accepted: 05/20/2016] [Indexed: 12/19/2022]
Abstract
PURPOSE The mitochondrial complement is critical in sustaining the earliest stages of life. To improve the Assisted Reproductive Technology (ART), current methods of interest were evaluated for increasing the activity and copy number of mitochondria in the oocyte cell. METHODS This covered the researches from 1966 to September 2015. RESULTS The results provided ten methods that can be studied individually or simultaneously. CONCLUSION Though the use of these techniques generated great concern about heteroplasmy observation in humans, it seems that with study on these suggested methods there is real hope for effective treatments of old oocyte or oocytes containing mitochondrial problems in the near future.
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Affiliation(s)
- Sara Darbandi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
| | - Mahsa Darbandi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
| | | | - Mohammad Reza Sadeghi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
| | - Safaa Al-Hasani
- Reproductive Medicine Unit, University of Schleswig-Holstein, Luebeck, Germany.
| | - Ashok Agarwal
- Center for Reproductive Medicine, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.
| | - Abolfazl Shirazi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
| | - Mahnaz Heidari
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran. M.@avicenna.ar.ir
| | - Mohammad Mehdi Akhondi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
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Mitochondrial Haplotypes Influence Metabolic Traits in Porcine Transmitochondrial Cybrids. Sci Rep 2015; 5:13118. [PMID: 26285652 PMCID: PMC4541322 DOI: 10.1038/srep13118] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 07/16/2015] [Indexed: 12/24/2022] Open
Abstract
In farm animals, mitochondrial DNA mutations exist widely across breeds and individuals. In order to identify differences among mtDNA haplotypes, two porcine transmitochondrial cybrids were generated by fusion of a Lantang pig cell line devoid of mitochondrial DNA with enucleated cytoplasm from either a Large White pig or a Xiang pig harboring potentially divergent mitochondrial haplotypes. These cybrid cells were subjected to mitochondrial genome sequencing, copy number detecting and analysis of biochemical traits including succinate dehydrogenase (SDH) activity, ATP content and susceptibility to reactive oxygen species (ROS). The Lantang and Xiang mitochondrial genomes were highly homologous with only 18 polymorphic sites, and differed radically from the Large White with 201 and 198 mutations respectively. The Large White and Xiang cybrids exhibited similar mtDNA copy numbers and different values among biochemical traits, generated greater ROS production (P < 0.05) and less SDH activity (P < 0.05) and a lesser ATP content (P < 0.05). The results show that functional differences exist between cybrid cells which differ in mitochondrial genomic background. In conclusion, transmitochondrial cybrids provide the first direct evidence on pig biochemical traits linking different mitochondrial genome haplotypes.
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Jang DH, Lampe JW, Becker LB. The Potential Application of Mitochondrial Medicine in Toxicologic Poisoning. J Med Toxicol 2015; 11:201-7. [PMID: 25907836 PMCID: PMC4469712 DOI: 10.1007/s13181-015-0478-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The advancement of biomolecular techniques has continued to advance in the area of mitochondrial medicine. This has allowed clinicians and researchers to more effectively study the bioenergetics of the mitochondria in various disease states. One potential technique in mitochondrial medicine is the generation of cytoplasmic hybrids. A cytoplasmic hybrid or cybrid are created by introducing mitochondrial DNA (mtDNA) of interest into cells depleted of mtDNA. A cybrid is therefore a hybrid cell that mixes the nuclear genome from one cell with the mitochondrial genes from another cell. Cybrids are currently utilized in mitochondrial research to demonstrate mitochondrial involvement in a wide range of diseases that include diabetes, Parkinson's disease and inherited diseases. At this time the use of cybrids to study toxicologic poisoning is limited and offers a potential avenue of research in this area.
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Affiliation(s)
- David H Jang
- Center for Resuscitation Science and Center for Mitochondrial and Epigenomic Medicine, Department of Emergency Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA,
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6
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Cannon MV, Irwin MH, Pinkert CA. Mitochondrially-Imported RNA in Drug Discovery. Drug Dev Res 2015; 76:61-71. [DOI: 10.1002/ddr.21241] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 12/14/2014] [Indexed: 12/15/2022]
Affiliation(s)
| | | | - Carl A. Pinkert
- Department of Pathobiology; Auburn University; Auburn AL USA
- Department of Biology; The University of Alabama; Tuscaloosa AL USA
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7
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Mitochondrial-nuclear genome interactions in non-alcoholic fatty liver disease in mice. Biochem J 2014; 461:223-32. [PMID: 24758559 DOI: 10.1042/bj20131433] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
NAFLD (non-alcoholic fatty liver disease) involves significant changes in liver metabolism characterized by oxidative stress, lipid accumulation and fibrogenesis. Mitochondrial dysfunction and bioenergetic defects also contribute to NAFLD. In the present study, we examined whether differences in mtDNA influence NAFLD. To determine the role of mitochondrial and nuclear genomes in NAFLD, MNX (mitochondrial-nuclear exchange) mice were fed an atherogenic diet. MNX mice have mtDNA from C57BL/6J mice on a C3H/HeN nuclear background and vice versa. Results from MNX mice were compared with wild-type C57BL/6J and C3H/HeN mice fed a control or atherogenic diet. Mice with the C57BL/6J nuclear genome developed more macrosteatosis, inflammation and fibrosis compared with mice containing the C3H/HeN nuclear genome when fed the atherogenic diet. These changes were associated with parallel alterations in inflammation and fibrosis gene expression in wild-type mice, with intermediate responses in MNX mice. Mice with the C57BL/6J nuclear genome had increased State 4 respiration, whereas MNX mice had decreased State 3 respiration and RCR (respiratory control ratio) when fed the atherogenic diet. Complex IV activity and most mitochondrial biogenesis genes were increased in mice with the C57BL/6J nuclear or mitochondrial genome, or both fed the atherogenic diet. These results reveal new interactions between mitochondrial and nuclear genomes and support the concept that mtDNA influences mitochondrial function and metabolic pathways implicated in NAFLD.
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Yu G, Tian J, Yin J, Li Q, Zhao X. Incompatibility of nucleus and mitochondria causes xenomitochondrial cybrid unviable across human, mouse, and pig cells. Anim Biotechnol 2014; 25:139-49. [PMID: 24555799 DOI: 10.1080/10495398.2013.841709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The nucleus and mitochondria are on correlative dependence; they interact in the process of protein transportation and energy metabolism. The compatibility of nucleus and mitochondria is essential for interspecies somatic cell nuclear transfer (iSCNT) and xenomitochondrial cybrid. In order to test the compatibility of nucleus and mitochondria among human, mouse, and pig cells, we compared the performances of cybrids that fused inter- and intra-species. The ρ0 cells from human and pig cell lines were created as nucleus donors which were transfected with GFP-neo for cell selective system in advance, and mitochondria donor cells were labeled by Mitochondria-RFP. Human and mouse platelets were also used as a mitochondrial donor. Results indicated that all interspecies cybrids declined to die in 2-4 d after the cell fusion in the selection medium, while intraspecies cybrid cells survived and formed stable clones. As a conclusion, the incompatibility between nucleus and mitochondria is the critical factor for the formation of interspecies cybrids.
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Affiliation(s)
- Guanghui Yu
- a National Engineering Laboratory for Animal Breeding, Ministry of Agricultural Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science and Technology , China Agricultural University , Beijing , China
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Menezes MJ, Riley LG, Christodoulou J. Mitochondrial respiratory chain disorders in childhood: Insights into diagnosis and management in the new era of genomic medicine. Biochim Biophys Acta Gen Subj 2014; 1840:1368-79. [DOI: 10.1016/j.bbagen.2013.12.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2013] [Revised: 12/10/2013] [Accepted: 12/18/2013] [Indexed: 12/26/2022]
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González-Vioque E, Bornstein B, Gallardo ME, Fernández-Moreno MÁ, Garesse R. The pathogenicity scoring system for mitochondrial tRNA mutations revisited. Mol Genet Genomic Med 2013; 2:107-14. [PMID: 24689073 PMCID: PMC3960052 DOI: 10.1002/mgg3.47] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 09/27/2013] [Accepted: 10/09/2013] [Indexed: 11/14/2022] Open
Abstract
Confirming the pathogenicity of mitochondrial tRNA point mutations is one of the classical challenges in the field of mitochondrial medicine. In addition to genetic and functional studies, the evaluation of a genetic change using a pathogenicity scoring system is extremely useful to discriminate between disease-causing mutations from neutral polymorphisms. The pathogenicity scoring system is very robust for confirming pathogenicity, especially of mutations that show impaired activity in functional studies. However, mutations giving normal results using the same functional approaches are disregarded, and this compromises the power of the system to rule out pathogenicity. We propose to include a new criterion in the pathogenicity scoring systems regarding mutations which fail to show any mitochondrial defect in functional studies. To evaluate this proposal we characterized two mutations, m.8296A>G and m.8347A>G, in the mitochondrial tRNALys gene (MT-TK) using trans-mitochondrial cybrid analysis. m.8347A>G mutation severely impairs oxidative phosphorylation, suggesting that it is highly pathogenic. By contrast, the behavior of cybrids homoplasmic for the m.8296A>G mutation is similar to cybrids containing wild-type mitochondrial DNA (mtDNA). The results indicate that including not only positive but also negative outcomes of functional studies in the scoring system is critical for facilitating the diagnosis of this complex group of diseases.
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Affiliation(s)
- Emiliano González-Vioque
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Universidad Autónoma de Madrid 28029, Madrid, Spain ; Laboratorio de Enfermedades Mitocondriales, Instituto de Investigación Sanitaria Hospital 12 de Octubre (i+12) Madrid, Spain
| | - Belén Bornstein
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Universidad Autónoma de Madrid 28029, Madrid, Spain ; Servicio de Bioquímica, Instituto de Investigación Sanitaria Puerta de Hierro Majadahonda Madrid, Spain
| | - María Esther Gallardo
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Universidad Autónoma de Madrid 28029, Madrid, Spain ; Laboratorio de Enfermedades Mitocondriales, Instituto de Investigación Sanitaria Hospital 12 de Octubre (i+12) Madrid, Spain
| | - Miguel Ángel Fernández-Moreno
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Universidad Autónoma de Madrid 28029, Madrid, Spain ; Laboratorio de Enfermedades Mitocondriales, Instituto de Investigación Sanitaria Hospital 12 de Octubre (i+12) Madrid, Spain
| | - Rafael Garesse
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Universidad Autónoma de Madrid 28029, Madrid, Spain ; Laboratorio de Enfermedades Mitocondriales, Instituto de Investigación Sanitaria Hospital 12 de Octubre (i+12) Madrid, Spain
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Bird MJ, Thorburn DR, Frazier AE. Modelling biochemical features of mitochondrial neuropathology. Biochim Biophys Acta Gen Subj 2013; 1840:1380-92. [PMID: 24161927 DOI: 10.1016/j.bbagen.2013.10.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 08/29/2013] [Accepted: 10/11/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND The neuropathology of mitochondrial disease is well characterised. However, pathophysiological mechanisms at the level of biochemistry and cell biology are less clear. Progress in this area has been hampered by the limited accessibility of neurologically relevant material for analysis. SCOPE OF REVIEW Here we discuss the recent development of a variety of model systems that have greatly extended our capacity to understand the biochemical features associated with mitochondrial neuropathology. These include animal and cell based models, with mutations in both nuclear and mitochondrial DNA encoded genes, which aim to recapitulate the neuropathology and cellular biochemistry of mitochondrial diseases. MAJOR CONCLUSIONS Analysis of neurological tissue and cells from these models suggests that although there is no unifying mode of pathogenesis, dysfunction of the oxidative phosphorylation (OXPHOS) system is often central. This can be associated with altered reactive oxygen species (ROS) generation, disruption of the mitochondrial membrane potential (ΔΨm) and inadequate ATP synthesis. Thus, other cellular processes such as calcium (Ca(2+)) homeostasis, cellular signaling and mitochondrial morphology could be altered, ultimately compromising viability of neuronal cells. GENERAL SIGNIFICANCE Mechanisms of neuronal dysfunction in mitochondrial disease are only just beginning to be characterised, are system dependent and complex, and not merely driven by energy deficiency. The diversity of pathogenic mechanisms emphasises the need for characterisation in a wide range of models, as different therapeutic strategies are likely to be needed for different diseases. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.
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Affiliation(s)
- Matthew J Bird
- The Murdoch Childrens Research Institute, The Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia
| | - David R Thorburn
- The Murdoch Childrens Research Institute, The Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia; Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Australia
| | - Ann E Frazier
- The Murdoch Childrens Research Institute, The Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia.
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McCormick E, Place E, Falk MJ. Molecular genetic testing for mitochondrial disease: from one generation to the next. Neurotherapeutics 2013; 10:251-61. [PMID: 23269497 PMCID: PMC3625386 DOI: 10.1007/s13311-012-0174-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Molecular genetic diagnostic testing for mitochondrial disease has evolved continually since the first genetic basis for a clinical mitochondrial disease syndrome was identified in the late 1980s. Owing to global limitations in both knowledge and technology, few individuals, even among those with strong clinical or biochemical evidence of mitochondrial respiratory chain dysfunction, ever received a definitive molecular diagnosis prior to 2005. Clinically available genetic diagnostic testing options improved by 2006 to include sequencing and deletion analysis of an increasing number of individual nuclear genes linked to mitochondrial disease, genome-wide microarray analysis for chromosomal copy number abnormalities, and mitochondrial DNA whole genome sequence analysis. To assess the collective effect of these tests on the genetic diagnosis of suspected mitochondrial disease, we report here results from a retrospective review of the diagnostic yield in patients evaluated from 2008 to 2011 in the Mitochondrial-Genetics Diagnostic Clinic at The Children's Hospital of Philadelphia. Among 152 patients aged 6 weeks to 81 years referred for clinical evaluation of multisystem presentations concerning for suspected mitochondrial disease, a genetic etiology was established that confirmed definite mitochondrial disease in 16.4% and excluded primary mitochondrial disease in 9.2%. Substantial diagnostic challenges remain owing to the clinical difficulty and frank low yield of a priori selecting individual nuclear genes to sequence based on particular symptomatic or biochemical manifestations of suspected mitochondrial disease. These findings highlight the particular utility of massively parallel nuclear exome sequencing technologies, whose benefits and limitations are explored relative to the clinical genetic diagnostic evaluation of mitochondrial disease.
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Affiliation(s)
- Elizabeth McCormick
- />Divisions of Human Genetics and Child Development and Metabolic Disease, Department of Pediatrics, The Children’s Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 USA
| | - Emily Place
- />Divisions of Human Genetics and Child Development and Metabolic Disease, Department of Pediatrics, The Children’s Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 USA
- />Department of Ophthalmology, Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA USA
| | - Marni J. Falk
- />Divisions of Human Genetics and Child Development and Metabolic Disease, Department of Pediatrics, The Children’s Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104 USA
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13
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Kelly RD, Rodda AE, Dickinson A, Mahmud A, Nefzger CM, Lee W, Forsythe JS, Polo JM, Trounce IA, McKenzie M, Nisbet DR, St. John JC. Mitochondrial DNA Haplotypes Define Gene Expression Patterns in Pluripotent and Differentiating Embryonic Stem Cells. Stem Cells 2013; 31:703-16. [DOI: 10.1002/stem.1313] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 11/22/2012] [Accepted: 11/28/2012] [Indexed: 01/07/2023]
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Yu M, Wan Y, Zou Q. Somatic mutations of the mitochondrial genome in Chinese patients with Ewing sarcoma. Hum Pathol 2013; 44:1350-6. [PMID: 23375644 DOI: 10.1016/j.humpath.2012.11.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Revised: 11/09/2012] [Accepted: 11/13/2012] [Indexed: 12/16/2022]
Abstract
Somatic mutations in mitochondrial DNA (mtDNA) have been long proposed to drive initiation and progression of human malignancies. Our previous study revealed a high prevalence of somatic mutations in the D-loop region of mtDNA in Ewing sarcoma (EWS). However, it is unclear whether somatic mutations also occur in the coding regions of mtDNA in EWS. To test this possibility, in the present study, we sequenced the whole mitochondrial genome from 20 cases of EWS specimens and their corresponding peripheral blood samples. We identified a total of 6 somatic mutations in the mtDNA coding regions in our EWS series, and 5 of them were missense or frame-shift mutations that have the potential to directly influence proper mitochondrial function. In combination with our earlier observations on the D-loop fragment, 70% (14/20) of EWS tissues appeared to harbor somatic mtDNA mutations. Among the identified 25 somatic mutations, 19 (76%) were located in the D-loop control region, 1 (4%) was in the sequence of the tRNA(Val) gene, 1 (4%) was in the mitochondrial ATP synthase subunit 6 gene, and 4 (16%) occurred in genes encoding components of the mitochondrial respiratory complexes. In addition, patients carrying somatic mtDNA mutations did not show significant association with their clinicopathologic characteristics. Together, these findings suggest that somatic mtDNA mutations occur in both protein coding and noncoding regions of mtDNA, which may play critical roles in the pathogenesis of EWS and should be further explored for its possible use as a novel marker for monitoring EWS occurrence and advancement.
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Affiliation(s)
- Man Yu
- Ontario Cancer Institute/Princess Margaret Hospital, University Health Network and University of Toronto, Toronto, M5G 2M9 Ontario, Canada.
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Dunn DA, Cannon MV, Irwin MH, Pinkert CA. Animal models of human mitochondrial DNA mutations. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1820:601-7. [PMID: 21854831 PMCID: PMC3249501 DOI: 10.1016/j.bbagen.2011.08.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 08/03/2011] [Accepted: 08/05/2011] [Indexed: 12/21/2022]
Abstract
BACKGROUND Mutations in mitochondrial DNA (mtDNA) cause a variety of pathologic states in human patients. Development of animal models harboring mtDNA mutations is crucial to elucidating pathways of disease and as models for preclinical assessment of therapeutic interventions. SCOPE OF REVIEW This review covers the knowledge gained through animal models of mtDNA mutations and the strategies used to produce them. Animals derived from spontaneous mtDNA mutations, somatic cell nuclear transfer (SCNT), nuclear translocation of mitochondrial genes followed by mitochondrial protein targeting (allotopic expression), mutations in mitochondrial DNA polymerase gamma, direct microinjection of exogenous mitochondria, and cytoplasmic hybrid (cybrid) embryonic stem cells (ES cells) containing exogenous mitochondria (transmitochondrial cells) are considered. MAJOR CONCLUSIONS A wide range of strategies have been developed and utilized in attempts to mimic human mtDNA mutation in animal models. Use of these animals in research studies has shed light on mechanisms of pathogenesis in mitochondrial disorders, yet methods for engineering specific mtDNA sequences are still in development. GENERAL SIGNIFICANCE Research animals containing mtDNA mutations are important for studies of the mechanisms of mitochondrial disease and are useful for the development of clinical therapies. This article is part of a Special Issue entitled Biochemistry of Mitochondria.
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Affiliation(s)
| | | | | | - Carl A. Pinkert
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, AL 36849 USA
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Induction of the permeability transition pore in cells depleted of mitochondrial DNA. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1860-6. [PMID: 22402226 DOI: 10.1016/j.bbabio.2012.02.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 02/16/2012] [Accepted: 02/21/2012] [Indexed: 02/08/2023]
Abstract
Respiratory complexes are believed to play a role in the function of the mitochondrial permeability transition pore (PTP), whose dysregulation affects the process of cell death and is involved in a variety of diseases, including cancer and degenerative disorders. We investigated here the PTP in cells devoid of mitochondrial DNA (ρ(0) cells), which lack respiration and constitute a model for the analysis of mitochondrial involvement in several pathological conditions. We observed that mitochondria of ρ(0) cells maintain a membrane potential and that this is readily dissipated after displacement of hexokinase (HK) II from the mitochondrial surface by treatment with either the drug clotrimazole or with a cell-permeant HK II peptide, or by placing ρ(0) cells in a medium without serum and glucose. The PTP inhibitor cyclosporin A (CsA) could decrease the mitochondrial depolarization induced by either HK II displacement or by nutrient depletion. We also found that a fraction of the kinases ERK1/2 and GSK3α/β is located in the mitochondrial matrix of ρ(0) cells, and that glucose and serum deprivation caused concomitant ERK1/2 inhibition and GSK3α/β activation with the ensuing phosphorylation of cyclophilin D, the mitochondrial target of CsA. GSK3α/β inhibition with indirubin-3'-oxime decreased PTP-induced cell death in ρ(0) cells following nutrient ablation. These findings indicate that ρ(0) cells are equipped with a functioning PTP, whose regulatory mechanisms are similar to those observed in cancer cells, and suggest that escape from PTP opening is a survival factor in this model of mitochondrial diseases. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012).
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An impaired mitochondrial electron transport chain increases retention of the hypoxia imaging agent diacetylbis(4-methylthiosemicarbazonato)copperII. Proc Natl Acad Sci U S A 2011; 109:47-52. [PMID: 22173633 DOI: 10.1073/pnas.1116227108] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Radiolabeled diacetylbis(4-methylthiosemicarbazonato)copper(II) [Cu(II)(atsm)] is an effective positron-emission tomography imaging agent for myocardial ischemia, hypoxic tumors, and brain disorders with regionalized oxidative stress, such as mitochondrial myopathy, encephalopathy, and lactic acidosis with stroke-like episodes (MELAS) and Parkinson's disease. An excessively elevated reductive state is common to these conditions and has been proposed as an important mechanism affecting cellular retention of Cu from Cu(II)(atsm). However, data from whole-cell models to demonstrate this mechanism have not yet been provided. The present study used a unique cell culture model, mitochondrial xenocybrids, to provide whole-cell mechanistic data on cellular retention of Cu from Cu(II)(atsm). Genetic incompatibility between nuclear and mitochondrial encoded subunits of the mitochondrial electron transport chain (ETC) in xenocybrid cells compromises normal function of the ETC. As a consequence of this impairment to the ETC we show xenocybrid cells upregulate glycolytic ATP production and accumulate NADH. Compared to control cells the xenocybrid cells retained more Cu after being treated with Cu(II)(atsm). By transfecting the cells with a metal-responsive element reporter construct the increase in Cu retention was shown to involve a Cu(II)(atsm)-induced increase in intracellular bioavailable Cu specifically within the xenocybrid cells. Parallel experiments using cells grown under hypoxic conditions confirmed that a compromised ETC and elevated NADH levels contribute to increased cellular retention of Cu from Cu(II)(atsm). Using these cell culture models our data demonstrate that compromised ETC function, due to the absence of O(2) as the terminal electron acceptor or dysfunction of individual components of the ETC, is an important determinant in driving the intracellular dissociation of Cu(II)(atsm) that increases cellular retention of the Cu.
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Chiaratti MR, Meirelles FV, Wells D, Poulton J. Therapeutic treatments of mtDNA diseases at the earliest stages of human development. Mitochondrion 2011; 11:820-8. [DOI: 10.1016/j.mito.2010.11.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 11/29/2010] [Indexed: 11/25/2022]
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Cannon MV, Takeda K, Pinkert CA. Mitochondrial biology in reproduction. Reprod Med Biol 2011; 10:251-258. [PMID: 29662358 DOI: 10.1007/s12522-011-0101-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2011] [Accepted: 06/22/2011] [Indexed: 11/28/2022] Open
Abstract
Mitochondrial biology plays an important role in the reproductive process, with influence on germ cell development and quality as well as embryonic development and reproductive success. This review outlines the role of mitochondrial genetics and function in reproductive biology, including a discussion of general mitochondrial function, genetics and germline transmission. Also highlighted are the mitochondrial morphologic changes that occur during oogenesis and the role these changes play in the mitochondrial bottleneck that influences the distribution of deleterious mitochondrial genomes to offspring. The review covers the influence of mitochondria in embryonic stem cell and induced pluripotent stem cell biology and development. Lastly, the role of mitochondrial biology in assisted reproductive techniques is discussed.
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Affiliation(s)
| | - Kumiko Takeda
- National Institute of Livestock and Grassland Science, NARO Tsukuba Japan
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Amarnath D, Choi I, Moawad AR, Wakayama T, Campbell KHS. Nuclear-cytoplasmic incompatibility and inefficient development of pig-mouse cytoplasmic hybrid embryos. Reproduction 2011; 142:295-307. [PMID: 21555359 DOI: 10.1530/rep-11-0044] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Inter-species somatic cell nuclear transfer (iSCNT) embryos usually fail to develop to the blastocyst stage and beyond due to incomplete reprogramming of donor cell. We evaluated whether using a karyoplast that would require less extensive reprogramming such as an embryonic blastomere or the meiotic spindle from metaphase II oocytes would provide additional insight into the development of iSCNT embryos. Our results showed that karyoplasts of embryonic or oocyte origin are no different from somatic cells; all iSCNT embryos, irrespective of karyoplast origin, were arrested during early development. We hypothesized that nuclear-cytoplasmic incompatibility could be another reason for failure of embryonic development from iSCNT. We used pig-mouse cytoplasmic hybrids as a model to address nuclear-cytoplasmic incompatibility in iSCNT embryos. Fertilized murine zygotes were reconstructed by fusing with porcine cytoplasts of varying cytoplasmic volumes (1/10 (small) and 1/5 (large) total volume of mouse zygote). The presence of pig cytoplasm significantly reduced the development of mouse zygotes to the blastocyst stage compared with control embryos at 120 h post-human chorionic gondotropin (41 vs 6 vs 94%, P<0.05; 1/10, 1/5, control respectively). While mitochondrial DNA copy numbers remained relatively unchanged, expression of several important genes namely Tfam, Polg, Polg2, Mfn2, Slc2a3 (Glut3), Slc2a1 (Glut1), Bcl2, Hspb1, Pou5f1 (Oct4), Nanog, Cdx2, Gata3, Tcfap2c, mt-Cox1 and mt-Cox2 was significantly reduced in cytoplasmic hybrids compared with control embryos. These results demonstrate that the presence of even a small amount of porcine cytoplasm is detrimental to murine embryo development and suggest that a range of factors are likely to contribute to the failure of inter-species nuclear transfer embryos.
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Affiliation(s)
- Dasari Amarnath
- Animal Development and Biotechnology Group, School of Biosciences, The University of Nottingham, Sutton Bonington, Loughborough, Leicestershire, LE12 5RD, UK
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Shaik NA, Lone WG, Khan IA, Vaidya S, Rao KP, Kodati VL, Hasan Q. Detection of somatic mutations and germline polymorphisms in mitochondrial DNA of uterine fibroids patients. Genet Test Mol Biomarkers 2011; 15:537-41. [PMID: 21453057 DOI: 10.1089/gtmb.2010.0255] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To identify the role of mitochondrial DNA (mtDNA) mutations in uterine fibroids patients, genomic DNA isolated from paired myometrium and fibroid tissues was screened for mutations. The present study represents the first investigation to report that 10.4% of uterine fibroids cases had either mtDNA mutations or polymorphisms or both. Among the 14 mitochondrial sequence variants identified, seven are somatic mutations (A3327C, G3352A, G3376A, G3380A, G3421A, T15312G, and C15493G) and the remaining (G3316A, C3342A, C3442T, T10205A, A10188G, A10229C, and A10301T) are gene polymorphisms. Somatic mutations were both homo- and heteroplasmic in nature. Of the seven somatic mutations located in the MTND1 and MTCYB genes, five (71.42%) are nonsynonymous in nature, whereas four (57.14%) of the polymorphisms located in MTND1 and MTND3 genes are found to be nonsynonymous. Sequence variants such as G3380A, G3421A, T15312G, G3376A, and G3316A have been earlier described in different human pathologies, but the remaining are novel ones. Mitochondrial somatic mutations and polymorphisms may predispose women to an earlier onset of degenerative cellular processes, which impair oxidative phosphorylation capacity and thereby promote tumorigenesis in uterine smooth muscle cells. Detection of mtDNA sequence variations in fibroid patients raises the need for larger case-control studies to screen the whole mitochondrial genome and evaluate as a future diagnostic biomarker in fibroid patients.
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Affiliation(s)
- Noor Ahmad Shaik
- Department of Genetics and Molecular Medicine, Vasavi Medical and Research Centre, Hyderabad, India
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22
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Gianazza E, Eberini I, Sensi C, Barile M, Vergani L, Vanoni MA. Energy matters: mitochondrial proteomics for biomedicine. Proteomics 2011; 11:657-74. [PMID: 21241019 DOI: 10.1002/pmic.201000412] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 09/22/2010] [Accepted: 11/03/2010] [Indexed: 12/16/2022]
Abstract
This review compiles results of medical relevance from mitochondrial proteomics, grouped either according to the type of disease - genetic or degenerative - or to the involved mechanism - oxidative stress or apoptosis. The findings are commented in the light of our current understanding of uniformity/variability in cell responses to different stimuli. Specificities in the conceptual and technical approaches to human mitochondrial proteomics are also outlined.
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Affiliation(s)
- Elisabetta Gianazza
- Dipartimento di Scienze Farmacologiche, Università degli Studi di Milano, Milano, Italy.
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Chiaratti MR, Ferreira CR, Meirelles FV, Méo SC, Perecin F, Smith LC, Ferraz ML, de Sá Filho MF, Gimenes LU, Baruselli PS, Gasparrini B, Garcia JM. Xenooplasmic transfer between buffalo and bovine enables development of homoplasmic offspring. Cell Reprogram 2010; 12:231-6. [PMID: 20698765 DOI: 10.1089/cell.2009.0076] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Nuclear-mitochondrial incompatibilities may be responsible for the development failure reported in embryos and fetuses produced by interspecies somatic cell nuclear transfer (iSCNT). Herein we performed xenooplasmic transfer (XOT) by introducing 10 to 15% of buffalo ooplasm into bovine zygotes to assess its effect on the persistence of buffalo mitochondrial DNA (mtDNA). Blastocyst rates were not compromised by XOT in comparison to both in vitro fertilized embryos and embryos produced by transfer of bovine ooplasm into bovine zygotes. Moreover, offspring were born after transfer of XOT embryos to recipient cows. Buffalo mtDNA introduced in zygotes was still present at the blastocyst stage (8.3 vs. 9.3%, p = 0.11), indicating unaltered heteroplasmy during early development. Nonetheless, no vestige of buffalo mtDNA was found in offspring, indicating a drift to homoplasmy during later stages of development. In conclusion, we show that the buffalo mtDNA introduced by XOT into a bovine zygote do not compromise embryo development. On the other hand, buffalo mtDNA was not inherited by offspring indicating a possible failure in the process of interspecies mtDNA replication.
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Cannon MV, Dunn DA, Irwin MH, Brooks AI, Bartol FF, Trounce IA, Pinkert CA. Xenomitochondrial mice: investigation into mitochondrial compensatory mechanisms. Mitochondrion 2010; 11:33-9. [PMID: 20638486 DOI: 10.1016/j.mito.2010.07.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 06/08/2010] [Accepted: 07/08/2010] [Indexed: 01/02/2023]
Abstract
Xenomitochondrial mice, harboring evolutionarily divergent Mus terricolor mitochondrial DNA (mtDNA) on a Mus musculus domesticus nuclear background (B6NTac(129S6)-mt(M. terricolor)/Capt; line D7), were subjected to molecular and phenotypic analyses. No overt in vivo phenotype was identified in contrast to in vitro xenomitochondrial cybrid studies. Microarray analyses revealed differentially expressed genes in xenomitochondrial mice, though none were directly involved in mitochondrial function. qRT-PCR revealed upregulation of mt-Co2 in xenomitochondrial mice. These results illustrate that cellular compensatory mechanisms for mild mitochondrial dysfunction alter mtDNA gene expression at a proteomic and/or translational level. Understanding these mechanisms will facilitate the development of therapeutics for mitochondrial disorders.
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Affiliation(s)
- M V Cannon
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Alabama 36849, United States
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25
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Takeda K, Kaneyama K, Tasai M, Akagi S, Takahashi S, Yonai M, Kojima T, Onishi A, Tagami T, Nirasawa K, Hanada H. Characterization of a donor mitochondrial DNA transmission bottleneck in nuclear transfer derived cow lineages. Mol Reprod Dev 2008; 75:759-65. [PMID: 18033682 DOI: 10.1002/mrd.20837] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In embryos derived by nuclear-transfer (NT), fusion of donor cells with recipient oocytes resulted in varying patterns of mitochondrial DNA (mtDNA) transmission in NT animals. Distribution of donor cell mtDNA (D-mtDNA) found in offspring of NT-derived founders may also vary from donor cell and host embryo heteroplasmy to host embryo homoplasmy. Here we examined the transmission of mtDNA from NT cows to G(1) offspring. Eleven NT founder cows were produced by fusion of enucleated oocytes (Holstein/Japanese Black) with Jersey/ Holstein oviduct epithelial cells, or Holstein/Japanese Black cumulus cells. Transmission of mtDNA was analyzed by PCR mediated single-strand conformation polymorphism of the D-loop region. In six of seven animals sampled postmortem, heteroplasmy were detected in various tissues, while D-mtDNA could not be detected in blood or hair samples from four live animals. The average proportion of D-mtDNA detected in one NT cow was 7.6%, and those in other cows were <5%. Heteroplasmic NT cows (n = 6) generated a total 12 G(1) offspring. Four of 12 G(1) offspring exhibited high percentages of D-mtDNA populations (range 17-51%). The remaining eight G(1) offspring had slightly or undetectable D-mtDNA (<5%). Generally, a genetic bottleneck in the female germ-line should favor a homoplasmic state. However, proportions of some G(1) offspring maintained heteroplasmy with a much higher percentage of D-mtDNA than their NT dams, which may also reflect a segregation distortion caused by the proposed mitochondrial bottleneck. These results demonstrate that D-mtDNA in NT cows is transmitted to G(1) offspring with varying efficiencies.
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Affiliation(s)
- Kumiko Takeda
- National Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan.
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26
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Eukaryotic complex I: functional diversity and experimental systems to unravel the assembly process. Mol Genet Genomics 2008; 280:93-110. [DOI: 10.1007/s00438-008-0350-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2008] [Accepted: 05/01/2008] [Indexed: 10/21/2022]
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Eichhorn-Mulligan K, Cestari DM. The genetics of leber hereditary optic neuropathy--prototype of an inherited optic neuropathy with mitochondrial dysfunction. Semin Ophthalmol 2008; 23:27-37. [PMID: 18214789 DOI: 10.1080/08820530701745207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Leber Hereditary Optic Neuropathy is a maternally inherited condition that is characterized by acute or subacute bilateral loss of vision, usually in otherwise healthy young individuals. Several point mutations in the mitochondrial genome have been identified in patients with the condition. Scientific advances into a better understanding of the molecular pathogenesis have been hampered by the lack of an animal model for the disease. This article summarizes what is known about the clinical features, epidemiology and genetics of Leber Hereditary Optic Neuropathy and reviews recent experiments scientists have used in addressing the many unanswered questions that remain about the disease.
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Affiliation(s)
- Knut Eichhorn-Mulligan
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA.
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Bowles EJ, Campbell KHS, St John JC. Nuclear Transfer: Preservation of a Nuclear Genome at the Expense of Its Associated mtDNA Genome(s). Curr Top Dev Biol 2007; 77:251-90. [PMID: 17222707 DOI: 10.1016/s0070-2153(06)77010-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Nuclear transfer technology has uses across theoretical and applied applications, but advances are restricted by continued poor success rates and health problems associated with live offspring. Development of reconstructed embryos is dependent upon numerous interlinking factors relating both to the donor cell and the recipient oocyte. For example, abnormalities in gene expression following somatic cell nuclear transfer (SCNT) have been linked with an inability of the oocyte cytoplasm to sufficiently epigenetically reprogram the nucleus. Furthermore, influences on the propagation of mitochondria and mitochondrial DNA (mtDNA) could be of great importance in determining the early developmental potential of NT embryos and contributing to their genetic identity. mtDNA encodes some of the subunits of the electron transfer chain, responsible for cellular ATP production. The remaining subunits and those factors required for mtDNA replication, transcription and translation are encoded by the nucleus, necessitating precise intergenomic communication. Additionally, regulation of mtDNA copy number, via the processes of mtDNA transcription and replication, is essential for normal preimplantation embryo development and differentiation. Unimaternal transmission following natural fertilization usually results in the presence of a single identical population of mtDNA, homoplasmy. Heteroplasmy can result if mixed populations of mtDNA genomes co-exist. Many abnormalities observed in NT embryos, fetuses, and offspring may be caused by deficiencies in OXPHOS, perhaps resulting in part from heteroplasmic mtDNA populations. Additionally, incompatibilities between the somatic nucleus and the cytoplast may be exacerbated by increased genetic divergence between the two genomes. It is important to ensure that the nucleus is capable of sufficiently regulating mtDNA, requiring a level of compatibility between the two genomes, which may be a function of evolutionary distance. We suggest that abnormal expression of factors such as TFAM and POLG in NT embryos will prematurely drive mtDNA replication, hence impacting on early development.
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Affiliation(s)
- Emma J Bowles
- The Mitochondrial and Reproductive Genetics Group, The Division of Medical Sciences, The Medical School, The University of Birmingham, Birmingham B15 2TT, United Kingdom
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