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Ayala DA, Matarazzo A, Seaberg BL, Patel M, Tijerina E, Matthews C, Bizi G, Brown A, Ta A, Rimer M, Srinivasan R. Heterogeneous brain region-specific responses to astrocytic mitochondrial DNA damage in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.29.596517. [PMID: 38853966 PMCID: PMC11160752 DOI: 10.1101/2024.05.29.596517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Astrocytes use Ca 2+ signals to regulate multiple aspects of normal and pathological brain function. Astrocytes display context-specific diversity in their functions, and in their response to noxious stimuli between brain regions. Indeed, astrocytic mitochondria have emerged as key players in governing astrocytic functional heterogeneity, given their ability to dynamically adapt their morphology to regional demands on their ATP generation and Ca 2+ buffering functions. Although there is reciprocal regulation between mitochondrial dynamics and mitochondrial Ca 2+ signaling in astrocytes, the extent of this regulation into the rich diversity of astrocytes in different brain regions remains largely unexplored. Brain-wide, experimentally induced mitochondrial DNA (mtDNA) loss in astrocytes showed that mtDNA integrity is critical for proper astrocyte function, however, few insights into possible diverse responses to this noxious stimulus from astrocytes in different brain areas were reported in these experiments. To selectively damage mtDNA in astrocytes in a brain-region-specific manner, we developed a novel adeno-associated virus (AAV)-based tool, Mito-PstI, which expresses the restriction enzyme PstI, specifically in astrocytic mitochondria. Here, we applied Mito-PstI to two distinct brain regions, the dorsolateral striatum, and the hippocampal dentate gyrus, and we show that Mito-PstI can induce astrocytic mtDNA loss in vivo , but with remarkable brain-region-dependent differences on mitochondrial dynamics, spontaneous Ca 2+ fluxes and astrocytic as well as microglial reactivity. Thus, AAV-Mito-PstI is a novel tool to explore the relationship between astrocytic mitochondrial network dynamics and astrocytic mitochondrial Ca 2+ signaling in a brain-region-selective manner.
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2
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Chang Y, Liu B, Jiang Y, Cao D, Liu Y, Li Y. Induce male sterility by CRISPR/Cas9-mediated mitochondrial genome editing in tobacco. Funct Integr Genomics 2023; 23:205. [PMID: 37335501 DOI: 10.1007/s10142-023-01136-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 06/21/2023]
Abstract
Genome editing has become more and more popular in animal and plant systems following the emergence of CRISPR/Cas9 technology. However, target sequence modification by CRISPR/Cas9 has not been reported in the plant mitochondrial genome, mtDNA. In plants, a type of male sterility known as cytoplasmic male sterility (CMS) has been associated with certain mitochondrial genes, but few genes have been confirmed by direct mitochondrial gene-targeted modifications. Here, the CMS-associated gene (mtatp9) in tobacco was cleaved using mitoCRISPR/Cas9 with a mitochondrial localization signal. The male-sterile mutant, with aborted stamens, exhibited only 70% of the mtDNA copy number of the wild type and exhibited an altered percentage of heteroplasmic mtatp9 alleles; otherwise, the seed setting rate of the mutant flowers was zero. Transcriptomic analyses showed that glycolysis, tricarboxylic acid cycle metabolism and the oxidative phosphorylation pathway, which are all related to aerobic respiration, were inhibited in stamens of the male-sterile gene-edited mutant. In addition, overexpression of the synonymous mutations dsmtatp9 could restore fertility to the male-sterile mutant. Our results strongly suggest that mutation of mtatp9 causes CMS and that mitoCRISPR/Cas9 can be used to modify the mitochondrial genome of plants.
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Affiliation(s)
- Yanzi Chang
- Qinghai Province Key Laboratory of Crop Molecular Breeding, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, 810008, Qinghai, China
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Xining, 810008, Qinghai, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Baolong Liu
- Qinghai Province Key Laboratory of Crop Molecular Breeding, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, 810008, Qinghai, China
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Xining, 810008, Qinghai, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanyan Jiang
- Qinghai Province Key Laboratory of Crop Molecular Breeding, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, 810008, Qinghai, China
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Xining, 810008, Qinghai, China
- Academy of Agriculture and Forestry Science, Qinghai University, Xining, 810008, Qinghai, China
| | - Dong Cao
- Qinghai Province Key Laboratory of Crop Molecular Breeding, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, 810008, Qinghai, China
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Xining, 810008, Qinghai, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yongju Liu
- Qinghai Province Key Laboratory of Crop Molecular Breeding, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, 810008, Qinghai, China
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Xining, 810008, Qinghai, China
| | - Yun Li
- Qinghai Province Key Laboratory of Crop Molecular Breeding, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, 810008, Qinghai, China.
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Xining, 810008, Qinghai, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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3
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Falabella M, Minczuk M, Hanna MG, Viscomi C, Pitceathly RDS. Gene therapy for primary mitochondrial diseases: experimental advances and clinical challenges. Nat Rev Neurol 2022; 18:689-698. [PMID: 36257993 DOI: 10.1038/s41582-022-00715-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2022] [Indexed: 11/09/2022]
Abstract
The variable clinical and biochemical manifestations of primary mitochondrial diseases (PMDs), and the complexity of mitochondrial genetics, have proven to be a substantial barrier to the development of effective disease-modifying therapies. Encouraging data from gene therapy trials in patients with Leber hereditary optic neuropathy and advances in DNA editing techniques have raised expectations that successful clinical transition of genetic therapies for PMDs is feasible. However, obstacles to the clinical application of genetic therapies in PMDs remain; the development of innovative, safe and effective genome editing technologies and vectors will be crucial to their future success and clinical approval. In this Perspective, we review progress towards the genetic treatment of nuclear and mitochondrial DNA-related PMDs. We discuss advances in mitochondrial DNA editing technologies alongside the unique challenges to targeting mitochondrial genomes. Last, we consider ongoing trials and regulatory requirements.
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Affiliation(s)
- Micol Falabella
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Michael G Hanna
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Queen Square Centre for Neuromuscular Diseases, The National Hospital for Neurology and Neurosurgery, London, UK
| | - Carlo Viscomi
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- CESNE - Center for the Study of Neurodegeneration, University of Padova, Padova, Italy
| | - Robert D S Pitceathly
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK.
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Queen Square Centre for Neuromuscular Diseases, The National Hospital for Neurology and Neurosurgery, London, UK.
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4
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McKnight CL, Low YC, Elliott DA, Thorburn DR, Frazier AE. Modelling Mitochondrial Disease in Human Pluripotent Stem Cells: What Have We Learned? Int J Mol Sci 2021; 22:7730. [PMID: 34299348 PMCID: PMC8306397 DOI: 10.3390/ijms22147730] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/16/2021] [Accepted: 07/16/2021] [Indexed: 02/06/2023] Open
Abstract
Mitochondrial diseases disrupt cellular energy production and are among the most complex group of inherited genetic disorders. Affecting approximately 1 in 5000 live births, they are both clinically and genetically heterogeneous, and can be highly tissue specific, but most often affect cell types with high energy demands in the brain, heart, and kidneys. There are currently no clinically validated treatment options available, despite several agents showing therapeutic promise. However, modelling these disorders is challenging as many non-human models of mitochondrial disease do not completely recapitulate human phenotypes for known disease genes. Additionally, access to disease-relevant cell or tissue types from patients is often limited. To overcome these difficulties, many groups have turned to human pluripotent stem cells (hPSCs) to model mitochondrial disease for both nuclear-DNA (nDNA) and mitochondrial-DNA (mtDNA) contexts. Leveraging the capacity of hPSCs to differentiate into clinically relevant cell types, these models permit both detailed investigation of cellular pathomechanisms and validation of promising treatment options. Here we catalogue hPSC models of mitochondrial disease that have been generated to date, summarise approaches and key outcomes of phenotypic profiling using these models, and discuss key criteria to guide future investigations using hPSC models of mitochondrial disease.
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Affiliation(s)
- Cameron L. McKnight
- Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, VIC 3052, Australia; (C.L.M.); (Y.C.L.); (D.A.E.); (D.R.T.)
- Department of Paediatrics, University of Melbourne, Parkville, VIC 3052, Australia
| | - Yau Chung Low
- Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, VIC 3052, Australia; (C.L.M.); (Y.C.L.); (D.A.E.); (D.R.T.)
- Department of Paediatrics, University of Melbourne, Parkville, VIC 3052, Australia
| | - David A. Elliott
- Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, VIC 3052, Australia; (C.L.M.); (Y.C.L.); (D.A.E.); (D.R.T.)
- Department of Paediatrics, University of Melbourne, Parkville, VIC 3052, Australia
| | - David R. Thorburn
- Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, VIC 3052, Australia; (C.L.M.); (Y.C.L.); (D.A.E.); (D.R.T.)
- Department of Paediatrics, University of Melbourne, Parkville, VIC 3052, Australia
- Victorian Clinical Genetics Services, Royal Children’s Hospital, Parkville, VIC 3052, Australia
| | - Ann E. Frazier
- Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, VIC 3052, Australia; (C.L.M.); (Y.C.L.); (D.A.E.); (D.R.T.)
- Department of Paediatrics, University of Melbourne, Parkville, VIC 3052, Australia
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5
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Fu L, Luo YX, Liu Y, Liu H, Li HZ, Yu Y. Potential of Mitochondrial Genome Editing for Human Fertility Health. Front Genet 2021; 12:673951. [PMID: 34354734 PMCID: PMC8329452 DOI: 10.3389/fgene.2021.673951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 06/28/2021] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial DNA (mtDNA) encodes vital proteins and RNAs for the normal functioning of the mitochondria. Mutations in mtDNA leading to mitochondrial dysfunction are relevant to a large spectrum of diseases, including fertility disorders. Since mtDNA undergoes rather complex processes during gametogenesis and fertilization, clarification of the changes and functions of mtDNA and its essential impact on gamete quality and fertility during this process is of great significance. Thanks to the emergence and rapid development of gene editing technology, breakthroughs have been made in mitochondrial genome editing (MGE), offering great potential for the treatment of mtDNA-related diseases. In this review, we summarize the features of mitochondria and their unique genome, emphasizing their inheritance patterns; illustrate the role of mtDNA in gametogenesis and fertilization; and discuss potential therapies based on MGE as well as the outlook in this field.
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Affiliation(s)
- Lin Fu
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology and Key Laboratory of Assisted Reproduction, Ministry of Education, Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
| | - Yu-Xin Luo
- Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-sen University, Guangzhou, China
| | - Ying Liu
- Food Inspection and Quarantine Technology Center of Shenzhen Customs District, FICS, Shenzhen, China
| | - Hui Liu
- Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Hong-Zhen Li
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology and Key Laboratory of Assisted Reproduction, Ministry of Education, Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
| | - Yang Yu
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology and Key Laboratory of Assisted Reproduction, Ministry of Education, Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China.,Stem Cell Research Center, Peking University Third Hospital, Beijing, China
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6
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Mitochondrial targeted meganuclease as a platform to eliminate mutant mtDNA in vivo. Nat Commun 2021; 12:3210. [PMID: 34050192 PMCID: PMC8163834 DOI: 10.1038/s41467-021-23561-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 04/26/2021] [Indexed: 11/24/2022] Open
Abstract
Diseases caused by heteroplasmic mitochondrial DNA mutations have no effective treatment or cure. In recent years, DNA editing enzymes were tested as tools to eliminate mutant mtDNA in heteroplasmic cells and tissues. Mitochondrial-targeted restriction endonucleases, ZFNs, and TALENs have been successful in shifting mtDNA heteroplasmy, but they all have drawbacks as gene therapy reagents, including: large size, heterodimeric nature, inability to distinguish single base changes, or low flexibility and effectiveness. Here we report the adaptation of a gene editing platform based on the I-CreI meganuclease known as ARCUS®. These mitochondrial-targeted meganucleases (mitoARCUS) have a relatively small size, are monomeric, and can recognize sequences differing by as little as one base pair. We show the development of a mitoARCUS specific for the mouse m.5024C>T mutation in the mt-tRNAAla gene and its delivery to mice intravenously using AAV9 as a vector. Liver and skeletal muscle show robust elimination of mutant mtDNA with concomitant restoration of mt-tRNAAla levels. We conclude that mitoARCUS is a potential powerful tool for the elimination of mutant mtDNA. Heteroplasmic mitochondrial DNA mutations lack effective treatments. Here the authors adapt I-CreI meganuclease to target the mitochondria and specifically-eliminate mtDNA with a m.5024C>T mutation in the mttRNA Ala gene.
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7
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Hussain SRA, Yalvac ME, Khoo B, Eckardt S, McLaughlin KJ. Adapting CRISPR/Cas9 System for Targeting Mitochondrial Genome. Front Genet 2021; 12:627050. [PMID: 33889176 PMCID: PMC8055930 DOI: 10.3389/fgene.2021.627050] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 03/01/2021] [Indexed: 12/21/2022] Open
Abstract
Gene editing of the mitochondrial genome using the CRISPR-Cas9 system is highly challenging mainly due to sub-efficient delivery of guide RNA and Cas9 enzyme complexes into the mitochondria. In this study, we were able to perform gene editing in the mitochondrial DNA by appending an NADH-ubiquinone oxidoreductase chain 4 (ND4) targeting guide RNA to an RNA transport-derived stem loop element (RP-loop) and expressing the Cas9 enzyme with a preceding mitochondrial localization sequence. We observe mitochondrial colocalization of RP-loop gRNA and a marked reduction of ND4 expression in the cells carrying a 11205G variant in their ND4 sequence coincidently decreasing the mtDNA levels. This proof-of-concept study suggests that a stem-loop element added sgRNA can be transported to the mitochondria and functionally interact with Cas9 to mediate sequence-specific mtDNA cleavage. Using this novel approach to target the mtDNA, our results provide further evidence that CRISPR-Cas9-mediated gene editing might potentially be used to treat mitochondrial-related diseases.
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Affiliation(s)
- Syed-Rehan A Hussain
- Center for Molecular and Human Genetics, Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, United States.,Center for Clinical and Translational Research, Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, United States
| | - Mehmet E Yalvac
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Benedict Khoo
- Center for Molecular and Human Genetics, Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, United States
| | - Sigrid Eckardt
- Center for Molecular and Human Genetics, Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, United States
| | - K John McLaughlin
- Center for Molecular and Human Genetics, Abigail Wexner Research Institute, Nationwide Children's Hospital, Columbus, OH, United States
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8
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Prole DL, Chinnery PF, Jones NS. Visualizing, quantifying, and manipulating mitochondrial DNA in vivo. J Biol Chem 2020; 295:17588-17601. [PMID: 33454000 PMCID: PMC7762947 DOI: 10.1074/jbc.rev120.015101] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 10/15/2020] [Indexed: 01/06/2023] Open
Abstract
Mitochondrial DNA (mtDNA) encodes proteins and RNAs that support the functions of mitochondria and thereby numerous physiological processes. Mutations of mtDNA can cause mitochondrial diseases and are implicated in aging. The mtDNA within cells is organized into nucleoids within the mitochondrial matrix, but how mtDNA nucleoids are formed and regulated within cells remains incompletely resolved. Visualization of mtDNA within cells is a powerful means by which mechanistic insight can be gained. Manipulation of the amount and sequence of mtDNA within cells is important experimentally and for developing therapeutic interventions to treat mitochondrial disease. This review details recent developments and opportunities for improvements in the experimental tools and techniques that can be used to visualize, quantify, and manipulate the properties of mtDNA within cells.
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Affiliation(s)
- David L Prole
- Department of Mathematics, Imperial College London, London, United Kingdom; Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Patrick F Chinnery
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom; Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom.
| | - Nick S Jones
- Department of Mathematics, Imperial College London, London, United Kingdom.
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9
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Stable retention of chloramphenicol-resistant mtDNA to rescue metabolically impaired cells. Sci Rep 2020; 10:14328. [PMID: 32868785 PMCID: PMC7459123 DOI: 10.1038/s41598-020-71199-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 08/10/2020] [Indexed: 12/27/2022] Open
Abstract
The permanent transfer of specific mtDNA sequences into mammalian cells could generate improved models of mtDNA disease and support future cell-based therapies. Previous studies documented multiple biochemical changes in recipient cells shortly after mtDNA transfer, but the long-term retention and function of transferred mtDNA remains unknown. Here, we evaluate mtDNA retention in new host cells using ‘MitoPunch’, a device that transfers isolated mitochondria into mouse and human cells. We show that newly introduced mtDNA is stably retained in mtDNA-deficient (ρ0) recipient cells following uridine-free selection, although exogenous mtDNA is lost from metabolically impaired, mtDNA-intact (ρ+) cells. We then introduced a second selective pressure by transferring chloramphenicol-resistant mitochondria into chloramphenicol-sensitive, metabolically impaired ρ+ mouse cybrid cells. Following double selection, recipient cells with mismatched nuclear (nDNA) and mitochondrial (mtDNA) genomes retained transferred mtDNA, which replaced the endogenous mutant mtDNA and improved cell respiration. However, recipient cells with matched mtDNA-nDNA failed to retain transferred mtDNA and sustained impaired respiration. Our results suggest that exogenous mtDNA retention in metabolically impaired ρ+ recipients depends on the degree of recipient mtDNA-nDNA co-evolution. Uncovering factors that stabilize exogenous mtDNA integration will improve our understanding of in vivo mitochondrial transfer and the interplay between mitochondrial and nuclear genomes.
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10
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Zekonyte U, Bacman SR, Moraes CT. DNA-editing enzymes as potential treatments for heteroplasmic mtDNA diseases. J Intern Med 2020; 287:685-697. [PMID: 32176378 PMCID: PMC7260085 DOI: 10.1111/joim.13055] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/04/2019] [Accepted: 12/11/2019] [Indexed: 12/13/2022]
Abstract
Mutations in the mitochondrial genome are the cause of many debilitating neuromuscular disorders. Currently, there is no cure or treatment for these diseases, and symptom management is the only relief doctors can provide. Although supplements and vitamins are commonly used in treatment, they provide little benefit to the patient and are only palliative. This is why gene therapy is a promising research topic to potentially treat and, in theory, even cure diseases caused by mutations in the mitochondrial DNA (mtDNA). Mammalian cells contain approximately a thousand copies of mtDNA, which can lead to a phenomenon called heteroplasmy, where both wild-type and mutant mtDNA molecules co-exist within the cell. Disease only manifests once the per cent of mutant mtDNA reaches a high threshold (usually >80%), which causes mitochondrial dysfunction and reduced ATP production. This is a useful feature to take advantage of for gene therapy applications, as not every mutant copy of mtDNA needs to be eliminated, but only enough to shift the heteroplasmic ratio below the disease threshold. Several DNA-editing enzymes have been used to shift heteroplasmy in cell culture and mice. This review provides an overview of these enzymes and discusses roadblocks of applying these to gene therapy in humans.
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Affiliation(s)
- U Zekonyte
- From the, Graduate Program in Human Genetics and Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - S R Bacman
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - C T Moraes
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
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11
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Klucnika A, Ma H. Mapping and editing animal mitochondrial genomes: can we overcome the challenges? Philos Trans R Soc Lond B Biol Sci 2019; 375:20190187. [PMID: 31787046 DOI: 10.1098/rstb.2019.0187] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The animal mitochondrial genome, although small, can have a big impact on health and disease. Non-pathogenic sequence variation among mitochondrial DNA (mtDNA) haplotypes influences traits including fertility, healthspan and lifespan, whereas pathogenic mutations are linked to incurable mitochondrial diseases and other complex conditions like ageing, diabetes, cancer and neurodegeneration. However, we know very little about how mtDNA genetic variation contributes to phenotypic differences. Infrequent recombination, the multicopy nature and nucleic acid-impenetrable membranes present significant challenges that hamper our ability to precisely map mtDNA variants responsible for traits, and to genetically modify mtDNA so that we can isolate specific mutants and characterize their biochemical and physiological consequences. Here, we summarize the past struggles and efforts in developing systems to map and edit mtDNA. We also assess the future of performing forward and reverse genetic studies on animal mitochondrial genomes. This article is part of the theme issue 'Linking the mitochondrial genotype to phenotype: a complex endeavour'.
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Affiliation(s)
- Anna Klucnika
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK.,Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
| | - Hansong Ma
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK.,Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
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12
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Al Khatib I, Shutt TE. Advances Towards Therapeutic Approaches for mtDNA Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1158:217-246. [PMID: 31452143 DOI: 10.1007/978-981-13-8367-0_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mitochondria maintain and express their own genome, referred to as mtDNA, which is required for proper mitochondrial function. While mutations in mtDNA can cause a heterogeneous array of disease phenotypes, there is currently no cure for this collection of diseases. Here, we will cover characteristics of the mitochondrial genome important for understanding the pathology associated with mtDNA mutations, and review recent approaches that are being developed to treat and prevent mtDNA disease. First, we will discuss mitochondrial replacement therapy (MRT), where mitochondria from a healthy donor replace maternal mitochondria harbouring mutant mtDNA. In addition to ethical concerns surrounding this procedure, MRT is only applicable in cases where the mother is known or suspected to carry mtDNA mutations. Thus, there remains a need for other strategies to treat patients with mtDNA disease. To this end, we will also discuss several alternative means to reduce the amount of mutant mtDNA present in cells. Such methods, referred to as heteroplasmy shifting, have proven successful in animal models. In particular, we will focus on the approach of targeting engineered endonucleases to specifically cleave mutant mtDNA. Together, these approaches offer hope to prevent the transmission of mtDNA disease and potentially reduce the impact of mtDNA mutations.
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Affiliation(s)
- Iman Al Khatib
- Deparments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Timothy E Shutt
- Deparments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
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13
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Hoitzing H, Gammage PA, Haute LV, Minczuk M, Johnston IG, Jones NS. Energetic costs of cellular and therapeutic control of stochastic mitochondrial DNA populations. PLoS Comput Biol 2019; 15:e1007023. [PMID: 31242175 PMCID: PMC6615642 DOI: 10.1371/journal.pcbi.1007023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 07/09/2019] [Accepted: 04/11/2019] [Indexed: 12/28/2022] Open
Abstract
The dynamics of the cellular proportion of mutant mtDNA molecules is crucial for mitochondrial diseases. Cellular populations of mitochondria are under homeostatic control, but the details of the control mechanisms involved remain elusive. Here, we use stochastic modelling to derive general results for the impact of cellular control on mtDNA populations, the cost to the cell of different mtDNA states, and the optimisation of therapeutic control of mtDNA populations. This formalism yields a wealth of biological results, including that an increasing mtDNA variance can increase the energetic cost of maintaining a tissue, that intermediate levels of heteroplasmy can be more detrimental than homoplasmy even for a dysfunctional mutant, that heteroplasmy distribution (not mean alone) is crucial for the success of gene therapies, and that long-term rather than short intense gene therapies are more likely to beneficially impact mtDNA populations.
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Affiliation(s)
- Hanne Hoitzing
- Department of Mathematics, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Payam A. Gammage
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, CB2 0XY, United Kingdom
- CRUK Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | - Lindsey Van Haute
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, CB2 0XY, United Kingdom
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, CB2 0XY, United Kingdom
| | - Iain G. Johnston
- Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen, Norway
- Alan Turing Institute, London, United Kingdom
| | - Nick S. Jones
- Department of Mathematics, Imperial College London, London, SW7 2AZ, United Kingdom
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14
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Bian WP, Chen YL, Luo JJ, Wang C, Xie SL, Pei DS. Knock-In Strategy for Editing Human and Zebrafish Mitochondrial DNA Using Mito-CRISPR/Cas9 System. ACS Synth Biol 2019; 8:621-632. [PMID: 30955321 DOI: 10.1021/acssynbio.8b00411] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mitochondria DNA (mtDNA) editing tool, zinc finger nucleases (ZFNs), transcription activator-like effector nuclease (TALENs), and clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9 (CRISPR/Cas9) system, is a promising approach for the treatment of mtDNA diseases by eliminating mutant mitochondrial genomes. However, there have been no reports of repairing the mutant mtDNA with homologous recombination strategy to date. Here, we show a mito-CRISPR/Cas9 system that mito-Cas9 protein can specifically target mtDNA and reduce mtDNA copy number in both human cells and zebrafish. An exogenous single-stranded DNA with short homologous arm was knocked into the targeting loci accurately, and this mutagenesis could be steadily transmitted to F1 generation of zebrafish. Moreover, we found some major factors involved in nuclear DNA repair were upregulated significantly by the mito-CRISPR/Cas9 system. Taken together, our data suggested that the mito-CRISPR/Cas9 system could be a useful method to edit mtDNA by knock-in strategy, providing a potential therapy for the treatment of inherited mitochondrial diseases.
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Affiliation(s)
- Wan-Ping Bian
- Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
| | - Yan-Ling Chen
- Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
| | - Juan-Juan Luo
- Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
| | - Chao Wang
- Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
| | - Shao-Lin Xie
- Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
| | - De-Sheng Pei
- Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
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15
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Zhang Y, Long C, Bassel-Duby R, Olson EN. Myoediting: Toward Prevention of Muscular Dystrophy by Therapeutic Genome Editing. Physiol Rev 2018; 98:1205-1240. [PMID: 29717930 DOI: 10.1152/physrev.00046.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Muscular dystrophies represent a large group of genetic disorders that significantly impair quality of life and often progress to premature death. There is no effective treatment for these debilitating diseases. Most therapies, developed to date, focus on alleviating the symptoms or targeting the secondary effects, while the underlying gene mutation is still present in the human genome. The discovery and application of programmable nucleases for site-specific DNA double-stranded breaks provides a powerful tool for precise genome engineering. In particular, the CRISPR/Cas system has revolutionized the genome editing field and is providing a new path for disease treatment by targeting the disease-causing genetic mutations. In this review, we provide a historical overview of genome-editing technologies, summarize the most recent advances, and discuss potential strategies and challenges for permanently correcting genetic mutations that cause muscular dystrophies.
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Affiliation(s)
- Yu Zhang
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Chengzu Long
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Rhonda Bassel-Duby
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Eric N Olson
- Department of Molecular Biology, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center and Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
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16
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Abstract
Mitochondrial myopathies are progressive muscle conditions caused primarily by the impairment of oxidative phosphorylation (OXPHOS) in the mitochondria. This causes a deficit in energy production in the form of adenosine triphosphate (ATP), particularly in skeletal muscle. The diagnosis of mitochondrial myopathy is reliant on the combination of numerous techniques including traditional histochemical, immunohistochemical, and biochemical testing combined with the fast-emerging molecular genetic techniques, namely next-generation sequencing (NGS). This has allowed for the diagnosis to become more effective in terms of determining causative or novel genes. However, there are currently no effective or disease-modifying treatments available for the vast majority of patients with mitochondrial myopathies. Existing therapeutic options focus on the symptomatic management of disease manifestations. An increasing number of clinical trials have investigated the therapeutic effects of various vitamins, cofactors, and small molecules, though these trials have failed to show definitive outcome measures for clinical practice thus far. In addition, new molecular strategies, specifically mtZFNs and mtTALENs, that cause beneficial heteroplasmic shifts in cell lines harboring varying pathogenic mtDNA mutations offer hope for the future. Moreover, recent developments in the reproductive options for patients with mitochondrial myopathies mean that for some families, the possibility of preventing transmission of the mutation to the next generation is now possible.
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Affiliation(s)
- Syeda T Ahmed
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Lyndsey Craven
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Oliver M Russell
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
- MRC Centre for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, UK
| | - Amy E Vincent
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.
- MRC Centre for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, UK.
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17
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Clinical syndromes associated with mtDNA mutations: where we stand after 30 years. Essays Biochem 2018; 62:235-254. [DOI: 10.1042/ebc20170097] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 05/29/2018] [Accepted: 05/30/2018] [Indexed: 01/16/2023]
Abstract
The landmark year 1988 can be considered as the birthdate of mitochondrial medicine, when the first pathogenic mutations affecting mtDNA were associated with human diseases. Three decades later, the field still expands and we are not ‘scraping the bottom of the barrel’ yet. Despite the tremendous progress in terms of molecular characterization and genotype/phenotype correlations, for the vast majority of cases we still lack a deep understanding of the pathogenesis, good models to study, and effective therapeutic options. However, recent technological advances including somatic cell reprogramming to induced pluripotent stem cells (iPSCs), organoid technology, and tailored endonucleases provide unprecedented opportunities to fill these gaps, casting hope to soon cure the major primary mitochondrial phenotypes reviewed here. This group of rare diseases represents a key model for tackling the pathogenic mechanisms involving mitochondrial biology relevant to much more common disorders that affect our currently ageing population, such as diabetes and metabolic syndrome, neurodegenerative and inflammatory disorders, and cancer.
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18
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Advances in methods for reducing mitochondrial DNA disease by replacing or manipulating the mitochondrial genome. Essays Biochem 2018; 62:455-465. [PMID: 29950320 PMCID: PMC6056713 DOI: 10.1042/ebc20170113] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/23/2018] [Accepted: 05/03/2018] [Indexed: 11/25/2022]
Abstract
Mitochondrial DNA (mtDNA) is a multi-copy genome whose cell copy number varies depending on tissue type. Mutations in mtDNA can cause a wide spectrum of diseases. Mutated mtDNA is often found as a subset of the total mtDNA population in a cell or tissue, a situation known as heteroplasmy. As mitochondrial dysfunction only presents after a certain level of heteroplasmy has been acquired, ways to artificially reduce or replace the mutated species have been attempted. This review addresses recent approaches and advances in this field, focusing on the prevention of pathogenic mtDNA transfer via mitochondrial donation techniques such as maternal spindle transfer and pronuclear transfer in which mutated mtDNA in the oocyte or fertilized embryo is substituted with normal copies of the mitochondrial genome. This review also discusses the molecular targeting and cleavage of pathogenic mtDNA to shift heteroplasmy using antigenomic therapy and genome engineering techniques including Zinc-finger nucleases and transcription activator-like effector nucleases. Finally, it considers CRISPR technology and the unique difficulties that mitochondrial genome editing presents.
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19
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Verechshagina N, Nikitchina N, Yamada Y, Harashima Н, Tanaka M, Orishchenko K, Mazunin I. Future of human mitochondrial DNA editing technologies. Mitochondrial DNA A DNA Mapp Seq Anal 2018; 30:214-221. [PMID: 29764251 DOI: 10.1080/24701394.2018.1472773] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
ATP and other metabolites, which are necessary for the development, maintenance, and functioning of bodily cells are all synthesized in the mitochondria. Multiple copies of the genome, present within the mitochondria, together with its maternal inheritance, determine the clinical manifestation and spreading of mutations in mitochondrial DNA (mtDNA). The main obstacle in the way of thorough understanding of mitochondrial biology and the development of gene therapy methods for mitochondrial diseases is the absence of systems that allow to directly change mtDNA sequence. Here, we discuss existing methods of manipulating the level of mtDNA heteroplasmy, as well as the latest systems, that could be used in the future as tools for human mitochondrial genome editing.
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Affiliation(s)
- N Verechshagina
- a Laboratory of Molecular Genetics Technologies , Immanuel Kant Baltic Federal University , Kaliningrad , Russia
| | - N Nikitchina
- a Laboratory of Molecular Genetics Technologies , Immanuel Kant Baltic Federal University , Kaliningrad , Russia
| | - Y Yamada
- b Faculty of Pharmaceutical Sciences, Laboratory for Molecular Design of Pharmaceutics , Hokkaido University , Sapporo , Japan
| | - Н Harashima
- b Faculty of Pharmaceutical Sciences, Laboratory for Molecular Design of Pharmaceutics , Hokkaido University , Sapporo , Japan
| | - M Tanaka
- c Department for Health and Longevity Research , National Institutes of Biomedical Innovation, Health and Nutrition , Ibaraki City, Osaka , Japan.,d Department of Neurology , Juntendo University Graduate School of Medicine , Tokyo , Japan
| | - K Orishchenko
- a Laboratory of Molecular Genetics Technologies , Immanuel Kant Baltic Federal University , Kaliningrad , Russia.,e Laboratory of Cell Technologies , Institute of Cytology and Genetics SB RAS , Novosibirsk , Russia
| | - I Mazunin
- a Laboratory of Molecular Genetics Technologies , Immanuel Kant Baltic Federal University , Kaliningrad , Russia
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20
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Guerra F, Arbini AA, Moro L. Mitochondria and cancer chemoresistance. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:686-699. [DOI: 10.1016/j.bbabio.2017.01.012] [Citation(s) in RCA: 178] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 01/07/2023]
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21
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Chan SSL. Inherited mitochondrial genomic instability and chemical exposures. Toxicology 2017; 391:75-83. [PMID: 28756246 DOI: 10.1016/j.tox.2017.07.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/12/2017] [Accepted: 07/24/2017] [Indexed: 12/21/2022]
Abstract
There are approximately 1500 proteins that are needed for mitochondrial structure and function, most of which are encoded in the nuclear genome (Calvo et al., 2006). Each mitochondrion has its own genome (mtDNA), which in humans encodes 13 polypeptides, 22 tRNAs and 2 rRNAs required for oxidative phosphorylation. The mitochondrial genome of humans and most vertebrates is approximately 16.5kbp, double-stranded, circular, with few non-coding bases. Thus, maintaining mtDNA stability, that is, the ability of the cell to maintain adequate levels of mtDNA template for oxidative phosphorylation is essential and can be impacted by the level of mtDNA mutation currently within the cell or mitochondrion, but also from errors made during normal mtDNA replication, defects in mitochondrial quality control mechanisms, and exacerbated by exposures to exogenous and/or endogenous genotoxic agents. In this review, we expand on the origins and consequences of mtDNA instability, the current state of research regarding the mechanisms by which mtDNA instability can be overcome by cellular and chemical interventions, and the future of research and treatments for mtDNA instability.
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Affiliation(s)
- Sherine S L Chan
- Drug Discovery and Biomedical Sciences, College of Pharmacy, Medical University of South Carolina, Charleston, SC 29425, United States; Neuroene Therapeutics, Mt. Pleasant, SC 29464, United States.
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22
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Moretton A, Morel F, Macao B, Lachaume P, Ishak L, Lefebvre M, Garreau-Balandier I, Vernet P, Falkenberg M, Farge G. Selective mitochondrial DNA degradation following double-strand breaks. PLoS One 2017; 12:e0176795. [PMID: 28453550 PMCID: PMC5409072 DOI: 10.1371/journal.pone.0176795] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 04/17/2017] [Indexed: 12/22/2022] Open
Abstract
Mitochondrial DNA (mtDNA) can undergo double-strand breaks (DSBs), caused by defective replication, or by various endogenous or exogenous sources, such as reactive oxygen species, chemotherapeutic agents or ionizing radiations. MtDNA encodes for proteins involved in ATP production, and maintenance of genome integrity following DSBs is thus of crucial importance. However, the mechanisms involved in mtDNA maintenance after DSBs remain unknown. In this study, we investigated the consequences of the production of mtDNA DSBs using a human inducible cell system expressing the restriction enzyme PstI targeted to mitochondria. Using this system, we could not find any support for DSB repair of mtDNA. Instead we observed a loss of the damaged mtDNA molecules and a severe decrease in mtDNA content. We demonstrate that none of the known mitochondrial nucleases are involved in the mtDNA degradation and that the DNA loss is not due to autophagy, mitophagy or apoptosis. Our study suggests that a still uncharacterized pathway for the targeted degradation of damaged mtDNA in a mitophagy/autophagy-independent manner is present in mitochondria, and might provide the main mechanism used by the cells to deal with DSBs.
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Affiliation(s)
- Amandine Moretton
- Université Clermont Auvergne, CNRS/IN2P3, Laboratoire de Physique de Clermont, BP 10448, F-63000 Clermont-Ferrand, France
| | - Frédéric Morel
- Université Clermont Auvergne, CNRS/IN2P3, Laboratoire de Physique de Clermont, BP 10448, F-63000 Clermont-Ferrand, France
| | - Bertil Macao
- Institute of Biomedicine, University of Gothenburg, P.O. Box 440, SE-405 30, Gothenburg, Sweden
| | - Philippe Lachaume
- Université Clermont Auvergne, CNRS/IN2P3, Laboratoire de Physique de Clermont, BP 10448, F-63000 Clermont-Ferrand, France
| | - Layal Ishak
- Université Clermont Auvergne, CNRS/IN2P3, Laboratoire de Physique de Clermont, BP 10448, F-63000 Clermont-Ferrand, France
| | - Mathilde Lefebvre
- Université Clermont Auvergne, CNRS/IN2P3, Laboratoire de Physique de Clermont, BP 10448, F-63000 Clermont-Ferrand, France
| | - Isabelle Garreau-Balandier
- Université Clermont Auvergne, CNRS/IN2P3, Laboratoire de Physique de Clermont, BP 10448, F-63000 Clermont-Ferrand, France
| | - Patrick Vernet
- Université Clermont Auvergne, CNRS/IN2P3, Laboratoire de Physique de Clermont, BP 10448, F-63000 Clermont-Ferrand, France
| | - Maria Falkenberg
- Institute of Biomedicine, University of Gothenburg, P.O. Box 440, SE-405 30, Gothenburg, Sweden
| | - Géraldine Farge
- Université Clermont Auvergne, CNRS/IN2P3, Laboratoire de Physique de Clermont, BP 10448, F-63000 Clermont-Ferrand, France
- * E-mail:
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23
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Bruni F, Lightowlers RN, Chrzanowska-Lightowlers ZM. Human mitochondrial nucleases. FEBS J 2017; 284:1767-1777. [PMID: 27926991 PMCID: PMC5484287 DOI: 10.1111/febs.13981] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/22/2016] [Accepted: 11/30/2016] [Indexed: 12/26/2022]
Abstract
Mitochondria are cytosolic organelles that have many essential roles including ATP production via oxidative phosphorylation, apoptosis, iron‐sulfur cluster biogenesis, heme and steroid synthesis, calcium homeostasis, and regulation of cellular redox state. One of the unique features of these organelles is the presence of an extrachromosomal mitochondrial genome (mtDNA), together with all the machinery required to replicate and transcribe mtDNA. The accurate maintenance of mitochondrial gene expression is essential for correct organellar metabolism, and is in part dependent on the levels of mtDNA and mtRNA, which are regulated by balancing synthesis against degradation. It is clear that although a number of mitochondrial nucleases have been identified, not all those responsible for the degradation of DNA or RNA have been characterized. Recent investigations, however, have revealed the contribution that mutations in the genes coding for these enzymes has made to causing pathogenic mitochondrial diseases.
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Affiliation(s)
- Francesco Bruni
- The Wellcome Trust Centre for Mitochondrial Research, The Medical School, Newcastle University, UK
| | - Robert N Lightowlers
- The Wellcome Trust Centre for Mitochondrial Research, The Medical School, Newcastle University, UK
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24
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Sen A, Cox RT. Fly Models of Human Diseases: Drosophila as a Model for Understanding Human Mitochondrial Mutations and Disease. Curr Top Dev Biol 2016; 121:1-27. [PMID: 28057297 DOI: 10.1016/bs.ctdb.2016.07.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mitochondrial diseases are a prevalent, heterogeneous class of diseases caused by defects in oxidative phosphorylation, whose severity depends upon particular genetic mutations. These diseases can be difficult to diagnose, and current therapeutics have limited efficacy, primarily treating only symptoms. Because mitochondria play a pivotal role in numerous cellular functions, especially ATP production, their diminished activity has dramatic physiological consequences. While this in and of itself makes treating mitochondrial disease complex, these organelles contain their own DNA, mtDNA, whose products are required for ATP production, in addition to the hundreds of nucleus-encoded proteins. Drosophila offers a tractable whole-animal model to understand the mechanisms underlying loss of mitochondrial function, the subsequent cellular and tissue damage that results, and how these organelles are inherited. Human and Drosophila mtDNAs encode the same set of products, and the homologous nucleus-encoded genes required for mitochondrial function are conserved. In addition, Drosophila contain sufficiently complex organ systems to effectively recapitulate many basic symptoms of mitochondrial diseases, yet are relatively easy and fast to genetically manipulate. There are several Drosophila models for specific mitochondrial diseases, which have been recently reviewed (Foriel, Willems, Smeitink, Schenck, & Beyrath, 2015). In this review, we highlight the conservation between human and Drosophila mtDNA, the present and future techniques for creating mtDNA mutations for further study, and how Drosophila has contributed to our current understanding of mitochondrial inheritance.
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Affiliation(s)
- A Sen
- Uniformed Services University, Bethesda, MD, United States
| | - R T Cox
- Uniformed Services University, Bethesda, MD, United States.
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25
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Venken KJT, Sarrion-Perdigones A, Vandeventer PJ, Abel NS, Christiansen AE, Hoffman KL. Genome engineering: Drosophila melanogaster and beyond. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 5:233-67. [PMID: 26447401 DOI: 10.1002/wdev.214] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 08/03/2015] [Accepted: 08/20/2015] [Indexed: 12/26/2022]
Abstract
A central challenge in investigating biological phenomena is the development of techniques to modify genomic DNA with nucleotide precision that can be transmitted through the germ line. Recent years have brought a boon in these technologies, now collectively known as genome engineering. Defined genomic manipulations at the nucleotide level enable a variety of reverse engineering paradigms, providing new opportunities to interrogate diverse biological functions. These genetic modifications include controlled removal, insertion, and substitution of genetic fragments, both small and large. Small fragments up to a few kilobases (e.g., single nucleotide mutations, small deletions, or gene tagging at single or multiple gene loci) to large fragments up to megabase resolution can be manipulated at single loci to create deletions, duplications, inversions, or translocations of substantial sections of whole chromosome arms. A specialized substitution of chromosomal portions that presumably are functionally orthologous between different organisms through syntenic replacement, can provide proof of evolutionary conservation between regulatory sequences. Large transgenes containing endogenous or synthetic DNA can be integrated at defined genomic locations, permitting an alternative proof of evolutionary conservation, and sophisticated transgenes can be used to interrogate biological phenomena. Precision engineering can additionally be used to manipulate the genomes of organelles (e.g., mitochondria). Novel genome engineering paradigms are often accelerated in existing, easily genetically tractable model organisms, primarily because these paradigms can be integrated in a rigorous, existing technology foundation. The Drosophila melanogaster fly model is ideal for these types of studies. Due to its small genome size, having just four chromosomes, the vast amount of cutting-edge genetic technologies, and its short life-cycle and inexpensive maintenance requirements, the fly is exceptionally amenable to complex genetic analysis using advanced genome engineering. Thus, highly sophisticated methods developed in the fly model can be used in nearly any sequenced organism. Here, we summarize different ways to perform precise inheritable genome engineering using integrases, recombinases, and DNA nucleases in the D. melanogaster. For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Koen J T Venken
- Department of Biochemistry and Molecular Biology, Verna and Marrs McLean, Houston, TX, USA.,Department of Pharmacology, Baylor College of Medicine, Houston, TX, USA.,Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA.,Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX, USA
| | | | - Paul J Vandeventer
- Department of Biochemistry and Molecular Biology, Verna and Marrs McLean, Houston, TX, USA
| | - Nicholas S Abel
- Department of Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Audrey E Christiansen
- Department of Biochemistry and Molecular Biology, Verna and Marrs McLean, Houston, TX, USA
| | - Kristi L Hoffman
- Department of Biochemistry and Molecular Biology, Verna and Marrs McLean, Houston, TX, USA
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26
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Tischner C, Wenz T. Keep the fire burning: Current avenues in the quest of treating mitochondrial disorders. Mitochondrion 2015; 24:32-49. [DOI: 10.1016/j.mito.2015.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 06/18/2015] [Accepted: 06/24/2015] [Indexed: 12/18/2022]
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27
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Diez-Juan A, Simón C. Converting a Problem into an Opportunity: mtDNA Heteroplasmy Shift. Cell Stem Cell 2015; 16:457-8. [PMID: 25957899 DOI: 10.1016/j.stem.2015.04.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The transmission of mitochondrial DNA (mtDNA) disease from a mother with a heteroplasmic mtDNA mutation to her children is unpredictable. In a recent issue of Cell, Reddy et al. (2015) present the potential for mitochondrial-targeted nucleases to remove mutated mtDNA through the induction of heteroplasmy shift in oocytes and zygotes.
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Affiliation(s)
- Antonio Diez-Juan
- Igenomix, Parc Cientific Valencia University, 46980 Paterna, Valencia, Spain
| | - Carlos Simón
- Igenomix, Parc Cientific Valencia University, 46980 Paterna, Valencia, Spain; Fundación Instituto Valenciano de Infertilidad (FIVI), Department of Obstetrics & Gynecology, School of Medicine, Valencia University and Instituto Universitario IVI/INCLIVA, 46015 Valencia, Spain; Department of Obstetrics and Gynecology, Stanford University, Palo Alto, CA 94304, USA.
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28
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MitoTALEN: A General Approach to Reduce Mutant mtDNA Loads and Restore Oxidative Phosphorylation Function in Mitochondrial Diseases. Mol Ther 2015; 23:1592-9. [PMID: 26159306 DOI: 10.1038/mt.2015.126] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/21/2015] [Indexed: 12/23/2022] Open
Abstract
We have designed mitochondrially targeted transcription activator-like effector nucleases or mitoTALENs to cleave specific sequences in the mitochondrial DNA (mtDNA) with the goal of eliminating mtDNA carrying pathogenic point mutations. To test the generality of the approach, we designed mitoTALENs to target two relatively common pathogenic mtDNA point mutations associated with mitochondrial diseases: the m.8344A>G tRNA(Lys) gene mutation associated with myoclonic epilepsy with ragged red fibers (MERRF) and the m.13513G>A ND5 mutation associated with MELAS/Leigh syndrome. Transmitochondrial cybrid cells harbouring the respective heteroplasmic mtDNA mutations were transfected with the respective mitoTALEN and analyzed after different time periods. MitoTALENs efficiently reduced the levels of the targeted pathogenic mtDNAs in the respective cell lines. Functional assays showed that cells with heteroplasmic mutant mtDNA were able to recover respiratory capacity and oxidative phosphorylation enzymes activity after transfection with the mitoTALEN. To improve the design in the context of the low complexity of mtDNA, we designed shorter versions of the mitoTALEN specific for the MERRF m.8344A>G mutation. These shorter mitoTALENs also eliminated the mutant mtDNA. These reductions in size will improve our ability to package these large sequences into viral vectors, bringing the use of these genetic tools closer to clinical trials.
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