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Brady S, Poulton J, Muller S. Inclusion body myositis: Correcting impaired mitochondrial and lysosomal autophagy as a potential therapeutic strategy. Autoimmun Rev 2024; 23:103644. [PMID: 39306221 DOI: 10.1016/j.autrev.2024.103644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 09/05/2024] [Accepted: 09/17/2024] [Indexed: 09/28/2024]
Abstract
Inclusion body myositis (IBM) is a late onset sporadic myopathy with a characteristic clinical presentation, but as yet unknown aetiology or effective treatment. Typical clinical features are early predominant asymmetric weakness of finger flexor and knee extensor muscles. Muscle biopsy shows endomysial inflammatory infiltrate, mitochondrial changes, and protein aggregation. Proteostasis (protein turnover) appears to be impaired, linked to potentially dysregulated chaperone-mediated autophagy and mitophagy (a type of mitochondrial quality control). In this review, we bring together the most recent clinical and biological data describing IBM. We then address the question of diagnosing this pathology and the relevance of the current biological markers that characterize IBM. In these descriptions, we put a particular emphasis on data related to the deregulation of autophagic processes and to the mitochondrial-lysosomal crosstalk. Finally, after a short description of current treatments, an overview is provided pointing towards novel therapeutic targets and emerging regulatory molecules that are being explored for treating IBM. Special attention is paid to autophagy inhibitors that may offer innovative breakthrough therapies for patients with IBM.
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Affiliation(s)
- Stefen Brady
- Oxford Adult Muscle Service, John Radcliffe Hospital, Oxford University Hospital Trust, Oxford, UK
| | - Joanna Poulton
- Nuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, UK
| | - Sylviane Muller
- CNRS and Strasbourg University Unit Biotechnology and Cell signalling/Strasbourg Drug Discovery and Development Institute (IMS), Strasbourg, France; University of Strasbourg Institute for Advanced Study (USIAS), Strasbourg, France.
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2
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Pasqualotto BA, Nelson A, Deheshi S, Sheldon CA, Vogl AW, Rintoul GL. Impaired mitochondrial morphological plasticity and failure of mitophagy associated with the G11778A mutation of LHON. Biochem Biophys Res Commun 2024; 721:150119. [PMID: 38768545 DOI: 10.1016/j.bbrc.2024.150119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 05/07/2024] [Accepted: 05/13/2024] [Indexed: 05/22/2024]
Abstract
Mitochondrial dynamics were examined in human dermal fibroblasts biopsied from a confirmed Leber's Hereditary Optic Neuropathy (LHON) patient with a homoplasmic G11778A mutation of the mitochondrial genome. Expression of the G11778A mutation did not impart any discernible difference in mitochondrial network morphology using widefield fluorescence microscopy. However, at the ultrastructural level, cells expressing this mutation exhibited an impairment of mitochondrial morphological plasticity when forced to utilize oxidative phosphorylation (OXPHOS) by transition to glucose-free, galactose-containing media. LHON fibroblasts also displayed a transient increase in mitophagy upon transition to galactose media. These results provide new insights into the consequences of the G11778A mutation of LHON and the pathological mechanisms underlying this disease.
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Affiliation(s)
- Bryce A Pasqualotto
- Centre for Cell Biology, Development, and Disease, and the Department of Biological Sciences, Simon Fraser University, Canada
| | - Alexa Nelson
- Centre for Cell Biology, Development, and Disease, and the Department of Biological Sciences, Simon Fraser University, Canada
| | - Samineh Deheshi
- Centre for Cell Biology, Development, and Disease, and the Department of Biological Sciences, Simon Fraser University, Canada
| | - Claire A Sheldon
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Canada
| | - A Wayne Vogl
- Life Sciences Institute and the Department of Cellular & Physiological Sciences, University of British Columbia, Canada
| | - Gordon L Rintoul
- Centre for Cell Biology, Development, and Disease, and the Department of Biological Sciences, Simon Fraser University, Canada.
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3
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Zhou Z, Dai W, Liu T, Shi M, Wei Y, Chen L, Xie Y. Transfer of massive mitochondria from astrocytes reduce propofol neurotoxicity. Neurosci Lett 2024; 818:137542. [PMID: 37926293 DOI: 10.1016/j.neulet.2023.137542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 10/20/2023] [Accepted: 10/26/2023] [Indexed: 11/07/2023]
Abstract
Studies have shown that propofol-induced neurotoxicity is mediated by disruption of mitochondrial fission and fusion, leading to an imbalance in energy supply for developing neurons. Healthy mitochondria released from astrocytes migrate to compromised neurons to mitigate propofol-induced neurotoxicity, yet the precise mechanisms involved require further clarification. In our investigation, primary neurons were incubated with propofol, which decreased ATP synthesis and mitochondrial membrane potential, increased ROS generation and neuronal apoptosis. Notably, astrocytes did not respond to the deleterious effects of propofol. The culture medium of neurons or astrocytes incubated with propofol was collected. It was found that mitochondrial ratio was decreased and mitochondrial function was impaired. Non-contact co-culture of neuro-astrocytes facilitated transcellular mitochondrial transfer in both physiological and propofol interventions, but failed to reverse propofol-induced neurotoxicity. The more pronounced damage to neuronal mitochondria induced by propofol compared to that in astrocytes alludes to secondary injury. Damaged neurons incubated with large, functional extracellular mitochondria derived from astrocytes demonstrates transfer of mitochondria to neurons, effectively reversing propofol-induced neurotoxicity. This discovery presents a novel mitochondrial transfer of neuro-astrocytes crosstalk that contributes to neuroprotection and neurological recovery in neurotoxicity.
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Affiliation(s)
- Zhan Zhou
- Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China.
| | - Weixin Dai
- Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China.
| | - Tianxiao Liu
- Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China.
| | - Min Shi
- Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China.
| | - Yi Wei
- Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China.
| | - Lifei Chen
- Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China.
| | - Yubo Xie
- Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China; Guangxi Key Laboratory of Enhanced Recovery after Surgery for Gastrointestinal Cancer, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China.
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Yang W, Abe S, Tabata Y. Association with cationized gelatin nanospheres enhances cell internalization of mitochondria efficiency. Regen Ther 2023; 24:190-200. [PMID: 37483433 PMCID: PMC10359715 DOI: 10.1016/j.reth.2023.06.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 06/11/2023] [Accepted: 06/24/2023] [Indexed: 07/25/2023] Open
Abstract
The objective of this study is to confirm the methodological feasibility of cationized gelatin nanospheres (cGNS) to enhance the internalization efficiency of mitochondria (Mt) isolated to cells for their increasing functions. The cGNS were simply associated on the surface of Mt by the electrostatic interaction. Different sizes of cGNS were used to allow Mt to associate on the Mt surface (Mt-cGNS). As a control, cationized gelatin (cG) was used to modify the Mt surface (Mt-cG). The Mt-cG and Mt-cGNS prepared were cultured with H9c2 cells to examine their internalization. The internalization efficiency significantly increased by utilizing cGNS. However, there was no significant difference in the internalization efficiency among cGNS with different sizes. After incubation of Mt, Mt-cG, and Mt-cGNS, the superoxide amount and ATP generation were evaluated. Significantly lower superoxide amount and higher ATP amount were observed for the Mt-cGNS group compared with those of non-modified Mt group. It is conceivable that cGNS enhance the cellular internalization of Mt, leading to an improve mitochondrial functions in the recipient cells. In conclusion, cGNS are promising to improve the efficacy in mitochondria internalization.
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Liu L, Li Y, Chen G, Chen Q. Crosstalk between mitochondrial biogenesis and mitophagy to maintain mitochondrial homeostasis. J Biomed Sci 2023; 30:86. [PMID: 37821940 PMCID: PMC10568841 DOI: 10.1186/s12929-023-00975-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 09/13/2023] [Indexed: 10/13/2023] Open
Abstract
Mitochondrial mass and quality are tightly regulated by two essential and opposing mechanisms, mitochondrial biogenesis (mitobiogenesis) and mitophagy, in response to cellular energy needs and other cellular and environmental cues. Great strides have been made to uncover key regulators of these complex processes. Emerging evidence has shown that there exists a tight coordination between mitophagy and mitobiogenesis, and their defects may cause many human diseases. In this review, we will first summarize the recent advances made in the discovery of molecular regulations of mitobiogenesis and mitophagy and then focus on the mechanism and signaling pathways involved in the simultaneous regulation of mitobiogenesis and mitophagy in the response of tissue or cultured cells to energy needs, stress, or pathophysiological conditions. Further studies of the crosstalk of these two opposing processes at the molecular level will provide a better understanding of how the cell maintains optimal cellular fitness and function under physiological and pathophysiological conditions, which holds promise for fighting aging and aging-related diseases.
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Affiliation(s)
- Lei Liu
- Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
- Institute for Stem Cell and Regenerative Medicine, Beijing, China.
| | - Yanjun Li
- Center of Cell Response, State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
| | - Guo Chen
- Center of Cell Response, State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China
| | - Quan Chen
- Center of Cell Response, State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, China.
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6
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Shamsnajafabadi H, MacLaren RE, Cehajic-Kapetanovic J. Current and Future Landscape in Genetic Therapies for Leber Hereditary Optic Neuropathy. Cells 2023; 12:2013. [PMID: 37566092 PMCID: PMC10416882 DOI: 10.3390/cells12152013] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 08/12/2023] Open
Abstract
Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial genetic disease that causes blindness in young adults. Over 50 inherited mitochondrial DNA (mtDNA) variations are associated with LHON; however, more than 95% of cases are caused by one of three missense variations (m.11778 G > A, m.3460 G > A, and m.14484 T > C) encoding for subunits ND4, ND1, and ND6 of the respiration complex I, respectively. These variants remain silent until further and currently poorly understood genetic and environmental factors precipitate the visual loss. The clinical course that ensues is variable, and a convincing treatment for LHON has yet to emerge. In 2015, an antioxidant idebenone (Raxone) received European marketing authorisation to treat visual impairment in patients with LHON, and since then it was introduced into clinical practice in several European countries. Alternative therapeutic strategies, including gene therapy and gene editing, antioxidant and neurotrophic agents, mitochondrial biogenesis, mitochondrial replacement, and stem cell therapies are being investigated in how effective they might be in altering the course of the disease. Allotopic gene therapies are in the most advanced stage of development (phase III clinical trials) whilst most other agents are in phase I or II trials or at pre-clinical stages. This manuscript discusses the phenotype and genotype of the LHON disease with complexities and peculiarities such as incomplete penetrance and gender bias, which have challenged the therapies in development emphasising the most recent use of gene therapy. Furthermore, we review the latest results of the three clinical trials based on adeno-associated viral (AAV) vector-mediated delivery of NADH dehydrogenase subunit 4 (ND4) with mitochondrial targeting sequence, highlighting the differences in the vector design and the rationale behind their use in the allotopic transfer.
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Affiliation(s)
- Hoda Shamsnajafabadi
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University NHS Foundation Trust, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University NHS Foundation Trust, John Radcliffe Hospital, Oxford OX3 9DU, UK
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Mitochondrial membrane proteins and VPS35 orchestrate selective removal of mtDNA. Nat Commun 2022; 13:6704. [PMID: 36344526 PMCID: PMC9640553 DOI: 10.1038/s41467-022-34205-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 10/17/2022] [Indexed: 11/09/2022] Open
Abstract
Understanding the mechanisms governing selective turnover of mutation-bearing mtDNA is fundamental to design therapeutic strategies against mtDNA diseases. Here, we show that specific mtDNA damage leads to an exacerbated mtDNA turnover, independent of canonical macroautophagy, but relying on lysosomal function and ATG5. Using proximity labeling and Twinkle as a nucleoid marker, we demonstrate that mtDNA damage induces membrane remodeling and endosomal recruitment in close proximity to mitochondrial nucleoid sub-compartments. Targeting of mitochondrial nucleoids is controlled by the ATAD3-SAMM50 axis, which is disrupted upon mtDNA damage. SAMM50 acts as a gatekeeper, influencing BAK clustering, controlling nucleoid release and facilitating transfer to endosomes. Here, VPS35 mediates maturation of early endosomes to late autophagy vesicles where degradation occurs. In addition, using a mouse model where mtDNA alterations cause impairment of muscle regeneration, we show that stimulation of lysosomal activity by rapamycin, selectively removes mtDNA deletions without affecting mtDNA copy number, ameliorating mitochondrial dysfunction. Taken together, our data demonstrates that upon mtDNA damage, mitochondrial nucleoids are eliminated outside the mitochondrial network through an endosomal-mitophagy pathway. With these results, we unveil the molecular players of a complex mechanism with multiple potential benefits to understand mtDNA related diseases, inherited, acquired or due to normal ageing.
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Chiaratti MR, Chinnery PF. Modulating mitochondrial DNA mutations: factors shaping heteroplasmy in the germ line and somatic cells. Pharmacol Res 2022; 185:106466. [PMID: 36174964 DOI: 10.1016/j.phrs.2022.106466] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/21/2022] [Accepted: 09/23/2022] [Indexed: 11/30/2022]
Abstract
Until recently it was thought that most humans only harbor one type of mitochondrial DNA (mtDNA), however, deep sequencing and single-cell analysis has shown the converse - that mixed populations of mtDNA (heteroplasmy) are the norm. This is important because heteroplasmy levels can change dramatically during transmission in the female germ line, leading to high levels causing severe mitochondrial diseases. There is also emerging evidence that low level mtDNA mutations contribute to common late onset diseases such as neurodegenerative disorders and cardiometabolic diseases because the inherited mutation levels can change within developing organs and non-dividing cells over time. Initial predictions suggested that the segregation of mtDNA heteroplasmy was largely stochastic, with an equal tendency for levels to increase or decrease. However, transgenic animal work and single-cell analysis have shown this not to be the case during germ-line transmission and in somatic tissues during life. Mutation levels in specific mtDNA regions can increase or decrease in different contexts and the underlying molecular mechanisms are starting to be unraveled. In this review we provide a synthesis of recent literature on the mechanisms of selection for and against mtDNA variants. We identify the most pertinent gaps in our understanding and suggest ways these could be addressed using state of the art techniques.
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Affiliation(s)
- Marcos R Chiaratti
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, Brazil.
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK.
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Bennett CF, Ronayne CT, Puigserver P. Targeting adaptive cellular responses to mitochondrial bioenergetic deficiencies in human disease. FEBS J 2022; 289:6969-6993. [PMID: 34510753 PMCID: PMC8917243 DOI: 10.1111/febs.16195] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/25/2021] [Accepted: 09/10/2021] [Indexed: 01/13/2023]
Abstract
Mitochondrial dysfunction is increasingly appreciated as a central contributor to human disease. Oxidative metabolism at the mitochondrial respiratory chain produces ATP and is intricately tied to redox homeostasis and biosynthetic pathways. Metabolic stress arising from genetic mutations in mitochondrial genes and environmental factors such as malnutrition or overnutrition is perceived by the cell and leads to adaptive and maladaptive responses that can underlie pathology. Here, we will outline cellular sensors that react to alterations in energy production, organellar redox, and metabolites stemming from mitochondrial disease (MD) mutations. MD is a heterogeneous group of disorders primarily defined by defects in mitochondrial oxidative phosphorylation from nuclear or mitochondrial-encoded gene mutations. Preclinical therapies that improve fitness of MD mouse models have been recently identified. Targeting metabolic/energetic deficiencies, maladaptive signaling processes, and hyper-oxygenation of tissues are all strategies aside from direct genetic approaches that hold therapeutic promise. A further mechanistic understanding of these curative processes as well as the identification of novel targets will significantly impact mitochondrial biology and disease research.
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Affiliation(s)
- Christopher F Bennett
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Conor T Ronayne
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Pere Puigserver
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
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Tostes K, dos Santos AC, Alves LO, Bechara LRG, Marascalchi R, Macabelli CH, Grejo MP, Festuccia WT, Gottlieb RA, Ferreira JCB, Chiaratti MR. Autophagy deficiency abolishes liver mitochondrial DNA segregation. Autophagy 2022; 18:2397-2408. [PMID: 35220898 PMCID: PMC9542960 DOI: 10.1080/15548627.2022.2038501] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Mutations in the mitochondrial genome (mtDNA) are ubiquitous in humans and can lead to a broad spectrum of disorders. However, due to the presence of multiple mtDNA molecules in the cell, co-existence of mutant and wild-type mtDNAs (termed heteroplasmy) can mask disease phenotype unless a threshold of mutant molecules is reached. Importantly, the mutant mtDNA level can change across lifespan as mtDNA segregates in an allele- and cell-specific fashion, potentially leading to disease. Segregation of mtDNA is mainly evident in hepatic cells, resulting in an age-dependent increase of mtDNA variants, including non-synonymous potentially deleterious mutations. Here we modeled mtDNA segregation using a well-established heteroplasmic mouse line with mtDNA of NZB/BINJ and C57BL/6N origin on a C57BL/6N nuclear background. This mouse line showed a pronounced age-dependent NZB mtDNA accumulation in the liver, thus leading to enhanced respiration capacity per mtDNA molecule. Remarkably, liver-specific atg7 (autophagy related 7) knockout abolished NZB mtDNA accumulat ion, resulting in close-to-neutral mtDNA segregation through development into adulthood. prkn (parkin RBR E3 ubiquitin protein ligase) knockout also partially prevented NZB mtDNA accumulation in the liver, but to a lesser extent. Hence, we propose that age-related liver mtDNA segregation is a consequence of macroautophagic clearance of the less-fit mtDNA. Considering that NZB/BINJ and C57BL/6N mtDNAs have a level of divergence comparable to that between human Eurasian and African mtDNAs, these findings have potential implications for humans, including the safe use of mitochondrial replacement therapy.Abbreviations: Apob: apolipoprotein B; Atg1: autophagy-related 1; Atg7: autophagy related 7; Atp5a1: ATP synthase, H+ transporting, mitochondrial F1 complex, alpha subunit 1; BL6: C57BL/6N mouse strain; BNIP3: BCL2/adenovirus E1B interacting protein 3; FCCP: carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; MAP1LC3A: microtubule-associated protein 1 light chain 3 alpha; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; mt-Atp8: mitochondrially encoded ATP synthase 8; MT-CO1: mitochondrially encoded cytochrome c oxidase I; MT-CO2: mitochondrially encoded cytochrome c oxidase II; mt-Co3: mitochondrially encoded cytochrome c oxidase III; mt-Cytb: mitochondrially encoded cytochrome b; mtDNA: mitochondrial DNA; MUL1: mitochondrial ubiquitin ligase activator of NFKB 1; nDNA: nuclear DNA; Ndufa9: NADH:ubiquinone oxireductase subunit A9; NDUFB8: NADH:ubiquinone oxireductase subunit B8; Nnt: nicotinamide nucleotide transhydrogenase; NZB: NZB/BINJ mouse strain; OXPHOS: oxidative phosphorylation; PINK1: PTEN induced putative kinase 1; Polg2: polymerase (DNA directed), gamma 2, accessory subunit; Ppara: peroxisome proliferator activated receptor alpha; Ppia: peptidylprolyl isomerase A; Prkn: parkin RBR E3 ubiquitin protein ligase; P10: post-natal day 10; P21: post-natal day 21; P100: post-natal day 100; qPCR: quantitative polymerase chain reaction; Rpl19: ribosomal protein L19; Rps18: ribosomal protein S18; SD: standard deviation; SEM: standard error of the mean; SDHB: succinate dehydrogenase complex, subunit B, iron sulfur (Ip); SQSTM1: sequestosome 1; Ssbp1: single-stranded DNA binding protein 1; TFAM: transcription factor A, mitochondrial; Tfb1m: transcription factor B1, mitochondrial; Tfb2m: transcription factor B2, mitochondrial; TOMM20: translocase of outer mitochondrial membrane 20; UQCRC2: ubiquinol cytochrome c reductase core protein 2; WT: wild-type.
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Affiliation(s)
- Katiane Tostes
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Angélica C. dos Santos
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Lindomar O. Alves
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Luiz R. G. Bechara
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Rachel Marascalchi
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Carolina H. Macabelli
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Mateus P. Grejo
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - William T. Festuccia
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Roberta A. Gottlieb
- Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Julio C. B. Ferreira
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil,Department of Chemical and Systems Biology, Stanford University School of Medicine, CA, USA
| | - Marcos R. Chiaratti
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil,CONTACT Marcos R. Chiaratti Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos13565-905, Brazil
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Small molecule-mediated allosteric activation of the base excision repair enzyme 8-oxoguanine DNA glycosylase and its impact on mitochondrial function. Sci Rep 2022; 12:14685. [PMID: 36038587 PMCID: PMC9424235 DOI: 10.1038/s41598-022-18878-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 08/22/2022] [Indexed: 02/07/2023] Open
Abstract
8-Oxoguanine DNA glycosylase (OGG1) initiates base excision repair of the oxidative DNA damage product 8-oxoguanine. OGG1 is bifunctional; catalyzing glycosyl bond cleavage, followed by phosphodiester backbone incision via a β-elimination apurinic lyase reaction. The product from the glycosylase reaction, 8-oxoguanine, and its analogues, 8-bromoguanine and 8-aminoguanine, trigger the rate-limiting AP lyase reaction. The precise activation mechanism remains unclear. The product-assisted catalysis hypothesis suggests that 8-oxoguanine and analogues bind at the product recognition (PR) pocket to enhance strand cleavage as catalytic bases. Alternatively, they may allosterically activate OGG1 by binding outside of the PR pocket to induce an active-site conformational change to accelerate apurinic lyase. Herein, steady-state kinetic analyses demonstrated random binding of substrate and activator. 9-Deazaguanine, which can't function as a substrate-competent base, activated OGG1, albeit with a lower Emax value than 8-bromoguanine and 8-aminoguanine. Random compound screening identified small molecules with Emax values similar to 8-bromoguanine. Paraquat-induced mitochondrial dysfunction was attenuated by several small molecule OGG1 activators; benefits included enhanced mitochondrial membrane and DNA integrity, less cytochrome c translocation, ATP preservation, and mitochondrial membrane dynamics. Our results support an allosteric mechanism of OGG1 and not product-assisted catalysis. OGG1 small molecule activators may improve mitochondrial function in oxidative stress-related diseases.
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Capristo M, Del Dotto V, Tropeano CV, Fiorini C, Caporali L, La Morgia C, Valentino ML, Montopoli M, Carelli V, Maresca A. Rapamycin rescues mitochondrial dysfunction in cells carrying the m.8344A > G mutation in the mitochondrial tRNA Lys. Mol Med 2022; 28:90. [PMID: 35922766 PMCID: PMC9347137 DOI: 10.1186/s10020-022-00519-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 07/25/2022] [Indexed: 11/25/2022] Open
Abstract
Background Myoclonus, Epilepsy and Ragged-Red-Fibers (MERRF) is a mitochondrial encephalomyopathy due to heteroplasmic mutations in mitochondrial DNA (mtDNA) most frequently affecting the tRNALys gene at position m.8344A > G. Defective tRNALys severely impairs mitochondrial protein synthesis and respiratory chain when a high percentage of mutant heteroplasmy crosses the threshold for full-blown clinical phenotype. Therapy is currently limited to symptomatic management of myoclonic epilepsy, and supportive measures to counteract muscle weakness with co-factors/supplements. Methods We tested two therapeutic strategies to rescue mitochondrial function in cybrids and fibroblasts carrying different loads of the m.8344A > G mutation. The first strategy was aimed at inducing mitochondrial biogenesis directly, over-expressing the master regulator PGC-1α, or indirectly, through the treatment with nicotinic acid, a NAD+ precursor. The second was aimed at stimulating the removal of damaged mitochondria through prolonged rapamycin treatment. Results The first approach slightly increased mitochondrial protein expression and respiration in the wild type and intermediate-mutation load cells, but was ineffective in high-mutation load cell lines. This suggests that induction of mitochondrial biogenesis may not be sufficient to rescue mitochondrial dysfunction in MERRF cells with high-mutation load. The second approach, when administered chronically (4 weeks), induced a slight increase of mitochondrial respiration in fibroblasts with high-mutation load, and a significant improvement in fibroblasts with intermediate-mutation load, rescuing completely the bioenergetics defect. This effect was mediated by increased mitochondrial biogenesis, possibly related to the rapamycin-induced inhibition of the Mechanistic Target of Rapamycin Complex 1 (mTORC1) and the consequent activation of the Transcription Factor EB (TFEB). Conclusions Overall, our results point to rapamycin-based therapy as a promising therapeutic option for MERRF. Supplementary Information The online version contains supplementary material available at 10.1186/s10020-022-00519-z.
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Affiliation(s)
- Mariantonietta Capristo
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, via Altura 3, 40139, Bologna, Italy
| | - Valentina Del Dotto
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, via Altura 3, 40139, Bologna, Italy
| | - Concetta Valentina Tropeano
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, via Altura 3, 40139, Bologna, Italy
| | - Claudio Fiorini
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, via Altura 3, 40139, Bologna, Italy
| | - Leonardo Caporali
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, via Altura 3, 40139, Bologna, Italy
| | - Chiara La Morgia
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, via Altura 3, 40139, Bologna, Italy
| | - Maria Lucia Valentino
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, via Altura 3, 40139, Bologna, Italy.,Department of Biomedical and NeuroMotor Sciences, University of Bologna, via Altura 3, 40139, Bologna, Italy
| | - Monica Montopoli
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, via Largo Meneghetti 2, 3513, Padova, Italy
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, via Altura 3, 40139, Bologna, Italy. .,Department of Biomedical and NeuroMotor Sciences, University of Bologna, via Altura 3, 40139, Bologna, Italy.
| | - Alessandra Maresca
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, via Altura 3, 40139, Bologna, Italy.
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13
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Suárez-Rivero JM, Pastor-Maldonado CJ, Povea-Cabello S, Álvarez-Córdoba M, Villalón-García I, Talaverón-Rey M, Suárez-Carrillo A, Munuera-Cabeza M, Reche-López D, Cilleros-Holgado P, Piñero-Perez R, Sánchez-Alcázar JA. UPR mt activation improves pathological alterations in cellular models of mitochondrial diseases. Orphanet J Rare Dis 2022; 17:204. [PMID: 35581596 PMCID: PMC9115953 DOI: 10.1186/s13023-022-02331-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 04/26/2022] [Indexed: 12/23/2022] Open
Abstract
Background Mitochondrial diseases represent one of the most common groups of genetic diseases. With a prevalence greater than 1 in 5000 adults, such diseases still lack effective treatment. Current therapies are purely palliative and, in most cases, insufficient. Novel approaches to compensate and, if possible, revert mitochondrial dysfunction must be developed. Results In this study, we tackled the issue using as a model fibroblasts from a patient bearing a mutation in the GFM1 gene, which is involved in mitochondrial protein synthesis. Mutant GFM1 fibroblasts could not survive in galactose restrictive medium for more than 3 days, making them the perfect screening platform to test several compounds. Tetracycline enabled mutant GFM1 fibroblasts survival under nutritional stress. Here we demonstrate that tetracycline upregulates the mitochondrial Unfolded Protein Response (UPRmt), a compensatory pathway regulating mitochondrial proteostasis. We additionally report that activation of UPRmt improves mutant GFM1 cellular bioenergetics and partially restores mitochondrial protein expression. Conclusions Overall, we provide compelling evidence to propose the activation of intrinsic cellular compensatory mechanisms as promising therapeutic strategy for mitochondrial diseases. Supplementary Information The online version contains supplementary material available at 10.1186/s13023-022-02331-8.
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Affiliation(s)
- Juan M Suárez-Rivero
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Carmen J Pastor-Maldonado
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Suleva Povea-Cabello
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Mónica Álvarez-Córdoba
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Irene Villalón-García
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Marta Talaverón-Rey
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Alejandra Suárez-Carrillo
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Manuel Munuera-Cabeza
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Diana Reche-López
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Paula Cilleros-Holgado
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - Rocío Piñero-Perez
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain
| | - José A Sánchez-Alcázar
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas, Universidad Pablo de Olavide, Carretera de Utrera Km 1, 41013, Seville, Spain. .,Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III, 41013, Seville, Spain.
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14
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The Mitochondrial Genome in Aging and Disease and the Future of Mitochondrial Therapeutics. Biomedicines 2022; 10:biomedicines10020490. [PMID: 35203698 PMCID: PMC8962324 DOI: 10.3390/biomedicines10020490] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/10/2022] [Accepted: 02/16/2022] [Indexed: 11/29/2022] Open
Abstract
Mitochondria are intracellular organelles that utilize nutrients to generate energy in the form of ATP by oxidative phosphorylation. Mitochondrial DNA (mtDNA) in humans is a 16,569 base pair double-stranded circular DNA that encodes for 13 vital proteins of the electron transport chain. Our understanding of the mitochondrial genome’s transcription, translation, and maintenance is still emerging, and human pathologies caused by mtDNA dysfunction are widely observed. Additionally, a correlation between declining mitochondrial DNA quality and copy number with organelle dysfunction in aging is well-documented in the literature. Despite tremendous advancements in nuclear gene-editing technologies and their value in translational avenues, our ability to edit mitochondrial DNA is still limited. In this review, we discuss the current therapeutic landscape in addressing the various pathologies that result from mtDNA mutations. We further evaluate existing gene therapy efforts, particularly allotopic expression and its potential to become an indispensable tool for restoring mitochondrial health in disease and aging.
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15
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Chang KC, Liu PF, Chang CH, Lin YC, Chen YJ, Shu CW. The interplay of autophagy and oxidative stress in the pathogenesis and therapy of retinal degenerative diseases. Cell Biosci 2022; 12:1. [PMID: 34980273 PMCID: PMC8725349 DOI: 10.1186/s13578-021-00736-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 12/19/2021] [Indexed: 12/27/2022] Open
Abstract
Oxidative stress is mainly caused by intracellular reactive oxygen species (ROS) production, which is highly associated with normal physiological homeostasis and the pathogenesis of diseases, particularly ocular diseases. Autophagy is a self-clearance pathway that removes oxidized cellular components and regulates cellular ROS levels. ROS can modulate autophagy activity through transcriptional and posttranslational mechanisms. Autophagy further triggers transcription factor activation and degrades impaired organelles and proteins to eliminate excessive ROS in cells. Thus, autophagy may play an antioxidant role in protecting ocular cells from oxidative stress. Nevertheless, excessive autophagy may cause autophagic cell death. In this review, we summarize the mechanisms of interaction between ROS and autophagy and their roles in the pathogenesis of several ocular diseases, including glaucoma, age-related macular degeneration (AMD), diabetic retinopathy (DR), and optic nerve atrophy, which are major causes of blindness. The autophagy modulators used to treat ocular diseases are further discussed. The findings of the studies reviewed here might shed light on the development and use of autophagy modulators for the future treatment of ocular diseases.
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Affiliation(s)
- Kun-Che Chang
- Department of Ophthalmology and Neurobiology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Pei-Feng Liu
- Department of Biomedical Science and Environmental Biology, PhD Program in Life Science, College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chia-Hsuan Chang
- Institute of BioPharmaceutical Sciences, National Sun Yat-Sen University, No. 70, Lianhai Rd., Gushan Dist., Kaohsiung, 80424, Taiwan
| | - Ying-Cheng Lin
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Yen-Ju Chen
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Department of Medical Research, Taichung Veterans General Hospital, Taichung, Taiwan.,Division of Allergy, Immunology and Rheumatology, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Chih-Wen Shu
- Institute of BioPharmaceutical Sciences, National Sun Yat-Sen University, No. 70, Lianhai Rd., Gushan Dist., Kaohsiung, 80424, Taiwan.
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16
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Rewiring cell signalling pathways in pathogenic mtDNA mutations. Trends Cell Biol 2021; 32:391-405. [PMID: 34836781 DOI: 10.1016/j.tcb.2021.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/19/2021] [Accepted: 10/22/2021] [Indexed: 12/24/2022]
Abstract
Mitochondria generate the energy to sustain cell viability and serve as a hub for cell signalling. Their own genome (mtDNA) encodes genes critical for oxidative phosphorylation. Mutations of mtDNA cause major disease and disability with a wide range of presentations and severity. We review here an emerging body of data suggesting that changes in cell metabolism and signalling pathways in response to the presence of mtDNA mutations play a key role in shaping disease presentation and progression. Understanding the impact of mtDNA mutations on cellular energy homeostasis and signalling pathways seems fundamental to identify novel therapeutic interventions with the potential to improve the prognosis for patients with primary mitochondrial disease.
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17
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Villarejo-Zori B, Jiménez-Loygorri JI, Zapata-Muñoz J, Bell K, Boya P. New insights into the role of autophagy in retinal and eye diseases. Mol Aspects Med 2021; 82:101038. [PMID: 34620506 DOI: 10.1016/j.mam.2021.101038] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/12/2021] [Accepted: 09/27/2021] [Indexed: 02/06/2023]
Abstract
Autophagy is a fundamental homeostatic pathway that mediates the degradation and recycling of intracellular components. It serves as a key quality control mechanism, especially in non-dividing cells such as neurons. Proteins, lipids, and even whole organelles are engulfed in autophagosomes and delivered to the lysosome for elimination. The retina is a light-sensitive tissue located in the back of the eye that detects and processes visual images. Vision is a highly demanding process, making the eye one of the most metabolically active tissues in the body and photoreceptors display glycolytic metabolism, even in the presence of oxygen. The retina and eye are also exposed to other stressors that can impair their function, including genetic mutations and age-associated changes. Autophagy, among other pathways, is therefore a key process for the preservation of retinal homeostasis. Here, we review the roles of both canonical and non-canonical autophagy in normal retinal function. We discuss the most recent studies investigating the participation of autophagy in eye diseases such as age-related macular degeneration, glaucoma, and diabetic retinopathy and its role protecting photoreceptors in several forms of retinal degeneration. Finally, we consider the therapeutic potential of strategies that target autophagy pathways to treat prevalent retinal and eye diseases.
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Affiliation(s)
- Beatriz Villarejo-Zori
- Department of Cellular and Molecular Biology, Margarita Salas Center for Biological Research, CSIC, Ramiro de Maetzu, 9, 28040, Madrid, Spain
| | - Juan Ignacio Jiménez-Loygorri
- Department of Cellular and Molecular Biology, Margarita Salas Center for Biological Research, CSIC, Ramiro de Maetzu, 9, 28040, Madrid, Spain
| | - Juan Zapata-Muñoz
- Department of Cellular and Molecular Biology, Margarita Salas Center for Biological Research, CSIC, Ramiro de Maetzu, 9, 28040, Madrid, Spain
| | - Katharina Bell
- Singapore Eye Research Institute, Singapore National Eye Centre, Republic of Singapore
| | - Patricia Boya
- Department of Cellular and Molecular Biology, Margarita Salas Center for Biological Research, CSIC, Ramiro de Maetzu, 9, 28040, Madrid, Spain.
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18
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Cheema NJ, Cameron JM, Hood DA. Effect of rapamycin on mitochondria and lysosomes in fibroblasts from patients with mtDNA mutations. Am J Physiol Cell Physiol 2021; 321:C176-C186. [PMID: 34106788 DOI: 10.1152/ajpcell.00471.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Maintaining mitochondrial function and dynamics is crucial for cellular health. In muscle, defects in mitochondria result in severe myopathies where accumulation of damaged mitochondria causes deterioration and dysfunction. Importantly, understanding the role of mitochondria in disease is a necessity to determine future therapeutics. One of the most common myopathies is mitochondrial encephalopathy lactic acidosis stroke-like episodes (MELAS), which has no current treatment. Recently, patients with MELAS treated with rapamycin exhibited improved clinical outcomes. However, the cellular mechanisms of rapamycin effects in patients with MELAS are currently unknown. In this study, we used cultured skin fibroblasts as a window into the mitochondrial dysfunction evident in MELAS cells, as well as to study the mechanisms of rapamycin action, compared with control, healthy individuals. We observed that mitochondria from patients were fragmented, had a threefold decline in the average speed of motility, a twofold reduced mitochondrial membrane potential, and a 1.5- to 2-fold decline in basal respiration. Despite the reduction in mitochondrial function, mitochondrial import protein Tim23 was elevated in patient cell lines. MELAS fibroblasts exhibited increased MnSOD levels and lysosomal function when compared with healthy controls. Treatment of MELAS fibroblasts with rapamycin for 24 h resulted in increased mitochondrial respiration compared with control cells, a higher lysosome content, and a greater localization of mitochondria to lysosomes. Our studies suggest that rapamycin has the potential to improve cellular health even in the presence of mtDNA defects, primarily via an increase in lysosomal content.
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Affiliation(s)
- Nashwa J Cheema
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
| | - Jessie M Cameron
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Pathology and Laboratory Medicine, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - David A Hood
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
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19
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Peron C, Maresca A, Cavaliere A, Iannielli A, Broccoli V, Carelli V, Di Meo I, Tiranti V. Exploiting hiPSCs in Leber's Hereditary Optic Neuropathy (LHON): Present Achievements and Future Perspectives. Front Neurol 2021; 12:648916. [PMID: 34168607 PMCID: PMC8217617 DOI: 10.3389/fneur.2021.648916] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Accepted: 04/26/2021] [Indexed: 01/19/2023] Open
Abstract
More than 30 years after discovering Leber's hereditary optic neuropathy (LHON) as the first maternally inherited disease associated with homoplasmic mtDNA mutations, we still struggle to achieve effective therapies. LHON is characterized by selective degeneration of retinal ganglion cells (RGCs) and is the most frequent mitochondrial disease, which leads young people to blindness, in particular males. Despite that causative mutations are present in all tissues, only a specific cell type is affected. Our deep understanding of the pathogenic mechanisms in LHON is hampered by the lack of appropriate models since investigations have been traditionally performed in non-neuronal cells. Effective in-vitro models of LHON are now emerging, casting promise to speed our understanding of pathophysiology and test therapeutic strategies to accelerate translation into clinic. We here review the potentials of these new models and their impact on the future of LHON patients.
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Affiliation(s)
- Camille Peron
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Alessandra Maresca
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
| | - Andrea Cavaliere
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Angelo Iannielli
- San Raffaele Scientific Institute, Milan, Italy.,National Research Council (CNR), Institute of Neuroscience, Milan, Italy
| | - Vania Broccoli
- San Raffaele Scientific Institute, Milan, Italy.,National Research Council (CNR), Institute of Neuroscience, Milan, Italy
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences-DIBINEM, University of Bologna, Bologna, Italy
| | - Ivano Di Meo
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Valeria Tiranti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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20
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Amore G, Romagnoli M, Carbonelli M, Barboni P, Carelli V, La Morgia C. Therapeutic Options in Hereditary Optic Neuropathies. Drugs 2021; 81:57-86. [PMID: 33159657 PMCID: PMC7843467 DOI: 10.1007/s40265-020-01428-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Options for the effective treatment of hereditary optic neuropathies have been a long time coming. The successful launch of the antioxidant idebenone for Leber's Hereditary Optic Neuropathy (LHON), followed by its introduction into clinical practice across Europe, was an important step forward. Nevertheless, other options, especially for a variety of mitochondrial optic neuropathies such as dominant optic atrophy (DOA), are needed, and a number of pharmaceutical agents, acting on different molecular pathways, are currently under development. These include gene therapy, which has reached Phase III development for LHON, but is expected to be developed also for DOA, whilst most of the other agents (other antioxidants, anti-apoptotic drugs, activators of mitobiogenesis, etc.) are almost all at Phase II or at preclinical stage of research. Here, we review proposed target mechanisms, preclinical evidence, available clinical trials with primary endpoints and results, of a wide range of tested molecules, to give an overview of the field, also providing the landscape of future scenarios, including gene therapy, gene editing, and reproductive options to prevent transmission of mitochondrial DNA mutations.
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Affiliation(s)
- Giulia Amore
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy
| | - Martina Romagnoli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Via Altura 3, 40139, Bologna, Italy
| | - Michele Carbonelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Via Altura 3, 40139, Bologna, Italy
| | | | - Valerio Carelli
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Via Altura 3, 40139, Bologna, Italy
| | - Chiara La Morgia
- IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Via Altura 3, 40139, Bologna, Italy.
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21
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Koňaříková E, Marković A, Korandová Z, Houštěk J, Mráček T. Current progress in the therapeutic options for mitochondrial disorders. Physiol Res 2020; 69:967-994. [PMID: 33129249 PMCID: PMC8549882 DOI: 10.33549/physiolres.934529] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 10/02/2020] [Indexed: 12/20/2022] Open
Abstract
Mitochondrial disorders manifest enormous genetic and clinical heterogeneity - they can appear at any age, present with various phenotypes affecting any organ, and display any mode of inheritance. What mitochondrial diseases do have in common, is impairment of respiratory chain activity, which is responsible for more than 90% of energy production within cells. While diagnostics of mitochondrial disorders has been accelerated by introducing Next-Generation Sequencing techniques in recent years, the treatment options are still very limited. For many patients only a supportive or symptomatic therapy is available at the moment. However, decades of basic and preclinical research have uncovered potential target points and numerous compounds or interventions are now subjects of clinical trials. In this review, we focus on current and emerging therapeutic approaches towards the treatment of mitochondrial disorders. We focus on small compounds, metabolic interference, such as endurance training or ketogenic diet and also on genomic approaches.
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Affiliation(s)
- E Koňaříková
- Laboratory of Bioenergetics, Institute of Physiology Czech Acad. Sci., Prague, Czech Republic. ,
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22
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Shanmughapriya S, Langford D, Natarajaseenivasan K. Inter and Intracellular mitochondrial trafficking in health and disease. Ageing Res Rev 2020; 62:101128. [PMID: 32712108 DOI: 10.1016/j.arr.2020.101128] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 07/13/2020] [Accepted: 07/17/2020] [Indexed: 02/07/2023]
Abstract
Neurons and glia maintain central nervous system (CNS) homeostasis through diverse mechanisms of intra- and intercellular signaling. Some of these interactions include the exchange of soluble factors between cells via direct cell-to-cell contact for both short and long-distance transfer of biological materials. Transcellular transfer of mitochondria has emerged as a key example of this communication. This transcellular transfer of mitochondria are dynamically involved in the cellular and tissue response to CNS injury and play beneficial roles in recovery. This review highlights recent research addressing the cause and effect of intra- and intercellular mitochondrial transfer with a specific focus on the future of mitochondrial transplantation therapy. We believe that mitochondrial transfer plays a crucial role during bioenergetic crisis/deficit, but the quality, quantity and mode of mitochondrial transfer determines the protective capacity for the receiving cells. Mitochondrial transplantation is a new treatment paradigm and will overcome the major bottleneck of traditional approach of correcting mitochondria-related disorders.
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23
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Machado TS, Macabelli CH, Collado MD, Meirelles FV, Guimarães FEG, Chiaratti MR. Evidence of Selection Against Damaged Mitochondria During Early Embryogenesis in the Mouse. Front Genet 2020; 11:762. [PMID: 32760430 PMCID: PMC7373801 DOI: 10.3389/fgene.2020.00762] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Accepted: 06/29/2020] [Indexed: 12/22/2022] Open
Abstract
There is evidence of a purifying filter acting in the female germline to prevent the expansion of deleterious mutations in the mitochondrial DNA (mtDNA). Given our poor understanding of this filter, here we investigate the competence of the mouse embryo to eliminate dysfunctional mitochondria. Toward that, mitochondria were damaged by photoirradiation of NZB/BINJ zygotes loaded with chloromethyl-X-rosamine (CMXRos). The resultant cytoplasm was then injected into C57BL/6J zygotes to track the levels of NZB/BINJ mtDNA during the preimplantation development. About 30% of NZB/BINJ mtDNA was present after injection, regardless of using photoirradiated or non-photoirradiated cytoplasmic donors. Moreover, injection of photoirradiated-derived cytoplasm did not impact development into blastocysts. However, lower levels of NZB/BINJ mtDNA were present in blastocysts when comparing injection of photoirradiated (24.7% ± 1.43) versus non-photoirradiated (31.4% ± 1.43) cytoplasm. Given that total mtDNA content remained stable between stages (zygotes vs. blastocysts) and treatments (photoirradiated vs. non-photoirradiated), these results indicate that the photoirradiated-derived mtDNA was replaced by recipient mtDNA in blastocysts. Unexpectedly, treatment with rapamycin prevented the drop in NZB/BINJ mtDNA levels associated with injection of photoirradiated cytoplasm. Additionally, analysis of mitochondria-autophagosome colocalization provided no evidence that photoirradiated mitochondria were eliminated by autophagy. In conclusion, our findings give evidence that the mouse embryo is competent to mitigate the levels of damaged mitochondria, which might have implications to the transmission of mtDNA-encoded disease.
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Affiliation(s)
- Thiago S Machado
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil.,Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, Brazil
| | - Carolina H Macabelli
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Maite Del Collado
- Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga, Brazil
| | - Flávio V Meirelles
- Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, Brazil.,Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga, Brazil
| | | | - Marcos R Chiaratti
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil.,Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, Brazil
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24
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Lechuga-Vieco AV, Latorre-Pellicer A, Johnston IG, Prota G, Gileadi U, Justo-Méndez R, Acín-Pérez R, Martínez-de-Mena R, Fernández-Toro JM, Jimenez-Blasco D, Mora A, Nicolás-Ávila JA, Santiago DJ, Priori SG, Bolaños JP, Sabio G, Criado LM, Ruíz-Cabello J, Cerundolo V, Jones NS, Enríquez JA. Cell identity and nucleo-mitochondrial genetic context modulate OXPHOS performance and determine somatic heteroplasmy dynamics. SCIENCE ADVANCES 2020; 6:eaba5345. [PMID: 32832682 PMCID: PMC7439646 DOI: 10.1126/sciadv.aba5345] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 06/17/2020] [Indexed: 05/02/2023]
Abstract
Heteroplasmy, multiple variants of mitochondrial DNA (mtDNA) in the same cytoplasm, may be naturally generated by mutations but is counteracted by a genetic mtDNA bottleneck during oocyte development. Engineered heteroplasmic mice with nonpathological mtDNA variants reveal a nonrandom tissue-specific mtDNA segregation pattern, with few tissues that do not show segregation. The driving force for this dynamic complex pattern has remained unexplained for decades, challenging our understanding of this fundamental biological problem and hindering clinical planning for inherited diseases. Here, we demonstrate that the nonrandom mtDNA segregation is an intracellular process based on organelle selection. This cell type-specific decision arises jointly from the impact of mtDNA haplotypes on the oxidative phosphorylation (OXPHOS) system and the cell metabolic requirements and is strongly sensitive to the nuclear context and to environmental cues.
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Affiliation(s)
- Ana Victoria Lechuga-Vieco
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- CIBERES: C/ Melchor Fernández-Almagro 3, 28029 Madrid, Spain
| | - Ana Latorre-Pellicer
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, IIS Aragon, E-50009 Zaragoza, Spain
| | - Iain G. Johnston
- Department of Mathematics, Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen, Norway
| | - Gennaro Prota
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Uzi Gileadi
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Raquel Justo-Méndez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Rebeca Acín-Pérez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | | | | | - Daniel Jimenez-Blasco
- IBFG, Universidad de Salamanca, Salamanca, Spain
- IBSAL, Hospital Universitario de Salamanca, Universidad de Salamanca, CSIC, Salamanca, Spain
- CIBERFES, C/Melchor Fernández-Almagro 3, 28029 Madrid, Spain
| | - Alfonso Mora
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | | | - Demetrio J. Santiago
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- Molecular Cardiology, IRCCS ICS Maugeri, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Silvia G. Priori
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- Molecular Cardiology, IRCCS ICS Maugeri, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Juan Pedro Bolaños
- IBFG, Universidad de Salamanca, Salamanca, Spain
- IBSAL, Hospital Universitario de Salamanca, Universidad de Salamanca, CSIC, Salamanca, Spain
- CIBERFES, C/Melchor Fernández-Almagro 3, 28029 Madrid, Spain
| | - Guadalupe Sabio
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Luis Miguel Criado
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Jesús Ruíz-Cabello
- CIBERES: C/ Melchor Fernández-Almagro 3, 28029 Madrid, Spain
- CIC biomaGUNE 20014 Donostia/San Sebastián, Gipuzkoa, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
- Universidad Complutense Madrid, Madrid, Spain
| | - Vincenzo Cerundolo
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Nick S. Jones
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College London, London SW7 2BB, UK
| | - José Antonio Enríquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- CIBERFES, C/Melchor Fernández-Almagro 3, 28029 Madrid, Spain
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25
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Lewis CJ, Dixit B, Batiuk E, Hall CJ, O'Connor MS, Boominathan A. Codon optimization is an essential parameter for the efficient allotopic expression of mtDNA genes. Redox Biol 2020; 30:101429. [PMID: 31981894 PMCID: PMC6976934 DOI: 10.1016/j.redox.2020.101429] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 12/29/2019] [Accepted: 01/10/2020] [Indexed: 11/29/2022] Open
Abstract
Mutations in mitochondrial DNA can be inherited or occur de novo leading to several debilitating myopathies with no curative option and few or no effective treatments. Allotopic expression of recoded mitochondrial genes from the nucleus has potential as a gene therapy strategy for such conditions, however progress in this field has been hampered by technical challenges. Here we employed codon optimization as a tool to re-engineer the protein-coding genes of the human mitochondrial genome for robust, efficient expression from the nucleus. All 13 codon-optimized constructs exhibited substantially higher protein expression than minimally-recoded genes when expressed transiently, and steady-state mRNA levels for optimized gene constructs were 5-180 fold enriched over recoded versions in stably-selected wildtype cells. Eight of thirteen mitochondria-encoded oxidative phosphorylation (OxPhos) proteins maintained protein expression following stable selection, with mitochondrial localization of expression products. We also assessed the utility of this strategy in rescuing mitochondrial disease cell models and found the rescue capacity of allotopic expression constructs to be gene specific. Allotopic expression of codon optimized ATP8 in disease models could restore protein levels and respiratory function, however, rescue of the pathogenic phenotype for another gene, ND1 was only partially successful. These results imply that though codon-optimization alone is not sufficient for functional allotopic expression of most mitochondrial genes, it is an essential consideration in their design.
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Affiliation(s)
- Caitlin J Lewis
- Department of Mitochondrial Research, SENS Research Foundation, Mountain View, CA, 94041, USA
| | - Bhavna Dixit
- Department of Mitochondrial Research, SENS Research Foundation, Mountain View, CA, 94041, USA
| | - Elizabeth Batiuk
- Department of Mitochondrial Research, SENS Research Foundation, Mountain View, CA, 94041, USA
| | - Carter J Hall
- Department of Mitochondrial Research, SENS Research Foundation, Mountain View, CA, 94041, USA
| | - Matthew S O'Connor
- Department of Mitochondrial Research, SENS Research Foundation, Mountain View, CA, 94041, USA.
| | - Amutha Boominathan
- Department of Mitochondrial Research, SENS Research Foundation, Mountain View, CA, 94041, USA.
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26
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Zhang X, Zheng Y, Chen Z. Autophagy and Mitochondrial Encephalomyopathies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1207:103-110. [PMID: 32671741 DOI: 10.1007/978-981-15-4272-5_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Mitochondrial encephalomyopathies are a group of disorders affecting skeletal muscles and brain. Although the symptoms vary among these disorders, mitochondrial DNA mutation or loss is the common characteristic. The abnormality of mitochondrial genome usually causes the dysfunction of mitochondrial respiratory and even mitochondrial damage. As a critical way of degradation, attention has been paid to the involvement of autophagy in encephalomyopathies. Autophagy is found activated in these encephalomyopathies-relevant cells as a compensatory manner to eliminate these damaged and dysfunctional mitochondria. However, accumulating evidences indicate that autophagy is incompetent to clear them. The insufficient mitophagy may ultimately accelerate cell death. Here we discuss the involvement of autophagy in encephalomyopathies based on the current evidence. We further look into the future to rescue encephalomyopathies by regulating autophagy. Only five encephalomyopathies are included in this chapter due to the availability of evidence. Nevertheless, these encephalomyopathies share a variety of common features and autophagy may also be regulated in the other encephalomyopathies.
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Affiliation(s)
- Xiangnan Zhang
- Institute of Pharmacology and Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Yanrong Zheng
- Institute of Pharmacology and Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Zhong Chen
- Institute of Pharmacology and Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China.
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27
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Deng J, Lu Y, Xie Z, Liu J, Yuan Y, Wang Z. RNA-seq profiling, and impaired autophagic process in skeletal muscle of MELAS. Biochem Biophys Res Commun 2019; 523:91-97. [PMID: 31836143 DOI: 10.1016/j.bbrc.2019.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Accepted: 12/01/2019] [Indexed: 01/22/2023]
Abstract
Mitochondrial myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like episodes (MELAS) is a common subtype of mitochondrial disease with high disability and mortality rate. The molecular mechanisms of MELAS are largely unknown and whether autophagy is activated in this disease remains controversial. In this work, we reported whole transcriptome profiling of skeletal muscle of MELAS patients and age-matched controls. Analyses revealed that MELAS patients had 224 differentially expressed genes (174 down-regulated, 50 up-regulated) compared to age-matched controls. Most of these genes relevant to MELAS are involved in signal transduction, metabolic process and immune system process. However, the RNA-seq data indicated that autophagy was not altered in MELAS. Functional assays showed that increased reactive oxygen species (ROS), decreased ATP production and decreased lysosome content in fibroblasts derived from MELAS patients, suggesting that mitochondrial dysfunction and degradation deficiency in MELAS. Furthermore, Western-blot analyses using skeletal muscle and fibroblasts derived from MELAS patients showed that autophagy was impaired in MEALS since two important autophagic genes: Beclin-1 and LC3-II, were significantly down-regulated. In conclusion, our study identified molecules and pathways involved in the mechanisms of MELAS, and the impairment of autophagy in this disease, which may serve as the potential therapeutic target for MELAS.
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Affiliation(s)
- Jianwen Deng
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yuanyuan Lu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhiying Xie
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Jing Liu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China.
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China.
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28
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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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29
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Aryaman J, Bowles C, Jones NS, Johnston IG. Mitochondrial Network State Scales mtDNA Genetic Dynamics. Genetics 2019; 212:1429-1443. [PMID: 31253641 PMCID: PMC6707450 DOI: 10.1534/genetics.119.302423] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 06/28/2019] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial DNA (mtDNA) mutations cause severe congenital diseases but may also be associated with healthy aging. mtDNA is stochastically replicated and degraded, and exists within organelles which undergo dynamic fusion and fission. The role of the resulting mitochondrial networks in the time evolution of the cellular proportion of mutated mtDNA molecules (heteroplasmy), and cell-to-cell variability in heteroplasmy (heteroplasmy variance), remains incompletely understood. Heteroplasmy variance is particularly important since it modulates the number of pathological cells in a tissue. Here, we provide the first wide-reaching theoretical framework which bridges mitochondrial network and genetic states. We show that, under a range of conditions, the (genetic) rate of increase in heteroplasmy variance and de novo mutation are proportionally modulated by the (physical) fraction of unfused mitochondria, independently of the absolute fission-fusion rate. In the context of selective fusion, we show that intermediate fusion:fission ratios are optimal for the clearance of mtDNA mutants. Our findings imply that modulating network state, mitophagy rate, and copy number to slow down heteroplasmy dynamics when mean heteroplasmy is low could have therapeutic advantages for mitochondrial disease and healthy aging.
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Affiliation(s)
- Juvid Aryaman
- Department of Mathematics, Imperial College London, SW7 2AZ, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, CB2 0QQ, United Kingdom
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, CB2 0XY, United Kingdom
| | - Charlotte Bowles
- School of Biosciences, University of Birmingham, B15 2TT, United Kingdom
| | - Nick S Jones
- Department of Mathematics, Imperial College London, SW7 2AZ, United Kingdom
- Engineering and Physical Sciences Research Council Centre for the Mathematics of Precision Healthcare, Imperial College London, SW7 2AZ, United Kingdom
| | - Iain G Johnston
- Faculty of Mathematics and Natural Sciences, University of Bergen, 5007, Norway
- Alan Turing Institute, London NW1 2DB, United Kingdom
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30
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Sharma LK, Tiwari M, Rai NK, Bai Y. Mitophagy activation repairs Leber's hereditary optic neuropathy-associated mitochondrial dysfunction and improves cell survival. Hum Mol Genet 2019; 28:422-433. [PMID: 30304398 PMCID: PMC6489411 DOI: 10.1093/hmg/ddy354] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 08/31/2018] [Accepted: 09/26/2018] [Indexed: 12/24/2022] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is a classical mitochondrial disease caused by mutations in the mitochondrial DNA encoding complex I subunits. Oxidative stress associated with complex I defect has been implicated in developing LHON phenotype such as retinal ganglion cell (RGC) death and loss of vision. However, the mechanism of LHON pathogenesis is still not very clear and thus no effective therapies are available to date. Using cybrid models for LHON, we show that autophagy is significantly compromised in cells carrying LHON-specific mtDNA mutations, which results in reduced clearance of dysfunctional mitochondria contributing to cell death. We further show that pharmacological activation of autophagy selectively clears the damaged mitochondria and thus repairs mitochondrial defects and improves overall cell survival in LHON cell models. Our results suggest that compromised autophagy is the missing link from oxidative stress to LHON pathogenesis. Activation of mitophagy ameliorates mitochondrial defects and exerts a protective role by improving cell survival in cells carrying LHON mutations that could be utilized as a potential therapeutic target for LHON treatment.
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Affiliation(s)
- Lokendra Kumar Sharma
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Biotechnology, Centre for Biological Sciences, Central University of South Bihar, Gaya, Bihar, India
| | - Meenakshi Tiwari
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Pathology / Lab Medicine, All India Institute of Medical Sciences-Patna, Phulwarisharif, Patna, Bihar, India
| | - Neeraj Kumar Rai
- Department of Biotechnology, Centre for Biological Sciences, Central University of South Bihar, Gaya, Bihar, India
| | - Yidong Bai
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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31
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Samstag CL, Hoekstra JG, Huang CH, Chaisson MJ, Youle RJ, Kennedy SR, Pallanck LJ. Deleterious mitochondrial DNA point mutations are overrepresented in Drosophila expressing a proofreading-defective DNA polymerase γ. PLoS Genet 2018; 14:e1007805. [PMID: 30452458 PMCID: PMC6289449 DOI: 10.1371/journal.pgen.1007805] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 12/11/2018] [Accepted: 11/01/2018] [Indexed: 01/08/2023] Open
Abstract
Mitochondrial DNA (mtDNA) mutations cause severe maternally inherited syndromes and the accumulation of somatic mtDNA mutations is implicated in aging and common diseases. However, the mechanisms that influence the frequency and pathogenicity of mtDNA mutations are poorly understood. To address this matter, we created a Drosophila mtDNA mutator strain expressing a proofreading-deficient form of the mitochondrial DNA polymerase. Mutator flies have a dramatically increased somatic mtDNA mutation frequency that correlates with the dosage of the proofreading-deficient polymerase. Mutator flies also exhibit mitochondrial dysfunction, shortened lifespan, a progressive locomotor deficit, and loss of dopaminergic neurons. Surprisingly, the frequency of nonsynonymous, pathogenic, and conserved-site mutations in mutator flies exceeded predictions of a neutral mutational model, indicating the existence of a positive selection mechanism that favors deleterious mtDNA variants. We propose from these findings that deleterious mtDNA mutations are overrepresented because they selectively evade quality control surveillance or because they are amplified through compensatory mitochondrial biogenesis. The energy needs of an animal cell are supplied by tiny organelles known as mitochondria. Each of the many mitochondria in a cell has a set of blueprints for making more mitochondria, known as mitochondrial DNA (mtDNA). As animals age, their mtDNA acquires irreversible defects called mutations, which accumulate and may cause aging. Cells can selectively destroy malfunctioning mitochondria, so we hypothesized that mitochondria with harmful mutations would be selectively destroyed. To test our theory, we created a fruit fly strain with a high mtDNA mutation rate. Our hypothesis predicts that, because mitochondria bearing harmful mtDNA mutations would be destroyed, we should detect primarily less harmful mutations in our strain. However, the mtDNA mutations we detected were more harmful than expected by chance. We suggest two possible explanations: First, mitochondria with harmful mtDNA mutations may be degraded less often because they generate little energy and are not damaged by toxic byproducts of energy production. Second, cells may compensate for harmful mtDNA mutations by stimulating mitochondria to multiply, creating more healthy mitochondria but also more mitochondria with harmful mtDNA mutations. Future studies will distinguish between these models and further advance our understanding of aging and aging related disease.
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Affiliation(s)
- Colby L. Samstag
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, United States of America
- Department of Genome Sciences, University of Washington, Seattle, WA, United States of America
| | - Jake G. Hoekstra
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Chiu-Hui Huang
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States of America
| | - Mark J. Chaisson
- Computational Biology and Bioinformatics, University of Southern California, Los Angeles, CA, United States of America
| | - Richard J. Youle
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States of America
| | - Scott R. Kennedy
- Department of Pathology, University of Washington, Seattle, WA, United States of America
- * E-mail: (SRK); (LJP)
| | - Leo J. Pallanck
- Department of Genome Sciences, University of Washington, Seattle, WA, United States of America
- * E-mail: (SRK); (LJP)
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32
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Tranah GJ, Maglione JE, Yaffe K, Katzman SM, Manini TM, Kritchevsky S, Newman AB, Harris TB, Cummings SR. Mitochondrial DNA m.13514G>A heteroplasmy is associated with depressive symptoms in the elderly. Int J Geriatr Psychiatry 2018; 33:1319-1326. [PMID: 29984425 DOI: 10.1002/gps.4928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 05/14/2018] [Indexed: 12/17/2022]
Abstract
OBJECTIVES Mitochondrial DNA (mtDNA) heteroplasmy is a mixture of normal and mutated mtDNA molecules in a cell. High levels of heteroplasmy at several mtDNA sites in complex I lead to inherited neurological neurologic diseases and brain magnetic resonance imaging (MRI) abnormalities. Here, we test the hypothesis that mtDNA heteroplasmy at these complex I sites is associated with depressive symptoms in the elderly. METHODS We examined platelet mtDNA heteroplasmy for associations with depressive symptoms among 137 participants over age 70 from the community-based Health, Aging and Body Composition Study. Depressive symptoms were assessed using the 10-point version of the Center for Epidemiologic Studies Depression Scale (CES-D 10). Complete mtDNA sequencing was performed and heteroplasmy derived for 5 mtDNA sites associated with neurologic mitochondrial diseases and tested for associations with depressive symptoms. RESULTS Of 5 candidate complex I mtDNA mutations examined for effects on depressive symptoms, increased heteroplasmy at m.13514A>G, ND5, was significantly associated with higher CES-D score (P = .01). A statistically significant interaction between m.13514A > G heteroplasmy and sex was detected (P = .04); in sex-stratified analyses, the impact of m.13514A>G heteroplasmy was stronger in male (P = .003) than in female (P = .98) participants. Men in highest tertile of mtDNA heteroplasmy exhibited significantly higher (P = .0001) mean ± SE CES-D 10 scores, 5.37 ± 0.58, when compared with those in the middle, 2.13 ± 0.52, and lowest tertiles, 2.47 ± 0.58. No associations between the 4 other candidate sites and depressive symptoms were observed. CONCLUSIONS Increased mtDNA heteroplasmy at m.13514A>G is associated with depressive symptoms in older men. Heteroplasmy may represent a novel biological risk factor for depression.
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Affiliation(s)
- Gregory J Tranah
- California Pacific Medical Center Research Institute, San Francisco, San Francisco, CA, USA
| | - Jeanne E Maglione
- University of California, San Diego, Department of Psychiatry, La Jolla, CA, USA
| | - Kristine Yaffe
- University of California, San Francisco, Departments of Psychiatry, Neurology, and Epidemiology, San Francisco, CA, USA.,San Francisco VA Medical Center, San Francisco, CA, USA
| | | | - Todd M Manini
- University of Florida, Department of Aging and Geriatric Research, Gainesville, FL, USA
| | - Stephen Kritchevsky
- Wake Forest School of Medicine, Sticht Center on Aging, Winston-Salem, NC, USA
| | - Anne B Newman
- University of Pittsburgh, Department of Epidemiology, Pittsburgh, PA, USA
| | - Tamara B Harris
- National Institute on Aging, Intramural Research Program, Laboratory of Epidemiology and Population Sciences, Bethesda, MD, USA
| | - Steven R Cummings
- California Pacific Medical Center Research Institute, San Francisco, San Francisco, CA, USA
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33
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Tranah GJ, Katzman SM, Lauterjung K, Yaffe K, Manini TM, Kritchevsky S, Newman AB, Harris TB, Cummings SR. Mitochondrial DNA m.3243A > G heteroplasmy affects multiple aging phenotypes and risk of mortality. Sci Rep 2018; 8:11887. [PMID: 30089816 PMCID: PMC6082898 DOI: 10.1038/s41598-018-30255-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 07/20/2018] [Indexed: 12/13/2022] Open
Abstract
Mitochondria contain many copies of a circular DNA molecule (mtDNA), which has been observed as a mixture of normal and mutated states known as heteroplasmy. Elevated heteroplasmy at a single mtDNA site, m.3243A > G, leads to neurologic, sensory, movement, metabolic, and cardiopulmonary impairments. We measured leukocyte mtDNA m.3243A > G heteroplasmy in 789 elderly men and women from the bi-racial, population-based Health, Aging, and Body Composition Study to identify associations with age-related functioning and mortality. Mutation burden for the m.3243A > G ranged from 0-19% and elevated heteroplasmy was associated with reduced strength, cognitive, metabolic, and cardiovascular functioning. Risk of all-cause, dementia and stroke mortality was significantly elevated for participants in the highest tertiles of m.3243A > G heteroplasmy. These results indicate that the accumulation of a rare genetic disease mutation, m.3243A > G, manifests as several aging outcomes and that some diseases of aging may be attributed to the accumulation of mtDNA damage.
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Grants
- R01-NR012459 U.S. Department of Health & Human Services | National Institutes of Health (NIH)
- R01 HL121023 NHLBI NIH HHS
- N01-AG-6-2106 U.S. Department of Health & Human Services | NIH | National Institute on Aging (U.S. National Institute on Aging)
- R01-HL121023 U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- P30 AG028740 NIA NIH HHS
- Z01A6000932 Office of Extramural Research, National Institutes of Health (OER)
- R03-AG032498 U.S. Department of Health & Human Services | NIH | National Institute on Aging (U.S. National Institute on Aging)
- R01-AG028050 U.S. Department of Health & Human Services | NIH | National Institute on Aging (U.S. National Institute on Aging)
- R01 NR012459 NINR NIH HHS
- R03 AG032498 NIA NIH HHS
- R01 AG028050 NIA NIH HHS
- This research was supported in part by the Intramural Research Program of the NIH, National Institute on Aging, Contracts N01-AG-6-2101, N01-AG-6-2103, and N01-AG-6-2106; National Institutes of Health grants R01-AG028050, R03-AG032498, R01-NR012459, Z01A6000932, R01-HL121023, and a grant from the Research and Education Leadership Committee of the CPMC Foundation and the L. K. Whittier Foundation.
- U.S. Department of Health & Human Services | NIH | National Institute on Aging (U.S. National Institute on Aging)
- U.S. Department of Health & Human Services | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- U.S. Department of Health & Human Services | National Institutes of Health (NIH)
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Affiliation(s)
- Gregory J Tranah
- California Pacific Medical Center Research Institute, San Francisco, CA, 94107, USA.
| | | | - Kevin Lauterjung
- California Pacific Medical Center Research Institute, San Francisco, CA, 94107, USA
| | - Kristine Yaffe
- Departments of Psychiatry, Neurology, and Epidemiology, University of California, San Francisco and the San Francisco VA Medical Center, San Francisco, CA, 94121, USA
| | - Todd M Manini
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, 32601, USA
| | - Stephen Kritchevsky
- Sticht Center on Aging, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - Anne B Newman
- Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Tamara B Harris
- Intramural Research Program, Laboratory of Epidemiology and Population Sciences, National Institute on Aging, Bethesda, MD, 20892, USA
| | - Steven R Cummings
- California Pacific Medical Center Research Institute, San Francisco, CA, 94107, USA
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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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Resolving the Enigma of the Clonal Expansion of mtDNA Deletions. Genes (Basel) 2018; 9:genes9030126. [PMID: 29495484 PMCID: PMC5867847 DOI: 10.3390/genes9030126] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 02/14/2018] [Accepted: 02/16/2018] [Indexed: 12/31/2022] Open
Abstract
Mitochondria are cell organelles that are special since they contain their own genetic material in the form of mitochondrial DNA (mtDNA). Damage and mutations of mtDNA are not only involved in several inherited human diseases but are also widely thought to play an important role during aging. In both cases, point mutations or large deletions accumulate inside cells, leading to functional impairment once a certain threshold has been surpassed. In most cases, it is a single type of mutant that clonally expands and out-competes the wild type mtDNA, with different mutant molecules being amplified in different cells. The challenge is to explain where the selection advantage for the accumulation comes from, why such a large range of different deletions seem to possess this advantage, and how this process can scale to species with different lifespans such as those of rats and man. From this perspective, we provide an overview of current ideas, present an update of our own proposal, and discuss the wider relevance of the phenomenon for aging.
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Bielas J, Herbst A, Widjaja K, Hui J, Aiken JM, McKenzie D, Miller RA, Brooks SV, Wanagat J. Long term rapamycin treatment improves mitochondrial DNA quality in aging mice. Exp Gerontol 2018; 106:125-131. [PMID: 29486228 DOI: 10.1016/j.exger.2018.02.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 01/23/2018] [Accepted: 02/20/2018] [Indexed: 12/19/2022]
Abstract
Age-induced mitochondrial DNA deletion mutations may underlie cell loss and tissue aging. Rapamycin extends mouse lifespan and modulates mitochondrial quality control. We hypothesized that reduced deletion mutation abundance may contribute to rapamycin's life extension effects. To test this hypothesis, genetically heterogeneous male and female mice were treated with rapamycin, compounded in chow at 14 or 42 ppm, from 9 months to 22 months of age. Mice under a 40% dietary restriction were included as a control known to protect mtDNA quality. To determine if chronic rapamycin treatment affects mitochondrial DNA quality, we assayed mtDNA deletion frequency and electron transport chain deficient fiber abundances in mouse quadriceps muscle. At 42 ppm rapamycin, we observed a 57% decrease in deletion frequency, a 2.8-fold decrease in ETC deficient fibers, and a 3.4-fold increase in the number of mice without electron transport chain deficient fibers. We observed a similar trend with the 14 ppm dose. DR significantly decreased ETC deficient fiber abundances with a trend toward lower mtDNA deletion frequency. The effects of rapamycin treatment on mitochondrial DNA quality were greatest in females at the highest dose. Rapamycin treatment at 14 ppm did not affect muscle mass or function. Dietary restriction also reduced deletion frequency and ETC deficient fibers. These data support the concept that the lifespan extending effects of rapamycin treatment result from enhanced mitochondrial DNA quality.
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Affiliation(s)
- Jason Bielas
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Allen Herbst
- Department of Agricultural Food and Nutritional Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Kevin Widjaja
- Department of Medicine, Division of Geriatrics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Jessica Hui
- Department of Medicine, Division of Geriatrics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Judd M Aiken
- Department of Agricultural Food and Nutritional Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Debbie McKenzie
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Richard A Miller
- Department of Pathology and Geriatrics Center, University of Michigan, Ann Arbor, MI, USA
| | - Susan V Brooks
- Department of Molecular and Integrative Physiology, Geriatrics Center, University of Michigan, Ann Arbor, MI, USA
| | - Jonathan Wanagat
- Department of Medicine, Division of Geriatrics, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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Weiland D, Brachvogel B, Hornig-Do HT, Neuhaus JF, Holzer T, Tobin DJ, Niessen CM, Wiesner RJ, Baris OR. Imbalance of Mitochondrial Respiratory Chain Complexes in the Epidermis Induces Severe Skin Inflammation. J Invest Dermatol 2018; 138:132-140. [DOI: 10.1016/j.jid.2017.08.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/16/2017] [Accepted: 08/16/2017] [Indexed: 11/24/2022]
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Hoffman TE, Barnett KJ, Wallis L, Hanneman WH. A multimethod computational simulation approach for investigating mitochondrial dynamics and dysfunction in degenerative aging. Aging Cell 2017; 16:1244-1255. [PMID: 28815872 PMCID: PMC5676065 DOI: 10.1111/acel.12644] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2017] [Indexed: 12/15/2022] Open
Abstract
Research in biogerontology has largely focused on the complex relationship between mitochondrial dysfunction and biological aging. In particular, the mitochondrial free radical theory of aging (MFRTA) has been well accepted. However, this theory has been challenged by recent studies showing minimal increases in reactive oxygen species (ROS) as not entirely deleterious in nature, and even beneficial under the appropriate cellular circumstances. To assess these significant and nonintuitive observations in the context of a functional system, we have taken an in silico approach to expand the focus of the MFRTA by including other key mitochondrial stress response pathways, as they have been observed in the nematode Caenorhabditis elegans. These include the mitochondrial unfolded protein response (UPRmt), mitochondrial biogenesis and autophagy dynamics, the relevant DAF‐16 and SKN‐1 axes, and NAD+‐dependent deacetylase activities. To integrate these pathways, we have developed a multilevel hybrid‐modeling paradigm, containing agent‐based elements among stochastic system‐dynamics environments of logically derived ordinary differential equations, to simulate aging mitochondrial phenotypes within a population of energetically demanding cells. The simulation experiments resulted in accurate predictions of physiological parameters over time that accompany normal aging, such as the declines in both NAD+ and ATP and an increase in ROS. Additionally, the in silico system was virtually perturbed using a variety of pharmacological (e.g., rapamycin, pterostilbene, paraquat) and genetic (e.g., skn‐1, daf‐16, sod‐2) schemes to quantitate the temporal alterations of specific mechanistic targets, supporting insights into molecular determinants of aging as well as cytoprotective agents that may improve neurological or muscular healthspan.
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Affiliation(s)
- Timothy E. Hoffman
- Center for Environmental Medicine College of Veterinary Medicine and Biomedical Sciences Colorado State University Fort Collins CO 80523 USA
| | - Katherine J. Barnett
- Center for Environmental Medicine College of Veterinary Medicine and Biomedical Sciences Colorado State University Fort Collins CO 80523 USA
| | - Lyle Wallis
- Center for Environmental Medicine College of Veterinary Medicine and Biomedical Sciences Colorado State University Fort Collins CO 80523 USA
| | - William H. Hanneman
- Center for Environmental Medicine College of Veterinary Medicine and Biomedical Sciences Colorado State University Fort Collins CO 80523 USA
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Siegmund SE, Yang H, Sharma R, Javors M, Skinner O, Mootha V, Hirano M, Schon EA. Low-dose rapamycin extends lifespan in a mouse model of mtDNA depletion syndrome. Hum Mol Genet 2017; 26:4588-4605. [PMID: 28973153 PMCID: PMC5886265 DOI: 10.1093/hmg/ddx341] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 07/31/2017] [Accepted: 08/24/2017] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial disorders affecting oxidative phosphorylation (OxPhos) are caused by mutations in both the nuclear and mitochondrial genomes. One promising candidate for treatment is the drug rapamycin, which has been shown to extend lifespan in multiple animal models, and which was previously shown to ameliorate mitochondrial disease in a knock-out mouse model lacking a nuclear-encoded gene specifying an OxPhos structural subunit (Ndufs4). In that model, relatively high-dose intraperitoneal rapamycin extended lifespan and improved markers of neurological disease, via an unknown mechanism. Here, we administered low-dose oral rapamycin to a knock-in (KI) mouse model of authentic mtDNA disease, specifically, progressive mtDNA depletion syndrome, resulting from a mutation in the mitochondrial nucleotide salvage enzyme thymidine kinase 2 (TK2). Importantly, low-dose oral rapamycin was sufficient to extend Tk2KI/KI mouse lifespan significantly, and did so in the absence of detectable improvements in mitochondrial dysfunction. We found no evidence that rapamycin increased survival by acting through canonical pathways, including mitochondrial autophagy. However, transcriptomics and metabolomics analyses uncovered systemic metabolic changes pointing to a potential 'rapamycin metabolic signature.' These changes also implied that rapamycin may have enabled the Tk2KI/KI mice to utilize alternative energy reserves, and possibly triggered indirect signaling events that modified mortality through developmental reprogramming. From a therapeutic standpoint, our results support the possibility that low-dose rapamycin, while not targeting the underlying mtDNA defect, could represent a crucial therapy for the treatment of mtDNA-driven, and some nuclear DNA-driven, mitochondrial diseases.
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Affiliation(s)
| | | | - Rohit Sharma
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Martin Javors
- Department of Psychiatry, University of Texas, San Antonio, TX 78229, USA
| | - Owen Skinner
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Vamsi Mootha
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | | | - Eric A Schon
- Department of Neurology
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032, USA
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Ebrahimi-Fakhari D, Saffari A, Wahlster L, Di Nardo A, Turner D, Lewis TL, Conrad C, Rothberg JM, Lipton JO, Kölker S, Hoffmann GF, Han MJ, Polleux F, Sahin M. Impaired Mitochondrial Dynamics and Mitophagy in Neuronal Models of Tuberous Sclerosis Complex. Cell Rep 2017; 17:1053-1070. [PMID: 27760312 DOI: 10.1016/j.celrep.2016.09.054] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 07/11/2016] [Accepted: 09/15/2016] [Indexed: 01/08/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is a neurodevelopmental disease caused by TSC1 or TSC2 mutations and subsequent activation of the mTORC1 kinase. Upon mTORC1 activation, anabolic metabolism, which requires mitochondria, is induced, yet at the same time the principal pathway for mitochondrial turnover, autophagy, is compromised. How mTORC1 activation impacts mitochondrial turnover in neurons remains unknown. Here, we demonstrate impaired mitochondrial homeostasis in neuronal in vitro and in vivo models of TSC. We find that Tsc1/2-deficient neurons accumulate mitochondria in cell bodies, but are depleted of axonal mitochondria, including those supporting presynaptic sites. Axonal and global mitophagy of damaged mitochondria is impaired, suggesting that decreased turnover may act upstream of impaired mitochondrial metabolism. Importantly, blocking mTORC1 or inducing mTOR-independent autophagy restores mitochondrial homeostasis. Our study clarifies the complex relationship between the TSC-mTORC1 pathway, autophagy, and mitophagy, and defines mitochondrial homeostasis as a therapeutic target for TSC and related diseases.
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Affiliation(s)
- Darius Ebrahimi-Fakhari
- The F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Afshin Saffari
- The F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Lara Wahlster
- Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany; Division of Hematology and Oncology, Stem Cell Program, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Alessia Di Nardo
- The F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Daria Turner
- The F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Tommy L Lewis
- Department of Neuroscience, Zuckerman Mind Brain Behavior Institute and Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | | | | | - Jonathan O Lipton
- The F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Stefan Kölker
- Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Georg F Hoffmann
- Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Min-Joon Han
- The F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Franck Polleux
- Department of Neuroscience, Zuckerman Mind Brain Behavior Institute and Kavli Institute for Brain Science, Columbia University, New York, NY 10027, USA
| | - Mustafa Sahin
- The F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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Lipid-based DNA/siRNA transfection agents disrupt neuronal bioenergetics and mitophagy. Biochem J 2017; 474:3887-3902. [PMID: 29025974 DOI: 10.1042/bcj20170632] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/06/2017] [Accepted: 10/09/2017] [Indexed: 12/13/2022]
Abstract
A multitude of natural and artificial compounds have been recognized to modulate autophagy, providing direct or, through associated pathways, indirect entry points to activation and inhibition. While these pharmacological tools are extremely useful in the study of autophagy, their abundance also suggests the potential presence of unidentified autophagic modulators that may interfere with experimental designs if applied unknowingly. Here, we report unanticipated effects on autophagy and bioenergetics in neuronal progenitor cells (NPCs) incubated with the widely used lipid-based transfection reagent lipofectamine (LF), which induced mitochondria depolarization followed by disruption of electron transport. When NPCs were exposed to LF for 5 h followed by 24, 48, and 72 h in LF-free media, an immediate increase in mitochondrial ROS production and nitrotyrosine formation was observed. These events were accompanied by disrupted mitophagy (accumulation of dysfunctional and damaged mitochondria, and of LC3II and p62), in an mTOR- and AMPK-independent manner, and despite the increased mitochondrial PINK1 (PTEN-inducible kinase 1) localization. Evidence supported a role for a p53-mediated abrogation of parkin translocation and/or abrogation of membrane fusion between autophagosome and lysosomes. While most of the outcomes were LF-specific, only two were shared by OptiMEM exposure (with no serum and reduced glucose levels) albeit at lower extents. Taken together, our findings show that the use of transfection reagents requires critical evaluation with respect to consequences for overall cellular health, particularly in experiments designed to address autophagy-inducing effects and/or energy stress.
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Modulating mitochondrial quality in disease transmission: towards enabling mitochondrial DNA disease carriers to have healthy children. Biochem Soc Trans 2017; 44:1091-100. [PMID: 27528757 PMCID: PMC4984448 DOI: 10.1042/bst20160095] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Indexed: 12/19/2022]
Abstract
One in 400 people has a maternally inherited mutation in mtDNA potentially causing incurable disease. In so-called heteroplasmic disease, mutant and normal mtDNA co-exist in the cells of carrier women. Disease severity depends on the proportion of inherited abnormal mtDNA molecules. Families who have had a child die of severe, maternally inherited mtDNA disease need reliable information on the risk of recurrence in future pregnancies. However, prenatal diagnosis and even estimates of risk are fraught with uncertainty because of the complex and stochastic dynamics of heteroplasmy. These complications include an mtDNA bottleneck, whereby hard-to-predict fluctuations in the proportions of mutant and normal mtDNA may arise between generations. In ‘mitochondrial replacement therapy’ (MRT), damaged mitochondria are replaced with healthy ones in early human development, using nuclear transfer. We are developing non-invasive alternatives, notably activating autophagy, a cellular quality control mechanism, in which damaged cellular components are engulfed by autophagosomes. This approach could be used in combination with MRT or with the regular management, pre-implantation genetic diagnosis (PGD). Mathematical theory, supported by recent experiments, suggests that this strategy may be fruitful in controlling heteroplasmy. Using mice that are transgenic for fluorescent LC3 (the hallmark of autophagy) we quantified autophagosomes in cleavage stage embryos. We confirmed that the autophagosome count peaks in four-cell embryos and this correlates with a drop in the mtDNA content of the whole embryo. This suggests removal by mitophagy (mitochondria-specific autophagy). We suggest that modulating heteroplasmy by activating mitophagy may be a useful complement to mitochondrial replacement therapy.
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Caicedo A, Aponte PM, Cabrera F, Hidalgo C, Khoury M. Artificial Mitochondria Transfer: Current Challenges, Advances, and Future Applications. Stem Cells Int 2017; 2017:7610414. [PMID: 28751917 PMCID: PMC5511681 DOI: 10.1155/2017/7610414] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 04/30/2017] [Accepted: 05/15/2017] [Indexed: 12/18/2022] Open
Abstract
The objective of this review is to outline existing artificial mitochondria transfer techniques and to describe the future steps necessary to develop new therapeutic applications in medicine. Inspired by the symbiotic origin of mitochondria and by the cell's capacity to transfer these organelles to damaged neighbors, many researchers have developed procedures to artificially transfer mitochondria from one cell to another. The techniques currently in use today range from simple coincubations of isolated mitochondria and recipient cells to the use of physical approaches to induce integration. These methods mimic natural mitochondria transfer. In order to use mitochondrial transfer in medicine, we must answer key questions about how to replicate aspects of natural transport processes to improve current artificial transfer methods. Another priority is to determine the optimum quantity and cell/tissue source of the mitochondria in order to induce cell reprogramming or tissue repair, in both in vitro and in vivo applications. Additionally, it is important that the field explores how artificial mitochondria transfer techniques can be used to treat different diseases and how to navigate the ethical issues in such procedures. Without a doubt, mitochondria are more than mere cell power plants, as we continue to discover their potential to be used in medicine.
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Affiliation(s)
- Andrés Caicedo
- Colegio de Ciencias de la Salud, Escuela de Medicina, Universidad San Francisco de Quito (USFQ), 170901 Quito, Ecuador
- Colegio de Ciencias Biológicas y Ambientales, Instituto de Microbiología, Universidad San Francisco de Quito (USFQ), 170901 Quito, Ecuador
- Mito-Act Research Consortium, Quito, Ecuador
| | - Pedro M. Aponte
- Mito-Act Research Consortium, Quito, Ecuador
- Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito (USFQ), 170901 Quito, Ecuador
| | - Francisco Cabrera
- Mito-Act Research Consortium, Quito, Ecuador
- Colegio de Ciencias de la Salud, Escuela de Medicina Veterinaria, Universidad San Francisco de Quito (USFQ), 170901 Quito, Ecuador
- Institute for Regenerative Medicine and Biotherapy (IRMB), INSERM U1183, 2 Montpellier University, Montpellier, France
| | - Carmen Hidalgo
- Mito-Act Research Consortium, Quito, Ecuador
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de Los Andes, Santiago, Chile
| | - Maroun Khoury
- Mito-Act Research Consortium, Quito, Ecuador
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de Los Andes, Santiago, Chile
- Consorcio Regenero, Chilean Consortium for Regenerative Medicine, Santiago, Chile
- Cells for Cells, Santiago, Chile
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Liao C, Ashley N, Diot A, Morten K, Phadwal K, Williams A, Fearnley I, Rosser L, Lowndes J, Fratter C, Ferguson DJP, Vay L, Quaghebeur G, Moroni I, Bianchi S, Lamperti C, Downes SM, Sitarz KS, Flannery PJ, Carver J, Dombi E, East D, Laura M, Reilly MM, Mortiboys H, Prevo R, Campanella M, Daniels MJ, Zeviani M, Yu-Wai-Man P, Simon AK, Votruba M, Poulton J. Dysregulated mitophagy and mitochondrial organization in optic atrophy due to OPA1 mutations. Neurology 2016; 88:131-142. [PMID: 27974645 PMCID: PMC5224718 DOI: 10.1212/wnl.0000000000003491] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 10/04/2016] [Indexed: 01/13/2023] Open
Abstract
Objective: To investigate mitophagy in 5 patients with severe dominantly inherited optic atrophy (DOA), caused by depletion of OPA1 (a protein that is essential for mitochondrial fusion), compared with healthy controls. Methods: Patients with severe DOA (DOA plus) had peripheral neuropathy, cognitive regression, and epilepsy in addition to loss of vision. We quantified mitophagy in dermal fibroblasts, using 2 high throughput imaging systems, by visualizing colocalization of mitochondrial fragments with engulfing autophagosomes. Results: Fibroblasts from 3 biallelic OPA1(−/−) patients with severe DOA had increased mitochondrial fragmentation and mitochondrial DNA (mtDNA)–depleted cells due to decreased levels of OPA1 protein. Similarly, in siRNA-treated control fibroblasts, profound OPA1 knockdown caused mitochondrial fragmentation, loss of mtDNA, impaired mitochondrial function, and mitochondrial mislocalization. Compared to controls, basal mitophagy (abundance of autophagosomes colocalizing with mitochondria) was increased in (1) biallelic patients, (2) monoallelic patients with DOA plus, and (3) OPA1 siRNA–treated control cultures. Mitophagic flux was also increased. Genetic knockdown of the mitophagy protein ATG7 confirmed this by eliminating differences between patient and control fibroblasts. Conclusions: We demonstrated increased mitophagy and excessive mitochondrial fragmentation in primary human cultures associated with DOA plus due to biallelic OPA1 mutations. We previously found that increased mitophagy (mitochondrial recycling) was associated with visual loss in another mitochondrial optic neuropathy, Leber hereditary optic neuropathy (LHON). Combined with our LHON findings, this implicates excessive mitochondrial fragmentation, dysregulated mitophagy, and impaired response to energetic stress in the pathogenesis of mitochondrial optic neuropathies, potentially linked with mitochondrial mislocalization and mtDNA depletion.
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Affiliation(s)
- Chunyan Liao
- Author affiliations are provided at the end of the article
| | - Neil Ashley
- Author affiliations are provided at the end of the article
| | - Alan Diot
- Author affiliations are provided at the end of the article
| | - Karl Morten
- Author affiliations are provided at the end of the article
| | | | | | - Ian Fearnley
- Author affiliations are provided at the end of the article
| | - Lyndon Rosser
- Author affiliations are provided at the end of the article
| | - Jo Lowndes
- Author affiliations are provided at the end of the article
| | - Carl Fratter
- Author affiliations are provided at the end of the article
| | | | - Laura Vay
- Author affiliations are provided at the end of the article
| | | | | | | | | | - Susan M Downes
- Author affiliations are provided at the end of the article
| | - Kamil S Sitarz
- Author affiliations are provided at the end of the article
| | | | - Janet Carver
- Author affiliations are provided at the end of the article
| | - Eszter Dombi
- Author affiliations are provided at the end of the article
| | - Daniel East
- Author affiliations are provided at the end of the article
| | - Matilde Laura
- Author affiliations are provided at the end of the article
| | - Mary M Reilly
- Author affiliations are provided at the end of the article
| | | | - Remko Prevo
- Author affiliations are provided at the end of the article
| | | | | | | | | | | | | | - Joanna Poulton
- Author affiliations are provided at the end of the article.
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Kandul NP, Zhang T, Hay BA, Guo M. Selective removal of deletion-bearing mitochondrial DNA in heteroplasmic Drosophila. Nat Commun 2016; 7:13100. [PMID: 27841259 PMCID: PMC5114534 DOI: 10.1038/ncomms13100] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/01/2016] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial DNA (mtDNA) often exists in a state of heteroplasmy, in which mutant mtDNA co-exists in cells with wild-type mtDNA. High frequencies of pathogenic mtDNA result in maternally inherited diseases; maternally and somatically acquired mutations also accumulate over time and contribute to diseases of ageing. Reducing heteroplasmy is therefore a therapeutic goal and in vivo models in post-mitotic tissues are needed to facilitate these studies. Here we describe a transgene-based model of a heteroplasmic lethal mtDNA deletion (mtDNAΔ) in adult Drosophila muscle. Stimulation of autophagy, activation of the PINK1/parkin pathway or decreased levels of mitofusin result in a selective decrease in mtDNAΔ. Decreased levels of mitofusin and increased levels of ATPIF1, an inhibitor of ATP synthase reversal-dependent mitochondrial repolarization, result in a further decrease in mtDNAΔ levels. These results show that an adult post-mitotic tissue can be cleansed of a deleterious genome, suggesting that therapeutic removal of mutant mtDNA can be achieved.
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Affiliation(s)
- Nikolay P. Kandul
- Division of Biology and Biological Engineering, California Institute of Technology, Mail Code 156-29, 1200 E. California blvd., Pasadena, California 91125, USA
| | - Ting Zhang
- Department of Neurology, Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, USA
- Department of Molecular and Medical Pharmacology, Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - Bruce A. Hay
- Division of Biology and Biological Engineering, California Institute of Technology, Mail Code 156-29, 1200 E. California blvd., Pasadena, California 91125, USA
| | - Ming Guo
- Department of Neurology, Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, USA
- Department of Molecular and Medical Pharmacology, Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, USA
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Su X, Wang W, Ruan G, Liang M, Zheng J, Chen Y, Wu H, Fahey TJ, Guan M, Teng L. A Comprehensive Characterization of Mitochondrial Genome in Papillary Thyroid Cancer. Int J Mol Sci 2016; 17:ijms17101594. [PMID: 27735863 PMCID: PMC5085627 DOI: 10.3390/ijms17101594] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/17/2016] [Accepted: 09/08/2016] [Indexed: 01/24/2023] Open
Abstract
Nuclear genetic alterations have been widely investigated in papillary thyroid cancer (PTC), however, the characteristics of the mitochondrial genome remain uncertain. We sequenced the entire mitochondrial genome of 66 PTCs, 16 normal thyroid tissues and 376 blood samples of healthy individuals. There were 2508 variations (543 sites) detected in PTCs, among which 33 variations were novel. Nearly half of the PTCs (31/66) had heteroplasmic variations. Among the 31 PTCs, 28 specimens harbored a total of 52 somatic mutations distributed in 44 sites. Thirty-three variations including seven nonsense, 11 frameshift and 15 non-synonymous variations selected by bioinformatic software were regarded as pathogenic. These 33 pathogenic mutations were associated with older age (p = 0.0176) and advanced tumor stage (p = 0.0218). In addition, they tended to be novel (p = 0.0003), heteroplasmic (p = 0.0343) and somatic (p = 0.0018). The mtDNA copy number increased in more than two-third (46/66) of PTCs, and the average content in tumors was nearly four times higher than that in adjacent normal tissues (p < 0.0001). Three sub-haplogroups of N (A4, B4a and B4g) and eight single-nucleotide polymorphisms (mtSNPs) (A16164G, C16266T, G5460A, T6680C, G9123A, A14587G, T16362C, and G709A) were associated with the occurrence of PTC. Here we report a comprehensive characterization of the mitochondrial genome and demonstrate its significance in pathogenesis and progression of PTC. This can help to clarify the molecular mechanisms underlying PTC and offer potential biomarkers or therapeutic targets for future clinical practice.
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Affiliation(s)
- Xingyun Su
- Department of Surgical Oncology, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China.
| | - Weibin Wang
- Department of Surgical Oncology, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China.
| | - Guodong Ruan
- Department of Oncology, the Second Hospital of Shaoxing, Shaoxing 312000, China.
| | - Min Liang
- Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou 310058, China.
| | - Jing Zheng
- Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou 310058, China.
| | - Ye Chen
- Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou 310058, China.
| | - Huiling Wu
- Department of Plastic Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China.
| | - Thomas J Fahey
- Department of Surgery, New York Presbyterian Hospital and Weill Medical College of Cornell University, New York, NY 10021, USA.
| | - Minxin Guan
- Institute of Genetics, School of Medicine, Zhejiang University, Hangzhou 310058, China.
| | - Lisong Teng
- Department of Surgical Oncology, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China.
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Torralba D, Baixauli F, Sánchez-Madrid F. Mitochondria Know No Boundaries: Mechanisms and Functions of Intercellular Mitochondrial Transfer. Front Cell Dev Biol 2016; 4:107. [PMID: 27734015 PMCID: PMC5039171 DOI: 10.3389/fcell.2016.00107] [Citation(s) in RCA: 260] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 09/14/2016] [Indexed: 12/25/2022] Open
Abstract
Mitochondria regulate multiple cell processes, including calcium signaling, apoptosis and cell metabolism. Mitochondria contain their own circular genome encoding selected subunits of the oxidative phosphorylation complexes. Recent findings reveal that, in addition to being maternally inherited, mitochondria can traverse cell boundaries and thus be horizontally transferred between cells. Although, the physiological relevance of this phenomenon is still under debate, mitochondria uptake rescues mitochondrial respiration defects in recipient cells and regulates signaling, proliferation or chemotherapy resistance in vitro and in vivo. In this review, we outline the pathophysiological consequences of horizontal mitochondrial transfer and offer a perspective on the cellular and molecular mechanisms mediating their intercellular transmission, including tunneling nanotubes, extracellular vesicles, cellular fusion, and GAP junctions. The physiological relevance of mitochondrial transfer and the potential therapeutic application of this exchange for treating mitochondrial-related diseases are discussed.
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Affiliation(s)
- Daniel Torralba
- Signaling and Inflammation Program, Centro Nacional Investigaciones CardiovascularesMadrid, Spain; Servicio de Inmunología, Instituto Investigación Sanitaria Princesa, Universidad Autonoma de MadridMadrid, Spain
| | - Francesc Baixauli
- Signaling and Inflammation Program, Centro Nacional Investigaciones CardiovascularesMadrid, Spain; Servicio de Inmunología, Instituto Investigación Sanitaria Princesa, Universidad Autonoma de MadridMadrid, Spain
| | - Francisco Sánchez-Madrid
- Signaling and Inflammation Program, Centro Nacional Investigaciones CardiovascularesMadrid, Spain; Servicio de Inmunología, Instituto Investigación Sanitaria Princesa, Universidad Autonoma de MadridMadrid, Spain
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49
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Malena A, Pantic B, Borgia D, Sgarbi G, Solaini G, Holt IJ, Spinazzola A, Perissinotto E, Sandri M, Baracca A, Vergani L. Mitochondrial quality control: Cell-type-dependent responses to pathological mutant mitochondrial DNA. Autophagy 2016; 12:2098-2112. [PMID: 27627835 DOI: 10.1080/15548627.2016.1226734] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Pathological mutations in the mitochondrial DNA (mtDNA) produce a diverse range of tissue-specific diseases and the proportion of mutant mitochondrial DNA can increase or decrease with time via segregation, dependent on the cell or tissue type. Previously we found that adenocarcinoma (A549.B2) cells favored wild-type (WT) mtDNA, whereas rhabdomyosarcoma (RD.Myo) cells favored mutant (m3243G) mtDNA. Mitochondrial quality control (mtQC) can purge the cells of dysfunctional mitochondria via mitochondrial dynamics and mitophagy and appears to offer the perfect solution to the human diseases caused by mutant mtDNA. In A549.B2 and RD.Myo cybrids, with various mutant mtDNA levels, mtQC was explored together with macroautophagy/autophagy and bioenergetic profile. The 2 types of tumor-derived cell lines differed in bioenergetic profile and mitophagy, but not in autophagy. A549.B2 cybrids displayed upregulation of mitophagy, increased mtDNA removal, mitochondrial fragmentation and mitochondrial depolarization on incubation with oligomycin, parameters that correlated with mutant load. Conversely, heteroplasmic RD.Myo lines had lower mitophagic markers that negatively correlated with mutant load, combined with a fully polarized and highly fused mitochondrial network. These findings indicate that pathological mutant mitochondrial DNA can modulate mitochondrial dynamics and mitophagy in a cell-type dependent manner and thereby offer an explanation for the persistence and accumulation of deleterious variants.
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Affiliation(s)
- Adriana Malena
- a Department of Neurosciences , University of Padova , Italy
| | - Boris Pantic
- a Department of Neurosciences , University of Padova , Italy
| | - Doriana Borgia
- a Department of Neurosciences , University of Padova , Italy
| | - Gianluca Sgarbi
- b Department of Biomedical and Neuromotor Sciences , University of Bologna , Italy
| | - Giancarlo Solaini
- b Department of Biomedical and Neuromotor Sciences , University of Bologna , Italy
| | - Ian J Holt
- c Medical Research Council, Mill Hill Laboratory , London , United Kingdom
| | | | - Egle Perissinotto
- d Department of Cardiac, Thoracic and Vascular Sciences, Biostatistics, Epidemiology and Public Health Unit , University of Padova , Padova , Italy
| | - Marco Sandri
- e Department of Biomedical Sciences , University of Padova , Italy.,f Venetian Institute of Molecular Medicine , Padova , Italy
| | - Alessandra Baracca
- b Department of Biomedical and Neuromotor Sciences , University of Bologna , Italy
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50
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Lopez Sanchez M, Crowston J, Mackey D, Trounce I. Emerging Mitochondrial Therapeutic Targets in Optic Neuropathies. Pharmacol Ther 2016; 165:132-52. [DOI: 10.1016/j.pharmthera.2016.06.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Indexed: 12/14/2022]
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