51
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Young MJ. Off-Target Effects of Drugs that Disrupt Human Mitochondrial DNA Maintenance. Front Mol Biosci 2017; 4:74. [PMID: 29214156 PMCID: PMC5702650 DOI: 10.3389/fmolb.2017.00074] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 10/31/2017] [Indexed: 12/17/2022] Open
Abstract
Nucleoside reverse transcriptase inhibitors (NRTIs) were the first drugs used to treat human immunodeficiency virus (HIV) the cause of acquired immunodeficiency syndrome. Development of severe mitochondrial toxicity has been well documented in patients infected with HIV and administered NRTIs. In vitro biochemical experiments have demonstrated that the replicative mitochondrial DNA (mtDNA) polymerase gamma, Polg, is a sensitive target for inhibition by metabolically active forms of NRTIs, nucleotide reverse transcriptase inhibitors (NtRTIs). Once incorporated into newly synthesized daughter strands NtRTIs block further DNA polymerization reactions. Human cell culture and animal studies have demonstrated that cell lines and mice exposed to NRTIs display mtDNA depletion. Further complicating NRTI off-target effects on mtDNA maintenance, two additional DNA polymerases, Pol beta and PrimPol, were recently reported to localize to mitochondria as well as the nucleus. Similar to Polg, in vitro work has demonstrated both Pol beta and PrimPol incorporate NtRTIs into nascent DNA. Cell culture and biochemical experiments have also demonstrated that antiviral ribonucleoside drugs developed to treat hepatitis C infection act as off-target substrates for POLRMT, the mitochondrial RNA polymerase and primase. Accompanying the above-mentioned topics, this review examines: (1) mtDNA maintenance in human health and disease, (2) reports of DNA polymerases theta and zeta (Rev3) localizing to mitochondria, and (3) additional drugs with off-target effects on mitochondrial function. Lastly, mtDNA damage may induce cell death; therefore, the possibility of utilizing compounds that disrupt mtDNA maintenance to kill cancer cells is discussed.
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Affiliation(s)
- Matthew J Young
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL, United States
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52
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Song X, Fiati Kenston SS, Kong L, Zhao J. Molecular mechanisms of nickel induced neurotoxicity and chemoprevention. Toxicology 2017; 392:47-54. [PMID: 29032222 DOI: 10.1016/j.tox.2017.10.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 10/08/2017] [Accepted: 10/10/2017] [Indexed: 01/05/2023]
Abstract
Nickel (Ni) is widely used in many industrial sectors such as alloy, welding, printing inks, electrical and electronics industries. Excessive environmental or occupational exposure to Ni may result in tumor, contact dermatitis, as well as damages to the nervous system. In recent years, more and more research has demonstrated that Ni induced nerve damages are related to mitochondrial dysfunction. In this paper, we try to characterize Ni induced neurotoxicity as well as the underlying mechanisms, and how to find new drugs for chemoprevention, by reviewing chemicals with neuroprotective effects on Ni induced neurotoxicity.
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Affiliation(s)
- Xin Song
- Department of Preventative Medicine, Zhejiang Key Laboratory of Pathophysiology, Medicine School of Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang Province, 315211, People's Republic of China
| | - Samuel Selorm Fiati Kenston
- Department of Preventative Medicine, Zhejiang Key Laboratory of Pathophysiology, Medicine School of Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang Province, 315211, People's Republic of China
| | - Lu Kong
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, Jiangsu, People's Republic of China
| | - Jinshun Zhao
- Department of Preventative Medicine, Zhejiang Key Laboratory of Pathophysiology, Medicine School of Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang Province, 315211, People's Republic of China.
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53
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Fernando MR, Jiang C, Krzyzanowski GD, Ryan WL. New evidence that a large proportion of human blood plasma cell-free DNA is localized in exosomes. PLoS One 2017; 12:e0183915. [PMID: 28850588 PMCID: PMC5574584 DOI: 10.1371/journal.pone.0183915] [Citation(s) in RCA: 184] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 08/14/2017] [Indexed: 11/19/2022] Open
Abstract
Cell-free DNA (cfDNA) in blood is used as a source of genetic material for noninvasive prenatal and cancer diagnostic assays in clinical practice. Recently we have started a project for new biomarker discovery with a view to developing new noninvasive diagnostic assays. While reviewing literature, it was found that exosomes may be a rich source of biomarkers, because exosomes play an important role in human health and disease. While characterizing exosomes found in human blood plasma, we observed the presence of cfDNA in plasma exosomes. Plasma was obtained from blood drawn into K3EDTA tubes. Exosomes were isolated from cell-free plasma using a commercially available kit. Sizing and enumeration of exosomes were done using electron microscopy and NanoSight particle counter. NanoSight and confocal microscopy was used to demonstrate the association between dsDNA and exosomes. DNA extracted from plasma and exosomes was measured by a fluorometric method and a droplet digital PCR (ddPCR) method. Size of extracellular vesicles isolated from plasma was heterogeneous and showed a mean value of 92.6 nm and a mode 39.7 nm. A large proportion of extracellular vesicles isolated from plasma were identified as exosomes using a fluorescence probe specific for exosomes and three protein markers, Hsp70, CD9 and CD63, that are commonly used to identify exosome fraction. Fluorescence dye that stain dsDNA showed the association between exosomes and dsDNA. Plasma cfDNA concentration analysis showed more than 93% of amplifiable cfDNA in plasma is located in plasma exosomes. Storage of a blood sample showed significant increases in exosome count and exosome DNA concentration. This study provide evidence that a large proportion of plasma cfDNA is localized in exosomes. Exosome release from cells is a metabolic energy dependent process, thus suggesting active release of cfDNA from cells as a source of cfDNA in plasma.
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Affiliation(s)
- M. Rohan Fernando
- Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Omaha, NE, United States of America
- Department of Research and Development, CFGenome®, Omaha, NE, United States of America
- * E-mail:
| | - Chao Jiang
- Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Omaha, NE, United States of America
| | - Gary D. Krzyzanowski
- Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Omaha, NE, United States of America
- Department of Research and Development, CFGenome®, Omaha, NE, United States of America
| | - Wayne L. Ryan
- Department of Research and Development, CFGenome®, Omaha, NE, United States of America
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54
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Desai R, Frazier AE, Durigon R, Patel H, Jones AW, Dalla Rosa I, Lake NJ, Compton AG, Mountford HS, Tucker EJ, Mitchell ALR, Jackson D, Sesay A, Di Re M, van den Heuvel LP, Burke D, Francis D, Lunke S, McGillivray G, Mandelstam S, Mochel F, Keren B, Jardel C, Turner AM, Ian Andrews P, Smeitink J, Spelbrink JN, Heales SJ, Kohda M, Ohtake A, Murayama K, Okazaki Y, Lombès A, Holt IJ, Thorburn DR, Spinazzola A. ATAD3 gene cluster deletions cause cerebellar dysfunction associated with altered mitochondrial DNA and cholesterol metabolism. Brain 2017; 140:1595-1610. [PMID: 28549128 PMCID: PMC5445257 DOI: 10.1093/brain/awx094] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 03/09/2017] [Indexed: 12/03/2022] Open
Abstract
Although mitochondrial disorders are clinically heterogeneous, they frequently involve the central nervous system and are among the most common neurogenetic disorders. Identifying the causal genes has benefited enormously from advances in high-throughput sequencing technologies; however, once the defect is known, researchers face the challenge of deciphering the underlying disease mechanism. Here we characterize large biallelic deletions in the region encoding the ATAD3C, ATAD3B and ATAD3A genes. Although high homology complicates genomic analysis of the ATAD3 defects, they can be identified by targeted analysis of standard single nucleotide polymorphism array and whole exome sequencing data. We report deletions that generate chimeric ATAD3B/ATAD3A fusion genes in individuals from four unrelated families with fatal congenital pontocerebellar hypoplasia, whereas a case with genomic rearrangements affecting the ATAD3C/ATAD3B genes on one allele and ATAD3B/ATAD3A genes on the other displays later-onset encephalopathy with cerebellar atrophy, ataxia and dystonia. Fibroblasts from affected individuals display mitochondrial DNA abnormalities, associated with multiple indicators of altered cholesterol metabolism. Moreover, drug-induced perturbations of cholesterol homeostasis cause mitochondrial DNA disorganization in control cells, while mitochondrial DNA aggregation in the genetic cholesterol trafficking disorder Niemann-Pick type C disease further corroborates the interdependence of mitochondrial DNA organization and cholesterol. These data demonstrate the integration of mitochondria in cellular cholesterol homeostasis, in which ATAD3 plays a critical role. The dual problem of perturbed cholesterol metabolism and mitochondrial dysfunction could be widespread in neurological and neurodegenerative diseases.
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Affiliation(s)
- Radha Desai
- MRC Laboratory, Mill Hill, London NW71AA, UK
| | - Ann E Frazier
- Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Melbourne VIC 3052, Australia
| | - Romina Durigon
- Department of Clinical Neurosciences, Institute of Neurology, Royal Free Campus, University College London, NW3 2PF, UK
| | - Harshil Patel
- Bioinformatics and Biostatistics, Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Aleck W Jones
- Department of Clinical Neurosciences, Institute of Neurology, Royal Free Campus, University College London, NW3 2PF, UK
| | - Ilaria Dalla Rosa
- Department of Clinical Neurosciences, Institute of Neurology, Royal Free Campus, University College London, NW3 2PF, UK
| | - Nicole J Lake
- Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Melbourne VIC 3052, Australia
| | - Alison G Compton
- Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Melbourne VIC 3052, Australia
| | - Hayley S Mountford
- Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Melbourne VIC 3052, Australia
| | - Elena J Tucker
- Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Melbourne VIC 3052, Australia
| | - Alice L R Mitchell
- Department of Clinical Neurosciences, Institute of Neurology, Royal Free Campus, University College London, NW3 2PF, UK
| | - Deborah Jackson
- Bioinformatics and Biostatistics, Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Abdul Sesay
- Bioinformatics and Biostatistics, Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Miriam Di Re
- Mitochondrial Biology Unit, Hills Road, Cambridge, CB2 0XY, UK
| | - Lambert P van den Heuvel
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Derek Burke
- Department of Genetics and Genomic Medicine, Institute of Child Health, University College London, London, UK and Laboratory Medicine, Great Ormond Street Hospital, London, UK
| | - David Francis
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne VIC 3052, Australia
| | - Sebastian Lunke
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne VIC 3052, Australia.,Department of Pathology, University of Melbourne, Melbourne 3052, Australia
| | - George McGillivray
- MRC Laboratory, Mill Hill, London NW71AA, UK.,Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne VIC 3052, Australia
| | - Simone Mandelstam
- Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Melbourne VIC 3052, Australia.,The Florey Institute of Neuroscience and Mental Health Melbourne, Australia.,Departments of Radiology and Paediatrics, University of Melbourne, Melbourne, Australia
| | - Fanny Mochel
- AP-HP, Department of Genetics, GHU Pitié-Salpêtrière, Paris, F-75651 France.,Inserm U975; CNRS UMR 7225, ICM; F-75013, Paris, France
| | - Boris Keren
- Inserm U975; CNRS UMR 7225, ICM; F-75013, Paris, France.,AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, GHU Pitié-Salpêtrière, Paris, F-75651 France
| | - Claude Jardel
- AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, GHU Pitié-Salpêtrière, Paris, F-75651 France.,Inserm U1016; CNRS UMR 8104; Université Paris-Descartes-Paris 5; Institut Cochin, 75014 Paris, France
| | - Anne M Turner
- Department of Clinical Genetics, Sydney Children's Hospital, Sydney, NSW, Australia.,School of Women's and Children's Health, University of New South Wales, Kensington, NSW, Australia
| | - P Ian Andrews
- School of Women's and Children's Health, University of New South Wales, Kensington, NSW, Australia.,Department of Paediatric Neurology, Sydney Children's Hospital, Sydney, NSW, Australia
| | - Jan Smeitink
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Johannes N Spelbrink
- Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Simon J Heales
- Department of Genetics and Genomic Medicine, Institute of Child Health, University College London, London, UK and Laboratory Medicine, Great Ormond Street Hospital, London, UK.,Department of Molecular Neuroscience, Institute of Neurology, University College London, Queen Square, London, UK
| | - Masakazu Kohda
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Akira Ohtake
- Department of Pediatrics, Saitama Medical University, Moroyama-machi, Iruma-gun, Saitama, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Yasushi Okazaki
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan.,Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka-shi, Saitama, Japan
| | - Anne Lombès
- MRC Laboratory, Mill Hill, London NW71AA, UK.,Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ian J Holt
- MRC Laboratory, Mill Hill, London NW71AA, UK.,Department of Clinical Neurosciences, Institute of Neurology, Royal Free Campus, University College London, NW3 2PF, UK.,Biodonostia Health Research Institute, 20014 San Sebastián, Spain. IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
| | - David R Thorburn
- Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Melbourne VIC 3052, Australia.,Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne VIC 3052, Australia
| | - Antonella Spinazzola
- Department of Clinical Neurosciences, Institute of Neurology, Royal Free Campus, University College London, NW3 2PF, UK.,MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
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55
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Chen MH, Wang FX, Cao JJ, Tan CP, Ji LN, Mao ZW. Light-Up Mitophagy in Live Cells with Dual-Functional Theranostic Phosphorescent Iridium(III) Complexes. ACS APPLIED MATERIALS & INTERFACES 2017; 9:13304-13314. [PMID: 28345337 DOI: 10.1021/acsami.7b01735] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Phosphorescent Ir(III) complexes are expected to be new multifunctional theranostic platforms that enable the integration of imaging capabilities and anticancer properties. Mitophagy is an important selective autophagic process that degrades dysfunctional mitochondria. Until now, the regulation of mitophagy is still poorly understood. Herein, we present two phosphorescent cyclometalated iridium(III) complexes (Ir1 and Ir2) that can accumulate in mitochondria and induce mitophagy. Because of their intrinsic phosphorescence, they can specially image mitochondria and track mitochondrial morphological alterations. Mechanism studies show that Ir1 and Ir2 induce mitophagy by depolarization of mitochondrial membrane potential, depletion of cellular ATP, perturbation in mitochondrial metabolic status, and induction of oxidative stress. Moreover, no sign of apoptosis is observed in Ir1- and Ir2-treated cells under the same conditions that an obvious mitophagic response is initiated. We demonstrate that Ir1 is a promising theranostic agent that can induce mitophagy and visualize changes in mitochondrial morphology simultaneously.
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Affiliation(s)
- Mu-He Chen
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, P. R. China
| | - Fang-Xin Wang
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, P. R. China
| | - Jian-Jun Cao
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, P. R. China
| | - Cai-Ping Tan
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, P. R. China
| | - Liang-Nian Ji
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, P. R. China
| | - Zong-Wan Mao
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, P. R. China
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56
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O’Brien PJ, Edvardsson A. Validation of a Multiparametric, High-Content-Screening Assay for Predictive/Investigative Cytotoxicity: Evidence from Technology Transfer Studies and Literature Review. Chem Res Toxicol 2017; 30:804-829. [PMID: 28147486 DOI: 10.1021/acs.chemrestox.6b00403] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Peter James O’Brien
- School
of Veterinary Medicine, University College Dublin, Stillorgan Road, Belfield, Dublin 4, Ireland
- Advanced Diagnostic Laboratory, Park West Enterprise Centre, Lavery Avenue, Park West, Dublin 12, Ireland
| | - Anna Edvardsson
- School
of Veterinary Medicine, University College Dublin, Stillorgan Road, Belfield, Dublin 4, Ireland
- Advanced Diagnostic Laboratory, Park West Enterprise Centre, Lavery Avenue, Park West, Dublin 12, Ireland
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57
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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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58
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Autophagosome-lysosome fusion triggers a lysosomal response mediated by TLR9 and controlled by OCRL. Nat Cell Biol 2016; 18:839-850. [PMID: 27398910 PMCID: PMC5040511 DOI: 10.1038/ncb3386] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 06/09/2016] [Indexed: 12/14/2022]
Abstract
Phosphoinositides (PtdIns) control fundamental cell processes, and inherited defects of PtdIns kinases or phosphatases cause severe human diseases, including Lowe syndrome due to mutations in OCRL, which encodes a PtdIns(4,5)P2 5-phosphatase. Here we unveil a lysosomal response to the arrival of autophagosomal cargo in which OCRL plays a key part. We identify mitochondrial DNA and TLR9 as the cargo and the receptor that triggers and mediates, respectively, this response. This lysosome-cargo response is required to sustain the autophagic flux and involves a local increase in PtdIns(4,5)P2 that is confined in space and time by OCRL. Depleting or inhibiting OCRL leads to an accumulation of lysosomal PtdIns(4,5)P2, an inhibitor of the calcium channel mucolipin-1 that controls autophagosome-lysosome fusion. Hence, autophagosomes accumulate in OCRL-depleted cells and in the kidneys of Lowe syndrome patients. Importantly, boosting the activity of mucolipin-1 with selective agonists restores the autophagic flux in cells from Lowe syndrome patients.
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59
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Tajiri N, Borlongan CV, Kaneko Y. Cyclosporine A Treatment Abrogates Ischemia-Induced Neuronal Cell Death by Preserving Mitochondrial Integrity through Upregulation of the Parkinson's Disease-Associated Protein DJ-1. CNS Neurosci Ther 2016; 22:602-10. [PMID: 27247192 PMCID: PMC5189675 DOI: 10.1111/cns.12546] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 03/04/2016] [Accepted: 03/06/2016] [Indexed: 12/28/2022] Open
Abstract
Aims Hypoxic‐ischemia alters mitochondrial membrane potential (Δψm), respiratory‐related enzymes, and mitochondrial DNA (mtDNA). Drugs acting on mitochondria, such as cyclosporine A (CsA), may reveal novel mitochondria‐based cell death signaling targets for stroke. Our previous studies showed that Parkinson's disease‐associated protein DJ‐1 participates in the acute endogenous neuroprotection after stroke via mitochondrial pathway. DJ‐1 was detected immediately after stroke and efficiently translocated into the mitochondria offering a new venue for developing treatment strategies against stroke. Here, we examined a molecular interaction between CsA and mitochondrial integrity in the in vitro acute stroke model of oxygen glucose deprivation/reperfusion (OGD/R) injury with emphasis on DJ‐1. Methods Primary rat neuronal cells (PRNCs) were exposed to OGD/R injury and processed for immunocytochemistry, ELISA, and mitochondria‐based molecular assays to reveal the role of DJ‐1 in CsA modulation of mitochondrial integrity. Results Administration of CsA before stroke onset (24 h pre‐OGD/R) afforded significantly much more robust neuroprotective effects than when CsA was initiated after stroke (2 h post‐OGD/R), revealing that CsA exerted neuroprotection in the early phase of ischemic stroke. CsA prevented the mitochondria‐dependent cell death signaling pathway involved in cytochrome c (Cyt c)‐induced intrinsic apoptotic process. CsA preserved cellular ATP content, but not hexokinase activity under hypoxic conditions. CsA prevented both mtDNA decrement and Δψm degradation after reperfusion, and enhanced secretion of DJ‐1 in the mitochondria, coupled with reduced oxidative stress. Conclusion These observations provided evidence that CsA maintained mitochondrial integrity likely via DJ‐1 upregulation, supporting the concept that mitochondria‐based treatments targeting the early phase of disease progression may prove beneficial in stroke.
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Affiliation(s)
- Naoki Tajiri
- Center of Excellence for Aging & Brain Repair, Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL, USA.,School of Physical Therapy & Rehabilitation Sciences, University of South Florida Morsani College of Medicine, Tampa, FL, USA
| | - Cesar V Borlongan
- Center of Excellence for Aging & Brain Repair, Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL, USA
| | - Yuji Kaneko
- Center of Excellence for Aging & Brain Repair, Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL, USA
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60
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Wisnovsky S, Jean SR, Liyanage S, Schimmer A, Kelley SO. Mitochondrial DNA repair and replication proteins revealed by targeted chemical probes. Nat Chem Biol 2016; 12:567-73. [DOI: 10.1038/nchembio.2102] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 03/24/2016] [Indexed: 01/16/2023]
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61
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Ligasová A, Koberna K. Tracking Mitochondrial DNA In Situ. Methods Mol Biol 2016; 1351:81-92. [PMID: 26530676 DOI: 10.1007/978-1-4939-3040-1_7] [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] [Indexed: 06/05/2023]
Abstract
The methods of the detection of (1) non-labeled and (2) BrdU-labeled mitochondrial DNA (mtDNA) are described. They are based on the production of singlet oxygen by monovalent copper ions and the subsequent induction of DNA gaps. The ends of interrupted DNA serve as origins for the labeling of mtDNA by DNA polymerase I or they are utilized by exonuclease that degrades DNA strands, unmasking BrdU in BrdU-labeled DNA. Both methods are sensitive approaches without the need of additional enhancement of the signal or the use of highly sensitive optical systems.
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Affiliation(s)
- Anna Ligasová
- Faculty of Medicine, Institute of Molecular and Translational Medicine, Palacký University, Hněvotínska 5, Olomouc, 77900, Czech Republic
| | - Karel Koberna
- Faculty of Medicine, Institute of Molecular and Translational Medicine, Palacký University, Hněvotínska 5, Olomouc, 77900, Czech Republic.
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Eyvazzadeh N, Neshasteh-Riz A, Mahdavi SR, Mohsenifar A. Genotoxic Damage to Glioblastoma Cells Treated with 6 MV X-Radiation in The Presence or Absence of Methoxy Estradiol, IUDR or Topotecan. CELL JOURNAL 2015. [PMID: 26199910 PMCID: PMC4503845 DOI: 10.22074/cellj.2016.3738] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Objective To explore the cumulative genotoxic damage to glioblastoma (GBM) cells,
grown as multicellular spheroids, following exposure to 6 MV X-rays (2 Gy, 22 Gy) with or
without, 2- methoxy estradiol (2ME2), iododeoxyuridine (IUDR) or topotecan (TPT), using
the Picogreen assay.
Materials and Methods The U87MG cells cultured as spheroids were treated with 6
MV X-ray using linear accelerator. Specimens were divided into five groups and irradiated using X-ray giving the dose of 2 Gy after sequentially incubated with one of
the following three drug combinations: TPT, 2-ME2/TPT, IUDR/TPT or 2ME2/IUDR/
TPT. One specimen was used as the irradiated only sample (R). The last group was
also irradiated with total dose of 22 Gy (each time 2 Gy) of 6 MV X-ray in 11 fractions
and treated for three times. DNA damage was evaluated using the Picogreen method
in the experimental study.
Results R/TPT treated group had more DNA damage [double strand break (DSB)/single strand break (SSB)] compared with the untreated group (P<0.05). Moreover the R/
TPT group treated with 2ME2 followed by IUDR had maximum DNA damage in spheroid
GBM indicating an augmented genotoxicity in the cells. The DNA damage was induced
after seven fractionated irradiation and two sequential treatments with 2ME2/IUDR/TPT.
To ensure accuracy of the slope of dose response curve the fractionated radiation was
calculated as 7.36 Gy with respect to α/β ratio based on biologically effective dose (BED)
formulae.
Conclusion Cells treated with 2ME2/IUDR showed more sensitivity to radiation and
accumulative DNA damage. DNA damage was significantly increased when GBM
cells treated with TPT ceased at S phase due to the inhibition of topoisomerase
enzyme and phosphorylation of Chk1 enzyme. These results suggest that R/TPT-
treated cells increase sensitivity to 2ME2 and IUDR especially when they are used
together. Therefore, due to an increase in the level of DNA damage (SSB vs. DSB)
and impairment of DNA repair machinery, more cell death will occur. This in turn may
improve the treatment of GBM.
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Affiliation(s)
- Nazila Eyvazzadeh
- Radiation Research Center, Faculty of Paramedicine, AJA University of Medical Sciences, Tehran, Iran
| | - Ali Neshasteh-Riz
- Department of Radiology, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Seyed Rabee Mahdavi
- Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
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Generation of Rho Zero Cells: Visualization and Quantification of the mtDNA Depletion Process. Int J Mol Sci 2015; 16:9850-65. [PMID: 25941929 PMCID: PMC4463621 DOI: 10.3390/ijms16059850] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/14/2015] [Accepted: 04/22/2015] [Indexed: 11/16/2022] Open
Abstract
Human mitochondrial DNA (mtDNA) is located in discrete DNA-protein complexes, so called nucleoids. These structures can be easily visualized in living cells by utilizing the fluorescent stain PicoGreen®. In contrary, cells devoid of endogenous mitochondrial genomes (ρ0 cells) display no mitochondrial staining in the cytoplasm. A modified restriction enzyme can be targeted to mitochondria to cleave the mtDNA molecules in more than two fragments, thereby activating endogenous nucleases. By applying this novel enzymatic approach to generate mtDNA-depleted cells the destruction of mitochondrial nucleoids in cultured cells could be detected in a time course. It is clear from these experiments that mtDNA-depleted cells can be seen as early as 48 h post-transfection using the depletion system. To prove that mtDNA is degraded during this process, mtDNA of transfected cells was quantified by real-time PCR. A significant decline could be observed 24 h post-transfection. Combination of both results showed that mtDNA of transfected cells is completely degraded and, therefore, ρ0 cells were generated within 48 h. Thus, the application of a mitochondrially-targeted restriction endonuclease proves to be a first and fast, but essential step towards a therapy for mtDNA disorders.
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Eyvazzadeh N, Neshasteh-Riz A, Mahdavi SR. DNA damage of glioblastoma multiform cells induced by Beta radiation of iodine-131 in the presence or absence of topotecan: a picogreen and colonogenic assay. CELL JOURNAL 2015; 17:99-110. [PMID: 25870839 PMCID: PMC4393677 DOI: 10.22074/cellj.2015.516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Accepted: 02/08/2014] [Indexed: 11/20/2022]
Abstract
Objective Glioblastoma multiforme (GBM), one of the most common and aggressive
malignant brain tumors, is highly resistant to radiotherapy. Numerous approaches have
been pursued to find new radiosensitizers. We used a picogreen and colonogenic assay
to appraise the DNA damage and cell death in a spheroid culture of GBM cells caused by
iodine-131 (I-131) beta radiation in the presence of topotecan (TPT). Materials and Methods U87MG cells were cultured as spheroids with approximate
diameters of 300 μm. Cells were treated with beta radiation of I-131 (at a dose of 2 Gy)
and/ or TPT (1 μg/ml for 2 hours). The numbers of cells that survived were compared with
untreated cells using a colonogenic assay. In addition, we evaluated possible DNA damages by the picogreen method. The relation between DNA damage and cell death was
assessed in the experimental study of groups.
Results The findings showed that survival fraction (SF) in the I-131+TPT group
(39%) was considerably less than the I-131 group (58.92%; p<0.05). The number of
single strand breaks (SSB) and double strand breaks (DSB), in the DNA of U87MG
cells treated with beta radiation of I-131 and TPT (I-131+TPT) significantly increased
compared to cells treated with only I-131 or TPT (p<0.05). The amount of SSB repair was more than DSB repair (p<0.05). The relationship between cell death and
DNA damage was close (r≥0.6) and significant (p<0.05) in the irradiated and treated
groups. Also the maximum rate of DNA repair occurred 24 hours after the treatments.
A significant difference was not observed on other days of the restoration.
Conclusion The findings in the present study indicated that TPT can sensitize
U87MG cells to radiation and increase DNA damages. Potentially, TPT can cause
an increase in damage from DSB and SSB by its inhibitory effects on topoisomerase
enzyme and the cell cycle. The increased complex damages following the use of a
genotoxic agent and beta I-131 radiation, causes a significant increase the cell death
because of the difficult repair process. By assessing the relationship between DNA
damage and cell death, the picogreen method can be useful in predicting colonogenic
assay. Consequently, it is suggested that co-treatment with I-131 beta radiation and
TPT can improve GBM treatment.
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Affiliation(s)
- Nazila Eyvazzadeh
- Radiation Research Center, Faculty of Paramedicine, AJA University of Medical Sciences, Tehran, Iran
| | - Ali Neshasteh-Riz
- Department of Radiology, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Seyed Rabee Mahdavi
- Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
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Shen YJ, Le Bert N, Chitre AA, Koo CX, Nga XH, Ho SSW, Khatoo M, Tan NY, Ishii KJ, Gasser S. Genome-derived cytosolic DNA mediates type I interferon-dependent rejection of B cell lymphoma cells. Cell Rep 2015; 11:460-73. [PMID: 25865892 DOI: 10.1016/j.celrep.2015.03.041] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 02/13/2015] [Accepted: 03/17/2015] [Indexed: 12/21/2022] Open
Abstract
The DNA damage response (DDR) induces the expression of type I interferons (IFNs), but the underlying mechanisms are poorly understood. Here, we show the presence of cytosolic DNA in different mouse and human tumor cells. Treatment of cells with genotoxic agents increased the levels of cytosolic DNA in a DDR-dependent manner. Cloning of cytosolic DNA molecules from mouse lymphoma cells suggests that cytosolic DNA is derived from unique genomic loci and has the potential to form non-B DNA structures, including R-loops. Overexpression of Rnaseh1, which resolves R-loops, reduced the levels of cytosolic DNA, type I Ifn transcripts, and type I IFN-dependent rejection of lymphoma cells. Live-cell imaging showed a dynamic contact of cytosolic DNA with mitochondria, an important organelle for innate immune recognition of cytosolic nucleotides. In summary, we found that cytosolic DNA is present in many tumor cells and contributes to the immunogenicity of tumor cells.
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Affiliation(s)
- Yu J Shen
- Immunology Programme and Department of Microbiology, Centre for Life Sciences, National University of Singapore, Singapore 117456, Singapore; NUS Graduate School for Integrative Sciences & Engineering, National University of Singapore, Singapore 117456, Singapore
| | - Nina Le Bert
- Immunology Programme and Department of Microbiology, Centre for Life Sciences, National University of Singapore, Singapore 117456, Singapore
| | - Anuja A Chitre
- Immunology Programme and Department of Microbiology, Centre for Life Sciences, National University of Singapore, Singapore 117456, Singapore
| | - Christine Xing'Er Koo
- NUS Graduate School for Integrative Sciences & Engineering, National University of Singapore, Singapore 117456, Singapore; Laboratory of Adjuvant Innovation, National Institute of Biomedical Innovation (NIBIO), 7-6-8 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
| | - Xing H Nga
- Immunology Programme and Department of Microbiology, Centre for Life Sciences, National University of Singapore, Singapore 117456, Singapore
| | - Samantha S W Ho
- Immunology Programme and Department of Microbiology, Centre for Life Sciences, National University of Singapore, Singapore 117456, Singapore
| | - Muznah Khatoo
- Immunology Programme and Department of Microbiology, Centre for Life Sciences, National University of Singapore, Singapore 117456, Singapore
| | - Nikki Y Tan
- Immunology Programme and Department of Microbiology, Centre for Life Sciences, National University of Singapore, Singapore 117456, Singapore
| | - Ken J Ishii
- Laboratory of Adjuvant Innovation, National Institute of Biomedical Innovation (NIBIO), 7-6-8 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan; Laboratory of Vaccine Science, WPI Immunology Frontier Research Center (iFREC), Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Stephan Gasser
- Immunology Programme and Department of Microbiology, Centre for Life Sciences, National University of Singapore, Singapore 117456, Singapore; NUS Graduate School for Integrative Sciences & Engineering, National University of Singapore, Singapore 117456, Singapore.
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66
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Japaridze A, Benke A, Renevey S, Benadiba C, Dietler G. Influence of DNA Binding Dyes on Bare DNA Structure Studied with Atomic Force Microscopy. Macromolecules 2015. [DOI: 10.1021/ma502537g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Aleksandre Japaridze
- Laboratory of Physics of Living Matter and ‡Laboratory of Experimental Biophysics, EPFL, 1015 Lausanne, Switzerland
| | - Alexander Benke
- Laboratory of Physics of Living Matter and ‡Laboratory of Experimental Biophysics, EPFL, 1015 Lausanne, Switzerland
| | - Sylvain Renevey
- Laboratory of Physics of Living Matter and ‡Laboratory of Experimental Biophysics, EPFL, 1015 Lausanne, Switzerland
| | - Carine Benadiba
- Laboratory of Physics of Living Matter and ‡Laboratory of Experimental Biophysics, EPFL, 1015 Lausanne, Switzerland
| | - Giovanni Dietler
- Laboratory of Physics of Living Matter and ‡Laboratory of Experimental Biophysics, EPFL, 1015 Lausanne, Switzerland
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White MJ, McArthur K, Metcalf D, Lane RM, Cambier JC, Herold MJ, van Delft MF, Bedoui S, Lessene G, Ritchie ME, Huang DCS, Kile BT. Apoptotic caspases suppress mtDNA-induced STING-mediated type I IFN production. Cell 2015; 159:1549-62. [PMID: 25525874 DOI: 10.1016/j.cell.2014.11.036] [Citation(s) in RCA: 676] [Impact Index Per Article: 75.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 09/22/2014] [Accepted: 11/10/2014] [Indexed: 02/07/2023]
Abstract
Activated caspases are a hallmark of apoptosis induced by the intrinsic pathway, but they are dispensable for cell death and the apoptotic clearance of cells in vivo. This has led to the suggestion that caspases are activated not just to kill but to prevent dying cells from triggering a host immune response. Here, we show that the caspase cascade suppresses type I interferon (IFN) production by cells undergoing Bak/Bax-mediated apoptosis. Bak and Bax trigger the release of mitochondrial DNA. This is recognized by the cGAS/STING-dependent DNA sensing pathway, which initiates IFN production. Activated caspases attenuate this response. Pharmacological caspase inhibition or genetic deletion of caspase-9, Apaf-1, or caspase-3/7 causes dying cells to secrete IFN-β. In vivo, this precipitates an elevation in IFN-β levels and consequent hematopoietic stem cell dysfunction, which is corrected by loss of Bak and Bax. Thus, the apoptotic caspase cascade functions to render mitochondrial apoptosis immunologically silent.
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Affiliation(s)
- Michael J White
- ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia.
| | - Kate McArthur
- ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Donald Metcalf
- Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Rachael M Lane
- ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia
| | - John C Cambier
- Integrated Department of Immunology, University of Colorado Denver School of Medicine and National Jewish Health, Denver, CO 80206, USA
| | - Marco J Herold
- Molecular Genetics of Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Mark F van Delft
- Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Sammy Bedoui
- Department of Microbiology and Immunology, The University of Melbourne, Parkville 3010, Australia
| | - Guillaume Lessene
- ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia; Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville 3010, Australia
| | - Matthew E Ritchie
- Molecular Medicine Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia; Department of Mathematics and Statistics, The University of Melbourne, Parkville 3010, Australia
| | - David C S Huang
- Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Benjamin T Kile
- ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia.
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Identification of species-specific nuclear insertions of mitochondrial DNA (numts) in gorillas and their potential as population genetic markers. Mol Phylogenet Evol 2014; 81:61-70. [PMID: 25194325 DOI: 10.1016/j.ympev.2014.08.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 05/31/2014] [Accepted: 08/18/2014] [Indexed: 12/12/2022]
Abstract
The first hyper-variable region (HV1) of the mitochondrial control region (MCR) has been widely used as a molecular tool in population genetics, but inadvertent amplification of nuclear translocated copies of mitochondrial DNA (numts) in gorillas has compromised the use of mitochondrial DNA in population genetic studies. At least three putative classes (I, II, III) of gorilla-specific HV1 MCR numts have been uncovered over the past decade. However, the number, size and location of numt loci in gorillas and other apes are completely unknown. Furthermore, little work to date has assessed the utility of numts as candidate population genetic markers. In the present study, we screened Bacterial Artificial Chromosome (BAC) genomic libraries in the chimpanzee and gorilla to compare patterns of mitochondrial-wide insertion in both taxa. We conducted an intensive BLAST search for numts in the gorilla genome and compared the prevalence of numt loci originating from the MCR with other great ape taxa. Additional gorilla-specific MCR numts were retrieved either through BAC library screens or using an anchored-PCR (A-PCR) amplification using genomic DNA from five unrelated gorillas. Locus-specific primers were designed to identify numt insertional polymorphisms and evaluate their potential as population genetic markers. Mitochondrial-wide surveys of chimpanzee and gorilla BACs showed that the number of numts does not differ between these two taxa. However, MCR numts are more abundant in chimpanzees than in other great apes. We identified and mapped 67 putative gorilla-specific numts, including two that contain the entire HV1 domain, cluster with sequences from two numt classes (I, IIb) and will likely co-amplify with mitochondrial sequences using most published HV1 primers. However, phylogenetic analysis coupled with post-hoc analysis of mitochondrial variation can successfully differentiate nuclear sequences. Insertional polymorphisms were evident in three out of five numts examined, indicating their potential utility as molecular markers. Taken together, these findings demonstrate the potentially powerful insight that numts could make in uncovering population history in gorillas and other mammals.
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69
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Fukuoh A, Cannino G, Gerards M, Buckley S, Kazancioglu S, Scialo F, Lihavainen E, Ribeiro A, Dufour E, Jacobs HT. Screen for mitochondrial DNA copy number maintenance genes reveals essential role for ATP synthase. Mol Syst Biol 2014; 10:734. [PMID: 24952591 PMCID: PMC4265055 DOI: 10.15252/msb.20145117] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The machinery of mitochondrial DNA (mtDNA) maintenance is only partially characterized and is of wide interest due to its involvement in disease. To identify novel components of this machinery, plus other cellular pathways required for mtDNA viability, we implemented a genome-wide RNAi screen in Drosophila S2 cells, assaying for loss of fluorescence of mtDNA nucleoids stained with the DNA-intercalating agent PicoGreen. In addition to previously characterized components of the mtDNA replication and transcription machineries, positives included many proteins of the cytosolic proteasome and ribosome (but not the mitoribosome), three proteins involved in vesicle transport, some other factors involved in mitochondrial biogenesis or nuclear gene expression, > 30 mainly uncharacterized proteins and most subunits of ATP synthase (but no other OXPHOS complex). ATP synthase knockdown precipitated a burst of mitochondrial ROS production, followed by copy number depletion involving increased mitochondrial turnover, not dependent on the canonical autophagy machinery. Our findings will inform future studies of the apparatus and regulation of mtDNA maintenance, and the role of mitochondrial bioenergetics and signaling in modulating mtDNA copy number.
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Affiliation(s)
- Atsushi Fukuoh
- BioMediTech and Tampere University Hospital, University of Tampere, Tampere, Finland Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Graduate school of Medical Sciences, Fukuoka, Japan Department of Medical Laboratory Science, Junshin Gakuen University, Fukuoka, Japan
| | - Giuseppe Cannino
- BioMediTech and Tampere University Hospital, University of Tampere, Tampere, Finland
| | - Mike Gerards
- BioMediTech and Tampere University Hospital, University of Tampere, Tampere, Finland
| | - Suzanne Buckley
- BioMediTech and Tampere University Hospital, University of Tampere, Tampere, Finland
| | - Selena Kazancioglu
- BioMediTech and Tampere University Hospital, University of Tampere, Tampere, Finland
| | - Filippo Scialo
- BioMediTech and Tampere University Hospital, University of Tampere, Tampere, Finland
| | - Eero Lihavainen
- Department of Signal Processing, Tampere University of Technology, Tampere, Finland
| | - Andre Ribeiro
- Department of Signal Processing, Tampere University of Technology, Tampere, Finland
| | - Eric Dufour
- BioMediTech and Tampere University Hospital, University of Tampere, Tampere, Finland
| | - Howard T Jacobs
- BioMediTech and Tampere University Hospital, University of Tampere, Tampere, Finland Research Program of Molecular Neurology, University of Helsinki, Helsinki, Finland
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Cytoplasmic hybrid (cybrid) cell lines as a practical model for mitochondriopathies. Redox Biol 2014; 2:619-31. [PMID: 25460729 PMCID: PMC4297942 DOI: 10.1016/j.redox.2014.03.006] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 03/28/2014] [Indexed: 12/21/2022] Open
Abstract
Cytoplasmic hybrid (cybrid) cell lines can incorporate human subject mitochondria and perpetuate its mitochondrial DNA (mtDNA)-encoded components. Since the nuclear background of different cybrid lines can be kept constant, this technique allows investigators to study the influence of mtDNA on cell function. Prior use of cybrids has elucidated the contribution of mtDNA to a variety of biochemical parameters, including electron transport chain activities, bioenergetic fluxes, and free radical production. While the interpretation of data generated from cybrid cell lines has technical limitations, cybrids have contributed valuable insight into the relationship between mtDNA and phenotype alterations. This review discusses the creation of the cybrid technique and subsequent data obtained from cybrid applications. The cytoplasmic hybrid (cybrid) model can be used to determine mitochondrial DNA (mtDNA) contributions to phenotypic alterations. Cybrids are used to study mitochondriopathies such as Parkinson’s disease and Alzheimer’s disease. mtDNA heteroplasmy threshold and nuclear DNA-mtDNA compatibility can be determined using cybrid models.
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71
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Elimination of mitochondrial DNA is not required for herpes simplex virus 1 replication. J Virol 2013; 88:2967-76. [PMID: 24371054 DOI: 10.1128/jvi.03129-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED Infection with herpes simplex virus type 1 (HSV-1) results in the rapid elimination of mitochondrial DNA (mtDNA) from host cells. It is known that a mitochondrial isoform of the viral alkaline nuclease (UL12) called UL12.5 triggers this process. However, very little is known about the impact of mtDNA depletion on viral replication or the biology of HSV-1 infections. These questions have been difficult to address because UL12.5 and UL12 are encoded by overlapping transcripts that share the same open reading frame. As a result, mutations that alter UL12.5 also affect UL12, and UL12 null mutations severely impair viral growth by interfering with the intranuclear processing of progeny viral genomes. Therefore, to specifically assess the impact of mtDNA depletion on viral replication, it is necessary to eliminate the activity of UL12.5 while preserving the nuclear functions of UL12. Previous work has shown that the human cytomegalovirus alkaline nuclease UL98 can functionally substitute for UL12 during HSV-1 replication. We found that UL98 is unable to deplete mtDNA in transfected cells and therefore generated an HSV-1 variant in which UL98 coding sequences replace the UL12/UL12.5 open reading frame. The resulting virus was severely impaired in its ability to trigger mtDNA loss but reached titers comparable to those of wild-type HSV-1 in one-step and multistep growth experiments. Together, these observations demonstrate that the elimination of mtDNA is not required for HSV-1 replication in cell culture. IMPORTANCE Herpes simplex virus types 1 and 2 destroy the DNA of host cell mitochondria, the powerhouses of cells. Epstein-Barr virus, a distantly related herpesvirus, has a similar effect, indicating that mitochondrial DNA destruction is under positive selection and thus confers a benefit to the virus. The present work shows that mitochondrial DNA destruction is not required for efficient replication of herpes simplex virus type 1 in cultured Vero kidney epithelial cells, suggesting that this activity likely benefits the virus in other cell types or in the intact human host.
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72
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Tucker EJ, Wanschers BFJ, Szklarczyk R, Mountford HS, Wijeyeratne XW, van den Brand MAM, Leenders AM, Rodenburg RJ, Reljić B, Compton AG, Frazier AE, Bruno DL, Christodoulou J, Endo H, Ryan MT, Nijtmans LG, Huynen MA, Thorburn DR. Mutations in the UQCC1-interacting protein, UQCC2, cause human complex III deficiency associated with perturbed cytochrome b protein expression. PLoS Genet 2013; 9:e1004034. [PMID: 24385928 PMCID: PMC3873243 DOI: 10.1371/journal.pgen.1004034] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 10/29/2013] [Indexed: 12/01/2022] Open
Abstract
Mitochondrial oxidative phosphorylation (OXPHOS) is responsible for generating the majority of cellular ATP. Complex III (ubiquinol-cytochrome c oxidoreductase) is the third of five OXPHOS complexes. Complex III assembly relies on the coordinated expression of the mitochondrial and nuclear genomes, with 10 subunits encoded by nuclear DNA and one by mitochondrial DNA (mtDNA). Complex III deficiency is a debilitating and often fatal disorder that can arise from mutations in complex III subunit genes or one of three known complex III assembly factors. The molecular cause for complex III deficiency in about half of cases, however, is unknown and there are likely many complex III assembly factors yet to be identified. Here, we used Massively Parallel Sequencing to identify a homozygous splicing mutation in the gene encoding Ubiquinol-Cytochrome c Reductase Complex Assembly Factor 2 (UQCC2) in a consanguineous Lebanese patient displaying complex III deficiency, severe intrauterine growth retardation, neonatal lactic acidosis and renal tubular dysfunction. We prove causality of the mutation via lentiviral correction studies in patient fibroblasts. Sequence-profile based orthology prediction shows UQCC2 is an ortholog of the Saccharomyces cerevisiae complex III assembly factor, Cbp6p, although its sequence has diverged substantially. Co-purification studies show that UQCC2 interacts with UQCC1, the predicted ortholog of the Cbp6p binding partner, Cbp3p. Fibroblasts from the patient with UQCC2 mutations have deficiency of UQCC1, while UQCC1-depleted cells have reduced levels of UQCC2 and complex III. We show that UQCC1 binds the newly synthesized mtDNA-encoded cytochrome b subunit of complex III and that UQCC2 patient fibroblasts have specific defects in the synthesis or stability of cytochrome b. This work reveals a new cause for complex III deficiency that can assist future patient diagnosis, and provides insight into human complex III assembly by establishing that UQCC1 and UQCC2 are complex III assembly factors participating in cytochrome b biogenesis. Mitochondrial complex III deficiency is a devastating disorder that impairs energy generation, and leads to variable symptoms such as developmental regression, seizures, kidney dysfunction and frequently death. The genetic basis of complex III deficiency is not fully understood, with around half of cases having no known cause. This lack of genetic diagnosis is partly due to an incomplete understanding of the genes required for complex III assembly and function. We have identified two key proteins required for complex III, UQCC1 and UQCC2, and have elucidated the role of these inter-dependent proteins in the biogenesis of cytochrome b, the only complex III subunit that is encoded by mitochondrial DNA. We have shown that mutations in UQCC2 cause human complex III deficiency in a patient with neonatal lactic acidosis and renal tubulopathy. This work contributes to an improved understanding of complex III biogenesis, and will aid future molecular diagnoses of complex III deficiency.
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Affiliation(s)
- Elena J. Tucker
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Bas F. J. Wanschers
- Centre for Molecular and Biomolecular Informatics, Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
- Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Radek Szklarczyk
- Centre for Molecular and Biomolecular Informatics, Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Hayley S. Mountford
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Xiaonan W. Wijeyeratne
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Mariël A. M. van den Brand
- Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Anne M. Leenders
- Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Richard J. Rodenburg
- Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Boris Reljić
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Alison G. Compton
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Ann E. Frazier
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Damien L. Bruno
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - John Christodoulou
- Genetic Metabolic Disorders Research Unit, Children's Hospital at Westmead, Westmead, New South Wales, Australia
- Disciplines of Paediatrics & Child Health and Genetic Medicine, University of Sydney, Sydney, New South Wales, Australia
| | - Hitoshi Endo
- Department of Biochemistry, Jichi Medical University, Tochigi, Japan
| | - Michael T. Ryan
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
- ARC Centre of Excellence for Coherent X-ray Science, La Trobe University, Melbourne, Australia
| | - Leo G. Nijtmans
- Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Martijn A. Huynen
- Centre for Molecular and Biomolecular Informatics, Nijmegen Centre for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
- * E-mail: (MAH); (DRT)
| | - David R. Thorburn
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Victoria, Australia
- * E-mail: (MAH); (DRT)
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73
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Tibrewal S, Sarkar J, Jassim SH, Gandhi S, Sonawane S, Chaudhary S, Byun YS, Ivanir Y, Hallak J, Horner JH, Newcomb M, Jain S. Tear fluid extracellular DNA: diagnostic and therapeutic implications in dry eye disease. Invest Ophthalmol Vis Sci 2013; 54:8051-61. [PMID: 24255046 DOI: 10.1167/iovs.13-12844] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
PURPOSE To determine the abundance of extracellular DNA (eDNA) in tear fluid of patients with dry eye disease (DED) and to report clinical outcomes after DNase I eyedrops use to reduce excessive tear fluid eDNA. METHODS Tear fluid was collected from healthy control subjects and patients with DED. The eDNA abundance was determined with the PicoGreen dye assay. The DED symptoms and clinical signs were recorded and correlated with eDNA abundance. Two patients with DED having excessive eDNA in tear fluid were treated with DNase I eyedrops. RESULTS The PicoGreen dye assay measures tear fluid eDNA abundance after a 2-minute incubation time. With longer incubations, admixed cells also contribute to eDNA measurements. The mean (SE) eDNA abundance in healthy control subjects' tear fluid was 1.4 (0.2) μg/mL. The mean (SE) eDNA abundance in tear fluid of patients with nonautoimmune DED, autoimmune DED, and graft versus host disease was significantly higher: the values were 2.9 (0.6), 5.2 (1.2), and 9.1 (2.3) μg/mL, respectively (P < 0.05). In most of these patients, the PicoGreen dye kinetic assay of tear fluid showed an increase in fluorescence signal due to the presence of viable cells in tear fluid. Tear fluid eDNA had the best correlation with corneal Rose Bengal staining (r = 0.55). Treatment of patients having DED with DNase I eyedrops reduced eDNA abundance, abrogated signal increase, and improved comfort. CONCLUSIONS Excessive eDNA is present in tear fluid of patients with dry eyes. A novel therapeutic approach for managing DED may be to measure eDNA abundance in tear fluid with the PicoGreen dye assay and reduce excessive amounts with DNase I eyedrops.
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Affiliation(s)
- Sapna Tibrewal
- Corneal Neurobiology Laboratory, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, Chicago, Illinois
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74
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Heid ME, Keyel PA, Kamga C, Shiva S, Watkins SC, Salter RD. Mitochondrial reactive oxygen species induces NLRP3-dependent lysosomal damage and inflammasome activation. THE JOURNAL OF IMMUNOLOGY 2013; 191:5230-8. [PMID: 24089192 DOI: 10.4049/jimmunol.1301490] [Citation(s) in RCA: 399] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome drives many inflammatory processes and mediates IL-1 family cytokine release. Inflammasome activators typically damage cells and may release lysosomal and mitochondrial products into the cytosol. Macrophages triggered by the NLRP3 inflammasome activator nigericin show reduced mitochondrial function and decreased cellular ATP. Release of mitochondrial reactive oxygen species (ROS) leads to subsequent lysosomal membrane permeabilization (LMP). NLRP3-deficient macrophages show comparable reduced mitochondrial function and ATP loss, but maintain lysosomal acidity, demonstrating that LMP is NLRP3 dependent. A subset of wild-type macrophages undergo subsequent mitochondrial membrane permeabilization and die. Both LMP and mitochondrial membrane permeabilization are inhibited by potassium, scavenging mitochondrial ROS, or NLRP3 deficiency, but are unaffected by cathepsin B or caspase-1 inhibitors. In contrast, IL-1β secretion is ablated by potassium, scavenging mitochondrial ROS, and both cathepsin B and caspase-1 inhibition. These results demonstrate interplay between lysosomes and mitochondria that sustain NLRP3 activation and distinguish cell death from IL-1β release.
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Affiliation(s)
- Michelle E Heid
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261
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75
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Kasashima K, Nagao Y, Endo H. Dynamic regulation of mitochondrial genome maintenance in germ cells. Reprod Med Biol 2013; 13:11-20. [PMID: 24482608 PMCID: PMC3890057 DOI: 10.1007/s12522-013-0162-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 07/04/2013] [Indexed: 12/11/2022] Open
Abstract
Mitochondria play a crucial role in the development and function of germ cells. Mitochondria contain a maternally inherited genome that should be transmitted to offspring without reactive oxygen species‐induced damage during germ line development. Germ cells are also involved in the mitochondrial DNA (mtDNA) bottleneck; thus, the appropriate regulation of mtDNA in these cells is very important for this characteristic transmission. In this review, we focused on unique regulation of the mitochondrial genome in animal germ cells; paternal elimination and the mtDNA bottleneck in females. We also summarized the mitochondrial nucleoid factors involved in various mtDNA regulation pathways. Among them, mitochondrial transcription factor A (TFAM), which has pleiotropic and essential roles in mtDNA maintenance, appears to have putative roles in germ cell regulation.
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Affiliation(s)
- Katsumi Kasashima
- Department of Biochemistry, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498 Japan
| | - Yasumitsu Nagao
- Center for Experimental Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498 Japan
| | - Hitoshi Endo
- Department of Biochemistry, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498 Japan
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76
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Clinical, biochemical, cellular and molecular characterization of mitochondrial DNA depletion syndrome due to novel mutations in the MPV17 gene. Eur J Hum Genet 2013; 22:184-91. [PMID: 23714749 PMCID: PMC3895632 DOI: 10.1038/ejhg.2013.112] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 04/15/2013] [Accepted: 04/17/2013] [Indexed: 11/29/2022] Open
Abstract
Mitochondrial DNA (mtDNA) depletion syndromes (MDS) are severe autosomal recessive disorders associated with decreased mtDNA copy number in clinically affected tissues. The hepatocerebral form (mtDNA depletion in liver and brain) has been associated with mutations in the POLG, PEO1 (Twinkle), DGUOK and MPV17 genes, the latter encoding a mitochondrial inner membrane protein of unknown function. The aims of this study were to clarify further the clinical, biochemical, cellular and molecular genetic features associated with MDS due to MPV17 gene mutations. We identified 12 pathogenic mutations in the MPV17 gene, of which 11 are novel, in 17 patients from 12 families. All patients manifested liver disease. Poor feeding, hypoglycaemia, raised serum lactate, hypotonia and faltering growth were common presenting features. mtDNA depletion in liver was demonstrated in all seven cases where liver tissue was available. Mosaic mtDNA depletion was found in primary fibroblasts by PicoGreen staining. These results confirm that MPV17 mutations are an important cause of hepatocerebral mtDNA depletion syndrome, and provide the first demonstration of mosaic mtDNA depletion in human MPV17 mutant fibroblast cultures. We found that a severe clinical phenotype was associated with profound tissue-specific mtDNA depletion in liver, and, in some cases, mosaic mtDNA depletion in fibroblasts.
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77
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Cronin-Furman EN, Borland MK, Bergquist KE, Bennett JP, Trimmer PA. Mitochondrial quality, dynamics and functional capacity in Parkinson's disease cybrid cell lines selected for Lewy body expression. Mol Neurodegener 2013; 8:6. [PMID: 23351342 PMCID: PMC3577453 DOI: 10.1186/1750-1326-8-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 01/21/2013] [Indexed: 12/13/2022] Open
Abstract
Background Lewy bodies (LB) are a neuropathological hallmark of Parkinson’s disease (PD) and other synucleinopathies. The role their formation plays in disease pathogenesis is not well understood, in part because studies of LB have been limited to examination of post-mortem tissue. LB formation may be detrimental to neuronal survival or merely an adaptive response to other ongoing pathological processes. In a human cytoplasmic hybrid (cybrid) neural cell model that expresses mitochondrial DNA from PD patients, we observed spontaneous formation of intracellular protein aggregates (“cybrid LB” or CLB) that replicate morphological and biochemical properties of native, cortical LB. We studied mitochondrial morphology, bioenergetics and biogenesis signaling by creating stable sub-clones of three PD cybrid cell lines derived from cells expressing CLB. Results Cloning based on CLB expression had a differential effect on mitochondrial morphology, movement and oxygen utilization in each of three sub-cloned lines, but no long-term change in CLB expression. In one line (PD63CLB), mitochondrial function declined compared to the original PD cybrid line (PD63Orig) due to low levels of mtDNA in nucleoids. In another cell line (PD61Orig), the reverse was true, and cellular and mitochondrial function improved after sub-cloning for CLB expression (PD61CLB). In the third cell line (PD67Orig), there was no change in function after selection for CLB expression (PD67CLB). Conclusions Expression of mitochondrial DNA derived from PD patients in cybrid cell lines induced the spontaneous formation of CLB. The creation of three sub-cloned cybrid lines from cells expressing CLB resulted in differential phenotypic changes in mitochondrial and cellular function. These changes were driven by the expression of patient derived mitochondrial DNA in nucleoids, rather than by the presence of CLB. Our studies suggest that mitochondrial DNA plays an important role in cellular and mitochondrial dysfunction in PD. Additional studies will be needed to assess the direct effect of CLB expression on cellular and mitochondrial function.
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Affiliation(s)
- Emily N Cronin-Furman
- Parkinson's and Movement Disorders Center, Virginia Commonwealth University, Richmond, VA 23298, USA
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78
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Oxidant stress in mitochondrial DNA damage, autophagy and inflammation in atherosclerosis. Sci Rep 2013; 3:1077. [PMID: 23326634 PMCID: PMC3546319 DOI: 10.1038/srep01077] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 11/29/2012] [Indexed: 12/27/2022] Open
Abstract
Our studies in HUVECs show that ox-LDL induced autophagy and damaged mtDNA leading to TLR9 expression. LOX-1 antibody or the ROS inhibitor apocynin attenuated ox-LDL-mediated autophagy, mtDNA damage and TLR9 expression, suggesting that these events are LOX-1 and ROS-dependent phenomena. Experiments using siRNA to DNase II indicated that DNase II digests mtDNA to protect the tissue from inflammation. Next, we studied and found intense autophagy, TLR9 expression and inflammatory signals (CD45 and CD68) in the aortas of LDLR knockout mice fed high cholesterol diet. Deletion of LOX-1 (LDLR/LOX-1 double knockout mice) attenuated autophagy, TLR9 expression as well as CD45 and CD68. Damaged mtDNA signal was also very high in LDLR knockout mice aortas, and this signal was attenuated by LOX-1 deletion. Thus, it appears that oxidative stress-mediated damaged mtDNA that escapes autophagy induces a potent inflammatory response in atherosclerosis.
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79
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Ding S, Riddoch-Contreras J, Contrevas JR, Abramov AY, Qi Z, Duchen MR. Mild stress of caffeine increased mtDNA content in skeletal muscle cells: the interplay between Ca2+ transients and nitric oxide. J Muscle Res Cell Motil 2012; 33:327-37. [PMID: 22926241 DOI: 10.1007/s10974-012-9318-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2012] [Accepted: 08/10/2012] [Indexed: 10/28/2022]
Abstract
Caffeine increases mitochondrial biogenesis in myotubes by evoking Ca(2+) transients. Nitric oxide (NO) also induces mitochondrial biogenesis in skeletal muscle cells via upregulation of AMP-activated protein kinase (AMPK) activity and PGC-1α. However, the interplay and timing sequence between Ca(2+) transients and NO releases remain unclear. Herein, we tested the hypothesis that caffeine-evoked Ca(2+) transients triggered NO production to increase mtDNA in skeletal muscle cells. Ca(2+) transients were recorded with Fura-2 AM and confocal microscopy; mtDNA staining, mitochondrial membrane potential and NO level were determined using fluorescent probes PicoGreen, tetramethylrhodamine methyl ester (TMRM) and DAF-FM, respectively. In primary cultured myotubes, a subtle and moderate stress of caffeine increased mtDNA exclusively. Mitochondrial membrane potential and mtDNA were increased by 1 mM as well as 5 mM caffeine, whereas 10 mM caffeine did not change the fluorescence intensity of PicoGreen and TMRM. NO level in myocytes increased gradually following the first jump of Ca(2+) transients evoked by caffeine (5 mM) till the end of recording, when Fura-2 indicated that Ca(2+) transients recovered partly and even disappeared. Importantly, nitric oxide synthase (NOS) inhibitor (L-NAME) suppressed caffeine-induced mtDNA biogenesis, whereas NO donor (DETA-NO) increased mtDNA content. These data strongly suggest that caffeine-induced mtDNA biogenesis is dose-sensitive and dependent on a certain level of stress. Further, an increasing level of NO following Ca(2+) transients is required for caffeine-induced mtDNA biogenesis. Additionally, Ca(2+) transients, a usual and first response to caffeine, was either suppressed or attenuated by L-NAME, DETA-NO, AICAR and U0126, suggesting an inability to control [Ca(2+)](i) in these treated cells. There may be an important interplay between NO and Ca(2+) transients in intracellular signaling system involving NOS, AMPK and MEK.
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Affiliation(s)
- Shuzhe Ding
- The Key Laboratory of Adolescent Health Assessment and Exercise Intervention, Ministry of Education of China, East China Normal University, Shanghai 200241, China.
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80
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Maintenance of mitochondrial genome distribution by mitochondrial AAA+ protein ClpX. Exp Cell Res 2012; 318:2335-43. [PMID: 22841477 DOI: 10.1016/j.yexcr.2012.07.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 06/22/2012] [Accepted: 07/10/2012] [Indexed: 11/20/2022]
Abstract
The segregation of mitochondrial DNA (mtDNA) is important for the maintenance and transmission of the genome between generations. Recently, we clarified that human mitochondrial transcription factor A (TFAM) is required for equal distribution and symmetric segregation of mtDNA in cultured cells; however, the molecular mechanism involved is largely unknown. ClpX is an ATPase associated with various cellular activities (AAA+) proteins that localize to the mitochondrial matrix and is suggested to associate with mtDNA. In this study, we found that RNAi-mediated knockdown of ClpX in HeLa cells resulted in enlarged mtDNA nucleoids, which is very similar to that observed in TFAM-knockdown cells in several properties. The expression of TFAM protein was not significantly reduced in ClpX-knockdown cells. However, the enlarged mtDNA nucleoids caused by ClpX-knockdown were suppressed by overexpression of recombinant TFAM and the phenotype was not observed in knockdown with ClpP, a protease subunit of ClpXP. Endogenous ClpX and TFAM exist in close vicinity, and ClpX enhanced DNA-binding activity of TFAM in vitro. These results suggest that human ClpX, a novel mtDNA regulator, maintains mtDNA nucleoid distribution through TFAM function as a chaperone rather than as a protease and its involvement in mtDNA segregation.
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81
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Oka T, Hikoso S, Yamaguchi O, Taneike M, Takeda T, Tamai T, Oyabu J, Murakawa T, Nakayama H, Nishida K, Akira S, Yamamoto A, Komuro I, Otsu K. Mitochondrial DNA that escapes from autophagy causes inflammation and heart failure. Nature 2012; 485:251-5. [PMID: 22535248 PMCID: PMC3378041 DOI: 10.1038/nature10992] [Citation(s) in RCA: 862] [Impact Index Per Article: 71.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Accepted: 03/01/2012] [Indexed: 12/24/2022]
Abstract
Heart failure is a leading cause of morbidity and mortality in industrialized countries. Although infection with microorganisms is not involved in the development of heart failure in most cases, inflammation has been implicated in the pathogenesis of heart failure1. However, the mechanisms responsible for initiating and integrating inflammatory responses within the heart remain poorly defined. Mitochondria are evolutionary endosymbionts derived from bacteria and contain DNA similar to bacterial DNA2,3,4. Mitochondria damaged by external hemodynamic stress are degraded by the autophagy/lysosome system in cardiomyocytes5. Here, we show that mitochondrial DNA that escapes from autophagy cell-autonomously leads to Toll-like receptor (TLR) 9-mediated inflammatory responses in cardiomyocytes and is capable of inducing myocarditis, and dilated cardiomyopathy. Cardiac-specific deletion of lysosomal deoxyribonuclease (DNase) II showed no cardiac phenotypes under baseline conditions, but increased mortality and caused severe myocarditis and dilated cardiomyopathy 10 days after treatment with pressure overload. Early in the pathogenesis, DNase II-deficient hearts exhibited infiltration of inflammatory cells and increased mRNA expression of inflammatory cytokines, with accumulation of mitochondrial DNA deposits in autolysosomes in the myocardium. Administration of the inhibitory oligodeoxynucleotides against TLR9, which is known to be activated by bacterial DNA6, or ablation of Tlr9 attenuated the development of cardiomyopathy in DNase II-deficient mice. Furthermore, Tlr9-ablation improved pressure overload-induced cardiac dysfunction and inflammation even in mice with wild-type Dnase2a alleles. These data provide new perspectives on the mechanism of genesis of chronic inflammation in failing hearts.
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Affiliation(s)
- Takafumi Oka
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
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82
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DeLuca SZ, O'Farrell PH. Barriers to male transmission of mitochondrial DNA in sperm development. Dev Cell 2012; 22:660-8. [PMID: 22421049 DOI: 10.1016/j.devcel.2011.12.021] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 11/09/2011] [Accepted: 12/25/2011] [Indexed: 11/19/2022]
Abstract
Across the eukaryotic phylogeny, offspring usually inherit their mitochondrial genome from only one of two parents: in animals, the female. Although mechanisms that eliminate paternally derived mitochondria from the zygote have been sought, the developmental stage at which paternal transmission of mitochondrial DNA is restricted is unknown in most animals. Here, we show that the mitochondria of mature Drosophila sperm lack DNA, and we uncover two processes that eliminate mitochondrial DNA during spermatogenesis. Visualization of mitochondrial DNA nucleoids revealed their abrupt disappearance from developing spermatids in a process requiring the mitochondrial nuclease, Endonuclease G. In Endonuclease G mutants, persisting nucleoids are swept out of spermatids by a cellular remodeling process that trims and shapes spermatid tails. Our results show that mitochondrial DNA is eliminated during spermatogenesis, thereby removing the capacity of sperm to transmit the mitochondrial genome to the next generation.
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Affiliation(s)
- Steven Z DeLuca
- Department of Biochemistry, UCSF, San Francisco, CA 94110, USA
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83
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Xu SC, He MD, Lu YH, Li L, Zhong M, Zhang YW, Wang Y, Yu ZP, Zhou Z. Nickel exposure induces oxidative damage to mitochondrial DNA in Neuro2a cells: the neuroprotective roles of melatonin. J Pineal Res 2011; 51:426-33. [PMID: 21797922 DOI: 10.1111/j.1600-079x.2011.00906.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Recent studies suggest that oxidative stress and mitochondrial dysfunction play important roles in the neurotoxicity of nickel. Because mitochondrial DNA (mtDNA) is highly vulnerable to oxidative stress and melatonin can efficiently protect mtDNA against oxidative damage in various pathological conditions, the aims of this study were to determine whether mtDNA oxidative damage was involved in the neurotoxicity of nickel and to assay the neuroprotective effects of melatonin in mtDNA. In this study, we exposed mouse neuroblastoma cell lines (Neuro2a) to different concentrations of nickel chloride (NiCl(2), 0.125, 0.25, and 0.5 mm) for 24 hr. We found that nickel significantly increased reactive oxygen species (ROS) production and mitochondrial superoxide levels. In addition, nickel exposure increased mitochondrial 8-hydroxyguanine (8-OHdG) content and reduced mtDNA content and mtDNA transcript levels. Consistent with this finding, nickel was found to destroy mtDNA nucleoid structure and decrease protein levels of Tfam, a key protein component for nucleoid organization. However, all the oxidative damage to mtDNA induced by nickel was efficiently attenuated by melatonin pretreatment. Our results suggest that oxidative damage to mtDNA may account for the neurotoxicity of nickel. Melatonin has great pharmacological potential in protecting mtDNA against the adverse effects of nickel in the nervous system.
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Affiliation(s)
- Shang-Cheng Xu
- Department of Occupational Health, Third Military Medical University, Chongqing, China
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84
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Superresolution fluorescence imaging of mitochondrial nucleoids reveals their spatial range, limits, and membrane interaction. Mol Cell Biol 2011; 31:4994-5010. [PMID: 22006021 DOI: 10.1128/mcb.05694-11] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A fundamental objective in molecular biology is to understand how DNA is organized in concert with various proteins, RNA, and biological membranes. Mitochondria maintain and express their own DNA (mtDNA), which is arranged within structures called nucleoids. Their functions, dimensions, composition, and precise locations relative to other mitochondrial structures are poorly defined. Superresolution fluorescence microscopy techniques that exceed the previous limits of imaging within the small and highly compartmentalized mitochondria have been recently developed. We have improved and employed both two- and three-dimensional applications of photoactivated localization microscopy (PALM and iPALM, respectively) to visualize the core dimensions and relative locations of mitochondrial nucleoids at an unprecedented resolution. PALM reveals that nucleoids differ greatly in size and shape. Three-dimensional volumetric analysis indicates that, on average, the mtDNA within ellipsoidal nucleoids is extraordinarily condensed. Two-color PALM shows that the freely diffusible mitochondrial matrix protein is largely excluded from the nucleoid. In contrast, nucleoids are closely associated with the inner membrane and often appear to be wrapped around cristae or crista-like inner membrane invaginations. Determinations revealing high packing density, separation from the matrix, and tight association with the inner membrane underscore the role of mechanisms that regulate access to mtDNA and that remain largely unknown.
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85
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Jeon J, Jeong JH, Baek JH, Koo HJ, Park WH, Yang JS, Yu MH, Kim S, Pak YK. Network clustering revealed the systemic alterations of mitochondrial protein expression. PLoS Comput Biol 2011; 7:e1002093. [PMID: 21738461 PMCID: PMC3127811 DOI: 10.1371/journal.pcbi.1002093] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 05/03/2011] [Indexed: 01/03/2023] Open
Abstract
The mitochondrial protein repertoire varies depending on the cellular state. Protein component modifications caused by mitochondrial DNA (mtDNA) depletion are related to a wide range of human diseases; however, little is known about how nuclear-encoded mitochondrial proteins (mt proteome) changes under such dysfunctional states. In this study, we investigated the systemic alterations of mtDNA-depleted (ρ0) mitochondria by using network analysis of gene expression data. By modularizing the quantified proteomics data into protein functional networks, systemic properties of mitochondrial dysfunction were analyzed. We discovered that up-regulated and down-regulated proteins were organized into two predominant subnetworks that exhibited distinct biological processes. The down-regulated network modules are involved in typical mitochondrial functions, while up-regulated proteins are responsible for mtDNA repair and regulation of mt protein expression and transport. Furthermore, comparisons of proteome and transcriptome data revealed that ρ0 cells attempted to compensate for mtDNA depletion by modulating the coordinated expression/transport of mt proteins. Our results demonstrate that mt protein composition changed to remodel the functional organization of mitochondrial protein networks in response to dysfunctional cellular states. Human mt protein functional networks provide a framework for understanding how cells respond to mitochondrial dysfunctions. Mitochondria are dynamic organelles that are essential for energy production and cellular processes in eukaryotic cells, and their functional failure is a major cause of age-associated degenerative diseases. To meet the specific needs of different cellular states, mitochondrial protein repertoires are adjusted. It is critical to characterize the systemic alterations of mitochondria to different cellular states to understand the dynamic organization of mitochondrial systems. In this study, we modularized the quantified proteomics data into protein functional networks to characterize gene expression changes under dysfunctional mitochondrial conditions. Our results demonstrate that mitochondrial protein repertoires changed to compensate for dysfunctional cellular states by reorganizing mitochondrial protein functional network. Through network clustering analysis, we discovered that cells respond to pathological conditions by modulating the coordinated expression/transport of mitochondrial proteins. Network analysis of mt proteins can advance our understanding of dysfunctional mitochondrial systems and elucidate the candidate mt proteins involved in human mitochondrial diseases.
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Affiliation(s)
- Jouhyun Jeon
- Division of Molecular and Life Science, School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Korea
| | - Jae Hoon Jeong
- Department of Life and Nanopharmaceutical Sciences, Kyung Hee University, Seoul, Korea
| | - Je-Hyun Baek
- Functional Proteomics Center, Korea Institute of Science and Technology, Seoul, Korea
| | - Hyun-Jung Koo
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Wook-Ha Park
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Jae-Seong Yang
- Division of Molecular and Life Science, School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Korea
| | - Myeong-Hee Yu
- Functional Proteomics Center, Korea Institute of Science and Technology, Seoul, Korea
| | - Sanguk Kim
- Division of Molecular and Life Science, School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, Korea
- Division of ITCE engineering, Pohang University of Science and Technology, Pohang, Korea
- * E-mail: (SK); (YKP)
| | - Youngmi Kim Pak
- Department of Life and Nanopharmaceutical Sciences, Kyung Hee University, Seoul, Korea
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea
- * E-mail: (SK); (YKP)
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86
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Reyes A, He J, Mao CC, Bailey LJ, Di Re M, Sembongi H, Kazak L, Dzionek K, Holmes JB, Cluett TJ, Harbour ME, Fearnley IM, Crouch RJ, Conti MA, Adelstein RS, Walker JE, Holt IJ. Actin and myosin contribute to mammalian mitochondrial DNA maintenance. Nucleic Acids Res 2011; 39:5098-108. [PMID: 21398640 PMCID: PMC3130256 DOI: 10.1093/nar/gkr052] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial DNA maintenance and segregation are dependent on the actin cytoskeleton in budding yeast. We found two cytoskeletal proteins among six proteins tightly associated with rat liver mitochondrial DNA: non-muscle myosin heavy chain IIA and β-actin. In human cells, transient gene silencing of MYH9 (encoding non-muscle myosin heavy chain IIA), or the closely related MYH10 gene (encoding non-muscle myosin heavy chain IIB), altered the topology and increased the copy number of mitochondrial DNA; and the latter effect was enhanced when both genes were targeted simultaneously. In contrast, genetic ablation of non-muscle myosin IIB was associated with a 60% decrease in mitochondrial DNA copy number in mouse embryonic fibroblasts, compared to control cells. Gene silencing of β-actin also affected mitochondrial DNA copy number and organization. Protease-protection experiments and iodixanol gradient analysis suggest some β-actin and non-muscle myosin heavy chain IIA reside within human mitochondria and confirm that they are associated with mitochondrial DNA. Collectively, these results strongly implicate the actomyosin cytoskeleton in mammalian mitochondrial DNA maintenance.
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Affiliation(s)
- A Reyes
- MRC Mitochondrial Biology Unit, Cambridge, UK
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87
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Kasashima K, Sumitani M, Endo H. Human mitochondrial transcription factor A is required for the segregation of mitochondrial DNA in cultured cells. Exp Cell Res 2011; 317:210-20. [DOI: 10.1016/j.yexcr.2010.10.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 10/08/2010] [Accepted: 10/09/2010] [Indexed: 10/18/2022]
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88
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Kim I, Lemasters JJ. Mitochondrial degradation by autophagy (mitophagy) in GFP-LC3 transgenic hepatocytes during nutrient deprivation. Am J Physiol Cell Physiol 2010; 300:C308-17. [PMID: 21106691 DOI: 10.1152/ajpcell.00056.2010] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fasting in vivo and nutrient deprivation in vitro enhance sequestration of mitochondria and other organelles by autophagy for recycling of essential nutrients. Here our goal was to use a transgenic mouse strain expressing green fluorescent protein (GFP) fused to rat microtubule-associated protein-1 light chain 3 (LC3), a marker protein for autophagy, to characterize the dynamics of mitochondrial turnover by autophagy (mitophagy) in hepatocytes during nutrient deprivation. In complete growth medium, GFP-LC3 fluorescence was distributed diffusely in the cytosol and incorporated in mostly small (0.2-0.3 μm) patches in proximity to mitochondria, which likely represent preautophagic structures (PAS). After nutrient deprivation plus 1 μM glucagon to simulate fasting, PAS grew into green cups (phagophores) and then rings (autophagosomes) that enveloped individual mitochondria, a process that was blocked by 3-methyladenine. Autophagic sequestration of mitochondria took place in 6.5 ± 0.4 min and often occurred coordinately with mitochondrial fission. After ring formation and apparent sequestration, mitochondria depolarized in 11.8 ± 1.4 min, as indicated by loss of tetramethylrhodamine methylester fluorescence. After ring formation, LysoTracker Red uptake, a marker of acidification, occurred gradually, becoming fully evident at 9.9 ± 1.9 min of ring formation. After acidification, GFP-LC3 fluorescence dispersed. PicoGreen labeling of mitochondrial DNA (mtDNA) showed that mtDNA was also sequestered and degraded in autophagosomes. Overall, the results indicate that PAS serve as nucleation sites for mitophagy in hepatocytes during nutrient deprivation. After autophagosome formation, mitochondrial depolarization and vesicular acidification occur, and mitochondrial contents, including mtDNA, are degraded.
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Affiliation(s)
- Insil Kim
- Center for Cell Death, Injury & Regeneration, Medical University of South Carolina, QF308 Quadrangle Bldg., 280 Calhoun St., P. O Box 250140, Charleston, SC 29425, USA
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89
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Elachouri G, Vidoni S, Zanna C, Pattyn A, Boukhaddaoui H, Gaget K, Yu-Wai-Man P, Gasparre G, Sarzi E, Delettre C, Olichon A, Loiseau D, Reynier P, Chinnery PF, Rotig A, Carelli V, Hamel CP, Rugolo M, Lenaers G. OPA1 links human mitochondrial genome maintenance to mtDNA replication and distribution. Genome Res 2010; 21:12-20. [PMID: 20974897 DOI: 10.1101/gr.108696.110] [Citation(s) in RCA: 172] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Eukaryotic cells harbor a small multiploid mitochondrial genome, organized in nucleoids spread within the mitochondrial network. Maintenance and distribution of mitochondrial DNA (mtDNA) are essential for energy metabolism, mitochondrial lineage in primordial germ cells, and to prevent mtDNA instability, which leads to many debilitating human diseases. Mounting evidence suggests that the actors of the mitochondrial network dynamics, among which is the intramitochondrial dynamin OPA1, might be involved in these processes. Here, using siRNAs specific to OPA1 alternate spliced exons, we evidenced that silencing of the OPA1 variants including exon 4b leads to mtDNA depletion, secondary to inhibition of mtDNA replication, and to marked alteration of mtDNA distribution in nucleoid and nucleoid distribution throughout the mitochondrial network. We demonstrate that a small hydrophobic 10-kDa peptide generated by cleavage of the OPA1-exon4b isoform is responsible for this process and show that this peptide is embedded in the inner membrane and colocalizes and coimmunoprecipitates with nucleoid components. We propose a novel synthetic model in which a peptide, including two trans-membrane domains derived from the N terminus of the OPA1-exon4b isoform in vertebrates or from its ortholog in lower eukaryotes, might contribute to nucleoid attachment to the inner mitochondrial membrane and promotes mtDNA replication and distribution. Thus, this study places OPA1 as a direct actor in the maintenance of mitochondrial genome integrity.
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Affiliation(s)
- Ghizlane Elachouri
- INSERM U-583, Institut des Neurosciences de Montpellier, Montpellier, France
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90
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Ruhanen H, Borrie S, Szabadkai G, Tyynismaa H, Jones AW, Kang D, Taanman JW, Yasukawa T. Mitochondrial single-stranded DNA binding protein is required for maintenance of mitochondrial DNA and 7S DNA but is not required for mitochondrial nucleoid organisation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:931-9. [DOI: 10.1016/j.bbamcr.2010.04.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 03/31/2010] [Accepted: 04/20/2010] [Indexed: 01/19/2023]
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91
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Mitra K, Lippincott-Schwartz J. Analysis of mitochondrial dynamics and functions using imaging approaches. ACTA ACUST UNITED AC 2010; Chapter 4:Unit 4.25.1-21. [PMID: 20235105 DOI: 10.1002/0471143030.cb0425s46] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Mitochondria are organelles that have been primarily known as the powerhouse of the cell. However, recent advances in the field have revealed that mitochondria are also involved in many other cellular activities like lipid modifications, redox balance, calcium balance, and even controlled cell death. These multifunctional organelles are motile and highly dynamic in shapes and forms; the dynamism is brought about by the mitochondria's ability to undergo fission and fusion with each other. Therefore, it is very important to be able to image mitochondrial shape changes to relate to the variety of cellular functions these organelles have to accomplish. The protocols described here will enable researchers to perform steady-state and time-lapse imaging of mitochondria in live cells by using confocal microscopy. High-resolution three-dimensional imaging of mitochondria will not only be helpful in understanding mitochondrial structure in detail but it also could be used to analyze their structural relationships with other organelles in the cell. FRAP (fluorescence recovery after photobleaching) studies can be performed to understand mitochondrial dynamics or dynamics of any mitochondrial molecule within the organelle. The microirradiation assay can be performed to study functional continuity between mitochondria. A protocol for measuring mitochondrial potential has also been included in this unit. In conclusion, the protocols described here will aid the understanding of mitochondrial structure-function relationship.
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Affiliation(s)
- Kasturi Mitra
- National Institute of Child Health and Human Development, NIH, Bethesda, Maryland, USA
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92
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Hoyle CHV, Pintor JJ. Diadenosine tetraphosphate protects sympathetic terminals from 6-hydroxydopamine-induced degeneration in the eye. Acta Physiol (Oxf) 2010; 199:205-10. [PMID: 20121713 DOI: 10.1111/j.1748-1716.2010.02089.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS To examine diadenosine tetraphosphate (Ap(4)A) for its ability to protect the eye from neurodegeneration induced by subconjunctival application of 6-hydroxydopamine (6-OHDA). METHODS Intraocular neurodegeneration of anterior structures was induced by subconjunctival injections of 6-OHDA. Animals were pre-treated with topical corneal applications of Ap(4)A or saline. RESULTS 6-OHDA caused miosis, abnormal pupillary light reflexes, a precipitous drop in intraocular pressure and loss of VMAT2-labelled (vesicle monoamine transporter-2, a marker for sympathetic neurones) intraocular neurones. Pre-treatment with Ap(4)A prevented all of these changes from being induced by 6-OHDA, demonstrably preserving the sympathetic innervation of the ciliary processes. This neuroprotective action of Ap(4)A was not shared with the related compounds adenosine, ATP or diadenosine pentaphosphate. P2-receptor antagonists showed that the effects of Ap(4)A were mediated via a P2-receptor. CONCLUSION Ap4A is a natural component of tears and aqueous humour, and its neuroprotective effect indicates that one of its physiological roles is to maintain neurones within the eye. Ap(4)A can prevent the degeneration of intraocular nerves, and it is suggested that this compound may provide the basis for a therapeutic intervention aimed at preventing or ameliorating the development of glaucoma associated with neurodegenerative diseases. Furthermore, subconjunctival application of 6-OHDA provides a useful model for studying diseases that cause ocular sympathetic dysautonomia.
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Affiliation(s)
- C H V Hoyle
- Dep. Bioquímica, Escuela Universitaria de Optica, Universidad Complutense de Madrid, Madrid, Spain
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93
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Detection of heteroplasmy in individual mitochondrial particles. Anal Bioanal Chem 2010; 397:3397-407. [PMID: 20467729 DOI: 10.1007/s00216-010-3751-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Revised: 04/12/2010] [Accepted: 04/13/2010] [Indexed: 10/19/2022]
Abstract
Mitochondrial DNA (mtDNA) mutations have been associated with disease and aging. Since each cell has thousands of mtDNA copies, clustered into nucleoids of five to ten mtDNA molecules each, determining the effects of a given mtDNA mutation and their connection with disease phenotype is not straightforward. It has been postulated that heteroplasmy (coexistence of mutated and wild-type DNA) follows simple probability rules dictated by the random distribution of mtDNA molecules at the nucleoid level. This model has been used to explain how mutation levels correlate with the onset of disease phenotype and loss of cellular function. Nonetheless, experimental evidence of heteroplasmy at the nucleoid level is scarce. Here, we report a new method to determine heteroplasmy of individual mitochondrial particles containing one or more nucleoids. The method uses capillary cytometry with laser-induced fluorescence detection to detect individual mitochondrial particles stained with PicoGreen, which makes it possible to quantify the mtDNA copy number of each particle. After detection, one or more particles are collected into polymerase chain reaction (PCR) wells and then subjected to real-time multiplexed PCR amplification. This PCR strategy is suitable to obtain the relative abundance of mutated and wild-type mtDNA. The results obtained here indicate that individual mitochondrial particles and nucleoids contained within these particles are not heteroplasmic. The results presented here suggest that current models of mtDNA segregation and distribution (i.e., heteroplasmic nucleoids) need further consideration.
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94
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Zielonka J, Kalyanaraman B. Hydroethidine- and MitoSOX-derived red fluorescence is not a reliable indicator of intracellular superoxide formation: another inconvenient truth. Free Radic Biol Med 2010; 48:983-1001. [PMID: 20116425 PMCID: PMC3587154 DOI: 10.1016/j.freeradbiomed.2010.01.028] [Citation(s) in RCA: 383] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 01/20/2010] [Accepted: 01/21/2010] [Indexed: 12/15/2022]
Abstract
Hydroethidine (HE; or dihydroethidium) is the most popular fluorogenic probe used for detecting intracellular superoxide radical anion. The reaction between superoxide and HE generates a highly specific red fluorescent product, 2-hydroxyethidium (2-OH-E(+)). In biological systems, another red fluorescent product, ethidium, is also formed, usually at a much higher concentration than 2-OH-E(+). In this article, we review the methods to selectively detect the superoxide-specific product (2-OH-E(+)) and the factors affecting its levels in cellular and biological systems. The most important conclusion of this review is that it is nearly impossible to assess the intracellular levels of the superoxide-specific product, 2-OH-E(+), using confocal microscopy or other fluorescence-based microscopic assays and that it is essential to measure by HPLC the intracellular HE and other oxidation products of HE, in addition to 2-OH-E(+), to fully understand the origin of red fluorescence. The chemical reactivity of mitochondria-targeted hydroethidine (Mito-HE, MitoSOX red) with superoxide is similar to the reactivity of HE with superoxide, and therefore, all of the limitations attributed to the HE assay are applicable to Mito-HE (or MitoSOX) as well.
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Affiliation(s)
- Jacek Zielonka
- Department of Biophysics and Free Radical Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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95
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Spelbrink JN. Functional organization of mammalian mitochondrial DNA in nucleoids: history, recent developments, and future challenges. IUBMB Life 2010; 62:19-32. [PMID: 20014006 DOI: 10.1002/iub.282] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Various proteins involved in replication, repair, and the structural organization of mitochondrial DNA (mtDNA) have been characterized in detail over the past 25 or so years. In addition, in recent years, many proteins were identified with a role in the dynamics of the mitochondrial network. Using advanced imaging and an increasing number of cytological techniques, we have begun to realize that an important aspect to mtDNA maintenance, in both health and disease, is its organization within the dynamic mitochondrial network in discrete protein-DNA complexes usually termed nucleoids. Here, I review recent developments in the study of nucleoid dynamics and proteins. I will discuss the implications of the organization of mtDNA in nucleoids in light of DNA replication, repair, gene expression, segregation, and inheritance.
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Affiliation(s)
- Johannes N Spelbrink
- FinMIT Centre of Excellence, Institute of Medical Technology and Tampere University Hospital, University of Tampere, Tampere 33014 TAY, Finland.
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96
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Barker PE, Murthy M. Biomarker Validation for Aging: Lessons from mtDNA Heteroplasmy Analyses in Early Cancer Detection. Biomark Insights 2009; 4:165-79. [PMID: 20029650 PMCID: PMC2796862 DOI: 10.4137/bmi.s2253] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The anticipated biological and clinical utility of biomarkers has attracted significant interest recently. Aging and early cancer detection represent areas active in the search for predictive and prognostic biomarkers. While applications differ, overlapping biological features, analytical technologies and specific biomarker analytes bear comparison. Mitochondrial DNA (mtDNA) as a biomarker in both biological models has been evaluated. However, it remains unclear whether mtDNA changes in aging and cancer represent biological relationships that are causal, incidental, or a combination of both. This article focuses on evaluation of mtDNA-based biomarkers, emerging strategies for quantitating mtDNA admixtures, and how current understanding of mtDNA in aging and cancer evolves with introduction of new technologies. Whether for cancer or aging, lessons from mtDNA based biomarker evaluations are several. Biological systems are inherently dynamic and heterogeneous. Detection limits for mtDNA sequencing technologies differ among methods for low-level DNA sequence admixtures in healthy and diseased states. Performance metrics of analytical mtDNA technology should be validated prior to application in heterogeneous biologically-based systems. Critical in evaluating biomarker performance is the ability to distinguish measurement system variance from inherent biological variance, because it is within the latter that background healthy variability as well as high-value, disease-specific information reside.
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Affiliation(s)
- Peter E. Barker
- Bioassay Methods Group, Biochemical Sciences Division, Bldg 227/B248, NIST, 100 Bureau Drive, Gaithersburg, Maryland
| | - Mahadev Murthy
- Division of Aging Biology (DAB), National Institute on Aging, 7201 Wisconsin Ave., GW 2C231, Bethesda, MD 20892.
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97
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Baqri RM, Turner BA, Rheuben MB, Hammond BD, Kaguni LS, Miller KE. Disruption of mitochondrial DNA replication in Drosophila increases mitochondrial fast axonal transport in vivo. PLoS One 2009; 4:e7874. [PMID: 19924234 PMCID: PMC2773408 DOI: 10.1371/journal.pone.0007874] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 10/16/2009] [Indexed: 01/16/2023] Open
Abstract
Mutations in mitochondrial DNA polymerase (pol γ) cause several progressive human diseases including Parkinson's disease, Alper's syndrome, and progressive external ophthalmoplegia. At the cellular level, disruption of pol γ leads to depletion of mtDNA, disrupts the mitochondrial respiratory chain, and increases susceptibility to oxidative stress. Although recent studies have intensified focus on the role of mtDNA in neuronal diseases, the changes that take place in mitochondrial biogenesis and mitochondrial axonal transport when mtDNA replication is disrupted are unknown. Using high-speed confocal microscopy, electron microscopy and biochemical approaches, we report that mutations in pol γ deplete mtDNA levels and lead to an increase in mitochondrial density in Drosophila proximal nerves and muscles, without a noticeable increase in mitochondrial fragmentation. Furthermore, there is a rise in flux of bidirectional mitochondrial axonal transport, albeit with slower kinesin-based anterograde transport. In contrast, flux of synaptic vesicle precursors was modestly decreased in pol γ−α mutants. Our data indicate that disruption of mtDNA replication does not hinder mitochondrial biogenesis, increases mitochondrial axonal transport, and raises the question of whether high levels of circulating mtDNA-deficient mitochondria are beneficial or deleterious in mtDNA diseases.
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Affiliation(s)
- Rehan M. Baqri
- Department of Zoology, Michigan State University, East Lansing, Michigan, United States of America
- Neuroscience Program, Michigan State University, East Lansing, Michigan, United States of America
- Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, Michigan, United States of America
| | - Brittany A. Turner
- Department of Zoology, Michigan State University, East Lansing, Michigan, United States of America
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Mary B. Rheuben
- Neuroscience Program, Michigan State University, East Lansing, Michigan, United States of America
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, Michigan, United States of America
| | - Bradley D. Hammond
- Department of Zoology, Michigan State University, East Lansing, Michigan, United States of America
- Neuroscience Program, Michigan State University, East Lansing, Michigan, United States of America
- Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, Michigan, United States of America
| | - Laurie S. Kaguni
- Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, Michigan, United States of America
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Kyle E. Miller
- Department of Zoology, Michigan State University, East Lansing, Michigan, United States of America
- Neuroscience Program, Michigan State University, East Lansing, Michigan, United States of America
- Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
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98
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Ashley N, Poulton J. Anticancer DNA intercalators cause p53-dependent mitochondrial DNA nucleoid re-modelling. Oncogene 2009; 28:3880-91. [PMID: 19684617 PMCID: PMC4548715 DOI: 10.1038/onc.2009.242] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 06/07/2009] [Accepted: 07/08/2009] [Indexed: 12/13/2022]
Abstract
Many anticancer drugs, such as doxorubicin (DXR), intercalate into nuclear DNA of cancer cells, thereby inhibiting their growth. However, it is not well understood how such drugs interact with mitochondrial DNA (mtDNA). Using cell and molecular studies of cultured cells, we show that DXR and other DNA intercalators, such as ethidium bromide, can rapidly intercalate into mtDNA within living cells, causing aggregation of mtDNA nucleoids and altering the distribution of nucleoid proteins. Remodelled nucleoids excluded DXR and maintained mtDNA synthesis, whereas non-remodelled nucleoids became heavily intercalated with DXR, which inhibited their replication, thus leading to mtDNA depletion. Remodelling was accompanied by extensive mitochondrial elongation or interconnection, and was suppressed in cells lacking mitofusin 1 and optic atrophy 1 (OPA1), the key proteins for mitochondrial fusion. In contrast, remodelling was significantly increased by p53 or ataxia telangiectasia mutated inhibition (ATM), indicating a link between nucleoid dynamics and the genomic DNA damage response. Collectively, our results show that DNA intercalators can trigger a common mitochondrial response, which likely contributes to the marked clinical toxicity associated with these drugs.
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Affiliation(s)
- N Ashley
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Headington, Oxford, UK.
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99
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Sumitani M, Kasashima K, Ohta E, Kang D, Endo H. Association of a Novel Mitochondrial Protein M19 with Mitochondrial Nucleoids. ACTA ACUST UNITED AC 2009; 146:725-32. [DOI: 10.1093/jb/mvp118] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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100
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Hornig-Do HT, Günther G, Bust M, Lehnartz P, Bosio A, Wiesner RJ. Isolation of functional pure mitochondria by superparamagnetic microbeads. Anal Biochem 2009; 389:1-5. [DOI: 10.1016/j.ab.2009.02.040] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Revised: 02/06/2009] [Accepted: 02/27/2009] [Indexed: 10/21/2022]
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