1
|
Bernardino Gomes TM, Vincent AE, Menger KE, Stewart JB, Nicholls TJ. Mechanisms and pathologies of human mitochondrial DNA replication and deletion formation. Biochem J 2024; 481:683-715. [PMID: 38804971 DOI: 10.1042/bcj20230262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 05/29/2024]
Abstract
Human mitochondria possess a multi-copy circular genome, mitochondrial DNA (mtDNA), that is essential for cellular energy metabolism. The number of copies of mtDNA per cell, and their integrity, are maintained by nuclear-encoded mtDNA replication and repair machineries. Aberrant mtDNA replication and mtDNA breakage are believed to cause deletions within mtDNA. The genomic location and breakpoint sequences of these deletions show similar patterns across various inherited and acquired diseases, and are also observed during normal ageing, suggesting a common mechanism of deletion formation. However, an ongoing debate over the mechanism by which mtDNA replicates has made it difficult to develop clear and testable models for how mtDNA rearrangements arise and propagate at a molecular and cellular level. These deletions may impair energy metabolism if present in a high proportion of the mtDNA copies within the cell, and can be seen in primary mitochondrial diseases, either in sporadic cases or caused by autosomal variants in nuclear-encoded mtDNA maintenance genes. These mitochondrial diseases have diverse genetic causes and multiple modes of inheritance, and show notoriously broad clinical heterogeneity with complex tissue specificities, which further makes establishing genotype-phenotype relationships challenging. In this review, we aim to cover our current understanding of how the human mitochondrial genome is replicated, the mechanisms by which mtDNA replication and repair can lead to mtDNA instability in the form of large-scale rearrangements, how rearranged mtDNAs subsequently accumulate within cells, and the pathological consequences when this occurs.
Collapse
Affiliation(s)
- Tiago M Bernardino Gomes
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- NHS England Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, U.K
| | - Amy E Vincent
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Katja E Menger
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - James B Stewart
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Thomas J Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| |
Collapse
|
2
|
Brañas Casas R, Zuppardo A, Risato G, Dinarello A, Celeghin R, Fontana C, Grelloni E, Gilea AI, Viscomi C, Rasola A, Dalla Valle L, Lodi T, Baruffini E, Facchinello N, Argenton F, Tiso N. Zebrafish polg2 knock-out recapitulates human POLG-disorders; implications for drug treatment. Cell Death Dis 2024; 15:281. [PMID: 38643274 PMCID: PMC11032366 DOI: 10.1038/s41419-024-06622-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 03/15/2024] [Accepted: 03/18/2024] [Indexed: 04/22/2024]
Abstract
The human mitochondrial DNA polymerase gamma is a holoenzyme, involved in mitochondrial DNA (mtDNA) replication and maintenance, composed of a catalytic subunit (POLG) and a dimeric accessory subunit (POLG2) conferring processivity. Mutations in POLG or POLG2 cause POLG-related diseases in humans, leading to a subset of Mendelian-inherited mitochondrial disorders characterized by mtDNA depletion (MDD) or accumulation of multiple deletions, presenting multi-organ defects and often leading to premature death at a young age. Considering the paucity of POLG2 models, we have generated a stable zebrafish polg2 mutant line (polg2ia304) by CRISPR/Cas9 technology, carrying a 10-nucleotide deletion with frameshift mutation and premature stop codon. Zebrafish polg2 homozygous mutants present slower development and decreased viability compared to wild type siblings, dying before the juvenile stage. Mutants display a set of POLG-related phenotypes comparable to the symptoms of human patients affected by POLG-related diseases, including remarkable MDD, altered mitochondrial network and dynamics, and reduced mitochondrial respiration. Histological analyses detected morphological alterations in high-energy demanding tissues, along with a significant disorganization of skeletal muscle fibres. Consistent with the last finding, locomotor assays highlighted a decreased larval motility. Of note, treatment with the Clofilium tosylate drug, previously shown to be effective in POLG models, could partially rescue MDD in Polg2 mutant animals. Altogether, our results point at zebrafish as an effective model to study the etiopathology of human POLG-related disorders linked to POLG2, and a suitable platform to screen the efficacy of POLG-directed drugs in POLG2-associated forms.
Collapse
Affiliation(s)
| | - Alessandro Zuppardo
- Department of Biomedical Sciences, University of Padova, Padova, 35131, Italy
| | - Giovanni Risato
- Department of Biology, University of Padova, Padova, 35131, Italy
- Department of Cardio-Thoraco-Vascular Sciences and Public Health, University of Padova, Padova, 35128, Italy
| | - Alberto Dinarello
- Department of Biology, University of Padova, Padova, 35131, Italy
- Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW), University of Copenhagen, Copenhagen, 2200, Denmark
| | - Rudy Celeghin
- Department of Cardio-Thoraco-Vascular Sciences and Public Health, University of Padova, Padova, 35128, Italy
| | - Camilla Fontana
- Department of Biology, University of Padova, Padova, 35131, Italy
- Department of Animal and Aquatic Sciences, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200, Thailand
| | | | - Alexandru Ionut Gilea
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, 43124, Italy
| | - Carlo Viscomi
- Department of Biomedical Sciences, University of Padova, Padova, 35131, Italy
| | - Andrea Rasola
- Department of Biomedical Sciences, University of Padova, Padova, 35131, Italy
| | | | - Tiziana Lodi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, 43124, Italy
| | - Enrico Baruffini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, 43124, Italy
| | - Nicola Facchinello
- Neuroscience Institute, Italian Research Council (CNR), 35131, Padova, Italy.
| | | | - Natascia Tiso
- Department of Biology, University of Padova, Padova, 35131, Italy.
| |
Collapse
|
3
|
Wojtaszek JL, Hoff KE, Longley MJ, Kaur P, Andres S, Wang H, Williams R, Copeland W. Structure-specific roles for PolG2-DNA complexes in maintenance and replication of mitochondrial DNA. Nucleic Acids Res 2023; 51:9716-9732. [PMID: 37592734 PMCID: PMC10570022 DOI: 10.1093/nar/gkad679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/13/2023] [Accepted: 08/09/2023] [Indexed: 08/19/2023] Open
Abstract
The homodimeric PolG2 accessory subunit of the mitochondrial DNA polymerase gamma (Pol γ) enhances DNA binding and processive DNA synthesis by the PolG catalytic subunit. PolG2 also directly binds DNA, although the underlying molecular basis and functional significance are unknown. Here, data from Atomic Force Microscopy (AFM) and X-ray structures of PolG2-DNA complexes define dimeric and hexameric PolG2 DNA binding modes. Targeted disruption of PolG2 DNA-binding interfaces impairs processive DNA synthesis without diminishing Pol γ subunit affinities. In addition, a structure-specific DNA-binding role for PolG2 oligomers is supported by X-ray structures and AFM showing that oligomeric PolG2 localizes to DNA crossings and targets forked DNA structures resembling the mitochondrial D-loop. Overall, data indicate that PolG2 DNA binding has both PolG-dependent and -independent functions in mitochondrial DNA replication and maintenance, which provide new insight into molecular defects associated with PolG2 disruption in mitochondrial disease.
Collapse
Affiliation(s)
- Jessica L Wojtaszek
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Kirsten E Hoff
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Matthew J Longley
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Parminder Kaur
- Physics Department, North Carolina State University, Raleigh, NC 27695, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
| | - Sara N Andres
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Hong Wang
- Physics Department, North Carolina State University, Raleigh, NC 27695, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
- Toxicology Program, North Carolina State University, Raleigh, NC 27695, USA
| | - R Scott Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| |
Collapse
|
4
|
Katsuda T, Cure H, Sussman J, Simeonov KP, Krapp C, Arany Z, Grompe M, Stanger BZ. Rapid in vivo multiplexed editing (RIME) of the adult mouse liver. Hepatology 2023; 78:486-502. [PMID: 36037289 PMCID: PMC11088813 DOI: 10.1002/hep.32759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 07/25/2022] [Accepted: 08/22/2022] [Indexed: 12/08/2022]
Abstract
BACKGROUND AND AIMS Assessing mammalian gene function in vivo has traditionally relied on manipulation of the mouse genome in embryonic stem cells or perizygotic embryos. These approaches are time-consuming and require extensive breeding when simultaneous mutations in multiple genes is desired. The aim of this study is to introduce a rapid in vivo multiplexed editing (RIME) method and provide proof of concept of this system. APPROACH AND RESULTS RIME, a system wherein CRISPR/caspase 9 technology, paired with adeno-associated viruses (AAVs), permits the inactivation of one or more genes in the adult mouse liver. The method is quick, requiring as little as 1 month from conceptualization to knockout, and highly efficient, enabling editing in >95% of target cells. To highlight its use, we used this system to inactivate, alone or in combination, genes with functions spanning metabolism, mitosis, mitochondrial maintenance, and cell proliferation. CONCLUSIONS RIME enables the rapid, efficient, and inexpensive analysis of multiple genes in the mouse liver in vivo .
Collapse
Affiliation(s)
- Takeshi Katsuda
- Department of Medicine , University of Pennsylvania , Philadelphia , Pennsylvania , USA
- Department of Cell and Developmental Biology , University of Pennsylvania , Philadelphia , Pennsylvania , USA
- Abramson Family Cancer Research Institute , University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Hector Cure
- Department of Medicine , University of Pennsylvania , Philadelphia , Pennsylvania , USA
- Department of Cell and Developmental Biology , University of Pennsylvania , Philadelphia , Pennsylvania , USA
- Abramson Family Cancer Research Institute , University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Jonathan Sussman
- Department of Medicine , University of Pennsylvania , Philadelphia , Pennsylvania , USA
- Department of Cell and Developmental Biology , University of Pennsylvania , Philadelphia , Pennsylvania , USA
- Abramson Family Cancer Research Institute , University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Kamen P Simeonov
- Department of Biomedical Sciences, School of Veterinary Medicine , University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Christopher Krapp
- Department of Cell and Developmental Biology , University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Zoltan Arany
- Cardiovascular Institute, Perelman School of Medicine , University of Pennsylvania , Philadelphia , Pennsylvania , USA
| | - Markus Grompe
- Department of Pediatrics , Oregon Health & Science University , Portland , Oregon , USA
| | - Ben Z Stanger
- Department of Medicine , University of Pennsylvania , Philadelphia , Pennsylvania , USA
- Department of Cell and Developmental Biology , University of Pennsylvania , Philadelphia , Pennsylvania , USA
- Abramson Family Cancer Research Institute , University of Pennsylvania , Philadelphia , Pennsylvania , USA
| |
Collapse
|
5
|
Verma M, Francis L, Lizama BN, Callio J, Fricklas G, Wang KZQ, Kaufman BA, D'Aiuto L, Stolz DB, Watkins SC, Nimgaonkar VL, Soto-Gutierrez A, Goldstein A, Chu CT. iPSC-Derived Neurons from Patients with POLG Mutations Exhibit Decreased Mitochondrial Content and Dendrite Simplification. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:201-212. [PMID: 36414085 PMCID: PMC9976192 DOI: 10.1016/j.ajpath.2022.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 10/18/2022] [Accepted: 11/03/2022] [Indexed: 11/21/2022]
Abstract
Mutations in POLG, the gene encoding the catalytic subunit of DNA polymerase gamma, result in clinical syndromes characterized by mitochondrial DNA (mtDNA) depletion in affected tissues with variable organ involvement. The brain is one of the most affected organs, and symptoms include intractable seizures, developmental delay, dementia, and ataxia. Patient-derived induced pluripotent stem cells (iPSCs) provide opportunities to explore mechanisms in affected cell types and potential therapeutic strategies. Fibroblasts from two patients were reprogrammed to create new iPSC models of POLG-related mitochondrial diseases. Compared with iPSC-derived control neurons, mtDNA depletion was observed upon differentiation of the POLG-mutated lines to cortical neurons. POLG-mutated neurons exhibited neurite simplification with decreased mitochondrial content, abnormal mitochondrial structure and function, and increased cell death. Expression of the mitochondrial kinase PTEN-induced kinase 1 (PINK1) mRNA was decreased in patient neurons. Overexpression of PINK1 increased mitochondrial content and ATP:ADP ratios in neurites, decreasing cell death and rescuing neuritic complexity. These data indicate an intersection of polymerase gamma and PINK1 pathways that may offer a novel therapeutic option for patients affected by this spectrum of disorders.
Collapse
Affiliation(s)
- Manish Verma
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Lily Francis
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Britney N Lizama
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jason Callio
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Gabriella Fricklas
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Kent Z Q Wang
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Brett A Kaufman
- Department of Medicine, Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Leonardo D'Aiuto
- Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Donna B Stolz
- Center for Biologic Imaging (CBI), University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Simon C Watkins
- Center for Biologic Imaging (CBI), University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Vishwajit L Nimgaonkar
- Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania
| | | | - Amy Goldstein
- Mitochondrial Medicine Frontier Program, Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Charleen T Chu
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
| |
Collapse
|
6
|
Khozhukhar N, Spadafora D, Rodriguez Rodriguez YA, Fayzulin R, Alexeyev M. Generation of Mammalian Cells Devoid of Mitochondrial DNA (ρ 0 cells). Curr Protoc 2023; 3:e679. [PMID: 36809687 PMCID: PMC10151036 DOI: 10.1002/cpz1.679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
To cope with DNA damage, mitochondria have developed a pathway whereby severely damaged or unrepairable mitochondrial DNA (mtDNA) molecules can be discarded and degraded, after which new molecules are synthesized using intact templates. In this unit, we describe a method that harnesses this pathway to eliminate mtDNA from mammalian cells by transiently overexpressing the Y147A mutant of human uracil-N-glycosylase (mUNG1) in mitochondria. We also provide alternate protocols for mtDNA elimination using either combined treatment with ethidium bromide (EtBr) and dideoxycytidine (ddC) or clustered regulatory interspersed short palindromic repeat (CRISPR)-Cas9-mediated knockout of TFAM or other genes essential for mtDNA replication. Support protocols detail approaches for several processes: (1) genotyping ρ0 cells of human, mouse, and rat origin by polymerase chain reaction (PCR); (2) quantification of mtDNA by quantitative PCR (qPCR); (3) preparation of calibrator plasmids for mtDNA quantification; and (4) quantification of mtDNA by direct droplet digital PCR (dddPCR). © 2023 Wiley Periodicals LLC. Basic Protocol: Inducing mtDNA loss with mUNG1 Alternate Protocol 1: Generation of ρ0 cells by mtDNA depletion with EtBr and ddC Alternate Protocol 2: Generation of ρ0 cells by knocking out genes critical for mtDNA replication Support Protocol 1: Genotyping ρ0 cells by DirectPCR Support Protocol 2: Determination of mtDNA copy number by qPCR Support Protocol 3: Preparation of calibrator plasmid for qPCR Support Protocol 4: Determination of mtCN by direct droplet digital PCR (dddPCR).
Collapse
Affiliation(s)
| | | | | | - Rafik Fayzulin
- University of South Alabama, Department of Physiology and Cell Biology
| | - Mikhail Alexeyev
- University of South Alabama, Department of Physiology and Cell Biology
| |
Collapse
|
7
|
Kozhukhar N, Spadafora D, Rodriguez YAR, Alexeyev MF. A Method for In Situ Reverse Genetic Analysis of Proteins Involved mtDNA Replication. Cells 2022; 11:2168. [PMID: 35883613 PMCID: PMC9316749 DOI: 10.3390/cells11142168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 06/29/2022] [Accepted: 07/10/2022] [Indexed: 02/01/2023] Open
Abstract
The unavailability of tractable reverse genetic analysis approaches represents an obstacle to a better understanding of mitochondrial DNA replication. Here, we used CRISPR-Cas9 mediated gene editing to establish the conditional viability of knockouts in the key proteins involved in mtDNA replication. This observation prompted us to develop a set of tools for reverse genetic analysis in situ, which we called the GeneSwap approach. The technique was validated by identifying 730 amino acid (aa) substitutions in the mature human TFAM that are conditionally permissive for mtDNA replication. We established that HMG domains of TFAM are functionally independent, which opens opportunities for engineering chimeric TFAMs with customized properties for studies on mtDNA replication, mitochondrial transcription, and respiratory chain function. Finally, we present evidence that the HMG2 domain plays the leading role in TFAM species-specificity, thus indicating a potential pathway for TFAM-mtDNA evolutionary co-adaptations.
Collapse
Affiliation(s)
| | | | | | - Mikhail F. Alexeyev
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, AL 36688, USA; (N.K.); (D.S.); (Y.A.R.R.)
| |
Collapse
|
8
|
Roy A, Kandettu A, Ray S, Chakrabarty S. Mitochondrial DNA replication and repair defects: Clinical phenotypes and therapeutic interventions. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148554. [PMID: 35341749 DOI: 10.1016/j.bbabio.2022.148554] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 03/06/2022] [Accepted: 03/16/2022] [Indexed: 12/15/2022]
Abstract
Mitochondria is a unique cellular organelle involved in multiple cellular processes and is critical for maintaining cellular homeostasis. This semi-autonomous organelle contains its circular genome - mtDNA (mitochondrial DNA), that undergoes continuous cycles of replication and repair to maintain the mitochondrial genome integrity. The majority of the mitochondrial genes, including mitochondrial replisome and repair genes, are nuclear-encoded. Although the repair machinery of mitochondria is quite efficient, the mitochondrial genome is highly susceptible to oxidative damage and other types of exogenous and endogenous agent-induced DNA damage, due to the absence of protective histones and their proximity to the main ROS production sites. Mutations in replication and repair genes of mitochondria can result in mtDNA depletion and deletions subsequently leading to mitochondrial genome instability. The combined action of mutations and deletions can result in compromised mitochondrial genome maintenance and lead to various mitochondrial disorders. Here, we review the mechanism of mitochondrial DNA replication and repair process, key proteins involved, and their altered function in mitochondrial disorders. The focus of this review will be on the key genes of mitochondrial DNA replication and repair machinery and the clinical phenotypes associated with mutations in these genes.
Collapse
Affiliation(s)
- Abhipsa Roy
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Amoolya Kandettu
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Swagat Ray
- Department of Life Sciences, School of Life and Environmental Sciences, University of Lincoln, Lincoln LN6 7TS, United Kingdom
| | - Sanjiban Chakrabarty
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
| |
Collapse
|
9
|
Chen Y, Liu Z, Chen H, Huang X, Huang X, Lei Y, Liang Q, Wei J, Zhang Q, Guo X, Huang Q. p53 SUMOylation Mediates AOPP-Induced Endothelial Senescence and Apoptosis Evasion. Front Cardiovasc Med 2022; 8:795747. [PMID: 35187108 PMCID: PMC8850781 DOI: 10.3389/fcvm.2021.795747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 12/30/2021] [Indexed: 12/14/2022] Open
Abstract
The aging of endothelial cells plays a critical role in the development of age-related vascular disease. We established a model of endothelial premature senescence by application of Advanced oxidation protein products (AOPPs) modified bovine serum albumin (AOPP-BSA) in human umbilical vein endothelial cells (HUVECs). This cellular senescence was accompanied with endothelial barrier dysfunction and angiogenesis impairment. It was further revealed that these senescent HUVECs underwent apoptosis evasion and the receptor for advanced glycation endproducts (RAGE) played a role in these processes. The AOPP-induced senescence was regulated by the state of autophagy in HUVECs. We further proved that AOPP-BSA attenuated the autophagy of HUVECs, led to p53 SUMOylation at K386, resulting in endothelial senescence. We also established the animal model of vascular senescence by using ApoE−/− mice fed with high-fat diet plus daily injection of AOPP-BSA to verify the role of p53 SUMOylation in vascular senescence. Combined with intraperitoneal injection of rapamycin, the effect of autophagy on AOPP-induced p53 SUMOylation was also confirmed in vivo. Our data indicates that p53 SUMOylation at K386 plays an important role in AOPP-induced endothelial senescence and apoptosis evasion, suggesting that p53 K386 SUMOylation may serve as a potential therapeutic target in protecting against vascular senescence.
Collapse
Affiliation(s)
- Yanjia Chen
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Shock and Microcirculation, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Zhuanhua Liu
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Shock and Microcirculation, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Hongyu Chen
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Shock and Microcirculation, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Xingfu Huang
- Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xiaoxia Huang
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Shock and Microcirculation, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Yang Lei
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Shock and Microcirculation, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Qing Liang
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Shock and Microcirculation, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Jiayi Wei
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Shock and Microcirculation, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Qin Zhang
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Shock and Microcirculation, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Xiaohua Guo
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Shock and Microcirculation, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Qiaobing Huang
- Department of Pathophysiology, Guangdong Provincial Key Laboratory of Shock and Microcirculation, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
- *Correspondence: Qiaobing Huang
| |
Collapse
|
10
|
Li X, Zou C, Li M, Fang C, Li K, Liu Z, Li C. Transcriptome Analysis of In Vitro Fertilization and Parthenogenesis Activation during Early Embryonic Development in Pigs. Genes (Basel) 2021; 12:genes12101461. [PMID: 34680856 PMCID: PMC8535918 DOI: 10.3390/genes12101461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 09/14/2021] [Accepted: 09/15/2021] [Indexed: 11/16/2022] Open
Abstract
Parthenogenesis activation (PA), as an important artificial breeding method, can stably preserve the dominant genotype of a species. However, the delayed development of PA embryos is still overly severe and largely leads to pre-implantation failure in pigs. The mechanisms underlying the deficiencies of PA embryos have not been completely understood. For further understanding of the molecular mechanism behind PA embryo failure, we performed transcriptome analysis among pig oocytes (meiosis II, MII) and early embryos at three developmental stages (zygote, morula, and blastocyst) in vitro fertilization (IVF) and PA group. Totally, 11,110 differentially expressed genes (DEGs), 4694 differentially expressed lincRNAs (DELs) were identified, and most DEGs enriched the regulation of apoptotic processes. Through cis- and trans-manner functional prediction, we found that hub lincRNAs were mostly involved in abnormal parthenogenesis embryonic development. In addition, twenty DE imprinted genes showed that some paternally imprinted genes in IVF displayed higher expression than that in PA. Notably, we identified that three DELs of imprinted genes (MEST, PLAGL1, and DIRAS3) were up regulated in IVF, and there was no significant change in PA group. Disordered expression of key genes for embryonic development might play key roles in abnormal parthenogenesis embryonic development. Our study indicates that embryos derived from different production techniques have varied in vitro development to the blastocyst stage, and they also affect the transcription level of corresponding genes, such as imprinted genes. This work will help future research on these genes and molecular-assisted breeding for pig parthenotes.
Collapse
Affiliation(s)
- Xin Li
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of the Ministry of Education and Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China; (X.L.); (C.Z.); (M.L.); (C.F.)
- The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Cheng Zou
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of the Ministry of Education and Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China; (X.L.); (C.Z.); (M.L.); (C.F.)
- The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Mengxun Li
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of the Ministry of Education and Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China; (X.L.); (C.Z.); (M.L.); (C.F.)
- The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Chengchi Fang
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of the Ministry of Education and Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China; (X.L.); (C.Z.); (M.L.); (C.F.)
- The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Kui Li
- Agricultural Genome Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518124, China;
- State Key Laboratory of Animal Nutrition, Key Laboratory of Animal Genetics Breeding and Reproduction of Ministry of Agriculture and Rural Affairs of China, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Zhiguo Liu
- State Key Laboratory of Animal Nutrition, Key Laboratory of Animal Genetics Breeding and Reproduction of Ministry of Agriculture and Rural Affairs of China, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China
- Correspondence: (Z.L.); (C.L.)
| | - Changchun Li
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of the Ministry of Education and Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China; (X.L.); (C.Z.); (M.L.); (C.F.)
- The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
- Correspondence: (Z.L.); (C.L.)
| |
Collapse
|
11
|
Contribution of Mitochondrial DNA Heteroplasmy to the Congenital Cardiac and Palatal Phenotypic Variability in Maternally Transmitted 22q11.2 Deletion Syndrome. Genes (Basel) 2021; 12:genes12010092. [PMID: 33450921 PMCID: PMC7828421 DOI: 10.3390/genes12010092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/24/2020] [Accepted: 01/11/2021] [Indexed: 11/25/2022] Open
Abstract
Congenital heart disease (CHD) and palatal anomalies (PA), are among the most common characteristics of 22q11.2 deletion syndrome (22q11.2DS), but they show incomplete penetrance, suggesting the presence of additional factors. The 22q11.2 deleted region contains nuclear encoded mitochondrial genes, and since mitochondrial function is critical during development, we hypothesized that changes in the mitochondrial DNA (mtDNA) could be involved in the intrafamilial variability of CHD and PA in cases of maternally inherited 22q11.2DS. To investigate this, we studied the transmission of heteroplasmic mtDNA alleles in seventeen phenotypically concordant and discordant mother-offspring 22q11.2DS pairs. We sequenced their mtDNA and identified 26 heteroplasmic variants at >1% frequency, representing 18 transmissions. The median allele frequency change between a mother and her child was twice as much, with a wider distribution range, in PA discordant pairs, p-value = 0.039 (permutation test, 11 concordant vs. 7 discordant variants), but not in CHD discordant pairs, p-value = 0.441 (9 vs. 9). Only the variant m.9507T>C was considered to be pathogenic, but it was unrelated to the structural phenotypes. Our study is novel, yet our results are not consistent with mtDNA variation contributing to PA or CHD in 22q11.2DS. Larger cohorts and additional factors should be considered moving forward.
Collapse
|
12
|
Crooks DR, Maio N, Lang M, Ricketts CJ, Vocke CD, Gurram S, Turan S, Kim YY, Cawthon GM, Sohelian F, De Val N, Pfeiffer RM, Jailwala P, Tandon M, Tran B, Fan TWM, Lane AN, Ried T, Wangsa D, Malayeri AA, Merino MJ, Yang Y, Meier JL, Ball MW, Rouault TA, Srinivasan R, Linehan WM. Mitochondrial DNA alterations underlie an irreversible shift to aerobic glycolysis in fumarate hydratase-deficient renal cancer. Sci Signal 2021; 14:14/664/eabc4436. [PMID: 33402335 DOI: 10.1126/scisignal.abc4436] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Understanding the mechanisms of the Warburg shift to aerobic glycolysis is critical to defining the metabolic basis of cancer. Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an aggressive cancer characterized by biallelic inactivation of the gene encoding the Krebs cycle enzyme fumarate hydratase, an early shift to aerobic glycolysis, and rapid metastasis. We observed impairment of the mitochondrial respiratory chain in tumors from patients with HLRCC. Biochemical and transcriptomic analyses revealed that respiratory chain dysfunction in the tumors was due to loss of expression of mitochondrial DNA (mtDNA)-encoded subunits of respiratory chain complexes, caused by a marked decrease in mtDNA content and increased mtDNA mutations. We demonstrated that accumulation of fumarate in HLRCC tumors inactivated the core factors responsible for replication and proofreading of mtDNA, leading to loss of respiratory chain components, thereby promoting the shift to aerobic glycolysis and disease progression in this prototypic model of glucose-dependent human cancer.
Collapse
Affiliation(s)
- Daniel R Crooks
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Nunziata Maio
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
| | - Martin Lang
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Christopher J Ricketts
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Cathy D Vocke
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Sandeep Gurram
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Sevilay Turan
- Sequencing Facility, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21701, USA
| | - Yun-Young Kim
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - G Mariah Cawthon
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Ferri Sohelian
- Electron Microscopy Laboratory, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21702, USA
| | - Natalia De Val
- Electron Microscopy Laboratory, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21702, USA
| | - Ruth M Pfeiffer
- Biostatistics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD 20850, USA
| | - Parthav Jailwala
- CCR Collaborative Bioinformatics Resource (CCBR), Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21702, USA.,Advanced Biomedical Computational Science, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21702, USA
| | - Mayank Tandon
- CCR Collaborative Bioinformatics Resource (CCBR), Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21702, USA.,Advanced Biomedical Computational Science, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21702, USA
| | - Bao Tran
- Sequencing Facility, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21701, USA
| | - Teresa W-M Fan
- Center for Environmental and Systems Biochemistry, Department of Toxicology and Cancer Biology and Markey Cancer Center, University of Kentucky, Lexington, KY 40536, USA
| | - Andrew N Lane
- Center for Environmental and Systems Biochemistry, Department of Toxicology and Cancer Biology and Markey Cancer Center, University of Kentucky, Lexington, KY 40536, USA
| | - Thomas Ried
- Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Darawalee Wangsa
- Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Ashkan A Malayeri
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Maria J Merino
- Genitourinary Pathology Section, Laboratory of Pathology, National Cancer Institute, Bethesda, MD 20892, USA
| | - Youfeng Yang
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Jordan L Meier
- Epigenetics and Metabolism Section, Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Mark W Ball
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Tracey A Rouault
- Molecular Medicine Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
| | - Ramaprasad Srinivasan
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - W Marston Linehan
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA.
| |
Collapse
|
13
|
Delavallée L, Mathiah N, Cabon L, Mazeraud A, Brunelle-Navas MN, Lerner LK, Tannoury M, Prola A, Moreno-Loshuertos R, Baritaud M, Vela L, Garbin K, Garnier D, Lemaire C, Langa-Vives F, Cohen-Salmon M, Fernández-Silva P, Chrétien F, Migeotte I, Susin SA. Mitochondrial AIF loss causes metabolic reprogramming, caspase-independent cell death blockade, embryonic lethality, and perinatal hydrocephalus. Mol Metab 2020; 40:101027. [PMID: 32480041 PMCID: PMC7334469 DOI: 10.1016/j.molmet.2020.101027] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/18/2020] [Accepted: 05/27/2020] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVES Apoptosis-Inducing Factor (AIF) is a protein involved in mitochondrial electron transport chain assembly/stability and programmed cell death. The relevant role of this protein is underlined because mutations altering mitochondrial AIF properties result in acute pediatric mitochondriopathies and tumor metastasis. By generating an original AIF-deficient mouse strain, this study attempted to analyze, in a single paradigm, the cellular and developmental metabolic consequences of AIF loss and the subsequent oxidative phosphorylation (OXPHOS) dysfunction. METHODS We developed a novel AIF-deficient mouse strain and assessed, using molecular and cell biology approaches, the cellular, embryonic, and adult mice phenotypic alterations. Additionally, we conducted ex vivo assays with primary and immortalized AIF knockout mouse embryonic fibroblasts (MEFs) to establish the cell death characteristics and the metabolic adaptive responses provoked by the mitochondrial electron transport chain (ETC) breakdown. RESULTS AIF deficiency destabilized mitochondrial ETC and provoked supercomplex disorganization, mitochondrial transmembrane potential loss, and high generation of mitochondrial reactive oxygen species (ROS). AIF-/Y MEFs counterbalanced these OXPHOS alterations by mitochondrial network reorganization and a metabolic reprogramming toward anaerobic glycolysis illustrated by the AMPK phosphorylation at Thr172, the overexpression of the glucose transporter GLUT-4, the subsequent enhancement of glucose uptake, and the anaerobic lactate generation. A late phenotype was characterized by the activation of P53/P21-mediated senescence. Notably, approximately 2% of AIF-/Y MEFs diminished both mitochondrial mass and ROS levels and spontaneously proliferated. These cycling AIF-/Y MEFs were resistant to caspase-independent cell death inducers. The AIF-deficient mouse strain was embryonic lethal between E11.5 and E13.5 with energy loss, proliferation arrest, and increased apoptotic levels. Contrary to AIF-/Y MEFs, the AIF KO embryos were unable to reprogram their metabolism toward anaerobic glycolysis. Heterozygous AIF+/- females displayed progressive bone marrow, thymus, and spleen cellular loss. In addition, approximately 10% of AIF+/- females developed perinatal hydrocephaly characterized by brain development impairment, meningeal fibrosis, and medullar hemorrhages; those mice died 5 weeks after birth. AIF+/- with hydrocephaly exhibited loss of ciliated epithelium in the ependymal layer. This phenotype was triggered by the ROS excess. Accordingly, it was possible to diminish the occurrence of hydrocephalus AIF+/- females by supplying dams and newborns with an antioxidant in drinking water. CONCLUSIONS In a single knockout model and at 3 different levels (cell, embryo, and adult mice) we demonstrated that by controlling the mitochondrial OXPHOS/metabolism, AIF is a key factor regulating cell differentiation and fate. Additionally, by providing new insights into the pathological consequences of mitochondrial OXPHOS dysfunction, our new findings pave the way for novel pharmacological strategies.
Collapse
Affiliation(s)
- Laure Delavallée
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Cell Death and Drug Resistance in Hematological Disorders Team, F-75006, Paris, France
| | - Navrita Mathiah
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Lauriane Cabon
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Cell Death and Drug Resistance in Hematological Disorders Team, F-75006, Paris, France
| | - Aurélien Mazeraud
- Experimental Neuropathology Unit, Institut Pasteur, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Neuropathology Service, Sainte-Anne Hospital Center, Paris, France
| | - Marie-Noelle Brunelle-Navas
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Cell Death and Drug Resistance in Hematological Disorders Team, F-75006, Paris, France
| | - Leticia K Lerner
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Cell Death and Drug Resistance in Hematological Disorders Team, F-75006, Paris, France
| | - Mariana Tannoury
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Cell Death and Drug Resistance in Hematological Disorders Team, F-75006, Paris, France
| | - Alexandre Prola
- INSERM UMRS 1180, LabEx LERMIT, Châtenay-Malabry, France; Faculté de Pharmacie, Université Paris-Sud, Châtenay-Malabry, France; Université de Versailles Saint Quentin en Yvelines, Versailles, France; U955-IMRB Team 10 BNMS, INSERM, UPEC, Université Paris-Est, Ecole Nationale Vétérinaire de Maisons-Alfort, France
| | - Raquel Moreno-Loshuertos
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain; Instituto de Investigación en Biocomputación y Física de Sistemas Complejos (BiFi), Universidad de Zaragoza, Zaragoza, Spain
| | - Mathieu Baritaud
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Cell Death and Drug Resistance in Hematological Disorders Team, F-75006, Paris, France
| | - Laura Vela
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Cell Death and Drug Resistance in Hematological Disorders Team, F-75006, Paris, France
| | - Kevin Garbin
- Centre de Recherche des Cordeliers, Genotyping and Biochemical facility, INSERM UMRS_1138, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
| | - Delphine Garnier
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Cell Death and Drug Resistance in Hematological Disorders Team, F-75006, Paris, France
| | - Christophe Lemaire
- INSERM UMRS 1180, LabEx LERMIT, Châtenay-Malabry, France; Faculté de Pharmacie, Université Paris-Sud, Châtenay-Malabry, France; Université de Versailles Saint Quentin en Yvelines, Versailles, France
| | | | - Martine Cohen-Salmon
- Physiology and Physiopathology of the Gliovascular Unit, Collège de France-Center for Interdisciplinary Research in Biology (CIRB)/CNRS UMR 7241/INSERM U1050/Sorbonne Université, Paris, France
| | - Patricio Fernández-Silva
- Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain; Instituto de Investigación en Biocomputación y Física de Sistemas Complejos (BiFi), Universidad de Zaragoza, Zaragoza, Spain
| | - Fabrice Chrétien
- Experimental Neuropathology Unit, Institut Pasteur, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Neuropathology Service, Sainte-Anne Hospital Center, Paris, France
| | - Isabelle Migeotte
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels, Belgium
| | - Santos A Susin
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Cell Death and Drug Resistance in Hematological Disorders Team, F-75006, Paris, France.
| |
Collapse
|
14
|
Falkenberg M, Gustafsson CM. Mammalian mitochondrial DNA replication and mechanisms of deletion formation. Crit Rev Biochem Mol Biol 2020; 55:509-524. [DOI: 10.1080/10409238.2020.1818684] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Claes M. Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
15
|
Mair B, Tomic J, Masud SN, Tonge P, Weiss A, Usaj M, Tong AHY, Kwan JJ, Brown KR, Titus E, Atkins M, Chan KSK, Munsie L, Habsid A, Han H, Kennedy M, Cohen B, Keller G, Moffat J. Essential Gene Profiles for Human Pluripotent Stem Cells Identify Uncharacterized Genes and Substrate Dependencies. Cell Rep 2020; 27:599-615.e12. [PMID: 30970261 DOI: 10.1016/j.celrep.2019.02.041] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 12/24/2018] [Accepted: 02/11/2019] [Indexed: 12/20/2022] Open
Abstract
Human pluripotent stem cells (hPSCs) provide an invaluable tool for modeling diseases and hold promise for regenerative medicine. For understanding pluripotency and lineage differentiation mechanisms, a critical first step involves systematically cataloging essential genes (EGs) that are indispensable for hPSC fitness, defined as cell reproduction in this study. To map essential genetic determinants of hPSC fitness, we performed genome-scale loss-of-function screens in an inducible Cas9 H1 hPSC line cultured on feeder cells and laminin to identify EGs. Among these, we found FOXH1 and VENTX, genes that encode transcription factors previously implicated in stem cell biology, as well as an uncharacterized gene, C22orf43/DRICH1. hPSC EGs are substantially different from other human model cell lines, and EGs in hPSCs are highly context dependent with respect to different growth substrates. Our CRISPR screens establish parameters for genome-wide screens in hPSCs, which will facilitate the characterization of unappreciated genetic regulators of hPSC biology.
Collapse
Affiliation(s)
- Barbara Mair
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Jelena Tomic
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Sanna N Masud
- Donnelly Centre, University of Toronto, Toronto, ON, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Peter Tonge
- Centre for Commercialization of Regenerative Medicine, Toronto, ON, Canada
| | | | - Matej Usaj
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | | | - Jamie J Kwan
- McEwen Stem Cell Institute, University Health Network, University of Toronto, Toronto, ON, Canada; Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Kevin R Brown
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Emily Titus
- Centre for Commercialization of Regenerative Medicine, Toronto, ON, Canada
| | - Michael Atkins
- McEwen Stem Cell Institute, University Health Network, University of Toronto, Toronto, ON, Canada; Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | | | - Lise Munsie
- Centre for Commercialization of Regenerative Medicine, Toronto, ON, Canada
| | - Andrea Habsid
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Hong Han
- Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Marion Kennedy
- McEwen Stem Cell Institute, University Health Network, University of Toronto, Toronto, ON, Canada; Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Brenda Cohen
- McEwen Stem Cell Institute, University Health Network, University of Toronto, Toronto, ON, Canada; Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Gordon Keller
- McEwen Stem Cell Institute, University Health Network, University of Toronto, Toronto, ON, Canada; Princess Margaret Cancer Centre, University Health Network, University of Toronto, Toronto, ON, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Jason Moffat
- Donnelly Centre, University of Toronto, Toronto, ON, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada; Canadian Institute for Advanced Research, Toronto, ON, Canada; Institute for Biomaterials and BioMedical Engineering, University of Toronto, ON, Canada.
| |
Collapse
|
16
|
Cheong A, Archambault D, Degani R, Iverson E, Tremblay KD, Mager J. Nuclear-encoded mitochondrial ribosomal proteins are required to initiate gastrulation. Development 2020; 147:dev.188714. [PMID: 32376682 DOI: 10.1242/dev.188714] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 03/30/2020] [Indexed: 12/11/2022]
Abstract
Mitochondria are essential for energy production and although they have their own genome, many nuclear-encoded mitochondrial ribosomal proteins (MRPs) are required for proper function of the organelle. Although mutations in MRPs have been associated with human diseases, little is known about their role during development. Presented here are the null phenotypes for 21 nuclear-encoded mitochondrial proteins and in-depth characterization of mouse embryos mutant for the Mrp genes Mrpl3, Mrpl22, Mrpl44, Mrps18c and Mrps22 Loss of each MRP results in successful implantation and egg-cylinder formation, followed by severe developmental delay and failure to initiate gastrulation by embryonic day 7.5. The robust and similar single knockout phenotypes are somewhat surprising given there are over 70 MRPs and suggest little functional redundancy. Metabolic analysis reveals that Mrp knockout embryos produce significantly less ATP than controls, indicating compromised mitochondrial function. Histological and immunofluorescence analyses indicate abnormal organelle morphology and stalling at the G2/M checkpoint in Mrp null cells. The nearly identical pre-gastrulation phenotype observed for many different nuclear-encoded mitochondrial protein knockouts hints that distinct energy systems are crucial at specific time points during mammalian development.
Collapse
Affiliation(s)
- Agnes Cheong
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA
| | - Danielle Archambault
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA
| | - Rinat Degani
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA
| | - Elizabeth Iverson
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA
| | - Kimberly D Tremblay
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA
| | - Jesse Mager
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA
| |
Collapse
|
17
|
Do Y, Matsuda S, Inatomi T, Nakada K, Yasukawa T, Kang D. The accessory subunit of human DNA polymerase γ is required for mitochondrial DNA maintenance and is able to stabilize the catalytic subunit. Mitochondrion 2020; 53:133-139. [PMID: 32470614 DOI: 10.1016/j.mito.2020.05.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 05/18/2020] [Accepted: 05/22/2020] [Indexed: 01/10/2023]
Abstract
Human DNA polymerase γ (POLG) is a mitochondria-specific replicative DNA polymerase consisting of a single catalytic subunit, POLGα, and a dimeric accessory subunit, POLGβ. To gain a deeper understanding of the role of POLGβ, we knocked out this protein in cultured human cybrid cells and established numerous knockout clones. POLGβ-knockout clones presented a clear phenotype of mitochondrial DNA loss, indicating that POLGβ is necessary for mitochondrial DNA replication. Moreover, POLGβ-knockout cells showed a severe decrease in POLGα levels and acute suppression of POLGβ expression efficiently down-regulated POLGα levels. These results suggest that, in addition to its role as the processivity factor of POLG, POLGβ acts as a POLGα stabilizer, an important role for POLGβ in mitochondrial DNA maintenance.
Collapse
Affiliation(s)
- Yura Do
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Shigeru Matsuda
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Teppei Inatomi
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Kazuto Nakada
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba-shi, Ibaraki, 305-8572, Japan
| | - Takehiro Yasukawa
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan.
| | - Dongchon Kang
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| |
Collapse
|
18
|
Dosekova P, Dubiel A, Karlowicz A, Zietkiewicz S, Rydzanicz M, Habalova V, Pienkowski VM, Skirkova M, Han V, Mosejova A, Gdovinova Z, Kaliszewska M, Tońska K, Szymanski MR, Skorvanek M, Ploski R. Whole exome sequencing identifies a homozygous POLG2 missense variant in an adult patient presenting with optic atrophy, movement disorders, premature ovarian failure and mitochondrial DNA depletion. Eur J Med Genet 2020; 63:103821. [PMID: 31778857 DOI: 10.1016/j.ejmg.2019.103821] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 11/09/2019] [Accepted: 11/24/2019] [Indexed: 12/31/2022]
Abstract
POLG2 associated disorders belong to the group of mitochondrial DNA (mtDNA) diseases and present with a heterogeneous clinical spectrum, various age of onset, and disease severity. We report a 39-year old female presenting with childhood-onset and progressive neuroophthalmic manifestation with optic atrophy, mixed polyneuropathy, spinal and cerebellar ataxia and generalized chorea associated with mtDNA depletion. Whole-exome sequencing identified an ultra-rare homozygous missense mutation located at Chr17: 062474101-C > A (p.Asp433Tyr) in nuclear POLG2 gene encoding PolγB, an accessory subunits of mitochondrial polymerase γ responsible for mtDNA replication. The healthy parents and 2 sisters of the patient were heterozygous for the variant. To our best knowledge, this is the first case of homozygous variant in the POLG2 gene resulting in mitochondrial depletion syndrome in an adult patient and its clinical manifestations extend the clinical spectrum of POLG2 associated diseases.
Collapse
Affiliation(s)
- Petra Dosekova
- Dept. of Neurology, P.J. Safarik University, Kosice, Slovakia; Dept. of Neurology, University Hospital L. Pasteur, Kosice, Slovakia.
| | - Andrzej Dubiel
- Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Anna Karlowicz
- Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Szymon Zietkiewicz
- Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | | | - Viera Habalova
- Dept. of Medical Biology, P. J. Safarik University, Kosice, Slovakia
| | - Victor Murcia Pienkowski
- Dept. of Medical Genetics, Medical University of Warsaw, Warsaw, Poland; Postgraduate School of Molecular Medicine, Medical University of Warsaw, Warsaw, Poland
| | - Miriam Skirkova
- Dept. of Ophtalmology, P. J. Safarik University and University Hospital L. Pasteur, Kosice, Slovakia
| | - Vladimir Han
- Dept. of Neurology, P.J. Safarik University, Kosice, Slovakia; Dept. of Neurology, University Hospital L. Pasteur, Kosice, Slovakia
| | - Alexandra Mosejova
- Dept. of Neurology, P.J. Safarik University, Kosice, Slovakia; Dept. of Neurology, University Hospital L. Pasteur, Kosice, Slovakia
| | - Zuzana Gdovinova
- Dept. of Neurology, P.J. Safarik University, Kosice, Slovakia; Dept. of Neurology, University Hospital L. Pasteur, Kosice, Slovakia
| | - Magdalena Kaliszewska
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Katarzyna Tońska
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Michal R Szymanski
- Intercollegiate Faculty of Biotechnology of the University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Matej Skorvanek
- Dept. of Neurology, P.J. Safarik University, Kosice, Slovakia; Dept. of Neurology, University Hospital L. Pasteur, Kosice, Slovakia
| | - Rafal Ploski
- Dept. of Medical Genetics, Medical University of Warsaw, Warsaw, Poland.
| |
Collapse
|
19
|
Patient-specific neural progenitor cells derived from induced pluripotent stem cells offer a promise of good models for mitochondrial disease. Cell Tissue Res 2020; 380:15-30. [PMID: 31925525 DOI: 10.1007/s00441-019-03164-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 12/19/2019] [Indexed: 02/06/2023]
Abstract
Mitochondria are the primary generators of ATP in eukaryotic cells through the process of oxidative phosphorylation. Mitochondria are also involved in several other important cellular functions including regulation of intracellular Ca2+, cell signaling and apoptosis. Mitochondrial dysfunction causes disease and since it is not possible to perform repeated studies in humans, models are essential to enable us to investigate the mechanisms involved. Recently, the discovery of induced pluripotent stem cells (iPSCs), made by reprogramming adult somatic cells (Takahashi and Yamanaka 2006; Yamanaka and Blau 2010), has provided a unique opportunity for studying aspects of disease mechanisms in patient-specific cells and tissues. Reprogramming cells to neuronal lineage such as neural progenitor cells (NPCs) generated from the neural induction of reprogrammed iPSCs can thus provide a useful model for investigating neurological disease mechanisms including those caused by mitochondrial dysfunction. In addition, NPCs display a huge clinical potential in drug screening and therapeutics.
Collapse
|
20
|
Kotrys AV, Cysewski D, Czarnomska SD, Pietras Z, Borowski LS, Dziembowski A, Szczesny RJ. Quantitative proteomics revealed C6orf203/MTRES1 as a factor preventing stress-induced transcription deficiency in human mitochondria. Nucleic Acids Res 2019; 47:7502-7517. [PMID: 31226201 PMCID: PMC6698753 DOI: 10.1093/nar/gkz542] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 06/05/2019] [Accepted: 06/13/2019] [Indexed: 12/18/2022] Open
Abstract
Maintenance of mitochondrial gene expression is crucial for cellular homeostasis. Stress conditions may lead to a temporary reduction of mitochondrial genome copy number, raising the risk of insufficient expression of mitochondrial encoded genes. Little is known how compensatory mechanisms operate to maintain proper mitochondrial transcripts levels upon disturbed transcription and which proteins are involved in them. Here we performed a quantitative proteomic screen to search for proteins that sustain expression of mtDNA under stress conditions. Analysis of stress-induced changes of the human mitochondrial proteome led to the identification of several proteins with poorly defined functions among which we focused on C6orf203, which we named MTRES1 (Mitochondrial Transcription Rescue Factor 1). We found that the level of MTRES1 is elevated in cells under stress and we show that this upregulation of MTRES1 prevents mitochondrial transcript loss under perturbed mitochondrial gene expression. This protective effect depends on the RNA binding activity of MTRES1. Functional analysis revealed that MTRES1 associates with mitochondrial RNA polymerase POLRMT and acts by increasing mitochondrial transcription, without changing the stability of mitochondrial RNAs. We propose that MTRES1 is an example of a protein that protects the cell from mitochondrial RNA loss during stress.
Collapse
Affiliation(s)
- Anna V Kotrys
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Dominik Cysewski
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Sylwia D Czarnomska
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Zbigniew Pietras
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw 02-106, Poland.,Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw 02-109, Poland
| | - Lukasz S Borowski
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw 02-106, Poland.,Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Warsaw 02-106, Poland
| | - Andrzej Dziembowski
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw 02-106, Poland.,Faculty of Biology, Institute of Genetics and Biotechnology, University of Warsaw, Warsaw 02-106, Poland
| | - Roman J Szczesny
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw 02-106, Poland
| |
Collapse
|
21
|
Young MJ, Jayaprakash AD, Young CKJ. Analysis of Mitochondrial DNA Polymorphisms in the Human Cell Lines HepaRG and SJCRH30. Int J Mol Sci 2019; 20:ijms20133245. [PMID: 31269646 PMCID: PMC6651321 DOI: 10.3390/ijms20133245] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/26/2019] [Accepted: 07/01/2019] [Indexed: 12/11/2022] Open
Abstract
The mitochondrial DNA (mtDNA) sequences of two commonly used human cell lines, HepaRG and SJCRH30, were determined. HepaRG originates from a liver tumor obtained from a patient with hepatocarcinoma and hepatitis C while SJCRH30 originates from a rhabdomyosarcoma patient tumor. In comparison to the revised Cambridge Reference Sequence, HepaRG and SJCRH30 mtDNA each contain 14 nucleotide variations. In addition to an insertion of a cytosine at position 315 (315insC), the mtDNA sequences from both cell types share six common polymorphisms. Heteroplasmic variants were identified in both cell types and included the identification of the 315insC mtDNA variant at 42 and 75% heteroplasmy in HepaRG and SJCRH30, respectively. Additionally, a novel heteroplasmic G13633A substitution in the HepaRG ND5 gene was detected at 33%. Previously reported cancer-associated mtDNA variants T195C and T16519C were identified in SJCRH30, both at homoplasmy (100%), while HepaRG mtDNA harbors a known prostate cancer-associated T6253C substitution at near homoplasmy, 95%. Based on our sequencing analysis, HepaRG mtDNA is predicted to lie within haplogroup branch H15a1 while SJCRH30 mtDNA is predicted to localize to H27c. The catalog of polymorphisms and heteroplasmy reported here should prove useful for future investigations of mtDNA maintenance in HepaRG and SJCRH30 cell lines.
Collapse
Affiliation(s)
- Matthew J Young
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901, USA.
| | | | - Carolyn K J Young
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901, USA
| |
Collapse
|
22
|
Affiliation(s)
- Qiancong Zhao
- 1 Department of Cardiovascular Surgery The Second Hospital of Jilin University Changchun China.,3 Department of Genetics The University of Alabama at Birmingham AL
| | - Qianchuang Sun
- 2 Department of Anesthesiology The Second Hospital of Jilin University Changchun China.,3 Department of Genetics The University of Alabama at Birmingham AL
| | - Lufang Zhou
- 4 Department of Medicine The University of Alabama at Birmingham AL
| | - Kexiang Liu
- 1 Department of Cardiovascular Surgery The Second Hospital of Jilin University Changchun China
| | - Kai Jiao
- 3 Department of Genetics The University of Alabama at Birmingham AL
| |
Collapse
|
23
|
Silva Ramos E, Motori E, Brüser C, Kühl I, Yeroslaviz A, Ruzzenente B, Kauppila JHK, Busch JD, Hultenby K, Habermann BH, Jakobs S, Larsson NG, Mourier A. Mitochondrial fusion is required for regulation of mitochondrial DNA replication. PLoS Genet 2019; 15:e1008085. [PMID: 31170154 PMCID: PMC6553695 DOI: 10.1371/journal.pgen.1008085] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/11/2019] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial dynamics is an essential physiological process controlling mitochondrial content mixing and mobility to ensure proper function and localization of mitochondria at intracellular sites of high-energy demand. Intriguingly, for yet unknown reasons, severe impairment of mitochondrial fusion drastically affects mtDNA copy number. To decipher the link between mitochondrial dynamics and mtDNA maintenance, we studied mouse embryonic fibroblasts (MEFs) and mouse cardiomyocytes with disruption of mitochondrial fusion. Super-resolution microscopy revealed that loss of outer mitochondrial membrane (OMM) fusion, but not inner mitochondrial membrane (IMM) fusion, leads to nucleoid clustering. Remarkably, fluorescence in situ hybridization (FISH), bromouridine labeling in MEFs and assessment of mitochondrial transcription in tissue homogenates revealed that abolished OMM fusion does not affect transcription. Furthermore, the profound mtDNA depletion in mouse hearts lacking OMM fusion is not caused by defective integrity or increased mutagenesis of mtDNA, but instead we show that mitochondrial fusion is necessary to maintain the stoichiometry of the protein components of the mtDNA replisome. OMM fusion is necessary for proliferating MEFs to recover from mtDNA depletion and for the marked increase of mtDNA copy number during postnatal heart development. Our findings thus link OMM fusion to replication and distribution of mtDNA. Mammalian mitochondria contain multiple copies of the mitochondrial genome (mtDNA), which encodes genes that are essential for the oxidative phosphorylation system. An important feature of mtDNA is that it is evenly distributed throughout the mitochondrial network. Dynamin-related GTPase proteins help control the size and shape of mitochondria by fusion and fission events and are intimately linked to maintenance and distribution of mtDNA. Certain human mutations in mitofusin 2 (MFN2) and optic atrophy protein 1 (OPA1) cause disease phenotypes, such as peripheral neuropathy and optic atrophy, which are often also associated with mtDNA depletion. However, the mechanism whereby MFNs and OPA1 are involved in maintenance of mtDNA is unclear. In this study, we demonstrate that rapid mtDNA synthesis in proliferating tissue-culture cells or cardiomyocytes during post-natal heart development requires mitochondrial fusion. However, the absence of mitochondrial fusion in mouse heart is not associated with mtDNA integrity defects but instead affects the replication of mtDNA. These findings provide direct evidence for the importance of mitochondrial fusion in maintaining mtDNA replication.
Collapse
Affiliation(s)
- Eduardo Silva Ramos
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Elisa Motori
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Christian Brüser
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Inge Kühl
- Institute of Integrative Biology of the Cell (I2BC) UMR9198, CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Assa Yeroslaviz
- Computational Systems Biochemistry, Bioinformatics Core Facility, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Benedetta Ruzzenente
- INSERM U1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, Paris, France
| | - Johanna H. K. Kauppila
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Jakob D. Busch
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Kjell Hultenby
- Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | | | - Stefan Jakobs
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- * E-mail: (NGL); (AM)
| | - Arnaud Mourier
- Université de Bordeaux, IBGC UMR 5095, Bordeaux, France
- CNRS, IBGC CNRS UMR 5095, Bordeaux, France
- * E-mail: (NGL); (AM)
| |
Collapse
|
24
|
Wheeler JH, Young CKJ, Young MJ. Analysis of Human Mitochondrial DNA Content by Southern Blotting and Nonradioactive Probe Hybridization. CURRENT PROTOCOLS IN TOXICOLOGY 2019; 80:e75. [PMID: 30982231 PMCID: PMC6581606 DOI: 10.1002/cptx.75] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A single cell can contain several thousand copies of the mitochondrial DNA genome or mtDNA. Tools for assessing mtDNA content are necessary for clinical and toxicological research, as mtDNA depletion is linked to genetic disease and drug toxicity. For instance, mtDNA depletion syndromes are typically fatal childhood disorders that are characterized by severe declines in mtDNA content in affected tissues. Mitochondrial toxicity and mtDNA depletion have also been reported in human immunodeficiency virus-infected patients treated with certain nucleoside reverse transcriptase inhibitors. Further, cell culture studies have demonstrated that exposure to oxidative stress stimulates mtDNA degradation. Here we outline a Southern blot and nonradioactive digoxigenin-labeled probe hybridization method to estimate mtDNA content in human genomic DNA samples. © 2019 by John Wiley & Sons, Inc.
Collapse
Affiliation(s)
- Joel H. Wheeler
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901
| | - Carolyn K. J. Young
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901
| | - Matthew J. Young
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901
| |
Collapse
|
25
|
Gorvin CM, Ahmad BN, Stechman MJ, Loh NY, Hough TA, Leo P, Marshall M, Sethi S, Bentley L, Piret SE, Reed A, Jeyabalan J, Christie PT, Wells S, Simon MM, Mallon AM, Schulz H, Huebner N, Brown MA, Cox RD, Brown SD, Thakker RV. An N-Ethyl-N-Nitrosourea (ENU)-Induced Tyr265Stop Mutation of the DNA Polymerase Accessory Subunit Gamma 2 (Polg2) Is Associated With Renal Calcification in Mice. J Bone Miner Res 2019; 34:497-507. [PMID: 30395686 PMCID: PMC6446808 DOI: 10.1002/jbmr.3624] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 10/12/2018] [Accepted: 10/28/2018] [Indexed: 12/24/2022]
Abstract
Renal calcification (RCALC) resulting in nephrolithiasis and nephrocalcinosis, which affects ∼10% of adults by 70 years of age, involves environmental and genetic etiologies. Thus, nephrolithiasis and nephrocalcinosis occurs as an inherited disorder in ∼65% of patients, and may be associated with endocrine and metabolic disorders including: primary hyperparathyroidism, hypercalciuria, renal tubular acidosis, cystinuria, and hyperoxaluria. Investigations of families with nephrolithiasis and nephrocalcinosis have identified some causative genes, but further progress is limited as large families are unavailable for genetic studies. We therefore embarked on establishing mouse models for hereditary nephrolithiasis and nephrocalcinosis by performing abdominal X-rays to identify renal opacities in N-ethyl-N-nitrosourea (ENU)-mutagenized mice. This identified a mouse with RCALC inherited as an autosomal dominant trait, designated RCALC type 2 (RCALC2). Genomewide mapping located the Rcalc2 locus to a ∼16-Mbp region on chromosome 11D-E2 and whole-exome sequence analysis identified a heterozygous mutation in the DNA polymerase gamma-2, accessory subunit (Polg2) resulting in a nonsense mutation, Tyr265Stop (Y265X), which co-segregated with RCALC2. Kidneys of mutant mice (Polg2+/Y265X ) had lower POLG2 mRNA and protein expression, compared to wild-type littermates (Polg2+/+ ). The Polg2+/Y265X and Polg2+/+ mice had similar plasma concentrations of sodium, potassium, calcium, phosphate, chloride, urea, creatinine, glucose, and alkaline phosphatase activity; and similar urinary fractional excretion of calcium, phosphate, oxalate, and protein. Polg2 encodes the minor subunit of the mitochondrial DNA (mtDNA) polymerase and the mtDNA content in Polg2+/Y265X kidneys was reduced compared to Polg2+/+ mice, and cDNA expression profiling revealed differential expression of 26 genes involved in several biological processes including mitochondrial DNA function, apoptosis, and ubiquitination, the complement pathway, and inflammatory pathways. In addition, plasma of Polg2+/Y265X mice, compared to Polg2+/+ littermates had higher levels of reactive oxygen species. Thus, our studies have identified a mutant mouse model for inherited renal calcification associated with a Polg2 nonsense mutation. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Caroline M Gorvin
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Bushra N Ahmad
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Michael J Stechman
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Nellie Y Loh
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Tertius A Hough
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council, Harwell, UK
| | - Paul Leo
- Translational Genomics Group, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology at Translational Research Institute, Brisbane, Australia
| | - Mhairi Marshall
- Translational Genomics Group, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology at Translational Research Institute, Brisbane, Australia
| | - Siddharth Sethi
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council, Harwell, UK
| | - Liz Bentley
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council, Harwell, UK
| | - Sian E Piret
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Anita Reed
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Jeshmi Jeyabalan
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Paul T Christie
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Sara Wells
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council, Harwell, UK
| | - Michelle M Simon
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council, Harwell, UK
| | - Ann-Marie Mallon
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council, Harwell, UK
| | - Herbert Schulz
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | | | - Matthew A Brown
- Translational Genomics Group, Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology at Translational Research Institute, Brisbane, Australia
| | - Roger D Cox
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council, Harwell, UK
| | - Steve D Brown
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council, Harwell, UK
| | - Rajesh V Thakker
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| |
Collapse
|
26
|
González de Cózar JM, Gerards M, Teeri E, George J, Dufour E, Jacobs HT, Jõers P. RNase H1 promotes replication fork progression through oppositely transcribed regions of Drosophila mitochondrial DNA. J Biol Chem 2019; 294:4331-4344. [PMID: 30635398 PMCID: PMC6433063 DOI: 10.1074/jbc.ra118.007015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/09/2019] [Indexed: 11/12/2022] Open
Abstract
Mitochondrial DNA (mtDNA) replication uses a simple core machinery similar to those of bacterial viruses and plasmids, but its components are challenging to unravel. Here, we found that, as in mammals, the single Drosophila gene for RNase H1 (rnh1) has alternative translational start sites, resulting in two polypeptides, targeted to either mitochondria or the nucleus. RNAi-mediated rnh1 knockdown did not influence growth or viability of S2 cells, but compromised mtDNA integrity and copy number. rnh1 knockdown in intact flies also produced a phenotype of impaired mitochondrial function, characterized by respiratory chain deficiency, locomotor dysfunction, and decreased lifespan. Its overexpression in S2 cells resulted in cell lethality after 5–9 days, attributable to the nuclearly localized isoform. rnh1 knockdown and overexpression produced opposite effects on mtDNA replication intermediates. The most pronounced effects were seen in genome regions beyond the major replication pauses where the replication fork needs to progress through a gene cluster that is transcribed in the opposite direction. RNase H1 deficiency led to an accumulation of replication intermediates in these zones, abundant mtDNA molecules joined by four-way junctions, and species consistent with fork regression from the origin. These findings indicate replication stalling due to the presence of unprocessed RNA/DNA heteroduplexes, potentially leading to the degradation of collapsed forks or to replication restart by a mechanism involving strand invasion. Both mitochondrial RNA and DNA syntheses were affected by rnh1 knockdown, suggesting that RNase H1 also plays a role in integrating or coregulating these processes in Drosophila mitochondria.
Collapse
Affiliation(s)
- Jose M González de Cózar
- From the Faculty of Medicine and Health Technology and Tampere University Hospital, FI-33014 Tampere University, Finland
| | - Mike Gerards
- From the Faculty of Medicine and Health Technology and Tampere University Hospital, FI-33014 Tampere University, Finland
| | - Eveliina Teeri
- From the Faculty of Medicine and Health Technology and Tampere University Hospital, FI-33014 Tampere University, Finland
| | - Jack George
- From the Faculty of Medicine and Health Technology and Tampere University Hospital, FI-33014 Tampere University, Finland
| | - Eric Dufour
- From the Faculty of Medicine and Health Technology and Tampere University Hospital, FI-33014 Tampere University, Finland
| | - Howard T Jacobs
- From the Faculty of Medicine and Health Technology and Tampere University Hospital, FI-33014 Tampere University, Finland, .,Institute of Biotechnology, FI-00014 University of Helsinki, Finland, and
| | - Priit Jõers
- From the Faculty of Medicine and Health Technology and Tampere University Hospital, FI-33014 Tampere University, Finland.,Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
| |
Collapse
|
27
|
Hoff KE, DeBalsi KL, Sanchez-Quintero MJ, Longley MJ, Hirano M, Naini AB, Copeland WC. Characterization of the human homozygous R182W POLG2 mutation in mitochondrial DNA depletion syndrome. PLoS One 2018; 13:e0203198. [PMID: 30157269 PMCID: PMC6114919 DOI: 10.1371/journal.pone.0203198] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 08/14/2018] [Indexed: 12/18/2022] Open
Abstract
Mutations in mitochondrial DNA (mtDNA) have been linked to a variety of metabolic, neurological and muscular diseases which can present at any time throughout life. MtDNA is replicated by DNA polymerase gamma (Pol γ), twinkle helicase and mitochondrial single-stranded binding protein (mtSSB). The Pol γ holoenzyme is a heterotrimer consisting of the p140 catalytic subunit and a p55 homodimeric accessory subunit encoded by the nuclear genes POLG and POLG2, respectively. The accessory subunits enhance DNA binding and promote processive DNA synthesis of the holoenzyme. Mutations in either POLG or POLG2 are linked to disease and adversely affect maintenance of the mitochondrial genome, resulting in depletion, deletions and/or point mutations in mtDNA. A homozygous mutation located at Chr17: 62492543G>A in POLG2, resulting in R182W substitution in p55, was previously identified to cause mtDNA depletion and fatal hepatic liver failure. Here we characterize this homozygous R182W p55 mutation using in vivo cultured cell models and in vitro biochemical assessments. Compared to control fibroblasts, homozygous R182W p55 primary dermal fibroblasts exhibit a two-fold slower doubling time, reduced mtDNA copy number and reduced levels of POLG and POLG2 transcripts correlating with the reported disease state. Expression of R182W p55 in HEK293 cells impairs oxidative-phosphorylation. Biochemically, R182W p55 displays DNA binding and association with p140 similar to WT p55. R182W p55 mimics the ability of WT p55 to stimulate primer extension, support steady-state nucleotide incorporation, and suppress the exonuclease function of Pol γin vitro. However, R182W p55 has severe defects in protein stability as determined by differential scanning fluorimetry and in stimulating function as determined by thermal inactivation. These data demonstrate that the Chr17: 62492543G>A mutation in POLG2, R182W p55, severely impairs stability of the accessory subunit and is the likely cause of the disease phenotype.
Collapse
Affiliation(s)
- Kirsten E. Hoff
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC, United States of America
| | - Karen L. DeBalsi
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC, United States of America
| | - Maria J. Sanchez-Quintero
- Department of Neurology, H. Houston Merritt Neuromuscular Research Center, Columbia University Medical Center, New York, NY, United States of America
| | - Matthew J. Longley
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC, United States of America
| | - Michio Hirano
- Department of Neurology, H. Houston Merritt Neuromuscular Research Center, Columbia University Medical Center, New York, NY, United States of America
| | - Ali B. Naini
- Department of Neurology, H. Houston Merritt Neuromuscular Research Center, Columbia University Medical Center, New York, NY, United States of America
- Department of Pathology and Cell Biology, Columbia University, New York, NY, United States of America
- Division of Personalized Genomic Medicine, Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, United States of America
| | - William C. Copeland
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, DHHS, Research Triangle Park, NC, United States of America
- * E-mail:
| |
Collapse
|
28
|
Mitochondrial DNA replication in mammalian cells: overview of the pathway. Essays Biochem 2018; 62:287-296. [PMID: 29880722 PMCID: PMC6056714 DOI: 10.1042/ebc20170100] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 12/27/2022]
Abstract
Mammalian mitochondria contain multiple copies of a circular, double-stranded DNA genome and a dedicated DNA replication machinery is required for its maintenance. Many disease-causing mutations affect mitochondrial replication factors and a detailed understanding of the replication process may help to explain the pathogenic mechanisms underlying a number of mitochondrial diseases. We here give a brief overview of DNA replication in mammalian mitochondria, describing our current understanding of this process and some unanswered questions remaining.
Collapse
|
29
|
Prasad R, Çağlayan M, Dai DP, Nadalutti CA, Zhao ML, Gassman NR, Janoshazi AK, Stefanick DF, Horton JK, Krasich R, Longley MJ, Copeland WC, Griffith JD, Wilson SH. DNA polymerase β: A missing link of the base excision repair machinery in mammalian mitochondria. DNA Repair (Amst) 2017; 60:77-88. [PMID: 29100041 PMCID: PMC5919216 DOI: 10.1016/j.dnarep.2017.10.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mitochondrial genome integrity is fundamental to mammalian cell viability. Since mitochondrial DNA is constantly under attack from oxygen radicals released during ATP production, DNA repair is vital in removing oxidatively generated lesions in mitochondrial DNA, but the presence of a strong base excision repair system has not been demonstrated. Here, we addressed the presence of such a system in mammalian mitochondria involving the primary base lesion repair enzyme DNA polymerase (pol) β. Pol β was localized to mammalian mitochondria by electron microscopic-immunogold staining, immunofluorescence co-localization and biochemical experiments. Extracts from purified mitochondria exhibited base excision repair activity that was dependent on pol β. Mitochondria from pol β-deficient mouse fibroblasts had compromised DNA repair and showed elevated levels of superoxide radicals after hydrogen peroxide treatment. Mitochondria in pol β-deficient fibroblasts displayed altered morphology by electron microscopy. These results indicate that mammalian mitochondria contain an efficient base lesion repair system mediated in part by pol β and thus pol β plays a role in preserving mitochondrial genome stability.
Collapse
Affiliation(s)
- Rajendra Prasad
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | - Melike Çağlayan
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | - Da-Peng Dai
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | - Cristina A Nadalutti
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Ming-Lang Zhao
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | - Natalie R Gassman
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA; University of South Alabama Mitchell Cancer Institute, 1660 Springhill Ave, Mobile, AL 36604, USA
| | - Agnes K Janoshazi
- Signal Transduction Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | - Donna F Stefanick
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | - Julie K Horton
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | - Rachel Krasich
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | - Matthew J Longley
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA
| | - Jack D Griffith
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Samuel H Wilson
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, P.O. Box 12233, Research Triangle Park, NC 27709, USA.
| |
Collapse
|
30
|
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.
Collapse
Affiliation(s)
- Matthew J Young
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL, United States
| |
Collapse
|
31
|
Chan SSL. Inherited mitochondrial genomic instability and chemical exposures. Toxicology 2017; 391:75-83. [PMID: 28756246 DOI: 10.1016/j.tox.2017.07.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/12/2017] [Accepted: 07/24/2017] [Indexed: 12/21/2022]
Abstract
There are approximately 1500 proteins that are needed for mitochondrial structure and function, most of which are encoded in the nuclear genome (Calvo et al., 2006). Each mitochondrion has its own genome (mtDNA), which in humans encodes 13 polypeptides, 22 tRNAs and 2 rRNAs required for oxidative phosphorylation. The mitochondrial genome of humans and most vertebrates is approximately 16.5kbp, double-stranded, circular, with few non-coding bases. Thus, maintaining mtDNA stability, that is, the ability of the cell to maintain adequate levels of mtDNA template for oxidative phosphorylation is essential and can be impacted by the level of mtDNA mutation currently within the cell or mitochondrion, but also from errors made during normal mtDNA replication, defects in mitochondrial quality control mechanisms, and exacerbated by exposures to exogenous and/or endogenous genotoxic agents. In this review, we expand on the origins and consequences of mtDNA instability, the current state of research regarding the mechanisms by which mtDNA instability can be overcome by cellular and chemical interventions, and the future of research and treatments for mtDNA instability.
Collapse
Affiliation(s)
- Sherine S L Chan
- Drug Discovery and Biomedical Sciences, College of Pharmacy, Medical University of South Carolina, Charleston, SC 29425, United States; Neuroene Therapeutics, Mt. Pleasant, SC 29464, United States.
| |
Collapse
|
32
|
Ren L, Zhang C, Tao L, Hao J, Tan K, Miao K, Yu Y, Sui L, Wu Z, Tian J, An L. High-resolution profiles of gene expression and DNA methylation highlight mitochondrial modifications during early embryonic development. J Reprod Dev 2017; 63:247-261. [PMID: 28367907 PMCID: PMC5481627 DOI: 10.1262/jrd.2016-168] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Well-organized mitochondrial functions and dynamics are critical for early embryonic development and are operated via a large number of mitochondria-related genes (MtGs) encoded by both the nuclear and the mitochondrial genome.
However, the mechanisms underlying mitochondrial modifications during the critical window between blastocyst implantation and postimplantation organogenesis are poorly understood. Herein, we performed high-resolution dynamic
profiling of MtGs to acquire a more detailed understanding of mitochondrial modifications during early development. Our data suggest that the resumption of mitochondrial mass growth is not only facilitated by increased
mitochondrial biogenesis and mitochondrial DNA (mtDNA) replication, but also by the appropriate balance between mitochondrial fission and fusion. In addition, increased levels of reactive oxygen species (ROS) resulting from
enhanced mitochondrial functions may be the critical inducer for activating the glutathione (GSH)-based stress response system in early embryos. The appropriate balance between the mitochondrial stress response and apoptosis
appears to be significant for cell differentiation and early organogenesis. Furthermore, we found that most MtGs undergo de novo promoter methylation, which may have functional consequences on mitochondrial
functions and dynamics during early development. We also report that mtDNA methylation can be observed as early as soon after implantation. DNMT1, the predominant enzyme for maintaining DNA methylation, localized to the
mitochondria and bound to mtDNA by the implantation stage. Our study provides a new insight into the involvement of mitochondria in early mammalian embryogenesis. We also propose that the epigenetic modifications during early
development are significant for modulating mitochondrial functions and dynamics.
Collapse
Affiliation(s)
- Likun Ren
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| | - Chao Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| | - Li Tao
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| | - Jing Hao
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| | - Kun Tan
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| | - Kai Miao
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| | - Yong Yu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| | - Linlin Sui
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| | - Zhonghong Wu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| | - Jianhui Tian
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| | - Lei An
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P. R. China
| |
Collapse
|
33
|
Wang T, Zhang M, Jiang Z, Seli E. Mitochondrial dysfunction and ovarian aging. Am J Reprod Immunol 2017; 77. [PMID: 28194828 DOI: 10.1111/aji.12651] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 01/17/2017] [Indexed: 01/02/2023] Open
Abstract
Mitochondria are double-membrane-bound organelles that are responsible for the generation of most of the cell's energy. Mitochondrial dysfunction has been implicated in cellular senescence in general and ovarian aging in particular. Recent studies exploited this association by studying mitochondrial DNA (mtDNA) copy number as a potential biomarker of embryo viability and the use of mitochondrial nutrients and autologous mitochondrial transfer as a potential treatment for poor ovarian function and response.
Collapse
Affiliation(s)
- Tianren Wang
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Man Zhang
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Zongliang Jiang
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Emre Seli
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| |
Collapse
|
34
|
DeBalsi KL, Hoff KE, Copeland WC. Role of the mitochondrial DNA replication machinery in mitochondrial DNA mutagenesis, aging and age-related diseases. Ageing Res Rev 2017; 33:89-104. [PMID: 27143693 DOI: 10.1016/j.arr.2016.04.006] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/19/2016] [Accepted: 04/19/2016] [Indexed: 12/19/2022]
Abstract
As regulators of bioenergetics in the cell and the primary source of endogenous reactive oxygen species (ROS), dysfunctional mitochondria have been implicated for decades in the process of aging and age-related diseases. Mitochondrial DNA (mtDNA) is replicated and repaired by nuclear-encoded mtDNA polymerase γ (Pol γ) and several other associated proteins, which compose the mtDNA replication machinery. Here, we review evidence that errors caused by this replication machinery and failure to repair these mtDNA errors results in mtDNA mutations. Clonal expansion of mtDNA mutations results in mitochondrial dysfunction, such as decreased electron transport chain (ETC) enzyme activity and impaired cellular respiration. We address the literature that mitochondrial dysfunction, in conjunction with altered mitochondrial dynamics, is a major driving force behind aging and age-related diseases. Additionally, interventions to improve mitochondrial function and attenuate the symptoms of aging are examined.
Collapse
Affiliation(s)
- Karen L DeBalsi
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Kirsten E Hoff
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
| |
Collapse
|
35
|
Krasich R, Copeland WC. DNA polymerases in the mitochondria: A critical review of the evidence. FRONT BIOSCI-LANDMRK 2017; 22:692-709. [PMID: 27814640 PMCID: PMC5485829 DOI: 10.2741/4510] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Since 1970, the DNA polymerase gamma (PolG) has been known to be the DNA polymerase responsible for replication and repair of mitochondrial DNA, and until recently it was generally accepted that this was the only polymerase present in mitochondria. However, recent data has challenged that opinion, as several polymerases are now proposed to have activity in mitochondria. To date, their exact role of these other DNA polymerases is unclear and the amount of evidence supporting their role in mitochondria varies greatly. Further complicating matters, no universally accepted standards have been set for definitive proof of the mitochondrial localization of a protein. To gain an appreciation of these newly proposed DNA polymerases in the mitochondria, we review the evidence and standards needed to establish the role of a polymerase in the mitochondria. Employing PolG as an example, we established a list of criteria necessary to verify the existence and function of new mitochondrial proteins. We then apply this criteria towards several other putative mitochondrial polymerases. While there is still a lot left to be done in this exciting new direction, it is clear that PolG is not acting alone in mitochondria, opening new doors for potential replication and repair mechanisms.
Collapse
Affiliation(s)
- Rachel Krasich
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, 111 T.W. Alexander Dr., Bldg. 101, Rm. E316, Research Triangle Park, NC 27709,
| |
Collapse
|
36
|
Van Maldergem L, Besse A, De Paepe B, Blakely EL, Appadurai V, Humble MM, Piard J, Craig K, He L, Hella P, Debray FG, Martin JJ, Gaussen M, Laloux P, Stevanin G, Van Coster R, Taylor RW, Copeland WC, Mormont E, Bonnen PE. POLG2 deficiency causes adult-onset syndromic sensory neuropathy, ataxia and parkinsonism. Ann Clin Transl Neurol 2016; 4:4-14. [PMID: 28078310 PMCID: PMC5221457 DOI: 10.1002/acn3.361] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/09/2016] [Accepted: 08/12/2016] [Indexed: 01/06/2023] Open
Abstract
Objective Mitochondrial dysfunction plays a key role in the pathophysiology of neurodegenerative disorders such as ataxia and Parkinson's disease. We describe an extended Belgian pedigree where seven individuals presented with adult‐onset cerebellar ataxia, axonal peripheral ataxic neuropathy, and tremor, in variable combination with parkinsonism, seizures, cognitive decline, and ophthalmoplegia. We sought to identify the underlying molecular etiology and characterize the mitochondrial pathophysiology of this neurological syndrome. Methods Clinical, neurophysiological, and neuroradiological evaluations were conducted. Patient muscle and cultured fibroblasts underwent extensive analyses to assess mitochondrial function. Genetic studies including genome‐wide sequencing were conducted. Results Hallmarks of mitochondrial dysfunction were present in patients’ tissues including ultrastructural anomalies of mitochondria, mosaic cytochrome c oxidase deficiency, and multiple mtDNA deletions. We identified a splice acceptor variant in POLG2, c.970‐1G>C, segregating with disease in this family and associated with a concomitant decrease in levels of POLG2 protein in patient cells. Interpretation This work extends the clinical spectrum of POLG2 deficiency to include an overwhelming, adult‐onset neurological syndrome that includes cerebellar syndrome, peripheral neuropathy, tremor, and parkinsonism. We therefore suggest to include POLG2 sequencing in the evaluation of ataxia and sensory neuropathy in adults, especially when it is accompanied by tremor or parkinsonism with white matter disease. The demonstration that deletions of mtDNA resulting from autosomal‐dominant POLG2 variant lead to a monogenic neurodegenerative multicomponent syndrome provides further evidence for a major role of mitochondrial dysfunction in the pathomechanism of nonsyndromic forms of the component neurodegenerative disorders.
Collapse
Affiliation(s)
- Lionel Van Maldergem
- Centre de génétique humaine Université de Franche-Comté Besançon France; Metabolic Unit Centre of Human Genetics University Hospital Liège Belgium
| | - Arnaud Besse
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
| | - Boel De Paepe
- Department of Pediatrics Division of Child Neurology & Metabolism Ghent University Hospital Belgium
| | - Emma L Blakely
- Wellcome Trust Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne United Kingdom
| | - Vivek Appadurai
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
| | - Margaret M Humble
- Mitochondrial DNA Replication Group National Institute of Environmental Health Sciences Durham North Carolina
| | - Juliette Piard
- Centre de génétique humaine Université de Franche-Comté Besançon France
| | - Kate Craig
- Wellcome Trust Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne United Kingdom
| | - Langping He
- Wellcome Trust Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne United Kingdom
| | - Pierre Hella
- Department of Neurology Sambre and Meuse Regional Hospital Namur Belgium
| | | | | | - Marion Gaussen
- Inserm U1127 CNRS UMR 7225 Sorbonne Universités UPMC Paris France; Institut du Cerveau et de la Moelle épinière Hopital Pitié-Salpêtrière Paris France; Ecole Pratique des Hautes Etudes PSL Université Laboratoire de neurogénétique F-75013 Paris France
| | - Patrice Laloux
- Université catholique de Louvain CHU UCL Namur Department of Neurology B5530 Yvoir Belgium; UCL Institute of Neuroscience (IoNS) B1200 Brussels Belgium
| | - Giovanni Stevanin
- Inserm U1127 CNRS UMR 7225 Sorbonne Universités UPMC Paris France; Institut du Cerveau et de la Moelle épinière Hopital Pitié-Salpêtrière Paris France; Ecole Pratique des Hautes Etudes PSL Université Laboratoire de neurogénétique F-75013 Paris France
| | - Rudy Van Coster
- Department of Pediatrics Division of Child Neurology & Metabolism Ghent University Hospital Belgium
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research Institute of Neuroscience Newcastle University Newcastle upon Tyne United Kingdom
| | - William C Copeland
- Mitochondrial DNA Replication Group National Institute of Environmental Health Sciences Durham North Carolina
| | - Eric Mormont
- Université catholique de Louvain CHU UCL Namur Department of Neurology B5530 Yvoir Belgium; UCL Institute of Neuroscience (IoNS) B1200 Brussels Belgium
| | - Penelope E Bonnen
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
| |
Collapse
|
37
|
Varma H, Faust PL, Iglesias AD, Lagana SM, Wou K, Hirano M, DiMauro S, Mansukani MM, Hoff KE, Nagy PL, Copeland WC, Naini AB. Whole exome sequencing identifies a homozygous POLG2 missense variant in an infant with fulminant hepatic failure and mitochondrial DNA depletion. Eur J Med Genet 2016; 59:540-5. [PMID: 27592148 DOI: 10.1016/j.ejmg.2016.08.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 08/04/2016] [Accepted: 08/31/2016] [Indexed: 11/26/2022]
Abstract
Mitochondrial DNA (mtDNA) depletion syndrome manifests as diverse early-onset diseases that affect skeletal muscle, brain and liver function. Mutations in several nuclear DNA-encoded genes cause mtDNA depletion. We report on a patient, a 3-month-old boy who presented with hepatic failure, and was found to have severe mtDNA depletion in liver and muscle. Whole-exome sequencing identified a homozygous missense variant (c.544C > T, p.R182W) in the accessory subunit of mitochondrial DNA polymerase gamma (POLG2), which is required for mitochondrial DNA replication. This variant is predicted to disrupt a critical region needed for homodimerization of the POLG2 protein and cause loss of processive DNA synthesis. Both parents were phenotypically normal and heterozygous for this variant. Heterozygous mutations in POLG2 were previously associated with progressive external ophthalmoplegia and mtDNA deletions. This is the first report of a patient with a homozygous mutation in POLG2 and with a clinical presentation of severe hepatic failure and mitochondrial depletion.
Collapse
Affiliation(s)
- Hemant Varma
- Department of Pathology and Cell Biology, Columbia University, 630 W, 168th Street, New York, NY 10032, USA; Division of Personalized Genomic Medicine, Department of Pathology and Cell Biology, Columbia University Medical Center, USA
| | - Phyllis L Faust
- Department of Pathology and Cell Biology, Columbia University, 630 W, 168th Street, New York, NY 10032, USA
| | - Alejandro D Iglesias
- Division of Medical Genetics, Columbia University, New York Presbyterian Hospital, USA
| | - Stephen M Lagana
- Department of Pathology and Cell Biology, Columbia University, 630 W, 168th Street, New York, NY 10032, USA
| | - Karen Wou
- Division of Genetics, New York Presbyterian Hospital, USA
| | - Michio Hirano
- Department of Neurology, Columbia University Medical Center, USA
| | | | - Mahesh M Mansukani
- Department of Pathology and Cell Biology, Columbia University, 630 W, 168th Street, New York, NY 10032, USA; Division of Personalized Genomic Medicine, Department of Pathology and Cell Biology, Columbia University Medical Center, USA
| | - Kirsten E Hoff
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA
| | - Peter L Nagy
- Department of Pathology and Cell Biology, Columbia University, 630 W, 168th Street, New York, NY 10032, USA; Division of Personalized Genomic Medicine, Department of Pathology and Cell Biology, Columbia University Medical Center, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA.
| | - Ali B Naini
- Department of Pathology and Cell Biology, Columbia University, 630 W, 168th Street, New York, NY 10032, USA; Division of Personalized Genomic Medicine, Department of Pathology and Cell Biology, Columbia University Medical Center, USA.
| |
Collapse
|
38
|
Kühl I, Miranda M, Posse V, Milenkovic D, Mourier A, Siira SJ, Bonekamp NA, Neumann U, Filipovska A, Polosa PL, Gustafsson CM, Larsson NG. POLRMT regulates the switch between replication primer formation and gene expression of mammalian mtDNA. SCIENCE ADVANCES 2016; 2:e1600963. [PMID: 27532055 PMCID: PMC4975551 DOI: 10.1126/sciadv.1600963] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 07/01/2016] [Indexed: 05/27/2023]
Abstract
Mitochondria are vital in providing cellular energy via their oxidative phosphorylation system, which requires the coordinated expression of genes encoded by both the nuclear and mitochondrial genomes (mtDNA). Transcription of the circular mammalian mtDNA depends on a single mitochondrial RNA polymerase (POLRMT). Although the transcription initiation process is well understood, it is debated whether POLRMT also serves as the primase for the initiation of mtDNA replication. In the nucleus, the RNA polymerases needed for gene expression have no such role. Conditional knockout of Polrmt in the heart results in severe mitochondrial dysfunction causing dilated cardiomyopathy in young mice. We further studied the molecular consequences of different expression levels of POLRMT and found that POLRMT is essential for primer synthesis to initiate mtDNA replication in vivo. Furthermore, transcription initiation for primer formation has priority over gene expression. Surprisingly, mitochondrial transcription factor A (TFAM) exists in an mtDNA-free pool in the Polrmt knockout mice. TFAM levels remain unchanged despite strong mtDNA depletion, and TFAM is thus protected from degradation of the AAA(+) Lon protease in the absence of POLRMT. Last, we report that mitochondrial transcription elongation factor may compensate for a partial depletion of POLRMT in heterozygous Polrmt knockout mice, indicating a direct regulatory role of this factor in transcription. In conclusion, we present in vivo evidence that POLRMT has a key regulatory role in the replication of mammalian mtDNA and is part of a transcriptional mechanism that provides a switch between primer formation for mtDNA replication and mitochondrial gene expression.
Collapse
Affiliation(s)
- Inge Kühl
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Maria Miranda
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Viktor Posse
- Department of Medical Biochemistry and Cell Biology, Göteborgs Universitet, 40530 Göteborg, Sweden
| | - Dusanka Milenkovic
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Arnaud Mourier
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
- Université de Bordeaux and the Centre National de la Recherche Scientifique, Institut de Biochimie et Génétique Cellulaires UMR 5095, Saint-Saëns, F-33077 Bordeaux, France
| | - Stefan J. Siira
- Harry Perkins Institute of Medical Research, Centre for Medical Research and School of Chemistry and Biochemistry, The University of Western Australia, Perth 6009, Australia
| | - Nina A. Bonekamp
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Ulla Neumann
- Central Microscopy, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Aleksandra Filipovska
- Harry Perkins Institute of Medical Research, Centre for Medical Research and School of Chemistry and Biochemistry, The University of Western Australia, Perth 6009, Australia
| | - Paola Loguercio Polosa
- Department of Biosciences, Biotechnologies, and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy
| | - Claes M. Gustafsson
- Department of Medical Biochemistry and Cell Biology, Göteborgs Universitet, 40530 Göteborg, Sweden
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden
| |
Collapse
|
39
|
Young MJ, Copeland WC. Human mitochondrial DNA replication machinery and disease. Curr Opin Genet Dev 2016; 38:52-62. [PMID: 27065468 DOI: 10.1016/j.gde.2016.03.005] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/03/2016] [Accepted: 03/08/2016] [Indexed: 12/21/2022]
Abstract
The human mitochondrial genome is replicated by DNA polymerase γ in concert with key components of the mitochondrial DNA (mtDNA) replication machinery. Defects in mtDNA replication or nucleotide metabolism cause deletions, point mutations, or depletion of mtDNA. The resulting loss of cellular respiration ultimately induces mitochondrial genetic diseases, including mtDNA depletion syndromes (MDS) such as Alpers or early infantile hepatocerebral syndromes, and mtDNA deletion disorders such as progressive external ophthalmoplegia, ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy. Here we review the current literature regarding human mtDNA replication and heritable disorders caused by genetic changes of the POLG, POLG2, Twinkle, RNASEH1, DNA2, and MGME1 genes.
Collapse
Affiliation(s)
- Matthew J Young
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709, United States
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709, United States.
| |
Collapse
|
40
|
Abstract
Mammalian mitochondrial DNA (mtDNA) encodes 13 proteins that are essential for the function of the oxidative phosphorylation system, which is composed of four respiratory-chain complexes and adenosine triphosphate (ATP) synthase. Remarkably, the maintenance and expression of mtDNA depend on the mitochondrial import of hundreds of nuclear-encoded proteins that control genome maintenance, replication, transcription, RNA maturation, and mitochondrial translation. The importance of this complex regulatory system is underscored by the identification of numerous mutations of nuclear genes that impair mtDNA maintenance and expression at different levels, causing human mitochondrial diseases with pleiotropic clinical manifestations. The basic scientific understanding of the mechanisms controlling mtDNA function has progressed considerably during the past few years, thanks to advances in biochemistry, genetics, and structural biology. The challenges for the future will be to understand how mtDNA maintenance and expression are regulated and to what extent direct intramitochondrial cross talk between different processes, such as transcription and translation, is important.
Collapse
Affiliation(s)
- Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, 405 30 Gothenburg, Sweden; ,
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, 405 30 Gothenburg, Sweden; ,
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany; .,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| |
Collapse
|
41
|
Complementation between polymerase- and exonuclease-deficient mitochondrial DNA polymerase mutants in genomically engineered flies. Nat Commun 2015; 6:8808. [PMID: 26554610 PMCID: PMC4773887 DOI: 10.1038/ncomms9808] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/06/2015] [Indexed: 01/08/2023] Open
Abstract
Replication errors are the main cause of mitochondrial DNA (mtDNA) mutations and a compelling approach to decrease mutation levels would therefore be to increase the fidelity of the catalytic subunit (POLγA) of the mtDNA polymerase. Here we genomically engineer the tamas locus, encoding fly POLγA, and introduce alleles expressing exonuclease- (exo−) and polymerase-deficient (pol−) POLγA versions. The exo− mutant leads to accumulation of point mutations and linear deletions of mtDNA, whereas pol− mutants cause mtDNA depletion. The mutant tamas alleles are developmentally lethal but can complement each other in trans resulting in viable flies with clonally expanded mtDNA mutations. Reconstitution of human mtDNA replication in vitro confirms that replication is a highly dynamic process where POLγA goes on and off the template to allow complementation during proofreading and elongation. The created fly models are valuable tools to study germ line transmission of mtDNA and the pathophysiology of POLγA mutation disease. A key source of mitochondrial DNA mutations is errors introduced during genome replication. Here the authors create Drosophilia strains with separated elongation and proofreading capabilities to explore the dynamism of mitochondrial DNA replication.
Collapse
|
42
|
Ren L, Wang Z, An L, Zhang Z, Tan K, Miao K, Tao L, Cheng L, Zhang Z, Yang M, Wu Z, Tian J. Dynamic comparisons of high-resolution expression profiles highlighting mitochondria-related genes between in vivo and in vitro fertilized early mouse embryos. Hum Reprod 2015; 30:2892-911. [PMID: 26385791 DOI: 10.1093/humrep/dev228] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 08/24/2015] [Indexed: 12/11/2022] Open
Abstract
STUDY QUESTION Does in vitro fertilization (IVF) induce comprehensive and consistent changes in gene expression associated with mitochondrial biogenesis and function in mouse embryos from the pre- to post-implantation stage? SUMMARY ANSWER IVF-induced consistent mitochondrial dysfunction in early mouse embryos by altering the expression of a number of mitochondria-related genes. WHAT IS KNOWN ALREADY Although IVF is generally safe and successful for the treatment of human infertility, there is increasing evidence that those conceived by IVF suffer increased health risks. The mitochondrion is a multifunctional organelle that plays a crucial role in early development. We hypothesized that mitochondrial dysfunction is associated with increased IVF-induced embryonic defects and risks in offspring. STUDY DESIGN, SIZE, DURATION After either IVF and development (IVO groups as control) or IVF and culture (IVF groups), blastocysts were collected and transferred to pseudo-pregnant recipient mice. Both IVO and IVF embryos were sampled at E3.5, E7.5 and E10.5, and the expression profiles of mitochondria-related genes from the pre- to post-implantation stage were compared. PARTICIPANTS/MATERIALS, SETTING, METHODS ICR mice (5- to 6-week-old males and 8- to 9-week-old females) were used to generate IVO and IVF blastocysts. Embryo day (E) 3.5 blastocysts were transferred to pseudo-pregnant recipient mice. Both IVO and IVF embryos were sampled at E3.5, E7.5 and E10.5 for generating transcriptome data. Mitochondria-related genes were filtered for dynamic functional profiling. Mitochondrial dysfunctions indicated by bioinformatic analysis were further validated using cytological and molecular detection, morphometric and phenotypic analysis and integrated analysis with other high-throughput data. MAIN RESULTS AND THE ROLE OF CHANCE A total of 806, 795 and 753 mitochondria-related genes were significantly (P < 0.05) dysregulated in IVF embryos at E3.5, E7.5 and E10.5, respectively. Dynamic functional profiling, together with cytological and molecular investigations, indicated that IVF-induced mitochondrial dysfunctions mainly included: (i) inhibited mitochondrial biogenesis and impaired maintenance of DNA methylation of mitochondria-related genes during the post-implantation stage; (ii) dysregulated glutathione/glutathione peroxidase (GSH/Gpx) system and increased mitochondria-mediated apoptosis; (iii) disturbed mitochondrial β-oxidation, oxidative phosphorylation and amino acid metabolism; and (iv) disrupted mitochondrial transmembrane transport and membrane organization. We also demonstrated that some mitochondrial dysfunctions in IVF embryos, including impaired mitochondrial biogenesis, dysregulated GSH homeostasis and reactive oxygen species-induced apoptosis, can be rescued by treatment with melatonin, a mitochondria-targeted antioxidant, during in vitro culture. LIMITATIONS, REASONS FOR CAUTION Findings in mouse embryos and fetuses may not be fully transferable to humans. Further studies are needed to confirm these findings and to determine their clinical significance better. WIDER IMPLICATIONS OF THE FINDINGS The present study provides a new insight in understanding the mechanism of IVF-induced aberrations during embryonic development and the increased health risks in the offspring. In addition, we highlighted the possibility of improving existing IVF systems by modulating mitochondrial functions.
Collapse
Affiliation(s)
- Likun Ren
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Zhuqing Wang
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Lei An
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Zhennan Zhang
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Kun Tan
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Kai Miao
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Li Tao
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Linghua Cheng
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Zhenni Zhang
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Mingyao Yang
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Zhonghong Wu
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| | - Jianhui Tian
- Ministry of Agriculture Key Laboratory of Animal Genetics, Breeding and Reproduction, National Engineering Laboratory for Animal Breeding, College of Animal Sciences and Technology, China Agricultural University, Haidian District, Beijing 100193, China
| |
Collapse
|
43
|
Young MJ, Humble MM, DeBalsi KL, Sun KY, Copeland WC. POLG2 disease variants: analyses reveal a dominant negative heterodimer, altered mitochondrial localization and impaired respiratory capacity. Hum Mol Genet 2015; 24:5184-97. [PMID: 26123486 PMCID: PMC4550827 DOI: 10.1093/hmg/ddv240] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 06/02/2015] [Accepted: 06/22/2015] [Indexed: 01/14/2023] Open
Abstract
Human mitochondrial DNA (mtDNA) is replicated and repaired by the mtDNA polymerase gamma, polγ. Polγ is composed of three subunits encoded by two nuclear genes: (1) POLG codes for the 140-kilodalton (kDa) catalytic subunit, p140 and (2) POLG2 encodes the ∼110-kDa homodimeric accessory subunit, p55. Specific mutations are associated with POLG- or POLG2-related disorders. During DNA replication the p55 accessory subunit binds to p140 and increases processivity by preventing polγ's dissociation from the template. To date, studies have demonstrated that homodimeric p55 disease variants are deficient in the ability to stimulate p140; however, all patients currently identified with POLG2-related disorders are heterozygotes. In these patients, we expect p55 to occur as 25% wild-type (WT) homodimers, 25% variant homodimers and 50% heterodimers. We report the development of a tandem affinity strategy to isolate p55 heterodimers. The WT/G451E p55 heterodimer impairs polγ function in vitro, demonstrating that the POLG2 c.1352G>A/p.G451E mutation encodes a dominant negative protein. To analyze the subcellular consequence of disease mutations in HEK293 cells, we designed plasmids encoding p55 disease variants tagged with green fluorescent protein (GFP). P205R and L475DfsX2 p55 variants exhibit irregular diffuse mitochondrial fluorescence and unlike WT p55, they fail to form distinct puncta associated with mtDNA nucleoids. Furthermore, homogenous preparations of P205R and L475DfsX2 p55 form aberrant reducible multimers. We predict that abnormal protein folding or aggregation or both contribute to the pathophysiology of these disorders. Examination of mitochondrial bioenergetics in stable cell lines overexpressing GFP-tagged p55 variants revealed impaired mitochondrial reserve capacity.
Collapse
Affiliation(s)
- Matthew J Young
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| | - Margaret M Humble
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| | - Karen L DeBalsi
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| | - Kathie Y Sun
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, DHHS, Research Triangle Park, NC 27709, USA
| |
Collapse
|
44
|
Szczepanowska K, Trifunovic A. Different faces of mitochondrial DNA mutators. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1362-72. [PMID: 26014346 DOI: 10.1016/j.bbabio.2015.05.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 05/15/2015] [Accepted: 05/17/2015] [Indexed: 10/23/2022]
Abstract
A number of studies have shown that ageing is associated with increased amounts of mtDNA deletions and/or point mutations in a variety of species as diverse as Caenorhabditis elegans, Drosophila melanogaster, mice, rats, dogs, primates and humans. This detected vulnerability of mtDNA has led to the suggestion that the accumulation of somatic mtDNA mutations might arise from increased oxidative damage and could play an important role in the ageing process by producing cells with a decreased oxidative capacity. However, the vast majority of DNA polymorphisms and disease-causing base-substitution mutations and age-associated mutations that have been detected in human mtDNA are transition mutations. They are likely arising from the slight infidelity of the mitochondrial DNA polymerase. Indeed, transition mutations are also the predominant type of mutation found in mtDNA mutator mice, a model for premature ageing caused by increased mutation load due to the error prone mitochondrial DNA synthesis. These particular misincorporation events could also be exacerbated by dNTP pool imbalances. The role of different repair, replication and maintenance mechanisms that contribute to mtDNA integrity and mutagenesis will be discussed in details in this article. This article is part of a Special Issue entitled: Mitochondrial Dysfunction in Aging.
Collapse
Affiliation(s)
- Karolina Szczepanowska
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931 Cologne, Germany
| | - Aleksandra Trifunovic
- Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases (CECAD) and Institute for Mitochondrial Diseases and Ageing, Medical Faculty, University of Cologne, D-50931 Cologne, Germany.
| |
Collapse
|
45
|
Baker CN, Gidus SA, Price GF, Peoples JNR, Ebert SN. Impaired cardiac energy metabolism in embryos lacking adrenergic stimulation. Am J Physiol Endocrinol Metab 2015; 308:E402-13. [PMID: 25516547 PMCID: PMC4346738 DOI: 10.1152/ajpendo.00267.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
As development proceeds from the embryonic to fetal stages, cardiac energy demands increase substantially, and oxidative phosphorylation of ADP to ATP in mitochondria becomes vital. Relatively little, however, is known about the signaling mechanisms regulating the transition from anaerobic to aerobic metabolism that occurs during the embryonic period. The main objective of this study was to test the hypothesis that adrenergic hormones provide critical stimulation of energy metabolism during embryonic/fetal development. We examined ATP and ADP concentrations in mouse embryos lacking adrenergic hormones due to targeted disruption of the essential dopamine β-hydroxylase (Dbh) gene. Embryonic ATP concentrations decreased dramatically, whereas ADP concentrations rose such that the ATP/ADP ratio in the adrenergic-deficient group was nearly 50-fold less than that found in littermate controls by embryonic day 11.5. We also found that cardiac extracellular acidification and oxygen consumption rates were significantly decreased, and mitochondria were significantly larger and more branched in adrenergic-deficient hearts. Notably, however, the mitochondria were intact with well-formed cristae, and there was no significant difference observed in mitochondrial membrane potential. Maternal administration of the adrenergic receptor agonists isoproterenol or l-phenylephrine significantly ameliorated the decreases in ATP observed in Dbh-/- embryos, suggesting that α- and β-adrenergic receptors were effective modulators of ATP concentrations in mouse embryos in vivo. These data demonstrate that adrenergic hormones stimulate cardiac energy metabolism during a critical period of embryonic development.
Collapse
Affiliation(s)
- Candice N Baker
- Burnett School of Biomedical Sciences, University of Central Florida, College of Medicine, Orlando, Florida; and
| | - Sarah A Gidus
- Burnett School of Biomedical Sciences, University of Central Florida, College of Medicine, Orlando, Florida; and
| | - George F Price
- Department of Electron Microscopy, Department of Pathology, Orlando Regional Medical Center, Orlando, Florida
| | - Jessica N R Peoples
- Burnett School of Biomedical Sciences, University of Central Florida, College of Medicine, Orlando, Florida; and
| | - Steven N Ebert
- Burnett School of Biomedical Sciences, University of Central Florida, College of Medicine, Orlando, Florida; and
| |
Collapse
|
46
|
Iommarini L, Peralta S, Torraco A, Diaz F. Mitochondrial Diseases Part II: Mouse models of OXPHOS deficiencies caused by defects in regulatory factors and other components required for mitochondrial function. Mitochondrion 2015; 22:96-118. [PMID: 25640959 DOI: 10.1016/j.mito.2015.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 01/22/2015] [Indexed: 01/21/2023]
Abstract
Mitochondrial disorders are defined as defects that affect the oxidative phosphorylation system (OXPHOS). They are characterized by a heterogeneous array of clinical presentations due in part to a wide variety of factors required for proper function of the components of the OXPHOS system. There is no cure for these disorders owing to our poor knowledge of the pathogenic mechanisms of disease. To understand the mechanisms of human disease numerous mouse models have been developed in recent years. Here we summarize the features of several mouse models of mitochondrial diseases directly related to those factors affecting mtDNA maintenance, replication, transcription, translation as well as other proteins that are involved in mitochondrial dynamics and quality control which affect mitochondrial OXPHOS function without being intrinsic components of the system. We discuss how these models have contributed to our understanding of mitochondrial diseases and their pathogenic mechanisms.
Collapse
Affiliation(s)
- Luisa Iommarini
- Department of Pharmacy and Biotechnology (FABIT), University of Bologna, Via Irnerio 42, 40128 Bologna, Italy.
| | - Susana Peralta
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| | - Alessandra Torraco
- Unit for Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Viale di San Paolo, 15 - 00146, Rome, Italy.
| | - Francisca Diaz
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| |
Collapse
|
47
|
Wu JH, Zhang SH, Nickerson JM, Gao FJ, Sun Z, Chen XY, Zhang SJ, Gao F, Chen JY, Luo Y, Wang Y, Sun XH. Cumulative mtDNA damage and mutations contribute to the progressive loss of RGCs in a rat model of glaucoma. Neurobiol Dis 2014; 74:167-179. [PMID: 25478814 DOI: 10.1016/j.nbd.2014.11.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 10/13/2014] [Accepted: 11/17/2014] [Indexed: 11/25/2022] Open
Abstract
Glaucoma is a chronic neurodegenerative disease characterized by the progressive loss of retinal ganglion cells (RGCs). Mitochondrial DNA (mtDNA) alterations have been documented as a key component of many neurodegenerative disorders. However, whether mtDNA alterations contribute to the progressive loss of RGCs and the mechanism whereby this phenomenon could occur are poorly understood. We investigated mtDNA alterations in RGCs using a rat model of chronic intraocular hypertension and explored the mechanisms underlying progressive RGC loss. We demonstrate that the mtDNA damage and mutations triggered by intraocular pressure (IOP) elevation are initiating, crucial events in a cascade leading to progressive RGC loss. Damage to and mutation of mtDNA, mitochondrial dysfunction, reduced levels of mtDNA repair/replication enzymes, and elevated reactive oxygen species form a positive feedback loop that produces irreversible mtDNA damage and mutation and contributes to progressive RGC loss, which occurs even after a return to normal IOP. Furthermore, we demonstrate that mtDNA damage and mutations increase the vulnerability of RGCs to elevated IOP and glutamate levels, which are among the most common glaucoma insults. This study suggests that therapeutic approaches that target mtDNA maintenance and repair and that promote energy production may prevent the progressive death of RGCs.
Collapse
Affiliation(s)
- Ji-Hong Wu
- Eye & ENT Hospital, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200032, China
| | - Sheng-Hai Zhang
- Eye & ENT Hospital, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200032, China
| | - John M Nickerson
- Ophthalmology Department, Emory University, Atlanta, GA, 30322, USA
| | - Feng-Juan Gao
- Eye & ENT Hospital, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China
| | | | - Xin-Ya Chen
- Eye & ENT Hospital, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China
| | - Shu-Jie Zhang
- Eye & ENT Hospital, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China
| | - Feng Gao
- Eye & ENT Hospital, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China
| | - Jun-Yi Chen
- Eye & ENT Hospital, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China
| | - Yi Luo
- Eye & ENT Hospital, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China
| | - Yan Wang
- Eye & ENT Hospital, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China
| | - Xing-Huai Sun
- Eye & ENT Hospital, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200032, China.,State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical college, Fudan University, Shanghai 200032, China
| |
Collapse
|
48
|
Holt IJ, Jacobs HT. Unique features of DNA replication in mitochondria: a functional and evolutionary perspective. Bioessays 2014; 36:1024-31. [PMID: 25220172 DOI: 10.1002/bies.201400052] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Last year, we reported a new mechanism of DNA replication in mammals. It occurs inside mitochondria and entails the use of processed transcripts, termed bootlaces, which hybridize with the displaced parental strand as the replication fork advances. Here we discuss possible reasons why such an unusual mechanism of DNA replication might have evolved. The bootlace mechanism can minimize the occurrence and impact of single-strand breaks that would otherwise threaten genome stability. Furthermore, by providing an implicit mismatch recognition system, it should limit the occurrence of replication-dependent deletions and insertions, and defend against invading elements. Such a mechanism may also limit attempts to manipulate the mammalian mitochondrial genome.
Collapse
Affiliation(s)
- Ian J Holt
- MRC National Institute for Medical Research, London, UK
| | | |
Collapse
|
49
|
Lee SK, Zhao MH, Zheng Z, Kwon JW, Liang S, Kim SH, Kim NH, Cui XS. Polymerase subunit gamma 2 affects porcine oocyte maturation and subsequent embryonic development. Theriogenology 2014; 83:121-30. [PMID: 25308052 DOI: 10.1016/j.theriogenology.2014.08.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 07/16/2014] [Accepted: 08/31/2014] [Indexed: 01/30/2023]
Abstract
Deoxyribonucleic acid polymerase subunit gamma (POLG) is an enzyme encoded by the mitochondrial Polg gene. Polymerase (DNA directed), gamma 2, accessory subunit, also known as POLG2, is involved in mitochondrial replication. In the present study, we examined the role of Polg2 in the maturation of porcine oocytes. After Polg2 knockdown, the mitochondrial DNA copy number was significantly (P < 0.05) lower than that in the control group. However, there was no decrease in mitochondrial membrane potential. The decrease in mitochondrial DNA copy number led to reductions in adenosine-5'-triphosphate content (P < 0.05) and the maturation rate (P < 0.05) of oocytes. Furthermore, in the Polg2-knockdown group, maturation-promoting factor activity was decreased (P < 0.05) and the percentage of oocytes displaying abnormal actin filaments and microtubules was significantly increased (P < 0.05). This likely led to the reduced development rate and number of cells per blastocyst in this group (P < 0.05). In conclusion, Polg2 seems to be critical for mitochondrial replication and regulation of adenosine-5'-triphosphate content and affects porcine oocyte maturation and subsequent embryonic development.
Collapse
Affiliation(s)
- Seul-Ki Lee
- Department of Animal Sciences, Chungbuk National University, Cheongju, South Korea; Brain Korea 21 Center for Bio-Resource Development, Cheongju, South Korea
| | - Ming-Hui Zhao
- Department of Animal Sciences, Chungbuk National University, Cheongju, South Korea; Brain Korea 21 Center for Bio-Resource Development, Cheongju, South Korea
| | - Zhong Zheng
- Department of Animal Sciences, Chungbuk National University, Cheongju, South Korea; Brain Korea 21 Center for Bio-Resource Development, Cheongju, South Korea
| | - Jung-Woo Kwon
- Department of Animal Sciences, Chungbuk National University, Cheongju, South Korea; Brain Korea 21 Center for Bio-Resource Development, Cheongju, South Korea
| | - Shuang Liang
- Department of Animal Sciences, Chungbuk National University, Cheongju, South Korea; Brain Korea 21 Center for Bio-Resource Development, Cheongju, South Korea
| | - Seon-Hyang Kim
- Department of Animal Sciences, Chungbuk National University, Cheongju, South Korea; Brain Korea 21 Center for Bio-Resource Development, Cheongju, South Korea
| | - Nam-Hyung Kim
- Department of Animal Sciences, Chungbuk National University, Cheongju, South Korea; Brain Korea 21 Center for Bio-Resource Development, Cheongju, South Korea
| | - Xiang-Shun Cui
- Department of Animal Sciences, Chungbuk National University, Cheongju, South Korea; Brain Korea 21 Center for Bio-Resource Development, Cheongju, South Korea.
| |
Collapse
|
50
|
Abstract
Mitochondrial DNA is replicated by DNA polymerase γ in concert with accessory proteins such as the mitochondrial DNA helicase, single-stranded DNA binding protein, topoisomerase, and initiating factors. Defects in mitochondrial DNA replication or nucleotide metabolism can cause mitochondrial genetic diseases due to mitochondrial DNA deletions, point mutations, or depletion, which ultimately cause loss of oxidative phosphorylation. These genetic diseases include mitochondrial DNA depletion syndromes such as Alpers or early infantile hepatocerebral syndromes, and mitochondrial DNA deletion disorders, such as progressive external ophthalmoplegia, ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy. This review focuses on our current knowledge of genetic defects of mitochondrial DNA replication (POLG, POLG2, C10orf2, and MGME1) that cause instability of mitochondrial DNA and mitochondrial disease.
Collapse
Affiliation(s)
- William C. Copeland
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| |
Collapse
|