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Dirven Y, Eide DM, Henriksson EW, Hjorth R, Sharma AK, Graupner A, Brunborg G, Ballangby J, Boisen AMZ, Swedmark S, Gützkow KB, Olsen AK. Assessing testicular germ cell DNA damage in the comet assay; introduction of a proof-of-concept. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2023; 64:88-104. [PMID: 36629742 DOI: 10.1002/em.22527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 12/30/2022] [Accepted: 01/06/2023] [Indexed: 06/17/2023]
Abstract
The in vivo comet assay is widely used to measure genotoxicity; however, the current OECD test guideline (TG 489) does not recommend using the assay to assess testicular germ cells, due to the presence of testicular somatic cells. An adapted approach to specifically assess testicular germ cells within the comet assay is certainly warranted, considering regulatory needs for germ cell-specific genotoxicity data in relation to the increasing global production of and exposure to potentially hazardous chemicals. Here, we provide a proof-of-concept to selectively analyze round spermatids and primary spermatocytes, distinguishing them from other cells of the testicle. Utilizing the comet assay recordings of DNA content (total fluorescence intensity) and DNA damage (% tail intensity) of individual comets, we developed a framework to distinguish testicular cell populations based on differences in DNA content/ploidy and appearance. Haploid round spermatid comets are identified through (1) visual inspection of DNA content distributions, (2) setting DNA content thresholds, and (3) modeling DNA content distributions using a normal mixture distribution function. We also describe an approach to distinguish primary spermatocytes during comet scoring, based on their high DNA content and large physical size. Our concept allows both somatic and germ cells to be analyzed in the same animal, adding a versatile, sensitive, rapid, and resource-efficient assay to the limited genotoxicity assessment toolbox for germ cells. An adaptation of TG 489 facilitates accumulation of valuable information regarding distribution of substances to germ cells and their potential for inducing germ cell gene mutations and structural chromosomal aberrations.
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Affiliation(s)
- Yvette Dirven
- Norwegian Institute of Public Health, Division of Climate and Environmental Health, Oslo, Norway
- Centre for Environmental Radioactivity (CERAD, Centre of Excellence of the Norwegian Research Council), Oslo, Norway
| | - Dag Markus Eide
- Norwegian Institute of Public Health, Division of Climate and Environmental Health, Oslo, Norway
- Centre for Environmental Radioactivity (CERAD, Centre of Excellence of the Norwegian Research Council), Oslo, Norway
| | - Erika Witasp Henriksson
- Swedish Chemicals Agency, Department of Development of Legislation and Other Instruments, Unit of Proposals for Classification and Restriction, Sundbyberg, Sweden
- Swedish Chemicals Agency, Department of Development of Legislation and Other Instruments, Unit of Evaluation of Substances, Sundbyberg, Sweden
| | - Rune Hjorth
- The Danish Environmental Protection Agency, Odense, Denmark
| | - Anoop Kumar Sharma
- Technical University of Denmark, National Food Institute, Lyngby, Denmark
| | - Anne Graupner
- Norwegian Institute of Public Health, Division of Climate and Environmental Health, Oslo, Norway
- Centre for Environmental Radioactivity (CERAD, Centre of Excellence of the Norwegian Research Council), Oslo, Norway
| | - Gunnar Brunborg
- Norwegian Institute of Public Health, Division of Climate and Environmental Health, Oslo, Norway
- Centre for Environmental Radioactivity (CERAD, Centre of Excellence of the Norwegian Research Council), Oslo, Norway
| | - Jarle Ballangby
- Norwegian Institute of Public Health, Division of Climate and Environmental Health, Oslo, Norway
- Centre for Environmental Radioactivity (CERAD, Centre of Excellence of the Norwegian Research Council), Oslo, Norway
| | | | - Stellan Swedmark
- Swedish Chemicals Agency, Department of Development of Legislation and Other Instruments, Unit of Evaluation of Substances, Sundbyberg, Sweden
| | - Kristine Bjerve Gützkow
- Norwegian Institute of Public Health, Division of Climate and Environmental Health, Oslo, Norway
- Centre for Environmental Radioactivity (CERAD, Centre of Excellence of the Norwegian Research Council), Oslo, Norway
| | - Ann-Karin Olsen
- Norwegian Institute of Public Health, Division of Climate and Environmental Health, Oslo, Norway
- Centre for Environmental Radioactivity (CERAD, Centre of Excellence of the Norwegian Research Council), Oslo, Norway
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2
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Akbari M, Nilsen HL, Montaldo NP. Dynamic features of human mitochondrial DNA maintenance and transcription. Front Cell Dev Biol 2022; 10:984245. [PMID: 36158192 PMCID: PMC9491825 DOI: 10.3389/fcell.2022.984245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/02/2022] [Indexed: 12/03/2022] Open
Abstract
Mitochondria are the primary sites for cellular energy production and are required for many essential cellular processes. Mitochondrial DNA (mtDNA) is a 16.6 kb circular DNA molecule that encodes only 13 gene products of the approximately 90 different proteins of the respiratory chain complexes and an estimated 1,200 mitochondrial proteins. MtDNA is, however, crucial for organismal development, normal function, and survival. MtDNA maintenance requires mitochondrially targeted nuclear DNA repair enzymes, a mtDNA replisome that is unique to mitochondria, and systems that control mitochondrial morphology and quality control. Here, we provide an overview of the current literature on mtDNA repair and transcription machineries and discuss how dynamic functional interactions between the components of these systems regulate mtDNA maintenance and transcription. A profound understanding of the molecular mechanisms that control mtDNA maintenance and transcription is important as loss of mtDNA integrity is implicated in normal process of aging, inflammation, and the etiology and pathogenesis of a number of diseases.
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Affiliation(s)
- Mansour Akbari
- Department of Medical Biology, Faculty of Health Sciences, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Hilde Loge Nilsen
- Department of Clinical Molecular Biology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Unit for precision medicine, Akershus University Hospital, Nordbyhagen, Norway
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | - Nicola Pietro Montaldo
- Department of Clinical Molecular Biology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- *Correspondence: Nicola Pietro Montaldo,
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3
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Lambert-Smith IA, Saunders DN, Yerbury JJ. Progress in biophysics and molecular biology proteostasis impairment and ALS. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2022; 174:3-27. [PMID: 35716729 DOI: 10.1016/j.pbiomolbio.2022.06.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 05/19/2022] [Accepted: 06/09/2022] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a rapidly progressive and fatal neurodegenerative disease that results from the loss of both upper and lower motor neurons. It is the most common motor neuron disease and currently has no effective treatment. There is mounting evidence to suggest that disturbances in proteostasis play a significant role in ALS pathogenesis. Proteostasis is the maintenance of the proteome at the right level, conformation and location to allow a cell to perform its intended function. In this review, we present a thorough synthesis of the literature that provides evidence that genetic mutations associated with ALS cause imbalance to a proteome that is vulnerable to such pressure due to its metastable nature. We propose that the mechanism underlying motor neuron death caused by defects in mRNA metabolism and protein degradation pathways converges on proteostasis dysfunction. We propose that the proteostasis network may provide an effective target for therapeutic development in ALS.
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Affiliation(s)
- Isabella A Lambert-Smith
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia; Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Darren N Saunders
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| | - Justin J Yerbury
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia; Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia.
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4
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Swift ML, Sell C, Azizkhan-Clifford J. DNA damage-induced degradation of Sp1 promotes cellular senescence. GeroScience 2021; 44:683-698. [PMID: 34550526 PMCID: PMC9135943 DOI: 10.1007/s11357-021-00456-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 09/07/2021] [Indexed: 11/28/2022] Open
Abstract
Persistent DNA damage (genotoxic stress) triggers signaling cascades that drive cells into apoptosis or senescence to avoid replicating a damaged genome. Sp1 has been found to play a role in double strand break (DSB) repair, and a link between Sp1 and aging has also been established, where Sp1 protein, but not RNA, levels decrease with age. Interestingly, inhibition ATM reverses the age-related degradation of Sp1, suggesting that DNA damage signaling is involved in senescence-related degradation of Sp1. Proteasomal degradation of Sp1 in senescent cells is mediated via sumoylation, where sumoylation of Sp1 on lysine 16 is increased in senescent cells. Taking into consideration our previous findings that Sp1 is phosphorylated by ATM in response to DNA damage and that proteasomal degradation of Sp1 at DSBs is also mediated by its sumoylation and subsequent interaction with RNF4, we investigated the potential contribution of Sp1’s role as a DSB repair factor in mediating cellular senescence. We report here that Sp1 expression is decreased with a concomitant increase in senescence markers in response to DNA damage. Mutation of Sp1 at serine 101 to create an ATM phospho-null mutant, or mutation of lysine 16 to create a sumo-null mutant, prevents the sumoylation and subsequent proteasomal degradation of Sp1 and results in a decrease in senescence. Conversely, depletion of Sp1 or mutation of Sp1 to create an ATM phosphomimetic results in premature degradation of Sp1 and an increase in senescence markers. These data link a loss of genomic stability with senescence through the action of a DNA damage repair factor.
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Affiliation(s)
- Michelle L Swift
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N 15th Street, MS497, Philadelphia, PA, 19102, USA
| | - Christian Sell
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N 15th Street, MS497, Philadelphia, PA, 19102, USA
| | - Jane Azizkhan-Clifford
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N 15th Street, MS497, Philadelphia, PA, 19102, USA.
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Breslauer KJ. The shaping of a molecular linguist: How a career studying DNA energetics revealed the language of molecular communication. J Biol Chem 2021; 296:100522. [PMID: 34237886 PMCID: PMC8058554 DOI: 10.1016/j.jbc.2021.100522] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 03/04/2021] [Indexed: 01/31/2023] Open
Abstract
My personal and professional journeys have been far from predictable based on my early childhood. Owing to a range of serendipitous influences, I miraculously transitioned from a rebellious, apathetic teenage street urchin who did poorly in school to a highly motivated, disciplined, and ambitious academic honors student. I was the proverbial “late bloomer.” Ultimately, I earned my PhD in biophysical chemistry at Yale, followed by a postdoc fellowship at Berkeley. These two meccas of thermodynamics, coupled with my deep fascination with biology, instilled in me a passion to pursue an academic career focused on mapping the energy landscapes of biological systems. I viewed differential energetics as the language of molecular communication that would dictate and control biological structures, as well as modulate the modes of action associated with biological functions. I wanted to be a “molecular linguist.” For the next 50 years, my group and I used a combination of spectroscopic and calorimetric techniques to characterize the energy profiles of the polymorphic conformational space of DNA molecules, their differential ligand-binding properties, and the energy landscapes associated with mutagenic DNA damage recognition, repair, and replication. As elaborated below, the resultant energy databases have enabled the development of quantitative molecular biology through the rational design of primers, probes, and arrays for diagnostic, therapeutic, and molecular-profiling protocols, which collectively have contributed to a myriad of biomedical assays. Such profiling is further justified by yielding unique energy-based insights that complement and expand elegant, structure-based understandings of biological processes.
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Affiliation(s)
- Kenneth J Breslauer
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, USA; The Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey, USA.
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6
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Khan FH, Dervan E, Bhattacharyya DD, McAuliffe JD, Miranda KM, Glynn SA. The Role of Nitric Oxide in Cancer: Master Regulator or NOt? Int J Mol Sci 2020; 21:ijms21249393. [PMID: 33321789 PMCID: PMC7763974 DOI: 10.3390/ijms21249393] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 12/06/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023] Open
Abstract
Nitric oxide (NO) is a key player in both the development and suppression of tumourigenesis depending on the source and concentration of NO. In this review, we discuss the mechanisms by which NO induces DNA damage, influences the DNA damage repair response, and subsequently modulates cell cycle arrest. In some circumstances, NO induces cell cycle arrest and apoptosis protecting against tumourigenesis. NO in other scenarios can cause a delay in cell cycle progression, allowing for aberrant DNA repair that promotes the accumulation of mutations and tumour heterogeneity. Within the tumour microenvironment, low to moderate levels of NO derived from tumour and endothelial cells can activate angiogenesis and epithelial-to-mesenchymal transition, promoting an aggressive phenotype. In contrast, high levels of NO derived from inducible nitric oxide synthase (iNOS) expressing M1 and Th1 polarised macrophages and lymphocytes may exert an anti-tumour effect protecting against cancer. It is important to note that the existing evidence on immunomodulation is mainly based on murine iNOS studies which produce higher fluxes of NO than human iNOS. Finally, we discuss different strategies to target NO related pathways therapeutically. Collectively, we present a picture of NO as a master regulator of cancer development and progression.
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Affiliation(s)
- Faizan H. Khan
- Discipline of Pathology, Lambe Institute for Translational Research, School of Medicine, National University of Ireland Galway (NUIG), H91 YR71 Galway, Ireland; (F.H.K.); (E.D.); (D.D.B.); (J.D.M.)
| | - Eoin Dervan
- Discipline of Pathology, Lambe Institute for Translational Research, School of Medicine, National University of Ireland Galway (NUIG), H91 YR71 Galway, Ireland; (F.H.K.); (E.D.); (D.D.B.); (J.D.M.)
| | - Dibyangana D. Bhattacharyya
- Discipline of Pathology, Lambe Institute for Translational Research, School of Medicine, National University of Ireland Galway (NUIG), H91 YR71 Galway, Ireland; (F.H.K.); (E.D.); (D.D.B.); (J.D.M.)
| | - Jake D. McAuliffe
- Discipline of Pathology, Lambe Institute for Translational Research, School of Medicine, National University of Ireland Galway (NUIG), H91 YR71 Galway, Ireland; (F.H.K.); (E.D.); (D.D.B.); (J.D.M.)
| | - Katrina M. Miranda
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA;
| | - Sharon A. Glynn
- Discipline of Pathology, Lambe Institute for Translational Research, School of Medicine, National University of Ireland Galway (NUIG), H91 YR71 Galway, Ireland; (F.H.K.); (E.D.); (D.D.B.); (J.D.M.)
- Correspondence:
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7
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Bao Y, Tong L, Song B, Liu G, Zhu Q, Lu X, Zhang J, Lu YF, Wen H, Tian Y, Sun Y, Zhu WG. UNG2 deacetylation confers cancer cell resistance to hydrogen peroxide-induced cytotoxicity. Free Radic Biol Med 2020; 160:403-417. [PMID: 32649985 DOI: 10.1016/j.freeradbiomed.2020.06.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 05/29/2020] [Accepted: 06/12/2020] [Indexed: 02/06/2023]
Abstract
Cancer therapeutics produce reactive oxygen species (ROS) that damage the cancer genome and lead to cell death. However, cancer cells can resist ROS-induced cytotoxicity and survive. We show that nuclear-localized uracil-DNA N-glycosylase isoform 2 (UNG2) has a critical role in preventing ROS-induced DNA damage and enabling cancer-cell resistance. Under physiological conditions, UNG2 is targeted for rapid degradation via an interaction with the E3 ligase UHRF1. In response to ROS, however, UNG2 protein in cancer cells exhibits a remarkably extended half-life. Upon ROS exposure, UNG2 is deacetylated at lysine 78 by histone deacetylases, which prevents the UNG2-UHRF1 interaction. Accumulated UNG2 protein can thus excise the base damaged by ROS and enable the cell to survive these otherwise toxic conditions. Consequently, combining HDAC inhibitors (to permit UNG2 degradation) with genotoxic agents (to produce cytotoxic cellular levels of ROS) leads to a robust synergistic killing effect in cancer cells in vitro. Altogether, these data support the application of a novel approach to cancer treatment based on promoting UNG2 degradation by altering its acetylation status using an HDAC inhibitor.
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Affiliation(s)
- Yantao Bao
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China; International Cancer Center, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Lili Tong
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Boyan Song
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Ge Liu
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Qian Zhu
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Xiaopeng Lu
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Jun Zhang
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Ya-Fei Lu
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - He Wen
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Yuan Tian
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China
| | - Yujie Sun
- Department of Cell Biology, Nanjing Medical University, Nanjing, 211166, China
| | - Wei-Guo Zhu
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Department of Biochemistry and Molecular Biology, Shenzhen University School of Medicine, Shenzhen, 518055, China; International Cancer Center, Shenzhen University School of Medicine, Shenzhen, 518055, China; Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China; Shenzhen Bay Laboratory, Shenzhen University School of Medicine, Shenzhen, 518055, China.
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8
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Zheng J, Akbari M, Schirmer C, Reynaert ML, Loyens A, Lefebvre B, Buée L, Croteau DL, Galas MC, Bohr VA. Hippocampal tau oligomerization early in tau pathology coincides with a transient alteration of mitochondrial homeostasis and DNA repair in a mouse model of tauopathy. Acta Neuropathol Commun 2020; 8:25. [PMID: 32131898 PMCID: PMC7057491 DOI: 10.1186/s40478-020-00896-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 02/11/2020] [Indexed: 01/09/2023] Open
Abstract
Insoluble intracellular aggregation of tau proteins into filaments and neurodegeneration are histopathological hallmarks of Alzheimer disease (AD) and other tauopathies. Recently, prefibrillar, soluble, oligomeric tau intermediates have emerged as relevant pathological tau species; however, the molecular mechanisms of neuronal responses to tau oligomers are not fully understood. Here, we show that hippocampal neurons in six-month-old transgenic mouse model of tauopathy, THY-Tau22, are enriched with oligomeric tau, contain elongated mitochondria, and display cellular stress, but no overt cytotoxicity compared to the control mice. The levels of several key mitochondrial proteins were markedly different between the THY-Tau22 and control mice hippocampi including the mitochondrial SIRT3, PINK1, ANT1 and the fission protein DRP1. DNA base excision repair (BER) is the primary defense system against oxidative DNA damage and it was elevated in six-month-old transgenic mice. DNA polymerase β, the key BER DNA polymerase, was enriched in the cytoplasm of hippocampal neurons in six-month-old transgenic mice and localized with and within mitochondria. Polβ also co-localized with mitochondria in human AD brains in neurons containing oligomeric tau. Most of these altered mitochondrial and DNA repair events were specific to the transgenic mice at 6 months of age and were not different from control mice at 12 months of age when tau pathology reaches its maximum and oligomeric forms of tau are no longer detectable. In summary, our data suggests that we have identified key cellular stress responses at early stages of tau pathology to preserve neuronal integrity and to promote survival. To our knowledge, this work provides the first description of multiple stress responses involving mitochondrial homeostasis and BER early during the progression of tau pathology, and represents an important advance in the etiopathogenesis of tauopathies.
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9
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Mitochondria in the signaling pathways that control longevity and health span. Ageing Res Rev 2019; 54:100940. [PMID: 31415807 PMCID: PMC7479635 DOI: 10.1016/j.arr.2019.100940] [Citation(s) in RCA: 106] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/09/2019] [Accepted: 08/06/2019] [Indexed: 12/26/2022]
Abstract
Genetic and pharmacological intervention studies have identified evolutionarily conserved and functionally interconnected networks of cellular energy homeostasis, nutrient-sensing, and genome damage response signaling pathways, as prominent regulators of longevity and health span in various species. Mitochondria are the primary sites of ATP production and are key players in several other important cellular processes. Mitochondrial dysfunction diminishes tissue and organ functional performance and is a commonly considered feature of the aging process. Here we review the evidence that through reciprocal and multilevel functional interactions, mitochondria are implicated in the lifespan modulation function of these pathways, which altogether constitute a highly dynamic and complex system that controls the aging process. An important characteristic of these pathways is their extensive crosstalk and apparent malleability to modification by non-invasive pharmacological, dietary, and lifestyle interventions, with promising effects on lifespan and health span in animal models and potentially also in humans.
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Zheng J, Croteau DL, Bohr VA, Akbari M. Diminished OPA1 expression and impaired mitochondrial morphology and homeostasis in Aprataxin-deficient cells. Nucleic Acids Res 2019; 47:4086-4110. [PMID: 30986824 PMCID: PMC6486572 DOI: 10.1093/nar/gkz083] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 01/25/2019] [Accepted: 01/31/2019] [Indexed: 01/16/2023] Open
Abstract
Ataxia with oculomotor apraxia type 1 (AOA1) is an early onset progressive spinocerebellar ataxia caused by mutation in aprataxin (APTX). APTX removes 5'-AMP groups from DNA, a product of abortive ligation during DNA repair and replication. APTX deficiency has been suggested to compromise mitochondrial function; however, a detailed characterization of mitochondrial homeostasis in APTX-deficient cells is not available. Here, we show that cells lacking APTX undergo mitochondrial stress and display significant changes in the expression of the mitochondrial inner membrane fusion protein optic atrophy type 1, and components of the oxidative phosphorylation complexes. At the cellular level, APTX deficiency impairs mitochondrial morphology and network formation, and autophagic removal of damaged mitochondria by mitophagy. Thus, our results show that aberrant mitochondrial function is a key component of AOA1 pathology. This work corroborates the emerging evidence that impaired mitochondrial function is a characteristic of an increasing number of genetically diverse neurodegenerative disorders.
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Affiliation(s)
- Jin Zheng
- Center for Healthy Aging, SUND, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, 251 Bayview Blvd, Baltimore, MD, 21224, USA
| | - Vilhelm A Bohr
- Center for Healthy Aging, SUND, University of Copenhagen, 2200 Copenhagen N, Denmark
- Laboratory of Molecular Gerontology, National Institute on Aging, 251 Bayview Blvd, Baltimore, MD, 21224, USA
| | - Mansour Akbari
- Center for Healthy Aging, SUND, University of Copenhagen, 2200 Copenhagen N, Denmark
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11
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Wang Y, Zhang X, Zou G, Peng S, Liu C, Zhou X. Detection and Application of 5-Formylcytosine and 5-Formyluracil in DNA. Acc Chem Res 2019; 52:1016-1024. [PMID: 30666870 DOI: 10.1021/acs.accounts.8b00543] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Nucleic acids contain a variety of different base modifications, such as decoration at the fifth position of cytosine, which is one of the most important epigenetic modifications. Nucleic acid epigenetics mediate a wide variety of biological processes, including embryonic development and gene regulation, genomic imprinting, differentiation, and X-chromosome inactivation. Furthermore, the modification level can be aberrantly expressed in distinct sets of tissue that can indicate different tumor onsets and canceration. Thus, the analysis of modified nucleobases may contribute to the understanding of epigenetic modification-related biological processes and the correlation of modified nucleobase patterns with disease states for clinical diagnosis and treatment. In addition to 5-methylcytosine, 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxycytosine are found in organisms at a low content but are nevertheless extremely important chemical modifications, and 5-hydroxyuracil and 5-formyluracil compounds are also present. 5-Formyluracil is found in bacteriophages, prokaryotes, and mammalian cells. The 5-formyluracil content is higher in certain cancer tissues than in the normal tissues adjacent to the tumor. The content of 5-formyluracil in different cell tissues may have cell type specificity. With the continuous use of chemical tools, new detection technologies have greatly advanced the research on natural pyrimidine modifications. These modifications dynamically regulate the gene expression in eukaryotes and prokaryotes and provide mechanistic insights into the occurrence of diseases. Natural pyrimidine modifications act not only as intermediates for DNA demethylation or oxidative damage products but also as modulators of gene expression. Therefore, the development of more effective chemical tools will help us better understand the dynamic changes of natural pyrimidine modifications in vivo. In this Account, we summarize the recent advanced techniques for the detection of 5-formylpyrimidine (5-formylcytosine and 5-formyluracil) and highlight their great potential as biomarkers in biomedical applications. Focusing on the great urgency for the detection of epigenetic modifications, our group developed a series of methods for the qualitative and quantitative analysis of 5-formylpyrimidine in the past few years, aiming at facilitating the accurate detection and mapping of these epigenetic modifications. By the construction of probes, 5-formylpyrimidine can be selectively labeled. Using mass spectrometry, the epigenetic modifications can be quantified. Upon treatment under specific conditions, 5-formylcytosine can be recognized at single-base resolution. With this Account, we anticipate providing chemical and biological researchers with some insight to unlock the complex mechanism involved in 5-formylpyrimidine-related biological processes and stimulate more collaborative research interests from the different fields of materials, biological, medicine, and chemistry to promote the translational research of epigenetics in tumor diagnosis and treatment.
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Affiliation(s)
- Yafen Wang
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Xiong Zhang
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Guangrong Zou
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Shuang Peng
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Chaoxing Liu
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Xiang Zhou
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, The Institute for Advanced Studies, Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei 430072, P. R. China
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12
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Holton NW, Ebenstein Y, Gassman NR. Broad spectrum detection of DNA damage by Repair Assisted Damage Detection (RADD). DNA Repair (Amst) 2018; 66-67:42-49. [PMID: 29723708 DOI: 10.1016/j.dnarep.2018.04.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 02/09/2018] [Accepted: 04/25/2018] [Indexed: 11/29/2022]
Abstract
Environmental exposures, reactive by-products of cellular metabolism, and spontaneous deamination events result in a spectrum of DNA adducts that if un-repaired threaten genomic integrity by inducing mutations, increasing instability, and contributing to the initiation and progression of cancer. Assessment of DNA adducts in cells and tissues is critical for genotoxic and carcinogenic evaluation of chemical exposure and may provide insight into the etiology of cancer. Numerous methods to characterize the formation of DNA adducts and their retention for risk assessment have been developed. However, there are still significant drawbacks to the implementation and wide-spread use of these methods, because they often require a substantial amount of biological sample, highly specialized expertise and equipment, and depending on technique, may be limited to the detection and quantification of only a handful of DNA adducts at a time. There is a pressing need for high throughput, easy to implement assays that can assess a broad spectrum of DNA lesions, allowing for faster evaluation of chemical exposures and assessment of the retention of adducts in biological samples. Here, we describe a new methodology, Repair Assisted Damage Detection (RADD), which utilizes a DNA damage processing repair enzyme cocktail to detect and modify sites of DNA damage for a subsequent gap filling reaction that labels the DNA damage sites. This ability to detect and label a broad spectrum of DNA lesions within cells, offers a novel and easy to use tool for assessing levels of DNA damage in cells that have been exposed to environmental agents or have natural variations in DNA repair capacity.
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Affiliation(s)
- Nathaniel W Holton
- Department of Oncologic Sciences, University of South Alabama Mitchell Cancer Institute, Mobile, AL, 36604, USA.
| | - Yuval Ebenstein
- School of Chemistry, Center for Nanoscience and Nanotechnology, Center for Light-Matter Interaction, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel.
| | - Natalie R Gassman
- Department of Oncologic Sciences, University of South Alabama Mitchell Cancer Institute, Mobile, AL, 36604, USA.
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13
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German P, Saenz D, Szaniszlo P, Aguilera-Aguirre L, Pan L, Hegde ML, Bacsi A, Hajas G, Radak Z, Ba X, Mitra S, Papaconstantinou J, Boldogh I. 8-Oxoguanine DNA glycosylase1-driven DNA repair-A paradoxical role in lung aging. Mech Ageing Dev 2016; 161:51-65. [PMID: 27343030 DOI: 10.1016/j.mad.2016.06.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 06/16/2016] [Accepted: 06/20/2016] [Indexed: 12/11/2022]
Abstract
Age-associated changes in lung structure and function are some of the most important predictors of overall health, cognitive activities and longevity. Common to all aging cells is an increase in oxidatively modified DNA bases, primarily 8-oxo-7,8-dihydroguanine (8-oxoG). It is repaired via DNA base excision repair pathway driven by 8-oxoguanine DNA glycosylase-1 (OGG1-BER), whose role in aging has been the focus of many studies. This study hypothesizes that signaling and consequent gene expression during cellular response to OGG1-BER "wires" senescence/aging processes. To test OGG1-BER was mimicked by repeatedly exposing diploid lung fibroblasts cells and airways of mice to 8-oxoG base. Results showed that repeated exposures led to G1 cell cycle arrest and pre-matured senescence of cultured cells in which over 1000 genes were differentially expressed -86% of them been identical to those in naturally senesced cells. Gene ontology analysis of gene expression displayed biological processes driven by small GTPases, phosphoinositide 3-kinase and mitogen activated kinase cascades both in cultured cells and lungs. These results together, points to a new paradigm about the role of DNA damage and repair by OGG1 in aging and age-associated disease processes.
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Affiliation(s)
- Peter German
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - David Saenz
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Peter Szaniszlo
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Leopoldo Aguilera-Aguirre
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Lang Pan
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Muralidhar L Hegde
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Attila Bacsi
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Gyorgy Hajas
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Zsolt Radak
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Xueqing Ba
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Sankar Mitra
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - John Papaconstantinou
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
| | - Istvan Boldogh
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA; Sealy Center for Molecular Medicine, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA.
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14
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Poly(ADP-ribosyl) glycohydrolase prevents the accumulation of unusual replication structures during unperturbed S phase. Mol Cell Biol 2014; 35:856-65. [PMID: 25535335 DOI: 10.1128/mcb.01077-14] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Poly(ADP-ribosyl)ation (PAR) has been implicated in various aspects of the cellular response to DNA damage and genome stability. Although 17 human poly(ADP-ribose) polymerase (PARP) genes have been identified, a single poly(ADP-ribosyl) glycohydrolase (PARG) mediates PAR degradation. Here we investigated the role of PARG in the replication of human chromosomes. We show that PARG depletion affects cell proliferation and DNA synthesis, leading to replication-coupled H2AX phosphorylation. Furthermore, PARG depletion or inhibition per se slows down individual replication forks similarly to mild chemotherapeutic treatment. Electron microscopic analysis of replication intermediates reveals marked accumulation of reversed forks and single-stranded DNA (ssDNA) gaps in unperturbed PARG-defective cells. Intriguingly, while we found no physical evidence for chromosomal breakage, PARG-defective cells displayed both ataxia-telangiectasia-mutated (ATM) and ataxia-Rad3-related (ATR) activation, as well as chromatin recruitment of standard double-strand-break-repair factors, such as 53BP1 and RAD51. Overall, these data prove PAR degradation to be essential to promote resumption of replication at endogenous and exogenous lesions, preventing idle recruitment of repair factors to remodeled replication forks. Furthermore, they suggest that fork remodeling and restarting are surprisingly frequent in unperturbed cells and provide a molecular rationale to explore PARG inhibition in cancer chemotherapy.
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15
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Overexpression of DNA ligase III in mitochondria protects cells against oxidative stress and improves mitochondrial DNA base excision repair. DNA Repair (Amst) 2014; 16:44-53. [PMID: 24674627 DOI: 10.1016/j.dnarep.2014.01.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 01/21/2014] [Accepted: 01/27/2014] [Indexed: 01/06/2023]
Abstract
Base excision repair (BER) is the most prominent DNA repair pathway in human mitochondria. BER also results in a temporary generation of AP-sites, single-strand breaks and nucleotide gaps. Thus, incomplete BER can result in the generation of DNA repair intermediates that can disrupt mitochondrial DNA replication and transcription and generate mutations. We carried out BER analysis in highly purified mitochondrial extracts from human cell lines U2OS and HeLa, and mouse brain using a circular DNA substrate containing a lesion at a specific position. We found that DNA ligation is significantly slower than the preceding mitochondrial BER steps. Overexpression of DNA ligase III in mitochondria improved the rate of overall BER, increased cell survival after menadione induced oxidative stress and reduced autophagy following the inhibition of the mitochondrial electron transport chain complex I by rotenone. Our results suggest that the amount of DNA ligase III in mitochondria may be critical for cell survival following prolonged oxidative stress, and demonstrate a functional link between mitochondrial DNA damage and repair, cell survival upon oxidative stress, and removal of dysfunctional mitochondria by autophagy.
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16
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Mohsin S, Siddiqi S, Collins B, Sussman MA. Empowering adult stem cells for myocardial regeneration. Circ Res 2012; 109:1415-28. [PMID: 22158649 DOI: 10.1161/circresaha.111.243071] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Treatment strategies for heart failure remain a high priority for ongoing research due to the profound unmet need in clinical disease coupled with lack of significant translational progress. The underlying issue is the same whether the cause is acute damage, chronic stress from disease, or aging: progressive loss of functional cardiomyocytes and diminished hemodynamic output. To stave off cardiomyocyte losses, a number of strategic approaches have been embraced in recent years involving both molecular and cellular approaches to augment myocardial structure and performance. Resultant excitement surrounding regenerative medicine in the heart has been tempered by realizations that reparative processes in the heart are insufficient to restore damaged myocardium to normal functional capacity and that cellular cardiomyoplasty is hampered by poor survival, proliferation, engraftment, and differentiation of the donated population. To overcome these limitations, a combination of molecular and cellular approaches must be adopted involving use of genetic engineering to enhance resistance to cell death and increase regenerative capacity. This review highlights biological properties of approached to potentiate stem cell-mediated regeneration to promote enhanced myocardial regeneration, persistence of donated cells, and long-lasting tissue repair. Optimizing cell delivery and harnessing the power of survival signaling cascades for ex vivo genetic modification of stem cells before reintroduction into the patient will be critical to enhance the efficacy of cellular cardiomyoplasty. Once this goal is achieved, then cell-based therapy has great promise for treatment of heart failure to combat the loss of cardiac structure and function associated with acute damage, chronic disease, or aging.
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17
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Jalal S, Earley JN, Turchi JJ. DNA repair: from genome maintenance to biomarker and therapeutic target. Clin Cancer Res 2011; 17:6973-84. [PMID: 21908578 DOI: 10.1158/1078-0432.ccr-11-0761] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A critical link exists between an individual's ability to repair cellular DNA damage and cancer development, progression, and response to therapy. Knowledge gained about the proteins involved and types of damage repaired by the individual DNA repair pathways has led to the development of a variety of assays aimed at determining an individual's DNA repair capacity. These assays and their use in the analysis of clinical samples have yielded useful though somewhat conflicting data. In this review article, we discuss the major DNA repair pathways, the proteins and genes required for each, assays used to analyze activity, and the relevant clinical studies to date. With the recent results from clinical trials targeting specific DNA repair proteins for the treatment of cancer, accurate, reproducible, and relevant analysis of DNA repair takes on an even greater significance. We highlight the strengths and limitations of these DNA repair studies and assays, with respect to the clinical assessment of DNA repair capacity to determine cancer development and response to therapy.
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Affiliation(s)
- Shadia Jalal
- Division of Hematology and Oncology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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18
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Abstract
Adult stem cells exist in most mammalian organs and tissues and are indispensable for normal tissue homeostasis and repair. In most tissues, there is an age-related decline in stem cell functionality but not a depletion of stem cells. Such functional changes reflect deleterious effects of age on the genome, epigenome, and proteome, some of which arise cell autonomously and others of which are imposed by an age-related change in the local milieu or systemic environment. Notably, some of the changes, particularly epigenomic and proteomic, are potentially reversible, and both environmental and genetic interventions can result in the rejuvenation of aged stem cells. Such findings have profound implications for the stem cell–based therapy of age-related diseases.
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Affiliation(s)
- Ling Liu
- Paul F. Glenn Laboratories for the Biology of Aging, Stanford University School of Medicine, Stanford, CA 94305, USA
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19
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Akbari M, Krokan HE. Base excision repair efficiency and mechanism in nuclear extracts are influenced by the ratio between volume of nuclear extraction buffer and nuclei-implications for comparative studies. Mutat Res 2011; 736:33-8. [PMID: 21736882 DOI: 10.1016/j.mrfmmm.2011.06.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 06/08/2011] [Accepted: 06/21/2011] [Indexed: 10/18/2022]
Abstract
The base excision repair (BER) pathway corrects many different DNA base lesions and is important for genomic stability. The mechanism of BER cannot easily be investigated in intact cells and therefore in vitro methods that reflect the in vivo processes are in high demand. Reconstitution of BER using purified proteins essentially mirror properties of the proteins used, and does not necessarily reflect the mechanism as it occurs in the cell. Nuclear extracts from cultured cells have the capacity to carry out complete BER and can give important information on the mechanism. Furthermore, candidate proteins in extracts can be inhibited or depleted in a controlled way, making defined extracts an important source for mechanistic studies. The major drawback is that there is no standardized method of preparing nuclear extract for BER studies, and it does not appear to be a topic given much attention. Here we have examined BER activity of nuclear cell extracts from HeLa cells, using as substrate a circular DNA molecule with either uracil or an AP-site in a defined position. We show that BER activity of nuclear extracts from the same batch of cells varies inversely with the volume of nuclear extraction buffer relative to nuclei volume, in spite of identical protein concentrations in the BER assay mixture. Surprisingly, the uracil-DNA glycosylase activity (mainly UNG2), but not amount of UNG2, also correlated negatively with the volume of extraction buffer. These studies demonstrate that the method for preparation of nuclear extract is an important factor to consider for in vitro BER analysis and conditions used in comparative studies must be carefully worked out.
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Affiliation(s)
- Mansour Akbari
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
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20
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Wnuk M, Bugno-Poniewierska M, Lewinska A, Oklejewicz B, Zabek T, Bartosz G, Słota E. Age-related changes in genomic stability of horses. Mech Ageing Dev 2011; 132:257-68. [PMID: 21557962 DOI: 10.1016/j.mad.2011.04.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 04/08/2011] [Accepted: 04/23/2011] [Indexed: 11/26/2022]
Abstract
Recently, the old horse has been proposed as a model to study telomere-dependent senescence, immunosenescence and inflamm-aging. In the present paper, we used 80 Hucul and Anglo-Arabian horses divided into 3 age groups (juvenile, adult, old) to evaluate age-dependent changes at the genomic and DNA level and in cell proliferative potential. The level of positive TUNEL cells (both apoptotic and with DNA fragmentation), oxidative DNA damage (8-oxoG immunostaining), sister chromatid exchange and bleomycin-induced chromatid breaks were significantly increased in the combined old group compared to the combined adult group. We observed a negative correlation between micronuclei formation and age, which may be associated with damaged cells undergoing apoptosis, rather than expressing micronuclei. We were unable to show any significant changes in the nuclear division index value, which reflects the proliferative status of the viable cell fraction during aging. Here, we show that breed-independent and age-associated changes in genomic stability may contribute, at least in part, to the aging process in the horse.
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Affiliation(s)
- Maciej Wnuk
- Department of Genetics, University of Rzeszow, Rejtana, Rzeszow, Poland.
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21
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Abstract
Structural changes to DNA severely affect its functions, such as replication and transcription, and play a major role in age-related diseases and cancer. A complicated and entangled network of DNA damage response (DDR) mechanisms, including multiple DNA repair pathways, damage tolerance processes, and cell-cycle checkpoints safeguard genomic integrity. Like transcription and replication, DDR is a chromatin-associated process that is generally tightly controlled in time and space. As DNA damage can occur at any time on any genomic location, a specialized spatio-temporal orchestration of this defense apparatus is required.
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22
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de Waard MC, van der Pluijm I, Zuiderveen Borgesius N, Comley LH, Haasdijk ED, Rijksen Y, Ridwan Y, Zondag G, Hoeijmakers JHJ, Elgersma Y, Gillingwater TH, Jaarsma D. Age-related motor neuron degeneration in DNA repair-deficient Ercc1 mice. Acta Neuropathol 2010; 120:461-75. [PMID: 20602234 PMCID: PMC2923326 DOI: 10.1007/s00401-010-0715-9] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 05/25/2010] [Accepted: 06/24/2010] [Indexed: 11/16/2022]
Abstract
Degeneration of motor neurons contributes to senescence-associated loss of muscle function and underlies human neurodegenerative conditions such as amyotrophic lateral sclerosis and spinal muscular atrophy. The identification of genetic factors contributing to motor neuron vulnerability and degenerative phenotypes in vivo are therefore important for our understanding of the neuromuscular system in health and disease. Here, we analyzed neurodegenerative abnormalities in the spinal cord of progeroid Ercc1Δ/− mice that are impaired in several DNA repair systems, i.e. nucleotide excision repair, interstrand crosslink repair, and double strand break repair. Ercc1Δ/− mice develop age-dependent motor abnormalities, and have a shortened life span of 6–7 months. Pathologically, Ercc1Δ/− mice develop widespread astrocytosis and microgliosis, and motor neuron loss and denervation of skeletal muscle fibers. Degenerating motor neurons in many occasions expressed genotoxic-responsive transcription factors p53 or ATF3, and in addition, displayed a range of Golgi apparatus abnormalities. Furthermore, Ercc1Δ/− motor neurons developed perikaryal and axonal intermediate filament abnormalities reminiscent of cytoskeletal pathology observed in aging spinal cord. Our findings support the notion that accumulation of DNA damage and genotoxic stress may contribute to neuronal aging and motor neuron vulnerability in human neuromuscular disorders.
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23
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Wang Z, Rhee DB, Lu J, Bohr CT, Zhou F, Vallabhaneni H, de Souza-Pinto NC, Liu Y. Characterization of oxidative guanine damage and repair in mammalian telomeres. PLoS Genet 2010; 6:e1000951. [PMID: 20485567 PMCID: PMC2869316 DOI: 10.1371/journal.pgen.1000951] [Citation(s) in RCA: 143] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 04/13/2010] [Indexed: 12/15/2022] Open
Abstract
8-oxo-7,8-dihydroguanine (8-oxoG) and 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyG) are among the most common oxidative DNA lesions and are substrates for 8-oxoguanine DNA glycosylase (OGG1)-initiated DNA base excision repair (BER). Mammalian telomeres consist of triple guanine repeats and are subject to oxidative guanine damage. Here, we investigated the impact of oxidative guanine damage and its repair by OGG1 on telomere integrity in mice. The mouse cells were analyzed for telomere integrity by telomere quantitative fluorescence in situ hybridization (telomere-FISH), by chromosome orientation-FISH (CO-FISH), and by indirect immunofluorescence in combination with telomere-FISH and for oxidative base lesions by Fpg-incision/Southern blot assay. In comparison to the wild type, telomere lengthening was observed in Ogg1 null (Ogg1(-/-)) mouse tissues and primary embryonic fibroblasts (MEFs) cultivated in hypoxia condition (3% oxygen), whereas telomere shortening was detected in Ogg1(-/-) mouse hematopoietic cells and primary MEFs cultivated in normoxia condition (20% oxygen) or in the presence of an oxidant. In addition, telomere length abnormalities were accompanied by altered telomere sister chromatid exchanges, increased telomere single- and double-strand breaks, and preferential telomere lagging- or G-strand losses in Ogg1(-/-) mouse cells. Oxidative guanine lesions were increased in telomeres in Ogg1(-/-) mice with aging and primary MEFs cultivated in 20% oxygen. Furthermore, oxidative guanine lesions persisted at high level in Ogg1(-/-) MEFs after acute exposure to hydrogen peroxide, while they rapidly returned to basal level in wild-type MEFs. These findings indicate that oxidative guanine damage can arise in telomeres where it affects length homeostasis, recombination, DNA replication, and DNA breakage repair. Our studies demonstrate that BER pathway is required in repairing oxidative guanine damage in telomeres and maintaining telomere integrity in mammals.
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Affiliation(s)
- Zhilong Wang
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - David B. Rhee
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- University of Tennessee–Oak Ridge National Laboratory Graduate School of Genome Science and Technology, Knoxville, Tennessee, United States of America
| | - Jian Lu
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Christina T. Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Fang Zhou
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Haritha Vallabhaneni
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Nadja C. de Souza-Pinto
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Yie Liu
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- * E-mail:
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24
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St Laurent G, Hammell N, McCaffrey TA. A LINE-1 component to human aging: do LINE elements exact a longevity cost for evolutionary advantage? Mech Ageing Dev 2010; 131:299-305. [PMID: 20346965 DOI: 10.1016/j.mad.2010.03.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 03/09/2010] [Accepted: 03/15/2010] [Indexed: 12/15/2022]
Abstract
Advancing age remains the largest risk factor for devastating diseases, such as heart disease, stroke, and cancer. The mechanisms by which advancing age predisposes to disease are now beginning to unfold, due in part, to genetic and environmental manipulations of longevity in lower organisms. Converging lines of evidence suggest that DNA damage may be a final common pathway linking several proposed mechanisms of aging. The present review forwards a theory for an additional aging pathway that involves modes of inherent genetic instability. Long interspersed nuclear elements (LINEs) are endogenous non-LTR retrotransposons that compose about 20% of the human genome. The LINE-1 (L1) gene products, ORF1p and ORF2p, possess mRNA binding, endonuclease, and reverse transcriptase activity that enable retrotransposition. While principally active only during embryogenesis, L1 transcripts are detected in adult somatic cells under certain conditions. The present hypothesis proposes that L1s act as an 'endogenous clock', slowly eroding genomic integrity by competing with the organism's double-strand break repair mechanism. Thus, while L1s are an accepted mechanism of genetic variation fueling evolution, it is proposed that longevity is negatively impacted by somatic L1 activity. The theory predicts testable hypotheses about the relationship between L1 activity, DNA repair, healthy aging, and longevity.
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Affiliation(s)
- Georges St Laurent
- The George Washington University Medical Center, Department of Medicine, Division of Genomic Medicine, 2300 I St. NW, Washington, DC 20037, United States
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25
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Khobta A, Anderhub S, Kitsera N, Epe B. Gene silencing induced by oxidative DNA base damage: association with local decrease of histone H4 acetylation in the promoter region. Nucleic Acids Res 2010; 38:4285-95. [PMID: 20338881 PMCID: PMC2910050 DOI: 10.1093/nar/gkq170] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Oxidized DNA bases, particularly 7,8-dihydro-8-oxoguanine (8-oxoG), are endogenously generated in cells, being a cause of carcinogenic mutations and possibly interfering with gene expression. We found that expression of an oxidatively damaged plasmid DNA is impaired after delivery into human host cells not only due to decreased retention in the transfected cells, but also due to selective silencing of the damaged reporter gene. To test whether the gene silencing was associated with a specific change of the chromatin structure, we determined the levels of histone modifications related to transcriptional activation (acetylated histones H3 and H4) or repression (methylated K9 and K27 of the histone H3, and histone H1) in the promoter region and in the downstream transcribed DNA. Acetylation of histone H4 was found to be specifically decreased by 25% in the proximal promoter region of the damaged gene, while minor quantitative changes in other tested chromatin components could not be proven as significant. Treatment with an inhibitor of histone deacetylases, trichostatin A, partially restored expression of the damaged DNA, suggesting a causal connection between the changes of histone acetylation and persistent gene repression. Based on these findings, we propose that silencing of the oxidatively damaged DNA may occur in a chromatin-mediated mechanism.
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Affiliation(s)
- Andriy Khobta
- Johannes Gutenberg University of Mainz, Institute of Pharmacy, Staudingerweg 5, 55128 Mainz, Germany.
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26
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Zietkiewicz E, Wojda A, Witt M. Cytogenetic perspective of ageing and longevity in men and women. J Appl Genet 2009; 50:261-73. [PMID: 19638683 DOI: 10.1007/bf03195682] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Analysis of relationships between the ageing cell phenotype and the age of cell donors is one of the ways towards understanding the link between cellular and organismal ageing. Cytogenetically, ageing is associated with a number of gross cellular changes, including altered size and morphology, genomic instability, and changes in expression and proliferation. Genomic instability can be easily assessed by analyzing the level of cytogenetic aberrations. In this review, we focus on the differences in the level and profile of cytogenetic aberrations observed in donors of different age and gender. Centenarians are a small fraction of the population at the extreme of human longevity. Their inclusion in such studies may shed light on one of the basic questions: whether genome stability is better maintained in successfully aged individuals compared to the rest of the population. At the same time, comparing the profile of age-related amount of chromosomal aberrations in men and women may help explaining the commonly observed gender differences in longevity.
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27
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Affiliation(s)
- Jan H J Hoeijmakers
- Department of Genetics, Cancer Genomics Center, Erasmus University Medical Center, Rotterdam, The Netherlands.
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28
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Nowsheen S, Wukovich RL, Aziz K, Kalogerinis PT, Richardson CC, Panayiotidis MI, Bonner WM, Sedelnikova OA, Georgakilas AG. Accumulation of oxidatively induced clustered DNA lesions in human tumor tissues. Mutat Res 2009; 674:131-6. [PMID: 18948225 PMCID: PMC6944316 DOI: 10.1016/j.mrgentox.2008.09.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Accepted: 09/23/2008] [Indexed: 02/05/2023]
Abstract
Increased levels of oxidatively induced DNA damage have been reported in various cases of human pathogenesis like age-related and chronic diseases. Advances in experimental carcinogenesis associate high oxidative stress with genome instability and oncogenic transformation. Cancer biomarkers are helpful for early tumor diagnostics, prediction of tumor development, and analysis of individual tumors' response to therapy as well as recurrence. The repair resistant oxidatively induced clustered DNA lesions (OCDLs) could serve as a common indicator of oxidative stress in human malignant cells or tissues. To test this hypothesis, we assessed the levels of endogenous OCDLs in several human tumor and adjacent normal tissues from patients with liver, ovary, kidney, breast and colon cancer. These tumor tissues have already been shown to accumulate higher endogenous levels of gamma-H2AX foci. For the detection of clustered DNA lesions we used the human repair enzymes APE1, OGG1 and NTH1 as well as the Escherichia coli homologue Endonuclease III. In the majority of cases we detected higher levels of OCDLs in tumor vs. normal tissues but not always with a statistically significant difference and not with uniform tissue dependence. These data suggest for the first time the importance of endogenous non-DSB clusters in human cancer and their potential use as cancer biomarkers.
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Affiliation(s)
- Somaira Nowsheen
- Department of Biology, Thomas Harriot College of Arts and Sciences, East Carolina University, Greenville, NC 27858, USA
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Maynard S, Schurman SH, Harboe C, de Souza-Pinto NC, Bohr VA. Base excision repair of oxidative DNA damage and association with cancer and aging. Carcinogenesis 2008; 30:2-10. [PMID: 18978338 DOI: 10.1093/carcin/bgn250] [Citation(s) in RCA: 429] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Aging has been associated with damage accumulation in the genome and with increased cancer incidence. Reactive oxygen species (ROS) are produced from endogenous sources, most notably the oxidative metabolism in the mitochondria, and from exogenous sources, such as ionizing radiation. ROS attack DNA readily, generating a variety of DNA lesions, such as oxidized bases and strand breaks. If not properly removed, DNA damage can be potentially devastating to normal cell physiology, leading to mutagenesis and/or cell death, especially in the case of cytotoxic lesions that block the progression of DNA/RNA polymerases. Damage-induced mutagenesis has been linked to various malignancies. The major mechanism that cells use to repair oxidative damage lesions, such as 8-hydroxyguanine, formamidopyrimidines, and 5-hydroxyuracil, is base excision repair (BER). The BER pathway in the nucleus is well elucidated. More recently, BER was shown to also exist in the mitochondria. Here, we review the association of BER of oxidative DNA damage with aging, cancer and other diseases.
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Affiliation(s)
- Scott Maynard
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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