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Egiazarian MA, Strømstad S, Sakshaug T, Nunez-Nescolarde AB, Bethge N, Bjørås M, Scheffler K. Age- and sex-dependent effects of DNA glycosylase Neil3 on amyloid pathology, adult neurogenesis, and memory in a mouse model of Alzheimer's disease. Free Radic Biol Med 2022; 193:685-693. [PMID: 36395955 DOI: 10.1016/j.freeradbiomed.2022.11.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 10/21/2022] [Accepted: 11/12/2022] [Indexed: 11/16/2022]
Abstract
Oxidative stress generating DNA damage has been shown to be a key characteristic in Alzheimer's disease (AD). However, how it affects the pathogenesis of AD is not yet fully understood. Neil3 is a DNA glycosylase initiating repair of oxidative DNA base lesions and with a distinct expression pattern in proliferating cells. In brain, its function has been linked to hippocampal-dependent memory and to induction of neurogenesis after stroke and in prion disease. Here, we generated a novel AD mouse model deficient for Neil3 to study the impact of impaired oxidative base lesion repair on the pathogenesis of AD. Our results demonstrate an age-dependent decrease in amyloid-β (Aβ) plaque deposition in female Neil3-deficient AD mice, whereas no significant difference was observed in male mice. Furthermore, male but not female Neil3-deficient AD mice show reduced neural stem cell proliferation in the adult hippocampus and impaired working memory compared to controls. These effects seem to be independent of DNA repair as both sexes show increased level of oxidative base lesions in the hippocampus upon loss of Neil3. Thus, our findings suggest an age- and sex-dependent role of Neil3 in the progression of AD by altering cerebral Aβ accumulation and promoting adult hippocampal neurogenesis to maintain cognitive function.
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Affiliation(s)
- Milena A Egiazarian
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Silje Strømstad
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Teri Sakshaug
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Ana B Nunez-Nescolarde
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Nicole Bethge
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Magnar Bjørås
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, Oslo, Norway
| | - Katja Scheffler
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Department of Neurology and Clinical Neurophysiology, University Hospital Trondheim, Trondheim, Norway.
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Cornelius C, Crupi R, Calabrese V, Graziano A, Milone P, Pennisi G, Radak Z, Calabrese EJ, Cuzzocrea S. Traumatic brain injury: oxidative stress and neuroprotection. Antioxid Redox Signal 2013; 19:836-53. [PMID: 23547621 DOI: 10.1089/ars.2012.4981] [Citation(s) in RCA: 240] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
SIGNIFICANCE A vast amount of circumstantial evidence implicates high energy oxidants and oxidative stress as mediators of secondary damage associated with traumatic brain injury. The excessive production of reactive oxygen species due to excitotoxicity and exhaustion of the endogenous antioxidant system induces peroxidation of cellular and vascular structures, protein oxidation, cleavage of DNA, and inhibition of the mitochondrial electron transport chain. RECENT ADVANCES Different integrated responses exist in the brain to detect oxidative stress, which is controlled by several genes termed vitagens. Vitagens encode for cytoprotective heat shock proteins, and thioredoxin and sirtuins. CRITICAL ISSUES AND FUTURE DIRECTIONS This article discusses selected aspects of secondary brain injury after trauma and outlines key mechanisms associated with toxicity, oxidative stress, inflammation, and necrosis. Finally, this review discusses the role of different oxidants and presents potential clinically relevant molecular targets that could be harnessed to treat secondary injury associated with brain trauma.
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Affiliation(s)
- Carolin Cornelius
- Department of Clinical and Experimental Medicine and Pharmacology, School of Medicine, University of Messina, Messina, Italy
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3
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Geter DR, Zhang F, Schisler MR, Wood AJ, Kan HL, Jeong YC, Bartels MJ, McFadden L, Gollapudi BB. Genetic damage, but limited evidence of oxidative stress markers in diethyl maleate-induced glutathione depleted mouse lymphoma L5178Y (TK(+/-)) cell cultures. Toxicol Mech Methods 2012; 22:547-54. [PMID: 22564015 DOI: 10.3109/15376516.2012.692111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Depletion of glutathione (GSH) in cells exposed to certain xenobiotics has been proposed to result in oxidative stress, which could lead to damage of cellular macromolecules such as proteins, lipids, and DNA. Diethyl maleate (DEM) is known to conjugate with GSH and rapidly lower cellular GSH levels. The objective of this study was to investigate the influence of DEM-induced GSH depletion on various genotoxicity and gene expression end points in mouse lymphoma L5178Y (TK(+/-)) cell cultures. Cells were exposed to DEM for 4 h at concentrations of 0, 6.7, 13.5, 26.9, 53.8, 107.6, 215.3, and 430.6 µg/mL (0.039-2.5 mM). Genotoxicity was evaluated by examining the induction of in vitro micronuclei (20 h post-treatment) and DNA strand breaks as measured by comet (immediately following treatment), and correlating these observations to cellular GSH levels. In the current study, GSH was decreased more than 50% at the lowest test concentration (6.7 µg/mL) and more than 95% at ≥ 107.6 µg/mL. A significant increase in micronuclei and DNA strand breaks was observed at concentrations of ≥ 26.9 µg/mL. Gene expression of seven apoptosis and oxidative-stress related genes showed significant alterations in only three genes only at the highest test concentration. Quantifiable levels of 8-OH-dG (≥ 2 adducts per 1 × 10(8) NT) were not detected at any treatment concentration. These results demonstrate an association between DEM-induced genotoxicity and GSH depletion in mouse lymphoma L5178Y (TK(+/-)) cells, but not with other oxidative markers.
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Affiliation(s)
- David R Geter
- Toxicology and Environmental Research & Consulting, The Dow Chemical Company, Midland, Michigan, USA
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Sampath H, McCullough AK, Lloyd RS. Regulation of DNA glycosylases and their role in limiting disease. Free Radic Res 2012; 46:460-78. [PMID: 22300253 DOI: 10.3109/10715762.2012.655730] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This review will present a current understanding of mechanisms for the initiation of base excision repair (BER) of oxidatively-induced DNA damage and the biological consequences of deficiencies in these enzymes in mouse model systems and human populations.
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Affiliation(s)
- Harini Sampath
- Center for Research on Occupational and Environmental Toxicology, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, Oregon 97239 - 3098, USA
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5
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Age-associated neurodegeneration and oxidative damage to lipids, proteins and DNA. Mol Aspects Med 2011; 32:305-15. [DOI: 10.1016/j.mam.2011.10.010] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 10/11/2011] [Indexed: 01/08/2023]
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6
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Wang X, Michaelis EK. Selective neuronal vulnerability to oxidative stress in the brain. Front Aging Neurosci 2010; 2:12. [PMID: 20552050 PMCID: PMC2874397 DOI: 10.3389/fnagi.2010.00012] [Citation(s) in RCA: 411] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 03/11/2010] [Indexed: 12/21/2022] Open
Abstract
Oxidative stress (OS), caused by the imbalance between the generation and detoxification of reactive oxygen and nitrogen species (ROS/RNS), plays an important role in brain aging, neurodegenerative diseases, and other related adverse conditions, such as ischemia. While ROS/RNS serve as signaling molecules at physiological levels, an excessive amount of these molecules leads to oxidative modification and, therefore, dysfunction of proteins, nucleic acids, and lipids. The response of neurons to this pervasive stress, however, is not uniform in the brain. While many brain neurons can cope with a rise in OS, there are select populations of neurons in the brain that are vulnerable. Because of their selective vulnerability, these neurons are usually the first to exhibit functional decline and cell death during normal aging, or in age-associated neurodegenerative diseases, such as Alzheimer's disease. Understanding the molecular and cellular mechanisms of selective neuronal vulnerability (SNV) to OS is important in the development of future intervention approaches to protect such vulnerable neurons from the stresses of the aging process and the pathological states that lead to neurodegeneration. In this review, the currently known molecular and cellular factors that contribute to SNV to OS are summarized. Included among the major underlying factors are high intrinsic OS, high demand for ROS/RNS-based signaling, low ATP production, mitochondrial dysfunction, and high inflammatory response in vulnerable neurons. The contribution to the selective vulnerability of neurons to OS by other intrinsic or extrinsic factors, such as deficient DNA damage repair, low calcium-buffering capacity, and glutamate excitotoxicity, are also discussed.
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Affiliation(s)
- Xinkun Wang
- Higuchi Biosciences Center, The University of Kansas Lawrence, KS, USA
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Radak Z, Atalay M, Jakus J, Boldogh I, Davies K, Goto S. Exercise improves import of 8-oxoguanine DNA glycosylase into the mitochondrial matrix of skeletal muscle and enhances the relative activity. Free Radic Biol Med 2009; 46:238-43. [PMID: 18992806 PMCID: PMC3032603 DOI: 10.1016/j.freeradbiomed.2008.10.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 08/31/2008] [Accepted: 10/01/2008] [Indexed: 12/16/2022]
Abstract
Exercise has been shown to modify the level/activity of the DNA damage repair enzyme 8-oxoguanine-DNA glycosylase (OGG1) in skeletal muscle. We have studied the impact of regular physical training (8 weeks of swimming) and detraining (8 weeks of rest after an 8-week training session) on the activity of OGG1 in the nucleus and mitochondria as well as its targeting to the mitochondrial matrix in skeletal muscle. Neither exercise training nor detraining altered the overall levels of reactive species; however, mitochondrial levels of carbonylated proteins were decreased in the trained group as assessed by electron spin resonance and biochemical approaches. Importantly, nuclear OGG1 activity was increased by daily exercise training, whereas detraining reversed the up-regulating effect of training. Interestingly, training decreased the outer-membrane-associated mitochondrial OGG1 levels, whereas detraining reversed this effect. These results suggest that exercise training improves OGG1 import into the mitochondrial matrix, thereby increasing OGG1-mediated repair of oxidized guanine bases. Taken together, our data suggest that physical inactivity could impair the mitochondrial targeting of OGG1; however, exercise training increases OGG1 levels/activity in the nucleus and specific activity of OGG1 in mitochondrial compartments, thereby augmenting the repair of oxidized nuclear and mitochondrial DNA bases.
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Affiliation(s)
- Zsolt Radak
- Institute of Sport Science, Faculty of Physical Education and Sport Science, Semmelweis University, H-1123 Budapest, Hungary.
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Abstract
Neuronal DNA repair remains one of the most exciting areas for investigation, particularly as a means to compare the DNA repair response in mitotic (cancer) vs. post-mitotic (neuronal) cells. In addition, the role of DNA repair in neuronal cell survival and response to aging and environmental insults is of particular interest. DNA damage caused by reactive oxygen species (ROS) such as generated by mitochondrial respiration includes altered bases, abasic sites, and single- and double-strand breaks which can be prevented by the DNA base excision repair (BER) pathway. Oxidative stress accumulates in the DNA of the human brain over time especially in the mitochondrial DNA (mtDNA) and is proposed to play a critical role in aging and in the pathogenesis of several neurological disorders including Parkinson's disease, ALS, and Alzheimer's diseases. Because DNA damage accumulates in the mtDNA more than nuclear DNA, there is increased interest in DNA repair pathways and the consequence of DNA damage in the mitochondria of neurons. The type of damage that is most likely to occur in neuronal cells is oxidative DNA damage which is primarily removed by the BER pathway. Following the notion that the bulk of neuronal DNA damage is acquired by oxidative DNA damage and ROS, the BER pathway is a likely area of focus for neuronal studies of DNA repair. BER variations in brain aging and pathology in various brain regions and tissues are presented. Therefore, the BER pathway is discussed in greater detail in this review than other repair pathways. Other repair pathways including direct reversal, nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination and non-homologous end joining are also discussed. Finally, there is a growing interest in the role that DNA repair pathways play in the clinical arena as they relate to the neurotoxicity and neuropathy associated with cancer treatments. Among the numerous side effects of cancer treatments, major clinical effects include neurocognitive dysfunction and peripheral neuropathy. These symptoms occur frequently and have not been effectively studied at the cellular or molecular level. Studies of DNA repair may help our understanding of how those cells that are not dividing could succumb to neurotoxicity with the clinical manifestations discussed in the following article.
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Affiliation(s)
- Melissa L Fishel
- Department of Pediatrics, Section of Hematology/Oncology, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 W. Walnut, Room 302C, Indianapolis, IN 46202, USA
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Sava V, Reunova O, Velasquez A, Sanchez-Ramos J. Can low level exposure to ochratoxin-A cause parkinsonism? J Neurol Sci 2006; 249:68-75. [PMID: 16844142 DOI: 10.1016/j.jns.2006.06.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mycotoxins are fungal metabolites with pharmacological activities that have been utilized in the production of antibiotics, growth promoters, and other classes of drugs. Some mycotoxins have been developed as biological and chemical warfare agents. Bombs and ballistic missiles loaded with aflatoxin were stockpiled and may have been deployed by Iraq during the first Gulf War. In light of the excess incidence of amyotrophic lateral sclerosis (ALS) in veterans from Operation Desert Storm, the potential for delayed neurotoxic effects of low doses of mycotoxins should not be overlooked. Ochratoxin-A (OTA) is a common mycotoxin with complex mechanisms of action, similar to that of the aflatoxins. Acute administration of OTA at non-lethal doses (10% of the LD(50)) have been shown to increase oxidative DNA damage in brain up to 72 h, with peak effects noted at 24 h in midbrain (MB), caudate/putamen (CP) and hippocampus (HP). Levels of dopamine (DA) and its metabolites in the striatum (e.g., CP) were shown to be decreased in a dose-dependent manner. The present study focused on the effects of chronic low dose OTA exposure on regional brain oxidative stress and striatal DA metabolism. Continuous administration of low doses of OTA with implanted subcutaneous Alzet minipumps caused a small but significant decrease in striatal DA levels and an upregulation of anti-oxidative systems and DNA repair. It is possible that low dose exposure to OTA will result in an earlier onset of parkinsonism when normal age-dependent decline in striatal DA levels are superimposed on the mycotoxin-induced lesion.
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Affiliation(s)
- V Sava
- University of South Florida, Tampa, FL 33612, USA
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10
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Sava V, Reunova O, Velasquez A, Song S, Sanchez-Ramos J. Neuroanatomical mapping of DNA repair and antioxidative responses in mouse brain: Effects of a single dose of MPTP. Neurotoxicology 2006; 27:1080-93. [PMID: 16831462 DOI: 10.1016/j.neuro.2006.05.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2006] [Revised: 05/10/2006] [Accepted: 05/30/2006] [Indexed: 12/21/2022]
Abstract
The primary objective of this study was to map the normal distribution of the base excision enzyme oxyguanosine glycosylase (OGG1) across mouse-brain regions as a prelude to assessing the effects of various neurotoxicants, ranging from highly selective molecules like MPTP to more global toxic agents. This research is based on the hypothesis that regional brain vulnerability to a toxicant is determined, in part, by variation in the intrinsic capacity of cellular populations to successfully repair oxidative DNA damage. After mapping the normal distributions of OGG1 and superoxide dismutase (SOD) across 44 loci dissected from mouse brain, MPTP, a mitochondrial toxicant with selective dopamine (DA) neuron cytotoxicity was used to elicit focal oxidative stress and DNA repair responses. A single dose of MPTP (20mg/kg, i.p.) elicited time- and region-dependent changes in both SOD and OGG1, with early increases in DNA repair and anti-oxidant activities throughout all regions of brain. In some sampled loci, notably the substantia nigra (SN) and hippocampus, the heightened DNA repair and antioxidant responses were not maintained beyond 48h. Other loci from cerebellum, cerebral cortex and pons maintained high levels of activity up to 72h. Levels of dopamine (DA) were decreased significantly at all time points and remained below control levels in nigro-striatal and mesolimbic systems (ventral tegmental area and nucleus accumbens). Assessment of apoptosis by TUNEL staining revealed a significant increase in number of apoptotic nuclei in the substantia nigra at 72h and not in other loci. The marked degree of apoptosis that became evident in SN at 72h was associated with large decreases in SOD and DNA repair activity at that locus. In conclusion, MPTP elicited global effects on DNA repair and antioxidant activity in all regions of brain, but the most vulnerable loci were unable to maintain elevated DNA repair and antioxidant responses.
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Affiliation(s)
- V Sava
- Department of Neurology, University of South Florida, MDC 55, 12901 Bruce B. Downs Blvd., Tampa, FL 33612, USA
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Imam SZ, Karahalil B, Hogue BA, Souza-Pinto NC, Bohr VA. Mitochondrial and nuclear DNA-repair capacity of various brain regions in mouse is altered in an age-dependent manner. Neurobiol Aging 2005; 27:1129-36. [PMID: 16005114 DOI: 10.1016/j.neurobiolaging.2005.06.002] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Revised: 05/26/2005] [Accepted: 06/04/2005] [Indexed: 11/16/2022]
Abstract
Aging is associated with increased susceptibility to neuronal loss and disruption of cerebral function either as a component of senescence, or as a consequence of neurodegenerative disease or stroke. Here we report differential changes in the repair of oxidative DNA damage in various brain regions during aging. We evaluated mitochondrial and nuclear incision activities of oxoguanine DNA glycosylase (OGG1), uracil DNA glycosylase (UDG) and the endonuclease III homologue (NTH1) in the caudate nucleus (CN), frontal cortex (FC), hippocampus (Hip), cerebellum (CE) and brain stem (BS) of 6- and 18-month-old male C57Bl/6 mice. We observed a significant age-dependent decrease in incision activities of all three glycosylases in the mitochondria of all brain regions, whereas variable patterns of changes were seen in nuclei. No age- or region-specific changes were observed in the mitochondrial repair synthesis incorporation of uracil-initiated base-excision repair (BER). We did not observe any age or region dependent differences in levels of BER proteins among the five brain regions. In summary, our data suggest that a decreased efficiency of mitochondrial BER-glycosylases and increased oxidative damage to mitochondrial DNA might contribute to the normal aging process. These data provide a novel characterization of oxidative DNA damage processing in different brain regions implicated in various neurodegenerative disorders, and suggest that this process is regulated in an age-dependent manner. Manipulation of DNA repair mechanisms may provide a strategy to prevent neuronal loss during age-dependent neurodegenerative disorders.
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Affiliation(s)
- Syed Z Imam
- Laboratory of Molecular Gerontology, National Institute on Aging, Gerontology Research Center, NIH, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
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12
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Bolin C, Stedeford T, Cardozo-Pelaez F. Single extraction protocol for the analysis of 8-hydroxy-2'-deoxyguanosine (oxo8dG) and the associated activity of 8-oxoguanine DNA glycosylase. J Neurosci Methods 2004; 136:69-76. [PMID: 15126047 DOI: 10.1016/j.jneumeth.2003.12.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2003] [Revised: 12/17/2003] [Accepted: 12/23/2003] [Indexed: 12/01/2022]
Abstract
Determination of the promutagenic base 8-hydroxy-2'-deoxyguanosine (oxo(8)dG) has been the hallmark of studies aimed to determine oxidative damage to DNA. Different techniques including HPLC, GC-mass spectrometry, DNA sensitive sites and histology have been used to quantify oxo(8)dG levels in samples from different sources. The most accepted and well-established methods are based on HPLC and the ability of oxo(8)dG to be oxidized with an electrochemical detector. Considerable concerns have been raised in the ability of different labs to utilize a process of DNA extraction that reduces the levels of artifactual oxo(8)dG formed during sample workup. Here, we present a fully detailed protocol that has been extensively used in our Lab to extract and analyze DNA and has little or no impact in the basal levels of oxo(8)dG. Additionally, this protocol allows for the determination of the activity of mOgg1, the enzyme responsible for the initial step in the repair of the accumulated oxo(8)dG, in the same sample in which oxo(8)dG is detected.
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Affiliation(s)
- Celeste Bolin
- Department of Pharmaceutical Sciences, Center for Environmental Health Sciences, University of Montana, Missoula, MT 59812, USA
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Sava V, Mosquera D, Song S, Cardozo-Pelaez F, Sánchez-Ramos JR. Effects of melanin and manganese on DNA damage and repair in PC12-derived neurons. Free Radic Biol Med 2004; 36:1144-54. [PMID: 15082068 DOI: 10.1016/j.freeradbiomed.2004.01.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2003] [Revised: 01/07/2004] [Accepted: 01/23/2004] [Indexed: 11/24/2022]
Abstract
The mechanism of neurotoxicity produced by the interaction of melanin with manganese was investigated in PC12-derived neuronal cell cultures. The cells were incubated with melanin (25-500 microg/ml), MnCl2 (10 ng/ml-100 microg/ml) and a combination of both substances for 24 and 72 h. Incubation with either toxicant alone resulted in a minimal decrease in cell viability. The combination of melanin and manganese caused significant (up to 60%) decreases in viability of PC12 cells in a dose-dependent manner. Increases in oxidative DNA damage, indicated by levels of 8-hydroxy-2'deoxyguanosine (8-oxodG), was associated with decreased cell viability. Melanin alone, but not manganese alone, resulted in increased oxidative DNA damage. The maximal increase in 8-oxodG caused by melanin was about seven times higher than control after 24 h of exposure. The activity of the DNA repair enzyme, 8-oxoguanine DNA glycosylase (OGG1), was increased in cells incubated with single toxicants and their combinations for 24 h. On the third day of incubation with the toxicants, activity of OGG1 declined below control levels and cell viability significantly decreased. Melanin was observed to have an inhibitory effect on OGG1 activity. Study of the regulation of OGG1 activity in response to melanin and manganese may provide insights into the vulnerability of nigral neurons to oxidative stress in Parkinson's disease.
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Affiliation(s)
- Vasyl Sava
- Department of Neurology, University of South Florida, Tampa, FL, USA
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Fonnum F, Lock EA. The contributions of excitotoxicity, glutathione depletion and DNA repair in chemically induced injury to neurones: exemplified with toxic effects on cerebellar granule cells. J Neurochem 2004; 88:513-31. [PMID: 14720201 DOI: 10.1046/j.1471-4159.2003.02211.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Six chemicals, 2-halopropionic acids, thiophene, methylhalides, methylmercury, methylazoxymethanol (MAM) and trichlorfon (Fig. 1), that cause selective necrosis to the cerebellum, in particular to cerebellar granule cells, have been reviewed. The basis for the selective toxicity to these neurones is not fully understood, but mechanisms known to contribute to the neuronal cell death are discussed. All six compounds decrease cerebral glutathione (GSH), due to conjugation with the xenobiotic, thereby reducing cellular antioxidant status and making the cells more vulnerable to reactive oxygen species. 2-Halopropionic acids and methylmercury appear to also act via an excitotoxic mechanism leading to elevated intracellular Ca2+, increased reactive oxygen species and ultimately impaired mitochondrial function. In contrast, the methylhalides, trichlorfon and MAM all methylate DNA and inhibit O6-guanine-DNA methyltransferase (OGMT), an important DNA repair enzyme. We propose that a combination of reduced antioxidant status plus excitotoxicity or DNA damage is required to cause cerebellar neuronal cell death with these chemicals. The small size of cerebellar granule cells, the unique subunit composition of their N-methyl-d-aspartate (NMDA) receptors, their low DNA repair ability, low levels of calcium-binding proteins and vulnerability during postnatal brain development and distribution of glutathione and its conjugating and metabolizing enzymes are all important factors in determining the sensitivity of cerebellar granule cells to toxic compounds.
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Affiliation(s)
- F Fonnum
- Norwegian Defence Research Establishment, Division for Protection and Material, Kjeller, Norway.
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Sava V, Mosquera D, Song S, Stedeford T, Calero K, Cardozo-Pelaez F, Harbison R, Sanchez-Ramos J. Rubratoxin B elicits antioxidative and DNA repair responses in mouse brain. Gene Expr 2004; 11:211-9. [PMID: 15200233 PMCID: PMC5991149 DOI: 10.3727/000000003783992261] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Rubratoxin B (RB) is a mycotoxin with potential neurotoxic effects that have not yet been characterized. Based on existing evidence that RB interferes with mitochondrial electron transport to produce oxidative stress in peripheral tissues, we hypothesized that RB would produce oxidative damage to macromolecules in specific brain regions. Parameters of oxidative DNA damage and repair, lipid peroxidation, and superoxide dismutase (SOD) activity were measured across six mouse brain regions 24 h after administration of a single dose of RB. Lipid peroxidation and oxidative DNA damage were either unchanged or decreased in all brain regions in RB-treated mice compared with vehicle-treated mice. Concomitant with these decreased indices of oxidative macromolecular damage, SOD activity was significantly increased in all brain regions. Oxyguanosine glycosylase activity (OGG1), a key enzyme in the repair of oxidized DNA, was significantly increased in three brain regions--cerebellum (CB), caudate/putamen (CP), and cortex (CX)--but not in the hippocampus (HP), midbrain (MB), and pons/medulla (PM). The RB-enhanced OGG1 catalytic activity in these brain regions was not due to increased OGG1 protein expression, but was a result of enhanced catalytic activity of the enzyme. In conclusion, specific brain regions responded to an acute dose of RB by significantly altering SOD and OGG1 activities to maintain the degree of oxidative DNA damage equal to, or less than, that of normal steady-state levels.
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Affiliation(s)
- V. Sava
- *Neurology, University of South Florida, Tampa, FL
- †Research Service, James Haley VA, Tampa, FL
| | - D. Mosquera
- *Neurology, University of South Florida, Tampa, FL
- †Research Service, James Haley VA, Tampa, FL
| | - S. Song
- *Neurology, University of South Florida, Tampa, FL
- †Research Service, James Haley VA, Tampa, FL
| | - T. Stedeford
- †Research Service, James Haley VA, Tampa, FL
- §College of Public Health, University of South Florida, Tampa, FL
| | - K. Calero
- *Neurology, University of South Florida, Tampa, FL
| | - F. Cardozo-Pelaez
- ‡Department of Pharmaceutical Sciences, University of Montana, Missoula, MT
| | - R. Harbison
- §College of Public Health, University of South Florida, Tampa, FL
| | - J. Sanchez-Ramos
- *Neurology, University of South Florida, Tampa, FL
- †Research Service, James Haley VA, Tampa, FL
- Address correspondence to Dr. Juan R. Sanchez-Ramos, The Helen E. Ellis Professor of Neurology, University of South Florida, Department of Neurology (MDC 55), 12901 Bruce B. Downs Blvd., Tampa, FL 33612. Tel: (813) 974-6022; Fax: (813) 974-7200; E-mail:
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Mosquera DI, Stedeford T, Cardozo-Pelaez F, Sanchez-Ramos J. Strain-specific differences in the expression and activity of Ogg1 in the CNS. Gene Expr 2003; 11:47-53. [PMID: 12691525 PMCID: PMC5991156 DOI: 10.3727/000000003783992333] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The expression and activity of 8-oxoguanosine DNA-glycosylase (Ogg1), a key enzyme responsible forthe clearance of the oxidized DNA base 8-hydroxy-2'-deoxyguanosine (oxo8dG), was determined in the cerebellum (CB) and the caudate and the putamen (CP) of male Balb/c, ICR, and C57BL/J mice. There was no significant difference in the protein expression of Ogg1 in the CB or CP. The activity of Ogg1 was not significantly different in the CB; however, in the CP of ICR mice, the activity of Ogg1 was 34% and 31% lower than Balb/c and C57BL/J, respectively. In contrast, the levels of oxo8dG in the CB and CP of C57BL/J mice were nearly twice as high as the values in both regions of Balb/c and ICR mice. The activity of superoxide dismutases (SOD) appeared to account for the differences in the levels of oxo8dG in the C57BL/J strain. Total SOD in the C57BL/J strain was two- and fourfold higher in the CB and CP, respectively, versus the other strains. These results suggest that the enhanced vulnerability of the C57BL/J strain to neurotoxicants may not be due to a decreased capacity for DNA repair, but rather, the significantly higher activity of SODs, which may cause these pathways to become more readily saturated.
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Affiliation(s)
- Diana I. Mosquera
- *Department of Neurology, College of Medicine, University of South Florida, Tampa, FL 33612
| | - Todd Stedeford
- *Department of Neurology, College of Medicine, University of South Florida, Tampa, FL 33612
- †Polish Academy of Sciences, Sowinskiego 5, 44-121 Gliwice, Poland
| | - Fernando Cardozo-Pelaez
- ‡Center for Environmental Health Sciences, Department of Pharmaceutical Sciences, University of Montana, Missoula, MT 59801
| | - Juan Sanchez-Ramos
- *Department of Neurology, College of Medicine, University of South Florida, Tampa, FL 33612
- §Research Services, James A. Haley Veterans’ Hospital, Tampa, FL 33612
- Address correspondence to Juan Sanchez-Ramos, Ph.D., M.D., Department of Neurology MDC 55, University of South Florida, 12901 Bruce B. Downs Blvd., Tampa, FL 33612. Tel: (813) 974-6022; Fax: (813) 974-7200; E-mail:
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Abstract
As one part of a distinguished scientific career, Dr. Bryn Bridges focused his attention on the issue of DNA damage and repair in stationary phase bacteria. His work in this area led to his interest in DNA repair and mutagenesis in another non-dividing cell population, the neurons in the mammalian nervous system. He has specifically taken an interest in the magnocellular neurons of the central nervous system, and the possibility that somatic mutations may be occurring in these neurons. As part of this special issue dedicated to Bryn Bridges upon his retirement, I will discuss the various DNA repair pathways known to be active in the nervous system. The importance of DNA repair to the nervous system is most graphically illustrated by the neurological abnormalities observed in patients with hereditary diseases associated with defects in DNA repair. I will consider the mechanisms underlying the neurological abnormalities observed in patients with four of these diseases: xeroderma pigmentosum (XP), Cockayne's syndrome (CS), ataxia telangectasia (AT) and AT-like disorder (ATLD). I will also propose a mechanism for one of the observations indicating that somatic mutation can occur in the magnocellular neurons of the aging rat brain. Finally, as a parallel to Bridges inquiry into how much DNA synthesis is going on in stationary phase bacteria, I will address the question of how much DNA synthesis in going on in neurons, and the implications of the answer to this question for recent studies of neurogenesis in adult mammals.
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Affiliation(s)
- P J Brooks
- Section on Molecular Neurobiology, Laboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 12420 Parklawn Drive, MSC 8110, Bethesda, MD 20892-8110, USA.
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