scholarly journals Oxidative DNA Damage in Tamoxifen Injected THPfl/+ ROSACre/+ Mice

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Robert Moore ◽  
Kaice LaFavers ◽  
Tarek El-Ashkar
Keyword(s):  
Dna Damage ◽  
Oxidative Damage ◽  
Genomic Dna ◽  
Oxidative Dna Damage ◽  
Heterozygous State ◽  
Serum Samples ◽  
Relevant Model ◽  
Important Regulator ◽  
Circulating Levels ◽  
Larger Sample

Background and Hypothesis:  Tamm-Horsfall protein (THP) is an important regulator of urinary and systemic homeostasis expressed exclusively in the kidney. Complete knockout of THP has been shown to lead to systemic oxidative damage in a mouse model. To develop a more clinically relevant model, we generated a tamoxifen inducible knockout/heterozygote mouse using the Cre/Lox system. We hypothesize that inducing a heterozygous state would increase levels of oxidative damage in mice.  Methods:  Experimental mice were generated by breeding THPfl/fl mice with ROSACreERT2/CreERT2 mice to develop the inducible heterozygote THPfl/+RosaCreERT2. These mice, along with controls (THPfl/fl) were treated with daily intraperitoneal injections of 75 mg/kg tamoxifen for 5 days. Serum samples were obtained from mice at baseline and 1, 2 and 3 weeks from the first injection, while kidneys were harvested at 1 or 3 weeks. PCR of kidney genomic DNA demonstrated excision of the floxed allele in mice expressing Cre-ERT2.  Western Blot analysis of kidney lysates was used to measure kidney THP, while circulating THP was measured by ELISA. Oxidative DNA damage was measured in the kidney and circulation by ELISA.  Results:  Though kidney THP levels decreased in mice expressing Cre-ERT2, circulating levels of THP remained stable, with evidence of transient increases at 1 or 2 weeks for most animals. Mice expressing Cre-ERT2 had significantly increased oxidative DNA damage within the kidney and there was a trend toward increased oxidative DNA damage in the serum, though larger sample sizes are required to verify this finding.  Conclusion:  Despite decreased THP in the kidney, mice maintained normal levels of circulating THP. However, higher levels of oxidative damage were found in both the kidney and circulation. Together, these results suggest that THP levels in the serum are tightly controlled and that an acute loss of THP leads to rapid increases in oxidative damage. 

scholarly journals Beta-carotene enhances the recovery of lymphocytes from oxidative DNA damage.

1998 ◽  
Vol 45 (1) ◽  
pp. 183-190 ◽  
Author(s):  
L Fillion ◽  
A Collins ◽  
S Southon
Keyword(s):  
Dna Damage ◽  
Oxidative Damage ◽  
Oxidative Dna Damage ◽  
Enhanced Recovery ◽  
Beta Carotene ◽  
Epidemiological Studies ◽  
Dietary Factors ◽  
Causal Mechanism ◽  
Strand Breaks

Epidemiological studies have revealed a strong correlation between high intake of fruit and vegetables and low incidence of certain cancers. Micronutrients present in these foods are thought to decrease free radical attack on DNA and hence protect against mutations that cause cancer, but the fine details of the causal mechanism have still to be elucidated. Whether dietary factors can modulate DNA repair--a crucial element in the avoidance of carcinogenesis--is an intriguing question that has not yet been satisfactorily answered. In order to investigate the effects of beta-carotene on oxidative damage and its repair, volunteers were given a single 45 mg dose and lymphocytes taken before and after the supplement were treated in vitro with H2O2. DNA strand breaks and oxidised pyrimidines were measured at intervals, to monitor the removal of oxidative DNA damage. We found inter-individual variations in response. In cases where the baseline plasma beta-carotene concentration was high, or where supplementation increased the plasma concentration, recovery from oxidative damage (i.e. removal of both oxidised pyrimidines and strand breaks) was relatively rapid. However, what seems to be an enhancement of repair might in fact represent an amelioration of the continuing oxidative stress encountered by the lymphocytes under in vitro culture conditions. We found that culture in a 5% oxygen atmosphere enhanced recovery of lymphocytes from H2O2 damage.

scholarly journals Oxidative lipid, protein, and DNA damage as oxidative stress markers in vascular complications of diabetes mellitus

2011 ◽  
Vol 34 (3) ◽  
pp. 163 ◽  
Author(s):  
Omur Tabak ◽  
Remise Gelisgen ◽  
Hayriye Erman ◽  
Fusun Erdenen ◽  
Cüneyt Muderrisoglu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Diabetes Mellitus ◽  
Dna Damage ◽  
Oxidative Dna Damage ◽  
Vascular Complications ◽  
Diabetic Group ◽  
Control Group ◽  
Diabetic Patients ◽  
Serum Samples ◽  
Type 2 Diabetic Patients

Purpose: The purpose of this study was to determine the effects of diabetic complications on oxidation of proteins, lipids, and DNA and to investigate the relationship between oxidative damage markers and clinical parameters. Methods: The study group consisted of 69 type 2 diabetic patients (20 patients without complication, 49 patients with complication) who attended internal medicine outpatient clinics of Istanbul Education and Research Hospital and 19 healthy control subjects. In serum samples of both diabetic patients and healthy subjects, 8-hydroxy-2’deoxyguanosine (8-OHdG), as a marker of oxidative DNA damage, Nε-(hexanoyl)lysine (HEL) and 15-F2t-iso-prostaglandin (15-F2t-IsoP). as products of lipooxidative damage, advanced oxidation protein products (AOPP), as markers of protein damage, and paraoxonase1 (PON1) as antioxidant were studied. Results: 15-F2t-IsoP (p < 0.005) and AOPP (p < 0.001) levels were significantly higher in diabetic group than control group while there were no significant differences in levels of 8-OHdG and HEL between the two groups. AOPP (p < 0.001) and 8-OHdG (p < 0.001) were significantly higher in diabetic group with complications compared to diabetic group without complications. Conclusions: Increased formation of free radicals and oxidative stress, under conditions of hyperglycaemia, is one of the probable causes for evolution of complications in diabetes mellitus. Our study supports the hypothesis that oxidant/antioxidant balance is disturbed in diabetic patients.

Paternal impacts on development: identification of genomic regions vulnerable to oxidative DNA damage in human spermatozoa

2019 ◽  
Vol 34 (10) ◽  
pp. 1876-1890 ◽  
Author(s):  
M J Xavier ◽  
B Nixon ◽  
S D Roman ◽  
R J Scott ◽  
J R Drevet ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Male Infertility ◽  
Oxidative Damage ◽  
Oxidative Dna Damage ◽  
Human Spermatozoa ◽  
Research Centre ◽  
Environmental Toxicants ◽  
Next Generation ◽  
Genomic Regions

Abstract STUDY QUESTION Do all regions of the paternal genome within the gamete display equivalent vulnerability to oxidative DNA damage? SUMMARY ANSWER Oxidative DNA damage is not randomly distributed in mature human spermatozoa but is instead targeted, with particular chromosomes being especially vulnerable to oxidative stress. WHAT IS KNOWN ALREADY Oxidative DNA damage is frequently encountered in the spermatozoa of male infertility patients. Such lesions can influence the incidence of de novo mutations in children, yet it remains to be established whether all regions of the sperm genome display equivalent susceptibility to attack by reactive oxygen species. STUDY DESIGN, SIZE, DURATION Human spermatozoa obtained from normozoospermic males (n = 8) were split into equivalent samples and subjected to either hydrogen peroxide (H2O2) treatment or vehicle controls before extraction of oxidized DNA using a modified DNA immunoprecipitation (MoDIP) protocol. Specific regions of the genome susceptible to oxidative damage were identified by next-generation sequencing and validated in the spermatozoa of normozoospermic males (n = 18) and in patients undergoing infertility evaluation (n = 14). PARTICIPANTS/MATERIALS, SETTING, METHODS Human spermatozoa were obtained from normozoospermic males and divided into two identical samples prior to being incubated with either H2O2 (5 mm, 1 h) to elicit oxidative stress or an equal volume of vehicle (untreated controls). Alternatively, spermatozoa were obtained from fertility patients assessed as having high basal levels of oxidative stress within their spermatozoa. All semen samples were subjected to MoDIP to selectively isolate oxidized DNA, prior to sequencing of the resultant DNA fragments using a next-generation whole-genomic sequencing platform. Bioinformatic analysis was then employed to identify genomic regions vulnerable to oxidative damage, several of which were selected for real-time quantitative PCR (qPCR) validation. MAIN RESULTS AND THE ROLE OF CHANCE Approximately 9000 genomic regions, 150–1000 bp in size, were identified as highly vulnerable to oxidative damage in human spermatozoa. Specific chromosomes showed differential susceptibility to damage, with chromosome 15 being particularly sensitive to oxidative attack while the sex chromosomes were protected. Susceptible regions generally lay outside protamine- and histone-packaged domains. Furthermore, we confirmed that these susceptible genomic sites experienced a dramatic (2–15-fold) increase in their burden of oxidative DNA damage in patients undergoing infertility evaluation compared to normal healthy donors. LIMITATIONS, REASONS FOR CAUTION The limited number of samples analysed in this study warrants external validation, as do the implications of our findings. Selection of male fertility patients was based on high basal levels of oxidative stress within their spermatozoa as opposed to specific sub-classes of male factor infertility. WIDER IMPLICATIONS OF THE FINDINGS The identification of genomic regions susceptible to oxidation in the male germ line will be of value in focusing future analyses into the mutational load carried by children in response to paternal factors such as age, the treatment of male infertility using ART and paternal exposure to environmental toxicants. STUDY FUNDING/COMPETING INTEREST(S) Project support was provided by the University of Newcastle’s (UoN) Priority Research Centre for Reproductive Science. M.J.X. was a recipient of a UoN International Postgraduate Research Scholarship. B.N. is the recipient of a National Health and Medical Research Council of Australia Senior Research Fellowship. Authors declare no conflict of interest.

scholarly journals Oxidative DNA Damage Defense Systems in Avoidance of Stationary-Phase Mutagenesis in Pseudomonas putida

2007 ◽  
Vol 189 (15) ◽  
pp. 5504-5514 ◽  
Author(s):  
Signe Saumaa ◽  
Andres Tover ◽  
Mariliis Tark ◽  
Radi Tegova ◽  
Maia Kivisaar
Keyword(s):  
Dna Damage ◽  
Oxidative Damage ◽  
Stationary Phase ◽  
Pseudomonas Putida ◽  
Dna Polymerase ◽  
Oxidative Dna Damage ◽  
Oxidation Products ◽  
Base Substitution ◽  
Repair Enzymes ◽  
Starvation Conditions

ABSTRACT Oxidative damage of DNA is a source of mutation in living cells. Although all organisms have evolved mechanisms of defense against oxidative damage, little is known about these mechanisms in nonenteric bacteria, including pseudomonads. Here we have studied the involvement of oxidized guanine (GO) repair enzymes and DNA-protecting enzyme Dps in the avoidance of mutations in starving Pseudomonas putida. Additionally, we examined possible connections between the oxidative damage of DNA and involvement of the error-prone DNA polymerase (Pol)V homologue RulAB in stationary-phase mutagenesis in P. putida. Our results demonstrated that the GO repair enzymes MutY, MutM, and MutT are involved in the prevention of base substitution mutations in carbon-starved P. putida. Interestingly, the antimutator effect of MutT was dependent on the growth phase of bacteria. Although the lack of MutT caused a strong mutator phenotype under carbon starvation conditions for bacteria, only a twofold increased effect on the frequency of mutations was observed for growing bacteria. This indicates that MutT has a backup system which efficiently complements the absence of this enzyme in actively growing cells. The knockout of MutM affected only the spectrum of mutations but did not change mutation frequency. Dps is known to protect DNA from oxidative damage. We found that dps-defective P. putida cells were more sensitive to sudden exposure to hydrogen peroxide than wild-type cells. At the same time, the absence of Dps did not affect the accumulation of mutations in populations of starved bacteria. Thus, it is possible that the protective role of Dps becomes essential for genome integrity only when bacteria are exposed to exogenous agents that lead to oxidative DNA damage but not under physiological conditions. Introduction of the Y family DNA polymerase PolV homologue rulAB into P. putida increased the proportion of A-to-C and A-to-G base substitutions among mutations, which occurred under starvation conditions. Since PolV is known to perform translesion synthesis past damaged bases in DNA (e.g., some oxidized forms of adenine), our results may imply that adenine oxidation products are also an important source of mutation in starving bacteria.

Impact of the Ser326Cys polymorphism of the OGG1 gene on the level of oxidative DNA damage in patients with colorectal cancer

2018 ◽  
Vol 90 (2) ◽  
pp. 13-15 ◽  
Author(s):  
Jacek Kabzinski ◽  
Anna Walczak ◽  
Adam Dziki ◽  
Michał Mik ◽  
Ireneusz Majsterek
Keyword(s):  
Colorectal Cancer ◽  
Dna Damage ◽  
Oxidative Damage ◽  
Oxidative Dna Damage ◽  
Excision Repair ◽  
Genetic Material ◽  
Control Group ◽  
Ogg1 Gene ◽  
Increased Risk ◽  
Ser326cys Polymorphism

As a result of reactive oxygen species operation, cell damage occurs in both cellular organelles and molecules, including DNA. Oxidative damage within the genetic material can lead to accumulation of mutations and consequently to cancer transformation. OGG1 glycosylase, a component of the Base Excision Repair (BER) system, is one of the enzymes that prevents excessive accumulation of 8-oxoguanine (8-oxG), the most common compound formed by oxidative DNA damage. In case of structural changes of OGG1 resulting from polymorphic variants, we can observe a significant increase in the concentration of 8-oxG. Linking individual polymorphisms to DNA repair systems with increased risk of colorectal cancer will allow patients to be classified as high risk and included in a prophylactic program. The aim of the study was to determine the level of oxidative DNA damage and to analyze the distribution of Ser326Cys polymorphism of the OGG1 gene in a group of patients with colorectal cancer and in a control group in the Polish population. Material and methodology. DNA was isolated from the blood of 174 patients with colorectal cancer. The control group consisted of 176 healthy individuals. The level of oxidative damage was determined by analyzing the amount of 8-oxguanine using the HT 8-oxo-dG ELISA II Kit. Genotyping was performed via the TaqMan method. Results. The obtained results indicate that Ser326Cys polymorphism of the OGG1 gene increases the risk of RJG and is associated with significantly increased levels of 8-oxoguanine. Conclusions. Based on the results obtained, we conclude that Ser326Cys polymorphism of the OGG1 gene may modulate the risk of colorectal cancer by increasing the level of oxidative DNA damage.

Selective Damage to Antioxidant Gene Promoters in FA Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2413-2413
Author(s):  
Wei Du ◽  
Reena Rani ◽  
Jared Sipple ◽  
Jonathan Schick ◽  
Qishen Pang
Keyword(s):  
Oxidative Stress ◽  
Bone Marrow ◽  
Dna Damage ◽  
Oxidative Damage ◽  
Oxidative Dna Damage ◽  
Defense Genes ◽  
Atpase Subunit ◽  
Promoter Complex ◽  
Anti Oxidant ◽  
Promoter Dna

Abstract Abstract 2413 Oxidative stress has been implicated in the pathogenesis of many human diseases including Fanconi anemia (FA), a genetic disorder associated with bone marrow failure and progression to leukemia and other cancers. Here we show that several major anti-oxidant defense genes, including Glutathione peroxidase 1, Peroxiredoxin 3, Thioredoxin reductase 1, Superoxide dismutases 1, NAD(P)H:quinone oxireductase and Catalase, are down-regulated in bone marrow cells of FA patients. This gene down-regulation is selectively associated with increased oxidative DNA damage in the promoters of these anti-oxidant defense genes. Further, we show that both increased initial damage and reduced repair rate contribute to augmented oxidative DNA damage in FA cells. Using cell-based assays to assess promoter activity and damage repair kinetics, we demonstrate that FA proteins function to protect the promoter DNA from oxidative damage. Mechanistically, FA proteins appeared to act in concert with Brg1, a chromatin-remodeling ATPase subunit of the BAF complex. Specifically, Brg1 binds to the promoters of the anti-oxidant defense genes in steady state. Upon challenge with oxidative stress, FANCA and FANCD2 proteins are recruited to the promoter DNA, which correlates with significant increase in the binding of Brg1 within the promoter regions. Intriguingly, the formation of the FA-Brg1-promoter complex results in a marked decrease in nuclease hypersensitivity and oxidative damage in the promoter DNA in normal cells compared to FA cells. Finally, disassociation of the FA proteins from the Brg1-promoter complex parallels Pol II loading, suggesting a regulatory role for the FA proteins in transcription. Taken together, the study identifies a role of FA proteins in protecting anti-oxidant genes from oxidative damage. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Genomic landscape of oxidative DNA damage and repair reveals regioselective protection from mutagenesis

2017 ◽  
Author(s):  
Anna R Poetsch ◽  
Simon J Boulton ◽  
Nicholas M Luscombe
Keyword(s):  
Dna Damage ◽  
Oxidative Damage ◽  
Oxidative Dna Damage ◽  
Molecular Mechanisms ◽  
Accumulation Rate ◽  
Repetitive Sequences ◽  
Open Chromatin ◽  
Regulatory Sequences ◽  
Dna Damage And Repair ◽  
A Genome

AbstractDNA is subject to constant chemical modification and damage, which eventually results in variable mutation rates throughout the genome. Although detailed molecular mechanisms of DNA damage and repair are well-understood, damage impact and execution of repair across a genome remains poorly defined. To bridge the gap between our understanding of DNA repair and mutation distributions we developed a novel method, AP-seq, capable of mapping apurinic sitesand 8-oxo-7,8-dihydroguanine bases at ∼300bp resolution on a genome-wide scale. We directly demonstrate that the accumulation rate of oxidative damage varies widely across the genome, with hot spots acquiring many times more damage than cold spots. Unlike SNVs in cancers, damage burden correlates with marks for open chromatin notably H3K9ac and H3K4me2. Oxidative damage is also highly enriched in transposable elements and other repetitive sequences. In contrast, we observe decreased damage at promoters, exons and termination sites, but not introns, in a seemingly transcription-independent manner. Leveraging cancer genomic data, we also find locally reduced SNV rates in promoters, genes and other functional elements. Taken together, our study reveals that oxidative DNA damage accumulation and repair differ strongly across the genome, but culminate in a previously unappreciated mechanism that safe-guards the regulatory sequences and the coding regions of genes from mutations.

scholarly journals Ginkgo biloba L. Leaf Extract Protects HepG2 Cells Against Paraquat-Induced Oxidative DNA Damage

Plants ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 556 ◽  
Author(s):  
Amélia M. Silva ◽  
Sandra C. Silva ◽  
Jorge P. Soares ◽  
Carlos Martins-Gomes ◽  
João Paulo Teixeira ◽  
...  
Keyword(s):  
Dna Damage ◽  
Oxidative Damage ◽  
Cell Viability ◽  
Ginkgo Biloba ◽  
Hepg2 Cells ◽  
Leaf Extract ◽  
Oxidative Dna Damage ◽  
Leaf Extracts ◽  
Ginkgo Biloba Leaf Extract ◽  
Ginkgo Biloba Leaf

Ginkgo biloba L. leaf extracts and herbal infusions are used worldwide due to the health benefits that are attributed to its use, including anti-neoplastic, anti-aging, neuro-protection, antioxidant and others. The aim of this study was to evaluate the effect of an aqueous Ginkgo biloba extract on HepG2 cell viability, genotoxicity and DNA protection against paraquat-induced oxidative damage. Exposure to paraquat (PQ), over 24 h incubation at 1.0 and 1.5 µM, did not significantly reduce cell viability but induced concentration and time-dependent oxidative DNA damage. Ginkgo biloba leaf extract produced dose-dependent cytotoxicity (IC50 = 540.8 ± 40.5 µg/mL at 24 h exposure), and short incubations (1 h) produced basal and oxidative DNA damage (>750 and 1500 µg/mL, respectively). However, lower concentrations (e.g., 75 µg/mL) of Ginkgo biloba leaf extract were not cytotoxic and reduced basal DNA damage, indicating a protective effect at incubations up to 4 h. On the other hand, longer incubations (24 h) induced oxidative DNA damage. Co-incubation of HepG2 cells for 4 h, with G. biloba leaf extract (75 µg/mL) and PQ (1.0 or 1.5 µM) significantly reduced PQ-induced oxidative DNA damage. In conclusion, the consumption of Ginkgo biloba leaf extract for long periods at high doses/concentrations is potentially toxic; however, low doses protect the cells against basal oxidative damage and against environmentally derived toxicants that induce oxidative DNA damage.

Sign in / Sign up

Export Citation Format

Share Document