Baicalein (5,6,7-trihydroxyflavone) reduces oxidative stress-induced DNA damage by upregulating the DNA repair system

Mediator 17 (MED17) is a subunit of the Mediator complex that regulates transcription initiation in eukaryotic organisms. In yeast and humans, MED17 also participates in DNA repair, physically interacting with proteins of the Nucleotide Excision DNA Repair system. We here analyzed the role of MED17 in Arabidopsis plants exposed to UV-B radiation, which role has not been previously described. Comparison of med17 mutant transcriptome to that of WT plants showed that almost one third of transcripts with altered expression in med17 plants are also changed by UV-B exposure in WT plants. To validate the role of MED17 in UV-B irradiated plants, plant responses to UV-B were analyzed, including flowering time, DNA damage accumulation and programmed cell death in the meristematic cells of the root tips. Our results show that med17 and OE MED17 plants have altered responses to UV-B; and that MED17 participates in various aspects of the DNA damage response (DDR). Increased sensitivity to DDR after UV-B in med17 plants can be due to altered regulation of UV-B responsive transcripts; but additionally MED17 physically interacts with DNA repair proteins, suggesting a direct role of this Mediator subunit during repair. Finally, we here also show that MED17 is necessary to regulate the DDR activated by ATR, and that PDCD5 overexpression reverts the deficiencies in DDR shown in med17 mutants. Together, the data presented demonstrates that MED17 is an important regulator of the DDR after UV-B radiation in Arabidopsis plants.

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Aging and oxidative stress alter DNA repair mechanisms in male germ cells of superoxide dismutase-1 null mice

Biology of Reproduction ◽

10.1093/biolre/ioab114 ◽

2021 ◽

Author(s):

Paulina Nguyen-Powanda ◽

Bernard Robaire

Keyword(s):

Oxidative Stress ◽

Dna Damage ◽

Dna Repair ◽

Superoxide Dismutase ◽

Germ Cells ◽

Superoxide Dismutase 1 ◽

Male Germ Cells ◽

Dna Repair Mechanisms ◽

Repair Mechanisms ◽

And Oxidative Stress

Abstract The efficiency of antioxidant defense system decreases with aging, thus resulting in high levels of reactive oxygen species (ROS) and DNA damage in spermatozoa. This damage can lead to genetic disorders in the offspring. There are limited studies investigating the effects of the total loss of antioxidants, such as superoxide dismutase-1 (SOD1), in male germ cells as they progress through spermatogenesis. In this study, we evaluated the effects of aging and removing SOD1 (in male germ cells of SOD1-null (Sod1−/−) mice) in order to determine the potential mechanism(s) of DNA damage in these cells. Immunohistochemical analysis showed an increase in lipid peroxidation and DNA damage in the germ cells of aged wild-type (WT) and Sod1−/− mice of all age. Immunostaining of OGG1, a marker of base excision repair (BER), increased in aged WT and young Sod1−/− mice. In contrast, immunostaining intensity of LIGIV and RAD51, markers of non-homologous end-joining (NHEJ) and homologous recombination (HR), respectively, decreased in aged and Sod1−/− mice. Gene expression analysis showed similar results with altered mRNA expression of these key DNA repair transcripts in pachytene spermatocytes and round spermatids of aged and Sod1−/− mice. Our study indicates that DNA repair pathway markers of BER, NHEJ, and HR are differentially regulated as a function of aging and oxidative stress in spermatocytes and spermatids, and aging enhances the repair response to increased oxidative DNA damage, whereas impairments in other DNA repair mechanisms may contribute to the increase in DNA damage caused by aging and the loss of SOD1.

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Evaluation of DNA Damage, DNA Repair, Oxidative Stress, and Cell Death Caused by Helicobacter pylori in Human Adenocarcinoma Cells

SSRN Electronic Journal ◽

10.2139/ssrn.3972034 ◽

2021 ◽

Author(s):

DİDEM ORAL ◽

ÜNZİLE SUR ◽

gizem özkemahlı ◽

Anıl Yirüna ◽

N. DİLARA ZEYBEK ◽

...

Keyword(s):

Oxidative Stress ◽

Dna Damage ◽

Cell Death ◽

Dna Repair ◽

Helicobacter Pylori ◽

Adenocarcinoma Cells

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Dynamic Compartmentalization of Base Excision Repair Proteins in Response to Nuclear and Mitochondrial Oxidative Stress

Molecular and Cellular Biology ◽

10.1128/mcb.01357-08 ◽

2008 ◽

Vol 29 (3) ◽

pp. 794-807 ◽

Cited By ~ 31

Author(s):

Lyra M. Griffiths ◽

Dan Swartzlander ◽

Kellen L. Meadows ◽

Keith D. Wilkinson ◽

Anita H. Corbett ◽

...

Keyword(s):

Oxidative Stress ◽

Dna Damage ◽

Dna Repair ◽

Base Excision Repair ◽

Oxidative Dna Damage ◽

Excision Repair ◽

Intracellular Localization ◽

Genotoxic Stress ◽

Mitochondrial Oxidative Stress ◽

Base Excision

ABSTRACT DNAs harbored in both nuclei and mitochondria of eukaryotic cells are subject to continuous oxidative damage resulting from normal metabolic activities or environmental insults. Oxidative DNA damage is primarily reversed by the base excision repair (BER) pathway, initiated by N-glycosylase apurinic/apyrimidinic (AP) lyase proteins. To execute an appropriate repair response, BER components must be distributed to accommodate levels of genotoxic stress that may vary considerably between nuclei and mitochondria, depending on the growth state and stress environment of the cell. Numerous examples exist where cells respond to signals, resulting in relocalization of proteins involved in key biological transactions. To address whether such dynamic localization contributes to efficient organelle-specific DNA repair, we determined the intracellular localization of the Saccharomyces cerevisiae N-glycosylase/AP lyases, Ntg1 and Ntg2, in response to nuclear and mitochondrial oxidative stress. Fluorescence microscopy revealed that Ntg1 is differentially localized to nuclei and mitochondria, likely in response to the oxidative DNA damage status of the organelle. Sumoylation is associated with targeting of Ntg1 to nuclei containing oxidative DNA damage. These studies demonstrate that trafficking of DNA repair proteins to organelles containing high levels of oxidative DNA damage may be a central point for regulating BER in response to oxidative stress.

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Kaempferol Induces DNA Damage and Inhibits DNA Repair Associated Protein Expressions in Human Promyelocytic Leukemia HL-60 Cells

The American Journal of Chinese Medicine ◽

10.1142/s0192415x1550024x ◽

2015 ◽

Vol 43 (02) ◽

pp. 365-382 ◽

Cited By ~ 20

Author(s):

Lung-Yuan Wu ◽

Hsu-Feng Lu ◽

Yu-Cheng Chou ◽

Yung-Luen Shih ◽

Da-Tian Bau ◽

...

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Protein Expression ◽

Ataxia Telangiectasia ◽

Repair System ◽

Dapi Staining ◽

Viable Cells ◽

Protein Expressions ◽

Dose Dependent

Numerous evidences have shown that plant flavonoids (naturally occurring substances) have been reported to have chemopreventive activities and protect against experimental carcinogenesis. Kaempferol, one of the flavonoids, is widely distributed in fruits and vegetables, and may have cancer chemopreventive properties. However, the precise underlying mechanism regarding induced DNA damage and suppressed DNA repair system are poorly understood. In this study, we investigated whether kaempferol induced DNA damage and affected DNA repair associated protein expression in human leukemia HL-60 cells in vitro. Percentages of viable cells were measured via a flow cytometry assay. DNA damage was examined by Comet assay and DAPI staining. DNA fragmentation (ladder) was examined by DNA gel electrophoresis. The changes of protein levels associated with DNA repair were examined by Western blotting. Results showed that kaempferol dose-dependently decreased the viable cells. Comet assay indicated that kaempferol induced DNA damage (Comet tail) in a dose-dependent manner and DAPI staining also showed increased doses of kaempferol which led to increased DNA condensation, these effects are all of dose-dependent manners. Western blotting indicated that kaempferol-decreased protein expression associated with DNA repair system, such as phosphate-ataxia-telangiectasia mutated (p-ATM), phosphate-ataxia-telangiectasia and Rad3-related (p-ATR), 14-3-3 proteins sigma (14-3-3σ), DNA-dependent serine/threonine protein kinase (DNA-PK), O6-methylguanine-DNA methyltransferase (MGMT), p53 and MDC1 protein expressions, but increased the protein expression of p-p53 and p-H2AX. Protein translocation was examined by confocal laser microscopy, and we found that kaempferol increased the levels of p-H2AX and p-p53 in HL-60 cells. Taken together, in the present study, we found that kaempferol induced DNA damage and suppressed DNA repair and inhibited DNA repair associated protein expression in HL-60 cells, which may be the factors for kaempferol induced cell death in vitro.

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The Dark Side of UV-Induced DNA Lesion Repair

Genes ◽

10.3390/genes11121450 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1450

Author(s):

Wojciech Strzałka ◽

Piotr Zgłobicki ◽

Ewa Kowalska ◽

Aneta Bażant ◽

Dariusz Dziga ◽

...

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Uv Light ◽

Genetic Material ◽

Dna Lesions ◽

Dark Side ◽

Repair System ◽

Strand Breaks ◽

Dna Lesion ◽

Pyrimidine Dimers

In their life cycle, plants are exposed to various unfavorable environmental factors including ultraviolet (UV) radiation emitted by the Sun. UV-A and UV-B, which are partially absorbed by the ozone layer, reach the surface of the Earth causing harmful effects among the others on plant genetic material. The energy of UV light is sufficient to induce mutations in DNA. Some examples of DNA damage induced by UV are pyrimidine dimers, oxidized nucleotides as well as single and double-strand breaks. When exposed to light, plants can repair major UV-induced DNA lesions, i.e., pyrimidine dimers using photoreactivation. However, this highly efficient light-dependent DNA repair system is ineffective in dim light or at night. Moreover, it is helpless when it comes to the repair of DNA lesions other than pyrimidine dimers. In this review, we have focused on how plants cope with deleterious DNA damage that cannot be repaired by photoreactivation. The current understanding of light-independent mechanisms, classified as dark DNA repair, indispensable for the maintenance of plant genetic material integrity has been presented.

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Physiological Responses of the Hyperthermophilic Archaeon “Pyrococcus abyssi” to DNA Damage Caused by Ionizing Radiation

Journal of Bacteriology ◽

10.1128/jb.185.13.3958-3961.2003 ◽

2003 ◽

Vol 185 (13) ◽

pp. 3958-3961 ◽

Cited By ~ 26

Author(s):

Edmond Jolivet ◽

Fujihiko Matsunaga ◽

Yoshizumi Ishino ◽

Patrick Forterre ◽

Daniel Prieur ◽

...

Keyword(s):

Dna Damage ◽

Dna Repair ◽

Ionizing Radiation ◽

Dna Synthesis ◽

Gamma Ray ◽

Pyrococcus Furiosus ◽

Repair System ◽

Cell Fractionation ◽

Chromosomal Dna ◽

Pyrococcus Abyssi

ABSTRACT The mechanisms by which hyperthermophilic Archaea, such as “Pyrococcus abyssi” and Pyrococcus furiosus, survive high doses of ionizing gamma irradiation are not thoroughly elucidated. Following gamma-ray irradiation at 2,500 Gy, the restoration of “P. abyssi” chromosomes took place within chromosome fragmentation. DNA synthesis in irradiated “P. abyssi” cells during the DNA repair phase was inhibited in comparison to nonirradiated control cultures, suggesting that DNA damage causes a replication block in this organism. We also found evidence for transient export of damaged DNA out of irradiated “P. abyssi” cells prior to a restart of chromosomal DNA synthesis. Our cell fractionation assays further suggest that “P. abyssi” contains a highly efficient DNA repair system which is continuously ready to repair the DNA damage caused by high temperature and/or ionizing radiation.

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