• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.438-447
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• 2011

Deinococcus radiodurans is extremely resistant to various genotoxic conditions and chemicals. In this study, we characterized the effect of a sublethal concentration (100 ${\mu}M$) of cadmium (Cd) on D. radiodurans using a whole-genome DNA microarray. Time-course global gene expression profiling showed that 1,505 genes out of 3,116 total ORFs were differentially expressed more than 2-fold in response to Cd treatment for at least one timepoint. The majority of the upregulated genes are related to iron uptake, cysteine biosynthesis, protein disulfide stress, and various types of DNA repair systems. The enhanced upregulation of genes involved in cysteine biosynthesis and disulfide stress indicate that Cd has a high affinity for sulfur compounds. Provocation of iron deficiency and growth resumption of Cd-treated cells by iron supplementation also indicates that CdS forms in iron-sulfur-containing proteins such as the [Fe-S] cluster. Induction of base excision, mismatch, and recombinational repair systems indicates that various types of DNA damage, especially base excision, were enhanced by Cd. Exposure to sublethal Cd stress reduces the growth rate, and many of the downregulated genes are related to cell growth, including biosynthesis of cell membrane, translation, and transcription. The differential expression of 52 regulatory genes suggests a dynamic operation of complex regulatory networks by Cd-induced stress. These results demonstrate the effect of Cd exposure on D. radiodurans and how the related genes are expressed by this stress.

• Journal of Plant Biotechnology
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• v.31 no.3
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• pp.225-230
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• 2004

We employed single cell gel electrophoresis method (comet assay) to analyze the degree of nucleus-DNA damage in the leaves of red pepper (Capsicum annuum L.) seedlings exposed to $^{60}$ CO v-radiation stress. Nucleus-DNA damage was measured as the ratio of tail length (T) to head length (H) in individual comet image isolated from pepper leaf cell. The T/H ratio of control-cells and treated-cells at 50 or 100 Gy were 1.28 and 3.54 or 3.39, respectively, suggesting that nuclei of pepper cells were severely damaged in the integrity of DNA strand by the treatment of enhanced v-radiation. The percentage of head-DNA in control-cells was 76.8%, whereas those of 50 and 100 Gy treated-cells were 55.9% and 59.9%, respectively. Pretreatment of low dose (4 to 20 Gy) radiation to seeds decreased DNA-damage in the leaves of seedlings treated with high dose radiation at 50 or 100 Gy. In this experiment, we developed a sensitive, reliable and rapid method for evaluating genotoxic effect in the nuclei of plant cells by employing comet assay.

• Toxicological Research
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• v.32 no.1
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• pp.21-33
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• 2016

Dichlorodiphenyltrichloroethane (DDT) is still used in certain areas of tropics and subtropics to control malaria and other insect-transmitted diseases. DDT and its metabolites have been extensively studied for their toxicity and carcinogenicity in animals and humans and shown to have an endocrine disrupting potential affecting reproductive system although the effects may vary among animal species in correlation with exposure levels. Epidemiologic studies revealed either positive or negative associations between exposure to DDT and tumor development, but there has been no clear evidence that DDT causes cancer in humans. In experimental animals, tumor induction by DDT has been shown in the liver, lung, and adrenals. The mechanisms of hepatic tumor development by DDT have been studied in rats and mice. DDT is known as a non-genotoxic hepatocarcinogen and has been shown to induce microsomal enzymes through activation of constitutive androstane receptor (CAR) and to inhibit gap junctional intercellular communication (GJIC) in the rodent liver. The results from our previously conducted 4-week and 2-year feeding studies of p,p'-DDT in F344 rats indicate that DDT may induce hepatocellular eosinophilic foci as a result of oxidative DNA damage and leads them to hepatic neoplasia in combination with its mitogenic activity and inhibitory effect on GJIC. Oxidative stress could be a key factor in hepatocarcinogenesis by DDT.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.99-103
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• 2003

An Escherichia coli strain containing the recA promoter that fused to the luxCDABE operon originating from Photorhabdus luminescens was shown to respond sensitively to genotoxic stresses. Two different recombinant bacteria, one (DPDI 657) harboring a plasmid with the recA promoter that fused to the luxCDABE operon, and the other (DPD1710) containing a chromosomally-integrated recA promoter that fused with luxCDABE, were compared and it was found that the sensitivity of 'the two strains was significantly different in terms of their bioluminescent level, response time, and the minimum detectable concentration of a chemical causing DNA damaging stress. DPDI 710, with a chromosomally-integrated single copy, generally led to lower basal luminescence levels, faster responses, increased response ratios, and an enhanced sensitivity to mutagens, when compared to DPD 1657 with a multi-copy plasmid.

• BMB Reports
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• v.50 no.6
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• pp.335-340
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• 2017

Although doxorubicin (Dox)-induced oxidative stress is known to be associated with cytotoxicity, the precise mechanism remains unclear. Genotoxic stress not only generates free radicals, but also affects actin cytoskeleton stability. We showed that Dox-induced RhoA signaling stimulated actin cytoskeleton alterations, resulting in central stress fiber disruption at early time points and cell periphery cortical actin formation at a later stage, in HeLa cells. Interestingly, activation of a cofilin phosphatase, chronophin (CIN), was initially evoked by Dox-induced RhoA signaling, resulting in a rapid phosphorylated cofilin turnover leading to actin cytoskeleton remodeling. In addition, a novel interaction between CIN and $14-3-3{\zeta}$ was detected in the absence of Dox treatment. We demonstrated that CIN activity is quite contrary to $14-3-3{\zeta}$ binding, and the interaction leads to enhanced phosphorylated cofilin levels. Therefore, initial CIN activation regulation could be critical in Dox-induced actin cytoskeleton remodeling through RhoA/cofilin signaling.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.5
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• pp.520-526
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• 2017

Carnosine was recently reported to protect against the DNA damage induced by oxidative stress. In this study, we investigated the protective effect of eel Anguilla japonica carnosine extracts prepared using different methods (heat treatment extracts, HTEs; ion exchange chromatography, IEC; ultrafiltration permeation, UFP) on leukocyte DNA damage using the comet assay. Human leukocytes were incubated with extracts of eel carnosine at concentrations (of 10, 50, $100{\mu}g/mL$), and then subjected to an oxidative stimulus [$200{\mu}M$ hydrogen peroxide ($H_2O_2$)]. Pretreatment of the cells for 30 min with carnosine significantly reduced the genotoxicity of $H_2O_2$ measured as DNA strand breaks. The protective effects of the three types of extract (HTE, IEC, and UFP) increased with concentration. At the highest concentration (100 g/mL). there were no statistical differences in oxidative damage between each extract treatment and PBS-treated negative controls. When leukocytes were incubated with carnosine for 30 min after exposure to $H_2O_2$. the protective ability of each extract changed. Therefore, eel carnosine inhibits the $H_2O_2$ induced damage to cellular DNA in human leukocytes, supporting the protective effect of this compound against oxidative damage.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2001.10a
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• pp.29-44
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• 2001

DNA damage by physical insult including UV and g-radiation might provoke genetic alterations in cells, which is followed by either acute cell death or tumorigenesis. The responsiveness to g-radiation depends on cellular context of target cells. To understand the mechanisms of checkpoint control, repair and cell death following genotoxic stimu]i, cDNA microarray can provide the gene expression profile. To make a profile of gene expression in irradiated Jurkat T cells, we hybridized the cDNA microarray using cDNA from g-irradiated Jurkat T cells. Jurkat T cells were exposed to 4Gy to 16Gy, and total RNA were extracted at 4 to 24 hrs after irradiation. The hybridization of the microarray to fluorescence-labeled cDNA from treated and untreated cells was analyzed by bioinformatic analysis to address relative changes in expression levels of the genes present in the array. Responses varied widely in different time points, suggesting acute stress response and chronic restoration or cell death. From these results we could select 384 genes related to radiation response in Tcells, and radiation response might be different in various types of cells. Using Radchip, we could separate "the exposed" from control PBMCs. We propose that Radchip might be useful to check the radiation research as well as radiation carcinogenesis.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.3
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• pp.975-978
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• 2012

P63 is a gene product required in cell cycle regulation which plays vital roles in tumor differentiation. Aims of the present study were to assess the frequency, pattern, sensitivity and specificity of two p63 protein clones P63 4A4 and P63 4A4+Y4A3 in squamous cell carcinomas (SCCs). Thirty cases of head and neck region SCC diagnosed on the basis of H&E staining were examined along with 60 cases of head and neck region biopsies other than squamous cell carcinoma, negative on H&E staining, were taken as control. Immunostaining was performed on slides according to the Thermo Scientific UltraVision LP detection System. P63 4A4+Y4A3 clone is more sensitive 96.6% in comparison to 86% in P63 4A4 with having greater NPV of 98.3%. The results signify the importance of P63 4A4+Y4A3 marker over the old markers and may be used as a confirmatory marker of squamous cell carcinoma.

• Molecules and Cells
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• v.42 no.7
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• pp.546-556
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• 2019

Protein phosphatase 4 (PP4) is a crucial protein complex that plays an important role in DNA damage response (DDR), including DNA repair, cell cycle arrest and apoptosis. Despite the significance of PP4, the mechanism by which PP4 is regulated remains to be elucidated. Here, we identified a novel PP4 inhibitor, protein phosphatase 4 inhibitory protein (PP4IP) and elucidated its cellular functions. PP4IP-knockout cells were generated using the CRISPR/Cas9 system, and the phosphorylation status of PP4 substrates (H2AX, KAP1, and RPA2) was analyzed. Then we investigated that how PP4IP affects the cellular functions of PP4 by immunoprecipitation, immunofluorescence, and DNA double-strand break (DSB) repair assays. PP4IP interacts with PP4 complex, which is affected by DNA damage and cell cycle progression and decreases the dephosphorylational activity of PP4. Both overexpression and depletion of PP4IP impairs DSB repairs and sensitizes cells to genotoxic stress, suggesting timely inhibition of PP4 to be indispensable for cells in responding to DNA damage. Our results identify a novel inhibitor of PP4 that inhibits PP4-mediated cellular functions and establish the physiological importance of this regulation. In addition, PP4IP might be developed as potential therapeutic reagents for targeting tumors particularly with high level of PP4C expression.

• Environmental Analysis Health and Toxicology
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• v.22 no.4
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• pp.357-366
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• 2007

To investigate the possible enhancement of genotoxicity in stress environment, we examined the of effect of genotoxic material in oxidative stress-induced condition using human tell line. Human lymphoblast cell line, TK6 was treated with hydrogen peroxide ($H_2O_2$) for induction of oxidative stress, and treated with N'-methyl-N'-nitroguanidine (MNNG), af a genetoxic material. We carried out MTS assay to set treatment doses. TK6 was treated with $H_2O_2$ at 6.75 (low dote) or $13.5\;{\mu}M$ (high dose) for 2 h, and treated with MNNG af 0.117 (low dose), 0.234 (middle dose), $0.468\;{\mu}M$ (high dose) for 2 h. As results, a treatment of MNNG induced DNA dam age as dose dependently. And TK6 treated with $H_2O_2$ at low as well as high dose followed by MNNG treatment showed higher DNA damage compared to MNNG alone treated groups. Malondialdehyde, as a marker of lipid peroxidation was increased in $H_2O_2$ and MNNG treated groups. Real-time RT-PCR analyses for expression of several antioxidative enzymes showed that catalase mRNA and glutathione peroxidase 1 mRNA expression were decreased in $H_2O_2$ and MNNG treated groups. Taken together, we conclude that genotoxicity induced by MNNG is enhanced in a condition of oxidative stress induced by $H_2O_2$ and it suggests that it should be associated with induction of lipid peroxidation and decrease of antioxidant enzymes.