• Journal of Photoscience
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• v.10 no.2
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• pp.195-198
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• 2003

In the cellular response to DNA damaging agents, cells undergo cell cycle arrest or apoptosis against irrepairable DNA damage. RpS3 is known to function as UV DNA repair endonuclease III and ribosomal protein S3. In this study, we used normal and rpS3-overexpressed 293T cells to examine the role of rpS3 in response to DNA damaging agents. When 293T cells transfected with rpS3 were irradiated with UV, the pattern of cell cycle was dramatically changed in comparison with un-transfected 293T cells. We also found that the expression of rpS3 in normal cells was increased by treatment with DNA damaging agents. By means of Western and Northern blot analyses in rat tissues, we showed the expression pattern of rpS3 protein and its mRNA. These data suggest that DNA repair and cell cycle arrest are interrelated to each other through rpS3, and the increased expression of rpS3 seems to regulate the cell cycle arrest by DNA damaging agents.

• The Korean Journal of Zoology
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• v.37 no.2
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• pp.232-239
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• 1994

RecA protein plans a central role in homologous recombination and DNA repair in Escherichia cofi (E. colD. The function 8nd structure of this protein are universal in prokarvotes and also conserved in eukaryotes such as yeast. The RecA-like protein with 74 lInDa in size has already been identified and purified from a fission yeast Schizosaccharomyces pombe (5. pommel (Lee, 19911. From this study it was revealed that the RecA-like protein of 5. pombe was highly inducible to various DNA damaging agents and inhibitors of nucleotide pool svnthesizins enzymes. The cellular level of the 5. pombe RecA-like protein wi,u markedly increased, upto 5- to 10-fold, by treatment with various DNA-damains agents including ultraviolet (UV) light, methyl methanesulfonate WS),4-nitroquinoline-1-oxide (4-NQO), and mitomycin-C (MMC), similar to E. cofi RecA protein. Interestingly, the protein level was also increased by inhibitors of nucleotide pool forming enzlwnes such as methotrexate (MTX) and hvdroxvurea (HU). The most effective doses for the inducibility of 4-NQO, MMS, W, MMC, MTX, and HU were 0.2 Ug/ml, 30 mM, 200 J/ma, 0.4 $\mus/ml,$ 1 Ug/ml, and 100 mM, respectively. The range of effective duration time for the inducibilitv of RecA-like protein was from 270 to 450 mins. These results suggest that the 5. pombe RecA-like protein also platys an imortant role in cellular responses to DNA damage as in E. coli system.

• Molecules and Cells
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• v.39 no.3
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• pp.204-210
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• 2016

DNA damage responses are important for the maintenance of genome stability and the survival of organisms. Such responses are activated in the presence of DNA damage and lead to cell cycle arrest, apoptosis, and DNA repair. In Caenorhabditis elegans, double-strand breaks induced by DNA damaging agents have been detected indirectly by antibodies against DSB recognizing proteins. In this study we used a comet assay to detect DNA strand breaks and to measure the elimination of DNA strand breaks in mitotic germline nuclei of C. elegans. We found that C. elegans brc-1 mutants were more sensitive to ionizing radiation and camptothecin than the N2 wild-type strain and repaired DNA strand breaks less efficiently than N2. This study is the first demonstration of direct measurement of DNA strand breaks in mitotic germline nuclei of C. elegans. This newly developed assay can be applied to detect DNA strand breaks in different C. elegans mutants that are sensitive to DNA damaging agents.

• Journal of Life Science
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• v.15 no.2 s.69
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• pp.192-196
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• 2005

The SNF2/SW12 family comprises proteins from a variety of species with in vivo functions, such as transcriptional regulation, maintenance of chromosome stability during mitosis, and various types of DNA repair. This study was shown the characterization of hrp2+ gene which was isolated by PCR amplification using the conserved domain of SNF2 motifs. Sequence analysis of hrp2+ gene showed striking evolutionary conservation among the SNF2 family of proteins. The transcript of hrp2+ gene was found to be a 4.7 kb as identified by Northern hybridization. To investigate the inducibility of hrp2+ gene, transcript levels were examined after treating the cells to various DNA damaging agents. The transcripts of hrp2+ were induced by UV-irradiation. But the transcripts were not induced by treatment of $ 0.25\%$ Methylmethane sulfonate (MMS). These results implied that the effects of damaging agents are complex and different regulatory pathways exist for the induction of this gene. Hrp2 protein was purified near homogeneity by combination of affinity chromatography. We tested the purified Hrp2 protein for the helicase activity in an oligonucleotide release assay. However we were unable to detect any helicase activity associated with the Hrp2 protein, indicating that the helicase motifs in Hrp2 are merely indicators of a broader DNA-dependent ATPase activity.

• Biotechnology and Bioprocess Engineering:BBE
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• v.4 no.1
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• pp.59-62
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• 1999

The recombinant bacteria strain DPD2540, containing a fabA::luxCDABE fusion, was used to detect the toxicity of various chemicals in this study. Membrane damaging agents such as phenol, ethanol, and cerulenin induced a rapid bioluminescent response from this strain. Other toxic agents, such as DNA-damaging or oxidative-damaging chemicals, showed a delayed bioluminescent response in which the maximum peak appeared over 150 min after induction. This strain was also tested for measurement of toxicity in field samples such as wastewater and river water effluents.

• Journal of Life Science
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• v.11 no.1
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• pp.52-56
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• 2001

The present study intends to characterize the DNA damage-inducible responses in eukaryotic cells. The fission yeast, S. pombe, which displays efficient DNA repair systems, was used in this study as a model system for higher eukaryotes. To study UV-inducible responses in S. pombe, five UV-inducible cDNA clones were isolated from S. pombe by using subtration hybridization method. To investigate the expression of isolated genes, the cellular levels of the transcripts of these genes were determined by Northern blot analysis after UV-irradiation. The transcripts of isolated gene (UV130) increased rapidly and reached maximum accumulation after UV-irradiation. Compared to the message levels of control, the levels of maximal increase were approximately 5 fold to UV-irradiation. In order to investigation whether the increase of UV130 transcripts was a specific results of UV-irradiation, UV130 transcript levels were examined after treating the cells to Methylmethane sulfonate (MMS). The transcripts of UV130 were not induced by treatment of 0.25% MMS. These results implied that the effects of damaging agents are complex and different regulatory pathways exist for the induction of these genes. To characterize the structure of UV130 gene, nucleotide sequences were analyzed. The nucleotide sequence of 1,340 nucleotide excluding poly(A) tail contains one open reading frame, which encodes a protein of 270 amino acids. The predicted amino acid sequences of UV130 do not exhibit any significant similarity to ther known sequences in the database.

• Animal cells and systems
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• v.2 no.3
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• pp.383-388
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• 1998

A RecA-like protein (RecAps) was identified from fluorescent Pseudomonas sp. and the inducible nature of the protein was characterized in detail. It was shown by dose-response and time-course experiments using two DNA damaging agents, nalidixic acid and mitomycin-C, that the cellular level of RecAps protein was increased 3-8 fold compared to that of the control. The most effective doses of nalidixic acid and mitomycin-C for the protein induction were $30{\mu}g/ml$ and $0.3{\mu}g/ml$ at the treatment time point of 150 min, respectively. The enhanced level of RecAps protein was gradually decreased to the control level after 10 hr in normal medium. Interestingly, the cellular level of RecAps protein was increased by the same DNA damaging agents even when cell growth was completely inhibited by treatment with $170{\mu}g/ml$ of chloramphenicol, an inhibitor of protein synthesis, suggesting that new protein synthesis is not required for the induction of RecAps. All these results suggest that a typical S0S repair function driven by RecA-like protein is conserved in Pseudomonas sp. cells as in E, coli.

• YAKHAK HOEJI
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• v.36 no.6
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• pp.582-590
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• 1992

S. pneumoniae recP mutant was compared with rec-8 mutant to identify whether they are the same gene or not by determining sensitivity to DNA damaging agents. recP and rec-8 mutant have almost same sensitivity to UV, ethylmethane sulfonate, and methylmethane sulfonate, suggesting that recP has the same function as the rec-8 gene in DNA repair.

• Molecular & Cellular Toxicology
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• v.1 no.1
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• pp.26-31
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• 2005

The detection and the regulation of man-made synthetic chemicals and the establishment of toxicity that may pose a genetic hazard in our environment are subjects of great concern because of its close correlation between environmental contamination and human health. Since the tens of thousands of man-made chemicals that have been introduced into the environment in the last few decades must also be tested for their damaging effect on DNA, the agents that cause this damage must be identified.

• Environmental Mutagens and Carcinogens
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• v.22 no.3
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• pp.137-141
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• 2002

The SNF2/SW12 family comprises proteins from a variety of species with in vivo functions, such as transcriptional regulation, maintenance of chromosome stability during mitosis, and various types of DNA repair. This study was shown the characterization of hrp2+ gene which was isolated by PCR amplification using the conserved domain of SNF2 motifs. Sequence analysis of hrp2+ gene showed striking evolutionary conservation among the SNF2 family of proteins. The transcript of hrp2+ gene was found to be a 4.7 kb as identified by Northern hybridization. In addition, to determine the transcription initiation site of hrp2+ gene, primer extension analysis was performed. This result showed the band of 64 bp. The transcriptional start point was mapped to a position of 47 base pair from the first ATG codon of translational initiation codon. In order to investigate the inducibility of hrp2+ gene, transcript levels were examined after treating the cells to various DNA damaging agents. The transcripts of hrp2+ were induced by UV-irradiation. But the transcripts were not induced by treatment of 0.25% Methylmethane sulfonate (MMS). These results implied that the effects of damaging agents are complex and different regulatory pathways exist for the induction of this gene.