• Toxicological Research
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• 제34권4호
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• pp.297-302
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• 2018

Cells are constantly exposed to endogenous and exogenous chemical and physical agents that damage their genome by forming DNA lesions. These lesions interfere with the normal functions of DNA such as transcription and replication, and need to be either repaired or tolerated. DNA lesions are accurately removed via various repair pathways. In contrast, tolerance mechanisms do not remove lesions but only allow replication to proceed despite the presence of unrepaired lesions. Cells possess two major tolerance strategies, namely translesion synthesis (TLS), which is an error-prone strategy and an accurate strategy based on homologous recombination (homology-dependent gap repair [HDGR]). Thus, the mutation frequency reflects the relative extent to which the two tolerance pathways operate in vivo. In the present paper, we review the present understanding of the mechanisms of TLS and HDGR and propose a novel and comprehensive view of the way both strategies interact and are regulated in vivo.

• Molecules and Cells
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• 제40권2호
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• pp.83-89
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• 2017

Error-free replication and repair of DNA are pivotal to organisms for faithful transmission of their genetic information. Cells orchestrate complex signaling networks that sense and resolve DNA damage. Post-translational protein modifications by ubiquitin and ubiquitin-like proteins, including SUMO and NEDD8, are critically involved in DNA damage response (DDR) and DNA damage tolerance (DDT). The expression of interferon-stimulated gene 15 (ISG15), the first identified ubiquitin-like protein, has recently been shown to be induced under various DNA damage conditions, such as exposure to UV, camptothecin, and doxorubicin. Here we overview the recent findings on the role of ISG15 and its conjugation to target proteins (e.g., p53,$ {\Delta}Np63{\alpha}$, and PCNA) in the control of cellular responses to genotoxic stress, such as the inhibition of cell growth and tumorigenesis.

• Asian-Australasian Journal of Animal Sciences
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• 제19권9호
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• pp.1335-1341
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• 2006

We selected a Lactobacillus spp. from Korean healthy infant feces based upon their antioxidant activity. This strain was identified as Lactobacillus gasseri by 16S rDNA sequencing, and named Lactobacillus gasseri NLRI-312. In the present study, we investigate the protective effect of this strain on the $H_2O_2$ induced damage to cellular membrane lipid and DNA in Jurkat cells. To estimate the extent of cellular lipid peroxidation inhibition, MDA (malondialdehyde) was measured, and DNA damage was tested by the comet assay. We also examined probiotic properties including tolerance to acid and bile, antibiotic resistance. From the results obtained, the supplementation of Jurkat cells with NLRI-312 decreased in DNA damage, while no effect was shown on MDA decrease. In probiotic properties, this strain was resistance to both acid and bile, showed considerably higher survival when incubated in pH 2 or 1% bile salts (w/v). We concluded that the NLRI-312 could be used as potential probiotic bacteria, with the effect of reducing DNA damage induced by $H_2O_2$.

• 생명과학회지
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• 제14권4호
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• pp.614-619
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• 2004

This study was undertaken to investigate the different responses of cultured plant cells to paraquat treatment and nucleus-DNA damage in relation to enzyme activity of superoxide dismutase (SOD). Furthermore, this study was also carried out to understand the antioxidative mechanism of plant cells to environmental stress. We selected two different species of plant cultured cells, Ipomoea batatas as high-SOD species and Lonicera japonica as low-SOD species. The total activity and specific activity of SOD in a chlorophyllous cell of I. batatas were 3,736 unit/gㆍfresh weight and 547 unit/mgㆍprotein, respectively, and those in L. japonica were 23 unit/gㆍfresh weight and 13 unit/mgㆍprotein, respectively SOD activity in chlorophyllous I. batatas cells reached its maximum level at 10 to 15 days after subculture, whereas that in L. japonica remained at a very low SOD level during the whole period of subculture. In comparison to L. japonica, I. batatas, a high-SOD species, showed high tolerance to paraquat 10 and 50 mg/l treatment in terms of cell viability and electrolyte leakage. Based on the result of comet assay, the nucleus-DNA damage of two species by paraquat 50 mg/l treatment was not significantly different. However, I. batatas cells repaired their damaged DNA more effectively than the cells of the low-SOD species, L. japonica.

• Advances in Traditional Medicine
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• 제9권1호
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• pp.39-48
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• 2009

We have evaluated the effect of long term treatment of Enicostemma littorale (E. littorale) in type 2 diabetic patients taking pills of aqueous extract of E. littorale regularly as a complimentary medicine for at least 9 months. The effects of E. littorale on glycemic control, lipid profile, cardiac function and DNA damage in these patients were compared with those who had not been regular in taking E. littorale but regular in taking other conventional anti-diabetics. Our data suggest that, E. littorale can maintain normal blood glucose, serum insulin, serum triglycerides levels of type 2 diabetic patients if taken regularly. E. littorale also improves insulin sensitivity, and normalize disturbed lipogram and elevated creatinine levels, thereby produces beneficial effect in preventing cardiovascular complications and may preserve the kidney function. The finding that E. littorale also prevents DNA damage suggest a long term effect in diabetic patients. E. littorale thus can be considered as safe supplementary therapy for a long term and effective management of type 2 diabetic patients.

• Journal of Plant Biotechnology
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• 제43권3호
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• pp.376-382
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• 2016

DNA methylation은 무수히 많이 발생하는 생리적 및 병리적 측면의 과정에서 관련 유전자의 발현을 조절함으로써 중추적인 역할을 가지고 있다. 본 연구에서는 NtROS2a가 과발현된 형질전환 벼를 육성하고, 그들의 형태적 측면을 관찰하고 스트레스 내성을 검토하였다. 형질전환 식물체는 WT에 비하여 신초의 신장이 작게 나타났다. 저온 스트레스 처리 하에서 NtROS2a 형질전환 벼는 스트레스로 인한 생육 불량을 보였으나 건조 스트레스 처리 하에서는 WT보다는 높은 비율로 회복하여 생존하는 것을 확인할 수 있었다. 이러한 결과는 NtROS2a 유전자의 과발현으로 인해 벼가 건조 스트레스에 노출되면 내성을 증진시킨 것으로 생각된다.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book I
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• pp.338-351
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• 2003

UV radiation is the most dangerous stress factor among permanent environmental impacts on human skin. Consequences of UV exposure are aberrant tissue architecture, alterations in skin cells including functional changes. Nowadays new kinds of outdoor leisure-time activities and changing environmental conditions make the question of sun protection more important than ever. It is necessary to recognize that self-confident consumers do not consider to change their way of life, they demand modern solutions on the basis of new scientific developments. In the past one fundamental principle of cosmetics was the use of physical and organic filter systems against damaging UV-rays. Today new research results demonstrate that natural protecting cell mechanisms can be activated. Suitable biological actives strongly support the protection function not from the surface but from the inside of the cell. A soy seed preparation (SSP) was proven to stimulate natural skin protective functions. The major functions are an increased energy level and the prevention of DNA damage. These functions can I be defined as biological UV protection. The tumor suppressor protein p53 plays a key role in the regulation of DNA repair. p53 must be transferred into the phosphorylated form to work as transcription factor for genes which are regulating the cell cycle or organizing DNA repair. A pretreatment with SSP increases the phosphorylation rate of p53 of chronically UV-irradiated human keratinocytes significantly. According to the same test procedure SSP induces a dramatic increase in the expression of the tumor suppressor protein p14$^{ARF}$ that is supporting the p53 activity by blocking the antagonist of p53, the oncoprotein Mdm2. Mdm2, a ubiquitin E3-ligase, downregulates p53 and at the same time it prevents phosphorylation of p53. The positive influence of the tumor suppressor proteins explains the stimulation of DNA repair and prevention of sunburn cell formation by SSP, which was proven in cell culture experiments. In vivo the increased skin tolerance against UV irradiation by SSP could be confirmed too. We have assumed, that an increased repair potential provides full cell functionality.y.

• 생명과학회지
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• 제11권5호
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• pp.464-469
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• 2001

내염성의 광합성 cyanobateria 인 Aphanothece halophytica로 부터 molecular chaperone으로 가능하는 HSP70 homolog인 dnaK2 유전자를 cloning 하였다. 이 danK2 유전자는 616개의 아미노산으로 구성되었으며 추정되는 분자량 68 kDa 의 단백질을 code하고 있었다. 아미노산 서열로부터 추정되는 DnaK2 단백질의 구조를 분석하여 본 결과, 다른 원핵생물의 DanK2 단백질들이 공통적으로 갖는 특성인 N-terminal ATPase domain과 C-terminal의 peptide-binding domain이 잘 보존되어 있었으며, 다른 HSP70/DanK 단백질들과의 높은은 상동성을 나타내었다. 한편 danK2 유전자는 생장온도인 28$^{\circ}C$에서 낮은 수준으로 구성적으로 발현하였으며 heat stress에 의해 그 발현량이 급격히 증가하였다. 또한 A. halophytica를 고농도의 염 스트레스로 처리한 결과, heat stress가 없음에도 불구하고 그 발현량이 급격히 증가하였다. 이러한 결과들은 DnaK 단백질의 고온 또는 염 스트레스에 따른 세포의 손상을 보호하기 위하여 중요한 기능을 담당하고 있기 때문에 추정된다.

• Molecules and Cells
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• 제41권5호
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• pp.413-422
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• 2018

Soybean transgenic plants with ectopically expressed AtABF3 were produced by Agrobacterium-mediated transformation and investigated the effects of AtABF3 expression on drought and salt tolerance. Stable Agrobacterium-mediated soybean transformation was carried based on the half-seed method (Paz et al. 2006). The integration of the transgene was confirmed from the genomic DNA of transformed soybean plants using PCR and the copy number of transgene was determined by Southern blotting using leaf samples from $T_2$ seedlings. In addition to genomic integration, the expression of the transgenes was analyzed by RT-PCR and most of the transgenic lines expressed the transgenes introduced. The chosen two transgenic lines (line #2 and #9) for further experiment showed the substantial drought stress tolerance by surviving even at the end of the 20-day of drought treatment. And the positive relationship between the levels of AtABF3 gene expression and drought-tolerance was confirmed by qRT-PCR and drought tolerance test. The stronger drought tolerance of transgenic lines seemed to be resulted from physiological changes. Transgenic lines #2 and #9 showed ion leakage at a significantly lower level (P < 0.01) than ${\underline{n}}on-{\underline{t}}ransgenic$ (NT) control. In addition, the chlorophyll contents of the leaves of transgenic lines were significantly higher (P < 0.01). The results indicated that their enhanced drought tolerance was due to the prevention of cell membrane damage and maintenance of chlorophyll content. Water loss by transpiration also slowly proceeded in transgenic plants. In microscopic observation, higher stomata closure was confirmed in transgenic lines. Especially, line #9 had 56% of completely closed stomata whereas only 16% were completely open. In subsequent salt tolerance test, the apparently enhanced salt tolerance of transgenic lines was measured in ion leakage rate and chlorophyll contents. Finally, the agronomic characteristics of ectopically expressed AtABF3 transgenic plants ($T_2$) compared to NT plants under regular watering (every 4 days) or low rate of watering condition (every 10 days) was investigated. When watered regularly, the plant height of drought-tolerant line (#9) was shorter than NT plants. However, under the drought condition, total seed weight of line #9 was significantly higher than in NT plants (P < 0.01). Moreover, the pods of NT plants showed severe withering, and most of the pods failed to set normal seeds. All the evidences in the study clearly suggested that overexpression of the AtABF3 gene conferred drought and salt tolerance in major crop soybean, especially under the growth condition of low watering.

• Journal of Applied Biological Chemistry
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• 제58권4호
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• pp.325-332
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• 2015

유채는 월동작물로 내한성이 약해 남부지역에서만 재배가 가능하다. 따라서 재배면적 확대 및 안정적 생산성 확보를 위해 내한성 증진 품종 육성이 절실하다. 본 연구에서는 유채의 내한성을 증진시키기 위해 보리에서 유래한 HvIRIP 유전자를 CaMV35S 프로모터 조절하에서 전신발현되도록 운반체를 제작하였고, 아그로박테리움을 이용하여 유채에 형질전환하였다. Southern 분석을 통해 HvIRIP 유전자가 유채 Genome 안으로 전이 되었음을 확인하였다. 또한 Northern 분석을 통해 $4^{\circ}C$에서 2주간 처리된 유묘에서 HvIRIP 유전자의 발현이 크게 증대되는 것을 알 수 있었다. 본엽 3-4매 전개 유채 형질전환체를 영하 $5^{\circ}C$에서 2일간 저온에 노출한 후 회복여부를 조사한 결과, 대조구는 회복하지 못하고 죽은 반면, 형질전환체는 회복이 정상적으로 이루어졌다. 또한 저온스트레스가 진행되는 동안에 스트레스를 극복하는데 필요한 Proline 함량이 형질전환체에서 크게 증대되는 것이 관찰되었다. 이 외에도 저온스트레스 과정 중에 생성되는 활성산소의 독성을 감소시키는 항산화제 효소인 CAT, SOD 그리고 ADH 활성을 측정한 결과, 대조구에 비해 형질전환체에서 그 함량이 현저히 증가됨을 알 수 있었다. 따라서 이러한 결과를 통해 HvIRIP 유전자가 함유된 유채 형질전환체의 내한성이 증진되었음을 확인하였다.