• The Korean Journal of Physiology and Pharmacology
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• 제22권1호
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• pp.43-51
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• 2018

Although cisplatin is one of the most effective antitumor drugs for ovarian cancer, the emergence of chemoresistance to cisplatin in over 80% of initially responsive patients is a major barrier to successful therapy. The precise mechanisms underlying the development of cisplatin resistance are not fully understood, but alteration of DNA methylation associated with aberrant gene silencing may play a role. To identify epigenetically regulated genes directly associated with ovarian cancer cisplatin resistance, we compared the expression and methylation profiles of cisplatin-sensitive and -resistant human ovarian cancer cell lines. We identified ${\alpha}$-N-acetylgalactosaminidase (NAGA) as one of the key candidate genes for cisplatin drug response. Interestingly, in cisplatin-resistant cell lines, NAGA was significantly down-regulated and hypermethylated at a promoter CpG site at position +251 relative to the transcriptional start site. Low NAGA expression in cisplatin-resistant cell lines was restored by treatment with a DNA demethylation agent, indicating transcriptional silencing by hyper-DNA methylation. Furthermore, overexpression of NAGA in cisplatin-resistant lines induced cytotoxicity in response to cisplatin, whereas depletion of NAGA expression increased cisplatin chemoresistance, suggesting an essential role of NAGA in sensitizing ovarian cells to cisplatin. These findings indicate that NAGA acts as a cisplatin sensitizer and its gene silencing by hypermethylation confers resistance to cisplatin in ovarian cancer. Therefore, we suggest NAGA may be a promising potential therapeutic target for improvement of sensitivity to cisplatin in ovarian cancer.

• Journal of Microbiology and Biotechnology
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• 제17권1호
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• pp.130-137
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• 2007

A disease resistance related gene, MbR7, was identified in the wild apple species, Malus baccata. The MbR7 gene has a single open reading frame (ORF) of 3,288 nucleotides potentially encoding a 1,095-amino acid protein. Its deduced amino acid sequence resembles the N protein of tobacco and the NL27 gene of potato and has several motifs characteristic of a TIR-NBS-LRR R gene subclass. Ectopic expression of MbR7 in Arabidopsis enhanced the resistance against a virulent pathogen, Pseudomonas syringae pv. tomato DC3000. Microarray analysis confirmed the induction of defense-related gene expression in 35S::MbR7 heterologous Arabidopsis plants, indicating that the MbR7 gene likely activates a downstream resistance pathway without interaction with pathogens. Our results suggest that MbR7 can be a potential target gene in developing a new disease-resistant apple variety.

• 한국재난정보학회 논문집
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• 제4권2호
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• pp.138-154
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• 2008

The conventional non-dig underground structure building method which made an appearance to reduce the social and environmental costs and maximize the efficiency of the social overhead capital facilities could not help being uneconomical because of many problems such as unnecessary excessive excavation, water leakage, obstacle interference, difficulty of curvilinear application and connection complexity between propelled and injected bodies due to indiscriminate application of small and large circular steel pipes without consideration of the site conditions. The T.S.T.M, in which a protruded square tube is applied as a propulsion and injection body in a design that considered site conditions such as ground condition, depth of soil and live load, was able to be economical as it solved the problems of water resistance, minimization of obstacle interference and curvilinearity, and we can see that it can be applied to all grounds by utilizing or complementing the target ground in terms of engineering. Also in configuring the transverse section, it is possible to not only secure excellent structural safety but also implement all of the above engineering characteristics not only in the square cross section but also in the arch cross section, so it was possible to build structures on any section or ground, and we could confirm the LCC reduction effect and the VE effect.

• Molecules and Cells
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• 제41권11호
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• pp.933-942
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• 2018

Traditionally, small-molecule or antibody-based therapies against human diseases have been designed to inhibit the enzymatic activity or compete for the ligand binding sites of pathological target proteins. Despite its demonstrated effectiveness, such as in cancer treatment, this approach is often limited by recurring drug resistance. More importantly, not all molecular targets are enzymes or receptors with druggable 'hot spots' that can be directly occupied by active site-directed inhibitors. Recently, a promising new paradigm has been created, in which small-molecule chemicals harness the naturally occurring protein quality control machinery of the ubiquitin-proteasome system to specifically eradicate disease-causing proteins in cells. Such 'chemically induced protein degradation' may provide unprecedented opportunities for targeting proteins that are inherently undruggable, such as structural scaffolds and other non-enzymatic molecules, for therapeutic purposes. This review focuses on surveying recent progress in developing E3-guided proteolysis-targeting chimeras (PROTACs) and small-molecule chemical modulators of deubiquitinating enzymes upstream of or on the proteasome.

• Journal of Microbiology and Biotechnology
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• 제26권9호
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• pp.1605-1612
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• 2016

Quinolone-resistant Salmonella strains were isolated from patient samples, and several quinolone-sensitive strains were used to analyze mutations in the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, and parE and to screen for plasmid-mediated quinolone resistance. Among the 21 strains that showed resistance to nalidixic acid and ciprofloxacin (MIC 0.125-2.0 μg/ml), 17 strains had a mutation in QRDR codon 87 of gyrA, and 3 strains had a single mutation (Ser83 → Phe). Another cause of resistance, efflux pump regulation, was studied by examining the expression of acrB, ramA, marA, and soxS. Five strains, including Sal-KH1 and Sal-KH2, showed no increase in relative expression in an analysis using the qRT-PCR method (p < 0.05). In order to determine the genes involved in the resistance, the Sal-9 isolate that showed decreased susceptibility and did not contain a mutation in the gyrA QRDR was used to make the STM (MIC 8 μg/ml) and STH (MIC 16 μg/ml) ciprofloxacin-resistant mutants. The gyrA QRDR Asp87 → Gly mutation was identified in both the STM and STH mutants by mutation analysis. qRT-PCR analysis of the efflux transporter acrB of the AcrAB-TolC efflux system showed increased expression levels in both the STM (1.79-fold) and STH (2.0-fold) mutants. In addition, the expression of the transcriptional regulator marA was increased in both the STM (6.35-fold) and STH (21.73-fold) mutants. Moreover, the expression of soxS was increased in the STM (3.41-fold) and STH (10.05-fold) mutants (p < 0.05). Therefore, these results indicate that AcrAB-TolC efflux pump activity and the target site mutation in gyrA are involved in quinolone resistance.

• Journal of Microbiology
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• 제40권1호
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• pp.63-69
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• 2002

A total of twenty-five norfloxacin resistant Escherichia coli were isolated from Joongrang-chun stream, a branch of the Han River in Seoul, Korea from May to July in 2000 and their norfloxacin resistance mechanism was characterized for target site mutation, permeability, and efflux pump. Fourteen iso- lates contained the same three mutations, Ser83→Leu and Asp87→Asn in GyrA and Ser90→ lle in ParC. Six isolates had Ser83→Leu and Asp87→Tyr in GyrA and Ser87→lle in ParC while one isolate had Ser83→Leu and Va1103→Ala in GyrA and Ser80→lle in ParC. Two isolates had mutation(s) in GyrA without any mutation in ParC. Two isolates had Ser80→Arg in ParC instead of the commonly found Ser80→lle. Every norfloxacin resistant isolate had an efflux system but the correlation between the efflux activity and MIC was not observed. The amount of OmpF for norfloxacin permeability decreased in resistant isolates compared to the susceptible strains. When amplified polymorphic DNA (RAPD) and pulse field gel electrophoresis (PFGE) were performed, these isolates showed no similarity to each other or clinical isolates.

• Journal of Applied Biological Chemistry
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• 제43권4호
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• pp.185-191
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• 2000

Pest insect control is dependent on about 200 insecticides that work by relatively few mechanisms. The targets they disrupt are mostly involved in the nervous system, respiratory chain, growth and development, or the gut. The major nerve targets are: acetylcholinesterase for the organophosphates and methylcarbamates; the nicotinic acetylcholine receptor for the neonicotinoids; the $\gamma$-aminobutyric acid receptor for several chlorinated hydrocarbons and fipronil; the voltage-gated sodium channel for DDT and pyrethroids. Selection of resistant strains often confers cross-resistance to some or all other insecticides working at the same site. The toxicological properties of different compounds acting on the same target are increasingly considered together, summating the risk even though the compounds are of quite diverse chemical types. Continuing attention is also being given to secondary targets not involved in the primary mechanism of toxicity but instead in side effects that must be considered in the overall safety evaluation. Research on insecticide targets is important in learning to keep up with resistance and changing concepts and policies on safety. These relationships are illustrated by recent studies in the Environmental Chemistry and Toxicology Laboratory of the University of California at Berkeley.

• Weed & Turfgrass Science
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• 제5권3호
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• pp.105-110
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• 2016

세계 잡초연구자들이 세계잡초학회에서 발표한 최근 연구동향을 파악하여 이를 토대로 향후 잡초연구 발전방향과 전망을 제시하고자 하였다. 제 7차 세계잡초학회는 우리나라를 포함한 59개국 520여명이 참석하였으며, 9개 분야 625편이 발표되었다. 주요 연구분야로는 제초제 저항성잡초, 잡초생태, 농경지 및 비농경지의 잡초관리, 제초제 살포기술, 비화학적 잡초방제 등이었다. 이중 제초제 저항성잡초 연구분야는 전체 30%를 점유하여 향후에도 이들 연구가 지속될 것으로 판단된다. 특히 설포닐우레아계 보다는 비선택성 제초제인 glyphosate, glufosinate-ammonium 저항성 잡초에 대한 발표가 많았다. 신규 제초제 개발은 synthetic auxin 작용기작의 제초제인 arylex, HPPD 저해제로 개발 중인 3가지 물질을 safener와의 합제 연구 등이 있었다. 그리고 세계 주곡작물인 옥수수, 밀, 벼 재배지에서 발생되는 제초제 저항성잡초에 대한 연구가 집중되었다. 특히 잡초의 non-target site에 대한 저항성 연구가 집중적이었다. 또한 우리나라에는 없는 기생잡초에 대한 연구 폭이 넓어지고 있으며, 예년에는 취급하지 않았던 비화학적 잡초방제 부문도 많았다. 향후에는 제초제 저항성 메카니즘 구명, 기생잡초 연구, 제초제 살포기술, 비화학적 잡초방제 등의 연구가 폭넓게 진행될 것으로 전망되었다.

• 미생물학회지
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• 제48권2호
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• pp.79-86
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• 2012

ErmSF는 23S rRNA의 A2058 (E. coli numbering)에 methylation을 유발하여 macrolide-lincosamide-streptogramin B ($MLS_B$)계 항생제의 부착을 저해함으로써 항생제 활성을 억제하는 내성인자 단백질인 Erm 단백질들 중의 하나이다. Erm 단백질들 사이에서 공통적으로 나타나는 $^{222}FXPXPXVXS^{230}$ (ErmSF numbering) 서열은 Erm 단백질인 ErmC'와 DNA methyltransferase인 M. Taq I의 구조를 분석한 연구에서 타깃인 adenine과 직접적으로 상호작용하는 부위로 제안되거나 확인되었다. 따라서 이 부분 중 Erm 단백질 사이에서 잘 보존되어있지는 않지만 염기성인 잔기의 특성상 기질인 RNA와 상호작용이 예상되는 223, 227번 arginine을 alanine으로 위치 지정 치환한 변이 단백질을 이용하여 그 잔기의 효소 활성에서의 역할을 확인하였다. 두 변이 단백질은 생체 내에서 그 활성을 여전히 유지하고 있어서 항생제인 erythromycin에 대하여 내성을 나타내었으나 in vitro 상에서는 R223A 또는 R227A가 야생형 ErmSF에 비하여 약 50%, 88%의 활성을 각각 나타내어 효소 활성에서 각 잔기가 결정적이지는 않지만 중요한 역할을 수행하고 있음을 확인하였다.

• 농약과학회지
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• 제7권4호
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• pp.288-295
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• 2003

유기인계 살충제인 chlorpyrifos에 대한 배추좀나방의 저항성 원인을 구명하기 위하여 저항성 인자로 알려진 두 가지 무독화 효소, esterases와 glutathione- S-trasferase(GST)의 활성과 작용점 효소인 acetylcholinesterase(AChE)의 insensitivity 정도를 측정하였다. 또한 chlorpyrifos와 작용점이 동일한 계통의 살충제에 대한 저항성 발달과의 상관관계를 조사하여 교차저항성 발달 특성을 검정하였다. 감수성 배추좀나방에 chlorpyrifos의 아치사량을 처리하여 160배의 저항성을 나타내도록 선발하여 실험에 사용하였다. 저항성 계통의 GST 활성은 감수성 계통의 GST 활성에 비하여 1.7배 높았으나, 감수성 계통과 저항성 계통간에 esterases 활성 차이는 없었다. 또한 chlorpyrifos의 작용점인 AChE insensitivity 측정결과 저항성 계통이 감수 성계통보다 11.6배 높았다. Chlorpyrifos 저항성 계통은 AChE을 저해하는 것으로 알려진 유기인계 및 카바 메이트계 살충제인 dichlorvos, dimethylvinphos, carbofuran에 대해서도 각각 33.6배, 17.6배, 18.7배의 insensitivity를 나타내었다. 그러나 동일한 작용점을 저해하는 phenthoate-oxon에 대해서는 1.7배의 낮은 insensitivity를 보였다. 또한 이들 약제들에 대한 교차저항성 발달정도를 측정한 결과, chlorpyrifos 저항성 계통은 dichlorvos, dimethylvinphos, carbofuran에 대하여도 각각 82배, 47배, 42배의 높은 교차저항성 발달을 나타내었으나, phenthoate에 대해서는 2.3배로 낮은 교차저항성 발달을 보여 작용점이 동일한 유사계열 약제들이라도 저항성을 유발하는 기작에는 서로 큰 차이가 있을 수 있음을 확인할 수 있었다. 본 실험 결과 AChE insensitivity 와 저항성 발달비 간에는 정의상관관계$(r=0.9951^{**},\;p^{(0.01)}$를 보이는 것으로 나타났는데, 이는 유기인계 및 카바메이트계 살충제의 저항성 발달이 AChE에 대한 insensitivity 정도와 관련 있음을 시사하는 것이다. 본 연구의 결과를 통하여 chlorpyrifos에 대한 배추좀나방의 저항성 발달은 작용점인 AChE에 대한 약제의 insensitivity가 주 요인 중 하나이며, 무독화 효소 중 GST 활성증가가 부가적인 요인이 될 수 있음을 확인할 수 있었다.