• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2002년도 추계학술대회
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• pp.40-50
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• 2002

Fruit fly, Drosophila melanogaster has developed efficient immune mechanisms to prevent microbial infection, which are consisted of cellular and humoral responses. During the systemic or local infection, two distinct pathways (Toll and Imd) play major roles in antimicrobial peptide synthesis. The Toll pathway is required to defend Gram-positive bacterial and fungal infections, whereas the Imd pathway is important in Gram-negative bacterial infection. We have shown that the infection of the opportunistic Gram-negative bacterium, Pseudomonas aeruginosa strain PA14 (PA14) into fly dorsal thorax can kill the flies within 48 h ($100\%$ mortality) in our optimized infection condition, suggesting that the PA14 strain can cause disease progress in fly model system. We found that flies carrying a constitutively activated mutant form of the Toll receptor $(Tl^{10b})$ showed increased resistance to P. aeruginosa infection and that flies carrying mutations in the Toll signaling pathway as well as in the Imd signaling pathway was more susceptible to PA14 infection. All these results imply that the Toll pathway might be important in the resistance to this pathogenic Gram-negative bacterial infection.

• Journal of Microbiology and Biotechnology
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• 제25권1호
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• pp.50-56
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• 2015

During pretreatment of lignocellulosic biomass, a variety of fermentation inhibitors, including acetic acid and vanillin, are released. Using DNA microarray analysis, this study explored genes of the budding yeast Saccharomyces cerevisiae that respond to vanillin-induced stress. The expression of 273 genes was upregulated and that of 205 genes was downregulated under vanillin stress. Significantly induced genes included MCH2, SNG1, GPH1, and TMA10, whereas NOP2, UTP18, FUR1, and SPR1 were down regulated. Sequence analysis of the 5'-flanking region of upregulated genes suggested that vanillin might regulate gene expression in a stress response element (STRE)-dependent manner, in addition to a pathway that involved the transcription factor Yap1p. Retardation in the cell growth of mutant strains indicated that MCH2, SNG1, and GPH1 are intimately involved in vanillin stress response. Deletion of the genes whose expression levels were decreased under vanillin stress did not result in a notable change in S. cerevisiae growth under vanillin stress. This study will provide the basis for a better understanding of the stress response of the yeast S. cerevisiae to fermentation inhibitors.

• Journal of Microbiology
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• 제41권1호
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• pp.52-57
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• 2003

The mutational spectra in the manganese (II) peroxidase gene (mnp) of the Pleurotus ostreatus mutants induced by gamma radiation (Co$\^$60/) give evidence to prove the effect of gamma radiation on the gene. mnp of each mutant was cloned, sequenced and analyzed. Among the 1941 base pairs of the sequenced region of the mnP genes of 4 mutants (PO-5,-6,-15 and -16), nine mutational hotspots on which the same base was mutated simultaneously were found, additionally 6 mutations were also found at different positions in the mnp gene. These mutation-spectra were predominantly A:T\longrightarrowG:C transitions (50.1%). By the analysis of putative amino acid sequences, PO-5 and PO-16 mutants have 3 and 1 mutated residues, respectively. Since the mutational spectra reported herein are specific to the mnp gene, we propose that the mutational hotspots for the gamma radiation could be in the gene(5) within cells.

• 한국환경성돌연변이발암원학회지
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• 제21권2호
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• pp.149-155
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• 2001

Eighty-one workers including 38 employees directly incinerating industry wastes were recruited from a company located in South Korea. To evaluate the association between urinary 1-hydroxypyrene glucuronide (1-OHPG) levels, as internal dose of polycyclic aromatic hydrocarbon (PAH) exposure, and glycophorin A (GPA) mutation frequency, as an early biologic effect indicator. Urinary 1-OHPG levels were measured by synchronous fluorescence spectroscopy after immunoaffinity purification using monoclonal antibody 8E11. Erythrocyte GPA variant frequency (NN or NO) was assessed in MN heterozygotes with a flow cytometic assay. The GSTM1 and GSTT1 genotypes were assessed by a multiplex PCR method. The GPA NN phenotype frequency was higher in occupationally exposed group (n=14, mean$\pm$S.D. 6.6$\pm$12.0 in 10/SUP 6/ erythrocyte cells) than in non-exposed group (n=22, 2.1$\pm$3.5). Similarly, the GPA(NO or NN) phenotype frequency was higher in exposed group (n=14, 9.7$\pm$17.3) than non-exposed group (n=22, 4.2$\pm$6.3). The above differences failed to reach statistical significance, but a significant increase was seen in GPA variant frequency levels with increase in urinary 1-OHPG levels (Spearman's correlation: p=0.06 (NO), p=0.07 (NO or NN)). When this association was evaluated by GSTM1 genotype status, the association between GPA mutation and urinary 1-OHPG levels was stronger in individuals with GSTM1 present genotype (Spearmans correlation; r=0.50, p=0.02). These results suggest that the association between urinary 1-OHPG and GPA mutation is be modulated by the GSTM1 genotype.

• 미생물학회지
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• 제50권4호
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• pp.281-284
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• 2014

병원성 균주인 녹농균(Pseudomonas aeruginosa) 감염에 대응하여 나타나는 면역반응은 인체의 항상성 유지에 중요하다. 선행 연구에서 녹농균의 감염에 대응하여 bradykinin receptor (BR)의 발현이 증가됨을 보고하였지만, 발현유도에 관여하는 녹농균 유래인자에 대해서는 보고한 바가 없었다. 이번 연구에서는 녹농균에 의한 BR의 발현은 Type III secretion system (T3SS)이 관여하지만, 기존에 알려진 T3SS인자가 아닌 nucleoside diphosphate kinase (Ndk)에 의한 것으로 조사되었다. 하지만 pDNNDK를 이용한 transfection 실험 결과, Ndk 만으로는 BR의 발현이 유도되지 않았으며, Ndk와 함께 flagella가 필요함을 발견하였다. 이러한 결과는 기존에 보고된 주요 pathogen-associated molecular patterns (PAMPs)인 flagella와 더불어 감염대응에 관여하는 Ndk를 발굴한 의미가 있으며, 녹농균에 의한 질병기전을 이해하는데 도움을 줄 수 있다.

• 대한두경부종양학회지
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• 제17권2호
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• pp.169-173
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• 2001

Objectives: The p53 tumor suppressor gene encodes a nuclear transcription factor that is critical regulator of cell growth and proliferation through its action in cell-cycle checkpoint control. The wide variety of stressful stmuli which include DNA damage, hypoxia, heat shock, metabolic changes activate the p53 protein, which in turn drives a series of events that culminate either in cell cycle arrest or apoptosis. Mutations of the p53 gene is the most common genetic alteration in human cancer. This gene is altered in approximately 40-60% of head and neck cancers. Whereas the wild-type form of the p53 protein plays a central role in cell-cycle control in response to DNA damage, most of the mutant forms are unable to do so. The high levels of p53 protein expression in tissues are related to the increased cellular proliferative activity and may be associated with the poor clinical outcome. To determine whether the expression of the p53 protein has prognostic significance and is associated with patterns of treatment failure in head and neck squamous cell carcinoma (HNSCC), We analyzed p53 overexpression in 40 cases of HNSCC. Materials and Methods: Immunohistochemical analysis with a monoclonal antibody (DO7) specific for p53 protein was used to detect expression of the protein in formalin-fixed, paraffin-embedded tumor samples from 40 HNSCC. We evaluated p53 protein expression and analyzed the relationship between the p53 overexpression and age, sex, primary tumor site, stage, survival rate, recurrence. All reported P values resulted from two-sided statistical tests. Results: Overexpression of p53 was detected in 20 cases(50%) among 40 cases of HNSCC. The p53 overexpression was not associated with age, sex, primary tumor site, stage, recurrence and survival rate. Conclusions: In our results, p53 was not significant prognostic factor in HNSCC. Based on many previous studies, It is evident that p53 has a certain role in tumorigenesis of HNSCC. So, the further study is needed to evaluate the prognostic significance of p53 in HNSCC.

• Journal of Korean Neurosurgical Society
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• 제63권5호
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• pp.566-578
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• 2020

Objective : Radiation is known to induce autophagy in malignant glioma cells whether it is cytocidal or cytoprotective. Dexamethasone is frequently used to reduce tumor-associated brain edema, especially during radiation therapy. The purpose of the study was to determine whether and how dexamethasone affects autophagy in irradiated malignant glioma cells and to identify possible intervening molecular pathways. Methods : We prepared p53 mutant U373 and LN229 glioma cell lines, which varied by phosphatase and tensin homolog (PTEN) mutational status and were used to make U373 stable transfected cells expressing GFP-LC3 protein. After performing cell survival assay after irradiation, the IC₅₀ radiation dose was determined. Dexamethasone dose (10 μM) was determined from the literature and added to the glioma cells 24 hours before the irradiation. The effect of adding dexamethasone was evaluated by cell survival assay or clonogenic assay and cell cycle analysis. Measurement of autophagy was visualized by western blot of LC3-I/LC3-II and quantified by the GFP-LC3 punctuated pattern under fluorescence microscopy and acridine orange staining for acidic vesicle organelles by flow cytometry. Results : Dexamethasone increased cell survival in both U373 and LN229 cells after irradiation. It interfered with autophagy after irradiation differently depending on the PTEN mutational status : the autophagy decreased in U373 (PTEN-mutated) cells but increased in LN229 (PTEN wild-type) cells. Inhibition of protein kinase B (AKT) phosphorylation after irradiation by LY294002 reversed the dexamethasone-induced decrease of autophagy and cell death in U373 cells but provoked no effect on both autophagy and cell survival in LN229 cells. After ATG5 knockdown, radiation-induced autophagy decreased and the effect of dexamethasone also diminished in both cell lines. The diminished autophagy resulted in a partial reversal of dexamethasone protection from cell death after irradiation in U373 cells; however, no significant change was observed in surviving fraction LN229 cells. Conclusion : Dexamethasone increased cell survival in p53 mutated malignant glioma cells and increased autophagy in PTEN-mutant malignant glioma cell but not in PTEN-wildtype cell. The difference of autophagy response could be mediated though the phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin signaling pathway.

• 한국미생물·생명공학회지
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• 제26권1호
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• pp.83-88
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• 1998

Capsular polymer인 zooglan을 생산하는 Z. ramigera 115와 수용성 slime polymer 생산 변이주인 Z. ramigera l15SLR의 중금속 제거능을 비교하였다. 중금속 5종($Cd^{2+}$, $Co^{2+}$, $Cu^{2+}$, $Ni^{2+}$, $Fe^{2+}$)의 최저 생장저해농도는 두 균주 모두 유사하였다. $Cd^{2+}$을 첨가하지 않은 경우에 비해 $Cd^{2+}$ 500ppm을 첨가한 액체 배지에서의 생체량은 Z. ramigera 115는 24%, Z. ramigera l15SLR은 50%로 감소하였고 동일한 생체량에 대하여 Z. ramigera 115SLR이 Z. ramtgera 115보다 $Cd^{2+}$을 1.5배 더 제거하였다. 세포와 polymer를 분리하여 중금속 흡착능을 비교한 결과 polymer가 세포보다 높은 흡착량을 나타냈으며 최적 중금속 흡착 pH는 7.5였다. Langmuir 흡착등온선과 Freundlich 흡착등온선을 분석한 결과 $Cd^{2+}$에 대하여 Z. ramigera l15SLR polymer는 Z. ramigera 115 및 이온 교환 수지보다 높은 최대흡착량과 흡착안정성을 보여서 홉착제로서 유용할 것으로 판단된다.

• 대한미생물학회지
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• 제35권3호
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• pp.203-214
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• 2000

Porphyromonas gingivalis has been implicated in periodontal diseases. Accumulating evidence suggests that cardiovascular disease is the most prevalent medical problem in patients with periodontal diseases. In order to check the possibility that P. gingivalis is involved in coronary heart disease, the present study was performed to observe P. gingivalis adherence and invasion of human coronary artery endothelial cells (HCAEC) and production of cytokines and growth factors by HCAEC upon P. gingivalis infection. $^3H$-labeled P. gingivalis 381 was incubated with HCAEC for 90 min. The radioactivity of the washed HCAEC was a measure of the absorbed (adhering and invading) P. gingivalis. The absorption radioactivity of the HCAEC infected by P. gingivalis was determined to be 59.58% of the input bacterial cells. In contrast, the absorption radioactivity of the cells infected by S. gordonii Challis which was employed as a control was negligible (0.59%). DPG3, a P. gingivalis mutant defective of fimbriae, appeared to be impaired to some extent in capability of adherence/invasion as compared to that of the parental strain 381, showing 43.04% of the absorption radioactivity. The absorption radioactivity of the HCAEC infected by P. gingivalis 381 in the presence of excessive fimbriae at the concentrations of $50\;{\mu}g$ and $100\;{\mu}g/ml$ was 57.27 and 45.44%, respectively. Invasion of HCAEC by P. gingivalis 381 was observed by an antibiotic (metronidazole) protection assay and transmission electron microscopy (TEM). In the antibiotic protection assay, invasion by the bacterium was measured to be 0.73, 1.09, and 1.51% of the input bacterial cells after incubation for 30, 60, and 90 min, respectively. Invasion by DPG3 was shown to be 0.16% after 90-min incubation. In comparison of invasion efficiency at 90 min of the incubation, the invasion efficiency of DPG3 was 0.37% while that of its parental strain 381 was 2.54%. The immunoblot analysis revealed fimbriae of P. gingivalis did not interact with the surface of HCAEC. These results suggest that fimbriae are not the major contribution to the adherence of P. gingivalis to HCAEC but may be important in the invasion of HCAEC by the bacterium. The presence of cytochalasin D ($1\;{\mu}g/ml$) and staurosporine ($1\;{\mu}M$) reduced the invasion of HCAEC by P. gingivalis 381 by 78.86 and 53.76%, respectively, indicating that cytoskeletal rearrangement and protein kinase of HCAEC are essential for the invasion. Infection of P. gingivalis induced HCAEC to increase the production of TNF-${\alpha}$. by 60.6%. At 90 min of the incubation, the HCAEC infected with P. gingivalis cells was apparently atypical in the shape, showing loss of the nuclear membrane and subcellular organelles. The overall results suggest that P. gingivalis may cause coronary heart disease by adhering to and invading endothelial cells, and subsequently damaging the cells.

• Journal of Korean Neurosurgical Society
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• 제29권4호
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• pp.471-476
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• 2000

Objective : p16/INK4a, a kind of tumor suppressor genes, encodes a specific inhibitor of the cyclin D-dependent kinases CDK4 and CDK6. This prevents the association of CDK4 with cyclin D1, and subsequently inhibits phosphorylation of retinoblastoma tumor suppressor protein(pRb), thus preventing exit from the G1 phase. According to previous reports, over 50% of glioma tissue and 80% of glioma cell lines have been demonstrated inactivation of p16/INK4a gene. The purpose of this study was to determine whether recombinant adenovirus-p16 virus is a suitable candidate for gene replacement therapy in cases of glioma. Methods : Three human glioma cell lines(U251MG, U87MG and U373MG) that express mutant p16 protein were used. Replication-deficient adenovirus was utilized as an expression vector to transfer exogenous p16 cDNA into the cells ; control cells were infected with the Ad-${\beta}$-gal expressing ${\beta}$-galactosidase. To monitor gene transfer and the expression of exogenous genes, we used Western Blotting analysis. Flow cytometry studies of cellular DNA content were performed to determine the cell cycle phenotype of the glioma cells before and after treatment. Results : We showed here that restoration of p16/INK4a expression in p16 negative U87MG, U251MG and partially deleted U373MG by Ad-CMV-p16 induced growth suppression in vitro. Flow cytometric study revealed that Ad-CMV-p16 infected U87MG cells were arrested during the G0-G1 phase of the cell cycle. Expression of p16 transferred by Ad-CMV-p16 in glioma cells was highly efficient and maintained for more than seven days. Conclusions : Our results suggest that Ad-CMV-p16 gene therapy strategy is potentially useful and warrants further clinical investigation for the treatment of gliomas.