• Microbiology and Biotechnology Letters
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• v.31 no.1
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• pp.75-82
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• 2003

The cellular responses of RDX-degrading bacterium, Pseudomonas sp. HK-6 to explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) were examined. Strain HK-6 grown at different RDX concentrations was found to demonstrate the survival rate in proportional to the rate of the stress shock proteins produced in this bacterium. Analysis of total cellular fatty acid acids showed that lipids 10:0 iso and 14:1 $\omega$5c/$\omega$5t increased approx three times in strain HK-6 grown on RDX media than TSA media. SDS-PAGE and Western blot using anti-DnaK and GroEL revealed that several stress shock proteins including 70 kDa DnaK and 60 kDa CroEL were newly synthesized in strain HK-6 exposed to different RDX concentrations in exponentially growing cultures. 2-D PAGE of soluble protein fractions from the culture of HK-6 exposed to RDX demonstrated that approximately 300 spots were observed on the silver stained gel ranging from pH 3 to pH 10. As a result, 10 spots were significantly induced and expressed in response to RDX. Scanning electron microscopy fur the cells treated with 0.135 mM RDX for 12 hrs showed the presence of perforations and irregular rod shapes with wrinkled surfaces.

• Journal of Life Science
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• v.16 no.6
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• pp.1052-1059
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• 2006

The heat shock response is induced by environmental stress, pathophysiological state and non-stress conditions and wide spread from bacteria to human. Although translations of most proteins are stopped under a heat shock response, heat shock proteins (HSPs) are produced to protect cell from stress. When heat shock response is induced, conformation of HSF1 was changed from monomer to trimer and HSF1 specifically binds to DNA, which was called a heat shock element(HSE) within the promoter of the heat shock genes. Human HSF1(hHSFl) contains five cysteine(Cys) residues. A thiol group(R-SH) of Cys is a strong nucleophile, the most readily oxidized and nitrosylated in amino acid chain. This consideration suggests that Cys residues may regulate the change of conformation and the activity of hHSF1 through a redox-dependent thiol/disulfide exchange reaction. We want to construct role of five Cys residues of hHSF by redox reagents. According to two studies, Cys residues are related to trimer formation of hHSF1. In this study, we want to demonstrate the correlation between structural change and DNA-binding activity of HSF1 through forming disulfide bond and trimerization. In this results, we could deduce that DNA binding activity of DNA binding domain wasn't affected by redox for always expose outside to easily bind to DNA. DNA binding activity of wild-type HSF's DNA binding domain was affected by conformational change, as conformational structure change (trimerization) caused DNA binding domain.

• Molecules and Cells
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• v.46 no.6
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• pp.374-386
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• 2023

Thermal stress induces dynamic changes in nuclear proteins and relevant physiology as a part of the heat shock response (HSR). However, how the nuclear HSR is fine-tuned for cellular homeostasis remains elusive. Here, we show that mitochondrial activity plays an important role in nuclear proteostasis and genome stability through two distinct HSR pathways. Mitochondrial ribosomal protein (MRP) depletion enhanced the nucleolar granule formation of HSP70 and ubiquitin during HSR while facilitating the recovery of damaged nuclear proteins and impaired nucleocytoplasmic transport. Treatment of the mitochondrial proton gradient uncoupler masked MRP-depletion effects, implicating oxidative phosphorylation in these nuclear HSRs. On the other hand, MRP depletion and a reactive oxygen species (ROS) scavenger non-additively decreased mitochondrial ROS generation during HSR, thereby protecting the nuclear genome from DNA damage. These results suggest that suboptimal mitochondrial activity sustains nuclear homeostasis under cellular stress, providing plausible evidence for optimal endosymbiotic evolution via mitochondria-to-nuclear communication.

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.105-109
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• 2005

Heat Shock Transcription Factor (HSF), and the promoter heat Shock Element (HSE), are among the most highly conserved transcriptional regulatory elements in nature. HSF mediates the transcriptional response of eukaryotic cells to heat, infection and inflammation, pharmacological agents, and other stresses. While HSF is essential for cell viability in yeast, oogenesis and early development in Drosophila, extended life-span in C. elegans, and extra-embryonic development and stress resistance in mammals, little is known about its full range of biological target genes. We used whole genome analyses to identify virtually all of the direct transcriptional targets of yeast HSF, representing nearly three percent of the genomic loci. The majority of the identified loci are heat-inducibly bound by yeast HSF, and the target genes encode proteins that have a broad range of biological functions including protein folding and degradation, energy generation, protein secretion, maintenance of cell integrity, small molecule transport, cell signaling, and transcription. Approximately 30% of the HSF direct target genes are also induced by the diauxic shift, in which glucose levels begin to be depleted. We demonstrate that phosphorylation of HSF by Snf1 kinase is responsible for expression of a subset of HSF targets upon glucose starvation.

• Genomics & Informatics
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• v.8 no.1
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• pp.34-40
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• 2010

Radiofrequency (RF) radiation might induce the transcription of a certain set of genes as other physical stresses like ionizing radiation and UV. To observe transcriptional changes upon RF radiation, we exposed WI-38, human lung fibroblast cell to 1763 MHz of mobile phone RF radiation at 60 W/kg of specific absorption rate (SAR) for 24h with or without heat control. There were no significant changes in cell numbers and morphology after exposure to RF radiation. Using quantitative RT-PCR, we checked the expression of three heat shock protein (HSP) (HSPA1A, HSPA6 and HSP105) and seven stress-related genes (TNFRSF11B, FGF2, TGFB2, ITGA2, BRIP1, EXO1, and MCM10) in RF only and RF/HS groups of RF-exposed cells. The expressions of three heat shock proteins and seven stress-related genes were selectively changed only in RF/HS groups. Based on the expression of ten genes, we could classify thermal and non-thermal effect of RF-exposure, which genes can be used as biomarkers for RF radiation exposure.

• The Journal of Korean Physical Therapy
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• v.20 no.1
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• pp.57-65
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• 2008

Purpose: Heat shock proteins (HSPs) are a group of proteins that are activated when cells are exposed to a variety of environmental stresses, such as infection, inflammation, exposure to toxins, starvation, hypoxia, brain injury, or water deprivation. The activation of HSPs by environmental stress plays a key role in signal transduction, including cytoprotection, molecular chaperone, anti-apoptotic effect, and anti-aging effects. However, the precise mechanism for the action of small HSPs, such as HSP27 and mitogen-activated protein kinases (MAPKs: extracellular-regulated protein kinase 1/2 (ERK1/2), p38MAPK, stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), is not completely understood, particularly in application of cell stimulators including platelet-derived growth factor (PDGF), angiotensin II (AngII), tumor necrosis factor $\alpha$ (TNF$\alpha$), and $H_2O_2$. This study examined the relationship between stimulators-induced enzymatic activity of HSP27 and MAPKs from rat smooth and skeletal muscles. Methods: 2-dimensional electrophoresis (2DE) and matrix assisted laser desorption ionizationtime-of-flight/time-of-flight (MALDI-TOF/TOF) analysis were used to identify HSP27 from the intact vascular smooth and skeletal muscles. Three isoforms of HSP27 were detected on silver-stained gels of the whole protein extracts from the rat aortic smooth and skeletal muscle strips. Results: The expression of PDGF, AngII, TNF$\alpha$, and $H_2O_2$-induced activation of HSP27, p38MAPK, ERK1/2, and SAPK/JNK was higher in the smooth muscle cells than the control. SB203580 (30${\mu}$M), a p38MAPK inhibitor, increased the level of HSP27 phosphorylation induced by stimulators in smooth muscle cells. Furthermore, the age-related and starvation-induced activation of HSP27 was higher in skeletal muscle cells (L6 myoblast cell lines) and muscle strips than the control. Conclusion: These results suggest, in part, that the activity of HSP27 and MAPKs affect stressors, such as PDGF, AngII, TNF$\alpha$, $H_2O_2$, and starvation in rat smooth and skeletal muscles. However, more systemic research will be needed into physical therapy, including thermotherapy, electrotherapy, radiotherapy and others.

• Journal of Microbiology and Biotechnology
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• v.10 no.2
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• pp.137-142
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• 2000

Environmental stres is known to induce heat shock proteins (HSPs) in eukaryotic cells. However, the induction of HSPs in host cells by microbial infection has not yet been well explained. Staphylococcus aureus (S. aureus) is one of the major pathogens in the pathogenesis of endovascular diseases such as infective endocarditis. In this study, the synthesis of stress-inducible 70 kDa HSP was investigated in the endothelial cells (ECs) after 3 h to 20 h of incubation with S. aureus. The dffect of S. aureus infection on the expression of HSP70 in cultured ECs was analyzed using laser scanning confocal microscopy (LSCM). The increase of HSP70 expression in ECs infected by S. aureus ($10^4{\;}cfu/ml$) for 20 h was 1.1-fold higher than that in heat shock treated ECs and 2.2-fold higher than that in untreated cells. Heat shock is known to induce intranucleus HSP70 expression in mammalian cells, whereas the S. aureus infection induced perinuclear expression in ECs as observed by LSCM. Consequently, the expression of HSP70 in ECs plays an important role in the pathogenesis of endovascular infection.

• Toxicological Research
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• v.15 no.1
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• pp.79-87
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• 1999

To know the stress response and antioxidative effect of sulfur containing compounds, we observed the expression of the stress protein (heat shock protein; inducible protein) from mouse tissues and evaluated the protective effects to hydroxyl radical in mouse brain cell culture. Cysteine, methionine or sodium sulfide was fed by oral administration of 1 ml/per 6hr/three times with 1 mM, 2mM or 3mM to mouse, respectively. After that, the stress proteins were extracted from mouse tissues and analyzed the features of expression. The stress proteins by sulfur containing compounds were showed different aspects in the kinds and concentrations of their compounds, and in the tissues of mouse. In the liver, the stress proteins were appeared at different time on the concentration of sulfur containing compounds and had less than 20 KDa as small molecules. In general, the molecular weights of stress protein in liver, the stress proteins were appeared at different time on the concentration of sulfur containing compounds and had less than 20 KDa as small molecules. In general, the molecular weights of stress protein in the spleen were evaluated from 32KDa to 50KDA, and the induced times were relatively late at high concentration of cysteine, early at low concentration of methionine or sodium sulfide. The stress proteins in mouse muscle were detected mostly between 24hr after treatment of sulfur containing compounds. Their molecular weights were 15~24KDa. In the antioxidative effects of sulfur containing compounds to hydroxyl radical, cell viabilities were measured by 63.2% at 10 $\mu\textrm{M}$, 65.5% at 50 $\mu\textrm{M}$, 68.6% at 100 $\mu\textrm{M}$, 78.3% at 150 $\mu\textrm{M}$, or 83.0% at 200 $\mu\textrm{M}$ of cysteine, respectively. At addition of methionine, the cell viabilities were assessed as 58.1% at 10 $\mu\textrm{M}$, 62.8% at 50 $\mu\textrm{M}$, 75.7% at 100 $\mu\textrm{M}$, 78.6% at 150 $\mu\textrm{M}$, and 79.2% at 200 $\mu\textrm{M}$ after 4hrs exposure with 20mU/ml glucose oxidase (GO) system, while the numbers of live cells to hydroxyl radicals in treatment of sodium sulfide were showed 48.6% at 10 $\mu\textrm{M}$, 54.8% at 100 $\mu\textrm{M}$, 51.8% at 150 $\mu\textrm{M}$, and 51.6% at 200 $\mu\textrm{M}$ in the neuronal cells. In the inhibitory effects on the proliferation of tumor cells, percentages of dead cells of the CT-26 or HeLa cell were generally less than 30% even 48hr after addition of sulfur containing compounds. Conclusively, the results of these experiments indicate that stress protein by sulfur containing compounds can be used as physiological indicator for animal nutrition and for environment, and also that cysteine and methionine can play critical roles as an antioxidant.

• Korean Journal of Microbiology
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• v.38 no.1
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• pp.45-49
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• 2002

Bradyrhizobium japonicum is a soil bacterium with a unique ability to infect the roots of leguminous plants and establish a nitrogen-fixing symbiosis, which has been used as a microbial manure. In this study, we examined the stress response after pretreatment of cells with cold temperature. When pre-treated with cold temperature ($4^{\circ}C$) for 16 hr, B. japonicum increased the viability in subsequent stress-conditions such as alcohol, $H_2O_2$, heat, and dehydration. For cold adpatation, cultured B. japonicum was exposed to $4^{\circ}C$. Upon subsequent exposure to various conditions, the number of adapted cells pretreated by cold adaptation was 10-1000 fold higher than that of non-adaptated ones. It appeared de novo protein synthesis occurred during adaptation, because a protein synthesis inhibitor, chloramphenicol abolished the increased stress tolerance. By using a degenerate PCR primer set, a csp homolog was amplified from B. japonicum genome and sequenced. The deduced partial amino acid sequence of the putative Csp (Cold shock protein) shares a significant similarity with known Csp proteins of other bacteria.

• Journal of Life Science
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• v.11 no.5
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• pp.464-469
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• 2001

A gene, dnaK2, encoding a distinct member of the HSP70 family of molecular chaperones is isolated from the halotolerant cyanobactrium Aphanothece halophytica. The dnak2 gene encodes a molecular wight of 68 kDa polypeptide with predicted 616 amino acid residues. The DnaK2 protein has a structural characteristic of bacterial DnaK homologues and shows high similarity to other HSP70/Dank proteins. The danK2 transcripts are hardly detectable at 28$^{\circ}C$ and strongly induced upon heat stress. It is also found that dnaK2 transcript is increased by high-salinity stress even in the absence of heat stress. These results suggest that the DnaK2 protein plays an important role in protecting A. halophytica against damage caused by salt stress at well as heat stress.