• Molecular & Cellular Toxicology
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• v.1 no.4
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• pp.275-280
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• 2005

Carbon tetrachloride ($CCl_4$) is well known hepatotoxicant. Its overdose cause severe centrilobular hepatic necrosis in human and experimental animals. We administered $CCl_{4}$ at low (0.2 mL/kg p.o.) and high (2 mL/kg p.o.) doses to mice. Mice were sacrificed at 24 h after administration. We evaluated liver toxicity by serum AST and ALT level and by microscopic observation. Using cDNA chip, we conducted gene expression analysis in liver. Mean serum activities of the hepatocellular leakage enzymes, ALT and AST, were significantly increased compare to control, respectively, in the low and high dose groups. H&E evaluation of stained liver sections revealed $CCl_{4}-related$ histopathological findings in mice. Moderate centrilobular hepatocellular necrosis was present in all $CCl_{4}$ treated mice. We found that gene expression pattern was very similar between low and high dose group. However, some stress related genes were differently expressed. These results could be a molecular signature for the degree of liver injury. Our data suggest that the degree of severity could be figure out by gene expression profiling.

• Molecular & Cellular Toxicology
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• v.3 no.4
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• pp.299-305
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• 2007

The endocrine disrupting chemical, di (2-ethylhexyl) phthalate (DEHP) is a plasticizer used in polyvinyl chloride products ubiquitous in our daily lives. DEHP has potentially adverse effects on the liver, kidney, lung, heart, reproductive organs and endocrine systems. Many toxicological data on the DEHP toxicity have been stated, but complete protein profiles have not yet been reported. In this study, DEHP-induced oxidative DNA damage in rat lymphocyte was evaluated by Comet assay (single-cell gel electrophoresis) for the first time. Moreover, DEHP-induced protein profile alterations were examined in rat liver by using toxicoproteomic tools. 34 protein spots in the liver were identified to be significantly deregulated by DEHP on the 2-dimensional gel. Among them, 20 spots were up-regulated and 14 spots down-regulated by DEHP.

• Molecular & Cellular Toxicology
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• v.2 no.4
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• pp.236-243
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• 2006

Microarray analysis of gene expression has become a powerful approach for exploring the biological effects of drugs, particularly at the stage of toxicology and safety assessment. Acetaminophen (APAP) has been known to induce necrosis in liver, but the molecular mechanism involved has not been fully understood. In this study, we investigated gene expression changes of APAP using microarray technology. APAP was orally administered with a single dose of 50 mg/kg or 500 mg/kg into ICR mice and the animals were sacrificed at 6, 24 and 72 h of APAP administration. Serum biochemical markers for liver toxicity were measured to estimate the maximal toxic time and hepatic gene expression was assessed using high-density oligonucleotide microarrays capable of determining the expression profile of >30,000 well-substantiated mouse genes. Significant alterations in gene expression were noted in the liver of APAP-administered mice. The most notable changes in APAP-administered mice were the expression of genes involved in apoptosis, cell cycle, and calcium signaling pathway, cystein metabolism, glutatione metabolism, and MAPK pathway. The majority of the genes upregulated included insulin-like growth factor binding protein 1, heme oxygenase 1, metallothionein 1, S100 calcium binding protein, caspase 4, and P21. The upregulation of apoptosis and cell cycle-related genes were paralleled to response to APAP. Most of the affected gene expressions were returned to control levels after 72 hr. In conclusion, we identified potential hepatotoxicity makers, and these expressions profiling lead to a better understanding of the molecular basis of APAP-induced hapatotoxicity.

• Molecular & Cellular Toxicology
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• v.2 no.3
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• pp.185-192
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• 2006

To elucidate the molecular mechanisms associated with early renal injury induced by gentamicin, the most commonly used antibiotics worldwide in the treatment of Gram-negative bacterial infections. We have identified genes differentially expressed at different duration of gentamicin administration. C57BL/6 female mice were treated daily with gentamicin (20 mg/kg, 100 mg/kg, and 200mg/kg) for 7 days and then sacrificed at day 1, 3, and 7 after administration. Standard blood biochemistry and histopathological observation indicative of nephrotoxicity were made. Total RNA was extracted from the kidney for microarray analysis using Affymetrix $GeneChip^{\circledR}$. Five hundred and seventy eight genes were identified as being either up-or down-regulated over 2-fold changes during early renal injury (p<0.05) and were analyzed by hierarchical clustering. The results showed that the genes involved in early immune responses were differentially regulated during early renal injury. Principal component analysis (PCA) confirmed sample separation according to the degree of renal toxicity. In addition, we identified two potential biomarkers that may predict early renal toxicity. This data may contribute to elucidate of the genetic events during early renal injury and to discover the potential biomarkers for nephrotoxicity induced by gentamicin.

• Development and Reproduction
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• v.27 no.4
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• pp.185-193
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• 2023

Although increasing evidence of cause-and-effect relationship between BPA exposure and female reproductive disorders have been suggested through many studies, the precise biochemical and molecular mechanism(s) by which BPA interferes with steroidogenesis in the ovarian cells still remain unclear. Therefore, the purpose of this study was to discover the steroidogenic biomarker(s) associated with BPA treatment in human granulosa cell line, KGN. In this study, our results obtained via the analysis of steroidogenesis-related protein expression in KGN cells using quantitative polymerase chain reaction (qPCR) and western blot analyses revealed that the expression levels of steroidogenic acute regulatory (StAR) and aromatase decreased considerably and gradually after BPA treatment in a dose-dependent manner under BPA treatment. Further, remarkable decreases in their expression levels at the cellular levels were also confirmed via immunocytochemistry, and subsequent StAR and aromatase mRNA expression levels showed profiles similar to those observed for their proteins, i.e., both StAR and aromatase mRNA expression levels were significantly decreased under BPA treatment at concentrations ≥0.1 μM. We observed that follicle stimulating hormone upregulated StAR and aromatase protein expression levels; however, this effect was suppressed in the presence of BPA. Regarding the steroidogenic effects of BPA on KGN cells, controversies remain regarding the ultimate outcomes. Nevertheless, we believe that the results here presented imply that KGN cells have a good cellular and steroidogenic machinery for evaluating endocrine disruption. Therefore, StAR and aromatase could be stable and sensitive biomarkers in KGN cells for the cellular screening of the potential risk posed by exogenous and environmental chemicals to female reproductive (endocrine) function.

• Molecular & Cellular Toxicology
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• v.2 no.1
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• pp.48-53
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• 2006

[ ${\alpha}-Naphthylisothiocyanate$ ] (ANIT) induces intrahepatic cholestasis, involving damage to biliary epitheial cells. This study investigates hepatic gene expression and histopathological alterations in response to ANIT treatment in order to elucidate early time response of ANIT-induced hepatotoxicity. ANIT was treated with single dose (3, 6, and 60 mg/kg) in corn oil by oral gavage. Serum biochemical and histopathological observation were performed for evaluation of hepatotoxicity level. Affymetrix oligo DNA chips were used for gene expression profile by ANIT-induced hetpatoxicity. Hepatic enzyme levels (ALT, AST, and ALP) were increased in 24 hr high dose group. In microscopic observations, moderate hepatocellular necrosis, were confirmed 24 hr high dose groups. We found that gene expression patterns were dependent on time and dose. Our selected genes were related inflammation and immunomodulation. In this study, ANIT-induced hepatotoxicity was involved in acute phase responses and provides evidence for role of neutrophil could be mechanism associated with ANIT-mediated hepatotoxicity.

• Molecules and Cells
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• v.42 no.12
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• pp.850-857
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• 2019

The Gram-negative opportunistic pathogen, Pseudomonas aeruginosa, has multiple multidrug efflux pumps. MexT, a LysR-type transcriptional regulator, functions as a transcriptional activator of the MexEF-OprN efflux system. MexT consists of an N-terminal DNA-binding domain and a C-terminal regulatory domain (RD). Little is known regarding MexT ligands and its mechanism of activation. We elucidated the crystal structure of the MexT RD at 2.0 Å resolution. The structure comprised two protomer chains in a dimeric arrangement. MexT possessed an arginine-rich region and a hydrophobic patch lined by a variable loop, both of which are putative ligand-binding sites. The three-dimensional structure of MexT provided clues to the interacting ligand structure. A DNase I footprinting assay of full-length MexT identified two MexT-binding sequence in the mexEF-oprN promoter. Our findings enhance the understanding of the regulation of MexT-dependent activation of efflux pumps.

• Molecules and Cells
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• v.42 no.1
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• pp.79-86
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• 2019

Endolysins are bacteriophage-derived enzymes that hydrolyze the peptidoglycan of host bacteria. Endolysins are considered to be promising tools for the control of pathogenic bacteria. LysB4 is an endolysin produced by Bacillus cereus-infecting bacteriophage B4, and consists of an N-terminal enzymatic active domain (EAD) and a C-terminal cell wall binding domain (CBD). LysB4 was discovered for the first time as an L-alanoyl-D-glutamate endopeptidase with the ability to breakdown the peptidoglycan among B. cereus-infecting phages. To understand the activity of LysB4 at the molecular level, this study determined the X-ray crystal structure of the LysB4 EAD, using the full-length LysB4 endolysin. The LysB4 EAD has an active site that is typical of LAS-type enzymes, where $Zn^{2+}$ is tetrahedrally coordinated by three amino acid residues and one water molecule. Mutational studies identified essential residues that are involved in lytic activity. Based on the structural and biochemical information about LysB4, we suggest a ligand-docking model and a putative endopeptidase mechanism for the LysB4 EAD. These suggestions add insight into the molecular mechanism of the endolysin LysB4 in B. cereus-infecting phages.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.176-176
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• 2003

Methylmercury is known to have devastating effects on the mammalian nervous system. When human neuroblastoma SH-SY5Y cells were treated with methylmercury at sublethal concentrations (6.25 uM), up-regulated genes (39) ＆ down-regulated genes (19) were identified by human 8k cDNA microarray. These genes are related with microtubule process, signal transduction pathway and cell death (apoptosis), Apoptosis-associated genes, HSP70, CDK inhibitor 1, FOS-like antigen were up-regulated and microtubule related genes like villin and dynein down-regultaed. To confirm the presence of apoptosis in cultured SH-SY5Y cells treated 6.25 and 1 uM methylmercury, we applied Annexin V-FITC assay followed by flow cytometric measurements after 6 and 24h. Studies on transcriptional and molecular effect by methylmercury may provide an insight into the neurotoxic effects of methylmercury in human neuronal cells and a possibility to develop more efficient and exact monitoring system of heavy metals as ubiquitous environmental pollutants.

• Molecular & Cellular Toxicology
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• v.3 no.2
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• pp.77-84
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• 2007

Millions of individuals worldwide are currently afflicted with neurodegenerative disorders such as Parkinson's disease and multiple sclerosis which are caused by the death of specific types of specialized cells in the Central Nervous System (CNS). Recently, Neural Stem Cells (NSCs) are able to replace these dead cells with new functional cells, thereby providing a cure for devastating neural diseases. The clinical use of neural stem cells (NSCs) for the treatment of neurological diseases requires overcoming the scarcity of the initial in vivo NSC population. Thus, we developed a novel 3-dimentional cellular automata model for optimum production of neural stem cells and their derivatives in large scale to treat neurodegenerative disorder patients.