• The Korean Journal of Mycology
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• v.36 no.2
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• pp.189-195
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• 2008

When a homothallic ascomycete Aspergillus nidulans is exposed to visible light, cleistothecial development is inhibited. The light response of development in A. nidulans implies the existence of delicate regulation process including reception and translocation of light signaling and determination of development. Previously, mutants that could develop cleistothecia even in the presence of relatively intensive visible light were isolated and several complementation groups were identified. A gene that was able to complement the silA98 mutation, which was responsible for preferred cleistothecia development under visible light, was isolated from AMA-NotI genomic library. The silA gene retained in the 4.3 kb recovered genomic library DNA has an open reading frame (ORF) consisted of 2,388 bp nucleotides, interrupted by 3 introns and consequently encoding 795 amino acids. The putative SilA carries a ${Zn_2}{Cys_6}$ binuclear cluster motif at N terminus and shows high amino acid sequence similarity to Aro80p of Saccharomyces cerevisiae. Deletion mutants of silA showed a strong induction of sexual development under visible light, indicating that SilA is involved in the negative regulation of sexual development in response to the light.

• Journal of Physiology & Pathology in Korean Medicine
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• v.29 no.6
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• pp.492-497
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• 2015

In the present study, vasorelaxant effect of the extract of seeds of Oenothera odorata (SOO) and its possible mechanism responsible for this effect were examined in vascular tissues isolated from rats. Changes in vascular tension, 3',5'-cyclic monophosphate (cGMP) levels were measured in thoracic aorta rings from rats. Methanol extract of seeds of Oenothera odorata relaxed endothelium-intact thoracic aorta in a dose-dependent manner. A dose-dependent vascular relaxation was also revealed by treatment of ethylacetate, n-butanol, and H₂O (aqua extract of seeds of Oenothera odorata , ASOO) extracts partitioned from methanol, but not by hexane extract. However, the vascular relaxation induced by ASOO were abolished by removal of endothelium of aortic tissues. Pretreatment of the endothelium-intact vascular tissues with N^G-nitro-L-arginine methyl ester (L-NAME) or ¹H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1- one (ODQ) significantly inhibited vascular relaxation induced by ASOO. Moreover, incubation of endothelium-intact aortic rings with ASOO increased the production of cGMP. However, ASOO-induced increases in cGMP production were blocked by pretreatment with L-NAME or ODQ. The vasorelaxant effect of ASOO was attenuated by tetraethylammonium (TEA), 4-aminopyridine, and glibenclamide attenuated. On the other hand, the ASOO-induced vasorelaxation was not blocked by verapamil, and diltiazem. Taken together, the present study demonstrates that ASOO dilate vascular smooth muscle via endothelium-dependent NO-cGMP signaling pathway, which may be closely related with the function of K⁺ channels.

• Molecular & Cellular Toxicology
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• v.3 no.2
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• pp.98-106
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• 2007

Genotoxic stress triggers a variety of biological responses including the transcriptional activation of genes regulating DNA repair, cell survival and cell death. In this study, we investigated to examine gene expression profiles and genotoxic response in TK6 cells treated with DNA damaging agents MNNG (N-methyl-N'-nitrosoguanidine) and hydrogen peroxide $(H_2O_2)$. We extracted total RNA in three independent experiments and hybridized cRNA probes with oligo DNA chip (Applied Biosystems Human Genome Survey Microarray). We analyzed raw signal data with R program and AVADIS software and identified a number of deregulated genes with more than 1.5 log-scale fold change and statistical significancy. We indentified 14 genes including G protein alpha 12 showing deregulation by MNNG. The deregulated genes by MNNG represent the biological pathway regarding MAP kinase signaling pathway. Hydrogen peroxide altered 188 genes including sulfiredoxins. These results show that MNNG and $H_2O_2$ have both uniquely regulated genes that provide the potential to serve as biomarkers of exposure to DNA damaging agents.

• Journal of Animal Science and Technology
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• v.56 no.2
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• pp.6.1-6.4
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• 2014

The aims of study were to investigate the effects of intraperitoneal (i.p.) infusion of ghrelin on pancreatic ${\alpha}$-amylase outputs and the responses of pancreatic proteins to ghrelin that may relate to the pancreatic exocrine. Six male Sprague-Dawley rats (300 g) were randomly divided into two groups, a control group (C, n = 3) and a treatment group (T, $10.0{\mu}g/kg$ BW, n = 3). Blood samples were collected from rat caudal vein once time after one hour injection. The concentrations of plasma ghrelin, cholecystokinin (CCK) and alfa-amylase activity were evaluated by enzyme immunoassay (EIA) kit. Two-dimensional gel electrophoresis (2-DE) analysis was conducted to separate the proteins in pancreas tissue. Results showed that the i.p. infusion of ghrelin at doses of $10.0{\mu}g/kg$ body weight (BW) increased the plasma ghrelin concentrations (p = 0.07) and elevated the plasma CCK level significantly (p < 0.05). Although there was no statistically significant, the ${\alpha}$-amylase activity tended to increase. The proteomics analysis indicated that some pancreatic proteins with various functions were up- or down-regulated compared with control group. In conclusion, ghrelin may have role in the pancreatic exocrine, but the signaling pathway was still not clear. Therefore, much more functional studies focus on these found proteins are needed in the near future.

• Journal of Periodontal and Implant Science
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• v.45 no.3
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• pp.101-110
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• 2015

Purpose: Sclerostin, an inhibitor of Wnt/${\beta}$-catenin signaling, exerts negative effects on bone formation and contributes to periodontitis-induced alveolar bone loss. Recent studies have demonstrated that serum sclerostin levels are increased in diabetic patients and that sclerostin expression in alveolar bone is enhanced in a diabetic periodontitis model. However, the molecular mechanism of how sclerostin expression is enhanced in diabetic patients remains elusive. Therefore, in this study, the effect of hyperglycemia on the expression of sclerostin in osteoblast lineage cells was examined. Methods: C2C12 and MLO-Y4 cells were used in this study. In order to examine the effect of hyperglycemia, the glucose concentration in the culture medium was adjusted to a range of levels between 40 and 100 mM. Gene expression levels were examined by quantitative reverse transcription-polymerase chain reaction and Western blot assays. Top-Flash reporter was used to examine the transcriptional activity of the ${\beta}$-catenin/lymphoid enhanced factor/T-cell factor complex. Tumor necrosis factor-alpha ($TNF{\alpha}$) protein levels were examined with the enzyme-linked immunosorbent assay. The effect of reactive oxygen species on sclerostin expression was examined by treating cells with 1 mM $H_2O_2$ or 20 mM N-acetylcysteine. Results: The high glucose treatment increased the mRNA and protein levels of sclerostin. High glucose suppressed Wnt3a-induced Top-Flash reporter activity and the expression levels of osteoblast marker genes. High glucose increased reactive oxygen species production and $TNF{\alpha}$ expression levels. Treatment of cells with $H_2O_2$ also enhanced the expression levels of $TNF{\alpha}$ and sclerostin. In addition, N-acetylcysteine treatment or knockdown of $TNF{\alpha}$ attenuated high glucose-induced sclerostin expression. Conclusions: These results suggest that hyperglycemia increases sclerostin expression via the enhanced production of reactive oxygen species and $TNF{\alpha}$.

• Journal of Life Science
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• v.13 no.6
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• pp.903-910
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• 2003

Phospholipase D (PLD) plays an important role as a signaling molecule in the activation of neutrophils. In this study, effect of nitric oxide (NO) and cGMP on the activation of PLD in human neutrophils was investigated. Sodium nitroprusside (SNP), an agent to produce NO spontaneously in cells, alone increased PLD activity and the maximal activation was obtained with 0.5 mM SNP. Dibutyryl-cAMP, an agent to increase an intracellular cAMP concentration inhibited formyl-Met-Leu-Phe (fMLP)-stimulated PLD activity but 8-bromo-cGMP (300 $\mu$M), an agent to increase an intracellular cGMP concentration did not affect basal and fMLP-stimulated PLD activity. NO-induced activation of PLD was not blocked by KT 5823, an inhibitor of cGMP-dependent protein kinase (PKG), suggesting that NO-induced PLD activation is not mediated by cGMP. NO also stimulated p38 mitogen activated protein kinase (MAPK) in human neutrophils, indicated by increased phosphorylation of p38 MAPK in Western blotting. NO-induced phosphorylation of p38 MAPK was not inhibited by KT 5823 or n-butanol. RhoA, an regulatory factor of PLD activation was trans-located from cytosolic fraction to plasma membranes by fMLP or phorbol ester, and fMLP-stimulated but not phorbol ester-stimulated translocation of RhoA was inhibited by cGMP. These results suggest that NO stimulates PLD activity through other unidentified facto.(s) than cGMP even though cGMP inhibits the artivation of RhoA.

• Tuberculosis and Respiratory Diseases
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• v.78 no.2
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• pp.99-105
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• 2015

Background: Aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor, binds to a wide variety of synthetic and naturally occurring compounds. AhR is involved in the regulation of inflammatory response during acute and chronic respiratory diseases. We investigated whether nuclear receptor coactivator 7 (NCOA7) could regulate transcriptional levels of AhR target genes and inflammatory cytokines in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-treated human bronchial epithelial cells. This study was based on our previous study that NCOA7 was differentially expressed between normal and chronic obstructive pulmonary disease lung tissues. Methods: BEAS-2B and A549 cells grown under serum-free conditions were treated with or without TCDD (0.15 nM and 6.5 nM) for 24 hours after transfection of pCMV-NCOA7 isoform 4. Expression levels of cytochrome P4501A1 (CYP1A1), IL-6, and IL-8 were measured by quantitative real-time polymerase chain reaction. Results: The transcriptional activities of CYP1A1 and inflammatory cytokines were strongly induced by TCDD treatment in both BEAS-2B and A549 cell lines. The NCOA7 isoform 4 oppositely regulated the transcriptional activities of CYP1A1 and inflammatory cytokines between BEAS-2B and A549 cell lines. Conclusion: Our results suggest that NCOA7 could act as a regulator in the TCDD-AhR signaling pathway with dual roles in normal and abnormal physiological conditions.

• Biomolecules & Therapeutics
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• v.28 no.5
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• pp.456-464
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• 2020

Mast cells (MCs) are systemically distributed and secrete several allergic mediators such as histamine and leukotrienes to cause type I hypersensitivity. Dasatinib is a type of anti-cancer agent and it has also been reported to inhibit human basophils. However, dasatinib has not been reported for its inhibitory effects on MCs or type I hypersensitivity in mice. In this study, we examined the inhibitory effect of dasatinib on MCs and MC-mediated allergic response in vitro and in vivo. In vitro, dasatinib inhibited the degranulation of MCs by antigen stimulation in a dose-dependent manner (IC₅₀, ~34 nM for RBL-2H3 cells; ~52 nM for BMMCs) without any cytotoxicity. It also suppressed the secretion of inflammatory cytokines IL-4 and TNF-α by antigen stimulation. Furthermore, dasatinib inhibited MC-mediated passive cutaneous anaphylaxis (PCA) in mice (ED₅₀, ~29 mg/kg). Notably, dasatinib significantly suppressed the degranulation of MCs in the ear tissue. As the mechanism of its effect, dasatinib inhibited the activation of Syk and Syk-mediated downstream signaling proteins, LAT, PLCγ1, and three typical MAP kinases (Erk1/2, JNK, and p38), which are essential for the activation of MCs. Interestingly, in vitro tyrosine kinase assay, dasatinib directly inhibited the activities of Lyn and Fyn, the upstream tyrosine kinases of Syk in MCs. Taken together, dasatinib suppresses MCs and PCA in vitro and in vivo through the inhibition of Lyn and Fyn Src-family kinases. Therefore, we suggest the possibility of repositioning the anti-cancer drug dasatinib as a treatment for various MC-mediated type I hypersensitive diseases.

• Journal of Life Science
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• v.31 no.10
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• pp.954-959
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• 2021

Apoptosis is an important mechanism that regulates cellular populations to maintain homeostasis, and the caspases, a family of cysteine proteases, are key mediators of the apoptosis pathway. Caspase-8 is an initiator caspase of the extrinsic apoptotic pathway, which is initiated by extracellular stimuli. Caspase-8 have two conserved domains, N-terminal tandem death effector domains (DED) and C-terminal two catalytic domain, which are important for this extrinsic apoptosis pathway. In extrinsic apoptosis pathway, death receptors which members of TNF superfamily are activated by binding of death receptor specific ligands from cell outside. After the activated death receptors recruit adaptor protein Fas-associated death domain protein (FADD), death domains (DD) of death receptor and FADD bind to each other and FADD combined with death receptor recruits procaspase-8, a precursor form of caspase-8. The DED of FADD and procaspase-8 bind to one another and FADD-bound procaspase-8 is activated by cleavage of the prodomain. This death receptor-FADD-caspase-8 complex called death inducing signaling complex (DISC). Cellular FLICE-inhibitory proteins (c-FLIPs) regulate caspase-8 activation by acting both anti- and pro-apoptotically, and caspase-8 activation initiates the activation of executioner caspases such as caspase-3. Finally activated executioner caspases complete the apoptosis by acting critically DNA degradation, nuclear condensation, plasma membrane blebbing, and the proteolysis of certain caspase substrates.

• BMB Reports
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• v.51 no.12
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• pp.660-665
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• 2018

Human epidermal growth factor receptor 2 (HER2) inhibitors, such as trastuzumab and lapatinib are used to treat HER2-positive breast and gastric cancers. However, as with other targeted therapies, intrinsic or acquired resistance to HER2 inhibitors presents unresolved therapeutic problems for HER2-positive gastric cancer. The present study describes investigations with AUY922, a heat shock protein 90 (HSP90) inhibitor, in primary lapatinib-resistant (ESO26 and OE33) and lapatinib-sensitive gastric cancer cells (OE19, N87, and SNU-216) harboring HER2 amplification/over-expression. In order to investigate whether AUY922 could overcome intrinsic and acquired resistance to HER2 inhibitors in HER2-positive gastric cancer, we generated lapatinib-resistant gastric cancer cell lines (OE19/LR and N87/LR) by continuous exposure to lapatinib in vitro. We found that activation of HER2 and protein kinase B (AKT) were key factors in inducing intrinsic and acquired lapatinib-resistant gastric cancer cell lines, and that AUY922 effectively suppressed activation of both HER2 and AKT in acquired lapatinib-resistant gastric cancer cell lines. In conclusion, AUY922 showed a synergistic anti-cancer effect with lapatinib and sensitized gastric cancer cells with intrinsic resistance to lapatinib. Dual inhibition of the HSP90 and HER2 signaling pathways could represent a potent therapeutic strategy to treat HER2-positive gastric cancer with intrinsic and acquired resistance to lapatinib.