• Journal of Life Science
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• v.23 no.10
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• pp.1216-1222
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• 2013

NK cells are lymphoid immune cells that participate in innate immunity to protect against foreign pathogens and transforming cells. It is known that the activity of NK cells is regulated by a balance between activating and inhibitory signals rather than specific antigens. One important activating signal is mediated by the NKG2D receptor, which recognizes NKG2D ligands on cancer cells. Therefore, tumor cells that express sufficient amounts of NKG2D ligands could be eliminated by NKD2D+ cells, including NK cells. Oncogenes drive tumor cells to apoptosis resistant and uncontrolled proliferation by altered expression of many critical genes. Therefore, the expression of NKG2D ligands may be affected by oncogenes. This study focused on increasing the susceptibility of cancer cells to NK cells by regulating the expression of NKG2D ligands influenced by three oncogenes: k-ras, wnt, and c-myc. We demonstrated that inhibition of k-ras and c-myc increased the expression of NKG2D ligands and enhanced the susceptibility of cancer cells to NK cells. On the contrary, inhibition of the wnt pathway decreased MICA and ULBP1 transcripts. Although the decreased transcription of NKG2D ligands by inhibition of the wnt pathway, surface proteins of NKG2D ligands were not changed, and the susceptibility of HCT-116 cells was unaffected. The results demonstrate that the transcription of NKG2D ligands are regulated deferentially by the k-ras, c-myc, and wnt pathways and that the cytotoxicity of NK cells solely depends on the amount of surface NKG2D ligands.

• Molecules and Cells
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• v.20 no.2
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• pp.235-240
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• 2005

Extracts of pine needles (Pinus densiflora Sieb. et Zucc.) have diverse physiological and pharmacological actions. In this study we show that pine needle extract alters pacemaker currents in interstitial cells of Cajal (ICC) by modulating ATP-sensitive $K^+$ channels and that this effect is mediated by prostaglandins. In whole cell patches at $30^{\circ}C$, ICC generated spontaneous pacemaker potentials in the current clamp mode (I = 0), and inward currents (pacemaker currents) in the voltage clamp mode at a holding potential of -70 mV. Pine needle extract hyperpolarized the membrane potential, and in voltage clamp mode decreased both the frequency and amplitude of the pacemaker currents, and increased the resting currents in the outward direction. It also inhibited the pacemaker currents in a dose-dependent manner. Because the effects of pine needle extract on pacemaker currents were the same as those of pinacidil (an ATP-sensitive $K^+$ channel opener) we tested the effect of glibenclamide (an ATP-sensitive $K^+$ channels blocker) on ICC exposed to pine needle extract. The effects of pine needle extract on pacemaker currents were blocked by glibenclamide. To see whether production of prostaglandins (PGs) is involved in the inhibitory effect of pine needle extract on pacemaker currents, we tested the effects of naproxen, a non-selective cyclooxygenase (COX-1 and COX-2) inhibitor, and AH6809, a prostaglandin EP1 and EP2 receptor antagonist. Naproxen and AH6809 blocked the inhibitory effects of pine needle extract on ICC. These results indicate that pine needle extract inhibits the pacemaker currents of ICC by activating ATP-sensitive $K^+$ channels via the production of PGs.

• The Korean Journal of Pharmacology
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• v.29 no.1
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• pp.43-55
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• 1993

The present study was conducted to examine the characteristics of histamine on catecholamine secretion in the isolated perfused rat adrenal gland and to clarify the mechanism of its secretory action. Histamine (37.5 to 150 ug) injected into an adrenal vein evoked a dose-dependent significant secretory response of catecholamines (CA) from the rat adrenal gland. However, upon the repeated injection of histamine (150 ug) at 120 min intervals, CA secretion was rapidly decreased after third injection of histamine. Tachyphylaxis to releasing effects of CA evoked by histamine was observed by the repeated administration. The histamine-induced CA secretion was markedly inhibited by the pretreatment with chlorisondamine, diphenhydramine, ranitidine, $Ca^{++}-free$ Krebs solution, nicardipine and TMB-8 while was not affected by pirenzepine. Moreover, the CA secretion evoked by ACh was considerably reduced by the prior perfusion of histamine $(6.8{\times}10^{-5} M)$ for 30 min. These experimental data suggest that histamine causes secretion of CA in a calcium dependent manner from the perfused rat adrenal gland and that its secretory effect is mediated through activation of both $H_1-$ and $H_2-histaminergic$ receptors located in adrenal medulla, which may be associated with stimulation of cholinergic nicotinic receptors.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.3
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• pp.149-156
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• 2011

Golgi SNAP receptor complex 1 (GS28) has been implicated in vesicular transport between intra-Golgi networks and between endoplasmic reticulum (ER) and Golgi. Additional role(s) of GS28 within cells have not been well characterized. We observed decreased expression of GS28 in rat ischemic hippocampus. In this study, we examined the role of GS28 and its molecular mechanisms in neuronal (SK-N-SH) cell death induced by hydrogen peroxide ($H_2O_2$). GS28 siRNA-transfected cells treated with $H_2O_2$ showed a significant increase in cytotoxicity under glutathione (GSH)-depleted conditions after pretreatment with buthionine sulfoximine, which corresponded to an increase of intracellular reactive oxygen species (ROS) in the cells. Pretreatment of GS28 siRNA-transfected cells with p38 chemical inhibitor significantly inhibited cytotoxicity; we also observed that p38 was activated in the cells by immunoblot analysis. We confirmed the role of p38 MAPK in cotransfected cells with GS28 siRNA and p38 siRNA in the cell viability assay, flow cytometry, and immunoblot. Involvement of apoptotic or autophagic processes in the cells was not shown in the cell viability, flow cytometry, and immunoblot analyses. However, pretreatment of the cells with necrostatin-1 completely inhibited $H_2O_2$-induced cytotoxicity, ROS generation, and p38 activation, indicating that the cell death is necroptotic. Collectively these data imply that $H_2O_2$ induces necroptotic cell death in the GS28 siRNA-transfected cells and that the necroptotic signals are mediated by sequential activations in RIP1/p38/ROS. Taken together, these results indicate that GS28 has a protective role in $H_2O_2$-induced necroptosis via inhibition of p38 MAPK in GSH-depleted neuronal cells.

• Korean journal of applied entomology
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• v.55 no.4
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• pp.413-419
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• 2016

Ryanodine receptors (RyRs) regulate the contractions of insect muscles by altering intracellular $Ca^{2+}$ concentration and are the targets of chlorantraniliprole. Recently, a chlorantraniliprole-resistant strain was reported in the diamondback moth Plutella xylostella by obtaining point mutations on the RyRs. In the present study, we established two resistant strains from Drosophila melanogaster, which were treated with low or high concentrations of chlorantraniliprole, and their resistance levels were determined on the basis of contact and ingestion toxicities. Compared with the control strain, the two resistant strains did not show any significant differences in contact toxicity. However, they showed significantly increased resistance ratios in ingestion toxicity than that by the control strain. The low and high concentration resistant strains exhibited 2.1- and 8.1-fold increased resistance ratios, respectively, compared with that by the control strain. Moreover, we found that the resistant strains had altered expression levels of RyRs and more enhanced Acetylcholinesterase and Glutathione-S-transferase activities than that by the non-selected strain. These results suggested that the resistance development of chlorantraniliprole in the two strains might be mediated by the activation of detoxification pathways in D. melanogaster.

• IMMUNE NETWORK
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• v.2 no.1
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• pp.53-59
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• 2002

Background: Clinical observations and laboratory studies have supported an immune basis for most acquired aplastic anemias, with the majority of patients responding to immunosuppressive therapy. Fas, a member of the tumor necrosis factor (TNF) receptor superfamily is a critical downregulator of cellular immune responses. Proinflammatory cytokines like interferon gamma (IFN-${\gamma}$) and TNF-${\alpha}$ can induce Fas expression and render hematopoietic progenitor cells susceptible to Fas-induced growth suppression and apoptosis. Methods: In order to investigate the involvement of apoptosis in the pathogenesis of aplastic anemia (AA), we measured the expression of Fas antigen and caspase-3 on bone marrow (BM) mononuclear cells (MNCs) of AA in the presence or absence of IFN-${\gamma}$, TNF-${\alpha}$, or macrophage inflammatory protein 1-${\alpha}$ (MIP-$1{\alpha}$). Results: We confirmed that AA BM MNCs were more apoptotic and highly expressed Fas antigen than normal donors. Stimulation by IFN-${\gamma}$, TNF-${\alpha}$, or MIP-$1{\alpha}$ increased Fas antigen and caspase-3 expression in AA BM MNCs than BM MNCs of normal donors. Anti-Fas monoclonal antibody enhanced IFN-${\gamma}$, TNF-${\alpha}$, or MIP$1{\alpha}$ mediated caspase-3 expression in BM MNCs of normal donors. Among these three cytokines, IFN-${\gamma}$ enhanced apoptosis most strongly via Fas-caspase-3 pathway. Conclusion: These results suggest that Fas signal pathway may play a role in the pathophysiology of aplastic anemia and negative hematopoietic regulators like IFN-${\gamma}$ can induce apoptosis of bone marrow progenitors in part by Fas induction.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.3
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• pp.345-353
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• 2002

Bone morphogenetic proteins(BMPs) are secretory signal molecules which have a variety of regulatory functions during morphogenesis and cell differentiation. To evaluate roles of BMPs and their receptors on mouse sagittal suture development, we have examined their expression patterns in serial sections of sagittal sutures by in situ hybridization during embryonic stages(E15-E18). BMP-2 and BMP-3 were expressed in the osteogenic front and parietal bone on embryonic 15day, from E16 in hair follicle. BMP-4 was strongly expressed in the osteogenic front and weakly expressed in the mesenchyme and parietal bone. BMP-S was expressed in the hair follicles. BMP-6 was not expressed in this study. BMP-7 was expressed in parietal bone during embryonic stage. BMPR-IB was expressed in the osteogenic front, but BMPR-IA was not. From these datas, we suggest that the BMP-4 regulates the early commitment of mesenchymal cells to the osteogenic lineages, the BMP-2 and BMP-3 may be involved in regulating the differentiation of osteoblast precursor cells. BMP-7 was involved in maintenance of differentiated osteoblasts. BMPs were key signaling molecules that regulate early calvarial bone morphogenesis, mediated by BMPR-IB.

• Journal of Ginseng Research
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• v.24 no.4
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• pp.168-175
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• 2000

Relatively little is known about the signaling mechanism of ginseng saponins (ginsenosides), active ingredients of ginseng, in non-neuronal cells. Here, we describe that ginsenosides utilize a common pathway of receptor-mediated signaling pathway in Xenopus oocytes: increase in intracellular $Ca^{2+}$ concentration via phospholipase C (PLC) and $Ca^{2+}$ mobilization. Ginsenosides induced a marked and robust artivation of $Ca^{2+}$-activated Cl- channels in Xenopus oocytes. The effect of ginsenosides was completely reversible, in a dose-dependent manner with EC$_{50}$ of 4.4 $\mu\textrm{g}$/mi, and specifically blocked by niflumic acid, an inhibitor of $Ca^{2+}$-activated Cl- channel. Intracellular injection of BAPIA abolished the effect of ginsenosides. Intracellular injection of GTP${\gamma}$S also abolished the effect of ginsenosides. The effect of gin senosides on $Ca^{2+}$-activated Cl- currents was greatly reduced by the intracellular injection of heparin, an IP$_3$ receptorantagonist or the pretreatment of PLC inhibitor. These results indicate that ginsenosides activate endogenous $Ca^{2+}$-activated Cl- channels via the activation of PLC and the release of $Ca^{2+}$ from the IP$_3$-sensitive intracellular store following the initial interaction with membrane component(s) from extracellular side. This signaling pathway of ginsenosides may be one of the action mechanisms for the pharmacological effects of ginseng.ts of ginseng.

• Journal of Ginseng Research
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• v.39 no.4
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• pp.398-405
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• 2015

Background: Ginseng has been used as a tonic for invigoration of the human body. In a previous report, we identified a novel candidate responsible for the tonic role of ginseng, designated gintonin. Gintonin induces $[Ca^{2+}]_i$ transient in animal cells via lysophosphatidic acid receptor activation. Gintonin-mediated $[Ca^{2+}]_i$ transient is linked to anti-Alzheimer's activity in transgenic Alzheimer's disease animal model. The previous method for gintonin preparation included multiple steps. The aim of this study is to develop a simple method of gintonin fraction with a high yield. Methods: We developed a brief method to obtain gintonin using ethanol and water. We extracted ginseng with fermentation ethanol and fractionated the extract with water to obtain water-soluble and water-insoluble fractions. The water-insoluble precipitate, rather than the water-soluble supernatant, induced a large $[Ca^{2+}]_i$ transient in primary astrocytes. We designated this fraction as gintonin-enriched fraction (GEF). Results: The yield of GEF was approximately 6-fold higher than that obtained in the previous gintonin preparation method. The apparent molecular weight of GEF, determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was equivalent to that obtained in the previous gintonin preparation method. GEF induced $[Ca^{2+}]_i$ transient in cortical astrocytes. The effective dose (ED50) was $0.3{\pm}0.09{\mu}g/mL$. GEF used the same signal transduction pathway as gintonin during $[Ca^{2+}]_i$ transient induction in mouse cortical astrocytes. Conclusion: Because GEF can be prepared through water precipitation of ginseng ethanol extract and is easily reproducible with high yield, it could be commercially utilized for the development of gintoninderived functional health food and natural medicine.

• Journal of Ginseng Research
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• v.32 no.2
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• pp.107-113
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• 2008

In this study, we have investigated the effect of panaxatriol (PT) on phosphoinositides (PIS) breakdown and $Ca^{2+}$-elevation in thrombin-induced platelet aggregation. Thrombin (5U/ml), a potent platelet agonist which activates phospholipase $C_{\beta}$ via protease activated receptor (PAR), hydrolyzed PIS in platelet membrane. The phosphatidylinositol 4, 5-bisphosphate $(PIP_2)$ was hydrolyzed after 10 sec of the thrombin-stimulation, and both the phosphatidylinositol 4-monophosphate (PIP) and phosphatidylinositol (PI) were brokendown after 30 sec of the thrombin-stimulation. However, PT inhibited the thrombin-stimulated hydrolysis of $PIP_2$, PIP, and PI. On the other hand, thrombin increased the level of phosphatidic acid (PA) which is phosphorylated from diacylglycerol (DG) generated by PIS-hydrolysis. However, Pr inhibited the thrombin-increased PA level non-significantly. Thrombin increased cytosolic free $Ca^{2+}([Ca^{2+}])_i$) up to 72% as compared with control $(30.8{\pm}0.9 nM)$ in intact platelet. However, PT (100 ${\mu}g/ml$) inhibited the thrombin-elevated $[Ca^{2+}]_i$ to 100%. These results suggest that PT may have a beneficial effect on platelet aggregation-mediated thrombotic disease by inhibiting thrombin-induced platelet aggregation via suppression of the $[Ca^{2+}]_i$ level and PIS breakdown.