• Journal of Korean Neurosurgical Society
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• v.46 no.4
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• pp.389-396
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• 2009

Objective : Triptolide (TP) has been reported to suppress the expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1), of which main function is to inactivate the extracellular signal-regulated kinase-1/2 (ERK-1/2), the p38 MAPK and the c-Jun N-terminal kinase-1/2 (JNK-1/2), and to exert antiproliferative and pro-apoptotic activities. However, the mechanisms underlying antiproliferative and pro-apoptotic activities of TP are not fully understood. The purpose of this study was to examine whether the down-regulation of MKP-1 expression by TP would account for antiproliferative activity of TP in immortalized HT22 hippocampal cells. Methods : MKP-1 expression and MAPK phosphorylation were analyzed by Western blot. Cell proliferation was assessed by $^3H$-thymidine incorporation. Small interfering RNA (siRNA) against MKP-1, vanadate (a phosphatase inhibitor), U0126 (a specific inhibitor for ERK-1/2), SB203580 (a specific inhibitor for p38 MAPK), and SP600125 (a specific inhibitor for JNK-1/2) were employed to evaluate a possible mechanism of antiproliferative action of TP. Results : At its non-cytotoxic dose, TP suppressed MKP-1 expression, reduced cell growth, and induced persistent ERK-1/2 activation. Similar growth inhibition and ERK-1/2 activation were observed when MKP-1 expression was blocked by MKP-1 siRNA and its activity was inhibited by vanadate. The antiproliferative effects of TP, MKP-1 siRNA, and vanadate were significantly abolished by U0126, but not by SB203580 or SP600125. Conclusion : Our findings suggest that TP inhibits the growth of immortalized HT22 hippocampal cells via persistent ERK-1/2 activation by suppressing MKP-1 expression. Additionally, this study provides evidence supporting that MKP-1 may play an important role in regulation of neuronal cell growth.

• IMMUNE NETWORK
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• v.5 no.4
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• pp.237-246
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• 2005

Background: Little information is available on the identification and characterization of the upstream regulators of the signal transduction cascades for Mycobacterium tuberculosis (M. tbc)-induced ERK 1/2 activation and chemokine expression. We investigated the signaling mechanisms involved in expression of CCL3 /MIP-1 and CCL4/MIP-1 in human primary monocytes infected with M. tbc. Methods: MAP kinase phosphorylation was determined using western blot analysis with specific primary antibodies (ERK 1/2, and phospho-ERK1/2), and the upstream signaling pathways were further investigated using specific inhibitors. Results: An avirulent strain, M. tbc H37Ra, induced greater and more sustained ERK 1/2 phosphorylation, and higher CCL3 and CCL4 production, than did M. tbc H37Rv. Specific inhibitors for mitogen-activated protein kinase (MAPK) kinase (MEK; U0126 and PD98059) significantly inhibited the expression of CCL3 and CCL4 in human monocytes. Mycobactetia-mediated expression of CCL3 and CCL4 was not inhibited by the Ras inhibitor manumycin A or the Raf-1 inhibitor GW 5074. On the other hand, phospholipase C (PLC) inhibitor (U73122) and protein kinase C (PKC)specific inhibitors ($G\ddot{o}6976$ and Ro31-8220) significantly reduced M. tbc-induced activation of ERK 1/2 and chemokine synthesis. Conclusion: These results are the first to demonstrate that the PLC-PKC-MEK-ERK, not the Ras-Raf-MEK-ERK, pathway is the major signaling pathway inducing M. tbc-mediated CCL3 and CCL4 expression in human primary monocytes.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.647-652
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• 2021

In this study, Saussurea Lappa roots were extracted using ethanol and n-hexane, and also the effects on proliferation of human hair dermal papilla cells and fibroblast and related signaling pathway were evaluated. 3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide (MTT) assay was conducted for cell proliferation effect of Saussurea Lappa root extract, and extracellular signal-related kinase (ERK), serine/threonine protein kinase (Akt), wingless-related integration site (Wnt)/𝛽-catenin signaling pathway, and 5𝛼-reductase expression through western blot analysis were measured. Saussurea Lappa root extract significantly increased human hair dermal papilla cells and propagation of fibroblast, promoted phosphorylation of ERK and Akt that get involved in cell proliferation. Additionally, Saussurea Lappa root extract significantly decreased promotion of Akt phosphorylation and cell proliferation by MEK/ERK inhibitor PD98059 and PI3K/Akt inhibitor LY294002. Also, Saussurea Lappa root extract induced intranuclear 𝛽-catenin accumulation by promoting phosphorylation of 𝛽-catenin (Ser552, 675) through phosphorylation of GSK-3𝛽 (Ser9), and suppressed activation of 5𝛼-reductase type I and II. Overall, Saussurea Lappa root induces cell proliferation through vitalization of ERK and Akt route of human hair dermal papilla cells and fibroblast and apoptosis defense mechanism, and can be helpful in hair loss prevention and hair growth by vitalizing the 𝛽-catenin signaling pathway and inhibiting activation of 5𝛼-reductase, which can be used as a potential hair care products.

• Archives of Pharmacal Research
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• v.23 no.6
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• pp.605-612
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• 2000

Green tea polyphenols (GTP) have been demonstrated to suppress tumorigenesis in several chemical-induced animal carcinogenesis models, and predicted as promising chemopreventive agents in human. Recent studies of GTP extracts showed the involvement of mitogen-activated protein kinases (MAPKs) in the regulation of Phase II enzymes gene expression and induction of apoptosis. In the current work we compared the biological actions of five green tea catechins: (1) induction of ARE reporter gene, (2) activation of MAP kinases, (3) cytotoxicity in human hepatoma HepG2-C8 cells, and (4) caspase activation in human cervical squamous carcinoma HeLa cells. For the induction of phase IIgene assay, (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate (ECG) potently induced antioxidant response element (ARE)-mediated luciferase activity, with induction observed at 25 $\mu\textrm{m}$with EGCG. The induction of ARE reporter gene appears to be structurally related to the 3-gallate group. Comparing the activation of MAPK by the five polyphenols, only EGCG showed potent activation of all three MAPKs (ERK, JNK and p38) in a dose- and time-dependent manner, whereas EGC activated ERK and p38. In the concentration range of 25 $\mu\textrm{m}$ to 1 mM, EGCG and ECG strongly suppressed HepG2-ARE-C8 cell-growth. To elucidate the mechanisms of green tea polyphenol-induced apoptosis, we measured the activation of an important cell death protein, caspase-3 induced by EGCG, and found that caspase-3 was activated in a dose- and time-dependent manner. Interestingly, the activation of caspase-3 was a relatively late event (peaked at 16 h), whereas activation of MAPKs was much earlier (peaked at 2 h). It is possible, that at low concentrations of EGCG, activation of MAPK leads to ARE-mediated gene expression including phase II detoxifying enzymes. Whereas at higher concentrations of EGCG, sustained activation of MAPKs such as JNK leads to apoptosis. These mechanisms are currently under investigation in our laboratory. As the most abundant catechin in GTP extract, we found that EGCG potently induced ARE-mediated gene expression, activated MAP kinase pathway, stimulated caspase-3 activity, and induced apoptosis. These mechanisms together with others, may contribute to the overall chemopreventive function of EGCG itself as well as the GTP.

• Natural Product Sciences
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• v.21 no.3
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• pp.205-209
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• 2015

Fucoidan, a sulfated polysaccharide is found in several types of edible brown algae. It has shown numerous biological activities; however, the molecular mechanisms on the activity against atopic dermatitis have not been reported yet. We now examined the effects of fucoidan on chemokine production co-induced by TNF-α/IFN-γ, and the possible mechanisms underlying these biological effects. Our data showed that fucoidan inhibited the TNF-α/IFN-γ-induced production of thymus and activation-regulated chemokine (TARC) and macrophagederived chemokine (MDC) mRNA in human keratinocytes HaCaT cells. Also, fucoidan suppressed phosphorylation of nuclear factor kappa B (NF-κB) and activation of signal transducer and activator of transcription (STAT)1 in a dose-dependent manner. In addition, fucoidan significantly inhibited activation of extracellular-signal-regulated kinases (ERK) phosphorylation. These data indicate that fucoidan shows anti-inflammatory effects by suppressing the expression of TNF-α/IFN-γ-induced chemokines by blocking NF-κB, STAT1, and ERK1/2 activation, suggestive of as used as a therapeutic application in inflammatory skin diseases, such as atopic dermatitis.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.2
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• pp.501-507
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• 2005

Shikonin is a chemically characterized component of traditional herbal medicine, the root of Lithospermum erythrorhizon and has been shown to possess antitumor activities. Here we investigated anticancer potential of shikonin and its possible mechanism of action in LLC cells. Shikonin inhibited the proliferation of LLC cells in a concentration-dependent manner. It was also demonstrated that shikonin induced apoptosis in LLC cells by Annexin V staining and TUNEL staining analysis. Shikonin treatment was caused that decrease of Bcl-2, activation of caspases and cleavage of PARP. And shikonin also induced that the activation of mitogen-activated protein kinases (MAPKs), such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38. Interestingly, the cell proliferation inhibition induced by shikonin was recovered by specific inhibitors of JNK and p38 but the inhibitor of MEK, the upstream kinase of ERK, did not recover. Additionally, shikonin administration at doses of 5 mg/kg in C57BL/6 mice strongly inhibited the primary tumor growth of LLC. Taken together, these results suggest that shikonin may suppress LLC cell proliferation by inducing an apoptotic process via activation of caspases and MAPKs

• IMMUNE NETWORK
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• v.11 no.6
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• pp.420-423
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• 2011

Since CKD-712 has been developed as an anti-inflammatory agent, we examined the effect of CKD-712 during TLR4 signaling. Using HEK293 cells expressing TLR4, CKD-712 was pre-treated 1 hr before LPS stimulation. Activation of NF-${\kappa}B$ was assessed by promoter assay. The activation of ERK, JNK, p38, IRF3 and Akt was measured by western blotting. CKD-712 inhibited the NF-${\kappa}B$ signaling triggered by LPS. The activation of ERK, JNK, p38 or IRF3 was not inhibited by CKD-712. On the contrary the activation of these molecules was augmented slightly. The activation of Akt with stimulation of LPS was also enhanced with CKD-712 pre-treatment at lower concentration, but was inhibited at higher concentration. We suggest that during TLR4 signaling CKD-712 inhibits NF-${\kappa}B$ activation. However, CKD-712 augmented the activation of Akt as well as Map kinases. Therefore, we suggest that CKD-712 might have a role as an immunomodulator.

• Journal of Life Science
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• v.26 no.10
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• pp.1182-1188
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• 2016

Membrane-associated guanylate kinase inverted-3 (MAGI-3) is a member of the family of membrane-associated guanylate kinases (MAGUKs). MAGI-3 modulates the kinase activity of protein kinase B (PKB)/AKT through interactions with phosphatase and tensin homolog (PTEN)/MMAC. Coxsackievirus B3 (CVB3) is a common causative agent of acute myocarditis and chronic dilated cardiomyopathy. Activation of AKT and extracellular signal-regulated kinases 1/2 (ERK1/2) is essential for CVB3 replication, but the relation between MAGI-3 signaling and CVB3 replication is not well understood. This study investigated the role of MAGI-3 in CVB3 infection and replication. MAGI-3 was overexpressed in HeLa cells by polyethylenimine (PEI) transfection. To optimize the transfection conditions, different ratios of plasmid DNA to PEI concentrations were used. MAGI-3 and empty plasmid DNA were transfected into the HeLa cells. MAGI-3 overexpression alone was not sufficient to efficiently activate AKT. However, expression of the CVB3 capsid protein VP1 dramatically increased in the HeLa cells overexpressing MAGI-3 24 h after CVB3 infection. In addition, the activities of AKT and ERK were significantly induced in the CVB3-infected MAGI-3 cells overexpressing HeLa. These results demonstrate that MAGI-3 expression upregulates CVB3 replication through AKT and ERK signaling activation. MAGI-3 may be an important target to control CVB3 replication.

• International Journal of Oral Biology
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• v.31 no.1
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• pp.21-26
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• 2006

Periodontopathogens including Porphyromonas gingivalis interact with host periodontal cells and the excessive subsequent host responses contribute a major part to the development of periodontal diseases. Cyclooxygenase(COX)-2-synthesized $PGE_2$ has detrimental activities in terms of periodontal pathogenesis. The present study investigated induction of COX-2 expression by P. gingivalis in human monocytic THP-1 cells. Live P. gingivalis increased expression of COX-2, but not that of COX-1, which was demonstrated at both mRNA and protein levels. Elevated levels of $PGE_2$ were released from P. gingivalis-infected THP-1 cells. Pharma-cological inhibition of p38 mitogen-activated protein kinase(MAPK) and extracellular signal-regulated kinase(ERK) substantially attenuated P. gingivalis-induced COX-2 mRNA expression. Indeed, activation of p38 MAPK and ERK was observed in P. gingivalis-infected THP-1 cells. Also, P. gingivalis induced activation of nuclear $factor-{\kappa}B\;(NF-{\kappa}B)$ which is an important transcription factor for COX-2. These results suggest that COX-2 expression is up regulated in P. gingivalis-infected monocytic cells, at least in part, via p38 MAPK, ERK, and $NF-{\kappa}B$.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.5
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• pp.1297-1302
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• 2007

Uncaria sinensis(OIi.) Havil (USH) is used in traditional Korean medicine to treat inflammation such as amebic dysentery. In this study, we investigated the anti-inflammatory effect of USH. The water extract of USH significantly inhibits lipopolysaccharide (LPS)-induced nitrite oxide (NO), tumor necrosis factor $(TNF)-{\alpha}$, interleukin (IL)-6and IL-12 productions in murine peritoneal macrophages. Furthermore, USH selectively inhibited activation of the extracellular signal-regulated kinase (ERK) but not of p38 MAPK, c-Jun N-terminal kinase (JNK) and nuclear $factor-{\kappa}B$ $(NF-{\kappa}B)$. In murine model, we found that administration of USH reduced serum levels of $TNF-{\alpha}$, IL-6 and IL-12 productions in LPS-treated mice. Our results suggest that USH exerts ant-inflammatory effects in macrophages via inhibition of ERK activation and may be a useful therapeutic approach to inflammatory diseases.