• Journal of Ginseng Research
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• 제39권3호
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• pp.279-285
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• 2015

Background: Korean Red Ginseng has been used as a traditional oriental medicine to treat illness and to promote health for several thousand years in Eastern Asia. It is widely accepted that ginseng saponins, ginsenosides, are the major active ingredients responsible for Korean Red Ginseng's therapeutic activity against many kinds of illness. Although the crude saponin fraction (CSF) displayed antiplatelet activity, the molecular mechanism of its action remains to be elucidated. Methods: The platelet aggregation was induced by collagen, the ligand of integrin ${\alpha}_{II}{\beta}_I$ and glycoprotein VI. The crude saponin's effects on granule secretion [e.g., calcium ion mobilization and adenosine triphosphate (ATP) release] were determined. The activation of mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated protein kinase 1/2 (ERK1/2), c-Jun N-terminal kinases (JNKs), and p38 MAPK, and phosphoinositide 3-kinase (PI3K)/Akt was analyzed by immunoblotting. In addition, the activation of integrin ${\alpha}_{II}b{\beta}_{III}$ was examined by fluorocytometry. Results: CSF strongly inhibited collagen-induced platelet aggregation and ATP release in a concentration-dependent manner. It also markedly suppressed $[Ca^{2+}]_i$ mobilization in collagen-stimulated platelets. Immunoblotting assay revealed that CSF significantly suppressed ERK1/2, p38, JNK, PI3K, Akt, and mitogen-activated protein kinase kinase 1/2 phosphorylation. In addition, our fraction strongly inhibited the fibrinogen binding to integrin ${\alpha}_{IIb}{\beta}_3$. Conclusion: Our present data suggest that CSF may have a strong antiplatelet property and it can be considered as a candidate with therapeutic potential for the treatment of cardiovascular disorders involving abnormal platelet function.

• BMB Reports
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• 제29권6호
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• pp.489-492
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• 1996

A number of anticancer-chemotherapeutic agents induce cell death through the process of apoptosis. Effects of echinomycin, an anticancer agent on cancer progression, were investigated in P388 murine leukemia cells. First, according to the results of cytotoxicity measurement. $IC_{50}$ of echinomycin was 1.12 nM, a relatively lower value than the other examined anticancer agents, mitomycin-C and etoposide Second, the DNA fragmentation assay for echinomycin-treated cells exhibited that echinomycin was able to induce apoptosis in a shorter period of time and with a lower dose than mitomycin-C or etoposide. The data of DNA fragmentation were quite comparable to those of cytotoxicity measurement. Finally we showed that mitogen-activated protein (MAP) kinase, a key protein in cell mitosis, was translocated into the nucleus from the cytosol after treatment with echinomycin. These findings suggest that a MAP kinase-related process may be involved in apoptosis induced by echinomycin.

• Journal of Applied Biological Chemistry
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• 제64권4호
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• pp.323-331
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• 2021

Lincomycin is a lincosamide antibiotic isolated from the actinomycete Streptomyces lincolnensis. Moreover, it has been found to be effective against infections caused by Staphylococcus, Streptococcus, and Bacteroides fragillis. To identify the melanin-inducing properties of lincomycin, we used B16F10 melanoma cells in this study. The melanin content and intracellular tyrosinase activity in the cells were increased by lincomycin, without any cytotoxicity. Western blot analysis indicated that the protein expressions of tyrosinase, tyrosinase related protein 1 (TRP1) and TRP2 increased after lincomycin treatment. In addition, lincomycin enhanced the expression of master transcription regulator of melanogenesis, a microphthalmia-associated transcription factor (MITF). Lincomycin also increased the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and decreased the AKT phosphorylation. Moreover, the activation of tyrosinase activity by lincomycin was inhibited by the treatment with SB203580, which is p38 inhibitor. Furthermore, we also found that lincomycin-induced tyrosinase expression was reduced by H-89, a specific protein kinase A (PKA) inhibitor. These results indicate that lincomycin stimulate melanogenesis via MITF activation via p38 MAPK, AKT, and PKA signal pathways. Thus, lincomycin can potentially be used for treatment of hypopigmentation disorders.

• 대한의생명과학회지
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• 제12권3호
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• pp.249-254
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• 2006

It has been reported that liver is a very important organ to xenotransplantation. Pig is known to be a most suitable species in transplantation of human organs. However, the physiological function of pig hepatocytes is not clear elucidated. Epidermal growth factor (EGF) is known to be a mitogen in various cell systems. Thus, we examined the effect of EGF on cell proliferation and its related signal cascades in primary cultured pig hepatocytes. EGF stimulates cell proliferation in a dose (>1ng/ml) dependent manner. EGF-induced increase of $[^3H]-thymidine$ incorporation was blocked by AG 1478 ($10^{-6}M$, an EGF receptor antagonist) genistein and herbymycin A (tyrosine kinase inhibitors, $10^{-6}M$), suggesting the role of activation and tyrosine phosphorylation of EGF receptor. In addition, EGF-induced increase of $[^3H]-thymidine$ incorporation was prevented by neomycin $(10^{-4}M)$, U73122 $(10^{-5}M)$ (phospholipase C [PLC] inhibitors), staurosporine ($(10^{-8}M)$, or bisindolylmaleimide I $(10^{-6}M)$ (protein kinase C [PKC] inhibitors), suggesting the role of PLC and PKC. Moreover, EGF-induced increase of $[^3H]-thymidine$ incorporation was blocked by PD 98059 (a p44/42 mitogen activated protein kinase [MAPK] inhibitor), SB 203580 (a p38 MAPK inhibitor), and SP 600125 (a JNK inhibitor). EGF increased the translocation of PKC from cytosol to membrane fraction and activated p42/44 MAPK, p38 MAPK and JNK. In conclusion, EGF stimulates cell proliferation via PKC and MAPK in cultured pig hepatocytes.

• IMMUNE NETWORK
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• 제5권1호
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• pp.30-35
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• 2005

Background: p38 and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) signaling are thought to have critical role in lipopolysaccharide (LPS)-induced immune response but the molecular mechanism underlying the induction of these signaling are not clear. Methods: Specific inhibitors for p38, SB203580, and for ERK, PD98059 were used. Cells were stimulated by LPS with or without specific MAPK inhibitors. Results: LPS activated inducible nitric oxide synthase (iNOS), subsequent NO productions, and pro-inflammatory cytokine gene expressions (TNF-${\alpha}$, IL-$1{\beta}$, IL-6, and IL-12). Treatment of both SB203580 and PD98059 decreased LPS-induced NO productions. Concomitant decreases in the expression of iNOS mRNA and protein were detected. SB203580 and PD98059 decreased LPS-induced gene expression of IL-$1{\beta}$ and IL-6. SB203580 increased LPS-induced expression of TNF-${\alpha}$ and IL-12, and reactive oxygen species production, but PD98059 had no effect. Conclusion: These results indicate that both p38 and ERK pathways are involved in LPS-stimulated NO synthesis, and expression of IL-$1{\beta}$ and IL-6. p38 signaling pathways are involved in LPS-induced TNF-${\alpha}$ and IL-12, and reactive oxygen species plays an important role in these signaling in macrophage.

• 대한한의학회지
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• 제27권1호
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• pp.220-228
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• 2006

Objectives : Interleukin-1 (IL-1)${\beta}$ in articular chondrocytes regulates differentiation, apoptosis, and inflammatory responses. It is still controversial, So, we investigated IL- $1{\beta}$ induces chondrocytes dedifferentiation and death. Also, we studied the role of the mitogen-activated protein kinase (MAPK) subtypes on IL-$1{\beta}$-induced dedifferentiation and apoptosis. Methods : To evaluation of dedifferentiation by chemokines of chondrocytes, we assessed such as proteoglycan, collagen, MMP-3 and MMP-13 by RT-PCR analysis. Also, to assess of apoptosis effect by chemokines, we measured annexin V/propidium iodode (PI) and sub G1 cells in chondrocytes by flowcytometric analysis Results : IL-$1{\beta}$ treatment did not affect activation of ERK-1/2, but stimulation of p38 kinase. Inhibition of phospho ERK-1/2 with PD98059 enhanced IL-1b-induced dedifferentiation, and apoptosis up to 13.5%, whereas inhibition of phospho p38 kinase with SB203580 inhibited dedifferentiation, and apoptosis. Conclusions : Our results indicate that SB203580, p38 kinase inhibitor, inhibits IL-$1{\beta}$-induced dedifferentiation, and apoptosis by the inhibition of type II collagen expression and proteoglycan synthesis of rabbit articular chondrocytes.

• BMB Reports
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• 제32권4호
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• pp.379-384
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• 1999

Taxol, a natural product with significant anti-tumor activity, stabilizes microtubules and arrests cells in the G2/M phase of the cell cycle. It has been reported that taxol has additional effects on the cell such as an increase in tyrosine phosphorylation of proteins and activation of mitogen-activated protein (MAP) kinase. This phosphorylated kinase translocates into the nucleus and phosphorylates its substrate c-jun, c-fos, ATF2, and ATF3. The MAP kinase family is comprised of key regulatory proteins that control the cellular response to both proliferation and stress signals. First examination was cytotoxicity and apoptosis-induced concentration with paclitaxel in HeLa cell. A half-maximal inhibition of cell proliferation ($IC_{50}$) occurred at 13 nM paclitaxel. When DNA fragmentation was analyzed by agarose gel electrophoresis, a nucleosomal ladder became evident 24 h after a taxol (50 nM) addition to the cells. In addition, an apoptotic body was detected by electron microscopy. Taxol-treated cells were arrested at the S phase at 10 nM. Treatment of 50 nM taxol activated the extracellular signal-regulated protein kinase (ERK1), and a fraction of the activated MAP kinases entered the nucleus. It was also discovered that nucleus substrates c-jun was phosphorylated and activated in the cell. The activated ERK1 could subsequently translocate into the nucleus and phosphorylate its substrate c-jun as well. This study suggests that taxol-induced apoptosis might be related with signal transduction via MAP kinases.

• 한국미생물·생명공학회지
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• 제50권4호
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• pp.441-456
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• 2022

Shiga toxins (Stxs) are major virulence factors from the enterohemorrhagic Escherichia coli (EHEC), a subset of Stx-producing Escherichia coli. Stxs are multi-functional, ribosome-inactivating proteins that underpin the development of hemolytic uremic syndrome (HUS) and central nervous system (CNS) damage. Currently, therapeutic options for the treatment of diseases caused by Stxs are limited and unsatisfactory. Furthermore, the pathophysiological mechanisms underpinning toxin-induced inflammation remain unclear. Numerous works have demonstrated that the various host ribotoxic stress-induced targets including p38 mitogen-activated protein kinase, its downstream substrate Mitogen-activated protein kinase-activated protein kinase 2, and apoptotic signaling via ER-stress sensors are activated in many different susceptible cell types following the regular retrograde transportation of the Stxs, eventually leading to disturbing intercellular communication. Therapeutic options targeting host cellular pathways induced by Stxs may represent a promising strategy for intervention in Stx-mediated acute renal dysfunction, retinal damage, and CNS damage. This review aims at fostering an in-depth understanding of EHEC Stxs-mediated pathogenesis through the toxin-host interactions.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제33권3호
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• pp.211-220
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• 2007

Objective: In organotypic culture of immortalized human oral keratinocytes (IHOK), the change of the growth and differentiation was investigated according to the fibroblast type and the involvement of mitogen-activated protein (MAP) kinase. Materials & Methods: IHOK was cultured three dimensionally with gingival fibroblast (GF), dermal fibroblast (DF) and immortalized gingival fibroblast (IGF). We characterized biologic properties of three dimensionally reconstructed IHOK by histological, immunohistochemical, and Western blot analysis. We also investigated whether MAP kinase pathway was involved in epithelial-mesenchymal interaction by Western blot analysis. Results: The best condition of three dimensionally cultured IHOK was the dermal equivalent consisting of type I collagen and IGF. IGF increased the expression of more proliferating cell nuclear antigen (PCNA), involucrin than GF and DF in response to co-culture with IHOK. Extracellularly regulated kinase (ERK) pathway was activated in organotypic co-culture with IGF. Conclusion: The organotypic co-culture of IHOK with dermal equivalent consisting of type I collagen and IGF resulted in excellent morphologic and immunohistochemical characteristics and involved ERK pathway. The epithelial-mesenchymal interaction was activated according to the fibroblast type.

• BMB Reports
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• 제34권6호
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• pp.517-525
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• 2001

Six renaturable protein kinases that utilize the myelin basic protein (MBP) as a substrate were activated during prolonged exposure of cardiac myocytes to okadaic acid (OA). We characterized the substrate preference and activation of these kinases, with particular emphasis on 3 novel kinases-MBPK-55, MBPK-62 and MBPK-87. The transcription factors c-Jun, Elk, ATF2, and c-Fos that are used to assess mitogen-activated protein kinase activation were all poor substrates for these three kinases. MAPKAPK2 was also not phosphorylated. In contrast, Histone IIIS was phosphorylated by MBPK-55 and MBPK-62. These protein kinases were activated in cultured cardiac fibroblasts, H9c2 cardiac myoblasts, and Cos cells. High concentrations (0.5 to $1\;{\mu}M$) of OA were essential for the activation of the protein kinases in all of the cell types examined, whereas calyculin A [an inhibitor of protein phosphatase 1 (PP1) and PP2A], cyclosporin A (a PP2B inhibitor), and an inactive OA analog all failed to activate these kinases. The high dose of okadaic acid that is required for kinase activation was also required for phosphatase inhibition, as assessed by immunoblotting whole cell lysates with anti-phosphothreonine antibodies. A variety of chemical inhibitors, including PD98059 (MEK-specific), genistein (tyrosine kinase-specific) and Bisindolylmaleimide I (protein kinase C-specific), failed to inhibit the OA activation of these kinases. Thus, MBPK-55 and MBPK-62 are also Histone IIIS kinases that are widely expressed and specifically activated upon exposure to high OA concentrations.