• International Journal of Oral Biology
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• v.42 no.4
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• pp.149-153
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• 2017

Cyclooxygenase-2 (COX-2)-mediated prostaglandin $E_2$ ($PGE_2$) plays a key role in development and progression of inflammatory responses and Porphyromonas gingivalis is a common endodontic pathogen. In this study, we investigated induction of COX-2 and $PGE_2$ by P. gingivalis in human dental pulp cells (HDPCs). P. gingivalis increased expression of COX-2, but not that of COX-1. Increased levels of $PGE_2$ were released from P. gingivalis-infected HDPCs and this $PGE_2$ increase was blocked by celecoxib, a selective COX-2 inhibitor. P. gingivalis activated all three types of mitogen-activated protein kinases (MAPKs). P. gingivalis-induced activation of nuclear $factor-{\kappa}B$ ($NF-{\kappa}B$) was demonstrated by the results of phosphorylation of $NF-{\kappa}B$ p65 and degradation of inhibitor of ${\kappa}B-{\alpha}$ ($I{\kappa}B-{\alpha}$). Pharmacological inhibition of each of the three types of MAPKs and $NF-{\kappa}B$ substantially attenuated P. gingivalis-induced $PGE_2$ production. These results suggest that P. gingivalis should promote endodontic inflammation by stimulating dental pulp cells to produce $PGE_2$.

• Biomedical Science Letters
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• v.16 no.2
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• pp.71-74
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• 2010

Cell proliferation is governed by precise and orderly process the regulation of which involves many different proteins. The key enzyme for cell growth and arrest is cyclin dependent kinases (cdks). In human cells, several cdks orchestrate four distinct cell cycle phases (M, $G_1$, S and $G_2$ ) and they sequentially operate in an order of cdc1, cdk4, cdk6 and cdk2. The regulatory components of cdks consist of cyclins and two family of cdk inhibitors, INK4 (inhibitors of cdk4) and KIP (kinase inhibitor protein). $G_1$ regulatory molecules for cdk mainly respond to environmental cues of mitogenic and anti-mitogenic stimuli and therefore influence activities of $G_1$ cdks, namely, cdk4/6 and cdk2. $G_1$ inhibitors include $p21^{CIP}$ and $p27^{KIP1}$. Between them, $p27^{KIP1}$ has attracted attentions of many researchers because of its characteristic regulatory features and diverse functions. Besides, the role of $p27^{KIP1}$ in cancer development warrants further studies in the future. Therefore, this review will focus on the recent findings and especially on the complexity of regulatory mechanisms of $p27^{KIP1}$.

• BMB Reports
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• v.40 no.1
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• pp.1-6
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• 2007

Apoptosis signal-regulating kinase 1 (ASK1) is a mitogenactivated protein kinase (MAPK) kinase kinase that activates JNK and p38 kinases. ASK1 is activated by various stresses, such as reactive oxygen species (ROS), endoplasmic reticulum (ER) stress, lipopolysaccharide (LPS) and calcium influx which are thought to be responsible for the pathogenesis or exacerbations of various human diseases. Recent studies revealed the involvement of ASK1 in ROS- or ER stressrelated diseases, suggesting that ASK1 may be a potential therapeutic target of various human diseases. In this review, we focus on the current findings for the relationship between pathogenesis and ASK1-MAPK pathways.

• BMB Reports
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• v.41 no.7
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• pp.523-528
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• 2008

BMI-1026 is a synthetic aminopyrimidine compound that targets cyclin dependent kinases (cdks) and was initially designed as a potential anticancer drug. Even though it has been well documented that BMI-1026 is a potent cdk inhibitor, little is known about the cellular effects of this compound. In this study, we examined the effects of BMI-1026 treatment on inducing premature senescence and then evaluated the biochemical features of BMI-1026-induced premature senescence. From these experiments we determined that BMI-1026 treatment produced several biochemical features of premature senescence and also stimulated expression of mitogen activated protein kinase (MAPK) family proteins. BMI-1026 treatment caused nuclear translocation of activated Erk1/2 and the formation of senescence associated heterochromatin foci in 5 days. The heterochromatin foci formation was perturbed by inhibition of Erk1/2 activation.

• BMB Reports
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• v.50 no.7
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• pp.373-378
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• 2017

The Jun activation-domain binding protein 1 (Jab1) induces p53 nuclear export and cytoplasmic degradation, but the underlying mechanism is poorly understood. Here, we show that phosphorylation at the threonine 155 residue is essential for Jab1-mediated p53 nuclear export. Jab1 stimulated phosphorylation of p53 at T155 was inhibited by curcumin, an inhibitor of COP9 signalosome (CSN)-associated kinases. The T155E mutant, which mimics phosphorylated p53, exhibited spontaneous cytoplasmic localization in the absence of Jab1. This process was prevented by leptinomycin B (LMB), but not by curcumin. The substitution of threonine 155 for valine (T155V) abrogated Jab1-mediated p53 nuclear export, indicating that phosphorylation at this site is essential for Jab1-mediated regulation of p53. Although T155E can be localized in the cytoplasm in the absence of Mdm2, the translocation of T155E was significantly enhanced by ectopic Hdm2 expression. Our data suggests that Jab1-mediated phosphorylation of p53 at Thr155 residue mediates nuclear export of p53.

• YAKHAK HOEJI
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• v.57 no.6
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• pp.394-399
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• 2013

In this study we demonstrated whether the extract of Polygonum aviculare L. (PAE) can be applied to the immune-stimulating responses in macrophages (Raw 264.7 cells). Cell viability was determined by WST-8 assay, and all four doses of PAE (5, 10, 20, and 40 ${\mu}g/ml$) had no significant cytotoxicity during the entire experimental period. PAE increased the production of inducible nitric oxide synthase (iNOS) and nitric oxide (NO), and mRNA expressions and protein levels of pro-inflammatory cytokines(tumor necrotic factor (TNF)-${\alpha}$, interleukin (IL)-$1{\beta}$ and IL-6) in the same cells. These immune-stimulating activities of PAE were found to be caused by the stimulation of $NF{\kappa}B$ signal and phosphorylation of MAP kinases (p38, ERK and JNK).

• Environmental Mutagens and Carcinogens
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• v.26 no.4
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• pp.97-112
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• 2006

Heme oxygenase(HO)-1 is an important antioxidant enzyme that plays a pivotal role in cellular adaptation and protection in response to a wide array of noxious stimuli. Thus, HO-1 induction has been associated with prevention or mitigation of pathogenesis of various diseases, including acute inflammation, atherosclerosis, degenerative diseases, and carcinogenesis. Recent progress in our understanding of the function of molecules in the cellular signaling network as key modulators of gene transcription sheds light on the molecular mechanisms underlyuing HO-1 gene expression. A panel of redox-sensitive transcription factors such as activator protein-1, nuclear factor-kB, and nuclear factor E2-related factor-2, and some of the upstream kinases have been identified as prime regulators of HO-1 gene induction. This review summarizes molecular mechanisms underlying HO-1 expression and the significance of targeted induction of HO-1 as a potential chemopreventive or chemoprotective strategy.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.2
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• pp.123-129
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• 2009

Aprotinin is used clinically in cardiopulmonary bypass surgery to reduce transfusion requirements and the inflammatory response. The mechanism of action for the anti-inflammatory effects of aprotinin is still unclear. We examined our hypothesis whether inhibitory effects of aprotinin on cytokine-induced inducible nitric oxide synthase (iNOS) expression (IL-$l\beta$ plus TNF-$\alpha$), reactive oxygen species (ROS) generation, and vascular smooth muscle cell (VSMC) proliferation were due to HO-l induction in rat VSMCs. Aprotinin induced HO-l protein expression in a dose-dependent manner, which was potentiated during inflammatory condition. Aprotinin reduced cytokine mixture (CM)-induced iNOS expression in a dose dependent manner. Furthermore, aprotinin reduced CM-induced ROS generation, cell proliferation, and phosphorylation of JNK but not of P38 and ERK1/2 kinases. Aprotinin effects were reversed by pre-treatment with the HO-l inhibitor, tin protoporphyrin IX (SnPPIX). HO-l is therefore closely involved in inflammatory-stimulated VSMC proliferation through the regulation of ROS generation and JNK phosphorylation. Our results suggest a new molecular basis for aprotinin anti-inflammatory properties.

• 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

• Biomolecules & Therapeutics
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• v.20 no.3
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• pp.352-356
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• 2012

The present study was undertaken to determine whether ethanol influences on the agonist-induced vascular smooth muscle contraction and, if so, to investigate the related mechanism. The measurement of isometric contractions using a computerized data acquisition system was combined with molecular experiments. Ethanol significantly inhibited thromboxane $A_2$ mimetic-induced contraction with intact endothelial function, but there was no relaxation on thromboxane $A_2$ mimetic U-46619-induced contraction irrespective of endothelium suggesting that the pathway such as Rho-kinase activation, $Ca^{2+}$ entry or thin filament regulation was not affected. In addition, ethanol didn't decrease thromboxane $A_2$ mimetic-induced increase of phospho-myosin phosphatase targeting subunit protein 1 (pMYPT1) or pERK1/2. Interestingly, ethanol didn't inhibit significantly phorbol ester-induced contraction in denuded muscles suggesting that thin filament regulation is less important on the ethanol-induced regulation in the muscle than endothelial NO synthesis. In conclusion, this study provides the evidence and possible related mechanism concerning the effect of ethanol on the agonist-dependent contraction in rat aortic rings with regard to endothelial function.