• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2494-2504
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• 2014

P38 mitogen activated protein (MAP) kinase is an important anti-inflammatory drug target, which can be activated by responding to various stimuli such as stress and immune response. Based on the conformation of the conserved DFG loop (in or out), binding inhibitors are termed as type-I and II. Type-I inhibitors are ATP competitive, whereas type-II inhibitors bind in DFG-out conformation of allosteric pocket. It remains unclear that how these allosteric inhibitors stabilize the DFG-out conformation and interact. Organosilicon compounds provide unusual opportunity to enhance potency and diversity of drug molecules due to their low toxicity. However, very few examples have been reported to utilize this property. In this regard, we performed docking of an inhibitor (BIRB) and its silicon analog (Si-BIRB) in an allosteric binding pocket of p38. Further, molecular dynamics (MD) simulations were performed to study the dynamic behavior of the simulated complexes. The difference in the biological activity and mechanism of action of the simulated inhibitors could be explained based on the molecular mechanics/generalized Born surface area (MM/GBSA) binding free energy per residue decomposition. MM/GBSA showed that biological activities were related with calculated binding free energy of inhibitors. Analyses of the per-residue decomposed energy indicated that van der Waals and non-polar interactions were predominant in the ligand-protein interactions. Further, crucial residues identified for hydrogen bond, salt bridge and hydrophobic interactions were Tyr35, Lys53, Glu71, Leu74, Leu75, Ile84, Met109, Leu167, Asp168 and Phe169. Our results indicate that stronger hydrophobic interaction of Si-BIRB with the binding site residues could be responsible for its greater binding affinity compared with BIRB.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.197.2-198
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• 2003

Activation of the apoptosis program by an increased production of beta-amyloid peptides (A${\beta}$) has been implicated in the neuronal cell death of Alzheimer's disease. Bcl-2 is a well demonstrated anti-apoptotic protein, however, the mechanism of anti-apoptotic action of Bcl-2 in A${\beta}$-induced apoptosis of neuronal cells is not fully understood. (omitted)

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.279-279
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• 2005

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.130.3-131
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• 2003

Inflammation is a frequent radiation-induced following therapeutic irradiation. Since the upregulation of adhesion molecules on endothelial cell surface has been known to be associated with inflammation, interfering with the expression of adhesion molecules is an important therapeutic target. We examined the effect if allicin, a major component of garlic, on the induction of intercellular adhesion molecule-l (ICAM-1) by gamma-irradiation and the mechanisms of its effect in gamma-irradiated human umbilical vein endothelial cells (HUVECs). (omitted)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.307.1-307.1
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• 2002

Inflammation is a frequent radiation-induced following therapeutic irradiation. Since the upregulation of adhesion molecules on endothelial cell surface has been known to be associated with inflammation. interfering with the expression of adhesion molecules is an important therapeutic target. We examined the effect of allicin. a major component of garlic. on the induction of intercellular adhesion molecule-1 (lCAM-1) by gamma-irradiation and the mechanisms of its effect in gamma-irradiated human umbilical vein endothelial cells (HUVECs). (omitted)

• Biomolecules & Therapeutics
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• v.24 no.4
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• pp.395-401
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• 2016

Endochondral bone formation is the process by which mesenchymal cells condense into chondrocytes, which are ultimately responsible for new bone formation. The processes of chondrogenic differentiation and hypertrophy are critical for bone formation and are therefore highly regulated. The present study was designed to investigate the effect of aloe-emodin on chondrogenic differentiation in clonal mouse chondrogenic ATDC5 cells. Aloe-emodin treatment stimulated the accumulation of cartilage nodules in a dose-dependent manner. ATDC5 cells were treated with aloe-emodin and stained with alcian blue. Compared with the control cells, the ATDC5 cells showed more intense alcian blue staining. This finding suggested that aloe-emodin induced the synthesis of matrix proteoglycans and increased the activity of alkaline phosphatase. Aloe-emodin also enhanced the expressions of chondrogenic marker genes such as collagen II, collagen X, BSP and RunX2 in a time-dependent manner. Furthermore, examination of the MAPK signaling pathway showed that aloe-emodin increased the activation of extracellular signal-regulated kinase (ERK), but had no effect on p38 and c-jun N-terminal kinase (JNK). Aloe-emodin also enhanced the protein expression of BMP-2 in a time-dependent manner. Thus, these results showed that aloe-emodin exhibited chodromodulating effects via the BMP-2 or ERK signaling pathway. Aloe-emodin may have potential future applications for the treatment of growth disorders.

• 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.

• Journal of Dental Anesthesia and Pain Medicine
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• v.18 no.6
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• pp.349-359
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• 2018

Background: Propofol is an intravenous anesthetic which has antioxidant effects due to its similarity in molecular structure to ${\alpha}$-tocopherol. It has been reported that ${\alpha}$-tocopherol increases osteoclast fusion and bone resorption. Here, we investigated the effects of propofol on signaling pathways of osteoclastogenic gene expression, as well as osteoclastogenesis and bone resorption using bone marrow-derived macrophages (BMMs). Methods: BMMs were cultured with macrophage colony-stimulating factor (M-CSF) alone or M-CSF plus receptor activator of nuclear factor kappa B ligand (RANKL) in the presence of propofol ($0-50{\mu}M$) for 4 days. Mature osteoclasts were stained for tartrate-resistant acid phosphatase (TRAP) and the numbers of TRAP-positive multinucleated osteoclasts were counted. To examine the resorption activities of osteoclasts, a bone resorption assay was performed. To identify the mechanism of action of propofol on the formation of multinucleated osteoclasts, we focused on dendritic cell-specific transmembrane protein (DC-STAMP), a protein essential for pre-osteoclastic cell fusion. Results: Propofol increased the formation of TRAP-positive multinucleated osteoclasts. In addition, the bone resorption assay revealed that propofol increased the bone resorption area on dentin discs. The mRNA expression of DC-STAMP was upregulated most strongly in the presence of both RANKL and propofol. However, SB203580, a p38 inhibitor, significantly suppressed the propofol/RANKL-induced increase in mRNA expression of DC-STAMP. Conclusion: We have demonstrated that propofol enhances osteoclast differentiation and maturation, and subsequently increases bone resorption. Additionally, we identified the regulatory pathway underlying osteoclast cell-cell fusion, which was enhanced by propofol through p38-mediated DC-STAMP expression.

• Molecules and Cells
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• v.28 no.3
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• pp.201-207
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• 2009

Silibinin is a polyphenolic flavonoid compound isolated from milk thistle (Silybum marianum), with known hepatoprotective, anticarcinogenic, and antioxidant effects. Herein, we show that silibinin inhibits receptor activator of $NF-{\kappa}B$ ligand (RANKL)-induced osteoclastogenesis from RAW264.7 cells as well as from bone marrow-derived monocyte/macrophage cells in a dose-dependent manner. Silibinin has no effect on the expression of RANKL or the soluble RANKL decoy receptor osteoprotegerin (OPG) in osteoblasts. However, we demonstrate that silibinin can block the activation of $NF-{\kappa}B$, c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein (MAP) kinase, and extracellular signal-regulated kinase (ERK) in osteoclast precursors in response to RANKL. Furthermore, silibinin attenuates the induction of nuclear factor of activated T cells (NFAT) c1 and osteoclast-associated receptor (OSCAR) expression during RANKL-induced osteoclastogenesis. We demonstrate that silibinin can inhibit $TNF-{\alpha}$-induced osteoclastogenesis as well as the expression of NFATc1 and OSCAR. Taken together, our results indicate that silibinin has the potential to inhibit osteoclast formation by attenuating the downstream signaling cascades associated with RANKL and $TNF-{\alpha}$.

• Journal of Life Science
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• v.16 no.4
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• pp.691-698
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• 2006

Phospholipase D (PLD) is known to play an important role in a variety of cells. However, little is known about $CoCl_2-mediated$ PLD signaling. In this study we demonstrated for the first time that $CoCl_2$ stimulates PLD activity and increases expression of cyclooxygenase-2 (COX-2), which is known to mediate inflammatory reaction. $CoCl_2-induced$ PLD activity was assessed by measuring the formation of $[^3H]$ phosphatidylbutanol (PtdBut), the product of PLD-mediated transphosphatidylation, in the presence of 1-butanol. To study mechanism of PLD signaling induced by $CoCl_2$, U87 human glioblastoma cells were stimulated by $CoCl_2$ and regulators of PLD activity induced by $CoCl_2$ were investigated using several inhibitors of signaling proteins. Moreover, PLD activation by $CoCl_2$ increased not only expression of COX-2 protein but also COX-2 promoter activity. In summary, these results suggest that $CoCl_2$ increases expression of COX-2 protein via PLD in human U87 glioblastoma cells.