• Journal of Yeungnam Medical Science
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• v.30 no.1
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• pp.10-16
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• 2013

Background: Toll-like receptors (TLRs) are well-known pattern recognition receptors. Among the 13 TLRs, TLR2 is the most known receptor for immune response. It activates mitogen-activated protein kinases (MAPKs), which are counterbalanced by MAPK phosphatases [MKPs or dual-specificity phosphatases (DUSPs)]. However, the regulatory mechanism of DUSPs is still unclear. In this study, the effect of a TLR2 ligand (TLR2L, Pam3CSK4) on DUSP4 expression in Raw264.7 cells was demonstrated. Methods: A Raw264.7 mouse macrophage cell line was cultured in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum and 1% antibiotics (100 U/mL penicillin and 100 g/mL streptomycin) at $37^{\circ}C$ in 5% $CO_2$. TLR2L (Pam3CSK4)-mediated DUSP4 expressions were confirmed with RT-PCR and western blot analysis. In addition, the detection of reactive oxygen species (ROS) was measured with lucigenin assay. Results: Pam3CSK4 induced the expression of DUSP1, 2, 4, 5 and 16. The DUSP4 expression was also increased by TLR4 and 9 agonists (lipopolysaccharide and CpG ODN, respectively). Pam3CSK4 also induced ERK1/2 phosphorylation and ROS production, and the Pam3CSK4-induced DUSP4 expression was decreased by ERK1/2 (U0126) and ROS (DPI) inhibitors. U0126 suppressed the ROS production by Pam3CSK4. Conclusion: Pam3CSK4-mediated DUSP4 expression is regulated by ERK1/2 and ROS. This finding suggests the physiological importance of DUSP4 in TLR2-mediated immune response.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.3
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• pp.185-191
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• 2008

While indirect targeting strategies using reporter-genes are taking center stage in current molecular imaging research, another vital strategy has long involved direct imaging of specific receptors using radiolabeled ligands. Recently, there is renewal of immense interest in this area with particular attention to the epidermal growth factor receptor (EGFR), a transmembrane glycoprotein critically involved in the regulation of many cellular functions and malignancies. Recently, two novel classes of EGFR-targeting anticancer drugs have entered clinical trials with great expectations. These are monoclonal antibodies such as cetuximab that target the extracellular domain, and small molecule tyrosine kinase inhibitors such as gefitinib (lressa) and erlotinib (Tarceva) that target the catalytic domain of the receptor. However, early results have showed disappointing survival benefits, disclosing a major challenge for this therapeutic strategy; namely, the need to identify tumors that are most likely to respond to the agents. To address this important clinical issue, several noninvasive imaging techniques are under investigation including radiolabeled probes based on small molecule tyrosine kinase inhibitors, anti-EGFR antibodies, and EGF peptides. This review describes the current status, limitations, and future prospects in the development of radiotracer methods for EGFR imaging.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.1
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• pp.31-36
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• 2011

To understand the roles of purinergic receptors and cellular molecules below the receptors in the vascular inflammatory response, we determined if extracellular nucleotides up-regulated chemokine expression in vascular smooth muscle cells (VSMCs). Human aortic smooth muscle cells (AoSMCs) abundantly express $PSY_1$, $PSY_6$, and $PSY_{11}$ receptors, which all respond to extracellular nucleotides. Exposure of human AoSMCs to $NAD^+$, an agonist of the human $PSY_{11}$ receptor, and $NADP^+$ as well as ATP, an agonist for $PSY_1$ and $PSY_{11}$ receptors, caused increase in chemokine (C-C motif) ligand 2 gene (CCL2) transcript and CCL2 release; however, UPT did not affect CCL2 expression. CCL2 release by $NAD^+$ and $NADP^+$ was inhibited by a concentration dependent manner by suramin, an antagonist of P2-purinergic receptors. $NAD^+$ and $NADP^+$ activated protein kinase C and enhanced phosphorylation of mitogen-activated protein kinases and Akt. $NAD^+$- and $NADP^+$-mediated CCL2 release was significantly attenuated by SP6001250, U0126, LY294002, Akt inhibitor IV, RO318220, GF109203X, and diphenyleneiodium chloride. These results indicate that extracellular nucleotides can promote the proinflammatory VSMC phenotype by up-regulating CCL2 expression, and that multiple cellular elements, including phosphatidylinositol 3-kinase, Akt, protein kinase C, and mitogen-activated protein kinases, are involved in that process.

• Journal of Life Science
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• v.17 no.6 s.86
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• pp.783-790
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• 2007

G protein coupled receptors (GPCRs) transmit various extracellular signals into the cells. Upon binding of the ligands, conformational changes in the extracellular and/or transmembrane (TM) domains of CPCRs were propagated into the cytoplasmic (CP) domain of the molecule leading to the activation of their cognate heterotrimeric C proteins and kinases. Constitutively active GPCR mutants causing the activation of C Protein signaling even in the absence of ligand binding are of interest for the study of activation mechanism of GPCRs. Two classes of constitutively active mutations, categorized by their effects on the salt bridge between Ell3 and K296, were found in the TM domain of rhodopsin. Opsin mutants containing combinations of the mutations were constructed to study the conformational changes required for the activation of rhodopsin. Rhodopsin chromophore regenerated with 11-cis-retinal showed a thermal stability inversely correlated with its constitutive activity. In contrast, rhodopsin mutants exhibited a binding affinity to an agonist, all-trans-retinal, in a constitutive activity-dependent manner. In order to test whether the conformational changes responsible for the activation of trans-ducin (Gt) are the same as the conformation required for the recognition of rhodopsin kinase, analysis of the mutants were carried out with phosphorylation by rhodopsin kinase. Rhodopsin mutants containing combinations of different classes of the mutations showed a strong synergistic effect on the phosphorylation of the mutants in the dark as similar to that of Gt activation. The results suggest that at least two or three kinds of segmental and independent conformational changes are required for the activation of rhodopsin and the conformational changes responsible for activating rhodopsin kinase and Gt are similar to each other.

• Journal of Ginseng Research
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• v.32 no.1
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• pp.1-7
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• 2008

Ginseng saponin has been shown to inhibit the development of dependence on morphine, cocaine, methamphetamine, but the antinarcotics effects of ginseng on nalbuphine remains still largely unknown. Ginseng administration attenuated the naloxone-induced jumping behavior on nalbuphine dependent mice. The development of morphine dependence was mediated through ${\mu}-opioid$ receptor, however, development of nalbuphine dependence was mediated through ${\kappa}-opioid$ receptor. However, it was found that the efficacy of analgesic antagonism of GTS was mediated through the serotonergic mechanism, not mediated through the opioid receptor. In addition, ginseng administration modulated cellular signal transduction in the brain. The increased NMDA receptor subunit (NR1, pNR1), phosphate extracellular signal regulated protein kinase (pERK), phosphate cAMP response element binding protein (pCREB) expression by nalbuphine was decreased by the administration of ginseng powder in cortex, hippocampus, striatum of rat brain. These results suggest that ginseng could be one of the targets of antinarcotic therapies to reduce the development of tolerance and dependence on nalbuphine as well as morphine.

• International Journal of Industrial Entomology and Biomaterials
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• v.48 no.1
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• pp.13-18
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• 2024

The rice field grasshopper, Oxya chinensis sinuosa (OC), has traditionally been utilized in Korea for various purposes; however, its potential benefits in the context of osteoporosis remain unclear. The results revealed that OC ethanol extract (OCE) significantly inhibited the formation and activity of tartrate-resistant acid phosphatase (TRAP)-positive cells in receptor activator of nuclear factor-κB ligand (RANKL)-stimulated RAW264.7 cells. Furthermore, OCE, at concentrations ranging from 100 to 400 ㎍/mL, demonstrated a dose-dependent reduction in the protein expression of osteoclast-specific markers, including nuclear factor of activated T cell cytoplasmic 1, c-Src, and TRAP, when compared to RANKL stimulation alone. Additionally, OCE significantly inhibited RANKL-induced activation of p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) but not the activation of extracellular signal-regulated kinase. Collectively, these results indicate that OCE suppresses osteoclastogenesis by attenuating the phosphorylation of p38 MAPK and JNK. Consequently, these findings suggest that OCE holds promise for the prevention of osteoporosis.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.6
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• pp.359-364
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• 2010

Many therapeutic roles have been proposed for sigma-1 receptor (Sig-1R), but the involvement of Sig-1R in neuropathic pain has currently not been well explored. The present study aimed to evaluate the anti-nociceptive effect of Sig-1R antagonist (BD1047) in a rat model of chronic compression of the dorsal root ganglion (CCD), which is a model of human foraminal stenosis and radicular pain. When stainless steel rods were inserted into the intervertebral foramen of lumbar vertebrae 4 and 5, the CCD developed reliable mechanical (from 3 day) and cold allodynia (from 1 day) as compared with the sham operation group. The spinal expressions of Sig-1R and phosphorylation of extracellular signal-regulated kinase (pERK) were significantly increased from day 3 to day 14 after CCD surgery, as is consistent with the manifestation of allodynia. The BD 1047 (10, 30, 100 mg/kg) administered on postoperative days 0~5 dose-dependently suppressed both the induction of allodynia and the elevation of the spinal pERK expression in a manner comparable with that of gabapentin (100 mg/kg). At 7 days post-CCD surgery, BD1047 (10, 30, 100 mg/kg) administration also produced anti-nociceptive effects on the mechanical and cold allodynia similar with those of gabapentin (100 mg/kg). Therefore, this data suggested that Sig-1R may play an important role in both the development and maintenance of CCD-induced neuropathy.

• IMMUNE NETWORK
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• v.5 no.4
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• pp.193-198
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• 2005

Background: Protease-activated receptor 2 (PAR2) belongs to a family of G protein coupled receptors activated by proteolytic cleavage. Trypsin-like serine proteases interact with PAR2 expressed by a variety of tissues and immune cells. The aim of our study was to investigate whether PAR2 stimulation can lead to the activation of human mac rophages. Methods: PAR2-mediated proliferation of human macrophage cell line THP-1 was measured with MTT assay. We also examined the extracellular regulated kinase (ERK) phosphorylation and cytokine production induced by trypsin and PAR2-agonist using western blot and enzyme-linked immunosorbent assay (ELISA), respectively. Results: Treatment of trypsin or PAR2-activating peptide increased cell proliferation in a dose-dependent manner, and induced the activation of ERK1/2 in THP-1 cells. In addition, trypsin-induced cell proliferation was inhibited by pretreatment of an ERK inhibitor (pD98059) or trypsin inhibitor (SBTI). Moreover, PAR2 activation by trypsin increased the secretion of TNF-${\alpha}$ in THP-1 cells. Conclusion: There results suggest that P AR2 activation by trypsin-like serine proteases can induce cell proliferation through the activation of ERK in human macrophage and that PAR2 may playa crucial role in the cell proliferation and cytokine secretion induced by trypsin-like serine proteases.

• Genomics & Informatics
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• v.21 no.3
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• pp.30.1-30.13
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• 2023

Ephs belong to the largest family of receptor tyrosine kinase and are highly conserved both sequentially and structurally. The structural organization of Eph is similar to other receptor tyrosine kinases; constituting the extracellular ligand binding domain, a fibronectin domain followed by intracellular juxtamembrane kinase, and SAM domain. Eph binds to respective ephrin ligand, through the ligand binding domain and forms a tetrameric complex to activate the kinase domain. Eph-ephrin regulates many downstream pathways that lead to physiological events such as cell migration, proliferation, and growth. Therefore, considering the importance of Eph-ephrin class of protein in tumorigenesis, 7,620 clinically reported missense mutations belonging to the class of variables of unknown significance were retrieved from cBioPortal and evaluated for pathogenicity. Thirty-two mutations predicted to be pathogenic using SIFT, Polyphen-2, PROVEAN, SNPs&GO, PMut, iSTABLE, and PremPS in-silico tools were found located either in critical functional regions or encompassing interactions at the binding interface of Eph-ephrin. However, seven were reported in nonsmall cell lung cancer (NSCLC). Considering the relevance of receptor tyrosine kinases and Eph in NSCLC, these seven mutations were assessed for change in the folding pattern using molecular dynamic simulation. Structural alterations, stability, flexibility, compactness, and solvent-exposed area was observed in EphA3 Trp790Cys, EphA7 Leu749Phe, EphB1 Gly685Cys, EphB4 Val748Ala, and Ephrin A2 Trp112Cys. Hence, it can be concluded that the evaluated mutations have potential to alter the folding pattern and thus can be further validated by in-vitro, structural and in-vivo studies for clinical management.

• BMB Reports
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• v.47 no.5
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• pp.280-285
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• 2014

Cancer cells undergo uncontrolled proliferation, and aberrant mitochondrial alterations. Tumor necrosis factor receptor-associated protein 1 (TRAP1) is a mitochondrial heat shock protein. TRAP1 mRNA is highly expressed in some cancer cell lines and tumor tissues. However, the effects of its overexpression on mitochondria are unclear. In this study, we assessed mitochondrial changes accompanying TRAP1 overexpression, in a mouse cell line, NIH/3T3. We found that overexpression of TRAP1 leads to a series of mitochondrial aberrations, including increase in basal ROS levels, and decrease in mitochondrial biogenesis, together with a decrease in peroxisome proliferator-activated receptor gamma coactivator-$1{\alpha}$ (PGC-$1{\alpha}$) mRNA levels. We also observed increased extracellular signal-regulated kinase (ERK) phosphorylation, and enhanced proliferation of TRAP1 overexpressing cells. This study suggests that overexpression of TRAP1 might be a critical link between mitochondrial disturbances and carcinogenesis.