• BMB Reports
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• v.48 no.5
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• pp.249-255
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• 2015

PTPRT/RPTPρ is the most recently isolated member of the type IIB receptor-type protein tyrosine phosphatase family and its expression is restricted to the nervous system. PTPRT plays a critical role in regulation of synaptic formation and neuronal development. When PTPRT was overexpressed in hippocampal neurons, synaptic formation and dendritic arborization were induced. On the other hand, knockdown of PTPRT decreased neuronal transmission and attenuated neuronal development. PTPRT strengthened neuronal synapses by forming homophilic trans dimers with each other and heterophilic cis complexes with neuronal adhesion molecules. Fyn tyrosine kinase regulated PTPRT activity through phosphorylation of tyrosine 912 within the membrane-proximal catalytic domain of PTPRT. Phosphorylation induced homophilic cis dimerization of PTPRT and resulted in the inhibition of phosphatase activity. BCR-Rac1 GAP and Syntaxin-binding protein were found as new endogenous substrates of PTPRT in rat brain. PTPRT induced polymerization of actin cytoskeleton that determined the morphologies of dendrites and spines by inhibiting BCR-Rac1 GAP activity. Additionally, PTPRT appeared to regulate neurotransmitter release through reinforcement of interactions between Syntaxin-binding protein and Syntaxin, a SNARE protein. In conclusion, PTPRT regulates synaptic function and neuronal development through interactions with neuronal adhesion molecules and the dephosphorylation of synaptic molecules. [BMB Reports 2015; 48(5): 249-255]

• Parasites, Hosts and Diseases
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• v.39 no.2
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• pp.151-160
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• 2001

Randomly selected 435 clones from Acanthamoeba healyi cDNA library were sequenced and a total of 387 expressed sequence tags (ESTs) had been generated. Based on the results of BLAST search, 130 clones (34.4%) were identified as the genes enconding surface Proteins , enzymes for DNA, energy Production or other metabolism, kinases and phosphatases, protease, proteins for signal transduction, structural and cytoskeletal proteins, cell cycle related proteins, transcription factors, transcription and translational machineries, and transporter proteins. Most of the genes (88.5%) are newly identified in the genus Acanthamoeba. Although 15 clones matched the genes of Acanthamoeba located in the public databases, twelve clones were actin gene which was the most frequently expressed gene in this study. These ESTs of Acanthamoeba would give valuable information to study the organism as a model system for biological investigations such as cytoskeleton or cell movement, signal transduction, transcriptional and translational regulations. These results would also provide clues to elucidate factors for pathogenesis in human granulomatous amoebic encephalitis or keratitis by Acanthamoeba.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.3
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• pp.211-217
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• 2000

Paxillin is a regulatory component of the complex of cytoskeletal proteins that link the actin cytoskeleton to the plasma membrane. However, the role of paxillin during smooth muscle contraction is unclear. We investigated a possible role for the membrane-associated dense plaque protein paxillin in the regulation of contraction in rat aortic vascular smooth muscle. The tyrosine phosphorylation of paxillin, which was increased by norepinephrine, reached a peak level after 1 min stimulation and then decreased with time. However, norepinephrine induced a sustained contraction that reached a steady state 30 min after application. Pretreatment with tyrphostin, an inhibitor of tyrosine kinase, inhibited the tyrosine phosphorylation of paxillin and also the contraction stimulated by norepinephrine. Both inhibitions were concentration-dependent, and the degree of correlation between them was high. These results show that, in rat aortic smooth muscle, tyrosine kinase(s) activated by norepinephrine may phosphorylate the tyrosine residues of paxillin, thereby providing a source of regulation during vascular smooth muscle contraction.

• Biomedical Science Letters
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• v.15 no.4
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• pp.343-347
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• 2009

Cytochalasin D (CD) is known as a disruptor of actin cytoskeleton architecture in chondrocytes. We have studied the role of CD in retinoic acid (RA) caused dedifferentiation and inflammation responses in rabbit articular chondrocytes. We have examined the effect of CD on RA induced dedifferentiation of chondrocytes. CD inhibited RA induced dedifferentiation determined by Western blot analysis and Alcian blue staining in rabbit articular chondrocytes. Also, CD additionally reduced inflammation response molecules such as cyclooxygenase-2 (COX-2) and prostaglandin $E_2$ ($PGE_2$) in RA treated cells. Treatment of CD reduced phosphorylation of p38 by treatment of RA. Inhibiton of p38kinase with SB203580 reduced expression of COX-2 and production of $PGE_2$ by treatment of CD in RA treated cells. But, Inhibiton of p38kinase with SB203580 did not any relationship with effect of CD on RA caused dedifferentiation. In summary, our results indicate that CD regulates RA reduced expression of COX-2 and production of PGE2 via p38kinase pathway.

• Journal of Surface Science and Engineering
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• v.41 no.6
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• pp.264-268
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• 2008

Interaction between human osteoblast and TiN films was conducted in vitro. TiN films were produced by cathodic arc plasma deposition. The surface was characterized by atomic force microscopy (AFM). TiN films, glass substrates and Ti films were cultured with human osteoblasts for 48 and 72 h hours. Actin stress fiber patterns and microtubules of osteoblasts were found slightly more organized and distributed on TiN films compared to those on the Ti films and the glass substrates. Human osteoblasts also showed slightly higher cell attachment, proliferation, and focal contact adhesion on TiN films compared to those on Ti films and glass substrates. Our results demonstrated that TiN films showed slightly better cellular adhesion of osteoblasts than Ti films and glass substrates in a short-time culture period.

• Applied Microscopy
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• v.21 no.1
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• pp.46-62
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• 1991

The intermediate filament is one of the most important constituents of the intracytoplasmic cytoskeleton microtubule, actin, myosin and intermediate filament. It is composed of keratin, desmin, vimentin, neurofilament and glial filament, and has important role as a cellular marker, epithelial or mesenchymal origin. So it will be important to differentiated from some poorly or undifferentiated neoplasm to provide adequate therapeutic modalities. This study was performed by using immunohistochemical staining and electron microscopic observation to find out intermediate filaments of epithelial and non-epithelial tumor cells evaluate the degree of differentiation in tumors and therefore to provide some diagnostic and therapeutic modalities. The materials consisted of 83 epithelial and non-epithelial elements bearing 23 normal control, 28 epithelial tumors, and 32 non-epithelial tumors, that are resected for definite treatment at Chosun University Hospital from June, 1988 to June, 1990. Immunohistochemical stain for keratin, desmin and vimentin, and electron microscopic study were performed in all cases. The results obtained were as follows. 1. Immunohistochemical stain for intermediate filament were very useful diagnostic aid for differentiated epithelial tumor to non-epithelial tumor in diagnostic neoplasia. 2. In the electron microscopic finding, the size of intermediate filaments were possible differentiated to cell components of epithelial tumor and non-epithelial tumors.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.1013-1017
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• 2008

Syndecan-3 is a cell-surface heparan sulfate proteoglycan, which performs a variety of functions during cell adhension process. It is also a coreceptor for growth factor, mediating cell-cell and cell-matrix interaction. Syndecan-3 contains a cytoplasmic domain potentially associated with the cytoskeleton. Syndecan-3 is specifically expressed in neuron cell and has related to neuron cell differentiation and development of actin filament in cell migration. Syndecans each have a unique, central, and variable (V) region in their cytoplasmic domains. And that region of syndecan-3 may modulate the interactions of the conserved C1 regions of the cytoplasmic domains by tyrosine phosphorylation. Cytoplasmic domain of syndecan-3 has been synthesized for NMR structural studies. The solution structure of syndecan-3 cytoplasmic domain has been determined by two-dimensional NMR spectroscopy and simulated-annealing calculation. The cytoplasmic domain of the syndecan proteins has a tendency to form a dimmer conformation with a central cavity, however, that of syndecan-3 demonstrated a monomer conformation with a flexible region near C-terminus. The structural information might add knowledge about the structure-function relationships among syndecan proteins.

• Molecules and Cells
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• v.20 no.2
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• pp.196-200
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• 2005

The neurofibromatosis type2 (NF2) tumor suppressor gene product, merlin, is structurally related to the ezrin-radixin-moesin (ERM) family of proteins that anchor the actin cytoskeleton to specific membrane proteins and participate in cell signaling. However, the basis of the tumor suppressing activity of merlin is not well understood. Previously, we identified a role of merlin as an inhibitor of the Ras-ERK signaling pathway. Recent studies have suggested that phosphorylation of merlin, as of other ERM proteins, may regulate its function. To determine whether phosphorylation of merlin affects its suppression of Ras-ERK signaling, we generated plasmids expressing full-length merlin with substitutions of serine 518, a potential phosphorylation site. A substitution that mimics constitutive phosphorylation (S518D) abrogated the ability of merlin to suppress effects of the Ras-ERK signaling pathway such as Ras-induced SRE transactivation, Elk-mediated SRE transactivation, Ras-induced ERK phosphorylation and Ras-induced focus formation. On the other hand, an S518A mutant, which mimics nonphosphorylated merlin, acted like wild type merlin. These observations show that mimicking merlin phosphorylation impairs not only growth suppression by merlin but also its inhibitory action on the Ras-ERK signaling pathway.

• Journal of Ginseng Research
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• v.41 no.4
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• pp.566-571
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• 2017

Background: A number of reports have described the protective effects of ginsenoside Rg1 (Rg1) in Alzheimer's disease (AD). However, the protective mechanisms of Rg1 in AD remain elusive. Methods: To investigate the potential mechanisms of Rg1 in ${\beta}$-amyloid peptide-treated SH-SY5Y cells, a comparative proteomic analysis was performed using stable isotope labeling with amino acids in cell culture combined with nano-LC-MS/MS. Results: We identified a total of 1,149 proteins in three independent experiments. Forty-nine proteins were significantly altered by Rg1 after exposure of the cells to ${\beta}$-amyloid peptides. The protein interaction network analysis showed that these altered proteins were clustered in ribosomal proteins, mitochondria, the actin cytoskeleton, and splicing proteins. Among these proteins, mitochondrial proteins containing HSD17B10, AARS2, TOMM40, VDAC1, COX5A, and NDUFA4 were associated with mitochondrial dysfunction in the pathogenesis of AD. Conclusion: Our results suggest that mitochondrial proteins may be related to the protective mechanisms of Rg1 in AD.

• The Korean Journal of Cytopathology
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• v.6 no.2
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• pp.106-115
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• 1995

Reactive humsn mesothelial cells were examined by immunocytochemical stain with intermediate filaments (cytokeratin [CK1, CK7, CK8, CK18, CD19), vimentin, desmin, actin), epithelial membrane antigen, carcinoembryonic antigen (CEA), MHC class II antigen (HLA-DR), LeuM-1 (CD15), $\alpha1-antitrypsin$(ACT), $\alpha1-antichymotrypsin$ (ACHT), CD68(KP-1) and FcyRIII(CD16). The mesothelial cells were isolated from patients with liver cirrhosis and pleural effusion, and short-term cultured in RPMI 1640 media containing 10% heat inactivated fetal calf serum and 1% identical supernatant fluid of the patients' transudates. The results obtained are as follows 1. The cultured-reactive mesothelial cells were positive for the protein of cytoskeleton such as cytokeratin and vimentin, but negative for desmin and actin. The resting mesothelial cells showed positive reactions for cylokeratin, but negative for vimentin, desmin and actin. 2. The primary antibodies to the cytokeratin were strongly reactive for CK1, CK8 and CK18 but negative for CK7 and CK19 in both reactive and resting mesothelial cells. 3. Resting mesothelial cells showed negative reactions for CEA, but strong positive reactions in cultured-reactive mesothelial cells. 4. The markers for the monocytes/histiocytes(CD11b, CD14, CD16, CD68, Iysozyme and $\alpha1-antitrypsin$ and $\alpha1-antichymotrypsin$) were nonreactive in resting mesothelial cells, but lysozyme and $\alpha1-antitrypsin$ were weakly reactive in reactive and proliferative mesothelial cells. 5. MHC Class II molecule(HLA-DR antigen) was negative in both resting and reactive mesothelial cells. These results suggest that the short-term cultured, reactive mesothelial cells show a newly aberrant expression of the vimentin and calcine-embryonic antigen. The reason of the aberrant expression of the intermediate filament and oncofetal antigen in reactive and proliferative mesothelial cells should be further evaluated.