• YAKHAK HOEJI
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• v.41 no.1
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• pp.81-85
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• 1997

Ceramide has been suggested as an important mediator of the effects of extracellular agonists on cell growth inhibition, differentiation, apoptosis. However the biochemical sign aling mechanism involved in transducing the effects of ceramide on leukemia cell differentiation is still unclear. In these respects, we examined the regulatory effects of ceramide on c-jun gene expression during differentiation. In U-937 cells. ceramide increased c-jun mRNA levels in a time-dependent manner. The half life, of c-jun mRNA was 30 min. In contrast, inhibition of protein synthesis with cycloheximide in the absence, of transcription with actinomycin D increased the half-life of c-jun mRNA in ceramide-treated U-937 cells to more than 90 min. In order to examine whether ceramide-inhibited c-jun gene expression is regulated through ceramide-activated protein phosphatase (CAPP), a direct target for the action of ceramide, okadaic acid were treated to the cells. Okadaic acid inhibited enhancement of c-jun mRNA induced by C2-ceramide in a dose-dependent manner. These results suggested that ceramide increases c-jun mRNA level during differentiation in U-937 cells and regulates the gene expression on posttranscriptional level. In addition, we provide the evidence that CAPP is involved in ceramide-induced c-jun gene expression in U-937 cells.

• Journal of Digestive Cancer Research
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• v.6 no.1
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• pp.6-10
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• 2018

The importance of signal transducer and activator of transcription 3 (STAT3) signaling in gastric carcinogenesis was firmly evaluated in the previous studies. Fully activated STAT3 induces various target genes involving tumor invasion and epithelial-mesenchymal transition (EMT), and mediates interaction between cancer cells and microenvironmental immune cells. Thus, suppression of STAT3 activity is an important issue for inhibition of gastric carcinogenesis and invasion. Unfortunately, data from clinical studies of direct inhibitor targeting STAT3 have been disappointing. SH2-containing protein tyrosine phosphatase 1 (SHP-1) effectively dephosphorylates and inhibits STAT3 activity, which has not been extensively studied gastric cancer research field. However, by summarizing recent data, it is evident that protein and gene expression of SHP-1 are minimal in gastric cancer cells, and induction of SHP-1 effectively downregulates phosphorylated STAT3 and inhibits cellular invasion in gastric cancer cells. Several SHP-1 inducers have been investigated in the experimental studies, including proton pump inhibitor, arsenic trioxide, and other natural compounds. Taken together, we suggest that modulation of SHP-1/STAT3 signaling axis may present a new way for treatment of gastric cancer, and development of effective SHP-1 inducer may be an important task in the future search field of gastric cancer.

• BMB Reports
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• v.41 no.5
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• pp.408-413
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• 2008

Pyridoxal-5'-phosphate phosphatase (PLPP) catalyzes the dephosphorylation of pyridoxal-5'-phosphate (PLP). A human brain PLPP gene was fused with a PEP-1 peptide and produced a genetic in-frame PEP-1-PLPP fusion protein. The purified PEP-1-PLPP fusion protein was efficiently transduced into PC12 cells in a time- and dose-dependent manner when added exogenously to culture media. Once inside the cells, the transduced PEP-1-PLPP fusion protein was stable for 36 h. The concentration of PLP was markedly decreased by the addition of exogenous PEP-1-PLPP to media pretreated with the vitamin $B_6$ precursors; pyridoxine, pyridoxal kinase and pyridoxine-5'-phosphate oxidase into cells. The results suggest that the transduction of the PEP-1-PLPP fusion protein can be one mode of PLP level regulation, and to replenish this enzyme in the various neurological disorders related to vitamin $B_6$.

• Journal of Korean Neurosurgical Society
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• v.46 no.4
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• pp.389-396
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• 2009

Objective : Triptolide (TP) has been reported to suppress the expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1), of which main function is to inactivate the extracellular signal-regulated kinase-1/2 (ERK-1/2), the p38 MAPK and the c-Jun N-terminal kinase-1/2 (JNK-1/2), and to exert antiproliferative and pro-apoptotic activities. However, the mechanisms underlying antiproliferative and pro-apoptotic activities of TP are not fully understood. The purpose of this study was to examine whether the down-regulation of MKP-1 expression by TP would account for antiproliferative activity of TP in immortalized HT22 hippocampal cells. Methods : MKP-1 expression and MAPK phosphorylation were analyzed by Western blot. Cell proliferation was assessed by $^3H$-thymidine incorporation. Small interfering RNA (siRNA) against MKP-1, vanadate (a phosphatase inhibitor), U0126 (a specific inhibitor for ERK-1/2), SB203580 (a specific inhibitor for p38 MAPK), and SP600125 (a specific inhibitor for JNK-1/2) were employed to evaluate a possible mechanism of antiproliferative action of TP. Results : At its non-cytotoxic dose, TP suppressed MKP-1 expression, reduced cell growth, and induced persistent ERK-1/2 activation. Similar growth inhibition and ERK-1/2 activation were observed when MKP-1 expression was blocked by MKP-1 siRNA and its activity was inhibited by vanadate. The antiproliferative effects of TP, MKP-1 siRNA, and vanadate were significantly abolished by U0126, but not by SB203580 or SP600125. Conclusion : Our findings suggest that TP inhibits the growth of immortalized HT22 hippocampal cells via persistent ERK-1/2 activation by suppressing MKP-1 expression. Additionally, this study provides evidence supporting that MKP-1 may play an important role in regulation of neuronal cell growth.

• Journal of Periodontal and Implant Science
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• v.28 no.1
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• pp.17-35
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• 1998

Chitosan, with a chemical structure similar to hyaluronic acid, has been implicated as a wound healing agent. The purpose of this research was to evaluate the effects of chitosan on the characteristics of periodontal ligament cells, calvaria cells and gingival fibroblasts and to define the effects of chitosan on bone formation in vitro. In control group, the cells were cultured alone with Dulbecco's Modified Eagle's Medium contained with 10% Fetal bovine serum, 100unit/ml penicillin, $100{\mu}g/ml$ streptomycin, $0.5{\mu}g/ml$ amphotericin-B. In experimental group, chitosan($40{\mu}g/ml$) is added into the above culture condition. And then each group was characterized by examining the cell proliferation at 1,3,5,7,9,12,15 day, the amount of total protein synthesis, alkaline phosphatase activity at 3, 7 day and the ability to produce mineralized nodules of rat calvaria cell at 11 day. The results were as follows : 1. At early time both periodontal ligament cells and calvaria cells in chitosan-treated group proliferated more rapidly than in non-treated control group, but chitosan-treated group of periodontal ligament cells at 9 days and calvaria cells at 12days showed lower growth rate than control group. Gingival fibroblast in chitosan-treated group had lower growth rate than in control group but the difference was not statistically significant (P< 0.01).2. Both periodontal ligament cells and calvaria cells in chitosan-treated group showed much protein synthesis than in control group at 3 days, but showed fewer than in control group at 7 days. Amount of total protein synthesis of gingival fibroblast didn't have statistically significant difference among the two groups(P< 0.01). 3. At 3 and 7 days, alkaline phosphatase activity of periodontal ligament cells and calvaria cells was increased in chitosan-treated group, but at 7 days there was not statistically significant difference among the two groups of calvaria cells (P< 0.01). Alkaline phosphatase activity of gingival fibroblast didn't have statistically significant difference among the two groups(P<0.01). 4. Mineralized nodules in chitosan-treated group of rat calvaria cells were more than in control group. In summery, chitosan had an effect on the proliferation, protein systhesis, alkaline phosphatase activity of periodontal ligament cells and calvaria cells, and facilitated the formation of bone. It is thought that these effects can be used clinically in periodontal regeneration therapy.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.5
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• pp.1060-1065
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• 2002

LC20 phosphorylation and PKC α play an important role in modulation of contractile activity of smooth muscle. Besides, myosin phosphatase is also related with smooth muscle contraction in signaling pathways. We previously demonstrated that Crataegi Fructus inhibited phenylephrine-induced contraction and which might be implicated in nitrite formation(Son et al., 2002). In this study, we investigated the effects of butanol fraction of Crataegi Fructus(BFFC) on the localization of α-protein kinease C(PKC α) and myosin phosphatase subnits(MPs) in freshly isolated single ferret potal vein cells, and phosphorylation of LC20 during phenylephrine stimulation. In PKC α and MPs localization, BFFC blocked its translocation from the cytosol to the cell membrane by treatment of phenylephrine. BFFC have also dephosphorylated LC20 phosphorylation by phenylephrine stimulation under basal level, but no significant. These results indicate that the relaxation effect of BFFC is associated with inhibition of PKC α activation and MPs dissociation, and thus myosin phosphatase activity may be increased.

• BMB Reports
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• v.34 no.3
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• pp.262-267
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• 2001

A cDNA coding alkaline phosphatase (AP) homologue was isolated from a cDNA library of Schizosaccharomyces pombe by colony hybridization. The nucleotide sequence of the cloned cDNA appeared to lack the N-terminal coding region. The genomic DNA encoding alkaline phosphatase homologue was isolated from S. pombe chromosomal DNA using PCR. The amplified DNA fragment was ligated into plasmid pRS315 to generate the recombinant plasmid pSW20. The DNA insert was subcloned as two smaller fragments for nucleotide sequencing. The sequence contains 2,789 by and encodes a protein of 532 amino acids with a molecular mass of 58,666 daltons. The S. pombe cells containing plasmid pSW20 showed much higher AP activity compared with the yeast cells with vector only This indicates that the cloned AP gene apparently encodes AP The predicted amino acid sequence of the S. pombe AP shares homology with those of other known APs.

• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.237-242
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• 1992

In order to clone the gene coding for alkaline phosphatase in the yeast Kluyveromyces fragilis, a genomic library was constructed using the yeast-E. coli shuttle vector pHN114 as a cloning vector. From the genomic library, a clone carrying the gene was isolated and the plasmid was designated as pSKH101. A restriction enzyme map was made using this plasmid. Subcloning experiments and complementation studies showed that alkaline phosphatase was active only in the original 3.1 kb insert. Southern hybridization analysis confirmed that the cloned DNA fragment was derived from K. fragilis genomic DNA. Using a minicell experiment, the product of the cloned gene was identified as a protein with a molecular weight of 63 KDa. A 0.6 kb HindIII fragment, which showed promoter activity, was isolated using the E. coli promoter-probe vector pKO-1.

• IMMUNE NETWORK
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• v.23 no.2
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• pp.12.1-12.17
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• 2023

Ssu72, a dual-specificity protein phosphatase, not only participates in transcription biogenesis, but also affects pathophysiological functions in a tissue-specific manner. Recently, it has been shown that Ssu72 is required for T cell differentiation and function by controlling multiple immune receptor-mediated signals, including TCR and several cytokine receptor signaling pathways. Ssu72 deficiency in T cells is associated with impaired fine-tuning of receptor-mediated signaling and a defect in CD4⁺ T cell homeostasis, resulting in immune-mediated diseases. However, the mechanism by which Ssu72 in T cells integrates the pathophysiology of multiple immune-mediated diseases is still poorly elucidated. In this review, we will focus on the immunoregulatory mechanism of Ssu72 phosphatase in CD4⁺ T cell differentiation, activation, and phenotypic function. We will also discuss the current understanding of the correlation between Ssu72 in T cells and pathological functions which suggests that Ssu72 might be a therapeutic target in autoimmune disorders and other diseases.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.5
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• pp.728-734
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• 1999

Thirty new born crossbred (Bos taurus${\times}$Bos indicus) calves, divided randomly in a $3{\times}2$ factorial design, were fed calf starters containing one of three protein sources i.e., groundnut cake (GN), cottonseed meal (CS) and meat and bone meal (MB) along with either raw (M) or gelatinized maize (MG) for 90d. Milk was fed upto 56d of age. Green oats and respective calf starters were offered from 14d of age onwards ad lib. Clinical profile of serum suggested significantly (p<0.05) higher albumin and lower alanine aminotransferase activity due to CS feeding. Alklaine phosphatase activity varied significantly (p<0.05) among dietary treatments showing interaction between protein and starch sources. Inclusion of gelatinized maize resulted in significantly higher concentration of serum globulin (p<0.05) and alkaline phosphatase activity (p<0.01). reduced (p<0.05) ruminal pH was accompanied by a significant decrease (p<0.01) in $NH_3-N$ concentration in the strained rumen liquor (SRL) of MG fed calves. Ruminal amylase activity was lower (p<0.05) on MG diets. Alanine aminotransferase activity in the rumen exhibited a significant (p<0.01) interaction between protein and starch sources. While feeding of CS significantly (p<0.01) reduced alanine aminotransferase activity, inclusion of thermally processed maize reduced (p<0.01) both aspartate and alanine aminotransferase activities in the rumen. The overall blood picture was similar among treatments, whereas rumen metabolites especially enzyme activities, seems to be altered with source of degradable protein an starch.