• Journal of the Korean Chemical Society
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• 제59권2호
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• pp.188-193
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• 2015

• BMB Reports
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• 제46권11호
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• pp.539-543
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• 2013

There is a correlation between obesity and the amount of brown adipose tissue; however, the molecular mechanism of brown adipogenic differentiation has not been as extensively studied. In this study, we performed a protein tyrosine phosphatase (PTP) profiling analysis during the brown adipogenic differentiation of mouse primary brown preadipocytes. Several PTPs, including PTPRF, PTPRZ, and DUSP12 showing differential expression patterns were identified. In the case of DUSP12, the expression level is dramatically downregulated during brown adipogenesis. The ectopic expression of DUSP12 using a retroviral expression system induces the suppression of adipogenic differentiation, whereas a catalytic inactive DUSP12 mutant showed no effect on differentiation. These results suggest that DUSP12 is involved in brown adipogenic differentiation and may be used as a target protein for the treatment or prevention of obesity by the regulation of brown adipogenic differentiation.

• Natural Product Sciences
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• 제15권1호
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• pp.32-36
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• 2009

Glutamate causes neurotoxicity through formation of reactive oxygen species and activation of mitogen-activated protein kinase (MAPK) pathways. MAPK phosphatase-1 (MKP-1) is one of the phosphatases responsible for dephosphorylation/deactivation of three MAPK families: the extracellular signal-regulated kinase-1/2 (ERK-1/2), the c-Jun N-terminal kinase-1/2 (JNK-1/2), and the p38 MAPK. In this report, the potential involvement of MKP-1 in neuroprotective effects of curcumin, the active ingredient of turmeric (Curcuma longa), was examined using HT22 cells. Glutamate caused cell death and activation of ERK-1/2 but not p38 MAPK or JNK-1/2. Blockage of ERK-1/2 by its inhibitor protected HT22 cells against glutamate-induced toxicity. Curcumin attenuated glutamate-induced cell death and ERK-1/2 activation. Interestingly, curcumin induced MKP-1 activation. In HT22 cells transiently transfected with small interfering RNA against MKP-1, curcumin failed to inhibit glutamate-induced ERK-1/2 activation and to protect HT22 cells from glutamate-induced toxicity. These results suggest that curcumin can attenuate glutamate-induced neurotoxicity by activating MKP-1 which acts as the negative regulator of ERK-1/2. This novel pathway may contribute to and explain at least one of the neuroprotective actions of curcumin.

• Microbiology and Biotechnology Letters
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• 제20권3호
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• pp.257-262
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• 1992

Virginiae butanolide (VB) is an autoregulator which triggers virginiamycin production in Strefltomyces virginiae. VB-C binding protein activity was investigated under various additives. The VB-C binding protein was almost fully observed in sotubte fraction (>90%) and the binding activity was optimum at pH 7.0. The VB-C binding activity was increased about 15% in 0.5 M KCI, whereas decreased about 60% in 20 mM $Mo^{6+}$. Chelating reagents (ethylenediarnine tetraacetic acid, ethyleneglycol bis(2-aminoethylether) tetraacetic acid, 8-hydroxyquinoline) and SH protecting reagents (rnercaptoethanol, dithiothreitol, thioglycerol) inhibited the VB-C binding activity about 30~55% and 3~20%, respectively. Serine protease inhibitor (phenyl methane sulfonyl fluoride), nucleotides (guanosine 5'-monophosphate, adenosine 3',5'-cyclic monophosphate), and phosphatases (alkaline, acid phosphatase) increased the VB-C binding activity about 17%, 6~20%, and 4- 13%, respectively.

• BMB Reports
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• 제41권12호
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• pp.881-885
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• 2008

Protein phosphatase 1 consists of a secondary structure arrangement, conserved in the serine/threonine protein phosphatase gene family, flanked by nonconserved N-terminal and C-terminal domains. The deletion mutant of PP1 with the 8 nonconserved N-terminal residues removed was designated PP1-(9-330). PP1-(9-330) had a higher activity and affinity than PP1 when assayed against four different substrates, and it also demonstrated a 6-fold higher sensitivity to the inhibitor okadaic acid. This suggested that the N-terminal domain suppresed the activity of PP1 and interfered with its inhibition by okadaic acid. The ANS fluorescence intensity of PP1-(9-330) was greater than that of PP1, which implies that the hydrophobic groove running from active site in the truncated PP1 was more hydrophobic than in PP1. Our findings provide evidence that the nonconserved N-terminus of PP1 functions as an important regulatory domain that influences the active site and its pertinent properties.

• Journal of Microbiology and Biotechnology
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• 제22권7호
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• pp.1029-1033
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• 2012

A number of evidence have been accumulated that the regulation of reversible tyrosine phosphorylation, which can be regulated by the combinatorial activity of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), plays crucial roles in various biological processes including differentiation. There are a total of 107 PTP genes in the human genome, collectively referred to as the "PTPome." In this study, we performed PTP profiling analysis of the HIB-1B cell line, a brown preadipocyte cell line, during brown adipogenesis. Through RT-PCR and real-time PCR, several PTPs showing differential expression pattern during brown adipogenesis were identified. In the case of PTP-RE, it was shown to decrease significantly until 4 days after brown adipogenic differentiation, followed by a dramatic increase at 6 days. The overexpression of PTP-RE led to decreased brown adipogenic differentiation via reducing the tyrosine phosphorylation of the insulin receptor, indicating that PTP-RE functions as a negative regulator at the early stage of brown adipogenesis.

• Journal of Life Science
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• 제21권1호
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• pp.31-35
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• 2011

Dual-specificity protein phosphatases (DUSPs) constitute a family of protein phosphatase characterized by the ability to dephosphorylate phospho-tyrosyl and phospho-seryl/threonyl residues. Most DUSPs are involved in regulation of cell survival and differentiation. In this study, a human dual-specificity protein phosphatase, DUSP28, was isolated from a human kidney cDNA. The recombinant protein was successfully produed in E.coli and showed sufficient phosphatase activity toward DiFMUP (6,8-difluoro-4-methylumbelliferyl phosphate). Various phosphatase inhibitors and divalent metals were tested for their effects on the DUSP28 phosphatase activity. As a result, $Zn^{2+}$ was found to strongly inhibit DUSP28 phosphatase activity, suggesting DUSP28 is involved in Zn-related signal transduction pathway. Furthermore, the DUSP28 protein preferred phospho-tyrosyl residues to phospho-threonyl residues, implying its physiological roles in the cellular process.

• Journal of Microbiology and Biotechnology
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• 제24권2호
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• pp.152-159
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• 2014

The regulation of protein tyrosine phosphorylation is mediated by protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) and is essential for cellular homeostasis. Co-expression of PTKs with PTPs in Pichia pastoris was used to facilitate the expression of active PTKs by neutralizing their apparent toxicity to cells. In this study, the gene encoding phosphatase PTP1B with or without a blue fluorescent protein or peroxisomal targeting signal 1 was cloned into the expression vector pAG32 to produce four vectors. These vectors were subsequently transformed into P. pastoris GS115. The tyrosine kinases EGFR-2 and $PDGFR{\beta}$ were expressed from vector pPIC3.5K and were fused with a His-tag and green fluorescent protein at the N-terminus. The two plasmids were transformed into P. pastoris with or without PTP1B, resulting in 10 strains. The EGFR-2 and $PDGFR{\beta}$ fusion proteins were purified by $Ni^{2+}$ affinity chromatography. In the recombinant P. pastoris, the PTKs co-expressed with PTP1B exhibited higher kinase catalytic activity than did those expressing the PTKs alone. The highest activities were achieved by targeting the PTKs and PTP1B into peroxisomes. Therefore, the EGFR-2 and $PDGFR{\beta}$ fusion proteins expressed in P. pastoris may be attractive drug screening targets for anticancer therapeutics.

• BMB Reports
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• 제49권7호
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• pp.370-375
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• 2016

Ras oncoproteins are small molecular weight GTPases known for their involvement in oncogenesis, which operate in a complex signaling network with multiple effectors. Approximately 25% of human tumors possess mutations in a member of this family. The Raf1/MEK/Erk1/2 pathway is one of the most intensively studied signaling mechanisms. Different levels of regulation account for the inactivation of MAP kinases by MAPK phosphatases in a cell type- and stimuli-dependent manner. In the present study, using three inducible Ras-expressing NIH/3T3 cell lines, we demonstrated that MKP3 upregulation requires the activation of the Erk1/2 pathway, which correlates with the shutdown of this pathway. We also demonstrated, by applying pharmacological inhibitors and effector mutants of Ras, that induction of MKP3 at the protein level is positively regulated by the oncogenic Ras/Raf/MEK/Erk1/2 signaling pathway.

• Korean Journal of Veterinary Research
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• 제52권2호
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• pp.99-104
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• 2012

The present study was performed to evaluate the relationship between the neurotoxicity of acrylamide and the differential gene expression pattern in mice. Both locomotor test and rota-rod test showed that the group treated with higher than 30 mg/kg/day of acrylamide caused impaired motor activity in mice. Based on cDNA microarray analysis of mouse brain, myelin basic protein gene, kinesin family member 5B gene, and fibroblast growth factor (FGF) 1 and its receptor genes were down-regulated by acrylamide. The genes are known to be essential for neurofilament synthesis, axonal transport, and neuroprotection, respectively. Interestingly, both FGF 1 and its receptor genes were down-regulated. Genes involved in nucleic acid binding such as AU RNA binding protein/enoyl-coA hydratase, translation initiation factor (TIF) 2 alpha kinase 4, activating transcription factor 2, and U2AF 1 related sequence 1 genes were down-regulated. More interesting finding was that genes of both catalytic and regulatory subunit of protein phosphatases which are important for signal transduction pathways were down-regulated. Here, we propose that acrylamide induces neurotoxicity by regulation of genes associated with neurofilament synthesis, axonal transport, neuro-protection, and signal transduction pathways.