• BMB Reports
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• 제45권12호
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• pp.693-699
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• 2012

Together with protein tyrosine kinases (PTKs), protein tyrosine phosphatases (PTPs) serve as hallmarks in cellular signal transduction by controlling the reversible phosphorylation of their substrates. The human genome is estimated to encode more than 100 PTPs, which can be divided into eleven sub-groups according to their structural and functional characteristics. All the crystal structures of catalytic domains of sub-groups have been elucidated, enabling us to understand their precise catalytic mechanism and to compare their structures across all sub-groups. In this review, I describe the structure and mechanism of catalytic domains of PTPs in the structural context.

• Journal of Photoscience
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• 제7권3호
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• pp.123-128
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• 2000

Phosphorylation of cellular proteins is a key regulatory mehanism for signal transduction pathway in living cells. Phytochrome, a red/far-red light photoreceptor in plants, is known to employ protein phosphorylation for its light signaling, although its detauked mechanism is still ambiguous. This study is intended to identify the phosphoproteins and protein kinases that are regulated by phytochrome, by employing transgenic rice seedlings that overexpress Arabidopsis phytochrome A. Red light stimulated phsophorylation of a 70 kDa protein and far-red light negated the effect. The red light induced phosphotylation of the 70 kDa protein was strongly activated by heparin and inhibited by poly-L-lysine, suggesting that the 70 kDa protein phosphorylating kinase belongs to GSK-3/SHAGGY protein kinase that has functional roles in establishing cell fate and pattern formation in Drosophila. Taken together with the fact that phytochrome controls plant development, these results may suggest that a GSK-3/SHAGGY-related protein kinase in plant(ASK) is likely to be involved in phytochrome signal transduction.

• 동의생리병리학회지
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• 제28권5호
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• pp.486-493
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• 2014

Adipocytes are endocrine cells that release bioactive mediators called adipokines. In condition of obesity characterized by low-grade chronic inflammation, adipocytes release inflammatory adipokines, which is related to insulin resistance. Bojungchiseub-tang (BJCST) has been used in symptoms and signs of edema, dampness-phlegm, kidney failure, and so on in Korean medicine. BJCST is also expected to have anti-obesity activities. In the present study, we examined whether BJCST modulate the production of inflammatory adipokines and the activations of the mitogen-activated protein kinases (MAPK) signaling pathway related to induce adipocyte inflammation to elucidate the effects and its mechanism of BJCST on lowering the content of inflammatory adipokines in 3T3-L1 adipocytes. As a result, BJCST suppressed the production of proinflammatory cytokines, tumor necrosis factor (TNF) $-{\alpha}$, interleukin (IL) $-1{\beta}$, IL-6, interferon (IFN) -${\gamma}$, granulocyte-macrophage colony-stimulating factor (GM-CSF), monocyte chemoattractant protein-1 (MCP-1), and the production of other inflammatory mediators, prostaglandin $E_2(PGE_2)$ and nitric oxide(NO)viadownregulationofcyclooxygenase-2(COX-2)andinducible NO synthase (iNOS) gene expressions. In addition, BJCST decreased the phosphorylation of MAPK that promotes the production of inflammatory adipokines in 3T3-L1 mature adipocytes. In conclusion, BJCST could regulate the production of inflammatory adipokines and MAPK signaling pathway related to induction of adipose inflammation.

• BMB Reports
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• 제32권4호
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• pp.379-384
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• 1999

Taxol, a natural product with significant anti-tumor activity, stabilizes microtubules and arrests cells in the G2/M phase of the cell cycle. It has been reported that taxol has additional effects on the cell such as an increase in tyrosine phosphorylation of proteins and activation of mitogen-activated protein (MAP) kinase. This phosphorylated kinase translocates into the nucleus and phosphorylates its substrate c-jun, c-fos, ATF2, and ATF3. The MAP kinase family is comprised of key regulatory proteins that control the cellular response to both proliferation and stress signals. First examination was cytotoxicity and apoptosis-induced concentration with paclitaxel in HeLa cell. A half-maximal inhibition of cell proliferation ($IC_{50}$) occurred at 13 nM paclitaxel. When DNA fragmentation was analyzed by agarose gel electrophoresis, a nucleosomal ladder became evident 24 h after a taxol (50 nM) addition to the cells. In addition, an apoptotic body was detected by electron microscopy. Taxol-treated cells were arrested at the S phase at 10 nM. Treatment of 50 nM taxol activated the extracellular signal-regulated protein kinase (ERK1), and a fraction of the activated MAP kinases entered the nucleus. It was also discovered that nucleus substrates c-jun was phosphorylated and activated in the cell. The activated ERK1 could subsequently translocate into the nucleus and phosphorylate its substrate c-jun as well. This study suggests that taxol-induced apoptosis might be related with signal transduction via MAP kinases.

• 대한의생명과학회지
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• 제10권4호
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• pp.325-332
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• 2004

Inflammatory factor such as Interleukin-1 play important roles in determining the fate of both acute and chronic neurological disorders. We investigated whether inhibitors of PKC or PTK can serve as pharmacological agents to reduce IL-I production and the mechanisms underlying their pharmacological effects in a mixed population of glia. Inhibitors of PKC such as H7, Go6976 and Ro31-8220 significantly reduced both the mRNA and protein levels of IL-1α and IL-β in lipopolysaccharide-activated primary glial cells. While the PTK inhibitor genistein also significantly reduced the production of these cytokines, it did not affect the expression of their mRNA. Taken together, inhibitors of PKC and PTK could serve as pharmacological agents to reduce IL-1 production. However, the mechanisms underlying their pharmacological effects are different. Our results provide evidence that inhibitors of protein kinases can serve as pharmacological agents to modulate IL-1 production in glial cell, and in turn, alleviate neuronal injury.

• Biomolecules & Therapeutics
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• 제21권6호
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• pp.435-441
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• 2013

Emodin, a naturally occurring anthraquinone derivative isolated from Polygoni cuspidati radix, has several beneficial pharmacologic effects, which include anti-cancer, anti-diabetic, and anti-inflammatory activities. In this study, the authors examined the effect of emodin on the production of proinflammatory cytokines, such as, tumor necrosis factor (TNF)-${\alpha}$ and interleukin (IL)-6, in mouse bone marrow-derived mast cells (BMMCs) stimulated with phorbol 12-myristate 13-acetate (PMA) plus the calcium ionophore A23187. To investigate the mechanism responsible for the regulation of pro-inflammatory cytokine production by emodin, the authors assessed its effects on the activations of transcriptional factor nuclear factor-${\kappa}B$ (NF-${\kappa}B$) and mitogen-activated protein kinases (MAPKs). Emodin attenuated the nuclear translocation of (NF)-${\kappa}B$ p65 and its DNA-binding activity by reducing the phosphorylation and degradation of $I{\kappa}B{\alpha}$ and the phosphorylation of $I{\kappa}B$ kinase B (IKK). Furthermore, emodin dose-dependently attenuated the phosphorylations of MAPKs, such as, extracellular signal-regulated kinase 1/2 (ERK1/2), p38 MAP kinase, and the stress-activated protein kinases (SAPK)/c-Jun-N-terminal kinase (JNK). Taken together, the findings of this study suggest that the anti-inflammatory effects of emodin on PMA plus A23187-stimulated BMMCs are mediated via the inhibition of NF-${\kappa}B$ activation and of the MAPK pathway.

• Asian Pacific Journal of Cancer Prevention
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• 제15권15호
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• pp.6247-6251
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• 2014

Background: The aim of the present study was to investigate the involvement of emodin on the growth of human breast cancer MCF-7 and MDA-MB-231 cells and the estrogen (E2) signal pathway in vitro. Materials and Methods: MTT assays were used to detect the effects of emodin on E2 induced proliferation of MCF-7 and MDA-MB-231 cells. Flow cytometry (FCM) was applied to determine the effect of emodin on E2-induced apoptosis of MCF-7 cells. Western blotting allowed detection of the effects of emodin on the expression of estrogen receptor ${\alpha}$, cyclin D1 and B-cell lymphoma-2 (Bcl-2), mitogen-activated protein kinases (MAPK) and phosphatidylinostiol 3-kinases (PI3K). Luciferase assays were emplyed to assess transcriptional activity of $ER{\alpha}$. Results: Emodin could inhibit E2-induced MCF-7 cell proliferation and anti-apoptosis effects, and arrest the cell cycle in G0/G1 phase, further blocking the effect of E2 on expression and transcriptional activity of $ER{\alpha}$. Moreover, Emodin influenced the ER ${\alpha}$ genomic pathway via downregulation of cyclin D1 and Bcl-2 protein expression, and influenced the non-genomic pathway via decreased PI3K/Akt protein expression. Conclusions: These findings indicate that emodin exerts inhibitory effects on MCF-7 cell proliferation via inhibiting both non-genomic and genomic pathways.

• Food Science and Biotechnology
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• 제18권5호
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• pp.1063-1070
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• 2009

Dangyuja (Citrus grandis Osbeck) is a native plant growing only on Jeju Island in Korea. In this study, antiinflammatory effect of dangyuja leaves on a murine macrophage cell line was investigated. RAW 264.7 murine macrophage cells were stimulated with lipopolysaccharide (LPS, $1{\mu}g/mL$) to induce expression of pro-inflammatory markers [interleukin (IL)-6 and inducible nitric oxide synthase (iNOS)]. The crude extract (80% MeOH Ex.) and solvent fractions (hexane, $CHCl_3$, EtOAc, BuOH, and $H_2O$ Ex.) were obtained from dangyuja leaves. The $CHCl_3$ fraction inhibited the nitric oxide (NO) and IL-6 production in a dose-dependent manner. Also, the $CHCl_3$ fraction inhibited mRNA expression and protein levels of iNOS in a dose-dependent manner. Furthermore, the $CHCl_3$ fraction inhibited LPS-induced nuclear factor (NF)-${\kappa}B$ activation and phosphorylation of mitogen-activated protein kinases (MAPKs: ERK, JNK, and p38). These results suggest that dangyuja leaves may inhibit LPS-induced production of inflammatory markers by blocking NF-${\kappa}B$ and MAPKs signaling in RAW 264.7 cells.

• The Korean Journal of Physiology and Pharmacology
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• 제3권3호
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• pp.357-364
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• 1999

We investigated the role of $Ca^{2+}$ and protein kinases/phosphatases in the stimulatory effect of insulin on glucose transport. In isolated rat adipocytes, the simple omission of $CaCl_2$ from the incubation medium significantly reduced, but did not abolish, insulin-stimulated 2-deoxy glucose (2-DG) uptake. Pre-loading adipocytes with intracellular $Ca^{2+}$ chelator, 5,5'-dimethyl bis (o-aminophenoxy)ethane-N,N,N'N' tetraacetic acetoxymethyl ester (5,5'-dimethyl BAPTA/AM) completely blocked the stimulation. Insulin raised intracellular $Ca^{2+}$ concentration $([Ca^{2+}]_i)$ about 1.7 times the basal level of $72{\pm}5$ nM, and 5,5'-dimethyl BAPTA/AM kept it constant at the basal level. This correlation between insulin-induced increases in 2-DG uptake and $[Ca^{2+}]_i$ indicates that the elevation of $[Ca^{2+}]_i$ may be prerequisite for the stimulation of glucose transport. Studies with inhibitors (ML-9, KN-62, cyclosporin A) of $Ca^{2+}-calmodulin$ dependent protein kinases/phosphatases also indicate an involvement of intracellular $Ca^{2+}.$ Additional studies with okadaic acid and calyculin A, protein phosphatase-1 (PP-1) and 2A (PP-2A) inhibitors, indicate an involvement of PP-1 in insulin action on 2-DG uptake. These results indicate an involvement of $Ca^{2+}-dependent$ signaling pathway in insulin action on glucose transport.

• Journal of Microbiology and Biotechnology
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• 제21권9호
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• pp.903-913
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• 2011

Vibrio parahaemolyticus, which causes gastroenteritis, wound infection, and septicemia, has two sets of type III secretion systems (TTSS), TTSS1 and TTSS2. A TTSS1-deficient vcrD1 mutant of V. parahaemolyticus showed an attenuated cytotoxicity against HEp-2 cells, and a significant reduction in mouse lethality, which were both restored by complementation with the intact vcrD1 gene. V. parahaemolyticus also triggered phosphorylation of mitogen-activated protein kinases (MAPKs) including p38 and ERK1/2 in HEp-2 cells. The ability to activate p38 and ERK1/2 was significantly affected in a TTSS1-deficient vcrD1 mutant. Experiments using MAPK inhibitors showed that p38 and ERK1/2 MAPKs are involved in V. parahaemolyticus-induced death of HEp-2 cells. In addition, caspase-3 and caspase-9 were processed into active forms in V. parahaemolyticus-exposed HEp-2 cells, but activation of caspases was not essential for V. parahaemolyticus-induced death of HEp-2 cells, as shown by both annexin V staining and lactate dehydrogenase release assays. We conclude that secreted protein(s) of TTSS1 play an important role in activation of p38 and ERK1/2 in HEp-2 cells that eventually leads to cell death via a caspase-independent mechanism.