• Journal of Life Science
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• v.26 no.10
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• pp.1182-1188
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• 2016

Membrane-associated guanylate kinase inverted-3 (MAGI-3) is a member of the family of membrane-associated guanylate kinases (MAGUKs). MAGI-3 modulates the kinase activity of protein kinase B (PKB)/AKT through interactions with phosphatase and tensin homolog (PTEN)/MMAC. Coxsackievirus B3 (CVB3) is a common causative agent of acute myocarditis and chronic dilated cardiomyopathy. Activation of AKT and extracellular signal-regulated kinases 1/2 (ERK1/2) is essential for CVB3 replication, but the relation between MAGI-3 signaling and CVB3 replication is not well understood. This study investigated the role of MAGI-3 in CVB3 infection and replication. MAGI-3 was overexpressed in HeLa cells by polyethylenimine (PEI) transfection. To optimize the transfection conditions, different ratios of plasmid DNA to PEI concentrations were used. MAGI-3 and empty plasmid DNA were transfected into the HeLa cells. MAGI-3 overexpression alone was not sufficient to efficiently activate AKT. However, expression of the CVB3 capsid protein VP1 dramatically increased in the HeLa cells overexpressing MAGI-3 24 h after CVB3 infection. In addition, the activities of AKT and ERK were significantly induced in the CVB3-infected MAGI-3 cells overexpressing HeLa. These results demonstrate that MAGI-3 expression upregulates CVB3 replication through AKT and ERK signaling activation. MAGI-3 may be an important target to control CVB3 replication.

• Korean Journal of Veterinary Pathology
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• v.1 no.1
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• pp.26-32
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• 1997

Protein kinase C an enzyme of signal transduction has been known to regulate cell proliferation activation as well as apoptosis in some cancer cell lines. To explore the role of PKC in the course of cell mediated autoimmune disease such as experimental autoimmune encephalomyelitis (EAE) EAE was induced in Lewis rats(6-8 weeks old) with immunization of myelin basic protein supplemented with complete Freund's adjuvants and affected spinal cords were sampled at days 13 postimmunization(PI) as peak stage of EAE and at days 21 PI as recovery stage. The spinal cords with EAE were subjected to Northern blot analysis and insitu hybridization of PKC delta which is one of prominant isotypes of PKC in the haematopoietic cells. Northern blot analysis showed that levels of PKS delta mRNA in the spinal cords of rats withEAE was significantly increased at days 13 PI in which inflammatory cells including T cells and macrophages in the EAE lesions appeared. however the stage. By in situ hybridization signals of PKC delta in EAE lesions was intensely expressed on the delta is also expressed on some brain cells in normal rat central nervous system This finding suggests that PKC plays an important role on either activation of inflammatory cells including encephalitogenic T cells and macrophages or apoptotic elimination of some inflammatory cells depending on the stge of EAE.

• Environmental Analysis Health and Toxicology
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• v.21 no.3 s.54
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• pp.245-253
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• 2006

We reported previously that glucagon decreased alpha- and pi-class glutathione S-transferases (GSTs) and microsomal epoxide hydrolase (mEN) protein levels in primary cultured rat hepatocytes. The present study examines the effects of Protein kinase A (PKA) inhibitor, KT5720, on the glucagon-mediated decrease in expression of GSTs and mEN. To assess cell viability. lactate dehydrogenase release and MTT activity were examined in hepatocytes treated KT5720. Cell viability was significantly decreased in a concentration dependent manner after incubation with KT5720 at the concentrations of 1 $\mu$M or above for 24 h, which was inhibited by the cytochrome P450 inhibitor SKF-525A. In contrast, another PKA inhibitor H89 (up to 25 $\mu$M) was not toxic to hepatocytes. The glucagon-mediated decrease in expression of alpha- and pi-class GSTs and mEH was completely inhibited by 25 $\mu$M H89 and attenuated by 0.1 $\mu$M KT5720. This study demonstrates that KT5720 may cause cytotoxicity in rat hepatocytes through cytochrome P450-dependent bioactivation. The present study implicates PKA in mediating the inhibitory effect of glucagon on expression of alpha- and pi- class GSTs and mEH.

• Journal of Ginseng Research
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• v.42 no.4
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• pp.436-446
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• 2018

Background: The potential therapeutic values of Korean Red Ginseng extract (KRGE) in autoimmune disorders of nervous system have not been fully investigated. Methods: We used an acute experimental autoimmune encephalomyelitis animal model of multiple sclerosis and determined the effects and mechanism of KRGE on spinal myelination. Results: Pretreatment with KRGE (100 mg/kg, orally) for 10 days before immunization with myelin basic protein $(MBP)_{68-82}$ peptide exerted a protective effect against demyelination in the spinal cord, with inhibited recruitment and activation of immune cells including microglia, decreased mRNA expression of detrimental inflammatory mediators (interleukin-6, interferon-${\gamma}$, and cyclooxygenase-2), but increased mRNA expression of protective inflammatory mediators (insulin-like growth factor ${\beta}1$, transforming growth factor ${\beta}$, and vascular endothelial growth factor-1). These results were associated with significant downregulation of p38 mitogen-activated protein kinase and nuclear factor-${\kappa}B$ signaling pathways in microglia/macrophages, T cells, and astrocytes. Conclusion: Our findings suggest that KRGE alleviates spinal demyelination in acute experimental autoimmune encephalomyelitis through inhibiting the activation of the p38 mitogen-activated protein kinase/nuclear factor-${\kappa}B$ signaling pathway. Therefore, KRGE might be used as a new therapeutic for autoimmune disorders such as multiple sclerosis, although further investigation is needed.

• Molecules and Cells
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• v.44 no.10
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• pp.710-722
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• 2021

Hypoxia, or low oxygen tension, is a hallmark of the tumor microenvironment. The hypoxia-inducible factor-1α (HIF-1α) subunit plays a critical role in the adaptive cellular response of hypoxic tumor cells to low oxygen tension by activating gene-expression programs that control cancer cell metabolism, angiogenesis, and therapy resistance. Phosphorylation is involved in the stabilization and regulation of HIF-1α transcriptional activity. HIF-1α is activated by several factors, including the mitogen-activated protein kinase (MAPK) superfamily. MAPK phosphatase 3 (MKP-3) is a cytoplasmic dual-specificity phosphatase specific for extracellular signal-regulated kinase 1/2 (Erk1/2). Recent evidence indicates that hypoxia increases the endogenous levels of both MKP-3 mRNA and protein. However, its role in the response of cells to hypoxia is poorly understood. Herein, we demonstrated that small-interfering RNA (siRNA)-mediated knockdown of MKP-3 enhanced HIF-1α (not HIF-2α) levels. Conversely, MKP-3 overexpression suppressed HIF-1α (not HIF-2α) levels, as well as the expression levels of hypoxia-responsive genes (LDHA, CA9, GLUT-1, and VEGF), in hypoxic colon cancer cells. These findings indicated that MKP-3, induced by HIF-1α in hypoxia, negatively regulates HIF-1α protein levels and hypoxia-responsive genes. However, we also found that long-term hypoxia (>12 h) induced proteasomal degradation of MKP-3 in a lactic acid-dependent manner. Taken together, MKP-3 expression is modulated by the hypoxic conditions prevailing in colon cancer, and plays a role in cellular adaptation to tumor hypoxia and tumor progression. Thus, MKP-3 may serve as a potential therapeutic target for colon cancer treatment.

• Development and Reproduction
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• v.3 no.1
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• pp.75-85
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• 1999

To investigate the origin and action mechanism of cytoplasmic factors as regulators of morphogenesis, the embryonic development, RNA synthesis and protein phosphorylation were examined in reconstituted embryos. A half of 1-cell mouse embryo with both pronuclei was electrofused with the enucleated cytoplasm of 1- or 2-cell embryos which were cultured for 24 hrs from post 20 hrs hCG in CZB with or without cycloheximide (CHX, an inhibitor of protein synthesis; P+P-CHX group), genistein (Gen, an inhibitor of tyrosine protein kinase; P+2-Gen group) and 6-dimethylaminopurine (6-DMAP, an inhibitor of serine-threonine protein kinase; P＋2-DMAP group), and co-cultured with Vero cells for 5 days. And their development, cell numbers at compaction, [5, 6-$^3$H]-uridine incorporation into RNA and the pattern of protein phosphorylation after labeling of [$^{32}$ P] orthophosphate were compared with that of the reconstituted embryos such as P+2 or P+P (control group). Embryonic development and the time of RNA synthesis in P+P-CHX were similar to those in P+P. But the time and the cell stages of embryonic compaction in P+P-CHX were similar to those in P+2. The compaction was initiated at 4-cell in P+2 and P+2-Gen, but at 8-cell in P+P and P+2-DMAP. On a two-dimensional gel electrophoresis, phosphorylation of 80KD and 110KD proteins were inhibited after 3 hrs of reconstruction in the embryo of P+2-DMAP when compared with that of P+2 and P+2-Gen. These results suggest that protein synthesis between 1- and 2-cell stage affects the timing of embryonic genome activation, and that cytoplasmic factors derived from oocyte or their modification regulates the time schedule of embryonic compaction in mouse. Also, serine-threonine protein kinase has an important role on the regulation of compaction.

• KSBB Journal
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• v.22 no.5
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• pp.282-287
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• 2007

The antiviral mechanism of KT5720 is known to inhibit the cAMP-dependent protein kinase (PKA), on the VSV infection in BHK-21 cell cultures. The virus inducted CPE (cell rounding) was almost completely suppressed by KT5720 at 5 uM. The inhibitor, however, did not affect the replication of the virus and the synthesis of viral macromolecules. Immunological studies showed the viral matrix (M) protein displayed intimate association with the cytoskeletal components and probably the cell rounding. KT5720, did not block the cytoskeletal disruption, while the cell rounding was suppressed. These observations suggest that the interaction between the viral M protein and the cytoskeletal components may not be enough to cause the morphological change of the cell. And, the KT5720-sensitive function may be involved in developing the VSV-induced CPE, but not essential for the virus replications.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.295-298
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• 2008

Creatine kinase (CK; E.C. 2.7.3.2) is an important enzyme that catalyzes the reversible transfer of a phosphoryl group from ATP to creatine in energy homeostasis. The brain-type cytosolic isoform of creatine kinase (BB-CK), which is found mainly in the brain and retina, is a key enzyme in brain energy metabolism, because high-energy phosphates are transfered through the creatine kinase/phosphocreatine shuttle system. The recombinant human BB-CK protein was overexpressed as a soluble form in Escherichia coli and crystallized at $22^{\circ}C$ using PEG 4000 as a precipitant. Native X-ray diffraction data were collected to $2.2{\AA}$ resolution using synchrotron radiation. The crystals belonged to the tetragonal space group $P4_32_12$, with cell parameters of a=b=97.963, $c=164.312{\AA},\;and\;{\alpha}={\beta}={\gamma}=90^{\circ}$. The asymmetric unit contained two molecules of CK, giving a crystal volume per protein mass $(V_m)$ of $1.80{\AA}^3\;Da^{-1}$ and a solvent content of 31.6%.

• Molecules and Cells
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• v.24 no.1
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• pp.9-15
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• 2007

To investigate the effects of chitosan on the redifferentiation of dedifferentiated chondrocytes, we used chondrocytes obtained from a micromass culture system. Micromass cultures of chick wing bud mesenchymal cells yielded differentiated chondrocytes, but these dedifferentiated during serial monolayer subculture. When the dedifferentiated chondrocytes were cultured on chitosan membranes they regained the phenotype of differentiated chondrocytes. Expression of protein kinase $C{\alpha}$ ($PKC{\alpha}$) increased during chondrogenesis, decreased during dedifferentiation, and increased again during redifferentiation. Treatment of the cultures with phorbol 12-myristate 13-acetate (PMA) inhibited redifferentiation and down-regulated $PKC{\alpha}$. In addition, the expression of p38 mitogen-activated protein (MAP) kinase increased during redifferentiation, and its inhibition suppressed redifferentiation. These findings establish a culture system for producing chondrocytes, point to a new role of chitosan in the redifferentiation of dedifferentiated chondrocytes, and show that $PKC{\alpha}$ and p38 MAP kinase activities are required for chondrocyte redifferentiation in this model system.

• Plant Biotechnology Reports
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• v.2 no.4
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• pp.227-231
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• 2008

D-class cyclins play important roles in controlling the cell cycle in development and in response to external signals by forming the regulatory subunit of cyclin-dependent kinase (CDK) complexes. To evaluate the effects of D-class cyclins in transgenic rice plants, Arabidopsis cyclin D2 gene (CycD2) was linked to the maize ubiquitin1 promoter (Ubi1) and introduced into rice by the Agrobacterium-mediated transformation method. Genomic deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and Western blot hybridizations of the Ubi1:-CycD2 plants revealed copy number of transgene and its increased expression in leaf and callus cells at messenger RNA (mRNA) and/or protein levels. The H1 kinase assay using the immunoprecipitates of protein extracts from the Ubi1:CycD2 plants and nontransgenic controls demonstrated that the introduced Arabidopsis CycD2 forms a functional CycD2/CDK complex with an unidentified CDK of rice. Shoot and root growth was enhanced in the Ubi1:CycD2 seedlings compared with nontransgenic controls, together, suggesting that Arabidopsis cyclin D2 interacts with a rice cyclin-dependent kinase, consequently enhancing seedling growth.