• Journal of Plant Biology
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• v.35 no.1
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• pp.85-90
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• 1992

The previous report (Chung and Lee, 1992) in our laboratory demonstrated that the protein kinase C (PKC) activator, TPA, promotes the elongation of corn coleoptiles significantly. To understand the role of TPA on the growth, substrates of PKC were investigated using PKC partially purified from soybean by DEAE-52 cellulose column. The enzyme activity increased about 5-fold in the presence of $Ca^{2+}$, phosphatidylserine and diolein compared with that in the absence of these reagents. Phosphorylation of both cytosol and membrane proteins by the purified PKC increased in the presence of $Ca^{2+}$ compared with that of EGTA treatment. However, the phosphorylation did not increase markedly by treatment with TPA or phosphatidylserine and diolein in the presence of $Ca^{2+}$ compared with $Ca^{2+}$ alone. The decrease, in phosphorylation of 100, 61 and 43 Kd proteins of the cytosol, and 140, no, 66, 47 and 32 Kd membrane proteins in hypocotyls, and 140, no, 66, 47, 33, 31 and 16 Kd membrane proteins in the root was observed in the presence of PKC inhibitor staurosporine (5T A). These results suggest that subatrates of PKC in soybean may be 110, 63 and 41 Kd proteins of the cytosol, and 140, 110, 66, 47 and 32 Kd membrane proteins in the subapical region of the hypocotyl, and 140, 110, 66, 47, 33, 31 and 16 Kd membrane proteins of the root.e root.

• Biomedical Science Letters
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• v.22 no.2
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• pp.60-64
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• 2016

In the pathogenesis of inflammatory diseases such as allergies, S100A8 acts as an important molecule and T lymphocytes are essential cytokine-releasing cells. In this study, we investigated the effect of S100A8 on release of cytokines, specifically MCP-1, IL-6, and IL-8 in T cells, and its associated signaling mechanism. S100A8 increased secretion of MCP-1, IL-6, and IL-8 in a time- and dose-dependent manner. Elevated secretion of MCP-1, IL-6, and IL-8 due to S100A8 was inhibited by the TLR4 inhibitor TLR4i, the PI3K inhibitor LY294002, the $PKC{\delta}$ inhibitor rottlerin, the ERK inhibitor PD98059, the p38 MAPK inhibitor SB202190, the JNK inhibitor SP600125, and the NF-${\kappa}B$ inhibitor BAY-11-7085. S100A8 induced phosphorylation of ERK, p38 MAPK, and JNK in a time-dependent manner, and activation was suppressed by TLR4i, LY294002, and rottlerin. S100A8 induced NF-${\kappa}B$ activation by $I{\kappa}-B{\alpha}$ degradation, and NF-${\kappa}B$ activity was suppressed by PD98059, SB202190, and SP600125. These results indicate that S100A8 induces cytokine release via TLR4. Study of PI3K, $PKC{\delta}$, MAPKs, and NF-${\kappa}B$ will contribute to elucidation of the S100A8-invovled mechanism.

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.1
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• pp.29-36
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• 2011

Nardostachyts chinensis (N. chinensis) belonging to the family Valerianaceae has been used to elicit stomachic and sedative effects. The MAPKs are serine/threonine kinases involved in the regulation of various cellular responses, such as cell proliferation, differentiation and apoptosis. The PKC also plays a key role in regulating the response of hematopoietic cells to both physiological and pathological inducers of proliferation and differentiation. This study investigated the signaling pathways on the U937 cell differentiation induced by N. chinensis. N. chinensis induced the differentiation of U937 cells, as shown by increased of differentiation surface antigen CD11b. Activation of ERK increased time-dependently in differentiation of U937 cells induced by N. chinensis, but activations of JNK and p38 were unaffected. Inhibitor of ERK (PD98059) significantly reduced CD11b expression induced by N. chinensis in U937 cells. In addition, N. chinensis increased protein level of PKC ${\beta}$I and PKC ${\beta}$II isoforms, but the protein level of PKC ${\alpha}$ and PKC ${\gamma}$was constant. PKC inhibitors (GF 109203X and H-7) inhibited U937 cell differentiation and the ERK activation induced by N. chinensis. These results indicated that PKC and ERK may be involved in U937 cell differentiation induced by N. chinensis.

• Archives of Pharmacal Research
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• v.29 no.12
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• pp.1114-1118
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• 2006

(+)-Eudesmin [4,8-bis(3,4-dimethoxyphenyl)-3,7 -dioxabicyclo[3.3.0]octane] was isolated from the stem bark of Magnolia kobus DC. var. borealis Sarg. and found to have neuritogenic activity. $50\;{\mu}M$ (+)-eudesmin induced neurite outgrowth and enhanced nerve growth factor (NGF)-mediated neurite outgrowth from PC12 cells. At this concentration, (+)-eudesmin also enhanced NGF-induced neurite-bearing activity and this activity was partially blocked by various protein kinase inhibitors. These included PD98059, a mitogen-activated protein kinase (MAPK) kinase inhibitor. GF109203X, a protein kinase C (PKC) inhibitor and H89, a protein kinase A (PKA) inhibitor. These results suggest that (+)-eudesmin can induce neurite outgrowth from PC12 cells by stimulating up-stream MAPK, PKC and PKA pathways.

• Molecules and Cells
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• v.25 no.4
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• pp.504-509
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• 2008

Three G-protein-linked acetylcholine receptors (GARs) exist in the nematode C. elegans. GAR-3 is pharmacologically most similar to mammalian muscarinic acetylcholine receptors (mAChRs). We observed that carbachol stimulated ERK1/2 activation in Chinese hamster ovary (CHO) cells stably expressing GAR-3b, the predominant alternatively spliced isoform of GAR-3. This effect was substantially reduced by the phospholipase C (PLC) inhibitor U73122 and the protein kinase C (PKC) inhibitor GF109203X, implying that PLC and PKC are involved in this process. On the other hand, GAR-3b-mediated ERK1/2 activation was inhibited by treatment with forskolin, an adenylate cyclase (AC) activator. This inhibitory effect was blocked by H89, an inhibitor of cAMP-dependent protein kinase A (PKA). These results suggest that GAR-3b-mediated ERK1/2 activation is negatively regulated by cAMP through PKA. Together our data show that GAR-3b mediates ERK1/2 activation in CHO cells and that GAR-3b can couple to both stimulatory and inhibitory pathways to modulate ERK1/2.

• Archives of Plastic Surgery
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• v.33 no.1
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• pp.5-12
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• 2006

Protein tyrosine kinase(PTK), protein kinase C(PKC), oxidase, as a mediator, take a significant role in signal transduction pathway of angiogenesis. The authors utilized the inhibitors, targeting the formation of three co-enzyme in signal transduction pathway in order to quantify the suppression of abnormal vascular endothelial cell proliferation induced by DMH, to compare the level suppression in each up-regulated growth factors, CTGF, CYR61, $ITG{\beta}1$, FHL2, and to identify the relationship between abnormal cell proliferation and signal transduction pathway. Five groups were established; Control group, Group of DMH, Group of DMH-mixed Herbimycin, inhibitor of protein tyrosine kinase, Group of DMH-mixed Calphostin C, inhibitor of protein kinase C, Group Of Dmh-Mixed 10U Catalase, Inhibitor Of oxidase. The rise of vascular endothelial cell was compared by MTT assay, and four growth factors were analysed with RT-PCR method, at pre-administration, 4, 8, 12, and 24 hours after administration. In comparison of abnormal proliferation of vascular endothelial cell induced by DMH, suppression was noticed in Herbimycin and Calphostin C group, and Calphostin C group revealed higher suppression effect. Nevertheless, Catalase group did not have any suppression. In manifestation of four growth factors, Herbimycin and Calphostin C group presented similar manifestation with control group, except in $ITG{\beta}$. Catalse group had similar manifestation with DMH group in all four growth factors. Abnormal proliferation of vascular endothelial cell induced by DMH have a direct relationship with PTK and PKC, more specifically to PKC. Oxidase was confirmed not to have any relevance.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.6
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• pp.743-752
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• 1998

The atrial acetylcholine-activated $K^+\;(K_{ACh})$ channel is gated by the pertussis toxin-sensitive inhibitory G $(G_K)$ protein. Earlier studies revealed that ATP alone can activate the $K_{ACh}$ channel via transphosphorylation mediated by nucleoside-diphosphate kinase (NDPK) in atrial cells of rabbit and guinea pig. This channel can be activated by various agonists and also modulated its function by phosphorylation. ATP-induced $K_{ACh}$ channel activation (AIKA) was maintained in the presence of the NDPK inhibitor, suggesting the existence of a mechanism other than NDPK-mediated process. Here we hypothesized the phosphorylation process as another mechanism underlying AIKA and was undertaken to examine what kinase is involved in atrial cells isolated from the rat heart. Single application of 1 mM ATP gradually increased the activity of $K_{ACh}$ channels and reached its maximum $40{\sim}50$ sec later following adding ATP. AIKA was not completely reduced but maintained by half even in the presence of NDPK inhibitor. Neither ADP nor a non-hydrolyzable ATP analogue, AMP-PNP can cause AIKA, while a non-specific phosphatase, alkaline phosphatase blocked completely AIKA. PKC antagonists such as sphingosine or tamoxifen, completely blocked AIKA, whereas PKC catalytic domain increased AIKA. Taken together, it is suggested that the PKC-mediated phosphorylation is partly involved in AIKA.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.4
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• pp.377-384
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• 2017

Activation of protein kinase C (PKC) is closely linked with endothelial dysfunction. However, the effect of $PKC{\beta}II$ on endothelial dysfunction has not been characterized in cultured endothelial cells. Here, using adenoviral $PKC{\beta}II$ gene transfer and pharmacological inhibitors, the role of $PKC{\beta}II$ on endothelial dysfucntion was investigated in cultured endothelial cells. Phorbol 12-myristate 13-acetate (PMA) increased reactive oxygen species (ROS), p66shc phosphorylation, intracellular adhesion molecule-1, and monocyte adhesion, which were inhibited by $PKC{\beta}i$ (10 nM), a selective inhibitor of $PKC{\beta}II$. PMA increased the phosphorylation of CREB and manganese superoxide dismutase (MnSOD), which were also inhibited by $PKC{\beta}i$. Gene silencing of CREB inhibited PMA-induced MnSOD expression, suggesting that CREB plays a key role in MnSOD expression. Gene silencing of $PKC{\beta}II$ inhibited PMA-induced mitochondrial ROS, MnSOD, and ICAM-1 expression. In contrast, overexpression of $PKC{\beta}II$ using adenoviral $PKC{\beta}II$ increased mitochondrial ROS, MnSOD, ICAM-1, and p66shc phosphorylation in cultured endothelial cells. Finally, $PKC{\beta}II$-induced ICAM-1 expression was inhibited by Mito-TEMPO, a mitochondrial ROS scavenger, suggesting the involvement of mitochondrial ROS in PKC-induced vascular inflammation. Taken together, the results suggest that $PKC{\beta}II$ plays an important role in PMA-induced endothelial dysfunction, and that the inhibition of $PKC{\beta}II$-dependent p66shc signaling acts as a therapeutic target for vascular inflammatory diseases.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.7
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• pp.958-963
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• 2006

The effect of ginsenosides (GS) on germ cell proliferation was evaluated with a chicken ovarian germ-somatic cell coculture model and the mechanism involving protein kinase C (PKC) pathway was investigated. Ovarian cells were cultured in serum-free McCoy's 5A medium and challenged with GS alone or in combinations with PKC activator (phorbol 12-myristate 13-acetate, PMA) or inhibitor ($H_7$) for 48 h. The number of germ cells was counted and the proliferating cells were identified by immunocytochemistry of proliferating cell nuclear antigen (PCNA). Results showed that GS significantly increased germ cell proliferation and this stimulating effect was further increased by PMA, but inhibited by H7, in a dose-dependent manner. Moreover, GS-elevated PCNA expression and the PCNA -labeling index of germ cells displayed similar changes with the increased numbers of germ cells. These results indicated that GS stimulated proliferation of ovarian germ cells with involvement of the PKC-mediated system.

• BMB Reports
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• v.45 no.11
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• pp.659-664
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• 2012

Extracellular superoxide dismutase (EC-SOD) overexpression modulates cellular responses such as tumor cell suppression and is induced by $IFN{\gamma}$. Therefore, we examined the role of EC-SOD in $IFN{\gamma}$-mediated tumor cell suppression. We observed that the dominant-negative protein kinase C delta ($PKC{\delta}$) suppresses $IFN{\gamma}$-induced EC-SOD expression in both keratinocytes and melanoma cells. Our results also showed that $PKC{\delta}$-induced EC-SOD expression was reduced by pretreatment with a PKC-specific inhibitor or a siRNA against $PKC{\delta}$. $PKC{\delta}$-induced EC-SOD expression suppressed cell proliferations by the up-regulation of p21 and Rb, and the downregulation of cyclin A and D. Finally, we demonstrated that increased expression of EC-SOD drastically suppressed lung melanoma proliferation in an EC-SOD transgenic mouse via p21 expression. In summary, our findings suggest that $IFN{\gamma}$-induced EC-SOD expression occurs via activation of $PKC{\delta}$. Therefore, the upregulation of EC-SOD may be effective for prevention of various cancers, including melanoma, via cell cycle arrest.