• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.22.2-22.2
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• 2008

• BMB Reports
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• v.36 no.4
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• pp.421-425
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• 2003

The serine/threonine protein kinase family is a large and diverse group of enzymes that are involved in the regulation of multiple cellular pathways. Elevated kinase activity has been implicated in many diseases and frequently targeted for the development of pharmacological inhibitors. Therefore, non-radioactive antibody-based kinase assays that allow high throughput screening of compound libraries have been developed. However, they require a generation of antibodies against the phosphorylated form of a specific substrate. We report here a time-resolved fluorescence assay platform that utilizes a commercially-available generic anti-phosphothreonine antibody and permits assaying kinases that are able to phosporylate threonin residues on protein substrates. Using this approach, we developed an assay for Cdc7/Dbf4 kinase activity, determined the $K_m$ for ATP, and identified rottlerin as a non-ATP competitive inhibitor of this enzyme.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.3
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• pp.188-195
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• 2016

Neutrophils and lymphocytes are essential inflammatory cells in the pathogenesis of allergy. In this study, we evaluated the role of house dust mite (HDM) in the interaction between allergic lymphocytes and neutrophils. The extract of Dermatophagoides pteronissinus (DP) showed a stronger anti-apoptotic impact on neutrophil apoptosis in the coculture of allergic neutrophils with allergic lymphocytes when compared with that in allergic neutrophils alone. DP increased IL-6, IL-8, MCP-1, and GM-CSF in allergic lymphocytes, and the increased cytokines were inhibited by rottlerin-an inhibitor of the protein kinase C (PKC) ${\delta}$, as well as by SB202190-a p38 MAPK inhibitor. DP activated p38 MAPK in a time-dependent manner. The activation of p38 MAPK was suppressed by PAR2i, which is a protease-activated receptor (PAR) 2 inhibitor, and rottlerin. Both aprotinin-a serine protease inhibitor-and E64-a cysteine protease inhibitor-were not effective on cytokine secretion of lymphocytes. These results, despite increased cytokines in allergic lymphocytes via DP, did not show any differences between asthma and allergic rhinitis. Molecules, including cytokines, released by DP in lymphocytes inhibited the migration of neutrophils. This finding may further elucidate the pathogenic mechanism of allergic diseases due to HDM.

• Biomolecules & Therapeutics
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• v.13 no.4
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• pp.251-255
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• 2005

In the present study, we tried to investigate whether protein kinase C (PKC) activator, phorbol 12-Myristate 13-Acetate (PMA), and PKC inhibitors, $G\"{o}-6976$, Ro-31-8220 and rottlerin significantly affect basal mucin relesed from cultured airway goblet cells. Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled with $^3H$-glucosamine for 24 hr and chased for 30 min in the presence of each agent to assess the effects on $^3H$-mucin release. The results were as follows: (1) PMA increased mucin release from cultured HTSE cells, during 30 min of treatment period; (2) However, $G\"{o}-6976$, Ro-31-8220 and rottlerin did not significantly affect mucin release, during 30 min of treatment period. This finding suggests, at least in part, that PKC might playa minor role in the signaling pathways involved in basal - physiological or constitutive - mucin release from airway goblet cells, although further studies are needed.

• BMB Reports
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• v.40 no.1
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• pp.130-134
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• 2007

Haptoglobin (Hp) is a glycoprotein that is produced by hepatic cells and secreted into the circulation. While studying the physiologic functions of Hp, we found that Hp synthesized in THP-1 monocytic cells was largely retained within cells, although Hp is considered a secretory protein. To investigate the molecular mechanism on Hp secretion in THP-1 cells, in the present study, we examined the effect of protein kinase C (PKC) on Hp secretion. When several inhibitors of PKC isoforms were tested, only Rottlerin, a specific inhibitor of PKC-$\delta$, completely blocked Hp secretion from cells to culture medium. To confirm the role of PKC-$\delta$ in Hp secretion, Hp-overexpressing COS7 cells were transiently transfected with a wild-type or a dominantnegative mutant of the PKC-$\delta$ gene. Mutant PKC-$\delta$ significantly inhibited Hp secretion, whereas the wild-type gene slightly increased Hp secretion. These results demonstrate that the PKC-$\delta$ signal is involved in Hp secretion.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.87.2-87.2
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• 2008

• 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.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.4
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• pp.1177-1182
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• 2012

Protein kinase C (PKC) has been implicated in carcinogenesis and displays variable expression profiles during cancer progression. Studies of dietary phytochemicals on cancer signalling pathway regulation have been conducted to search for potent signalling regulatory agents. The present study was designed to evaluate any suppressive effect of maslinic acid on PKC expression in human B-lymphoblastoid cells (Raji cells), and to identify the PKC isoforms expressed. Effects of maslinic acid on PKC activity were determined using a PepTag$^{(R)}$ assay for non-radioactive detection of PKC. The highest expression in Raji cells was obtained at 20 nM PMA induced for 6 hours. Suppressive effects of maslinic acid were compared with those of four PKC inhibitors (H-7, rottlerin, sphingosine, staurosporine) and two triterpenes (oleanolic acid and ursolic acid). The $IC_{50}$ values achieved for maslinic acid, staurosporine, H-7, sphingosine, rottlerin, ursolic acid and oleanolic acid were 11.52, 0.011, 0.767, 2.45, 5.46, 27.93 and $39.29\;{\mu}M$, respectively. Four PKC isoforms, PKC ${\beta}I$, ${\beta}II$, ${\delta}$, and ${\zeta}$, were identified in Raji cells via western blotting. Maslinic acid suppressed the expression of PKC ${\beta}I$, ${\delta}$, and ${\zeta}$ in a concentration-dependent manner. These preliminary results suggest promising suppressive effects of maslinic acid on PKC activity in Raji cells. Maslinic acid could be a potent cancer chemopreventive agent that may be involved in regulating many downstream signalling pathways that are activated through PKC receptors.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.10
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• pp.5687-5692
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• 2013

Type 2 diabetes mellitus (T2DM) has contributed to advanced breast cancer development over the past decades. However, the mechanism underlying this contribution is poorly understood. In this study, we determined that high glucose enhanced proteasome activity was accompanied by enhanced proliferation, migration and invasion, as well as suppressed apoptosis, in human breast cancer MCF-7 cells. Proteasome inhibitor bortezomib (BZM) pretreatment mitigated high glucose-induced MCF-7 cell growth and invasion. Furthermore, high glucose increased protein kinase C delta ($PKC{\delta}$)-phosphorylation. Administration of the specific $PKC{\delta}$ inhibitor rottlerin attenuated high glucose-stimulated cancer cell growth and invasion. In addition, $PKC{\delta}$ inhibition by both rottlerin and $PKC{\delta}$ shRNA significantly suppressed high glucose-induced proteasome activity. Our results suggest that $PKC{\delta}$-dependent ubiquitin proteasome system activation plays an important role in high glucose-induced breast cancer cell growth and metastasis.

• Molecules and Cells
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• v.42 no.6
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• pp.470-479
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• 2019

Interstitial cells of Cajal (ICCs) are pacemaker cells that exhibit periodic spontaneous depolarization in the gastrointestinal (GI) tract and generate pacemaker potentials. In this study, we investigated the effects of ghrelin and motilin on the pacemaker potentials of ICCs isolated from the mouse small intestine. Using the whole-cell patch-clamp configuration, we demonstrated that ghrelin depolarized pacemaker potentials of cultured ICCs in a dose-dependent manner. The ghrelin receptor antagonist [D-Lys] GHRP-6 completely inhibited this ghrelin-induced depolarization. Intracellular guanosine 5'-diphosphate-${\beta}$-S and pre-treatment with $Ca^{2+}$-free solution or thapsigargin also blocked the ghrelin-induced depolarization. To investigate the involvement of inositol triphosphate ($IP_3$), Rho kinase, and protein kinase C (PKC) in ghrelin-mediated pacemaker potential depolarization of ICCs, we used the $IP_3$ receptor inhibitors 2-aminoethoxydiphenyl borate and xestospongin C, the Rho kinase inhibitor Y-27632, and the PKC inhibitors staurosporine, Go6976, and rottlerin. All inhibitors except rottlerin blocked the ghrelin-induced pacemaker potential depolarization of ICCs. In addition, motilin depolarized the pacemaker potentials of ICCs in a similar dose-dependent manner as ghrelin, and this was also completely inhibited by [D-Lys] GHRP-6. These results suggest that ghrelin induced the pacemaker potential depolarization through the ghrelin receptor in a G protein-, $IP_3$-, Rho kinase-, and PKC-dependent manner via intracellular and extracellular $Ca^{2+}$ regulation. In addition, motilin was able to depolarize the pacemaker potentials of ICCs through the ghrelin receptor. Therefore, ghrelin and its receptor may modulate GI motility by acting on ICCs in the murine small intestine.