• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.7
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• pp.929-937
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• 2016

The purpose of this study was to investigate the effect of Acanthopanax senticosus extract (ASE) (ethanol : DW=1:1, v/v) on inhibition of type 2 diabetes using an OLETF rat model via regulation of HbA1c and AGEs levels. Supplementation with ASE 0.1% and 0.5% effectively lowered levels of glucose, insulin, oral glucose tolerance test, and Homa-insulin resistance, suggesting reduced insulin resistance. Blood levels of HbA1c and AGEs were significantly reduced in a dose-dependent manner. As oxidative stress plays a key role in accelerating production of HbA1c and AGEs, which worsen symptoms of type 2 diabetes, levels of malonaldehyde and pro-inflammatory cytokines were measured. Lipid peroxidation in both blood and liver tissues was significantly reduced, and induction of pro-inflammatory cytokines interleukin-${\beta}$ and tumor necrosis factor-${\alpha}$, which elevate production of HbA1c and AGEs, was inhibited (P<0.05). To evaluate the possible cellular events after AGEs receptor activation, genetic expression of protein kinase C (PKC)-${\delta}$ and transforming growth factor (TGF)-${\beta}$ was measured by real-time polymerase chain reaction. Supplementation with both ASE 0.1% and 0.5% significantly inhibited mRNA expression of PKC-${\delta}$ and TGF-${\beta}$, indicating that ASE may have beneficial effects on preventing insulin-resistant cells or tissues from progressing to diabetic complications. Taken together, ASE has potential to improve type 2 diabetes by inhibiting insulin resistance and protein glycosylation, including production of HbA1c and AGEs. Anti-oxidative activities of ASE are a main requisite for reducing production of HbA1c and AGEs and are also related to regulation of the PKC signaling pathway, resulting in suppression of TGF-${\beta}$, which increases synthesis of collagen, prostaglandin, and disease-related proteins.

• Journal of Life Science
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• v.24 no.6
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• pp.664-670
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• 2014

In the present study, we investigate the role of V. vulnificus in promoting the inflammation of mouse ileal ephitelium and its related signaling pathways. ICR mice were infected orally with V. vulnificus ($1{\times}10^9CFU$) for 16 h as a representative model of food-borne infection. To find the major portal of entry of V. vulnificus in mouse intestine, we have measured the levels of bacterial colonization in small intestine, colon, spleen, and liver. V. vulnificus appeared to colonize in intestine and colon in the order of ileum >> jejunum> colon, but lack in the duodenum, spleen, and liver. V. vulnificus in ileum caused severe necrotizing enteritis and showed shortened villi heights accompanied by an expanded width and inflammation, compared with the control mice. V. vulnificus induced ileal epithelium inflammation by activating phosphorylation of PKC and membrane translocation of $PKC{\alpha}$. V. vulnificus induced the phosphorylation of ERK and JNK, but did not affect p38 MAPK phosphorylation. Notably, V. vulnificus stimulated the I-${\kappa}B$-dependent phosphorylation of NF-${\kappa}B$ in mouse ileal epithelium. Finally, the ileal infection of V. vulnificus resulted in a significant increase in expression of proinflammatory cytokines and Toll-like receptors, respectively, compared to the control. Collectively, our results indicate that V. vulnificus induces ileal epithelium inflammation by increasing NF-${\kappa}B$ phosphorylation via activation of PKC, ERK, and JNK, which is critical for host defense mechanism in food-borne infection by V. vulnificus.

• Journal of Microbiology and Biotechnology
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• v.12 no.4
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• pp.592-597
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• 2002

The Rkp1/CPC2, a receptor for activated protein kinase C of Schizosaccharomyces pombe, contains seven WD motifs found in the G-protein $\beta$-subunit. A 110-kDa protein was identified to interact with Rkp1/CPC2 by immunoprecipitation and following in vitro binding assay. To examine its kinase activity and binding ability to Rkp1, the $pck1^+$, a PKC homolog of S. pombe, was cloned. Pckl phosphorylated myelin basic protein (MBP) and histone Hl in a phospholipid-dependent and $Ca^{2+}$-independent manner. It was demonstrated that the N-terminal region of Pck1 was responsible for the binding to Rkp1 , thus suggesting that Rkp1 interacted with Pckl to regulate Pckl-mediated signaling in S. pombe.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.6
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• pp.571-578
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• 1999

This study evaluated the effects of PKC activation using phorbol 12-myristate 13-acetate (PMA) and PKC inhibition using the isoquinoline sulfomide derivative H-7 on hemodynamics and glucoregulation in the isolated perfused rat liver. Livers were isolated from fed male Holtzman rats and perfused with Krebs Ringer bicarbonate solution under a constant flow of 50 ml/min at $35^{\circ}C.$ Portal vein pressure, glucose and lactate concentrations in the medium and oxygen consumption rates were continuously monitored by a Grass polygraph, YSI glucose and lactate monitors, and a YSI oxygen monitor, respectively. PMA at concentration of 2 to 200 nM increased the portal vein pressure, glucose and lactate production, but decreased oxygen consumption rate in a dose-dependent fashion. H-7 $(200\;{\mu}M)$ attenuated PMA (50 nM)-induced vasoconstriction $(15.1{\pm}1.36\;vs\;10.56{\pm}1.17\;mmHg),$ glucose production rate $(91.3{\pm}6.15\;vs\;71.8{\pm}2.50\;{\mu}moles/g/hr),$ lactate production rate $(72.4{\pm}6.82\;vs\;53.6{\pm}4.82\;{\mu}moles/g/hr)$ and oxygen consumption rate $(33.7{\pm}1.41\;vs\;27.9{\pm}1.75\;{\mu}l/g/min).$ The effects of PMA were blocked either by addition of verapamil $(9\;{\mu}M)$ or perfusion with $Ca^{2+}-free$ KRB. These results suggest that the hemodynamic and glucoregulatory changes in the perfused rat liver are mediated by protein kinase C activation and require $Ca^{2+}$ influx from the extracellular fluid.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.6
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• pp.363-368
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• 2003

To gain insight on the role of pro-inflammatory cytokines in the pathogenesis and treatment of rheumatoid arthritis (RA), the phorbol 12-myristate 13-acetate (PMA)-induced IL-6 gene expression and the effect of caffeic acid phenethyl ester (CAPE) on the PMA-induced IL-6 gene expression were investigated in human fibroblast-like synoviocytes (FLSs). Synovial tissue samples were obtained from rheumatoid arthritis patients, and FLSs were isolated. The cells were stimulated with PMA (100 nM) for 6 hrs to induce IL-6 gene. The cells were pretreated with CAPE (20, 50, $100{\mu}M$) prior to PMA treatment. PMA increased IL-6 RNA expression, binding activities of transcription factors ($NF-{\kappa}B$, AP-1) to IL-6 promoter, and IL-6 promoter activity. However, CAPE inhibited PMA-induced IL-6 mRNA expression in dose-dependent manner, and also inhibited the increased binding activities of transcription factors to IL-6 promoter and IL-6 promoter activity. These results suggest that CAPE might regulate PKC-mediated IL-6 expression and inflammatory reactions in RA.

• BMB Reports
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• v.45 no.7
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• pp.414-418
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• 2012

Triglycerides (TG) are implicated in the development of atherosclerosis through formation of foam cells and induction of macrophage cell death. In this study, we report that addition of exogenous TG induced cell death in phorbol 12-myristate 13-acetate-differentiated THP-1 human macrophages. TG treatment induced a dramatic decrease in interleukin-$1{\beta}$ (IL-$1{\beta}$) mRNA expression in a dose- and time-dependent manner. The expression of granulocyte macrophage colony-stimulating factor and platelet endothelial cell adhesion molecule remained unchanged. To identify signaling pathways involved in TG-induced downregulation of IL-$1{\beta}$, we added p38 MAPK, protein kinase C (PKC) or c-Raf1 specific inhibitors. We found that inhibition of p38 MAPK alleviated the TG-induced downregulation of IL-$1{\beta}$, whereas inhibition of PKC and c-Raf1 had no effect. This is the first report showing decreased IL-$1{\beta}$ expression during TG-induced cell death in a human macrophage line. Our results suggest that downregulation of IL-$1{\beta}$ expression by TG-treated macrophages may play a role during atherogenesis.

• Molecules and Cells
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• v.39 no.3
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• pp.229-241
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• 2016

We have previously reported the role of miR-326-HDAC3 loop in anti-cancer drug-resistance. CAGE, a cancer/testis antigen, regulates the response to anti-cancer drug-resistance by forming a negative feedback loop with miR-200b. Studies investigating the relationship between CAGE and HDAC3 revealed that HDAC3 negatively regulated the expression of CAGE. ChIP assays demonstrated the binding of HDAC3 to the promoter sequences of CAGE. However, CAGE did not affect the expression of HDAC3. We also found that EGFR signaling regulated the expressions of HDAC3 and CAGE. Anti-cancer drug-resistant cancer cell lines show an increased expression of $pEGFR^{Y845}$. HDAC3 was found to negatively regulate the expression of $pEGFR^{Y845}$. CAGE showed an interaction and co-localization with EGFR. It was seen that miR-326, a negative regulator of HDAC3, regulated the expression of CAGE, $pEGFR^{Y845}$, and the interaction between CAGE and EGFR. miR-326 inhibitor induced the binding of HDAC3 to the promoter sequences in anti-cancer drug-resistant $Malme3M^R$ cells, decreasing the tumorigenic potential of $Malme3M^R$ cells in a manner associated with its effect on the expression of HDAC3, CAGE and $pEGFR^{Y845}$. The down-regulation of HDAC3 enhanced the tumorigenic, angiogenic and invasion potential of the anti-cancer drug-sensitive Malme3M cells in CAGE-dependent manner. Studies revealed that $PKC{\delta}$ was responsible for the increased expression of $pEGFR^{Y845}$ and CAGE in $Malme3M^R$ cells. CAGE showed an interaction with $PKC{\delta}$ in $Malme3M^R$ cells. Our results show that HDAC3-CAGE axis can be employed as a target for overcoming resistance to EGFR inhibitors.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.6
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• pp.667-674
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• 2017

Angiotensin II (Ang II) is metabolized from N-terminal by aminopeptidases and from C-terminal by Ang converting enzyme (ACE) to generate several truncated angiotensin peptides (Angs). The truncated Angs have different biological effects but it remains unknown whether Ang-(4-8) is an active peptide. The present study was to investigate the effects of Ang-(4-8) on hemodynamics and atrial natriuretic peptide (ANP) secretion using isolated beating rat atria. Atrial stretch caused increases in atrial contractility by 60% and in ANP secretion by 70%. Ang-(4-8) (0.01, 0.1, and $1{\mu}M$) suppressed high stretch-induced ANP secretion in a dose-dependent manner. Ang-(4-8) ($0.1{\mu}M$)-induced suppression of ANP secretion was attenuated by the pretreatment with an antagonist of Ang type 1 receptor ($AT_1R$) but not by an antagonist of $AT_2R$ or $AT_4R$. Ang-(4-8)-induced suppression of ANP secretion was attenuated by the pretreatment with inhibitor of phospholipase (PLC), inositol triphosphate ($IP_3$) receptor, or nonspecific protein kinase C (PKC). The potency of Ang-(4-8) to inhibit ANP secretion was similar to Ang II. However, Ang-(4-8) $10{\mu}M$ caused an increased mean arterial pressure which was similar to that by 1 nM Ang II. Therefore, we suggest that Ang-(4-8) suppresses high stretch-induced ANP secretion through the $AT_1R$ and $PLC/IP_3/PKC$ pathway. Ang-(4-8) is a biologically active peptide which functions as an inhibition mechanism of ANP secretion and an increment of blood pressure.

• BMB Reports
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• v.30 no.3
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• pp.182-187
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• 1997

The NADPH oxidase of phagocytes catalyzes the reduction of oxygen to $O_2^-$ at the expense of NADPH. The enzyme is dormant in resting neutrophils and becomes activated on stimulation. During activation, $p47^{phox}\;(\underline{ph}agocyte\;\underline{ox}idase\;factor)$, a cytosolic oxidase subunit, becomes extensively phosphorylated at a number of serines located between S303-S379. Oxidase activation can also be achieved by the addition of phosphorylated recombinant $p47^{phox}$ by protein kinase C in the cell-free system in the presence of $GTP{\gamma}S$. The cell-free activation is inhibited by wortmannin and LY294002. specific inhibitors of phosphatidylinositol 3kinase (PI 3-kinasel) These results indicate that PI 3-kinase may playa pivotal role in the activation of NADPH oxidase.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.86.2-86.2
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• 2008