• The Journal of Korean Physical Therapy
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• v.20 no.3
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• pp.61-68
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• 2008

Purpose: Protein kinase C (PKC) is a member of a family of serine/threonine kinases that are activated by diacylglycerol (DG) and PKC stimulants. PKC play a key role in signal transduction, including muscle contraction, cell migration, apoptosis, cell proliferation and differentiation. However, the mechanism relating mitogen-activated protein kinases (MAPKs) and PKC, especially in the volume-dependent hypertensive state, remains unclear. Methods: In the present study, I investigated the relationship between PKC and MAPKs for isometric contraction, PKC translocation, and enzymatic activity from normotensive sham-operated rats (NSR) and aldosterone-analogue deoxycorticosterone acetate (DOCA) hypertensive rats (ADHR). Results: Systolic blood pressure was significantly increased in ADHR than in NSR. Physiological salt solution (PSS)-induced resting tension and the intracellular $Ca^{2+}$ concentration ([$Ca^{2+}{_i}$]) were different in the ADHR and NSR. The expression of PKC$\alpha$, PKC$\beta$II, PKC$\delta$, PKC$\varepsilon$ and PKC$\xi$ were different between the cytoplasmic and membranous fractions. However, expression of the PKC isoforms did not differ for the ADHR and NSR. The use of 12-deoxyphorbol 13-isobutyrate (DPB, a PKC stimulant) induced isometric contraction in $Ca^{2+}$-free medium, which was diminished in muscle strips from ADHR as compared to NSR. Increased vasoconstriction and phosphorylation induced by the use of 1 ${\mu}$M DPB were inhibited by treatment with 10 ${\mu}$M PD098059 and 10 ${\mu}$M SB203580, inhibitors of extracellular-regulated protein kinase 1/2 (ERK1/2) and p38 MAPK from ADHR, respectively. Conclusion: These results suggest that the development of aldosterone analogue-induced hypertension is associated with an altered blood pressure, resting tension, [$Ca^{2+}{_i}$], and that the $Ca^{2+}$-independent contraction evoked by PKC stimulants is due to the activation of ERK1/2 and p38 MAPK in volume-dependent hypertension. Therefore, it is suggested that PKC activity affects volume-dependent hypertension and the need to develop cardiovascular disease-specialized physical therapy.

• BMB Reports
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• v.31 no.4
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• pp.350-354
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• 1998

To understand the role of protein kinase C (PKC) in the regulation of chondrogenesis, we examined proteins which are phosphorylated by PKC. Stage 23/24 chick embryo wing mesenchymes were micromass-cultured to induce chondrogenesis and cell extracts were phosphorylated in a condition that activates PKC. Several proteins including 63 and 66 kDa proteins were phosphorylated. The 66 kDa protein was phosphorylated only in the presence of phorbol 12-myristate 13-acetate (PMA) and phosphatidylserine CPS), and the phosphorylation was almost completely diminished by bisindolylmaleimide, a PKC inhibitor. In addition, partially purified PKC increased the phosphorylation of the 66 kDa protein. Treatment of cultures with lysophosphatidylcholine (LPC) promoted chondrogenesis and phosphorylation of 66 kDa protein, while PMA and thymeleatoxin inhibited both of the two events. Our results suggest that the 66 kDa protein is a putative substrate of PKC, and phosphorylation of the 66 kDa protein, probably by $PKC\alpha$ is required for chondrogenesis.

• Molecules and Cells
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• v.39 no.3
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• pp.266-279
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• 2016

The mechanism by which 12-O-tetradecanoylphorbol-13-acetate (TPA) bypasses cellular senescence was investigated using human diploid fibroblast (HDF) cell replicative senescence as a model. Upon TPA treatment, protein kinase C (PKC) ${\alpha}$ and $PKC{\beta}1$ exerted differential effects on the nuclear translocation of cytoplasmic pErk1/2, a protein which maintains senescence. $PKC{\alpha}$ accompanied pErk1/2 to the nucleus after freeing it from $PEA-15pS^{104}$ via $PKC{\beta}1$ and then was rapidly ubiquitinated and degraded within the nucleus. Mitogen-activated protein kinase docking motif and kinase activity of $PKC{\alpha}$ were both required for pErk1/2 transport to the nucleus. Repetitive exposure of mouse skin to TPA downregulated $PKC{\alpha}$ expression and increased epidermal and hair follicle cell proliferation. Thus, $PKC{\alpha}$ downregulation is accompanied by in vivo cell proliferation, as evidenced in 7, 12-dimethylbenz(a)anthracene (DMBA)-TPA-mediated carcinogenesis. The ability of TPA to reverse senescence was further demonstrated in old HDF cells using RNA-sequencing analyses in which TPA-induced nuclear $PKC{\alpha}$ degradation freed nuclear pErk1/2 to induce cell proliferation and facilitated the recovery of mitochondrial energy metabolism. Our data indicate that TPA-induced senescence reversal and carcinogenesis promotion share the same molecular pathway. Loss of $PKC{\alpha}$ expression following TPA treatment reduces pErk1/2-activated SP1 biding to the $p21^{WAF1}$ gene promoter, thus preventing senescence onset and overcoming G1/S cell cycle arrest in senescent cells.

• Korean Journal of Veterinary Research
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• v.39 no.6
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• pp.1073-1080
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• 1999

Previous studies suggested that the inhibition of thyroxine ($T_4$) release by ${\alpha}_1$-adrenoceptor and muscarinic receptor stimulation results in activated protein kinase C (PKC) from mouse and guinea pig thyroids. In the present study, the effect of carbachol, methoxamine, phorbol myristate acetate (PMA), and R59022 on the release of $T_4$ from the mouse, rat, and guinea pig thyroids was compared to clarify the role of PKC in the regulation of the release of $T_4$. The thyroids were incubated in the medium containing the test agents, samples of the medium were assayed for $T_4$ by EIA kits. Forskolin, an adenylate cyclase activator, chlorophenylthio-cAMP sodium, a membrane permeable analog of cAMP, and isobutyl-methylxanthine, a phosphodiesterase inhibitor, like TSH (thyroid stimulating hormone), enhaced the release of $T_4$ from the mouse, rat, and guinea pig thyroids. Methoxamine, an ${\alpha}_1$-adrenoceptor agonist, inhibited the TSH-stimulated release of $T_4$ in mouse, but not rat and guinea pig thyroids. In contrast, carbachol, a muscarinic receptor agonist, inhibited the release of $T_4$ in guinea pig, but not mouse and rat thyroids. These inhibition were reversed by prazosin, an ${\alpha}_1$-adrenoceptor antagonist or atropine, a muscarinic antagonist or $M_1$- and $M_3$-muscarinic antagonists, in mouse or guinea pig thyroids. In addition, staurosporine, a PKC inhibitor, reversed methoxamine or carbachol inhibition of TSH stimulation. Furthermore, PMA, a PKC activator, and R59022, a diacylglycerol (DAG) kinase inhibitor, inhibited the TSH-stimulated release of $T_4$ in mouse, rat, and guinea pig thyroids. These inhibition were blocked by staurosporine. These findings suggest that the activation of receptor or DAG inhibits TSH-stimulated $T_4$ release through a PKC-dependent mechanism in thyroid gland.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.78-78
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• 2003

Inulin, an active component of Chicorium intybus root, has been shown to stimulate the growth of bifidobacteria, and inhibit colon carcinogenesis. NO mediates a number of the host-defense functions of activated macrophages, including antimicrobial and tumoricidal activity. We examined the effect of inulin on the synthesis of NO in RAW 264.7 cells. Inulin alone had no effect, whereas inulin with IFN-ν synergistically increased the NO production and inducible NO synthase (iNOS) expression in RAW 264.7 cells. Synergy between IFN-ν and inulin was mainly dependent on inulin-induced TNF-${\alpha}$ secretion. Also, protein kinase C (PKC)-${\alpha}$ was involved in the inulin-induced NO production. Inulin-mediated NO production was inhibited by the protein tyrosine kinase (PTK) inhibitor, tyrphostin AG126. Since iNOS gene transcriptions have been shown to be under the control of the NF -$\kappa$B/Rel family of transcription factors, we assessed the effect of inulin on NF -$\kappa$B/Rel using an EMSA. Inulin produced strong induction of NF-$\kappa$B/Rel binding, whereas AP-l binding was slightly induced in RAW 264.7 cells. Inulin stimulated phosphorylation and degradation of I$\kappa$B-${\alpha}$. These results suggest that in IFN-ν-primed RAW 264.7 cells inulin might stimulate NO synthesis via activation of PKC-${\alpha}$ and PTK, resulting in the activation of NF-$\kappa$B.

• BMB Reports
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• v.38 no.6
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• pp.639-645
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• 2005

Protein kinase C (PKC) isozymes, a family of serine-threonine kinases, are important regulators of cell proliferation and malignant transformation. Phorbol esters, the prototype PKC activators, cause PKC translocation to the plasma membrane in prostate cancer cells, and trigger an apoptotic response. Studies in recent years have determined that each member of the PKC family exerts different effects on apoptotic or survival pathways. $PKC{\delta}$, one of the novel PKCs, is a key player of the apoptotic response via the activation of the p38 MAPK pathway. Studies using RNAi revealed that depletion of $PKC{\delta}$ totally abolishes the apoptotic effect of the phorbol ester PMA. Activation of the classical $PKC{\alpha}$ promotes the dephosphorylation and inactivation of the survival kinase Akt. Studies have assigned a pro-survival role to $PKC{\varepsilon}$, but the function of this PKC isozyme remains controversial. Recently, it has been determined that the PKC apoptotic effect in androgen-dependent prostate cancer cells is mediated by the autocrine secretion of death factors. $PKC{\delta}$ stimulates the release of $TNF{\alpha}$ from the plasma membrane, and blockade of $TNF{\alpha}$ secretion or $TNF{\alpha}$ receptors abrogates the apoptotic response of PMA. Molecular analysis indicates the requirement of the extrinsic apoptotic cascade via the activation of death receptors and caspase-8. Dissecting the pathways downstream of PKC isozymes represents a major challenge to understanding the molecular basis of phorbol ester-induced apoptosis.

• Journal of Chest Surgery
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• v.36 no.9
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• pp.666-673
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• 2003

Cigarette smoking is the leading cause of the lung cancer. However, mechanism of action underlying the carcinogenesis in the lung still remains to be elucidated. The present study attempted to look into the carcinogenic potential of tobacco-specific nitrosamine, NNK (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone) and the effects of protein kinase C (PKC) isoforms in an immortalized human epithelial cell model. Material and Method: Immortalized human epithelial cells were exposed with NNK and examined for its carcinogenic potential as measured by saturation density, soft-agar colony formation, and cell aggregation assay. The specific isoform of PKCs involved in the cellular transformation was analysed through western blot with monoclonal antibody and measured separately in cytosolic fraction and membrane fraction. Result: Human epithelial cells exposed with NNK showed prominent carcinogenic potential in saturation density, soft agar colony formation, and cell aggregation assay. PKC isoform analysis results are as follows: PKC- $\alpha$ showed significant translocation of protein levels from cytosolic fraction to membrane fraction, as analyzed by immunoblot. PKC- $\varepsilon$ showed a dose-dependent increase of translocation. PKC- λ was not affected by NNK treatment. Conclusion: The study demonstrated that there was a certain specificity in the patterns of isoform induction following chemical carcinogen exposure. Thus, it is suggested that identification of specific isoform be a clue to find target molecules in the carcinogenesis.

• 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.

• Archives of Pharmacal Research
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• v.23 no.5
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• pp.518-524
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• 2000

We examined the modulation of protein kinase C (PKC) subtypes during apoptosis induced by ginsenoside Rh2 (G-Rh2) in human neuroblastoma SK-N-Bl(2) and rat glioma C6Bu-1 cells. Apoptosis induced by C-Rh2 in both cell lines was confirmed, as indicated by DNA fragmentation and in situ strand breaks, and characteristic morphological changes. During apoptosis induced by G-Rh2 in SK-N-BE(2) cells, PKC subtypes $\alpha$, $\beta$ and $\gamma$ were progressively increased with prolonged treatment, whereas PKC $\delta$ increased transiently at 3 and 6 h and PKC $\varepsilon$ was gradually down-regulated after 6 h following the treatment. On the other hand, PKC subtype $\beta$ markedly increased at 24 h when maximal apoptosis was achieved. In C6Bu-l cells, no significant changes in PKC subtypes $\alpha$, $\gamma$, $\delta$, $\varepsilon$ and $\beta$ were observed during apoptosis induced by G-Rh2. These results suggest the evidence for a possible role of PKC subtype in apoptosis induced by G-Rh2 in SK-N-BE(2) cells but not in C6Bu-1 cells, and raise the possibility that G-Rh2 may induce apoptosis via different pathways interacting with or without PKC in different cell types.

• BMB Reports
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• v.42 no.8
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• pp.516-522
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• 2009

SH2D4A, comprising a single SH2 domain, is a novel protein of the SH2 signaling protein family. We have previously demonstrated SH2D4A is expressed ubiquitously in various tissues and is located in the cytoplasm. In this study we investigated the function of SH2D4A in human embryonic kidney (HEK) 293 cells using interaction analysis, cell proliferation assays, and kinase activity detection. SH2D4A was found to directly bind to estrogen receptor $\alpha$ (ER$\alpha$), and prevent the recruitment of phospholipase C-$\gamma$ (PLC-$\gamma$) to ER$\alpha$. Moreover, we observed its inhibitory effects on estrogen-induced cell proliferation, involving the protein kinase C (PKC) signaling pathway. Together, these findings suggested that SH2D4A inhibited cell proliferation by suppression of the ER$\alpha$/PLC-$\gamma$/PKC signaling pathway. SH2D4A may be useful for the development of a new anti-cancer drug acting as an ER signaling modulator.