• Journal of Life Science
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• v.20 no.10
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• pp.1451-1457
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• 2010

Serotonin (5-hydroxytryptamine, 5-HT) is an important mediator of cell-cell signaling in neuronal systems. The serotonin transporter (SERT) on the plasma membrane controls the extracellular 5-HT level by reuptake of released 5-HT from the synaptic cleft, but the underlying regulation mechanism is unclear. Here, we used the yeast two-hybrid system to identify the specific binding protein(s) that interacts with the carboxyl (C)-terminal region of SERT and found a specific interaction with protein kinase C-$\varepsilon$ (PKC-$\varepsilon$), a PKC isotype that is characterized as a calcium-independent and phorbol ester/diacylglycerol-sensitive serine/threonine kinase. PKC-$\varepsilon$ bound to the tail region of SERT but not to other members of the $Na^+/Cl^-$ dependent SLC6 gene family in the yeast two-hybrid assay. The C-terminal region of PKC-$\varepsilon$ is essential for interaction with SERT. In addition, these proteins showed specific interactions in the glutathione S-transferase (GST) pull-down assay. PKC-$\varepsilon$ phosphorylated the peptide of the SERT amino (N)-terminus in vitro. These results suggest that the phosphorylation of SERT by PKC-$\varepsilon$ may regulate SERT activity in plasma membrane.

• 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.

• Journal of Life Science
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• v.10 no.5
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• pp.456-466
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• 2000

Aquaperin 4 (AQP4) is the mercurial water channel expressed abundantly in brain, especially the region related with cerebrospinal fluid reabsorption and osmoregulation. The primary structure of AQP4 water channel was elucidated but the molecular mechanism of AQP4 channel regulation is still unknown. To investigate the possible regulation of AQP4 water channel by phosphorylation via various protein kinases, osmotic water permeability of AQP4 expressed in Xenopus oocytes was measured by videomicroscopy technique. Forskolin (10 $\mu$M) did not affect osmotic water permeability of oocytes injected with AQP4 cRNA, excluding the regulation of AQP4 water cnannel by protein kinase A. Osmotic water permeability (P아래첨자) of AQP4-expressed oocytes was ingibited by the pretreatmeat of BAPTA/AM (up to 500$\mu$M), an intracellular Ca윗첨자 chelator, and calmidazolium (100$\mu$M), a specific Ca윗첨자/calmodulin antagonist, in a dose-dependent manner. The inhibition of osmotic water permeability (P아래첨자) by the calmidazolium treatment was completely reversed by the addition of calyculin A (0.1$\mu$M), a nonspecific phosphatase inhibitor. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C activator, had biphasic effects on osmotic water permeability in AQP4 cRNA injected oocytes depending on its concentration; 21% increase by 100 nM PMA, 35% decrease by 1$\mu$M PMA. These effects were reversed with 2$\mu$M staurosporine, a nonspecific PKC inhibitor. These results suggest that phosphorylation of AQP4 water channel by Ca윗첨자/calmodulin kinase and protein kinase C might regulate the osmotic water permeability.

• Archives of Plastic Surgery
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• v.34 no.1
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• pp.8-12
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• 2007

Purpose: Protein tyrosine kinase(PTK), protein kinase C(PKC), oxidase, as a mediator, have been known to take a role in signal transduction pathway of angiogenesis. The authors confirmed that PKC is the most noticeable mediator for abnormal proliferation of vascular endothelial cells through in vitro study model using the inhibitors, targeting the formation of three co-enzymes. In this study, we would investigate which isoform of PKC play an important role in abnormal angiogenesis of vascular endothelial cell. Methods: In 96 well plates, $10^4$ HUVECs(human umbilical vein endothelial cells) were evenly distributed. Two groups were established; the control group without administration of DMH(1,2-dimethylhydrazine) and the DMH group with administration of $7.5{\times}10^{-9}M$ DMH. RNA was extracted from vascular endothelial cell of each group and expression of the PKC isoform was analyzed by RT-PCR(reverse transcriptase-polymerase chain reaction) method. Results: RT-PCR analysis showed that $PKC{\alpha}$, $-{\beta}I$, $-{\beta}II$, $-{\eta}$, $-{\mu}$ and $-{\iota}$ were expressed in vascular endothelial cells of each group. DMH incresed the expression of $PKC{\alpha}$ and $PKC{\mu}$, and decreased $PKC{\beta}I$, $PKC{\beta}II$ expression dominantly. Conclusion: Based on the result of this study, it was suggested that $PKC{\alpha}$ and $PKC{\mu}$ may have significant role in abnormal proliferation of vascular endothelial cell.

• BMB Reports
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• v.33 no.2
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• pp.103-111
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• 2000

Phosphorylation of the eukaryotic elongation factor 2 (eEF-2) blocks the elongation step of translation and stops overall protein synthesis. Although the overall rate of protein synthesis in mitosis reduces to 20% of that in S phase, it is unclear how the protein translation procedure is regulated during the cell cycle, especially in the stage of peptide elongation. To delineate the regulation of the elongation step through eEF-2 function, the changes in phosphorylation of eEF-2, and in activity of corresponding $Ca^{2+}$/calmodulin (CaM)-dependent protein kinase III (CaMK-III) during the cell cycle of NIH 3T3 cells, were determined. The in vivo level of phosphorylated eEF-2 showed an 80% and 40% increase in the cells arrested at G1 and M, respectively. The activity of CaMK-III also changed in a similar pattern, more than a 2-fold increase when arrested at G1 and M. The activity change of the kinase during one turn of the cell cycle also demonstrated the activation at G1 and M phases. The activity change of cAMP-dependent protein kinase (PKA) was reciprocal to that of CaMK-III. These results indicated: (1) the activity of CaMK-III was cell cycle-dependent and (2) the level of eEF-2 phosphorylation followed the kinase activity change. Therefore, the elongation step of protein synthesis might be cell cycle dependently regulated.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.3
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• pp.211-217
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• 2012

Recent studies have demonstrated that nitric oxide (NO) activates transient receptor potential vanilloid subtype 1 (TRPV1) via S-nitrosylation of the channel protein. NO also modulates various cellular functions via activation of the soluble guanylyl cyclase (sGC)/protein kinase G (PKG) pathway and the direct modification of proteins. Thus, in the present study, we investigated whether NO could indirectly modulate the activity of TRPV1 via a cGMP/PKG-dependent pathway in cultured rat dorsal root ganglion (DRG) neurons. NO donors, sodium nitroprusside (SNP) and S-nitro-N-acetylpenicillamine (SNAP), decreased capsaicin-evoked currents ($I_{cap}$). NO scavengers, hemoglobin and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO), prevented the inhibitory effect of SNP on $I_{cap}$. Membrane-permeable cGMP analogs, 8-bromoguanosine 3', 5'-cyclic monophosphate (8bromo-cGMP) and 8-(4chlorophenylthio)-guanosine 3',5'-cyclic monophosphate (8-pCPT-cGMP), and the guanylyl cyclase stimulator YC-1 mimicked the effect of SNP on $I_{cap}$. The PKG inhibitor KT5823 prevented the inhibition of $I_{cap}$ by SNP. These results suggest that NO can downregulate the function of TRPV1 through activation of the cGMP/PKG pathway in peripheral sensory neurons.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.1
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• pp.11-18
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• 1999

Nuclear factor $_{\kappa}B\;(NF-_{\kappa}B)$ activation is modulated by various protein kinases. Activation of $NF-_{\kappa}B$ is known to be important in the regulation of cell viability. The present study investigated the effect of inhibitors of protein tyrosine kinase (PTK), protein kinase C (PKC) and protein kinase A (PKA) on $NF-_{\kappa}B$ activity and the viability of bovine cerebral endothelial cells (BCECs). In serum-deprivation-induced BCEC death, low doses of $TNF{\alpha}$ showed a protective effect. $TNF{\alpha}$ induced $NF-_{\kappa}B$ activation within 4 h in serum-deprivation. PTK inhibitors (herbimycin A and genistein) and PKC inhibitor (calphostin C) prevented $NF-_{\kappa}B$ activation stimulated by $TNF{\alpha}.$ Likewise, these inhibitors prevented the protective effect of $TNF{\alpha}.$ In contrast to $TNF{\alpha}-stimulated\;NF-_{\kappa}B$ activity, basal $NF-_{\kappa}B$ activity of BCECs in media containing serum was suppressed only by calphostin C, but not by herbimycin A. As well BCEC death was also induced only by calphostin C in serum-condition. H 89, a PKA inhibitor, did not affect the basal and $TNF{\alpha}-stimulated\;NF-_{\kappa}B$ activities and the protective effect of $TNF{\alpha}$ on cell death. These data suggest that modulation of $NF-_{\kappa}B$ activation could be a possible mechanism for regulating cell viability by protein kinases in BCECs.

• BMB Reports
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• v.44 no.9
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• pp.559-565
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• 2011

Protein kinase C (PKC) is a central enzyme that modulates numerous biological functions. For this reason, specific PKC inhibitors/activators are required to study PKC-related signaling mechanisms. To date, although many PKC inhibitors have been developed, they are limited by poor selectivity and nonspecificity. In this review, we focus on the nonspecific actions of PKC inhibitors on cardiovascular ion channels in addition to their PKC-inhibiting functions. The aim of this paper is to urge caution when using PKC inhibitors to block PKC function. This information may help to better understand PKC-related physiological/biochemical studies.

• Korean Journal of Poultry Science
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• v.23 no.3
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• pp.113-119
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• 1996

A series of experiments were conducted to investigate the role of protein kinase C (PKC) as a second messenger in vasoactive intestinal peptide (VIP) mediated prolactin secretion. Primary pituitary cells (106 cells/treatment) were separated from laying hens and incubated in M-199 with 5% chicken serum and 5% fetal calf serum. The VIP(0.1 $\pi$M) treatment enhanced prolactin Secretion into media upto 9-fold during 48-h incubation. The phorbol 12-myristate 13-acetate (PMA), a PKG agonist, increased prolactin secretion upto 2-fold at 0.1 nM PMA (P<0.01), and the prolactin secretion was not significantly higher than this concentration. Staurosporine (ST; 1.0$\pi$M) a PKC antagonist, decreased by 70% of 0.1 $\pi$M VIP-stimulated prolactin secretion and by 48% of 10 ${\mu}$M PMA-stimulated prolactin secretion (P<0.01). However, pituitary cell prolactin content did not differ in any treatment (P>0.05). In conclusion, these results indicate that the PKC second messenger system is involved in VIP-stimulated prolactin release in chicken primary pituitary cell culture.

• 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.