• Reproductive and Developmental Biology
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• v.28 no.3
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• pp.187-190
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• 2004

Protein kinase C exists as a family of serine/threonine kinases which are broadly classified into three groups as cPKC nPKC and aPKC depending on their cofactor requirements. Previous studies have shown that the role of PKC in the process of mouse oocyte maturation. For example, phorbol 12-myristate 13-acetate which is known as an activator of cPKC and nPKC inhibits germinal vesicle break down and 1st polar body extrusion in maturing oocytes. In this study, the effect of thymeleatoxin, a specific activator of cPKC not nPKC, was tested comparing with PMA to address the roles of cPKC and nPKC during mouse oocyte maturation. Cumulus-oocyte complex were cultured in M16 medium for 6 or 12 hr with each of these PKC activators to investigate the effect of germinal vesicle breakdown (GVBD) or the extrusion of 1st polar body. IC/sup 50/ of GVBD were at concentrations of 50nM in PMA and 400nM in thymeleatoxin and of 1st polar body extrusion were 20nM in PMA and 200nM in thy- meleatoxin. The results suggest that activation of nPKC is more closely related to the inhibition of GVBD and 1st polar body extrusion than activation of cPKC. Additionally, we found that the oocytes inhibited 1st polar body extrusion with PMA or thymeleatoxin were arrested in metaphase I of first meiosis.

• Molecules and Cells
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• v.37 no.10
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• pp.747-752
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• 2014

Protein kinase C (PKC) family members phosphorylate a wide variety of protein targets and are known to be involved in diverse cellular signaling pathways. However, the role of PKC in receptor activator of NF-${\kappa}B$ ligand (RANKL) signaling has remained elusive. We now demonstrate that $PKC{\beta}$ acts as a positive regulator which inactivates glycogen synthase kinase-$3{\beta}$ (GSK-$3{\beta}$) and promotes NFATc1 induction during RANKL-induced osteoclastogenesis. Among PKCs, $PKC{\beta}$ expression is increased by RANKL. Pharmacological inhibition of $PKC{\beta}$ decreased the formation of osteoclasts which was caused by the inhibition of NFATc1 induction. Importantly, the phosphorylation of GSK-$3{\beta}$ was decreased by $PKC{\beta}$ inhibition. Likewise, down-regulation of $PKC{\beta}$ by RNA interference suppressed osteoclast differentiation, NFATc1 induction, and GSK-$3{\beta}$ phosphorylation. The administration of PKC inhibitor to the RANKL-injected mouse calvaria efficiently protected RANKL-induced bone destruction. Thus, the $PKC{\beta}$ pathway, leading to GSK-$3{\beta}$ inactivation and NFATc1 induction, has a key role in the differentiation of osteoclasts. Our results also provide a further rationale for $PKC{\beta}$'s therapeutic targeting to treat inflammation-related bone diseases.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.5
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• pp.259-265
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• 2008

$[Ca^{2+}]_i$ transients by reverse mode of cardiac $Na^+/Ca^{2+}$ exchanger (NCX1) were recorded in fura-2 loaded BHK cells with stable expression of NCX1. Repeated stimulation of reverse NCX1 produced a long-lasting decrease of $Ca^{2+}$ transients ('rundown'). Rundown of NCX1 was independent of membrane $PIP_2$ depletion. Although the activation of protein kinase C (PKC) was observed during the $Ca^{2+}$ transients, neither a selective PKC inhibitor (calphostin C) nor a PKC activator (PMA) changed the degrees of rundown. By comparison, a non-specific PKC inhibitor, staurosporine (STS), reversed rundown in a dose-dependent and reversible manner. The action of STS was unaffected by pretreatment of the cells with calphostin C, PMA, or forskolin. Taken together, the results suggest that the stimulation of reverse NCX1 by STS is independent of PKC and/or PKA inhibition.

• Reproductive and Developmental Biology
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• v.30 no.2
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• pp.75-79
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• 2006

The developmental regulation of the preimplantation mammalian embryos is a fundamental step for preparing the implantation and it may be regulated by several autocrine and paracrine factors including platelet-activating factor. PAF improved the embryonic survival and implantation but its role during blastocyst development is still largely unknown. In this study, the effects and the possible pathway of PAF on developmental regulation of blastocyst to hatching stage were investigated. Developmental pattern in hatching embryo was a concentration-response curve showing maximal activity at 1 nM PAF, with decreasing activity at higher concentrations. $50{\mu}M$ 1-(5-isoquinolimnesulfonyl)-2-methylpiperazinme dihydrochloride (H-7), a PKC inhibitor, inhibited the progression of blastocyst to hatching embryo. In addition H-7 blocked the PAF effects on the blastocyst development. Besides tetradecanoylphorbol acetate (TPA), a PKC activator stimulated development of blastocyst to the hatching stage. These finding revealed that PAF support the blastocyst development to the hatching embryo. Also it is suggested that PAF action pathways in hatching supporting include the PKC signaling pathway.

• Archives of Pharmacal Research
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• v.27 no.7
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• pp.757-762
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• 2004

The protective adaptive response to electrophiles and reactive oxygen species is mediated by the induction of phase II detoxifying genes including glutathione S-transferases (GSTs). NF-E2-related factor-2 (Nrf2) phosphorylation by protein kinase C (PKC) is a critical event for its nuclear translocation in response to oxidative stress. Previously, we have shown that peroxynitrite plays a role in activation of Nrf2 and Nrf2 binding to the antioxidant response element (ARE) via the pathway of phosphatidylinositol 3-kinase (PI3-kinase) and that nitric oxide synthase in hepatocytes is required for GSTA2 induction. In view of the importance of PKC and Pl3-kinase in Nrf2-mediated GST induction, we investigated the role of these kinases in peroxynitrite formation for GSTA2 induction by oxidative stress and determined the relationship between PKC and PI3-kinase. Although PKC activation by phorbol 12-myristate-13-acetate (PMA) did not increase the extents of constitutive and inducible GSTA2 expression, either PKC depletion by PMA or PKC inhibition by staurosporine significantly inhibited GSTA2 induction by tert-butylhydroquinone (t-SHa) a prooxidant chemical. Therefore, the basal PKC activity is req- uisite for GSTA2 induction. 3-Morpholinosydnonimine (SIN-1), which decomposes and yields peroxynitrite, induced GSTA2, which was not inhibited by PKC depletion, but slightly enhanced by PKC activation, suggesting that PKC promotes peroxynitrite formation for Nrf2-mediated GSTA2 induction. Treatment of cells with S-nitroso-N-acetyl-penicillamine (SNAP), an exogenous NO donor, in combination with t-BHQ may produce peroxynitrite. GSTA2 induction by SNAP ＋ t-BHQ was not decreased by PKC depletion, but rather enhanced by PKC activation, showing that the activity of PKC might be required for peroxynitrite formation. LY294002 a P13-kinase inhibitor blocked GSTA2 induction by t-BHQ, which was reversed by PMA-induced PKC activation. These results provide evidence that PKC may playa role in formation of peroxynitrite that activates Nrf2 for GSTA2 induction and that PKC may serve an activator for GSTA2 induction downstream of PI3-kinase.

• Korean Journal of Veterinary Research
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• v.38 no.3
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• pp.508-517
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• 1998

There is evidence that the sympathetic nervous system exerts a control on thyroid function via an adrenergic innervation of thyroid cells. Although it is clear that the inhibitory effects of catecholamines result from an activation of ${\alpha}_1$-adrenoceptors, the mechanisms involved in ${\alpha}_1$-stimulation are not fully understood. The effects of methoxamine and protein kinase C (PKC) activator on the release of thyroxine ($T_4$) from mouse thyroid were studied to clarify the role of PKC in the regulation of $T_4$ release in vitro. The glands were incubated in the medium, samples of the medium were assayed for $T_4$ by EIA kits. Methoxamine inhibited the TSH-stimulated $T_4$ release. This inhibition was reversed by prazosin, an ${\alpha}_1$-adrenergic antagonist. Futhermore, the inhibitory effect of methoxamine on the $T_4$ release stimulated by TSH was prevented by chloroethylclonidine, an ${\alpha}_{1b}$-adrenoceptor antagonist, but not by WB4101, an ${\alpha}_{1a}$-adrenoceptor antagonist. Also methoxamine inhibited the forskolin-, cAMP- or IBMX-stimulated $T_4$ release. These inhibition were reversed by PKC inhibitors, such as staurosporine and $H_7$. PMA, a PKC activator, completely inhibited the TSH-stimulated $T_4$ release, and its inhibition was reversed by staurosporine and $H_7$, but not by chelerythrine. R59022 (a diacylglycerol kinase inhibitor), like methoxamine, also inhibited the TSH-stimulated $T_4$ release, and its inhibition was also reversed by staurosporine. The present study suggests that methoxamine inhibition of $T_4$ release from mouse thyroid can be induced by activation of the ${\alpha}_{1b}$-adrenoceptors and that it is mediated through the ${\alpha}_1$-adrenoceptor-stimulated PKC formation.

• 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.

• YAKHAK HOEJI
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• v.43 no.2
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• pp.263-273
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• 1999

When glutamate was infected intrathecally, the result is similar to those produced by TPA injected. The involvement of protein kinase C (PKC) in the nociceptive responses in rat dorsal horn neurons of lumbar spinal cord was studied. In test with formalin, a PKC inhibitor (chelerythrine) inhibited dose-dependently the formalin-induced behavior response. Neomycin also inhibited it significantly. But, a PKC activator (12-O-tetradecanoylphorbol-13-ester, TPA) showed reverse effect. When gluatamate was injected intrathecally, we observed the result is smilar to those produced by TPA injection. On the other hand, intrathecal injection of glutamate induced thermal and mechanical hyperalgesia. In Tail-flick test, we examined the involvement of PKC on the glutamate-indeced thermal hyperalgesia. Chelerythrine showed an inhibitory effect and TPA enhanced thermal response. Glutamate decreased the mechanical threshold significantly. A pretreatment of chelerythrine and neomycin inhibited glutamate-induced mechanical hyperalgesia, but the effect of neomycin was not significant. TPA had little effect on the mechanical nociceptive response. These results suggest that the PKC activation through metabotropic receptor at postsynaptic region of spinal cord dorsal horn neurons may influence on the persistent nociception produced by chemical stimulation with formalin, thermal and mechanical hyperalgesia induced by glutamate.

• Journal of Life Science
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• v.13 no.4
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• pp.441-447
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• 2003

To examine the role of protein kinase C (PKC) in regulation of interleukin-1 beta (IL-1$\beta$)-induced iNOS expression, IL-1$\beta$-induced nitrite production was observed in cultured vascular smooth muscle (VSM) cells pretreated with phorbol 12-myristate 13-acetate (PMA) and phorbol 12,13-butyrate (PDB) as PKC activator; 4$\alpha$-phorbol-didecanoate (PDD) as PKC non-activator. Nitrite production induced by IL-1$\beta$ was increased by the presence of increasing concentration of PMA ranging from 2 to 200 nM. However, in VSM cells pretreated with PMA and PDB, IL-1$\beta$-induced $NO_2$ production was decreased in proportion to the duration of pretreatment, and most significantly decreased in pretreatment time of 24 hours. Using RT-PCR method, the expression of iNOS mRNA induced by IL-1$\beta$ was decreased in VSM cells pretreated with PMA 200 nM for 24 hours. These results suggest that decrease in IL-I$\beta$-induced nitrite production by the pretreatment of PMA result from inhibition of iNOS expression and the inhibition related to PMA-induced PKC down-regulation.

• Journal of Life Science
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• v.8 no.6
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• pp.638-647
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• 1998

Protein Kinase C (PKC) activators, phorbol 12-myristate 13-acetate (PMA), bryostatin, and dioctanoyl glycerol (DiC8), induce translocation of PKC isozymes from cytoplasm to plasma membrane or into nucleus. The activated PKC negatively modulates growth of human breast cancer cells. Antiproliferative effect and translocation of PKC were investigated in MCF-7 cells. The translocation of activated PKC isozymes by PMA, bryostatin and DiC8 was occurred at the various different regions in MCF-7 cell. PKC $\alpha$ and $\beta$ could be translocated to the nucleus or the nuclear mem-brane, and PKC $\delta$and $\varepsilon$ to cell membrane by PMA while DiC8 and bryostatin induced the translocation of PKC $\alpha$ and $\beta$ to the nucleus or plasma membrane, respectively. In the antiproliferative effect of PKC activators, PMA ($IC_{50}$/ values of 1.2$\pm$0.3nM) and DiC8 ($IC_{50}$/ values of 5.0$\pm$1.1$\mu$M) inhibited the cell growth. Bryostatin also inhibited the cell growth but to a much less degree than one obser-ved with PMA : 16% growth reduction by 100nM bryostatin. However, PMA treated with bryostatin induced gro-wth inhibition, but PMA with DiC8 at 10$\mu$M was not effective. These results suggest that each PKC isozyme is tran-slocated to various specific sites, and that especially, PKC $\alpha$ isozyme plays an important role in control of antiprolife-raive function of cell growth.