Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Since there is increasing evidence that protein kinase C (PKC) has a crucial role in the production of nitric oxide (NO) from activated macrophages, this study was undertaken to address whether NO could regulate the expression of the gene of this enzyme. Stimulation of the cells with lipopolysaccharide (LPS) or phorbol 12-myristate 13-acetate (PMA) after treatment with recombinant interferon-gamma (rIFN-gamma) resulted in the increased production of NO in the medium. rIFN-gamma in combination with either LPS or PMA showed marked inhibition of the expression of PKC delta gene, whereas rIFN-gamma alone showed modest inhibition. The inhibition of gene expression was correlated with the amount of NO produced by activated macrophages. The inhibitory effect of NO on the expression of PKC delta gene is mimicked by the treatment of NO generating agent, sodium nitroprusside (SNP). On the other hand, a specific inhibitor for NO synthase, NG-monomethyl-L-arginine (NGMMA), blocked the inhibition of the expression of PKC delta gene by blocking the NO production in the rIFN-gamma and LPS-stimulated cells. However, production of NO did not affect the expression of both TNF-alpha and TGF-beta gene which were induced by the stimulation of macrophages, as well as beta-actin gene, which was constitutively expressed in the macrophages. In conclusion, these findings show that NO has a regulatory role for the expression of the gene of PKC delta which is crucially involved in the process of NO synthesis.
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PMID:Nitric oxide inhibits the expression of protein kinase C delta gene in the murine peritoneal macrophages. 794 48

The signal pathways by which interferon-gamma (IFN-gamma) is able to up-regulate major histocompatibility complex (MHC) class I transcription were studied in two human hematopoietic tumor cell lines, K562 and Ramos. These studies suggest that the IFN-gamma signal is transduced via an H7- and staurosporine-sensitive kinase that is distinct from protein kinase C (PKC) and protein kinase A (PKA) in both cell types. Ramos cells appear to utilize an additional pathway involving double-stranded RNA-dependent protein kinase. PKC and possibly PKA appear to be involved in one or more intersecting pathways by which agonists of these kinases are able to act synergistically with IFN-gamma, but activation of these latter pathways is neither necessary nor sufficient for induction of MHC class I transcription. Modulation of G-protein- and Ca2+-calmodulin-associated pathways and arachidonic acid metabolism had no effect on constitutive or IFN-gamma-stimulated class I transcription. The class I stimulatory factor produced in response to IFN-gamma treatment appears to have a short t1/2. The identity of this factor is unknown, but is likely to be distinct from known mediators of IFN-stimulated transcription. Gene and cell-type specificity in the signal transduction pathways utilized by IFN-gamma implies that such pathways may be useful targets for experimental and therapeutic manipulation.
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PMID:Stimulation of MHC class I transcription by interferon-gamma involves a non-A, non-C kinase in addition to protein kinase C. 809 99

Incubation of the human renal carcinoma cell line CaKi-1 with interferon-gamma (IFN-gamma) or the phorbol ester, phorbol-12-myristate 13-acetate (PMA) strongly stimulated the immunocytochemical expression of the intercellular adhesion molecule-1 (ICAM-1) in a dose-dependent manner. Since PMA is capable of activating the Ca2+/phospholipid-dependent protein kinase C (PKC), we investigated the role of this kinase during IFN-gamma signal transduction. Calcium ionophore A23187 significantly enhanced IFN-gamma- and PMA-induced ICAM-1 staining. While staurosporine, H7 and sphingosine, three known PKC inhibitors, blocked the PMA effect, only staurosporine abrogated the action of IFN-gamma. Finally, 24 h of PMA pretreatment with subsequent IFN-gamma stimulation enhanced ICAM-1 staining above values from cultures where IFN-gamma was omitted. This occurred despite the fact that 24 h of PMA pretreatment abolished the effect of IFN-gamma on PKC activation, as determined by acetylated myelin basic protein 4-14 phosphorylation. In conclusion, these results suggest that additional events other than PKC activation are required for complete regulation of ICAM-1 antigen by IFN-gamma in the whole cell population. Hence, other Ca(2+)-dependent signalling pathway(s) mediated by IFN-gamma receptors must act. Further studies are needed to elucidate these specific pathway(s) activated during IFN-gamma stimulation in our model.
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PMID:Role of protein kinase C during interferon-gamma- and phorbol ester-stimulated immunocytochemical expression of ICAM-1 in human renal carcinoma cells. 810 44

We studied the effect of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and interferon-gamma (IFN-gamma) on the function of thyroid cells and pituitary thyrotrophs. In FRTL-5 rat thyroid cells, both human and murine TNF-alpha inhibited basal and TSH-stimulated [125I]iodide transport. IL-1 shared this action with TNF-alpha, but was less potent. IL-1 and IFN-gamma did not cause a further reduction of TNF-alpha-induced inhibition of [125I]iodide transport. TNF-alpha, phorbol ester 12-myristate 13-acetate (PMA), and calcium ionophore (CI) A23817 all inhibited [125I]iodide transport, but high doses of PMA and CI also blocked the inhibitory action of TNF-alpha on [125I]iodide transport. Inhibition of protein kinase A and protein kinase C by H7 or HA inhibited TSH-stimulated iodide transport, but did not block the TNF-alpha action, suggesting that the mechanism of TNF-alpha action on thyroid cells is independent of protein kinase A and C. In pituitary cells, both human and murine TNF-alpha did not affect basal TSH secretion, but TNF-alpha reduced TRH-stimulated TSH secretion. This study provides further in vitro evidence that TNF-alpha inhibits the function of the hypothalamus-pituitary-thyroid axis acting directly on both the pituitary and thyroid glands.
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PMID:Suppression of rat thyrotroph and thyroid cell function by tumor necrosis factor-alpha. 811 27

The effects of glucocorticoid on the production of nitric oxide (NO) by murine microglial cells were investigated. Stimulation of the cells with lipopolysaccharide (LPS) or phorbol 12-myristate 13-acetate (PMA) after the treatment of recombinant interferon-gamma (rIFN-gamma) resulted in the increased accumulation of nitrite in the medium. Concomitant incubation of the cells with dexamethasone (DEX) markedly inhibited the production of NO in a dose dependent manner. DEX also suppressed both rIFN-gamma and rIFN-gamma plus LPS-induced activity of the enzyme protein kinase C (PKC), a putative regulator of NO synthesis, but had only a modest inhibitory effect on basal activity. In addition, the inhibitory effect of DEX on NO generation was mimicked by the treatment of PKC inhibitors such as staurosporine (STSN) and polymyxin B. Our findings show that glucocorticoids have the potential to modulate central nervous system (CNS) NO production via the inhibition of PKC activity particularly under the conditions of stimulated production of NO, such as inflammatory and demyelinating CNS disorders.
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PMID:Involvement of protein kinase C in the inhibition of nitric oxide production from murine microglial cells by glucocorticoid. 813 4

It is well known that interferon-gamma (IFN-gamma; type II) potentiates various responses of human tumor necrosis factor (TNF) in a wide variety of cells and that this potentiation is accompanied by the up-regulation of TNF receptor synthesis. In the present studies we examined the regulation of TNF receptors by type I and type II IFNs in a hepatocellular carcinoma cell line, HEP G2. Exposure of these cells to IFN-gamma led to a decrease in TNF receptor number (4029 vs. 2719 sites/cell) without any change in the receptor affinity (0.96 nM vs. 1.1 nM). The effect was time and dose-dependent. Like IFN-gamma, IFN-alpha and IFN-beta (type I) down-modulated the TNF receptors on these cells. The effect of IFNs on the TNF receptors was inhibited by staurosporin, a protein kinase C (PK-C) inhibitor. Furthermore, by the use of receptor-specific antibodies, we found that the IFN-dependent decrease was primarily due to the p60 form of the TNF receptor. Our results presented are the first to demonstrate that IFNs can also down-modulate TNF receptors in certain cells and that this effect is mediated through PK-C.
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PMID:Both type I and type II interferons down-regulate human tumor necrosis factor receptors in human hepatocellular carcinoma cell line Hep G2. Role of protein kinase C. 827 22

Current adoptive immunotherapy strategies in cancer patients require large numbers of activated T-cells and are limited by the availability of autologous tumour. We describe a novel method of T-cell activation that produced relatively rapid, high-fold expansion of stored, frozen lymphocytes obtained from the lymph nodes of 20 breast cancer patients during axillary dissection but does not require autologous tumour. In vitro exposure of thawed cells to bryostatin-1 (B), a non-tumour promoting protein kinase C activator and ionomycin (I), a calcium ionophore, at day 0 followed by culture in low dose interleukin-2 (IL-2 20 units ml-1) and restimulation again on day 10 results in 269-28,206 fold (geometric mean = 2254) expansion in cell numbers counted 17 days after initial stimulation. Analysis of cell surface markers revealed that B/I expanded human cells were predominantly T-cells (83-97%) and consisted of a mixture of CD8+ (46-74%) and CD4+ (4-30%) cells. B/I expanded cells did not lyse autologous tumour cells when tested in a 4-h 51Cr release assay, but murine studies reported previously have demonstrated specific and curative in vivo efficacy in MCA-105 tumour-bearing mice despite an inability to lyse autologous tumour in vitro. B/I expanded T-cells from five of six patients secreted the cytokines tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in response to co-culture with autologous tumour cells but not with irrelevant tumour. These results are analogous to findings in a murine model, in which non-cytolytic B/I expanded T-cells mediated specific, curative anti-tumour effects in vivo, and lay the groundwork for a clinical trial of this novel strategy for the adoptive immunotherapy of breast cancer patients.
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PMID:Expansion and tumour specific cytokine secretion of bryostatin-activated T-cells from cryopreserved axillary lymph nodes of breast cancer patients. 830 69

To understand the differential role of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in the process of macrophage tumoricidal activation, we investigated the production of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide in activated murine macrophages and the effects of those lymphokines on prostaglandin E2 (PGE2)-mediated down-regulation. IFN-gamma and IL-4 increased lipopolysaccharide (LPS)-induced TNF-alpha production by different mechanisms because IL-4, unlike IFN-gamma, failed to overcome the LPS-hyporesponsiveness in C3H/HeJ mice. Moreover, only IFN-gamma synergized with LPS to induce nitric oxide production and blocked eicosanoid-mediated down-regulation. These differential effects of IFN-gamma and IL-4 on the select efferent cytolytic activities may be the result of an altered or different signal transduction pathway. Because potentiation of protein kinase C (PKC) activity by IFN-gamma has been previously documented, we next studied the role of IFN-gamma and IL-4 in alteration of enzymatic activity of PKC. Two lymphokines caused translocation of PKC from cytosol to membrane with different levels, providing a biochemical basis for explaining how two lymphokines lead to different phenotypic responses. Although treatment of macrophages with IFN-gamma and IL-4 gave rise to a similar enhancing effect on macrophage TNF-alpha production, these two lymphokines appeared to differentially regulate the overall functional state of macrophages for tumour cell killing capability. Additionally, this differential regulation seems to be accomplished in part by different biochemical events.
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PMID:Regulation of murine macrophage function by IL-4: IL-4 and IFN-gamma differentially regulate macrophage tumoricidal activation. 830 12

Murine T helper cell clones are classified into two distinct subsets, T helper 1 (Th1) and T helper 2 (Th2), on the basis of cytokine secretion patterns. Th1 clones produce interleukin-2 (IL-2), tumor necrosis factor-beta (TNF-beta) and interferon-gamma (IFN-gamma), while Th2 clones produce IL-4, IL-5, IL-6 and IL-10. These subsets differentially promote delayed-type hypersensitivity or antibody responses, respectively. The nuclear factor NF-AT is induced in Th1 clones stimulated through the T cell receptor-CD3 complex, and is required for IL-2 gene induction. The NF-AT complex consists of two components: NF-ATp, which pre-exists in the cytosol and whose appearance in the nucleus is induced by an increase of intracellular calcium, and a nuclear AP-1 component whose induction is dependent upon activation of protein kinase C (PKC). Here we report that the induction of the Th2-specific IL-4 gene in an activated Th2 clone involves an NF-AT complex that consists only of NF-ATp, and not the AP-1 component. On the basis of binding experiments we show that this 'AP-1-less' NF-AT complex is specific for the IL-4 promoter and does not reflect the inability of activated Th2 cells to induce the AP-1 component. We propose that NF-ATp is a common regulatory factor for both Th1 and Th2 cytokine genes, and that the involvement of PKC-dependent factors, such as AP-1, may help determine Th1-/Th2-specific patterns of gene expression.
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PMID:A common factor regulates both Th1- and Th2-specific cytokine gene expression. 831 7

Trypanosoma brucei brucei releases a lymphocyte-triggering factor (TLTF) that activates CD8+ T cells. We here study second messenger mechanisms in this activation, i.e. the effects of protein kinase C (PKC), protein kinase A (PKA) and tyrosine kinases (TPK) inhibitors on TLTF-induced interferon-gamma (IFN-gamma) secretion and proliferation in lymphoid cell cultures. The effects were compared to those obtained by phytohemagglutinin (PHA) stimulation. Rat spleen mononuclear cells (MNC) and spleen MNC from a mutant mouse strain possessing CD8+ T cells but lacking CD4+ T cells were used as responder cells. Although both the PKC and the PKA inhibitors suppressed PHA-induced IFN-gamma secretion and proliferation of rat MNC and mouse CD8+ CD4- MNC, they had no effect on the same TLTF-induced responses. The TPK inhibitor genistein, however, strongly suppressed TLTF-induced activation of both types of responder cells to IFN-gamma secretion and the TLTF-induced proliferation of mouse CD8+ CD4- MNC. The suppressive effects of the drugs could be overcome by ionomycin and tetradecanoylphorbol acetate, which show that the effects were not due to drug nonspecific cellular toxicity of the drugs. We conclude that TLTF activates CD8+ T cells through pathways other than the PKC- or PKA-dependent signal transduction, and that TPK may be involved in the triggering.
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PMID:T cell activation by a Trypanosoma brucei brucei-derived lymphocyte triggering factor is dependent on tyrosine protein kinases but not on protein kinase C and A. 832 29


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