Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Murine immune interferon (Mu-IFN-gamma) can be radiolabeled with [gamma-32P]ATP by the catalytic subunit of cAMP-dependent protein kinase. The resulting 32P-labeled Mu-IFN-gamma (32P-Mu-IFN-gamma) with high radiological specific activity (60-260 muCi/micrograms) retains biological activity. Acid hydrolysis of 32P-Mu-IFN-gamma or 32P-labeled human IFN-gamma leads to the release of [32P]phosphoserine but not phosphothreonine or phosphotyrosine. With 32P-Mu-IFN-gamma, we have demonstrated that there are 5 X 10(3) to 1.5 X 10(4) receptors per-cell on several murine cell lines of diverse origin and that the Kd at 24 degrees C for these cells is in the range of 1 X 10(-10) to 1 X 10(-9) M. Covalent binding of 32P-Mu-IFN-gamma to its receptor results in the formation of several specific high-molecular weight products, the major one of which has an apparent molecular weight of 90,000-100,000. If this represents a 1:1 complex of Mu-IFN-gamma and its receptor (or its binding subunit), the murine interferon gamma receptor has a molecular weight of 75,000-85,000.
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PMID:Preparation of 32P-labeled murine immune interferon and its binding to the mouse immune interferon receptor. 301 8

The activation of the serine/threonine kinase, Raf-1, serves to connect upstream protein tyrosine kinases to downstream signaling events. We previously reported that FcgammaRI stimulation of interferon gamma-differentiated U937 cells (termed U937IF cells) induces a mobility shift in Erk2. Herein, we report that cross-linking of FcgammaRI receptor in U937IF cells induces a marked tyrosine phosphorylation of Raf-1 (10-fold increase). Tyrosine phosphorylation of Raf-1 is induced by FcgammaRI activation and not by PMA (1 microg/ml), N-formyl-Met-Leu-Phe (1 microM), calcium ionophore (1 microM), thrombin (0.05 unit/ml), FcgammaRII, or FcgammaRIII stimulation. The kinetics of Raf-1 tyrosine phosphorylation is rapid, reaching peak levels 1-2 min after FcgammaRI activation, and the tyrosine phosphorylation of Raf-1 precedes the activation of the respiratory burst. FcgammaRI cross-linking induces the tyrosine phosphorylation of Shc; tyrosine-phosphorylated Shc binds to Grb2 forming a Shc-Grb2 complex. The data provide evidence that the FcgammaRI receptor signals via the upstream activation of nonreceptor protein tyrosine kinases, which leads to the subsequent activation of Ras family GTPases and serine/threonine kinases, Raf-1 and mitogen-activated protein kinase.
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PMID:A role for Shc, Grb2, and Raf-1 in FcgammaRI signal relay. 866 46

There is currently much interest in the mechanisms of action of antiproliferative agents and their effects on cell cycle machinery. In the present study we examined the mechanisms of action of four unrelated agents known to inhibit proliferation of CSF-1-stimulated bone marrow-derived macrophages (BMM). We report that 8-bromo-cAMP (8Br-cAMP) and lipopolysaccharide (LPS) potently reduced CSF-1-stimulated cyclin D1 protein, and cyclin-dependent kinase (cdk) 4 mRNA and protein levels, while the inhibitory effects of the Na+/ H+ antiport inhibitor 5-(N',N'-dimethyl) amiloride (DMA) and interferon gamma (IFN gamma ) were only weak. All agents repressed CSF-1-stimulated retinoblastoma protein phosphorylation. Furthermore, 8Br-cAMP and to a lesser extent IFN gamma, also reduced CSF-1-stimulated levels of E2F DNA binding activity in a macrophage cell line, BAC1.2F5. An explanation for the different effects of the agents is that 8Br-cAMP and LPS were found to arrest BMM in early/mid-G1, while IFN gamma and DMA arrested cells in late G1 or early S phase. These data indicate that (1) different antiproliferative agents can arrest the same cell type at distinct checkpoints in G1 and (2) effects of antiproliferative agents on cell cycle machinery is linked to the position at which they arrest cells in G1.
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PMID:Differential regulation of cell cycle machinery by various antiproliferative agents is linked to macrophage arrest at distinct G1 checkpoints. 876 Mar 1

Cell-mediated immunity is often impaired in cancer. This may be partly due to increased amounts of prostaglandin E2 (PGE2) and histamine in the blood of cancer patients, since PGE2 and histamine possess inhibitory effects on cellular immunity. These effects are mediated by cyclic AMP (cAMP), which is increased in leukocytes by PGE2 through EP2 and by histamine through H2 receptors and also by epinephrine through beta 2-adrenergic receptors. Increased cAMP activates protein kinase A, which inhibits the formation of interleukin 2 (IL-2) in T cells. The formation of interferon gamma is concomitantly decreased, and cellular immunity is attenuated. In monocyte/macrophages the formation of IL-1 beta, IL-12 and tumor necrosis factor alpha is decreased by cAMP or through the increased formation of IL-10, which is up-regulated by cAMP. This attenuates cellular immunity. In monocytes histamine may decrease the formation of oxygen intermediates, which can induce apoptosis of natural killer cells and thus inhibit immunity. The superoxide anion is a potent inducer of the cyclooxygenase-2 enzyme, which is upregulated in colorectal cancer. Cyclooxygenase-2 catalyzes the formation of PGE2, e.g. in cancer cells. Thus the inhibition of cellular immunity in cancer may be at least partly mediated by cAMP and oxygen intermediates. This may offer new options for cancer immunotherapy.
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PMID:The role of cyclic AMP and oxygen intermediates in the inhibition of cellular immunity in cancer. 891 29

HIV-1 Nef protein shares a significant homology with the immunosuppressive and highly conserved retroviral transmembrane protein p15E. In the present study, extracellular Nef protein is shown to induce interleukin (IL)-10 mRNA expression in human peripheral blood mononuclear cells as well as in cells of H9 T and U937 promonocytic human cell lines. Release of IL-10 protein into supernatants of peripheral blood mononuclear cells stimulated with Nef is dose-dependent. Expression of cytokines IL-2, IL-4, IL-5, IL-12 p40, IL-13, and interferon gamma is not affected by Nef stimulation. IL-10 protein production induced by Nef is inhibited by the calcium/calmodulin phosphodiesterase inhibitor W-7 but not by the protein kinase A inhibitor H-89 nor the protein kinase C inhibitors staurosporine and calphostin C. The calcium chelating agent EGTA also inhibits the IL-10 production induced by Nef, and this inhibition is reversed by the addition of calcium along with Nef. These findings indicate that extracellular Nef may contribute to the immunopathogenesis of HIV infection by inducing IL-10.
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PMID:Interleukin 10 is induced by recombinant HIV-1 Nef protein involving the calcium/calmodulin-dependent phosphodiesterase signal transduction pathway. 909 66

1. In RAW 264.7 murine macrophages and rat aortic smooth muscle (RASM) cells lipopolysaccharide (LPS) alone or in combination with interferon gamma (IFN gamma) or forskolin, respectively, stimulated the expression of the 130 kDa inducible isoform of nitric oxide synthase (iNOS) in both a time- and concentration-dependent manner. 2. Incubation with the direct activator of protein kinase C (PKC), phorbol 12-myristate 13-acetate (PMA) alone, did not result in detectable iNOS expression in either cell type. 3. Chronic PMA pretreatment resulted in significant down-regulation of alpha, beta and epsilon isforms of PKC in RAW 264.7 macrophages and corresponded to a 20-30% reduction in LPS-induced iNOS expression. In contrast, IFN gamma alone or in combination with LPS stimulated an approximate 20% and 50% potentiation, respectively. 4. Pre-incubation with PKC inhibitors (calphostin C and H-7) showed similar effects upon stimulated induction of iNOS. 5. In RASM cells chronic PMA pretreatment resulted in down-regulation of alpha and epsilon PKC isoforms and corresponded to potentiation of iNOS expression in response to LPS alone or in combination with forskolin. 6. Co-incubation of RASM cells in the presence of PMA, angiotensin II (AII) or foetal calf serum (FCS) resulted in the inhibition of iNOS expression in response to LPS alone or in combination with forskolin. 7. Differential sensitivity to PKC inhibitors (calphostin C and H-7) was observed in RASM cells and exhibited both negative and positive modulation of stimulated induction. 8. In addition the PKC inhibitor compound Ro-31-8220 abolished stimulated induction in both cell types in response to all treatments. 9. These results suggest that PKC activation is required for induction of the 130 kDa isoform of NOS in both RAW 264.7 macrophages and RASM cells. However, individual PKC isoforms regulate iNOS expression in both a positive and negative manner.
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PMID:Differential regulation by protein kinase C isoforms of nitric oxide synthase induction in RAW 264.7 macrophages and rat aortic smooth muscle cells. 913 2

This study analyses the production of tumour necrosis factor (TNF)alpha and soluble TNF receptor (sTNF-R) before and after exposure to gamma irradiation and interferon gamma (IFN gamma) in 12 cell lines derived from Ewing's sarcoma (ES)/peripheral primitive neuroectodermal tumours (pPNET). Supernatants from ES/pPNET cell cultures were tested in a TNF alpha-specific amplified enzyme-linked immunosorbent assay (ELISA), a bioassay, and sTNF-Rp55 and sTNF-Rp75 ELISA. The tumour cell lines released minimal amounts of TNF alpha, prominent amounts of sTNF-Rp55 (7/12 cell lines) and no sTNF-Rp75. Exposure to gamma irradiation (5 Gy) either induced (3/12) cell lines) or up-regulated (3/12 cell lines) TNF alpha release without changing sTNF-Rp55 and sTNF-Rp75 levels. Priming of cultures with recombinant human IFN gamma (rhIFN gamma) markedly enhanced TNF alpha secretion in the radiation-responsive cell lines and had no influence on sTNF-Rp55 and sTNF-Rp75 levels. rhIFN gamma affected the magnitude rather than the sensitivity of the radiation response. The TNF alpha secreted was bioactive, as shown by its cytotoxic effect of WEHI-164 cells, and neutralization of its activity by anti-TNF alpha monoclonal antibody. Herbimycin A (a tyrosine-specific protein kinase inhibitor) but not calphostin C (a protein kinase C inhibitor), H89 (a protein kinase A inhibitor), AA-COCF3 (a specific inhibitor of phospholipase A2) and MK-886 (a specific inhibitor of 5-lipoxygenase) abrogated gamma-irradiation-stimulated TNF alpha release. The antioxidants N-acetylcysteine, nordihydroguaiaretic acid and mepacrine dose-dependently inhibited gamma-irradiation-mediated TNF alpha production. Collectively our findings indicate that IFN gamma priming potentiates the secretion of bioactive TNF alpha by ES/pPNET cells in response to gamma irradiation without affecting sTNF-R release. The data suggest a requirement for protein tyrosine kinase activity and a role for reactive oxygen species in the gamma-irradiation-mediated intracellular signalling pathway leading to TNF alpha production.
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PMID:Regulation of the release of tumour necrosis factor (TNF)alpha and soluble TNF receptor by gamma irradiation and interferon gamma in Ewing's sarcoma/peripheral primitive neuroectodermal tumour cells. 920 Dec 46

A primary signaling cascade responsible for the expression of cytokine-stimulated immediate early genes involves the activation of the Jak/Stat pathway. In addition to being tyrosine-phosphorylated, several signal transducers and activators of transcription (Stats), including Stat1alpha, Stat3, and Stat4, are phosphorylated on a conserved serine residue, which is a consensus phosphorylation site for mitogen-activated protein kinases (MAPKs). Serine phosphorylation of Stat1alpha is required for maximal transcriptional activation of early response genes by interferon gamma (IFNgamma) as well as the antiviral and antigrowth actions of this cytokine. Incubation of cells with either IFNgamma or oncostatin M (OSM) activates Raf-1, a serine/threonine kinase responsible for the ultimate activation of p42 MAPK. To examine whether any of the signaling components that are required for activation of the Jak/Stat pathway are also necessary for activation of Raf-1 by IFNs and OSM, we examined activation of Raf-1 in cell lines that are deficient in either Stat1alpha or Stat2. Unexpectedly, incubation of Stat1-deficient, but not Stat2-deficient cells with IFNgamma or OSM for 5 min displayed no increase in Raf-1 activity. In peripheral blood lymphocytes Raf-1 was associated with Stat1, and this interaction was disrupted after incubation of cells with IFNgamma. Stat1-negative cells reconstituted with either Stat1alpha or Stat1alpha with a point mutation in the site where it is serine-phosphorylated displayed normal activation of Raf-1 by IFNgamma and OSM. However, activation of Raf-1 was not observed in lines that expressed Stat1alpha containing a mutation in its tyrosine phosphorylation site or in its SH2 domain. These results provide the first example of a novel role of Stat1alpha not as a transcription factor, but as a protein which may function to scaffold signaling components required for activation of the distinct Raf/MEK/MAPK signaling cascade.
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PMID:Activation of Raf-1 by interferon gamma and oncostatin M requires expression of the Stat1 transcription factor. 966 40

In the present study, the expression of interleukin 17 (IL-17) by human CD8(+) T lymphocytes and its regulation following PKA activation was determined and compared with that of interferon gamma (IFN-gamma) and IL-10. IL-17 mRNA was highly expressed in human CD8(+) T lymphocytes at least at the same level than in CD4(+) T cells that were isolated from peripheral blood mononuclear cells (PBMC). Expression of IL-17 mRNA in CD8(+) T cell was induced by prior activation of PBMC for 18 h with Ca2+ ionophore and phorbol myristate acetate (PMA). Furthermore, our results clearly showed that CD8(+) T cells are sensitive to elevation of cAMP and PKA activation pathway. Data demonstrated a significant inhibition of IL-17 as well as of IFN-gamma mRNA expression in CD8(+) T cells isolated from activated PBMC cultured in the presence of either dibutyryl cAMP (db-cAMP) or PGE2. In contrast, IL-10 mRNA expression was strongly enhanced in the same experimental conditions. The differential expression of IL-10 and IFN-gamma production in CD8(+) T cells was also observed at the protein level as it was measured by a double immunofluorescence technique and flow cytometry analysis. Taken together, these results provide evidence that human CD8(+) T cells are also the source of massive expression of IL-17, and that PKA plays a prominent role in the switch of CD8(+) T cells to a Th2 like profile and an inhibition of IL-17 expression, thus suggesting that the activation of cAMP signal transduction pathway may have consequences for the relative role of CD8(+) T cells in the immune and inflammatory process.
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PMID:Regulation of IL-17, IFN-gamma and IL-10 in human CD8(+) T cells by cyclic AMP-dependent signal transduction pathway. 987 22

In the present study, the authors compared the interleukin 17 (IL-17 expression of human naive and phenotypically defined memory T cells as well as its regulation by cAMP pathway. Our data showed that IL-17 mRNA was highly expressed in memory human peripheral CD8(+)45RO+T cells and CD4(+)45RO+T cells when peripheral blood mononuclear cells were first stimulated with ionomycin/PMA. IL-17 expression in memory CD8(+)T cells required accessory signals since culture of ionomycin/PMA-activated CD8(+)45RO+T cells alone did not result to IL-17 expression. In contrast, memory CD4(+)T cell population seems to be more independent. IL-17 and interferon gamma(IFN-gamma) mRNA were both inhibited in the presence of PGE2 or the cAMP analogue (dibutyryl-cAMP), while the anti-inflammatory cytokine IL-10 was highly increased. In contrast, naive CD45RA+T cells were unable to express IL-17 whatever the culture conditions. Naive CD4(+)and CD8(+)T cells were sensitive to the PKA regulatory pathway since they represent a significant source of IL-10 when PBMC were first cultured with ionomycin/PMA in the presence of either PGE2 or db-cAMP. The authors showed that naive cells are highly dependent to their microenvironment, since culture of ionomycin/PMA-activated CD45RA+T cells alone did not result in detectable levels of cytokines even in the presence of PGE2. Results also showed that PGE2 induced quite the same levels of intracellular cAMP in naive and memory cells suggesting that these cell populations are equally sensitive to PGE2. However, we suggest that PGE2 may be more efficient in blocking both IL-17 and IFN-gamma expression in already primed memory T cells, rather than in suppressing naive T cells that could represent a significant source of IL-10. Data suggest that PKA activation pathway plays a critical role in the regulation of cytokine profiles and consequently the functional properties of both human naive and memory CD4(+) and CD8(+)T cells during the immune and inflammatory processes.
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PMID:Expression of IL-17 in human memory CD45RO+ T lymphocytes and its regulation by protein kinase A pathway. 1032 64


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