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)

We have investigated the mechanism of tolerance in a patient with severe combined immunodeficiency (SCID) transplanted with HLA-haploidentical, T cell-depleted bone marrow cells obtained from the mother. At 4 years after transplantation, T cells, natural killer (NK) cells, and a small percentage (2%) of B cells were found to be of donor origin, whereas monocytes and the majority of B cells remained of host origin. In primary mixed lymphocyte cultures (MLC), the engrafted T cells of the donor did not proliferate in response to the host cells, whereas untransplanted donor T cells showed good proliferative responses. However, CD4+ and CD8+ T-cell clones of donor origin with specificity for class II and class I HLA determinants of the host were isolated. CD8+, host-reactive T-cell clones displayed normal cytotoxic activity after stimulation with the host cells, but proliferative responses of CD4+, host-reactive T-cell clones were considerably reduced. In addition, both CD8+ and CD4+, host-reactive T-cell clones produced very low to undetectable levels of interleukin-2 (IL-2), IL-4, IL-5, IL-10, interferon-gamma, and granulocyte-macrophage colony-stimulating factor after specific antigenic activation, which may be responsible for their nonresponsive state in vivo. Expression of the CD3 zeta subunit of the T-cell receptor (TcR) was normal, and after stimulation via CD3, Raf-1 and p42 mitogen activated protein (MAP) kinase were phosphorylated, indicating that this part of the signaling pathway after triggering of the TcR/CD3 complex is present. These results, together with our previous observation that dysfunctional, host-reactive T-cell clones can be isolated in SCID patients transplanted with fetal liver stem cells, demonstrate that lack of clonal deletion of host-reactive T cells is a general phenomenon after HLA-mismatched stem cell transplantation.
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PMID:Dysfunctional cytokine production by host-reactive T-cell clones isolated from a chimeric severe combined immunodeficiency patient transplanted with haploidentical bone marrow. 770 97

Expression of the IL-5 gene in T cells is induced in response to Ag stimulation; however, functional analysis of the IL-5 gene has been limited by lack of an appropriate transfection assay to facilitate measurement of the IL-5 promoter activity in response to T cell activation signals. Here, we describe a transient transfection system with which the IL-5 promoter activity can be assayed quantitatively. Using mouse thymoma line EL-4 cells, which produce several lymphokines including IL-2, IL-3, IL-4, IL-10, and GM-CSF in response to PMA, the effect of cAMP on IL-5 production was examined. These cells produce a low level of IL-5 when stimulated with PMA alone; however, N6, O2-dibutyryl cAMP (Bt2cAMP), in combination with PMA, augmented by more than tenfold the IL-5 production at the mRNA and the protein levels. Likewise, a transient transfection assay revealed that Bt2cAMP activated the IL-5 promoter more than tenfold, in a PMA-dependent manner, thereby indicating that two signals, PMA and cAMP, are required for optimal activation of the IL-5 promoter. Activation of the IL-5 promoter in response to Bt2cAMP and PMA depends on the region spanning from nucleotide position -1,200 to +33 relative to the transcription initiation site. Action of cAMP on the IL-5 promoter is mimicked by cotransfection of the expression plasmid containing cDNA encoding the catalytic subunit of protein kinase A, hence, cAMP probably exerts its action through the signaling pathway that involves protein kinase A. In contrast, Bt2cAMP almost completely inhibited the PMA-dependent activation of the endogenous IL-2 gene as well as the transfected IL-2 promoter. These results indicate that the IL-5 gene in EL-4 cells is positively regulated by cAMP in a manner opposite that for the IL-2 gene.
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PMID:cAMP activates the IL-5 promoter synergistically with phorbol ester through the signaling pathway involving protein kinase A in mouse thymoma line EL-4. 824 56

In the present study, we have investigated the involvement of the cyclic adenosine monophosphate (cAMP)-dependent signaling pathway on interleukin-4 (IL-4) gene expression in freshly isolated human T lymphocytes. 2'-0-dibutyryl cAMP (db-cAMP) and prostaglandin E2 (PGE2) were used to directly and indirectly activate the protein kinase A pathway. Northern analysis showed that concanavalin A (Con A)-, anti-CD3 (alpha CD3)-, or anti-CD3 plus anti-CD28 (alpha CD3/alpha CD28)-induced accumulation of IL-4 mRNA was inhibited by db-cAMP (10(-3) mol/L). Db-cAMP showed a steep dose-dependent inhibition; concentrations < or = 10(-4) mol/L did not affect IL-4 mRNA accumulation. In contrast, GM-CSF mRNA expression showed a wider dose-dependent range; 10(-5) mol/L db-cAMP still affected GM-CSF accumulation. PGE2 inhibited the Con A- and alpha CD3/alpha CD28-induced accumulation of IL-4 mRNA in a dose-dependent fashion. Con A-induced IL-4 mRNA was inhibited by 10(-4) to 10(-7) mol/L PGE2; alpha CD3/alpha CD28-induced IL-4 mRNA was inhibited by 10(-5) to 10(-8) mol/L PGE2. Nuclear run-on experiments showed that the inhibitory effects of db-cAMP and PGE2 were accomplished at transcriptional level in Con A-activated T cells, whereas changes at transcriptional and posttranscriptional level were involved in alpha CD3/alpha CD28-activated T lymphocytes. In contrast to Con A and alpha CD3/alpha CD28 activation, phorbol myristate acetate plus A23187-induced IL-4 mRNA expression was insensitive to the inhibitory effect of db-cAMP and PGE2. Moreover, it appeared that the sensitivity for cAMP-mediated downregulation could not be blocked by stimulation T lymphocytes with alpha CD3/alpha CD28 in the presence of IL-2, IL-7, IL-10, IL-12, or a combination of these cytokines. Finally, it was shown that, in accordance with the mRNA studies, db-cAMP and PGE2 suppressed the IL-4 secretion in Con A- and alpha CD3/alpha CD28-activated T cells. In conclusion, these data show that IL-4 expression is negatively regulated by the protein kinase A-dependent signaling pathway by transcriptional and posttranscriptional mechanisms that depend on costimulatory signals.
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PMID:Interleukin-4 gene expression in activated human T lymphocytes is regulated by the cyclic adenosine monophosphate-dependent signaling pathway. 855 92

Previous reports have indicated that the early induction of interleukin-12 (IL-12), tumor necrosis factor alpha (TNF-alpha), IL-1beta, and IL-10 is crucial for the establishment and regulation of host cell-mediated immunity to the intracellular protozoan parasite Toxoplasma gondii. In this study, we demonstrate that a soluble tachyzoite extract (soluble tachyzoite antigen) can trigger the expression of these four monokines by murine inflammatory macrophages. Further characterization revealed that the parasite molecules in soluble tachyzoite antigen responsible for monokine induction are heat stable at 100 degree C but differ in sensitivity to protease digestion. Thus, the tachyzoite factors that stimulate TNF-alpha and IL-to expression were found to be more resistant to treatment with proteinase K than those responsible for IL-12 and IL-10 induction. Similarly, while the factors responsible for the induction of all four monokines were found to be sensitive to periodate oxidation, the TNF-alpha-stimulating activity was partially resistant to treatment with the compound at a low concentration (1 mM). A further dichotomy in monokine induction signals was inferred from experiments with isoquinoline sulfonamide protein kinase inhibitors. The latter work suggested that the pathways for TNF-alpha and IL-1beta are protein kinase C dependent, while expression of IL-12 and expression of IL-10 share distinct signal transduction mechanisms involving other kinases. Together, these data argue that monokine induction by T. gondii is mediated by glycoproteins that may belong to distinct groups in terms of their biochemical properties and intracellular signaling pathways.
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PMID:Biochemical characterization and protein kinase C dependency of monokine-inducing activities of Toxoplasma gondii. 867 1

The authors analysed the effect of protein kinase A (PKA) activation on the protein synthesis and secretion in the T-helper 2 cell line D10.G4.1 (D10) using an assay that allows the detection of almost all secreted proteins of a cell. IL-4 and IL-10 were quantified. Three groups of secretory products could be defined. The T-cell receptor (TCR)-induced production of the first group (A) of proteins including IL-4 was enhanced by low concentrations of PKA activators. At higher concentrations the enhancement was less marked. The synthesis and secretion of a second group (B) of proteins including IL-10 remained unaffected. The production of a third group (C) of proteins was inhibited in a concentration-dependent manner. Biochemical analysis revealed a block of phospholipase C gamma (PLC gamma) activity by PKA activators. When D10 cells were stimulated by a phorbol ester plus calcium ionophore the production of group A proteins was enhanced almost fourfold, whereas production of group B proteins was unaffected by PKA activation. This effect was observed at all concentrations of various PKA activators tested. The secretion of group C proteins was no longer inhibited. The same results were obtained when analysing IL-4 and IL-10 m-RNA by Northern blotting. The data demonstrate a lymphokine specific mode of action on a single cell basis. Furthermore, it suggests that the inhibitory action of PKA in D10 cells is due partly to blocking of PLC gamma activity.
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PMID:Differential effect of the activation of protein kinase A on the protein synthesis and secretion in the T-helper 2 cell line D10.G4.1. 871 28

Lymphokines produced by non-transformed Th clones, Th1 and Th2, were classified into three groups based on their patterns of expression by different stimuli: Group I, GM-CSF and IL-2, characterized by a strict requirement of activation of both the PKC- and calcium-dependent pathways; Group II, IFN-gamma, IL-3, and IL-4, partially induced by calcium ionophore alone; and Group III, IL-5, IL-6, and IL-10, partially induced by either PMA or calcium ionophore alone. Transfection of constitutively active PKC or p21ras replaced the requirement for PMA in expression of these lymphokines, with the exception of GM-CSF. Production of Group II lymphokines was partially induced by constitutively active calcineurin. Production of Group I and II lymphokines was highly sensitive to cyclosporin A, while Group III lymphokines were relatively resistant. Addition of prostaglandin E2 (PGE2) and overexpression of catalytic subunit of protein kinase A inhibited lymphokine production in Th1 cells, but not in Th2 cells, with the exception of GM-CSF. Production of Group III lymphokines induced by PMA alone was upregulated by PGE2, but that of Group II and III lymphokines induced by calcium ionophore alone was not affected. These results suggest that one of the targets of PGE2 is downstream of the PKC-dependent pathway.
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PMID:Signal transduction in Th clones: target of differential modulation by PGE2 may reside downstream of the PKC-dependent pathway. 872 62

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

Cholera toxin (CT) is a potent mucosal adjuvant and is widely used for vaccine studies in animal models. However, there have been few studies that describe the immunomodulating effects of CT on cells of the human immune system. In this study, the immunomodulatory properties of CT on human peripheral blood mononuclear cells (PBMC) were examined to gain insights to its effects on cells of the human immune system. CT induced production of immunostimulating (IL-1 beta and IL-6) and immunosuppressive (IL-10) cytokines by PBMC. However, the dose-response curve of its cytokine-inducing activity did not correlate well with the concentrations of intracellular cAMP generated by varying doses of CT. the CT mode of action on human PBMC, regarding induction of these cytokines, was clarified by the use of inhibitors of adenyl cyclase, protein kinase A (PKA), and protein kinase C (PKC). 2',3'-Dideoxyadenosine, which inhibits adenyl cyclase activity, reduced IL-1, IL-6, and IL-10 levels by 29, 15, and 28% respectively. HA1004, an inhibitor of PKA, reduced the IL-1 and IL-6 levels by 29 and 27%, respectively. The PKC inhibitor, H7, completely blocked the induction of all three cytokines by CT, suggesting a cAMP-independent mode of action for CT on human PBMC. These observations suggest that CT induces immunomodulating cytokines from human PBMC via the PKC pathway.
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PMID:Evidence for protein kinase C pathway in the response of human peripheral blood mononuclear cells to cholera toxin. 896 84

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

Expression of cytokines by T lymphocytes is a highly balanced process, involving stimulatory and inhibitory intracellular signalling pathways. In the present work, we attempted to clarify the role of cAMP on interferon-gamma (IFN-gamma), interleukin (IL)-10, IL-4 and IL-13 expression as well as on the inducible nitric oxide synthase (iNOS) expression. Treatment of phytohaemagglutinin (PHA)/phorbol 12-myristate 13-acetate (PMA)-activated Jurkat cells with either dibutyryl-cyclic adenosine monophosphate (cAMP) or pentoxifylline induced a strong inhibition of IFN-gamma mRNA expression as measured by reverse transcription (RT)-polymerase chain reaction (PCR), without affecting IL-10 expression. Both cholera toxin and prostaglandin E2 (PGE2) induced a strong inhibition of IFN-gamma mRNA expression, whereas IL-10 mRNA expression was significantly enhanced. This differential regulation of IFN-gamma and IL-10 expression was related to intracellular cAMP concentration. IL-13 and IL-4 mRNA expressions were not inhibited. We developed a new method based on immunofluorescence for intracellular cytokine detection followed by optical and computerized image processing, and our results showed that IFN-gamma protein was strongly inhibited when cells were treated with PGE2 or dibutyryl (db)-cAMP, whereas IL-10 protein was enhanced. This suggests that cAMP exerts its action at both the transcriptional and protein levels. iNOS mRNA expression was markedly elevated in the presence of PGE2. The generation of nitric oxide using sodium nitroprusside (SNP) induced a dramatic decrease of IFN-gamma, while IL-10 was enhanced; and conversely the inhibition of iNOS activity using 1-NG-monomethyl arginine (1-NMMA) induced a clear inhibition of IL-10 and IL-4, while IFN-gamma was enhanced. These results provide evidence that the protein kinase A (PKA) activation pathway plays a prominent role in the balance between the type 1 and type 2 cytokine profile in PHA/PMA-activated Jurkat cells. Data also suggest that iNOS expression is under the control of PKA activation, and that NO seems to be able to assume the polarization of activated T cells to the type 2 profile.
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PMID:Differential regulation of IFN-gamma, IL-10 and inducible nitric oxide synthase in human T cells by cyclic AMP-dependent signal transduction pathway. 930 24


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