Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitric oxide (NO) synthesis is upregulated during chronic hepatic inflammation. The present study characterized the mechanisms involved in the induction of NO production and inducible NO synthase (iNOS) messenger RNA (mRNA) expression in murine embryonic liver cell line, BNL CL.2 cells. No production by BNL CL.2 cells was induced by interferon-r (IFN-r) plus lipopolysaccharide (LPS). However, other inflammatory cytokines such as interleukin (IL)-beta, tumor necrosis factor alpha (TNF-alpha), and IL-6 had no additional effects on it. The stimulatory effects of IFN-r and LPS were time- and dose-dependent. NO secretion was inhibited by treatment with inducible NOS inhibitors such as NG-monomethyl L-arginine, NG-amino-L-arginine, and diphenylene iodonium. iNOS mRNA was induced 3 hours after IFN-r plus LPS treatment, and iNOS expression was maximal in the presence of IFN-r and LPS. The protein tyrosine kinase inhibitors such as genistein and tyrphostin reduced IFN-r plus LPS-induced iNOS mRNA expression and NO production. In contrast, the inhibitors of protein kinase C, protein kinase A, and protein phosphatases did not affect iNOS expression induced by IFN-r plus LPS. In addition, iNOS mRNA expression was completely blocked by treatment with tyrphostin. However, mRNA expression of an early response gene, JunB, and constitutively expressed genes beta-actin and GAPDH were not inhibited by tyrphostin. Furthermore, tyrphostin inhibited the promoter activation of iNOS gene induced by IFN-gamma plus LPS, and it also suppressed IFN-gamma plus LPS-induced nuclear factor-kappa B-binding activity but not AP-1-binding activity. These results suggest that NO production and iNOS mRNA expression in this cell line is dependent on protein tyrosine kinases but does not require protein kinase C, protein kinase A, or protein phosphatases.
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PMID:Roles of tyrosine kinases in the regulation of nitric oxide synthesis in murine liver cells: modulation of NF-kappa B activity by tyrosine kinases. 909 97

Raf kinase is an important intracellular mediator in T cell signalling and may be crucial for the proliferation of this inflammatory cell. In order to elucidate its effect on cytokine production by human T cells in response to T cell receptor activation, experiments were carried out on human T cell clones using antisense (AS) oligodeoxynucleotides (ODN) to inhibit the expression of Raf kinase. AS ODN to Raf were shown to have a significant effect on a human Th1-like T cell clone, inhibiting antiCD3-induced IFN-gamma secretion by 76%, whereas no inhibitory effect was observed on IL-5 or IL-4 production by a Th2-like clone. IL-2 secretion from both clones was also not affected by the Raf AS ODN. In all cases, a reduction in Raf kinase within the cell was demonstrated by Western blot. Our results clearly demonstrate the importance of Raf kinase in the production of IFN-gamma from Th1 cells, but also show the lack of effect of this intracellular mediator on cytokine (IL-5, IL-4) release from Th2 cells.
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PMID:IFN-gamma production from human Th1 cells is controlled by Raf kinase. 913 May 47

Zinc is a trace element which is essential for immune functions. It directly induces monokine secretion by monocytes; however, effects of zinc on T cells appear contradictory. Apart from enhanced lymphocyte proliferation in peripheral blood mononuclear cells (PBMC), inhibitory properties of high zinc dosages have also been described. In this study, PBMC failed to produce lymphokines like interferon (IFN)-gamma after stimulation with zinc in a serum- and LPS-free cell culture system, whereas monokine secretion [interleukin (IL)-1 beta] occurred. Zinc-uptake studies with the zinc-specific fluorescent probe zinquin revealed that zinc is taken up by PBMC within a few minutes, reaching nearly equal levels in PBMC, isolated monocytes, and T cells. However, if zinc was depleted 1 h after monocyte induction, zinc-free pre-cultured T cells were stimulated to secrete IFN-gamma by zinc-induced monokines. Furthermore, the necessity for a cell-cell interaction between monocytes and T cells for IFN-gamma induction was elucidated. Zinc ions inhibited the proliferation of the IL-1-dependent T cell line D 10N in a dose-dependent manner, suggesting a direct inhibitory effect of zinc. By immunoprecipitation we revealed a specific inhibition of IL-1 receptor-associated protein kinase (IRAK) by zinc ions. Therefore, in contrast to an indirect stimulation of T cells due to zinc-induced monokines, higher concentrations of zinc directly inhibit T cell functions by means of specific inhibition of IRAK and subsequent signaling events such as NF kappa B activation. The divergent effects of zinc on different cell populations, depending on the zinc concentration, could explain contradictory results of zinc stimulation. Furthermore, our data suggest new strategies of specific zinc-mediated immune modulation.
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PMID:Zinc inhibits interleukin-1-dependent T cell stimulation. 936 6

Human endothelial cells are injured by the action of leukocytes. We investigated the role of nitric oxide (NO) in the induction of injury to human pulmonary artery endothelial cells. NO has been a putative source of cytotoxic reactive oxygen species in some settings. Incubation of endothelial cells with neutrophils increased the release of lactate dehydrogenase activity and preloaded fura-2 from endothelial cells, indicating that neutrophils induce endothelial cell injury. This effect was augmented by treatment with carboxy-PTIO, which traps NO in the medium, or with L-NAME, an inhibitor of NO synthase. When endothelial cells were incubated with neutrophils stimulated by phorbol myristate acetate, an activator of protein kinase C, endothelial cell damage was further enhanced and the amount of NO in the medium was decreased. Dibutyryl cyclic AMP, a cell-permeable analogue of cyclic AMP, protected against neutrophil-induced endothelial cell injury and increased NO release into the medium. The effects of dibutyryl cyclic AMP were abrogated by treatment with H-89, a potent inhibitor of cyclic AMP-dependent protein kinase. The protective effect on neutrophil-induced endothelial cell injury by dibutyryl cyclic AMP was abolished by addition of carboxy-PTIO or L-NAME. Thus, our studies suggest that NO, presumably released from endothelial cells, protects against endothelial injury by activated neutrophils and the protective effect by cyclic AMP during coculture with activated neutrophils is mediated through the action of NO. However, when monocytes activated by lipopolysaccharide and IFN-gamma were used instead of neutrophils, endothelial cells were likewise injured, but a much higher level of NO was detected and injury was diminished by addition of carboxy-PTIO to the medium. These observations suggest that the high levels of NO released by activated monocytes contribute to endothelial injury, whereas low levels of NO protect endothelial cells against injury by neutrophils.
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PMID:The role of nitric oxide in human pulmonary artery endothelial cell injury mediated by neutrophils. 941 36

This study was undertaken to investigate the effects of propranolol, IFN-beta, and the protein kinase modulators on IFN-gamma induction of MHC class II antigen expression and cytokine production in THP-1 human monocytic cells. IFN-gamma induced expression of HLA-DR and DQ molecules and secretion of the monokines IL-1 beta and TNF-alpha in THP-1 cells in a time and dose-dependent manner. The effect of INF-gamma on class II HLA antigens was dose-dependently inhibited by IFN-beta. H-7, phloretin, staurosporine as well as GF 109203X are selective enzyme inhibitors of protein kinase C (PKC), down-regulating IFN-gamma induced MHC class II expression and cytokine production. Stimulators of PKC, like PMA, replaced IFN-gamma in the induction of monokines in THP-1 cells, whereas the addition of HA 1004 or arachidonic acid to the culture had no effect on IFN-gamma mediated changes. Blocking of phospholipase D (PLD)-derived diacylglycerol (DAG) formation by propranolol abrogated IFN-gamma increased HLA class II expression and IL-1 beta secretion, but had little effect on IFN-gamma induced TNF-alpha production. These findings appear to suggest that PLD-derived phosphatidate is not the primary source of DAG production in IFN-gamma-induced TNF-alpha secretion, but may be necessary for IFN-gamma-mediated MHC class II induction and IL-1 beta production in human monocytes, whereas phospholipase A2 may not be required for IFN-gamma activation of PKC in the process.
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PMID:Effect of propranolol and IFN-beta on the induction of MHC class II expression and cytokine production by IFN-gamma IN THP-1 human monocytic cells. 954 99

Phagocyte functions are markedly inhibited after infection with the intracellular protozoan parasite Leishmania. This situation strongly favors the installation and propagation of this pathogen within its mammalian host. Previous findings by us and others have established that alteration of several signaling pathways (protein kinase C-, Ca2+- and protein-tyrosine kinases-dependent signaling events) were directly responsible for Leishmania-induced macrophage (MO) dysfunctions. Here we report that modulation of phosphotyrosine-dependent events with a protein tyrosine phosphatases (PTP) inhibitor, the peroxovanadium (pV) compound bpV(phen) (potassium bisperoxo(1,10-phenanthroline)oxovanadate(Vi)), can control host-pathogen interactions by different mechanisms. We observed that the inhibition of parasite PTP resulted in an arrest of proliferation and death of the latter in coincidence with cyclin-dependent kinase (CDK1) tyrosine 15 phosphorylation. Moreover the treatment of MO with bpV(phen) resulted in an increased sensitivity to interferon-gamma stimulation, which was reflected by enhanced nitric oxide (NO) production. This enhanced IFN-gamma-induced NO generation was accompanied by a marked increase of inducible nitric oxide synthase (iNOS) mRNA gene and protein expression. Finally we have verified the in vivo potency of bpV(phen) over a 6-week period of daily administration of a sub-toxic dose. The results revealed its effectiveness in controlling the progression of visceral and cutaneous leishmaniasis. Therefore PTP inhibition of Leishmania and MO by the pV compound bpV(phen) can differentially affect these eukaryotic cells. This strongly suggests that PTP plays an important role in the progression of Leishmania infection and pathogenesis. The apparent potency of pV compounds along with their relatively simple and versatile structure render them attractive pharmacological agents for the management of parasitic infections.
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PMID:Modulation of interferon-gamma-induced macrophage activation by phosphotyrosine phosphatases inhibition. Effect on murine Leishmaniasis progression. 959 43

To explore the role of sympathetic nervous system activation in HIV pathogenesis, we examined the effect of the neuroeffector molecule norepinephrine (NE) on HIV-1 replication in quiescently infected PBMCs that were subsequently activated with Abs to CD3 and CD28. NE accelerated HIV-1 replication at concentrations ranging from 10(-8) to 10(-5) M. This effect could be mimicked by protein kinase A (PKA) activators (forskolin or dibutyryl-cAMP) and abrogated by beta-adrenoreceptor antagonists or the PKA inhibitor rp-cAMP, indicating transduction via the adrenoreceptor signaling pathway. NE reduced cellular activation and altered the production of several HIV-modulating cytokines: IL-10 and IFN-gamma were markedly suppressed; TNF-alpha, IL-1beta, IL-2, IL-4, and IL-6 were mildly suppressed; and levels of IL-12 were not significantly altered. The addition of either exogenous IFN-gamma or IL-10 abrogated the effect of NE on virus production. Thus PKA-dependent suppression of cytokine production appears to mediate the enhancement of HIV-1 replication by NE.
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PMID:Norepinephrine accelerates HIV replication via protein kinase A-dependent effects on cytokine production. 967 Sep 34

We recently demonstrated that different CD45 monoclonal antibodies (mAb) are able to induce cellular aggregation in human peripheral blood mononuclear cells (PBMC) through LFA-1/ICAM-1 interactions. Such interactions could be down-modulated by protein kinase (PK) A/G inhibitors, but were unaffected by inhibitors of PKC, suggesting the involvement of PKA or PKG in CD45 mAb-induced adhesion. In this study we show that after incubation of PBMC with several (but not all) mAb to CD45, CD45RO and CD45RA, intracellular cAMP, but not cGMP concentrations readily increase, reaching a maximum 30 min after start of activation. As evidenced by several lines of investigation cAMP accumulation was independent of Fc receptor-associated signaling as well as tyrosine phosphatase activity of CD45. In highly pure T lymphocytes, CD45 mAb were unable to induce cAMP synthesis, but readily did so after addition of autologous monocytes. After paraformaldehyde fixation of both quiescent or IFN-gamma/TNF-alpha-preactivated monocytes, cAMP production was no longer detectable, suggesting monocytes as the cell of origin for the increased cAMP synthesis. Further, cAMP accumulation in monocytes occurred after reconstitution to T lymphocytes preincubated with CD45 mAb and extensively washed. Importantly, pretreatment of T lymphocyte/monocyte mixtures with LFA-1 mAb and/or ICAM-1 mAb down-regulated CD45 mAb-induced cAMP synthesis. Finally, we demonstrate that CD45 mAb are not only capable of inducing cAMP production, but also of directly stimulating PKA enzyme activity. Based on the data presented, we propose that CD45 signaling in T lymphocytes subsequently activates cAMP accumulation and PKA activation in monocytes via LFA-1/ICAM-1-dependent cellular interactions.
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PMID:Epitope-specific signaling through CD45 on T lymphocytes leads to cAMP synthesis in monocytes after ICAM-1-dependent cellular interaction. 971 Feb 8

The double-stranded RNA-dependent protein kinase (PKR) is a serine/threonine kinase that plays an important role in the antiviral activities of interferon (IFN). To determine the organization and regulation of the PKR locus, lambda phage and bacterial artificial chromosome (BAC) clones containing the human PKR gene were isolated. Characterization of these clones revealed that PKR has 17 exons and 16 introns dispersed in a genomic region of 50 kb. Sequence analysis of the PKR 5'-flanking region identified a canonical IFN-stimulated response element (ISRE), GAAAACGAAACT. Transient transfection of PKR promoter constructs linked to a luciferase reporter gene into human T98G cells indicated that this 5'-flanking region is capable of functioning as a basal promoter that is also inducible by IFN-alpha and IFN-beta but not IFN-gamma. Interestingly, the PKR gene contains a polymorphic CGG trinucleotide repeat in exon 1. In addition, four PKR alleles, varying in repeat number from 7 to 10, were detected in 30 individual chromosomes. The PKR gene undergoes alternative splicing of exon 2, which gives rise to two forms of 5'-untranslated exons of different length. Although the human and murine PKR proteins have high homology, comparison of their gene structures reveals divergence in 5'-flanking regions, suggesting distinct regulation at the genomic level.
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PMID:Genomic features of human PKR: alternative splicing and a polymorphic CGG repeat in the 5'-untranslated region. 972 42

To study the oncogenic role of the p210(bcr-abl) fusion protein in chronic myelogenous leukemia cells, we generated a mouse cell line that was stably transfected with and overexpressed the human p210(bcr-abl) fusion protein. We then looked for phosphorylation activation of the Janus-activated kinase (JAK) family of tyrosine-specific protein kinases by the p210(bcr-abl) fusion protein. We found that JAK1, which has been shown by others to be associated with the IFN-alpha and -gamma plasma membrane receptors, was phosphorylated to a much greater degree in cells containing the p210(bcr-abl) fusion protein than was the case in the original, untransfected cell line. In contrast, no phosphorylation of the JAK2 kinase, which is associated with the IFN-gamma but not IFN-alpha receptor, was observed either with or without p210(bcr-abl) protein. A substrate of JAK1, STAT1 (signal transducers and activators of transcription 1), was found to be phosphorylated in cells containing overexpressed p210(bcr-abl) fusion protein. These results indicate that the presence of the p210(bcr-abl) protein kinase within a cell is associated with phosphorylation of the JAK1 kinase and its substrate STAT1.
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PMID:Potential role of bcr-abl in the activation of JAK1 kinase. 981 65


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