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)

The adherence of tumour cells to microvascular endothelium is believed to be a necessary step in their migration to sites of metastasis. It has been proposed that this process occurs when cell surface molecules on tumour cells bind to complementary sites on endothelial cells. The expression of these endothelial-derived cell adhesion molecules appears to be modulated by cytokines, a broad class of protein mediators which play important roles in immune and inflammatory reactions. It has been found by ourselves and others that exposure of endothelium to some cytokines augments the adhesion of inflammatory cells as well as tumour cells in in vitro assays. We used a murine model consisting of P815 mastocytoma cells and microvascular endothelium and found that pretreatment of endothelial monolayers with TNF-alpha, IL-1, LPS or PMA augmented the number of tumour cells that attach in a dose-dependent fashion. FACS analysis showed that the change in binding was due to an increase in the expression of VCAM-1 on the surface of the endothelial cell. Methylxanthines (caffeine and theophylline) as well as "classical" calcium-mobilizing agents (ionomycin and thapsigargin) inhibited the expression of VCAM-1 in MME. We also studied the possible mechanisms of TNF-alpha signal transduction in endothelial cells. We examined the involvement of protein kinases in the TNF-alpha effect. Although we found that inhibitors of PKC could inhibit the TNF-alpha effect, our studies suggest that the "classical" PKC pathway is not completely responsible for signaling since TNF-alpha did not cause translocation of PKC to the cell membrane and its effect could not be completely mimicked by PMA. We also studied the effect of TGF-beta on the binding of tumour cells to endothelium. Exposure of endothelium to TGF-beta led to the inhibition of both basal and TNF-alpha enhanced binding of P815 cells. Inhibitors of G-proteins do not abolish TGF-beta action, and PKC and PKA activators elicit an opposite effect. However, TGF-beta-mediated inhibition of both basal binding and TNF-alpha-enhanced P815 binding to endothelium is completely abolished in the presence of the protein phosphatase inhibitor okadaic acid suggesting that TGF-beta elicits its effect by stimulating protein phosphatase activity.
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PMID:Effect of cytokines on tumour cell-endothelial interactions. 934 51

The purpose of this study was to examine whether rCGRP has effects on TNF-alpha produced by mouse resident peritoneal macrophages. Macrophages were obtained from the peritoneal exudate of male Balb/c mouse. The cells were plated on culture dishes at a density of 2.5x10(5) cells per well and allowed to adhere for 2 hr. Pretreatment with rCGRP (10 nM-1 microM) for 24 hr, the macrophages were cultured with LPS 1 microg/ml for another 24 h. The medium was harvested for measuring TNF-alpha by ELISA kits. The results showed that rCGRP had no direct effects on TNF-alpha production, but it inhibited LPS-induced TNF-alpha production in a concentration-dependent manner. When rCGRP was at a concentration of 1 microM, the LPS-induced TNF-alpha production was inhibited by 39%. The effect of rCGRP was reversed by hCGRP(8-37) (10 microM), an antagonist of CGRP1 receptor. The LPS-induced TNF-alpha production from macrophages was also inhibited by forskolin 3 microM, an activator of adenylate cyclase. Furthermore, pretreatment with H-89 1 microM or Rp-cAMPS 100 microM, the inhibitors of cAMP-dependent protein kinase, the effect of rCGRP was abolished. These data suggest that the LPS-induced TNF-alpha production is inhibited by rCGRP via activation of cAMP responses in mouse resident peritoneal macrophages.
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PMID:Inhibition of LPS-induced TNF-alpha production by calcitonin gene-related peptide (CGRP) in cultured mouse peritoneal macrophages. 936 15

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

The cell cycle events accompanying TGF-beta1-induced growth arrest of normal mouse resting B lymphocytes stimulated by LPS were investigated. We showed that TGF-beta1 prevents the retinoblastoma protein (pRb) phosphorylation and induces growth arrest in mid- to late G1. To explore the molecular basis of the effect of TGF-beta1, we analyzed the in vitro kinase activities of cyclin/cyclin-dependent kinase (cdk) complexes involved in the progression through G1 phase and in the G1/S transition, by using the glutathione S-transferase-pRb fusion protein as a substrate. Cdk2-associated kinase activity was strongly induced in mitogen-treated B cells. It was dramatically inhibited by TGF-beta1 as were the cyclin E- and cyclin A-dependent kinase activities. TGF-beta1 treatment had no significant effect on the expression of two G1/S phase proteins, cyclin E and cdk2. In contrast, the appearance of cyclin A, occuring in late G1 phase, was almost totally inhibited by TGF-beta1. We also showed that expression of the cdk inhibitor protein p27Kip1 decreased as cells progressed through the G1 phase. An accumulation of p27 was found in TGF-beta1-treated cells, showing that TGF-beta1 prevented LPS-induced decline of p27. Finally we found that the lack of kinase activity associated with cyclin E/cdk2 complexes was correlated with increased amounts of cdk2- and cyclin E-bound p27. Overall, these results suggest that both cyclin A and cdk2 may be active participants in the TGF-beta1-induced cell cycle arrest in normal mouse B cells and indicate the involvement of p27 in this mechanism.
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PMID:Effect of TGF-beta1 on cell cycle regulatory proteins in LPS-stimulated normal mouse B lymphocytes. 937 8

Several cytokines and LPS regulate the population of the B1 receptors (B1Rs) for kinins; these are responsive to des-Arg9-bradykinin (BK) and Lys-des-Arg9-BK. B1R activation contributes to inflammatory vascular changes and pain. Aortic rings isolated from normal rabbits and incubated in vitro in Krebs physiological medium were used as a model of tissue injury. From a null level of response, these rings exhibit a time- and protein synthesis-dependent increase in the maximal contractile response to des-Arg9-BK. Exposure to exogenous IL-1beta or epidermal growth factor (EGF) considerably increases the process of sensitization to the kinins. Freshly isolated control aortic rings showed high mitogen-activated protein (MAP) kinase activities (persistent activation of p38, but less prolonged for extracellular signal-regulated kinase and c-Jun-N-terminal kinase/stress-activated protein kinase pathways) relatively to the basal activities found in various types of cultured cells. IL-1beta or EGF further increased the activities of the extracellular signal-regulated kinase and c-Jun-N-terminal kinase/stress-activated protein kinase MAP kinases. The inhibitor of the p38 MAP kinase, SB 203580 (10 microM), massively (approximately 75%) and selectively inhibited the spontaneous sensitization to des-Arg9-BK over 6 h. SB 203580 also significantly reduced the development of the response to des-Arg9-BK as stimulated by IL-1 or EGF. Both spontaneous and IL-1beta-stimulated up-regulation of responsiveness to des-Arg9-BK were significantly inhibited by the MAP kinase extracellular signal-regulated kinase kinase 1 inhibitor PD 98059 (approximately 40%). The protein kinase inhibitors failed to inhibit protein synthesis and to acutely inhibit the contractile effect of des-Arg9-BK, suggesting that they do not influence B1 receptor transduction mechanisms. In cultured aortic smooth muscle cells stimulated with EGF, MAP kinase activation preceded B1R mRNA induction. Protein kinase inhibitors reveal the role of cell injury-controlled MAP kinase pathways, and singularly of the p38 pathway, in the induction of B1R.
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PMID:Role of the mitogen-activated protein kinases in the expression of the kinin B1 receptors induced by tissue injury. 957 May 62

The secretion of IL-6 after stimulation of macrophages has been found to play a central role in the regulation of defense mechanism, haematopoiesis, and acute phase reaction. It was reported that cAMP is involved in the regulation of IL-6 production. Since calcitonin gene-related peptide (CGRP) is known to increase cAMP accumulation in mouse macrophages, we examined whether CGRP would induce IL-6 release in macrophages. Macrophages were obtained from the peritoneal exudate of male Balb/c mouse. The cells were plated on culture dishes at a density of 2.5 x 10(5) cells per well and allowed to adhere for 2 h. After incubation for 48 h with two changes of PRMI-1640, the macrophages were cultured with CGRP and LPS 1 microg/ml for 12 h. The IL-6 level in medium was measured by ELISA kits. The results showed that CGRP had no direct effects on IL-6 production, but it potentiated LPS-induced IL-6 production in a concentration-dependent manner. When CGRP was at a concentration of 10(-10) M, the LPS-induced IL-6 production was increased from 5.16 +/- 0.48 to 8.88 +/- 0.48 ng/ml. The effect of CGRP 10(-10) M was reversed by hCGRP(8-37) 10(-8) M, an antagonist of CGRP1 receptor. The LPS-induced IL-6 production from macrophages was also potentiated by forskolin 5 microM, an activator of adenylate cyclase. Furthermore, pretreatment with H-89 1 microM or Rp-cAMPS 100 microM, the inhibitors of cAMP-dependent protein kinase, inhibited the effect of CGRP by 31% and 98%, respectively. These results demonstrate that the LPS-induced IL-6 release is potentiated by CGRP via the activation of cAMP pathway in mouse resident peritoneal macrophages.
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PMID:Calcitonin gene-related peptide potentiates LPS-induced IL-6 release from mouse peritoneal macrophages. 962 64

We recently reported that LPS stimulation of monocytic cells leads to the activation of PU.1, a member of the Ets family of transcription factors. Phosphorylation of PU.1 by protein kinase CK2 was found to up-regulate its trans-activation function, but not its DNA binding activity. Previous studies suggested that Ets proteins could bind to NF-kappa B motifs at the tetrameric core sequence TTCC. In macrophages, LPS-inducible HIV-1 gene expression is mediated in part by binding of NF-kappa B to identical tandem binding sites located within the long terminal repeat (LTR). Thus, we performed additional studies to determine whether PU.1 also played a role in regulating HIV-1 gene expression in macrophages. Our functional studies revealed that activation of the HIV-1 LTR in LPS-stimulated cells requires both NF-kappa B and PU.1. Extensive mutagenesis of the HIV-1 LTR revealed that PU.1-dependent activation requires the Ets motif within the upstream NF-kappa B site, whereas NF-kappa B itself binds to the downstream site. We also found that insertion of five additional nucleotides between the NF-kappa B sites abolished LPS inducibility, suggesting a direct interaction between factors that bind these sites. Lastly, we found that mutation of PU.1 at serine 148, which prevents its phosphorylation by CK2, blocked its ability to activate the HIV-1 LTR in response to LPS. These effects were promoter specific because PU.1 did not affect LPS-inducible activation of a distinct NF-kappa B-dependent promoter. While these data do not demonstrate direct binding of PU.1 to the HIV-1 LTR, they illustrate a novel role for PU.1 in activation of the HIV-1 LTR by LPS.
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PMID:Both PU.1 and nuclear factor-kappa B mediate lipopolysaccharide- induced HIV-1 long terminal repeat transcription in macrophages. 964 33

The aim of the present study was to investigate the role of cAMP in enhanced IL-10 synthesis in human mononuclear cells. Adrenaline is known to act via the alpha- and beta-adrenergic receptors which are coupled to adenylyl cyclase. The effects of cAMP elevation on IL-10 synthesis were studied at the protein level by ELISA and at the level of mRNA by RT/PCR. In this in vitro model adrenaline enhanced the LPS-induced synthesis of IL-10 with parallel suppression of TNF synthesis. These effects were demonstrated both at the protein level and the level of mRNA. To analyze the role of cAMP we antagonized this effect by application of (Rp)-cAMPS, a diastereomer of adenosine-3',5'-cyclic phosphorothioate, known to inhibit competitively the cAMP-induced activation of protein kinase A. Simultaneous addition of adrenaline and (Rp)-cAMPS led to a reversal of IL-10 synthesis to values induced by LPS stimulation alone. The kinetic analysis in LPS-stimulated mononuclear cells revealed a significant delay of IL-10 synthesis starting after 7 h compared with TNF synthesis which showed the first significant increase at 90 min. Finally, the combination of adrenaline and exogenous IL-10 led to a more pronounced suppression of TNF synthesis after LPS stimulation compared to suppression by IL-10 or adrenaline alone. The present results suggest the role of protein kinase A activation for adrenaline-induced IL-10 synthesis in human mononuclear cells. Additionally, based on the kinetic analysis and further experiments described in the literature, endogenous IL-10 could contribute to the adrenaline-induced suppression of TNF synthesis after prolonged incubation. These in vitro results could explain the suppression of TNF plasma concentration after parallel infusion of LPS and epinephrine compared to LPS infusion alone as has been demonstrated in a first human study.
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PMID:Adrenaline enhances LPS-induced IL-10 synthesis: evidence for protein kinase A-mediated pathway. 971 82

Alpha-melanocyte-stimulating hormone (alpha-MSH) is a tridecapeptide found mainly in the brain, pituitary, and circulation. It inhibits most forms of inflammation by a mechanism that is not known. As most types of inflammation require activation of NF-kappa B, we investigated the effect of alpha-MSH on the activation of this transcription factor by a wide variety of inflammatory stimuli. Electrophoretic mobility shift assay showed that alpha-MSH completely abolished TNF-mediated NF-kappa B activation in a dose- and time-dependent manner. It also suppressed NF-kappa B activation induced by LPS, okadaic acid, and ceramide. The effect was specific, as the activation of the transcription factor activating protein-1 by TNF was unaffected. Western blot analysis revealed that TNF-dependent degradation of the inhibitory subunit of NF-kappa B, I kappa B alpha, and nuclear translocation of the p65 subunit of NF-kappa B were also inhibited. This correlated with suppression of NF-kappa B-dependent reporter gene expression induced by TNF. The inhibitory effect of alpha-MSH appeared to be mediated through generation of cAMP, as inhibitors of adenylate cyclase and of protein kinase A reversed its inhibitory effect. Similarly, addition of membrane-permeable dibutyryl cAMP, like alpha-MSH, suppressed TNF-induced NF-kappa B activation. Overall, our results suggest that alpha-MSH suppresses NF-kappa B activated by various inflammatory agents and that this mechanism probably contributes to its anti-inflammatory effects.
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PMID:Alpha-melanocyte-stimulating hormone inhibits the nuclear transcription factor NF-kappa B activation induced by various inflammatory agents. 974 48

Phosphatidylinositol 3-kinase (PI 3-kinase) and protein kinase B are critical players in cell proliferation and survival. Their downstream effector protein kinase, p70 S6 kinase, has an established role in protein translation. The mechanism by which bacterial LPS induces production of nitric oxide (NO) in murine macrophages is incompletely understood, and a role for PI 3-kinase/p70 S6 kinase pathway had not been previously investigated. In this study we demonstrate that LPS induced a fivefold activation of p70 S6 kinase and a twofold stimulation of PI 3-kinase. Pretreatment of Raw 264.7 cells with either rapamycin or Ly290042 completely blocked LPS-induced activation of p70 S6 kinase. Protein kinase B was also activated (twofold) by LPS and was only minimally affected by these inhibitors. PI 3-kinase activity was inhibited by both Ly294002 and wortmannin. The effects on NO production by these agents were strikingly different. While both rapamycin and Ly294002 resulted in almost complete inhibition of NO production, wortmannin was ineffective. Surprisingly, none of the inhibitors reduced the production of the inducible nitric oxide synthase protein (iNOS) as determined by immunoprecipitation. In vivo labeling studies revealed that the iNOS protein was phosphorylated in concordance with the production of NO. We conclude that LPS-mediated NO production occurs via a PI 3-kinase-independent, but FKBP12-rapamycin-associated protein-dependent, pathway in RAW cells by a mechanism probably involving phosphorylation of iNOS.
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PMID:Activation of phosphatidylinositol 3-kinase, protein kinase B, and p70 S6 kinases in lipopolysaccharide-stimulated Raw 264.7 cells: differential effects of rapamycin, Ly294002, and wortmannin on nitric oxide production. 986 29


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