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)

Signals transduced via the TCR activate the transcription factor nuclear factor-kappaB (NF-kappaB), which, in turn, is critical to the transcriptional induction of many genes important for the proliferation and expression of a differentiated phenotype. Treatment of T cells with the protein kinase C activator PMA in combination with Ca2+ ionophores mimics this process, and the two agents are often substituted for TCR stimulation, bypassing the TCR. Here we identify intracellular signaling components involved in activation of NF-kappaB following TCR stimulation. TCR signaling was triggered by treating Jurkat T cells with PHA or anti-CD3 Abs, and NF-kappaB activation was monitored by electrophoretic mobility shift assays and/or by kappaB-dependent reporter assays. Contrary to the idea that protein kinase C is involved in TCR-mediated activation of NF-kappaB, high doses of staurosporine did not interfere with activation of NF-kappaB by PHA, while the same dose of staurosporine completely blocked activation by PMA. PHA-induced kappaB-dependent reporter activity was, however, effectively blocked by a dominant negative form of Raf-1, suggesting a critical role for a Raf kinase. The TCR-mediated activation of NF-kappaB was also dependent on a Ca2+ influx, because the Ca2+ channel blocker, SK&F 96365, as well as other agents that prevented the Ca2+ influx, inhibited NF-kappaB activation. Cotransfection of a constitutively active form of calcineurin largely substituted for the Ca2+ requirement and reversed the blockade by SK&F 96365. Consistent with these observations, coexpression of constitutively active forms of Raf-1 and calcineurin synergistically induced kappaB-dependent reporter activity, suggesting a physiologically relevant functional interaction between the kinase and the phosphatase.
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PMID:Activation of nuclear factor-kappaB via T cell receptor requires a Raf kinase and Ca2+ influx. Functional synergy between Raf and calcineurin. 895 73

The nef gene of the human and simian immunodeficiency viruses (HIV and SIV) encodes a 27 to 34 kDa myristoylated protein that induces downregulation of CD4 from the cell surface and enhances virus infectivity. As shown by experiments on SIV-infected adult macaques, Nef is important in pathogenesis and disease progression. In vitro, protein kinase C (PKC) phosphorylates Nef, but the role of phosphorylation in the function and expression of this protein has not yet been determined. Here we show that in HIV type 1-infected cells, phosphorylation of Nef increased 8- to 12-fold after treatment with phorbol myristate acetate and phytohemagglutinin (PMA/PHA). Basal and PMA/PHA-induced phosphorylation occurred on serine residues of Nef and was independent of other HIV proteins. The PMA/PHA-induced phosphorylation of Nef was inhibited by bisindolylmaleimide I, a potent and specific inhibitor of PKC, but was unaffected by H89, an inhibitor of protein kinase A. In contrast, treatment with bisindolylmaleimide I did not affect the basal level of Nef phosphorylation, suggesting two different phosphorylation pathways. A PMA-insensitive CD4 mutant in which three serine residues in the cytoplasmic domain have been replaced by alanines was used to determine whether PMA-induced phosphorylation affects Nef-induced CD4 downregulation. In Nef-expressing cells, treatment with PMA enhanced downregulation of the CD4 serine triple mutant from the cell surface, suggesting that phosphorylation is important for Nef function.
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PMID:Induction of phosphorylation of human immunodeficiency virus type 1 Nef and enhancement of CD4 downregulation by phorbol myristate acetate. 903 96

tpl-2 is a rat gene that encodes a serine/threonine protein kinase that can act as a novel mitogen-activated protein (MAP) kinase kinase kinase. Tpl-2 is activated in Moloney murine leukemia virus-induced rat T lymphomas, due to a truncation in the C-terminal region of the protein. cot is a very closely related gene, if not the human homologue. The truncated form of Cot has been shown to have a higher transforming activity than the nontruncated form. In this paper we show that an increase in truncated Cot kinase expression correlates with an increase in IL-2 production in anti-CD3-treated Jurkat cells. Truncated Cot expression also cooperates with PHA or phorbol 12,13-dibutyrate (PDBu) and calcium ionophore for IL-2 production in Jurkat cells. Both the truncated and nontruncated Cot forms increased IL-2 transcription because they enhanced transcription of a reporter gene linked to the IL-2 promoter. The expression of a dominant negative form of Cot inhibits transcription directed by the IL-2 promoter in Jurkat cells stimulated by PDBu and ionophore. These data suggest a role of Tpl-2/Cot kinase in IL-2 production during T lymphocyte activation and could also explain its role in Moloney murine leukemia virus-induced lymphomagenesis.
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PMID:Cot kinase regulation of IL-2 production in Jurkat T cells. 925 20

The BCR/ABL fusion protein transforms myeloid stem cells. Both chronic myelogenous leukemias (CML) and a subset of acute lymphoblastic leukemias (ALL) are associated with the expression of BCR/ABL proteins. This knowledge has not yet been translated into any specific tool to control ABL driven neoplastic cells growth. CGP57148B is an ATP-competitive inhibitor of the ABL protein kinase; it has been shown to inhibit the kinase activity of ABL both in vitro and in vivo and to inhibit the growth of v-abl and bcr/abl transfectants, as well as the in vitro formation of bone marrow (BM)-derived colonies in the presence of growth factors in some CML patients. These studies were performed to investigate the activity of CGP57148B on the spontaneous proliferation of both fresh and cultured, leukemic and normal, BCR/ABL positive and negative cells, and to study its mechanism of action. Six cell lines derived from BCR/ABL+ leukemias (K562, BV173, KCL22, KU812, MC3, LAMA84), thirteen BCR/ABL negative lines, both neoplastic (KG1, SU-DHL-1, U937, Daudi, NB4, NB4.306) and derived from normal cells (PHA blasts, LAK, fibroblasts, LCL, renal epithelial cells, endothelial cells, CD34(+) cells), and 14 fresh leukemic samples were tested using a tritiated thymidine uptake assay. The in vivo phosphorylation of the BCR/ABL protein was evaluated by western blot, while apoptosis was detected by the annexin V/propidium binding test. The induction of differentiation was assayed by immunofluorescence using multiple antibodies. All six BCR/ABL+ lines showed a dose dependent inhibition of their spontaneous proliferative rate, which was not accompanied by differentiation. The treatment caused, within minutes, dephosphorylation of the BCR/ABL protein, followed in 16-24 hours by a decrease in cycling cells and induction of apoptosis. No significant inhibition of DNA synthesis was observed in any BCR/ABL negative normal or neoplastic line at concentrations </=3 microM, with the exception of fibroblasts and CD34 cells. Proliferation inhibition was observed also when using fresh samples obtained from two Ph+ ALL and 12 consecutive CML patients. Induction of apoptosis was observed in these samples too. The activity of CGP57148B can be monitored in ex vivo isolated or cultured cells using a simple and reproducible assay, without the need for exogenously added growth factors. This molecule possibly exerts its effects through the inhibition of the kinase activity of BCR/ABL and the subsequent initiation of apoptosis, without inducing cell differentiation. Some normal cells are also affected. These data support the use of CGP57148B in initial clinical studies; possible toxic effects on BM and fibroblast-derived cells will have to be closely monitored. The in vivo monitoring of patients will have to be focused on the induction of apoptosis in leukemic cells.
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PMID:Inhibition of the ABL kinase activity blocks the proliferation of BCR/ABL+ leukemic cells and induces apoptosis. 944 52

The analysis of T-cell activation and- proliferation previously identified a renaturable protein kinase activity of 55-60 kDa (PK55) that was associated with growth arrest in T cells and other differentiated immune cell types. For further studies of this protein a rapid purification procedure was developed using preparative isoelectric focusing (IEF) and High Performance Electrophoretic Chromatography (HPEC). Near homogeneous purification of PK55 was attained using this two-step approach. Purified PK55 was used for the production of monoclonal antibodies via in vitro antigen presentation to murine splenocytes. The result of this approach yielded a single hybridoma (3B1) with high reactivity toward PK55 by ELISA. Monoclonal antibody 3B1 recognized denatured PK55 on ELISA as well as immunoblot but failed to react with the native protein. Analysis of 3B1 immunoblots of untreated or 72-h PHA-cultured T cells shows reactivity with a single 55-60 kDa (PK55) protein in untreated cells and additional reactivity to a 45 kDa protein as well as PK55 in PHA treated cells. Further analysis using monoclonal 3B1 reveals that PK55 activity is regulated by a mechanism that is distinct from changes in PK55 expression.
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PMID:Purification of the renaturable protein kinase PK55 by preparative isoelectric focusing and high performance electrophoretic chromatography and the generation of PK55 monoclonal antibodies by in vitro B cell stimulation. 945 1

Depletion of guanine nucleotide pools after inhibition of inosine monophosphate dehydrogenase (IMPDH) potently inhibits DNA synthesis by arresting cells in G1 and has been shown to induce the differentiation of cultured myeloid and erythroid cell lines, as well as chronic granulocytic leukemic cells after blast transformation. Inhibitors of IMPDH are also highly effective as immunosuppressive agents. The mechanism underlying these pleiotropic effects of depletion of guanine nucleotides is unknown. We have examined the effects of mycophenolic acid (MPA), a potent IMPDH inhibitor, on the cell cycle progression of activated normal human T lymphocytes. MPA treatment resulted in the inhibition of pRb phosphorylation and cell entry into S phase. The expression of cyclin D3, a major component of the cyclin-dependent kinase (CDK) activity required for pRb phosphorylation, was completely abrogated by MPA treatment of T cells activated by interleukin-2 (IL-2) and leucoagglutinin (PHA-L), whereas the expression of cyclin D2, CDK6, and CDK4 was more mildly attenuated. The direct kinase activity of a complex immunoprecipitated with anti-CDK6 antibody was also inhibited. In addition, MPA prevented the IL-2-induced elimination of p27(Kip1), a CDK inhibitor, and resulted in the retention of high levels of p27(Kip1) in IL-2/PHA-L-treated T cells bound to CDK2. These results indicate that inhibition of the de novo synthesis of guanine nucleotides blocks the transition of normal peripheral blood T lymphocytes from G0 to S phase in early- to mid-G1 and that this cell cycle arrest results from inhibition of the induction of cyclin D/CDK6 kinase and the elimination of p27(Kip1) inhibitory activity.
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PMID:Effects of guanine nucleotide depletion on cell cycle progression in human T lymphocytes. 953

We have previously identified a cDNA clone from a murine teratocarcinoma PCC4 cDNA library, which we have termed MPK38 for murine protein kinase 38. MPK38 is a new member of the SNF1 serine/threonine kinase family. To understand the role of the MPK38 in thymocytes, we have investigated the level of MPK38 expression by Northern blot analysis. Interestingly, incubation of thymocytes at 37 degrees C resulted in the loss of the MPK38 transcript, however the transcript could be reinduced by treatment with Con A or PHA, but not with PMA and growth factors such as IL-2, IL-7, TGF-beta, TNF-alpha, and EGF. In addition, stimulation of mature T cells from the spleen with Con A failed to reinduce the MPK38 transcript, indicating a developmental regulation of MPK38 expression, whereas non-T cell populations significantly reinduced the transcript. These results suggest that MPK38 may play a functional role as one of the signal regulators in early T cell activation and, potentially, certain lineages of hematopoietic cell activation induced by Con A.
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PMID:MPK38 expression is upregulated in immature T cells activated by concanavalin A. 987 Jun 58

The release of histamine from mast cells and basophils during allergic reactions can regulate functions of T cells and may influence the nature of the immune response to a given antigen. The effects of histamine on T lymphocytes are associated with its binding to H2-receptors linked with adenylate cyclase, elevation of cAMP levels and activation of cAMP-dependent protein kinase (PKA). In this report we explore the role of PKA in histamine-mediated effects on IL-2 mRNA expression and IL-2 protein secretion. Fresh isolated mouse splenocytes (C57Bl/6) were pretreated with histamine (10(-4) M) for 1 h in the presence or absence of Rp-cAMPS (50 microM), an inhibitor of PKA regulatory subunit. The cells were then washed thoroughly and activated with plate-bound anti-CD3 (5 microg/ml), or PHA (1:100) or PMA + ionomycin (10 ng/ml, 1 microg/ml) for 6 h. Pretreatment with histamine inhibited IL-2 mRNA expression and secretion in cells activated with anti-CD3 or PMA, but not in cells activated with PMA + ionomycin. Rp-cAMPS prevented histamine-mediated suppression and did not itself affect IL-2 production. These results provide evidence that histamine affected IL-2 production when the cells were activated via the T cell receptor (TCR)/CD3 complex, but did not interfere with signal transduction pathways downstream of PKC leading to production of IL-2. These effects of histamine on IL-2 secretion and mRNA expression were mediated via PKA.
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PMID:Involvement of protein kinase A in histamine-mediated inhibition of IL-2 mRNA expression in mouse splenocytes. 1010 90

Human platelet and T cell activation antigen 1 (PTA1) is a 67kDa type I transmembrane glycoprotein mainly expressed on the surface of activated T cells and platelets, and is involved in the development of human cytotoxic T cell (CTL) as well as platelet activation and aggregation. We have cloned and sequenced gibbon PTA1 (gPTA1) and monkey PTA1 (mPTA1) cDNAs by RT-PCR from gibbon leukemic cell line MLA 144 and PHA-induced Rhesus monkey PBMC respectively. The mature proteins of gPTA1, mPTA1 and human PTA1 (hPTA1) share 93-95% amino acid similarity with the highest similarity in domain 1 of extracellular region. All the important features of PTA1 molecule are conserved among these Primates: (1) the ORF encoding 336 amino acid residues including signal sequence (18aa), extracellular region (232aa), transmembrane sequence (25aa) and cytoplasmic region (61aa); (2) two conserved pairs of Cys (Cys19 to Cys90 and Cys134 to Cys204) forming disulfide bonds stabilizing the two immunoglobulin superfamily V-like domains; (3) eight putative N-linked glycosylation sites (except gPTA1 with nine sites) and three O-linked glycosylation sites in extracellular region; and (4) predicated protein kinase C phosphorylation sites (Thr275 and Ser311), casein kinase II sites (Ser295 and The299) and the potential tyrosine phosphorylation site (Tyr304). These data indicate that PTA1 molecule is highly conserved among the Primates and may play important roles in immune response.
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PMID:Isolation of cDNAs encoding gibbon and monkey platelet and T cell activation antigen 1 (PTA1). 1064 17

Stimulation of lymphocytes through the Ag receptor can lead to cytokine responsiveness or unresponsiveness. We examined the importance of cyclin-dependent kinase (CDK)4 to establish and maintain IL-2 responsiveness in human T cells. Our results show that a herbimycin A- and staurosporine-sensitive phase of CDK4 expression and activity preceded the acquisition of IL-2-responsiveness in mitogen-stimulated peripheral blood T cells. Intriguingly, CDK4 expression and activity were demonstrable in purified unstimulated peripheral blood T cells from approximately 30% (5/16) of healthy individuals examined for this study. These T cells proliferated in response to IL-2 without additional mitogens, and both the expression and activity of CDK4 and the ability to respond to cytokines were resistant to herbimycin A and staurosporine. The pattern of CDK4 expression and response to IL-2 in this subset of individuals resembled that seen in the human IL-2-dependent Kit-225 T cell line. However, in contrast to normal T cells, Kit-225 cells were rendered unresponsive to IL-2 by stimulation through the Ag receptor. In these cells, PHA, anti-CD3, or PMA induced marked reductions of CDK4 expression and activity that paralleled IL-2 unresponsiveness, and these effects were not reversible by IL-2. Furthermore, IL-2-dependent proliferation could be similarly inhibited in Kit-225 cells by overexpression of the CDK inhibitors p16/Ink4-a or p21/Waf-1a or by overexpression of a kinase-inactive CDK4 mutant. The data indicate that CDK4 expression and activity are necessary to induce and maintain cytokine responsiveness in T cells, suggesting that CDK4 is important to link T cell signaling pathways to the machinery that controls cell cycle progression.
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PMID:CDK4 expression and activity are required for cytokine responsiveness in T cells. 1112 Jul 86


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