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Query: UNIPROT:P14784 (IL-2 receptor)
 3,849 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a previous study, we observed that a cell-free Salmonella typhimurium extract induced suppression of mitogen-induced T-cell proliferation and this suppression involved non-responsiveness of T-cells to interleukin-2 (IL-2). In this study, we found that a cell-free S. typhimurium extract modulated IL-2 receptor (IL-2R) expression on phytohemagglutinin (PHA)-stimulated murine spleen cells and this was a mechanism of T-cell non-responsiveness to IL-2, but did not affect IL-2 binding to IL-2R and the consequent responses. Western blotting using anti-phosphotyrosine antibodies showed that IL-2R-mediated tyrosine phosphorylation of protein substrates in PHA-activated murine splenic T-cells, which express a high-affinity IL-2R (alpha- and beta-chains), was not affected by treatment with the S. typhimurium cell-free extract. Furthermore, PHA-activated spleen T-cells responded to recombinant IL-2 and this was not inhibited by the extract. Surprisingly, IL-2R expression was augmented by treatment with the extract, although this was independent of IL-2 production. These results suggest that the suppression of T-cell proliferation induced by the Salmonella cell-free extract was associated with augmentation of IL-2R expression, rather than down-regulation of the IL-2 response. This may be a mechanism responsible for the Salmonella extract-evoked suppression of mitogen-induced T-cell proliferation.
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PMID:A cell-free Salmonella typhimurium extract modulates interleukin-2 (IL-2) receptor expression but not IL-2-stimulated responses of murine splenic lymphocytes. 780 63

The immunoregulatory action of saikosaponin-d (SSd), which was isolated from the root of Bupleurum falcatum L. and has a steroid-like structure, was examined on splenic T lymphocytes of C57BL/6 mice. SSd displayed a definite action in vitro to bidirectionally control the growth response of T lymphocytes stimulated by concanavalin A, anti-CD3 monoclonal antibody, and calcium ionophore A23187 plus phorbol 12-myristate 13-acetate. Low concentrations (1-3 micrograms/ml) of SSd upregulated the responses to suboptimum stimuli of agonists, particularly during the relatively late stage of the responses, whereas it downregulated the responses to supraoptimal stimuli. Under appropriate experimental conditions, SSd promoted interleukin-2 (IL-2) production and IL-2 receptor expression. It also accelerated c-fos gene transcription, but it did not modulate the level of tyrosine phosphorylation of cellular proteins. We concluded from these results that SSd uniquely modulates T lymphocyte function and that at least one target of the action of SSd is located at or before the step of c-fos gene transcription and after T-cell receptor/CD3-mediated protein tyrosine kinase activation.
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PMID:Characterization of the immunoregulatory action of saikosaponin-d. 795 39

Interleukin-2 (IL-2) signaling requires the dimerization of the IL-2 receptor beta.(IL-2R beta) and common gamma (gamma c) chains. Mutations of gamma c can result in X-linked severe combined immunodeficiency (XSCID). IL-2, IL-4, IL-7 (whose receptors are known to contain gamma c), and IL-9 (whose receptor is shown here to contain gamma c) induced the tyrosine phosphorylation and activation of the Janus family tyrosine kinases Jak1 and Jak3. Jak1 and Jak3 associated with IL-2R beta and gamma c, respectively; IL-2 induced Jak3-IL-2R beta and increased Jak3-gamma c associations. Truncations of gamma c, and a gamma c, point mutation causing moderate X-linked combined immunodeficiency (XCID), decreased gamma c-Jak3 association. Thus, gamma c mutations in at least some XSCID and XCID patients prevent normal Jak3 activation, suggesting that mutations of Jak3 may result in an XSCID-like phenotype.
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PMID:Interaction of IL-2R beta and gamma c chains with Jak1 and Jak3: implications for XSCID and XCID. 797 58

The intracellular portion of the IL-2 receptor (IL-2R) signal transducing beta-chain contains a distinct region, designated "serine-rich," which encompasses sequences required for IL-2-mediated cell growth. Although the receptor does not possess intrinsic protein-tyrosine kinase activity, IL-2 binding induces activation of intracellular protein-tyrosine kinases. Activation of many protein-tyrosine kinases leads to activation of phosphatidylinositol 3-kinase (PI 3-kinase). IL-2 binding also induces activation of PI 3-kinase. To study the interaction of PI 3-kinase with the IL-2 receptor beta-chain we analyzed PI 3-kinase activity in cells which express the wild type and mutant beta-chain. IL-2 mediated an increase in association with PI 3-kinase activity and protein in immunoprecipitates from cells expressing mitogenically competent receptors. PI 3-kinase products also increased in response to IL-2 in these cells. Deletion of the beta-chain serine-rich region abolished IL-2-mediated mitogenesis and cells expressing this mutant failed to activate PI 3-kinase. The interaction of the IL-2 receptor with an intracellular tyrosine kinase, lck, has been mapped to the acidic-rich region of the beta-chain. Cells which express the beta-chain lacking the acidic-rich region grow in the presence of IL-2 and had IL-2-dependent activation of PI 3-kinase. Activation of PI 3-kinase in response to IL-2 was not abolished by treatment of cells with rapamicin and occurred only in cells which express mitogenically competent receptors. The results presented in this study suggest that IL-2-mediated PI 3-kinase activation occurs by a mechanism distinct from interaction with the lck protein-tyrosine kinase.
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PMID:Serine-rich region of the IL-2 receptor beta-chain is required for activation of phosphatidylinositol 3-kinase. 802 55

Pervanadate has been shown to rapidly increase the level of tyrosine phosphorylation in intact cells. Because one of the most rapidly detectable events following treatment of human T cells with interleukin-2 (IL-2) is tyrosine kinase activation, we were interested to determine whether pervanadate could act to induce IL-2-associated events. We show here that pervanadate does act to induce IL-2 signal transduction pathways as determined by induction of mitogenesis and interferon gamma production in normal human T cells and the factor independent T cell line YT. Analysis of signal transduction events shows that pervanadate induces the activity of the src family of tyrosine kinases lck and fyn and the tyrosine phosphorylation of a major IL-2 responsive protein of 97 kDa. Pervanadate does not, however, induce the activity of tyrosine kinases associated with the IL-2 receptor or the phosphorylation of a major IL-2 responsive protein of 116 kDa (Jak-3). Together these data suggest that src family kinase activation is a down stream event following IL-2 stimulation and is not directly associated with the activation of the IL-2 receptor-associated tyrosine kinase. The data also imply that tyrosine phosphorylation of p116/Jak-3 is strictly associated with activation of tyrosine kinases associated with the IL-2 receptor. With the use of pervanadate as a tool, we have established a dissociation of src family kinases with IL-2 receptor activation and imply the involvement of two distinct tyrosine kinase pathways, a receptor-associated pathway closely coupled with Jak-3 phosphorylation and a downstream pathway involving src family kinase activation.
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PMID:Pervanadate simulates the effects of interleukin-2 (IL-2) in human T cells and provides evidence for the activation of two distinct tyrosine kinase pathways by IL-2. 808 4

The present study investigates the effect of transforming growth factor (TGF)-beta on the production of IL-4 and IFN-gamma by the leukemia Th0 type cell line HUT78, by freshly isolated human T cells, and by antigen specific human T cell clones. We found that IL-4 and IFN-gamma, but not IL-2, production by stimulated HUT78 cells was inhibited by TGF-beta 1. TGF-beta 1 also reduced the accumulation of IL-4 and IFN-gamma specific mRNA in stimulated HUT78 cells. However, IL-2 and IL-7 co-stimulated IL-4 and IFN-gamma production, whereas IL-1, IL-3, IL-5, IL-6, IL-8, tumor necrosis factor-alpha or granulocyte macrophage colony stimulating factor had no effect. Because IL-2 is an important helper cytokine for the production of IL-4 and IFN-gamma, we investigated whether signal transduction through the IL-2 receptor is impaired by TGF-beta 1. We found that tyrosine phosphorylation in response to IL-2 in HUT78 cells was strongly inhibited by a short preincubation with TGF-beta 1. Evidence for an antagonistic role for TGF-beta 1 and IL-2 comes from the finding that high doses of IL-2 could partially overcome TGF-beta 1 mediated inhibition of IL-4 and IFN-gamma production. Similar to its effect on HUT78 cells, TGF-beta 1 also inhibited IL-4 and IFN-gamma production by freshly isolated T cells as well as by human T cell clones. Taken together, our experiments show that the IL-2 dependent cytokines IL-4 and IFN-gamma are both negatively controlled by TGF-beta under conditions where IL-2 production is unaffected by a mechanism which partially involves an inhibition of IL-2/IL-2R signal transduction. These data identify TGF-beta and IL-2 as mutual antagonists in the regulation of IL-4 and IFN-gamma production.
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PMID:Transforming growth factor-beta inhibits IL-4 and IFN-gamma production by stimulated human T cells. 818 98

Protooncogenes are the normal forms of cellular genes that when altered in their expression or coding sequences can contribute to neoplastic transformation. As these genes often are important for normal cellular growth control, we explored the possibility that protein kinases encoded by particular protooncogenes could participate in signal transduction pathways regulated by the T cell growth factor, interleukin-2 (IL-2). In this review we summarize our findings to date regarding Raf-1, a serine/threonine-specific kinase that becomes phosphorylated on tyrosine residues and enzymatically activated in response to IL-2 stimulation. In addition, we describe our investigations of Lck and Lyn, two closely related protein tyrosine kinases of the src gene family that physically associate with the IL-2 receptor complex and whose activities are regulated by IL-2 in at least some T cells and B cells, respectively.
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PMID:Protooncogene-encoded protein kinases in interleukin-2 signal transduction. 826 Jun 49

Binding of interleukin-2 (IL-2) to the IL-2 receptor (IL-2R) stimulates Src family kinases, tyrosine phosphorylation of several proteins, conversion of Ras to its active GTP-bound form, and eventually c-fos, c-jun, and c-myc induction. The IL-2R beta chain plays a crucial role in IL-2R signaling. Within the cytoplasmic domain of the beta chain, a region essential for mitogenesis and another involved in binding the Src family kinase Lck have been defined. The beta chain itself is tyrosine-phosphorylated upon IL-2 stimulation. Since the adapter protein Shc acts upstream of Ras and is involved in T cell receptor-mediated Ras activation, we examined the role of Shc in IL-2 signaling. Shc was found to be tyrosine-phosphorylated upon IL-2 stimulation in CTLL-20 cells. After its phosphorylation, Shc interacted with another adapter protein, Grb2, and, via Grb2, with the Ras GTP/GDP exchange factor mSOS. After IL-2 stimulation, Shc also associated with the IL-2R beta chain. Thus, during IL-2 signaling, the interaction of Shc with the IL-2R beta chain and its simultaneous association with Grb2 and mSOS may couple IL-2R stimulation to Ras signaling.
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PMID:The adapter protein Shc interacts with the interleukin-2 (IL-2) receptor upon IL-2 stimulation. 829 3

The genes encoding the alpha- and beta-chains of the human interleukin-2 receptor were expressed in lepidopteran insect cells using the baculovirus expression vector system. The corresponding genes were inserted under the polyhedrin promoter of the Autographa california nuclear polyhedrosis virus and expressed in the Spodoptera frugiperda insect cell line during viral infection. The recombinant receptor proteins were identified in the insect cell lysates by using protein dot blot and ELISA techniques. At 36 h post infection the corresponding proteins were clearly detected using anti-IL-2 alpha- and beta-receptor-specific antibodies. A large amount of the alpha-chain was also found in the supernatant culture media at 72 h post infection and metabolic labelling with [35S]-methionine indicated that it was proteolytically cleaved into a 32 kDa soluble form. A similar soluble or secreted form of the beta-chain was, however, not observed. Both receptor proteins were expressed on the surface of the insect cells as determined by flow cytometry analysis. Studies performed with the different IL-2 receptor forms (alpha- and beta-chains alone or in combination) in the presence or absence of rIL-2 suggest that the receptor proteins when expressed in infected insect cells are non-functional with respect to tyrosine phosphorylation.
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PMID:Expression of human IL-2 receptor alpha- and beta-chains using the baculovirus expression system. 835 2

We investigated activation of mitogen-activated protein (MAP) kinase, also known as microtubule associated protein-2 kinase (MAP-2K), by recombinant interleukin-2 (rIL-2) in phytohaemagglutinin (PHA)-induced peripheral blood lymphoblasts (PBL). MAP-kinase activation has been implicated in growth of lymphocytes and other cell types. Enzyme activity was purified from cell lysates by ion-exchange chromatography and activity measured by the ability to phosphorylate the substrates MAP-2 and myelin basic protein peptide (APRTPGGRR) in vitro. Recombinant IL-2 stimulated a variable (two-to 10-fold) and evanescent MAP-2K response which was dose dependent over the range 0-50 U/ml. In contrast to MAP-kinase activation by the CD3 receptor, activation by the IL-2 receptor (IL-2R) proceeded independently from protein kinase C (PKC) and extracellular-free Ca2+. MAP-kinase activation by CD3 involves an activation cascade which depends on Ca2+ influx and PKC activation. These events culminate in tyrosine phosphorylation and activation of MAP kinase. Recombinant IL-2 induced tyrosine phosphorylation of several intracellular proteins, including a 40,000 MW substrate which co-electrophoresed with ERK-2 on SDS-PAGE. The ERK-2 gene encodes a 41,000 MW MAP-2K and is subject to regulation by a variety of mitogens and growth factors in lymphocytes and non-lymphoid cells. MAP-kinase activation by rIL-2 was abrogated when PHA blasts were pretreated with the tyrosine protein kinase (TPK) inhibitor, methyl-2,5-dihydroxy-cinnamate. Although the TPK, p56lck, has been implicated in the activation of MAP kinase and the function of IL-2R, we found no mobility shift from a 56,000 to a 60,000 MW position as seen during PKC activation. Together these data suggest that tyrosine phosphorylation is critical to IL-2-mediated signal transduction and that MAP kinase is one of the cellular intermediates involved in this pathway.
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PMID:Activation of mitogen-activated protein kinase/ERK-2 in phytohaemagglutin in blasts by recombinant interleukin-2: contrasting features with CD3 activation. 838 29


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