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

Interleukin 2 (IL-2) is a lymphokine, produced by T cells upon antigenic or mitogenic stimulation, that is a critical regulator of T-cell proliferation. Although the binding of IL-2 to its receptor has been well characterized, the molecular mechanisms by which IL-2 transmits its signal from the membrane to the interior of the cell are poorly understood. Like most other growth factors, IL-2 causes rapid phosphorylation of proteins within its target cells. Unlike many other growth factors, however, the known subunits of the IL-2 receptor lack tyrosine-specific kinase activity, and little is known about the kinases whose activities are regulated by IL-2. Here we show that IL-2 (but not IL-4) induces rapid phosphorylation of the p72-74 serine/threonine-specific kinase encoded by the c-Raf-1 protooncogene in an IL-2-dependent murine T-cell line, CTLL-2, and that this phosphorylation is associated with increased kinase activity in p72-74 Raf-1-containing immune complexes. The concentration dependence of IL-2-mediated elevations in Raf-1 kinase activity correlated well with IL-2-stimulated proliferation of CTLL-2 cells. Furthermore, much of the IL-2-stimulated phosphorylation of p72-74 Raf-1 occurred on tyrosines. To our knowledge, the Raf-1 kinase represents the first endogenous substrate of an IL-2-regulated tyrosine kinase to be identified.
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PMID:Interleukin 2 induces tyrosine phosphorylation and activation of p72-74 Raf-1 kinase in a T-cell line. 199 24

Interleukin-2 (IL-2) stimulates the rapid phosphorylation on tyrosine of several specific cellular proteins. However, the high-affinity human IL-2 receptor, composed of an alpha (p55) and beta (p70/75) subunit, does not contain a cytoplasmic tyrosine kinase domain. In this study, we investigated the identities of the proteins phosphorylated on tyrosine in response to IL-2 stimulation to examine possible pathways of signal transduction. By the use of immunoblotting with anti-phosphotyrosine antibodies, we demonstrate that IL-2 augments tyrosine phosphorylation of the IL-2 receptor beta chain in human cell lines expressing either high-affinity (alpha/beta) receptors or only the beta chain. In IL-2-dependent mouse T cell lines, a 100,000-Da protein was phosphorylated on tyrosine in response to IL-2 and is proposed to be the mouse IL-2 receptor beta chain. Two other cellular proteins, pp55 and pp105 in human or pp55 and pp115 in mouse cell lines, were phosphorylated on tyrosine in response to IL-2 and coimmunoprecipitated with the high-affinity IL-2 receptor after chemical crosslinking of IL-2-stimulated cells. Thus, the IL-2 receptor may associate with additional subunits or with cellular proteins involved in signal transduction.
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PMID:Ligand-stimulated tyrosine phosphorylation of the IL-2 receptor beta chain and receptor-associated proteins. 200 86

In the interleukin-2 (IL-2) system, intracellular signal transduction is triggered by the beta chain of the IL-2 receptor (IL-2R beta); however, the responsible signaling mechanism remains unidentified. Evidence for the formation of a stable complex of IL-2R beta and the lymphocyte-specific protein tyrosine kinase p56lck is presented. Specific association sites were identified in the tyrosine kinase catalytic domain of p56lck and in the cytoplasmic domain of IL-2R beta. As a result of interaction, IL-2R beta became phosphorylated in vitro by p56lck. Treatment of T lymphocytes with IL-2 promotes p56lck kinase activity. These data suggest the participation of p56lck as a critical signaling molecule downstream of IL-2R via a novel interaction.
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PMID:Interaction of the IL-2 receptor with the src-family kinase p56lck: identification of novel intermolecular association. 204 59

We previously established a monoclonal antibody, TU11 mAb, which is specific for human IL-2 receptor (IL-2R) beta chain (p75) and does not inhibit IL-2-binding to IL-2R beta. Using TU11 mAb, we first demonstrated the existence of a third component, p64, of IL-2R, tentatively named the gamma chain of IL-2R. TU11 mAb precipitated not only the beta chain but also the alpha and gamma chains in the lysates of cells bearing the high-affinity IL-2R in the presence of IL-2 without any chemical crosslinker. The gamma chain was also detected in lymphoid MOLT alpha beta and MOLT beta cells, which were stably transfected with both alpha and beta cDNA, and with beta cDNA alone, respectively, but not in fibroblastoid COS alpha beta and COS beta cells, which were stably transfected with both alpha and beta cDNA, and with beta cDNA alone, respectively. Furthermore, IL-2-mediated growth signals were transduced in the lymphoid transfectant cells but not in the fibroblastoid transfectant cells, suggesting the possibility that the gamma chain along with the beta chain has an essential role in the transduction of IL-2-mediated growth signals. Using TU11 mAb, we secondly demonstrated that IL-2 rapidly induces tyrosine phosphorylation of both the beta and gamma chains in an IL-2-dose-dependent manner. The tyrosine phosphorylation of beta and gamma chains were also detected in the lymphoid transfectant cells but not in the fibroblastoid transfectant cells, indicating the correlation between tyrosine kinase activation and IL-2-mediated growth signaling. The beta chain was phosphorylated in in vitro on serine, threonine and tyrosine residues, but the gamma chain was phosphorylated in in vitro predominantly on tyrosine residues, suggesting the possibility that the gamma chain itself is a tyrosine kinase molecule.
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PMID:IL-2-induced signal transduction: involvement of tyrosine kinase and IL-2 receptor gamma chain. 209 Aug 80

We have recently established a mAb named TU11 mAb specific for the p75 subunit of human IL-2 receptor (IL-2R). The present study using TU11 mAb demonstrates the IL-2-induced phosphorylation of IL-2Rp75 on tyrosine residues in IL-2-dependent T cells. The tyrosine phosphorylation is mediated by the high affinity IL-2R, correlates with the IL-2-induced cell growth, and rapidly increases during the first 5 min of IL-2 stimulation. Phosphorylation of serine and threonine residues of IL-2Rp75 is also detected, but its IL-2 dependency is not significant during at least the first 5 min. These results suggest some roles of a tyrosine kinase associated with IL-2Rp75 in the IL-2-induced signal-transducing pathway.
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PMID:Interleukin 2 (IL-2)-induced tyrosine phosphorylation of IL-2 receptor p75. 210 66

The T-cell antigen receptor (TCR) regulates two signal transduction pathways: the phosphatidylinositol (PtdIns) and tyrosine kinase pathways. Stimulation of T cells with antigen or anti-TCR monoclonal antibodies induces an increase in inositol phosphates and diacylglycerol, the second messengers responsible for the mobilization of cytoplasmic free calcium and activation of protein kinase C-4. The TCR also activates a tyrosine kinase that is not intrinsic to the TCR. The relationship between these two signal transduction pathways and their contribution to later T-cell responses is unclear. Studies using variants of a murine hybridoma suggested that the PtdIns pathway might not be necessary for or be involved in regulating interleukin-2 (IL-2) production. To address the relationship between later T-cell responses and the early biochemical signals, we investigated the ability of a heterologous receptor with defined signal transduction function to induce T-cell activation. The human muscarinic subtype-1 receptor (HM1), which elicits PtdIns metabolism in neuronal cells through a G protein-coupled mechanism, also functionally activates this pathway when expressed in the T-cell line Jurkat-derived host, J-HM1-2.2 (ref.8). We show here that stimulation of HM1 alone induced IL-2 production and IL-2 receptor alpha chain expression. HM1 does not induce the tyrosine kinase pathway, suggesting that this pathway does not directly influence later T cell-activation responses. Instead, our studies indicate that activation of the PtdIns pathway is probably sufficient to induce later T-cell responses.
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PMID:Stimulation of the phosphatidylinositol pathway can induce T-cell activation. 223 59

Interleukin-2 (IL-2) is a requisite factor for growth and proliferation of IL-2-dependent T cells. At present, the mechanism by which the high-affinity IL-2-IL-2 receptor interaction transmits a mitogenic signal to the cellular interior remains unclear. In this report we have used three murine T cell clones to demonstrate that IL-2 stimulates rapid tyrosine phosphorylation of several proteins. Two of these clones, CTLL-2 and CT6, exhibit a cytotoxic T cell phenotype, while the third, HT-2, was derived from a helper T cell line. All three T cell clones proliferated in response to IL-2 stimulation, but HT-2 cells also proliferated in response to interleukin-4 (IL-4). We comparatively examined the effects of IL-2 and IL-4 on protein tyrosine phosphorylation in these cells by immunoaffinity purification of phosphotyrosyl substrates with an anti-phosphotyrosine monoclonal antibody. Stimulation with concentrations of IL-2 resulting in maximal (10-30 U/ml) or sub-maximal (1-5 U/ml) proliferation caused the rapid tyrosine phosphorylation of 97 and 57 kDa proteins in all three cell lines. The 97 kDa protein was localized in the cytosol, while the 57 kDa protein was detected in both cytosolic and crude membrane fractions. IL-2-dependent tyrosine phosphorylation of an 86 kDa cytosolic protein was observed only in CT6 cells. Tyrosine phosphorylation of 22, 23 and 200 kDa proteins was also observed, but only in the cytotoxic T cell clones. Phosphoamino acid analyses revealed that the 97, 86 and 57 kDa proteins contained phosphotyrosine and phosphoserine residues. Concentrations of IL-2 below the threshold concentration for induction of a proliferative response correspondingly failed to stimulate protein tyrosine phosphorylation. In contrast, growth stimulation of HT-2 cells by IL-4 was not preceded by early changes in protein tyrosine phosphorylation, suggesting that protein tyrosine phosphorylation may not be essential for the induction of IL-4-dependent cell-cycle progression. These results demonstrate that high-affinity IL-2 receptors are coupled to tyrosine kinase activity(s) in T cells. However, the failure of IL-4 to stimulate protein tyrosine phosphorylation in the same cells indicates that enhanced protein tyrosine phosphorylation may not be requisite for growth factor-dependent T cell proliferation.
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PMID:Differential effects of interleukin-2 and interleukin-4 on protein tyrosine phosphorylation in factor-dependent murine T cells. 233 39

Interleukin-3 (IL-3) binds to its receptor with high and low affinities, induces tyrosine phosphorylation, and promotes the proliferation and differentiation of hematopoietic cells. A binding component of the IL-3 receptor was cloned. Fibroblasts transfected with the complementary DNA bound IL-3 with a low affinity [dissociation constant (Kd) of 17.9 +/- 3.6 nM]. No consensus sequence for a tyrosine kinase was present in the cytoplasmic domain. Thus, additional components are required for a functional high affinity IL-3 receptor. A sequence comparison of the IL-3 receptor with other cytokine receptors (erythropoietin, IL-4, IL-6, and the beta chain IL-2 receptor) revealed a common motif of a distinct receptor gene family.
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PMID:Cloning of an interleukin-3 receptor gene: a member of a distinct receptor gene family. 240 37

Both interleukin 2 (IL-2) and epidermal growth factor (EGF) receptors exist in two forms that differ with respect to affinity for their ligand. Only the high-affinity receptors appear to be responsible for the proliferation signal delivered upon binding of the growth factor. Fibroblasts transfected with IL-2 receptor cDNA generate only low-affinity receptors for IL-2, but fusion of membranes from these fibroblasts with T-cell membranes converts some receptors to high affinity, indicating the involvement of a T cell-specific factor in the generation of high-affinity receptors. We have constructed a chimeric cDNA molecule containing the extracellular IL-2-binding domain of the IL-2 receptor cDNA and the transmembrane and intracellular tyrosine kinase domains of the EGF receptor cDNA. When transfected into fibroblasts, this IL-2-EGF receptor cDNA generated high-affinity receptors for IL-2. Moreover, fibroblasts transfected with the chimeric molecule were morphologically transformed and produced rapidly growing tumors in nude mice.
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PMID:High-affinity interleukin 2 binding by an oncogenic hybrid interleukin 2-epidermal growth factor receptor molecule. 310 9

In this study both a ligand-dependent treatment [concanavalin A (Con A)] and a ligand-independent treatment [high-voltage pulsed galvanic stimulation (HVPGS)] have been used to initiate lymphocyte activation via a transmembrane signaling process. Our results show that both treatments cause the exposure of two different hormone [insulin and interleukin-2 (IL-2)] receptors within the first 5 min of stimulation. When either insulin or IL-2 is present in the culture medium, the stimulated lymphocytes undergo the following responses: (1) increased free intracellular Ca2+ activity; (2) aggregation of insulin or IL-2 receptors into patch/cap structures; (3) tyrosine-kinase-specific phosphorylation of a 32-kd membrane protein; and finally (4) induction of DNA synthesis. Further analysis indicates that hormone receptor capping is inhibited by (1) cytochalasin D, suggesting the involvement of microfilaments; (2) sodium azide, indicating a requirement for ATP production; and (3) W-5, W-7, and W-12 drugs, implying a need for Ca2+/calmodulin activity. Treatment with these metabolic or cytoskeletal inhibitors also prevents both the tyrosine-kinase-specific protein phosphorylation and DNA synthesis which normally follow hormone receptor capping. Double immunofluorescence staining shows that actomyosin, Ca2+/calmodulin, and myosin light-chain kinase are all closely associated with the insulin and IL-2 receptor cap structures. These findings strongly suggest that an actomyosin-mediated contractile system (regulated by Ca2+, calmodulin, and myosin light-chain kinase in an energy-dependent manner) is required not only for the collection of insulin and IL-2 receptors into patch and cap structures but also for the subsequent activation of tyrosine kinase and the initiation of DNA synthesis. We, therefore, propose that the exposure and subsequent patching/capping of at least one hormone receptor are required for the activation of mouse splenic T-lymphocytes.
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PMID:Lymphocyte activation and capping of hormone receptors. 313 94


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