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

The growth, differentiation, and functional activities of antigen-stimulated T lymphocytes are regulated by the interaction of the T-cell-derived cytokine, interleukin-2 (IL-2), with the high-affinity IL-2 receptor (IL-2R). IL-2R occupancy initiates a rapid increase in intracellular protein tyrosine phosphorylation, suggesting that a receptor-coupled protein tyrosine kinase (PTK) serves as a proximal signaling element for the IL-2R. Previous studies implicated the src-family kinase, p56lck, as a potential IL-2R-linked signal transducer. In this study, we have characterized a spontaneous variant of the IL-2-dependent cytotoxic T-cell line, CTLL-2, which contains no detectable lck-derived mRNA transcripts, protein, or PTK activity. The p56lck-deficient CTLL-2 cells retained strict dependence on IL-2 for both viability and growth, indicating that p56lck activity was not required for the transduction of IL-2-mediated mitogenic signals. However, the p56lck-deficient cells exhibited a moderate decrease in their rate of IL-2-dependent proliferation. In contrast to this relatively modest proliferative defect, the p56lck-deficient cell line displayed a profound reduction in T-cell antigen receptor-dependent cytolytic effector functions. Both the proliferative and the cytolytic defects observed in the p56lck-deficient cells were completely reversed by transfection of these cells with a wild-type lck expression vector. These results indicate that p56lck expression is not obligatory for IL-2-mediated T-cell growth stimulation; however, this PTK plays a central role in the generation T-cell-mediated cytotoxic responses.
Mol Cell Biol 1992 Oct
PMID:Effects of p56lck deficiency on the growth and cytolytic effector function of an interleukin-2-dependent cytotoxic T-cell line. 140 41

The calcium ionophore, A23187, when used alone was found to induce proliferation of murine T cells, at concentrations of 0.5-1 mM. This response required the presence of syngeneic splenic adherant cells (SAC) as a source of accessory cells. Interestingly, only CD4+ T cells but not CD8+ T cells or B cells responded to the calcium ionophore by proliferation. The inability of CD8+ T cells or B cells to respond was not related to decreased elevation in the intracellular ionized calcium [Ca2+]i concentration induced by the ionophore, because activated CD4+ T, CD8+ T and B cells all exhibited similar elevation in [Ca2+]i. The inability of CD8+ T cells to respond to calcium ionophore was probably due to insufficient production of autocrine growth factors, such as IL-2, inasmuch as the addition of exogenous IL-2 could completely restore the CD8+ T cell responsiveness. Also, exogenous rIL-1 could partially restore purified T cell response to calcium ionophore, whereas, rIL-6 failed to do so. IL-2, but not IL-4, acted as an autocrine growth factor for T cells responding to the calcium ionophore in the presence of SAC, since, antibodies against IL-2 or IL-2 receptor (IL-2R) but not against IL-4, could inhibit the T cell proliferation. Furthermore, exogenous rIL-2 but not rIL-4 supported the proliferation of T cells to calcium ionophore in the absence of accessory cells. Our results suggest that murine lymphocytes exhibit heterogeneity in their proliferative responsiveness to calcium ionophore and that this may not depend on the early activation signal such as the elevation in [Ca2+]i) induced by the ionophore but may depend on subsequent signals which regulate endogenous growth factor production.
Cell Mol Biol (Noisy-le-grand)
PMID:Murine lymphocytes exhibit heterogeneity in their proliferative responsiveness to calcium ionophore. 148 6

Stimulation of activated T lymphocytes with interleukin 2 (IL-2) results in rapid increases in intracellular protein tyrosine phosphorylation. Both the identity of the protein tyrosine kinase (PTK) activated by IL-2 receptor ligation and the identities of the critical target proteins for this PTK remain largely undefined. In this article, we demonstrate that stimulation of activated murine or human T cells with IL-2 for 10 to 30 min induces two- to threefold increases in the level of phosphatidylinositol (PtdIns) 3-kinase activity present in antiphosphotyrosine (p-Tyr) antibody immunoprecipitates from these cells. Furthermore, substantial levels of PtdIns 3-kinase activity were coprecipitated from IL-2-deprived T cells by antibodies to the src-related PTK p59fyn. Cellular stimulation with IL-2 induced a two- to threefold increase in the level of p59fyn-associated PtdIns 3-kinase activity. To examine the effect of a constitutive increase in PtdIns 3-kinase activity on the growth factor responsiveness of activated T cells, murine CTLL-2 cells were transfected with a polyomavirus middle T antigen (MTAg) expression vector. Anti-p-Tyr and anti-p59fyn immunoprecipitates from MTAg-transfected CTLL-2 cells contained three- to sixfold higher levels of PtdIns 3-kinase activity than wild-type cells. Immune complex kinase assays revealed that MTAg expression concomitantly induced a constitutive threefold increase in the PTK activity of p59fyn in these cells. However, stable MTAg expression did not abrogate the dependence of CTLL-2 cells on exogenous IL-2 for continued growth and proliferation.
Mol Cell Biol 1991 Sep
PMID:Interleukin 2- and polyomavirus middle T antigen-induced modification of phosphatidylinositol 3-kinase activity in activated T lymphocytes. 165 56

Human cytomegalovirus (HCMV) immediate early (IE) genes act as trans-acting factors to upregulate various viral promoters. We used various IE plasmid constructs in transient transfection assays and demonstrated that the HCMV IE2 gene product upregulated expression from the interleukin (IL)-2 and IL-2 receptor (IL-2R) promoters and increased amounts of endogenous, steady-state IL-2 and IL-2R RNA. In marked contrast, the IE1 gene product, which can upregulate the major IE promoter and the IL-1 beta promoter, had no effect on the IL-2 and IL-2R promoters. These studies suggest a role for the HCMV IE2 gene product as a modulator of the inflammatory response associated with HCMV infection.
Am J Respir Cell Mol Biol 1991 Sep
PMID:The immediate early genes of human cytomegalovirus upregulate expression of the interleukin-2 and interleukin-2 receptor genes. 165 52

A role for tyrosine phosphorylation in the signal-transducing mechanisms of several hematopoietic growth factors has been hypothesized. To extend these observations, we have examined the effects of erythropoietin (Epo) on tyrosine phosphorylation in an Epo-responsive cell that was obtained by transfecting the murine erythropoietin receptor (EpoR) into an interleukin-3 (IL-3)-dependent cell line. By two-dimensional analysis of phosphotyrosine-containing proteins isolated with a monoclonal antibody (1G2) against phosphotyrosine, Epo and IL-3 were found to rapidly induce tyrosine phosphorylation of comparable substrates of 92, 70, and 56 kDa. In addition, Epo uniquely induced phosphorylation of a 72-kDa substrate while IL-3 uniquely induced phosphorylation of a 140-kDa substrate. Immunoprecipitation and mixing experiments indicated that the 72-kDa substrate may represent a small fraction of the EpoR. To explore the significance of tyrosine phosphorylation, we generated two mutants of the EpoR that lacked 108 or 146 amino acids at their carboxyl termini. In addition we constructed an internally deleted mutant that lacked 20 amino acids in a region of sequence homology with the IL-2 receptor beta chain. Although all mutants were expressed at comparable levels and had comparable binding affinities for Epo, only the mutant lacking 108 amino acids at the carboxyl terminus retained significant mitogenic activity or the ability to induce tyrosine phosphorylation.
Mol Cell Biol 1991 Oct
PMID:Induction of tyrosine phosphorylation by the erythropoietin receptor correlates with mitogenesis. 165 16

The macrolide FK-506, like the cyclic undecapeptide cyclosporin A (CsA), is a potent immunosuppressant that interferes with the transcriptional activation of several early-phase genes in T lymphocytes, including that for interleukin-2 (IL-2). We compared the effects of FK-506 and CsA on transcription from the 5' upstream activating sequences (UAS) of the human IL-2 gene and several cellular and viral UAS to define cis-acting sites which may be responsive to FK-506. The UAS surveyed included the human IL-2 receptor alpha-chain, human metallothionein II, simian virus 40 early, human cytomegalovirus immediate-early, adenovirus major late, and Rous sarcoma virus long terminal repeat UAS. In addition, we studied multimers of several defined promoter elements (NFIL-2A, NF-kappa B, or NF-AT1) which are found in the UAS of the human IL-2 gene and which have been reported to be responsive to CsA when linked to a minimal promoter element (TATA box and transcription start site). Each promoter-regulatory region was fused to the bacterial chloramphenicol acetyltransferase gene and used to transiently transfect Jurkat cells. Quantitative chloramphenicol acetyltransferase assay determinations indicated that the transcriptional activity of each UAS induced upon T-cell activation was (i) completely sensitive, (ii) partially sensitive, or (iii) resistant to inhibition by CsA and FK-506. The induced transcription driven by the IL-2 promoter elements NF-AT1 and NFIL-2A could be blocked completely by FK-506 or CsA. Gel mobility shift assays indicated that the binding activities of the factors specifically interacting with these sequences were detected in activated cells regardless of whether the cells were treated with FK-506 or CsA. The results suggest that FK-506 or CsA inhibits a transacting mechanism(s) without disrupting the binding activities of these transcription factors. The degree to which each UAS was resistant to FK-506 was consistent with the level of transcription induced by phorbol myristate acetate, while UAS which were sensitive to inhibition by FK-506 were dependent on the presence of both phorbol myristate acetate and ionomycin.
Mol Cell Biol 1991 Aug
PMID:The immunosuppressant FK-506 specifically inhibits mitogen-induced activation of the interleukin-2 promoter and the isolated enhancer elements NFIL-2A and NF-AT1. 171 1

In a phase I/II dose escalation study performed at our institution, a total of 14 advanced metastatic cancer patients received between 4 and 16 weeks of subcutaneous recombinant interleukin-2. Doses were escalated at weekly intervals, starting at 1.8 million IU/m2/day up to a maximum dose of 14.4 million U/m2 daily. When comparing patients with (n = 4) and without (n = 7) prior chemotherapy on day 0 (i.e., before rIL-2), both patient groups exhibited Tac IL-2 receptor (CD25) positive peripheral blood lymphocytes at equal levels of positivity (8%). In contrast, 4-week systemic treatment with subcutaneous rIL-2 at escalating dose levels revealed a significant difference in the up-regulation by interleukin-2 of CD25 cell surface receptor. Thus, after 4 consecutive weeks of treatment, patients without previous chemotherapy showed a mean CD25 positivity of peripheral blood lymphocytes at 38%, as compared with 22% in patients who did receive prior chemotherapy (p less than 0.05). These data suggest that chemotherapy pretreatment may have a significant effect on biological response to rIL-2 in vivo.
Mol Biother 1991 Jun
PMID:Diminished expression of interleukin-2 receptors in vivo after prior chemotherapy in advanced cancer patients receiving recombinant interleukin-2. 191 Jun 21

Two murine T cell lines (C30.1 and Line 1) were used to study the expression of the p55 interleukin-2 receptor gene. C30.1 is an IL-2-dependent T cell line that can be stimulated for a short period of time by IL-4. Line 1 cells are propagated in IL-4 but they also proliferate in response to IL-2. In both cell lines stimulation by IL-2 leads to a strong induction of p55 IL-2 receptor mRNA while stimulation by IL-4 leads only to a very moderate increase in expression of this mRNA. The induction of p55 IL-2 receptor mRNA by IL-4 is comparable to that of beta-actin mRNA. These data confirm that IL-2 upregulates p55 IL-2 receptor gene expression while IL-4, which also activates T cells, does not lead to specific induction of this gene. We have also determined the transcription initiation sites utilized by the p55 IL-2 receptor gene in C30.1 and Line 1 cells. Seven sites were identified, one of which predominates. Resting cells, or cells stimulated with IL-2 or IL-4, display the same pattern of transcription site utilization.
Mol Immunol
PMID:Induction of mouse p55 interleukin-2 receptor gene expression by IL-2 and IL-4 and characterization of its transcription initiation sites. 201 Nov 31

Murine T and B lymphocytes can be induced to release soluble interleukin 2 receptors (sIL2R). This receptor is believed to be a truncated form of the p55 chain of the cell membrane-associated receptor. It has been speculated that this receptor may play an immunoregulatory role via competition for IL-2 with the high-affinity (p55/75 heterodimer) IL-2 receptor. Of crucial importance to this hypothesis are both the concentration of the receptor and its affinity of binding for interleukin 2. We report the measurement of the affinity of sIL2R derived from stimulated normal murine splenocytes for IL-2. We also report the quantification of an enzyme linked immunosorbent assay (ELISA) for sIL2R via measurement of the sIL2R concentration in normal murine splenocyte conditioned medium using a radioimmunometric assay and Scatchard analysis. This method of sIL2R quantification is preferable to sIL2R purification and subsequent concentration estimation as used by previous investigators as any purification process risks destruction of some epitopes. Using the above conditioned medium as a standard we have tested supernatants from several cell lines and sera from several different mouse strains for sIL2R. As would be expected this method of quantification yielded a markedly different value for serum sIL2R levels in normal mice than that obtained by previous investigators. Our results indicate that it is very unlikely that sIL2R competes with the high-affinity form of the IL-2 receptor for IL-2. However, it is possible that it competes for IL-2 with the medium-affinity p75 form of the IL-2 receptor and as such is important in restricting unwanted non-specific (bystander) activation of p75 expressing cells. Evidence from both our previous work as well as from the literature is presented to support this hypothesis.
J Mol Cell Immunol 1990
PMID:A regulatory role for the soluble IL-2 receptor via competition with the p75 cell-surface form of the receptor for IL-2. 208 Sep 85

The human immunodeficiency virus type I (HIV-1) possesses powerful regulatory elements that control the rate of replication of HIV-1 and subsequent processing of HIV-1 genes. We have used this regulatory mechanism to drive expression of foreign genes inserted in retrovirus vectors. This approach was used to express the human IL-2 gene in IL-2-dependent mouse CTLL-2 cells to determine the role of autonomous growth in maintaining proliferation of virus-infected T lymphocytes during HTLV-1-induced adult T-cell leukemia (ATL). Expression of IL-2 sequences in IL-2-dependent mouse CTLL-2 cells resulted in autonomous growth of IL-2-independent CTLL-2 clones. Endogenous expression of IL-2 appeared to interrupt normal constraints of growth in that these IL-2-independent clones showed reduced cell-density-dependent inhibition but not a tumorigenic phenotype. IL-2-independent CTLL-2 clones did not secrete detectable quantities of IL-2 into culture supernatant and exhibited reduced sensitivity to the inhibitory effects of both IL-2 and IL-2 receptor antibody. These results suggest that the IL-2 autocrine loop within these cells involves intracellular IL-2/IL-2 receptor binding. The apparent lack of IL-2 production and poor responsiveness to IL-2 or IL-2 antibodies displayed by cell lines from ATL patients may be explained by an intracellular IL-2/IL-2 receptor autocrine loop.
Somat Cell Mol Genet 1990 Jan
PMID:Autonomous growth of lymphoid cells following IL-2 expression from retrovirus vectors containing HIV-1 trans-acting elements. 240 56


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