scholarly journals Submicromolar La3+ concentrations block the calcium release-activated channel, and impair CD69 and CD25 expression in CD3- or thapsigargin-activated Jurkat cells

1996 ◽  
Vol 313 (3) ◽  
pp. 909-913 ◽  
Author(s):  
Claude AUSSEL ◽  
Rachid MARHABA ◽  
Claudette PELASSY ◽  
Jean-Philippe BREITTMAYER
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Calcium Release ◽  
Cell Signalling ◽  
Interleukin 2 ◽  
Jurkat Cells ◽  
T Cell Signalling ◽  
A Chain ◽  
20 Nm

The calcium release-activated channel (CRAC) opened in Jurkat cells activated either with CD3 monoclonal antibody or the endoplasmic reticulum Ca2+-ATPase blocker, thapsigargin, is blocked by La3+ with an IC50 of 20 nM. Similarly, the entry of Mn2+, used as a surrogate for Ca2+, is also blocked by submicromolar La3+ concentrations. La3+ seems to play its role simply by plugging the CRAC because this ion does not penetrate the cells, as demonstrated by chelation experiments with EGTA. Blocking the Ca2+ influx in activated Jurkat cells results in a lack of expression of CD25, a chain of the interleukin-2 receptor and of CD69, a marker of T-cell activation. By contrast, the very early steps of the T-cell signalling pathway such as the release of Ca2+ from intracellular stores and the subsequent inhibition of phosphatidylserine synthesis are not affected by La3+.

scholarly journals Signalling through CD28 T-cell activation pathway involves an inositol phospholipid-specific phospholipase C activity

1993 ◽  
Vol 293 (3) ◽  
pp. 835-842 ◽  
Author(s):  
J Nunes ◽  
S Klasen ◽  
M D Franco ◽  
C Lipcey ◽  
C Mawas ◽  
...  
Keyword(s):  
T Cell ◽  
Phospholipase C ◽  
T Cell Activation ◽  
Cell Activation ◽  
Interleukin 2 ◽  
Jurkat Cells ◽  
Cd28 Molecule ◽  
Human T Cell ◽  
Protein Kinase C Inhibitor ◽  
Human T Cell Line

Stimulation of the human T-cell line, Jurkat, by a monoclonal antibody (mAb) directed against the CD28 molecule leads to sustained increases in intracellular levels of Ca2+ ([Ca2+]i); the initial rise in Ca2+ comes from internal stores, followed by Ca2+ entry into the cells. The CD28 molecule also appears to activate polyphosphoinositide (InsPL)-specific phospholipase C (PLC) activity in Jurkat cells, as demonstrated by PtdInsP2 breakdown, InsP3 and 1,2-diacylglycerol generation and PtdIns resynthesis. We also observed that interleukin-2 (IL2) production induced via CD28 triggering was sensitive to a selective protein kinase C inhibitor. Of the four other anti-CD28 mAbs (CD28.2, CD28.4, CD28.5, CD28.6) tested, only one (CD28.5) was unable to generate any InsPL-specific PLC or IL2 secretion. However, the cross-linking of cell-bound CD28.5 with anti-mouse Ig antibodies led to an increase in [Ca2+]i. CD28-molecule clustering in itself appears to be a sufficient signal for induction of PLC activity.

scholarly journals Phosphorylation of two cytosolic proteins. An early event of T-cell activation

1989 ◽  
Vol 258 (2) ◽  
pp. 505-510 ◽  
Author(s):  
J F Peyron ◽  
C Aussel ◽  
B Ferrua ◽  
H Häring ◽  
M Fehlmann
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Peptide Mapping ◽  
Interleukin 2 ◽  
Jurkat Cells ◽  
Early Event ◽  
Ionophore A23187 ◽  
Receptor Complex ◽  
Cytosolic Proteins

T lymphocytes can be activated to proliferate by triggering the T-cell antigen-receptor complex (CD3-Ti) with anti-CD3 (Cluster of Differentiation 3) monoclonal antibody (mAb) or with the mitogenic lectin phytohaemagglutinin A (PHA). We have investigated the relationship between lymphocyte activation and protein phosphorylation in the human leukaemic T-cell line Jurkat. Incubation of 32P-labelled Jurkat cells with anti-CD3 mAb or PHA induced the phosphorylation of two cytosolic proteins that migrate with apparent Mr values of 21,000 (pp21) and 23,000 (pp23) and pI values of 5.1 and 5.0 respectively. Peptide mapping of the two proteins produced the same phosphopeptides pattern, suggesting that pp21 and pp23 are closely related. The phosphorylation of pp21 and pp23 induced by anti-CD3 mAb appeared to be transient, since it was already detected 2 min after the addition of the mAb, reached a maximum at 10 min and recovered its basal level after 1 h. Phosphorylation of pp21 and pp23 could also be elicited by the Ca2+ ionophore A23187 and sodium orthovanadate (Na3VO4), two agents that bypass the T-cell-receptor complex and produced an increase in cytosolic Ca2+ concentration. In addition, we found that vanadate, like the Ca2+ ionophore, induced the secretion of interleukin-2 (IL-2) when used in combination with a submitogenic concentration of the phorbol ester 12-O-tetradecanoylphorbol 13-acetate. These results show that the Ca2+-dependent phosphorylation of pp21 and pp23 represents an early event in the process of signal transduction through the CD3-Ti receptor complex.

Opposing roles of serine/threonine kinases MEKK1 and LOK in regulating the CD28 responsive element in T-cells

2002 ◽  
Vol 363 (1) ◽  
pp. 175-182 ◽  
Author(s):  
Li TAO ◽  
Scott WADSWORTH ◽  
Jason MERCER ◽  
Cynthia MUELLER ◽  
Kirsten LYNN ◽  
...  
Keyword(s):  
T Cell ◽  
Reporter Gene ◽  
T Cell Activation ◽  
Cell Activation ◽  
Interleukin 2 ◽  
Jurkat Cells ◽  
Dominant Negative Mutant ◽  
Nuclear Factor ◽  
Response Element ◽  
Enhancer Element

T-cell activation requires signals from both the T-cell receptor (TcR) and other co-stimulatory molecules such as CD28. TcR- and CD28-mediated signals are integrated during T-cell activation resulting in the expression of cytokine genes such as interleukin-2 (IL-2). An enhancer element (CD28RE) of the IL-2 gene specifically responsive to CD28 signals has been previously identified and characterized. This response element and an adjacent Activated Protein-1 (nuclear factor-interleukin-2B) site together (RE/AP1) were shown to complex with c-rel, AP-1 and other factors. However, details of the signal transduction pathways leading from CD28 to the composite response element remain poorly understood. We present data showing that overexpression of the serine threonine kinase, mitogen-activated protein kinase/extracellular-signal-regulated kinase kinase kinase-1 (MEKK1), but not nuclear factor-κB inducing kinase, or MAP kinase/ERK kinase-1 (MEK1), can significantly increase the level of CD28RE/AP1-driven luciferase (Luc) reporter gene expression in Jurkat E6-1 cells. A MEKK1 dominant negative mutant blocked such activation induced by stimulation with Raji B cells and the superantigen staphylococcus enterotoxin E (SEE), as well as via CD3/CD28. Mutations in either site of the RE/AP1 element abolished MEKK1-induced Luc expression. Calcineurin inhibitors, CsA and FK520, or inhibitors of p38 kinase (SB 203580), or MEK1 (PD 098059), did not affect MEKK1-induced reporter activation. These results directly implicate MEKK1 in the CD28 signalling pathway that activates the CD28 response element. Co-expression of the lymphocyte-oriented kinase (LOK) kinase attenuated Raji/SEE-induced IL-2 production in Jurkat cells, as well as MEKK1 and Raji/SEE-induced reporter gene activation. These data suggest that MEKK1 and LOK may have opposing roles in regulating the CD28RE/AP1 element.

Protein kinase Cθ: the pleiotropic T-cell signalling intermediate

2014 ◽  
Vol 42 (6) ◽  
pp. 1512-1518 ◽  
Author(s):  
Katarzyna Wachowicz ◽  
Gottfried Baier
Keyword(s):  
T Cell ◽  
Protein Kinase ◽  
T Cell Activation ◽  
Th17 Cell ◽  
Cell Activation ◽  
Cell Signalling ◽  
Cell Receptor ◽  
Cell Phenotype ◽  
Inhibitory Circuits ◽  
T Cell Signalling

Activating as well as inhibitory circuits tightly regulate T-cell activation thresholds and effector differentiation processes enabling proper immune response outcomes. Recently, an additional molecular link between T-cell receptor signalling and CD4+ Th17 cell skewing has been reported, namely that protein kinase C (PKC) θ critically regulates Th17/Th1 phenotypic differentiation and plasticity in CD4+ T-cells by selectively acting as a ‘reprogramming element’ that suppresses Th1-typical genes during Th17-mediated immune activation in order to stabilize a Th17 cell phenotype.

scholarly journals CD28-B7 interactions allow the induction of CD8+ cytotoxic T lymphocytes in the absence of exogenous help.

1993 ◽  
Vol 177 (6) ◽  
pp. 1791-1796 ◽  
Author(s):  
F A Harding ◽  
J P Allison
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cytotoxic T Cells ◽  
Interleukin 2 ◽  
Cell Receptor ◽  
Histocompatibility Complex ◽  
Necessary And Sufficient ◽  
Additional Antigen

The activation requirements for the generation of CD8+ cytotoxic T cells (CTL) are poorly understood. Here we demonstrate that in the absence of exogenous help, a CD28-B7 interaction is necessary and sufficient for generation of class I major histocompatibility complex-specific CTL. Costimulation is required only during the inductive phase of the response, and not during the effector phase. Transfection of the CD28 counter receptor, B7, into nonstimulatory P815 cells confers the ability to elicit P815-specific CTL, and this response can be inhibited by anti-CD28 Fab or by the chimeric B7-binding protein CTLA4Ig. Anti-CD28 monoclonal antibody (mAb) can provide a costimulatory signal to CD8+ T cells when the costimulatory capacity of splenic stimulators is destroyed by chemical fixation. CD28-mediated signaling provokes the release of interleukin 2 (IL-2) from the CD8+ CTL precursors, as anti-CD28 mAb could be substituted for by the addition of IL-2, and an anti-IL-2 mAb can block the generation of anti-CD28-induced CTL. CD4+ cells are not involved in the costimulatory response in the systems examined. We conclude that CD8+ T cell activation requires two signals: an antigen-specific signal mediated by the T cell receptor, and an additional antigen nonspecific signal provided via a CD28-B7 interaction.

scholarly journals SLFN2 protection of tRNAs from stress-induced cleavage is essential for T cell–mediated immunity

Science ◽  
2021 ◽  
Vol 372 (6543) ◽  
pp. eaba4220 ◽  
Author(s):  
Tao Yue ◽  
Xiaoming Zhan ◽  
Duanwu Zhang ◽  
Ruchi Jain ◽  
Kuan-wen Wang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Interleukin 2 ◽  
Cell Receptor ◽  
Cell Mediated Immunity ◽  
Activated T Cells ◽  
Granule Formation

Reactive oxygen species (ROS) increase in activated T cells because of metabolic activity induced to support T cell proliferation and differentiation. We show that these ROS trigger an oxidative stress response that leads to translation repression. This response is countered by Schlafen 2 (SLFN2), which directly binds transfer RNAs (tRNAs) to protect them from cleavage by the ribonuclease angiogenin. T cell–specific SLFN2 deficiency results in the accumulation of tRNA fragments, which inhibit translation and promote stress-granule formation. Interleukin-2 receptor β (IL-2Rβ) and IL-2Rγ fail to be translationally up-regulated after T cell receptor stimulation, rendering SLFN2-deficient T cells insensitive to interleukin-2’s mitogenic effects. SLFN2 confers resistance against the ROS-mediated translation-inhibitory effects of oxidative stress normally induced by T cell activation, permitting the robust protein synthesis necessary for T cell expansion and immunity.

scholarly journals Bispecific T-Cell Engagers Targeting Membrane-Bound IgE

Biomedicines ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1568
Author(s):  
Aleksandra Rodak ◽  
Gerhard Stadlmayr ◽  
Katharina Stadlbauer ◽  
Dominic Lichtscheidl ◽  
Madhusudhan Reddy Bobbili ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
T Cell Activation ◽  
Cell Activation ◽  
Jurkat Cells ◽  
Single Chain ◽  
Ige Antibodies ◽  
Serum Ige ◽  
Single Chain Fv ◽  
Membrane Bound

The increased incidence of allergies and asthma has sparked interest in IgE, the central player in the allergic response. Interaction with its high-affinity receptor FcεRI leads to sensitization and allergen presentation, extracellular membrane-proximal domain in membrane IgE can act as an antigen receptor on B cells, and the interaction with low-affinity IgE receptor CD23 additionally influences its homeostatic range. Therapeutic anti-IgE antibodies act by the inhibition of IgE functions by interfering with its receptor binding or by the obliteration of IgE-B cells, causing a reduction of serum IgE levels. Fusion proteins of antibody fragments that can act as bispecific T-cell engagers have proven very potent in eliciting cytotoxic T-lymphocyte-mediated killing. We have tested five anti-IgE Fc antibodies, recognizing different epitopes on the membrane-expressed IgE, for the ability to elicit specific T-cell activation when expressed as single-chain Fv fragments fused with anti-CD3ε single-chain antibody. All candidates could specifically stain the cell line, expressing the membrane-bound IgE-Fc and bind to CD3-positive Jurkat cells, and the specific activation of engineered CD3-overexpressing Jurkat cells and non-stimulated CD8-positive cells was demonstrated for 8D6- and ligelizumab-based bispecific antibodies. Thus, such anti-IgE antibodies have the potential to be developed into agents that reduce the serum IgE concentration by lowering the numbers of IgE-secreting cells.

scholarly journals Antigen-independent activation of naive and memory resting T cells by a cytokine combination.

1994 ◽  
Vol 180 (3) ◽  
pp. 1159-1164 ◽  
Author(s):  
D Unutmaz ◽  
P Pileri ◽  
S Abrignani
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Interleukin 2 ◽  
Effector Function ◽  
Necrosis Factor Alpha ◽  
Naive T Cells ◽  
Naïve T Cells

We investigated whether human resting T cells could be activated to proliferate and display effector function in the absence of T cell receptor occupancy. We report that combination of interleukin 2 (IL-2), tumor necrosis factor alpha, and IL-6 activated highly purified naive (CD45RA+) and memory (CD45RO+) resting CD4+ T cells to proliferate. Under this condition, memory resting T cells could also display effector function as measured by lymphokine synthesis and help for immunoglobulin production by B cells. This novel Ag-independent pathway of T cell activation may play an important role in vivo in recruiting effector T cells at the site of immune response and in maintaining the clonal size of memory T cells in the absence of antigenic stimulation. Moreover, cytokines can induce proliferation of naive T cells without switch to memory phenotype and this may help the maintenance of the peripheral pool of naive T cells.

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