T Cell Activation-dependent Association between the p85 Subunit of the Phosphatidylinositol 3-Kinase and Grb2/Phospholipase C-γ1-binding Phosphotyrosyl Protein pp36/38

T-cell activation involves two distinct signal transduction pathways. Antigen-specific signaling events are initiated by T-cell receptor recognition of cognate peptide presented by major histocompatibility complex molecules. Costimulatory signals, which are required for optimal T-cell activation and for overcoming the induction of anergy, can be provided by the homodimeric T-cell glycoprotein CD28 through its interaction with the counterreceptors B7-1 and B7-2 on antigen-presenting cells. Ligation of CD28 results in its phosphorylation on tyrosines and the subsequent recruitment and activation of phosphatidylinositol 3-kinase (PI 3-kinase). It has been suggested that the induced association of CD28 and PI 3-kinase is required for costimulation. We report here that ligation of CD19, a heterologous B-cell receptor that also associates with and activates PI 3-kinase upon ligation, failed to costimulate interleukin-2 production. Moreover, pharmacological inhibition of PI 3-kinase activity failed to block costimulation mediated by CD28. By mutational analysis, we demonstrate that disruption of PI 3-kinase association with CD28 also did not abrogate costimulation. These results argue that PI 3-kinase association with CD28 is neither necessary nor sufficient for costimulation of interleukin-2 production. Finally, we identify specific amino acid residues required for CD28-mediated costimulatory activity.

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The Class II Phosphatidylinositol 3 kinase C2β Is Required for the Activation of the K+ Channel KCa3.1 and CD4 T-Cells

Molecular Biology of the Cell ◽

10.1091/mbc.e09-05-0390 ◽

2009 ◽

Vol 20 (17) ◽

pp. 3783-3791 ◽

Cited By ~ 46

Author(s):

Shekhar Srivastava ◽

Lie Di ◽

Olga Zhdanova ◽

Zhai Li ◽

Santosha Vardhana ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Activation ◽

Cd4 T Cells ◽

Critical Role ◽

Class Ii ◽

K Channel ◽

Channel Activity ◽

Phosphatidylinositol 3 Kinase ◽

Phosphatidylinositol 3

The Ca2+-activated K+ channel KCa3.1 is required for Ca2+ influx and the subsequent activation of T-cells. We previously showed that nucleoside diphosphate kinase beta (NDPK-B), a mammalian histidine kinase, directly phosphorylates and activates KCa3.1 and is required for the activation of human CD4 T lymphocytes. We now show that the class II phosphatidylinositol 3 kinase C2β (PI3K-C2β) is activated by the T-cell receptor (TCR) and functions upstream of NDPK-B to activate KCa3.1 channel activity. Decreased expression of PI3K-C2β by siRNA in human CD4 T-cells resulted in inhibition of KCa3.1 channel activity. The inhibition was due to decreased phosphatidylinositol 3-phosphate [PI(3)P] because dialyzing PI3K-C2β siRNA-treated T-cells with PI(3)P rescued KCa3.1 channel activity. Moreover, overexpression of PI3K-C2β in KCa3.1-transfected Jurkat T-cells led to increased TCR-stimulated activation of KCa3.1 and Ca2+ influx, whereas silencing of PI3K-C2β inhibited both responses. Using total internal reflection fluorescence microscopy and planar lipid bilayers, we found that PI3K-C2β colocalized with Zap70 and the TCR in peripheral microclusters in the immunological synapse. This is the first demonstration that a class II PI3K plays a critical role in T-cell activation.

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Cloning and characterization of Lnk, a signal transduction protein that links T-cell receptor activation signal to phospholipase C gamma 1, Grb2, and phosphatidylinositol 3-kinase.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.92.25.11618 ◽

1995 ◽

Vol 92 (25) ◽

pp. 11618-11622 ◽

Cited By ~ 112

Author(s):

X. Huang ◽

Y. Li ◽

K. Tanaka ◽

K. G. Moore ◽

J. I. Hayashi

Keyword(s):

Signal Transduction ◽

T Cell ◽

Phospholipase C ◽

T Cell Receptor ◽

Cell Receptor ◽

Receptor Activation ◽

Phosphatidylinositol 3 Kinase ◽

Signal Transduction Protein ◽

Phosphatidylinositol 3

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

Biochemical Journal ◽

10.1042/bj2930835 ◽

1993 ◽

Vol 293 (3) ◽

pp. 835-842 ◽

Cited By ~ 30

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.

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CTLA-4 and PD-1 Receptors Inhibit T-Cell Activation by Distinct Mechanisms

Molecular and Cellular Biology ◽

10.1128/mcb.25.21.9543-9553.2005 ◽

2005 ◽

Vol 25 (21) ◽

pp. 9543-9553 ◽

Cited By ~ 1002

Author(s):

Richard V. Parry ◽

Jens M. Chemnitz ◽

Kenneth A. Frauwirth ◽

Anthony R. Lanfranco ◽

Inbal Braunstein ◽

...

Keyword(s):

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Direct Evidence ◽

Phosphatidylinositol 3 Kinase ◽

Akt Phosphorylation ◽

Akt Activation ◽

Pi3k Activation ◽

Cellular Phenotypes ◽

Induced Changes

ABSTRACT CTLA-4 and PD-1 are receptors that negatively regulate T-cell activation. Ligation of both CTLA-4 and PD-1 blocked CD3/CD28-mediated upregulation of glucose metabolism and Akt activity, but each accomplished this regulation using separate mechanisms. CTLA-4-mediated inhibition of Akt phosphorylation is sensitive to okadaic acid, providing direct evidence that PP2A plays a prominent role in mediating CTLA-4 suppression of T-cell activation. In contrast, PD-1 signaling inhibits Akt phosphorylation by preventing CD28-mediated activation of phosphatidylinositol 3-kinase (PI3K). The ability of PD-1 to suppress PI3K/AKT activation was dependent upon the immunoreceptor tyrosine-based switch motif located in its cytoplasmic tail, adding further importance to this domain in mediating PD-1 signal transduction. Lastly, PD-1 ligation is more effective in suppressing CD3/CD28-induced changes in the T-cell transcriptional profile, suggesting that differential regulation of PI3K activation by PD-1 and CTLA-4 ligation results in distinct cellular phenotypes. Together, these data suggest that CTLA-4 and PD-1 inhibit T-cell activation through distinct and potentially synergistic mechanisms.

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CTLA-4 and PD-1 Receptors Inhibit T-Cell Activation by Distinct Mechanisms.

Blood ◽

10.1182/blood.v104.11.2657.2657 ◽

2004 ◽

Vol 104 (11) ◽

pp. 2657-2657 ◽

Cited By ~ 2

Author(s):

Jens M. Chemnitz ◽

James L. Riley ◽

Kenneth A. Frauwirth ◽

Inbal Braunstein ◽

Sumire V. Kobayashi ◽

...

Keyword(s):

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Direct Evidence ◽

Differential Regulation ◽

Phosphatidylinositol 3 Kinase ◽

Akt Phosphorylation ◽

Pi3k Activation ◽

Cellular Phenotypes ◽

Induced Changes

Abstract CTLA-4 and PD-1 are receptors that negatively regulate T cell activation. Ligation of both CTLA-4 and PD-1 blocked CD3/CD28 mediated upregulation of glucose metabolism and Akt activity, but each accomplished this regulation using separate mechanisms. CTLA-4 mediated inhibition of Akt phosphorylation is sensitive to okadaic acid, providing direct evidence that PP2A plays a prominent role in mediating CTLA-4 suppression of T cell activation. In contrast, PD-1 signaling inhibits Akt phosphorylation by preventing CD28 mediated activation of phosphatidylinositol 3-kinase (PI3K). The ability of PD-1 to suppress PI3K/Atk activation was dependent upon the ITSM located in its cytoplasmic tail. Lastly, PD-1 ligation is more effective in suppressing CD3/28 induced changes in the T cell transcriptional profile, suggesting that differential regulation of PI3K activation by PD-1 and CTLA-4 ligation results in distinct cellular phenotypes. Together, these data suggest that CTLA-4 and PD-1 inhibit T cell activation through distinct and potentially synergistic mechanisms.

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