scholarly journals Rab6-dependent retrograde traffic of LAT controls immune synapse formation and T cell activation

2018 ◽  
Vol 215 (4) ◽  
pp. 1245-1265 ◽  
Author(s):  
Jean-Marie Carpier ◽  
Andres E. Zucchetti ◽  
Laurence Bataille ◽  
Stéphanie Dogniaux ◽  
Massiullah Shafaq-Zadah ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
T Lymphocyte ◽  
Cell Activation ◽  
Lymphocyte Activation ◽  
Retrograde Transport ◽  
Small Gtpase ◽  
Immune Synapse ◽  
T Lymphocyte Activation ◽  
Retrograde Traffic

The adapter molecule linker for activation of T cells (LAT) orchestrates the formation of signalosomes upon T cell receptor (TCR) stimulation. LAT is present in different intracellular pools and is dynamically recruited to the immune synapse upon stimulation. However, the intracellular traffic of LAT and its function in T lymphocyte activation are ill defined. We show herein that LAT, once internalized, transits through the Golgi–trans-Golgi network (TGN), where it is repolarized to the immune synapse. This retrograde transport of LAT depends on the small GTPase Rab6 and the target soluble N-ethylmaleimide-sensitive factor attachment protein receptor (t-SNARE) Syntaxin-16, two regulators of the endosome-to-Golgi/TGN retrograde transport. We also show in vitro in Syntaxin-16– or Rab6-silenced human cells and in vivo in CD4+ T lymphocytes of the Rab6 knockout mouse that this retrograde traffic controls TCR stimulation. These results establish that the retrograde traffic of LAT from the plasma membrane to the Golgi-TGN controls the polarized delivery of LAT at the immune synapse and T lymphocyte activation.

scholarly journals Shikonin Suppresses Human T Lymphocyte Activation through Inhibition of IKKβActivity and JNK Phosphorylation

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Ting Li ◽  
Fenggen Yan ◽  
Rui Wang ◽  
Hua Zhou ◽  
Liang Liu
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
T Lymphocyte ◽  
Cell Activation ◽  
Nuclear Translocation ◽  
Lymphocyte Activation ◽  
Immunosuppressive Agent ◽  
Buffy Coat ◽  
T Lymphocyte Activation

The key role of T cells has been elaborated in mediating immune responses and pathogenesis of human inflammatory and autoimmune conditions. In the current study the effect of shikonin, a compound isolated from a medicinal plant, on inhibition of T-cell activation was firstly examined by using primary human T lymphocytes isolated from buffy coat. Results showed that shikonin dose dependently suppressed T-cell proliferation, IL-2 and IFN-γsecretion, CD69 and CD25 expression, as well as cell cycle arrest activated by costimulation of PMA/ionomycin or OKT-3/CD28 monoclonal antibodies. Moreover, these inhibitory responses mediated by shikonin were found to be associated with suppression of the NF-κB signaling pathway via inhibition of the IKKα/βphosphorylation, IκB-αphosphorylation and degradation, and NF-κB nuclear translocation by directly decreasing IKKβactivity. Moreover, shikonin suppressed JNK phosphorylation in the MAPKs pathway of T cells. In this connection, we conclude that shikonin could suppress T lymphocyte activation through suppressing IKKβactivity and JNK signaling, which suggests that shikonin is valuable for further investigation as a potential immunosuppressive agent.

scholarly journals Voltage-gated potassium channels regulate calcium-dependent pathways involved in human T lymphocyte activation.

1993 ◽  
Vol 177 (3) ◽  
pp. 637-645 ◽  
Author(s):  
C S Lin ◽  
R C Boltz ◽  
J T Blake ◽  
M Nguyen ◽  
A Talento ◽  
...  
Keyword(s):  
T Cell ◽  
Potassium Channels ◽  
T Cell Activation ◽  
T Lymphocyte ◽  
Cell Activation ◽  
Lymphocyte Activation ◽  
Voltage Gated ◽  
Lymphokine Production ◽  
T Lymphocyte Activation ◽  
Human T Lymphocyte

The role that potassium channels play in human T lymphocyte activation has been investigated by using specific potassium channel probes. Charybdotoxin (ChTX), a blocker of small conductance Ca(2+)-activated potassium channels (PK,Ca) and voltage-gated potassium channels (PK,V) that are present in human T cells, inhibits the activation of these cells. ChTX blocks T cell activation induced by signals (e.g., anti-CD2, anti-CD3, ionomycin) that elicit a rise in intracellular calcium ([Ca2+]i) by preventing the elevation of [Ca2+]i in a dose-dependent manner. However, ChTX has no effect on the activation pathways (e.g., anti-CD28, interleukin 2 [IL-2]) that are independent of a rise in [Ca2+]i. In the former case, both proliferative response and lymphokine production (IL-2 and interferon gamma) are inhibited by ChTX. The inhibitory effect of ChTX can be demonstrated when added simultaneously, or up to 4 h after the addition of the stimulants. Since ChTX inhibits both PK,Ca and PK,V, we investigated which channel is responsible for these immunosuppressive effects with the use of two other peptides, noxiustoxin (NxTX) and margatoxin (MgTX), which are specific for PK,V. These studies demonstrate that, similar to ChTX, both NxTX and MgTX inhibit lymphokine production and the rise in [Ca2+]i. Taken together, these data provide evidence that blockade of PK,V affects the Ca(2+)-dependent pathways involved in T lymphocyte proliferation and lymphokine production by diminishing the rise in [Ca2+]i that occurs upon T cell activation.

scholarly journals DC-HIL is a negative regulator of T lymphocyte activation

Blood ◽  
2007 ◽  
Vol 109 (10) ◽  
pp. 4320-4327 ◽  
Author(s):  
Jin-Sung Chung ◽  
Kota Sato ◽  
Irene I. Dougherty ◽  
Ponciano D. Cruz ◽  
Kiyoshi Ariizumi
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
T Lymphocyte ◽  
Cell Activation ◽  
Lymphocyte Activation ◽  
Negative Regulator ◽  
Secondary Response ◽  
Inhibitory Function ◽  
T Lymphocyte Activation

Abstract T-cell activation is the net product of competing positive and negative signals transduced by regulatory molecules on antigen-presenting cells (APCs) binding to corresponding ligands on T cells. Having previously identified DC-HIL as a receptor expressed by APCs that contains an extracellular immunoglobulin (Ig)–like domain, we postulated that it plays a role in T-cell activation. To probe this function, we created soluble recombinant DC-HIL, which we observed to bind activated (but not resting) T cells, indicating that expression of the putative ligand on T cells is induced by activation. Binding of DC-HIL to naive T cells attenuated these cells' primary response to anti-CD3 antibody, curtailing IL-2 production, and preventing entry into the cell cycle. DC-HIL also inhibited reactivation of T cells previously activated by APCs (secondary response). By contrast, addition of soluble DC-HIL to either allogeneic or ovalbumin-specific lymphocyte reactions augmented T-cell proliferation, and its injection into mice during the elicitation (but not sensitization) phase of contact hypersensitivity exacerbated ear-swelling responses. Mutant analyses showed the inhibitory function of DC-HIL to reside in its extracellular Ig-like domain. We conclude that endogenous DC-HIL is a negative regulator of T lymphocyte activation, and that this native inhibitory function can be blocked by exogenous DC-HIL, leading to enhanced immune responses.

scholarly journals Retrograde And Anterograde Transport Of LAT-Vesicles During The Immunological Synapse Formation: Defining The Finely-Tuned Mechanism

2020 ◽  
Author(s):  
Juan José Saez ◽  
Stéphanie Dogniaux ◽  
Massiullah Shafaq-Zadah ◽  
Ludger Johannes ◽  
Claire Hivroz ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Synapse Formation ◽  
Immunological Synapse ◽  
Retrograde Transport ◽  
Anterograde Transport ◽  
Immune Synapse ◽  
Cellular Context ◽  
Intracellular Compartments

ABSTRACTLAT is an important player of the signaling cascade induced by TCR activation. This adapter molecule is present at the plasma membrane of T lymphocytes and more abundantly in intracellular compartments. Upon T-cell activation the intracellular pool of LAT is recruited to the immune synapse (IS). We previously described two pathways controlling LAT trafficking: retrograde transport from endosomes to the TGN, and anterograde traffic from the Golgi to the IS. We address the specific role of 4 proteins, the GTPase Rab6, the t-SNARE syntaxin-16, the v-SNARE VAMP7 and the golgin GMAP210, in each pathway. Using different methods (endocytosis and Golgi trap assays, confocal and TIRF microscopy, TCR-signalosome pull down) we show that syntaxin-16 is regulating the retrograde transport of LAT whereas VAMP7 is regulating the anterograde transport. Moreover, GMAP210 and Rab6, known to contribute in both pathways, are in our cellular context specifically and respectively involved in anterograde and retrograde transport of LAT. Altogether, our data describe how retrograde and anterograde pathways coordinate LAT enrichment at the IS and point the Golgi as a central hub for the polarized recruitment of LAT to the IS. The role that this finely-tuned transport of signaling molecules plays in T-cell activation is discussed.

scholarly journals Systemic and Mucosal T-Lymphocyte Activation Induced by Recombinant Adenovirus Vaccines in Rhesus Monkeys

2009 ◽  
Vol 83 (20) ◽  
pp. 10596-10604 ◽  
Author(s):  
Yue Sun ◽  
Robert T. Bailer ◽  
Srinivas S. Rao ◽  
John R. Mascola ◽  
Gary J. Nabel ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
T Lymphocyte ◽  
Rhesus Monkeys ◽  
Recombinant Adenovirus ◽  
Lymphocyte Activation ◽  
T Cell Responses ◽  
Cell Responses ◽  
T Lymphocyte Activation

ABSTRACT The administration of vectors designed to elicited cell-mediated immune responses may have other consequences that are clinically significant. To explore this possibility, we evaluated T-cell activation during the first 2 months after recombinant adenovirus serotype 5 (rAd5) prime or boost immunizations in rhesus monkeys. We also evaluated the kinetics of T-lymphocyte activation in both the systemic and the mucosal compartments after rAd5 administration in monkeys with preexisting immunity to Ad5. The rAd5 immunization induced lower-frequency Gag epitope-specific CD8+ T cells in the colonic mucosa than in the peripheral blood. There was evidence of an expansion of the simian immunodeficiency virus Gag-specific CD8+ T-cell responses, but not the Ad5 hexon-specific T-cell responses, following a homologous rAd5 boost. A striking but transient T-lymphocyte activation in both the systemic and the mucosal compartments of rhesus monkeys was observed after rAd5 immunization. These findings indicate that the administration of a vaccine vector such as Ad5 can induce a global activation of T cells.

scholarly journals Human plasma-like medium improves T lymphocyte activation

2019 ◽  
Author(s):  
Michael A. Leney-Greene ◽  
Arun K. Boddapati ◽  
Helen C. Su ◽  
Jason Cantor ◽  
Michael J. Lenardo
Keyword(s):  
Human Plasma ◽  
T Cell Activation ◽  
T Lymphocyte ◽  
Cell Activation ◽  
Lymphocyte Activation ◽  
Cell Physiology ◽  
Transcriptional Responses ◽  
T Lymphocyte Activation ◽  
Synthetic Media

SUMMARYT lymphocytes are critical for effective immunity and the ability to study their behavior in synthetic media in vitro facilitates major discoveries in their development, function, and fate. However, the composition of human plasma differs from synthetic media and we hypothesized that these differences could have important effects on cell physiology. We therefore compared T lymphocyte activation in human plasma-like medium (HPLM) to RPMI supplemented with dialyzed FBS (RPMIdFBS) and found that it entrained markedly different transcriptional responses. We also found that the concentration of calcium in RPMIdFBS is six-fold lower than HPLM causing altered T cell activation which could be reversed by calcium addition. Thus, investigators should be cognizant of differences between commonly used media formulations and HPLM which is based on the in vivo plasma environment as these could profoundly affect their experimental results. Physiologic media may be a valuable new way to study immune cells in culture.

scholarly journals B7-1 or B7-2 Is Required to Produce the Lymphoproliferative Phenotype in Mice Lacking Cytotoxic T Lymphocyte–associated Antigen 4 (CTLA-4)

1999 ◽  
Vol 189 (2) ◽  
pp. 435-440 ◽  
Author(s):  
Didier A. Mandelbrot ◽  
Alexander J. McAdam ◽  
Arlene H. Sharpe
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
T Lymphocyte ◽  
Cell Activation ◽  
Cytotoxic T Lymphocyte ◽  
Lymphocyte Activation ◽  
Lymphoproliferative Disease ◽  
Inhibitory Function ◽  
B7 Molecules

The costimulatory molecules B7-1 and B7-2 regulate T lymphocyte activation by delivering activating signals through CD28 and inhibitory signals through cytotoxic T lymphocyte–associated antigen 4 (CTLA-4). The importance of CTLA-4–mediated inhibition was demonstrated by the uncontrolled T cell activation and lymphoproliferative disease that develops in CTLA-4–deficient (−/−) mice. To examine the role of B7 signaling in the activation of CTLA-4–deficient T cells, we bred CTLA-4−/− mice with mice lacking B7-1, B7-2, or both B7 molecules. The CTLA-4/B7-1−/− and the CTLA-4/B7-2−/− mice develop lymphoproliferation and enhanced T cell activation. Mice lacking CTLA-4, B7-1, and B7-2 have a normal life-span, and do not have lymphocytic infiltrates in any organs, or increased T cell activation. Therefore, the two B7 molecules have overlapping functions, since either B7-1 or B7-2 alone can cause the CTLA-4−/− phenotype. Elimination of both B7-1 and B7-2 from the CTLA-4– deficient mouse abrogates the lymphocyte activation and disease, and does not reveal evidence for additional stimulatory CD28 ligands. The CTLA-4−/− phenotype can be reproduced with anti-CD28 antibody in mice lacking CTLA-4, B7-1, and B7-2, but wild-type mice are unaffected by the same treatment. This suggests that the inhibitory function of CTLA-4 can overcome strong CD28-mediated signaling in vivo.

RecombinantPseudomonasexoenzyme S and exoenzyme S fromPseudomonas aeruginosaDG1 share the ability to stimulate T lymphocyte proliferation

1999 ◽  
Vol 45 (7) ◽  
pp. 607-611 ◽  
Author(s):  
Tony F Bruno ◽  
Donald E Woods ◽  
Douglas G Storey ◽  
Christopher H Mody
Keyword(s):  
Pseudomonas Aeruginosa ◽  
T Cell ◽  
T Cell Activation ◽  
T Lymphocyte ◽  
Lymphocyte Proliferation ◽  
Cell Activation ◽  
Lymphocyte Activation ◽  
Activation Markers ◽  
Exoenzyme S ◽  
T Lymphocyte Proliferation

Exoenzyme S from P. aeruginosa DG1 and recombinant exoenzyme S derived from strain 388 have distinct characteristics, which has led to a controversy about their homology and their pathophysiologic consequences. We have been investigating the ability of exoenzyme S to activate T lymphocytes, and therefore performed studies to determine whether exoenzyme S from P. aeruginosa DG1 and recombinant exoenzyme S derived from strain 388 and expressed in Pseudomonas aeruginosa PA103 or in E. coli BL21(DE3), could induce T lymphocyte activation and proliferation. Both preparations were able to activate T cells and induce lymphocyte proliferation at similar levels as measured by flow cytometry of surface-activation markers and DNA synthesis, respectively. Further, a monoclonal antibody raised against exoenzyme S from strain DG1 partially neutralized T cell activation induced by recombinant exoenzyme S and bound to it in an immunoblot suggesting that the epitope responsible for T cell activation is shared by exoenzyme S from strain DG1 and recombinant exoenzyme S. These data suggest that the two different preparations of exoenzyme S, despite biochemical differences, share the characteristic that is responsible for T lymphocyte activation.Key words: exoenzyme S, Pseudomonas aeruginosa, T lymphocyte, cystic fibrosis.

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