scholarly journals Integrating Receptor Signal Inputs That Influence Small Rho GTPase Activation Dynamics at the Immunological Synapse

2009 ◽  
Vol 29 (11) ◽  
pp. 2997-3006 ◽  
Author(s):  
Konstantina Makrogianneli ◽  
Leo M. Carlin ◽  
Melanie D. Keppler ◽  
Daniel R. Matthews ◽  
Enyinnaya Ofo ◽  
...  
Keyword(s):  
T Cell Activation ◽  
Cell Activation ◽  
Immunological Synapse ◽  
Rho Gtpase ◽  
Fluorescence Lifetime Imaging ◽  
Β1 Integrin ◽  
Receptor Signal ◽  
Receptor Input ◽  
Domain Perturbations ◽  
Gtpase Activation

ABSTRACT The Rho GTPase Cdc42 regulates cytoskeletal changes at the immunological synapse (IS) that are critical to T-cell activation. By imaging fluorescent activity biosensors (Raichu) using fluorescence lifetime imaging microscopy, Cdc42 activation was shown to display kinetics that are conditional on the specific receptor input (through two IS-associated receptors, CD3 and β1 integrin). CD3-triggered Cdc42 activity is dependent on the cyto-2 (NPIY) motif of the β1 integrin cytoplasmic domain. Perturbations of the ezrin-radixin-moesin (ERM) function blocked CD3- and β1-dependent increases in Cdc42 activity. Both IS-associated receptors probably lie on a serial molecular pathway and transduce signals through the ERM-dependent machinery that is responsible for the remodeling and stabilization of the synapse. Cdc42 activity is impaired in β1 integrin-deficient T cells that form conjugates with antigen-presenting cells but is partially restored in the context of an antigen-specific synapse. This restoration of Cdc42 activity is due, at least in part, to the recruitment and activation of β2 integrin.

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 Actin Cytoskeleton Regulates Calcium Dynamics and NFAT Nuclear Duration

2004 ◽  
Vol 24 (4) ◽  
pp. 1628-1639 ◽  
Author(s):  
Fabiola V. Rivas ◽  
James P. O'Keefe ◽  
Maria-Luisa Alegre ◽  
Thomas F. Gajewski
Keyword(s):  
T Cell ◽  
Actin Cytoskeleton ◽  
T Cell Activation ◽  
Actin Polymerization ◽  
Cell Activation ◽  
Cell Function ◽  
Immunological Synapse ◽  
Interleukin 2 ◽  
Actin Dynamics ◽  
Activated T Cells

ABSTRACT T-cell activation by antigen-presenting cells is accompanied by actin polymerization, T-cell receptor (TCR) capping, and formation of the immunological synapse. However, whether actin-dependent events are required for T-cell function is poorly understood. Herein, we provide evidence for an unexpected negative regulatory role of the actin cytoskeleton on TCR-induced cytokine production. Disruption of actin polymerization resulted in prolonged intracellular calcium elevation in response to anti-CD3, thapsigargin, or phorbol myristate acetate plus ionomycin, leading to persistent NFAT (nuclear factor of activated T cells) nuclear duration. These events were dominant, as the net effect of actin blockade was augmented interleukin 2 promoter activity. Increased surface expression of the plasma membrane Ca2+ ATPase was observed upon stimulation, which was inhibited by cytochalasin D, suggesting that actin polymerization contributes to calcium export. Our results imply a novel role for the actin cytoskeleton in modulating the duration of Ca2+-NFAT signaling and indicate that actin dynamics regulate features of T-cell activation downstream of receptor clustering.

Rho GTPases link cytoskeletal rearrangements and activation processes induced via the tetraspanin CD82 in T lymphocytes

2002 ◽  
Vol 115 (2) ◽  
pp. 433-443
Author(s):  
Alix Delaguillaumie ◽  
Cécile Lagaudrière-Gesbert ◽  
Michel R. Popoff ◽  
Hélène Conjeaud
Keyword(s):  
T Lymphocytes ◽  
Tyrosine Kinases ◽  
Rho Gtpases ◽  
Cell Activation ◽  
Immunological Synapse ◽  
Rho Gtpase ◽  
Morphological Changes ◽  
Cell Receptor ◽  
Tcr Signaling ◽  
Cytoskeletal Rearrangements

Activation of T lymphocytes requires the engagement of the T-cell receptor and costimulation molecules through cell-to-cell contacts. The tetraspanin CD82 has previously been shown to act as a cytoskeleton-dependent costimulation molecule. We show here that CD82 engagement leads to the tyrosine phosphorylation and association of both the Rho GTPases guanosine exchange factor Vav1 and adapter protein SLP76, suggesting that Rho GTPases participate in CD82 signaling. Indeed, broad inactivation of all Rho GTPases, or a specific blockade of RhoA, Rac1 or Cdc42, inhibited the morphological changes linked to CD82 engagement but failed to modulate the inducible association of CD82 with the actin network. Rho GTPase inactivation, as well as actin depolymerization, reduced the ability of CD82 to phosphorylate Vav and SLP76 and to potentiate the phosphorylation of two early TcR signaling intermediates: the tyrosine kinases ZAP70 and membrane adapter LAT. Taken together, this suggests that an amplification loop, via early Vav and SLP76 phosphorylations and Rho-GTPases activation, is initiated by CD82 association with the cytoskeleton, which permits cytoskeletal rearrangements and costimulatory activity. Moreover, the involvement of CD82 in the formation of the immunological synapse is strongly suggested by its accumulation at the site of TcR engagement. This novel link between a tetraspanin and the Rho GTPase cascade could explain why tetraspanins, which are known to form heterocomplexes, are involved in cell activation, adhesion, growth and metastasis.

scholarly journals The space and time frames of T cell activation at the immunological synapse

FEBS Letters ◽  
2010 ◽  
Vol 584 (24) ◽  
pp. 4851-4857 ◽  
Author(s):  
Salvatore Valitutti ◽  
Daniel Coombs ◽  
Loïc Dupré
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Immunological Synapse ◽  
Space And Time ◽  
Time Frames

scholarly journals Periodic Membrane Potential and Ca2+ Oscillations in T Cells Forming an Immune Synapse

2020 ◽  
Vol 21 (5) ◽  
pp. 1568 ◽  
Author(s):  
Ferenc Papp ◽  
Peter Hajdu ◽  
Gabor Tajti ◽  
Agnes Toth ◽  
Eva Nagy ◽  
...  
Keyword(s):  
T Cells ◽  
Membrane Potential ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Calcium Release ◽  
Immunological Synapse ◽  
Level Control ◽  
Potential Oscillations ◽  
Immune Synapse

The immunological synapse (IS) is a specialized contact area formed between a T cell and an antigen presenting cell (APC). Besides molecules directly involved in antigen recognition such as the TCR/CD3 complex, ion channels important in the membrane potential and intracellular free Ca2+ concentration control of T cells are also recruited into the IS. These are the voltage-gated Kv1.3 and Ca2+-activated KCa3.1 K+ channels and the calcium release-activated Ca2+ channel (CRAC). However, the consequence of this recruitment on membrane potential and Ca2+ level control is not known. Here we demonstrate that the membrane potential (MP) of murine T cells conjugated with APCs in an IS shows characteristic oscillations. We found that depolarization of the membrane by current injection or by increased extracellular K+ concentration produced membrane potential oscillations (MPO) significantly more frequently in conjugated T cells than in lone T cells. Furthermore, oscillation of the free intracellular Ca2+ concentration could also be observed more frequently in cells forming an IS than in lone cells. We suggest that in the IS the special arrangement of channels and the constrained space between the interacting cells creates a favorable environment for these oscillations, which may enhance the signaling process leading to T cell activation.

Sign in / Sign up

Export Citation Format

Share Document