scholarly journals RIAM Links the ADAP/SKAP-55 Signaling Module to Rap1, Facilitating T-Cell-Receptor-Mediated Integrin Activation

2007 ◽  
Vol 27 (11) ◽  
pp. 4070-4081 ◽  
Author(s):  
Gaël Ménasché ◽  
Stefanie Kliche ◽  
Emily J. H. Chen ◽  
Theresia E. B. Stradal ◽  
Burkhart Schraven ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Small Gtpase ◽  
Adapter Proteins ◽  
Adapter Protein ◽  
Integrin Activation ◽  
Tcr Signaling ◽  
Antigen Presenting

ABSTRACT One outcome of T-cell receptor (TCR) signaling is increased affinity and avidity of integrins for their ligands. This occurs through a process known as inside-out signaling, which has been shown to require several molecular components including the adapter proteins ADAP (adhesion and degranulation-promoting adapter protein) and SKAP-55 (55-kDa src kinase-associated phosphoprotein) and the small GTPase Rap1. Herein, we provide evidence linking ADAP and SKAP-55 to RIAM, a recently described adapter protein that binds selectively to active Rap1. We identified RIAM as a key component linking the ADAP/SKAP-55 module to the small GTPase Rap1, facilitating TCR-mediated integrin activation. We show that RIAM constitutively interacts with SKAP-55 in both a heterologous transfection system and primary T cells and map the region essential for this interaction. Additionally, we find that the SKAP-55/RIAM complex is essential both for TCR-mediated adhesion and for efficient conjugate formation between T cells and antigen-presenting cells. Mechanistic studies revealed that the ADAP/SKAP-55 module relocalized RIAM and Rap1 to the plasma membrane following TCR activation to facilitate integrin activation. These results describe for the first time a link between ADAP/SKAP-55 and the Rap1/RIAM complex and provide a potential new mechanism for TCR-mediated integrin activation.

scholarly journals Fyn-Binding Protein (Fyb)/Slp-76–Associated Protein (Slap), Ena/Vasodilator-Stimulated Phosphoprotein (Vasp) Proteins and the Arp2/3 Complex Link T Cell Receptor (Tcr) Signaling to the Actin Cytoskeleton

2000 ◽  
Vol 149 (1) ◽  
pp. 181-194 ◽  
Author(s):  
Matthias Krause ◽  
Antonio S. Sechi ◽  
Marlies Konradt ◽  
David Monner ◽  
Frank B. Gertler ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Actin Cytoskeleton ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
T Cell Signaling ◽  
Tcr Signaling ◽  
Activated T Cells ◽  
Antigen Presenting ◽  
Syndrome Protein

T cell receptor (TCR)-driven activation of helper T cells induces a rapid polarization of their cytoskeleton towards bound antigen presenting cells (APCs). We have identified the Fyn- and SLP-76–associated protein Fyb/SLAP as a new ligand for Ena/ vasodilator-stimulated phosphoprotein (VASP) homology 1 (EVH1) domains. Upon TCR engagement, Fyb/SLAP localizes at the interface between T cells and anti-CD3–coated beads, where Evl, a member of the Ena/VASP family, Wiskott-Aldrich syndrome protein (WASP) and the Arp2/3 complex are also found. In addition, Fyb/SLAP is restricted to lamellipodia of spreading platelets. In activated T cells, Fyb/SLAP associates with Ena/VASP family proteins and is present within biochemical complexes containing WASP, Nck, and SLP-76. Inhibition of binding between Fyb/SLAP and Ena/VASP proteins or WASP and the Arp2/3 complex impairs TCR-dependent actin rearrangement, suggesting that these interactions play a key role in linking T cell signaling to remodeling of the actin cytoskeleton.

scholarly journals The ADAP/SKAP55 Signaling Module Regulates T-Cell Receptor-Mediated Integrin Activation through Plasma Membrane Targeting of Rap1

2006 ◽  
Vol 26 (19) ◽  
pp. 7130-7144 ◽  
Author(s):  
Stefanie Kliche ◽  
Dennis Breitling ◽  
Mauro Togni ◽  
Rico Pusch ◽  
Katja Heuer ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Small Gtpase ◽  
Membrane Targeting ◽  
Adapter Proteins ◽  
Integrin Activation ◽  
Raft Fraction ◽  
Inside Out

ABSTRACT Adhesion of T cells after stimulation of the T-cell receptor (TCR) is mediated via signaling processes that have collectively been termed inside-out signaling. The molecular basis for inside-out signaling is not yet completely understood. Here, we show that a signaling module comprising the cytosolic adapter proteins ADAP and SKAP55 is involved in TCR-mediated inside-out signaling and, moreover, that the interaction between ADAP and SKAP55 is mandatory for integrin activation. Disruption of the ADAP/SKAP55 module leads to displacement of the small GTPase Rap1 from the plasma membrane without influencing its GTPase activity. These findings suggest that the ADAP/SKAP55 complex serves to recruit activated Rap1 to the plasma membrane. In line with this hypothesis is the finding that membrane targeting of the ADAP/SKAP55 module induces T-cell adhesion in the absence of TCR-mediated stimuli. However, it appears as if the ADAP/SKAP55 module can exert its signaling function outside of the classical raft fraction of the cell membrane.

scholarly journals Loss of tonic T-cell receptor signals alters the generation but not the persistence of CD8+ memory T cells

Blood ◽  
2010 ◽  
Vol 116 (25) ◽  
pp. 5560-5570 ◽  
Author(s):  
Karla R. Wiehagen ◽  
Evann Corbo ◽  
Michelle Schmidt ◽  
Haina Shin ◽  
E. John Wherry ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Lymphocytic Choriomeningitis ◽  
Sh2 Domain ◽  
Normal Numbers ◽  
Tcr Signaling ◽  
Tcr Signals

Abstract The requirements for tonic T-cell receptor (TCR) signaling in CD8+ memory T-cell generation and homeostasis are poorly defined. The SRC homology 2 (SH2)-domain–containing leukocyte protein of 76 kDa (SLP-76) is critical for proximal TCR-generated signaling. We used temporally mediated deletion of SLP-76 to interrupt tonic and activating TCR signals after clearance of the lymphocytic choriomeningitis virus (LCMV). SLP-76–dependent signals are required during the contraction phase of the immune response for the normal generation of CD8 memory precursor cells. Conversely, LCMV-specific memory CD8 T cells generated in the presence of SLP-76 and then acutely deprived of TCR-mediated signals persist in vivo in normal numbers for more than 40 weeks. Tonic TCR signals are not required for the transition of the memory pool toward a central memory phenotype, but the absence of SLP-76 during memory homeostasis substantially alters the kinetics. Our data are consistent with a model in which tonic TCR signals are required at multiple stages of differentiation, but are dispensable for memory CD8 T-cell persistence.

scholarly journals Leukocyte-associated immunoglobulin-like receptor 1 inhibits T-cell signaling by decreasing protein phosphorylation in the T-cell signaling pathway

2020 ◽  
Vol 295 (8) ◽  
pp. 2239-2247 ◽  
Author(s):  
Jeoung-Eun Park ◽  
David D. Brand ◽  
Edward F. Rosloniec ◽  
Ae-Kyung Yi ◽  
John M. Stuart ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tyrosine Kinase ◽  
Cell Signaling ◽  
Signaling Pathway ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
T Cell Signaling ◽  
Tcr Signaling ◽  
Cell Signaling Pathway

Multiple observations implicate T-cell dysregulation as a central event in the pathogenesis of rheumatoid arthritis. Here, we investigated mechanisms for suppressing T-cell activation via the inhibitory receptor leukocyte-associated immunoglobulin-like receptor 1 (LAIR-1). To determine how LAIR-1 affects T-cell receptor (TCR) signaling, we compared 1) T cells from LAIR-1–sufficient and –deficient mice, 2) Jurkat cells expressing either LAIR-1 mutants or C-terminal Src kinase (CSK) mutants, and 3) T cells from mice that contain a CSK transgene susceptible to chemical inhibition. Our results indicated that LAIR-1 engagement by collagen or by complement C1q (C1Q, which contains a collagen-like domain) inhibits TCR signaling by decreasing the phosphorylation of key components in the canonical T-cell signaling pathway, including LCK proto-oncogene SRC family tyrosine kinase (LCK), LYN proto-oncogene SRC family tyrosine kinase (LYN), ζ chain of T-cell receptor–associated protein kinase 70 (ZAP-70), and three mitogen-activated protein kinases (extracellular signal–regulated kinase, c-Jun N-terminal kinase 1/2, and p38). The intracellular region of LAIR-1 contains two immunoreceptor tyrosine-based inhibition motifs that are both phosphorylated by LAIR-1 activation, and immunoprecipitation experiments revealed that Tyr-251 in LAIR-1 binds CSK. Using CRISPR/Cas9-mediated genome editing, we demonstrate that CSK is essential for the LAIR-1–induced inhibition of the human TCR signal transduction. T cells from mice that expressed a PP1 analog–sensitive form of CSK (CskAS) corroborated these findings, and we also found that Tyr-251 is critical for LAIR-1's inhibitory function. We propose that LAIR-1 activation may be a strategy for controlling inflammation and may offer a potential therapeutic approach for managing autoimmune diseases.

scholarly journals Interleukin-7 Enhances Proliferation Responses to T-Cell Receptor Stimulation in Naïve CD4+ T Cells from Human Immunodeficiency Virus-Infected Persons

2007 ◽  
Vol 81 (22) ◽  
pp. 12670-12674 ◽  
Author(s):  
Douglas A. Bazdar ◽  
Scott F. Sieg
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Healthy Controls ◽  
Receptor Stimulation ◽  
Interleukin 7 ◽  
Immunodeficiency Virus ◽  
Antigen Presenting

ABSTRACT Proliferation responses of naïve CD4+ T cells to T-cell receptor and interleukin-7 (IL-7) stimulation were evaluated by using cells from human immunodeficiency virus-positive (HIV+) donors. IL-7 enhanced responses to T-cell receptor stimulation, and the magnitude of this enhancement was similar in cells from healthy controls and from HIV+ subjects. The overall response to T-cell receptor stimulation alone or in combination with IL-7, however, was diminished among viremic HIV+ donors and occurred independent of antigen-presenting cells. Frequencies of CD127+ cells were related to the magnitudes of proliferation enhancement that were mediated by IL-7. Thus, IL-7 enhances but does not fully restore the function of naïve CD4+ T cells from HIV-infected persons.

scholarly journals Crucial Role for Nuclear Factor of Activated T Cells in T Cell Receptor-mediated Regulation of Human Interleukin-17

2004 ◽  
Vol 279 (50) ◽  
pp. 52762-52771 ◽  
Author(s):  
Xikui K. Liu ◽  
Xin Lin ◽  
Sarah L. Gaffen
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Promoter Activity ◽  
Cell Receptor ◽  
Cross Linking ◽  
Supporting Evidence ◽  
Nuclear Factor ◽  
Tcr Signaling ◽  
Activated T Cells

The biological activities of the inflammatory cytokine interleukin (IL)-17 have been widely studied. However, comparatively little is known about how IL-17 expression is controlled. Here, we examined the basis for transcriptional regulation of the human IL-17 gene. IL-17 secretion was induced in peripheral blood mononuclear cells following anti-CD3 cross-linking to activate the T cell receptor (TCR), and costimulatory signaling through CD28 strongly enhanced CD3-induced IL-17 production. To definecis-acting elements important for IL-17 gene regulation, we cloned 1.25 kb of genomic sequence upstream of the transcriptional start site. This putative promoter was active in Jurkat T cells following CD3 and CD28 cross-linking, and its activity was inhibited by cyclosporin A and MAPK inhibitors. The promoter was also active in Hut102 T cells, which we have shown to secrete IL-17 constitutively. Overexpression of nuclear factor of activated T cells (NFAT) or Ras enhanced IL-17 promoter activity, and studies in Jurkat lines deficient in specific TCR signaling pathways provided supporting evidence for a role for NFAT. To delineate the IL-17 minimal promoter, we created a series of 5′ truncations and identified a region between -232 and -159 that was sufficient for inducible promoter activity. Interestingly, two NFAT sites were located within this region, which bound to NFATc1 and NFATc2 in nuclear extracts from Hut102 and Jurkat cells. Moreover, mutations of these sites dramatically reduced both specific DNA binding and reporter gene activity, and chromatin immunoprecipitation assays showed occupancy of NFAT at this regionin vivo. Together, these data show that NFAT is the crucial sensor of TCR signaling in the IL-17 promoter.

scholarly journals Suboptimal T-cell receptor signaling compromises protein translation, ribosome biogenesis, and proliferation of mouse CD8 T cells

2017 ◽  
Vol 114 (30) ◽  
pp. E6117-E6126 ◽  
Author(s):  
Thomas C. J. Tan ◽  
John Knight ◽  
Thomas Sbarrato ◽  
Kate Dudek ◽  
Anne E. Willis ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Ribosome Biogenesis ◽  
Cell Activation ◽  
Mrna Translation ◽  
Protein Translation ◽  
Cell Receptor ◽  
Tcr Signaling

Global transcriptomic and proteomic analyses of T cells have been rich sources of unbiased data for understanding T-cell activation. Lack of full concordance of these datasets has illustrated that important facets of T-cell activation are controlled at the level of translation. We undertook translatome analysis of CD8 T-cell activation, combining polysome profiling and microarray analysis. We revealed that altering T-cell receptor stimulation influenced recruitment of mRNAs to heavy polysomes and translation of subsets of genes. A major pathway that was compromised, when TCR signaling was suboptimal, was linked to ribosome biogenesis, a rate-limiting factor in both cell growth and proliferation. Defective TCR signaling affected transcription and processing of ribosomal RNA precursors, as well as the translation of specific ribosomal proteins and translation factors. Mechanistically, IL-2 production was compromised in weakly stimulated T cells, affecting the abundance of Myc protein, a known regulator of ribosome biogenesis. Consequently, weakly activated T cells showed impaired production of ribosomes and a failure to maintain proliferative capacity after stimulation. We demonstrate that primary T cells respond to various environmental cues by regulating ribosome biogenesis and mRNA translation at multiple levels to sustain proliferation and differentiation.

scholarly journals T Cell Receptor–initiated Calcium Release Is Uncoupled from Capacitative Calcium Entry in Itk-deficient T Cells

1998 ◽  
Vol 187 (10) ◽  
pp. 1721-1727 ◽  
Author(s):  
Karen-Qianye Liu ◽  
Stephen C. Bunnell ◽  
Christine B. Gurniak ◽  
Leslie J. Berg
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Calcium Release ◽  
Interleukin 2 ◽  
Cell Receptor ◽  
Calcium Entry ◽  
Tcr Signaling ◽  
Store Depletion ◽  
High Concentrations

Itk, a Tec family tyrosine kinase, plays an important but as yet undefined role in T cell receptor (TCR) signaling. Here we show that T cells from Itk-deficient mice have a TCR-proximal signaling defect, resulting in defective interleukin 2 secretion. Upon TCR stimulation, Itk−/− T cells release normal amounts of calcium from intracellular stores, but fail to open plasma membrane calcium channels. Since thapsigargin-induced store depletion triggers normal calcium entry in Itk−/− T cells, an impaired biochemical link between store depletion and channel opening is unlikely to be responsible for this defect. Biochemical studies indicate that TCR-induced inositol 1,4,5 tris-phosphate (IP3) generation and phospholipase C γ1 tyrosine phosphorylation are substantially reduced in Itk−/− T cells. In contrast, TCR-ζ and ZAP-70 are phosphorylated normally, suggesting that Itk functions downstream of, or in parallel to, ZAP-70 to facilitate TCR-induced IP3 production. These findings support a model in which quantitative differences in cytosolic IP3 trigger distinct responses, and in which only high concentrations of IP3 trigger the influx of extracellular calcium.

scholarly journals Early T cell receptor signals globally modulate ligand:receptor affinities during antigen discrimination

2017 ◽  
Vol 114 (46) ◽  
pp. 12190-12195 ◽  
Author(s):  
Rafal M. Pielak ◽  
Geoff P. O’Donoghue ◽  
Jenny J. Lin ◽  
Katherine N. Alfieri ◽  
Nicole C. Fay ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Single Molecule ◽  
Cell Activation ◽  
Cell Receptor ◽  
Physical Constraints ◽  
Molecular Binding ◽  
Antigen Presenting

Antigen discrimination by T cells occurs at the junction between a T cell and an antigen-presenting cell. Juxtacrine binding between numerous adhesion, signaling, and costimulatory molecules defines both the topographical and lateral geometry of this cell–cell interface, within which T cell receptor (TCR) and peptide major histocompatibility complex (pMHC) interact. These physical constraints on receptor and ligand movement have significant potential to modulate their molecular binding properties. Here, we monitor individual ligand:receptor binding and unbinding events in space and time by single-molecule imaging in live primary T cells for a range of different pMHC ligands and surface densities. Direct observations of pMHC:TCR and CD80:CD28 binding events reveal that the in situ affinity of both pMHC and CD80 ligands for their respective receptors is modulated by the steady-state number of agonist pMHC:TCR interactions experienced by the cell. By resolving every single pMHC:TCR interaction it is evident that this cooperativity is accomplished by increasing the kinetic on-rate without altering the off-rate and has a component that is not spatially localized. Furthermore, positive cooperativity is observed under conditions where the T cell activation probability is low. This TCR-mediated feedback is a global effect on the intercellular junction. It is triggered by the first few individual pMHC:TCR binding events and effectively increases the efficiency of TCR scanning for antigen before the T cell is committed to activation.

scholarly journals Cd8− T Cell Transfectants That Express a High Affinity T Cell Receptor Exhibit Enhanced Peptide-Dependent Activation

2001 ◽  
Vol 194 (8) ◽  
pp. 1043-1052 ◽  
Author(s):  
Phillip D. Holler ◽  
Alice R. Lim ◽  
Bryan K. Cho ◽  
Laurie A. Rund ◽  
David M. Kranz
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cytotoxic T Lymphocyte ◽  
Cell Activity ◽  
Cell Receptor ◽  
Wild Type ◽  
High Affinity ◽  
Antigen Presenting

T cells are activated by binding of the T cell receptor (TCR) to a peptide-major histocompatibility complex (MHC) complex (pMHC) expressed on the surface of antigen presenting cells. Various models have predicted that activation is limited to a narrow window of affinities (or dissociation rates) for the TCR–pMHC interaction and that above or below this window, T cells will fail to undergo activation. However, to date there have not been TCRs with sufficiently high affinities in order to test this hypothesis. In this report we examined the activity of a CD8-negative T cell line transfected with a high affinity mutant TCR (KD = 10 nM) derived from cytotoxic T lymphocyte clone 2C by in vitro engineering. The results show that despite a 300-fold higher affinity and a 45-fold longer off-rate compared with the wild-type TCR, T cells that expressed the mutant TCRs were activated by peptide. In fact, activation could be detected at significantly lower peptide concentrations than with T cells that expressed the wild-type TCR. Furthermore, binding and functional analyses of a panel of peptide variants suggested that pMHC stability could account for apparent discrepancies between TCR affinity and T cell activity observed in several prior studies.

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