scholarly journals LIME

2003 ◽  
Vol 198 (10) ◽  
pp. 1453-1462 ◽  
Author(s):  
Naděžda Brdičková ◽  
Tomáš Brdička ◽  
Pavla Angelisová ◽  
Ondrej Horváth ◽  
Jiří Špička ◽  
...  
Keyword(s):  
T Cells ◽  
Lipid Rafts ◽  
T Cell Activation ◽  
Cell Activation ◽  
Ectopic Expression ◽  
Adaptor Protein ◽  
Negative Regulator ◽  
Membrane Rafts ◽  
Cross Linking ◽  
Jurkat T Cells

Lymphocyte membrane rafts contain molecules critical for immunoreceptor signaling. Here, we report identification of a new raft-associated adaptor protein LIME (Lck-interacting molecule) expressed predominantly in T lymphocytes. LIME becomes tyrosine phosphorylated after cross-linking of the CD4 or CD8 coreceptors. Phospho-LIME associates with the Src family kinase Lck and its negative regulator, Csk. Ectopic expression of LIME in Jurkat T cells results in an increase of Csk in lipid rafts, increased phosphorylation of Lck and higher Ca2+ response to CD3 stimulation. Thus, LIME appears to be involved in regulation of T cell activation by coreceptors.

scholarly journals Non–T Cell Activation Linker (NTAL)

2002 ◽  
Vol 196 (12) ◽  
pp. 1617-1626 ◽  
Author(s):  
Tomáš Brdička ◽  
Martin Imrich ◽  
Pavla Angelisová ◽  
Naděžda Brdičková ◽  
Ondrej Horváth ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
T Cell Activation ◽  
Cell Activation ◽  
Adaptor Protein ◽  
Cell Receptor ◽  
Cross Linking ◽  
Multicomponent Complex ◽  
Transient Elevation

A key molecule necessary for activation of T lymphocytes through their antigen-specific T cell receptor (TCR) is the transmembrane adaptor protein LAT (linker for activation of T cells). Upon TCR engagement, LAT becomes rapidly tyrosine phosphorylated and then serves as a scaffold organizing a multicomponent complex that is indispensable for induction of further downstream steps of the signaling cascade. Here we describe the identification and preliminary characterization of a novel transmembrane adaptor protein that is structurally and evolutionarily related to LAT and is expressed in B lymphocytes, natural killer (NK) cells, monocytes, and mast cells but not in resting T lymphocytes. This novel transmembrane adaptor protein, termed NTAL (non–T cell activation linker) is the product of a previously identified WBSCR5 gene of so far unknown function. NTAL becomes rapidly tyrosine-phosphorylated upon cross-linking of the B cell receptor (BCR) or of high-affinity Fcγ- and Fcε-receptors of myeloid cells and then associates with the cytoplasmic signaling molecules Grb2, Sos1, Gab1, and c-Cbl. NTAL expressed in the LAT-deficient T cell line J.CaM2.5 becomes tyrosine phosphorylated and rescues activation of Erk1/2 and minimal transient elevation of cytoplasmic calcium level upon TCR/CD3 cross-linking. Thus, NTAL appears to be a structural and possibly also functional homologue of LAT in non–T cells.

scholarly journals The Transmembrane Adaptor Protein Trim Regulates T Cell Receptor (Tcr) Expression and Tcr-Mediated Signaling via an Association with the Tcr ζ Chain

2001 ◽  
Vol 193 (11) ◽  
pp. 1269-1284 ◽  
Author(s):  
Henning Kirchgessner ◽  
Jes Dietrich ◽  
Jeanette Scherer ◽  
Pia Isomäki ◽  
Vladimir Korinek ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Surface ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Cell Activation ◽  
Adaptor Protein ◽  
Cell Receptor ◽  
Jurkat T Cells ◽  
Integral Component

T cell receptor (TCR)-interacting molecule (TRIM) is a recently identified transmembrane adaptor protein, which is exclusively expressed in T cells. Here we demonstrate that in mature T cells, TRIM preferentially interacts with the TCR via the TCR-ζ chains and to a lesser extent via the CD3-ε/γ heterodimer. Transient or stable overexpression of TRIM in Jurkat T cells results in enhancement of TCR expression on the cell surface and elevated induction of Ca2+ mobilization after T cell activation. TRIM-mediated upregulation of TCR expression results from inhibition of spontaneous TCR internalization and stabilization of TCR complexes on the cell surface. Collectively, our data identify TRIM as a novel integral component of the TCR complex and suggest that one function of TRIM might be to modulate the strength of signals transduced through the TCR through regulation of TCR expression on the cell surface.

scholarly journals LIME, a Novel Transmembrane Adaptor Protein, Associates with p56lck and Mediates T Cell Activation

2003 ◽  
Vol 198 (10) ◽  
pp. 1463-1473 ◽  
Author(s):  
Eun Mi Hur ◽  
Myoungsun Son ◽  
Ok-Hee Lee ◽  
Young Bong Choi ◽  
Changwon Park ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Transcriptional Activation ◽  
Cell Activation ◽  
Transmembrane Domain ◽  
Adaptor Protein ◽  
Jurkat T Cells ◽  
Downstream Signaling ◽  
Src Homology

In this study, we identify and characterize a novel transmembrane adaptor protein, designated Lck-interacting membrane protein (LIME), as a binding partner of the Lck Src homology (SH)2 domain. LIME possesses a short extracellular domain, a transmembrane domain, and a cytoplasmic tail containing five tyrosine-based motifs. The protein is primarily expressed in hematopoietic cells and lung. Interestingly, LIME expression is up-regulated by TCR stimulation and sustained up to 24 h, suggesting that LIME acts throughout the early to late stages of T cell activation. LIME is localized to membrane rafts and distributed within the T cell–APC contact site. Upon TCR stimulation of Jurkat T cells, LIME associates with Lck as a tyrosine-phosphorylated protein. Experiments using Jurkat T cells expressing CD8–LIME chimera reveal that the protein associates with phosphatidylinositol 3-kinase, Grb2, Gads, and SHP2, and activates ERK1/2 and JNK but not p38. Moreover, overexpression of LIME in Jurkat T cells induces transcriptional activation of the IL-2 promoter. Our data collectively show that LIME is a raft-associated transmembrane adaptor protein linking TCR stimuli to downstream signaling pathways via associations with Lck.

Abstract 219: Deficiency of the T Cell Regulator Cbl-B Aggravates Atherosclerosis by Inducing CD8 + T Cell-Mediated Macrophage Death

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Tom T Seijkens ◽  
Holger Winkels ◽  
Marion Gijbels ◽  
Jan A Kuivenhoven ◽  
Ljubica Perisic ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Aortic Arch ◽  
T Cell Activation ◽  
Cell Activation ◽  
B Cell Lymphoma ◽  
Negative Regulator ◽  
Atherosclerotic Plaques ◽  
Chow Diet ◽  
Plaque Area

Aims: The E3-ligase CBL-B ( Casitas B-cell Lymphoma-B ) is an important negative regulator of T cell activation that is also expressed in macrophages. T cells and macrophages mediate atherosclerosis, but their regulation in this disease remains largely unknown; thus, we studied the function of CBL-B in atherogenesis. Methods and Results: Here we investigated the effect of CBL-B deficiency in hyperlipidemic Apoe -/- mice in atherosclerosis. At the age of 20 weeks, chow diet-fed Cbl-b -/- Apoe -/- mice showed a significant increase in plaque area in the aortic arch, due to greater macrophage infiltration. Cbl-b -/- Apoe -/- macrophages displayed strong recruitment towards MCP1 and showed an increase in oxidized (ox)LDL uptake. In the aortic root of the same Cbl-b -/- Apoe -/- mice, where more advanced plaques were present than in the aortic arch, plaque area rose by 40%, accompanied by a dramatic change in plaque phenotype. Plaques contained fewer macrophages, had larger necrotic cores, and harboured more CD8 + T cells. The CD8 + T cells of Cbl-b -/- Apoe -/- mice were less susceptible to apoptosis and less resistant to Treg suppression. The increase in CD8 + T cells in the plaque effected greater macrophage apoptosis, resulting in enhanced necrotic core formation. Moreover, CBL-B gene expression was downregulated in human atherosclerotic plaques, and positively correlated with FoxP3 expression, indicating an atheroprotective effect. Conclusion: CBL-B is an important regulator of innate and adaptive immune reactions in atherosclerosis, by mediating macrophage recruitment and activation, CD8 + T cell activation, and CD8 + T cell-induced macrophage death in atherosclerotic plaques.

scholarly journals Modulating p56Lck in T-Cells by a Chimeric Peptide Comprising Two Functionally Different Motifs of Tip fromHerpesvirus saimiri

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Jean-Paul Vernot ◽  
Ana María Perdomo-Arciniegas ◽  
Luis Alberto Pérez-Quintero ◽  
Diego Fernando Martínez
Keyword(s):  
T Cells ◽  
T Cell ◽  
Lipid Rafts ◽  
T Cell Activation ◽  
Cell Activation ◽  
Jurkat Cells ◽  
Chimeric Peptide ◽  
Vector Targeting

The Lck interacting protein Tip ofHerpesvirus saimiriis responsible for T-cell transformation bothin vitroandin vivo. Here we designed the chimeric peptide hTip-CSKH, comprising the Lck specific interacting motif CSKH of Tip and its hydrophobic transmembrane sequence (hTip), the latter as a vector targeting lipid rafts. We found that hTip-CSKH can induce a fivefold increase in proliferation of human andAotussp. T-cells. Costimulation with PMA did not enhance this proliferation rate, suggesting that hTip-CSKH is sufficient and independent of further PKC stimulation. We also found that human Lck phosphorylation was increased earlier after stimulation when T-cells were incubated previously with hTip-CSKH, supporting a strong signalling and proliferative effect of the chimeric peptide. Additionally, Lck downstream signalling was evident with hTip-CSKH but not with control peptides. Importantly, hTip-CSKH could be identified in heavy lipid rafts membrane fractions, a compartment where important T-cell signalling molecules (LAT, Ras, and Lck) are present during T-cell activation. Interestingly, hTip-CSKH was inhibitory to Jurkat cells, in total agreement with the different signalling pathways and activation requirements of this leukemic cell line. These results provide the basis for the development of new compounds capable of modulating therapeutic targets present in lipid rafts.

scholarly journals Induction of Cytotoxic T Lymphocyte Antigen 4 (Ctla-4) Restricts Clonal Expansion of Helper T Cells

2001 ◽  
Vol 194 (7) ◽  
pp. 893-902 ◽  
Author(s):  
Alden M. Doyle ◽  
Alan C. Mullen ◽  
Alejandro V. Villarino ◽  
Anne S. Hutchins ◽  
Frances A. High ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell Activation ◽  
T Lymphocyte ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Cytotoxic T Lymphocyte ◽  
Clonal Expansion ◽  
Negative Regulator ◽  
Lymphocyte Antigen ◽  
Cell Divisions

Cytotoxic T lymphocyte antigen (CTLA)-4 plays an essential role in immunologic homeostasis. How this negative regulator of T cell activation executes its functions has remained controversial. We now provide evidence that CTLA-4 mediates a cell-intrinsic counterbalance to restrict the clonal expansion of proliferating CD4+ T cells. The regulation of CTLA-4 expression and function ensures that, after ∼3 cell divisions of expansion, most progeny will succumb to either proliferative arrest or death over the ensuing three cell divisions. The quantitative precision of the counterbalance hinges on the graded, time-independent induction of CTLA-4 expression during the first three cell divisions. In contrast to the limits imposed on unpolarized cells, T helper type 1 (Th1) and Th2 effector progeny may be rescued from proliferative arrest by interleukin (IL)-12 and IL-4 signaling, respectively, allowing appropriately stimulated progeny to proceed to the stage of tissue homing. These results suggest that the cell-autonomous regulation of CTLA-4 induction may be a central checkpoint of clonal expansion of CD4+ T cells, allowing temporally and spatially restricted growth of progeny to be dictated by the nature of the threat posed to the host.

scholarly journals Tyrosine 192 within the SH2 domain of the Src-protein tyrosine kinase p56Lck regulates T-cell activation independently of Lck/CD45 interactions

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Matthias Kästle ◽  
Camilla Merten ◽  
Roland Hartig ◽  
Thilo Kaehne ◽  
Ardiyanto Liaunardy-Jopeace ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tyrosine Kinase ◽  
Enzymatic Activity ◽  
T Cell Activation ◽  
Protein Tyrosine Kinase ◽  
Cell Activation ◽  
Sh2 Domain ◽  
Jurkat T Cells

Abstract Background Upon engagement of the T-cell receptor (TCR), the Src-family protein tyrosine kinase p56Lck phosphorylates components of the TCR (e.g. the TCRζ chains), thereby initiating T-cell activation. The enzymatic activity of Lck is primarily regulated via reversible and dynamic phosphorylation of two tyrosine residues, Y394 and Y505. Lck possesses an additional highly conserved tyrosine Y192, located within the SH2 domain, whose role in T-cell activation is not fully understood. Methods Knock-in mice expressing a phospho-mimetic (Y192E) form of Lck were generated. Cellular and biochemical characterization was performed to elucidate the function of Y192 in primary T cells. HEK 293T and Jurkat T cells were used for in vitro studies. Results Co-immunoprecipitation studies and biochemical analyses using T cells from LckY192E knock-in mice revealed a diminished binding of LckY192E to CD45 and a concomitant hyperphosphorylation of Y505, thus corroborating previous data obtained in Jurkat T cells. Surprisingly however, in vitro kinase assays showed that LckY192E possesses a normal enzymatic activity in human and murine T cells. FLIM/FRET measurements employing an LckY192E biosensor further indicated that the steady state conformation of the LckY192E mutant is similar to Lckwt. These data suggest that Y192 might regulate Lck functions also independently from the Lck/CD45-association. Indeed, when LckY192E was expressed in CD45−/−/Csk−/− non-T cells (HEK 293T cells), phosphorylation of Y505 was similar to Lckwt, but LckY192E still failed to optimally phosphorylate and activate the Lck downstream substrate ZAP70. Furthermore, LckY19E was recruited less to CD3 after TCR stimulation. Conclusions Taken together, phosphorylation of Y192 regulates Lck functions in T cells at least twofold, by preventing Lck association to CD45 and by modulating ligand-induced recruitment of Lck to the TCR. Major findings Our data change the current view on the function of Y192 and suggest that Y192 also regulates Lck activity in a manner independent of Y505 phosphorylation.

18β-Glycyrrhetinic acid potently inhibits Kv1.3 potassium channels and T cell activation in human Jurkat T cells

2013 ◽  
Vol 148 (2) ◽  
pp. 647-654 ◽  
Author(s):  
Xiao-Xing Fu ◽  
Li-Li Du ◽  
Ning Zhao ◽  
Qian Dong ◽  
Yu-Hua Liao ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Potassium Channels ◽  
T Cell Activation ◽  
Cell Activation ◽  
Glycyrrhetinic Acid ◽  
Jurkat T Cells

scholarly journals The RING ubiquitin E3 RNF114 interacts with A20 and modulates NF-κB activity and T-cell activation

2014 ◽  
Vol 5 (8) ◽  
pp. e1399-e1399 ◽  
Author(s):  
M S Rodriguez ◽  
I Egaña ◽  
F Lopitz-Otsoa ◽  
F Aillet ◽  
M P Lopez-Mato ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Zinc Finger Protein ◽  
Inflammatory Diseases ◽  
Negative Regulator ◽  
Cell Mediated Immune Response ◽  
Cycle Regulation ◽  
Hybrid Screening

Abstract Accurate regulation of nuclear factor-κB (NF-κB) activity is crucial to prevent a variety of disorders including immune and inflammatory diseases. Active NF-κB promotes IκBα and A20 expression, important negative regulatory molecules that control the NF-κB response. In this study, using two-hybrid screening we identify the RING-type zinc-finger protein 114 (RNF114) as an A20-interacting factor. RNF114 interacts with A20 in T cells and modulates A20 ubiquitylation. RNF114 acts as negative regulator of NF-κB-dependent transcription, not only by stabilizing the A20 protein but also IκBα. Importantly, we demonstrate that in T cells, the effect of RNF114 is linked to the modulation of T-cell activation and apoptosis but is independent of cell cycle regulation. Altogether, our data indicate that RNF114 is a new partner of A2O involved in the regulation of NF-κB activity that contributes to the control of signaling pathways modulating T cell-mediated immune response.

scholarly journals RIAM Interacts with the Hematopoietic-Specific Adaptor Protein Gads and Forms a LAT-Independent Node of Signal Integration That Regulates Activation of PLC-γ1

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4138-4138
Author(s):  
Kankana Bardhan ◽  
Nikolaos Patsoukis ◽  
Donna M Berry ◽  
Jane McGlade ◽  
Vassiliki A. Boussiotis
Keyword(s):  
T Cells ◽  
Plasma Membrane ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Adaptor Protein ◽  
Ph Domain ◽  
Activated T Cells ◽  
Independent Manner ◽  
C Terminus

Abstract TCR stimulation triggers the activation of protein tyrosine kinases resulting in phosphorylation of the adaptor protein LAT. SLP-76, interacts constitutively with PLC-γ1 and with the SH3 domain of Gads, which via its SH2 domain mediates inducible recruitment of SLP-76 and PLC-γ1 to LAT, upon T cell activation. PLC-γ1 hydrolyzes phosphatidylinositol-4, 5 bisphosphate [PI(4,5)P2], generating inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), second messengers responsible for mediating intracellular calcium release and activation of downstream signals. The adaptor protein RIAM constitutively interacts with PLC-γ1 and is required for PLC-γ1 activation. RIAM is a multidomain protein with a small N-terminus proline-rich region, two coiled-coiled regions, sequential Ras association (RA) and pleckstrin homology (PH) domains, and a large C-terminus proline-rich region, which interacts with PLC-γ1. The RA domain of RIAM has specificity for Rap1-GTP whereas the PH domain binds to the PLC-γ1 substrate PI(4,5)P2. The RA-PH domain region of RIAM functions as a single structural unit and mediates translocation of RIAM to the plasma membrane upon T cell activation. Previously, we determined that RIAM deficiency results in impaired activation of PLC-γ1 in spite of the formation of the PLC-γ1-SLP-76-LAT complex, suggesting perhaps somewhat paradoxically, that PLC-γ1-SLP-76-LAT signalosome is not sufficient to mediate distal signaling in the absence of RIAM. This observation indicated that RIAM mediates its effects at a level distal to SLP-76-LAT or through a signaling pathway parallel but distinct from SLP-76-Gads-LAT. Here we investigated whether RIAM forms a signalosome parallel to PLC-γ1-SLP-76-Gads and whether such pathway might be involved in the activation of PLC-γ1. Using primary T lymphocytes and Jurkat T cells stimulated via TCR/CD3 and CD28 we determined that RIAM constitutively interacted with Gads as determined by immunoprecipitation with RIAM-specific antibody followed by Gads immunoblot. To determine whether the interaction between RIAM and Gads was direct, we employed an in vitro protein association assay. Glutathione S-transferase (GST) and GST-fusion protein of Gads were coupled to glutathione-sepharose and incubated with [35S]methionine-labeled RIAM or luciferase, as negative control. Gads bound to [35S]methionine-labeled RIAM indicating that RIAM interacts directly with Gads. We further examined domain-specific interaction of RIAM with endogenous Gads using GST fusion proteins of RIAM. We determined a constitutive interaction between Gads and GST fusion proteins of full-length RIAM or C-terminus region of RIAM. Although a number of tyrosine phosphorylated proteins were associated with the RIAM-Gads complex upon T cell activation, LAT was not detected among the components of this complex as determined by immunoblot with anti-phosphotyrosine-specific or LAT-specific antibodies. Using a GST fusion protein of the RA-PH domain of RIAM we determined that, surprisingly, Gads displayed activation-dependent interaction with the RA-PH domain, which mediates the recruitment of RIAM to the plasma membrane upon T cell activation. Furthermore, in addition to Gads, SLP-76 and PLC-γ1 were recruited to the RA-PH domain of RIAM in activated T cells. To determine whether RIAM and Gads had a synergistic effect on IL-2 transcription, we performed luciferase-based reporter assays using a reporter construct driven by the entire IL-2 promoter or by NFAT binding sequences. We found that RIAM and Gads had a synergistic effect on IL-2 and on NFAT-mediated transcriptional activation, which depends on PLC-γ1. Thus, via its C-terminus region, RIAM directly and constitutively interacts with Gads. In addition, via its RA-PH domain, RIAM mediates an activation-dependent interaction with Gads and serves as a docking site recruiting the PLC-γ1-SLP-76-Gads complex to the plasma membrane in a LAT-independent manner. These findings indicate a crosstalk between RIAM and SLP-76 in the activation of PLC-γ1 and reveal a previously unidentified, alternative signaling pathway leading to Gads-SLP-76 recruitment to the plasma membrane of activated T cells in a LAT-independent manner. Disclosures No relevant conflicts of interest to declare.

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