scholarly journals CD4+ T cells require Ikaros to inhibit their differentiation toward a pathogenic cell fate

2021 ◽  
Vol 118 (17) ◽  
pp. e2023172118
Author(s):  
Chiara Bernardi ◽  
Gaëtan Maurer ◽  
Tao Ye ◽  
Patricia Marchal ◽  
Bernard Jost ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
T Cell ◽  
Cell Fate ◽  
Tissue Injury ◽  
Cell Receptor ◽  
Chromatin Accessibility ◽  
Activated T Cells ◽  
Gm Csf ◽  
Csf Production

The production of proinflammatory cytokines, particularly granulocyte-macrophage colony-stimulating factor (GM-CSF), by pathogenic CD4+ T cells is central for mediating tissue injury in inflammatory and autoimmune diseases. However, the factors regulating the T cell pathogenic gene expression program remain unclear. Here, we investigated how the Ikaros transcription factor regulates the global gene expression and chromatin accessibility changes in murine T cells during Th17 polarization and after activation via the T cell receptor (TCR) and CD28. We found that, in both conditions, Ikaros represses the expression of genes from the pathogenic signature, particularly Csf2, which encodes GM-CSF. We show that, in TCR/CD28-activated T cells, Ikaros binds a critical enhancer downstream of Csf2 and is required to regulate chromatin accessibility at multiple regions across this locus. Genome-wide Ikaros binding is associated with more compact chromatin, notably at multiple sites containing NFκB or STAT5 target motifs, and STAT5 or NFκB inhibition prevents GM-CSF production in Ikaros-deficient cells. Importantly, Ikaros also limits GM-CSF production in TCR/CD28-activated human T cells. Our data therefore highlight a critical conserved transcriptional mechanism that antagonizes GM-CSF expression in T cells.

scholarly journals Hierarchy of signaling thresholds downstream of the T cell receptor and the Tec kinase ITK

2021 ◽  
Vol 118 (35) ◽  
pp. e2025825118
Author(s):  
Michael P. Gallagher ◽  
James M. Conley ◽  
Pranitha Vangala ◽  
Manuel Garber ◽  
Andrea Reboldi ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Signal Strength ◽  
Cell Receptor ◽  
Early Gene ◽  
Sequencing Analysis ◽  
Nuclear Factor ◽  
Activated T Cells

The strength of peptide:MHC interactions with the T cell receptor (TCR) is correlated with the time to first cell division, the relative scale of the effector cell response, and the graded expression of activation-associated proteins like IRF4. To regulate T cell activation programming, the TCR and the TCR proximal interleukin-2–inducible T cell kinase (ITK) simultaneously trigger many biochemically separate signaling cascades. T cells lacking ITK exhibit selective impairments in effector T cell responses after activation, but under the strongest signaling conditions, ITK activity is dispensable. To gain insight into whether TCR signal strength and ITK activity tune observed graded gene expression through the unequal activation of distinct signaling pathways, we examined Erk1/2 phosphorylation or nuclear factor of activated T cells (NFAT) and nuclear factor (NF)-κB translocation in naïve OT-I CD8+ cell nuclei. We observed the consistent digital activation of NFAT1 and Erk1/2, but NF-κB displayed dynamic, graded activation in response to variation in TCR signal strength, tunable by treatment with an ITK inhibitor. Inhibitor-treated cells showed the dampened induction of AP-1 factors Fos and Fosb, NF-κB response gene transcripts, and survival factor Il2 transcripts. ATAC sequencing analysis also revealed that genomic regions most sensitive to ITK inhibition were enriched for NF-κB and AP-1 motifs. Specific inhibition of NF-κB during peptide stimulation tuned the expression of early gene products like c-Fos. Together, these data indicate a key role for ITK in orchestrating the optimal activation of separate TCR downstream pathways, specifically aiding NF-κB activation. More broadly, we revealed a mechanism by which variations in TCR signal strength can produce patterns of graded gene expression in activated T cells.

scholarly journals T Cell Receptor (TCR) Engagement Leads to Activation-induced Splicing of  Tumor Necrosis Factor (TNF) Nuclear Pre-mRNA

1998 ◽  
Vol 188 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Yang Yang ◽  
Ju-Fay Chang ◽  
Jane R. Parnes ◽  
C. Garrison Fathman
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
T Cell ◽  
Tumor Necrosis Factor ◽  
T Cell Receptor ◽  
Tumor Necrosis ◽  
Protein Production ◽  
Cell Receptor ◽  
Activated T Cells ◽  
Necrosis Factor

Inducible gene expression is primarily regulated at the level of transcription. Additional steps of “processing” pre-mRNA, involved in the regulation of induced gene expression, have not been previously reported. Here we report a novel mechanism of “activation-induced splicing” of preexisting tumor necrosis factor (TNF) message (pre-mRNA) in naive T lymphocytes after engagement of the T cell receptor (TCR), which still occurs after inhibition of transcription. Expression of TNF has been previously demonstrated to be regulated at both the transcriptional and translational levels. However, neither the large pool of TNF mRNA observed in activated T cells nor TNF protein production, which peaks very shortly after activation, can be solely attributed to increased transcription. Evidence is presented that activation-induced splicing of TNF pre-mRNA plays a significant role in the rapid production of TNF seen in activated T cells. Activation triggers processing of TNF pre-mRNA that has accumulated in naive T cells (before activation-induced transcription), and the mature TNF mRNA is translocated to the cytoplasm for rapid translation and protein production. This novel form of activation-induced splicing of TNF may allow T cells to mount an immediate response to activation stimuli under physiological conditions.

T cells: a dedicated effector kinase pathways for every trait?

2021 ◽  
Vol 478 (6) ◽  
pp. 1303-1307
Author(s):  
Kriti Bahl ◽  
Jeroen P. Roose
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Receptor ◽  
Spectrometric Analysis ◽  
Activated T Cells ◽  
Biological Responses ◽  
Extracellular Signal ◽  
Differentiation And Proliferation

Signaling pathways play critical roles in regulating the activation of T cells. Recognition of foreign peptide presented by MHC to the T cell receptor (TCR) triggers a signaling cascade of proximal kinases and adapter molecules that lead to the activation of Effector kinase pathways. These effector kinase pathways play pivotal roles in T cell activation, differentiation, and proliferation. RNA sequencing-based methods have provided insights into the gene expression programs that support the above-mentioned cell biological responses. The proteome is often overlooked. A recent study by Damasio et al. [Biochem. J. (2021) 478, 79–98. doi:10.1042/BCJ20200661] focuses on characterizing the effect of extracellular signal-regulated kinase (ERK) on the remodeling of the proteome of activated CD8+ T cells using Mass spectrometric analysis. Surprisingly, the Effector kinase ERK pathway is responsible for only a select proportion of the proteome that restructures during T cell activation. The primary targets of ERK signaling are transcription factors, cytokines, and cytokine receptors. In this commentary, we discuss the recent findings by Damasio et al. [Biochem. J. (2021) 478, 79–98. doi:10.1042/BCJ20200661] in the context of different Effector kinase pathways in activated T cells.

scholarly journals Fas ligand mediates activation-induced cell death in human T lymphocytes.

1995 ◽  
Vol 181 (1) ◽  
pp. 71-77 ◽  
Author(s):  
M R Alderson ◽  
T W Tough ◽  
T Davis-Smith ◽  
S Braddy ◽  
B Falk ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
Fas Ligand ◽  
Significant Proportion ◽  
Cell Receptor ◽  
Target Cells ◽  
Activated T Cells ◽  
Activation Induced Cell Death ◽  
Fas L

A significant proportion of previously activated human T cells undergo apoptosis when triggered through the CD3/T cell receptor complex, a process termed activation-induced cell death (AICD). Ligation of Fas on activated T cells by either Fas antibodies or recombinant human Fas-ligand (Fas-L) also results in cytolysis. We demonstrate that these two pathways of apoptosis are causally related. Stimulation of previously activated T cells resulted in the expression of Fas-L mRNA and lysis of Fas-positive target cells. Fas-L antagonists inhibited AICD of T cell clones and staphylococcus enterotoxin B (SEB)-specific T cell lines. The data indicate AICD in previously stimulated T cells is mediated by Fas/Fas-L interactions.

scholarly journals The ht beta gene encodes a novel CACCC box-binding protein that regulates T-cell receptor gene expression

1993 ◽  
Vol 13 (9) ◽  
pp. 5691-5701
Author(s):  
Y Wang ◽  
J A Kobori ◽  
L Hood
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Binding Protein ◽  
Cell Receptor ◽  
Regulatory Function ◽  
Human T Cell ◽  
Alpha Gene ◽  
Beta Gene

A gene encoding a novel CACCC box-binding protein that binds to the promoter region of the human T-cell receptor (TCR) V beta 8.1 gene and the mouse TCR alpha gene silencer has been cloned. This gene, termed ht beta, contains four zinc fingers of the class Cys2-X12-His2 that may be responsible for DNA binding and a highly negatively charged region that defines a putative transcriptional activation domain. Analysis of the expression of ht beta mRNA revealed similar expression levels and patterns in various cell lines. The bacterially expressed ht beta protein can bind to the CACCC box in both the human TCR V beta 8.1 gene promoter and the mouse TCR alpha gene silencer. The CACCC box is essential for efficient transcription of the V beta 8.1 promoter. Cotransfection with an ht beta expression plasmid and a reporter vector indicated that ht beta can activate human TCR V beta 8.1 gene transcription. ht beta also is able to counteract the silencing effect of the mouse TCR alpha gene silencer. The CACCC box has been found in almost all V beta 8.1 gene subfamily members and in both TCR alpha and beta gene enhancers in humans and mice. These results suggest that the CACCC box-binding protein may have an important regulatory function for TCR gene expression in alpha beta T cells versus gamma delta T cells.

scholarly journals SLFN2 protection of tRNAs from stress-induced cleavage is essential for T cell–mediated immunity

Science ◽  
2021 ◽  
Vol 372 (6543) ◽  
pp. eaba4220 ◽  
Author(s):  
Tao Yue ◽  
Xiaoming Zhan ◽  
Duanwu Zhang ◽  
Ruchi Jain ◽  
Kuan-wen Wang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Interleukin 2 ◽  
Cell Receptor ◽  
Cell Mediated Immunity ◽  
Activated T Cells ◽  
Granule Formation

Reactive oxygen species (ROS) increase in activated T cells because of metabolic activity induced to support T cell proliferation and differentiation. We show that these ROS trigger an oxidative stress response that leads to translation repression. This response is countered by Schlafen 2 (SLFN2), which directly binds transfer RNAs (tRNAs) to protect them from cleavage by the ribonuclease angiogenin. T cell–specific SLFN2 deficiency results in the accumulation of tRNA fragments, which inhibit translation and promote stress-granule formation. Interleukin-2 receptor β (IL-2Rβ) and IL-2Rγ fail to be translationally up-regulated after T cell receptor stimulation, rendering SLFN2-deficient T cells insensitive to interleukin-2’s mitogenic effects. SLFN2 confers resistance against the ROS-mediated translation-inhibitory effects of oxidative stress normally induced by T cell activation, permitting the robust protein synthesis necessary for T cell expansion and immunity.

scholarly journals Modulation of let-7 miRNAs controls the differentiation of effector CD8 T cells

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Alexandria C Wells ◽  
Keith A Daniels ◽  
Constance C Angelou ◽  
Eric Fagerberg ◽  
Amy S Burnside ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Cytotoxic T Lymphocytes ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cell Receptor ◽  
Activated T Cells ◽  
Cell Responses

The differentiation of naive CD8 T cells into effector cytotoxic T lymphocytes upon antigen stimulation is necessary for successful antiviral, and antitumor immune responses. Here, using a mouse model, we describe a dual role for the let-7 microRNAs in the regulation of CD8 T cell responses, where maintenance of the naive phenotype in CD8 T cells requires high levels of let-7 expression, while generation of cytotoxic T lymphocytes depends upon T cell receptor-mediated let-7 downregulation. Decrease of let-7 expression in activated T cells enhances clonal expansion and the acquisition of effector function through derepression of the let-7 targets, including Myc and Eomesodermin. Ultimately, we have identified a novel let-7-mediated mechanism, which acts as a molecular brake controlling the magnitude of CD8 T cell responses.

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.

Activated T cells enhance interferon-α production by plasmacytoid dendritic cells stimulated with RNA-containing immune complexes

2015 ◽  
Vol 75 (9) ◽  
pp. 1728-1734 ◽  
Author(s):  
Dag Leonard ◽  
Maija-Leena Eloranta ◽  
Niklas Hagberg ◽  
Olof Berggren ◽  
Karolina Tandre ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Immune Complexes ◽  
Serum Levels ◽  
Plasmacytoid Dendritic Cells ◽  
Interferon Α ◽  
Type I ◽  
Activated T Cells ◽  
Gm Csf

ObjectivesPatients with systemic lupus erythematosus (SLE) have an ongoing interferon-α (IFN-α) production by plasmacytoid dendritic cells (pDCs). We investigated whether T cells can promote IFN-α production by pDCs.MethodsHuman pDCs were stimulated with immune complexes (ICs) containing U1 small nuclear ribonucleic proteins particles and SLE-IgG (RNA-IC) in the presence of T cells or T cell supernatants. T cells were activated by anti-CD3/CD28 antibodies or in a mixed leucocyte reaction. IFN-α and other cytokines were determined in culture supernatants or patient sera with immunoassays. The effect of interleukin (IL) 3 and granulocyte-macrophage-colony-stimulating factor (GM-CSF) on pDCs was examined by the use of antibodies, and the expression of CD80/CD86 was determined using flow cytometry.ResultsActivated T cells and supernatants from activated T cells increased IFN-α production by >20-fold. The stimulatory effect of T cell supernatants was reduced after depletion of GM-CSF (81%) or by blocking the GM-CSF receptor (55%–81%). Supernatant from activated T cells, furthermore, increased the frequency of CD80 and CD86 expressing pDCs stimulated with RNA-IC from 6% to 35% (p<0.05) and from 10% to 26% (p<0.01), respectively. Activated SLE T cells enhanced IFN-α production to the same extent as T cells from healthy individuals and a subset of patients with SLE had increased serum levels of GM-CSF.ConclusionsActivated T cells enhance IFN-α production by RNA-IC stimulated pDCs via GM-CSF and induce pDC maturation. Given the increased serum levels of GM-CSF in a subset of patients with SLE, these findings suggest that activated T cells may upregulate type I IFN production in SLE.

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