Acid sphingomyelinase mediates human CD4+ T-cell signaling: potential roles in T-cell responses and diseases

PubMed Central

Bai, Aiping; Guo, Yuan

2017-01-01

Acid sphingomyelinase (ASM) is a lipid hydrolase. By generating ceramide, ASM had been reported to have an important role in regulating immune cell functions inclusive of macrophages, NK cells, and CD8+ T cells, whereas the role of ASM bioactivity in regulation of human CD4+ T-cell functions remained uncertain. Recent studies have provided novel findings in this field. Upon stimulation of CD3 and/or CD28, ASM-dependent ceramide signaling mediates intracellular downstream signal cascades of CD3 and CD28, and regulates CD4+ T-cell activation and proliferation. Meanwhile, CD39 and CD161 have direct interactions with ASM, which mediates downstream signals inclusive of STAT3 and mTOR and thus defines human Th17 cells. Intriguingly, ASM mediates Th1 responses, but negatively regulates Treg functions. In this review, we summarized the pivotal roles of ASM in regulation of human CD4+ T-cell activation and responses. ASM/sphingolipid signaling may be a novel target for the therapy of human autoimmune diseases. PMID:28749465

Nuclear calcium is required for human T cell activation

PubMed Central

Samstag, Yvonne

2016-01-01

Calcium signals in stimulated T cells are generally considered single entities that merely trigger immune responses, whereas costimulatory events specify the type of reaction. Here we show that the “T cell calcium signal” is a composite signal harboring two distinct components that antagonistically control genomic programs underlying the immune response. Using human T cells from healthy individuals, we establish nuclear calcium as a key signal in human T cell adaptogenomics that drives T cell activation and is required for signaling to cyclic adenosine monophosphate response element–binding protein and the induction of CD25, CD69, interleukin-2, and γ-interferon. In the absence of nuclear calcium signaling, cytosolic calcium activating nuclear factor of activated T cells translocation directed the genomic response toward enhanced expression of genes that negatively modulate T cell activation and are associated with a hyporesponsive state. Thus, nuclear calcium controls the T cell fate decision between a proliferative immune response and tolerance. Modulators of nuclear calcium–driven transcription may be used to develop a new type of pro-tolerance immunosuppressive therapy. PMID:27810914

Regulation and function of mTOR signalling in T cell fate decision

PubMed Central

Chi, Hongbo

2012-01-01

The evolutionary conserved kinase mTOR couples cell growth and metabolism to environmental inputs in eukaryotes. T cells depend on mTOR signalling to integrate immune signals and metabolic cues for their proper maintenance and activation. Under steady-state conditions, mTOR is actively controlled by multiple inhibitory mechanisms, and this enforces normal T cell homeostasis. Antigen recognition by naïve CD4+ and CD8+ T cells triggers mTOR activation, which in turn programs their differentiation into functionally distinct lineages. This Review focuses on the signalling mechanisms of mTOR in T cell homeostatic and functional fates and therapeutic implications of targeting mTOR in T cells. PMID:22517423

NITRIC OXIDE, MITOCHONDRIAL HYPERPOLARIZATION AND T-CELL ACTIVATION

PubMed Central

Nagy, Gyorgy; Koncz, Agnes; Fernandez, David; Perl, Andras

2007-01-01

T lymphocyte activation is associated with nitric oxide (NO) production that plays an essential role in multiple T cell functions. NO acts as a messenger, activating soluble guanyl cyclase and participating in the transduction signaling pathways involving cyclic GMP. NO modulates mitochondrial events that are involved in apoptosis and regulates mitochondrial membrane potential and mitochondrial biogenesis in many cell types, including lymphocytes. Mitochondrial hyperpolarization (MHP), an early and reversible event during both T lymphocyte activation and apoptosis, is regulated by NO. Here, we discuss recent evidence that NO-induced MHP represents a molecular switch in multiple T cell signaling pathways. Overproduction of NO in systemic lupus erythematosus (SLE) induces mitochondrial biogenesis and alters Ca2+ signaling. Thus, while NO plays a physiological role in lymphocyte cell signaling, its overproduction may disturb normal T cell function, contributing to the pathogenesis of autoimmunity. PMID:17462531

Colorectal cancer cells suppress CD4+ T cells immunity through canonical Wnt signaling.

PubMed

Sun, Xuan; Liu, Suoning; Wang, Daguang; Zhang, Yang; Li, Wei; Guo, Yuchen; Zhang, Hua; Suo, Jian

2017-02-28

Understanding how colorectal cancer escapes from immunosurveillance and immune attack is important for developing novel immunotherapies for colorectal cancer. In this study we evaluated the role of canonical Wnt signaling in the regulation of T cell function in a mouse colorectal cancer model. We found that colorectal cancer cells expressed abundant Wnt ligands, and intratumoral T cells expressed various Frizzled proteins. Meanwhile, both active β-catenin and total β-catenin were elevated in intratumoral T cells. In vitro study indicated that colorectal cancer cells suppressed IFN-γ expression and increased IL-17a expression in activated CD4+ T cells. However, the cytotoxic activity of CD8+ T cells was not altered by colorectal cancer cells. To further evaluate the importance of Wnt signaling for CD4+ T cell-mediated cancer immunity, β-catenin expression was enforced in CD4+ T cells using lentiviral transduction. In an adoptive transfer model, enforced expression of β-catenin in intratumoral CD4+ T cells increased IL-17a expression, enhanced proliferation and inhibited apoptosis of colorectal cancer cells. Taken together, our study disclosed a new mechanism by which colorectal cancer impairs T cell immunity.

Ghrelin augments murine T-cell proliferation by activation of the phosphatidylinositol-3-kinase, extracellular signal-regulated kinase and protein kinase C signaling pathways

PubMed Central

Lee, Jun Ho; Patel, Kalpesh; Tae, Hyun Jin; Lustig, Ana; Kim, Jie Wan; Mattson, Mark P.; Taub, Dennis D.

2014-01-01

Thymic atrophy occurs during normal aging, and is accelerated by exposure to chronic stressors that elevate glucocorticoid levelsand impair the naïve T cell output. The orexigenic hormone ghrelin was recently shown to attenuate age-associated thymic atrophy. Here, we report that ghrelin enhances the proliferation of murine CD4+ primary T cells and a CD4+ T-cell line. Ghrelin induced activation of the ERK1/2 and Akt signaling pathways, via upstream activation of phosphatidylinositol-3-kinase and protein kinase C, to enhance T-cell proliferation. Moreover, ghrelin induced expression of the cell cycle proteins cyclin D1, cyclin E, cyclin-dependent kinase 2 (CDK2) and retinoblastoma phosphorylation. Finally, ghrelin activated the above-mentioned signaling pathways and stimulated thymocyte proliferation in young and older mice in vivo. PMID:25447526

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

PubMed

Tan, Thomas C J; Knight, John; Sbarrato, Thomas; Dudek, Kate; Willis, Anne E; Zamoyska, Rose

2017-07-25

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.

Magnetic Field-Induced T Cell Receptor Clustering by Nanoparticles Enhances T Cell Activation and Stimulates Antitumor Activity

PubMed Central

2015-01-01

Iron–dextran nanoparticles functionalized with T cell activating proteins have been used to study T cell receptor (TCR) signaling. However, nanoparticle triggering of membrane receptors is poorly understood and may be sensitive to physiologically regulated changes in TCR clustering that occur after T cell activation. Nano-aAPC bound 2-fold more TCR on activated T cells, which have clustered TCR, than on naive T cells, resulting in a lower threshold for activation. To enhance T cell activation, a magnetic field was used to drive aggregation of paramagnetic nano-aAPC, resulting in a doubling of TCR cluster size and increased T cell expansion in vitro and after adoptive transfer in vivo. T cells activated by nano-aAPC in a magnetic field inhibited growth of B16 melanoma, showing that this novel approach, using magnetic field-enhanced nano-aAPC stimulation, can generate large numbers of activated antigen-specific T cells and has clinically relevant applications for adoptive immunotherapy. PMID:24564881

The basis of distinctive IL-2- and IL-15-dependent signaling: weak CD122-dependent signaling favors CD8+ T central-memory cell survival but not T effector-memory cell development.

PubMed

Castro, Iris; Yu, Aixin; Dee, Michael J; Malek, Thomas R

2011-11-15

Recent work suggests that IL-2 and IL-15 induce distinctive levels of signaling through common receptor subunits and that such varied signaling directs the fate of Ag-activated CD8(+) T cells. In this study, we directly examined proximal signaling by IL-2 and IL-15 and CD8(+) T cell primary and memory responses as a consequence of varied CD122-dependent signaling. Initially, IL-2 and IL-15 induced similar p-STAT5 and p-S6 activation, but these activities were only sustained by IL-2. Transient IL-15-dependent signaling is due to limited expression of IL-15Rα. To investigate the outcome of varied CD122 signaling for CD8(+) T cell responses in vivo, OT-I T cells were used from mouse models where CD122 signals were attenuated by mutations within the cytoplasmic tail of CD122 or intrinsic survival function was provided in the absence of CD122 expression by transgenic Bcl-2. In the absence of CD122 signaling, generally normal primary response occurred, but the primed CD8(+) T cells were not maintained. In marked contrast, weak CD122 signaling supported development and survival of T central-memory (T(CM)) but not T effector-memory (T(EM)) cells. Transgenic expression of Bcl-2 in CD122(-/-) CD8(+) T cells also supported the survival and persistence of T(CM) cells but did not rescue T(EM) development. These data indicate that weak CD122 signals readily support T(CM) development largely through providing survival signals. However, stronger signals, independent of Bcl-2, are required for T(EM) development. Our findings are consistent with a model whereby low, intermediate, and high CD122 signaling support T(CM) memory survival, T(EM) programming, and terminal T effector cell differentiation, respectively.

Lack of T-cell receptor-induced signaling is crucial for CD95 ligand up-regulation and protects cutaneous T-cell lymphoma cells from activation-induced cell death.

PubMed

Klemke, Claus-Detlev; Brenner, Dirk; Weiss, Eva-Maria; Schmidt, Marc; Leverkus, Martin; Gülow, Karsten; Krammer, Peter H

2009-05-15

Restimulation of previously activated T cells via the T-cell receptor (TCR) leads to activation-induced cell death (AICD), which is, at least in part, dependent on the death receptor CD95 (APO-1, FAS) and its natural ligand (CD95L). Here, we characterize cutaneous T-cell lymphoma (CTCL) cells (CTCL tumor cell lines and primary CTCL tumor cells from CTCL patients) as AICD resistant. We show that CTCL cells have elevated levels of the CD95-inhibitory protein cFLIP. However, cFLIP is not responsible for CTCL AICD resistance. Instead, our data suggest that reduced TCR-proximal signaling in CTCL cells is responsible for the observed AICD resistance. CTCL cells exhibit no PLC-gamma1 activity, resulting in an impaired Ca(2+)release and reduced generation of reactive oxygen species upon TCR stimulation. Ca(2+) and ROS production are crucial for up-regulation of CD95L and reconstitution of both signals resulted in AICD sensitivity of CTCL cells. In accordance with these data, CTCL tumor cells from patients with Sézary syndrome do not up-regulate CD95L upon TCR-stimulation and are therefore resistant to AICD. These results show a novel mechanism of AICD resistance in CTCL that could have future therapeutic implications to overcome apoptosis resistance in CTCL patients.

Crammed signaling motifs in the T-cell receptor.

PubMed

Borroto, Aldo; Abia, David; Alarcón, Balbino

2014-09-01

Although the T cell antigen receptor (TCR) is long known to contain multiple signaling subunits (CD3γ, CD3δ, CD3ɛ and CD3ζ), their role in signal transduction is still not well understood. The presence of at least one immunoreceptor tyrosine-based activation motif (ITAM) in each CD3 subunit has led to the idea that the multiplication of such elements essentially serves to amplify signals. However, the evolutionary conservation of non-ITAM sequences suggests that each CD3 subunit is likely to have specific non-redundant roles at some stage of development or in mature T cell function. The CD3ɛ subunit is paradigmatic because in a relatively short cytoplasmic sequence (∼55 amino acids) it contains several docking sites for proteins involved in intracellular trafficking and signaling, proteins whose relevance in T cell activation is slowly starting to be revealed. In this review we will summarize our current knowledge on the signaling effectors that bind directly to the TCR and we will propose a hierarchy in their response to TCR triggering. Copyright © 2014 Elsevier B.V. All rights reserved.

CAR T cell therapy for breast cancer: harnessing the tumor milieu to drive T cell activation.

PubMed

Bajgain, Pradip; Tawinwung, Supannikar; D'Elia, Lindsey; Sukumaran, Sujita; Watanabe, Norihiro; Hoyos, Valentina; Lulla, Premal; Brenner, Malcolm K; Leen, Ann M; Vera, Juan F

2018-05-10

The adoptive transfer of T cells redirected to tumor via chimeric antigen receptors (CARs) has produced clinical benefits for the treatment of hematologic diseases. To extend this approach to breast cancer, we generated CAR T cells directed against mucin1 (MUC1), an aberrantly glycosylated neoantigen that is overexpressed by malignant cells and whose expression has been correlated with poor prognosis. Furthermore, to protect our tumor-targeted cells from the elevated levels of immune-inhibitory cytokines present in the tumor milieu, we co-expressed an inverted cytokine receptor linking the IL4 receptor exodomain with the IL7 receptor endodomain (4/7ICR) in order to transform the suppressive IL4 signal into one that would enhance the anti-tumor effects of our CAR T cells at the tumor site. First (1G - CD3ζ) and second generation (2G - 41BB.CD3ζ) MUC1-specific CARs were constructed using the HMFG2 scFv. Following retroviral transduction transgenic expression of the CAR±ICR was assessed by flow cytometry. In vitro CAR/ICR T cell function was measured by assessing cell proliferation and short- and long-term cytotoxic activity using MUC1+ MDA MB 468 cells as targets. In vivo anti-tumor activity was assessed using IL4-producing MDA MB 468 tumor-bearing mice using calipers to assess tumor volume and bioluminescence imaging to track T cells. In the IL4-rich tumor milieu, 1G CAR.MUC1 T cells failed to expand or kill MUC1+ tumors and while co-expression of the 4/7ICR promoted T cell expansion, in the absence of co-stimulatory signals the outgrowing cells exhibited an exhausted phenotype characterized by PD-1 and TIM3 upregulation and failed to control tumor growth. However, by co-expressing 2G CAR.MUC1 (signal 1 - activation + signal 2 - co-stimulation) and 4/7ICR (signal 3 - cytokine), transgenic T cells selectively expanded at the tumor site and produced potent and durable tumor control in vitro and in vivo. Our findings demonstrate the feasibility of targeting breast

CD81 Controls Sustained T Cell Activation Signaling and Defines the Maturation Stages of Cognate Immunological Synapses

PubMed Central

Rocha-Perugini, V.; Zamai, M.; González-Granado, J. M.; Barreiro, O.; Tejera, E.; Yañez-Mó, M.; Caiolfa, V. R.

2013-01-01

In this study, we investigated the dynamics of the molecular interactions of tetraspanin CD81 in T lymphocytes, and we show that CD81 controls the organization of the immune synapse (IS) and T cell activation. Using quantitative microscopy, including fluorescence recovery after photobleaching (FRAP), phasor fluorescence lifetime imaging microscopy-Föster resonance energy transfer (phasorFLIM-FRET), and total internal reflection fluorescence microscopy (TIRFM), we demonstrate that CD81 interacts with ICAM-1 and CD3 during conjugation between T cells and antigen-presenting cells (APCs). CD81 and ICAM-1 exhibit distinct mobilities in central and peripheral areas of early and late T cell-APC contacts. Moreover, CD81–ICAM-1 and CD81-CD3 dynamic interactions increase over the time course of IS formation, as these molecules redistribute throughout the contact area. Therefore, CD81 associations unexpectedly define novel sequential steps of IS maturation. Our results indicate that CD81 controls the temporal progression of the IS and the permanence of CD3 in the membrane contact area, contributing to sustained T cell receptor (TCR)-CD3-mediated signaling. Accordingly, we find that CD81 is required for proper T cell activation, regulating CD3ζ, ZAP-70, LAT, and extracellular signal-regulated kinase (ERK) phosphorylation; CD69 surface expression; and interleukin-2 (IL-2) secretion. Our data demonstrate the important role of CD81 in the molecular organization and dynamics of the IS architecture that sets the signaling threshold in T cell activation. PMID:23858057

Bacterial superantigens bypass Lck-dependent T cell receptor signaling by activating a Galpha11-dependent, PLC-beta-mediated pathway.

PubMed

Bueno, Clara; Lemke, Caitlin D; Criado, Gabriel; Baroja, Miren L; Ferguson, Stephen S G; Rahman, A K M Nur-Ur; Tsoukas, Constantine D; McCormick, John K; Madrenas, Joaquin

2006-07-01

The paradigm to explain antigen-dependent T cell receptor (TCR) signaling is based on the activation of the CD4 or CD8 coreceptor-associated kinase Lck. It is widely assumed that this paradigm is also applicable to signaling by bacterial superantigens. However, these bacterial toxins can activate human T cells lacking Lck, suggesting the existence of an additional pathway of TCR signaling. Here we showed that this alternative pathway operates in the absence of Lck-dependent tyrosine-phosphorylation events and was initiated by the TCR-dependent activation of raft-enriched heterotrimeric Galpha11 proteins. This event, in turn, activated a phospholipase C-beta and protein kinase C-mediated cascade that turned on the mitogen-activated protein kinases ERK-1 and ERK-2, triggered Ca(2+) influx, and translocated the transcription factors NF-AT and NF-kappaB to the nucleus, ultimately inducing the production of interleukin-2 in Lck-deficient T cells. The triggering of this alternative pathway by superantigens suggests that these toxins use a G protein-coupled receptor as a coreceptor on T cells.

Calcium signaling properties of a thyrotroph cell line, mouse TαT1 cells.

PubMed

Tomić, Melanija; Bargi-Souza, Paula; Leiva-Salcedo, Elias; Nunes, Maria Tereza; Stojilkovic, Stanko S

2015-12-01

TαT1 cells are mouse thyrotroph cell line frequently used for studies on thyroid-stimulating hormone beta subunit gene expression and other cellular functions. Here we have characterized calcium-signaling pathways in TαT1 cells, an issue not previously addressed in these cells and incompletely described in native thyrotrophs. TαT1 cells are excitable and fire action potentials spontaneously and in response to application of thyrotropin-releasing hormone (TRH), the native hypothalamic agonist for thyrotrophs. Spontaneous electrical activity is coupled to small amplitude fluctuations in intracellular calcium, whereas TRH stimulates both calcium mobilization from intracellular pools and calcium influx. Non-receptor-mediated depletion of intracellular pool also leads to a prominent facilitation of calcium influx. Both receptor and non-receptor stimulated calcium influx is substantially attenuated but not completely abolished by inhibition of voltage-gated calcium channels, suggesting that depletion of intracellular calcium pool in these cells provides a signal for both voltage-independent and -dependent calcium influx, the latter by facilitating the pacemaking activity. These cells also express purinergic P2Y1 receptors and their activation by extracellular ATP mimics TRH action on calcium mobilization and influx. The thyroid hormone triiodothyronine prolongs duration of TRH-induced calcium spikes during 30-min exposure. These data indicate that TαT1 cells are capable of responding to natively feed-forward TRH signaling and intrapituitary ATP signaling with acute calcium mobilization and sustained calcium influx. Amplification of TRH-induced calcium signaling by triiodothyronine further suggests the existence of a pathway for positive feedback effects of thyroid hormones probably in a non-genomic manner. Published by Elsevier Ltd.

Lipid rafts in T cell signalling and disease

PubMed Central

Jury, Elizabeth C.; Flores-Borja, Fabian; Kabouridis, Panagiotis S.

2007-01-01

Lipid rafts is a blanket term used to describe distinct areas in the plasma membrane rich in certain lipids and proteins and which are thought to perform diverse functions. A large number of studies report on lipid rafts having a key role in receptor signalling and activation of lymphocytes. In T cells, lipid raft involvement was demonstrated in the early steps during T cell receptor (TCR) stimulation. Interestingly, recent evidence has shown that signalling in these domains differs in T cells isolated from patients with autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Here, we discuss these findings and explore the potential of lipid rafts as targets for the development of a new class of agents to downmodulate immune responses and for the treatment of autoimmune diseases. PMID:17890113

Nuclear factor of activated T-cells 5 increases intestinal goblet cell differentiation through an mTOR/Notch signaling pathway

PubMed Central

Zhou, Yuning; Wang, Qingding; Weiss, Heidi L.; Evers, B. Mark

2014-01-01

The intestinal mucosa undergoes a continual process of proliferation, differentiation, and apoptosis that is regulated by multiple signaling pathways. Previously, we have shown that the nuclear factor of activated T-cells 5 (NFAT5) is involved in the regulation of intestinal enterocyte differentiation. Here we show that treatment with sodium chloride (NaCl), which activates NFAT5 signaling, increased mTORC1 repressor regulated in development and DNA damage response 1 (REDD1) protein expression and inhibited mTOR signaling; these alterations were attenuated by knockdown of NFAT5. Knockdown of NFAT5 activated mammalian target of rapamycin (mTOR) signaling and significantly inhibited REDD1 mRNA expression and protein expression. Consistently, overexpression of NFAT5 increased REDD1 expression. In addition, knockdown of REDD1 activated mTOR and Notch signaling, whereas treatment with mTOR inhibitor rapamycin repressed Notch signaling and increased the expression of the goblet cell differentiation marker mucin 2 (MUC2). Moreover, knockdown of NFAT5 activated Notch signaling and decreased MUC2 expression, while overexpression of NFAT5 inhibited Notch signaling and increased MUC2 expression. Our results demonstrate a role for NFAT5 in the regulation of mTOR signaling in intestinal cells. Importantly, these data suggest that NFAT5 participates in the regulation of intestinal homeostasis via the suppression of mTORC1/Notch signaling pathway. PMID:25057011

γδ T Cells Support Pancreatic Oncogenesis by Restraining αβ T Cell Activation.

PubMed

Daley, Donnele; Zambirinis, Constantinos Pantelis; Seifert, Lena; Akkad, Neha; Mohan, Navyatha; Werba, Gregor; Barilla, Rocky; Torres-Hernandez, Alejandro; Hundeyin, Mautin; Mani, Vishnu Raj Kumar; Avanzi, Antonina; Tippens, Daniel; Narayanan, Rajkishen; Jang, Jung-Eun; Newman, Elliot; Pillarisetty, Venu Gopal; Dustin, Michael Loran; Bar-Sagi, Dafna; Hajdu, Cristina; Miller, George

2016-09-08

Inflammation is paramount in pancreatic oncogenesis. We identified a uniquely activated γδT cell population, which constituted ∼40% of tumor-infiltrating T cells in human pancreatic ductal adenocarcinoma (PDA). Recruitment and activation of γδT cells was contingent on diverse chemokine signals. Deletion, depletion, or blockade of γδT cell recruitment was protective against PDA and resulted in increased infiltration, activation, and Th1 polarization of αβT cells. Although αβT cells were dispensable to outcome in PDA, they became indispensable mediators of tumor protection upon γδT cell ablation. PDA-infiltrating γδT cells expressed high levels of exhaustion ligands and thereby negated adaptive anti-tumor immunity. Blockade of PD-L1 in γδT cells enhanced CD4(+) and CD8(+) T cell infiltration and immunogenicity and induced tumor protection suggesting that γδT cells are critical sources of immune-suppressive checkpoint ligands in PDA. We describe γδT cells as central regulators of effector T cell activation in cancer via novel cross-talk. Copyright © 2016 Elsevier Inc. All rights reserved.

T cell receptor for antigen induces linker for activation of T cell–dependent activation of a negative signaling complex involving Dok-2, SHIP-1, and Grb-2

PubMed Central

Dong, Shen; Corre, Béatrice; Foulon, Eliane; Dufour, Evelyne; Veillette, André; Acuto, Oreste; Michel, Frédérique

2006-01-01

Adaptor proteins positively or negatively regulate the T cell receptor for antigen (TCR) signaling cascade. We report that after TCR stimulation, the inhibitory adaptor downstream of kinase (Dok)-2 and its homologue Dok-1 are involved in a multimolecular complex including the lipid phosphatase Src homology 2 domain–containing inositol polyphosphate 5′-phosphatase (SHIP)-1 and Grb-2 which interacts with the membrane signaling scaffold linker for activation of T cells (LAT). Knockdown of LAT and SHIP-1 expression indicated that SHIP-1 favored recruitment of Dok-2 to LAT. Knockdown of Dok-2 and Dok-1 revealed their negative control on Akt and, unexpectedly, on Zap-70 activation. Our findings support the view that Dok-1 and -2 are critical elements of a LAT-dependent negative feedback loop that attenuates early TCR signal. Dok-1 and -2 may therefore exert a critical role in shaping the immune response and as gatekeepers for T cell tolerance. PMID:17043143

The essential role of G protein-coupled receptor (GPCR) signaling in regulating T cell immunity.

PubMed

Wang, Dashan

2018-06-01

The aim of this paper is to clarify the critical role of GPCR signaling in T cell immunity. The G protein-coupled receptors (GPCRs) are the most common targets in current pharmaceutical industry, and represent the largest and most versatile family of cell surface communicating molecules. GPCRs can be activated by a diverse array of ligands including neurotransmitters, chemokines as well as sensory stimuli. Therefore, GPCRs are involved in many key cellular and physiological processes, such as sense of light, taste and smell, neurotransmission, metabolism, endocrine and exocrine secretion. In recent years, GPCRs have been found to play an important role in immune system. T cell is an important type of immune cell, which plays a central role in cell-mediated immunity. A variety of GPCRs and their signaling mediators (RGS proteins, GRKs and β-arrestin) have been found to express in T cells and involved T cell-mediated immunity. We will summarize the role of GPCR signaling and their regulatory molecules in T cell activation, homeostasis and function in this article. GPCR signaling plays an important role in T cell activation, homeostasis and function. GPCR signaling is critical in regulating T cell immunity.

Adenosine regulates CD8 T-cell priming by inhibition of membrane-proximal T-cell receptor signalling

PubMed Central

Linnemann, Carsten; Schildberg, Frank A; Schurich, Anna; Diehl, Linda; Hegenbarth, Silke I; Endl, Elmar; Lacher, Svenja; Müller, Christa E; Frey, Jürgen; Simeoni, Luca; Schraven, Burkhart; Stabenow, Dirk; Knolle, Percy A

2009-01-01

Adenosine is a well-described anti-inflammatory modulator of immune responses within peripheral tissues. Extracellular adenosine accumulates in inflamed and damaged tissues and inhibits the effector functions of various immune cell populations, including CD8 T cells. However, it remains unclear whether extracellular adenosine also regulates the initial activation of naïve CD8 T cells by professional and semi-professional antigen-presenting cells, which determines their differentiation into effector or tolerant CD8 T cells, respectively. We show that adenosine inhibited the initial activation of murine naïve CD8 T cells after αCD3/CD28-mediated stimulation. Adenosine caused inhibition of activation, cytokine production, metabolic activity, proliferation and ultimately effector differentiation of naïve CD8 T cells. Remarkably, adenosine interfered efficiently with CD8 T-cell priming by professional antigen-presenting cells (dendritic cells) and semi-professional antigen-presenting cells (liver sinusoidal endothelial cells). Further analysis of the underlying mechanisms demonstrated that adenosine prevented rapid tyrosine phosphorylation of the key kinase ZAP-70 as well as Akt and ERK1/2 in naïve αCD3/CD28-stimulated CD8 cells. Consequently, αCD3/CD28-induced calcium-influx into CD8 cells was reduced by exposure to adenosine. Our results support the notion that extracellular adenosine controls membrane-proximal T-cell receptor signalling and thereby also differentiation of naïve CD8 T cells. These data raise the possibility that extracellular adenosine has a physiological role in the regulation of CD8 T-cell priming and differentiation in peripheral organs. PMID:19740334

Adenosine regulates CD8 T-cell priming by inhibition of membrane-proximal T-cell receptor signalling.

PubMed

Linnemann, Carsten; Schildberg, Frank A; Schurich, Anna; Diehl, Linda; Hegenbarth, Silke I; Endl, Elmar; Lacher, Svenja; Müller, Christa E; Frey, Jürgen; Simeoni, Luca; Schraven, Burkhart; Stabenow, Dirk; Knolle, Percy A

2009-09-01

Adenosine is a well-described anti-inflammatory modulator of immune responses within peripheral tissues. Extracellular adenosine accumulates in inflamed and damaged tissues and inhibits the effector functions of various immune cell populations, including CD8 T cells. However, it remains unclear whether extracellular adenosine also regulates the initial activation of naïve CD8 T cells by professional and semi-professional antigen-presenting cells, which determines their differentiation into effector or tolerant CD8 T cells, respectively. We show that adenosine inhibited the initial activation of murine naïve CD8 T cells after alphaCD3/CD28-mediated stimulation. Adenosine caused inhibition of activation, cytokine production, metabolic activity, proliferation and ultimately effector differentiation of naïve CD8 T cells. Remarkably, adenosine interfered efficiently with CD8 T-cell priming by professional antigen-presenting cells (dendritic cells) and semi-professional antigen-presenting cells (liver sinusoidal endothelial cells). Further analysis of the underlying mechanisms demonstrated that adenosine prevented rapid tyrosine phosphorylation of the key kinase ZAP-70 as well as Akt and ERK1/2 in naïve alphaCD3/CD28-stimulated CD8 cells. Consequently, alphaCD3/CD28-induced calcium-influx into CD8 cells was reduced by exposure to adenosine. Our results support the notion that extracellular adenosine controls membrane-proximal T-cell receptor signalling and thereby also differentiation of naïve CD8 T cells. These data raise the possibility that extracellular adenosine has a physiological role in the regulation of CD8 T-cell priming and differentiation in peripheral organs.

Early T-cell activation biophysics

PubMed Central

Henry, Nelly; Hivroz, Claire

2009-01-01

The T-cell is one of the main players in the mammalian immune response. It ensures antigen recognition at the surface of antigen-presenting cells in a complex and highly sensitive and specific process, in which the encounter of the T-cell receptor with the agonist peptide associated with the major histocompatibility complex triggers T-cell activation. While signaling pathways have been elucidated in increasing detail, the mechanism of TCR triggering remains highly controversial despite active research published in the past 10 years. In this paper, we present a short overview of pending questions on critical initial events associated with T-cell triggering. In particular, we examine biophysical approaches already in use, as well as future directions. We suggest that the most recent advances in fluorescence super-resolution imaging, coupled with the new classes of genetic fluorescent probes, will play an important role in elucidation of the T-cell triggering mechanism. Beyond this aspect, we predict that exploration of mechanical cues in the triggering process will provide new clues leading to clarification of the entire mechanism. PMID:20514131

PKCθ links proximal T cell and Notch signaling through localized regulation of the actin cytoskeleton

PubMed Central

Britton, Graham J; Ambler, Rachel; Clark, Danielle J; Hill, Elaine V; Tunbridge, Helen M; McNally, Kerrie E; Burton, Bronwen R; Butterweck, Philomena; Sabatos-Peyton, Catherine; Hampton-O’Neil, Lea A; Verkade, Paul; Wülfing, Christoph; Wraith, David Cameron

2017-01-01

Notch is a critical regulator of T cell differentiation and is activated through proteolytic cleavage in response to ligand engagement. Using murine myelin-reactive CD4 T cells, we demonstrate that proximal T cell signaling modulates Notch activation by a spatiotemporally constrained mechanism. The protein kinase PKCθ is a critical mediator of signaling by the T cell antigen receptor and the principal costimulatory receptor CD28. PKCθ selectively inactivates the negative regulator of F-actin generation, Coronin 1A, at the center of the T cell interface with the antigen presenting cell (APC). This allows for effective generation of the large actin-based lamellum required for recruitment of the Notch-processing membrane metalloproteinase ADAM10. Such enhancement of Notch activation is critical for efficient T cell proliferation and Th17 differentiation. We reveal a novel mechanism that, through modulation of the cytoskeleton, controls Notch activation at the T cell:APC interface thereby linking T cell receptor and Notch signaling pathways. DOI: http://dx.doi.org/10.7554/eLife.20003.001 PMID:28112644

T Cell Dynamic Activation and Functional Analysis in Nanoliter Droplet Microarray.

PubMed

Sarkar, Saheli; Motwani, Vinny; Sabhachandani, Pooja; Cohen, Noa; Konry, Tania

2015-06-01

Characterization of the heterogeneity in immune reactions requires assessing dynamic single cell responses as well as interactions between the various immune cell subsets. Maturation and activation of effector cells is regulated by cell contact-dependent and soluble factor-mediated paracrine signalling. Currently there are few methods available that allow dynamic investigation of both processes simultaneously without physically constraining non-adherent cells and eliminating crosstalk from neighboring cell pairs. We describe here a microfluidic droplet microarray platform that permits rapid functional analysis of single cell responses and co-encapsulation of heterotypic cell pairs, thereby allowing us to evaluate the dynamic activation state of primary T cells. The microfluidic droplet platform enables generation and docking of monodisperse nanoliter volume (0.523 nl) droplets, with the capacity of monitoring a thousand droplets per experiment. Single human T cells were encapsulated in droplets and stimulated on-chip with the calcium ionophore ionomycin. T cells were also co-encapsulated with dendritic cells activated by ovalbumin peptide, followed by dynamic calcium signal monitoring. Ionomycin-stimulated cells depicted fluctuation in calcium signalling compared to control. Both cell populations demonstrated marked heterogeneity in responses. Calcium signalling was observed in T cells immediately following contact with DCs, suggesting an early activation signal. T cells further showed non-contact mediated increase in calcium level, although this response was delayed compared to contact-mediated signals. Our results suggest that this nanoliter droplet array-based microfluidic platform is a promising technique for assessment of heterogeneity in various types of cellular responses, detection of early/delayed signalling events and live cell phenotyping of immune cells.

T Cell Activation Thresholds are Affected by Gravitational

NASA Technical Reports Server (NTRS)

Adams, Charley; Gonzalez, M.; Nelman-Gonzalez, M.

1999-01-01

T cells stimulated in space flight by various mitogenic signals show a dramatic reduction in proliferation and expression of early activation markers. Similar results are also obtained in a ground based model of microgravity, clinorotation, which provides a vector-averaged reduction of the apparent gravity on cells without significant shear force. Here we demonstrate that T cell inhibition is due to an increase in the required threshold for activation. Dose response curves indicate that cells activated during clinorotation require higher stimulation to achieve the same level of activation, as measured by CD69 expression. Interleukin 2 receptor expression, and DNA synthesis. The amount of stimulation necessary for 50% activation is 5 fold in the clinostat relative to static. Correlation of TCR internalization with activation also exhibit a dramatic right shift in clinorotation, demonstrating unequivocally that signal transduction mechanism independent of TCR triggering account for the increased activation threshold. Previous results from space flight experiments are consistent with the dose response curves obtained for clinorotation. Activation thresholds are important aspects of T cell memory, autoimmunity and tolerance Clinorotation is a useful, noninvasive tool for the study of cellular and biochemical event regulating T cell activation threshold and the effects of gravitation forces on these systems.

CD4(+) T-cell help amplifies innate signals for primary CD8(+) T-cell immunity.

PubMed

Bedoui, Sammy; Heath, William R; Mueller, Scott N

2016-07-01

CD8(+) T cells provide an important component of protection against intracellular infections and cancer. Immune responses by these T cells involve a primary phase of effector expansion and differentiation, followed by a contraction phase leading to memory formation and, if antigen is re-encountered, a secondary expansion phase with more rapid differentiation. Both primary and secondary phases of CD8(+) T-cell immunity have been shown to depend on CD4(+) T-cell help, although during certain infections the primary phase is variable in this requirement. One explanation for such variability relates to the strength of associated inflammatory signals, with weak signals requiring help. Here, we focus on our studies that have dissected the requirements for help in the primary phase of the CTL response to herpes simplex virus, elucidating intricate interactions and communications between CD4(+) T cells, various dendritic cell subsets, and CD8(+) T cells. We place our studies in the context of others and describe a simple model of help where CD40 signaling amplifies innate signals to enable efficient CD8(+) T-cell expansion and differentiation. This model facilitates CTL induction to various different agents, without altering the qualitative innate signals that direct other important arms of immunity. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Notch/Delta signaling constrains reengineering of pro-T cells by PU.1

PubMed Central

Franco, Christopher B.; Scripture-Adams, Deirdre D.; Proekt, Irina; Taghon, Tom; Weiss, Angela H.; Yui, Mary A.; Adams, Stephanie L.; Diamond, Rochelle A.; Rothenberg, Ellen V.

2006-01-01

PU.1 is essential for early stages of mouse T cell development but antagonizes it if expressed constitutively. Two separable mechanisms are involved: attenuation and diversion. Dysregulated PU.1 expression inhibits pro-T cell survival, proliferation, and passage through β-selection by blocking essential T cell transcription factors, signaling molecules, and Rag gene expression, which expression of a rearranged T cell antigen receptor transgene cannot rescue. However, Bcl2 transgenic cells are protected from this attenuation and may even undergo β-selection, as shown by PU.1 transduction of defined subsets of Bcl2 transgenic fetal thymocytes with differentiation in OP9-DL1 and OP9 control cultures. The outcome of PU.1 expression in these cells depends on Notch/Delta signaling. PU.1 can efficiently divert thymocytes toward a myeloid-like state with multigene regulatory changes, but Notch/Delta signaling vetoes diversion. Gene expression analysis distinguishes sets of critical T lineage regulatory genes with different combinatorial responses to PU.1 and Notch/Delta signals, suggesting particular importance for inhibition of E proteins, Myb, and/or Gfi1 (growth factor independence 1) in diversion. However, Notch signaling only protects against diversion of cells that have undergone T lineage specification after Thy-1 and CD25 up-regulation. The results imply that in T cell precursors, Notch/Delta signaling normally acts to modulate and channel PU.1 transcriptional activities during the stages from T lineage specification until commitment. PMID:16880393

CD3ζ-based chimeric antigen receptors mediate T cell activation via cis- and trans-signalling mechanisms: implications for optimization of receptor structure for adoptive cell therapy

PubMed Central

Bridgeman, J S; Ladell, K; Sheard, V E; Miners, K; Hawkins, R E; Price, D A; Gilham, D E

2014-01-01

Chimeric antigen receptors (CARs) can mediate redirected lysis of tumour cells in a major histocompatibility complex (MHC)-independent manner, thereby enabling autologous adoptive T cell therapy for a variety of malignant neoplasms. Currently, most CARs incorporate the T cell receptor (TCR) CD3ζ signalling chain; however, the precise mechanisms responsible for CAR-mediated T cell activation are unclear. In this study, we used a series of immunoreceptor tyrosine-based activation motif (ITAM)-mutant and transmembrane-modified receptors to demonstrate that CARs activate T cells both directly via the antigen-ligated signalling chain and indirectly via associated chains within the TCR complex. These observations allowed us to generate new receptors capable of eliciting polyfunctional responses in primary human T cells. This work increases our understanding of CAR function and identifies new avenues for the optimization of CAR-based therapeutic interventions. PMID:24116999

Leptin receptor signaling in T cells is required for Th17 differentiation.

PubMed

Reis, Bernardo S; Lee, Kihyun; Fanok, Melania H; Mascaraque, Cristina; Amoury, Manal; Cohn, Lillian B; Rogoz, Aneta; Dallner, Olof S; Moraes-Vieira, Pedro M; Domingos, Ana I; Mucida, Daniel

2015-06-01

The hormone leptin plays a key role in energy homeostasis, and the absence of either leptin or its receptor (LepR) leads to severe obesity and metabolic disorders. To avoid indirect effects and to address the cell-intrinsic role of leptin signaling in the immune system, we conditionally targeted LepR in T cells. In contrast with pleiotropic immune disorders reported in obese mice with leptin or LepR deficiency, we found that LepR deficiency in CD4(+) T cells resulted in a selective defect in both autoimmune and protective Th17 responses. Reduced capacity for differentiation toward a Th17 phenotype by lepr-deficient T cells was attributed to reduced activation of the STAT3 and its downstream targets. This study establishes cell-intrinsic roles for LepR signaling in the immune system and suggests that leptin signaling during T cell differentiation plays a crucial role in T cell peripheral effector function. Copyright © 2015 by The American Association of Immunologists, Inc.

Intermittent IL-7 Signaling Essential for T cell Homeostasis | Center for Cancer Research

Cancer.gov

In order for the immune system to mount an appropriate response to foreign antigens throughout a person’s life, the body must maintain a sufficient population of circulating mature, naïve T cells, a process known as T cell homeostasis. Previous studies revealed that this process depends upon signaling from the cytokine interleukin-7 (IL-7) as well as from the T cell antigen receptor (TCR). Intriguingly, signals from each pathway affect the other and lead to their alternating activation: IL-7 binding to its receptor leads to increasing expression of the TCR co-receptor CD8; sufficient CD8 expression allows TCRs to signal when bound to self-ligands, blocking IL-7 signaling; suppressed IL-7 signals lead to down-regulation of CD8 and ligand disengagement, which allows T cells to again respond to IL-7. Alfred Singer, M.D., and his colleagues in CCR’s Experimental Immunology Branch set out to understand how this intricate pathway promotes T cell survival.

A CRISPR-Based Toolbox for Studying T Cell Signal Transduction

PubMed Central

Chi, Shen; Weiss, Arthur; Wang, Haopeng

2016-01-01

CRISPR/Cas9 system is a powerful technology to perform genome editing in a variety of cell types. To facilitate the application of Cas9 in mapping T cell signaling pathways, we generated a toolbox for large-scale genetic screens in human Jurkat T cells. The toolbox has three different Jurkat cell lines expressing distinct Cas9 variants, including wild-type Cas9, dCas9-KRAB, and sunCas9. We demonstrated that the toolbox allows us to rapidly disrupt endogenous gene expression at the DNA level and to efficiently repress or activate gene expression at the transcriptional level. The toolbox, in combination with multiple currently existing genome-wide sgRNA libraries, will be useful to systematically investigate T cell signal transduction using both loss-of-function and gain-of-function genetic screens. PMID:27057542

Signalling through NK1.1 triggers NK cells to die but induces NK T cells to produce interleukin-4.

PubMed

Asea, A; Stein-Streilein, J

1998-02-01

In vivo inoculation of specific antibody is an accepted protocol for elimination of specific cell populations. Except for anti-CD3 and anti-CD4, it is not known if the depleted cells are eliminated by signalling through the target molecule or through a more non-specific mechanism. C57BL/6 mice were inoculated with anti-natural killer (NK1.1) monoclonal antibody (mAb). Thereafter spleen cells were harvested, stained for both surface and intracellular markers, and analysed by flow cytometry. As early as 2 hr post inoculation, NK cells were signalled to become apoptotic while signalling through the NK1.1 molecule activated NK1.1+ T-cell receptor (TCR)+ (NK T) cells to increase in number, and produce interleukin-4 (IL-4). Anti NK1.1 mAb was less efficient at signalling apoptosis in NK cells when NK T-cell deficient [beta 2-microglobulin beta 2m-deficient] mice were used compared with wild type mice. Efficient apoptotic signalling was restored when beta 2m-deficient mice were reconstituted with NK T cells. NK-specific antibody best signals the apoptotic process in susceptible NK cells when resistant NK T cells are present, activated, and secrete IL-4.

Function of the nucleotide exchange activity of vav1 in T cell development and activation.

PubMed

Saveliev, Alexander; Vanes, Lesley; Ksionda, Olga; Rapley, Jonathan; Smerdon, Stephen J; Rittinger, Katrin; Tybulewicz, Victor L J

2009-12-15

The guanine nucleotide exchange factor (GEF) Vav1 is essential for transducing T cell antigen receptor (TCR) signals and therefore plays a critical role in the development and activation of T cells. It has been presumed that the GEF activity of Vav1 is important for its function; however, there has been no direct demonstration of this. Here, we generated mice expressing enzymatically inactive, but normally folded, Vav1 protein. Analysis of these mice showed that the GEF activity of Vav1 was necessary for the selection of thymocytes and for the optimal activation of T cells, including signal transduction to Rac1, Akt, and integrins. In contrast, the GEF activity of Vav1 was not required for TCR-induced calcium flux, activation of extracellular signal-regulated kinase and protein kinase D1, and cell polarization. Thus, in T cells, the GEF activity of Vav1 is essential for some, but not all, of its functions.

HIV-1 Activates T Cell Signaling Independently of Antigen to Drive Viral Spread.

PubMed

Len, Alice C L; Starling, Shimona; Shivkumar, Maitreyi; Jolly, Clare

2017-01-24

HIV-1 spreads between CD4 T cells most efficiently through virus-induced cell-cell contacts. To test whether this process potentiates viral spread by activating signaling pathways, we developed an approach to analyze the phosphoproteome in infected and uninfected mixed-population T cells using differential metabolic labeling and mass spectrometry. We discovered HIV-1-induced activation of signaling networks during viral spread encompassing over 200 cellular proteins. Strikingly, pathways downstream of the T cell receptor were the most significantly activated, despite the absence of canonical antigen-dependent stimulation. The importance of this pathway was demonstrated by the depletion of proteins, and we show that HIV-1 Env-mediated cell-cell contact, the T cell receptor, and the Src kinase Lck were essential for signaling-dependent enhancement of viral dissemination. This study demonstrates that manipulation of signaling at immune cell contacts by HIV-1 is essential for promoting virus replication and defines a paradigm for antigen-independent T cell signaling. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Intermittent Ca2+ signals mediated by Orai1 regulate basal T cell motility

PubMed Central

Greenberg, Milton L; Jairaman, Amit; Akunwafo, Chijioke; Leverrier, Sabrina; Yu, Ying; Parker, Ian; Dynes, Joseph L

2017-01-01

Ca2+ influx through Orai1 channels is crucial for several T cell functions, but a role in regulating basal cellular motility has not been described. Here, we show that inhibition of Orai1 channel activity increases average cell velocities by reducing the frequency of pauses in human T cells migrating through confined spaces, even in the absence of extrinsic cell contacts or antigen recognition. Utilizing a novel ratiometric genetically encoded cytosolic Ca2+ indicator, Salsa6f, which permits real-time monitoring of cytosolic Ca2+ along with cell motility, we show that spontaneous pauses during T cell motility in vitro and in vivo coincide with episodes of cytosolic Ca2+ signaling. Furthermore, lymph node T cells exhibited two types of spontaneous Ca2+ transients: short-duration ‘sparkles’ and longer duration global signals. Our results demonstrate that spontaneous and self-peptide MHC-dependent activation of Orai1 ensures random walk behavior in T cells to optimize immune surveillance. PMID:29239723

Core binding factors are necessary for natural killer cell development and cooperate with Notch signaling during T-cell specification

PubMed Central

Guo, Yalin; Maillard, Ivan; Chakraborti, Sankhamala; Rothenberg, Ellen V.

2008-01-01

CBFβ is the non-DNA binding subunit of the core binding factors (CBFs). Mice with reduced CBFβ levels display profound, early defects in T-cell but not B-cell development. Here we show that CBFβ is also required at very early stages of natural killer (NK)–cell development. We also demonstrate that T-cell development aborts during specification, as the expression of Gata3 and Tcf7, which encode key regulators of T lineage specification, is substantially reduced, as are functional thymic progenitors. Constitutively active Notch or IL-7 signaling cannot restore T-cell expansion or differentiation of CBFβ insufficient cells, nor can overexpression of Runx1 or CBFβ overcome a lack of Notch signaling. Therefore, the ability of the prethymic cell to respond appropriately to Notch is dependent on CBFβ, and both signals converge to activate the T-cell developmental program. PMID:18390836

NF-κB signaling mechanisms in HTLV-1-induced adult T-cell leukemia/lymphoma.

PubMed

Harhaj, Edward William; Giam, Chou-Zen

2018-05-03

The human T-cell leukemia virus type 1 (HTLV-1) is a complex deltaretrovirus linked to adult T-cell leukemia/lymphoma (ATLL), a fatal CD4+ malignancy in 3-5% of infected individuals. The HTLV-1 Tax regulatory protein plays indispensable roles in regulating viral gene expression and activating cellular signaling pathways that drive the proliferation and clonal expansion of T cells bearing HTLV-1 proviral integrations. Tax is a potent activator of NF-κB, a key signaling pathway that is essential for the survival and proliferation of HTLV-1 infected T cells. However, constitutive NF-κB activation by Tax also triggers a senescence response, suggesting the possibility that only T cells capable of overcoming NF-κB-induced senescence can selectively undergo clonal expansion after HTLV-1 infection. Tax expression is often silenced in the majority of ATLL due to genetic alterations in the tax gene or DNA hypermethylation of the 5'-LTR. Despite the loss of Tax, NF-κB activation remains persistently activated in ATLL due to somatic mutations in genes in the T/B-cell receptor (T/BCR) and NF-κB signaling pathways. In this review, we focus on the key events driving Tax-dependent and independent mechanisms of NF-κB activation during the multi-step process leading to ATLL. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Core Fucosylation on T Cells, Required for Activation of T-Cell Receptor Signaling and Induction of Colitis in Mice, Is Increased in Patients With Inflammatory Bowel Disease.

PubMed

Fujii, Hironobu; Shinzaki, Shinichiro; Iijima, Hideki; Wakamatsu, Kana; Iwamoto, Chizuru; Sobajima, Tomoaki; Kuwahara, Ryusuke; Hiyama, Satoshi; Hayashi, Yoshito; Takamatsu, Shinji; Uozumi, Naofumi; Kamada, Yoshihiro; Tsujii, Masahiko; Taniguchi, Naoyuki; Takehara, Tetsuo; Miyoshi, Eiji

2016-06-01

(-/-) mice did not signal properly after activation and were not transported to lipid rafts. Core fucosylation of the TCR is required for T-cell signaling and production of inflammatory cytokines and induction of colitis in mice. Levels of TCR core fucosylation are increased on T cells from intestinal tissues of patients with IBD; this process might be blocked as a therapeutic strategy. Copyright © 2016 AGA Institute. Published by Elsevier Inc. All rights reserved.

Antigen-Specific T-Cell Activation Independently of the MHC: Chimeric Antigen Receptor-Redirected T Cells

PubMed Central

Chmielewski, Markus; Hombach, Andreas A.; Abken, Hinrich

2013-01-01

Adoptive T-cell therapy has recently shown promise in initiating a lasting anti-tumor response with spectacular therapeutic success in some cases. Specific T-cell therapy, however, is limited since a number of cancer cells are not recognized by T cells due to various mechanisms including the limited availability of tumor-specific T cells and deficiencies in antigen processing or major histocompatibility complex (MHC) expression of cancer cells. To make adoptive cell therapy applicable for the broad variety of cancer entities, patient’s T cells are engineered ex vivo with pre-defined specificity by a recombinant chimeric antigen receptor (CAR) which consists in the extracellular part of an antibody-derived domain for binding with a “tumor-associated antigen” and in the intracellular part of a T-cell receptor (TCR)-derived signaling moiety for T-cell activation. The specificity of CAR-mediated T-cell recognition is defined by the antibody domain, is independent of MHC presentation and can be extended to any target for which an antibody is available. We discuss the advantages and limitations of MHC-independent T-cell targeting by an engineered CAR in comparison to TCR modified T cells and the impact of the CAR activation threshold on redirected T-cell activation. Finally we review most significant progress recently made in early stage clinical trials to treat cancer. PMID:24273543

Antigen-Specific T-Cell Activation Independently of the MHC: Chimeric Antigen Receptor-Redirected T Cells.

PubMed

Chmielewski, Markus; Hombach, Andreas A; Abken, Hinrich

2013-01-01

Adoptive T-cell therapy has recently shown promise in initiating a lasting anti-tumor response with spectacular therapeutic success in some cases. Specific T-cell therapy, however, is limited since a number of cancer cells are not recognized by T cells due to various mechanisms including the limited availability of tumor-specific T cells and deficiencies in antigen processing or major histocompatibility complex (MHC) expression of cancer cells. To make adoptive cell therapy applicable for the broad variety of cancer entities, patient's T cells are engineered ex vivo with pre-defined specificity by a recombinant chimeric antigen receptor (CAR) which consists in the extracellular part of an antibody-derived domain for binding with a "tumor-associated antigen" and in the intracellular part of a T-cell receptor (TCR)-derived signaling moiety for T-cell activation. The specificity of CAR-mediated T-cell recognition is defined by the antibody domain, is independent of MHC presentation and can be extended to any target for which an antibody is available. We discuss the advantages and limitations of MHC-independent T-cell targeting by an engineered CAR in comparison to TCR modified T cells and the impact of the CAR activation threshold on redirected T-cell activation. Finally we review most significant progress recently made in early stage clinical trials to treat cancer.

Germinal Center T Follicular Helper Cell IL-4 Production Is Dependent on Signaling Lymphocytic Activation Molecule Receptor (CD150)

PubMed Central

Yusuf, Isharat; Kageyama, Robin; Monticelli, Laurel; Johnston, Robert J.; DiToro, Daniel; Hansen, Kyle; Barnett, Burton; Crotty, Shane

2010-01-01

CD4 T cell help is critical for the generation and maintenance of germinal centers (GCs), and T follicular helper (TFH) cells are the CD4 T cell subset required for this process. Signaling lymphocytic activation molecule (SLAM)-associated protein (SAP [SH2D1A]) expression in CD4 T cells is essential for GC development. However, SAP-deficient mice have only a moderate defect in TFH differentiation, as defined by common TFH surface markers. CXCR5+ TFH cells are found within the GC, as well as along the boundary regions of T/B cell zones. In this study, we show that GC-associated T follicular helper (GC TFH) cells can be identified by their coexpression of CXCR5 and the GL7 epitope, allowing for phenotypic and functional analysis of TFH and GC TFH populations. GC TFH cells are a functionally discrete subset of further polarized TFH cells, with enhanced B cell help capacity and a specialized ability to produce IL-4 in a TH2-independent manner. Strikingly, SAP-deficient mice have an absence of the GC TFH cell subset and SAP− TFH cells are defective in IL-4 and IL-21 production. We further demonstrate that SLAM (Slamf1, CD150), a surface receptor that uses SAP signaling, is specifically required for IL-4 production by GC TFH cells. GC TFH cells require IL-4 and -21 production for optimal help to B cells. These data illustrate complexities of SAP-dependent SLAM family receptor signaling, revealing a prominent role for SLAM receptor ligation in IL-4 production by GC CD4 T cells but not in TFH cell and GC TFH cell differentiation. PMID:20525889

Metabolic control of T-cell activation and death in SLE

PubMed Central

Fernandez, David; Perl, Andras

2009-01-01

Systemic lupus erythematosus (SLE) is characterized by abnormal T-cell activation and death, processes which are crucially dependent on the controlled production of reactive oxygen intermediates (ROI) and of ATP in mitochondria. The mitochondrial transmembrane potential (Δψm) has conclusively emerged as a critical checkpoint of ATP synthesis and cell death. Lupus T cells exhibit persistent elevation of Δψm or mitochondrial hyperpolarization (MHP) as well as depletion of ATP and glutathione which decrease activation-induced apoptosis and instead predispose T cells for necrosis, thus stimulating inflammation in SLE. NO-induced mitochondrial biogenesis in normal T cells accelerates the rapid phase and reduces the plateau of Ca2+ influx upon CD3/CD28 co-stimulation, thus mimicking the Ca2+ signaling profile of lupus T cells. Treatment of SLE patients with rapamycin improves disease activity, normalizes CD3/CD28-induced Ca2+ fluxing but fails to affect MHP, suggesting that altered Ca2+ fluxing is downstream or independent of mitochondrial dysfunction. Understanding the molecular basis and consequences of MHP is essential for controlling T-cell activation and death signaling in SLE. Lupus T cells exhibit mitochondrial dysfunctionMitochondrial hyperpolarization (MHP) and ATP depletion predispose lupus T cells to death by necrosis which is pro-inflammatoryMHP is caused by depletion of glutathione and exposure to nitric oxide (NO)NO-induced mitochondrial biogenesis regenerates the Ca2+ signaling profile of lupus T cellsRapamycin treatment normalizes Ca2+ fluxing but not MHP, suggesting that the mammalian target of rapamycin, acts as a sensor and effector of MHP in SLE PMID:18722557

An alternative mode of CD43 signal transduction activates pro-survival pathways of T lymphocytes.

PubMed

Bravo-Adame, Maria Elena; Vera-Estrella, Rosario; Barkla, Bronwyn J; Martínez-Campos, Cecilia; Flores-Alcantar, Angel; Ocelotl-Oviedo, Jose Pablo; Pedraza-Alva, Gustavo; Rosenstein, Yvonne

2017-01-01

CD43 is one of the most abundant co-stimulatory molecules on a T-cell surface; it transduces activation signals through its cytoplasmic domain, contributing to modulation of the outcome of T-cell responses. The aim of this study was to uncover new signalling pathways regulated by this sialomucin. Analysis of changes in protein abundance allowed us to identify pyruvate kinase isozyme M2 (PKM2), an enzyme of the glycolytic pathway, as an element potentially participating in the signalling cascade resulting from the engagement of CD43 and the T-cell receptor (TCR). We found that the glycolytic activity of this enzyme was not significantly increased in response to TCR+CD43 co-stimulation, but that PKM2 was tyrosine phosphorylated, suggesting that it was performing moonlight functions. We report that phosphorylation of both Y 105 of PKM2 and of Y 705 of signal transducer and activator of transcription 3 was induced in response to TCR+CD43 co-stimulation, resulting in activation of the mitogen-activated protein kinase kinase 5/extracellular signal-regulated kinase 5 (MEK5/ERK5) pathway. ERK5 and the cAMP response element binding protein (CREB) were activated, and c-Myc and nuclear factor-κB (p65) nuclear localization, as well as Bad phosphorylation, were augmented. Consistent with this, expression of human CD43 in a murine T-cell hybridoma favoured cell survival. Altogether, our data highlight novel signalling pathways for the CD43 molecule in T lymphocytes, and underscore a role for CD43 in promoting cell survival through non-glycolytic functions of metabolic enzymes. © 2016 John Wiley & Sons Ltd.

Effect Of Simulated Microgravity On Activated T Cell Gene Transcription

NASA Technical Reports Server (NTRS)

Morrow, Maureen A.

2003-01-01

Studies of T lymphocytes under the shear stress environment of clinorotation have demonstrated an inhibition of activation in response to TCR mediated signaling. These results mimic those observed during space flight. This work investigates the molecular signaling events of T lymphocyte activation with clinorotation. Purified human T lymphocytes and the T cell clone Jurkat exhibit an uncoupling of signaling as mediated through the TCR. Activation of the transcription factor AP-1 is inhibited while activation of NFAT occurs. NFAT dephosphorylation and activation is dependent on sustained Ca(++) influx. Alternatively, AP-1, which consists of two transcription factors, jun and fos, is activated by PKC and Ras mediated pathways. TCR signaling is known to be dependent on cytoskeletal rearrangements, in particular, raft aggregation is critical. Raft aggregation, as mediated through GM, crosslinking, overcomes the inhibition of T lymphocyte activation with clinorotation, indicating that the block is occurring upstream of raft aggregation. Clinorotation is shown to have an effect similar to a weak TCR signal.

Protein kinase D2 is a digital amplifier of T cell receptor–stimulated diacylglycerol signaling in naïve CD8+ T cells

PubMed Central

Navarro, María N.; Feijoo-Carnero, Carmen; Arandilla, Alba Gonzalez; Trost, Matthias; Cantrell, Doreen A.

2016-01-01

Protein kinase D2 (PKD2) is a serine and threonine kinase that is activated in T cells by diacylglycerol and protein kinase C in response to stimulation of the T cell receptor (TCR) by antigen. We quantified the activation of PKD2 at the single-cell level and found that this kinase acts as a sensitive digital amplifier of TCR engagement, enabling CD8+ T cells to match the production of inflammatory cytokines to the quality and quantity of TCR ligands. There was a digital response pattern of PKD2 activation in response to TCR engagement, such that increasing the concentration and potency of TCR ligands increased the number of cells that exhibited activated PKD2. However, for each cell that responded to TCR stimulation, the entire cellular pool of PKD2 (~400,000 molecules) was activated. Moreover, PKD2 acted as an amplification checkpoint for antigen-stimulated digital cytokine responses and translated the differential strength of TCR signaling to determine the number of naïve CD8+ T cells that became effector cells. Together, these results provide insights into PKD family kinases and how they act digitally to amplify signaling networks controlled by the TCR. PMID:25336615

Differences In Early T-Cell Signaling In Cultures Grown In a Rotating Clinostat vs. Static Controls

NASA Technical Reports Server (NTRS)

Alexamder. M.; Nelman-Gonzales, M.; Penkala, J.; Sams, C.

1999-01-01

Altered gravity has previously been demonstrated to be a stress that can influence components of the immune system. Specifically, T-cell activation has been shown to be affected by changes in gravity, exhibiting a decrease in proliferative response to in vitro stimulation in microgravity. Subsequent ground based studies utilizing a rotating clinostat to model some of the effects of microgravity have been consistent with earlier flight based experiments. These ground and flight experiments have examined T-cell activation by measuring various responses including production of cytokines, DNA synthesis and the production of various cell surface activation markers. These indicators of T-cell activation were measured anywhere from 4 to 72 hours after stimulation. Prior to the work described here, the initial signaling events in T-cell activation had not been directly examined. The goal of this project was to determine how the process of early signal transduction was affected by growth in a rotating clinostat. Here we directly show a defect in signaling from TCR to MAPK in purified peripheral T-cells activated in the clinostat by OKT3/antiCD28 coated microbeads as compared to static controls.

In vitro and in vivo effects of zinc on cytokine signalling in human T cells.

PubMed

Varin, Audrey; Larbi, Anis; Dedoussis, George V; Kanoni, Stavroula; Jajte, Jolanta; Rink, Lothar; Monti, Daniela; Malavolta, Marco; Marcellini, Fiorella; Mocchegiani, Eugenio; Herbein, Georges; Fulop, Tamas

2008-05-01

Aging is associated with changes in the immune response which are collectively called immunosenescence. The changes mainly affect the adaptive immune response and especially the T cell-mediated cellular immune response. There are a few data indicating that the cytokine signalling in T cells is altered with aging. Zinc has been specifically shown to have potent immunomodulatory effects. The aim of the present work was to study the IL-2 and IL-6 cytokine signalling and activation induced cell death (AICD) in T cells of elderly subjects of various ages and from various European countries. These experiments were performed in the frame of European Community financed project called ZINCAGE "Nutritional zinc, oxidative stress and immunosenescence: biochemical, genetic and lifestyle implications for healthy ageing", assembling 17 laboratories from 8 countries through Europe. The study was carried out in a total of 312 French and a group of 201 (26 from Italy, 63 from France, 57 from Greece, 24 from Poland and 30 from Germany) healthy non-institutionalized men and women older than 60 years of age, with available dietary data. Human peripheral blood mononuclear cells (PBMC) were obtained from heparinized blood and were stimulated in vitro by IL-2 or IL-6 for various periods and the phosphorylation of STAT3 and STAT5 was measured by FACScan. The activation induced cell death (AICD) was measured after anti-CD3 and CD28 restimulation for 48h by using the Annexin:FITC Apoptosis Kit. We found that there is an IL-2 signalling defect with aging up to 90 years of age which cannot be modulated by zinc. In contrast at 90 years and over the zinc could reverse the negative signalling effect of IL-2. There is also a signalling defect for STAT3 and STAT5 activation in T cells under IL-6 stimulation with aging and the zinc supplementation could potentiate only the STAT5 activation in the age-group 90 years and over. Studying signalling in PBL from different countries we detected less

T11TS immunotherapy repairs PI3K-AKT signaling in T-cells: Clues toward enhanced T-cell survival in rat glioma model.

PubMed

Chaudhuri, Suhnrita; Singh, Manoj K; Bhattacharya, Debanjan; Datta, Ankur; Hazra, Iman; Mondal, Somnath; Faruk Sk Md, Omar; Ronsard, Larance; Ghosh, Tushar K; Chaudhuri, Swapna

2018-02-01

Malignant glioma is the most fatal of astrocytic lineage tumors despite therapeutic advances. Onset and progression of gliomas is accompanied by severe debilitation of T-cell defense and T-cell survival. One of the chief contributors to T-cell survival downstream of activation is the PI3K-AKT pathway. Our prior studies showed that the novel immunotherapeutic molecule T11-target structure (T11TS) blocks T-cell apoptosis in glioma. We also showed activation of immunological synapse components and calcineurin-NFAT pathway following T11TS immunotherapy of glioma-bearing rats. This lead to investigations whether such T-cell activation upon T11TS therapy translates into activation of downstream PI3K/AKT signals which may be related to observed blockade of T-cell apoptosis. For the purpose, we assessed by flowcytometry and immunoblotting, expressions of PI3K, PDK1, AKT, p-AKT, and PTEN in splenic T-cells of normal, experimentally-induced glioma-bearing rats and glioma-bearing rats receiving first, second and third doses of T11TS. We also determined comparative nuclear translocation of NF-κB across groups. We found significant increases in T-cell expressions of PDK1, PI3K, and p-AKT in T11TS-treated animal groups compared to sharp downregulations in glioma. AKT levels remained unchanged across groups. PTEN levels declined sharply after T11TS immunotherapy. T11TS also caused enhanced NF-κB translocation to the T-cell nucleus compared to glioma group. Results showed heightened activation of the PI3K-AKT pathway in glioma-bearing rats following T11TS immunotherapy. These results illustrate the novel role of T11TS immunotherapy in ameliorating the PI3K pathway in T-cells in glioma-bearing animals to enhance T-cell survival, according greater defense against glioma. The study thus has far-reaching clinical outcomes. © 2017 Wiley Periodicals, Inc.

Akt signaling is critical for memory CD8+ T-cell development and tumor immune surveillance.

PubMed

Rogel, Anne; Willoughby, Jane E; Buchan, Sarah L; Leonard, Henry J; Thirdborough, Stephen M; Al-Shamkhani, Aymen

2017-02-14

Memory CD8 + T cells confer long-term immunity against tumors, and anticancer vaccines therefore should maximize their generation. Multiple memory CD8 + T-cell subsets with distinct functional and homing characteristics exist, but the signaling pathways that regulate their development are ill defined. Here we examined the role of the serine/threonine kinase Akt in the generation of protective immunity by CD8 + T cells. Akt is known to be activated by the T-cell antigen receptor and the cytokine IL-2, but its role in T-cell immunity in vivo has not been explored. Using CD8 + T cells from pdk1 K465E/K465E knockin mice, we found that decreased Akt activity inhibited the survival of T cells during the effector-to-memory cell transition and abolished their differentiation into C-X-C chemokine receptor 3 (CXCR3) lo CD43 lo effector-like memory cells. Consequently, antitumor immunity by CD8 + T cells that display defective Akt signaling was substantially diminished during the memory phase. Reduced memory T-cell survival and altered memory cell differentiation were associated with up-regulation of the proapoptotic protein Bim and the T-box transcription factor eomesodermin, respectively. These findings suggest an important role for effector-like memory CD8 + T cells in tumor immune surveillance and identify Akt as a key signaling node in the development of protective memory CD8 + T-cell responses.

Akt signaling is critical for memory CD8+ T-cell development and tumor immune surveillance

PubMed Central

Rogel, Anne; Willoughby, Jane E.; Buchan, Sarah L.; Leonard, Henry J.; Thirdborough, Stephen M.; Al-Shamkhani, Aymen

2017-01-01

Memory CD8+ T cells confer long-term immunity against tumors, and anticancer vaccines therefore should maximize their generation. Multiple memory CD8+ T-cell subsets with distinct functional and homing characteristics exist, but the signaling pathways that regulate their development are ill defined. Here we examined the role of the serine/threonine kinase Akt in the generation of protective immunity by CD8+ T cells. Akt is known to be activated by the T-cell antigen receptor and the cytokine IL-2, but its role in T-cell immunity in vivo has not been explored. Using CD8+ T cells from pdk1K465E/K465E knockin mice, we found that decreased Akt activity inhibited the survival of T cells during the effector-to-memory cell transition and abolished their differentiation into C-X-C chemokine receptor 3 (CXCR3)loCD43lo effector-like memory cells. Consequently, antitumor immunity by CD8+ T cells that display defective Akt signaling was substantially diminished during the memory phase. Reduced memory T-cell survival and altered memory cell differentiation were associated with up-regulation of the proapoptotic protein Bim and the T-box transcription factor eomesodermin, respectively. These findings suggest an important role for effector-like memory CD8+ T cells in tumor immune surveillance and identify Akt as a key signaling node in the development of protective memory CD8+ T-cell responses. PMID:28137869

Activation of B cells by non-canonical helper signals

PubMed Central

Cerutti, Andrea; Cols, Montserrat; Puga, Irene

2012-01-01

Cognate interaction between T and B lymphocytes of the adaptive immune system is essential for the production of high-affinity antibodies against microbes, and for the establishment of long-term immunological memory. Growing evidence shows that—in addition to presenting antigens to T and B cells—macrophages, dendritic cells and other cells of the innate immune system provide activating signals to B cells, as well as survival signals to antibody-secreting plasma cells. Here, we discuss how these innate immune cells contribute to the induction of highly diversified and temporally sustained antibody responses, both systemically and at mucosal sites of antigen entry. PMID:22868664

Defects of mitogen-activated protein kinase in ICOS signaling pathway lead to CD4(+) and CD8(+) T-cell dysfunction in patients with active SLE.

PubMed

Gang, Cai; Jiahui, Yang; Huaizhou, Wang; Qing, Cai; Dongbao, Zhao; Qian, Shen

2009-01-01

In this study, hypoproliferation and defects of effectors and cytokines in CD4(+) and CD8(+) T-cells via ICOS costimulation were found in active SLE patients, relative to normal individuals and RA patient controls. Exogenous IL-2 can partially reverse those defects. In addition, low level of ERK phosphorylation in ICOS-mediated signaling pathway was discovered in lupus CD4(+) and CD8(+) T-cells. When blocked with ERK-specific chemical inhibitor PD98059, cell proliferation and IL-2 production via ICOS costimulation from both CD4(+) and CD8(+) T-cells will be severely inhibited. These findings confirmed the dysfunction of both CD4(+) and CD8(+) T-cells after ICOS costimulation in lupus patients and most importantly pointed out that impairment of ERK activation might be one of the critical factors involved in ICOS-mediated IL-2 and T-cell hypoproliferation in active SLE.

Function of the Nucleotide Exchange Activity of Vav1 in T cell Development and Activation*

PubMed Central

Saveliev, Alexander; Vanes, Lesley; Ksionda, Olga; Rapley, Jonathan; Smerdon, Stephen J.; Rittinger, Katrin; Tybulewicz, Victor L. J.

2012-01-01

The guanine nucleotide exchange factor (GEF) Vav1 is essential for transducing T cell antigen receptor (TCR) signals and therefore plays a critical role in the development and activation of T cells. It has been presumed that the GEF activity of Vav1 is important for its function; however, there has been no direct demonstration of this. Here, we generated mice expressing enzymatically inactive, but normally folded, Vav1 protein. Analysis of these mice showed that the GEF activity of Vav1 was necessary for the selection of thymocytes and for the optimal activation of T cells, including signal transduction to Rac1, Akt, and integrins. In contrast, the GEF activity of Vav1 was not required for TCR-induced calcium flux, activation of extracellular signal–regulated kinase (ERK) and protein kinase D1 (PKD1), and cell polarization. Thus, in T cells, the GEF activity of Vav1 is essential for some, but not all, of its functions. PMID:20009105

ZnT-1 enhances the activity and surface expression of T-type calcium channels through activation of Ras-ERK signaling.

PubMed

Mor, Merav; Beharier, Ofer; Levy, Shiri; Kahn, Joy; Dror, Shani; Blumenthal, Daniel; Gheber, Levi A; Peretz, Asher; Katz, Amos; Moran, Arie; Etzion, Yoram

2012-07-15

Zinc transporter-1 (ZnT-1) is a putative zinc transporter that confers cellular resistance from zinc toxicity. In addition, ZnT-1 has important regulatory functions, including inhibition of L-type calcium channels and activation of Raf-1 kinase. Here we studied the effects of ZnT-1 on the expression and function of T-type calcium channels. In Xenopus oocytes expressing voltage-gated calcium channel (CaV) 3.1 or CaV3.2, ZnT-1 enhanced the low-threshold calcium currents (I(caT)) to 182 ± 15 and 167.95 ± 9.27% of control, respectively (P < 0.005 for both channels). As expected, ZnT-1 also enhanced ERK phosphorylation. Coexpression of ZnT-1 and nonactive Raf-1 blocked the ZnT-1-mediated ERK phosphorylation and abolished the ZnT-1-induced augmentation of I(caT). In mammalian cells (Chinese hamster ovary), coexpression of CaV3.1 and ZnT-1 increased the I(caT) to 166.37 ± 6.37% compared with cells expressing CaV3.1 alone (P < 0.01). Interestingly, surface expression measurements using biotinylation or total internal reflection fluorescence microscopy indicated marked ZnT-1-induced enhancement of CaV3.1 surface expression. The MEK inhibitor PD-98059 abolished the ZnT-1-induced augmentation of surface expression of CaV3.1. In cultured murine cardiomyocytes (HL-1 cells), transient exposure to zinc, leading to enhanced ZnT-1 expression, also enhanced the surface expression of endogenous CaV3.1 channels. Consistently, in these cells, endothelin-1, a potent activator of Ras-ERK signaling, enhanced the surface expression of CaV3.1 channels in a PD-98059-sensitive manner. Our findings indicate that ZnT-1 enhances the activity of CaV3.1 and CaV3.2 through activation of Ras-ERK signaling. The augmentation of CaV3.1 currents by Ras-ERK activation is associated with enhanced trafficking of the channel to the plasma membrane.

Shp1 regulates T cell homeostasis by limiting IL-4 signals

PubMed Central

Johnson, Dylan J.; Pao, Lily I.; Dhanji, Salim; Murakami, Kiichi

2013-01-01

The protein-tyrosine phosphatase Shp1 is expressed ubiquitously in hematopoietic cells and is generally viewed as a negative regulatory molecule. Mutations in Ptpn6, which encodes Shp1, result in widespread inflammation and premature death, known as the motheaten (me) phenotype. Previous studies identified Shp1 as a negative regulator of TCR signaling, but the severe systemic inflammation in me mice may have confounded our understanding of Shp1 function in T cell biology. To define the T cell–intrinsic role of Shp1, we characterized mice with a T cell–specific Shp1 deletion (Shp1fl/fl CD4-cre). Surprisingly, thymocyte selection and peripheral TCR sensitivity were unaltered in the absence of Shp1. Instead, Shp1fl/fl CD4-cre mice had increased frequencies of memory phenotype T cells that expressed elevated levels of CD44. Activation of Shp1-deficient CD4+ T cells also resulted in skewing to the Th2 lineage and increased IL-4 production. After IL-4 stimulation of Shp1-deficient T cells, Stat 6 activation was sustained, leading to enhanced Th2 skewing. Accordingly, we observed elevated serum IgE in the steady state. Blocking or genetic deletion of IL-4 in the absence of Shp1 resulted in a marked reduction of the CD44hi population. Therefore, Shp1 is an essential negative regulator of IL-4 signaling in T lymphocytes. PMID:23797092

The adapter protein SLP-76 mediates "outside-in" integrin signaling and function in T cells.

PubMed

Baker, R G; Hsu, C J; Lee, D; Jordan, M S; Maltzman, J S; Hammer, D A; Baumgart, T; Koretzky, G A

2009-10-01

The adapter protein SH2 domain-containing leukocyte protein of 76 kDa (SLP-76) is an essential mediator of signaling from the T-cell antigen receptor (TCR). We report here that SLP-76 also mediates signaling downstream of integrins in T cells and that SLP-76-deficient T cells fail to support adhesion to integrin ligands. In response to both TCR and integrin stimulation, SLP-76 relocalizes to surface microclusters that colocalize with phosphorylated signaling proteins. Disruption of SLP-76 recruitment to the protein named LAT (linker for activation of T cells) inhibits SLP-76 clustering downstream of the TCR but not downstream of integrins. Conversely, an SLP-76 mutant unable to bind ADAP (adhesion and degranulation-promoting adapter protein) forms clusters following TCR but not integrin engagement and fails to support T-cell adhesion to integrin ligands. These findings demonstrate that SLP-76 relocalizes to integrin-initiated signaling complexes by a mechanism different from that employed during TCR signaling and that SLP-76 relocalization corresponds to SLP-76-dependent integrin function in T cells.

mTOR Complex Signaling through the SEMA4A-Plexin B2 Axis Is Required for Optimal Activation and Differentiation of CD8+ T Cells.

PubMed

Ito, Daisuke; Nojima, Satoshi; Nishide, Masayuki; Okuno, Tatsusada; Takamatsu, Hyota; Kang, Sujin; Kimura, Tetsuya; Yoshida, Yuji; Morimoto, Keiko; Maeda, Yohei; Hosokawa, Takashi; Toyofuku, Toshihiko; Ohshima, Jun; Kamimura, Daisuke; Yamamoto, Masahiro; Murakami, Masaaki; Morii, Eiichi; Rakugi, Hiromi; Isaka, Yoshitaka; Kumanogoh, Atsushi

2015-08-01

Mammalian target of rapamycin (mTOR) plays crucial roles in activation and differentiation of diverse types of immune cells. Although several lines of evidence have demonstrated the importance of mTOR-mediated signals in CD4(+) T cell responses, the involvement of mTOR in CD8(+) T cell responses is not fully understood. In this study, we show that a class IV semaphorin, SEMA4A, regulates CD8(+) T cell activation and differentiation through activation of mTOR complex (mTORC) 1. SEMA4A(-/-) CD8(+) T cells exhibited impairments in production of IFN-γ and TNF-α and induction of the effector molecules granzyme B, perforin, and FAS-L. Upon infection with OVA-expressing Listeria monocytogenes, pathogen-specific effector CD8(+) T cell responses were significantly impaired in SEMA4A(-/-) mice. Furthermore, SEMA4A(-/-) CD8(+) T cells exhibited reduced mTORC1 activity and elevated mTORC2 activity, suggesting that SEMA4A is required for optimal activation of mTORC1 in CD8(+) T cells. IFN-γ production and mTORC1 activity in SEMA4A(-/-) CD8(+) T cells were restored by administration of recombinant Sema4A protein. In addition, we show that plexin B2 is a functional receptor of SEMA4A in CD8(+) T cells. Collectively, these results not only demonstrate the role of SEMA4A in CD8(+) T cells, but also reveal a novel link between a semaphorin and mTOR signaling. Copyright © 2015 by The American Association of Immunologists, Inc.

Non-immune cells equipped with T cell receptor-like signaling for cancer cell ablation

PubMed Central

Kojima, Ryosuke; Scheller, Leo; Fussenegger, Martin

2017-01-01

The ability to engineer custom cell-contact-sensing output devices into human non-immune cells would be useful for extending the applicability of cell-based cancer therapies and avoiding risks associated with engineered immune cells. Here, we have developed a new class of synthetic T-cell receptor-like signal-transduction device that functions efficiently in human non-immune cells and triggers release of output molecules specifically upon sensing contact with a target cell. This device employs an interleukin signaling cascade, whose OFF/ON switching is controlled by biophysical segregation of a transmembrane signal-inhibitory protein from the sensor cell/target cell interface. We further showed that designer non-immune cells equipped with this device driving expression of a membrane-penetrator/prodrug-activating enzyme construct could specifically kill target cells in the presence of the prodrug, indicating its potential usefulness for target-cell-specific, cell-based enzyme-prodrug cancer therapy. Our study also contributes to advancement of synthetic biology by extending available design principles to transmit extracellular information to cells. PMID:29131143

The effect of inhibitory signals on the priming of drug-hapten-specific T-cells that express distinct Vβ receptors

PubMed Central

Gibson, Andrew; Faulkner, Lee; Lichtenfels, Maike; Ogese, Monday; Al-Attar, Zaid; Alfirevic, Ana; Esser, Philipp R.; Martin, Stefan F.; Pirmohamed, Munir; Park, B. Kevin; Naisbitt, Dean J.

2017-01-01

Drug hypersensitivity involves the activation of T-cells in an HLA allele-restricted manner. Since the majority of individuals who carry HLA risk alleles do not develop hypersensitivity, other parameters must control development of the drug-specific T-cell response. Thus, we have utilized a T-cell priming assay and nitroso sulfamethoxazole (SMX-NO) as a model antigen to investigate (1) the activation of specific T-cell receptor (TCR)Vβ subtypes, (2) the impact of PD-1, CTLA4 and TIM-3 co-inhibitory signalling on activation of naïve and memory T-cells and (3) the ability of Tregs to prevent responses. An expansion of the TCR repertoire was observed for nine different Vβ subtypes, while spectratyping revealed that SMX-NO-specific T-cell responses are controlled by public TCRs present in all individuals alongside private TCR repertoires specific to each individual. We proceeded to evaluate the extent to which the activation of these TCR Vβ-restricted antigen-specific T-cell responses is governed by regulatory signals. Blockade of PDL-1/CTLA4 signalling dampened activation of SMX-NO-specific naïve and memory T-cells, while blockade of TIM-3 produced no effect. PD-1, CTLA4, and TIM-3 displayed discrete expression profiles during drug-induced T-cell activation and expression of each receptor was enhanced on dividing T-cells. As these receptors are also expressed on Tregs, Treg-mediated suppression of SMX-NO-induced T-cell activation was investigated. Tregs significantly dampened the priming of T-cells. In conclusion, our findings demonstrate that distinct TCR Vβ subtypes, dysregulation of co-inhibitory signalling pathways and dysfunctional Tregs may influence predisposition to hypersensitivity. PMID:28687658

Innate and cytokine-driven signals, rather than microbial antigens, dominate in natural killer T cell activation during microbial infection.

PubMed

Brigl, Manfred; Tatituri, Raju V V; Watts, Gerald F M; Bhowruth, Veemal; Leadbetter, Elizabeth A; Barton, Nathaniel; Cohen, Nadia R; Hsu, Fong-Fu; Besra, Gurdyal S; Brenner, Michael B

2011-06-06

Invariant natural killer T cells (iNKT cells) are critical for host defense against a variety of microbial pathogens. However, the central question of how iNKT cells are activated by microbes has not been fully explained. The example of adaptive MHC-restricted T cells, studies using synthetic pharmacological α-galactosylceramides, and the recent discovery of microbial iNKT cell ligands have all suggested that recognition of foreign lipid antigens is the main driver for iNKT cell activation during infection. However, when we compared the role of microbial antigens versus innate cytokine-driven mechanisms, we found that iNKT cell interferon-γ production after in vitro stimulation or infection with diverse bacteria overwhelmingly depended on toll-like receptor-driven IL-12. Importantly, activation of iNKT cells in vivo during infection with Sphingomonas yanoikuyae or Streptococcus pneumoniae, pathogens which are known to express iNKT cell antigens and which require iNKT cells for effective protection, also predominantly depended on IL-12. Constitutive expression of high levels of IL-12 receptor by iNKT cells enabled instant IL-12-induced STAT4 activation, demonstrating that among T cells, iNKT cells are uniquely equipped for immediate, cytokine-driven activation. These findings reveal that innate and cytokine-driven signals, rather than cognate microbial antigen, dominate in iNKT cell activation during microbial infections.

HIV Envelope gp120 Alters T Cell Receptor Mobilization in the Immunological Synapse of Uninfected CD4 T Cells and Augments T Cell Activation

PubMed Central

Deng, Jing; Mitsuki, Yu-ya; Shen, Guomiao; Ray, Jocelyn C.; Cicala, Claudia; Arthos, James; Dustin, Michael L.

2016-01-01

ABSTRACT HIV is transmitted most efficiently from cell to cell, and productive infection occurs mainly in activated CD4 T cells. It is postulated that HIV exploits immunological synapses formed between CD4 T cells and antigen-presenting cells to facilitate the targeting and infection of activated CD4 T cells. This study sought to evaluate how the presence of the HIV envelope (Env) in the CD4 T cell immunological synapse affects synapse formation and intracellular signaling to impact the downstream T cell activation events. CD4 T cells were applied to supported lipid bilayers that were reconstituted with HIV Env gp120, anti-T cell receptor (anti-TCR) monoclonal antibody, and ICAM-1 to represent the surface of HIV Env-bearing antigen-presenting cells. The results showed that the HIV Env did not disrupt immunological synapse formation. Instead, the HIV Env accumulated with TCR at the center of the synapse, altered the kinetics of TCR recruitment to the synapse and affected synapse morphology over time. The HIV Env also prolonged Lck phosphorylation at the synapse and enhanced TCR-induced CD69 upregulation, interleukin-2 secretion, and proliferation to promote virus infection. These results suggest that HIV uses the immunological synapse as a conduit not only for selective virus transmission to activated CD4 T cells but also for boosting the T cell activation state, thereby increasing its likelihood of undergoing productive replication in targeted CD4 T cells. IMPORTANCE There are about two million new HIV infections every year. A better understanding of how HIV is transmitted to susceptible cells is critical to devise effective strategies to prevent HIV infection. Activated CD4 T cells are preferentially infected by HIV, although how this is accomplished is not fully understood. This study examined whether HIV co-opts the normal T cell activation process through the so-called immunological synapse. We found that the HIV envelope is recruited to the center of the

Integration of T Cell Receptor, Notch and Cytokine Signals Programs in Mouse γδ T Cell Effector Differentiation.

PubMed

Zarin, Payam; In, Tracy S H; Chen, Edward L Y; Singh, Jastaranpreet; Wong, Gladys W; Mohtashami, Mahmood; Wiest, David L; Anderson, Michele K; Zúñiga-Pflücker, Juan Carlos

2018-05-13

γδ T-cells perform a wide range of tissue and disease specific functions that are dependent on the effector cytokines produced by these cells. However, the aggregate signals required for the development of interferon-γ (IFNγ) and interleukin-17 (IL-17) producing γδ T-cells remain unknown. Here, we define the cues involved in the functional programming of γδ T-cells, by examining the roles of T-cell receptor (TCR), Notch, and cytokine-receptor signaling. KN6 γδTCR-transduced Rag2 -/- T-cell progenitors were cultured on stromal cells variably expressing TCR and Notch ligands, supplemented with different cytokines. We found that distinct combinations of these signals are required to program IFNγ versus IL-17 producing γδ T cell subsets, with Notch and weak TCR ligands optimally enabling development of γδ17 cells in the presence of IL-1β, IL-21 and IL-23. Notably, these cytokines were also shown to be required for the intrathymic development of γδ17 cells. Together, this work provides a framework of how signals downstream of TCR, Notch and cytokine receptors integrate to program the effector function of IFNγ and IL-17 producing γδ T-cell subsets. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

End-binding protein 1 controls signal propagation from the T cell receptor

PubMed Central

Martín-Cófreces, Noa B; Baixauli, Francesc; López, María J; Gil, Diana; Monjas, Alicia; Alarcón, Balbino; Sánchez-Madrid, Francisco

2012-01-01

The role of microtubules (MTs) in the control and dynamics of the immune synapse (IS) remains unresolved. Here, we show that T cell activation requires the growth of MTs mediated by the plus-end specific protein end-binding 1 (EB1). A direct interaction of the T cell receptor (TCR) complex with EB1 provides the molecular basis for EB1 activity promoting TCR encounter with signalling vesicles at the IS. EB1 knockdown alters TCR dynamics at the IS and prevents propagation of the TCR activation signal to LAT, thus inhibiting activation of PLCγ1 and its localization to the IS. These results identify a role for EB1 interaction with the TCR in controlling TCR sorting and its connection with the LAT/PLCγ1 signalosome. PMID:22922463

Mesenchymal stem cells promote the sustained expression of CD69 on activated T lymphocytes: roles of canonical and non-canonical NF-κB signalling

PubMed Central

Saldanha-Araujo, Felipe; Haddad, Rodrigo; de Farias, Kelen C R Malmegrim; Souza, Alessandra de Paula Alves; Palma, Patrícia V; Araujo, Amélia G; Orellana, Maristela D; Voltarelli, Julio C; Covas, Dimas T; Zago, Marco A; Panepucci, Rodrigo A

2012-01-01

Abstract Mesenchymal stem cells (MSCs) are known to induce the conversion of activated T cells into regulatory T cells in vitro. The marker CD69 is a target of canonical nuclear factor kappa-B (NF-κB) signalling and is transiently expressed upon activation; however, stable CD69 expression defines cells with immunoregulatory properties. Given its enormous therapeutic potential, we explored the molecular mechanisms underlying the induction of regulatory cells by MSCs. Peripheral blood CD3+ T cells were activated and cultured in the presence or absence of MSCs. CD4+ cell mRNA expression was then characterized by microarray analysis. The drug BAY11-7082 (BAY) and a siRNA against v-rel reticuloendotheliosis viral oncogene homolog B (RELB) were used to explore the differential roles of canonical and non-canonical NF-κB signalling, respectively. Flow cytometry and real-time PCR were used for analyses. Genes with immunoregulatory functions, CD69 and non-canonical NF-κB subunits (RELB and NFKB2) were all expressed at higher levels in lymphocytes co-cultured with MSCs. The frequency of CD69+ cells among lymphocytes cultured alone progressively decreased after activation. In contrast, the frequency of CD69+ cells increased significantly following activation in lymphocytes co-cultured with MSCs. Inhibition of canonical NF-κB signalling by BAY immediately following activation blocked the induction of CD69; however, inhibition of canonical NF-κB signalling on the third day further induced the expression of CD69. Furthermore, late expression of CD69 was inhibited by RELB siRNA. These results indicate that the canonical NF-κB pathway controls the early expression of CD69 after activation; however, in an immunoregulatory context, late and sustained CD69 expression is promoted by the non-canonical pathway and is inhibited by canonical NF-κB signalling. PMID:21777379

Aberrant Signaling Pathways in T-Cell Acute Lymphoblastic Leukemia

PubMed Central

Bongiovanni, Deborah; Saccomani, Valentina

2017-01-01

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disease caused by the malignant transformation of immature progenitors primed towards T-cell development. Clinically, T-ALL patients present with diffuse infiltration of the bone marrow by immature T-cell blasts high blood cell counts, mediastinal involvement, and diffusion to the central nervous system. In the past decade, the genomic landscape of T-ALL has been the target of intense research. The identification of specific genomic alterations has contributed to identify strong oncogenic drivers and signaling pathways regulating leukemia growth. Notwithstanding, T-ALL patients are still treated with high-dose multiagent chemotherapy, potentially exposing these patients to considerable acute and long-term side effects. This review summarizes recent advances in our understanding of the signaling pathways relevant for the pathogenesis of T-ALL and the opportunities offered for targeted therapy. PMID:28872614

Increasing JAK/STAT Signaling Function of Infant CD4+ T Cells during the First Year of Life

PubMed Central

dela Peña-Ponce, Myra Grace; Rodriguez-Nieves, Jennifer; Bernhardt, Janice; Tuck, Ryan; Choudhary, Neelima; Mengual, Michael; Mollan, Katie R.; Hudgens, Michael G.; Peter-Wohl, Sigal; De Paris, Kristina

2017-01-01

Most infant deaths occur in the first year of life. Yet, our knowledge of immune development during this period is scarce and derived from cord blood (CB) only. To more effectively combat pediatric diseases, a deeper understanding of the kinetics and the factors that regulate the maturation of immune functions in early life is needed. Increased disease susceptibility of infants is generally attributed to T helper 2-biased immune responses. The differentiation of CD4+ T cells along a specific T helper cell lineage is dependent on the pathogen type, and on costimulatory and cytokine signals provided by antigen-presenting cells. Cytokines also regulate many other aspects of the host immune response. Therefore, toward the goal of increasing our knowledge of early immune development, we defined the temporal development of the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling function of CD4+ T cells using cross-sectional blood samples from healthy infants ages 0 (birth) to 14 months. We specifically focused on cytokines important in T cell differentiation (IFN-γ, IL-12, and IL-4) or in T cell survival and expansion (IL-2 and IL-7) in infant CD4+ T cells. Independent of the cytokine tested, JAK/STAT signaling in infant compared to adult CD4+ T cells was impaired at birth, but increased during the first year, with the most pronounced changes occurring in the first 6 months. The relative change in JAK/STAT signaling of infant CD4+ T cells with age was distinct for each cytokine tested. Thus, while about 60% of CB CD4+ T cells could efficiently activate STAT6 in response to IL-4, less than 5% of CB CD4+ T cells were able to activate the JAK/STAT pathway in response to IFN-γ, IL-12 or IL-2. By 4–6 months of age, the activation of the cytokine-specific STAT molecules was comparable to adults in response to IL-4 and IFN-γ, while IL-2- and IL-12-induced STAT activation remained below adult levels even at 1 year. These results

Vav1 GEF activity is required for T cell mediated allograft rejection.

PubMed

Haubert, Dirk; Li, Jianping; Saveliev, Alexander; Calzascia, Thomas; Sutter, Esther; Metzler, Barbara; Kaiser, Daniel; Tybulewicz, Victor L J; Weckbecker, Gisbert

2012-06-01

The GDP exchange factor (GEF) Vav1 is a central signal transducer downstream of the T cell receptor and has been identified as a key factor for T cell activation in the context of allograft rejection. Vav1 has been shown to transduce signals both dependent and independent of its GEF function. The most promising approach to disrupt Vav1 activity by pharmacological inhibition would be to target its GEF function. However, the contribution of Vav1 GEF activity for allogeneic T cell activation has not been clarified yet. To address this question, we used knock-in mice bearing a mutated Vav1 with disrupted GEF activity but intact GEF-independent functions. T cells from these mice showed strongly reduced proliferation and activation in response to allogeneic stimulation. Furthermore, lack of Vav1 GEF activity strongly abrogated the in vivo expansion of T cells in a systemic graft-versus-host model. In a cardiac transplantation model, mice with disrupted Vav1 GEF activity show prolonged allograft survival. These findings demonstrate a strong requirement for Vav1 GEF activity for allogeneic T cell activation and graft rejection suggesting that disruption of Vav1 GEF activity alone is sufficient to induce significant immunosuppression. Copyright © 2012 Elsevier B.V. All rights reserved.

Vav1 GEF activity is required for T cell mediated allograft rejection

PubMed Central

Haubert, Dirk; Li, Jianping; Saveliev, Alexander; Calzascia, Thomas; Sutter, Esther; Metzler, Barbara; Kaiser, Daniel; Tybulewicz, Victor L.J.; Weckbecker, Gisbert

2012-01-01

The GDP exchange factor (GEF) Vav1 is a central signal transducer downstream of the T cell receptor and has been identified as a key factor for T cell activation in the context of allograft rejection. Vav1 has been shown to transduce signals both dependent and independent of its GEF function. The most promising approach to disrupt Vav1 activity by pharmacological inhibition would be to target its GEF function. However, the contribution of Vav1 GEF activity for allogeneic T cell activation has not been clarified yet. To address this question, we used knock-in mice bearing a mutated Vav1 with disrupted GEF activity but intact GEF-independent functions. T cells from these mice showed strongly reduced proliferation and activation in response to allogeneic stimulation. Furthermore, lack of Vav1 GEF activity strongly abrogated the in vivo expansion of T cells in a systemic graft-versus-host model. In a cardiac transplantation model, mice with disrupted Vav1 GEF activity show prolonged allograft survival. These findings demonstrate a strong requirement for Vav1 GEF activity for allogeneic T cell activation and graft rejection suggesting that disruption of Vav1 GEF activity alone is sufficient to induce significant immunosuppression. PMID:22456277

Constitutive Signaling from an Engineered IL7 Receptor Promotes Durable Tumor Elimination by Tumor-Redirected T Cells.

PubMed

Shum, Thomas; Omer, Bilal; Tashiro, Haruko; Kruse, Robert L; Wagner, Dimitrios L; Parikh, Kathan; Yi, Zhongzhen; Sauer, Tim; Liu, Daofeng; Parihar, Robin; Castillo, Paul; Liu, Hao; Brenner, Malcolm K; Metelitsa, Leonid S; Gottschalk, Stephen; Rooney, Cliona M

2017-11-01

Successful adoptive T-cell immunotherapy of solid tumors will require improved expansion and cytotoxicity of tumor-directed T cells within tumors. Providing recombinant or transgenic cytokines may produce the desired benefits but is associated with significant toxicities, constraining clinical use. To circumvent this limitation, we constructed a constitutively signaling cytokine receptor, C7R, which potently triggers the IL7 signaling axis but is unresponsive to extracellular cytokine. This strategy augments modified T-cell function following antigen exposure, but avoids stimulating bystander lymphocytes. Coexpressing the C7R with a tumor-directed chimeric antigen receptor (CAR) increased T-cell proliferation, survival, and antitumor activity during repeated exposure to tumor cells, without T-cell dysfunction or autonomous T-cell growth. Furthermore, C7R-coexpressing CAR T cells were active against metastatic neuroblastoma and orthotopic glioblastoma xenograft models even at cell doses that had been ineffective without C7R support. C7R may thus be able to enhance antigen-specific T-cell therapies against cancer. Significance: The constitutively signaling C7R system developed here delivers potent IL7 stimulation to CAR T cells, increasing their persistence and antitumor activity against multiple preclinical tumor models, supporting its clinical development. Cancer Discov; 7(11); 1238-47. ©2017 AACR. This article is highlighted in the In This Issue feature, p. 1201 . ©2017 American Association for Cancer Research.

Regulation of T cell receptor complex-mediated signaling by ubiquitin and ubiquitin-like modifications.

PubMed

Friend, Samantha F; Deason-Towne, Francina; Peterson, Lisa K; Berger, Allison J; Dragone, Leonard L

2014-01-01

Post-translational protein modifications are a dynamic method of regulating protein function in response to environmental signals. As with any cellular process, T cell receptor (TCR) complex-mediated signaling is highly regulated, since the strength and duration of TCR-generated signals governs T cell development and activation. While regulation of TCR complex-mediated signaling by phosphorylation has been well studied, regulation by ubiquitin and ubiquitin-like modifiers is still an emerging area of investigation. This review will examine how ubiquitin, E3 ubiquitin ligases, and other ubiquitin-like modifications such as SUMO and NEDD8 regulate TCR complex-mediated signaling.

Regulation of T cell receptor complex-mediated signaling by ubiquitin and ubiquitin-like modifications

PubMed Central

Friend, Samantha F; Deason-Towne, Francina; Peterson, Lisa K; Berger, Allison J; Dragone, Leonard L

2014-01-01

Post-translational protein modifications are a dynamic method of regulating protein function in response to environmental signals. As with any cellular process, T cell receptor (TCR) complex-mediated signaling is highly regulated, since the strength and duration of TCR-generated signals governs T cell development and activation. While regulation of TCR complex-mediated signaling by phosphorylation has been well studied, regulation by ubiquitin and ubiquitin-like modifiers is still an emerging area of investigation. This review will examine how ubiquitin, E3 ubiquitin ligases, and other ubiquitin-like modifications such as SUMO and NEDD8 regulate TCR complex-mediated signaling. PMID:25628960

Cholinergic signaling inhibits oxalate transport by human intestinal T84 cells

PubMed Central

Cheng, Ming; Aronson, Peter S.

2012-01-01

Urolithiasis remains a very common disease in Western countries. Seventy to eighty percent of kidney stones are composed of calcium oxalate, and minor changes in urinary oxalate affect stone risk. Intestinal oxalate secretion mediated by anion exchanger SLC26A6 plays a major constitutive role in limiting net absorption of ingested oxalate, thereby preventing hyperoxaluria and calcium oxalate urolithiasis. Using the relatively selective PKC-δ inhibitor rottlerin, we had previously found that PKC-δ activation inhibits Slc26a6 activity in mouse duodenal tissue. To identify a model system to study physiologic agonists upstream of PKC-δ, we characterized the human intestinal cell line T84. Knockdown studies demonstrated that endogenous SLC26A6 mediates most of the oxalate transport by T84 cells. Cholinergic stimulation with carbachol modulates intestinal ion transport through signaling pathways including PKC activation. We therefore examined whether carbachol affects oxalate transport in T84 cells. We found that carbachol significantly inhibited oxalate transport by T84 cells, an effect blocked by rottlerin. Carbachol also led to significant translocation of PKC-δ from the cytosol to the membrane of T84 cells. Using pharmacological inhibitors, we observed that carbachol inhibits oxalate transport through the M3 muscarinic receptor and phospholipase C. Utilizing the Src inhibitor PP2 and phosphorylation studies, we found that the observed regulation downstream of PKC-δ is partially mediated by c-Src. Biotinylation studies revealed that carbachol inhibits oxalate transport by reducing SLC26A6 surface expression. We conclude that carbachol negatively regulates oxalate transport by reducing SLC26A6 surface expression in T84 cells through signaling pathways including the M3 muscarinic receptor, phospholipase C, PKC-δ, and c-Src. PMID:21956166

Pontin is required for pre-TCR signaling at the β-selection checkpoint in T cell development.

PubMed

Boo, Kyungjin; Baek, Sung Hee; Lee, Ho

2014-04-25

Pontin is a chromatin remodeling factor that possesses both ATPase and DNA helicase activities. Based on high expression in lymphoid tissues, we examined whether Pontin has a T cell-specific function. We generated Pontin(f/f);Lck-Cre mice, in which Pontin can be conditionally deleted in T cells and then explored T cell-specific function of Pontin in vivo. Here, we show that specific abrogation of Pontin expression in T cells almost completely blocked development of αβ T cells at the β-selection checkpoint by inducing cell apoptosis indicating that Pontin is essential for early T cell development. Pontin-deficient thymocytes show a comparable expression level of T cell receptor (TCR)β chain, but have enhanced activation of p53 and Notch signaling compared to wild-type thymocytes. Intriguingly, the developmental block of αβ T cells can be partially rescued by loss of p53. Together, our data demonstrate a novel role of Pontin as a crucial regulator in pre-TCR signaling during T cell development. Copyright © 2014 Elsevier Inc. All rights reserved.

T-Cell Receptor- and CD28-induced Vav1 activity is required for the accumulation of primed T cells into antigenic tissue

PubMed Central

David, Rachel; Ma, Liang; Ivetic, Aleksandar; Takesono, Aya; Ridley, Anne J.; Chai, Jian-Guo; Tybulewicz, Victor; Marelli-Berg, Federica M.

2016-01-01

Localization of primed T cells to antigenic tissue is essential for the development of effective immunity. Together with tissue-selective homing molecules, T-cell receptor (TCR)- and CD28-mediated signals have been shown to promote transendothelial migration of specific T cells into non-lymphoid antigen-rich tissue tissue. However, the cellular and molecular requirements for T-cell accumulation to target tissue following their recruitment are largely undefined. The guanine nucleotide exchange factor (GEF) Vav1 has an integral role in coupling TCR and CD28 to signalling pathways that regulate T cell activation and migration. Here, we have investigated the contribution of TCR- and CD28-induced Vav1 activity to the trafficking and localization of primed HY-specific CD4+ T cells to antigenic sites. Severe migratory defects displayed by Vav1-/- T cells in vitro were fully compensated by a combination of shear flow and chemokines, leading to normal recruitment of Vav1-/- T cells in vivo. In contrast, Vav1-/- T-cell retention into antigen-rich tissue was severely impaired, reflecting their inability to engage in sustained TCR- and CD28-mediated interactions with tissue-resident antigen-presenting cells (APCs). This novel function of APC-induced, TCR- and CD28-mediated Vav1 activity in the regulation of effector T-cell immunity highlights its potential as a therapeutic target in T-cell-mediated tissue damage. PMID:19060239

The Non-Classical MAP Kinase ERK3 Controls T Cell Activation

PubMed Central

Mathien, Simon; Rousseau, Justine; Thébault, Paméla; Daudelin, Jean-François; Rooney, Julie; Turgeon, Benjamin; Beauchamp, Claudine; Meloche, Sylvain; Labrecque, Nathalie

2014-01-01

The classical mitogen-activated protein kinases (MAPKs) ERK1 and ERK2 are activated upon stimulation of cells with a broad range of extracellular signals (including antigens) allowing cellular responses to occur. ERK3 is an atypical member of the MAPK family with highest homology to ERK1/2. Therefore, we evaluated the role of ERK3 in mature T cell response. Mouse resting T cells do not transcribe ERK3 but its expression is induced in both CD4+ and CD8+ T cells following T cell receptor (TCR)-induced T cell activation. This induction of ERK3 expression in T lymphocytes requires activation of the classical MAPK ERK1 and ERK2. Moreover, ERK3 protein is phosphorylated and associates with MK5 in activated primary T cells. We show that ERK3-deficient T cells have a decreased proliferation rate and are impaired in cytokine secretion following in vitro stimulation with low dose of anti-CD3 antibodies. Our findings identify the atypical MAPK ERK3 as a new and important regulator of TCR-induced T cell activation. PMID:24475167

An electrostatic selection mechanism controls sequential kinase signaling downstream of the T cell receptor

PubMed Central

Shah, Neel H; Wang, Qi; Yan, Qingrong; Karandur, Deepti; Kadlecek, Theresa A; Fallahee, Ian R; Russ, William P; Ranganathan, Rama; Weiss, Arthur; Kuriyan, John

2016-01-01

The sequence of events that initiates T cell signaling is dictated by the specificities and order of activation of the tyrosine kinases that signal downstream of the T cell receptor. Using a platform that combines exhaustive point-mutagenesis of peptide substrates, bacterial surface-display, cell sorting, and deep sequencing, we have defined the specificities of the first two kinases in this pathway, Lck and ZAP-70, for the T cell receptor ζ chain and the scaffold proteins LAT and SLP-76. We find that ZAP-70 selects its substrates by utilizing an electrostatic mechanism that excludes substrates with positively-charged residues and favors LAT and SLP-76 phosphosites that are surrounded by negatively-charged residues. This mechanism prevents ZAP-70 from phosphorylating its own activation loop, thereby enforcing its strict dependence on Lck for activation. The sequence features in ZAP-70, LAT, and SLP-76 that underlie electrostatic selectivity likely contribute to the specific response of T cells to foreign antigens. DOI: http://dx.doi.org/10.7554/eLife.20105.001 PMID:27700984

TCR Signal Strength Regulates Akt Substrate Specificity To Induce Alternate Murine Th and T Regulatory Cell Differentiation Programs.

PubMed

Hawse, William F; Boggess, William C; Morel, Penelope A

2017-07-15

The Akt/mTOR pathway is a key driver of murine CD4 + T cell differentiation, and induction of regulatory T (Treg) cells results from low TCR signal strength and low Akt/mTOR signaling. However, strong TCR signals induce high Akt activity that promotes Th cell induction. Yet, it is unclear how Akt controls alternate T cell fate decisions. We find that the strength of the TCR signal results in differential Akt enzymatic activity. Surprisingly, the Akt substrate networks associated with T cell fate decisions are qualitatively different. Proteomic profiling of Akt signaling networks during Treg versus Th induction demonstrates that Akt differentially regulates RNA processing and splicing factors to drive T cell differentiation. Interestingly, heterogeneous nuclear ribonucleoprotein (hnRNP) L or hnRNP A1 are Akt substrates during Treg induction and have known roles in regulating the stability and splicing of key mRNAs that code for proteins in the canonical TCR signaling pathway, including CD3ζ and CD45. Functionally, inhibition of Akt enzymatic activity results in the dysregulation of splicing during T cell differentiation, and knockdown of hnRNP L or hnRNP A1 results in the lower induction of Treg cells. Together, this work suggests that a switch in substrate specificity coupled to the phosphorylation status of Akt may lead to alternative cell fates and demonstrates that proteins involved with alternative splicing are important factors in T cell fate decisions. Copyright © 2017 by The American Association of Immunologists, Inc.

Estrogen prevents bone loss through transforming growth factor β signaling in T cells

PubMed Central

Gao, Yuhao; Qian, Wei-Ping; Dark, Kimberly; Toraldo, Gianluca; Lin, Angela S. P.; Guldberg, Robert E.; Flavell, Richard A.; Weitzmann, M. Neale; Pacifici, Roberto

2004-01-01

Estrogen (E) deficiency leads to an expansion of the pool of tumor necrosis factor (TNF)-producing T cells through an IFN-γ-dependent pathway that results in increased levels of the osteoclastogenic cytokine TNF in the bone marrow. Disregulated IFN-γ production is instrumental for the bone loss induced by ovariectomy (ovx), but the responsible mechanism is unknown. We now show that mice with T cell-specific blockade of type β transforming growth factor (TGFβ) signaling are completely insensitive to the bone-sparing effect of E. This phenotype results from a failure of E to repress IFN-γ production, which, in turn, leads to increased T cell activation and T cell TNF production. Furthermore, ovx blunts TGFβ levels in the bone marrow, and overexpression of TGFβ in vivo prevents ovx-induced bone loss. These findings demonstrate that E prevents bone loss through a TGFβ-dependent mechanism, and that TGFβ signaling in T cells preserves bone homeostasis by blunting T cell activation. Thus, stimulation of TGFβ production in the bone marrow is a critical “upstream” mechanism by which E prevents bone loss, and enhancement of TGFβ levels in vivo may constitute a previously undescribed therapeutic approach for preventing bone loss. PMID:15531637

T Cell Receptor Signaling in the Control of Regulatory T Cell Differentiation and Function

PubMed Central

Li, Ming O.; Rudensky, Alexander Y.

2016-01-01

Regulatory T cells (TReg cells), a specialized T cell lineage, have a pivotal function in the control of self-tolerance and inflammatory responses. Recent studies have revealed a discrete mode of TCR signaling that regulates Treg cell differentiation, maintenance and function and that impacts on gene expression, metabolism, cell adhesion and migration of these cells. Here, we discuss the emerging understanding of TCR-guided differentiation of Treg cells in the context of their function in health and disease. PMID:27026074

Placing Ion Channels into a Signaling Network of T Cells: From Maturing Thymocytes to Healthy T Lymphocytes or Leukemic T Lymphoblasts

PubMed Central

Delgado-Enciso, Iván; Best-Aguilera, Carlos; Rojas-Sotelo, Rocío Monserrat; Pottosin, Igor

2015-01-01

T leukemogenesis is a multistep process, where the genetic errors during T cell maturation cause the healthy progenitor to convert into the leukemic precursor that lost its ability to differentiate but possesses high potential for proliferation, self-renewal, and migration. A new misdirecting “leukemogenic” signaling network appears, composed by three types of participants which are encoded by (1) genes implicated in determined stages of T cell development but deregulated by translocations or mutations, (2) genes which normally do not participate in T cell development but are upregulated, and (3) nondifferentially expressed genes which become highly interconnected with genes expressed differentially. It appears that each of three groups may contain genes coding ion channels. In T cells, ion channels are implicated in regulation of cell cycle progression, differentiation, activation, migration, and cell death. In the present review we are going to reveal a relationship between different genetic defects, which drive the T cell neoplasias, with calcium signaling and ion channels. We suggest that changes in regulation of various ion channels in different types of the T leukemias may provide the intracellular ion microenvironment favorable to maintain self-renewal capacity, arrest differentiation, induce proliferation, and enhance motility. PMID:25866806

Infiltrating T cells promote renal cell carcinoma (RCC) progression via altering the estrogen receptor β-DAB2IP signals.

PubMed

Yeh, Chiuan-Ren; Ou, Zheng-Yu; Xiao, Guang-Qian; Guancial, Elizabeth; Yeh, Shuyuan

2015-12-29

Previous studies indicated the T cells, one of the most common types of immune cells existing in the microenvironment of renal cell carcinoma (RCC), may influence the progression of RCC. The potential linkage of T cells and the estrogen receptor beta (ERβ), a key player to impact RCC progression, however, remains unclear. Our results demonstrate that RCC cells can recruit more T cells than non-malignant kidney cells. Using an in vitro matrigel invasion system, we found infiltrating T cells could promote RCC cells invasion via increasing ERβ expression and transcriptional activity. Mechanism dissection suggested that co-culturing T cells with RCC cells released more T cell attraction factors, including IFN-γ, CCL3 and CCL5, suggesting a positive regulatory feed-back mechanism. Meanwhile, infiltrating T cells may also promote RCC cell invasion via increased ERβ and decreased DAB2IP expressions, and knocking down DAB2IP can then reverse the T cells-promoted RCC cell invasion. Together, our results suggest that infiltrating T cells may promote RCC cell invasion via increasing the RCC cell ERβ expression to inhibit the tumor suppressor DAB2IP signals. Further mechanism dissection showed that co-culturing T cells with RCC cells could produce more IGF-1 and FGF-7, which may enhance the ERβ transcriptional activity. The newly identified relationship between infiltrating T cells/ERβ/DAB2IP signals may provide a novel therapeutic target in the development of agents against RCC.

Curtailed T-cell activation curbs effector differentiation and generates CD8+ T cells with a naturally-occurring memory stem cell phenotype.

PubMed

Zanon, Veronica; Pilipow, Karolina; Scamardella, Eloise; De Paoli, Federica; De Simone, Gabriele; Price, David A; Martinez Usatorre, Amaia; Romero, Pedro; Mavilio, Domenico; Roberto, Alessandra; Lugli, Enrico

2017-09-01

Human T memory stem (T SCM ) cells with superior persistence capacity and effector functions are emerging as important players in the maintenance of long-lived T-cell memory and are thus considered an attractive population to be used in adoptive transfer-based immunotherapy of cancer. However, the molecular signals regulating their generation remain poorly defined. Here we show that curtailed T-cell receptor stimulation curbs human effector CD8 + T-cell differentiation and allows the generation of CD45RO - CD45RA + CCR7 + CD27 + CD95 + -phenotype cells from highly purified naïve T-cell precursors, resembling naturally-occurring human T SCM . These cells proliferate extensively in vitro and in vivo, express low amounts of effector-associated genes and transcription factors and undergo considerable self-renewal in response to IL-15 while retaining effector differentiation potential. Such a phenotype is associated with a lower number of mitochondria compared to highly-activated effector T cells committed to terminal differentiation. These results shed light on the molecular signals that are required to generate long-lived memory T cells with potential application in adoptive cell transfer immunotherapy. © 2017 The Authors. European Journal of Immunology published by WILEY-VCH Verlag GmbH & Co.KGaA, Weinheim.

Homeostatic Signals do not Drive Post-thymic T cell Maturation

PubMed Central

Houston, Evan G.; Boursalian, Tamar E.; Fink, Pamela J.

2012-01-01

Recent thymic emigrants, the youngest T cells in the lymphoid periphery, undergo a 3-week-long period of functional and phenotypic maturation before being incorporated into the pool of mature, naïve T cells. Previous studies indicate that this maturation requires T cell exit from the thymus and access to secondary lymphoid organs, but is MHC-independent. We now show that post-thymic T cell maturation is independent of homeostatic and costimulatory pathways, requiring neither signals delivered by IL-7 nor CD80/86. Furthermore, while CCR7/CCL19,21-regulated homing of recent thymic emigrants to the T cell zones within the secondary lymphoid organs is not required for post-thymic T cell maturation, an intact dendritic cell compartment modulates this process. It is thus clear that, unlike T cell development and homeostasis, post-thymic maturation is focused not on interrogating the T cell receptor or the cell’s responsiveness to homeostatic or costimulatory signals, but on some as yet unrecognized property. PMID:22398309

Sympathetic neural signaling via the β2-adrenergic receptor suppresses T-cell receptor-mediated human and mouse CD8(+) T-cell effector function.

PubMed

Estrada, Leonardo D; Ağaç, Didem; Farrar, J David

2016-08-01

Postganglionic sympathetic neurons innervate secondary lymphoid organs and secrete norepinephrine (NE) as the primary neurotransmitter. NE binds and signals through five distinct members of the adrenergic receptor family. In this study, we show elevated expression of the β2-adrenergic receptor (ADRB2) on primary human CD8(+) effector memory T cells. Treatment of both human and murine CD8(+) T cells with NE decreased IFN-γ and TNF-α secretion and suppressed their cytolytic capacity in response to T-cell receptor (TCR) activation. The effects of NE were specifically reversed by β2-specific antagonists. Adrb2(-/-) CD8(+) T cells were completely resistant to the effects of NE. Further, the ADRB2-specific pharmacological ligand, albuterol, significantly suppressed effector functions in both human and mouse CD8(+) T cells. While both TCR activation and stimulation with IL-12 + IL-18 were able to induce inflammatory cytokine secretion, NE failed to suppress IFN-γ secretion in response to IL-12 + IL18. Finally, the long-acting ADRB2-specific agonist, salmeterol, markedly reduced the cytokine secretion capacity of CD8(+) T cells in response to infection with vesicular stomatitis virus. This study reveals a novel intrinsic role for ADRB2 signaling in CD8(+) T-cell function and underscores the novel role this pathway plays in adaptive T-cell responses to infection. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Profiling calcium signals of in vitro polarized human effector CD4+ T cells.

PubMed

Kircher, Sarah; Merino-Wong, Maylin; Niemeyer, Barbara A; Alansary, Dalia

2018-06-01

Differentiation of naïve CD4 + T cells into effector subtypes with distinct cytokine profiles and physiological roles is a tightly regulated process, the imbalance of which can lead to an inadequate immune response or autoimmune disease. The crucial role of Ca 2+ signals, mainly mediated by the store operated Ca 2+ entry (SOCE) in shaping the immune response is well described. However, it is unclear if human effector CD4 + T cell subsets show differential Ca 2+ signatures in response to different stimulation methods. Herein, we provide optimized in vitro culture conditions for polarization of human CD4 + effector T cells and characterize their SOCE following both pharmacological store depletion and direct T-cell receptor (TCR) activation. Moreover, we measured whole cell Ca 2+ release activated Ca 2+ currents (I CRAC ) and investigated whether the observed differences correlate to the expression of CRAC genes. Our results show that Ca 2+ profiles of helper CD4 + Th1, Th2 and Th17 are distinct and in part shaped by the intensity of stimulation. Regulatory T cells (Treg) are unique being the subtype with the most prominent SOCE response. Analysis of in vivo differentiated Treg unraveled the role of differential expression of ORAI2 in fine-tuning signals in Treg vs. conventional CD4 + T cells. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

Manipulating memory CD8 T cell numbers by timed enhancement of IL-2 signals1

PubMed Central

Kim, Marie T.; Kurup, Samarchith P.; Starbeck-Miller, Gabriel R.; Harty, John T.

2016-01-01

Due to the growing burden of tumors and chronic infections, manipulating CD8 T cell responses for clinical use has become an important goal for immunologists. Here, we show that dendritic cell (DC) immunization coupled with relatively early (days 1–3) or late (days 4–6) administration of enhanced IL-2-signals both increase peak effector CD8 T cell numbers, but only early IL-2 signals enhance memory numbers. IL-2 signals delivered at relatively late time points drive terminal differentiation, marked Bim mediated contraction and do not increase memory T cell numbers. In contrast, early IL-2 signals induce effector cell metabolic profiles more conducive to memory formation. Of note, down-regulation of CD80 and CD86 was observed on DCs in vivo following early IL-2 treatment. Mechanistically, early IL-2 treatment enhanced CTLA-4 expression on regulatory T (Treg) cells, and CTLA-4 blockade alongside IL-2 treatment in vivo prevented the decrease in CD80 and CD86, supporting a cell-extrinsic role of CTLA-4 in down-regulating B7-ligand expression on DCs. Finally, DC immunization followed by early IL-2 treatment and αCTLA-4 blockade resulted in lower memory CD8 T cell numbers compared to the DC + early IL-2 treatment group. These data suggest that curtailed signaling through the B7-CD28 co-stimulatory axis during CD8 T cell activation limits terminal differentiation and preserves memory CD8 T cell formation and thus, should be considered in future T cell vaccination strategies. PMID:27439516

The non-classical MAP kinase ERK3 controls T cell activation.

PubMed

Marquis, Miriam; Boulet, Salix; Mathien, Simon; Rousseau, Justine; Thébault, Paméla; Daudelin, Jean-François; Rooney, Julie; Turgeon, Benjamin; Beauchamp, Claudine; Meloche, Sylvain; Labrecque, Nathalie

2014-01-01

The classical mitogen-activated protein kinases (MAPKs) ERK1 and ERK2 are activated upon stimulation of cells with a broad range of extracellular signals (including antigens) allowing cellular responses to occur. ERK3 is an atypical member of the MAPK family with highest homology to ERK1/2. Therefore, we evaluated the role of ERK3 in mature T cell response. Mouse resting T cells do not transcribe ERK3 but its expression is induced in both CD4⁺ and CD8⁺ T cells following T cell receptor (TCR)-induced T cell activation. This induction of ERK3 expression in T lymphocytes requires activation of the classical MAPK ERK1 and ERK2. Moreover, ERK3 protein is phosphorylated and associates with MK5 in activated primary T cells. We show that ERK3-deficient T cells have a decreased proliferation rate and are impaired in cytokine secretion following in vitro stimulation with low dose of anti-CD3 antibodies. Our findings identify the atypical MAPK ERK3 as a new and important regulator of TCR-induced T cell activation.

STATs shape the active enhancer landscape of T cell populations.

PubMed

Vahedi, Golnaz; Takahashi, Hayato; Nakayamada, Shingo; Sun, Hong-Wei; Sartorelli, Vittorio; Kanno, Yuka; O'Shea, John J

2012-11-21

Signaling pathways are intimately involved in cellular differentiation, allowing cells to respond to their environment by regulating gene expression. Although enhancers are recognized as key elements that regulate selective gene expression, the interplay between signaling pathways and actively used enhancer elements is not clear. Here, we use CD4(+) T cells as a model of differentiation, mapping the activity of cell-type-specific enhancer elements in T helper 1 (Th1) and Th2 cells. Our data establish that STAT proteins have a major impact on the activation of lineage-specific enhancers and the suppression of enhancers associated with alternative cell fates. Transcriptome analysis further supports a functional role for enhancers regulated by STATs. Importantly, expression of lineage-defining master regulators in STAT-deficient cells fails to fully recover the chromatin signature of STAT-dependent enhancers. Thus, these findings point to a critical role of STATs as environmental sensors in dynamically molding the specialized enhancer architecture of differentiating cells. Copyright © 2012 Elsevier Inc. All rights reserved.

Homeostatic signals do not drive post-thymic T cell maturation.

PubMed

Houston, Evan G; Boursalian, Tamar E; Fink, Pamela J

2012-01-01

Recent thymic emigrants, the youngest T cells in the lymphoid periphery, undergo a 3 week-long period of functional and phenotypic maturation before being incorporated into the pool of mature, naïve T cells. Previous studies indicate that this maturation requires T cell exit from the thymus and access to secondary lymphoid organs, but is MHC-independent. We now show that post-thymic T cell maturation is independent of homeostatic and costimulatory pathways, requiring neither signals delivered by IL-7 nor CD80/86. Furthermore, while CCR7/CCL19,21-regulated homing of recent thymic emigrants to the T cell zones within the secondary lymphoid organs is not required for post-thymic T cell maturation, an intact dendritic cell compartment modulates this process. It is thus clear that, unlike T cell development and homeostasis, post-thymic maturation is focused not on interrogating the T cell receptor or the cell's responsiveness to homeostatic or costimulatory signals, but on some as yet unrecognized property. Copyright © 2012 Elsevier Inc. All rights reserved.

The phosphatase JKAP/DUSP22 inhibits T-cell receptor signalling and autoimmunity by inactivating Lck.

PubMed

Li, Ju-Pi; Yang, Chia-Yu; Chuang, Huai-Chia; Lan, Joung-Liang; Chen, Der-Yuan; Chen, Yi-Ming; Wang, Xiaohong; Chen, Alice J; Belmont, John W; Tan, Tse-Hua

2014-04-09

JNK pathway-associated phosphatase (JKAP, also known as DUSP22 or JSP-1) is a JNK activator. The in vivo role of JKAP in immune regulation remains unclear. Here we report that JKAP directly inactivates Lck by dephosphorylating tyrosine-394 residue during T-cell receptor (TCR) signalling. JKAP-knockout T cells display enhanced cell proliferation and cytokine production. JKAP-knockout mice show enhanced T-cell-mediated immune responses and are more susceptible to experimental autoimmune encephalomyelitis (EAE). In addition, the recipient mice that are adoptively transferred with JKAP-knockout T cells show exacerbated EAE symptoms. Aged JKAP-knockout mice spontaneously develop inflammation and autoimmunity. Thus, our results indicate that JKAP is an important phosphatase that inactivates Lck in the TCR signalling turn-off stage, leading to suppression of T-cell-mediated immunity and autoimmunity.

Glucose metabolism regulates T cell activation, differentiation, and functions.

PubMed

Palmer, Clovis S; Ostrowski, Matias; Balderson, Brad; Christian, Nicole; Crowe, Suzanne M

2015-01-01

The adaptive immune system is equipped to eliminate both tumors and pathogenic microorganisms. It requires a series of complex and coordinated signals to drive the activation, proliferation, and differentiation of appropriate T cell subsets. It is now established that changes in cellular activation are coupled to profound changes in cellular metabolism. In addition, emerging evidence now suggest that specific metabolic alterations associated with distinct T cell subsets may be ancillary to their differentiation and influential in their immune functions. The "Warburg effect" originally used to describe a phenomenon in which most cancer cells relied on aerobic glycolysis for their growth is a key process that sustain T cell activation and differentiation. Here, we review how different aspects of metabolism in T cells influence their functions, focusing on the emerging role of key regulators of glucose metabolism such as HIF-1α. A thorough understanding of the role of metabolism in T cell function could provide insights into mechanisms involved in inflammatory-mediated conditions, with the potential for developing novel therapeutic approaches to treat these diseases.

Decreased SAP expression in T cells from patients with SLE contributes to early signaling abnormalities and reduced IL-2 production

PubMed Central

Karampetsou, Maria P.; Comte, Denis; Kis-Toth, Katalin; Terhorst, Cox; Kyttaris, Vasileios C.; Tsokos, George C.

2016-01-01

T cells from patients with systemic lupus erythematosus (SLE) display a number of functions including increased early signaling events following engagement of the T cell receptor (TCR). Signaling lymphocytic activation molecule family (SLAMF) cell surface receptors and the X-chromosome-defined signaling lymphocytic activation molecule-associated protein (SAP) adaptor are important in the development of several immunocyte lineages and modulating immune response. Here we present evidence that SAP protein levels are decreased in T cells and in their main subsets isolated from 32 women and 3 men with SLE independently of disease activity. In SLE T cells the SAP protein is also subject to increased degradation by a caspase-3. Forced expression of SAP in SLE T cells simultaneously heightened IL-2 production, calcium (Ca2+) responses and tyrosine phosphorylation of a number of proteins. Exposure of normal T cells to SLE serum IgG, known to contain anti-CD3/TCR antibodies, resulted in SAP downregulation. We conclude that SLE T cells display reduced levels of the adaptor protein SAP probably as a result of continuous T cell activation and degradation by caspase-3. Restoration of SAP levels in SLE T cells corrects the overexcitable lupus T cell phenotype. PMID:27183584

Mitochondrial translocation of signal transducer and activator of transcription 5 (STAT5) in leukemic T cells and cytokine-stimulated cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chueh, Fu-Yu; Leong, King-Fu; Yu, Chao-Lan, E-mail: chaolan.yu@rosalindfranklin.edu

2010-11-26

Research highlights: {yields} STAT5 interacts with a mitochondrial protein PDC-E2 in a leukemic T cell line LSTRA. {yields} Tyrosine-phosphorylated STAT5, but not STAT3, is present in LSTRA mitochondria. {yields} Cytokines induce mitochondrial translocation of STAT5, but not STAT1 or STAT3. {yields} Cytokine-induced mitochondrial translocation of tyrosine-phosphorylated STAT5 is transient. {yields} Mitochondrial STAT5 binds to a putative STAT5 site in the mitochondrial DNA in vitro. -- Abstract: Signal transducers and activators of transcription (STATs) were first identified as key signaling molecules in response to cytokines. Constitutive STAT activation also has been widely implicated in oncogenesis. We analyzed STAT5-associated proteins in amore » leukemic T cell line LSTRA, which exhibits constitutive tyrosine phosphorylation and activation of STAT5. A cellular protein was found to specifically interact with STAT5 in LSTRA cells by co-immunoprecipitation. Sequencing analysis and subsequent immunoblotting confirmed the identity of this STAT5-associated protein as the E2 component of mitochondrial pyruvate dehydrogenase complex (PDC-E2). Consistent with this interaction, both subcellular fractionation and immunofluorescence microscopy revealed mitochondrial localization of STAT5 in LSTRA cells. Mitochondrial localization of tyrosine-phosphorylated STAT5 also occurred in cytokine-stimulated cells. A time course experiment further demonstrated the transient kinetics of STAT5 mitochondrial translocation after cytokine stimulation. In contrast, cytokine-induced STAT1 and STAT3 activation did not result in their translocation into mitochondria. Furthermore, we showed that mitochondrial STAT5 bound to the D-loop regulatory region of mitochondrial DNA in vitro. It suggests a potential role of STAT5 in regulating the mitochondrial genome. Proliferative metabolism toward aerobic glycolysis is well known in cancer cells as the Warburg effect and is also observed in

Decreased diacylglycerol metabolism enhances ERK activation and augments CD8+ T cell functional responses.

PubMed

Riese, Matthew J; Grewal, Jashanpreet; Das, Jayajit; Zou, Tao; Patil, Vineet; Chakraborty, Arup K; Koretzky, Gary A

2011-02-18

Modulation of T cell receptor signal transduction in CD8(+) T cells represents a novel strategy toward enhancing the immune response to tumor. Recently, levels of guanine exchange factors, RasGRP and SOS, within T cells have been shown to represent a key determinant in the regulation of the analog to the digital activation threshold of Ras. One important for regulating activation levels of RasGRP is diacylglycerol (DAG), and its levels are influenced by diacylglycerol kinase-ζ (DGKζ), which metabolizes DAG into phosphatidic acid, terminating DAG-mediated Ras signaling. We sought to determine whether DGKζ-deficient CD8(+) T cells demonstrated enhanced in vitro responses in a manner predicted by the current model of Ras activation and to evaluate whether targeting this threshold confers enhanced CD8(+) T cell responsiveness to tumor. We observed that DGKζ-deficient CD8(+) T cells conform to most predictions of the current model of how RasGRP levels influence Ras activation. But our results differ in that the EC(50) value of stimulation is not altered for any T cell receptor stimulus, a finding that suggests a further degree of complexity to how DGKζ deficiency affects signals important for Ras and ERK activation. Additionally, we found that DGKζ-deficient CD8(+) T cells demonstrate enhanced responsiveness in a subcutaneous lymphoma model, implicating the analog to a digital conversion threshold as a novel target for potential therapeutic manipulation.

IL-15 signaling promotes adoptive effector T-cell survival and memory formation in irradiation-induced lymphopenia.

PubMed

Xu, Aizhang; Bhanumathy, Kalpana Kalyanasundaram; Wu, Jie; Ye, Zhenmin; Freywald, Andrew; Leary, Scot C; Li, Rongxiu; Xiang, Jim

2016-01-01

Lymphopenia promotes naïve T-cell homeostatic proliferation and adoptive effector T-cell survival and memory formation. IL-7 plays a critical role in homeostatic proliferation, survival and memory formation of naïve T-cells in lymphopenia, and its underlying molecular mechanism has also been well studied. However, the mechanism for adoptively transferred effector T-cell survival and memory formation is not fully understood. Here, we transferred in vitro-activated transgenic OT-I CD8(+) effector T-cells into irradiation (600 rads)-induced lymphopenic C57BL/6, IL-7 knockout (KO) and IL-15 KO mice, and investigated the survival and memory formation of transferred T-cells in lymphopenia. We demonstrate that transferred T-cells prolong their survival and enhance their memory in lymphopenic mice, in a manner that depends on IL-15 signaling, but not IL-7. We determine that in vitro stimulation of naïve or effector T-cells with IL-7 and IL-15 reduces IL-7Rα, and increases and/or maintains IL-15Rβ expression, respectively. Consistent with these findings, the expression of IL-7Rα and IL-15Rβ is down- and up-regulated, respectively, in vivo on transferred T-cells in an early phase post T-cell transfer in lymphopenia. We further show that in vitro IL-15 restimulation-induced memory T-cells (compared to IL-2 restimulation-induced effector T-cells) and in vivo transferred T-cells in irradiated IL-15-sufficient C57BL/6 mice (compared to IL-15-deficient IL-15 KO mice) have increased mitochondrial content, but less NADH and lower mitochondrial potential (ΔΨm), and demonstrate greater phosphorylation of signal transducers and activators of transcription-5 (STAT5) and Unc-51-like kinase-1 (ULK1), and higher expression of B-cell leukemia/lymphoma-2 (Bcl2) and memory-, autophagy- and mitochondrial biogenesis-related molecules. Irradiation-induced lymphopenia promotes effector T-cell survival via IL-15 signaling the STAT5/Bcl2 pathway, enhances T-cell memory formation via IL

Dependence on nuclear factor of activated T-cells (NFAT) levels discriminates conventional T cells from Foxp3+ regulatory T cells

PubMed Central

Vaeth, Martin; Schliesser, Ulrike; Müller, Gerd; Reissig, Sonja; Satoh, Kazuki; Tuettenberg, Andrea; Jonuleit, Helmut; Waisman, Ari; Müller, Martin R.; Serfling, Edgar; Sawitzki, Birgit S.; Berberich-Siebelt, Friederike

2012-01-01

Several lines of evidence suggest nuclear factor of activated T-cells (NFAT) to control regulatory T cells: thymus-derived naturally occurring regulatory T cells (nTreg) depend on calcium signals, the Foxp3 gene harbors several NFAT binding sites, and the Foxp3 (Fork head box P3) protein interacts with NFAT. Therefore, we investigated the impact of NFAT on Foxp3 expression. Indeed, the generation of peripherally induced Treg (iTreg) by TGF-β was highly dependent on NFAT expression because the ability of CD4+ T cells to differentiate into iTreg diminished markedly with the number of NFAT family members missing. It can be concluded that the expression of Foxp3 in TGF-β–induced iTreg depends on the threshold value of NFAT rather than on an individual member present. This is specific for iTreg development, because frequency of nTreg remained unaltered in mice lacking NFAT1, NFAT2, or NFAT4 alone or in combination. Different from expectation, however, the function of both nTreg and iTreg was independent on robust NFAT levels, reflected by less nuclear NFAT in nTreg and iTreg. Accordingly, absence of one or two NFAT members did not alter suppressor activity in vitro or during colitis and transplantation in vivo. This scenario emphasizes an inhibition of high NFAT activity as treatment for autoimmune diseases and in transplantation, selectively targeting the proinflammatory conventional T cells, while keeping Treg functional. PMID:22991461

T cell resistance to activation by dendritic cells requires long-term culture in simulated microgravity

NASA Astrophysics Data System (ADS)

Bradley, Jillian H.; Stein, Rachel; Randolph, Brad; Molina, Emily; Arnold, Jennifer P.; Gregg, Randal K.

2017-11-01

Immune impairment mediated by microgravity threatens the success of space exploration requiring long-duration spaceflight. The cells of most concern, T lymphocytes, coordinate the host response against microbial and cancerous challenges leading to elimination and long-term protection. T cells are activated upon recognition of specific microbial peptides bound on the surface of antigen presenting cells, such as dendritic cells (DC). Subsequently, this engagement results in T cell proliferation and differentiation into effector T cells driven by autocrine interleukin-2 (IL-2) and other cytokines. Finally, the effector T cells acquire the weaponry needed to destroy microbial invaders and tumors. Studies conducted on T cells during spaceflight, or using Earth-based culture systems, have shown reduced production of cytokines, proliferation and effector functions as compared to controls. This may account for the cases of viral reactivation events and opportunistic infections associated with astronauts of numerous missions. This work has largely been based upon the outcome of T cell activation by stimulatory factors that target select T cell signaling pathways rather than the complex, signaling events related to the natural process of antigen presentation by DC. This study tested the response of an ovalbumin peptide-specific T cell line, OT-II TCH, to activation by DC when the T cells were cultured 24-120 h in a simulated microgravity (SMG) environment generated by a rotary cell culture system. Following 72 h culture of T cells in SMG (SMG-T) or control static (Static-T) conditions, IL-2 production by the T cells was reduced in SMG-T cells compared to Static-T cells upon stimulation by phorbol 12-myristate 13-acetate (PMA) and ionomycin. However, when the SMG-T cells were stimulated with DC and peptide, IL-2 was significantly increased compared to Static-T cells. Such enhanced IL-2 production by SMG-T cells peaked at 72 h SMG culture time and decreased thereafter. When

IFNγ Signaling Endows DCs with the Capacity to Control Type I Inflammation during Parasitic Infection through Promoting T-bet+ Regulatory T Cells

PubMed Central

Lee, Hyang-Mi; Fleige, Anne; Forman, Ruth; Cho, Sunglim; Khan, Aly Azeem; Lin, Ling-Li; Nguyen, Duc T.; O'Hara-Hall, Aisling; Yin, Zhinan; Hunter, Christopher A.; Muller, Werner; Lu, Li-Fan

2015-01-01

IFNγ signaling drives dendritic cells (DCs) to promote type I T cell (Th1) immunity. Here, we show that activation of DCs by IFNγ is equally crucial for the differentiation of a population of T-bet+ regulatory T (Treg) cells specialized to inhibit Th1 immune responses. Conditional deletion of IFNγ receptor in DCs but not in Treg cells resulted in a severe defect in this specific Treg cell subset, leading to exacerbated immune pathology during parasitic infections. Mechanistically, IFNγ-unresponsive DCs failed to produce sufficient amount of IL-27, a cytokine required for optimal T-bet induction in Treg cells. Thus, IFNγ signalling endows DCs with the ability to efficiently control a specific type of T cell immunity through promoting a corresponding Treg cell population. PMID:25658840

LYSOPHOSPHATIDIC ACID INHIBITS CD8 T CELL ACTIVATION AND CONTROL OF TUMOR PROGRESSION

PubMed Central

Oda, Shannon K.; Strauch, Pamela; Fujiwara, Yuko; Al-Shami, Amin; Oravecz, Tamas; Tigyi, Gabor; Pelanda, Roberta; Torres, Raul M.

2013-01-01

CD8 T lymphocytes are able to eliminate nascent tumor cells through a process referred to as immune surveillance. However, multiple inhibitory mechanisms within the tumor microenvironment have been described that impede tumor rejection by CD8 T cells, including increased signaling by inhibitory receptors. Lysophosphatidic acid (LPA) is a bioactive lysophospholipid that has been shown repeatedly to promote diverse cellular processes benefiting tumorigenesis. Accordingly, the increased expression of LPA and LPA receptors is a common feature of diverse tumor cell lineages and can result in elevated systemic LPA levels. LPA is recognized by at least 6 distinct G-protein-coupled receptors and several of which are expressed by T cells, although the precise role of LPA signaling in CD8 T cell activation and function has not been defined. Here, we demonstrate that LPA signaling via the LPA5 receptor expressed by CD8 T cells suppresses antigen receptor signaling, cell activation and proliferation in vitro and in vivo. Importantly, in a mouse melanoma model tumor-specific CD8 T cells that are LPA5-deficient are able to control tumor growth significantly better than wild-type tumor-specific CD8 T cells. Together, these data suggest that the production of LPA by tumors serves not only in an autocrine manner to promote tumorigenesis but also as a mechanism to suppress adaptive immunity and highlights a potential novel target for cancer treatment. PMID:24455753

TLR4 signaling in effector CD4+ T cells regulates TCR activation and experimental colitis in mice

PubMed Central

González-Navajas, José M.; Fine, Sean; Law, Jason; Datta, Sandip K.; Nguyen, Kim P.; Yu, Mandy; Corr, Maripat; Katakura, Kyoko; Eckman, Lars; Lee, Jongdae; Raz, Eyal

2010-01-01

TLRs sense various microbial products. Their function has been best characterized in DCs and macrophages, where they act as important mediators of innate immunity. TLR4 is also expressed on CD4+ T cells, but its physiological function on these cells remains unknown. Here, we have shown that TLR4 triggering on CD4+ T cells affects their phenotype and their ability to provoke intestinal inflammation. In a model of spontaneous colitis, Il10–/–Tlr4–/– mice displayed accelerated development of disease, with signs of overt colitis as early as 8 weeks of age, when compared with Il10–/– and Il10–/–Tlr9–/– mice, which did not develop colitis by 8 months. Similar results were obtained in a second model of colitis in which transfer of naive Il10–/–Tlr4–/– CD4+ T cells into Rag1–/– recipients sufficient for both IL-10 and TLR4 induced more aggressive colitis than the transfer of naive Il10–/– CD4+ T cells. Mechanistically, LPS stimulation of TLR4-bearing CD4+ T cells inhibited ERK1/2 activation upon subsequent TCR stimulation via the induction of MAPK phosphatase 3 (MKP-3). Our data therefore reveal a tonic inhibitory role for TLR4 signaling on subsequent TCR-dependent CD4+ T cell responses. PMID:20051628

Tethered IL-15 augments antitumor activity and promotes a stem-cell memory subset in tumor-specific T cells.

PubMed

Hurton, Lenka V; Singh, Harjeet; Najjar, Amer M; Switzer, Kirsten C; Mi, Tiejuan; Maiti, Sourindra; Olivares, Simon; Rabinovich, Brian; Huls, Helen; Forget, Marie-Andrée; Datar, Vrushali; Kebriaei, Partow; Lee, Dean A; Champlin, Richard E; Cooper, Laurence J N

2016-11-29

Adoptive immunotherapy retargeting T cells to CD19 via a chimeric antigen receptor (CAR) is an investigational treatment capable of inducing complete tumor regression of B-cell malignancies when there is sustained survival of infused cells. T-memory stem cells (T SCM ) retain superior potential for long-lived persistence, but challenges exist in manufacturing this T-cell subset because they are rare among circulating lymphocytes. We report a clinically relevant approach to generating CAR + T cells with preserved T SCM potential using the Sleeping Beauty platform. Because IL-15 is fundamental to T-cell memory, we incorporated its costimulatory properties by coexpressing CAR with a membrane-bound chimeric IL-15 (mbIL15). The mbIL15-CAR T cells signaled through signal transducer and activator of transcription 5 to yield improved T-cell persistence independent of CAR signaling, without apparent autonomous growth or transformation, and achieved potent rejection of CD19 + leukemia. Long-lived T cells were CD45RO neg CCR7 + CD95 + , phenotypically most similar to T SCM , and possessed a memory-like transcriptional profile. Overall, these results demonstrate that CAR + T cells can develop long-term persistence with a memory stem-cell phenotype sustained by signaling through mbIL15. This observation warrants evaluation in clinical trials.

The mediator subunit Med23 contributes to controlling T-cell activation and prevents autoimmunity.

PubMed

Sun, Yang; Zhu, Xiaoyan; Chen, Xufeng; Liu, Haifeng; Xu, Yu; Chu, Yajing; Wang, Gang; Liu, Xiaolong

2014-10-10

T-cell activation is critical for successful immune responses and is controlled at multiple levels. Although many changes of T-cell receptor-associated signalling molecules affect T-cell activation, the transcriptional mechanisms that control this process remain largely unknown. Here we find that T cell-specific deletion of the mediator subunit Med23 leads to hyperactivation of T cells and aged Med23-deficient mice exhibit an autoimmune syndrome. Med23 specifically and consistently promotes the transcription of multiple negative regulators of T-cell activation. In the absence of Med23, the T-cell activation threshold is lower, which results in enhanced antitumour T-cell function. Cumulatively, our data suggest that Med23 contributes to controlling T-cell activation at the transcriptional level and prevents the development of autoimmunity.

CD6 and Linker of Activated T Cells are Potential Interaction Partners for T Cell-Specific Adaptor Protein.

PubMed

Hem, C D; Ekornhol, M; Granum, S; Sundvold-Gjerstad, V; Spurkland, A

2017-02-01

The T cell-specific adaptor protein (TSAd) contains several protein interaction domains, and is merging as a modulator of T cell activation. Several interaction partners for the TSAd proline-rich region and phosphotyrosines have been identified, including the Src and Tec family kinases lymphocyte-specific protein tyrosine kinase and interleukin 2-inducible T cell kinase. Via its Src homology 2 (SH2) domain, TSAd may thus function as a link between these enzymes and other signalling molecules. However, few binding partners to the TSAd SH2 domain in T cells are hitherto known. Through the use of in silico ligand prediction, peptide spot arrays, pull-down and immunoprecipitation experiments, we here report novel interactions between the TSAd SH2 domain and CD6 phosphotyrosine (pTyr) 629 and linker of activated T cells (LAT) pTyr 171 , pTyr 191 and pTyr 226 . © 2016 The Foundation for the Scandinavian Journal of Immunology.

T cell resistance to activation by dendritic cells requires long-term culture in simulated microgravity.

PubMed

Bradley, Jillian H; Stein, Rachel; Randolph, Brad; Molina, Emily; Arnold, Jennifer P; Gregg, Randal K

2017-11-01

Immune impairment mediated by microgravity threatens the success of space exploration requiring long-duration spaceflight. The cells of most concern, T lymphocytes, coordinate the host response against microbial and cancerous challenges leading to elimination and long-term protection. T cells are activated upon recognition of specific microbial peptides bound on the surface of antigen presenting cells, such as dendritic cells (DC). Subsequently, this engagement results in T cell proliferation and differentiation into effector T cells driven by autocrine interleukin-2 (IL-2) and other cytokines. Finally, the effector T cells acquire the weaponry needed to destroy microbial invaders and tumors. Studies conducted on T cells during spaceflight, or using Earth-based culture systems, have shown reduced production of cytokines, proliferation and effector functions as compared to controls. This may account for the cases of viral reactivation events and opportunistic infections associated with astronauts of numerous missions. This work has largely been based upon the outcome of T cell activation by stimulatory factors that target select T cell signaling pathways rather than the complex, signaling events related to the natural process of antigen presentation by DC. This study tested the response of an ovalbumin peptide-specific T cell line, OT-II TCH, to activation by DC when the T cells were cultured 24-120 h in a simulated microgravity (SMG) environment generated by a rotary cell culture system. Following 72 h culture of T cells in SMG (SMG-T) or control static (Static-T) conditions, IL-2 production by the T cells was reduced in SMG-T cells compared to Static-T cells upon stimulation by phorbol 12-myristate 13-acetate (PMA) and ionomycin. However, when the SMG-T cells were stimulated with DC and peptide, IL-2 was significantly increased compared to Static-T cells. Such enhanced IL-2 production by SMG-T cells peaked at 72 h SMG culture time and decreased thereafter

In the absence of its cytosolic domain, the CD28 molecule still contributes to T cell activation

PubMed Central

Morin, Stéphanie; Giroux, Valentin; Favre, Cédric; Bechah, Yassina; Auphan-Anezin, Nathalie; Roncagalli, Romain; Mège, Jean-Louis; Olive, Daniel; Malissen, Marie; Nunes, Jacques

2015-01-01

The CD28 costimulatory receptor has a pivotal role in T cell biology as this molecule amplifies T cell receptor (TCR) signals to provide an efficient immune T cell response. There is a large debate about how CD28 mediates these signals. Here, we designed a CD28 gene targeted knock-in mouse strain lacking the cytoplasmic tail of CD28. As is the case in CD28-deficient (CD28 knock-out) mice, regulatory T cell homeostasis and T cell activation are altered in these CD28 knock-in mice. Unexpectedly, the presence of a CD28 molecule deprived of its cytoplasmic tail could partially induce some early activation events in T cells such as signaling events or expression of early activation markers. These results unravel a new mechanism of T cell costimulation by CD28, independent of its cytoplasmic tail. PMID:25725801

From the outside, from within: Biological and therapeutic relevance of signal transduction in T-cell acute lymphoblastic leukemia.

PubMed

Oliveira, Mariana L; Akkapeddi, Padma; Alcobia, Isabel; Almeida, Afonso R; Cardoso, Bruno A; Fragoso, Rita; Serafim, Teresa L; Barata, João T

2017-10-01

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological cancer that arises from clonal expansion of transformed T-cell precursors. In this review we summarize the current knowledge on the external stimuli and cell-intrinsic lesions that drive aberrant activation of pivotal, pro-tumoral intracellular signaling pathways in T-cell precursors, driving transformation, leukemia expansion, spread or resistance to therapy. In addition to their pathophysiological relevance, receptors and kinases involved in signal transduction are often attractive candidates for targeted drug development. As such, we discuss also the potential of T-ALL signaling players as targets for therapeutic intervention. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Constitutive Lck Activity Drives Sensitivity Differences between CD8+ Memory T Cell Subsets.

PubMed

Moogk, Duane; Zhong, Shi; Yu, Zhiya; Liadi, Ivan; Rittase, William; Fang, Victoria; Dougherty, Janna; Perez-Garcia, Arianne; Osman, Iman; Zhu, Cheng; Varadarajan, Navin; Restifo, Nicholas P; Frey, Alan B; Krogsgaard, Michelle

2016-07-15

CD8(+) T cells develop increased sensitivity following Ag experience, and differences in sensitivity exist between T cell memory subsets. How differential TCR signaling between memory subsets contributes to sensitivity differences is unclear. We show in mouse effector memory T cells (TEM) that >50% of lymphocyte-specific protein tyrosine kinase (Lck) exists in a constitutively active conformation, compared with <20% in central memory T cells (TCM). Immediately proximal to Lck signaling, we observed enhanced Zap-70 phosphorylation in TEM following TCR ligation compared with TCM Furthermore, we observed superior cytotoxic effector function in TEM compared with TCM, and we provide evidence that this results from a lower probability of TCM reaching threshold signaling owing to the decreased magnitude of TCR-proximal signaling. We provide evidence that the differences in Lck constitutive activity between CD8(+) TCM and TEM are due to differential regulation by SH2 domain-containing phosphatase-1 (Shp-1) and C-terminal Src kinase, and we use modeling of early TCR signaling to reveal the significance of these differences. We show that inhibition of Shp-1 results in increased constitutive Lck activity in TCM to levels similar to TEM, as well as increased cytotoxic effector function in TCM Collectively, this work demonstrates a role for constitutive Lck activity in controlling Ag sensitivity, and it suggests that differential activities of TCR-proximal signaling components may contribute to establishing the divergent effector properties of TCM and TEM. This work also identifies Shp-1 as a potential target to improve the cytotoxic effector functions of TCM for adoptive cell therapy applications. Copyright © 2016 by The American Association of Immunologists, Inc.

Visualization of Cytolytic T Cell Differentiation and Granule Exocytosis with T Cells from Mice Expressing Active Fluorescent Granzyme B

PubMed Central

Mouchacca, Pierre; Schmitt-Verhulst, Anne-Marie; Boyer, Claude

2013-01-01

To evaluate acquisition and activation of cytolytic functions during immune responses we generated knock in (KI) mice expressing Granzyme B (GZMB) as a fusion protein with red fluorescent tdTomato (GZMB-Tom). As for GZMB in wild type (WT) lymphocytes, GZMB-Tom was absent from naïve CD8 and CD4 T cells in GZMB-Tom-KI mice. It was rapidly induced in most CD8 T cells and in a subpopulation of CD4 T cells in response to stimulation with antibodies to CD3/CD28. A fraction of splenic NK cells expressed GZMB-Tom ex vivo with most becoming positive upon culture in IL-2. GZMB-Tom was present in CTL granules and active as a protease when these degranulated into cognate target cells, as shown with target cells expressing a specific FRET reporter construct. Using T cells from mice expressing GZMB-Tom but lacking perforin, we show that the transfer of fluorescent GZMB-Tom into target cells was dependent on perforin, favoring a role for perforin in delivery of GZMB at the target cells’ plasma membranes. Time-lapse video microscopy showed Ca++ signaling in CTL upon interaction with cognate targets, followed by relocalization of GZMB-Tom-containing granules to the synaptic contact zone. A perforin-dependent step was next visualized by the fluorescence signal from the non-permeant dye TO-PRO-3 at the synaptic cleft, minutes before the labeling of the target cell nucleus, characterizing a previously undescribed synaptic event in CTL cytolysis. Transferred OVA-specific GZMB-Tom-expressing CD8 T cells acquired GZMB-Tom expression in Listeria monocytogenes-OVA infected mice as soon as 48h after infection. These GZMB-Tom positive CD8 T cells localized in the splenic T-zone where they interacted with CD11c positive dendritic cells (DC), as shown by GZMB-Tom granule redistribution to the T/DC contact zone. GZMB-Tom-KI mice thus also provide tools to visualize acquisition and activation of cytolytic function in vivo. PMID:23840635

HIV-1 Nef limits communication between linker of activated T cells and SLP-76 to reduce formation of SLP-76-signaling microclusters following TCR stimulation.

PubMed

Abraham, Libin; Bankhead, Peter; Pan, Xiaoyu; Engel, Ulrike; Fackler, Oliver T

2012-08-15

Signal initiation by engagement of the TCR triggers actin rearrangements, receptor clustering, and dynamic organization of signaling complexes to elicit and sustain downstream signaling. Nef, a pathogenicity factor of HIV, disrupts early TCR signaling in target T cells. To define the mechanism underlying this Nef-mediated signal disruption, we employed quantitative single-cell microscopy following surface-mediated TCR stimulation that allows for dynamic visualization of distinct signaling complexes as microclusters (MCs). Despite marked inhibition of actin remodeling and cell spreading, the induction of MCs containing TCR-CD3 or ZAP70 was not affected significantly by Nef. However, Nef potently inhibited the subsequent formation of MCs positive for the signaling adaptor Src homology-2 domain-containing leukocyte protein of 76 kDa (SLP-76) to reduce MC density in Nef-expressing and HIV-1-infected T cells. Further analyses suggested that Nef prevents formation of SLP-76 MCs at the level of the upstream adaptor protein, linker of activated T cells (LAT), that couples ZAP70 to SLP-76. Nef did not disrupt pre-existing MCs positive for LAT. However, the presence of the viral protein prevented de novo recruitment of active LAT into MCs due to retargeting of LAT to an intracellular compartment. These modulations in MC formation and composition depended on Nef's ability to simultaneously disrupt both actin remodeling and subcellular localization of TCR-proximal machinery. Nef thus employs a dual mechanism to disturb early TCR signaling by limiting the communication between LAT and SLP-76 and preventing the dynamic formation of SLP-76-signaling MCs.

Transcriptomic analysis of mouse EL4 T cells upon T cell activation and in response to protein synthesis inhibition via cycloheximide treatment.

PubMed

Lim, Pek Siew; Hardy, Kristine; Peng, Kaiman; Shannon, Frances M

2016-03-01

T cell activation involves the recognition of a foreign antigen complexed to the major histocompatibility complex on the antigen presenting T cell to the T cell receptor. This leads to activation of signaling pathways, which ultimately leads to induction of key cytokine genes responsible for eradication of foreign antigens. We used the mouse EL4 T cell as a model system to study genes that are induced as a result of T cell activation using phorbol myristate acetate (PMA) and calcium ionomycin (I) as stimuli. We were also interested to examine the importance of new protein synthesis in regulating the expression of genes involved in T cell activation. Thus we have pre-treated mouse EL4 T cells with cycloheximide, a protein synthesis inhibitor, and left the cells unstimulated or stimulated with PMA/I for 4 h. We performed microarray expression profiling of these cells to correlate the gene expression with chromatin state of T cells upon T cell activation [1]. Here, we detail further information and analysis of the microarray data, which shows that T cell activation leads to differential expression of genes and inducible genes can be further classified as primary and secondary response genes based on their protein synthesis dependency. The data is available in the Gene Expression Omnibus under accession number GSE13278.

Activation Loop Dynamics Determine the Different Catalytic Efficiencies of B Cell- and T Cell-Specific Tec Kinases

PubMed Central

Joseph, Raji E.; Kleino, Iivari; Wales, Thomas E.; Xie, Qian; Fulton, D. Bruce; Engen, John R.; Berg, Leslie J.; Andreotti, Amy H.

2014-01-01

Itk and Btk are nonreceptor tyrosine kinases of the Tec family that signal downstream of the T cell receptor (TCR) and B cell receptor (BCR), respectively. Despite their high sequence similarity and related signaling roles, Btk is a substantially more active kinase than Itk. We showed that substitution of six of the 619 amino acid residues of Itk with those of Btk was sufficient to completely switch the activities of Itk and Btk. The substitutions responsible for the swap in activity are all localized to the activation segment of the kinase domain. Nuclear magnetic resonance and hydrogen-deuterium exchange mass spectrometry analyses revealed that Itk and Btk had distinct protein dynamics in this region, which could explain the observed differences in catalytic efficiency between these kinases. Introducing Itk with enhanced activity into T cells led to enhanced and prolonged TCR signaling compared to that in cells with wild-type Itk. These findings imply that evolutionary pressures have led to Tec kinases having distinct enzymatic properties depending on the cellular context. We suggest that the weaker catalytic activities observed for T cell–specific kinases is one mechanism to regulate cellular activation and prevent aberrant immune responses. PMID:23982207

Tethered IL-15 augments antitumor activity and promotes a stem-cell memory subset in tumor-specific T cells

PubMed Central

Hurton, Lenka V.; Singh, Harjeet; Najjar, Amer M.; Switzer, Kirsten C.; Mi, Tiejuan; Maiti, Sourindra; Olivares, Simon; Rabinovich, Brian; Huls, Helen; Forget, Marie-Andrée; Datar, Vrushali; Kebriaei, Partow; Lee, Dean A.; Champlin, Richard E.; Cooper, Laurence J. N.

2016-01-01

Adoptive immunotherapy retargeting T cells to CD19 via a chimeric antigen receptor (CAR) is an investigational treatment capable of inducing complete tumor regression of B-cell malignancies when there is sustained survival of infused cells. T-memory stem cells (TSCM) retain superior potential for long-lived persistence, but challenges exist in manufacturing this T-cell subset because they are rare among circulating lymphocytes. We report a clinically relevant approach to generating CAR+ T cells with preserved TSCM potential using the Sleeping Beauty platform. Because IL-15 is fundamental to T-cell memory, we incorporated its costimulatory properties by coexpressing CAR with a membrane-bound chimeric IL-15 (mbIL15). The mbIL15-CAR T cells signaled through signal transducer and activator of transcription 5 to yield improved T-cell persistence independent of CAR signaling, without apparent autonomous growth or transformation, and achieved potent rejection of CD19+ leukemia. Long-lived T cells were CD45ROnegCCR7+CD95+, phenotypically most similar to TSCM, and possessed a memory-like transcriptional profile. Overall, these results demonstrate that CAR+ T cells can develop long-term persistence with a memory stem-cell phenotype sustained by signaling through mbIL15. This observation warrants evaluation in clinical trials. PMID:27849617

Requirements of transcription factor Smad-dependent and -independent TGF-β signaling to control discrete T-cell functions.

PubMed

Gu, Ai-Di; Wang, Yunqi; Lin, Lin; Zhang, Song S; Wan, Yisong Y

2012-01-17

TGF-β modulates immune response by suppressing non-regulatory T (Treg) function and promoting Treg function. The question of whether TGF-β achieves distinct effects on non-Treg and Treg cells through discrete signaling pathways remains outstanding. In this study, we investigated the requirements of Smad-dependent and -independent TGF-β signaling for T-cell function. Smad2 and Smad3 double deficiency in T cells led to lethal inflammatory disorder in mice. Non-Treg cells were spontaneously activated and produced effector cytokines in vivo on deletion of both Smad2 and Smad3. In addition, TGF-β failed to suppress T helper differentiation efficiently and to promote induced Treg generation of non-Treg cells lacking both Smad2 and Smad3, suggesting that Smad-dependent signaling is obligatory to mediate TGF-β function in non-Treg cells. Unexpectedly, however, the development, homeostasis, and function of Treg cells remained intact in the absence of Smad2 and Smad3, suggesting that the Smad-independent pathway is important for Treg function. Indeed, Treg-specific deletion of TGF-β-activated kinase 1 led to failed Treg homeostasis and lethal immune disorder in mice. Therefore, Smad-dependent and -independent TGF-β signaling discretely controls non-Treg and Treg function to modulate immune tolerance and immune homeostasis.

The calcium feedback loop and T cell activation: how cytoskeleton networks control intracellular calcium flux.

PubMed

Joseph, Noah; Reicher, Barak; Barda-Saad, Mira

2014-02-01

During T cell activation, the engagement of a T cell with an antigen-presenting cell (APC) results in rapid cytoskeletal rearrangements and a dramatic increase of intracellular calcium (Ca(2+)) concentration, downstream to T cell antigen receptor (TCR) ligation. These events facilitate the organization of an immunological synapse (IS), which supports the redistribution of receptors, signaling molecules and organelles towards the T cell-APC interface to induce downstream signaling events, ultimately supporting T cell effector functions. Thus, Ca(2+) signaling and cytoskeleton rearrangements are essential for T cell activation and T cell-dependent immune response. Rapid release of Ca(2+) from intracellular stores, e.g. the endoplasmic reticulum (ER), triggers the opening of Ca(2+) release-activated Ca(2+) (CRAC) channels, residing in the plasma membrane. These channels facilitate a sustained influx of extracellular Ca(2+) across the plasma membrane in a process termed store-operated Ca(2+) entry (SOCE). Because CRAC channels are themselves inhibited by Ca(2+) ions, additional factors are suggested to enable the sustained Ca(2+) influx required for T cell function. Among these factors, we focus here on the contribution of the actin and microtubule cytoskeleton. The TCR-mediated increase in intracellular Ca(2+) evokes a rapid cytoskeleton-dependent polarization, which involves actin cytoskeleton rearrangements and microtubule-organizing center (MTOC) reorientation. Here, we review the molecular mechanisms of Ca(2+) flux and cytoskeletal rearrangements, and further describe the way by which the cytoskeletal networks feedback to Ca(2+) signaling by controlling the spatial and temporal distribution of Ca(2+) sources and sinks, modulating TCR-dependent Ca(2+) signals, which are required for an appropriate T cell response. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters

The T cell STAT signaling network is reprogrammed within hours of bacteremia via secondary signals1

PubMed Central

Hotson, Andrew N.; Hardy, Jonathan W.; Hale, Matthew B.; Contag, Christopher H.; Nolan, Garry P.

2014-01-01

The delicate balance between protective immunity and inflammatory disease is challenged during sepsis, a pathologic state characterized by aspects of both a hyper-active immune response and immunosuppression. The events driven by systemic infection by bacterial pathogens on the T cell signaling network that likely control these responses have not been illustrated in great detail. We characterized how intracellular signaling within the immune compartment is reprogrammed at the single cell level when the host is challenged with a high levels of pathogen. To accomplish this, we applied flow cytometry to measure the phosphorylation potential of key signal transduction proteins during acute bacterial challenge. We modeled the onset of sepsis by intravenous administration of avirulent strains of Listeria and E. coli to mice. Within six hours of bacterial challenge, T cells were globally restricted in their ability to respond to specific cytokine stimulations as determined by assessing the extent of STAT protein phosphorylation. Mechanisms by which this negative feedback response occurred included SOCS1 and SOCS3 gene up regulation and IL-6 induced endocystosis of the IL-6 receptor. In addition, macrophages were partially tolerized in their ability to respond to TLR agonists. Thus, in contrast to the view that there is a wholesale immune activation during sepsis, one immediate host response to blood borne bacteria was induction of a refractory period during which leukocyte activation by specific stimulations was attenuated. PMID:19494279

Involvement of Semaphorin (Sema4D) in T-Dependent Activation of B Cells.

PubMed

Kuklina, Е М; Nekrasova, I V; Valieva, Yu V

2017-08-01

The involvement of endogenous semaphorin (Sema4D) into the key stage of T-dependent differentiation of B cells, formation of plasmoblasts, was demonstrated in vitro in T/B cell co-culture under conditions of polyclonal activation of T cells. The effect of semaphorin was not associated with activation of high-affinity Sema4D receptor plexin B1, but involves lowaffinity receptor CD72. These data indicate that Sema4D-dependent signal regulates not only the initial stage of B-cell activation, proliferative response to the antigen, but also further differentiation of B cells into plasma cells.

Phosphoproteomics analyses show subnetwork systems in T-cell receptor signaling.

PubMed

Hatano, Atsushi; Matsumoto, Masaki; Nakayama, Keiichi I

2016-10-01

A key issue in the study of signal transduction is how multiple signaling pathways are systematically integrated into the cell. We have now performed multiple phosphoproteomics analyses focused on the dynamics of the T-cell receptor (TCR) signaling network and its subsystem mediated by the Ca 2+ signaling pathway. Integration of these phosphoproteomics data sets and extraction of components of the TCR signaling network dependent on Ca 2+ signaling showed unexpected phosphorylation kinetics for candidate substrates of the Ca 2+ -dependent phosphatase calcineurin (CN) during TCR stimulation. Detailed characterization of the TCR-induced phosphorylation of a novel CN substrate, Itpkb, showed that phosphorylation of this protein is regulated by both CN and the mitogen-activated protein kinase Erk in a competitive manner. Phosphorylation of additional CN substrates was also found to be regulated by Erk and CN in a similar manner. The combination of multiple phosphoproteomics approaches thus showed two major subsystems mediated by Erk and CN in the TCR signaling network, with these subsystems regulating the phosphorylation of a group of proteins in a competitive manner. © 2016 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.

T cell receptor–induced phosphoinositide-3-kinase p110δ activity is required for T cell localization to antigenic tissue in mice

PubMed Central

Jarmin, Sarah J.; David, Rachel; Ma, Liang; Chai, Jan-Guo; Dewchand, Hamlata; Takesono, Aya; Ridley, Anne J.; Okkenhaug, Klaus; Marelli-Berg, Federica M.

2008-01-01

The establishment of T cell–mediated inflammation requires the migration of primed T lymphocytes from the blood stream and their retention in antigenic sites. While naive T lymphocyte recirculation in the lymph and blood is constitutively regulated and occurs in the absence of inflammation, the recruitment of primed T cells to nonlymphoid tissue and their retention at the site are enhanced by various inflammatory signals, including TCR engagement by antigen-displaying endothelium and resident antigen-presenting cells. In this study, we investigated whether signals downstream of TCR ligation mediated by the phosphoinositide-3-kinase (PI3K) subunit p110δ contributed to the regulation of these events. T lymphocytes from mice expressing catalytically inactive p110δ displayed normal constitutive trafficking and migratory responses to nonspecific stimuli. However, these cells lost susceptibility to TCR-induced migration and failed to localize efficiently to antigenic tissue. Importantly, we showed that antigen-induced T cell trafficking and subsequent inflammation was abrogated by selective pharmacological inhibition of PI3K p110δ activity. These observations suggest that pharmacological targeting of p110δ activity is a viable strategy for the therapy of T cell–mediated pathology. PMID:18259608

Decreased SAP Expression in T Cells from Patients with Systemic Lupus Erythematosus Contributes to Early Signaling Abnormalities and Reduced IL-2 Production.

PubMed

Karampetsou, Maria P; Comte, Denis; Kis-Toth, Katalin; Terhorst, Cox; Kyttaris, Vasileios C; Tsokos, George C

2016-06-15

T cells from patients with systemic lupus erythematosus (SLE) display a number of abnormalities, including increased early signaling events following engagement of the TCR. Signaling lymphocytic activation molecule family cell surface receptors and the X-chromosome-defined signaling lymphocytic activation molecule-associated protein (SAP) adaptor are important in the development of several immunocyte lineages and modulating the immune response. We present evidence that SAP protein levels are decreased in T cells and in their main subsets isolated from 32 women and three men with SLE, independent of disease activity. In SLE T cells, SAP protein is also subject to increased degradation by caspase-3. Forced expression of SAP in SLE T cells normalized IL-2 production, calcium (Ca(2+)) responses, and tyrosine phosphorylation of a number of proteins. Exposure of normal T cells to SLE serum IgG, known to contain anti-CD3/TCR Abs, resulted in SAP downregulation. We conclude that SLE T cells display reduced levels of the adaptor protein SAP, probably as a result of continuous T cell activation and degradation by caspase-3. Restoration of SAP levels in SLE T cells corrects the overexcitable lupus T cell phenotype. Copyright © 2016 by The American Association of Immunologists, Inc.

Identification of a G protein coupled receptor induced in activated T cells.

PubMed

Kaplan, M H; Smith, D I; Sundick, R S

1993-07-15

Many genes are induced after T cell activation to make a cell competent for proliferation and ultimately, function. Many of these genes encode surface receptors for growth factors that signal a cell to proliferate. We have cloned a novel gene (clone 6H1) that codes for a member of the G protein-coupled receptor superfamily. This gene was isolated from a chicken activated T cell cDNA library by low level hybridization to mammalian IL-2 cDNA probes. The 308 amino acid open reading frame has seven hydrophobic, presumably transmembrane domains and a consensus site for interaction with G proteins. Tissue distribution studies suggest that gene expression is restricted to activated T cells. The message appears by 1 h after activation and is maintained for at least 45 h. Transcription of 6H1 is induced by a number of T cell stimuli and is inhibited by cyclosporin A, but not by cycloheximide. This is the first description of a member of this superfamily expressed specifically in activated T cells. The gene product may provide a link between T cell growth factors and G protein activation.

Ghrelin Inhibits the Differentiation of T Helper 17 Cells through mTOR/STAT3 Signaling Pathway

PubMed Central

Xu, Yanhui; Li, Ziru; Yin, Yue; Lan, He; Wang, Jun; Zhao, Jing; Feng, Juan; Li, Yin; Zhang, Weizhen

2015-01-01

Enhanced activity of interleukin 17 (IL-17) producing T helper 17 (Th17) cells plays an important role in autoimmune and inflammatory diseases. Significant loss of body weight and appetite is associated with chronic inflammation and immune activation, suggesting the cross talk between immune and neuroendocrine systems. Ghrelin has been shown to regulate the organism immune function. However, the effects of ghrelin on the differentiation of Th17 cells remain elusive. In the present study, we observed the enhanced differentiation of Th17 cells in spleens of growth hormone secretagogue receptor 1a (GHSR1a)-/- mice. Treatment of ghrelin repressed Th17 cell differentiation in a time- and concentration-dependent manner. Phosphorylation of mammalian target of rapamycin (mTOR) and signal transducer and activator of transcription 3 (STAT3) was increased in the spleens of GHSR1a-/- mice. Activation of mTOR signaling by injection of Cre-expressiong adenovirus into tuberous sclerosis complex 1 (TSC1) loxp/loxp mice increased the differentiation of Th17 cells in spleen, which was associated with an increment in the phosphorylation of STAT3. Activation of mTOR signaling by leucine or overexpression of p70 ribosome protein subunit 6 kinase 1 (S6K1) activated mTOR signaling in isolated T cells, while reversed the ghrelin-induced inhibition of iTh17 cell differentiation. In conclusion, mTOR mediates the inhibitory effect of ghrelin on the differentiation of Th17 cells by interacting with STAT3. PMID:25658305

CD28 co-stimulation restores T cell responsiveness in NOD mice by overcoming deficiencies in Rac-1/p38 mitogen-activated protein kinase signaling and IL-2 and IL-4 gene transcription.

PubMed

Zhang, J; Salojin, K V; Delovitch, T L

2001-03-01

Previously, we reported that T cell hyporesponsiveness induced by TCR ligation is causal to autoimmune diabetes in NOD mice. Neonatal CD28 co-stimulation reverses T cell hyporesponsiveness and protects NOD mice from diabetes by an IL-4-mediated mechanism, indicating that a deficiency in TCR signaling may be overcome by CD28/B7-2 co-stimulation in NOD T cells. To investigate which co-stimulation-induced signaling events mediate this protection, we analyzed the activity of Ras, Rac-1, mitogen-activated protein kinases (MAPK) and several transcription factors in TCR-activated NOD T cells in the presence or absence of CD28 co-stimulation. We show that CD28 co-stimulation restores normal TCR-induced activation of Rac-1 and p38 MAPK in NOD T cells. Deficiencies in TCR-induced nuclear expression of activating protein (AP)-1 binding proteins as well as activation of AP-1 and NF-AT in the IL-2 and IL-4 P1 promoters are also corrected by CD28 co-stimulation. Thus, CD28 co-stimulation reverses NOD T cell hyporesponsiveness by restoring TCR signaling leading to the activation of AP-1 and NF-AT during IL-2 and IL-4 gene transcription. Our findings provide additional evidence that CD28 co-stimulation amplifies signals delivered by the TCR and further explain the mechanism by which CD28 co-stimulation may protect against autoimmune diabetes.

Notch ligands Delta1 and Jagged1 transmit distinct signals to T-cell precursors

PubMed Central

Lehar, Sophie M.; Dooley, James; Farr, Andrew G.; Bevan, Michael J.

2009-01-01

Signaling through the Notch pathway plays an essential role in inducing T-lineage commitment and promoting the maturation of immature thymocytes. Using an in vitro culture system, we show that 2 different classes of Notch ligands, Jagged1 or Delta1, transmit distinct signals to T-cell progenitors. OP9 stromal cells expressing either Jagged1 or Delta1 inhibit the differentiation of DN1 thymocytes into the B-cell lineage, but only the Delta1-expressing stromal cells promote the proliferation and maturation of T-cell progenitors through the early double-negative (DN) stages of thymocyte development. Whereas the majority of bone marrow-derived stem cells do not respond to Jagged1 signals, T-cell progenitors respond to Jagged1 signals during a brief window of their development between the DN1 and DN3 stages of thymic development. During these stages, Jagged1 signals can influence the differentiation of immature thymocytes along the natural killer (NK) and γδ T-cell lineages. PMID:15486060

The Adaptor Protein SAP Directly Associates with CD3ζ Chain and Regulates T Cell Receptor Signaling

PubMed Central

Proust, Richard; Bertoglio, Jacques; Gesbert, Franck

2012-01-01

Mutations altering the gene encoding the SLAM associated protein (SAP) are responsible for the X-linked lymphoproliferative disease or XLP1. Its absence is correlated with a defective NKT cells development, a decrease in B cell functions and a reduced T cells and NK cells cytotoxic activities, thus leading to an immunodeficiency syndrome. SAP is a small 128 amino-acid long protein that is almost exclusively composed of an SH2 domain. It has been shown to interact with the CD150/SLAM family of receptors, and in a non-canonical manner with SH3 containing proteins such as Fyn, βPIX, PKCθ and Nck1. It would thus play the role of a minimal adaptor protein. It has been shown that SAP plays an important function in the activation of T cells through its interaction with the SLAM family of receptors. Therefore SAP defective T cells display a reduced activation of signaling events downstream of the TCR-CD3 complex triggering. In the present work, we evidence that SAP is a direct interactor of the CD3ζ chain. This direct interaction occurs through the first ITAM of CD3ζ, proximal to the membrane. Additionally, we show that, in the context of the TCR-CD3 signaling, an Sh-RNA mediated silencing of SAP is responsible for a decrease of several canonical T cell signaling pathways including Erk, Akt and PLCγ1 and to a reduced induction of IL-2 and IL-4 mRNA. Altogether, we show that SAP plays a central function in the T cell activation processes through a direct association with the CD3 complex. PMID:22912825

T-kininogen inhibits kinin-mediated activation of ERK in endothelial cells.

PubMed

Leiva-Salcedo, Elias; Perez, Viviana; Acuña-Castillo, Claudio; Walter, Robin; Sierra, Felipe

2002-01-01

Serum levels of T-kininogen increase dramatically as rats approach the end of their lifespan. Stable expression of the protein in Balb/c 3T3 fibroblasts leads to a dramatic inhibition of cell proliferation, as well as inhibition of the ERK signaling pathway. T-kininogen is a potent inhibitor of cysteine proteinases, and we have described that the inhibition of ERK activity occurs, at least in part, via stabilization of the MAP kinase phosphatase, MKP-1. Since fibroblasts are not a physiological target of T-kininogen, we have now purified the protein from rat serum, and used it to assess the effect of T-kininogen on endothelial cells. Adding purified T-kininogen to EAhy 926 hybridoma cells resulted in inhibition of basal ERK activity levels, as estimated using appropriate anti-phospho ERK antibodies. Furthermore, exogenously added T-kininogen inhibited the activation of the ERK pathway induced by either bradykinin or T-kinin. We conclude that the age-related increase in hepatic T-kininogen gene expression and serum levels of the protein could have dramatic consequences on endothelial cell physiology, both under steady state conditions, and after activation by cell-specific stimuli. Our results are consistent with T-kininogen being an important modulator of the senescent phenotype in vivo.

Interleukin 4: signalling mechanisms and control of T cell differentiation.

PubMed

Paul, W E

1997-01-01

Interleukin 4 (IL-4) is a pleiotropic type I cytokine that controls both growth and differentiation among haemopoietic and non-haemopoietic cells. Its receptor is a heterodimer. One chain, the IL-4R alpha chain, binds IL-4 with high affinity and determines the nature of the biochemical signals that are induced. The second chain, gamma c, is required for the induction of such signals. IL-4-mediated growth depends upon activation events that involve phosphorylation of Y497 of IL-4R alpha, leading to the binding and phosphorylation of 4PS/IRS-2 in haemopoietic cells and of IRS-1 in non-haemopoietic cells. By contrast, IL-4-mediated differentiation events depend upon more distal regions of the IL-4R alpha chain that include a series of STAT-6 binding sites. The distinctive roles of these receptor domains was verified by receptor-reconstruction experiments. The 'growth' and 'differentiation' domains of the IL-4R alpha chain, independently expressed as chimeric structures with a truncated version of the IL-2R beta chain, were shown to convey their functions to the hybrid receptor. The critical role of STAT-6 in IL-4-mediated gene activation and differentiation was made clear by the finding that lymphocytes from STAT-6 knockout mice are strikingly deficient in these functions but have retained the capacity to grow, at least partially, in response to IL-4. IL-4 plays a central role in determining the phenotype of naive CD4+ T cells. In the presence of IL-4, newly primed naive T cells develop into IL-4 producers while in its absence they preferentially become gamma-interferon (IFN-gamma) producers. Recently, a specialized subpopulation of T cells, CD4+/NK1.1+ cells, has been shown to produce large amounts of IL-4 upon stimulation. Two examples of mice with deficiencies in these cells are described--beta 2-microglobulin knockout mice and SJL mice. Both show defects in the development of IL-4-producing cells and in the increase in serum IgE in response to stimulation with the

Heat shock protein 70 (Hsp70) interacts with the Notch1 intracellular domain and contributes to the activity of Notch signaling in myelin-reactive CD4 T cells.

PubMed

Juryńczyk, Maciej; Lewkowicz, Przemysław; Domowicz, Małgorzata; Mycko, Marcin P; Selmaj, Krzysztof W

2015-10-15

Notch receptors (Notch1-4) are involved in the differentiation of CD4 T cells and the development of autoimmunity. Mechanisms regulating Notch signaling in CD4 T cells are not fully elucidated. In this study we investigated potential crosstalk between Notch pathway molecules and heat shock protein 70 (Hsp70), the major intracellular chaperone involved in the protein transport during immune responses and other stress conditions. Using Hsp70(-/-) mice we found that Hsp70 is critical for up-regulation of NICD1 and induction of Notch target genes in Jagged1- and Delta-like1-stimulated CD4 T cells. Co-immunoprecipitation analysis of wild-type CD4 T cells stimulated with either Jagged1 or Delta-like1 showed a direct interaction between NICD1 and Hsp70. Both molecules co-localized within the nucleus of CD4 T cells stimulated with Notch ligands. Molecular interaction and nuclear colocalization of NICD1 and Hsp70 were also detected in CD4 T cells reactive against myelin oligodendrocyte glycoprotein (MOG)35-55, which showed Hsp70-dependent up-regulation of both NICD1 and Notch target genes. In conclusion, we demonstrate for the first time that Hsp70 interacts with NICD1 and contributes to the activity of Notch signaling in CD4 T cells. Interaction between Hsp70 and NICD1 may represent a novel mechanism regulating Notch signaling in activated CD4 T cells. Copyright © 2015 Elsevier B.V. All rights reserved.

Signal transduction in T lymphocytes in microgravity

NASA Technical Reports Server (NTRS)

Cogoli, A.

1997-01-01

More than 120 experiments conducted in space in the last 15 years have shown that dramatic changes are occurring in several types of single cells during their exposure to microgravity. One focus of today's research on cells in space is on signal transduction, especially those steps involving the cytoskeleton and cell-cell interactions. Signal transduction is often altered in microgravity as well as in hypergravity. This leads to changes in cell proliferation, genetic expression and differentiation. Interesting examples are leukocytes, HeLa cells, epidermoid cells and osteoblastic cells. Signalling pathways were studied in T lymphocytes in microgravity by several investigators after the discovery that mitogenic activation in vitro is virtually nil at 0g. T cells are a good model to study signal transduction because three extracellular signals (mitogen, IL-1 and IL-2) are required for full activation, and two classical pathways (via proteins G and PKC) are activated within the cell. In addition, low molecular weight GTP-binding proteins (Ras and Rap) are interacting with the cytoskeleton. The data at 0g support the notion that the expression of IL-2 receptor is inhibited at 0g, while mitogen binding and the transmission of IL-1 by accessory cells occur normally. In addition, alterations of the cytoskeleton suggest that the interaction with Rap proteins is disturbed. Data obtained with phorbol esters indicate that the function of PKC is changed in microgravity. Similar conclusions are drawn from the results with epidermoid cells A431.

Computational properties of mitochondria in T cell activation and fate

PubMed Central

Dupont, Geneviève

2016-01-01

In this article, we review how mitochondrial Ca2+ transport (mitochondrial Ca2+ uptake and Na+/Ca2+ exchange) is involved in T cell biology, including activation and differentiation through shaping cellular Ca2+ signals. Based on recent observations, we propose that the Ca2+ crosstalk between mitochondria, endoplasmic reticulum and cytoplasm may form a proportional–integral–derivative (PID) controller. This PID mechanism (which is well known in engineering) could be responsible for computing cellular decisions. In addition, we point out the importance of analogue and digital signal processing in T cell life and implication of mitochondrial Ca2+ transport in this process. PMID:27852805

Computational properties of mitochondria in T cell activation and fate.

PubMed

Uzhachenko, Roman; Shanker, Anil; Dupont, Geneviève

2016-11-01

In this article, we review how mitochondrial Ca 2+ transport (mitochondrial Ca 2+ uptake and Na + /Ca 2+ exchange) is involved in T cell biology, including activation and differentiation through shaping cellular Ca 2+ signals. Based on recent observations, we propose that the Ca 2+ crosstalk between mitochondria, endoplasmic reticulum and cytoplasm may form a proportional-integral-derivative (PID) controller. This PID mechanism (which is well known in engineering) could be responsible for computing cellular decisions. In addition, we point out the importance of analogue and digital signal processing in T cell life and implication of mitochondrial Ca 2+ transport in this process. © 2016 The Authors.

Ablation of SLP-76 signaling after T cell priming generates memory CD4 T cells impaired in steady-state and cytokine-driven homeostasis.

PubMed

Bushar, Nicholas D; Corbo, Evann; Schmidt, Michelle; Maltzman, Jonathan S; Farber, Donna L

2010-01-12

The intracellular signaling mechanisms regulating the generation and long-term persistence of memory T cells in vivo remain unclear. In this study, we used mouse models with conditional deletion of the key T cell receptor (TCR)-coupled adaptor molecule SH2-domain-containing phosphoprotein of 76 kDa (SLP-76), to analyze signaling mechanisms for memory CD4 T cell generation, maintenance, and homeostasis. We found that ablation of SLP-76 expression after T cell priming did not inhibit generation of phenotypic effector or memory CD4 T cells; however, the resultant SLP-76-deficient memory CD4 T cells could not produce recall cytokines in response to TCR-mediated stimulation and showed decreased persistence in vivo. In addition, SLP-76-deficient memory CD4 T cells exhibited reduced steady-state homeostasis and were impaired in their ability to homeostatically expand in vivo in response to the gamma(c) cytokine IL-7, despite intact proximal signaling through the IL-7R-coupled JAK3/STAT5 pathway. Direct in vivo deletion of SLP-76 in polyclonal memory CD4 T cells likewise led to impaired steady-state homeostasis as well as impaired homeostatic responses to IL-7. Our findings demonstrate a dominant role for SLP-76-dependent TCR signals in regulating turnover and perpetuation of memory CD4 T cells and their responses to homeostatic cytokines, with implications for the selective survival of memory CD4 T cells following pathogen exposure, vaccination, and aging.

Mangifera indica L. extract protects T cells from activation-induced cell death.

PubMed

Hernández, Patricia; Delgado, Rene; Walczak, Henning

2006-09-01

The aqueous stem bark extract of Mangifera indica L. (Vimang) has been reported to have antioxidant properties. AIDS is characterized by up-regulation of CD95 ligand (CD95L) expression and enhancement of activation-induced cell death (AICD). Recent studies demonstrate oxidative signals combined with simultaneous calcium (Ca(2+)) influx into the cytosol are required for induction of CD95L expression. In this study we show that M. indica extract attenuated anti-CD3-induced accumulation of reactive oxygen species (ROS) and intracellular free Ca(2+) and consequently, downregulates CD95L mRNA expression and CD95-mediated AICD. In addition, TCR triggering caused an elevation in the antioxidant enzyme manganous superoxide dismutase (Mn-SOD) and the increase in c-Jun N-terminal kinase (JNK) phosphorylation, both effects being prevented by M. indica extract. We provide a number of evidences regarding how M. indica extract enhance T-cell survival by inhibiting AICD, a finding associated with a decrease in oxidative stress generated through the TCR signaling pathway in activated T cells.

Homocysteine activates T cells by enhancing endoplasmic reticulum-mitochondria coupling and increasing mitochondrial respiration.

PubMed

Feng, Juan; Lü, Silin; Ding, Yanhong; Zheng, Ming; Wang, Xian

2016-06-01

Hyperhomocysteinemia (HHcy) accelerates atherosclerosis by increasing proliferation and stimulating cytokine secretion in T cells. However, whether homocysteine (Hcy)-mediated T cell activation is associated with metabolic reprogramming is unclear. Here, our in vivo and in vitro studies showed that Hcy-stimulated splenic T-cell activation in mice was accompanied by increased levels of mitochondrial reactive oxygen species (ROS) and calcium, mitochondrial mass and respiration. Inhibiting mitochondrial ROS production and calcium signals or blocking mitochondrial respiration largely blunted Hcy-induced T-cell interferon γ (IFN-γ) secretion and proliferation. Hcy also enhanced endoplasmic reticulum (ER) stress in T cells, and inhibition of ER stress with 4-phenylbutyric acid blocked Hcy-induced T-cell activation. Mechanistically, Hcy increased ER-mitochondria coupling, and uncoupling ER-mitochondria by the microtubule inhibitor nocodazole attenuated Hcy-stimulated mitochondrial reprogramming, IFN-γ secretion and proliferation in T cells, suggesting that juxtaposition of ER and mitochondria is required for Hcy-promoted mitochondrial function and T-cell activation. In conclusion, Hcy promotes T-cell activation by increasing ER-mitochondria coupling and regulating metabolic reprogramming.

Role of T cells in the B-cell response: glutaraldehyde-fixed T-helper hybridoma cells synergize with the lymphokine IL-4 to induce B-cell activation and proliferation.

PubMed

Kubota, E; McKenzie, D T; Dutton, R W; Swain, S L

1991-01-01

Antigen-unselected helper T-cell hybridomas (Th) which activate normal resting B cells to RNA synthesis and proliferation in the presence of concanavalin A (Con A) have been developed. The response is completely Th cell dependent, and not restricted by the haplotype of the B-cell major histocompatibility complex (MHC). Culture supernatants from the Con A-stimulated Th hybridomas contain interleukin-4 (IL-4) and IL-2, but undetectable level of IL-5. The supernatant alone, however, does not induce B-cell activation or proliferation. Although the Con A-mediated Th cell-dependent B-cell response occurs in an MHC-unrestricted manner, the response of resting B cells can be blocked by monoclonal Ia antibody specific for the surface class II molecules of the responding B cell. The response is also blocked by monoclonal antibody to L3T4. Significant activation and proliferation of resting B cells can also be triggered by glutaraldehyde-fixed Th hybridomas and Con A when exogenous IL-4 is added. The stimulation with fixed Th hybridomas plus IL-4 can be inhibited by monoclonal anti-L3T4 or anti-Ia. These results suggest that maximal B-cell activation requires a direct helper T cell-B cell interaction which depends on availability of Ia on the B cell and L3T4 on the T cell, even when Con A overcomes the requirement for MHC-restricted T-cell recognition. We suggest that this signal, in conjunction with T-cell produced lymphokine IL-4, is responsible for the activation and subsequent proliferation of the B cells which occurs following interaction with T cells.

IL-7–dependent STAT1 activation limits homeostatic CD4+ T cell expansion

PubMed Central

Le Saout, Cecile; Luckey, Megan A.; Villarino, Alejandro V.; Smith, Mindy; Hasley, Rebecca B.; Myers, Timothy G.; Imamichi, Hiromi; Park, Jung-Hyun; O’Shea, John J.; Lane, H. Clifford

2017-01-01

IL-7 regulates homeostatic mechanisms that maintain the overall size of the T cell pool throughout life. We show that, under steady-state conditions, IL-7 signaling is principally mediated by activation of signal transducers and activators of transcription 5 (STAT5). In contrast, under lymphopenic conditions, there is a modulation of STAT1 expression resulting in an IL-7–dependent STAT1 and STAT5 activation. Consequently, the IL-7–induced transcriptome is altered with enrichment of IFN-stimulated genes (ISGs). Moreover, STAT1 overexpression was associated with reduced survival in CD4+ T cells undergoing lymphopenia-induced proliferation (LIP). We propose a model in which T cells undergoing LIP upregulate STAT1 protein, “switching on” an alternate IL-7–dependent program. This mechanism could be a physiological process to regulate the expansion and size of the CD4+ T cell pool. During HIV infection, the virus could exploit this pathway, leading to the homeostatic dysregulation of the T cell pools observed in these patients. PMID:29202461

Immunomodulatory effect of tea saponin in immune T-cells and T-lymphoma cells via regulation of Th1, Th2 immune response and MAPK/ERK2 signaling pathway.

PubMed

Bhardwaj, Jyoti; Chaudhary, Narendra; Seo, Hyo-Jin; Kim, Min-Yong; Shin, Tai-Sun; Kim, Jong-Deog

2014-06-01

The anti-cancer activity of saponins and phenolic compounds present in green tea was previously reported. However, the immunomodulatory and adjuvanticity activity of tea saponin has never been studied. In this study, we investigated the immunomodulatory effect of tea saponin in T-lymphocytes and EL4 cells via regulation of cytokine response and mitogen-activated protein kinases (MAPK) signaling pathway. Quantitative analysis of mRNA expression level of cytokines were performed by reverse transcription polymerase chain reaction following stimulation with tea saponin, ovalbumin (OVA) alone or tea saponin in combination with OVA. Tea saponin inhibited the proliferation of EL4 cells measured in a dose-dependent manner. No cytotoxicity effect of tea saponin was detected in T-lymphocytes; rather, tea saponin enhanced the proliferation of T-lymphocytes. Tea saponin with OVA increased the expression of interleukin (IL)-1, IL-2, IL-12, interferon-γ and tumor necrosis factor (TNF)-α and decreased the expression level of IL-10 and IL-8 in T-lymphocytes. Furthermore, tea saponin, in the presence of OVA, downregulated the MAPK signaling pathway via inhibition of IL-4, IL-8 and nuclear factor kappaB (NF-κB) in EL4 cells. Th1 cytokines enhancer and Th2 cytokines and NF-κB inhibitor, tea saponin can markedly inhibit the proliferation and invasiveness of T-lymphoma (EL4) cells, possibly due to TNF-α- and NF-κB-mediated regulation of MAPK signaling pathway.

Agrin Signalling Contributes to Cell Activation and Is Overexpressed in T Lymphocytes from Lupus Patients1

PubMed Central

Jury, Elizabeth C.; Eldridge, Jillian; Isenberg, David A.; Kabouridis, Panagiotis S.

2008-01-01

It is shown in this study that the heparan sulfate proteoglycan agrin is overexpressed in T cells isolated from patients with the autoimmune disease systemic lupus erythematosus (SLE). Freshly isolated CD4+ and CD8+ subpopulations both exhibited higher expression over healthy controls, which however, gradually declined when cells were cultured in vitro. Agrin expression was induced following in vitro activation of cells via their Ag receptor, or after treatment with IFN-α, a cytokine shown to be pathogenic in lupus. Furthermore, serum from SLE patients with active disease was able to induce agrin expression when added to T cells from healthy donors, an increase that was partially blocked by neutralizing anti-IFN-α Abs. Cross-linking agrin with mAbs resulted in rapid reorganization of the actin cytoskeleton, activation of the ERK MAPK cascade, and augmentation of anti-CD3-induced proliferation and IL-10 production, indicating that agrin is a functional receptor in T cells. These results demonstrate that agrin expression in human T cells is regulated by cell activation and IFN-α, and may have an important function during cell activation with potential implications for autoimmunity. PMID:18025246

Co-stimulatory signaling determines tumor antigen sensitivity and persistence of CAR T cells targeting PSCA+ metastatic prostate cancer

PubMed Central

Priceman, Saul J.; Gerdts, Ethan A.; Tilakawardane, Dileshni; Kennewick, Kelly T.; Murad, John P.; Park, Anthony K.; Jeang, Brook; Yamaguchi, Yukiko; Urak, Ryan; Weng, Lihong; Chang, Wen-Chung; Wright, Sarah; Pal, Sumanta; Reiter, Robert E.; Brown, Christine E.; Forman, Stephen J.

2018-01-01

ABSTRACT Advancing chimeric antigen receptor (CAR)-engineered adoptive T cells for the treatment of solid cancers is a major focus in the field of immunotherapy, given impressive recent clinical responses in hematological malignancies. Prostate cancer may be amenable to T cell-based immunotherapy since several tumor antigens, including prostate stem-cell antigen (PSCA), are widely over-expressed in metastatic disease. While antigen selectivity of CARs for solid cancers is crucial, it is problematic due to the absence of truly restricted tumor antigen expression and potential safety concerns with “on-target off-tumor” activity. Here, we show that the intracellular co-stimulatory signaling domain can determine a CAR's sensitivity for tumor antigen expression. A 4-1BB intracellular co-stimulatory signaling domain in PSCA-CARs confers improved selectivity for higher tumor antigen density, reduced T cell exhaustion phenotype, and equivalent tumor killing ability compared to PSCA-CARs containing the CD28 co-stimulatory signaling domain. PSCA-CARs exhibit robust in vivo anti-tumor activity in patient-derived bone-metastatic prostate cancer xenograft models, and 4-1BB-containing CARs show superior T cell persistence and control of disease compared with CD28-containing CARs. Our study demonstrates the importance of co-stimulation in defining an optimal CAR T cell, and also highlights the significance of clinically relevant models in developing solid cancer CAR T cell therapies. PMID:29308300

A Natural Variant of the T Cell Receptor-Signaling Molecule Vav1 Reduces Both Effector T Cell Functions and Susceptibility to Neuroinflammation.

PubMed

Kassem, Sahar; Gaud, Guillaume; Bernard, Isabelle; Benamar, Mehdi; Dejean, Anne S; Liblau, Roland; Fournié, Gilbert J; Colacios, Céline; Malissen, Bernard; Saoudi, Abdelhadi

2016-07-01

The guanine nucleotide exchange factor Vav1 is essential for transducing T cell antigen receptor signals and therefore plays an important role in T cell development and activation. Our previous genetic studies identified a locus on rat chromosome 9 that controls the susceptibility to neuroinflammation and contains a non-synonymous polymorphism in the major candidate gene Vav1. To formally demonstrate the causal implication of this polymorphism, we generated a knock-in mouse bearing this polymorphism (Vav1R63W). Using this model, we show that Vav1R63W mice display reduced susceptibility to experimental autoimmune encephalomyelitis (EAE) induced by MOG35-55 peptide immunization. This is associated with a lower production of effector cytokines (IFN-γ, IL-17 and GM-CSF) by autoreactive CD4 T cells. Despite increased proportion of Foxp3+ regulatory T cells in Vav1R63W mice, we show that this lowered cytokine production is intrinsic to effector CD4 T cells and that Treg depletion has no impact on EAE development. Finally, we provide a mechanism for the above phenotype by showing that the Vav1R63W variant has normal enzymatic activity but reduced adaptor functions. Together, these data highlight the importance of Vav1 adaptor functions in the production of inflammatory cytokines by effector T cells and in the susceptibility to neuroinflammation.

A Natural Variant of the T Cell Receptor-Signaling Molecule Vav1 Reduces Both Effector T Cell Functions and Susceptibility to Neuroinflammation

PubMed Central

Kassem, Sahar; Bernard, Isabelle; Dejean, Anne S.; Liblau, Roland; Fournié, Gilbert J.; Colacios, Céline

2016-01-01

The guanine nucleotide exchange factor Vav1 is essential for transducing T cell antigen receptor signals and therefore plays an important role in T cell development and activation. Our previous genetic studies identified a locus on rat chromosome 9 that controls the susceptibility to neuroinflammation and contains a non-synonymous polymorphism in the major candidate gene Vav1. To formally demonstrate the causal implication of this polymorphism, we generated a knock-in mouse bearing this polymorphism (Vav1R63W). Using this model, we show that Vav1R63W mice display reduced susceptibility to experimental autoimmune encephalomyelitis (EAE) induced by MOG35-55 peptide immunization. This is associated with a lower production of effector cytokines (IFN-γ, IL-17 and GM-CSF) by autoreactive CD4 T cells. Despite increased proportion of Foxp3+ regulatory T cells in Vav1R63W mice, we show that this lowered cytokine production is intrinsic to effector CD4 T cells and that Treg depletion has no impact on EAE development. Finally, we provide a mechanism for the above phenotype by showing that the Vav1R63W variant has normal enzymatic activity but reduced adaptor functions. Together, these data highlight the importance of Vav1 adaptor functions in the production of inflammatory cytokines by effector T cells and in the susceptibility to neuroinflammation. PMID:27438086

IL-7 signaling imparts polyfunctionality and stemness potential to CD4+ T cells

PubMed Central

Ding, Zhi-Chun; Liu, Chufeng; Cao, Yang; Habtetsion, Tsadik; Kuczma, Michal; Pi, Wenhu; Kong, Heng; Cacan, Ercan; Greer, Susanna F.; Cui, Yan; Blazar, Bruce R.; Munn, David H.; Zhou, Gang

2016-01-01

ABSTRACT The functional status of CD4+ T cells is a critical determinant of antitumor immunity. Polyfunctional CD4+ T cells possess the ability to concomitantly produce multiple Th1-type cytokines, exhibiting a functional attribute desirable for cancer immunotherapy. However, the mechanisms by which these cells are induced are neither defined nor it is clear if these cells can be used therapeutically to treat cancer. Here, we report that CD4+ T cells exposed to exogenous IL-7 during antigenic stimulation can acquire a polyfunctional phenotype, characterized by their ability to simultaneously express IFNγ, IL-2, TNFα and granzyme B. This IL-7-driven polyfunctional phenotype was associated with increased histone acetylation in the promoters of the effector genes, indicative of increased chromatin accessibility. Moreover, forced expression of a constitutively active (CA) form of STAT5 recapitulated IL-7 in inducing CD4+ T-cell polyfunctionality. Conversely, the expression of a dominant negative (DN) form of STAT5 abolished the ability of IL-7 to induce polyfunctional CD4+ T cells. These in-vitro-generated polyfunctional CD4+ T cells can traffic to tumor and expand intratumorally in response to immunization. Importantly, adoptive transfer of polyfunctional CD4+ T cells following lymphodepletive chemotherapy was able to eradicate large established tumors. This beneficial outcome was associated with the occurrence of antigen epitope spreading, activation of the endogenous CD8+ T cells and persistence of donor CD4+ T cells exhibiting memory stem cell attributes. These findings indicate that IL-7 signaling can impart polyfunctionality and stemness potential to CD4+ T cells, revealing a previously unknown property of IL-7 that can be exploited in adoptive T-cell immunotherapy. PMID:27471650

PKC-Theta is a Novel SC35 Splicing Factor Regulator in Response to T Cell Activation.

PubMed

McCuaig, Robert Duncan; Dunn, Jennifer; Li, Jasmine; Masch, Antonia; Knaute, Tobias; Schutkowski, Mike; Zerweck, Johannes; Rao, Sudha

2015-01-01

Alternative splicing of nuclear pre-mRNA is essential for generating protein diversity and regulating gene expression. While many immunologically relevant genes undergo alternative splicing, the role of regulated splicing in T cell immune responses is largely unexplored, and the signaling pathways and splicing factors that regulate alternative splicing in T cells are poorly defined. Here, we show using a combination of Jurkat T cells, human primary T cells, and ex vivo naïve and effector virus-specific T cells isolated after influenza A virus infection that SC35 phosphorylation is induced in response to stimulatory signals. We show that SC35 colocalizes with RNA polymerase II in activated T cells and spatially overlaps with H3K27ac and H3K4me3, which mark transcriptionally active genes. Interestingly, SC35 remains coupled to the active histone marks in the absence of continuing stimulatory signals. We show for the first time that nuclear PKC-θ co-exists with SC35 in the context of the chromatin template and is a key regulator of SC35 in T cells, directly phosphorylating SC35 peptide residues at RNA recognition motif and RS domains. Collectively, our findings suggest that nuclear PKC-θ is a novel regulator of the key splicing factor SC35 in T cells.

IFN-γ regulates CD8+ memory T cell differentiation and survival in response to weak, but not strong, TCR signals.

PubMed

Stoycheva, Diana; Deiser, Katrin; Stärck, Lilian; Nishanth, Gopala; Schlüter, Dirk; Uckert, Wolfgang; Schüler, Thomas

2015-01-15

In response to primary Ag contact, naive mouse CD8(+) T cells undergo clonal expansion and differentiate into effector T cells. After pathogen clearance, most effector T cells die, and only a small number of memory T cell precursors (TMPs) survive to form a pool of long-lived memory T cells (TMs). Although high- and low-affinity CD8(+) T cell clones are recruited into the primary response, the TM pool consists mainly of high-affinity clones. It remains unclear whether the more efficient expansion of high-affinity clones and/or cell-intrinsic processes exclude low-affinity T cells from the TM pool. In this article, we show that the lack of IFN-γR signaling in CD8(+) T cells promotes TM formation in response to weak, but not strong, TCR agonists. The IFN-γ-sensitive accumulation of TMs correlates with reduced mammalian target of rapamycin activation and the accumulation of long-lived CD62L(hi)Bcl-2(hi)Eomes(hi) TMPs. Reconstitution of mammalian target of rapamycin or IFN-γR signaling is sufficient to block this process. Hence, our data suggest that IFN-γR signaling actively blocks the formation of TMPs responding to weak TCR agonists, thereby promoting the accumulation of high-affinity T cells finally dominating the TM pool. Copyright © 2015 by The American Association of Immunologists, Inc.

STATs Shape the Active Enhancer Landscape of T Cell Populations

PubMed Central

Vahedi, Golnaz; Takahashi, Hayato; Nakayamada, Shingo; Sun, Hong-wei; Sartorelli, Vittorio; Kanno, Yuka; O’Shea, John J.

2012-01-01

SUMMARY Signaling pathways are intimately involved in cellular differentiation, allowing cells to respond to their environment by regulating gene expression. While enhancers are recognized as key elements that regulate selective gene expression, the interplay between signaling pathways and actively used enhancer elements is not clear. Here, we use CD4+ T cells as a model of differentiation, mapping the acquisition of cell-type-specific enhancer elements in T-helper 1 (Th1) and Th2 cells. Our data establish that STAT proteins have a major impact on the acquisition of lineage-specific enhancers and the suppression of enhancers associated with alternative cell fates. Transcriptome analysis further supports a functional role for enhancers regulated by STATs. Importantly, expression of lineage-defining master regulators in STAT-deficient cells fails to fully recover the chromatin signature of STAT-dependent enhancers. Thus, these findings point to a critical role of STATs as environmental sensors in dynamically molding the specialized enhancer architecture of differentiating cells. PMID:23178119

Unexpected T cell regulatory activity of anti-histone H1 autoantibody: Its mode of action in regulatory T cell-dependent and -independent manners

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takaoka, Yuki; Kawamoto, Seiji, E-mail: skawa@hiroshima-u.ac.jp; Katayama, Akiko

2013-02-08

Highlights: ► Anti-histone H1 autoantibody (anti-H1) acts on T cells to inhibit their activation. ► Anti-H1 suppresses T cell activation in Treg cell-dependent and -independent manners. ► Suboptimal dose of anti-H1 enhances suppressor function of Treg cells. ► High dose of anti-H1 directly inhibits T cell receptor signaling. -- Abstract: Induction of anti-nuclear antibodies against DNA or histones is a hallmark of autoimmune disorders, but their actual contribution to disease predisposition remains to be clarified. We have previously reported that autoantibodies against histone H1 work as a critical graft survival factor in a rat model of tolerogeneic liver transplantation. Heremore » we show that an immunosuppressive anti-histone H1 monoclonal antibody (anti-H1 mAb) acts directly on T cells to inhibit their activation in response to T cell receptor (TCR) ligation. Intriguingly, the T cell activation inhibitory activity of anti-H1 mAb under suboptimal dosages required regulatory T (Treg) cells, while high dose stimulation with anti-H1 mAb triggered a Treg cell-independent, direct negative regulation of T cell activation upon TCR cross-linking. In the Treg cell-dependent mode of immunosuppressive action, anti-H1 mAb did not induce the expansion of CD4{sup +}Foxp3{sup +} Treg cells, but rather potentiated their regulatory capacity. These results reveal a previously unappreciated T cell regulatory role of anti-H1 autoantibody, whose overproduction is generally thought to be pathogenic in the autoimmune settings.« less

Cellular cooperation in lymphocyte activation. III. B-cell helper effect in the enhancement of T-cell response.

PubMed

Kasahara, T; Kin, K; Itoh, Y; Kawai, T; Kano, Y; Shioiri-Nakano, K

1979-01-01

T and B cells were purified from human tonsil and peripheral blood by the removal of phagocytic cells, followed by filtration through a nylon fiber column (NC) and E-rosette formation. Purified T and B cells contained less than 1% of other cell types. The responses of T cells to concanavalin A (Con A) and soluble protein A were greatly enhanced in the presence of autologous B cells. Participation of B cells in T-cell enhancement was confirmed by the following observations: (a) purified B copulation, which was separated further from adherent B cells, retained its enhancing activity. (b) Another adherent cell-free B-cell preparation, which was purified from the NC-passed fraction, and (c) no T lymphoid but some B lymphoid cell lines, elicited strong T-cell enhancement. It was also found that the enhancing capacity of B cells required no metabolic activity, but rather an intact cell form and direct cell-to-cell contact with responding cells. The stimulatory determinants on B cells were resistant to trypsin and neuraminidase treatment. In this paper a hypothesis will be presented that at least two signals are prerequisite for the effective activation of T cells.

CD155T/TIGIT Signaling Regulates CD8+ T-cell Metabolism and Promotes Tumor Progression in Human Gastric Cancer.

PubMed

He, Weiling; Zhang, Hui; Han, Fei; Chen, Xinlin; Lin, Run; Wang, Wei; Qiu, Haibo; Zhuang, Zhenhong; Liao, Qi; Zhang, Weijing; Cai, Qinbo; Cui, Yongmei; Jiang, Wenting; Wang, Han; Ke, Zunfu

2017-11-15

The T-cell surface molecule TIGIT is an immune checkpoint molecule that inhibits T-cell responses, but its roles in cancer are little understood. In this study, we evaluated the role TIGIT checkpoint plays in the development and progression of gastric cancer. We show that the percentage of CD8 T cells that are TIGIT + was increased in gastric cancer patients compared with healthy individuals. These cells showed functional exhaustion with impaired activation, proliferation, cytokine production, and metabolism, all of which were rescued by glucose. In addition, gastric cancer tissue and cell lines expressed CD155, which bound TIGIT receptors and inactivated CD8 T cells. In a T cell-gastric cancer cell coculture system, gastric cancer cells deprived CD8 T cells of glucose and impaired CD8 T-cell effector functions; these effects were neutralized by the additional glucose or by TIGIT blockade. In gastric cancer tumor cells, CD155 silencing increased T-cell metabolism and IFNγ production, whereas CD155 overexpression inhibited T-cell metabolism and IFNγ production; this inhibition was neutralized by TIGIT blockade. Targeting CD155/TIGIT enhanced CD8 T-cell reaction and improved survival in tumor-bearing mice. Combined targeting of TIGIT and PD-1 further enhanced CD8 T-cell activation and improved survival in tumor-bearing mice. Our results suggest that gastric cancer cells inhibit CD8 T-cell metabolism through CD155/TIGIT signaling, which inhibits CD8 T-cell effector functions, resulting in hyporesponsive antitumor immunity. These findings support the candidacy of CD155/TIGIT as a potential therapeutic target in gastric cancer. Cancer Res; 77(22); 6375-88. ©2017 AACR . ©2017 American Association for Cancer Research.

T cell ignorance is bliss: T cells are not tolerized by Langerhans cells presenting human papillomavirus antigens in the absence of costimulation.

PubMed

Woodham, Andrew W; Yan, Lisa; Skeate, Joseph G; van der Veen, Daniel; Brand, Heike H; Wong, Michael K; Da Silva, Diane M; Kast, W Martin

2016-12-01

Human papillomavirus type 16 (HPV16) infections are intra-epithelial, and thus, HPV16 is known to interact with Langerhans cells (LCs), the resident epithelial antigen-presenting cells (APCs). The current paradigm for APC-mediated induction of T cell anergy is through delivery of T cell receptor signals via peptides on MHC molecules (signal 1), but without costimulation (signal 2). We previously demonstrated that LCs exposed to HPV16 in vitro present HPV antigens to T cells without costimulation, but it remained uncertain if such T cells would remain ignorant, become anergic, or in the case of CD4+ T cells, differentiate into Tregs. Here we demonstrate that Tregs were not induced by LCs presenting only signal 1, and through a series of in vitro immunizations show that CD8 + T cells receiving signal 1 + 2 from LCs weeks after consistently receiving signal 1 are capable of robust effector functions. Importantly, this indicates that T cells are not tolerized but instead remain ignorant to HPV, and are activated given the proper signals.

Lubiprostone activates Cl- secretion via cAMP signaling and increases membrane CFTR in the human colon carcinoma cell line, T84.

PubMed

Ao, Mei; Venkatasubramanian, Jayashree; Boonkaewwan, Chaiwat; Ganesan, Nivetha; Syed, Asma; Benya, Richard V; Rao, Mrinalini C

2011-02-01

Lubiprostone, used clinically (b.i.d.) to treat constipation, has been reported to increase transepithelial Cl(-) transport in T84 cells by activating ClC-2 channels. To identify the underlying signaling pathway, we explored the effects of short-term and overnight lubiprostone treatment on second messenger signaling and Cl(-) transport. Cl(-) transport was assessed either as I(sc) across T84 monolayers grown on Transwells and mounted in Ussing chambers or by the iodide efflux assay. [cAMP](i) was measured by enzyme immunoassay, and [Ca(2+)](i) by Fluo-3 fluorescence. Quantitation of apical cell surface CFTR protein levels was assessed by Western blotting and biotinylation with the EZ-Link Sulfo-NHS-LC-LC-Biotin. ClC-2 mRNA level was studied by RT-PCR. Lubiprostone and the cAMP stimulator, forskolin, caused comparable and maximal increases of I(sc) in T84 cells. The I(sc) effects of lubiprostone and forskolin were each suppressed if the tissue had previously been treated with the other agent. These responses were unaltered even if the monolayers were treated with lubiprostone overnight. Lubiprostone-induced increases in iodide efflux were ~80% of those obtained with forskolin. Lubiprostone increased [cAMP](i). H89, bumetanide, or CFTR(inh)-172 greatly attenuated lubiprostone-stimulated Cl(-) secretion, whereas the ClC-2 inhibitor CdCl(2) did not. Compared to controls, FSK-treatment increased membrane-associated CFTR by 1.9 fold, and lubiprostone caused a 2.6-fold increase in apical membrane CFTR as seen by immunoblotting following cell surface biotinylation. Lubiprostone activates Cl(-) secretion in T84 cells via cAMP, protein kinase A, and by increasing apical membrane CFTR protein.

Notch signalling in T cell lymphoblastic leukaemia/lymphoma and other haematological malignancies

PubMed Central

Aster, Jon C.; Blacklow, Stephen C.; Pear, Warren S.

2010-01-01

Notch receptors participate in a highly conserved signalling pathway that regulates normal development and tissue homeostasis in a context- and dose-dependent manner. Deregulated Notch signalling has been implicated in many diseases, but the clearest example of a pathogenic role is found in T cell lymphoblastic leukaemia/lymphoma (T-LL), in which the majority of human and murine tumours have acquired mutations that lead to aberrant increases in Notch1 signalling. Remarkably, it appears that the selective pressure for Notch mutations is virtually unique among cancers to T-LL, presumably reflecting a special context-dependent role for Notch in normal T cell progenitors. Nevertheless, there are some recent reports suggesting that Notch signalling has subtle yet important roles in other forms of hematologic malignancy as well. Here, we review the role of Notch signalling in various blood cancers, focusing on T-LL with an eye toward targeted therapeutics. PMID:20967796

Aberrant T Cell Signaling and Subsets in Systemic Lupus Erythematosus.

PubMed

Katsuyama, Takayuki; Tsokos, George C; Moulton, Vaishali R

2018-01-01

Systemic lupus erythematosus (SLE) is a chronic multi-organ debilitating autoimmune disease, which mainly afflicts women in the reproductive years. A complex interaction of genetics, environmental factors and hormones result in the breakdown of immune tolerance to "self" leading to damage and destruction of multiple organs, such as the skin, joints, kidneys, heart and brain. Both innate and adaptive immune systems are critically involved in the misguided immune response against self-antigens. Dendritic cells, neutrophils, and innate lymphoid cells are important in initiating antigen presentation and propagating inflammation at lymphoid and peripheral tissue sites. Autoantibodies produced by B lymphocytes and immune complex deposition in vital organs contribute to tissue damage. T lymphocytes are increasingly being recognized as key contributors to disease pathogenesis. CD4 T follicular helper cells enable autoantibody production, inflammatory Th17 subsets promote inflammation, while defects in regulatory T cells lead to unchecked immune responses. A better understanding of the molecular defects including signaling events and gene regulation underlying the dysfunctional T cells in SLE is necessary to pave the path for better management, therapy, and perhaps prevention of this complex disease. In this review, we focus on the aberrations in T cell signaling in SLE and highlight therapeutic advances in this field.

Aberrant T Cell Signaling and Subsets in Systemic Lupus Erythematosus

PubMed Central

Katsuyama, Takayuki; Tsokos, George C.; Moulton, Vaishali R.

2018-01-01

Systemic lupus erythematosus (SLE) is a chronic multi-organ debilitating autoimmune disease, which mainly afflicts women in the reproductive years. A complex interaction of genetics, environmental factors and hormones result in the breakdown of immune tolerance to “self” leading to damage and destruction of multiple organs, such as the skin, joints, kidneys, heart and brain. Both innate and adaptive immune systems are critically involved in the misguided immune response against self-antigens. Dendritic cells, neutrophils, and innate lymphoid cells are important in initiating antigen presentation and propagating inflammation at lymphoid and peripheral tissue sites. Autoantibodies produced by B lymphocytes and immune complex deposition in vital organs contribute to tissue damage. T lymphocytes are increasingly being recognized as key contributors to disease pathogenesis. CD4 T follicular helper cells enable autoantibody production, inflammatory Th17 subsets promote inflammation, while defects in regulatory T cells lead to unchecked immune responses. A better understanding of the molecular defects including signaling events and gene regulation underlying the dysfunctional T cells in SLE is necessary to pave the path for better management, therapy, and perhaps prevention of this complex disease. In this review, we focus on the aberrations in T cell signaling in SLE and highlight therapeutic advances in this field. PMID:29868033

How polarity shapes the destiny of T cells.

PubMed

Russell, Sarah

2008-01-15

The differentiation, activation and expansion of T cells are dictated by their integrated response to a complex array of extracellular signals. Recent studies provide insight into how these signals are integrated and demonstrate a key role for cell shape in many aspects of T-cell signalling. T cells polarise during migration, antigen presentation and cell division to give rise to daughter cells that can have different cell fates. In each case, the polarity of the T cell facilitates this activity. This raises the possibility that adoption of a polarised state acts as a positive feedback mechanism to enhance responses to specific signals. Similarly, in asymmetric division of other cell types, the distribution of different molecules into each daughter can have profound consequences for proliferation, death and differentiation. The mechanisms of polarity regulation are far better understood in cells such as epithelial cells, neurons and neuronal precursors, and the fertilised zygote. With the emerging parallels between polarity in these cells and T cells, we should now be able to elucidate how polarity affects signalling and cell fate determination in T cells.

Nonlinear microscopy as diagnostic tool for the discrimination of activated T cells

NASA Astrophysics Data System (ADS)

Gavgiotaki, E.; Filippidis, G.; Zerva, I.; Agelaki, S.; Georgoulias, V.; Athanassakis, I.

2017-07-01

Third Harmonic Generation (THG) imaging was applied to mouse resting and activated T-cells. Quantification of THG signal, which corresponded to lipid droplets, could distinguish activated Tcells, allowing follow-up of immune response development.

MyD88 signaling in T cells directs IgA-mediated control of the microbiota to promote health

PubMed Central

Kubinak, Jason L.; Petersen, Charisse; Stephens, W. Zac; Soto, Ray; Bake, Erin; O’Connell, Ryan M.; Round, June L.

2015-01-01

SUMMARY Altered commensal communities are associated with human disease. IgA mediates intestinal homeostasis and regulates microbiota composition. Intestinal IgA is produced at high levels as a result of T follicular helper cell (TFH) and B cell interactions in germinal centers. However, the pathways directing host IgA responses towards the microbiota remain unknown. Here, we report that signaling through the innate adaptor MyD88 in gut T cells coordinates germinal center responses, including TFH and IgA+ B cell development. TFH development is deficient in germfree mice and can be restored by feeding TLR2 agonists that activate T cell intrinsic MyD88 signaling. Loss of this pathway diminishes high affinity IgA targeting of the microbiota and fails to control the bacterial community, leading to worsened disease. Our findings identify that T cells converge innate and adaptive immune signals to coordinate IgA against the microbiota, constraining microbial community membership to promote symbiosis. PMID:25620548

Mast cells enhance T cell activation: Importance of mast cell-derived TNF

NASA Astrophysics Data System (ADS)

Nakae, Susumu; Suto, Hajime; Kakurai, Maki; Sedgwick, Jonathon D.; Tsai, Mindy; Galli, Stephen J.

2005-05-01

Mast cells are not only important effector cells in immediate hypersensitivity reactions and immune responses to pathogens but also can contribute to T cell-mediated disorders. However, the mechanisms by which mast cells might influence T cells in such settings are not fully understood. We find that mast cells can enhance proliferation and cytokine production in multiple T cell subsets. Mast cell-dependent enhancement of T cell activation can be promoted by FcRI-dependent mast cell activation, TNF production by both mast cells and T cells, and mast cell-T cell contact. However, at high concentrations of cells, mast cells can promote T cell activation independent of IgE or TNF. Finally, mast cells also can promote T cell activation by means of soluble factors. These findings identify multiple mechanisms by which mast cells can influence T cell proliferation and cytokine production. allergy | asthma | autoimmunity | cytokines | immune response

Modulation of T Cell Activation by Malignant Melanoma Initiating Cells

PubMed Central

Schatton, Tobias; Schütte, Ute; Frank, Natasha Y.; Zhan, Qian; Hoerning, André; Robles, Susanne C.; Zhou, Jun; Hodi, F. Stephen; Spagnoli, Giulio C.; Murphy, George F.; Frank, Markus H.

2010-01-01

Highly immunogenic cancers such as malignant melanoma are capable of inexorable tumor growth despite the presence of antitumor immunity. This raises the possibility that only a restricted minority of tumorigenic malignant cells might possess the phenotypic and functional characteristics to modulate tumor-directed immune activation. Here we provide evidence supporting this hypothesis, by demonstrating that tumorigenic ABCB5+ malignant melanoma-initiating cells (MMICs) possess the capacity to preferentially inhibit interleukin (IL)-2-dependent T cell activation and to support, in a B7.2-dependent manner, regulatory T (Treg) cell induction. Compared to melanoma bulk populations, ABCB5+ MMICs expressed lower levels of the major histocompatibility complex (MHC) class I, showed aberrant positivity for MHC class II, and exhibited lower expression levels of the melanoma-associated antigens (MAAs) MART-1, ML-IAP, NY-ESO-1, and MAGE-A. In addition, tumorigenic ABCB5+ subpopulations preferentially expressed the costimulatory molecules B7.2 and PD-1 in both established melanoma xenografts and clinical tumor specimens in vivo. In immune activation assays, ABCB5+ melanoma cells inhibited mitogen-dependent human peripheral blood mononuclear cell (PBMC) proliferation and IL-2 production more efficiently than ABCB5− populations. Moreover, coculture with ABCB5+ MMICs increased, in a B7.2 signalling-dependent manner, CD4+CD25+FoxP3+ Treg cell abundance and IL-10 production by mitogen-activated PBMCs. Consistent with these findings, ABCB5+ melanoma subsets also preferentially inhibited IL-2 production and induced IL-10 secretion by cocultured patient-derived, syngeneic PBMCs. Our findings identify novel T cell-modulatory functions of ABCB5+ melanoma subpopulations and suggest specific roles for MMICs in the evasion of antitumor immunity and in cancer immunotherapeutic resistance. PMID:20068175

Cell wall mannoprotein of Candida albicans induces cell cycle alternation and inhibits apoptosis of HaCaT cells via NF-κB signal pathway.

PubMed

Han, Yang; Jiang, Hang-Hang; Zhang, Yu-Jing; Hao, Xing-Jia; Sun, Yu-Zhe; Qi, Rui-Qun; Chen, Hong-Duo; Gao, Xing-Hua

2017-10-01

Candida albicans (C. albicans) is a commensal organism in human and a well-known dimorphic opportunistic pathogenic fungus. Though plenty of researches on the pathogenesis of C. albicans have been performed, the mechanism is not fully understood. The cell wall components of C. albicans have been documented to play important roles in its pathogenic processes. To further study the infectious mechanism of C. albicans, we investigated the potential functional role of its cell wall mannoprotein in cell cycle and apoptosis of HaCaT cells. We found that mannoprotein could promote the transition of cell cycle from G1/G0 to S phase, in which Cyclin D1, CDK4 and p-Rb, the major regulators of the cell cycle progression, showed significant upregulation, and CDKN1A (cyclin dependent kinase inhibitor 1A (p21)) showed significant downregulation. Mannoprotein also could inhibit apoptosis of HaCaT cells, which was well associated with increased expression of BCL2 (Bcl-2). Moreover, mannoprotein could increase the phosphorylation levels of RELA (p65) and NFKBIA (IκBα), as the key factors of NF-κB signal pathway in HaCaT cells, suggesting the activation of NF-κB signal pathway. Additionally, a NF-κB specific inhibitor, PDTC, could rescue the effect of mannoprotein on cell cycle and apoptosis of HaCaT cells, which suggested that mannoprotein could activate NF-κB signal pathway to mediate cell cycle alternation and inhibit apoptosis. Copyright © 2017. Published by Elsevier Ltd.

TCR signaling by conventional CD4+ T cells is required for optimal maintenance of peripheral regulatory T cell numbers.

PubMed

Leichner, Theresa M; Satake, Atsushi; Kambayashi, Taku

2016-06-01

To maintain immune tolerance, regulatory T cell (Treg) numbers must be closely indexed to the number of conventional T cells (Tconvs) so that an adequate Treg:Tconv ratio can be maintained. Two factors important in this process are the cytokine interleukin-2 (IL-2) and T cell receptor (TCR) stimulation by major histocompatibility complex class II (MHC-II). Here, we report that in addition to TCR stimulation of Tregs themselves, the maintenance of Tregs also requires TCR signaling by Tconvs. We found that Tconvs produce IL-2 in response to self-peptide-MHC-II complexes and that Tconvs possessing more highly self-reactive TCRs express more IL-2 at baseline. Furthermore, selective disruption of TCR signaling in Tconvs led to a trend toward decreased expression of IL-2 and attenuated their ability to maintain Treg numbers. These data suggest that in order to maintain an adequate Treg:Tconv ratio, Tregs are continuously indexed to self-peptide-MHC-II-induced TCR signaling of Tconvs. These results have implications in attempts to modulate immune tolerance, as Treg numbers adjust to the self-reactivity, and ultimately IL-2 production by the T cells around them.

The function of lysyl-tRNA synthetase and Ap4A as signaling regulators of MITF activity in FcepsilonRI-activated mast cells.

PubMed

Lee, Yu-Nee; Nechushtan, Hovav; Figov, Navah; Razin, Ehud

2004-02-01

The involvement of microphthalmia transcription factor (MITF) in the function of mast cells, melanocytes, and osteoclasts has recently started to be investigated in depth. In a previous study, we found Hint to be associated with MITF in mast cells and showed that it suppresses MITF's transcriptional activity. Here, we have found that lysyl-tRNA synthetase (LysRS) is also associated with MITF and forms a multicomplex with MITF and Hint. We have also shown that Ap4A, an endogenous molecule consisting of two adenosine linked by four phosphate which is known to be synthesized by LysRS, is accumulated intracellularily above 700 microM in IgE-Ag-activated mast cells, binds to Hint, liberates MITF, and thus leads to the activation of MITF-dependent gene expression. This implies that LysRS plays a key role via Ap4A as an important signaling molecule in MITF transcriptional activity.

Long noncoding RNA derived from CD244 signaling epigenetically controls CD8+ T-cell immune responses in tuberculosis infection

PubMed Central

Wang, Yang; Zhong, Huiling; Xie, Xiaodan; Chen, Crystal Y.; Huang, Dan; Shen, Ling; Zhang, Hui; Chen, Zheng W.; Zeng, Gucheng

2015-01-01

Molecular mechanisms for T-cell immune responses modulated by T cell-inhibitory molecules during tuberculosis (TB) infection remain unclear. Here, we show that active human TB infection up-regulates CD244 and CD244 signaling-associated molecules in CD8+ T cells and that blockade of CD244 signaling enhances production of IFN-γ and TNF-α. CD244 expression/signaling in TB correlates with high levels of a long noncoding RNA (lncRNA)-BC050410 [named as lncRNA-AS-GSTT1(1-72) or lncRNA-CD244] in the CD244+CD8+ T-cell subpopulation. CD244 signaling drives lncRNA-CD244 expression via sustaining a permissive chromatin state in the lncRNA-CD244 locus. By recruiting polycomb protein enhancer of zeste homolog 2 (EZH2) to infg/tnfa promoters, lncRNA-CD244 mediates H3K27 trimethylation at infg/tnfa loci toward repressive chromatin states and inhibits IFN-γ/TNF-α expression in CD8+ T cells. Such inhibition can be reversed by knock down of lncRNA-CD244. Interestingly, adoptive transfer of lncRNA-CD244–depressed CD8+ T cells to Mycobacterium tuberculosis (MTB)-infected mice reduced MTB infection and TB pathology compared with lncRNA-CD244–expressed controls. Thus, this work uncovers previously unidentified mechanisms in which T cell-inhibitory signaling and lncRNAs regulate T-cell responses and host defense against TB infection. PMID:26150504

βig-h3 Represses T-Cell Activation in Type 1 Diabetes.

PubMed

Patry, Maeva; Teinturier, Romain; Goehrig, Delphine; Zetu, Cornelia; Ripoche, Doriane; Kim, In-San; Bertolino, Philippe; Hennino, Ana

2015-12-01

βig-h3/TGF-βi is a secreted protein capable of binding to both extracellular matrix and cells. Human genetic studies recently revealed that in the tgfbi gene encoding for βig-h3, three single nucleotide polymorphisms were significantly associated with type 1 diabetes (T1D) risk. Pancreatic islets express βig-h3 in physiological conditions, but this expression is reduced in β-cell insult in T1D. Since the integrity of islets is destroyed by autoimmune T lymphocytes, we thought to investigate the impact of βig-h3 on T-cell activation. We show here that βig-h3 inhibits T-cell activation markers as well as cytotoxic molecule production as granzyme B and IFN-γ. Furthermore, βig-h3 inhibits early T-cell receptor signaling by repressing the activation of the early kinase protein Lck. Moreover, βig-h3-treated T cells are unable to induce T1D upon transfer in Rag2 knockout mice. Our study demonstrates for the first time that T-cell activation is modulated by βig-h3, an islet extracellular protein, in order to efficiently avoid autoimmune response. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

Analysis of T cell-replacing factor-like activity: potent induction of T helper activity for human B cells by residual concanavalin A and interleukin 2.

PubMed

Sauerwein, R W; Van der Meer, W G; Aarden, L A

1987-08-01

At least two factors with the capacity to induce IgM synthesis in human B cells were found to be present in the 15-20-kDa fraction of the supernatant of mononuclear cells activated with concanavalin A (Con A) and phorbol ester. Previously, it has been shown (Sauerwein, R. W. et al., Eur. J. Immunol. 1985. 15: 611) that interleukin 2 (IL2) in this material is able to induce T cell-dependent IgM secretion in normal B cells. Evidence was obtained for the presence of another factor distinct from IL2 that could replace T cells in the induction of B cell differentiation. We have analyzed this factor with the use of a neoplastic B cell population of prolymphocytic origin that was functionally nonresponsive to IL2. T cell-replacing factor (TRF)-like activity and IL2 could be separated by ion-exchange chromatography, although a small amount of IL2 was recovered in the TRF fractions. This small amount of IL2 was found to be crucial for the observed TRF activity. Moreover, a substantial amount of monomeric Con A was detected in the TRF preparation. Our studies show that Con A in the presence of IL2 can act as a potent inducer of helper function in lower numbers of T cells for normal and neoplastic B cells. Functional assays for T cell contamination in B cell suspensions are therefore of limited value because they are determined by the efficiency of the stimulating signal. Particularly in those B cell factor preparations, obtained from mitogen-activated T cells with an obligatory or unidentified role of IL2, the possible effect of a contaminating mitogen must be considered.

Membrane Transfer from Mononuclear Cells to Polymorphonuclear Neutrophils Transduces Cell Survival and Activation Signals in the Recipient Cells via Anti-Extrinsic Apoptotic and MAP Kinase Signaling Pathways.

PubMed

Li, Ko-Jen; Wu, Cheng-Han; Shen, Chieh-Yu; Kuo, Yu-Min; Yu, Chia-Li; Hsieh, Song-Chou

2016-01-01

The biological significance of membrane transfer (trogocytosis) between polymorphonuclear neutrophils (PMNs) and mononuclear cells (MNCs) remains unclear. We investigated the biological/immunological effects and molecular basis of trogocytosis among various immune cells in healthy individuals and patients with active systemic lupus erythematosus (SLE). By flow cytometry, we determined that molecules in the immunological synapse, including HLA class-I and-II, CD11b and LFA-1, along with CXCR1, are exchanged among autologous PMNs, CD4+ T cells, and U937 cells (monocytes) after cell-cell contact. Small interfering RNA knockdown of the integrin adhesion molecule CD11a in U937 unexpectedly enhanced the level of total membrane transfer from U937 to PMN cells. Functionally, phagocytosis and IL-8 production by PMNs were enhanced after co-culture with T cells. Total membrane transfer from CD4+ T to PMNs delayed PMN apoptosis by suppressing the extrinsic apoptotic molecules, BAX, MYC and caspase 8. This enhancement of activities of PMNs by T cells was found to be mediated via p38- and P44/42-Akt-MAP kinase pathways and inhibited by the actin-polymerization inhibitor, latrunculin B, the clathrin inhibitor, Pitstop-2, and human immunoglobulin G, but not by the caveolin inhibitor, methyl-β-cyclodextrin. In addition, membrane transfer from PMNs enhanced IL-2 production by recipient anti-CD3/anti-CD28 activated MNCs, and this was suppressed by inhibitors of mitogen-activated protein kinase (PD98059) and protein kinase C (Rottlerin). Of clinical significance, decreased total membrane transfer from PMNs to MNCs in patients with active SLE suppressed mononuclear IL-2 production. In conclusion, membrane transfer from MNCs to PMNs, mainly at the immunological synapse, transduces survival and activation signals to enhance PMN functions and is dependent on actin polymerization, clathrin activation, and Fcγ receptors, while membrane transfer from PMNs to MNCs depends on MAP kinase and

Effect of memory CD4+ T cells' signal transducer and activator of transcription (STATs) functional shift on cytokine-releasing properties in asthma.

PubMed

Chen, Zhihong; Pan, Jue; Jia, Yi; Li, Dandan; Min, Zhihui; Su, Xiaoqiong; Yuan, Honglei; Shen, Geng; Cao, Shengxuan; Zhu, Lei; Wang, Xiangdong

2017-02-01

Recent data have demonstrated that long-lived memory T cells are present in the human lung and can play significant roles in the pathogenesis of specific allergic and autoimmune diseases. However, most evidence has been obtained from mouse studies, and the potential roles of memory T cells in human allergic diseases, such as asthma, remain largely unknown. Thirty-three asthmatics, 26 chronic obstructive pulmonary disease (COPD) patients, and 22 healthy volunteers were enrolled in this study. Peripheral blood mononuclear cells (PBMCs) were isolated from the peripheral blood, and cell surface staining (CD4, CD45RO, CRTH2, CD62L, and CCR7) was performed for the detection of memory CD4 + T cells in blood. After stimulation with interleukin-27 (IL-27) or IL-4 for 15 min, the STAT1/STAT6 phosphorylation of memory CD4 + T cells was measured separately by flow cytometric techniques. The cytokine-releasing profiles after 6 days of culture under neutralization, T H 2, T H 2 + lipopolysaccharide (LPS), and T H 2 + house dust mite (HDM) conditions were detected by intracellular protein (IL-5, IL-17, and interferon (IFN)-γ) staining. Correlation analyses between the profile of memory CD4 + T cells and clinical characteristics of asthma were performed. The number of circulating memory CD4 + T (CD4 + Tm) cells in asthmatics was increased compared with that in the healthy subjects (48 ± 5.7 % vs. 32 ± 4.1 %, p < 0.05). Compared with COPD and healthy subjects, the phosphorylation of signal transducer and activator of transcription 1 (STAT1-py) was impaired in asthmatics, whereas the phosphorylation of signal transducer and activator of transcription 6 (STAT6-py) was slightly enhanced. This imbalance of STAT1-py/STAT6-py was attributed to T H 2 memory cells but not non-T H 2 memory cells in blood. The cytokine-releasing profiles of asthmatics was unique, specifically IL-5 high , IL-17 high , and IFN-r low , compared with those of COPD patients and healthy subjects

2B4-SAP signaling is required for the priming of naive CD8+ T cells by antigen-expressing B cells and B lymphoma cells

PubMed Central

2017-01-01

ABSTRACT Mutations in SH2D1A gene that encodes SAP (SLAM-associated protein) result in X-linked lymphoproliferative disease (XLP), a rare primary immunodeficiency disease defined by exquisite sensitivity to the B-lymphotropic Epstein–Barr virus (EBV) and B cell lymphomas. However, the precise mechanism of how the loss of SAP function contributes to extreme vulnerability to EBV and the development of B cell lymphomas remains unclear. Here, we investigate the hypothesis that SAP is critical for CD8+ T cell immune surveillance of antigen (Ag)-expressing B cells or B lymphoma cells under conditions of defined T cell receptor (TCR) signaling. Sh2d1a−/− CD8+ T cells exhibited greatly diminished proliferation relative to wild type when Ag-presenting-B cells or -B lymphoma cells served as the primary Ag-presenting cell (APC). By contrast, Sh2d1a−/− CD8+ T cells responded equivalently to wild-type CD8+ T cells when B cell-depleted splenocytes, melanoma cells or breast carcinoma cells performed Ag presentation. Through application of signaling lymphocyte activation molecule (SLAM) family receptor blocking antibodies or SLAM family receptor-deficient CD8+ T cells and APCs, we found that CD48 engagement on the B cell surface by 2B4 is crucial for initiating SAP-dependent signaling required for the Ag-driven CD8+ T cell proliferation and differentiation. Altogether, a pivotal role for SAP in promoting the expansion and differentiation of B cell-primed viral-specific naive CD8+ T cells may explain the selective immune deficiency of XLP patients to EBV and B cell lymphomas. PMID:28344876

2B4-SAP signaling is required for the priming of naive CD8+ T cells by antigen-expressing B cells and B lymphoma cells.

PubMed

Huang, Yu-Hsuan; Tsai, Kevin; Tan, Sara Y; Kang, Sohyeong; Ford, Mandy L; Harder, Kenneth W; Priatel, John J

2017-01-01

Mutations in SH2D1A gene that encodes SAP (SLAM-associated protein) result in X-linked lymphoproliferative disease (XLP), a rare primary immunodeficiency disease defined by exquisite sensitivity to the B-lymphotropic Epstein-Barr virus (EBV) and B cell lymphomas. However, the precise mechanism of how the loss of SAP function contributes to extreme vulnerability to EBV and the development of B cell lymphomas remains unclear. Here, we investigate the hypothesis that SAP is critical for CD8 + T cell immune surveillance of antigen (Ag)-expressing B cells or B lymphoma cells under conditions of defined T cell receptor (TCR) signaling. Sh2d1a - / - CD8 + T cells exhibited greatly diminished proliferation relative to wild type when Ag-presenting-B cells or -B lymphoma cells served as the primary Ag-presenting cell (APC). By contrast, Sh2d1a - / - CD8 + T cells responded equivalently to wild-type CD8 + T cells when B cell-depleted splenocytes, melanoma cells or breast carcinoma cells performed Ag presentation. Through application of signaling lymphocyte activation molecule (SLAM) family receptor blocking antibodies or SLAM family receptor-deficient CD8 + T cells and APCs, we found that CD48 engagement on the B cell surface by 2B4 is crucial for initiating SAP-dependent signaling required for the Ag-driven CD8 + T cell proliferation and differentiation. Altogether, a pivotal role for SAP in promoting the expansion and differentiation of B cell-primed viral-specific naive CD8 + T cells may explain the selective immune deficiency of XLP patients to EBV and B cell lymphomas.

Role of T Cell TGF-β Signaling in Intestinal Cytokine Responses and Helminthic Immune Modulation

PubMed Central

Ince, M. Nedim; Elliott, David E.; Setiawan, Tommy; Metwali, Ahmed; Blum, Arthur; Chen, Hung-lin; Urban, Joseph F.; Flavell, Richard A.; Weinstock, Joel V.

2010-01-01

Colonization with helminthic parasites induces mucosal regulatory cytokines, like IL-10 or TGF-β that are important in suppressing colitis. Helminths induce mucosal T cell IL-10 secretion and regulate lamina propria mononuclear cell Th1 cytokine generation in an IL-10 dependent manner in wild-type mice. Helminths also stimulate mucosal TGF-β release. As TGF-β exerts major regulatory effects on T lymphocytes, we investigated the role of T lymphocyte TGF-β signaling in helminthic modulation of intestinal immunity. T cell TGF-β signaling is interrupted in TGF-βRII DN mice by T cell-specific over-expression of a dominant negative TGF-β receptor II. We studied lamina propria mononuclear cell responses in wild-type and TGF-βRII DN mice that were uninfected or colonized with the nematode, Heligmosomoides polygyrus. Our results indicate an essential role of T cell TGF-β signaling in limiting mucosal Th1 and Th2 responses. Furthermore, we demonstrate that helminthic induction of intestinal T cell IL-10 secretion requires intact T cell TGF-β signaling pathway. Helminths fail to curtail robust, dysregulated intestinal Th1 cytokine production and chronic colitis in TGF-βRII DN mice. Thus, T cell TGF-β signaling is essential for helminthic stimulation of mucosal IL-10 production, helminthic modulation of intestinal interferon-γ generation and H. polygyrus-mediated suppression of chronic colitis. PMID:19544487

T-cell receptor signaling enhances transcriptional elongation from latent HIV proviruses by activating P-TEFb through an ERK-dependent pathway.

PubMed

Kim, Young Kyeung; Mbonye, Uri; Hokello, Joseph; Karn, Jonathan

2011-07-29

Latent human immunodeficiency virus (HIV) proviruses are thought to be primarily reactivated in vivo through stimulation of the T-cell receptor (TCR). Activation of the TCR induces multiple signal transduction pathways, leading to the ordered nuclear migration of the HIV transcription initiation factors NF-κB (nuclear factor κB) and NFAT (nuclear factor of activated T-cells), as well as potential effects on HIV transcriptional elongation. We have monitored the kinetics of proviral reactivation using chromatin immunoprecipitation assays to measure changes in the distribution of RNA polymerase II in the HIV provirus. Surprisingly, in contrast to TNF-α (tumor necrosis factor α) activation, where early transcription elongation is highly restricted due to rate-limiting concentrations of Tat, efficient and sustained HIV elongation and positive transcription elongation factor b (P-TEFb) recruitment are detected immediately after the activation of latent proviruses through the TCR. Inhibition of NFAT activation by cyclosporine had no effect on either HIV transcription initiation or elongation. However, examination of P-TEFb complexes by gel-filtration chromatography showed that TCR signaling led to the rapid dissociation of the large inactive P-TEFb:7SK RNP (small nuclear RNA 7SK ribonucleoprotein) complex and the release of active low-molecular-weight P-TEFb complexes. Both P-TEFb recruitment to the HIV long terminal repeat and enhanced HIV processivity were blocked by the ERK (extracellular-signal-regulated kinase) inhibitor U0126, but not by AKT (serine/threonine protein kinase Akt) and PI3K (phosphatidylinositol 3-kinase) inhibitors. In contrast to treatment with HMBA (hexamethylene bisacetamide) and DRB (5,6-dichlorobenzimidazole 1-β-ribofuranoside), which disrupt the large 7SK RNP complex but do not stimulate early HIV elongation, TCR signaling provides the first example of a physiological pathway that can shift the balance between the inactive P-TEFb pool and

Spatial and Temporal Control of T Cell Activation Using a Photoactivatable Agonist.

PubMed

Sanchez, Elisa; Huse, Morgan

2018-04-25

T lymphocytes engage in rapid, polarized signaling, occurring within minutes following TCR activation. This induces formation of the immunological synapse, a stereotyped cell-cell junction that regulates T cell activation and directionally targets effector responses. To study these processes effectively, an imaging approach that is tailored to capturing fast, polarized responses is necessary. This protocol describes such a system, which is based on a photoactivatable peptide-major histocompatibility complex (pMHC) that is non-stimulatory until it is exposed to ultraviolet light. Targeted decaging of this reagent during videomicroscopy experiments enables precise spatiotemporal control of TCR activation and high-resolution monitoring of subsequent cellular responses by total internal reflection (TIRF) imaging. This approach is also compatible with genetic and pharmacological perturbation strategies. This allows for the assembly of well-defined molecular pathways that link TCR signaling to the formation of the polarized cytoskeletal structures that underlie the immunological synapse.

Genomic profiling of Sézary Syndrome identifies alterations of key T-cell signaling and differentiation genes

PubMed Central

Wang, Linghua; Ni, Xiao; Covington, Kyle R.; Yang, Betty Y.; Shiu, Jessica; Zhang, Xiang; Xi, Liu; Meng, Qingchang; Langridge, Timothy; Drummond, Jennifer; Donehower, Lawrence A.; Doddapaneni, Harshavardhan; Muzny, Donna M.; Gibbs, Richard A.; Wheeler, David A.; Duvic, Madeleine

2016-01-01

Sézary Syndrome is a rare leukemic form of cutaneous T-cell lymphoma defined as erythroderma, adenopathy, and circulating atypical T-lymphocytes. It is rarely curable with poor prognosis. Here we present a multi-platform genomic analysis of 37 Sézary Syndrome patients that implicates dysregulation of the cell cycle checkpoint and T-cell signaling. Frequent somatic alterations were identified in TP53, CARD11, CCR4, PLCG1, CDKN2A, ARID1A, RPS6KA1, and ZEB1. Activating CCR4 and CARD11 mutations were detected in nearly a third of patients. ZEB1, a transcription repressor essential for T-cell differentiation, was deleted in over half of patients. IL32 and IL2RG were over-expressed in nearly all cases. Analysis of T-cell receptor Vβ and Vα expression revealed ongoing rearrangement of the receptors after the expansion of a malignant clone in one third of subjects. Our results demonstrate profound disruption of key signaling pathways in Sézary Syndrome and suggest potential targets for novel therapies. PMID:26551670

Loss of T-cadherin (CDH-13) regulates AKT signaling and desensitizes cells to apoptosis in melanoma.

PubMed

Bosserhoff, Anja K; Ellmann, Lisa; Quast, Annika S; Eberle, Juergen; Boyle, Glen M; Kuphal, Silke

2014-08-01

An understanding of signaling pathways is a basic requirement for the treatment of melanoma. Currently, kinases are at the center of melanoma therapies. According to our research, additional alternative molecules are equally important for development of melanoma. In this regard, cancer progression is, among other factors, driven by an altered adhesion via cadherins. For instance, the de-regulated expression of the adhesion molecule T-cadherin is found in various cancer types, including melanoma, and influences migration and invasion. T-cadherin is thought to affect cellular function largely through its signaling and not its adhesion properties because the molecule is anchored into the cell membrane by a glycosylphosphatidylinositol (GPI) moiety. However, detailed knowledge about the consequences of the loss of T-cadherin in melanoma is currently lacking. For this reason, we were interested in assessing which signaling pathways are initiated by T-cadherin. The tumor growth of subcutaneously injected T-cadherin-positive melanoma cells was diminished compared with T-cadherin-negative cells in nude mice. The difference in tumor volume was not due to decreased proliferation but rather due to increased apoptosis. After the expression of T-cadherin was induced, we detected V-AKT murine thymoma viral oncogene homolog (AKT) and FoxO3a hypophosphorylation accompanied by the downregulation of the antiapoptotic molecules BCL-2, BCL-x and Clusterin. Furthermore, we detected a diminished transcriptional activity of CREB and AP-1. We demonstrated that T-cadherin functions as a pro-apoptotic tumor suppressor that antagonizes AKT/CREB/AP-1/FoxO3a signaling, whereas NFκB, TCF/LEF and mTOR are not part of the T-cadherin signaling pathway. Notably, we found that the restoration of T-cadherin in melanoma cells causes sensitization to apoptosis induced by CD95/Fas antibody CH-11. © 2013 Wiley Periodicals, Inc.

The C-type lectin OCILRP2 costimulates EL4 T cell activation via the DAP12-Raf-MAP kinase pathway.

PubMed

Lou, Qiang; Zhang, Wei; Liu, Guangchao; Ma, Yuanfang

2014-01-01

OCILRP2 is a typical Type-II transmembrane protein that is selectively expressed in activated T lymphocytes, dendritic cells, and B cells and functions as a novel co-stimulator of T cell activation. However, the signaling pathways underlying OCILRP2 in T cell activation are still not completely understood. In this study, we found that the knockdown of OCILRP2 expression with shRNA or the blockage of its activity by an anti-OCILRP2 antagonist antibody reduced CD3/CD28-costimulated EL4 T cell viability and IL-2 production, inhibit Raf1, MAPK3, and MAPK8 activation, and impair NFAT and NF-κB transcriptional activities. Furthermore, immunoprecipitation results indicated that OCILRP2 could interact with the DAP12 protein, an adaptor containing an intracellular ITAM motif that can transduce signals to induce MAP kinase activation for T cell activation. Our data reveal that after binding with DAP12, OCILRP2 activates the Raf-MAP kinase pathways, resulting in T cell activation.

Regulation of T-cell receptor signalling by membrane microdomains

PubMed Central

Razzaq, Tahir M; Ozegbe, Patricia; Jury, Elizabeth C; Sembi, Phupinder; Blackwell, Nathan M; Kabouridis, Panagiotis S

2004-01-01

There is now considerable evidence suggesting that the plasma membrane of mammalian cells is compartmentalized by functional lipid raft microdomains. These structures are assemblies of specialized lipids and proteins and have been implicated in diverse biological functions. Analysis of their protein content using proteomics and other methods revealed enrichment of signalling proteins, suggesting a role for these domains in intracellular signalling. In T lymphocytes, structure/function experiments and complementary pharmacological studies have shown that raft microdomains control the localization and function of proteins which are components of signalling pathways regulated by the T-cell antigen receptor (TCR). Based on these studies, a model for TCR phosphorylation in lipid rafts is presented. However, despite substantial progress in the field, critical questions remain. For example, it is unclear if membrane rafts represent a homogeneous population and if their structure is modified upon TCR stimulation. In the future, proteomics and the parallel development of complementary analytical methods will undoubtedly contribute in further delineating the role of lipid rafts in signal transduction mechanisms. PMID:15554919

T cell costimulation by chemokine receptors.

PubMed

Molon, Barbara; Gri, Giorgia; Bettella, Monica; Gómez-Moutón, Concepción; Lanzavecchia, Antonio; Martínez-A, Carlos; Mañes, Santos; Viola, Antonella

2005-05-01

Signals mediated by chemokine receptors may compete with T cell receptor stop signals and determine the duration of T cell-antigen-presenting cell interactions. Here we show that during T cell stimulation by antigen-presenting cells, T cell chemokine receptors coupled to G(q) and/or G(11) protein were recruited to the immunological synapse by a G(i)-independent mechanism. When chemokine receptors were sequestered at the immunological synapse, T cells became insensitive to chemotactic gradients, formed more stable conjugates and finally responded with enhanced proliferation and cytokine production. We suggest that chemokine receptor trapping at the immunological synapse enhances T cell activation by improving T cell-antigen-presenting cell attraction and impeding the 'distraction' of successfully engaged T cells by other chemokine sources.

Curcumin Inhibits CD4+ T Cell Activation, but Augments CD69 Expression and TGF-β1-Mediated Generation of Regulatory T Cells at Late Phase

PubMed Central

Kim, Girak; Jang, Mi Seon; Son, Young Min; Seo, Min Ji; Ji, Sang Yun; Han, Seung Hyun; Jung, In Duk; Park, Yeong-Min; Jung, Hyun Jung; Yun, Cheol-Heui

2013-01-01

Background Curcumin is a promising candidate for a natural medicinal agent to treat chronic inflammatory diseases. Although CD4+ T cells have been implicated in the pathogenesis of chronic inflammation, whether curcumin directly regulates CD4+ T cells has not been definitively established. Here, we showed curcumin-mediated regulation of CD2/CD3/CD28-initiated CD4+ T cell activation in vitro. Methodology/Principal Findings Primary human CD4+ T cells were stimulated with anti-CD2/CD3/CD28 antibody-coated beads as an in vitro surrogate system for antigen presenting cell-T cell interaction and treated with curcumin. We found that curcumin suppresses CD2/CD3/CD28-initiated CD4+ T cell activation by inhibiting cell proliferation, differentiation and cytokine production. On the other hand, curcumin attenuated the spontaneous decline of CD69 expression and indirectly increased expression of CCR7, L-selectin and Transforming growth factor-β1 (TGF-β1) at the late phase of CD2/CD3/CD28-initiated T cell activation. Curcumin-mediated up-regulation of CD69 at late phase was associated with ERK1/2 signaling. Furthermore, TGF-β1 was involved in curcumin-mediated regulation of T cell activation and late-phase generation of regulatory T cells. Conclusions/Significance Curcumin not merely blocks, but regulates CD2/CD3/CD28-initiated CD4+ T cell activation by augmenting CD69, CCR7, L-selectin and TGF-β1 expression followed by regulatory T cell generation. These results suggest that curcumin could directly reduce T cell-dependent inflammatory stress by modulating CD4+ T cell activation at multiple levels. PMID:23658623

cAMP is an essential signal in the induction of antibody production by B cells but inhibits helper function of T cells.

PubMed

Gilbert, K M; Hoffmann, M K

1985-09-01

Dibutyryl cAMP and IL 1 were found to stimulate antigen-specific and polyclonal antibody production when added together to cultures of highly purified B cells. We propose that IL 1 and an elevation in cytoplasmic cAMP represent minimal signal requirements for B cell activation. In contrast to its effect on B cells, dibutyryl cAMP inhibited helper T cell activity. Cyclic AMP suppressed the production of IL 2 and T cell replacing factor (TRF) by T cells and thus abrogated the ability of helper T cells to enhance SRBC-specific antibody production by B cells. Cyclic AMP did not inhibit the generation by T cells of B cell growth factor (BCGF). BCGF, not normally detected in Con A supernatant, was found in the culture supernatant of spleen cells that were stimulated with Con A in the presence of cAMP. Our findings indicate that cAMP blocks the production of an inhibitor of BCGF activity. cAMP had no effect on the production by macrophages of IL 1.

A Proteomic View at T Cell Costimulation

PubMed Central

Hombach, Andreas A.; Recktenwald, Christian V.; Dressler, Sven P.; Abken, Hinrich; Seliger, Barbara

2012-01-01

The “two-signal paradigm” in T cell activation predicts that the cooperation of “signal 1,” provided by the T cell receptor (TCR) through engagement of major histocompatility complex (MHC)-presented peptide, with “signal 2″ provided by costimulatory molecules, the prototype of which is CD28, is required to induce T cell effector functions. While the individual signalling pathways are well understood, little is known about global changes in the proteome pattern during TCR/CD28-mediated activation. Therefore, comparative 2-DE-based proteome analyses of CD3+ CD69- resting T cells versus cells incubated with (i) the agonistic anti-CD3 antibody OKT3 mimicking signal 1 in absence or presence of IL-2 and/or with (ii) the agonistic antibody 15E8 triggering CD28-mediated signaling were performed. Differentially regulated spots were defined leading to the identification of proteins involved in the regulation of the metabolism, shaping and maintenance of the cytoskeleton and signal transduction. Representative members of the differentially expressed protein families, such as calmodulin (CALM), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), L-lactate dehydrogenase (LDH), Rho GDP-dissociation inhibitor 2 (GDIR2), and platelet basic protein (CXCL7), were independently verified by flow cytometry. Data provide a detailed map of individual protein alterations at the global proteome level in response to TCR/CD28-mediated T cell activation. PMID:22539942

Role of two adaptor molecules SLP-76 and LAT in the PI3K signaling pathway in activated T cells.

PubMed

Shim, Eun Kyung; Jung, Seung Hee; Lee, Jong Ran

2011-03-01

Previously, we identified p85, a subunit of PI3K, as one of the molecules that interacts with the N-terminal region of Src homology 2 domain-containing leukocyte protein of 76 kDa (SLP-76). We also demonstrated that tyrosine phosphorylation either at the 113 and/or 128 position is sufficient for the association of SLP-76 with the Src homology 2 domain near the N terminus of p85. The present study further examines the role of the association of these two molecules on the activation of PI3K signaling cascade. Experiments were done to determine the role of SLP-76, either wild-type, tyrosine mutants, or membrane-targeted forms of various SLP-76 constructs, on the membrane localization and phosphorylation of Akt, which is an event downstream of PI3K activation. Reconstitution studies with these various SLP-76 constructs in a Jurkat variant cell line that lacks SLP-76 or linker for activation of T cells (LAT) show that the activation of PI3K pathway following TCR ligation requires both SLP-76 and LAT adaptor proteins. The results suggest that SLP-76 associates with p85 after T cell activation and that LAT recruits this complex to the membrane, leading to Akt activation.

Attenuation of T cell receptor signaling by serine phosphorylation-mediated lysine 30 ubiquitination of SLP-76 protein.

PubMed

Wang, Xiaohong; Li, Ju-Pi; Chiu, Li-Li; Lan, Joung-Liang; Chen, Der-Yuan; Boomer, Jonathan; Tan, Tse-Hua

2012-10-05

SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa) is an adaptor protein that is essential for T cell development and T cell receptor (TCR) signaling activation. Previous studies have identified an important negative feedback regulation of SLP-76 by HPK1 (hematopoietic progenitor kinase 1; MAP4K1)-induced Ser-376 phosphorylation. Ser-376 phosphorylation of SLP-76 mediates 14-3-3 binding, resulting in the attenuation of SLP-76 activation and downstream signaling; however, the underlying mechanism of this action remains unknown. Here, we report that phosphorylated SLP-76 is ubiquitinated and targeted for proteasomal degradation during TCR signaling. SLP-76 ubiquitination is mediated by Ser-376 phosphorylation. Furthermore, Lys-30 is identified as a ubiquitination site of SLP-76. Loss of Lys-30 ubiquitination of SLP-76 results in enhanced anti-CD3 antibody-induced ERK and JNK activation. These results reveal a novel regulation mechanism of SLP-76 by ubiquitination and proteasomal degradation of activated SLP-76, which is mediated by Ser-376 phosphorylation, leading to down-regulation of TCR signaling.

Attenuation of T Cell Receptor Signaling by Serine Phosphorylation-mediated Lysine 30 Ubiquitination of SLP-76 Protein*

PubMed Central

Wang, Xiaohong; Li, Ju-Pi; Chiu, Li-Li; Lan, Joung-Liang; Chen, Der-Yuan; Boomer, Jonathan; Tan, Tse-Hua

2012-01-01

SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa) is an adaptor protein that is essential for T cell development and T cell receptor (TCR) signaling activation. Previous studies have identified an important negative feedback regulation of SLP-76 by HPK1 (hematopoietic progenitor kinase 1; MAP4K1)-induced Ser-376 phosphorylation. Ser-376 phosphorylation of SLP-76 mediates 14-3-3 binding, resulting in the attenuation of SLP-76 activation and downstream signaling; however, the underlying mechanism of this action remains unknown. Here, we report that phosphorylated SLP-76 is ubiquitinated and targeted for proteasomal degradation during TCR signaling. SLP-76 ubiquitination is mediated by Ser-376 phosphorylation. Furthermore, Lys-30 is identified as a ubiquitination site of SLP-76. Loss of Lys-30 ubiquitination of SLP-76 results in enhanced anti-CD3 antibody-induced ERK and JNK activation. These results reveal a novel regulation mechanism of SLP-76 by ubiquitination and proteasomal degradation of activated SLP-76, which is mediated by Ser-376 phosphorylation, leading to down-regulation of TCR signaling. PMID:22902619

Towards immunotherapy with redirected T cells in a large animal model: Ex vivo activation, expansion, and genetic modification of canine T cells

PubMed Central

Mata, Melinda; Vera, Juan; Gerken, Claudia; Rooney, Cliona M.; Miller, Tasha; Pfent, Catherine; Wang, Lisa L.; Wilson-Robles, Heather M.; Gottschalk, Stephen

2014-01-01

Adoptive transfer of T cells expressing chimeric antigen receptors (CARs) has shown promising anti-tumor activity in early phase clinical studies, especially for hematological malignancies. However, most preclinical models do not reliably mimic human disease. We reasoned that developing an adoptive T-cell therapy approach for spontaneous osteosarcoma (OS) occurring in dogs would more closely reproduce the condition in human cancer. To generate CAR-expressing canine T cells we developed expansion and transduction protocols that allow for the generation of sufficient numbers of CAR-expressing canine T cells for future clinical studies in dogs within 2 weeks of ex vivo culture. To evaluate the functionality of CAR-expressing canine T cells we targeted HER2-positive OS. We demonstrate that canine OS is positive for HER2, and that canine T cells expressing a HER2-specific CAR with human-derived transmembrane and CD28.ζ signaling domains recognize and kill HER2-positive canine OS cell lines in an antigen-dependent manner. To reduce the potential immunogenicity of the CAR we evaluated a CAR with canine-derived transmembrane and signaling domains, and found no functional difference between human and canine CARs. Hence, we have successfully developed a strategy to generate CAR-expressing canine T cells for future preclinical studies in dogs. Testing T-cell therapies in an immunocompetent, outbred animal model may improve our ability to predict their safety and efficacy prior to conducting studies in humans. PMID:25198528

Roles of calpain-calpastatin system (CCS) in human T cell activation.

PubMed

Mikosik, Anna; Jasiulewicz, Aleksandra; Daca, Agnieszka; Henc, Izabella; Frąckowiak, Joanna E; Ruckemann-Dziurdzińska, Katarzyna; Foerster, Jerzy; Le Page, Aurelie; Bryl, Ewa; Fulop, Tamas; Witkowski, Jacek M

2016-11-22

The immune response is determined by the speed of the T cell reaction to antigens assured by a state of readiness for proliferation and cytokine secretion. Proliferation, apoptosis and motion of many cell types are controlled by cytoplasmic proteases - µ- and m-calpain - and their inhibitor calpastatin, together forming the "calpain-calpastatin system" (CCS), assumed to modify their targets only upon activation-dependent cytoplasmic Ca2+ increase. Contrastingly to this notion, using quantitative real time PCR and semiquantitative flow cytometry respectively, we show here that the CCS genes are constitutively expressed, and that both calpains are constitutively active in resting, circulating human CD4+ and CD8+ lymphocytes. Furthermore, we demonstrate that calpain inhibition in the resting T cells prevents them from proliferation in vitro and greatly reduces secretion of multiple cytokines. The mechanistic reason for these effects of calpain inhibition on T cell functions might be the demonstrated significant reduction of the expression of active (phosphorylated) upstream signalling molecules, including the phospholipase C gamma, p56Lck and NFκB, in the inhibitor-treated cells. Thus, we propose that the constitutive, self-regulatory calpain-calpastatin system activity in resting human T cells is a necessary, controlling element of their readiness for complex and effective response to antigenic challenge.

Repression of BIM mediates survival signaling by MYC and AKT in high-risk T-cell acute lymphoblastic leukemia.

PubMed

Reynolds, C; Roderick, J E; LaBelle, J L; Bird, G; Mathieu, R; Bodaar, K; Colon, D; Pyati, U; Stevenson, K E; Qi, J; Harris, M; Silverman, L B; Sallan, S E; Bradner, J E; Neuberg, D S; Look, A T; Walensky, L D; Kelliher, M A; Gutierrez, A

2014-09-01

Treatment resistance in T-cell acute lymphoblastic leukemia (T-ALL) is associated with phosphatase and tensin homolog (PTEN) deletions and resultant phosphatidylinositol 3'-kinase (PI3K)-AKT pathway activation, as well as MYC overexpression, and these pathways repress mitochondrial apoptosis in established T-lymphoblasts through poorly defined mechanisms. Normal T-cell progenitors are hypersensitive to mitochondrial apoptosis, a phenotype that is dependent on the expression of proapoptotic BIM. In a conditional zebrafish model, MYC downregulation induced BIM expression in T-lymphoblasts, an effect that was blunted by expression of constitutively active AKT. In human T-ALL cell lines and treatment-resistant patient samples, treatment with MYC or PI3K-AKT pathway inhibitors each induced BIM upregulation and apoptosis, indicating that BIM is repressed downstream of MYC and PI3K-AKT in high-risk T-ALL. Restoring BIM function in human T-ALL cells using a stapled peptide mimetic of the BIM BH3 domain had therapeutic activity, indicating that BIM repression is required for T-ALL viability. In the zebrafish model, where MYC downregulation induces T-ALL regression via mitochondrial apoptosis, T-ALL persisted despite MYC downregulation in 10% of bim wild-type zebrafish, 18% of bim heterozygotes and in 33% of bim homozygous mutants (P=0.017). We conclude that downregulation of BIM represents a key survival signal downstream of oncogenic MYC and PI3K-AKT signaling in treatment-resistant T-ALL.

The clerodane diterpene casearin J induces apoptosis of T-ALL cells through SERCA inhibition, oxidative stress, and interference with Notch1 signaling

PubMed Central

De Ford, C; Heidersdorf, B; Haun, F; Murillo, R; Friedrich, T; Borner, C; Merfort, I

2016-01-01

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy that preferentially affects children and adolescents. Over 50% of human T-ALLs possess activating mutations of Notch1. The clerodane diterpene casearin J (CJ) is a natural product that inhibits the sarcoendoplasmatic reticulum calcium ATPase (SERCA) pump and induces cell death in leukemia cells, but the molecular mechanism of cytotoxicity remains poorly understood. Here we show that owing to SERCA pump inhibition, CJ induces depletion of the endoplasmic reticulum calcium pools, oxidative stress, and apoptosis via the intrinsic signaling pathway. Moreover, Notch1 signaling is reduced in T-ALL cells with auto-activating mutations in the HD-domain of Notch1, but not in cells that do not depend on Notch1 signaling. CJ also provoked a slight activation of NF-κB, and consistent with this notion a combined treatment of CJ and the NF-κB inhibitor parthenolide (Pt) led to a remarkable synergistic cell death in T-ALL cells. Altogether, our data support the concept that inhibition of the SERCA pump may be a novel strategy for the treatment of T-ALL with HD-domain-mutant Notch1 receptors and that additional treatment with the NF-κB inhibitor parthenolide may have further therapeutic benefits. PMID:26821066

β-Arrestin-2-Dependent Signaling Promotes CCR4-mediated Chemotaxis of Murine T-Helper Type 2 Cells.

PubMed

Lin, Rui; Choi, Yeon Ho; Zidar, David A; Walker, Julia K L

2018-06-01

Allergic asthma is a complex inflammatory disease that leads to significant healthcare costs and reduction in quality of life. Although many cell types are implicated in the pathogenesis of asthma, CD4 + T-helper cell type 2 (Th2) cells are centrally involved. We previously reported that the asthma phenotype is virtually absent in ovalbumin-sensitized and -challenged mice that lack global expression of β-arrestin (β-arr)-2 and that CD4 + T cells from these mice displayed significantly reduced CCL22-mediated chemotaxis. Because CCL22-mediated activation of CCR4 plays a role in Th2 cell regulation in asthmatic inflammation, we hypothesized that CCR4-mediated migration of CD4 + Th2 cells to the lung in asthma may use β-arr-dependent signaling. To test this hypothesis, we assessed the effect of various signaling inhibitors on CCL22-induced chemotaxis using in vitro-polarized primary CD4 + Th2 cells from β-arr2-knockout and wild-type mice. Our results show, for the first time, that CCL22-induced, CCR4-mediated Th2 cell chemotaxis is dependent, in part, on a β-arr2-dependent signaling pathway. In addition, we show that this chemotactic signaling mechanism involves activation of P-p38 and Rho-associated protein kinase. These findings point to a proinflammatory role for β-arr2-dependent signaling and support β-arr2 as a novel therapeutic target in asthma.

Termination of T cell priming relies on a phase of unresponsiveness promoting disengagement from APCs and T cell division.

PubMed

Bohineust, Armelle; Garcia, Zacarias; Beuneu, Hélène; Lemaître, Fabrice; Bousso, Philippe

2018-05-07

T cells are primed in secondary lymphoid organs by establishing stable interactions with antigen-presenting cells (APCs). However, the cellular mechanisms underlying the termination of T cell priming and the initiation of clonal expansion remain largely unknown. Using intravital imaging, we observed that T cells typically divide without being associated to APCs. Supporting these findings, we demonstrate that recently activated T cells have an intrinsic defect in establishing stable contacts with APCs, a feature that was reflected by a blunted capacity to stop upon T cell receptor (TCR) engagement. T cell unresponsiveness was caused, in part, by a general block in extracellular calcium entry. Forcing TCR signals in activated T cells antagonized cell division, suggesting that T cell hyporesponsiveness acts as a safeguard mechanism against signals detrimental to mitosis. We propose that transient unresponsiveness represents an essential phase of T cell priming that promotes T cell disengagement from APCs and favors effective clonal expansion. © 2018 Bohineust et al.

In TCR-Stimulated T-cells, N-ras Regulates Specific Genes and Signal Transduction Pathways

PubMed Central

Lynch, Stephen J.; Zavadil, Jiri; Pellicer, Angel

2013-01-01

It has been recently shown that N-ras plays a preferential role in immune cell development and function; specifically: N-ras, but not H-ras or K-ras, could be activated at and signal from the Golgi membrane of immune cells following a low level T-cell receptor stimulus. The goal of our studies was to test the hypothesis that N-ras and H-ras played distinct roles in immune cells at the level of the transcriptome. First, we showed via mRNA expression profiling that there were over four hundred genes that were uniquely differentially regulated either by N-ras or H-ras, which provided strong evidence in favor of the hypothesis that N-ras and H-ras have distinct functions in immune cells. We next characterized the genes that were differentially regulated by N-ras in T cells following a low-level T-cell receptor stimulus. Of the large pool of candidate genes that were differentially regulated by N-ras downstream of TCR ligation, four genes were verified in qRT-PCR-based validation experiments (Dntt, Slc9a6, Chst1, and Lars2). Finally, although there was little overlap between individual genes that were regulated by N-ras in unstimulated thymocytes and stimulated CD4+ T-cells, there was a nearly complete correspondence between the signaling pathways that were regulated by N-ras in these two immune cell types. PMID:23755101

Curcumin Suppresses T Cell Activation by Blocking Ca2+ Mobilization and Nuclear Factor of Activated T Cells (NFAT) Activation

PubMed Central

Kliem, Christian; Merling, Anette; Giaisi, Marco; Köhler, Rebecca; Krammer, Peter H.; Li-Weber, Min

2012-01-01

Curcumin is the active ingredient of the spice turmeric and has been shown to have a number of pharmacologic and therapeutic activities including antioxidant, anti-microbial, anti-inflammatory, and anti-carcinogenic properties. The anti-inflammatory effects of curcumin have primarily been attributed to its inhibitory effect on NF-κB activity due to redox regulation. In this study, we show that curcumin is an immunosuppressive phytochemical that blocks T cell-activation-induced Ca2+ mobilization with IC50 = ∼12.5 μm and thereby prevents NFAT activation and NFAT-regulated cytokine expression. This finding provides a new mechanism for curcumin-mediated anti-inflammatory and immunosuppressive function. We also show that curcumin can synergize with CsA to enhance immunosuppressive activity because of different inhibitory mechanisms. Furthermore, because Ca2+ is also the secondary messenger crucial for the TCR-induced NF-κB signaling pathway, our finding also provides another mechanism by which curcumin suppresses NF-κB activation. PMID:22303019

NKL homeobox gene activities in hematopoietic stem cells, T-cell development and T-cell leukemia.

PubMed

Nagel, Stefan; Pommerenke, Claudia; Scherr, Michaela; Meyer, Corinna; Kaufmann, Maren; Battmer, Karin; MacLeod, Roderick A F; Drexler, Hans G

2017-01-01

T-cell acute lymphoblastic leukemia (T-ALL) cells represent developmentally arrested T-cell progenitors, subsets of which aberrantly express homeobox genes of the NKL subclass, including TLX1, TLX3, NKX2-1, NKX2-5, NKX3-1 and MSX1. Here, we analyzed the transcriptional landscape of all 48 members of the NKL homeobox gene subclass in CD34+ hematopoietic stem and progenitor cells (HSPCs) and during lymphopoiesis, identifying activities of nine particular genes. Four of these were expressed in HSPCs (HHEX, HLX1, NKX2-3 and NKX3-1) and three in common lymphoid progenitors (HHEX, HLX1 and MSX1). Interestingly, our data indicated downregulation of NKL homeobox gene transcripts in late progenitors and mature T-cells, a phenomenon which might explain the oncogenic impact of this group of genes in T-ALL. Using MSX1-expressing T-ALL cell lines as models, we showed that HHEX activates while HLX1, NKX2-3 and NKX3-1 repress MSX1 transcription, demonstrating the mutual regulation and differential activities of these homeobox genes. Analysis of a public T-ALL expression profiling data set comprising 117 patient samples identified 20 aberrantly activated members of the NKL subclass, extending the number of known NKL homeobox oncogene candidates. While 7/20 genes were also active during hematopoiesis, the remaining 13 showed ectopic expression. Finally, comparative analyses of T-ALL patient and cell line profiling data of NKL-positive and NKL-negative samples indicated absence of shared target genes but instead highlighted deregulation of apoptosis as common oncogenic effect. Taken together, we present a comprehensive survey of NKL homeobox genes in early hematopoiesis, T-cell development and T-ALL, showing that these genes generate an NKL-code for the diverse stages of lymphoid development which might be fundamental for regular differentiation.

NKL homeobox gene activities in hematopoietic stem cells, T-cell development and T-cell leukemia

PubMed Central

Pommerenke, Claudia; Scherr, Michaela; Meyer, Corinna; Kaufmann, Maren; Battmer, Karin; MacLeod, Roderick A. F.; Drexler, Hans G.

2017-01-01

T-cell acute lymphoblastic leukemia (T-ALL) cells represent developmentally arrested T-cell progenitors, subsets of which aberrantly express homeobox genes of the NKL subclass, including TLX1, TLX3, NKX2-1, NKX2-5, NKX3-1 and MSX1. Here, we analyzed the transcriptional landscape of all 48 members of the NKL homeobox gene subclass in CD34+ hematopoietic stem and progenitor cells (HSPCs) and during lymphopoiesis, identifying activities of nine particular genes. Four of these were expressed in HSPCs (HHEX, HLX1, NKX2-3 and NKX3-1) and three in common lymphoid progenitors (HHEX, HLX1 and MSX1). Interestingly, our data indicated downregulation of NKL homeobox gene transcripts in late progenitors and mature T-cells, a phenomenon which might explain the oncogenic impact of this group of genes in T-ALL. Using MSX1-expressing T-ALL cell lines as models, we showed that HHEX activates while HLX1, NKX2-3 and NKX3-1 repress MSX1 transcription, demonstrating the mutual regulation and differential activities of these homeobox genes. Analysis of a public T-ALL expression profiling data set comprising 117 patient samples identified 20 aberrantly activated members of the NKL subclass, extending the number of known NKL homeobox oncogene candidates. While 7/20 genes were also active during hematopoiesis, the remaining 13 showed ectopic expression. Finally, comparative analyses of T-ALL patient and cell line profiling data of NKL-positive and NKL-negative samples indicated absence of shared target genes but instead highlighted deregulation of apoptosis as common oncogenic effect. Taken together, we present a comprehensive survey of NKL homeobox genes in early hematopoiesis, T-cell development and T-ALL, showing that these genes generate an NKL-code for the diverse stages of lymphoid development which might be fundamental for regular differentiation. PMID:28151996

Strategies for enhancing adoptive T-cell immunotherapy against solid tumors using engineered cytokine signaling and other modalities.

PubMed

Shum, Thomas; Kruse, Robert L; Rooney, Cliona M

2018-05-04

Cancer therapy has been transformed by the demonstration that tumor-specific T-cells can eliminate tumor cells in a clinical setting with minimal long-term toxicity. However, significant success in the treatment of leukemia and lymphoma with T-cells using native receptors or redirected with chimeric antigen receptors (CARs) has not been recapitulated in the treatment of solid tumors. This lack of success is likely related to the paucity of costimulatory and cytokine signaling available in solid tumors, in addition to a range of inhibitory mechanisms. Areas covered: We summarize the latest developments in engineered T-cell immunotherapy, describe the limitations of these approaches in treating solid tumors, and finally highlight several strategies that may be useful in mediating solid tumor responses in the future, while also ensuring safety of engineered cells. Expert opinion: CAR-T therapies require further engineering to achieve their potential against solid tumors. Facilitating cytokine signaling in CAR T-cells appears to be essential in achieving better responses. However, the engineering of T-cells with potentially unchecked proliferation and potency raises the question of whether the simultaneous combination of enhancements will prove safe, necessitating continued advancements in regulating CAR-T activity at the tumor site and methods to safely switch off these engineered cells.

The C-Type Lectin OCILRP2 Costimulates EL4 T Cell Activation via the DAP12-Raf-MAP Kinase Pathway

PubMed Central

Lou, Qiang; Zhang, Wei; Liu, Guangchao; Ma, Yuanfang

2014-01-01

OCILRP2 is a typical Type-II transmembrane protein that is selectively expressed in activated T lymphocytes, dendritic cells, and B cells and functions as a novel co-stimulator of T cell activation. However, the signaling pathways underlying OCILRP2 in T cell activation are still not completely understood. In this study, we found that the knockdown of OCILRP2 expression with shRNA or the blockage of its activity by an anti-OCILRP2 antagonist antibody reduced CD3/CD28-costimulated EL4 T cell viability and IL-2 production, inhibit Raf1, MAPK3, and MAPK8 activation, and impair NFAT and NF-κB transcriptional activities. Furthermore, immunoprecipitation results indicated that OCILRP2 could interact with the DAP12 protein, an adaptor containing an intracellular ITAM motif that can transduce signals to induce MAP kinase activation for T cell activation. Our data reveal that after binding with DAP12, OCILRP2 activates the Raf-MAP kinase pathways, resulting in T cell activation. PMID:25411776

GARP-TGF-β complexes negatively regulate regulatory T cell development and maintenance of peripheral CD4+ T cells in vivo.

PubMed

Zhou, Angela X; Kozhaya, Lina; Fujii, Hodaka; Unutmaz, Derya

2013-05-15

The role of surface-bound TGF-β on regulatory T cells (Tregs) and the mechanisms that mediate its functions are not well defined. We recently identified a cell-surface molecule called Glycoprotein A Repetitions Predominant (GARP), which is expressed specifically on activated Tregs and was found to bind latent TGF-β and mediate a portion of Treg suppressive activity in vitro. In this article, we address the role of GARP in regulating Treg and conventional T cell development and immune suppression in vivo using a transgenic mouse expressing GARP on all T cells. We found that, despite forced expression of GARP on all T cells, stimulation through the TCR was required for efficient localization of GARP to the cell surface. In addition, IL-2 signals enhanced GARP cell surface expression specifically on Tregs. GARP-transgenic CD4(+) T cells and Tregs, especially those expressing higher levels of GARP, were significantly reduced in the periphery. Mature Tregs, but not conventional CD4(+) T cells, were also reduced in the thymus. CD4(+) T cell reduction was more pronounced within the effector/memory subset, especially as the mouse aged. In addition, GARP-overexpressing CD4(+) T cells stimulated through the TCR displayed reduced proliferative capacity, which was restored by inhibiting TGF-β signaling. Furthermore, inhibiting TGF-β signals greatly enhanced surface expression of GARP on Tregs and blocked the induction of Foxp3 in activated CD4(+) T cells overexpressing GARP. These findings suggest a role for GARP in natural and induced Treg development through activation of bound latent TGF-β and signaling, which negatively regulates GARP expression on Tregs.

Protein Tyrosine Phosphatase PRL2 Mediates Notch and Kit Signals in Early T Cell Progenitors.

PubMed

Kobayashi, Michihiro; Nabinger, Sarah C; Bai, Yunpeng; Yoshimoto, Momoko; Gao, Rui; Chen, Sisi; Yao, Chonghua; Dong, Yuanshu; Zhang, Lujuan; Rodriguez, Sonia; Yashiro-Ohtani, Yumi; Pear, Warren S; Carlesso, Nadia; Yoder, Mervin C; Kapur, Reuben; Kaplan, Mark H; Daniel Lacorazza, Hugo; Zhang, Zhong-Yin; Liu, Yan

2017-04-01

The molecular pathways regulating lymphoid priming, fate, and development of multipotent bone marrow hematopoietic stem and progenitor cells (HSPCs) that continuously feed thymic progenitors remain largely unknown. While Notch signal is indispensable for T cell specification and differentiation, the downstream effectors are not well understood. PRL2, a protein tyrosine phosphatase that regulates hematopoietic stem cell proliferation and self-renewal, is highly expressed in murine thymocyte progenitors. Here we demonstrate that protein tyrosine phosphatase PRL2 and receptor tyrosine kinase c-Kit are critical downstream targets and effectors of the canonical Notch/RBPJ pathway in early T cell progenitors. While PRL2 deficiency resulted in moderate defects of thymopoiesis in the steady state, de novo generation of T cells from Prl2 null hematopoietic stem cells was significantly reduced following transplantation. Prl2 null HSPCs also showed impaired T cell differentiation in vitro. We found that Notch/RBPJ signaling upregulated PRL2 as well as c-Kit expression in T cell progenitors. Further, PRL2 sustains Notch-mediated c-Kit expression and enhances stem cell factor/c-Kit signaling in T cell progenitors, promoting effective DN1-DN2 transition. Thus, we have identified a critical role for PRL2 phosphatase in mediating Notch and c-Kit signals in early T cell progenitors. Stem Cells 2017;35:1053-1064. © 2016 AlphaMed Press.

Optimization of Dendritic Cell-Mediated Cytotoxic T-Cell Activation by Tracking of Dendritic Cell Migration Using Reporter Gene Imaging.

PubMed

Lee, Hongje; Lee, Ho Won; La Lee, You; Jeon, Yong Hyun; Jeong, Shin Young; Lee, Sang-Woo; Lee, Jaetae; Ahn, Byeong-Cheol

2018-06-01

The aim of this study is to optimize the dendritic cell (DC)-mediated T-cell activation using reporter gene imaging and flow cytometric analysis in living mice. A murine dendritic cell line (DC2.4) co-expressing effluc and Thy1.1 genes were established by transfection with retroviral vectors. Thy1.1 positive cells were sorted by magnetic bead separation system (DC2.4/effluc). Cell proliferation assay and phenotype analysis to determine the effects of gene transduction on the function of dendritic cells between parental DC2.4 and DC2.4/effluc were performed. To optimize the DC-mediated immune response by cell number or frequency, different cell numbers (5 × 10 5 , 1 × 10 6 , and 2 × 10 6  DC2.4/effluc) or different frequencies of DC2.4/effluc (first, second, and third injections) were injected in the right footpad of mice. The migration of the DC2.4/effluc into the draining popliteal lymph node of mice was monitored by bioluminescence imaging (BLI). Flow cytometric analysis was performed with splenocytes to determine the cytotoxic T-cell population after injection of DC2.4/effluc. Parental DC2.4 and DC2.4/effluc exhibit no significant differences in their proliferation and phenotype. BLI signals were observed in the draining popliteal lymph node at day 1 after injection of DC2.4/effluc in 1 × 10 6 and 2 × 10 6 cells-injected groups. The highest BLI signal intensity was detected in 2 × 10 6 cells-injected mice. On day 11, the BLI signal was detected in only 2 × 10 6 cell-injected group but not in other groups. Optimized cell numbers (2 × 10 6 ) were injected in three animal groups with a different frequency (first, second, and third injection groups). The BLI signal was detected at day 1 and maintained until day 7 in the first injection group, but there is low signal intensity in the second and the third injection groups. Although the expression levels of Thy1.1 gene in the first injection group were very high, there reveals no expression of

T cell activation responses are differentially regulated during clinorotation and in spaceflight

NASA Technical Reports Server (NTRS)

Hashemi, B. B.; Penkala, J. E.; Vens, C.; Huls, H.; Cubbage, M.; Sams, C. F.

1999-01-01

Studies of T lymphocyte activation with mitogenic lectins during spaceflight have shown a dramatic inhibition of activation as measured by DNA synthesis at 72 h, but the mechanism of this inhibition is unknown. We have investigated the progression of cellular events during the first 24 h of activation using both spaceflight microgravity culture and a ground-based model system that relies on the low shear culture environment of a rotating clinostat (clinorotation). Stimulation of human peripheral blood mononuclear cells (PBMCs) with soluble anti-CD3 (Leu4) in clinorotation and in microgravity culture shows a dramatic reduction in surface expression of the receptor for IL-2 (CD25) and CD69. An absence of bulk RNA synthesis in clinorotation indicates that stimulation with soluble Leu4 does not induce transition of T cells from G0 to the G1 stage of the cell cycle. However, internalization of the TCR by T cells and normal levels of IL-1 synthesis by monocytes indicate that intercellular interactions that are required for activation occur during clinorotation. Complementation of TCR-mediated signaling by phorbol ester restores the ability of PBMCs to express CD25 in clinorotation, indicating that a PKC-associated pathway may be compromised under these conditions. Bypassing the TCR by direct activation of intracellular pathways with a combination of phorbol ester and calcium ionophore in clinorotation resulted in full expression of CD25; however, only partial expression of CD25 occurred in microgravity culture. Though stimulation of purified T cells with Bead-Leu4 in microgravity culture resulted in the engagement and internalization of the TCR, the cells still failed to express CD25. When T cells were stimulated with Bead-Leu4 in microgravity culture, they were able to partially express CD69, a receptor that is constitutively stored in intracellular pools and can be expressed in the absence of new gene expression. Our results suggest that the inhibition of T cell

Cell intrinsic abrogation of TGFβ signaling delays but does not prevent dysfunction of self/tumor specific CD8 T cells in a murine model of autochthonous prostate cancer

PubMed Central

Chou, Cassie K.; Schietinger, Andrea; Liggitt, H. Denny; Tan, Xiaoxia; Funk, Sarah; Freeman, Gordon J.; Ratliff, Timothy L.; Greenberg, Norman M.; Greenberg, Philip D.

2012-01-01

Adoptive T cell therapy (ACT) for the treatment of established cancers is actively being pursued in clinical trials. However, poor in vivo persistence and maintenance of anti-tumor activity of transferred T cells remain major problems. Transforming growth factor beta (TGFβ) is a potent immunosuppressive cytokine that is often expressed at high levels within the tumor microenvironment, potentially limiting T cell mediated anti-tumor activity. Here, we used a model of autochthonous murine prostate cancer to evaluate the effect of cell intrinsic abrogation of TGFβ signaling in self/tumor specific CD8 T cells used in ACT to target the tumor in situ. We found that persistence and anti-tumor activity of adoptively transferred effector T cells deficient in TGFβ signaling was significantly improved in the cancerous prostate. However, over time, despite persistence in peripheral lymphoid organs, the numbers of transferred cells in the prostate decreased and the residual prostate infiltrating T cells were no longer functional. These findings reveal that TGFβ negatively regulates the accumulation and effector function of transferred self/tumor specific CD8 T cells and highlight that, when targeting a tumor antigen that is also expressed as a self-protein, additional substantive obstacles are operative within the tumor microenvironment, potentially hampering the success of ACT for solid tumors. PMID:22984076

Sargahydroquinoic acid inhibits TNFα-induced AP-1 and NF-κB signaling in HaCaT cells through PPARα activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeon, Youngsic; Jung, Yujung; Kim, Min Cheol

2014-08-08

Highlights: • SHQA increases PPARα/γ transactivation and inhibits MMP-2/-9 expression. • SHQA inhibits TNFα-induced AP-1 and MAPK signaling. • SHQA inhibits TNFα-induced p65 translocation and IκBα phosphorylation. • SHQA inhibits TNFα-induced AP-1 and NF-κB signaling via PPARα. - Abstract: Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligand-activated transcription factors and expressed in various cell types in the skin, including keratinocytes, fibroblasts and infiltrating immune cells. Thus, their ligands are targets for the treatment of various skin disorders, such as photo-aging and chronological aging of skin. Intensive studies have revealed that PPARα/γ functions in photo-agingmore » and age-related inflammation by regulating matrix metalloproteinases (MMPs) via activator protein-1 (AP-1) and nuclear factor kappa B (NF-κB). However, the detailed mechanism of PPARα/γ’s role in skin aging has not yet been elucidated. In this study, we confirmed that sargahydroquinoic acid (SHQA) as a PPARα/γ ligand significantly decreased Tumor Necrosis Factor-alpha (TNFα)-induced MMP-2/-9 expression by downregulating TNFα-induced transcription factors, subsequently reducing IκBα degradation and blocking NF-κB p65 nuclear translocation in HaCaT human epidermal keratinocyte cells. Treatment of cells with SHQA and GW6471 (PPARα antagonist) not bisphenol A diglycidyl ether (PPARγ antagonists), reversed the effect on TNFα-induced inflammatory signaling pathway activation. Taken together, our data suggest that SHQA inhibit TNFα-induced MMP-2/-9 expression and age-related inflammation by suppressing AP-1 and NF-κB pathway via PPARα.« less

Human papillomavirus (HPV) oncoprotein E6 facilitates Calcineurin-Nuclear factor for activated T cells 2 (NFAT2) signaling to promote cellular proliferation in cervical cell carcinoma.

PubMed

Ram, Babul Moni; Dolpady, Jayashree; Kulkarni, Rakesh; Usha, R; Bhoria, Usha; Poli, Usha Rani; Islam, Mojahidul; Trehanpati, Nirupma; Ramakrishna, Gayatri

2018-01-01

The calcineurin-NFAT signaling pathway regulates cell proliferation, differentiation, and development in diverse cell types and organ systems. Deregulation of calcineurin-NFAT signaling has been reported in leukaemias and few solid tumors such as breast and colon. In the present study, we found elevated calcineurin protein levels and phosphatase activity in cervical cancer cell lines and depletion of the same attenuated cell proliferation. Additionally, nuclear levels of NFAT2, a downstream target of calcineurin, viz, was found elevated in human papillomavirus (HPV) infected cells, HeLa and SiHa, compared to the HPV negative cells, HaCaT and C33A, indicative of its higher DNA binding activity. The nuclear levels of both NFAT1 and NFAT3 remain unaltered implicating they have little role in cervical carcinogenesis. Similar to the in vitro studies, the HPV infected human squamous cell carcinoma specimens showed higher NFAT2 levels compared to the normal cervical epithelium. Depletion of NFAT2 by RNAi attenuated growth of SiHa cells. Overexpression of HPV16 oncoproteins viz, E6 and E7 increased NFAT2 expression levels and DNA binding activity, while knockdown of E6 by RNAi decreased the same. Briefly, we now report an activation of calcineurin-NFAT2 axis in cervical cancer and a novel role of HPV oncoprotein in facilitating NFAT2 dependent cell proliferation. Copyright © 2017 Elsevier Inc. All rights reserved.

Therapeutic targeting of NOTCH1 signaling in T-ALL

PubMed Central

Palomero, Teresa; Ferrando, Adolfo

2010-01-01

The recent identification of activating mutations in NOTCH1 in the majority of T-cell acute lymphoblastic leukemias (T-ALL) has brought major interest towards targeting the NOTCH signaling pathway in this disease. Small molecule γ-secretase inhibitors (GSIs) which block a critical proteolytic step required for NOTCH1 activation can effectively block the activity of NOTCH1 mutant alleles. However, the clinical development of GSIs has been hampered by their low cytotoxicity against human T-ALL and the development of significant gastrointestinal toxicity derived from inhibition of NOTCH signaling in the gut. Improved understanding of the oncogenic mechanisms of NOTCH1 and the effects of NOTCH inhibition in leukemic cells and the intestinal epithelium are required for the design of effective anti-NOTCH1 therapies in T-ALL. PMID:19778842

A Combined Omics Approach to Generate the Surface Atlas of Human Naive CD4+ T Cells during Early T-Cell Receptor Activation*

PubMed Central

Graessel, Anke; Hauck, Stefanie M.; von Toerne, Christine; Kloppmann, Edda; Goldberg, Tatyana; Koppensteiner, Herwig; Schindler, Michael; Knapp, Bettina; Krause, Linda; Dietz, Katharina; Schmidt-Weber, Carsten B.; Suttner, Kathrin

2015-01-01

Naive CD4+ T cells are the common precursors of multiple effector and memory T-cell subsets and possess a high plasticity in terms of differentiation potential. This stem-cell-like character is important for cell therapies aiming at regeneration of specific immunity. Cell surface proteins are crucial for recognition and response to signals mediated by other cells or environmental changes. Knowledge of cell surface proteins of human naive CD4+ T cells and their changes during the early phase of T-cell activation is urgently needed for a guided differentiation of naive T cells and may support the selection of pluripotent cells for cell therapy. Periodate oxidation and aniline-catalyzed oxime ligation technology was applied with subsequent quantitative liquid chromatography-tandem MS to generate a data set describing the surface proteome of primary human naive CD4+ T cells and to monitor dynamic changes during the early phase of activation. This led to the identification of 173 N-glycosylated surface proteins. To independently confirm the proteomic data set and to analyze the cell surface by an alternative technique a systematic phenotypic expression analysis of surface antigens via flow cytometry was performed. This screening expanded the previous data set, resulting in 229 surface proteins, which were expressed on naive unstimulated and activated CD4+ T cells. Furthermore, we generated a surface expression atlas based on transcriptome data, experimental annotation, and predicted subcellular localization, and correlated the proteomics result with this transcriptional data set. This extensive surface atlas provides an overall naive CD4+ T cell surface resource and will enable future studies aiming at a deeper understanding of mechanisms of T-cell biology allowing the identification of novel immune targets usable for the development of therapeutic treatments. PMID:25991687

Vav1-phospholipase C-γ1 (Vav1-PLC-γ1) pathway initiated by T cell antigen receptor (TCRγδ) activation is required to overcome inhibition by ubiquitin ligase Cbl-b during γδT cell cytotoxicity.

PubMed

Yin, Shanshan; Zhang, Jianmin; Mao, Yujia; Hu, Yu; Cui, Lianxian; Kang, Ning; He, Wei

2013-09-13

T cell antigen receptor γδ (TCRγδ) and natural killer group 2, member D (NKG2D) are two crucial receptors for γδT cell cytotoxicity. Compelling evidences suggest that γδT cell cytotoxicity is TCRγδ-dependent and can be co-stimulated by NKG2D. However, the molecular mechanism of underlying TCRγδ-dependent activation of γδT cells remains unclear. In this study we demonstrated that TCRγδ but not NKG2D engagement induced lytic granule polarization and promoted γδT cell cytotoxicity. TCRγδ activation alone was sufficient to trigger Vav1-dependent phospholipase C-γ1 signaling, resulting in lytic granule polarization and effective killing, whereas NKG2D engagement alone failed to trigger cytotoxicity-related signaling to overcome the inhibitory effect of Cbl-b; therefore, NKG2D engagement alone could not induce effective killing. However, NKG2D ligation augmented the activation of γδT cell cytotoxicity through the Vav1-phospholipase C-γ1 pathway. Vav1 overexpression or Cbl-b knockdown not only enhanced TCRγδ activation-initiated killing but also enabled NKG2D activation alone to induce γδT cell cytotoxicity. Taken together, our results suggest that the activation of γδT cell cytotoxicity requires a strong activation signal to overcome the inhibitory effect of Cbl-b. Our finding provides new insights into the molecular mechanisms underlying the initiation of γδT cell cytotoxicity and likely implications for optimizing γδT cell-based cancer immunotherapy.

Exposure to inorganic mercury in vivo attenuates extrinsic apoptotic signaling in Staphylococcal aureus enterotoxin B stimulated T-cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laiosa, Michael D.; Eckles, Kevin G.; Langdon, Margaret

2007-12-15

The heavy metal mercury (Hg) is known to have immunomodulatory properties affecting lymphocyte signal transduction, death receptor signaling and autoimmunity. In this study we tested the hypothesis that Hg exposure would attenuate T-cell activation and caspase 8 and 3 activity in response to antigenic stimuli. To test this hypothesis, BALB/cJ mice were exposed to 10 mg/l mercuric chloride (HgCl{sub 2}) in their drinking water for 2 weeks followed by injection with 20 {mu}g of the Staphylococcal aureus enterotoxin B (SEB) superantigen. Eighteen hours after SEB challenge, there was a statistically significant reduction in caspase 8 and caspase 3 enzyme activitymore » in the SEB reactive V{beta}8+ T-cells. The attenuated caspase activity in Hg-exposed mice persisted for 48 h after exposure. Moreover, activation of caspase 8 and caspase 3 was reduced by more than 60% in CD95 deficient MRL/MpJ-Fas{sup lpr} mice demonstrating that caspase 8 and 3 activation in response to SEB is CD95 dependent. In addition to the effects of Hg on caspase activity, expression of the T-cell activation marker CD69 was also attenuated in SEB reactive V{beta}8 T-cells in Hg-exposed mice. Moreover, CD69 expression in MRL/MpJ-Fas{sup lpr} mice was also reduced. Taken together the caspase and CD69 data support a role for CD95 in promoting a proapoptotic and activated state in SEB responsive T-lymphocytes and this state is attenuated by the autoimmune potentiating environmental agent mercury.« less

Sepsis-induced alteration in T-cell Ca(2+) signaling in neonatal rats.

PubMed

Alattar, M H; Ravindranath, T M; Choudhry, M A; Muraskas, J K; Namak, S Y; Dallal, O; Sayeed, M M

2001-01-01

Sepsis-induced suppression in T-cell proliferation follows deranged Ca(2+) signaling in adult rats. In preliminary studies, we observed suppression in T-cell proliferation in septic neonatal rats as well. In this study, we assessed splenic T-cell cytosolic Ca(2+) concentration, [Ca(2+)](i), as its elevation plays an important role in T-cell proliferation. Also, we investigated the role of PGE(2) in sepsis-related changes in T-cell [Ca(2+)](i) in animals pretreated with cyclooxygenase-1 (COX-1) inhibitor (resveratrol) and cyclooxygenase-2 (COX-2) inhibitor (NS-398). Sepsis was induced in 15-day-old rat pups by intraperitoneal implantation of fecal pellets containing Escherichia coli and Bacteroides fragilis. The sham group consisted of pups implanted with sterile fecal pellets. Septic and sham pups were sacrificed 24 h after implantation and their spleens were removed. The spleens from sham and septic pups, along with spleens from unoperated control pups, were processed for single cell suspensions, and T cells were isolated using nylon wool columns. Fura-2 fluorophotometry was employed for the measurement of [Ca(2+)](i) (in nM units) in T cells stimulated with concanavalin A (ConA). Our results show that ConA-mediated T-cell [Ca(2+)](i) response is significantly suppressed in septic neonatal rats. Pretreatment of pups with COX-2, but not COX-1 inhibitor, prevented the decrease in the [Ca(2+)](i) response. These findings suggest that PGE(2) might induce the attenuation in T-cell Ca(2+) signaling during sepsis in neonatal rats. Copyright 2001 S. Karger AG, Basel

Phosphatase and tensin homolog-β-catenin signaling modulates regulatory T cells and inflammatory responses in mouse liver ischemia/reperfusion injury.

PubMed

Zhu, Qiang; Li, Changyong; Wang, Kunpeng; Yue, Shi; Jiang, Longfeng; Ke, Michael; Busuttil, Ronald W; Kupiec-Weglinski, Jerzy W; Zhang, Feng; Lu, Ling; Ke, Bibo

2017-06-01

The phosphatase and tensin homolog (PTEN) deleted on chromosome 10 plays an important role in regulating T cell activation during inflammatory response. Activation of β-catenin is crucial for maintaining immune homeostasis. This study investigates the functional roles and molecular mechanisms by which PTEN-β-catenin signaling promotes regulatory T cell (Treg) induction in a mouse model of liver ischemia/reperfusion injury (IRI). We found that mice with myeloid-specific phosphatase and tensin homolog knockout (PTEN M-KO ) exhibited reduced liver damage as evidenced by decreased levels of serum alanine aminotransferase, intrahepatic macrophage trafficking, and proinflammatory mediators compared with the PTEN-proficient (floxed phosphatase and tensin homolog [PTEN FL/FL ]) controls. Disruption of myeloid PTEN-activated b-catenin promoted peroxisome proliferator-activated receptor gamma (PPARγ)-mediated Jagged-1/Notch signaling and induced forkhead box P3 (FOXP3)1 Tregs while inhibiting T helper 17 cells. However, blocking of Notch signaling by inhibiting γ-secretase reversed myeloid PTEN deficiency-mediated protection in ischemia/reperfusion-triggered liver inflammation with reduced FOXP3 + and increased retinoid A receptor-related orphan receptor gamma t-mediated interleukin 17A expression in ischemic livers. Moreover, knockdown of β-catenin or PPARγ in PTEN-deficient macrophages inhibited Jagged-1/Notch activation and reduced FOXP3 + Treg induction, leading to increased proinflammatory mediators in macrophage/T cell cocultures. In conclusion, our findings demonstrate that PTEN-β-catenin signaling is a novel regulator involved in modulating Treg development and provides a potential therapeutic target in liver IRI. Liver Transplantation 23 813-825 2017 AASLD. © 2017 by the American Association for the Study of Liver Diseases.

Adenosine production by human B cells and B cell–mediated suppression of activated T cells

PubMed Central

Saze, Zenichiro; Schuler, Patrick J.; Hong, Chang-Sook; Cheng, Dongmei; Jackson, Edwin K.

2013-01-01

Antibody-independent role of B cells in modulating T-cell responses is incompletely understood. Freshly isolated or cultured B cells isolated from the peripheral blood of 30 normal donors were evaluated for CD39 and CD73 coexpression, the ability to produce adenosine 5′-monophosphate (AMP) and adenosine (ADO) in the presence of exogenous adenosine triphosphate (ATP) as well as A1, A2A, A2B, and A3 adenosine receptor (ADOR) expression. Human circulating B cells coexpress ectonucleotidases CD39 and CD73, hydrolyze exogenous ATP to 5′-AMP and ADO, and express messenger RNA for A1R, A2AR, and A3R. 2-chloroadenosine inhibited B-cell proliferation and cytokine expression, and only A3R selective antagonist restored B-cell functions. This suggested that B cells use the A3R for autocrine signaling and self-regulation. Mediated effects on B-cell growth ± ADOR antagonists or agonists were tested in carboxyfluorescein diacetate succinimidyl ester assays. In cocultures, resting B cells upregulated functions of CD4+ and CD8+ T cells. However, in vitro–activated B cells downregulated CD73 expression, mainly produced 5′-AMP, and inhibited T-cell proliferation and cytokine production. These B cells acquire the ability to restrict potentially harmful effects of activated T cells. Thus, B cells emerge as a key regulatory component of T cell–B cell interactions, and their dual regulatory activity is mediated by the products of ATP hydrolysis, 5′-AMP, and ADO. PMID:23678003

Nicotine-mediated signals modulate cell death and survival of T lymphocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oloris, Silvia C.S.; Instituto de Ciencias Exatas e Naturais, Universidade do Estado do Rio Grande do Norte, Mossoro, RN; Frazer-Abel, Ashley A.

The capacity of nicotine to affect the behavior of non-neuronal cells through neuronal nicotinic acetylcholine receptors (nAChRs) has been the subject of considerable recent attention. Previously, we showed that exposure to nicotine activates the nuclear factor of activated T cells (NFAT) transcription factor in lymphocytes and endothelial cells, leading to alterations in cellular growth and vascular endothelial growth factor production. Here, we extend these studies to document effects of nicotine on lymphocyte survival. The data show that nicotine induces paradoxical effects that might alternatively enforce survival or trigger apoptosis, suggesting that depending on timing and context, nicotine might act bothmore » as a survival factor or as an inducer of apoptosis in normal or transformed lymphocytes, and possibly other non-neuronal cells. In addition, our results show that, while having overlapping functions, low and high affinity nAChRs also transmit signals that promote distinct outcomes in lymphocytes. The sum of our data suggests that selective modulation of nAChRs might be useful to regulate lymphocyte activation and survival in health and disease.« less

Signal peptide cleavage is essential for surface expression of a regulatory T cell surface protein, leucine rich repeat containing 32 (LRRC32).

PubMed

Chan, Derek V; Somani, Ally-Khan; Young, Andrew B; Massari, Jessica V; Ohtola, Jennifer; Sugiyama, Hideaki; Garaczi, Edina; Babineau, Denise; Cooper, Kevin D; McCormick, Thomas S

2011-05-26

Elevated numbers of regulatory T cells (T(regs)) have been implicated in certain cancers. Depletion of T(regs) has been shown to increase anti-tumor immunity. T(regs) also play a critical role in the suppression of autoimmune responses. The study of T(regs) has been hampered by a lack of adequate surface markers. Leucine Rich Repeat Containing 32 (LRRC32), also known as Glycoprotein A Repetitions Predominant (GARP), has been postulated as a novel surface marker of activated T(regs). However, there is limited information regarding the processing of LRRC32 or the regulatory phenotype and functional activity of T(regs) expressing LRRC32. Using naturally-occurring freshly isolated T(regs), we demonstrate that low levels of LRRC32 are present intracellularly prior to activation and that freshly isolated LRRC32+ T(regs) are distinct from LRRC32- T(regs) with respect to the expression of surface CD62L. Using LRRC32 transfectants of HEK cells, we demonstrate that the N-terminus of LRRC32 is cleaved prior to expression of the protein at the cell surface. Furthermore, we demonstrate using a construct containing a deleted putative signal peptide region that the presence of a signal peptide region is critical to cell surface expression of LRRC32. Finally, mixed lymphocyte assays demonstrate that LRRC32+ T(regs) are more potent suppressors than LRRC32- T(regs). A cleaved signal peptide site in LRRC32 is necessary for surface localization of native LRRC32 following activation of naturally-occurring freshly-isolated regulatory T cells. LRRC32 expression appears to alter the surface expression of activation markers of T cells such as CD62L. LRRC32 surface expression may be useful as a marker that selects for more potent T(reg) populations. In summary, understanding the processing and expression of LRRC32 may provide insight into the mechanism of action of T(regs) and the refinement of immunotherapeutic strategies aimed at targeting these cells.

Utilizing T-cell Activation Signals 1, 2, and 3 for Tumor-infiltrating Lymphocytes (TIL) Expansion: The Advantage Over the Sole Use of Interleukin-2 in Cutaneous and Uveal Melanoma.

PubMed

Tavera, René J; Forget, Marie-Andrée; Kim, Young Uk; Sakellariou-Thompson, Donastas; Creasy, Caitlin A; Bhatta, Ankit; Fulbright, Orenthial J; Ramachandran, Renjith; Thorsen, Shawne T; Flores, Esteban; Wahl, Arely; Gonzalez, Audrey M; Toth, Christopher; Wardell, Seth; Mansaray, Rahmatu; Radvanyi, Laszlo G; Gombos, Dan S; Patel, Sapna P; Hwu, Patrick; Amaria, Rodabe N; Bernatchez, Chantale; Haymaker, Cara

2018-05-11

In this study, we address one of the major critiques for tumor-infiltrating lymphocyte (TIL) therapy-the time needed for proper expansion of a suitable product. We postulated that T-cell receptor activation in the first phase of expansion combined with an agonistic stimulation of CD137/4-1BB and interleukin-2 would favor preferential expansion of CD8 TIL. Indeed, this novel 3-signal approach for optimal T-cell activation resulted in faster and more consistent expansion of CD8CD3 TIL. This new method allowed for successful expansion of TIL from cutaneous and uveal melanoma tumors in 100% of the cultures in <3 weeks. Finally, providing the 3 signals attributed to optimal T-cell activation led to expansion of TIL capable of recognizing their tumor counterpart in cutaneous and uveal melanoma. This new methodology for the initial phase of TIL expansion brings a new opportunity for translation of TIL therapy in challenging malignancies such as uveal melanoma.

MHY1485 ameliorates UV-induced skin cell damages via activating mTOR-Nrf2 signaling.

PubMed

Yang, Bo; Xu, Qiu-Yun; Guo, Chun-Yan; Huang, Jin-Wen; Wang, Shu-Mei; Li, Yong-Mei; Tu, Ying; He, Li; Bi, Zhi-Gang; Ji, Chao; Cheng, Bo

2017-02-21

Ultra Violet (UV)-caused skin cell damage is a main cause of skin cancer. Here, we studied the activity of MHY1485, a mTOR activator, in UV-treated skin cells. In primary human skin keratinocytes, HaCaT keratinocytes and human skin fibroblasts, MHY1485 ameliorated UV-induced cell death and apoptosis. mTOR activation is required for MHY1485-induced above cytoprotective actions. mTOR kinase inhibitors (OSI-027, AZD-8055 and AZD-2014) or mTOR shRNA knockdown almost abolished MHY1485-induced cytoprotection. Further, MHY1485 treatment in skin cells activated mTOR downstream NF-E2-related factor 2 (Nrf2) signaling, causing Nrf2 Ser-40 phosphorylation, stabilization/upregulation and nuclear translocation, as well as mRNA expression of Nrf2-dictated genes. Contrarily, Nrf2 knockdown or S40T mutation almost nullified MHY1485-induced cytoprotection. MHY1485 suppressed UV-induced reactive oxygen species production and DNA single strand breaks in skin keratinocytes and fibroblasts. Together, we conclude that MHY1485 inhibits UV-induced skin cell damages via activating mTOR-Nrf2 signaling.

Phosphoinositide 3–kinase γ participates in T cell receptor–induced T cell activation

PubMed Central

Alcázar, Isabela; Marqués, Miriam; Kumar, Amit; Hirsch, Emilio; Wymann, Matthias; Carrera, Ana C.; Barber, Domingo F.

2007-01-01

Class I phosphoinositide 3–kinases (PI3Ks) constitute a family of enzymes that generates 3-phosphorylated polyphosphoinositides at the cell membrane after stimulation of protein tyrosine (Tyr) kinase–associated receptors or G protein–coupled receptors (GPCRs). The class I PI3Ks are divided into two types: class IA p85/p110 heterodimers, which are activated by Tyr kinases, and the class IB p110γ isoform, which is activated by GPCR. Although the T cell receptor (TCR) is a protein Tyr kinase–associated receptor, p110γ deletion affects TCR-induced T cell stimulation. We examined whether the TCR activates p110γ, as well as the consequences of interfering with p110γ expression or function for T cell activation. We found that after TCR ligation, p110γ interacts with Gαq/11, lymphocyte-specific Tyr kinase, and ζ-associated protein. TCR stimulation activates p110γ, which affects 3-phosphorylated polyphosphoinositide levels at the immunological synapse. We show that TCR-stimulated p110γ controls RAS-related C3 botulinum substrate 1 activity, F-actin polarization, and the interaction between T cells and antigen-presenting cells, illustrating a crucial role for p110γ in TCR-induced T cell activation. PMID:17998387

Mitochondria-derived hydrogen peroxide selectively enhances T cell receptor-initiated signal transduction.

PubMed

Gill, Tejpal; Levine, Alan D

2013-09-06

T cell receptor (TCR)-initiated signal transduction is reported to increase production of intracellular reactive oxygen species, such as superoxide (O2˙(-)) and hydrogen peroxide (H2O2), as second messengers. Although H2O2 can modulate signal transduction by inactivating protein phosphatases, the mechanism and the subcellular localization of intracellular H2O2 as a second messenger of the TCR are not known. The antioxidant enzyme superoxide dismutase (SOD) catalyzes the dismutation of highly reactive O2˙(-) into H2O2 and thus acts as an intracellular generator of H2O2. As charged O2˙(-) is unable to diffuse through intracellular membranes, cells express distinct SOD isoforms in the cytosol (Cu,Zn-SOD) and mitochondria (Mn-SOD), where they locally scavenge O2˙(-) leading to production of H2O2. A 2-fold organelle-specific overexpression of either SOD in Jurkat T cell lines increases intracellular production of H2O2 but does not alter the levels of intracellular H2O2 scavenging enzymes such as catalase, membrane-bound peroxiredoxin1 (Prx1), and cytosolic Prx2. We report that overexpression of Mn-SOD enhances tyrosine phosphorylation of TCR-associated membrane proximal signal transduction molecules Lck, LAT, ZAP70, PLCγ1, and SLP76 within 1 min of TCR cross-linking. This increase in mitochondrial H2O2 specifically modulates MAPK signaling through the JNK/cJun pathway, whereas overexpressing Cu,Zn-SOD had no effect on any of these TCR-mediated signaling molecules. As mitochondria translocate to the immunological synapse during TCR activation, we hypothesize this translocation provides the effective concentration of H2O2 required to selectively modulate downstream signal transduction pathways.

IL-1 Receptor Signaling on Graft Parenchymal Cells Regulates Memory and De Novo Donor-Reactive CD8 T Cell Responses to Cardiac Allografts.

PubMed

Iida, Shoichi; Tsuda, Hidetoshi; Tanaka, Toshiaki; Kish, Danielle D; Abe, Toyofumi; Su, Charles A; Abe, Ryo; Tanabe, Kazunari; Valujskikh, Anna; Baldwin, William M; Fairchild, Robert L

2016-03-15

Reperfusion of organ allografts induces a potent inflammatory response that directs rapid memory T cell, neutrophil, and macrophage graft infiltration and their activation to express functions mediating graft tissue injury. The role of cardiac allograft IL-1 receptor (IL-1R) signaling in this early inflammation and the downstream primary alloimmune response was investigated. When compared with complete MHC-mismatched wild-type cardiac allografts, IL-1R(-/-) allografts had marked decreases in endogenous memory CD8 T cell and neutrophil infiltration and expression of proinflammatory mediators at early times after transplant, whereas endogenous memory CD4 T cell and macrophage infiltration was not decreased. IL-1R(-/-) allograft recipients also had marked decreases in de novo donor-reactive CD8, but not CD4, T cell development to IFN-γ-producing cells. CD8 T cell-mediated rejection of IL-1R(-/-) cardiac allografts took 3 wk longer than wild-type allografts. Cardiac allografts from reciprocal bone marrow reconstituted IL-1R(-/-)/wild-type chimeric donors indicated that IL-1R signaling on graft nonhematopoietic-derived, but not bone marrow-derived, cells is required for the potent donor-reactive memory and primary CD8 T cell alloimmune responses observed in response to wild-type allografts. These studies implicate IL-1R-mediated signals by allograft parenchymal cells in generating the stimuli-provoking development and elicitation of optimal alloimmune responses to the grafts. Copyright © 2016 by The American Association of Immunologists, Inc.