bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cutting Edge: Lectin-Like Transcript 1 Is a Ligand for the CD161 Receptor
Authors: Aldemir Hatice , Prod’homme Virginie , Dumaurier Marie-Jeanne , Retiere Christelle , Poupon Gwenola , Cazareth Julie , Bihl Franck , Braud Veronique M. 
Published: April 2014

Abstract
Human NK cells and subsets of T cells or NKT cells express the orphan C-type lectin receptor CD161 (NKR-P1A) of unknown function. In contrast to rodents that possess several NKR-P1 genes coding for either activating or inhibitory receptors, the nature of signals delivered by the single human NKR-P1A receptor is still to be clarified. In this article, we show that the lectin-like transcript 1 (LLT1) molecule is a ligand for the CD161 receptor. Engagement of CD161 on NK cells with LLT1 expressed on target cells inhibited NK cell-mediated cytotoxicity and IFN-γ secretion. Conversely, LLT1/CD161 interaction in the presence of a TCR signal enhanced IFN-γ production by T cells. These findings identify a novel ligand/receptor pair that differentially regulate NK and T cell functions.
The Scaffolding Protein CG-NAP/AKAP450 Is a Critical Integrating Component of the LFA-1-Induced Signaling Complex in Migratory T Cells
Authors: El Homasany Basma Salah El Din , Volkov Yuri , Takahashi Mikiko , Ono Yoshitaka , Keryer Guy , Delouvée Annie , Looby Eileen , Long Aideen , Kelleher Dermot 
Published: April 2014

Abstract
T cell migration represents a complex highly coordinated process involving participation of surface receptor/ligand interactions, cytoskeletal rearrangements, and phosphorylation-dependent signaling cascades. Members of the A-kinase anchoring protein (AKAP) family of giant scaffolding proteins can assemble and compartmentalize multiple signaling and structural molecules thereby providing a platform for their targeted positioning and efficient interactions. We characterize here the expression, intracellular distribution, and functional role of the scaffolding protein CG-NAP (centrosome and Golgi localized protein kinase N-associated protein)/AKAP450 in the process of active T cell motility induced via LFA-1 integrins. This protein is predominantly localized at the centrosome and Golgi complex. T cell locomotion triggered by LFA-1 ligation induces redistribution of CG-NAP/AKAP450 along microtubules in trailing cell extensions. Using an original in situ immunoprecipitation approach, we show that CG-NAP/AKAP450 is physically associated with LFA-1 in the multimolecular signaling complex also including tubulin and the protein kinase C β and δ isoenzymes. CG-NAP/AKAP450 recruitment to this complex was specific for the T cells migrating on LFA-1 ligands, but not on the β1 integrin ligand fibronectin. Using the GFP-tagged C-terminal CG-NAP/AKAP450 construct, we demonstrate that expression of the intact CG-NAP/AKAP450 and its recruitment to the LFA-1-associated multimolecular complex is critically important for polarization and migration of T cells induced by this integrin.
Silencing Human NKG2D, DAP10, and DAP12 Reduces Cytotoxicity of Activated CD8+ T Cells and NK Cells
Authors: Karimi Mobin , Cao Thai M. , Baker Jeanette A. , Verneris Michael R. , Soares Luis , Negrin Robert S. 
Published: April 2014

Abstract
Human CD8+ T cells activated and expanded by TCR cross-linking and high-dose IL-2 acquire potent cytolytic ability against tumors and are a promising approach for immunotherapy of malignant diseases. We have recently reported that in vitro killing by these activated cells, which share phenotypic and functional characteristics with NK cells, is mediated principally by NKG2D. NKG2D is a surface receptor that is expressed by all NK cells and transmits an activating signal via the DAP10 adaptor molecule. Using stable RNA interference induced by lentiviral transduction, we show that NKG2D is required for cytolysis of tumor cells, including autologous tumor cells from patients with ovarian cancer. We also demonstrated that NKG2D is required for in vivo antitumor activity. Furthermore, both activated and expanded CD8+ T cells and NK cells use DAP10. In addition, direct killing was partially dependent on the DAP12 signaling pathway. This requirement by activated and expanded CD8+ T cells for DAP12, and hence stimulus from a putative DAP12-partnered activating surface receptor, persisted when assayed by anti-NKG2D Ab-mediated redirected cytolysis. These studies demonstrated the importance of NKG2D, DAP10, and DAP12 in human effector cell function.
CD80 Cytoplasmic Domain Controls Localization of CD28, CTLA-4, and Protein Kinase Cθ in the Immunological Synapse
Authors: Tseng Su-Yi , Liu Mengling , Dustin Michael L. 
Published: April 2014

AbstractThe binding of costimulatory ligand CD80 to CD28 or CTLA-4 on T cells plays an important role in the regulation of the T cell response. We have examined the role of the cytoplasmic domain of CD80 in murine T cell costimulation and its organization in the immunological synapse (IS). Removal of CD80 cytoplasmic tail decreased its effectiveness in costimulating T cell proliferative response and early IL-2 production in response to agonist MHC-peptide complexes. Immunofluorescent study showed a decreased tailless CD80 accumulation in the IS of naive T cells. The two forms of CD80 accumulated differently at the IS; the tailless CD80 was colocalized with the TCR whereas the full-length CD80 was segregated from the TCR. In addition, we showed that CD80, CD28, and protein kinase Cθ colocalized in the presence or absence of the CD80 cytoplasmic tail. Thus, the cytoplasmic tail of CD80 regulates its spatial localization at the IS and that of its receptors and T cell signaling molecules such as protein kinase Cθ, and thereby facilitates full T cell activation.
Cooperation of Invariant NKT Cells and CD4+CD25+ T Regulatory Cells in the Prevention of Autoimmune Myasthenia
Authors: Liu Ruolan , La Cava Antonio , Bai Xue-Feng , Jee Youngheun , Price Mary , Campagnolo Denise I. , Christadoss Premkumar , Vollmer Timothy L. , Van Kaer Luc , Shi Fu-Dong 
Published: April 2014

Abstract
CD1d-restricted NKT cells and CD4+CD25+ regulatory T (Treg) cells are thymus-derived subsets of regulatory T cells that have an important role in the maintenance of self-tolerance. Whether NKT cells and Treg cells cooperate functionally in the regulation of autoimmunity is not known. We have explored this possibility in experimental autoimmune myasthenia gravis (EAMG), an animal model of human myasthenia gravis, induced by immunization of C57BL/6 mice with the autoantigen acetylcholine receptor. We have demonstrated that activation of NKT cells by a synthetic glycolipid agonist of NKT cells, α-galactosylceramide (α-GalCer), inhibits the development of EAMG. α-GalCer administration in EAMG mice increased the size of the Treg cell compartment, and augmented the expression of foxp3 and the potency of CD4+CD25+ cells to inhibit proliferation of autoreactive T cells. Furthermore, α-GalCer promoted NKT cells to transcribe the IL-2 gene and produce IL-2 protein. Depletion of CD25+ cells or neutralization of IL-2 reduced the therapeutic effect of α-GalCer in this model. Thus, α-GalCer-activated NKT cells can induce expansion of CD4+CD25+ Treg cells, which in turn mediate the therapeutic effects of α-GalCer in EAMG. Induced cooperation of NKT cells and Treg cells may serve as a superior strategy to treat autoimmune disease.
CD4+ T Cell Responses Elicited by Different Subsets of Human Skin Migratory Dendritic Cells
Authors: Morelli Adrian E. , Rubin J. Peter , Erdos Geza , Tkacheva Olga A. , Mathers Alicia R. , Zahorchak Alan F. , Thomson Angus W. , Falo Louis D. , Larregina Adriana T. 
Published: April 2014

Abstract
Skin dendritic cells (DC) are professional APC critical for initiation and control of adaptive immunity. In the present work we have analyzed the CD4+ T cell stimulatory function of different subsets of DC that migrate spontaneously from human skin explants, including CD1a+CD14− Langerhans’ cells (LC), CD1a−CD14− dermal DC (DDC), and CD1a−CD14+ LC precursors. Skin migratory DC consisted of APC at different stages of maturation-activation that produced IL-10, TGF-β1, IL-23p19, and IL-12p40, but did not release IL-12p70 even after exposure to DC1-driving stimuli. LC and DDC migrated as mature/activated APC able to stimulate allogeneic naive CD4+ T cells and to induce memory Th1 cells in the absence of IL-12p70. The potent CD4+ T cell stimulatory function of LC and DDC correlated with their high levels of expression of MHC class II, adhesion, and costimulatory molecules. The Th1-biasing function of LC and DDC depended on their ability to produce IL-23. By contrast, CD1a−CD14+ LC precursors migrated as immature-semimature APC and were weak stimulators of allogeneic naive CD4+ T cells. However, and opposite of a potential tolerogenic role of immature DC, the T cell allostimulatory and Th1-biasing function of CD14+ LC precursors increased significantly by augmenting their cell number, prolonging the time of interaction with responding T cells, or addition of recombinant human IL-23 in MLC. The data presented in this study provide insight into the function of the complex network of skin-resident DC that migrate out of the epidermis and dermis after cutaneous immunizations, pathogen infections, or allograft transplantation.
Stabilized β-Catenin Extends Thymocyte Survival by Up-Regulating Bcl-xL
Authors: Xie Huimin , Huang Zhaofeng , Sadim Maureen S. , Sun Zuoming 
Published: April 2014

Abstract
CD4+CD8+ double-positive (DP) thymocytes, which are extremely sensitive to apoptosis, specifically up-regulate Bcl-xL to extend their lifespan. Deletion of the Bcl-xL gene leads to premature apoptosis of the thymocytes. In this study, we show that stabilization of β-catenin, a critical coactivator for T cell factor (TCF), enhances DP thymocyte survival via up-regulating Bcl-xL. Spontaneous or glucocorticoid-induced thymocyte apoptosis was associated with reduced levels of β-catenin and Bcl-xL. Transgenic expression of a stabilized β-catenin protected DP thymocytes from both spontaneous and glucocorticoid-induced apoptosis, resulting in significantly increased thymic cellularity. Compared with the wild-type mice, both protein and transcript levels of Bcl-xL were significantly increased in thymocytes of β-catenin transgenic mice. In addition, TCF-1 as well as β-catenin were able to stimulate transcriptional activity of the reporter driven by a Bcl-xL promoter. β-Catenin/TCF is thus able to act as a signal to up-regulate Bcl-xL levels in DP thymocytes, resulting in their enhanced survival.
The Cytotoxicity Receptor CRACC (CS-1) Recruits EAT-2 and Activates the PI3K and Phospholipase Cγ Signaling Pathways in Human NK Cells
Authors: Tassi Ilaria , Colonna Marco 
Published: April 2014

Abstract
The CD2-like receptor-activating cytotoxic cell (CRACC) is a cell surface receptor of the CD2 family that triggers NK cell-mediated cytotoxicity through an undefined signaling pathway. CRACC contains cytoplasmic tyrosine-based motifs, immunoreceptor tyrosine-based switch motifs, which resemble those found in the NK cell receptor 2B4. In 2B4, these motifs recruit the adaptor signaling lymphocytic activation molecule-associated protein (SAP), which initiates a signaling cascade mediating cytotoxicity. However, CRACC does not recruit SAP. In this study, we demonstrate that, upon activation, CRACC associates with a homolog of SAP, Ewing’s sarcoma’s/FLI1-activated transcript 2 (EAT-2), in human NK cells. We show that association of EAT-2 induces the phosphorylation of CRACC and that this process is partially reduced by a pharmacological inhibitor of Src kinases. We identify PLCγ1, PLCγ2, and PI3K as the major signaling mediators downstream of CRACC/EAT-2 implicated in NK cell-mediated cytotoxicity. Moreover, EAT-2 also associates with 2B4 predominantly in resting NK cells, whereas SAP preferentially binds 2B4 upon activation. These results outline a new signaling pathway that triggers CRACC-mediated cytotoxicity and modulates 2B4-mediated activation.
CD43 Functions as a Ligand for E-Selectin on Activated T Cells
Authors: Matsumoto Masanori , Atarashi Kazuyuki , Umemoto Eiji , Furukawa Yuko , Shigeta Akiko , Miyasaka Masayuki , Hirata Takako 
Published: April 2014

Abstract
E-selectin, an inducible cell adhesion molecule expressed on endothelial cells, mediates the rolling on endothelium of leukocytes expressing E-selectin ligands, such as neutrophils and activated T cells. Although previous studies using mice lacking P-selectin glycoprotein ligand-1 (PSGL-1) have indicated that PSGL-1 on Th1 cells functions as an E-selectin ligand, the molecular nature of E-selectin ligands other than PSGL-1 remains unknown. In this study, we show that a 130-kDa glycoprotein was precipitated by an E-selectin-IgG chimera from mouse Th1 cells. This protein was cleaved by O-sialoglycoprotein endopeptidase and required sialic acid for E-selectin binding. The mAb 1B11, which recognizes the 130-kDa glycoform of CD43, recognized the 130-kDa band in the E-selectin-IgG precipitate. In addition, immunoprecipitation of the E-selectin-IgG precipitate with 1B11 depleted the 130-kDa protein, further confirming its identity as CD43. CD43 was also precipitated with E-selectin-IgG from cultured human T cells. E-selectin-dependent cell rolling on CD43 was observed under flow conditions using a CD43-IgG chimera generated in Chinese hamster ovary cells expressing α-1,3-fucosyltransferase VII and a core 2 β-1,6-N-acetylglucosaminyltransferase. These results suggest that CD43, when modified by a specific set of glycosyltranferases, can function as an E-selectin ligand and therefore potentially mediate activated T cell migration into inflamed sites.
Elevated T Regulatory Cells in Long-Term Stable Transplant Tolerance in Rhesus Macaques Induced by Anti-CD3 Immunotoxin and Deoxyspergualin
Authors: Asiedu Clement K. , Goodwin Karen J. , Balgansuren Gansuvd , Jenkins Stacie M. , Le Bas-Bernardet Stéphanie , Jargal Uuganbayar , Neville David M. , Thomas Judith M. 
Published: April 2014

Abstract
Regulatory T cells (Tregs) are implicated in immune tolerance and are variably dependent on IL-10 for in vivo function. Brief peritransplant treatment of multiple nonhuman primates (NHP) with anti-CD3 immunotoxin and deoxyspergualin has induced stable (5–10 years) rejection-free tolerance to MHC-mismatched allografts, which associated with sustained elevations in serum IL-10. In this study, we demonstrate that resting and activated PBMC from long-term tolerant NHP recipients are biased to secrete high levels of IL-10, compared with normal NHP PBMC. Although IL-10-producing CD4+ Tregs (type 1 regulatory cells (TR1)/IL-10 Tregs) were undetectable (&lt;0.5%) in normal rhesus monkeys, 7.5 ± 1.7% of circulating CD4+ T cells of tolerant rhesus recipients expressed IL-10. In addition to this &gt;15-fold increase in Tr1/IL-10 Tregs, the tolerant monkeys exhibited a nearly 3-fold increase in CD4+CD25+ Tregs, 8.1 ± 3.0% of CD4 T cells vs 2.8 ± 1.4% in normal cohorts (p &lt; 0.02). The frequency of CD4+CD25+IL-10+ cells was elevated 5-fold in tolerant vs normal NHP (1.8 ± 0.9% vs 0.4 ± 0.2%). Rhesus CD4+CD25+ Tregs exhibited a memory phenotype, and expressed high levels of Foxp3 and CTLA-4 compared with CD4+CD25− T cells. Also, NHP CD4+CD25+ Tregs proliferated poorly after activation and suppressed proliferation of CD4+CD25− effector T cells, exhibiting regulatory properties similar to rodent and human CD4+CD25+ Tregs. Of note, depletion of CD4+CD25+ Tregs restored indirect pathway antidonor responses in tolerant NHP. Our study demonstrates an expanded presence of Treg populations in tolerant NHP recipients, suggesting that these adaptations may be involved in maintenance of stable tolerance.
Disruption of Lipid Rafts Stimulates Phospholipase D Activity in Human Lymphocytes: Implication in the Regulation of Immune Function
Authors: Diaz Olivier , Mébarek-Azzam Saïda , Benzaria Amal , Dubois Madeleine , Lagarde Michel , Némoz Georges , Prigent Annie-France 
Published: April 2014

Abstract
Recent evidence suggests that phospholipase D (PLD) can be regulated through its association/dissociation to lipid rafts. We show here that modifying lipid rafts either by cholesterol depletion using methyl-β-cyclodextrin and filipin or by conversion of sphingomyelin to ceramide with exogenous bacterial sphingomyelinase (bSMase) markedly activated the PLD of human PBMC. bSMase was the most potent PLD activator, giving maximal 6- to 7-fold increase in PLD activity. Triton X-100-treated lysates prepared from control PBMC and from bSMase-treated cells were fractionated by centrifugation on sucrose density gradient. We observed that bSMase treatment of the cells induced a larger ceramide increase in raft than in nonraft membranes and displaced both the Src kinase Lck and PLD1 out of the raft fractions. In addition, the three raft-modifying agents markedly inhibited the lymphoproliferative response to mitogenic lectin. To examine further the potential role of PLD activation in the control of lymphocyte responses, we transiently overexpressed either of the PLD1 and PLD2 isoforms in Jurkat cells and analyzed the phorbol ester plus ionomycin-induced expression of IL-2 mRNA, which is one of the early responses of lymphocyte to activation. We observed a 43% decrease of IL-2 mRNA level in Jurkat cells overexpressing PLD1 as compared with mock- or PLD2-transfected cells, which indicates that elevated PLD1, but not PLD2, activity impairs lymphocyte activation. Altogether, the present results support the hypothesis that PLD1 is activated by exclusion from lipid rafts and that this activation conveys antiproliferative signals in lymphoid cells.
A Role for TLRs in the Regulation of Immune Cell Migration by First Trimester Trophoblast Cells
Authors: Abrahams Vikki M. , Visintin Irene , Aldo Paulomi B. , Guller Seth , Romero Roberto , Mor Gil 
Published: April 2014

Abstract
Normal pregnancy is characterized by the presence of innate immune cells at the maternal-fetal interface. Originally, it was postulated that the presence of these leukocytes was due to an immune response toward paternal Ags expressed by the invading trophoblasts. Instead, we and others postulate that these innate immune cells are necessary for successful implantation and pregnancy. However, elevated leukocyte infiltration may be an underlying cause of pregnancy complications, such as preterm labor or preeclampsia. Furthermore, such conditions have been attributed to an intrauterine infection. Therefore, we hypothesize that first trimester trophoblast cells, upon recognition of microbes through TLRs, may coordinate an immune response by recruiting cells of the innate immune system to the maternal-fetal interface. In this study, we have demonstrated that human first trimester trophoblast cells constitutively secrete the chemokines growth-related oncogene, growth-related oncogene α, IL-8, and MCP-1 and are able to recruit monocytes and NK cells, and to a lesser degree, neutrophils. Following the ligation of TLR-3 by the viral ligand, poly(I:C), or TLR-4 by bacterial LPS, trophoblast secretion of chemokines is significantly increased and this in turn results in elevated monocyte and neutrophil chemotaxis. In addition, TLR-3 stimulation also induces trophoblast cells to secrete RANTES. These results suggest a novel mechanism by which first trimester trophoblast cells may differentially modulate the maternal immune system during normal pregnancy and in the presence of an intrauterine infection. Such altered trophoblast cell responses might contribute to the pathogenesis of certain pregnancy complications.
Somatic Hypermutation and Junctional Diversification at Ig Heavy Chain Loci in the Nurse Shark
Authors: Malecek Karolina , Brandman Julie , Brodsky Jennie E. , Ohta Yuko , Flajnik Martin F. , Hsu Ellen 
Published: April 2014

Abstract
We estimate there are ∼15 IgM H chain loci in the nurse shark genome and have characterized one locus. It consists of one V, two D, and one J germline gene segments, and the constant (C) region can be distinguished from all of the others by a unique combination of restriction endonuclease sites in Cμ2. On the basis of these Cμ2 markers, 22 cDNA clones were selected from an epigonal organ cDNA library from the same individual; their C region sequences proved to be the same up to the polyadenylation site. With the identification of the corresponding germline gene segments, CDR3 from shark H chain rearrangements could be analyzed precisely, for the first time. Considerable diversity was generated by trimming and N addition at the three junctions and by varied recombination patterns of the two D gene segments. The cDNA sequences originated from independent rearrangements events, and most carried both single and contiguous substitutions. The 53 point mutations occurred with a bias for transition changes (53%), whereas the 78 tandem substitutions, mostly 2–4 bp long, do not (36%). The nature of the substitution patterns is the same as for mutants from six loci of two nurse shark L chain isotypes, showing that somatic hypermutation events are very similar at both H and L chain genes in this early vertebrate. The cis-regulatory elements targeting somatic hypermutation must have already existed in the ancestral Ig gene, before H and L chain divergence.
T Cell Activation-Induced CrkII Binding to the Zap70 Protein Tyrosine Kinase Is Mediated by Lck-Dependent Phosphorylation of Zap70 Tyrosine 315
Authors: Gelkop Sigal , Gish Gerrald D. , Babichev Yael , Pawson Tony , Isakov Noah 
Published: April 2014

Abstract
The Zap70 protein tyrosine kinase controls TCR-linked signal transduction pathways and is critical for T cell development and responsiveness. Following engagement of TCR, the Zap70 undergoes phosphorylation on multiple tyrosine residues that are implicated in the regulation of its catalytic activity and interaction with signaling effector molecules downstream of the TCR. We have shown previously that the CT10 regulator of kinase II (CrkII) adapter protein interacts with tyrosine-phosphorylated Zap70 in TCR-engaged T cells, and now extend these studies to show that Tyr315 in the Zap70 interdomain B region is the site of interaction with CrkII. A point mutation of Tyr315 (Y315F) eliminated the CrkII-Zap70 interaction capacity. Phosphorylation of Tyr315 and Zap70 association with CrkII were both dependent upon the Lck protein tyrosine kinase. Previous studies demonstrated the Tyr315 is the Vav-Src homology 2 (SH2) binding site, and that replacement of Tyr315 by Phe impaired the function of Zap70 in TCR signaling. However, fluorescence polarization-based binding studies revealed that the CrkII-SH2 and the Vav-SH2 bind a phosphorylated Tyr315-Zap70-derived peptide with affinities of a similar order of magnitude (Kd of 2.5 and 1.02 μM, respectively). The results suggest therefore that the biological functions attributed to the association of Zap70 with Vav following T cell activation may equally reflect the association of Zap70 with CrkII, and further support a regulatory role for CrkII in the TCR-linked signal transduction pathway.