bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of Sustained Actin Dynamics by the TCR and Costimulation as a Mechanism of Receptor Localization
Authors: Tskvitaria-Fuller Irina , Rozelle Andrew L. , Yin Helen L. , Wülfing Christoph 
Published: April 2014

AbstractThe localization of receptors, signaling intermediates, and cytoskeletal components at the T cell/APC interface is thought to be a major determinant of efficient T cell activation. However, important questions remain open. What are the dynamics of the T cell cytoskeleton as a potential mediator of such localization? How are they regulated by the TCR and costimulatory receptors? Do they actually mediate receptor localization? In this study, we have addressed these questions. Even under limiting T cell activation conditions, actin accumulated immediately and transiently at the T cell/APC interface, the microtubule organizing center reoriented toward it. In contrast, sustained (&gt;5 min) actin accumulation in highly dynamic patterns depended on an optimal T cell stimulus: high concentrations of the strong TCR ligand agonist peptide/MHC and engagement of the costimulatory receptors CD28 and LFA-1 were required in an overlapping, yet distinct, fashion. Intact sustained actin dynamics were required for interface accumulation of TCR/MHC in a central pattern and for efficient T cell proliferation, as established using a novel approach to selectively block only the sustained actin dynamics. These data suggest that control of specific elements of actin dynamics by TCR and costimulatory receptors is a mechanism to regulate the efficiency of T cell activation.
Surface Expression of Notch1 on Thymocytes: Correlation with the Double-Negative to Double-Positive Transition
Authors: Huang Eugene Y. , Gallegos Alena M. , Richards Sabrina M. , Lehar Sophie M. , Bevan Michael J. 
Published: April 2014

Abstract
Notch1 plays a critical role in regulating T lineage commitment during the differentiation of lymphoid precursors. The physiological relevance of Notch1 signaling during subsequent stages of T cell differentiation has been more controversial. This is due in part to conflicting data from studies examining the overexpression or targeted deletion of Notch1 and to difficulties in distinguishing between the activities of multiple Notch family members and their ligands, which are expressed in the thymus. We employed a polyclonal antiserum against the extracellular domain of Notch1 to study surface expression during thymopoiesis. We found high levels of Notch1 on the cell surface only on double negative (DN) stage 2 through the immature single-positive stage of thymocyte development, before the double-positive (DP) stage. The Notch signaling pathway, as read out by Deltex1 expression levels, is highly active in DN thymocytes. When an active Notch1 transgene, Notch1IC, is exogenously introduced into thymocytes of recombinase-activating gene 2-deficient mice, it promotes proliferation and development to the DP stage following anti-CD3 treatment without apparently affecting the intensity of pre-TCR signaling. In addition, a stromal cell line expressing the Notch ligand, Delta-like-1, promotes the in vitro expansion of wild-type DN3 thymocytes in vitro. Consistent with other recent reports, these data suggest a role for Notch1 during the DN to DP stage of thymocyte maturation and suggest a cellular mechanism by which Notch1IC oncogenes could contribute to thymoma development and maintenance.
CpG DNA Induces a Class II Transactivator-Independent Increase in Class II MHC by Stabilizing Class II MHC mRNA in B Lymphocytes
Authors: Kuchtey John , Pennini Meghan , Pai Rish K. , Harding Clifford V. 
Published: April 2014

AbstractMicrobial products, such as CpG DNA and LPS, enhance class II MHC (MHC-II) expression and Ag presentation by dendritic cells, but this effect does not occur with macrophages and is largely unexplored in B cells. Although MHC-II expression is influenced by transcriptional regulation, which is governed by class II transactivator (CIITA) in all cells, microbial products enhance MHC-II expression by dendritic cells in part by increasing MHC-II protein stability. In this study, we show that the CpG-induced increase in MHC-II expression by B lymphocytes is not due to protein stabilization or changes in CIITA expression or activity, but instead is due to increased stability of MHC-II mRNA. This CIITA-independent mechanism adds a new layer of complexity to regulation of MHC-II and may increase T cell help for B cell Ab responses to microbial or vaccine Ags.
Interaction of Murine Precursor B Cell Receptor with Stroma Cells Is Controlled by the Unique Tail of λ5 and Stroma Cell-Associated Heparan Sulfate
Authors: Bradl Harald , Wittmann Jürgen , Milius Doreen , Vettermann Christian , Jäck Hans-Martin 
Published: April 2014

AbstractEfficient clonal expansion of early precursor B (pre-B) cells requires signals delivered by an Ig-like integral membrane complex, the so-called pre-B cell receptor (pre-BCR). A pre-BCR consists of two membrane μH chains, two covalently associated surrogate L chains, and the heterodimeric signaling transducer Igαβ. In contrast to a conventional Ig L chain, the surrogate L chain is a heterodimer composed of the invariant polypeptides VpreB and λ5. Although it is still unclear how pre-BCR signals are initiated, two recent findings support a ligand-dependent initiation of pre-BCR signals: 1) a pre-BCR/galectin-1 interaction is required to induce phosphorylation of Igαβ in a human precursor B line, and 2) soluble murine as well as human pre-BCR molecules bind to stroma and other adherent cells. In this study, we show that efficient binding of a soluble murine pre-BCR to stroma cells requires the non-Ig-like unique tail of λ5. Surprisingly however, a murine pre-BCR, in contrast to its human counterpart, does not interact with galectin-1, as revealed by lactose blocking, RNA interference, and immunoprecipitation assays. Finally, the binding of a murine pre-BCR to stroma cells can be blocked either with heparin or by pretreatment of stroma cells with heparitinase or a sulfation inhibitor. Hence, efficient binding of a murine pre-BCR to stroma cells requires the unique tail of λ5 and stroma cell-associated heparan sulfate. These findings not only identified heparan sulfate as potential pre-BCR ligands, but will also facilitate the development of appropriate animal models to determine whether a pre-BCR/heparan sulfate interaction is involved in early B cell maturation.
Cholera Toxin Promotes the Induction of Regulatory T Cells Specific for Bystander Antigens by Modulating Dendritic Cell Activation
Authors: Lavelle Ed C. , McNeela Edel , Armstrong Michelle E. , Leavy Olive , Higgins Sarah C. , Mills Kingston H. G. 
Published: April 2014

Abstract
It has previously been reported that cholera toxin (CT) is a potent mucosal adjuvant that enhances Th2 or mixed Th1/Th2 type responses to coadministered foreign Ag. Here we demonstrate that CT also promotes the generation of regulatory T (Tr) cells against bystander Ag. Parenteral immunization of mice with Ag in the presence of CT induced T cells that secreted high levels of IL-4 and IL-10 and lower levels of IL-5 and IFN-γ. Ag-specific CD4+ T cell lines and clones generated from these mice had cytokine profiles characteristic of Th2 or type 1 Tr cells, and these T cells suppressed IFN-γ production by Th1 cells. Furthermore, adoptive transfer of bone marrow-derived dendritic cells (DC) incubated with Ag and CT induced T cells that secreted IL-4 and IL-10 and low concentrations of IL-5. It has previously been shown that IL-10 promotes the differentiation or expansion of type 1 Tr cells. Here we found that CT synergized with low doses of LPS to induce IL-10 production by immature DC. CT also enhanced the expression of CD80, CD86, and OX40 (CD134) on DC and induced the secretion of the chemokine, macrophage inflammatory protein-2 (MIP-2), but inhibited LPS-driven induction of CD40 and ICAM-I expression and production of the inflammatory cytokines/chemokines IL-12, TNF-α, MIP-1α, MIP-1β, and monocyte chemoattractant protein-1. Our findings suggest that CT induces maturation of DC, but, by inducing IL-10, inhibiting IL-12, and selectively affecting surface marker expression, suppresses the generation of Th1 cells and promotes the induction of T cells with regulatory activity.
A Transgenic Mouse Model Genetically Tags All Activated CD8 T Cells
Authors: Maris Charles H. , Miller Joseph D. , Altman John D. , Jacob Joshy 
Published: April 2014

AbstractIdentifying and characterizing Ag-specific CD8+ T cells are central to the study of immunological memory. Although powerful strategies such as MHC tetramers and peptide-induced cytokine production assays exist for identifying Ag-specific CD8+ T cells, alternate strategies that are not dependent upon a priori knowledge of the immunodominant and subdominant antigenic epitopes, as well as the MHC background of the animal are of obvious utility. In this study, we present a transgenic mouse model that uses Cre-loxP recombination to permanently mark all activated CD8+ T cells with β-galactosidase. We used the lymphocytic choriomeningitis virus infection model to track the dynamics of the antiviral CD8+ T cell responses. We show that in this transgenic mouse model system, all of the antiviral effector and memory CD8+ T cells are contained within the β-gal-marked CD8+ T cell population.
Most IL-4-Producing γδ Thymocytes of Adult Mice Originate from Fetal Precursors
Authors: Grigoriadou Kalliopi , Boucontet Laurent , Pereira Pablo 
Published: April 2014

AbstractThy-1dull γδ T cells constitute a distinct adult γδ T cell subset characterized by the expression of a TCR composed of Vγ1Cγ4 and Vδ6Cδ chains with limited junctional sequence diversity. However, several features of the expressed Thy-1dull TCR-γδ genes, in particular the absence or minimal presence of N region diversity and the almost invariable Dδ2-Jδ1 junction, are typical of rearrangements often found in the fetal thymus. In this study, we have investigated the origin of these cells. Few Thy-1dull γδ thymocytes developed in syngeneic radiation adult chimeras, regardless of whether the recipient mice were given adult bone marrow or fetal liver cells as a source of hemopoietic precursors. In contrast, normal numbers of Thy-1dull γδ T cells developed in fetal thymi grafted into adult syngeneic recipients. Interestingly, the majority of Thy-1dull γδ thymocytes present in the grafts were of graft origin, even when most conventional γδ and αβ thymocytes in the grafted thymi originated from T cell precursors of recipient origin. Single-cell PCR analyses of the nonselected TCR-γ rearrangements present in adult Thy-1dull γδ thymocytes revealed that more than one-half of these cells represent the progenies of a limited number of clones that greatly expanded possibly during the first weeks of life. Finally, the second TCR-δ allele of a large number of Thy-1dull γδ Τ cells contained incomplete TCR-δ rearrangements, thus providing an explanation for the adult-type rearrangements previously found among nonfunctional V(D)J rearrangements present in Thy-1dull γδ thymocytes.
TCR Binding Kinetics Measured with MHC Class I Tetramers Reveal a Positive Selecting Peptide with Relatively High Affinity for TCR
Authors: Holmberg Kaisa , Mariathasan Sanjeev , Ohteki Toshiaki , Ohashi Pamela S. , Gascoigne Nicholas R. J. 
Published: April 2014

AbstractThe interaction between TCR and peptide-MHC (pMHC) complexes is crucial for the activation of T cells as well as for positive and negative selection in the thymus. The kinetics and affinity of this interaction and the densities of TCR and pMHC complexes on the cell surface are determining factors for different outcomes during thymic selection. In general, it is thought that agonist pMHC, which cause negative selection, have higher affinities and, in particular, slower off-rates than partial or weak agonists and antagonists, which cause positive selection. In this study, we have used pMHC tetramers to investigate the kinetics of TCR-pMHC interaction for agonist, weak agonist, and antagonist ligands of the anti-lymphocytic choriomeningitis virus P14 TCR. Kinetics determined on the cell surface may be biologically more relevant than methods using soluble proteins. We can distinguish between agonists and weak agonists or antagonists based on the half-life and the avidity of tetramer-TCR interaction. Furthermore, we show that a weak agonist self-peptide that positively selects P14 TCR+ thymocytes has a tetramer half-life and avidity only slightly weaker than strong agonists. We show that, in fact, it can act as quite a strong agonist, but that its poor ability to stabilize MHC causes it instead to have a weak agonist phenotype.
Molecular Cloning of C4 Gene and Identification of the Class III Complement Region in the Shark MHC
Authors: Terado Tokio , Okamura Kazuhiko , Ohta Yuko , Shin Dong-Ho , Smith Sylvia L. , Hashimoto Keiichiro , Takemoto Tadashi , Nonaka Mayumi I. , Kimura Hiroshi , Flajnik Martin F. , Nonaka Masaru 
Published: April 2014

AbstractTo clarify the evolutionary origin of the linkage of the MHC class III complement genes with the MHC class I and II genes, we isolated C4 cDNA from the banded hound shark (Triakis scyllium). Upon phylogenetic tree analysis, shark C4 formed a well-supported cluster with C4 of higher vertebrates, indicating that the C3/C4 gene duplication predated the divergence of cartilaginous fish from the main line of vertebrate evolution. The deduced amino acid sequence predicted the typical C4 three-subunits chain structure, but without the histidine residue catalytic for the thioester bond, suggesting the human C4A-like specificity. The linkage analysis of the complement genes, one C4 and two factor B (Bf) genes, to the shark MHC was performed using 56 siblings from two typing panels of T. scyllium and Ginglymostoma cirratum. The C4 and one of two Bf genes showed a perfect cosegregation with the class I and II genes, whereas two recombinants were identified for the other Bf gene. These results indicate that the linkage between the complement C4 and Bf genes, as well as the linkage between these complement genes and the MHC class I and II genes were established before the emergence of cartilaginous fish &gt;460 million years ago.
T Cell Recognition of Distinct Peptide:I-Au Conformers in Murine Experimental Autoimmune Encephalomyelitis
Authors: Huang Jason C. , Han Mei , Minguela Alfredo , Pastor Silvia , Qadri Ayub , Ward E. Sally 
Published: April 2014

AbstractWe have used T cells bearing TCRs that are closely related in sequence as probes to detect conformational variants of peptide-MHC complexes in murine experimental autoimmune encephalomyelitis in H-2u mice. The N-terminal epitope of myelin basic protein (MBP) is immunodominant in this model. Our studies have primarily focused on T cell recognition of a position 4 analog of this peptide (MBP1–9[4Y]) complexed with I-Au. Using site-directed mutagenesis, we have mapped the functionally important complementarity determining region residues of the 1934.4 TCR Vα domain. One of the resulting mutants (Tyr95 to alanine in CDR3α, Y95A) has interesting properties: relative to the parent wild-type TCR, this mutant poorly recognizes Ag complexes generated by pulsing professional APCs (PL-8 cells) with MBP1–9[4Y] while retaining recognition of MBP1–9[4Y]-pulsed unconventional APCs or insect cell-expressed complexes of I-Au containing tethered MBP1–9[4Y]. Insect cell expression of recombinant I-Au with covalently tethered class II-associated invariant chain peptide or other peptides which bind relatively weakly, followed by proteolytic cleavage of the peptide linker and replacement by MBP1–9[4Y] in vitro, results in complexes that resemble peptide-pulsed PL-8 cells. Therefore, the distinct conformers can be produced in recombinant form. T cells that can distinguish these two conformers can also be generated by the immunization of H-2u mice, indicating that differential recognition of the conformers is observed for responding T cells in vivo. These studies have relevance to understanding the molecular details of T cell recognition in murine experimental autoimmune encephalomyelitis. They are also of particular importance for the effective use of multimeric peptide-MHC complexes to characterize the properties of Ag-specific T cells.
Regulation of the Human High Affinity IgE Receptor β-Chain Gene Expression Via an Intronic Element
Authors: Takahashi Kyoko , Nishiyama Chiharu , Hasegawa Masanari , Akizawa Yushiro , Ra Chisei 
Published: April 2014

AbstractThe high affinity IgE receptor, FcεRI, is a key regulatory molecule in the allergic reaction. By screening for cis-acting elements over the entire region of the human FcεRI β-chain gene, a sequence located in the fourth intron was revealed to serve as a repressor element. This element was recognized by a transcription factor, myeloid zinc finger protein 1 (MZF-1). Introduction of MZF-1 antisense inhibited the suppressive effect of the element on the β-chain promoter and increased the mRNA for the β-chain in KU812 cells, indicating that MZF-1 repressed human FcεRI β-chain gene expression via the element in the fourth intron. Furthermore, it was suggested that a cofactor binding with MZF-1, whose expression level was different among the cell types, was required for transcriptional repression by MZF-1.
Functional Requirements for Interactions Between CD84 and Src Homology 2 Domain-Containing Proteins and Their Contribution to Human T Cell Activation
Authors: Tangye Stuart G. , Nichols Kim E. , Hare Nathan J. , van de Weerdt Barbara C. M. 
Published: April 2014

AbstractCell surface receptors belonging to the CD2 subset of the Ig superfamily of molecules include CD2, CD48, CD58, 2B4, signaling lymphocytic activation molecule (SLAM), Ly9, CD84, and the recently identified molecules NTB-A/Ly108/SLAM family (SF) 2000, CD84H-1/SF2001, B lymphocyte activator macrophage expressed (BLAME), and CRACC (CD2-like receptor-activating cytotoxic cells)/CS-1. Some of these receptors, such as CD2, SLAM, 2B4, CRACC, and NTB-A, contribute to the activation and effector function of T cells and NK cells. Signaling pathways elicited via some of these receptors are believed to involve the Src homology 2 (SH2) domain-containing cytoplasmic adaptor protein SLAM-associated protein (SAP), as it is recruited to SLAM, 2B4, CD84, NTB-A, and Ly-9. Importantly, mutations in SAP cause the inherited human immunodeficiency X-linked lymphoproliferative syndrome (XLP), suggesting that XLP may result from perturbed signaling via one or more of these SAP-associating receptors. We have now studied the requirements for SAP recruitment to CD84 and lymphocyte activation elicited following ligation of CD84 on primary and transformed human T cells. CD84 was found to be rapidly tyrosine phosphorylated following receptor ligation on activated T cells, an event that involved the Src kinase Lck. Phosphorylation of CD84 was indispensable for the recruitment of SAP, which was mediated by Y262 within the cytoplasmic domain of CD84 and by R32 within the SH2 domain of SAP. Furthermore, ligating CD84 enhanced the proliferation of anti-CD3 mAb-stimulated human T cells. Strikingly, this effect was also apparent in SAP-deficient T cells obtained from patients with XLP. These results reveal a novel function of CD84 on human lymphocytes and suggest that CD84 can activate human T cells via a SAP-independent mechanism.
The Block in Immunoglobulin Class Switch Recombination Caused by Activation-Induced Cytidine Deaminase Deficiency Occurs Prior to the Generation of DNA Double Strand Breaks in Switch μ Region
Authors: Catalan Nadia , Selz Françoise , Imai Kohsuke , Revy Patrick , Fischer Alain , Durandy Anne 
Published: April 2014

AbstractAffinity maturation of the Ab repertoire in germinal centers leads to the selection of high affinity Abs with selected heavy chain constant regions. Ab maturation involves two modifications of the Ig genes, i.e., somatic hypermutation and class switch recombination. The mechanisms of these two processes are not fully understood. As shown by the somatic hypermutation and class switch recombination-deficient phenotype of activation-induced cytidine deaminase (AID)-deficient patients (hyperIgM type 2 syndrome) and mice, both processes require the AID molecule. Somatic DNA modifications require DNA breaks, which, at least for class switch recombination, lead to dsDNA breaks. By using a ligation-mediated PCR, it was found that class switch recombination-induced dsDNA breaks in Sμ switch regions were less frequent in AID-deficient B cells than in AID-proficient B cells, thus indicating that AID acts upstream of DNA break induction.
IFN-γ-Producing γδ T Cells Help Control Murine West Nile Virus Infection
Authors: Wang Tian , Scully Eileen , Yin Zhinan , Kim Jung H. , Wang Sha , Yan Jun , Mamula Mark , Anderson John F. , Craft Joe , Fikrig Erol 
Published: April 2014

Abstract
West Nile (WN) virus causes fatal meningoencephalitis in laboratory mice, thereby partially mimicking human disease. Using this model, we have demonstrated that mice deficient in γδ T cells are more susceptible to WN virus infection. TCRδ−/− mice have elevated viral loads and greater dissemination of the pathogen to the CNS. In wild-type mice, γδ T cells expanded significantly during WN virus infection, produced IFN-γ in ex vivo assays, and enhanced perforin expression by splenic T cells. Adoptive transfer of γδ T cells to TCRδ−/− mice reduced the susceptibility of these mice to WN virus, and this effect was primarily due to IFN-γ-producing γδ T cells. These data demonstrate a distinct role for γδ T cells in the control of and prevention of mortality from murine WN virus infection.
Functional Plasticity of Dendritic Cell Subsets as Mediated by CD40 Versus B7 Activation
Authors: Grohmann Ursula , Bianchi Roberta , Orabona Ciriana , Fallarino Francesca , Vacca Carmine , Micheletti Alessandra , Fioretti Maria C. , Puccetti Paolo 
Published: April 2014

Abstract
Murine dendritic cells (DCs) can present Ag in an immunogenic or tolerogenic fashion, the distinction depending on either the occurrence of specialized DC subsets or the maturation or activation state of the DC. Although DC subsets may be programmed to direct either tolerance or immunity, it is not known whether appropriate environmental stimulation can result in complete flexibility of a basic program. Using splenic CD8− and CD8+ DCs that mediate the respective immunogenic and tolerogenic presentation of self peptides, we show that both the in vivo and in vitro activities of either subset can be altered by ligation of specific surface receptors. Otherwise immunogenic CD8− DCs become tolerogenic upon B7 ligation by soluble CTLA-4, a maneuver that initiates immunosuppressive tryptophan catabolism. In contrast, CD40 ligation on tolerogenic CD8+ DCs makes these cells capable of immunogenic presentation. Thus, environmental conditioning by T cell ligands may alter the default function of DC subsets to meet the needs of flexibility and redundancy.