bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement ofmi-Transcription Factor in Expression of α-Melanocyte-Stimulating Hormone Receptor in Cultured Mast Cells of Mice
Authors: Adachi Shiro , Morii Eiichi , Kim Dae-ki , Ogihara Hideki , Jippo Tomoko , Ito Akihiko , Lee Young-Mi , Kitamura Yukihiko 
Published: April 2014

AbstractThe microphthalmia (mi) locus encodes a member of the basic-helix-loop-helix-leucine zipper (bHLH-Zip) protein family of transcription factors (MITF). We have reported that expression of several genes was impaired in cultured mast cells (CMCs) of mi/mi mice due to a defective transactivation ability of mutant MITF (mi-MITF). We also found that mi/mi CMCs did not express a receptor (MC1R) for α-melanocyte-stimulating hormone. The overexpression of the wild-type (+/+) MITF but not mi-MITF normalized the expression of the MC1R in mi/mi CMCs, indicating the involvement of +-MITF in the MC1R gene expression. Next, we analyzed the promoter region of the MC1R gene by the transient cotransfection assay. The luciferase construct under the control of the MC1R promoter and the cDNA-encoding +-MITF or mi-MITF were cotransfected into NIH/3T3 fibroblasts. The cotransfection of +-MITF but not mi-MITF increased the luciferase activity. There were five CANNTG motifs recognized by bHLH-Zip-type transcription factors in the cloned promoter region. We found +-MITF bound two of five CANNTG motifs, and both motifs were essential for the transactivation of the MC1R gene by +-MITF. These results indicated that +-MITF directly transactivated the MC1R gene through these two motifs.
Contribution of Individual Amino Acids Within MHC Molecule or Antigenic Peptide to TCR Ligand Potency
Authors: Hemmer Bernhard , Pinilla Clemencia , Gran Bruno , Vergelli Marco , Ling Nick , Conlon Paul , McFarland Henry F. , Houghten Richard , Martin Roland 
Published: April 2014

Abstract
The TCR recognition of peptides bound to MHC class II molecules is highly flexible in some T cells. Although progress has been made in understanding the interactions within the trimolecular complex, to what extent the individual components and their amino acid composition contribute to ligand recognition by individual T cells is not completely understood. We investigated how single amino acid residues influence Ag recognition of T cells by combining several experimental approaches. We defined TCR motifs for CD4+ T cells using peptide synthetic combinatorial libraries in the positional scanning format (PS-SCL) and single amino acid-modified peptide analogues. The similarity of the TCR motifs defined by both methods and the identification of stimulatory antigenic peptides by the PS-SCL approach argue for a contribution of each amino acid residue to the overall potency of the antigenic peptide ligand. In some instances, however, motifs are formed by adjacent amino acids, and their combined influence is superimposed on the overall contribution of each amino acid within the peptide epitope. In contrast to the flexibility of the TCR to interact with different peptides, recognition was very sensitive toward modifications of the MHC-restriction element. Exchanges of just one amino acid of the MHC molecule drastically reduced the number of peptides recognized. The results indicate that a specific MHC molecule not only selects certain peptides, but also is crucial for setting an affinity threshold for TCR recognition, which determines the flexibility in peptide recognition for a given TCR.
TNF-α Regulates Transforming Growth Factor-α Expression in Regenerating Murine Liver and Isolated Hepatocytes
Authors: Gallucci Randle M. , Simeonova Petia P. , Toriumi Wataru , Luster Michael I. 
Published: April 2014

Abstract
TNF-α is a pleotropic proinflammatory cytokine that has been implicated as a contributing factor in a number of disease processes, primarily through its ability to induce the expression of inflammatory and cytotoxic mediators. TNF-α is also involved in cell growth accompanying the healing process in multiple organ systems and influences liver repair following hepatotoxic damage or regeneration following partial hepatectomy. In this respect, TNF-α is a known mitogen for hepatocytes. In this paper we describe a novel role for TNF-α in the modulation of expression of TGF-α, the latter being a complete hepatocyte mitogen. TNF-α directly up-regulates TGF-α mRNA by up to 7-fold in isolated mouse hepatocytes, whereas neutralization of TNF-α significantly decreased liver mRNA and protein expression of TGF-α following chemical-induced hepatotoxicity. That TNF-α directly stimulated TGF-α was suggested by the inability of either anti-IL-6 Abs or cycloheximide to inhibit TNF-α-induced TGF-α expression in hepatocytes. However, in the presence of anti-TGF-α neutralizing Abs, the mitogenic activity of TNF-α is abrogated. Using cells transfected with the TGF-α promoter, and an RNA polymerase inhibitor, it was shown that TNF-α modulates TGF-α expression through both pre- and posttranscriptional events. Taken together, these data suggest that TNF-α participates in liver repair and regeneration, in part, by directly inducing the expression of TGF-α.
Evidence for a Stepwise Evolution of the CD3 Family
Authors: Göbel Thomas W. F. , Dangy Jean-Pierre 
Published: April 2014

Abstract
The three CD3 components of the TCR complex are encoded as clustered genes in mammals. The evolution of such a multimeric complex is likely to occur stepwise. The chicken CD3 cluster was entirely sequenced, and, in contrast to mammals, only two chicken CD3 genes were found to be physically linked to the unrelated genes HZW10 and epithelial V-like Ag flanking both sides of the CD3 cluster. Biochemical analyses of CD3 immunoprecipitates confirmed the presence of only two CD3 proteins and revealed an essential role for CD3γδ glycosylation during assembly. Functional analyses indicated that the chicken TCR/CD3 complex was efficiently down-regulated by phorbol ester treatment, demonstrating the integrity of a CD3γ-like cytoplasmic internalization motif. These data argue for a stepwise CD3 evolution, with major differences in the TCR/CD3 structure between mammalian and nonmammalian vertebrates setting a basis for the understanding of the CD3 phylogeny and proving the ancestral nature of the CD3γδ protein.
Transgenic Expression of Ly-49A in Thymocytes Alters Repertoire Selection
Authors: Pauza Mary , Smith Kathleen M. , Neal Heather , Reilly Christina , Lanier Lewis L. , Lo David 
Published: April 2014

AbstractA T cell-specific Ly-49A transgene inhibits TCR-mediated activation in the presence of H-2Dd. Expression of this transgene by developing thymocytes impairs negative selection evidenced by a failure to delete potentially autoreactive T cells and development of a graft-vs-host-disease-like syndrome. In mice carrying both the Ly-49A and a class II-restricted TCR transgene, positive selection was lost, but only when H-2Dd was present on thymic epithelium. These results are consistent with models suggesting that thymic selection is dependent on the perceived intensity of TCR signaling. More interestingly, these results show that Ly-49A does not simply provide a strict on/off switch for T cell responses. Since Ly-49A may shift the signaling threshold of TCR-induced triggering, inducible expression of Ly-49A may regulate peripheral memory/activated T cells by raising the threshold for T cell reactivation.
Frequency and Characterization of Phenotypic Ig Heavy Chain Allelically Included IgM-Expressing B Cells in Mice
Authors: Barreto Vasco , Cumano Ana 
Published: April 2014

AbstractIg H chain (IgH) allelic exclusion remains a puzzling topic. Here, we address the following question: Do phenotypic IgH allelically included cells exist in normal mice and, if so, at what frequency? Sorted cells from heterozygous mice were evaluated for the expression of both IgM allotypes by double intracytoplasmic stainings. Dual expressors were found at a frequency of 1 in 104 splenic B cells. These data were confirmed by direct sequencing of IgH-rearranged alleles obtained after single cell (or clone) PCR on dual expressors. Typically, these cells have one rearranged J558 VH whereas, in the other allele, a D-proximal VH gene is used. Interestingly, dual expressors have rearranged IgH alleles with similar CDR3 lengths. These results show that, in contrast to the κ L chain and the TCR β-chain, IgH allelic exclusion is the result of an extremely stringent mechanism. We discuss two non-mutually exclusive scenarios for the origin of IgH dual expressors: 1) IgH allelically included cells arise when the first allele to rearrange productively is unable to form a pre-BCR; dual expressors could be a subset of this population in which, upon conventional L chain rearrangement, both IgH are expressed at the surface; and 2) synchronous rearrangement of the IgH alleles.
Extension of HLA-A*0201-Restricted Minimal Epitope by Nε-Palmitoyl-lysine Increases the Life Span of Functional Presentation to Cytotoxic T Cells
Authors: Loing Estelle , Andrieu Muriel , Thiam Kader , Schörner Dominik , Wiesmüller Karl-Heinz , Hosmalin Anne , Jung Günther , Gras-Masse Hélène 
Published: April 2014

Abstract
The delineation of the minimal requirements for efficient delivery of functional cytotoxic epitopes into APC could be a step toward the definition of “minimal length” lipopeptides for the modulation of CTL activity. Several analogues of the HLA-A*0201-restricted HIV-1 polymerase (pol476–484) minimal cytotoxic epitope were obtained by modifying P0, P1, or P10 positions by a single Nε-palmitoyl-lysine residue. The use of fluorescent derivatives confirmed the cell-permeating activities and suggested that a P0- and a P1-modified lipopeptide possessing ionizable extremities fulfills the structural requirements for MHC loading. The expressions of HLA-peptide complexes at the surface of TAP-deficient cells incubated with the parent epitope or lipopeptide derivatives were compared, in terms of intensity and stability. Both lipopeptides induced a considerably prolonged expression of conformationally correct complexes, which were dependent on the integrity of the exocytosis pathway, suggesting a dynamic mechanism of formation or reloading of the complexes from an intracellular pool. The agonistic activities of the different HLA-peptide complexes were evaluated using two independent T cell lines from HIV-infected donors. We report that a lipodecapeptide obtained by N-terminal addition of a Nε-palmitoyl-lysine to the pol476–484 epitope was able to increase the life span of functional presentation to cytotoxic T cells specific for the parent peptide.
Bacterial Clearance and Survival Are Dependent on CXC Chemokine Receptor-2 Ligands in a Murine Model of Pulmonary Nocardia asteroides Infection
Authors: Moore Thomas A. , Newstead Michael W. , Strieter Robert M. , Mehrad Borna , Beaman Blaine L. , Standiford Theodore J. 
Published: April 2014

Abstract
Survival from murine pulmonary nocardiosis is highly dependent on CXC chemokine receptor-2 (CXCR2) ligand-mediated neutrophil chemotaxis and subsequent clearance of the infectious agent Nocardia asteroides. Intratracheal inoculation of N. asteroides rapidly up-regulated the CXC chemokines macrophage inflammatory protein-2 (MIP-2) and KC within 24 h, with levels remaining elevated through day 3 before returning to near baseline levels by day 7. Coinciding with elevated MIP-2 and KC were the rapid recruitment of neutrophils and clearance of the organism. Anti-Ly-6G Ab-mediated neutrophil depletion before bacterial challenge resulted in strikingly increased mortality to N. asteroides infection. The relative contribution of MIP-2 in neutrophil recruitment was examined by anti-MIP-2 Ab treatment before nocardial infection. MIP-2 neutralization had no detrimental effects on survival, neutrophil recruitment, or bacterial clearance, suggesting the usage of additional or alternative CXCR2-binding ligands. The importance of the CXC family of chemokines was determined by the administration of an anti-CXCR2 Ab capable of blocking ligand binding in vivo. Anti-CXCR2 treatment greatly increased mortality by preventing neutrophil migration into the lung. Paralleling this impaired neutrophil recruitment was a 100-fold increase in lung bacterial burden. Combined, these observations indicate a critical role for neutrophils and CXC chemokines during nocardial pneumonia. These data directly link CXCR2 ligands and neutrophil recruitment and lend further support to the concept of CXC chemokine redundancy. For infections highly dependent on neutrophils, such as nocardial pneumonia, this is of critical importance.
Type 1 and Type 2 CD8+ Effector T Cell Subpopulations Promote Long-Term Tumor Immunity and Protection to Progressively Growing Tumor
Authors: Dobrzanski Mark J. , Reome Joyce B. , Dutton Richard W. 
Published: April 2014

AbstractCytolytic CD8+ effector cells fall into two subpopulations based on cytokine secretion. Type 1 CD8+ T cells (Tc1) secrete IFN-γ, whereas type 2 CD8+ T cells (Tc2) secrete IL-4, IL-5, and IL-10. Using an OVA-transfected B16 lung metastases model, we assessed the therapeutic effects of adoptively transferred OVA-specific Tc1 and Tc2 subpopulations in mice bearing established pulmonary malignancy. Effector cell-treated mice exhibiting high (5 × 105) tumor burdens experienced significant (p &lt; 0.05) delays in mortality compared with those of untreated control mice, whereas high proportions (70–90%) of mice receiving therapy with low (1 × 105) tumor burdens survived indefinitely. Long-term tumor immunity was evident by resistance to lethal tumor rechallenge, heightened levels of systemic OVA Ag-specific CTL responses ex vivo, and detection of long-lived TCR transgene-positive donor cells accompanied by an elevation in the total numbers of CD8+ CD44high activated and/or memory T cells at sites of tumor growth. Long-lasting protection by Tc2 and Tc1 effector cells were dependent, in part, on both the level of tumor burden and effector cell-derived IL-4, IL-5, and IFN-γ, respectively. We conclude that Tc1 and Tc2 effector cells provide immunity by different mechanisms that subsequently potentiate host-derived antitumor responses.
Decreased Cytomegalovirus Expression Following Proinflammatory Cytokine Treatment of Primary Human Astrocytes
Authors: Cheeran Maxim C.-J. , Hu Shuxian , Gekker Genya , Lokensgard James R. 
Published: April 2014

Abstract
Understanding the influence of immune effector mechanisms on CMV infection of the CNS may facilitate the development of immunotherapies for viral encephalitis. Using cultures of highly purified, fully permissive primary human astrocytes, proinflammatory cytokines, but not antiinflammatory cytokines or β-chemokines, were found to inhibit CMV expression, DNA synthesis, and replication. Treatment with certain proinflammatory cytokines 24 h before CMV infection markedly suppressed viral expression in astrocytes. TNF-α, IL-1β, and IFN-γ all inhibited CMV expression (70 ± 4.2%, 65 ± 3.4%, and 82 ± 3.6% inhibition of viral expression, respectively, n = 5). In contrast, no viral suppression was observed following IL-6 treatment. Suppressive activity was dependent on the addition of cytokines before CMV infection. Cytokine pretreatment did not affect CMV entry into primary astrocytes, and the observed cytokine-induced suppressive activity was not affected by the NO synthase inhibitor NG-monomethyl-l-arginine (NGMA). Instead, the suppressive effect appeared to be mediated through a mechanism involving inhibition of CMV major immediate early promoter activity. These results support the hypothesis that proinflammatory cytokines possess anti-CMV activity in brain cells and may lead to new interventions for CMV encephalitis based upon immunotherapy.
Identification of Multiple Simian Immunodeficiency Virus (SIV)-Specific CTL Epitopes in Sooty Mangabeys with Natural and Experimentally Acquired SIV Infection
Authors: Kaur Amitinder , Yang Janet , Hempel Donna , Gritz Linda , Mazzara Gail P. , McClure Harold , Johnson R. Paul 
Published: April 2014

Abstract
Host immune responses to SIV infection in sooty mangabeys are likely to be an important determinant of how such nonhuman primate species maintain asymptomatic lentivirus infection. We have previously described two patterns of asymptomatic SIV infection in sooty mangabeys: low viral loads with vigorous SIV-specific CTL activity in SIVmac239-infected sooty mangabeys, and high viral loads with generally weak or absent SIV-specific CTL activity in naturally infected sooty mangabeys. To define the specificity of the CTL response in SIV-infected mangabeys, we characterized CTL epitopes in two naturally infected and three SIVmac239-infected sooty mangabeys. Compared with that in SIVmac239-infected mangabeys, the yield of SIV-specific CTL clones was significantly lower in naturally infected sooty mangabeys. All CTL clones were phenotypically CD3+ CD8+, and lysis was MHC restricted. Seven SIV CTL epitopes were identified in five sooty mangabeys: one in Gag and three each in Nef and Envelope (Env). The CTL epitopes mapped to conserved regions in the SIV genome and were immunodominant. Several similar or identical CTL epitopes were recognized by both naturally infected and SIVmac239-infected mangabeys that shared class I MHC alleles. To our knowledge, this is the first report of SIV-specific CTL epitopes in sooty mangabeys. Longitudinal studies of viral load and sequence variation in CTL epitopes may provide useful information on the role of CTL in control or persistence of SIV infection in sooty mangabeys.
Mechanism and Function of a Newly Identified CpG DNA Motif in Human Primary B Cells
Authors: Hartmann Gunther , Krieg Arthur M. 
Published: April 2014

Abstract
The vertebrate immune system recognizes bacterial DNA based on the presence of unmethylated CpG-dinucleotides in particular base contexts (“CpG motifs”). In contrast to mice, knowledge about CpG-mediated effects on human B cells is poor. In the present study we identify and determine an optimal human CpG motif. A phosphodiester oligonucleotide containing this motif strongly stimulated CD86, CD40, CD54, and MHC class II expression, IL-6 synthesis, and proliferation of primary human B cells. These effects required internalization of the oligonucleotide and endosomal maturation. The molecular mechanism of action of this CpG motif was associated with the sustained induction of the NF-κB p50/p65 heterodimer and of the transcription-factor complex AP-1. Transcription-factor activation by CpG DNA was preceded by increased phosphorylation of the stress kinases c-Jun N-terminal kinase and p38, and of activating transcription factor-2. In contrast to CpG, signaling through the B cell receptor led to activation of extracellular receptor kinase and to phosphorylation of a different isoform of c-Jun N-terminal kinase. These studies define the structure of a highly active human CpG motif and characterize its molecular mechanism of action in primary human B cells.
Ebola Virus Secretory Glycoprotein (sGP) Diminishes FcγRIIIB-to-CR3 Proximity on Neutrophils
Authors: Kindzelskii Andrei L. , Yang Zhi-yong , Nabel Gary J. , Todd Robert F. , Petty Howard R. 
Published: April 2014

Abstract
Previous studies have shown that Ebola virus’ secretory glycoprotein (sGP) binds to FcγRIIIB (CD16b) and inhibits L-selectin shedding. In this study, we test the hypothesis that sGP interferes with the physical linkage between CR3 and FcγRIIIB. Neutrophils were stained with rhodamine-conjugated anti-CD16b mAb (which does not inhibit sGP binding) and fluorescein-conjugated anti-CR3 mAb reagents and then incubated in media with or without sGP. Physical proximity between fluorochrome-labeled CR3 and FcγRIIIB on individual cells was measured by resonance energy transfer (RET) imaging, quantitative RET microfluorometry, and single-cell imaging spectrophotometry. Cells incubated with control supernatants displayed a significant RET signal, indicative of physical proximity (&lt;7 nm) between CR3 and FcγRIIIB. In contrast, cells exposed to sGP showed a significant reduction in the CR3-FcγRIIIB RET signal using these methods. Interestingly, colocalization and cocapping of CR3 and FcγRIIIB were not affected, suggesting that the proximity of these two receptors is reduced without triggering dissociation. Thus, sGP alters the physical linkage between FcγRIIIB and CR3.
Activation of Human Neutrophils byMycobacterium tuberculosisH37Ra Involves Phospholipase Cγ2, Shc Adapter Protein, and p38 Mitogen-Activated Protein Kinase
Authors: Perskvist Nasrin , Zheng Limin , Stendahl Olle 
Published: April 2014

AbstractRecent studies have shown that human neutrophils play a significant protective role in mycobacteria infection. When encountered with mycobacteria, neutrophils exhibit the typical early bactericidal responses including phagocytosis and generation of reactive oxygen intermediates (ROI), but the underlying mechanisms are largely unknown. The present study shows that stimulation of neutrophils with an attenuated strain of Mycobacterium tuberculosis H37Ra (Mtb) led to a tyrosine kinase-dependent ROI production in these cells. Stimulation with Mtb induces a rapid and transient tyrosine phosphorylation of several proteins, one of which was identified as phospholipase Cγ2 (PLCγ2). Several tyrosine-phosphorylated proteins were associated with the PLCγ2 precipitates from Mtb-stimulated neutrophils, of which pp46 was characterized as the Shc adapter protein. A role for PLCγ2-Shc association in the generation of ROI is supported by the observations that stimulation with Mtb causes the activation of p38 mitogen-activated protein kinase (MAPK), a downstream target of the Shc/Ras signaling cascade, and that the effect of genistein on ROI production coincided with its ability to inhibit both PLCγ2-Shc association and p38 MAPK activation. Moreover, pretreatment of neutrophils with a PLC inhibitor markedly suppresses the Mtb-stimulated ROI production as well as p38 MAPK activation in these cells. Taken together, these results indicate that stimulation of neutrophils with Mtb triggers the tyrosine phosphorylation of PLCγ2 and its association with Shc, and that such association is critical for the Mtb-stimulated ROI production through activating p38 MAPK.
Lipopolysaccharide Activates Distinct Signaling Pathways in Intestinal Epithelial Cell Lines Expressing Toll-Like Receptors
Authors: Cario Elke , Rosenberg Ian M. , Brandwein Steven L. , Beck Paul L. , Reinecker Hans-Christian , Podolsky Daniel K. 
Published: April 2014

Abstract
LPS elicits several immediate proinflammatoy responses in peripheral blood leukocytes via a recently described pathway including CD14, Toll-like receptors (TLR), serine-threonine kinases, and NF-κB transcription factor. However, the functional responses of intestinal epithelial cells (IEC) to stimulation with LPS are unknown. Expression of mRNA and protein for CD14 and TLRs were assessed by RT-PCR, immunoblotting, and immunohistochemistry in mouse and human IEC lines. LPS-induced activation of signaling pathways (p42/p44 mitogen-activated protein kinase (MAPK), c-Jun NH2-terminal kinase (JNK), p38, p65, NF-κB) were assessed by immunoblotting and gel shifts. CD14 mRNA and protein expression were not detectable in IEC. However, human TLR2, TLR3, and TLR4 mRNA were present in IEC. TLR4 protein was expressed in all cell lines; however, TLR2 protein was absent in HT29 cells. Immunofluorescent staining of T84 cells demonstrated the cell-surface presence of the TLRs. LPS-stimulation of IEC resulted in activation (&gt;1.5-fold) of the three members of the MAPK family. In contrast, LPS did not significantly induce activation of JNK and p38 in CMT93 cells, p38 in T84 cells and MAPK and JNK in HT29 cells. Downstream, LPS activated NF-κB in IEC in a time-, dose-, and serum-dependent manner. IEC express TLRs that appear to mediate LPS stimulation of specific intracellular signal transduction pathways in IEC. Thus, IEC may play a frontline role in monitoring lumenal bacteria.