bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unexpected Transcriptional Induction of Monocyte Chemoattractant Protein 1 by Proteasome Inhibition: Involvement of the c-Jun N-Terminal Kinase-Activator Protein 1 Pathway
Authors: Nakayama Kenji , Furusu Akira , Xu Qihe , Konta Tsuneo , Kitamura Masanori 
Published: April 2014

AbstractProteasome inhibitors, the well-known inhibitors of NF-κB, are recently considered therapeutic agents for inflammation. However, the anti-inflammatory properties of these agents have not been fully evaluated. In this report we describe a novel effect of proteasome inhibitors on the expression of monocyte chemoattractant protein 1 (MCP-1) in mesangial cells. We found that proteasome inhibitor MG132 dose-dependently induced expression of MCP-1 at the transcriptional level. The stimulatory effect was similarly observed with other proteasome inhibitors (proteasome inhibitor 1 and lactacystin) and in other cell types (NRK fibroblasts). The 5′-flanking region of the MCP-1 gene contains multiple AP-1 sites. To explore the mechanisms involved, we examined the effects of proteasome inhibition on the AP-1 pathway. Northern blot analysis showed that MG132 rapidly induced the expression of c-jun, but not c-fos. Immunoblot analysis showed that MG132 prevented degradation of c-Jun protein. Kinase assay revealed that c-Jun N-terminal kinase (JNK) was rapidly activated by MG132. Consistent with these results, a reporter assay showed that AP-1 activity was up-regulated after treatment with MG132. Curcumin, a pharmacological inhibitor of the JNK-AP-1 pathway, abrogated the induction of MCP-1 by MG132. Similarly, stable transfection with a dominant-negative mutant of c-Jun attenuated both MG132-induced activation of AP-1 and expression of MCP-1. The transcriptional activation by proteasome inhibitors was observed not only in MCP-1, but also in other AP-1-dependent genes, including stromelysin and mitogen-activated protein kinase phosphatase 1. These data revealed that proteasome inhibition triggered the expression of MCP-1 and other genes via the multistep induction of the JNK-c-Jun/AP-1 pathway.
A Novel Autocrine Pathway of Tumor Escape from Immune Recognition: Melanoma Cell Lines Produce a Soluble Protein That Diminishes Expression of the Gene Encoding the Melanocyte Lineage Melan-A/MART-1 Antigen Through Down-Modulation of Its Promoter
Authors: Kurnick James T. , Ramirez-Montagut Teresa , Boyle Lenora A. , Andrews David M. , Pandolfi Franco , Durda Paul J. , Butera David , Dunn Ian S. , Benson Elizabeth M. , Gobin Sam J. P. , van den Elsen Peter J. 
Published: April 2014

AbstractWe have observed that malignant melanoma cells produce a soluble protein factor(s), which down-regulates melanocyte lineage Melan-A/MART-1 Ag expression by melanoma cells with concomitant loss of recognition by Melan-A/MART-1-specific T cells. This down-modulation of Melan-A/MART-1 expression, which we refer to as “Ag silencing,” is mediated via its minimal promoter, whereas the promoter for the restricting Ag-presenting HLA-A2 molecule is not affected. Significantly, this Ag silencing is reversible, as removal of factor-containing supernatants from Melan-A/MART-1-expressing cells results in up-regulation of the promoter for the gene encoding this Ag, and renewed expression of the protein. We have evaluated over 20 known factors, none of which accounts for the Ag-silencing activity of the melanoma cell culture supernatants. The existence of this autocrine pathway provides an additional novel explanation for melanoma tumor progression in vivo in the presence of CTL specific for this melanocyte lineage Ag. These observations may have important implications for Melan-A/MART-1-specific CTL-mediated immunotherapy of melanoma tumors.
A Role of the Mitochondrial Apoptosis-Inducing Factor in Granulysin-Induced Apoptosis
Authors: Pardo Julián , Pérez-Galán Patricia , Gamen Susana , Marzo Isabel , Monleón Inmaculada , Kaspar Allan A. , Susín Santos A. , Kroemer Guido , Krensky Alan M. , Naval Javier , Anel Alberto 
Published: April 2014

AbstractGranulysin is a cytolytic molecule released by CTL via granule-mediated exocytosis. In a previous study we showed that granulysin induced apoptosis using both caspase- and ceramide-dependent and -independent pathways. In the present study we further characterize the biochemical mechanism for granulysin-induced apoptosis of tumor cells. Granulysin-induced death is significantly inhibited by Bcl-2 overexpression and is associated with a rapid (1–5 h) loss of mitochondrial membrane potential, which is not mediated by ceramide generation and is not inhibited by the general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone. Ceramide generation induced by granulysin is a slow event, only observable at longer incubation times (12 h). Apoptosis induced by exogenous natural (C18) ceramide is truly associated with mitochondrial membrane potential loss, but contrary to granulysin, this event is inhibited by benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone. Ceramide-induced apoptosis is also completely prevented by Bcl-2 overexpression. The nuclear morphology of cells dying after granulysin treatment in the presence of caspase inhibitors suggested the involvement of mitochondrial apoptosis-inducing factor (AIF) in granulysin-induced cell death. We demonstrate using confocal microscopy that AIF is translocated from mitochondria to the nucleus during granulysin-induced apoptosis. The majority of Bcl-2 transfectants are protected from granulysin-induced cell death, mitochondrial membrane potential loss, and AIF translocation, while a small percentage are not protected. In this small percentage the typical nuclear apoptotic morphology is delayed, being of the AIF type at 5 h time, while at longer times (12 h) the normal apoptotic morphology is predominant. These and previous results support a key role for the mitochondrial pathway of apoptosis, and especially for AIF, during granulysin-induced tumoral cell death.
A VH12 Transgenic Mouse Exhibits Defects in Pre-B Cell Development and Is Unable to Make IgM+ B Cells
Authors: Wang Hongsheng , Ye Jian , Arnold Larry W. , McCray Suzanne K. , Clarke Stephen H. 
Published: April 2014

AbstractVH12 B cells undergo stringent selection at multiple checkpoints to favor development of B-1 cells that bind phosphatidylcholine. Selection begins with the VH third complementarity-determining region (CDR3) at the pre-B cell stage, in which most VH12 pre-B cells are selectively eliminated, enriching for those with VHCDR3s of 10 aa and a fourth position Gly (designated 10/G4). To understand this selection, we compared B cell differentiation in mice of two VH12 transgenic lines, one with the favored 10/G4 VHCDR3 and one with a non-10/G4 VHCDR3 of 8 aa and no Gly (8/G0). Both H chains drive B cell differentiation to the small pre-BII cell stage, and induce allelic exclusion and L chain gene rearrangement. However, unlike 10/G4 pre-B cells, 8/G0 pre-B cells are deficient in cell division and unable to differentiate to B cells. We suggest that this is due to poor 8/G0 pre-B cell receptor expression and to an inability to form an 8/G0 B cell receptor. Our findings also suggest that VH12 H chains have evolved such that association with surrogate and conventional L chains is most efficient with a 10/G4 CDR3. Thus, selection for phosphatidylcholine-binding B-1 cells is most likely the underlying evolutionary basis for the loss of non-10/G4 pre-B cells.
Positive Signaling Through CD72 Induces Mitogen-Activated Protein Kinase Activation and Synergizes with B Cell Receptor Signals to Induce X-Linked Immunodeficiency B Cell Proliferation
Authors: Wu Hsin-Jung , Venkataraman Chandrasekar , Estus Steven , Dong Chen , Davis Roger J. , Flavell Richard A. , Bondada Subbarao 
Published: April 2014

AbstractCD72 is a 45-kDa B cell transmembrane glycoprotein that has been shown to be important for B cell activation. However, whether CD72 ligation induces B cell activation by delivering positive signals or sequestering negative signals away from B cell receptor (BCR) signals remains unclear. Here, by comparing the late signaling events associated with the mitogen-activated protein kinase pathway, we identified many similarities and some differenes between CD72 and BCR signaling. Thus, CD72 and BCR activated the extracellular signal-regulated kinase (ERK) and the c-Jun N-terminal kinase (JNK) but not p38 mitogen-activated protein kinase. Both CD72- and BCR-mediated ERK and JNK activation required protein kinase C activity, which was equally important for CD72- and BCR-induced B cell proliferation. However, CD72 induced stronger JNK activation compared with BCR. Surprisingly, the JNK activation induced by both BCR and CD72 is Btk independent. Although both CD72 and BCR induced Btk-dependent ERK activation, CD72-mediated proliferation is more resistent to blocking of ERK activity than that of BCR, as shown by the proliferation response of B cells treated with PD98059 and dibutyryl cAMP, agents that inhibit ERK activity. Most importantly, CD72 signaling compensated for defective BCR signaling in X-linked immunodeficiency B cells and partially restored the proliferation response of X-linked immunodeficiency B cells to anti-IgM ligation. These results suggest that CD72 signals B cells by inducing BCR-independent positive signaling pathways.
Multiple Paths for Activation of Naive CD8+ T Cells: CD4-Independent Help
Authors: Wang Bo , Norbury Christopher C. , Greenwood Roberta , Bennink Jack R. , Yewdell Jonathan W. , Frelinger Jeffrey A. 
Published: April 2014

AbstractCD8+ CTLs play a pivotal role in immune responses against many viruses and tumors. Two models have been proposed. The “three-cell” model focuses on the role of CD4+ T cells, proposing that help is only provided to CTLs by CD4+ T cells that recognize Ag on the same APC. The sequential “two-cell” model proposes that CD4+ T cells can first interact with APCs, which in turn activate naive CTLs. Although these models provide a general framework for the role of CD4+ T cells in mediating help for CTLs, a number of issues are unresolved. We have investigated the induction of CTL responses using dendritic cells (DCs) to immunize mice against defined peptide Ags. We find that help is required for activation of naive CTLs when DCs are used as APCs, regardless of the origin or MHC class I restriction of the peptides we studied in this system. However, CD8+ T cells can provide self-help if they are present at a sufficiently high precursor frequency. The important variable is the total number of T cells responding, because class II-knockout DCs pulsed with two noncompeting peptides are effective in priming.
Minimal Requirements for IgE-Mediated Regulation of Surface FcεRI
Authors: Borkowski Teresa A. , Jouvin Marie-Hélène , Lin Shih-Yao , Kinet Jean-Pierre 
Published: April 2014

AbstractThe IgE-FcεRI network plays a central role in allergic inflammation. IgE levels control cell surface levels of FcεRI and, in turn, FcεRI levels modulate the intensity of effector responses. Treatment of allergic patients with anti-IgE Abs has been shown to induce a decrease in FcεRI expression on basophils and a decrease in Ag-triggered histamine release. However, the mechanisms underlying IgE-mediated regulation of FcεRI expression remain unclear. Here, we designed an in vitro model system to establish the minimal cellular requirements for regulation of FcεRI by IgE. Using this system, we demonstrate that transcriptional regulation, hemopoietic-specific factors, and signaling are not required for IgE-mediated increases in FcεRI expression. IgE binding to the α-chain is the minimal requirement for the induction of FcεRI up-regulation. The rate of up-regulation is independent of the baseline level of expression. The mechanism of this up-regulation is the result of a combination of three factors: 1) stabilization of the receptor at the cell surface, which prevents receptor internalization and degradation; 2) use of a preformed pool of receptor comprising recycled and recently synthesized receptors; and 3) continued basal level of protein synthesis. It is possible that in vivo additional factors contribute to modulate the basic regulatory mechanism described here.
An Absolute Requirement for STAT4 and a Role for IFN-γ as an Amplifying Factor in IL-12 Induction of the Functional IL-18 Receptor Complex
Authors: Nakahira Masakiyo , Tomura Michio , Iwasaki Masayuki , Ahn Hyun-Jong , Bian Yang , Hamaoka Toshiyuki , Ohta Tsunetaka , Kurimoto Masashi , Fujiwara Hiromi 
Published: April 2014

AbstractIL-12 and IL-18 are both proinflammatory cytokines that contribute to promoting Th1 development and IFN-γ expression. However, neither IL-12R nor IL-18R is expressed as a functional complex on most resting T cells. This study investigated the molecular mechanisms underlying the induction of an IL-18R complex in T cells. Resting T cells expressed IL-18Rα chains but did not exhibit IL-18 binding sites as detected by incubation with rIL-18 followed by anti-IL-18 Ab, suggesting a lack of IL-18Rβ expression in resting T cells. Although they also failed to express IL-12R, stimulation with anti-CD3 plus anti-CD28 generated IL-12R. Exposure of these cells to IL-12 led not only to up-regulation of IL-18Rα expression but also to induction of IL-18R binding sites on both CD4+ and CD8+ T cells concomitant with IL-18Rβ mRNA expression. The IL-18 binding site represented a functional IL-18R complex capable of exhibiting IL-18 responsiveness. IL-12 induction of an IL-18R complex and IL-18Rβ mRNA expression was not observed in STAT4-deficient (STAT4−/−) T cells and was substantially decreased in IFN-γ−/− T cells. However, the failure of STAT4−/− T cells to induce an IL-18R complex was not corrected by IFN-γ. These results indicate that STAT4 and IFN-γ play an indispensable role and a role as an amplifying factor, respectively, in IL-12 induction of the functional IL-18R complex.
4-1BB Ligand Induces Cell Division, Sustains Survival, and Enhances Effector Function of CD4 and CD8 T Cells with Similar Efficacy
Authors: Cannons Jennifer L. , Lau Peggy , Ghumman Birinder , DeBenedette Mark A. , Yagita Hideo , Okumura Ko , Watts Tania H. 
Published: April 2014

AbstractA costimulatory member of the TNFR family, 4-1BB, is expressed on activated T cells. Although some reports have suggested that 4-1BB is primarily involved in CD8 T cell activation, in this report we demonstrate that both CD4 and CD8 T cells respond to 4-1BB ligand (4-1BBL) with similar efficacy. CD4 and CD8 TCR transgenic T cells up-regulate 4-1BB, OX40, and CD27 and respond to 4-1BBL-mediated costimulation during a primary response to peptide Ag. 4-1BBL enhanced proliferation, cytokine production, and CTL effector function of TCR transgenic T cells. To compare CD4 vs CD8 responses to 4-1BBL under similar conditions of antigenic stimulation, we performed MLRs with purified CD4 or CD8 responders from CD28+/+ and CD28−/− mice. We found that CD8 T cells produced IL-2 and IFN-γ in a 4-1BBL-dependent manner, whereas under the same conditions the CD4 T cells produced IL-2 and IL-4. 4-1BBL promoted survival of CD4 and CD8 T cells, particularly at late stages of the MLR. CD4 and CD8 T cells both responded to anti-CD3 plus s4-1BBL with a similar cytokine profile as observed in the MLR. CD4 and CD8 T cells exhibited enhanced proliferation and earlier cell division when stimulated with anti-CD3 plus anti-CD28 compared with anti-CD3 plus 4-1BBL, and both subsets responded comparably to anti-CD3 plus 4-1BBL. These data support the idea that CD28 plays a primary role in initial T cell expansion, whereas 4-1BB/4-1BBL sustains both CD4 and CD8 T cell responses, as well as enhances cell division and T cell effector function.
A T Cell Clone’s Avidity Is a Function of Its Activation State
Authors: Hesse Maike D. , Karulin Alexey Y. , Boehm Bernhard O. , Lehmann Paul V. , Tary-Lehmann Magdalena 
Published: April 2014

AbstractAt present it is unclear how Ag dose-dependent T cell functions, such as cytokine production, reflect TCR affinity and how the signal strength afforded by the Ag dose affects the kinetics of cytokine production by the individual T cell. We used a computer-assisted ELISPOT approach to address these issues. IFN-γ release by a clonal population of CD4 T cells was monitored on a clonal population of APC while titrating the nominal peptide. The frequency of cytokine-producing cells, the net per-cell output of cytokine, and the onset of cytokine production were each found to be functions of the signal strength. Sigmoidal dose-response curves were seen at the clonal population level, but the activation thresholds for the individual T cells followed a Gaussian distribution. Moreover, the overall dose-response curve of the T cell clone revealed cyclic changes, becoming increasingly shifted toward lower Ag concentrations with the duration of time that elapsed since the last restimulation with Ag. Therefore, responsiveness to Ag (“functional avidity”) is not a constant parameter of a T cell clone but a function of the T cell’s history of last Ag encounter. The implications of such shifting activation thresholds are discussed for autoimmune disease.
H2-O Inhibits Presentation of Bacterial Superantigens, but Not Endogenous Self Antigens
Authors: Qi Ling , Ostrand-Rosenberg Suzanne 
Published: April 2014

AbstractH2-O/HLA-DO are MHC class II accessory molecules that modulate exogenous Ag presentation. Most class II accessory molecules are expressed in all professional APC; however, H2-O is only expressed in B cells and medullary thymic epithelial cells. Because B cells present exogenous Ags and superantigens (SAgs), and medullary thymic epithelial cells are specialized APC for self Ags during negative selection in the thymus, we have hypothesized that H2-O might play a role in MHC class II-restricted SAg and self Ag presentation. In this study, we demonstrate that H2-O expression inhibits presentation of the bacterial SAgs staphylococcal enterotoxins A and B to four SAg-reactive T hybridoma cells. In contrast, H2-O has no effect on presentation of endogenous self Ags, as measured by tumorigenicity in vivo and Ag presentation to three self Ag-specific T hybridoma cells. Additional experiments suggest that H2-O inhibits presentation of exogenous Ags by both newly synthesized and recycling MHC class II molecules. These data suggest H2-O may have a physiological role in tolerance induction and SAg-mediated toxic shock.
Sendai Virus Fusion Protein-Mediates Simultaneous Induction of MHC Class I/II-Dependent Mucosal and Systemic Immune Responses Via the Nasopharyngeal-Associated Lymphoreticular Tissue Immune System
Authors: Kunisawa Jun , Nakanishi Tsuyoshi , Takahashi Ichiro , Okudaira Akiko , Tsutsumi Yasuo , Katayama Kazufumi , Nakagawa Shinsaku , Kiyono Hiroshi , Mayumi Tadanori 
Published: April 2014

AbstractNasal administration of Ags using a novel hybrid Ag delivery vehicle composed of envelope glycoproteins of Sendai virus on the surface of liposome membranes (fusogenic liposome) efficiently delivered Ags to Ag-sampling M cells in nasopharyngeal-associated lymphoreticular tissue. Additionally, fusogenic liposomes also effectively delivered the Ags into epithelial cells and macrophages in nasopharyngeal-associated lymphoreticular tissue and nasal passages. In vitro Ag presentation assays clearly showed that fusogenic liposomes effectively presented encapsulated Ags via the MHC class II-dependent pathway of epithelial cells as well as macrophages. Fusogenic liposomes also have an adjuvant activity against mucosal epithelial cells to enhance MHC class II expression. According to these high delivery and adjuvant activities of fusogenic liposomes, nasal immunization with OVA-encapsulated fusogenic liposomes induced high levels of OVA-specific CD4+ Th1 and Th2 cell responses. Furthermore, Ag-specific CTL responses and Ab productions were also elicited at both mucosal and systemic sites by nasal immunization with Ag-encapsulated fusogenic liposomes. These results indicate that fusogenic liposome is a versatile and effective system for the stimulation of Ag-specific immune responses at both mucosal and systemic compartments.
Dendritic Cells from Nonobese Diabetic Mice Exhibit a Defect in NF-κB Regulation Due to a Hyperactive IκB Kinase
Authors: Weaver Donald J. , Poligone Brian , Bui Thi , Abdel-Motal Ussama M. , Baldwin Albert S. , Tisch Roland 
Published: April 2014

AbstractInsulin-dependent diabetes mellitus (IDDM) is characterized by the T cell-mediated destruction of insulin-producing β cells. Accordingly, APCs, such as macrophage, have also been shown to be important in the disease process. However, the role(s) of dendritic cells (DCs) that exhibit potent APC function remains undefined in IDDM. Here we demonstrate that DCs derived from nonobese diabetic (NOD) mice, a model for IDDM, are more sensitive to various forms of stimulation compared with those from C57BL/6 and BALB/c mice, resulting in increased IL-12 secretion. This property is a consequence of hyperactivation of NF-κB, a transcription factor known to regulate IL-12 gene expression. Specifically, NOD DCs exhibit persistent hyperactivation of both IκB kinase and NF-κB in response to stimuli, in addition to selective degradation of IκBε. Transfection of NOD DCs with a modified form of IκBα significantly reduced IL-12 secretion, suggesting that hyperactivation of NF-κB was in part responsible for increased IL-12 production. An enhanced capacity of NOD DCs to secrete IL-12 would be expected to contribute to the development of pathogenic Th1 (Tc1) cells during the diabetogenic response.
C1 Inhibitor: Analysis of the Role of Amino Acid Residues Within the Reactive Center Loop in Target Protease Recognition
Authors: Zahedi Rana , MacFarlane Ryan C. , Wisnieski Jeffrey J. , Davis Alvin E. 
Published: April 2014

AbstractPrevious analysis of a naturally occurring C1 inhibitor P2 mutant (Ala443→Val) indicated a role for P2 in specificity determination. To define this role and that of other reactive center loop residues, a number of different amino acids were introduced at P2, as well as at P6 (Ala439) and P8′/9′ (Gln452Gln453). Ala439→Val is a naturally occurring mutant observed in a patient with hereditary angioedema. Previous data suggested that Gln452Gln453 might be a contact site for C1s. Reactivity of the inhibitors toward target (C1s, C1r, kallikrein, β factor XIIa, and plasmin) and nontarget proteases (α-thrombin and trypsin) were studied. Substitution of P2 with bulky or charged residues resulted in decreased reactivity with all target proteases. Substitution with residues with hydrophobic or polar side chains resulted in decreased reactivity with some proteases, but in unaltered or increased reactivity with others. Second order rate constants for the reaction with C1s were determined for the mutants with activities most similar to the wild-type protein. The three P2 mutants showed reductions in rate from 3.35 × 105 M−1s−1 for the wild type to 1.61, 1.29, and 0.63 × 105 for the Ser, Thr, and Val mutants, respectively. In contrast, the Ala439→Val and the Gln452Gln453→Ala mutants showed little difference in association rates with C1s, in comparison with the wild-type inhibitor. The data confirm the importance of P2 in specificity determination. However, the P6 position appears to be of little, if any, importance. Furthermore, it appears unlikely that Gln452Gln453 comprise a portion of a protease contact site within the inhibitor.