bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of Macrophage CD8: Pharmacological Studies of TNF and IL-1β Production
Authors: Lin Tong-Jun , Hirji Nadir , Stenton Grant R. , Gilchrist Mark , Grill Brock J. , Schreiber Alan D. , Befus A. Dean 
Published: April 2014

Abstract
Previously, we demonstrated that rat macrophages express CD8 and that Ab to CD8 stimulates NO production. We confirm that CD8 is expressed by rat macrophages and extend understanding of its functional significance. Activation of CD8α (OX8 Ab) on alveolar macrophages stimulated mRNA expression for TNF and IL-1β and promoted TNF and IL-1β secretion. Similarly, OX8 Ab (CD8α) stimulated NR8383 cells to secrete TNF, IL-1β, and NO. Activation of CD8β (Ab 341) on alveolar macrophages increased mRNA expression for TNF and IL-1β and stimulated secretion of TNF, but not IL-1β. Interestingly, anti-CD8 Abs did not stimulate IFN-γ or PGE2 production, or phagocytosis by macrophages. OX8 (CD8α)-induced TNF and IL-1β production by macrophages was blocked by inhibitors of protein tyrosine kinase(s), PP1, and genistein, but not by phosphatidylinositol-3 kinase inhibitor, wortmannin. Moreover, OX8 stimulated protein tyrosine kinase activity in NR8383 cells. Further analysis of kinase dependence using antisense to Syk kinase demonstrated that TNF, but not IL-1β, stimulation by CD8α is Syk dependent. By contrast, protein kinase C inhibitor Ro 31-8220 had no effect on OX8-induced TNF production, whereas OX8-induced IL-1β production was blocked by Ro 31-8220. Thus, there are distinct signaling mechanisms involved in CD8α (OX8)-induced TNF and IL-1β production. In summary, macrophages express CD8 molecules that, when activated, stimulate TNF and IL-1β expression, probably through mechanisms that include activation of Src and Syk kinases and protein kinase C. These findings identify a previously unknown pathway of macrophage activation likely to be involved in host defense and inflammation.
IFN-γ Activates the C3G/Rap1 Signaling Pathway
Authors: Alsayed Yazan , Uddin Shahab , Ahmad Sarfraz , Majchrzak Beata , Druker Brian J. , Fish Eleanor N. , Platanias Leonidas C. 
Published: April 2014

Abstract
IFN-γ transduces signals by activating the IFN-γ receptor-associated Jak-1 and Jak-2 kinases and by inducing tyrosine phosphorylation and activation of the Stat-1 transcriptional activator. We report that IFN-γ activates a distinct signaling cascade involving the c-cbl protooncogene product, CrkL adapter, and small G protein Rap1. During treatment of NB-4 human cells with IFN-γ, c-cbl protooncogene product is rapidly phosphorylated on tyrosine and provides a docking site for the src homology 2 domain of CrkL, which also undergoes IFN-γ-dependent tyrosine phosphorylation. CrkL then regulates activation of the guanine exchange factor C3G, with which it interacts constitutively via its N terminus src homology 3 domain. This results in the IFN-γ-dependent activation of Rap1, a protein known to exhibit tumor suppressor activity and mediate growth inhibitory responses. In a similar manner, Rap1 is also activated in response to treatment of cells with type I IFNs (IFN-α, IFN-β), which also engage CrkL in their signaling pathways. On the other hand, IFN-γ does not induce formation of nuclear CrkL-Stat5 DNA-binding complexes, which are induced by IFN-α and IFN-β, indicating that pathways downstream of CrkL are differentially regulated by different IFN subtypes. Taken altogether, our data demonstrate that, in addition to activating the Stat pathway, IFN-γ activates a distinct signaling cascade that may play an important role in the generation of its growth inhibitory effects on target cells.
Cloning and Characterization of IL-10-Related T Cell-Derived Inducible Factor (IL-TIF), a Novel Cytokine Structurally Related to IL-10 and Inducible by IL-9
Authors: Dumoutier Laure , Louahed Jamila , Renauld Jean-Christophe 
Published: April 2014

Abstract
IL-9 is a Th2 cytokine active on various cell types such as T and B lymphocytes, mast cells, and eosinophils, and potentially involved in allergy and asthma. To understand better the molecular mechanisms underlying the activity of this cytokine, we used a cDNA subtraction method to identify genes specifically induced by IL-9 in mouse T cells. One of the IL-9-regulated genes isolated by this approach turned out to encode a 180-amino acid long protein, including a potential signal peptide, and showing 22% amino acid identity with IL-10. This protein, designated IL-10-related T cell-derived inducible factor (IL-TIF), is induced by IL-9 in thymic lymphomas, T cells, and mast cells, and by lectins in freshly isolated splenocytes. Experiments concerning the mechanism regulating IL-TIF expression in T cells indicate that IL-9 induction is rapid (within 1 h), does not require protein synthesis, and depends on the activation of the Janus kinase (JAK)-STAT pathway. In vivo, constitutive expression of IL-TIF was detected by RT-PCR in thymus and brain, suggesting that the role of this new factor is not restricted to the immune system. Transfection of HEK293 cells with the IL-TIF cDNA resulted in the production of a glycosylated protein of about 25 kDa that was found to induce STAT activation in mesangial and neuronal cell lines. Further studies will have to address the possibility that some of the IL-9 activities may be mediated by IL-TIF.
Regulator of G Protein Signaling 1 (RGS1) Markedly Impairs Giα Signaling Responses of B Lymphocytes
Authors: Moratz Chantal , Kang Veronica H. , Druey Kirk M. , Shi Chong-Shan , Scheschonka Astrid , Murphy Philip M. , Kozasa Tohru , Kehrl John H. 
Published: April 2014

Abstract
Regulator of G protein signaling (RGS) proteins modulate signaling through pathways that use heterotrimeric G proteins as transducing elements. RGS1 is expressed at high levels in certain B cell lines and can be induced in normal B cells by treatment with TNF-α. To determine the signaling pathways that RGS1 may regulate, we examined the specificity of RGS1 for various Gα subunits and assessed its effect on chemokine signaling. G protein binding and GTPase assays revealed that RGS1 is a Giα and Gqα GTPase-activating protein and a potential G12α effector antagonist. Functional studies demonstrated that RGS1 impairs platelet activating factor-mediated increases in intracellular Ca+2, stromal-derived factor-1-induced cell migration, and the induction of downstream signaling by a constitutively active form of G12α. Furthermore, germinal center B lymphocytes, which are refractory to stromal-derived factor-1-triggered migration, express high levels of RGS1. These results indicate that RGS proteins can profoundly effect the directed migration of lymphoid cells.
Membrane Cofactor Protein (MCP; CD46): Isoform-Specific Tyrosine Phosphorylation
Authors: Wang Guixian , Liszewski M. Kathryn , Chan Andrew C. , Atkinson John P. 
Published: April 2014

Abstract
Membrane cofactor protein (MCP; CD46) is a widely expressed type 1 transmembrane glycoprotein that inhibits complement activation on host cells. It also is a receptor for several pathogens including measles virus, Streptococcus pyogenes, Neisseria gonorrhea, and Neisseria meningitidis. That MCP may have signaling capability was suggested by its microbial interactions. That is, binding of MCP on human monocytes by measles virus hemagglutinin or cross-linking by an anti-MCP Ab resulted in IL-12 down-regulation, while binding to MCP by Neisseria on epithelial cells produced a calcium flux. Through alternative splicing, MCP is expressed on most cells with two distinct cytoplasmic tails of 16 (CYT-1) or 23 (CYT-2) amino acids. These play pivotal roles in intracellular precursor processing and basolateral localization. We investigated the putative signal transduction pathway mediated by MCP and demonstrate that CYT-2, but not CYT-1, is phosphorylated on tyrosine. We examined MCP tail peptides and performed Ab cross-linking experiments on several human cell lines and MCP isoform transfectants. We found an MCP peptide of CYT-2 was phosphorylated by a src kinase system. Western blots of the cells lines demonstrated that cells bearing CYT-2 were also phosphorylated on tyrosine. Additionally, we provide genetic and biochemical evidence that the src family of kinases is responsible for the latter phosphorylation events. In particular, the src kinase, Lck, is required for phosphorylation of MCP in the Jurkat T cell line. Taken together, these studies suggest a src family-dependent pathway for signaling through MCP.
Single-Cytokine-Producing CD4 Memory Cells Predominate in Type 1 and Type 2 Immunity
Authors: Karulin Alexey Y. , Hesse Maike D. , Tary-Lehmann Magdalena , Lehmann Paul V. 
Published: April 2014

Abstract
The patterns of Ag-induced cytokine coexpression in normal, in vivo-primed CD4 memory T cells has remained controversial because the low frequency at which these cells occur has effectively prevented direct ex vivo measurements. We have overcome this limitation by using two-color cytokine enzyme-linked immunospot assays and computer-assisted image analysis. We found CD4 memory cells that simultaneously expressed IL-2, IL-3, IL-4, IL-5, and IFN-γ to be rare (0–10%). This cytokine segregation was seen in adjuvant-induced type 1, type 2, and mixed immunity to OVA, in Leishmania infection regardless of the Ag dose used or how long after immunization the assay was performed. The data suggest that type 1 and type 2 immunity in vivo is not mediated by classic Th1 or Th2 cells but by single-cytokine-producing memory cells.
Transgenic Expression of Cyclin D1 in Thymic Epithelial Precursors Promotes Epithelial and T Cell Development
Authors: Klug David B. , Crouch Elizabeth , Carter Carla , Coghlan Lezlee , Conti Claudio J. , Richie Ellen R. 
Published: April 2014

Abstract
We previously reported that precursors within the keratin (K) 8+5+ thymic epithelial cell (TEC) subset generate the major cortical K8+5− TEC population in a process dependent on T lineage commitment. This report demonstrates that expression of a cyclin D1 transgene in K8+5+ TECs expands this subset and promotes TEC and thymocyte development. Cyclin D1 transgene expression is not sufficient to induce TEC differentiation in the absence of T lineage-committed thymocytes because TECs from both hCD3ε transgenic and hCD3ε/cyclin D1 double transgenic mice remain blocked at the K8+5+ maturation stage. However, enforced cyclin D1 expression does expand the developmental window during which K8+5+ cells can differentiate in response to normal hemopoietic precursors. Thus, enhancement of thymic function may be achieved by manipulating the growth and/or survival of TEC precursors within the K8+5+ subset.
Heavy Chain Diversity Region Segments of the Channel Catfish: Structure, Organization, Expression and Phylogenetic Implications
Authors: Hayman J. Russell , Lobb Craig J. 
Published: April 2014

Abstract
Circular DNA, derived from lymphocytes of juvenile channel catfish, was used to construct λ libraries that were screened to identify the products of immunoglobulin DH-JH excision events. Clones were characterized that contained DH to JH recombination signal joints. The signal joints represented 23-bp recombination signal sequences (RSS) identical to germline JH segments that were adjacent to DH 12-bp RSS elements. DH flanking regions within the clones were used to probe a genomic library. Three germline DH gene segments containing 11–19 bp coding regions flanked by 12-bp RSS elements with conserved heptamers and nonamers were identified. The DH locus is closely linked to the JH locus, and Southern blots indicate that the DH segments represent different single member gene families. Analysis of H chain cDNA shows that each germline DH segment was expressed in functional VDJ recombination events involving different JH segments and members of different VH families. Several aspects of CDR3 junctional diversity were evident, including deletion of coding region nucleotides, N- and P-region nucleotide additions, alternate DH reading frame utilization, and point mutations. Coding region motifs of catfish DH segments are phylogenetically conserved in some DH segments of higher vertebrates. These studies indicate that the structure, genomic organization, and recombination patterns of DH segments typically associated with higher vertebrates evolved early in vertebrate phylogeny at the level of the bony fish.
The Nucleotide-Replacement Spectrum Under Somatic Hypermutation Exhibits Microsequence Dependence That Is Strand-Symmetric and Distinct from That Under Germline Mutation
Authors: Cowell Lindsay G. , Kepler Thomas B. 
Published: April 2014

AbstractSomatic mutation is a fundamental component of acquired immunity. Although its molecular basis remains undetermined, the sequence specificity with which mutations are introduced has provided clues to the mechanism. We have analyzed data representing over 1700 unselected mutations in V gene introns and nonproductively rearranged V genes to identify the sequence specificity of the mutation spectrum—the distribution of resultant nucleotides. In other words, we sought to determine what effects the neighboring bases have on what a given base mutates “to.” We find that both neighboring bases have a significant effect on the mutation spectrum. Their influences are complicated, but much of the effect can be characterized as enhancing homogeneity of the mutated DNA sequence. In contrast to what has been reported for the sequence specificity of the “targeting” mechanism, that of the spectrum is notably symmetric under complementation, indicating little if any strand bias. We compared the spectrum to that found previously for germline mutations as revealed by analyzing pseudogene sequences. We find that the influences of nearest neighbors are quite different in the two datasets. Altogether, our findings suggest that the mechanism of somatic hypermutation is complex, involving two or more stages: introduction of mis-pairs and their subsequent resolution, each with distinct sequence specificity and strand bias.
Intestinal Intraepithelial Lymphocytes Exert Potent Protective Cytotoxic Activity During an Acute Virus Infection
Authors: Müller Stefan , Bühler-Jungo Myriam , Mueller Christoph 
Published: April 2014

AbstractAfter systemic infection of mice with 104 PFU of lymphocytic choriomeningitis virus (LCMV), infected cells are detected simultaneously in various organs, including spleen and intestinal mucosa. Most notably, virus-infected cells are also present among CD11c+ dendritic cells in the subepithelial area of the small intestinal mucosa. Some of these virus-infected cells are in close spatial association with intestinal intraepithelial lymphocytes (IEL). Therefore, we compared virus-specific cytotoxic activity of CD8 splenocytes with that of IEL subsets. While ex vivo isolated TCRαβ+CD8αα+ IEL exert only minimal virus-specific cytotoxicity, maximum specific killing mediated by TCRαβ+CD8αβ+ IEL on day 8 postinfection exceeds maximum cytotoxic activity observed with CD8 splenocytes when assessed in vitro. Maximum cytotoxic activity of IEL is preceded by peak perforin and granzyme B mRNA expression in IEL around day 6 postinfection, suggesting a recent activation in situ. The antivirus cytotoxicity of in vivo primed IEL is further demonstrated by the protection from virus production in the spleen of mice infected with LCMV 10 h before adoptive cell transfer. These data indicate a potent priming of LCMV-specific IEL in situ after systemic LCMV infection and suggest that cytotoxic IEL markedly contribute to the elimination of virus-infected cells in the intestinal mucosa.
Selection of Babesia bovis-Infected Erythrocytes for Adhesion to Endothelial Cells Coselects for Altered Variant Erythrocyte Surface Antigen Isoforms
Authors: O’Connor Roberta M. , Allred David R. 
Published: April 2014

Abstract
Sequestration of Babesia bovis-infected erythrocytes (IRBCs) in the host microvasculature is thought to constitute an important mechanism of immune evasion. Since Ig is considered to be important for protection from disease, an in vitro assay of B. bovis sequestration was used to explore the ability of anti-B. bovis Ig to interfere with IRBC cytoadhesion, and to identify IRBC surface Ags acting as endothelial cell receptors. Bovine infection sera reactive with the IRBC surface inhibited and even reversed the binding of IRBCs to bovine brain capillary endothelial cells (BBECs). This activity is at least partially attributable to serum IgG. IgG isolated from inhibitory serum captured the variant erythrocyte surface ag 1 (VESA1) in surface-specific immunoprecipitations of B. bovis-IRBCs. Selection for the cytoadhesive phenotype concurrently selected for antigenic and structural changes in the VESA1 Ag. In addition, the anti-VESA1 mAb, 4D9.1G1, proved capable of effectively inhibiting and reversing binding of adhesive, mAb-reactive parasites to BBECs, and by immunoelectron microscopy localized VESA1 to the external tips of the IRBC membrane knobs. These data are consistent with a link between antigenic variation and cytoadherence in B. bovis and suggest that the VESA1 Ag acts as an endothelial cell ligand on the B. bovis-IRBC.
Ras, Protein Kinase Cζ, and IκB Kinases 1 and 2 Are Downstream Effectors of CD44 During the Activation of NF-κB by Hyaluronic Acid Fragments in T-24 Carcinoma Cells
Authors: Fitzgerald Katherine A. , Bowie Andrew G. , Skeffington Barbara Sheehy , O’Neill Luke A. J. 
Published: April 2014

Abstract
We have investigated the ability of hyaluronic acid (HA) fragments to activate the transcription factor NF-κB. HA fragments activated NF-κB in the cell lines T-24, HeLa, MCF7, and J774. Further studies in T-24 cells demonstrated that HA fragments also induced IκBα phosphorylation and degradation, κB-linked reporter gene expression, and ICAM-1 promoter activity in an NF-κB-dependent manner. The effect of HA was size dependent as neither disaccharide nor native HA were active. CD44, the principal cellular receptor for HA, was critical for the response because the anti-CD44 Ab IM7.8.1 blocked the effect on NF-κB. HA fragments activated the IκB kinase complex, and the effect on a κB-linked reporter gene was blocked in T-24 cells expressing dominant negative IκB kinases 1 or 2. Activation of protein kinase C (PKC) was required because calphostin C inhibited NF-κB activation and IκBα phosphorylation. In particular, PKCζ was required because transfection of cells with dominant negative PKCζ blocked the effect of HA fragments on κB-linked gene expression and HA fragments increased PKCζ activity. Furthermore, damnacanthal and manumycin A, two mechanistically distinct inhibitors of Ras, blocked NF-κB activation. Transfection of T-24 cells with dominant negative Ras (RasN17) blocked HA fragment-induced κB-linked reporter gene expression, and HA fragments activated Ras activity within 5 min. Taken together, these studies establish a novel signal transduction cascade eminating from CD44 to Ras, PKCζ, and IκB kinase 1 and 2.
Human Toll-Like Receptor 2 Mediates Monocyte Activation byListeria monocytogenes, But Not by Group B Streptococci or Lipopolysaccharide
Authors: Flo Trude H. , Halaas Øyvind , Lien Egil , Ryan Liv , Teti Giuseppe , Golenbock Douglas T. , Sundan Anders , Espevik Terje 
Published: April 2014

AbstractHuman Toll like receptor (TLR) 2 has been implicated as a signaling receptor for LPS from Gram-negative bacteria and cell wall components from Gram-positive organisms. In this study, we investigated whether TLR2 can signal cell activation by the heat-killed group B streptococci type III (GBS) and Listeria monocytogenes (HKLM). HKLM, but not GBS, showed a time- and dose-dependent activation of Chinese hamster ovary cells transfected with human TLR2, as measured by translocation of NF-κB and induction of IL-6 production. A mAb recognizing a TLR2-associated epitope (TL2.1) was generated that inhibited IL-6 production from Chinese hamster ovary-TLR2 cells stimulated with HKLM or LPS. The TL2.1 mAb reduced HKLM-induced TNF production from human monocytes by 60%, whereas a CD14 mAb (3C10) reduced the TNF production by 30%. However, coadministrating TL2.1 and 3C10 inhibited the TNF response by 80%. In contrast to this, anti-CD14 blocked LPS-induced TNF production from monocytes, whereas anti-TLR2 showed no inhibition. Neither TL2.1 nor 3C10 affected GBS-induced TNF production. These results show that TLR2 can function as a signaling receptor for HKLM, possibly together with CD14, but that TLR2 is unlikely to be involved in cell activation by GBS. Furthermore, although LPS can activate transfected cell lines through TLR2, this receptor does not seem to be the main transducer of LPS activation of human monocytes. Thus, our data demonstrate the ability of TLR2 to distinguish between different pathogens.
Administration of IgG Fc Fragments Prevents Glomerular Injury in Experimental Immune Complex Nephritis
Authors: Gómez-Guerrero Carmen , Duque Natalia , Casado María Teresa , Pastor Carlos , Blanco Julia , Mampaso Francisco , Vivanco Fernando , Egido Jesús 
Published: April 2014

Abstract
Most human nephritis is due to glomerular deposition and/or formation of immune complexes (IC). In cultured mesangial cells, Fc receptor stimulation induces proliferation, matrix synthesis, and release of several mediators implicated in the initiation and progression of glomerular injury. Since Ig Fc fragments in vitro modified these phenomena, we studied the effects of systemic administration of IgG Fc fragments on the evolution of experimental IC nephritis. Fc fragment injection (1 mg/day i.p.) to rats with ongoing nephritis (proteinuria 20–50 mg/24 h vs 9 ± 0.2 mg/24 h in controls) markedly ameliorates proteinuria, renal function, and morphological renal lesions. This was accompanied by a reduction in the renal synthesis of chemokines (monocyte chemoattractant protein-1, IFN-inducible protein-10, and cytokine-induced neutrophil chemoattractant-1), matrix proteins, and growth factors (platelet-derived growth factor, and TGF-β), and in the activity of transcription factors. The treatment did not affect the glomerular deposition of IgG IC and complement C1q. In contrast, a decrease in the renal expression and production of C3 was observed without changes in serum complement levels. In vitro, very low complement consumption and no C3b covalent interaction were observed with Fc fragments, confirming that they did not modify systemic complement activity. These results indicate that the administration of Fc fragments prevents the development of glomerular damage in an aggressive model of proliferative glomerulonephritis through mechanisms involving a reduced local generation of complement, chemokines and growth factors. Modulation of IC-mesangial cell interaction by Fc fragment administration could represent a new approach to the treatment of severe immune nephritis.