bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resistance to CD4+CD25+ Regulatory T Cells and TGF-β in Cbl-b−/− Mice
Authors: Wohlfert Elizabeth A. , Callahan Margaret K. , Clark Robert B. 
Published: April 2014

Abstract
Cbl-b−/− mice have signaling defects that result in CD28-independent T cell activation, increased IL-2 production, hyper-reactive T cells, and increased autoimmunity. Although the increased autoimmunity in these mice is believed to result from the hyper-reactive T cells, the mechanisms leading from T cell hyper-reactivity to autoimmunity remain unclear. Specifically, the function and interaction of CD4+CD25+ regulatory T cells (Treg) and CD4+CD25− effector T cells (Teff) in Cbl-b−/− mice have not been examined. We now report that Cbl-b−/− CD4+CD25+ Treg exhibit normal regulatory function in vitro. In contrast, the in vitro response of Cbl-b−/− CD4+CD25− Teff is abnormal, in that it is not inhibited by either Cbl-b−/− or wild-type Treg. This resistance of Cbl-b−/− Teff to in vitro regulation is seen at the levels of both DNA synthesis and cell division. In addition to this resistance to CD4+CD25+ Treg, Cbl-b−/− Teff demonstrate in vitro resistance to inhibition by TGF-β. This second form of resistance in Cbl-b−/− Teff is seen despite the expression of normal levels of type II TGF-β receptors and normal levels of phosphorylated Smad3 after TGF-β stimulation. Coupled with recent reports of resistance to Treg in Teff exposed to LPS-treated dendritic cells, our present findings suggest that resistance to regulation may be a relevant mechanism in both normal immune function and autoimmunity.
TNF Activates Syk Protein Tyrosine Kinase Leading to TNF-Induced MAPK Activation, NF-κB Activation, and Apoptosis
Authors: Takada Yasunari , Aggarwal Bharat B. 
Published: April 2014

Abstract
Spleen tyrosine kinase (Syk), a nonreceptor protein kinase initially found to be expressed only in hemopoietic cells, has now been shown to be expressed in nonhemopoietic cells and to mediate signaling of various cytokines. Whether Syk plays any role in TNF signaling was investigated. Treatment of Jurkat T cells with TNF activated Syk kinase but not ZAP70, another member of Syk kinase family, and the optimum activation occurred at 10 s and with 1 nM TNF. TNF also activated Syk in myeloid and epithelial cells. TNF-induced Syk activation was abolished by piceatannol (Syk-selective inhibitor), which led to the suppression of TNF-induced activation of c- JNK, p38 MAPK, and p44/p42 MAPK. Jurkat cells that did not express Syk (JCaM1, JCaM1/lck) showed lack of TNF-induced Syk, JNK, p38 MAPK, and p44/p42 MAPK activation, as well as TNF-induced IκBα phosphorylation, IκBα degradation, and NF-κB activation. TNF-induced NF-κB activation was enhanced by overexpression of Syk by Syk-cDNA and suppressed when Syk expression was down-regulated by expression of Syk-small interfering RNA (siRNA-Syk). The apoptotic effects of TNF were reduced by up-regulation of NF-κB by Syk-cDNA, and enhanced by down-regulation of NF-κB by siRNA-Syk. Immunoprecipitation of cells with Syk Abs showed TNF-dependent association of Syk with both TNFR1 and TNFR2; this association was enhanced by up-regulation of Syk expression with Syk-cDNA and suppressed by down-regulation of Syk using siRNA-Syk. Overall, our results demonstrate that Syk activation plays an essential role in TNF-induced activation of JNK, p38 MAPK, p44/p42 MAPK, NF-κB, and apoptosis.
Two Human ULBP/RAET1 Molecules with Transmembrane Regions Are Ligands for NKG2D
Authors: Bacon Louise , Eagle Robert A. , Meyer Martina , Easom Nicholas , Young Neil T. , Trowsdale John 
Published: April 2014

Abstract
We characterized two novel members of the RAET1/ULBP gene cluster, RAET1E and RAET1G. The encoded proteins were similar to the ULBP in their class I-like α1 and α2 domains, but differed in that, instead of being GPI-anchored, their sequences were type 1 membrane-spanning molecules. Both proteins were capable of being expressed at the cell surface. Both proteins bound the activating receptor NKG2D, and RAET1G bound the human CMV protein UL16. The expression of diverse NKG2D-binding molecules in different tissues and with different properties is consistent with multiple modes of infection- or stress-induced activation.
Dissection of the HLA-DR4 Peptide Repertoire in Endocrine Epithelial Cells: Strong Influence of Invariant Chain and HLA-DM Expression on the Nature of Ligands
Authors: Muntasell Aura , Carrascal Montserrat , Alvarez Iñaki , Serradell Laurence , van Veelen Peter , Verreck Frank A. W. , Koning Frits , Abian Joaquín , Jaraquemada Dolores 
Published: April 2014

Abstract
Class II MHC (MHC II) expression is restricted to professional APCs and thymic epithelium but it also occurs in the epithelial cells of autoimmune organs which are the unique targets of the CD4 autoreactive T cells in endocrine autoimmune diseases. This specificity is presumably conditioned by an epithelium-specific peptide repertoire associated to MHC II at the cell surface. MHC II expression and function is dependent on the action of two main chaperones, invariant chain (Ii) and DM, whose expression is coregulated with MHC II. However, there is limited information about the in vivo expression levels of these molecules and uncoordinated expression has been demonstrated in class II-positive epithelial cells that may influence the MHC-associated peptide repertoires and the outcome of the autoimmune response. We have examined the pool of peptides associated to DR4 molecules expressed by a neuroendocrine epithelial cell and the consequences of Ii and DM coexpression. The RINm5F rat insulinoma cell line was transfected with HLA-DRB1*0401, Ii, and DM molecules in four different combinations: RIN-DR4, -DR4Ii, -DR4DM, and -DR4IiDM. The analysis of the peptide repertoire and the identification of the DR4 naturally processed ligands in each transfected cell were achieved by mass spectrometry. The results demonstrate that 1) the expression of Ii and DM affected the DR4 peptide repertoires by producing important variations in their content and in the origin of peptides; 2) these restrictions affected the stability and sequence of the peptides of each repertoire; and 3) Ii and DM had both independent and coordinate effects on these repertoires.
Analysis of Transcription Factor Expression during Discrete Stages of Postnatal Thymocyte Differentiation
Authors: Tabrizifard Sahba , Olaru Alexandru , Plotkin Jason , Fallahi-Sichani Mohammad , Livak Ferenc , Petrie Howard T. 
Published: April 2014

Abstract
Postnatal T lymphocyte differentiation in the thymus is a multistage process involving serial waves of lineage specification, proliferative expansion, and survival/cell death decisions. Although these are believed to originate from signals derived from various thymic stromal cells, the ultimate consequence of these signals is to induce the transcriptional changes that are definitive of each step. To help to characterize this process, high density microarrays were used to analyze transcription factor gene expression in RNA derived from progenitors at each stage of T lymphopoietic differentiation, and the results were validated by a number of appropriate methods. We find a large number of transcription factors to be expressed in developing T lymphocytes, including many with known roles in the control of differentiation, proliferation, or cell survival/death decisions in other cell types. Some of these are expressed throughout the developmental process, whereas others change substantially at specific developmental transitions. The latter are particularly interesting, because stage-specific changes make it increasingly likely that the corresponding transcription factors may be involved in stage-specific processes. Overall, the data presented here represent a large resource for gene discovery and for confirmation of results obtained through other methods.
STAT1 Regulates Lipopolysaccharide- and TNF-α-Dependent Expression of Transporter Associated with Antigen Processing 1 and Low Molecular Mass Polypeptide 2 Genes in Macrophages by Distinct Mechanisms
Authors: Marqués Laura , Brucet Marina , Lloberas Jorge , Celada Antonio 
Published: April 2014

Abstract
Transporter associated with Ag processing 1 and low molecular mass polypeptide 2 (LMP2) are essential for class I MHC function and share a common bidirectional promoter. In murine bone marrow-derived macrophages, LPS and TNF-α induced Tap1 and up-regulated Lmp2, which is constitutively expressed at low levels. These two genes are induced by LPS and TNF-α with distinct kinetics, at 6 and 12–24 h, respectively. Using macrophages derived from the TNF-α receptors of knockout mice, we found that induction by LPS is not due to the autocrine production of TNF-α. In macrophages from STAT-1 knockout mice, neither LPS nor TNF-α induced the expression of Tap1 or Lmp2. The shared promoter contains several areas that can be controlled by STAT-1, such as the proximal and distal IFN-γ activation site (GAS) boxes in the direction of the Tap1 gene. By making deletions of the promoter, we determined that only the proximal GAS box is required for LPS induction of Tap1 and Lmp2. In contrast, TNF-α induction of these two genes is dependent on the IFN regulatory factor-1 and NF-κB boxes, and not on the GAS box. Our experiments using gel shift analysis and Abs indicated that STAT1 binds to the GAS box in nuclear extracts from LPS-treated macrophages. The nuclear extracts obtained from macrophages treated with TNF-α bound to the IFN regulatory factor-1 and NF-κB boxes. These results show that LPS and TNF-α regulate the induction of Tap1 and Lmp2 through STAT1, but use distinct areas of the promoter.
The E2F-1 Transcription Factor Promotes Caspase-8 and Bid Expression, and Enhances Fas Signaling in T Cells
Authors: Cao Qingyu , Xia Ying , Azadniv Mitra , Crispe I. Nicholas 
Published: April 2014

Abstract
The immune system depends on the extensive proliferation of rare Ag-specific precursor T lymphocytes, followed by their differentiation, the delivery of effector function, and finally death by apoptosis. T cells that lack the E2F-1 transcription factor, which is activated as cells pass the restriction point and enter S phase, show defects in activation-induced cell death. We now report that E2F-1 increases the activity of an apoptotic pathway that is important in murine primary T cells. Thus, E2F-1 promotes the transcription of Bid, a molecule that links death receptor signaling to the activation of apoptotic mechanisms in mitochondria. It also promotes the transcription of caspase-8, the enzyme that cleaves and activates Bid. Enforced expression of Bid can partially restore apoptosis in E2F-1-deficient T cells. Thus, E2F-1 integrates cell cycle progression with apoptosis.
A Short Consensus Repeat-Containing Complement Regulatory Protein of Lamprey That Participates in Cleavage of Lamprey Complement 3
Authors: Kimura Yuko , Inoue Naokazu , Fukui Aya , Oshiumi Hiroyuki , Matsumoto Misako , Nonaka Mayumi , Kuratani Shigeru , Fujita Teizo , Nonaka Masaru , Seya Tsukasa 
Published: April 2014

Abstract
The prototype of the short consensus repeat (SCR)-containing C regulatory protein is of interest in view of its evolutionary significance with regard to the origin of the C regulatory system. Lamprey is an agnathan fish that belongs to the lowest class of vertebrates. Because it does not possess lymphocytes, it lacks Ig and consequently the classical C pathway. We identified an SCR-containing C regulatory protein from the lamprey. The primary structure predicted from the cDNA sequence showed that this is a secretary protein consisting of eight SCRs. This framework is similar to the α-chain of C4b-binding protein (C4bp). SCR2 and -3 of human C4bp are essential for C4b inactivation, and this region is fairly well conserved in the lamprey protein. However, the other SCRs of this protein are similar to those of other human C regulatory proteins. The lamprey protein binds to the previously reported lamprey C3b/C3bi deposited on yeast and cleaves lamprey C3b-like C3 together with a putative serum protease. The scheme resembles the C regulatory system of mammals, where factor I and its cofactor inactivate C3b. Unlike human cofactors, the lamprey protein requires divalent cations for C3b-like C3 cleavage. Its artificial membrane-anchored form protects host cells from lamprey C attack via the lectin pathway. Thus, the target of this protein appears to be C3b and/or its family. We named this protein Lacrep, the lamprey C regulatory protein. Lacrep is a member of SCR-containing C regulators, the first of its kind identified in the lowest vertebrates.
Unprecedented Multiplicity of Ig Transmembrane and Secretory mRNA Forms in the Cartilaginous Fish
Authors: Rumfelt Lynn L. , Diaz Marilyn , Lohr Rebecca L. , Mochon Evonne , Flajnik Martin F. 
Published: April 2014

Abstract
In most jawed vertebrates including cartilaginous fish, membrane-bound IgM is expressed as a five Ig superfamily (Igsf)-domain H chain attached to a transmembrane (Tm) region. Heretofore, bony fish IgM was the one exception with IgM mRNA spliced to produce a four-domain Tm H chain. We now demonstrate that the Tm and secretory (Sec) mRNAs of the novel cartilaginous fish Ig isotypes, IgW and IgNAR, are present in multiple forms, most likely generated by alternative splicing. In the nurse shark, Ginglymostoma cirratum, and horn shark, Heterodontus francisci, alternative splicing of Tm exons to the second or the fourth constant (CH) exons produces two distinct IgW Tm cDNAs. Although the seven-domain IgW Sec cDNA form contains a canonical secretory tail shared with IgM, IgNAR, and IgA, we report a three-domain cDNA form of shark IgW (IgWshort) having an unusual Sec tail, which is orthologous to skate IgXshort cDNA. The IgW and IgWshort Sec transcripts are restricted in their tissue distribution and expression levels vary among individual sharks, with all forms expressed early in ontogeny. IgNAR mRNA is alternatively spliced to produce a truncated four-domain Tm cDNA and a second Tm cDNA is expressed identical in Igsf domains as the Sec form. PBL is enriched in the Tm cDNA of these Igs. These molecular data suggest that cartilaginous fish have augmented their humoral immune repertoire by diversifying the sizes of their Ig isotypes. Furthermore, these Tm cDNAs are prototypical and the truncated variants may translate as more stable protein at the cell surface.
Peptide Variants of Viral CTL Epitopes Mediate Positive Selection and Emigration of Ag-Specific Thymocytes In Vivo
Authors: Fridkis-Hareli Masha , Reche Pedro A. , Reinherz Ellis L. 
Published: April 2014

Abstract
During development, thymocytes carrying TCRs mediating low-affinity interactions with MHC-bound self-peptides are positively selected for export into the mature peripheral T lymphocyte pool. Thus, exogenous administration of certain altered peptide ligands (APL) with reduced TCR affinity relative to cognate Ags may provide a tool to elicit maturation of desired TCR specificities. To test this “thymic vaccination” concept, we designed APL of the viral CTL epitopes gp33–41 and vesicular stomatitis virus nucleoprotein octapeptide N52–59 relevant for the lymphocytic choriomeningitis virus-specific P14- and vesicular stomatitis virus-specific N15-TCRs, respectively, and examined their effects on thymocytes in vivo using irradiation chimeras. Injection of APL into irradiated congenic (Ly-5.1) mice, reconstituted with T cell progenitors from the bone marrow of P14 RAG2−/− (Ly-5.2) or N15 RAG2−/− (Ly-5.2) transgenic mice, resulted in positive selection of T cells expressing the relevant specificity. Moreover, the variants led to export of virus-specific T cells to lymph nodes, but without inducing T cell proliferation. These findings show that the mature T cell repertoire can be altered by in vivo peptide administration through manipulation of thymic selection.
Tyrosine Kinase 2 Interacts with and Phosphorylates Receptor for Activated C Kinase-1, a WD Motif-Containing Protein
Authors: Haro Takashi , Shimoda Kazuya , Kakumitsu Haruko , Kamezaki Kenjirou , Numata Akihiko , Ishikawa Fumihiko , Sekine Yuichi , Muromoto Ryuta , Matsuda Tadashi , Harada Mine 
Published: April 2014

Abstract
Receptor for activated C kinase (Rack)-1 is a protein kinase C-interacting protein, and contains a WD repeat but has no enzymatic activity. In addition to protein kinase C, Rack-1 also binds to Src, phospholipase Cγ, and ras-GTPase-activating proteins. Thus, Rack-1 is thought to function as a scaffold protein that recruits specific signaling elements. In a cytokine signaling cascade, Rack-1 has been reported to interact with the IFN-αβ receptor and Stat1. In addition, we show here that Rack-1 associates with a member of Jak, tyrosine kinase 2 (Tyk2). Rack-1 interacts weakly with the kinase domain and interacts strongly with the pseudokinase domain of Tyk2. Rack-1 associates with Tyk2 via two regions, one in the N terminus and one in the middle portion (aa 138–203) of Rack-1. Jak activation causes the phosphorylation of tyrosine 194 on Rack-1. After phosphorylation, Rack-1 is translocated toward the perinuclear region. In addition to functioning as a scaffolding protein, these results raise the possibility that Rack-1 functions as a signaling molecule in cytokine signaling cascades.
Direct Repression of prdm1 by Bcl-6 Inhibits Plasmacytic Differentiation
Authors: Tunyaplin Chainarong , Shaffer A. L. , Angelin-Duclos Cristina D. , Yu Xin , Staudt Louis M. , Calame Kathryn L. 
Published: April 2014

Abstract
We have identified two intronic regions of mouse prdm1, the gene encoding B lymphocyte-induced maturation protein-1 (Blimp-1), which confer transcriptional repression in response to Bcl-6. The Bcl-6 response element in intron 5, which is conserved between mice and humans, was studied in detail. It binds Bcl-6 in vitro and was shown by chromatin immunoprecipitation to be occupied by Bcl-6 in vivo. Neither Bcl-6 response element functions as a STAT3-response element, showing that STAT3 does not compete with Bcl-6 at these sites. Bcl-6−/− mice confirm the biological importance of Bcl-6-dependent repression of prdm1. These mice have elevated Ab response, increased Ig-secreting cells, and increased Blimp-1+ cells in spleen following immunization and their splenic B cells show accelerated plasmacytic development in vitro.
TLR4 Is the Signaling but Not the Lipopolysaccharide Uptake Receptor
Authors: Dunzendorfer Stefan , Lee Hyun-Ku , Soldau Katrin , Tobias Peter S. 
Published: April 2014

Abstract
TLR4 is the primary recognition molecule for inflammatory responses initiated by bacterial LPS (endotoxin). Internalization of endotoxin by various cell types is an important step for its removal and detoxification. Because of its role as an LPS-signaling receptor, TLR4 has been suggested to be involved in cellular LPS uptake as well. LPS uptake was investigated in primary monocytes and endothelial cells derived from TLR4 and CD14 knockout C57BL/6 mice using tritiated and fluorescein-labeled LPS. Intracellular LPS distribution was investigated by deconvolution confocal microscopy. We could not observe any difference in LPS uptake and intracellular LPS distribution in either monocytes or endothelial cells between TLR4−/− and wild-type cells. As expected, CD14−/− monocytes showed a highly impaired LPS uptake, confirming CD14-dependent uptake in monocytes. Upon longer incubation periods, the CD14-deficient monocytes mimicked the LPS uptake pattern of endothelial cells. Endothelial cell LPS uptake is slower than monocyte uptake, LBP rather than CD14 dependent, and sensitive to polyanionic polymers, which have been shown to block scavenger receptor-dependent uptake mechanisms. We conclude that TLR4 is not involved in cellular LPS uptake mechanisms. In membrane CD14-positive cells, LPS is predominantly taken up via CD14-mediated pathways, whereas in the CD14-negative endothelial cells, there is a role for scavenger receptor-dependent pathways.
Suppression of Ongoing Adjuvant-Induced Arthritis by Neutralizing the Function of the p28 Subunit of IL-27
Authors: Goldberg Ruth , Wildbaum Gizi , Zohar Yaniv , Maor Gila , Karin Nathan 
Published: April 2014

Abstract
IL-27 is a recently defined family member of the long-chain four-helix bundle cytokines, which consists of EBI3, an IL-12p40-related protein, and p28, an IL-12p35-related polypeptide. The role of IL-27 in the regulation of inflammatory autoimmune diseases has never been studied. The current study uses the DNA vaccination technology, and highly specific Abs to the p28 subunit of IL-27 that were generated by this technology, to delineate its role in the regulation of adjuvant-induced arthritis in Lewis rats. Neutralizing the in vivo function of IL-27 by targeted DNA vaccines and by Abs against IL-27 p28 that were produced in protected donors could rapidly suppress an ongoing disease. Disease suppression was associated with a reduced ex vivo production of inflammatory cytokines. We then used these Abs to investigate the mechanistic basis of disease suppression, showing that IL-27 is not only involved in directing the polarization of naive T cells, but also affects the proliferative response and cytokine production of Ag-specific effector/memory Th1 cells. This may explain, in part, its important role in the regulation of inflammatory autoimmune diseases, and also suggest novel ways of therapy.
TLR9 Is Localized in the Endoplasmic Reticulum Prior to Stimulation
Authors: Leifer Cynthia A. , Kennedy Margaret N. , Mazzoni Alessandra , Lee ChangWoo , Kruhlak Michael J. , Segal David M. 
Published: April 2014

Abstract
In mammals, 10 TLRs recognize conserved pathogen-associated molecular patterns, resulting in the induction of inflammatory innate immune responses. One of these, TLR9, is activated intracellularly by bacterial DNA and synthetic oligodeoxynucleotides (ODN), containing unmethylated CpG dinucleotides. Following treatment with CpG ODN, TLR9 is found in lysosome-associated membrane protein type 1-positive lysosomes, and we asked which intracellular compartment contains TLR9 before CpG exposure. Surprisingly, we found by microscopy and supporting biochemical evidence that both transfected and endogenously expressed human TLR9 is retained in the endoplasmic reticulum. By contrast, human TLR4 trafficked to the cell surface, indicating that endoplasmic reticulum retention is not a property common to all TLRs. Because TLR9 is observed in endocytic vesicles following exposure to CpG ODN, our data indicate that a special mechanism must exist for translocating TLR9 to the signaling compartments that contain the CpG DNA.
Role of IFN Regulatory Factor-1 and IL-12 in Immunological Resistance to Pathogenesis of N-Methyl-N-Nitrosourea-Induced T Lymphoma
Authors: Liu Jianguo , Xiang Zhaoying , Ma Xiaojing 
Published: April 2014

Abstract
IFN regulatory factor-1 (IRF-1) is a critical effector molecule in IFN signaling and acts as a tumor suppressor and tumor susceptibility gene. IL-12 is a key factor in the induction of innate resistance and generation of Th1 cells and CTL. Our recent study has revealed an intimate relationship between IRF-1 and IL-12 in that IRF-1 regulates the production of IL-12 by selectively controlling transcriptional activation of IL-12 p35 gene. In this work, we find that IRF-1-deficient mice are highly susceptible to N-methyl-N-nitrosourea (MNU)-induced T lymphomas. This susceptibility is associated with strong defects in the expression of IL-12, lymphotoxin (LT)β, and IFN-γ. Consistently, IL-12 p35−/−, IFN-γ−/−, and LTβ−/− mice are also highly vulnerable to MNU-induced carcinogenesis. Administration of rIL-12 to IRF-1−/− mice restores normal expression of LTβ and IFN-γ, and significantly enhances the ability of IRF-1−/− mice to resist MNU-induced pathogenesis. This strongly suggests an IRF-1/IL-12/IFN-γ regulatory axis in tumor surveillance. By DNA microarray analysis, we comprehensively identify differences and patterns in gene expression in splenocytes of wild-type (WT) vs IRF-1−/− mice challenged with MNU. This study contributes to efforts to elucidate the cellular/molecular mechanisms and the downstream players involved in IRF-1-mediated host defense against lymphoproliferative malignancies.