Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.2.3.23 (GAS)
 957 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

BCL-6 is a POZ domain zinc-finger transcription factor that appears to play important roles in the development of the immune system and its regulation. Mutations within BCL-6 gene can therefore contribute to the genesis of a variety of lymphomas, and can also manifest as a classic Th2-type hyperimmune response. In addition to its roles in B- and T-cell development, and in germinal centre formation, the factor is also critical for the development of peripheral memory T cells. In this study, we report that BCL-6 expression is induced by IFN-gamma in Jurkat cells and in nontransformed T cells polarized toward the Th1 phenotype. The IFN-gamma-responsive region has been mapped within the first exon between nucleotide +180 and +200. In vivo footprinting of the first exon reveals that a stretch of DNA between nucleotide +180 to +195 (which we term the X-box) is constitutively occupied in vivo in the presence or absence of IFN-gamma. A guanine at +195 residing at the boundary of the X-box and a downstream IFN-gamma-activated sequence (GAS 1; between nucleotides +192 to +200) is occupied in IFN-gamma-treated cells, indicating the interaction of an IFN-gamma-inducible/modified factor to this region. Consistent with this, electrophoretic mobility shift assays detect STAT-1alpha interactions with the downstream GAS1 motif. The cumulative data suggest that the X-box-binding protein facilitate the binding of STAT-1alpha to the GAS 1 site. The discovery that the BCL-6 transcription factor is inducible by IFN-gamma may help explain some of the postulated biological roles of BCL-6 in T cell development and differentiation, and help explain the Th2-biased phenotype of BCL-6-deficient mice.
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PMID:Induction of BCL-6 gene expression by interferon-gamma and identification of an IRE in exon I. 1559 57

The MHC class II transactivator (CIITA), the master regulator of MHC class II (MHC II) expression, is a co-activator that controls MHC II transcription. Human B lymphocytes express MHC II constitutively due to persistent activity of CIITA promoter III (pIII), one of the four potential promoters (pI-pIV) of this gene. Although increases in MHC II expression in B cells in response to cytokines have been observed and induction of MHC II and CIITA by IFN-gamma has been studied in a number of different cell types, the specific effects of IFN-gamma on CIITA expression in B cells have not been studied. To investigate the regulation of CIITA expression by IFN-gamma in B cells, RT-PCR, in vivo and in vitro protein/DNA binding studies, and functional promoter analyses were performed. Both MHC II and CIITA type IV-specific RNAs increased in human B lymphocytes in response to IFN-gamma treatment. CIITA promoter analysis confirmed that pIV is IFN-gamma inducible in B cells and that the GAS and IRF-E sites are necessary for full induction. DNA binding of IRF-1 and IRF-2, members of the IFN regulatory factor family, was up-regulated in B cells in response to IFN-gamma and increased the activity of CIITA pIV. In vivo genomic footprint analysis demonstrated proteins binding at the GAS, IRF-E and E box sites of CIITA pIV. Although CIITA pIII is considered to be the hematopoietic-specific promoter of CIITA, these findings demonstrate that pIV is active in B lymphocytes and potentially contributes to the expression of CIITA and MHC II in these cells.
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PMID:Expression of the MHC class II transactivator (CIITA) type IV promoter in B lymphocytes and regulation by IFN-gamma. 1595 Feb 83

Costimulation between T cells and antigen-presenting cells is required for adaptive immune responses. CD40, a costimulatory molecule, is expressed in macrophages and microglia. The aberrant expression of CD40 is involved in human diseases including multiple sclerosis, rheumatoid arthritis, and Alzheimer's disease. CD40 expression is induced by a variety of stimuli, including IFN-gamma and lipopolysaccharide (LPS). In this study, we describe the molecular basis by which IFN-beta, a cytokine with immunomodulatory properties, regulates CD40 gene expression. IFN-beta induces CD40 expression in macrophages and microglia at the transcriptional level, and GAS elements in the CD40 promoter are required for IFN-beta-induced CD40 promoter activity. The critical role of signal transducers and activators of transcription-1alpha (STAT-1alpha) in this response was confirmed by utilizing primary microglia from STAT-1alpha deficient mice. IFN-beta induces suppressor of cytokine signaling-1 (SOCS-1) gene expression, which inhibits cytokine signaling by inhibiting activation of STAT proteins. The ectopic expression of SOCS-1 abrogates IFN-beta-mediated STAT-1alpha activation and inhibits IFN-beta-induced CD40 expression. IFN-beta-induced recruitment of STAT-1alpha and RNA Pol II and permissive histone modifications on the CD40 promoter are also inhibited by SOCS-1 overexpression. These novel results indicate that IFN-beta-induced SOCS-1 plays an important role in the negative regulation of IFN-beta-induced CD40 gene expression.
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PMID:IFN-beta-induced SOCS-1 negatively regulates CD40 gene expression in macrophages and microglia. 1657 71

Previous studies from our laboratory have shown that fulminant hepatitis caused by the mouse hepatitis virus, MHV-3, is dependent on production of the novel immune coagulant fgl2/fibroleukin. In this study, we investigate the role of IFN-gamma and TNF-alpha in the induction of fgl2 expression and fgl2-dependent hepatic apoptosis. Infusion of IFN-gamma in combination with TNF-alpha through the portal vein of fgl2+/+ mice led to widespread hepatic apoptosis and fibrin deposition. Livers from fgl2-/- mice were normal, although strong expression of the fgl2 knockout reporter gene Lac Z was seen in both resident hepatic macrophages and endothelial cells. In vitro, IFN-gamma and TNF-alpha induced fgl2 expression in a macrophage and endothelial cell-specific manner. In macrophages (peritoneal and RAW 264.7 cells), IFN-gamma, but not IFN-alpha, LPS, TNF-alpha, or IL-1 induced fgl2 mRNA transcription and protein expression, while in endothelial cells TNF-alpha, but not IFN-gamma, induced fgl2 transcription. In addition, while TNF-alpha enhanced IFN-gamma-induced macrophage fgl2 transcription, IFN-gamma also enhanced TNF-alpha-induced endothelial cell fgl2 transcription. The induction of fgl2 by IFN-gamma in macrophages involved a STAT1-dependent pathway, involving the composite cis elements Sp1/Sp3 and GAS/PU.1. The latter interacted with IFN-gamma-dependent Sp1/Sp3, STAT1, and the ETS family of transcription factors member PU.1. The interaction of PU.1 with the IFN-gamma-activated sequence/ETS family of transcription factors site determined the macrophage-specific induction of fgl2 by IFN-gamma. Overall, this study demonstrates that IFN-gamma and TNF-alpha induce hepatocyte apoptosis in vivo, which is dependent on induction of fgl2, and defines the molecular basis of transcription of fgl2 in vitro.
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PMID:Cytokine-induced hepatic apoptosis is dependent on FGL2/fibroleukin: the role of Sp1/Sp3 and STAT1/PU.1 composite cis elements. 1670 65

Previous reports suggest that type I and type II Interferon can co-operatively inhibit some virus replication, e.g. HCV, SARS-CoV, HSV-1. To find out the molecular mechanism underlying this phenomenon, we analyzed the transcription profile stimulated by IFN-alpha and IFN-gamma in Huh-7 cells and found that the transcription of a subset of IFN stimulated genes (ISGs) including BclG, XAF1, TRAIL and TAP1 was enhanced when IFN-alpha and gamma were both present. Promoter analysis of BclG revealed that IRF-1 and STAT1 were both required in this process. Enhanced IRF-1/DNA complex formation was observed in interferon co-treatment group by gel shift analysis. Furthermore, IRF-1 activation was found to be generally required in this cluster of ISGs. STAT1 tyrosine phosphorylation was elevated by IFN combination treatment, however, only the hyper-transactivation of GAS but not ISRE was observed. In conclusion, hyper-activation of IRF-1 and elevated STAT1 dimer formation may be two general switches which contribute to a much more robust antiviral symphony against virus replication when type I and type II IFNs are co-administered.
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PMID:Hyper-activated IRF-1 and STAT1 contribute to enhanced interferon stimulated gene (ISG) expression by interferon alpha and gamma co-treatment in human hepatoma cells. 1698 58

We previously identified a 1.2 Kb DNA element (P-1161/+16), 5' to caspase-8 exon-1, that acts as promoter in caspase-8-positive, but not in caspase-8-negative neuroblastoma (NB) cells. The P-1161/+16 DNA element regulates both constitutive and interferon IFN-gamma-inducible caspase-8 expression. Two GAS (IFN-activated sequence, STAT-1 binding site) and two ISRE (interferon sensitive response element, IRF binding site) were present in P-1161/+16. Deletion studies indicated that elements essential for promoter activity in NB cells were present in a 167 bp region 5' flanking exon-1 (P-151/+16), which contains an ISRE at position -32. The transcription initiation site was mapped by 5' rapid amplification of cDNA end (RACE) at position -20 from caspase-8 cDNA reference sequence. Disruption of the ISRE-32 indicated that it is required for both constitutive and IFN-gamma-inducible caspase-8 expression. IRF-1 and IRF-2 transcription factors bind to the (-151/+16) DNA fragment in vitro. Chromatin immunoprecipitation (ChIP) assays showed that IRF-1 and IRF-2 bind to the DNA region at the 5' of caspase-8 gene in NB cells, which show constitutive expression but not in caspase-8 negative cells. In these last cells, up-regulation of caspase-8 by IFN-gamma was associated to induction of IRF-1 and IRF-2 binding to caspase-8 promoter and increased histone acetylation. Moreover, RNA interference experiments also supported the involvement of IRF-1 and IRF-2 in constitutive caspase-8 expression in NB cells.
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PMID:An interferon-sensitive response element is involved in constitutive caspase-8 gene expression in neuroblastoma cells. 1703 21

The MHC class II transactivator (CIITA) acts in the cell nucleus as the master regulator of MHC class II (MHC II) gene expression. It is important to study CIITA regulation in multiple myeloma since MHC expression is central to ability of myeloma cells to present antigen and to the ability of the immune system to recognize and destroy this malignancy. Regulation of CIITA by IFN-gamma in B lymphocytes occurs through the CIITA type IV promoter (pIV), one of the four potential promoters (pI-pIV) of this gene. To investigate regulation of CIITA by IFN-gamma in multiple myeloma cells, first the ability of these cells to respond to IFN-gamma was examined. RT-PCR analyses show that IFN-gammaR1, the IFN-gamma-binding chain of the IFN-gamma receptor, is expressed in myeloma cells and IRF-1 expression increases in response to IFN-gamma treatment. Western blotting demonstrates that STAT1 is activated by phosphorylation in response to IFN-gamma. RT-PCR and functional promoter analyses show that IFN-gamma upregulates the activity of CIITA pIV, as does ectopic expression of IRF-1 or IRF-2. In vivo protein/DNA binding studies demonstrate protein binding at the GAS, E box and IRF-E sites. In vitro studies confirm the binding of IRF-1 and IRF-2 to CIITA pIV. Although multiple myeloma cells express PRDI-BF1/Blimp-1, a factor that represses both the CIITA type III and IV promoters, they retain the capability to upregulate CIITA pIV and MHC II expression in response to IFN-gamma treatment. These findings are the first to demonstrate that although PRDI-BF1/Blimp-1 diminishes the constitutive ability of these cells to present antigen by limiting CIITA and MHC II expression, it is possible to enhance this expression through the use of cytokines, like IFN-gamma.
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PMID:MHC class II transactivator (CIITA) expression is upregulated in multiple myeloma cells by IFN-gamma. 1730 Aug 40

Cytokines are intimately involved with the innate and adaptive immune response to bacterial infections. This study was designed to determine the expression of inflammatory cytokines in children by the severity of Streptococcus pyogenes (group A Streptococcus [GAS]) infections. The study population consisted of 16 invasive, 20 noninvasive, and 24 pharyngeal colonization, and 21 healthy controls. All children underwent the laboratory tests and cytokine measurement. GAS isolates were analyzed for emm gene typing. Patients with invasive GAS diseases had significantly higher interferon (IFN)-gamma, interleukin (IL)-1beta, IL-6, IL-8, IL-10, and IL-18 than those with noninvasive diseases, colonization, and healthy controls. There was no difference in tumor necrosis factor (TNF)-alpha, IL-12, and IL-2 levels among the groups. Elevated white blood cell counts and levels of C-reactive protein and C3 were detected only in patients with invasive diseases. emm1 and emm12 predominated in invasive disease and colonization. Children with invasive GAS infections exhibited significant up-regulation of plasma levels of IFN-gamma, IL-1beta, IL-6, IL-8, IL-10, and IL-18, and suppression of TNF-alpha and IL-12 during the acute phase of their illness. An exuberant cytokine response was associated with the severity of illness.
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PMID:The severity of Streptococcus pyogenes infections in children is significantly associated with plasma levels of inflammatory cytokines. 1829 3

Reporter constructs of three interferon (IFN)-gamma-induced rainbow trout genes were generated to examine specificity to type I or type II IFN. Constructs included gammaIP-10, LMP2 and TAP2 and were used to transfect trout fibroblast cells (RTG-2) which were then exposed to rainbow trout rIFNs. The gammaIP-10 construct showed high reporter activity even in the absence of rIFNs. The LMP2 promoter contained one GAS element and two double ISRE elements, of four constructs made, only those with ISRE elements showed significant reporter activity following rIFN-gamma stimulation. The TAP2 regulatory region contained two GAS, two ISRE and one C/EBP element from which four constructs were made. Reporter expression for the construct containing all five elements showed an 11- and 2-fold increase in response to rIFN-gamma and type I rIFN, respectively. Constructs containing only the GAS elements did not respond to rIFNs. The TAP2 construct with two ISRE and the C/EBP gave the greatest dose-dependent reporter response to rIFN-gamma, with no significant response to type I rIFN. These data suggest that the ISRE elements, or elements nearby, are essential for the induction of type II IFN responsive genes in trout. The TAP2 construct is a candidate to develop a IFN-gamma reporter stable cell line.
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PMID:Characterisation of gamma-interferon responsive promoters in fish. 1845 79

The interferon (IFN)-related cytokine interleukin (IL)-29 (also known as IFN-lambda1) inhibits virus replication by inducing a cellular antiviral response similar to that activated by IFN-alpha/beta. However, because it binds to a unique receptor, this cytokine may function cooperatively with IFN-alpha/beta or IFN-gamma during natural infections to inhibit virus replication, and might also be useful therapeutically in combination with other cytokines to treat chronic viral infections such as hepatitis C (HCV). We therefore investigated the ability of IL-29 and IFN-alpha or IFN-gamma to cooperatively inhibit virus replication and induce antiviral gene expression. Compared with the individual cytokines alone, the combination of IL-29 with IFN-alpha or IFN-gamma was more effective at blocking vesicular stomatitis virus and HCV replication, and this cooperative antiviral activity correlated with the magnitude of induced antiviral gene expression. Although the combined effects of IL-29 and IFN-alpha were primarily additive, the IL-29/IFN-gamma combination synergistically induced multiple genes and had the greatest antiviral activity. Two different mechanisms contributed to the enhanced gene expression induced by the cytokine combinations: increased activation of ISRE promoter elements and simultaneous activation of both ISRE and GAS elements within the same promoter. These findings provide new insight into the coregulation of a critical innate immune response by functionally distinct cytokine families.
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PMID:Interleukin-29 functions cooperatively with interferon to induce antiviral gene expression and inhibit hepatitis C virus replication. 1875 65


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