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)

Binding of many cytokines to their cognate receptors immediately activates Jak tyrosine kinases and their substrates, STAT (signal transducers and activators of transcription) DNA-binding proteins. The DNA binding targets of STATs are sequence elements related to the archetypal gamma interferon activation site, GAS. However, association of interleukin 1 (IL-1) with Jak-STAT signaling has remained unresolved. We now report an element termed LILRE (lipopolysaccharide [LPS] and IL-1-responsive element) in the human prointerleukin 1beta gene (IL1B) which can be immediately induced by either lipopolysaccharide (LPS) or IL-1 protein to bind a tyrosine-phosphorylated protein. This LPS- and IL-1-induced factor (LIL factor) is recognized by an antibody raised against the N terminus of Stat1, but not by those specific for either the C terminus of Stat1 or any other GAS-binding STAT. Phosphotyrosine (P-Tyr) specifically inhibits formation of the LIL factor-DNA complex, suggesting the importance of P-Tyr for the DNA-binding activity, as has been found for all STAT dimers. Analysis of DNA-binding specificity demonstrates that the LIL factor possesses a novel GAS-like binding activity that contrasts with those of other STATs in a requirement for a G residue at position 8 (TTCCTGAGA). Further investigation has revealed that IL-6, but neither IL-4 nor gamma interferon, activates the LIL factor. Thus, the existence of such a STAT-like factor (LIL-Stat) relates the LPS and IL-1 signaling pathway to other cytokine receptor signaling pathways via the activation of STATs. Moreover, the unique DNA-binding specificity and antigenicity of this factor suggest that LPS, IL-1, and IL-6 may use a common signaling pathway.
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PMID:A novel STAT-like factor mediates lipopolysaccharide, interleukin 1 (IL-1), and IL-6 signaling and recognizes a gamma interferon activation site-like element in the IL1B gene. 862 85

Incubation of primary cultures of rat hepatocytes with lipopolysaccharide (LPS), S-[2,3-bis(palmitoyloxy)-(2-R, S)-propyl]-N-palmitoyl-(R)-Cys-Ser-Lys4 (TPP), a synthetic lipopeptide present in bacterial cell wall lipoproteins, or with phorbol 12,13-dibutyrate (PDBu) induced an increase in nitric oxide synthesis through the expression of type II nitric oxide synthase (iNOS). Transfection of hepatocytes with a HindII fragment corresponding to the promoter region of the murine iNOS gene (from nucleotide -1588 to +165) resulted in the expression of the reporter gene when cells were stimulated with these factors. The transcription factors activated by these stimuli involved an increase in the nuclear content of proteins that bind to kappaB, AP-1, GAS, and SIE sequences. Inhibition of NF-kappaB activation with pyrrolidine dithiocarbamate eliminated the expression of iNOS in hepatocytes stimulated with LPS, TPP, or PDBu. In addition to this, transfection of hepatocytes with promoter mutants in which a sequential 2-base pair change within the kappaB sites was introduced (position -971 to -961 and -85 to -75, respectively), resulted in approximately 17 and 35%, respectively, of the activity of the naive promoter. Simultaneous mutation of both kappaB sites abolished the promoter activity. Analysis of the proteins involved in kappaB binding showed the presence of p50/p65 dimers in the nuclei of activated cells at the time that an important decrease of IkappaB-alpha was observed soon after cell stimulation with LPS, TPP, or PDBu. However, only LPS was able to decrease the amount of IkappaB-beta. These results suggest that LPS, TPP, and PDBu, although activating different signal transduction pathways, use a common mechanism mediating iNOS expression in cultured hepatocytes.
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PMID:Evidence for common mechanisms in the transcriptional control of type II nitric oxide synthase in isolated hepatocytes. Requirement of NF-kappaB activation after stimulation with bacterial cell wall products and phorbol esters. 893 60

The activation status of a recently identified STAT (signal transducers and activators of transcription) factor, LIL-Stat (lipopolysaccharide [LPS]/IL-1-inducible Stat) in adult T-cell leukemia (ATL) cells was investigated by electrophoretic mobility shift assays using nuclear extracts of leukemic cells from 7 patients with ATL and a GAS (gamma interferon activation site)-like element termed LILRE (LPS/IL-1-responsive element), which is found in the human prointerleukin 1beta (IL1B) gene. Spontaneous DNA binding of LIL-Stat was observed in all ATL cells examined. However, in normal human peripheral lymphocytes, DNA binding of LIL-Stat was detected only after stimulation with IL-1. These results demonstrated that LIL-Stat is constitutively activated in ATL cells. Furthermore, our transient transfection studies using LILRE chloramphenicol acetyltransferase (CAT) reporters argue that LIL-Stat in ATL cells functions as a transcriptional activator through binding to the LILRE in the IL1B gene. (Blood. 2000;95:2715-2718)
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PMID:Constitutive activation of LIL-Stat in adult T-cell leukemia cells. 1075 55

1. In this study we examined the signalling events that regulate lipopolysaccharide (LPS)-stimulated induction of interferon regulatory factor (IRF)-1 in human umbilical vein endothelial cells (HUVECs). 2. LPS stimulated a time- and concentration-dependent increase in IRF-1 protein expression, an effect that was mimicked by the cytokine, tumour necrosis factor (TNF)-alpha. 3. LPS stimulated a rapid increase in nuclear factor kappa B (NFkappaB) DNA-binding activity. Pre-incubation with the NFkappaB pathway inhibitors, N-alpha-tosyl-L-lysine chloromethyl ketone (TLCK) or pyrrolidine dithiocarbamate (PDTC), or infection with adenovirus encoding IkappaBalpha, blocked both IRF-1 induction and NFkappaB DNA-binding activity. 4. LPS and TNFalpha also stimulated a rapid activation of gamma interferon activation site/gamma interferon activation factor (GAS/GAF) DNA-binding in HUVECs. Preincubation with the Janus kinase (JAK)-2 inhibitor, AG490 blocked LPS-stimulated IRF-1 induction but did not affect GAS/GAF DNA-binding. 5. Preincubation with TLCK, PDTC or infection with IkappaBalpha adenovirus abolished LPS-stimulated GAS/GAF DNA-binding. 6. Incubation of nuclear extracts with antibodies to RelA/p50 supershifted GAS/GAF DNA-binding demonstrating the involvement of NFkappaB isoforms in the formation of the GAS/GAF complex. 7. These studies show that NFkappaB plays an important role in the regulation of IRF-1 induction in HUVECs. This is in part due to the interaction of NFkappaB isoforms with the GAS/GAF complex either directly or via an intermediate protein.
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PMID:Nuclear factor kappa B is involved in lipopolysaccharide-stimulated induction of interferon regulatory factor-1 and GAS/GAF DNA-binding in human umbilical vein endothelial cells. 1173 38

PKR, the double-stranded RNA (dsRNA)-activated serine/threonine kinase, has been implicated as an important component of host responses to infection and various situations of cellular stress. The involvement of PKR in signal transduction and regulation of transcription suggested to us that it may play an important role in lipopolysaccharide (LPS)-induced activation of STAT1 in rat brain immune cells. We found that LPS rapidly stimulated the phosphorylation of PKR within 5 min, followed by phosphorylation of STAT1 at 2 h in rat primary microglia and astrocyte. Using 2-aminopurine (2-AP), a pharmacological inhibitor of PKR, and PKR-specific short interfering RNA (siRNA), we demonstrated that activation of PKR was essential for LPS-induced activation of STAT1. Inhibition of PKR activity by 2-AP resulted in suppression not only of STAT1 phosphorylation, but also of nuclear factors binding activity to GAS/ISRE elements. 2-AP also significantly suppressed the downstream events of LPS-stimulated STAT1 phosphorylation, including STAT-mediated transcriptional responses and generation of nitric oxide, a hallmark of brain inflammation. Consistent with these results, transfection of PKR-specific siRNA markedly attenuated all the STAT1 dependent inflammatory signaling responses tested. We further revealed that activation of PKR by LPS led to the induction of IFN-beta through activation of NF-kappaB, triggering the phosphorylation of STAT1 in rat brain glial cells. Taken together, these findings indicate that PKR functions as an essential modulator in LPS-induced STAT inflammatory signaling events, and provides new insight into endotoxin-induced CNS diseases following infection.
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PMID:Double-stranded RNA-activated protein kinase is required for the LPS-induced activation of STAT1 inflammatory signaling in rat brain glial cells. 1563 Jul 3

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

Induction of nitric oxide synthase-2 (iNOS) by cytokines and bacterial products is associated with protein binding at the proximal promoter and in an upstream enhancer region of the Nos2 gene. To clarify how ethanol suppresses rat iNOS activity, we constructed several deletion mutants of the Nos2 promoter fused to the luciferase gene and transfected the constructs into C6 glial cells. Acute ethanol exposure of stably transfected cells for 24 h inhibits induced activity of Nos2 promoter constructs containing deletions in the 5' flanking region, including a 94 bp promoter that lacks any known NF-kappaB site but which carries a C/EBPbeta and overlapping gamma-IRE, GAS and Oct motifs. Ethanol failed to inhibit the endogenous activity of a smaller, 78 bp promoter that lacks the C/EBPbeta and overlapping, gamma-IRE and GAS motifs and showed no inducible activity. As another approach, in vivo DNA footprinting was used and identified protein protections at five regions of the proximal Nos2 promoter in induced cells. Exposure to acute ethanol diminished protein occupation in the five promoter regions including the gamma-IRE/NF-kappaB and the overlapping gamma-IRE/GAS/Oct sites. Site-directed mutagenesis in the octamer domain of the gamma-IRE/GAS/Oct motifs was studied in a 1002 bp promoter to examine its role in ethanol inhibition of cytokine and lipopolysaccharide induced activity. The data indicate that ethanol failed to inhibit promoter activity when the Oct motif is missing. Electrophoretic mobility shift assays performed using a 22-mer probe containing the overlapping gamma-IRE/GAS/Oct sites showed three complexes with one of the complexes being competed by an octamer-1 antibody. These observations demonstrate the role of protein-DNA binding at the core promoter, and the likely involvement of the octamer motif, in ethanol modulation of cytokine and lipopolysaccharide induced iNOS expression.
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PMID:The Oct DNA motif participates in the alcohol inhibition of the inducible nitric oxide synthase gene promoter in rat C6 glioma cells. 1793 31

Lectins are sugar-binding proteins that mediate pathogen recognition and cell-cell interactions. A rhamnose-binding lectin (RBL) gene and its promoter region have been cloned and characterized from snakehead Channa argus. From the transcription initiation site, snakehead rhamnose-binding lectin (SHL) gene extends 2,382 bp to the end of the 3' untranslated region (UTR), and contains nine exons and eight introns. The open reading frame (ORF) of the SHL transcript has 675 bp which encodes 224 amino acids. The molecular structure of SHL is composed of two tandem repeat carbohydrate recognition domains (CRD) with 35% internal identity. Analysis of the gene organization of SHL indicates that the ancestral gene of RBL may diverge and evolve by exon shuffling and gene duplication, producing new forms to play their own roles in various organisms. The characteristics of SHL gene 5' flanking region are the presence of consensus nuclear factor of interleukin 6 (NF-IL6) and IFN-gamma activation (GAS) sites. The results provide indirect evidence that up-regulation of SHL expression may be induced in response to inflammatory stimuli, such as lipopolysaccharide (LPS), interleukin 6 (IL-6), and interferon gamma (IFN-gamma). The transcript of SHL mRNA was expressed in the head kidney, posterior kidney, spleen, liver, intestine, heart, muscle, and ovary. No tissue-specific expressive pattern is different from reported STLs, WCLs, and PFLs, suggesting that different types of RBLs exist in species-specific fish that have evolved and adapted to their surroundings.
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PMID:Molecular cloning of rhamnose-binding lectin gene and its promoter region from snakehead Channa argus. 1932 50