Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tissue factor (TF) expression by endothelial cells is implicated in thrombotic episodes in patients with a variety of clinical disorders. In a baboon model of lethal sepsis, TF is expressed by endothelial cells in the splenic microvasculature. In vitro, endothelial cells are induced to express TF in response to tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and bacterial endotoxin (lipopolysaccharide [LPS]). Here, we identified cis-acting regulatory elements that control TF gene transcription in primary human endothelial cells. Functional studies showed that the TF promoter contained a 56-bp enhancer (-227 to -172 bp), which included two activator protein-1 (AP-1) sites and a kappa B-like site, that mediated induction by TNF-alpha, IL-1 beta, and LPS. Electrophoretic mobility shift assays demonstrated that endothelial cells contained constitutive AP-1 binding activity, whereas the kappa B-like site, 5'-CGGAGTTTCC-3', bound an inducible nuclear complex composed of c-Rel-p65 heterodimers. Taken together, our data suggest that induction of TF gene transcription in endothelial cells is mediated by functional interactions between Fos-Jun and c-Rel-p65 heterodimers.
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PMID:Transcriptional regulation of tissue factor expression in human endothelial cells. 774 75

Taxol, a plant-derived antimitotic, was recently found to mimic several of the effects of endotoxic bacterial lipopolysaccharide on murine macrophages. However, the mechanisms underlying the cell cycle-independent actions of taxol remain unclear. Here, we report that taxol rapidly activated nuclear factor kappa B (NF-kappa B) in mouse peritoneal macrophages. The intranuclear transcription factor complexes contained two NF-kappa B heterodimers, p50/RelA and p50/c-rel. Taxol-induced nuclear translocation of NF-kappa B was inhibited by pyrrolidine dithiocarbamate, an antioxidant, but not by cycloheximide, a protein synthesis inhibitor. The ability of taxol to activate NF-kappa B may help account for its induction of immunoregulatory and cytotoxic cytokines, which in turn may contribute to its antitumor effects.
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PMID:Activation of NF-kappa B in murine macrophages by taxol. 776

The effects of bacterial lipopolysaccharide (LPS) on macrophage gene expression are mediated in part by its ability to induce activation of transcription factor NF-kappa B. We compared the ability of LPS-treated macrophages from Lpsn (LPS-responsive) C3H/HeN and Lpsd (LPS-hyporesponsive) C3H/HeJ mice to mobilize NF-kappa B by electrophoretic mobility shift assays with oligonucleotide probes containing a unique NF-kappa B sequence from the promoter of inducible nitric oxide synthase (iNOS). In response to ng/ml concentrations of LPS, this probe bound proteins that appeared rapidly in the nuclei of thioglycollate-elicited macrophages and bone marrow-derived macrophage cell lines from both Lpsn and Lpsd mice. Only in macrophages from Lpsn mice, however, was LPS able to induce iNOS or tumor necrosis factor alpha. NF-kappa B-containing DNA-protein complexes from Lpsd macrophages were formed in lesser amounts than from Lpsn macrophages but shared the same composition, insofar as they displayed the same electrophoretic mobilities and content of heterodimers of p50/RelA (p65) and p50/c-rel. Two conclusions emerge from these findings: (1) NF-kappa B activity alone is not sufficient for induction of certain LPS-responsive genes and (2) An LPS-response pathway involving activation of NF-kappa B is preserved in Lpsd mice. The inability of cells from Lpsd mice to induce gene expression in response to LPS thus cannot be attributed to inability to activate NF-kappa B.
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PMID:Macrophages derived from C3H/HeJ (Lpsd) mice respond to bacterial lipopolysaccharide by activating NF-kappa B. 782 69

Tissue factor (TF) is expressed rapidly by human monocytes exposed to bacterial endotoxin (lipopolysaccharide, or LPS). Transcriptional regulation is mediated by binding of c-Rel/p65 heterodimers to a kappa B-like site in the TF promoter. Nuclear translocation of cytosolic c-Rel/p65 heterodimers and other members of the NF-kappa B/Rel family requires dissociation and proteolytic degradation of the inhibitor protein, I kappa B alpha. The protease inhibitors N alpha-tosylphenylalanyl chloromethyl ketone (TPCK) and N alpha-tosyl-L-lysine chloromethyl ketone (TLCK) block activation of NF-kappa B/Rel proteins by preventing degradation of I kappa B alpha. To determine if TPCK and TLCK inhibited LPS induction of TF expression, freshly isolated human monocytes and monocytic THP-1 cells were pretreated with these inhibitors for 30 min before LPS stimulation. Both TPCK and TLCK inhibited LPS induction of TF protein, TF mRNA and TF promoter activity in a dose-dependent manner. These inhibitors specifically prevented degradation of I kappa B alpha and nuclear translocation of c-Rel/p65 heterodimers. In contrast, TPCK and TLCK did not block induction of an immediate-early gene encoding the transcription factor, Egr-1. Taken together, these data indicated that inhibiting nuclear translocation of c-Rel/p65 heterodimers prevented LPS induction of TF gene transcription in monocytic cells.
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PMID:Protease inhibitors block lipopolysaccharide induction of tissue factor gene expression in human monocytic cells by preventing activation of c-Rel/p65 heterodimers. 792 55

Stimulation of endothelial cells by cytokines and bacterial lipopolysaccharide leads to activation of the transcription factor NF-kappa B. NF-kappa B in turn regulates the expression of several genes involved in the inflammatory reaction, including cell adhesion molecules, interleukins, and transcription factors. One of these induced genes encodes an inhibitor of NF-kappa B, ECI-6/I kappa B alpha, that contains in its 5' regulatory region six consensus binding sites for NF-kappa B. We demonstrate here that these sites display striking differences in their ability in vitro to bind to various NF-kappa B subunits. In vivo, all six sites contribute, though to varying degrees, to transcription from the ECI-6/I kappa B alpha promoter, as demonstrated by deletion and mutation analysis. Among the NF-kappa B subunits tested p65, the p65/p50 heterodimer and, to a lesser extent, c-Rel, are able to activate transcription, whereas p50 or p50/Re1B were inactive. Since many genes regulated by NF-kappa B contain only one or two DNA-binding sites for this transcription factor, the presence of six functional NF-kappa B-binding sites in the ECI-6/I kappa B alpha promoter represents a unique feature of this gene.
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PMID:NK-kappa B subunit-specific regulation of the I kappa B alpha promoter. 817 90

Exposure of monocytic cells to bacterial lipopolysaccharide (LPS) activates the NF-kappa B/Rel family of proteins and leads to the rapid induction of inflammatory gene products, including tissue factor (TF). TF is the primary cellular initiator of the coagulation protease cascades. Here we report the characterization of a nuclear complex from human monocytic cells that bound to a kappa B-like site, 5'-CGGAGTTTCC-3', in the 5'-flanking region of the human TF gene. This nuclear complex was activated by LPS with kinetics that preceded induction of the TF gene. In vitro binding studies demonstrated that the TF site bound translated c-Rel and p65 homodimers but not p50/p65 heterodimers or p50 homodimers. Base-pair substitutions in the TF site indicated that the presence of a cytosine at position 1 precluded binding of NF-kappa B. In fact, under low-ionic-strength conditions, the TF complex did not migrate with translated p50/p65 dimers but instead comigrated with c-Rel/p65 dimers. Antibodies against the NF-kappa B and Rel proteins and UV cross-linking studies revealed the presence of c-Rel and p65 and the absence of p50 in the TF complex and further showed that c-Rel/p65 heterodimers selectively bound to the TF kappa B-like site. Functional studies indicated that the TF site conferred LPS inducibility on a heterologous promoter and was transactivated by c-Rel or p65. Taken together, our results demonstrated that binding of c-Rel/p65 heterodimers to a novel kappa B-like site mediated LPS induction of TF gene expression in monocytic cells.
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PMID:Lipopolysaccharide induction of tissue factor gene expression in monocytic cells is mediated by binding of c-Rel/p65 heterodimers to a kappa B-like site. 819 20

The transcription factor NF-kappa B is stored in the cytoplasm in complexes with the inhibitor protein I kappa B alpha. It has been shown in vitro that dissociation of I kappa B alpha from these complexes results in active NF-kappa B. In this report we show that lipopolysaccharide (LPS)-induced activation of B or pre-B cells results in loss of I kappa B alpha from NF-kappa B complexes in vivo. Many liberated NF-kappa B dimers reached the nucleus, where increased c-rel, p65 and p50 were detected by immunoblotting and by DNA binding assays. Some liberated dimers were retained in the cytoplasm, however, through binding to newly synthesized I kappa B alpha, a finding which strongly suggests (i) that the LPS-induced signal causes dissociation of complexes rather than preventing their association and (ii) that dissociation results from modification of I kappa B alpha and not of c-rel or p65. No effect of LPS treatment was detected on p105 or p100, which also retain rel family members in the cytoplasm. Quite unexpectedly, we also found that in unstimulated cells there is a constant ongoing process of degradation and replacement of complexed I kappa B alpha. We propose that this turnover results in the low level of active NF-kappa B presumably necessary even in the unstimulated cell, and that the high rate of synthesis of I kappa B alpha provides the ability to turn off NF-kappa B activity rapidly as soon as the activating signal ceases.
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PMID:In vivo control of NF-kappa B activation by I kappa B alpha. 822 78

Nuclear factor kappa B (NF-kappa B) is an important regulator of gene expression in cells of the immune system. One such gene, tumor necrosis factor, is induced by bacterial lipopolysaccharide (LPS) in macrophages, and this induction has been shown to be mediated in part by NF-kappa B activation in murine macrophages. In this study, immunochemical analysis was used to follow LPS activation of the NF-kappa B 50-kDa subunit in the RAW264 macrophage-like cell line. The recombinant NF-kappa B 50-kDa subunit was used as an immunogen to produce a rabbit antiserum, which was then affinity-purified using a portion of the NF-kappa B 50-kDa subunit that does not have homology to other members of the c-rel gene family. Untreated macrophages had little NF-kappa B in the nucleus as detected by Western immunoblotting. The protein was predominantly localized in the cytoplasmic fraction. Interestingly, NF-kappa B was found as the 50-kDa mature protein and 105-kDa precursor. After LPS treatment, there was a rapid nuclear translocation of NF-kappa B as detected by immunoblot analysis. There was also a rapid decrease in the amount of the cytoplasmic 105-kDa protein. This may indicate that the 105-kDa protein is a reservoir for the 50-kDa protein and that one of the actions of LPS is to increase the rate of 105-kDa precursor processing.
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PMID:Lipopolysaccharide stimulates both nuclear localization of the nuclear factor kappa B 50-kDa subunit and loss of the 105-kDa precursor in RAW264 macrophage-like cells. 834 9

The -300 region of the interleukin 1 beta (IL-1 beta) promoter contains a functional NF-kappa B binding site composed of the decamer sequence 5'-GGGAAAATCC-3'. Probes representing the -300 region or the NF-kappa B site alone interacted with NF-kappa B proteins present in phorbol myristate acetate-, lipopolysaccharide-, or Sendai virus-induced myeloid cell extracts as well as recombinant NFKB1 (p50) and RelA (p65); furthermore, NF-kappa B protein-DNA complex formation was dissociated in vitro by the addition of recombinant I kappa B alpha. Mutation of the NF-kappa B site in the context of the IL-1 beta promoter reduced the responsiveness of the IL-1 beta promoter to various inducers, including phorbol ester, Sendai virus, poly(rI-rC), and IL-1 beta. A 4.4-kb IL-1 beta promoter fragment linked to a chloramphenicol acetyltransferase reporter gene was also preferentially inducible by coexpression of individual NF-kappa B subunits compared with a mutated IL-1 beta promoter fragment. When multiple copies of the IL-1 beta NF-kappa B site were linked to an enhancerless simian virus 40 promoter, this element was able to mediate phorbol ester- or lipopolysaccharide-inducible gene expression. In cotransfection experiments, RelA (p65) and c-Rel (p85) were identified as the main subunits responsible for the activation of the IL-1 beta NF-kappa B site; also, combinations of NFKB1 (p50) and RelA (p65) or c-Rel and RelA were strong transcriptional activators of reporter gene activity. The presence of a functional NF-kappa B binding site in the IL-1 beta promoter suggests that IL-1 positively autoregulates its own synthesis, since IL-1 is a strong inducer of NF-kappa B binding activity. Thus, the IL-1 beta gene may be considered as an important additional member of the family of cytokine genes regulated in part by the NF-kappa B/rel family of transcription factors.
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PMID:Characterization of a functional NF-kappa B site in the human interleukin 1 beta promoter: evidence for a positive autoregulatory loop. 841 23

Many effects of lipopolysaccharide (LPS) on gene expression, including that of human immunodeficiency virus (HIV), in monocytic cells are mediated by activation of kappa B DNA-binding proteins. However, the specific members of the NF-kappa B/Rel transcription factor family involved in the LPS response, and the mechanisms through which LPS-generated signals are transduced remain unclear. Here we show that LPS induces nuclear expression of c-Rel/p50 heterodimers as well as p50/p65 (NF-kappa B) kappa B DNA-binding complexes in human monocytic THP-1 cells. Nuclear localization of these proteins occurred concomitantly with a rapid decrease in their cytosolic levels and was independent of phorbol ester-sensitive protein kinase C. Within 24 h following LPS stimulation there was a striking increase in the levels of c-Rel, p105, and p50 in the cytosol. The increased levels of these proteins correlated with increases in the amounts of their mRNAs during LPS activation of THP-1 cells. LPS activation of THP-1 cells resulted in phosphorylation of MAD3 (an I kappa B-like protein), a rapid increase in MAD3 mRNA, and an increase in MAD3 protein by 2 h. Thus, LPS activation of human monocytic cells results in nuclear expression of c-Rel/p50 and p50/p65 (NF-kappa B) and induces phosphorylation of MAD3.
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PMID:Lipopolysaccharide induces phosphorylation of MAD3 and activation of c-Rel and related NF-kappa B proteins in human monocytic THP-1 cells. 850 9


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