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

Endotoxin-associated protein (EP) from Salmonella typhi activated murine resident peritoneal macrophages to produce prostaglandin E2 (PGE2). Cells from both endotoxin nonresponder (C3H/HeJ) and the endotoxin responder (C3H/OuJ) mouse strains were activated by EP. This EP-induced prostaglandin E2 production was blocked by the protein kinase C (PKC) inhibitor H-7 as well as the tyrosine kinase inhibitor genistein, suggesting the involvement of both serine and threonine phosphorylation and tyrosine phosphorylation pathways in the activation of resident peritoneal macrophages by EP. Immunoblot analysis using antiphosphoserine and antiphosphothreonine antibodies showed that EP induced the serine and threonine phosphorylation of a 14-kDa protein (p14). This phosphorylation was not induced by phorbol myristic acid or by lipopolysaccharide endotoxin. Inhibitors of PKC, PKA, and PKG did not block the phosphorylation of p14. However, the tyrosine kinase inhibitor piceatannol blocked p14 serine and threonine phosphorylation, suggesting that this phosphorylation is dependent upon and preceded by a tyrosine phosphorylation step.
 ...
PMID:Induction of serine and threonine protein phosphorylation by endotoxin-associated protein in murine resident peritoneal macrophages. 752 47

Nuclear factor kappa B (NF-kappa B), consisting of p50 and p65, is bound to a cytoplasmic retention protein, I kappa B, in a resting state, and the stimulation of cells with a variety of inflammatory stimuli induces the dissociation of NF-kappa B from I kappa B and the nuclear translocation of NF-kappa B, thereby activating several genes involved in inflammatory responses, such as interleukin (IL)-6, IL-8, and tumor necrosis factor alpha. In order to elucidate the precise mechanism of NF-kappa B activation, we have established lipopolysaccharide (LPS)-dependent NF-kappa B activation in a cell-free system using plasma membrane-enriched, cytosol, and nuclear fractions extracted from a human monocytic cell line, THP-1, by disruption with sonication followed by a differential centrifugation. The combination of plasma membrane-enriched fraction and cytosol was sufficient to activate NF-kappa B in a LPS/CD14-dependent manner only in the presence of ATP as judged by the binding of NF-kappa B to the IL-8 gene kappa B site on an electrophoretic mobility shift assay. LPS-dependent NF-kappa B activation was inhibited by protein kinase inhibitors, such as staurosporine, herbimycin A, tyrphostin, and genistein, but not mitogen-activated protein kinase substrate, cGMP-dependent protein kinase, cAMP-dependent protein kinase, protein kinase C, and calmodulin-dependent protein kinase II inhibitory peptides, suggesting that staurosporine-sensitive kinase(s) as well as tyrosine kinase(s) are involved in LPS-mediated NF-kappa B activation. In addition, LPS induced the phosphorylation of I kappa B-alpha, starting at 5 min after the stimulation in a cell-free system. Moreover, the phosphorylation was inhibited by herbimycin A and tyrphostin, but not staurosporine, suggesting that these protein kinase inhibitors act at distinct steps of signal transmission. Establishment of ligand-dependent activation of NF-kappa B in a cell-free system will facilitate identification of protein kinase(s) and its substrate(s) involved in LPS-mediated NF-kappa B activation.
 ...
PMID:Establishment of lipopolysaccharide-dependent nuclear factor kappa B activation in a cell-free system. 787 68

We studied the effects of endotoxin from Escherichia coli (E. coli) on Ca2+ channel activity in PC12 cells using the cell-attached patch clamp technique. Endotoxin (1-100 ng/ml) decreased channel availability (n x Po) to about one third of control values, an effect that required 3.5 +/- 1 min (mean +/- SD; n = 13) to reach steady state. The biophysical properties of the channel, including slope conductance (22 pS; 40 mM Ba2+), voltage dependence of n x Po, and open times (tau 1 = 0.78 ms, tau 2 = 8.9 ms) for the two open states at 0 mV, were not altered. The effect of endotoxin was blocked by polymyxin-B, indicating involvement of the lipid-A moiety of lipopolysaccharide, and by the tyrosine kinase (tk) inhibitor, tyrphostin. The effect of endotoxin was mimicked by 8-bromo-cGMP (100 microM), and was blocked by the inhibitor of cGMP-dependent protein kinase (PKG), H-8, suggesting involvement of the cGMP/PKG pathway. The effect of endotoxin also was blocked by the nitric oxide (NO) synthase inhibitor, NG-monomethyl-L-arginine monoacetate, suggesting involvement of nitric oxide synthase (NOS). The rapidity of the effect of endotoxin on Ca2+ channel activity suggested that constitutive NOS (cNOS) was involved, in accordance with our finding that endotoxin-induced transcriptional induction of NOS, as measured by nitrite production, required > 6 hr. We conclude that early signaling events by endotoxin in PC12 cells involve tk, cNOS, cGMP/PKG, and Ca2+ channels.
 ...
PMID:Early signaling events by endotoxin in PC12 cells: involvement of tyrosine kinase, constitutive nitric oxide synthase, cGMP-dependent protein kinase, and Ca2+ channels. 884 82

The transcription factor Sp1 plays a crucial role in the monocyte-specific expression of CD14, a binding site (or putative receptor) for lipopolysaccharide (LPS) complexes with LPS-binding protein (LBP). By using RAW 264.7 macrophages treated with spectrally pure deep-rough-chemotype hexa-acyl LPS from Escherichia coli D31m4, three inhibitors were found to block the binding activity of transcription factor Sp1, as measured by electrophoretic mobility shift assays. These inhibitors were diphosphoryl lipid A from Rhodobacter sphaeroides (10 microg/ml); the isoquinoline-sulfonamide H-8 (10 and 100 microM), which is thought to be a cGMP-dependent protein kinase inhibitor; and the anti-inflammatory agent dexamethasone (10 microM).
 ...
PMID:Inhibition of lipopolysaccharide-induced transcription factor Sp1 binding by spectrally pure diphosphoryl lipid A from Rhodobacter sphaeroides, protein kinase inhibitor H-8, and dexamethasone. 912 41

To investigate the mechanisms by which lipopolysaccharide (LPS) affects Ca2+ signaling systems, we studied the effects of LPS on the serotonin (5-HT)- or thrombin-induced intracellular Ca2+ ([Ca2+]i) increase in rat C6 glioma cells. Pretreatment of the cells with 1 microg/ml LPS for 24 hr significantly inhibited [Ca2+]i increase induced by 10 microM 5-HT- or 0.5 U/ml thrombin. Its inhibitory effects were both dose- and time-dependent. Treatment with 1 mM dibutyryl cGMP (dbcGMP) for 30 min also significantly inhibited the 5-HT- and thrombin-induced [Ca2+]i increase to approximately 60-70% of control. However, simultaneous pretreatment with LPS and dbcGMP did not show any synergistic inhibition. The simultaneous pretreatment with LPS and the potent cGMP-dependent protein kinase (PKG) inhibitors H-8 and KT5823 for 24 hr significantly antagonized the inhibitory effect of LPS. Pretreatment of the cells with 1 microg/ml LPS for 24 hr significantly enhanced cGMP accumulation, while dexamethasone and NMMA (NOS inhibitors) significantly attenuated the LPS-induced enhancement in cGMP accumulation. In addition, pretreatment of the cells with 100 nM dexamethasone for 24 hr significantly suppressed LPS-induced inducible nitric oxide synthase (iNOS; type II NOS, NOS-II) protein expression. These results indicate that LPS may inhibit both 5-HT- and thrombin-induced [Ca2+]i increase via iNOS expression and PKG activation pathway in rat C6 glioma cells.
 ...
PMID:Lipopolysaccharide regulates both serotonin- and thrombin-induced intracellular calcium mobilization in rat C6 glioma cells: possible involvement of nitric oxide synthase-mediated pathway. 951 5

Calcitonin gene-related peptide (CGRP), is produced in dorsal root ganglia (DRG) neurons and released from primary afferent neurons to mediate hemodynamic effects and neurogenic inflammation. In this work, we determined whether lipopolysaccharide (LPS), an inflammatory stimulator, could trigger CGRP release from cultured DRG neurons and if so, which cellular signaling pathway was involved in this response. Cytoplasmic concentration of calcium ([Ca(2+)](i)) plays a key role in neurotransmitter release, therefore [Ca(2+)](i) was also determined in cultured DRG cells using fluo-3/AM. The results showed that LPS (0.1-10 microg/ml) evoked CGRP release in a time- and concentration-dependent manner from DRG neurons. LPS also increased [Ca(2+)](i) in a concentration-dependent manner. The protein kinase C (PKC) inhibitors, calphostin C 0.5 microM or RO-31-8220 0.1 microM, and the cAMP-dependent protein kinase (PKA) specific inhibitor RP-CAMPS 30 microM or nonspecific inhibitor H8 1 microM inhibited 1 microg/ml LPS-evoked CGRP release and [Ca(2+)](i) increase from DRG neurons. The cGMP-dependent protein kinase (PKG) inhibitor Rp-8-pCPT-cGMPS 30 microM did not block the LPS response. These data suggest that LPS may stimulate CGRP release and [Ca(2+)](i) elevation through PKC and PKA, but not PKG signaling pathway in DRG neurons of neonatal rats.
 ...
PMID:PKC and PKA, but not PKG mediate LPS-induced CGRP release and [Ca(2+)](i) elevation in DRG neurons of neonatal rats. 1174 79

Nitric oxide (NO) induced by bacterial lipopolysaccharide (LPS) plays a critical role in various patho-physiological implications, such as atherosclerosis, vasculitis and septic shock. In addition, cAMP-responsive element binding protein (CREB), an important transcription factor for cell differentiation, has been shown to be involved in atherosclerogenesis in VSMCs. Here we investigated the possibility whether LPS-induced NO signaling led to phosphorylation of cAMP-responsive element binding protein on Serine-133 (CREBSer-133) in cultured vascular smooth muscle cells (VSMCs) from rats. Addition of LPS (1-10 microg/ml) for 48 hours increased not only the production NO, but also the phosphorylation of CREBSer-133. The use of NOS inhibitor (100-500 microM L-NAME) blocked the magnitudes of both LPS-induced NO production and CREBSer-133 phosphorylation. In addition, either a guanylyl cyclase (GC) inhibitor (30 microM ODQ) or a cGMP-dependent protein kinase (PKG) inhibitor (20 microM (Rp)-8-pCPT-cGMPs) significantly attenuated the magnitudes of LPS-induced CREBSer-133 phosphorylation, suggesting the involvement of NO-GC-PKG signaling. Thus, the present study suggests that NO-mediated signaling activated by bacterial LPS, at least in part, enhance CREBSer-133 phosphorylation in cultured VSMCs. The findings here may provide not only signaling pathway involved in VSMC differentiation during inflammatory response, but also new insight into possible therapeutic intervention.
 ...
PMID:Enhancement of CREBSerine-133 phosphorylation through nitric oxide-mediated signaling induced by bacterial lipopolysaccharide in vascular smooth muscle cells from rats. 1281 20

The endothelial cells (EC) of the microvasculature in the brain form the anatomical basis of the blood-brain barrier (BBB). In the present study, the effects of agents that modify the permeability of a well-established in vitro model of the human BBB were studied. The monolayers formed by confluent human brain microvessel endothelial cell (HBMEC) cultures are impermeable to the macromolecule tracer horseradish peroxidase (HRP) and have high electrical resistance. Exposure of HBMEC to various cytokines including TNF-alpha, IL-1beta, interferon gamma (IFN-gamma), or lipopolysaccharide (LPS) decreased transendothelial electrical resistance (TEER) mainly by increasing the permeability of the tight junctions. Primary cultures of HBMEC express endothelial nitric oxide synthase (eNOS) and produce low levels of NO. Treatment with the NO donors sodium nitroprusside (SNP) and DETA NONOate or the cGMP agonist 8-Br-cGMP significantly increased monolayer resistance. Conversely, inhibition of soluble guanylyl cyclase with ODQ rapidly decreased the resistance, and pretreatment of HBMEC with Rp-8-CPT-cGMPS, an inhibitor of cGMP-dependent protein kinase, partially prevented the 8-Br-cGMP-induced increase in resistance. Furthermore, NO donors and 8-Br-cGMP could also reverse the increased permeability of the monolayers induced by IL-1beta, IFN-gamma, and LPS. These results indicate that NO can decrease the permeability of the human BBB through a mechanism at least partly dependent on cGMP production and cGMP-dependent protein kinase activation.
 ...
PMID:Cytokines, nitric oxide, and cGMP modulate the permeability of an in vitro model of the human blood-brain barrier. 1553 Aug 83

Increased expression of CD11b, the beta-integrin marker of microglia, represents microglial activation during neurodegenerative inflammation. However, the molecular mechanism behind increased microglial CD11b expression is poorly understood. The present study was undertaken to explore the role of nitric oxide (NO) in the expression of CD11b in microglial cells. Bacterial lipopolysaccharide (LPS) induced the production of NO and increased the expression of CD11b in mouse BV-2 microglial cells and primary microglia. Either a scavenger of NO (PTIO) or an inhibitor of inducible nitric-oxide synthase (L-NIL) blocked this increase in microglial CD11b expression. Furthermore, co-microinjection of PTIO with LPS was also able to suppress LPS-mediated expression of CD11b and loss of dopaminergic neuronal fibers and neurotransmitters in striatum in vivo. Similarly, other inducers of NO production such as interferon-gamma, interleukin-1beta, human immunodeficiency virus type-1 gp120, and double-stranded RNA (poly(IC)) also increased the expression of CD11b in microglia through NO. The role of NO in the expression of CD11b was corroborated further by the expression of microglial CD11b by GSNO, an NO donor. Because NO transduces many intracellular signals via guanylate cyclase (GC), we investigated the role of GC, cyclic GMP (cGMP), and cGMP-activated protein kinase (PKG) in microglial expression of CD11b. Inhibition of LPS- and GSNO-mediated up-regulation of CD11b either by NS2028 (a specific inhibitor of GC) or by KT5823 and Rp-8-bromo-cGMP (specific inhibitors of PKG), and increase in CD11b expression either by 8-bromo-cGMP or by MY-5445 (a specific inhibitor of cGMP phosphodiesterase) alone suggest that NO increases microglial expression of CD11b via GC-cGMP-PKG. In addition, GSNO induced the activation of cAMP response element-binding protein (CREB) via PKG that was involved in the up-regulation of CD11b. This study illustrates a novel biological role of NO in regulating the expression of CD11b in microglia through GC-cGMP-PKG-CREB pathway that may participate in the pathogenesis of devastating neurodegenerative disorders.
 ...
PMID:Up-regulation of microglial CD11b expression by nitric oxide. 1655 37

Immunologically activated astrocytes over-express matrix metalloproteinase-9 (MMP-9) and nitric oxide (NO). Because they have both beneficial and detrimental effects on the pathophyiological outcomes of several neurological diseases, their expression should be tightly regulated in the CNS. NO can modify the activity of other proteins either by directly modifying protein structure or regulating the expression of target proteins. In this study, we investigated the role of NO on the expression of MMPs in rat primary astrocytes. Rat primary astrocytes were stimulated with lipopolysaccharide (LPS), resulting in the over-expression of both MMP-9 and NO. Inhibition of NO production using nitric oxide synthase inhibitor, Nomega-nitro-l-arginine methyl ester (l-NAME), further increased MMP-9 expression, suggesting NO inhibits MMP-9 expression. In line with this observation, exogenous addition of NO donor, sodium nitroprusside (SNP) or S-nitroso-N-acetylpenicillamine (SNAP), inhibited MMP-9 expression in astrocytes. The inhibitory effect of NO was mediated by the down-regulation of mRNA and protein levels of MMP-9 but not by the direct modification of the enzymatic activity of MMP-9. The effect of NO on MMP-9 expression was mimicked by dibutyryl-cGMP and inhibited by PKG inhibitor KT5823, suggesting NO regulates MMP-9 expression via guanylate cyclase-PKG pathway. Finally, SNP or dibutyryl-cGMP inhibited the activation of ERK1/2 in LPS-stimulated astrocytes, which is an essential regulator of MMP-9 expression in astrocytes. The regulation of MMP-9 expression by NO may confer additional levels of fine-tuning of the level of MMP-9 during brain inflammatory conditions.
 ...
PMID:Down-regulation of matrix metalloproteinase-9 expression by nitric oxide in lipopolysaccharide-stimulated rat primary astrocytes. 1745 15


1 2 Next >>