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)

ADP-ribosyltransferase activity was shown to be present on the surface of human monocytes. Incubating the cells in the presence of BSA leads to an increase in enzyme activity. The acceptor amino acid mainly responsible for the ADP-ribose bond was identified as a cysteine residue. An increase in ADP-ribosyltransferase activity was observed when cells were treated for 16 h with bacterial lipopolysaccharide (LPS). Possible candidates for catalysing the reaction are mono-ADP-ribosyltransferases (ARTs). When measuring expression of the mRNA of ART1, 3, 4 and 5, only ART3 mRNA was detected in unstimulated monocytes. Upon stimulation for 16 h with LPS, lipoteichoic acid or peptidoglycan, ART4 mRNA was found to be expressed. No ART4 signal appeared after a 4 h exposure of the cells to LPS. Cell-surface proteins were labelled when incubating monocytes with [(32)P]NAD(+). Their molecular masses were 29, 33, 43, 45, 60 and 82 kDa. In response to LPS an additional protein of 31 kDa was found to be labelled. The bound label was resistant to treatment with NH(2)OH but sensitive to HgCl(2), characteristic of a cysteine-linked ADP-ribosylation.
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PMID:Mono-ADP-ribosyltransferases in human monocytes: regulation by lipopolysaccharide. 1187

Mammalian poly(ADP-ribose)polymerase 1 (PARP-1) is an abundant nuclear chromatin-associated protein and belongs to a large family of enzymes that catalyzes the transfer of ADP-ribose units from its substrate beta-nicotinamide adenine dinucleotide (NAD+) covalently to itself and other nuclear chromatin-associated proteins. PARP-1 knockout mice are protected against myocardial infarction, streptozotocin-induced diabetes, lipopolysaccharide-induced septic shock, and zymosan-induced multiple organ failure, indicating that PARP-1 is involved in the regulation of the pathogenesis of these disorders. PARP-1 and nuclear factor kappa B (NF-kappaB) have both been suggested to play a crucial role in inflammatory disorders. NF-kappaB encompasses a family of inducible transcription factors which play a crucial role in the regulation of genes involved in immune and inflammatory responses. Recent reports have shown that PARP-1 can act as a coactivator of NF-kappaB. These findings might provide new insights into the pathophysiology of different diseases such as type I diabetes and septic shock. The purpose of this review is to give a short overview of the current knowledge about PARP-1 and its functional and biochemical interactions with NF-kappaB. A more precise role for PARP-1 in NF-kappaB-dependent gene regulation and cellular metabolism during development of pathophysiological processes is discussed. Special considerations is given to the pathophysiological significance of these findings in terms of inflammatory disorders.
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PMID:The functional role of poly(ADP-ribose)polymerase 1 as novel coactivator of NF-kappaB in inflammatory disorders. 1244 Jul 74

Plesiomonas shigelloides is a ubiquitous waterborne pathogen responsible for diseases such as diarrhea and bacillary dysentery, commonly afflicting infants and children. This bacterium is endowed with an O-antigen gene cluster consisting of 10 consecutive reading frames. One of these, designated wbgU (orf3), has been overexpressed and biochemically characterized to show that it encodes a uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) C4 epimerase, only the second microbial enzyme characterized to have this activity. Epimerization is an equilibrium reaction resulting in a 70:30 ratio of UDP-GlcNAc to uridine diphosphate-N-acetylgalactosamine (UDP-GalNAc), irrespective of the initial substrate. The K(m) values for UDP-GalNAc and UDP-GlcNAc are 131 microM and 137 microM, respectively. WbgU is also capable of converting nonacetylated derivatives but with much lower efficiency. It contains a tightly bound nicotinamide adenine dinucleotide [NAD(H)] molecule and requires no other cofactors for activity. We propose here that this enzyme catalyzes the first of the three transformations in the biosynthetic pathway of 2-acetamino-2-deoxy-L-altruronic acid, an unusual sugar present in the O-specific side chains of lipopolysaccharide of P. shigelloides O17 and its close relative Escherichia coli Sonnei.
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PMID:New UDP-GlcNAc C4 epimerase involved in the biosynthesis of 2-acetamino-2-deoxy-L-altruronic acid in the O-antigen repeating units of Plesiomonas shigelloides O17. 1248 81

The rate of oxygen consumption by certain tissues is impaired when mice or rats are injected with lipopolysaccharide. A similar change in the rate of oxygen consumption is observed when Caco-2 human enterocyte-like cells are incubated in vitro with cytomix, a cocktail of cytokines containing tumor necrosis factor, IL-1beta, and IFN-gamma. The decrease in the rate of oxygen consumption is not due to a change in oxygen delivery (e.g. on the basis of diminished microvascular perfusion), but rather to an acquired intrinsic defect in cellular respiration, a phenomenon that we have termed 'cytopathic hypoxia'. A number of different biochemical mechanisms have been postulated to account for cytopathic hypoxia in sepsis, including reversible inhibition of cytochrome a,a3 by nitric oxide, and irreversible inhibition of one or more mitochondrial respiratory complexes by peroxynitrite. Recently, however, our laboratory has obtained data to suggest that the most important mechanism underlying the development of cytopathic hypoxia is depletion of cellular stores of nicotinamide adenine dinucleotide (NAD+/NADH) as a result of activation of the enzyme, poly(ADP-ribose) polymerase-1. If cytopathic hypoxia is important in the pathophysiology of established sepsis and multiorgan dysfunction syndrome, then efforts in the future will need to focus on pharmacological interventions designed to preserve normal mitochondrial function and energy production in sepsis.
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PMID:Bench-to-bedside review: Cytopathic hypoxia. 1249 70

Identification and use of effective cancer chemopreventive agents have become an important issue in public health-related research. For identification of potential cancer chemopreventive constituents we have set up a battery of cell- and enzyme-based in vitro marker systems relevant for prevention of carcinogenesis in vivo. These systems include modulation of drug metabolism (inhibition of Cyp1A activity, induction of NAD(P)H:quinone reductase (QR) activity in Hepa1c1c7 murine hepatoma cell culture), determination of radical scavenging (DPPH scavenging) and antioxidant effects (scavenging of superoxide anion-, hydroxyl- and peroxyl-radicals), anti-inflammatory mechanisms (inhibition of lipopolysaccharide (LPS)-mediated nitric oxide (NO) generation by inducible NO synthase (iNOS) in Raw 264.7 murine macrophages, cyclooxygenase-1 (Cox-1) inhibition), and anti-tumor promoting activities (inhibition of phorbol ester-induced ornithine decarboxylase (ODC) activity in 308 murine keratinocytes). We have tested a series of known chemopreventive substances belonging to several structural classes as reference compounds for the identification of novel chemopreventive agents or mechanisms. These include organosulfur compounds (phenethylisothiocyanate (PEITC), diallylsulfide, diallyldisulfide), terpenes (limonene, perillyl alcohol, oleanolic acid, 18-beta-glycyrrhetinic acid), short-chain fatty acids (sodium butyrate), indoles (indole-3-carbinol), isoflavonoids (quercetin, silymarin, genistein), catechins ((-)-epigallocatechin gallate (EGCG)), simple phenols (ellagic acid, resveratrol, piceatannol, curcumin), pharmaceutical agents (piroxicam, acetylsalicylic acid, tamoxifen), and vitamins/derivatives (ascorbic acid, Trolox). We confirmed known chemopreventive mechanisms of these compounds. Additionally, we could demonstrate the usefulness of our approach by identification of hitherto unknown mechanisms of selected agents. As an example, we detected anti-inflammatory properties of PEITC, based on NF-kappaB-mediated inhibition of NO production. Further, PEITC inhibited phorbol ester-induced superoxide anion radical production in granulocytes, and ODC induction in the 308 cell line. These mechanisms might contribute to the chemopreventive potential of PEITC.
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PMID:Mechanism-based in vitro screening of potential cancer chemopreventive agents. 1262 14

Cyclic ADP-ribose (cADPR), a universal calcium mobilizer from intracellular stores, was recently demonstrated to stimulate proliferation of various cell types. The role of cADPR in a specific process of monocyte- and plasma-mediated activation of T-lymphocytes by lipopolysaccharide (LPS) was addressed using human mononuclear cells from peripheral blood (PBMCs). Incubation of PBMCs with 0.1 microg/ml of LPS for 24 h provided a doubling in the intracellular levels of cADPR as compared with unstimulated PBMCs. The cADPR increase was abolished either by prior removal of monocytes or by pre-incubating a whole PBMC population with a monoclonal antibody against the monocyte marker CD14. The increased concentrations of intracellular cADPR elicited by LPS stimulation were paralleled by significant increases in NAD+ levels and in the activities of ectocellular and membrane-bound fractions of ADP-ribosyl cyclase/cADPR hydrolase activities. A cytosolic ADP-ribosyl cyclase was also detectable in PBMCs and its activity was comparably enhanced by LPS stimulation. This soluble cyclase is distinguished from the membrane-bound cyclase by both substrate and inhibitor sensitivities. LPS-stimulated PBMCs showed 2-3-fold increases of intracellular calcium ([Ca2+]i), and these changes were prevented completely by the cADPR antagonist 8-Br-cADPR and by ryanodine. Both compounds, and the cyclase inhibitor nicotinamide, significantly inhibited the T-lymphocyte proliferation induced by LPS in PBMCs. These results demonstrate that cADPR plays a role of second messenger in the adaptive immune recognition process of LPS-stimulated proliferation of PBMCs.
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PMID:Cyclic ADP-ribose is a second messenger in the lipopolysaccharide-stimulated proliferation of human peripheral blood mononuclear cells. 1285 85

In the course of other experiments, we serendipitously observed that extracellular nicotinamide adenine dinucleotide (NAD+) ameliorated the development of epithelial hyperpermeability when monolayers of Caco-2 enterocyte-like cells were incubated with cytomix, a mixture containing interferon-gamma, interleukin-1beta, and tumor necrosis factor-alpha. We sought to characterize the effects of NAD+ on inflammation-induced epithelial barrier dysfunction using Caco-2 monolayers that were exposed to cytomix in the absence or presence of NAD+ or other purine-containing molecules. Paracellular barrier function measured as the apical-to-basolateral passage of fluorescein isothiocyanate-conjugated dextran (mol. wt. approximately 4000) was preserved in a concentration-dependent manner when immunostimulated Caco-2 cells were exposed to extracellular NAD+. Incubation with NAD+ prevented cytomix-induced derangements in the expression and localization of the tight junction proteins occludin and zonula occludens-1 in Caco-2 cells. Treatment of cytomix-stimulated cells with NAD+ also blocked nuclear factor-kappaB (NF-kappaB) activation, inducible nitric-oxide synthase induction, and increased production of nitric oxide (NO.). Ileal mucosal permeability to fluorescein isothiocyanate-dextran mol. wt. approximately 4000 was increased in mice 18 h after lipopolysaccharide (endotoxin) injection, but treatment of endotoxemic mice with NAD+ ameliorated the development of gut mucosal hyperpermeability. Thus, extracellular NAD+ seems to ameliorate inflammation-induced intestinal epithelial barrier dysfunction by inhibiting NF-kappaB activation and increased NO. production.
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PMID:NAD+ ameliorates inflammation-induced epithelial barrier dysfunction in cultured enterocytes and mouse ileal mucosa. 1297 82

The O antigen of lipopolysaccharide in Gram-negative bacteria plays a critical role in bacterium-host interactions, and for pathogenic bacteria it is a major virulence factor. In Pseudomonas aeruginosa serotype O6 one of the initial steps in O-antigen biosynthesis is catalyzed by a saccharide epimerase, WbpP. WbpP is a member of the UDP-hexose 4-epimerase family of enzymes and exists as a homo-dimer. This enzyme preferentially catalyzes the conversion between UDP-GlcNAc and UDPGalNAc above UDP-Glc and UDP-Gal, using NAD(+) as a cofactor. The crystal structures of WbpP in complex with cofactor and either UDP-Glc or UDP-GalNAc were determined at 2.5 and 2.1 A, respectively, which represents the first structural studies of a genuine UDP-GlcNAc 4-epimerase. These structures in combination with complementary mutagenesis studies suggest that the basis for the differential substrate specificity of WbpP is a consequence of the presence of a pliable solvent network in the active site. This information allows for a comprehensive analysis of the relationship between sequence and substrate specificity for UDP-hexose 4-epimerases and enables the formulation of consensus sequences that predict substrate specificity of UDP-hexose 4-epimerases yet to be biochemically characterized. Furthermore, the examination indicates that as little as one residue can dictate substrate specificity. Nonetheless, phylogenetic analysis suggests that this substrate specificity is an evolutionary and highly conserved property within UDP-hexose 4-epimerases.
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PMID:Crystal structure of WbpP, a genuine UDP-N-acetylglucosamine 4-epimerase from Pseudomonas aeruginosa: substrate specificity in udp-hexose 4-epimerases. 1501 16

Synthesis of ADP-ribose polymers catalyzed by poly-(ADP-ribose) polymerase-1 (PARP-1) has been implicated in transcriptional regulation. Recent studies with PARP-1 null mice and PARP-1 inhibitors have also demonstrated that PARP-1 has an essential role in nuclear factor-kappaB (NF-kappaB)-dependent gene expression induced by various inflammatory stimuli. In this study, we used primary cultured mouse glial cells to investigate the role of poly(ADP-ribosyl)ation by PARP-1 in NF-kappaB-dependent gene expression. PARP-1 inhibitors and the antisense RNA for PARP-1 mRNA suppressed lipopolysaccharide (LPS)-induced expression of tumor necrosis factor-alpha and inducible nitric-oxide synthase, suggesting that PARP-1 activity has a critical role in synthesis. Western blotting with anti-poly(ADP-ribose) antibody revealed that PARP-1 itself was mainly poly(ADP-ribosyl)ated in glial cells, i.e. automodified PARP-1 (AM-PARP). The amounts of AM-PARP were not affected by LPS treatment, but were decreased by PARP-1 inhibitors. Electrophoretic mobility shift assay revealed that PARP-1 inhibitors and the antisense RNA for PARP-1 mRNA reduced the LPS-induced DNA binding of NF-kappaB. Non-modified PARP-1 also reduced the DNA binding of NF-kappaB via its physical association with NF-kappaB, whereas AM-PARP had no effect. On the other hand, enhancement of the automodification of PARP-1 by the addition of NAD+, its substrate, promoted the DNA binding of NF-kappaB. Furthermore, in in vitro transcription assay, the addition of AM-PARP or NAD+ to nuclear extracts promoted NF-kappaB p50-dependent transcription. These results indicate that automodification of PARP-1 positively up-regulates formation of the NF-kappaB.DNA complex and enhances transcriptional activation. Therefore, AM-PARP may be critical for the NF-kappaB-dependent gene expression of some inflammatory mediators in glial cells.
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PMID:Critical role of the automodification of poly(ADP-ribose) polymerase-1 in nuclear factor-kappaB-dependent gene expression in primary cultured mouse glial cells. 1530 69

The inducible nitric oxide synthase (iNOS) plays an important role in endotoxic shock. However,little is known about the involvment of constitutive isoform(s) of NOS (cNOS). The aim of this study was to determine the role of cNOS in the mouse brain after lipopolysaccharide (LPS) injection. Concentrations of nicotinamide adenine dinucleotide (NAD(+)), carbonyl group and thiobarbituric acid reactive substances were determined spectrophotometrically, cNOS mRNA was evaluated by RT-PCR. Our data showed that LPS significantly decreased NAD(+) level, and enhanced protein and lipid oxidation, but had no effect on cNOS mRNA expression. Inhibitors of cNOS protected the cells against alterations evoked by LPS, suggesting involvement of cNOS isoforms in pathology.
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PMID:Inhibition of nitric oxide synthase prevents energy failure and oxidative damage evoked in the brain by lipopolysaccharide. 1559 55


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