UNIPROT:P43026 - FACTA Search

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Query: UNIPROT:P43026 (lipopolysaccharide)
62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Matrix-bound fibronectin (FN) appears to be involved in cell adhesion and motility mediated by integrin receptors. Although lymphoid cells and other cell types are capable of producing and secreting FN, the precise role of this secreted FN-like factor in regulating immune reactions is unclear. In the present study we analyzed the adhesive properties of FN secreted by rat CD4+ T cells and clone cells activated by the T cell mitogen concanavalin A (Con A), antigen, or via the CD2 pathways, or by macrophages (M phi) activated by lipopolysaccharide (LPS). Immobilized culture supernatant (CS) from the activated T cells or M phi supports the adhesion of activated rat or human CD4+ T cell or murine tumor cell. These CS contained FN and were more potent at facilitating cell adhesion then plasma FN. The adhesion activity of CS was attributed to FN because (a) gelatin columns depleted the FN present in the CS and (b) pretreating the cells with peptides of the cell-binding domain of FN abrogated their ability to bind CS. CS-mediated adhesion appears to occur primarily via the recognition of the Arg-Gly-Asp (RGD) by the beta 1-integrin-specific receptors of the adhesive cells. Thus, we postulate that FN secreted by various types of leukocytes is involved in promoting essential cell-matrix interactions, possibly affecting cell-adhesive and migratory processes at inflammatory or extravasation sites.
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PMID:Activated T lymphocytes and macrophages secrete fibronectin which strongly supports cell adhesion. 157 55

We investigated the relationship of polymorphonuclear leukocyte (PMN) candicidal activity, matrix proteins, and lipopolysaccharide (LPS) to determine how LPS modulates the normal enhancing effect of matrix proteins on PMN candicidal activity. LPS reduced PMN candicidal activity when PMN were adhered in the presence of either fibronectin or laminin. In the presence of fibronectin or laminin, LPS reduced CD11b/CD18 expression (the fibronectin receptor) as assessed using sheep erythrocytes coated with C3bi. Experiments with 125I-fibronectin and 125I-RGDS (Arg-Gly-Asp-Ser) demonstrated that LPS reduced both the binding of fibronectin and the bioavailability of the binding epitope on the PMN surface. Stimulating the PMN oxidative burst with PMA but not FMLP also reduced fibronectin and RGDS binding. Incubation of LPS-treated PMN with staurosporine blocked the decrease in fibronectin and RGDS binding. Exposure of PMN to LPS plus low-dose TNF-alpha restored both fibronectin and RGDS binding with a concomitant increase in CD11b/CD18 surface expression. Low-dose TNF-alpha restored PMN candicidal activity in the presence of LPS and was most effective if PMN were preadhered to fibronectin. These results demonstrate that: (1) matrix proteins enhance normal PMN candicidal activity, (2) LPS reduces PMN candicidal activity in the presence of matrix proteins, (3) stimulation of the PMN oxidative burst in particular via protein kinase c activation reduces the bioavailability of the fibronectin receptor, and (4) low-dose TNF-alpha may restore PMN candicidal activity in part by upregulating the surface receptor for fibronectin binding.
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PMID:Endotoxin suppresses matrix protein-induced upregulation of PMN candicidal activity: an effect reversed by low-dose TNF-alpha. 161 18

This study shows that stimulating bone marrow-derived macrophages with either lipopolysaccharide (LPS) or the lipopeptide N-palmitoyl-S-(2,3-bis(palmitoyloxy)-(2RS)-propyl)-(R)- cysteinyl-alanyl-glycine (Pam3Cys-Ala-Gly), a synthetic analogue of the N-terminal part of bacterial lipoprotein, leads to the formation of nitric oxide (NO) and nitrite (NO2-), a stable analogue of NO. NO was detected by applying the chemiluminescence method and by measuring the activity of exogenously added soluble guanylate cyclase (GC), which is strongly and selectively activated by NO. Synthesis of NO and NO2- occurs via activation of the L-arginine and NADPH-dependent enzyme(s) present in the cytosol of bone marrow-derived macrophages. No produced by this non-constitutive L-arginine pathway is thought to be responsible for the cytostatic and killing properties of macrophages (Stuehr & Nathan, 1989). Macrophages stimulated either with LPS or Pam3Cys-Ala-Gly exhibited a 6-hr lag time before engaging in nitrite synthesis, a time at which expression of the NO-forming enzyme had already reached its maximum. The regulation of NO and NO2- synthesis during macrophage development seems to differ from that of cytokine synthesis. Whereas cytokine release varies during a culture period up to 20 days, NO synthesis and expression of the NO-forming enzyme remain unaltered. These studies show that, similar to LPS, Pam3Cys-Ala-Gly is a potent activator of 'the oxidative L-arginine pathway' in bone marrow-derived macrophages. Whether both stimuli use the same signal transfer mechanism to induce this pathway and whether NO synthesized by this pathway is involved in the activation of the enzyme guanylate cyclase in macrophages requires clarification.
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PMID:L-arginine-dependent nitric oxide formation and nitrite release in bone marrow-derived macrophages stimulated with bacterial lipopeptide and lipopolysaccharide. 197 43

Fibronectin (Fn), an extracellular matrix glycoprotein with binding sites for collagen, fibrin, heparin, and cell surfaces, is a nonimmune opsonin which up-regulates phagocytic function and facilitates adherence of human monocytes. We have developed a simple assay to study adherence of peripheral blood monocytes to Fn on a gelatin matrix. While cell adherence was enhanced by the presence of Fn in a dose-dependent manner, it was inhibited by peptides containing the Arg-Gly-Asp (RGD) cell attachment sequence or by coating the matrix with antibodies directed against Fn. Preincubation of monocytes for 30 min with Escherichia coli lipopolysaccharide (LPS) at doses of 1-50 micrograms/ml increased adherence to Fn-gelatin but not to gelatin alone, while longer preincubation (24 hr) resulted in similar changes at lower doses (0.01-1.0 micrograms/ml). Enhanced Fn adherence may be essential for monocyte localization to sites of inflammation.
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PMID:Lipopolysaccharide enhances monocyte adherence to matrix-bound fibronectin. 214 32

Upon exposure to the bacterial chemotactic peptide fMet-Leu-Phe, human neutrophils release lysozyme and generate superoxide anions (O2.-). The synthetic lipoamino acid N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-(R)-cysteine (Pam3Cys), which is derived from the N-terminus of bacterial lipoprotein, when attached to Ser-(Lys)4 [giving Pam3Cys-Ser-(Lys)4], activated O2.- formation and lysozyme release in human neutrophils with an effectiveness amounting to about 15% of that of fMet-Leu-Phe. Palmitic acid, muramyl dipeptide, lipopolysaccharide and the lipopeptides Pam3Cys-Ala-Gly, Pam3Cys-Ser-Gly, Pam3Cys-Ser, Pam3Cys-OMe and Pam3Cys-OH did not activate O2.- formation. Pertussis toxin, which ADP-ribosylates guanine-nucleotide-binding proteins (G-proteins) and functionally uncouples formyl peptide receptors from G-proteins, prevented activation of O2.- formation by fMet-Leu-Phe and inhibited Pam3Cys-Ser-(Lys)4-induced O2.- formation by 85%. Lipopeptide-induced exocytosis was pertussis-toxin-insensitive. O2.- formation induced by Pam3Cys-Ser-(Lys)4 and fMet-Leu-Phe was enhanced by cytochalasin B, by a phorbol ester and by a diacylglycerol kinase inhibitor. Addition of activators of adenylate cyclase and removal of extracellular Ca2+ inhibited O2.- formation by fMet-Leu-Phe and Pam3Cys-Ser-(Lys)4 to different extents. Pam3Cys-Ser-(Lys)4 synergistically enhanced fMet-Leu-Phe-induced O2.- formation and primed neutrophils to respond to the chemotactic peptide at non-stimulatory concentrations. Our data suggest the following. (1) Pam3Cys-Ser-(Lys)4 activates neutrophils through G-proteins, involving pertussis-toxin-sensitive and -insensitive processes. (2) The signal transduction pathways activated by fMet-Leu-Phe and Pam3Cys-Ser-(Lys)4 are similar but not identical. (3) In inflammatory processes, bacterial lipoproteins and chemotactic peptides may interact synergistically to activate O2.- formation, leading to enhanced bactericidal activity.
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PMID:Activation of superoxide formation and lysozyme release in human neutrophils by the synthetic lipopeptide Pam3Cys-Ser-(Lys)4. Involvement of guanine-nucleotide-binding proteins and synergism with chemotactic peptides. 216 Feb 37

The studies reported here probe the existence of a receptor-mediated mode of fibrin-binding by macrophages that is associated with the chemical change underlying the fibrinogen-fibrin conversion (the release of fibrinopeptides from the amino-terminal domain) without depending on fibrin-aggregation. The question is pursued by 1) characterization of binding in relation to fibrinopeptide content of both the intact protein and the CNBr-fragment comprising the amino-terminal domain known as the NDSK of the protein, 2) tests of competition for binding sites, and 3) photo-affinity labeling of macrophage surface proteins. The binding of intact monomers of types lacking either fibrinopeptide A alone (alpha-fibrin) or both fibrinopeptides A and B (alpha beta-fibrin) by peritoneal macrophages is characterized as proceeding through both a fibrin-specific low density/high affinity (BMAX congruent 200-800 molecules/cell, KD congruent to 10(-12) M) interaction that is not duplicated with fibrinogen, and a non-specific high density/low affinity (BMAX greater than or equal to 10(5) molecules/cell, KD greater than or equal to 10(-6) M) interaction equivalent to the weak binding of fibrinogen. Similar binding characteristics are displayed by monocyte/macrophage cell lines (J774A.1 and U937) as well as peritoneal macrophages towards the NDSK preparations of these proteins, except for a slightly weaker (KD congruent to 10(-10) M) high-affinity binding. The high affinity binding of intact monomer is inhibitable by fibrin-NDSK, but not fibrinogen-NDSK. This binding appears principally dependent on release of fibrinopeptide-A, because a species of fibrin (beta-fibrin) lacking fibrinopeptide-B alone undergoes only weak binding similar to that of fibrinogen. Synthetic Gly-Pro-Arg and Gly-His-Arg-Pro corresponding to the N-termini of to the alpha- and the beta-chains of fibrin both inhibit the high affinity binding of the fibrin-NDSKs, and the cell-adhesion peptide Arg-Gly-Asp does not. Photoaffinity-labeling experiments indicate that polypeptides with electrophoretically estimated masses of 124 and 187 kDa are the principal membrane components associated with specifically bound fibrin-NDSK. The binding could not be up-regulated with either phorbol myristyl acetate, interferon gamma or ADP, but was abolished by EDTA and by lipopolysaccharide. Because of the low BMAX, it is suggested that the high-affinity mode of binding characterized here would be too limited to function by itself in scavenging much fibrin, but may act cooperatively with other, less limited modes of fibrin binding.
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PMID:Characterization of a mode of specific binding of fibrin monomer through its amino-terminal domain by macrophages and macrophage cell-lines. 216 52

The cDNA encoding the murine low-affinity receptor for IgE (Fc epsilon RII) has been isolated from a cDNA library prepared from B cells activated with lipopolysaccharide and interleukin 4. It encodes a 37-kDa protein of 331 amino acids with two potential N-linked glycosylation sites. Analogous to its human counterpart, there is no signal sequence and the putative transmembrane region is close to the amino terminus, indicating an inverse membrane orientation with the carboxyl terminus at the cell exterior. The predicted murine Fc epsilon RII amino acid sequence demonstrates a 57% identity with its human counterpart. The murine sequence has an additional internal repeat motif of 21 amino acids giving four repeats as compared to three in the human sequence. Furthermore, the murine Fc epsilon RII is truncated at the carboxyl terminus and the Arg-Gly-Asp sequence, a common recognition site of integrin receptors, which is found in the reverse configuration in human Fc epsilon RII, is missing. B cells activated with interleukin 4 and lipopolysaccharide have an increased amount of Fc epsilon RII mRNA as compared with resting or lipopolysaccharide-stimulated B cells. Con A-activated normal T cells, the TH-2 cell line D10, as well as the macrophage cell line J774 have no detectable Fc epsilon RII mRNA. Expression analysis using transiently transfected COS cells revealed that recombinant murine Fc epsilon RII binds anti-Fc epsilon RII as well as mouse and rat IgE but does not bind human IgE or mouse IgG. Fc epsilon RII expressed in COS cells has a molecular mass of 45 kDa whereas the Fc epsilon RII from B-cell lines is a 49-kDa protein.
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PMID:Molecular structure and expression of the murine lymphocyte low-affinity receptor for IgE (Fc epsilon RII). 252 42

Conjugation and bacteriophage P1 transduction experiments in Escherichia coli showed that resistance to the antibacterial compound diazaborine is caused by an allelic form of the envM gene. The envM gene from Salmonella typhimurium was cloned and sequenced. It codes for a 27,765-dalton protein. The plasmids carrying this DNA complemented a conditionally lethal envM mutant of E. coli. Recombinant plasmids containing gene envM from a diazaborine-resistant S. typhimurium strain conferred the drug resistance phenotype to susceptible E. coli cells. A guanine-to-adenine exchange in the envM gene changing a Gly codon to a Ser codon was shown to be responsible for the resistance character. Upstream of envM a small gene coding for a 10,445-dalton protein was identified. Incubating a temperature-sensitive E. coli envM mutant at the nonpermissive temperature caused effects on the cells similar to those caused by treatment with diazaborine, i.e., inhibition of fatty acid, phospholipid, and lipopolysaccharide biosynthesis, induction of a 28,000-dalton inner membrane protein, and change in the ratio of the porins OmpC and OmpF.
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PMID:envM genes of Salmonella typhimurium and Escherichia coli. 268 43

Lipoprotein from the outer membrane of Escherichia coli and the synthetically prepared lipopeptides Pam3Cys-Ala-Gly and Pam3Cys-Ser-[Lys]4 derived from the N-terminus of lipoprotein constitute potent macrophage and polyclonal B-lymphocyte activators. The compounds have also been shown to induce tumor cytotoxicity in murine bone marrow-derived macrophages (BMDM). Bone marrow stem cells were cultured in the presence of colony-stimulating factor 1 to yield BMDM of 98 to 99% purity at day 8. After stimulation with the lipopeptides on days 4, 6, 8 and 10 of bone marrow culture, the cytotoxic effect of BMDM on the tumor cell line L929 was determined in a [3H]thymidine release assay. Maximum tumor cytotoxicity was found on day 8 with an optimal effector/target-cell ratio of 10:1, and a duration of lipopeptide stimulation of 4 h. The supernatants of lipopeptide stimulated BMDM also showed cytotoxic activity that could be inhibited by antiserum against tumor necrosis factor alpha. The effects of the lipopeptides Pam3Cys-Ala-Gly and Pam3Cys-Ser-[Lys]4 were comparable or superior to those exerted by lipopolysaccharide. Our results demonstrate that synthetic lipopeptides are potent activators for murine BMDM and may therefore prove to be an important tool for the elucidation of the role of macrophages in the host defence mechanisms against tumor cells.
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PMID:Induction of tumor cytotoxicity in murine bone marrow-derived macrophages by two synthetic lipopeptide analogues. 277 84

Lys-His-Gly-NH2 has been claimed to selectively induce B cell precursors to differentiate into mature B lymphocytes. In the present study, the effects of this tripeptide and a control compound having the reverse sequence (Gly-His-Lys-NH2) on growth and differentiation of chicken and mouse B cell precursors were investigated. When chicken bone marrow (BM) cells from 15-day-old embryos were treated for 18 hr with either of the tripeptides, the frequency of Bu-1 antigen-bearing cells increased. Moreover, when embryonic bursa cells were stimulated in vitro with phorbol myristate acetate, which induces them to proliferate and undergo terminal differentiation into immunoglobulin (Ig)-secreting cells, these compounds caused a 10-fold increase in the number of Ig-secreting cells but did not increase cell proliferation. They had no effect on neonatal or adult bursa cells. Embryonic bursa cells were cultured in the presence of either of the tripeptides and metabolically labeled with [35S]methionine. When immunoprecipitated Ig was analyzed by two-dimensional gel electrophoresis, no differences in mu heavy or lambda light chain diversity patterns could be detected, indicating that neither of these compounds enhances Ig diversification. The effect of these tripeptides on murine B cell precursors was assayed in cultures of BM cells depleted of mature B cells by 5-fluorouracil. When precursor cells were incubated without adherent BM stromal cells, they did not respond to the tripeptides. However, after incubation of precursors with adherent stromal BM cells for 2 days, followed by treatment with either of the two tripeptides, differentiation into lipopolysaccharide-reactive mature B cells took place. Incubation of precursors with adherent stromal BM cells in the absence of tripeptides was not sufficient to allow the precursors to complete differentiation. In addition, both tripeptides acted synergistically with interleukin 1 or interleukin 3. In conclusion, these tripeptides seem to enhance precursor B cell differentiation in a lineage-nonspecific manner rather than to function as lineage-specific differentiation hormones.
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PMID:A role for Lys-His-Gly-NH2 in avian and murine B cell development. 278 13

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