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)

Although the fibrosis observed during chronic liver injury is the result of a complex process, the striking accumulation of collagen in end stage liver disease has provoked interest in the mechanisms that regulate both collagen production and degradation in the diseased liver. The present studies have examined the cell interactions that may be important in the regulation of collagen degradation. Although minimal amounts of interstitial collagenase activity were noted in cultures of normal hepatocytes and sinusoidal cells, the co-cultures of these cells in the presence of lipopolysaccharide showed a substantial increase in collagenase activity. When the hepatocytes were obtained from rats that had been treated with carbon tetrachloride in vivo, the enhanced activity seen in the co-cultures did not require the addition of lipopolysaccharide. Further characterization of this interaction suggested that the increase in collagenolytic activity was partially due to the elaboration of soluble factors by the hepatocyte, which stimulated collagenase production by the sinusoidal cell population. Elaboration of collagenase activity by the sinusoidal cells was inhibited by cycloheximide, suggesting that protein synthesis was required. The proteolytic activity was abrogated by inhibitors of metalloproteinases but not by serine or thiol proteinase inhibitors. The degradation products of type I collagen were typical of the expected products seen with vertebrate collagenases. Thus, it appears that the increased collagenolytic activity detected in this co-culture system is attributable to the production of interstitial collagenase by the sinusoidal cell population. Such cell-cell interactions may play an important role in the maintenance of normal connective tissue structure of the liver during disease processes.
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PMID:Stimulation of interstitial collagenase in co-cultures of rat hepatocytes and sinusoidal cells. 300 4

Mononuclear phagocytes release interleukin-1 (IL-1), a 17-kDa polypeptide with diverse biological activities. IL-1 is synthesized as a precursor (31 kDa) which lacks a signal sequence or hydrophobic domains that could facilitate transmembrane translocation. Possible postsynthetic modifications of IL-1 that might account for its cellular transport were examined. We found that lipopolysaccharide stimulated, but not unstimulated, murine macrophages incorporated 32PO4 into the IL-1 alpha precursor (31 kDa) predominantly at residue serine 90. Released IL-1 alpha (17 kDa) is not phosphorylated in agreement with peptide sequence data that the site of 32P incorporation is in the amino-terminal one-third of the precursor. Approximately 10% of the phosphorylated IL-1 alpha precursor is membrane bound and associated with a fraction enriched in lysosomal vesicles. Together these data suggest mechanisms by which the postsynthetic proteolysis of the IL-1 alpha precursor may be modified and cellular transport of IL-1 alpha is accomplished.
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PMID:The precursor of interleukin-1 alpha is phosphorylated at residue serine 90. 312 84

An intracellular clotting factor, factor C, found in the horseshoe crab hemocytes is a lipopolysaccharide-sensitive serine-protease zymogen, which participates in the initiation of the hemolymph clotting system [T. Nakamura et al. (1986) Eur. J. Biochem. 154, 511-521]. The subsequent study of this zymogen, using various synthetic lipid A analogues, revealed that the zymogen factor C is rapidly activated by acylated (beta 1-6)-D-glucosamine disaccharide bisphosphate (synthetic Escherichia coli-type lipid A), and the corresponding 4'-monophosphate analogues. However, the corresponding non-phosphorylated lipid A did not activate factor C, indicating that a phosphate ester group linked with the (beta 1-6)-D-glucosamine disaccharide backbone is required for the zymogen activation. During these studies we also found that the zymogen factor C is significantly activated by acidic phospholipids, such as phosphatidylinositol, phosphatidylglycerol and cardiolipin, but not at all by neutral phospholipids. The rate of this activation, however, was affected markedly by ionic strength in the reaction mixture, although such an effect was not observed in the lipid-A-mediated activation of factor C. A variety of negatively charged surfaces, such as sulfatide, dextran sulfate and ellagic acid, which are known as typical initiators for activation of the mammalian intrinsic clotting system, did not show any effect on the zymogen factor C activation. These results suggest that lipid A is the most effective trigger to initiate the activation of the horseshoe crab hemolymph clotting system.
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PMID:Intracellular serine-protease zymogen, factor C, from horseshoe crab hemocytes. Its activation by synthetic lipid A analogues and acidic phospholipids. 316 24

Expression of alpha 1 proteinase inhibitor (alpha 1-PI) in human mononuclear phagocytes may provide a local mechanism for inactivation of serine proteases at sites of tissue injury, thereby preventing incidental damage to surrounding tissue and allowing for orderly initiation of repair. We have previously shown that serine (neutrophilic or pancreatic) elastase and lipopolysaccharide (LPS) each mediate an increase in the expression of alpha 1-PI in human peripheral blood monocytes and bronchoalveolar macrophages. In this study we demonstrate that elastase and LPS have an additive positive regulatory effect on alpha 1-PI expression. Distinct pretranslational and translational mechanisms of action for elastase and LPS, respectively, account for the additive effect. The possibility that translational regulation of alpha 1-PI by LPS involves a mechanism analogous to that of the yeast gene GCN4 during amino acid starvation and that of the human ferritin gene in response to iron is discussed.
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PMID:Distinct and additive effects of elastase and endotoxin on expression of alpha 1 proteinase inhibitor in mononuclear phagocytes. 326 70

The horseshoe crab clotting factor, factor C, present in the hemocytes is a serine-protease zymogen activated with lipopolysaccharide. It is a two-chain glycoprotein (Mr = 123,000) composed of a heavy chain (Mr = 80,000) and a light chain (Mr = 43,000) [T. Nakamura et al. (1986) Eur. J. Biochem. 154, 511-521]. In our continued study of this zymogen, we have now also found a single-chain form of factor C (Mr = 123,000) in the hemocyte lysate. The heavy chain had the NH2-terminal sequence of Ser-Gly-Val-Asp-, consistent with that of the single-chain factor C, indicating that the heavy chain is derived from the NH2-terminal part of the molecule. The light chain had an NH2-terminal sequence of Ser-Ser-Gln-Pro-. Incubation of the two-chain zymogen with lipopolysaccharide resulted in the cleavage of a Phe-Ile bond between residues 72 and 73 of the light chain. Concomitant with this cleavage, the A (72 amino acid residues) and B chains derived from the light chain were formed. The complete amino acid sequence of the A chain was determined by automated Edman degradation. The A chain contained a typical segment which is similar in sequence to a family of repeats in human beta 2-glycoprotein I, complement factors B, protein H, C4b-binding protein, and coagulation factor XIII b subunit. The NH2-terminal sequence of the B chain was Ile-Trp-Asn-Gly-. This chain contained the serine-active site sequence-Asp-Ala-Cys-Ser-Gly-Asp-Ser-Gly-Gly-Pro-. These results indicate that horseshoe crab factor C exists in the hemocytes in a single-chain zymogen form and is converted to an active serine protease by hydrolysis of a specific Phe-Ile peptide bond.
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PMID:Lipopolysaccharide-sensitive serine-protease zymogen (factor C) of horseshoe crab hemocytes. Identification and alignment of proteolytic fragments produced during the activation show that it is a novel type of serine protease. 330 57

Cysteine and cystine transport activities of resting and activated mouse spleen lymphocytes were characterized in order to examine the contributions of cysteine and cystine to intracellular glutathione contents. Following stimulation with lipopolysaccharide, the lymphocytes markedly increased their capacity to transport cysteine. The uptake of cysteine was mediated mainly by the ASC system (Na+-dependent neutral amino acid transport system especially reactive with alanine, serine, and cysteine). On the other hand, both the resting and the activated lymphocytes had extremely low cystine transport activities. Because of the instability of cysteine, the culture media usually contained cystine but not cysteine. Therefore, both the resting and the activated lymphocytes rapidly decreased their glutathione contents owing to their poor capacities to take up cystine. The effects of freshly added cysteine on the cellular glutathione contents were examined in the presence of bathocuproinedisulfonate, a nontoxic copper-specific chelator that inhibits autoxidation of cysteine. Cysteine added at 25-400 microM only partially prevented the rapid decrease of the glutathione contents in fresh resting lymphocytes. In the lipopolysaccharide-activated cells, however, cysteine enhanced the cellular glutathione contents in a dose-dependent manner. These results indicate that the enhanced activity of the ASC system increases the level of intracellular glutathione in the presence of cysteine.
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PMID:Regulation of glutathione levels in mouse spleen lymphocytes by transport of cysteine. 368 Mar 92

Factor B, the complement alternative pathway serine proteinase, a class III gene product of the major histocompatibility complex, is a major constitutive secretion product of mouse mononuclear phagocytes. This glycoprotein was synthesized and secreted by macrophages as a doublet of Mr 90,000 and 93,000 polypeptides that were immunoprecipitable with antibodies raised to human serum factor B, and that were indistinguishable from plasma factor B by immunoreactivity, peptide mapping, and molecular weight. Macrophage factor B was cleaved and activated to factor Bb- and Ba-like fragments by factor D and cobra venom factor. Some conversion of macrophage factor B to Bb-sized fragments occurred spontaneously in the conditioned culture medium after several hours. Factor B represented approximately 0.5% of newly synthesized protein and 4-6% of the secreted protein of resident peritoneal macrophages and macrophages elicited with thioglycollate broth, pyran copolymer, NaIO4, bacillus Calmette-Guerin, or Corynebacterium parvum. We detected synthesis of factor B immediately upon explanting these macrophages in culture; synthesis continued for several days in culture. The rate of secretion of factor B, as a proportion of total protein secretion in culture, remained constant with time. By radioimmunoassay, factor B antigens accumulated in the 24-h macrophage-conditioned culture medium at 2-10 nM, and was present in cell lysates at 4-8 nmol per 10(6) cells. We detected synthesis of factor B in bone marrow-derived macrophages as early as 5 d of culture. The P388D1 macrophage line synthesized factor B, but mouse L cells did not. In contrast, apolipoprotein E, another secreted protein of macrophages, was secreted by resident and thioglycollate-elicited macrophages but not by freshly harvested pyran copolymer-activated macrophages. Its synthesis was initiated at day 9 in culture of bone marrow-derived macrophages. These data support the classification of factor B as a constitutive biosynthetic and secreted protein of immature and mature macrophages in various states of activation. Production of factor B was modulated by treatment of macrophages in vivo or in culture with bacterial lipopolysaccharide endotoxin, which increased the synthesis, secretion, and accumulation of factor B up to 11-fold.
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PMID:Factor B, the complement alternative pathway serine proteinase, is a major constitutive protein synthesized and secreted by resident and elicited mouse macrophages. 384 38

The biosynthesis of pyrophosphoethanolamine residues linked to the core oligosaccharide region of the lipopolysaccharide of Escherichia coli K2 strain BB 26-36 has been investigated by means of isotope tracer experiments in living cells. Phosphoethanolamine was isolated from the pyrophosphoethanolamine residues after hydrolysis in 1 N HCl at 100 degrees C. The kinetics of labeling of the phosphoethanolamine from [3H]serine or sn-glycero-3-32P during pulse-chase experiments revealed that the biosynthetic precursor of the phosphoethanolamine must be a large, relatively stable pool, and not a small, rapidly metabolized pool such as that of free serine, or seryl-tRNA. Labeling of the pyrophosphoethanolamine residues of the lipopolysaccharide from the two isotopes was closely parallel, and the isotope ratio 3H/32P was closely similar to that in phosphatidylethanolamine at the same time intervals. These experiments offer strong evidence that phosphatidylethanolamine functions in the biosynthesis of pyrophosphoethanolamine residues in lipopolysaccharide in a reaction in which the phosphoethanolamine head-group of the phospholipid is transferred as a unit to a lipopolysaccharide acceptor.
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PMID:Role of phosphatidylethanolamine in the biosynthesis of pyrophosphoethanolamine residues in the lipopolysaccharide of Escherichia coli. 675 35

Diisopropylfluorophosphate (DFP), a group-specific irreversible inhibitor of serine proteases, has been shown to exert time-dependent inhibition of DNA synthesis of lymphocytes stimulated by three different B lymphocyte mitogens: purified protein derivative of tuberculin (PPD), endotoxin protein (EP), and lipopolysaccharide (LPS). The time-dependent inhibition profile found in B lymphocytes is absent in concanavalin A (Con A)-stimulated T lymphocytes. Structural analogs of DFP, which have lost the phosphorylating ability, are not inhibitory. Inhibition of DNA synthesis by DFP is reversible in the first 8 hr of mitogenic stimulation. Maximal and irreversible inhibition by DFP occurs around the 16th hour of stimulation. These data support the postulate that a mitogenesis-linked protease, or proteases, in B lymphocytes is absent in the resting cells but is made available several hours before the initiation of DNA synthesis in the late G1 phase of the cell cycle.
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PMID:Time-dependent inhibition of tuberculin-induced lymphocyte DNA synthesis by a serine protease inhibitor. 697 91

We have examined the mechanism of release of monocyte-derived mediators that stimulate fibroblast proliferation in vitro. Adherence of human monocytes promotes the rapid release of these factors and treatment of adherent peripheral blood mononuclear cell (APBM) cultures with lipopolysaccharide (LPS) greatly enhances the level of fibroblast-stimulating activity in the cell-free culture supernatant fluid (SN). Stimulation of phagocytosis or pinocytosis does not alter the release of these mediators from APBM cultures while trypan blue pretreatment of peripheral blood mononuclear cells (PBM) results in a significant reduction in fibroblast stimulation by PBM-SN. Protein synthesis was blocked by pretreatment of monocytes with puromycin and was accompanied by a concomitant reduction in the production of these mediators. Monocyte serine proteases appear to be essential for mediator synthesis or release since tosyl-lysine chloromethyl ketone (TLCK) and phenylmethyl sulfonyl fluoride (PMSF), irreversible inhibitors of serine esterase activity, diminish the release of fibroblast-stimulating factors. Furthermore, time course data indicate that monocytes rapidly release these products in vitro during the first 24 hr of culture with significantly reduced levels being produced from 24 to 96 hr. These data indicate that adherent human monocytes rapidly release fibroblast-activating mediators in vitro, requiring both protein synthesis and protease activity; furthermore LPS, but not phagocytosis, can enhance the release of these products.
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PMID:Characterization of the release of human monocyte regulators of fibroblast proliferation. 710 71


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