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)

PC4 is a serine protease primarily expressed in spermatids. We have produced PC4-deficient mice carrying an insertion of the bacterial gene for beta galactosidase under the PC4 gene promoter. Male mice lacking PC4 (-/-) exhibit severely reduced fertility. Surprisingly, the fertility of female mice is also significantly diminished in these mutants (Mbikay et al., 1997. Proc. Natl. Acad. Sci. USA 94, 6842-6846). The aim of this study was to determine the site of PC4 expression in mouse ovaries. Using a histoenzymatic assay for beta-galactosidase, we show that the PC4 promoter can drive strong expression of this enzyme in the theca-interstitium and in degenerating corpora lutea of +/- ovaries. We also demonstrate that PC4 transcripts can be detected by RT-PCR in the ovaries of +/- and +/+ mice, but not in those of -/- mice. The cells expressing PC4 were macrophage-like, since they expressed the macrophage markers CD11b and F4/80, as well as interleukin 1beta and tumor necrosis factor alpha (TNFalpha). Expression of PC4 was also detected in the mouse macrophage RAW264.7 cell line. Interestingly, TNFalpha transcripts were 3-fold more abundant in ovarian macrophage-like cells from -/- mice than in those from +/+ mice, suggesting a constitutive state of activation of the mutant cells. An inverse relationship between PC4 expression and macrophage activation was also observed in RAW264.7 cells. When these cells were activated using bacterial lipopolysaccharide, the level of PC4 transcripts decreased, while that of TNFalpha increased. These observations identify PC4 as an enzyme that could influence ovarian physiology by affecting macrophage functions.
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PMID:The testicular germ-cell protease PC4 is also expressed in macrophage-like cells of the ovary. 1116 98

Achatinin, a 9-O-acetyl sialic acid (9-O-AcSA) binding lectin, has been demonstrated to be synthesized in amoebocytes of Achatina fulica snails. This lectin was affinity-purified from Achatina amoebocytes lysate (AAL); it appeared as a single band on native polyacrylamide gel electrophoresis (PAGE) and showed 16 identical subunits of M.W. 15 kDa on sodium dodecyl sulphate (SDS)-PAGE. It was found to be homologous with an earlier reported lectin, Achatinin-H, derived from hemolymph of A. fulica snails (Sen, G., Mandal, C., 1995. The specificity of the binding site of Achatinin-H, a sialic-acid binding lectin from Achantia fulica. Carbohydr. Res., 268, 115-125). Homology between both lectins was confirmed by their similar electrophoretic mobilities, carbohydrate specificity and cross reactivity on immunodiffusion. Achatinin showed in vitro calcium dependent binding to two 9-O-acetylated sialoglyoconjugates (9-O-AcSG) on lipopolysaccharide (LPS) (Escherichia coli 055: B5) of M.W. 40 kDa and 27.5 kDa, which was abolished following de-O-acetylation. Based on the previously defined narrow sugar specificity of Achatinin towards 9-O-AcSAalpha2-->6GalNAc [Sen, G., Mandal, C., 1995. The specificity of the binding site of Achatinin-H, a sialic-acid binding lectin from Achatina fulica. Carbohydr. Res., 268, 115-125], we conclude that LPS contains this lectinogenic epitope at the terminal sugar moiety. The Achatinin-mediated hemagglutination inhibition of rabbit erythrocytes by LPS further confirmed it. The lectin exhibited bacteriostatic effect on Gram-negative bacteria E. coli, DH5alpha and C600. AAL was earlier reported to undergo coagulation in presence of pg level of LPS (Biswas, C., Mandal, C., 1999. The role of amoebocytes in the endotoxin-mediated coagulation in the innate immunity of Achatina fulica snail, Scand. J. Immunol. 49, 131-138). We now demonstrate that Achatinin participates in LPS-mediated coagulation of AAL as indicated by enhanced release of Achatinin from the LPS stimulated amoebocytes and most importantly, by exhibiting a 77% decline in the coagulation of AAL when depleted of Achatinin. Level of Achatinin sharply declined (17-fold) following injection of LPS (20 microg per snail) to the snails, which was reversible by simultaneous injection of LPS and leupeptin implying the presence of LPS-mediated serine protease activity in Achatinin. This was substantiated when purified Achatinin in vitro showed serine protease activity in the presence of LPS followed by its complete blockage in the presence of leupeptin and phenyl methyl sulphonyl fluoride. Therefore, Achatinin, an abundantly available lectin at multiple sites of A. fulica, by virtue of its interaction with LPS, essentially plays a crucial role in the innate immune protection of A. fulica snails.
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PMID:Investigation on interaction of Achatinin, a 9-O-acetyl sialic acid-binding lectin, with lipopolysaccharide in the innate immunity of Achatina fulica snails. 1127 59

Factor C is an endotoxin-sensitive, intracellular serine protease zymogen which initiates the coagulation cascade system in the horseshoe crab hemolymph. The special lipopolysaccharide (LPS) binding activation of FC makes it a potential drug for anti-LPS treatment and has a high commercial value. Based on the sequence of reported FC from Japan horseshoe crab, two pairs of primers were designed. The total RNA was extracted from amebocytes of Chinese Tachypleus tridentatus and the cDNA was separated into two parts and were cloned using RT-PCR, respectively. FCs from different geographical areas showed high homology in sequence. The whole FC cDNA was cloned into pET-28a (+) containing T7 promoter and recombinant expression plasmid pET-FC was constructed. The recombinant plasmid was transformed into E. coli BL21 (DE3). Recombinant FC was expressed as inclusion body when the expression strain was induced with 1 mmol/L IPTG. Refolded recombinant FC was confirmed to be active by bacteriostatic assay in vitro. The results of Western blot also suggested the recombinant FC may be able to cleave itself partly and produced an extra immunoblot band.
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PMID:[Cloning and expression of Tachypleus tridentatus factor C]. 1195 40

Epithelial cells are the first cells that encounter infecting bacteria and, as such, they have developed several mechanisms for microbial protection. We have shown previously that bladder epithelial cells express the lipopolysaccharide (LPS) receptor Toll-like receptor (TLR) 4 that enables a rapid cellular interleukin (IL)-8 response when exposed to Escherichia coli and LPS. TLR4 belongs to a family of receptors that was initially identified in Drosophila, in which Toll is required for the immune response against fungi. Fungal exposure activates a series of serine proteases that process the protein Spaetzle to a cytokine-like form that acts as a ligand for Toll. Here, we investigated whether a similar proteolytic cascade is required for human TLR activation. When screening a set of 18 protease inhibitors, three serine protease inhibitors (TPCK, TLCK and Pefabloc) were shown to inhibit LPS- and peptidoglycan-induced IL-8 production in TLR2- and TLR4-positive bladder epithelial cells. However, they were equally effective inhibitors of IL-1beta-induced signalling, indicating that their target(s) is/are located downstream of the TLRs. Further characterization showed that these inhibitors blocked I kappa B degradation but not phosphorylation in LPS-stimulated cells, which suggests that the serine protease inhibitors target the 26S proteasome. Identical results were obtained on LPS-stimulated monocytes. Based on these data, we find no evidence for the involvement of proteases upstream of TLRs in either epithelial cells or cells of the monocytic lineage.
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PMID:TLR4-dependent lipopolysaccharide signalling in epithelial cells is independent of extracellular protease activity. 1202 57

The Limulus Factor C (FC), a multidomain glycoprotein that binds bacterial endotoxin with high affinity, belongs to the serine protease family of the complement and blood coagulation cascade. Here, we provide compelling evidence for the importance of modular arrangement and relevance of the proline-rich region (PRR) and N-glycosylation to the secretion and function of FC. We propose that PRR could be a universal conformational domain that regulates protein folding and targeting. FCs lacking PRR preceding the serine protease domain, were localized intracellularly. Misfolded conformers of the intracellular FCs were more susceptible to trypsin digestion. Glycosylation inhibition studies indicate that the presence but not the exact structure of the N-glycans affects the secretion of FC, although the complexity of glycosylation may influence its endotoxin-induced proteolytic cleavage with resultant enzymatic activity. Disruption of specific N-glycan sites at positions 740, 767, and 912, downstream of the PRR, at or near the serine protease domain, blocks its secretion. Co-expressed molecular chaperones like canine calnexin associates with glycosylated FCs to increase its solubility and secretion level but did not alter their expression profiles. Our results clearly demonstrate that the folding and secretion of a multidomain serine protease like FC are determined by its modular domain arrangement and site-specific N-glycans. The secreted FCs containing the N-terminal portion of FC are able to detect lipopolysaccharide with high sensitivity. We also identified the lectin-like and sushi 4 domains to contribute to the binding of lipopolysaccharide.
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PMID:Modular arrangement and secretion of a multidomain serine protease. Evidence for involvement of proline-rich region and N-glycans in the secretion pathway. 1208 46

Activated protein C (APC), an important natural anticoagulant, inhibits tumor necrosis factor-alpha (TNF-alpha) production and attenuates various deleterious events induced by lipopolysaccharide (LPS), contributing thereby to a significant reduction of mortality in patients with severe sepsis. In this study, we investigated the mechanism(s) by which APC inhibits TNF-alpha production by LPS-stimulated human monocytes in vitro. Although APC inhibited LPS-induced TNF-alpha production in a concentration-dependent fashion, diisopropyl fluorophosphate-treated APC, an active-site-blocked APC, had no effect. APC inhibited both the binding of nuclear factor-kappa B (NF-kappa B) to target sites and the degradation of I kappa B alpha. APC also inhibited both the binding of activator protein-1 (AP-1) to target sites and the activation of mitogen-activated protein kinase pathways. These observations strongly suggest that APC inhibited LPS-induced TNF-alpha production by inhibiting the activation of both NF-kappa B and AP-1 and that the inhibitory activity of APC might depend on its serine protease activity. These results would at least partly explain the mechanism(s) by which APC reduces the tissue injury seen in animal models of sepsis and in patients with sepsis.
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PMID:Activated protein C inhibits lipopolysaccharide-induced tumor necrosis factor-alpha production by inhibiting activation of both nuclear factor-kappa B and activator protein-1 in human monocytes. 2213 Oct 84

Expression of tissue factor (TF) by activated monocytes may initiate thrombotic episodes associated with diseases, such as thrombosis and atherosclerosis. In this study, steps in the regulatory pathways of lipopolysaccharide (LPS)-induced monocyte TF activity and released TNF-alpha in human whole blood were probed for using an array of inhibitors, comprising specific inhibitors of cytosolic phospholipase A(2) (PLA(2)) (AACOCF(3)), secretory PLA(2) (SB-203347), protein kinase (PK) (staurosporine), PKC (GF-109203; BIM), and serine protease (Pefabloc SC), antagonists of thromboxane prostanoid (TP) receptor (R) (SQ-29548), platelet activating factor (PAF) R (BN-52021), leukotriene B(4) R (SC-41930), serotonin R (cyproheptadine), fibronectin/fibrinogen R (RGDS), and finally, creatine phosphate/creatine phosphokinase (CP/CPK) which removes ADP. Whereas when added alone neither of these agents significantly inhibited LPS-induced TF or TNF-alpha, when presented as a reference cocktail comprising all the agents, TF activity and TNF-alpha were reduced by 77% and 49%, respectively. By subsequently testing a series of incomplete inhibitory cocktails equal to the reference except for deleted single agents or combinations of two or three active agents, the inhibitory effect of the reference cocktail could be shown to depend on the presence of the protease inhibitor and the thromboxane A(2) and PAF antagonists.
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PMID:The central role of thromboxane and platelet activating factor receptors in ex vivo regulation of endotoxin-induced monocyte tissue factor activity in human whole blood. 1223 Sep 18

The complement activation product, C5a, is a powerful phlogistic factor. Using antibodies to detect human or rat C5a, incubation at pH 7.4 of human blood neutrophils or rat alveolar macrophages (AMs) with C5 in the presence of phorbol 12-myristate 13-acetate (PMA) led to generation of C5a. Rat AMs activated with lipopolysaccharide also generated C5a from C5. With activated neutrophils, extensive cleavage of C5 occurred, whereas activated macrophages had much more selective proteolytic activity for C5. Peripheral blood human or rat mononuclear cells and rat alveolar epithelial cells when stimulated with phorbol ester all failed to demonstrate an ability to cleave C5, suggesting a specificity of C5 cleavage by phagocytic cells. With rat AMs, C5a generation was time-dependent and was blocked if AMs were pretreated with inhibitors of transcription or protein synthesis (actinomycin D or cycloheximide). Similar treatment of activated human polymorphonuclear leukocytes only partially reduced C5a generation after addition of C5. C5a generated by activated AMs was biologically (chemotactically) active. This generation was sensitive to serine protease inhibitors but not to other classes of inhibitors. These data indicate that phagocytic cells, especially lung macrophages, can generate C5a from C5. In the context of the lung, this may represent an important C5a-generating pathway that is independent of the plasma complement system.
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PMID:Generation of C5a by phagocytic cells. 1241 31

C1r and C1s are highly specific serine proteases that initiate the classical pathway of complement activation. We recently demonstrated that, in the mouse, the genes encoding these proteins are duplicated. Analysis of the 5'-flanking region of the murine C1rA gene, the homologue of human C1r, revealed the presence of a novel gene encoding a C1r-like protein (c1r-LP). Although this gene carries a large deletion, it shows an overall structure similar to that of c1rA, suggesting that it may have arisen from a duplication of the C1r gene. The c1r-LP gene is expressed primarily in the liver, and is not regulated by lipopolysaccharide. The open reading frame of full-length cDNA clones encodes a pre-protein with a calculated molecular mass of 50.6 kDa which, except for an internal deletion of several modules, has a modular organization similar to that of C1r and shows 51% overall amino acid identity to corresponding regions of C1rA. Western blot analysis demonstrates the presence of C1r-LP in mouse serum. The serine protease domain of C1r-LP displays 60% amino acid residue identity to that of C1rA, however, certain atypical features of the active center, and primarily the absence of the activation/cleavage site, suggest that C1r-LP is either an atypical enzyme, or it lacks proteolytic activity, perhaps serving a regulatory function in the classical pathway.
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PMID:A novel murine complement-related gene encoding a C1r-like serum protein. 1268 6

Serine proteases play fundamental roles in invertebrate development, hemostasis, and innate immunity. This is exemplified by the limulus Factor C, which is a serine protease that binds a pathogen-associated molecule, lipopolysaccharide (LPS) to trigger a blood coagulation cascade. As a central molecule in the limulus innate immunity and hemostasis, Factor C gene expression has been detected in two major immune defense tissues, the amebocytes and hepatopancreas. Infection of the limulus with live Gram-negative bacteria induces a 2-3-fold increase in mRNA transcripts in both tissues. However, in vitro studies in Drosophila cell lines using Factor C promoter-reporter chimera DNA constructs, and site-directed mutagenesis of the promoter demonstrated that a proximal kappaB binding site, aided by an adjacent dorsal-like binding motif responds dramatically to LPS and dorsal transcription factor overexpression. Electrophoretic mobility shift assay further confirmed a strong interaction of the limulus kappaB motif with Rel proteins. However, deletion constructs of the Factor C promoter harboring different numbers of dorsal-like binding sites upstream of the kappaB motif as well as the electrophoretic mobility shift assay of these motifs with Rel proteins strongly suggest that the up-regulation of Factor C gene expression is attenuated during microbial challenge. The repression of the dramatic activation of this pathogen-responsive gene by LPS is probably effected via competition between the dorsal-like motifs over the proximal LPS-responsive kappaB unit, or through inhibition from the upstream repressive element(s), which accounts for the gene expression pattern observed in vivo. Our findings demonstrate that blood coagulation and innate immune response are integrated at the transcriptional level in this ancient organism, and that this LPS-responsive serine protease is controlled by an evolutionarily conserved NFkappaB pathway.
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PMID:Transcriptional regulation of limulus factor C: repression of an NFkappaB motif modulates its responsiveness to bacterial lipopolysaccharide. 1294 77


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