Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proteinase 3 (PR3), a 29-kDa serine proteinase secreted from activated neutrophils, also exists in a membrane-bound form, and is suggested to actively contribute to inflammatory processes. The present study focused on the mechanism by which PR3 activates human oral epithelial cells. PR3 activated the epithelial cells in culture to produce IL-8 and monocyte chemoattractant protein-1 and to express ICAM-1 in a dose- and time-dependent manner. Incubation of the epithelial cells for 24 h with PR3 resulted in a significant increase in the adhesion to neutrophils, which was reduced to baseline levels in the presence of anti-ICAM-1 mAb. Activation of the epithelial cells by PR3 was inhibited by serine proteinase inhibitors and serum. The epithelial cells strongly express protease-activated receptor (PAR)-1 and PAR-2 mRNA and weakly express PAR-3 mRNA. The expression of PAR-2 on the cell surface was promoted by PR3, and inhibited by cytochalasin B, but not by cycloheximide. PR3 cleaved the peptide corresponding to the N terminus of PAR-2 with exposure of its tethered ligand. Treatment with trypsin, an agonist for PAR-2, and a synthetic PAR-2 agonist peptide induced intracellular Ca(2+) mobilization, and rendered cells refractory to subsequent stimulation with PR3 and vice versa. The production of cytokine induced by PR3 and the PAR-2 agonist peptide was completely abolished by a phospholipase C inhibitor. These findings suggest that neutrophil PR3 activates oral epithelial cells through G protein-coupled PAR-2 and actively participates in the process of inflammation such as periodontitis.
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PMID:Activation of human oral epithelial cells by neutrophil proteinase 3 through protease-activated receptor-2. 2030 33

Protease-activated receptors (PARs) compose a family of G protein-coupled receptors activated by proteolysis with exposure of their tethered ligand. Recently, we reported that a neutrophil-derived serine proteinase, proteinase 3 (PR3), activated human oral epithelial cells through PAR-2. The present study examined whether other neutrophil serine proteinases, human leukocyte elastase (HLE), and cathepsin G (Cat G) activate nonepithelial cells, human gingival fibroblasts (HGF). HLE and Cat G as well as PR3 activated HGF to produce IL-8 and monocyte chemoattractant protein 1. Human oral epithelial cells but not HGF express mRNA and protein of secretory leukocyte protease inhibitor, an inhibitor of HLE and Cat G, and recombinant secretory leukocyte protease inhibitor clearly inhibited the activation of HGF induced by HLE and Cat G but not by PR3. HGF express PAR-1 and PAR-2 mRNA in the cells and the proteins on the cell surface. HLE and Cat G cleaved the peptide corresponding to the N terminus of PAR-2 with exposure of its tethered ligand. Treatment with trypsin, an agonist for PAR-2, and a synthetic PAR-2 agonist peptide induced intracellular Ca(2+) mobilization and rendered cells refractory to subsequent stimulation with HLE and Cat G. The production of cytokine induced by HLE and Cat G and the PAR-2 agonist peptide was completely abolished by inhibition of phospholipase C. These findings suggest that neutrophil serine proteinases have equal ability to activate human nonepithelial cells through PAR-2 to produce inflammatory cytokines and may control a number of inflammatory processes such as periodontitis.
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PMID:Neutrophil serine proteinases activate human nonepithelial cells to produce inflammatory cytokines through protease-activated receptor 2. 2030 34

Anti-neutrophil cytoplasmic Abs targeting proteinase 3 (PR3) have been detected in relation to a wide range of inflammatory conditions such as periodontitis, and interaction of anti-PR3 Abs with endothelial and epithelial cells provokes cell activation, although the underlying mechanism has been unclear. The present study showed that human oral epithelial cells expressed PR3 mRNA after treatment with proinflammatory cytokines such as IL-1alpha, TNF-alpha, IFN-alpha, IFN-beta, and IFN-gamma. A 29-kDa PR3 was expressed on the cell surface and released into culture supernatants by the cells upon stimulation with these cytokines. The membrane and supernatant fractions of oral epithelial cells exhibited enzymatic activity, which was inhibited by serine proteinase inhibitors, but not by a cysteine proteinase inhibitor or secretory leukocyte protease inhibitor. Addition of anti-PR3 Abs to cytokine-primed oral epithelial cells in culture induced remarkable secretion of IL-8 and monocyte chemoattractant protein 1 and aggregation of PR3 on the cells. RNA interference targeted to protease-activated receptor-2 mRNA and intracellular Ca2+ mobilization assays revealed that anti-PR3 Abs activated the epithelial cells through protease-activated receptor-2, a family of G protein-coupled receptors. The anti-PR3 Ab-mediated cell activation was completely abolished by RNA interference targeted to PR3 mRNA and by inhibition of phospholipase C and NF-kappaB. Immunohistochemistry showed that inflamed oral epithelium actually expresses PR3 protein. These results suggest that oral epithelial cells express functional PR3 in the inflamed sites and respond to anti-PR3 Abs detected in diseased sera, and that these mechanisms may actively participate in the inflammatory process, including periodontitis.
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PMID:Proinflammatory cytokines induce proteinase 3 as membrane-bound and secretory forms in human oral epithelial cells and antibodies to proteinase 3 activate the cells through protease-activated receptor-2. 2030 35

Protease-activated receptors (PARs) are widely distributed in human airways. They couple to G- proteins and are activated after proteolytic cleavage of the N terminus of the receptor. Evidence is growing that PAR subtype 2 plays a pivotal role in inflammatory airway diseases, such as allergic asthma or bronchitis. However, nothing is known about the effects of PAR-2 on electrolyte transport in the native airways. PAR-2 is expressed in airway epithelial cells, where they are activated by mast cell tryptase, neutrophil proteinase 3, or trypsin. Recent studies produced conflicting results about the functional consequence of PAR-2 stimulation. Here we report that stimulation of PAR-2 receptors in mouse and human airways leads to a change in electrolyte transport and a shift from absorption to secretion. Although PAR-2 appears to be expressed on both sides of the epithelium, only basolateral stimulation results in inhibition of amiloride sensitive Na+ conductance and stimulation of both luminal Cl- channels and basolateral K+ channels. The present data indicate that these changes occur through activation of phospholipase C and increase in intracellular Ca2+, which activates basolateral SK4 K+ channels and luminal Ca2+-dependent Cl- channels. In addition, the present data suggest a PAR-2 mediated release of prostaglandin E2, which may contribute to the secretory response. In conclusion, these results provide further evidence for a role of PAR-2 in inflammatory airway disease: stimulation of these receptors may cause accumulation of airway surface liquid, which, however, may help to flush noxious stimuli away from the affected airways.
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PMID:Control of ion transport in mammalian airways by protease activated receptors type 2 (PAR-2). 1580 58

Autoantibodies to proteinase 3 (PR3) are involved in the pathogenesis of autoimmune-mediated vasculitis in Wegener granulomatosis (WG). To address the question how the autoantigen PR3 becomes a target of adaptive immunity, we investigated the effect of PR3 on immature dendritic cells (iDCs) in patients with WG, healthy blood donors, and patients with Crohn disease (CD), another granulomatous disease. PR3 induces phenotypic and functional maturation of a fraction of blood monocyte-derived iDCs. PR3-treated DCs express high levels of CD83, a DC-restricted marker of maturation, CD80 and CD86, and HLA-DR. Furthermore, the DCs become fully competent antigen-presenting cells and can induce stimulation of PR3-specific CD4(+) T cells, which produce IFN-gamma. PR3-maturated DCs derived from WG patients induce a higher IFN-gamma response of PR3-specific CD4(+) T cells compared with patients with CD and healthy controls. The maturation of DCs mediated through PR3 was inhibited by a serine protease inhibitor, by antibodies directed against the protease-activated receptor-2 (PAR-2), and by inhibition of phospholipase C, suggesting that the interactions of PR3 with PAR-2 are involved in the induction of DC maturation. Wegener autoantigen interacts with a "gateway" receptor (PAR-2) on iDCs in vitro triggering their maturation and licenses them for a T helper 1 (Th1)-type response potentially favoring granuloma formation in WG.
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PMID:Wegener autoantigen induces maturation of dendritic cells and licenses them for Th1 priming via the protease-activated receptor-2 pathway. 1647 88

Proteinase 3 (PR3) is a serine protease of neutrophil granules released to the medium or into the phagocytic vesicle upon neutrophil stimulation. A fraction of the enzyme is thought to associate with the cell membrane yielding membrane PR3 (mPR3). In autoimmune disorders characterized by the presence of antineutrophil cytoplasmic antibodies (ANCA), the reaction of the latter with their target antigen mPR3 activates the cell inflicting injuries on the surrounding tissues. In a previous communication we provided evidence for the presence of mPR3 in lipid rafts obtained by lysis of neutrophils in Triton X-100 and for the mediation of PR3 binding to the membrane by a glycosylphosphatidylinositol (GPI)-anchored neutrophil protein, possibly FcgammaRIIIb. In the current study we employed the mild detergent Brij 58 to isolate high molecular weight (HMW) protein complexes in the void volume of a Sepharose 4B gel filtration minicolumn. HMW complexes of unstimulated neutrophils comprised PR3, FcgammaRIIIb, the beta2 integrin CD11b/CD18 as well as the membrane and cytosolic subunits of the NADPH oxidase, p22phox and p47phox/p67phox. Treatment of neutrophils with phosphatidylinositol-specific phospholipase C (PI-PLC) reduced amounts of PR3 and FcgammaRIIIb in HMW complexes isolated from the treated cells, supporting our previous suggestion that FcgammaRIIIb acts as a membrane adaptor for PR3. FcgammaRIIIb of HMW fractions co-immunoprecipitated with PR3, indicating their presence in the same protein complex. Since HMW fractions contained also the majority of biotinylated proteins obtained by the reaction of neutrophils with a membrane impermeable biotinylating agent Sulfo-NHS-biotin, it was concluded that HMW proteins were derived from cell membranes. Lipid rafts isolated from Brij 58-lysed neutrophils were similar in their protein composition to the HMW complexes but not identical.
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PMID:Membrane proteinase 3 and its interactions within microdomains of neutrophil membranes. 1659 72

Anti-proteinase-3 (anti-PR3) or anti-myeloperoxidase (anti-MPO) antibodies are capable of activating human neutrophils primed by TNF-alpha in vitro. We described previously the involvement of FcgammaRIIa and beta(2) integrins in this neutrophil activation. In the literature, the requirement of TNF priming has been attributed to an effect of TNF-alpha on the expression of PR3 or MPO on the cell surface. Under our experimental conditions, TNF-alpha (2 ng/ml) increased the binding of the antibody against PR3, whereas binding of the antibody against MPO could hardly be detected, not even after TNF-alpha treatment. The aim of this study was to consider (an)other(s) role(s) for TNF-alpha in facilitating the NADPH-oxidase activation by these antibodies. We demonstrate the early mobilization of the secretory vesicles as a result of TNF-induced increase in intracellular-free calcium ions, the parallel colocalization of gp91(phox), the main component of the NADPH oxidase with beta(2) integrins and FcgammaRIIa on the neutrophil surface, and the FcgammaRIIa clustering upon TNF priming. TNF-alpha also induced redistribution of FcgammaRIIa to the cytoskeleton in a dose- and time-dependent manner. Moreover, blocking CD18 MHM23 antibody, cytochalasin B, and D609 (an inhibitor of phosphatidylcholine phospholipase C) inhibited this redistribution and the respiratory burst in TNF-treated neutrophils exposed to anti-PR3 or anti-MPO antibodies. Our results indicate direct effects of TNF-alpha in facilitating neutrophil activation by these antibodies and further support the importance of cytoskeletal rearrangements in this priming process.
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PMID:Priming by tumor necrosis factor-alpha of human neutrophil NADPH-oxidase activity induced by anti-proteinase-3 or anti-myeloperoxidase antibodies. 1699 60

Anti-neutrophil cytoplasmic Abs against proteinase 3 (PR3) have been detected in relation to a wide range of inflammatory conditions, and the interaction of anti-PR3 Abs with leukocytes provokes cell activation, although how is not clear. Flow cytometric analysis revealed an increase in cell-surface CD14, Toll-like receptor (TLR)2, TLR4 and intracellular TLR3, TLR7, TLR8, TLR9, NOD1 and NOD2 expression during anti-PR3 priming in human monocytic THP-1 cells. Anti-RP3 Abs markedly promoted the release of IL-8 induced by chemically synthesized TLR and NOD ligands mimicking bacterial components: TLR2-agonistic lipopeptide (FSL-1), TLR3-agonistic poly I:C, TLR4-agonistic lipid A (LA-15-PP), TLR7/8-agonistic single stranded RNA (ssPolyU), TLR9-agonistic bacterial CpG DNA, NOD1-agonistic FK156/565 and NOD2-agonistic muramyldipeptide (MDP) in THP-1 cells and human peripheral blood mononuclear cells, although sole incubation with anti-PR3 Abs induced only a low level of IL-8. The priming response was evident after 2h of preincubation with anti-PR3 Abs and peaked after 6h. Priming was also observed for the production of TNF-alpha and monocyte chemoattractant protein-1. An RNA interference assay revealed that anti-PR3 Abs activated THP-1 cells in a PR3- and protease-activated receptor-2-dependent manner. Furthermore, the anti-PR3 Ab-mediated cell activation was significantly abolished by RNA interference targeted at PR3 mRNA and by inhibition of phospholipase C and NF-kappaB. These results suggest that anti-PR3 Abs prime human monocytic cells to produce cytokines upon stimulation with various bacterial components by up-regulating the TLR and NOD signaling pathway, and that these mechanisms may actively participate in the inflammatory process.
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PMID:Antibodies to proteinase 3 prime human monocytic cells via protease-activated receptor-2 and NF-kappaB for Toll-like receptor- and NOD-dependent activation. 1745 51