Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proteinase-activated receptor-2 (PAR-2) is the second member of a putative larger class of proteolytically activated receptors that mediate cell activation events by receptor cleavage or synthetic peptidomimetics corresponding to the newly generated N-terminus. To further study the previously identified mitogenic effects of PAR-2, we used the interleukin-3 (IL-3)-dependent murine lymphoid cell line, BaF3, for generation of stable cell lines expressing PAR-2 (BaF3/PAR-2) or the noncleavable PAR-2 mutant PAR-2(Arg36 --> Ala36). Only BaF3 cells expressing either wild-type or mutated receptor exhibited mitogenic responses when grown in IL-3-deficient media supplemented with PAR-2 activating peptide (SLIGRL, PAR39-44). This effect was dose dependent with an EC50 of approximately 80 micromol/L, sustained at 24, 48, and 72 hours, and was also demonstrable using thrombin receptor peptide TR42-47. Because tryptase shares approximately 70% homology with trypsin (previously shown to activate PAR-2), we studied recombinantly expressed forms of alpha- and beta-tryptases as candidate protease agonists for PAR-2. Hydrolytic activity of the chromogenic substrate tosyl-glycyl-prolyl-argly-4-nitroanilide acetate was present as a sharp peak at Mr approximately 130, confirming the presence of secretable and functionally active homotetrameric alpha- and beta-tryptases in transfected COS-1 cells. Dose-dependent proliferative responses were evident using either secreted form of tryptase with maximal responses seen at approximately 3 pmol/L (0.1 U/L). Receptor proteolysis was necessary and sufficient for mitogenesis because active site-blocked tryptase failed to induce this response, and proliferative responses were abrogated in BaF3 cells expressing PAR-2(Arg36 --> Ala36). These results specifically identify both forms of mast cell tryptases as serine protease agonists for PAR-2 and have implications for elucidating molecular mechanisms regulating cellular activation events mediated by proteases generated during inflammatory, fibrinolytic, or hemostatic-regulated pathways.
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PMID:Mitogenic responses mediated through the proteinase-activated receptor-2 are induced by expressed forms of mast cell alpha- or beta-tryptases. 935 58

Proteinase-activated receptor 2 (PAR2) has been suggested to play a role in inflammatory reactions. Because leukocyte-endothelial cell interactions are critical events during inflammatory reactions, and because PAR2 is expressed both on endothelium and leukocytes, we have examined the effects of PAR2-activating peptides (PAR2-APs) on leukocyte rolling and adhesion in mesenteric venules and on leukocyte recruitment into the peritoneal cavity. Using intravital microscopy, leukocyte rolling, flux, and adhesion in rat mesenteric postcapillary venules were quantified. Topical addition of PAR2-APs (10 microM) for 1 min to the superfused venule induced a significant increase in leukocyte rolling and adherence. The increase in leukocyte adherence was not affected by pretreatment with a mast cell stabilizer (sodium cromoglycate) nor by prior degranulation of mast cells with compound 48/80. Nonetheless, both leukocyte rolling and adhesion were completely inhibited by pretreatment with a platelet-activating factor receptor antagonist (WEB 2086). Intraperitoneal injections of a selective PAR2-AP (SLIGRL-NH2) caused a significant increase in leukocyte migration into the peritoneal cavity. The effect of SLIGRL-NH2 on peritoneal leukocyte infiltration was completely inhibited by WEB 2086. These data suggest that PAR2 activation could contribute to several early events in the inflammatory reaction, including leukocyte rolling, adherence, and recruitment, by a mechanism dependent on platelet-activating factor release.
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PMID:Proteinase-activated receptor-2-activating peptides induce leukocyte rolling, adhesion, and extravasation in vivo. 1052 12

We have previously shown that mast cells enhance eosinophil survival and activation. In this study we further characterized mast cell activity toward eosinophils. Sonicate of both rat peritoneal mast cells and the human mast cell line 1 (HMC-1) induced a concentration-dependent IL-6 and IL-8 release from human peripheral blood eosinophils (ELISA). HMC-1-induced IL-8 release was significantly reduced by the tryptase inhibitors GW-45 and GW-58 (90 and 87%, respectively, at an optimal concentration) but not by anti-stem cell factor, anti-TNF-alpha, or anti-IFN-gamma neutralizing Abs or by the antihistamine drugs pyrilamine and cimetidine. In a manner similar to HMC-1, human recombinant tryptase induced the expression of mRNA for IL-8 (RT-PCR) and caused IL-8 release from the eosinophils. Addition of cycloheximide, actinomycin D, dexamethasone, PD 98059, curcumin, or SB 202190 completely inhibited the tryptase-induced IL-6 and IL-8 release. In contrast, cyclosporin A had no effect on tryptase-induced IL-8 release. Tryptase caused phosphorylation of extracellular signal-regulated kinases 1 and 2, c-Jun N-terminal kinases 1 and 2, and p38 (Western blot). Tryptase also induced the translocation of c-Jun from the cytosol to the nucleus (confocal microscopy) and enhanced AP-1 binding activity to the DNA (EMSA). Eosinophils were found to express proteinase-activated receptor 2 (FACS). When eosinophils were incubated with tryptase in the presence of anti-proteinase-activated receptor 2 antagonist Abs a significant decrease in the IL-6 and IL-8 release occurred. In summary, we have demonstrated that the preformed mast cell mediator tryptase induces cytokine production and release in human peripheral blood eosinophils by the mitogen-activated protein kinase/AP-1 pathway.
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PMID:Tryptase activates the mitogen-activated protein kinase/activator protein-1 pathway in human peripheral blood eosinophils, causing cytokine production and release. 1219 39

Mast cells that are in close proximity to autonomic and enteric nerves release several mediators that cause neuronal hyperexcitability. This study examined whether mast cell tryptase evokes acute and long-term hyperexcitability in submucosal neurons from the guinea-pig ileum by activating proteinase-activated receptor 2 (PAR2) on these neurons. We detected the expression of PAR2 in the submucosal plexus using RT-PCR. Most submucosal neurons displayed PAR2 immunoreactivity, including those colocalizing VIP. Brief (minutes) application of selective PAR2 agonists, including trypsin, the activating peptide SL-NH2 and mast cell tryptase, evoked depolarizations of the submucosal neurons, as measured with intracellular recording techniques. The membrane potential returned to resting values following washout of agonists, but most neurons were hyperexcitable for the duration of recordings (> 30 min-hours) and exhibited an increased input resistance and amplitude of fast EPSPs. Trypsin, in the presence of soybean trypsin inhibitor, and the reverse sequence of the activating peptide (LR-NH2) had no effect on neuronal membrane potential or long-term excitability. Degranulation of mast cells in the presence of antagonists of established excitatory mast cell mediators (histamine, 5-HT, prostaglandins) also caused depolarization, and following washout of antigen, long-term excitation was observed. Mast cell degranulation resulted in the release of proteases, which desensitized neurons to other agonists of PAR2. Our results suggest that proteases from degranulated mast cells cleave PAR2 on submucosal neurons to cause acute and long-term hyperexcitability. This signalling pathway between immune cells and neurons is a previously unrecognized mechanism that could contribute to chronic alterations in visceral function.
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PMID:Mast cell tryptase and proteinase-activated receptor 2 induce hyperexcitability of guinea-pig submucosal neurons. 1256 62

We examined whether neuronal proteinase-activated receptor-2 (PAR-2) may be involved in pruritus of human skin. The endogenous PAR-2 agonist tryptase was increased up to fourfold in atopic dermatitis (AD) patients. PAR-2 was markedly enhanced on primary afferent nerve fibers in skin biopsies of AD patients. Intracutaneous injection of endogenous PAR-2 agonists provoked enhanced and prolonged itch when applied intralesionally. Moreover, itch upon mast cell degranulation was abolished by local antihistamines in controls but prevailed in AD patients. Thus, we identified enhanced PAR-2 signaling as a new link between inflammatory and sensory phenomena in AD patients. PAR-2 therefore represents a promising therapeutic target for the treatment of cutaneous neurogenic inflammation and pruritus.
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PMID:Proteinase-activated receptor-2 mediates itch: a novel pathway for pruritus in human skin. 1286

The mast cell serine protease tryptase has been implicated as a critical mediator of airway hyperresponsiveness in vitro and in vivo. We have previously demonstrated that tryptase promotes hyperresponsiveness in isolated guinea pig bronchi. In this study, we have investigated the potential role of tryptase-mediated activation of proteinase-activated receptor-2 (PAR-2) in promoting airway hyperresponsiveness. Ex vivo exposure of guinea pig bronchi to the PAR-2 agonists H(2)N-Ser-Leu-Ile-Gly-Arg-Leu-CONH(2) (SLIGRL) and t-cinnamoyl-H(2)N-Leu-Ile-Gly-Arg-Leu-O-CONH(2) (t-c-LIGRLO) (0.1-10 microM) induced a concentration-dependent increase of contractile response to histamine. Treatment with 10 microM SLIGRL or t-c LIGRLO for 45 min increased subsequent responsiveness to histamine (0.3mM) by 54+/-3% and 69+/-5%, respectively (P<0.05 vs. control). In contrast, the PAR-1 agonist peptide H(2)N-Ser-Phe-Leu-Leu-Arg-Asn-CONH(2) (SFLLRN) did not promote significant changes in the airway. Effects of the peptides were observed following at least a 30-min preincubation with the tissue. Coincubation with indomethacin or removal of epithelial cells is required for PAR-2-mediated hyperreactivity. The inactive analogue H(2)N-Leu-Ser-Ile-Gly-Arg-Leu-CONH(2) (LISGRL; 10 microM) failed to promote hyperresponsiveness. Neuropeptide antagonists blocked the effect of the PAR-2 agonists. Selective antagonists of NK1 (L-703,606), NK2 (L-659,877), and CGRP (alphaCGRP 8-37) provided additive inhibition of PAR-2-mediated hyperreactivity. Pretreatment of bronchi with capsaicin (0.8 microM) also prevented the effects of SLIGRL. These results demonstrate the potential involvement of tryptase-mediated activation of PAR-2 in promoting airway hyperresponsiveness. These results further demonstrate that the PAR-2-mediated response involves a neurogenic mechanism involving neuropeptide release.
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PMID:Proteinase-activated receptor-2 mediates hyperresponsiveness in isolated guinea pig bronchi. 1290 52

Proteinase-activated receptor 2 (Par2, F2rl1, also designated PAR-2 or PAR2) is prominently expressed in the intestine and has been suggested as a mediator of inflammatory, mitogenic and fibrogenic responses to injury. Mast cell proteinases and pancreatic trypsin, both of which have been shown to affect the intestinal radiation response, are the major biological activators of Par2. Conventional Sprague-Dawley rats, mast cell-deficient rats, and rats in which pancreatic exocrine secretion was blocked pharmacologically by octreotide underwent localized irradiation of a 4-cm loop of small bowel. Radiation injury was assessed 2 weeks after irradiation (early, inflammatory phase) and 26 weeks after irradiation (chronic, fibrotic phase). Par2 expression and activation were assessed by in situ hybridization and immunohistochemistry, using antibodies that distinguished between total (preactivated and activated) Par2 and preactivated Par2. Compared to unirradiated intestine, irradiated intestine exhibited increased Par2 expression, particularly in areas of myofibroblast proliferation and collagen accumulation, after both single-dose and fractionated irradiation. The majority of Par2 expressed in fibrotic areas was activated. Postirradiation Par2 overexpression was greatly attenuated in both mast cell-deficient and octreotide-treated rats. The severity of acute mucosal injury did not affect postirradiation Par2 expression. Mast cells and pancreatic proteinases may exert their fibro-proliferative effects partly through activation of Par2. Par2 may be a potential target for modulating the intestinal radiation response, particularly delayed intestinal wall fibrosis.
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PMID:Up-regulation and activation of proteinase-activated receptor 2 in early and delayed radiation injury in the rat intestine: influence of biological activators of proteinase-activated receptor 2. 1456 30

Tryptase, the major secretory product of human mast cells, is emerging as a new target for therapeutic intervention in allergic airways disease. We have investigated the ability of tryptase and inhibitors of tryptase to modulate histamine release from human lung mast cells and have examined the potential contribution of proteinase-activated receptor 2 (PAR2). The tryptase inhibitor APC366 [N-(1-hydroxy-2-naphthoyl)-L-arginyl-L-prolinamide hydrochloride] was highly effective at inhibiting histamine release stimulated by anti-IgE antibody or calcium ionophore from enzymatically dispersed human lung cells. A concentration of APC366 as low as 10 microM was able to inhibit anti-IgE-dependent histamine release by some 50%. Addition of leupeptin or the tryptic substrate N-benzoyl-D,L-arginine-p-nitroanilide also inhibited IgE-dependent histamine release. Purified tryptase in the presence of heparin stimulated a small but significant release of histamine from lung cells, suggesting that tryptase may provide an amplification signal from activated cells that may be susceptible to proteinase inhibitors. Trypsin was also able to induce histamine release apparently by a catalytic mechanism. Moreover, pretreatment of cells with metabolic inhibitors or with pertussis toxin reduced responses, indicating a noncytoxic pertussis toxin-sensitive G protein-mediated signaling process. Addition to cells of the PAR2 agonists SLIGKV-NH(2) or tc-LIGRLO-NH(2) or appropriate control peptides were without effect on histamine release, and PAR2 was not detected by immunohistochemistry in tissue mast cells. The potent actions of tryptase inhibitors as mast cell-stabilizing agents could be of value in the treatment of allergic inflammation of the respiratory tract, possibly by targeting the non-PAR2-mediated actions of tryptase.
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PMID:Inhibitors of tryptase as mast cell-stabilizing agents in the human airways: effects of tryptase and other agonists of proteinase-activated receptor 2 on histamine release. 1472 28

We hypothesized that proteinase-activated receptor-2 (PAR(2)) modulates intestinal injuries induced by ischemia/reperfusion. Ischemia (1 hour) plus reperfusion (6 hours) significantly delayed gastrointestinal transit (GIT) compared with sham operation. Intraduodenal injection of PAR(2)-activating peptide SLIGRL-NH(2) significantly accelerated transit in ischemia/reperfusion but not in sham-operated rats. GIT was significantly delayed in ischemia/reperfusion and sham-operated PAR(2)(-/-) mice compared with PAR(2)(+/+). SLIGRL-NH(2) significantly accelerated transit in ischemia/reperfusion in PAR(2)(+/+) but not in PAR(2)(-/-) mice. Prevention of mast cell degranulation with cromolyn, ablation of visceral afferents with capsaicin, and antagonism of calcitonin gene-related peptide (CGRP) and neurokinin-1 receptors with CGRP(8-37) and RP67580, respectively, abolished the SLIGRL-NH(2)-induced stimulatory effect on transit in ischemia/reperfusion. Tissue damage was significantly reduced by SLIGRL-NH(2); this effect was not observed in cromolyn-, capsaicin-, or RP67580-treated rats but was detected following CGRP(8-37). Intestinal PAR(2) mRNA levels were not affected by SLIGRL-NH(2) in ischemia/reperfusion. We propose that PAR(2) modulates GIT and tissue damage in intestinal ischemia/reperfusion by a mechanism dependent on mast cells and visceral afferents. PAR(2) effect on transit might be mediated by CGRP and substance P, whereas the effect on tissue damage appears to involve substance P but not CGRP. PAR(2) might be a signaling system in the neuroimmune communication in intestinal ischemia/reperfusion.
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PMID:Protective effect of proteinase-activated receptor 2 activation on motility impairment and tissue damage induced by intestinal ischemia/reperfusion in rodents. 1681 71

Measurement of visceral sensitivity in animals is mainly based on 'pseudoaffective' responses, which are brain stem reflexes. For example, in female, but not male rats, acute partial restraint stress induces hypersensitivity to colorectal distension. Mucosal mast cell density increases in rats after nematode infection or maternal deprivation, and both also induce colon hypersensitivity. Significantly, the proximity between nerves and mast cells has been found to be increased in adult rats submitted to maternal deprivation. Protease activation of the proteinase-activated receptor-2 also increases visceral nociception in rats, suggesting that an increase in paracellular permeability may be the primum movens in several animal models of visceral hypersensitivity. Accumulating evidence suggests that sensitization of visceral afferents is not restricted to the presumed nociceptor population, suggesting that most of the mechanosensitive afferent population can contribute to visceral discomfort and pain. Other inflammation-produced changes (e.g. subunit composition of purine-gated P2X channels) in visceral sensory neurones may also contribute to visceral hypersensitivity. This article discusses use of in vivo strategies (and transgenic mouse models) to reveal putative roles in mechanosensitivity and sensitization for molecules not previously considered to have mechanosensory functions.
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PMID:In vivo and transgenic animal models used to study visceral hypersensitivity. 1728 May 83


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