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

This study demonstrates the ability of phospholipase C from Clostridium perfringens to stimulate the generation of platelet-activating factor (PAF-acether) in cultured intestinal epithelial cells (INT 407). Cells were exposed to phospholipase C for up to 60 min, and the content of PAF-acether within the cells and in the extracellular medium was determined. Phospholipase C caused a time-dependent formation of PAF-acether within the cells and also release of PAF-acether to the medium. In contrast, phospholipase C did not affect the cellular acetylhydrolase activity or the ability of the cells to metabolize extracellularly added 14C-PAF-acether. These findings suggest the possibility that intestinal epithelial cells, when stimulated with a naturally occurring intestinal bacterial toxin, generate and release PAF-acether. The possibility that this might contribute to the pathophysiology of inflammatory bowel disease is discussed.
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PMID:Phospholipase C from Clostridium perfringens stimulates formation and release of platelet-activating factor (PAF-acether) in cultured intestinal epithelial cells (INT 407). 194 65

The mechanisms by which phospholipase C from Clostridium perfringens stimulates release of arachidonic acid (AA) in cultured intestinal epithelial cells (INT-407) were investigated. INT-407 cells were first allowed to incorporate 14C-labeled AA into their phospholipids; the labeled cells were then exposed to phospholipase C, and the release of free 14C-AA was determined. Phospholipase C caused a rapid (3 min) intracellular rise of free 14C-AA, followed by a considerable, dose- and time-dependent release of 14C-AA into the extracellular medium. For comparison, the calcium ionophore A23187 also caused a rapid mobilization of free 14C-AA, but a much lower extracellular 14C-AA release than phospholipase C during longer (1 h) incubation. The 14C-AA release was accompanied by a degradation of 14C-myo-inositol-labeled phosphatidylinositols and was reduced by the protein kinase C inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7). Both phospholipase C- and A23187-stimulated 14C-AA release was associated with degradation of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol and was reduced by nordihydroguaiaretic acid and 4-bromophenacyl bromide, two known phospholipase A2 inhibitors. In addition, the 14C-AA release was reduced by the calmodulin inhibitors trifluoperazine, compound 48/80, and N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W-7). These findings indicate that phospholipase C from C. perfringens stimulates phospholipase A2-mediated AA release from human intestinal epithelial cells and suggest that this stimulation is brought about via processes involving phosphatidylinositol breakdown and activation of calmodulin and protein kinase C. It is possible that this phospholipase C-evoked AA release may contribute to the mucosal pathologic condition in diseases with altered intestinal microbial flora.
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PMID:Phospholipase C from Clostridium perfringens stimulates phospholipase A2-mediated arachidonic acid release in cultured intestinal epithelial cells (INT 407). 211 Jun 84

The release of free arachidonic acid (AA) in cultured intestinal epithelial cells (INT 407) was investigated. INT-407 cells were first incubated overnight with radiolabeled 14C-AA, and most of the incorporated 14C-AA esterified into phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol. Labeled cells were then exposed to different stimulating agents and the release of free 14C-AA determined. The calcium ionophore A23187 caused a dose-dependent AA release that was preceded by a rapid uptake and a subsequent efflux of 45Ca2+. By contrast, phospholipase C from Clostridium perfringens caused a great AA release that was accompanied by an apparent uptake and a sustained intracellular accumulation of 45Ca2+. The cells alos released AA when exposed to the protein kinase C activator, 4 beta-phorbol-12-myristate-13-acetate (PMA), and this agent, like the diacylglycerol 1-oleoyl-2-acetyl-rac-glycerol, significantly potentiated the AA release caused by A23187. Not only A23187-mediated but also phospholipase C- and PMA-mediated AA release was inhibited by 4-bromophenacyl bromide, a known phospholipase A2 inhibitor. These findings, taken together, indicate that AA release in intestinal epithelial cells can be caused by (i) Ca2+-mediated phospholipase activation, (ii) products of phospholipase C activity, and (iii) stimulation of protein kinase C. It is suggested, therefore, that AA release in intestinal epithelial cells is governed by intracellular Ca2+, protein kinase C-mediated protein phosphorylation, and activation of phospholipase A2.
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PMID:Phospholipase activation and arachidonic acid release in cultured intestinal epithelial cells (INT 407). 250 36

The mechanisms by which phospholipase C from Clostridium perfringens stimulates the formation of platelet-activating factor (PAF-acether) in cultured intestinal epithelial cells (INT 407) were investigated. Although stimulation with phospholipase C caused a significant formation of PAF-acether, there was no significant increase in the cellular levels of lysoPAF-acether after stimulation. Moreover, when cells prelabeled with 3H-1-O-alkyl-2-acyl-sn-glycerophosphocholine were stimulated with phospholipase C, the 3H-lysoPAF-acether content was not increased in stimulated cells as compared with unstimulated cells. When cells were preincubated with the calmodulin inhibitor trifluoperazine (TFPA), the protein kinase C inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), or the combined phospholipase A2-inhibitor and lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) before stimulation with phospholipase C, the PAF-acether formation was significantly decreased. The phospholipase A2 inhibitor 4-bromophenacyl bromide (BPB), on the other hand, had no significant effect on the PAF-acether formation. Preincubation with NDGA also decreased the levels of lysoPAF-acether, whereas BPB, H7, or TFPA had no such effect. These findings indicate that stimulation of acetyltransferase activity with increased acetylation of lysoPAF-acether may be one way by which phospholipase C from C. perfringens stimulates formation of PAF-acether in INT 407 cells.
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PMID:Phospholipase C from Clostridium perfringens stimulates acetyltransferase-dependent formation of platelet-activating factor in cultured intestinal epithelial cells (INT 407). 820 84

Tumor necrosis factor-alpha (TNF-alpha), a known pro-inflammatory cytokine, has been suggested to play a role in the pathogenesis of inflammatory bowel disease (IBD) by mediating damage to the intestinal epithelial cells. The present study demonstrates that TNF-alpha potentiates release and metabolism of 14C-labeled arachidonic acid (14C-AA) in cultured intestinal epithelial cells (INT 407). Although TNF-alpha on its own was but a weak stimulator of cellular 14C-AA turnover, it significantly potentiated the release of 14C-AA and 14C-labeled prostaglandin E2(14C-PGE2) after stimulation with three known phospholipase A2 activators: phospholipase. C from Clostridium perfringens, the calcium ionophore A23187, and the phorbol ester 4-beta-phorbol-12-myristate-13-acetate (PMA). The phospholipase A2 inhibitor quinacrine significantly reduced both AA and PGE2 release after combined stimulation with phospholipase C and TNF-alpha. In contrast to its effect on the AA turnover, TNF-alpha did not affect the phospholipase C-stimulated production of platelet-activating factor (PAF-acether). Taken together, these findings indicate that a) TNF-alpha potentiates phospholipase A2-stimulated AA release from cultured intestinal epithelial cells; b) TNF-alpha may stimulate phospholipase A2-dependent AA release without affecting the formation of PAF-acether and c) pretreatment with TNF-alpha potentiates the formation of PGE2 after stimulation with phospholipase A2 activators. In summary, the present investigation points to the possibility that TNF-alpha may stimulate intestinal epithelial cells to produce biologically active AA metabolites and that this stimulation may be modulated by components of the intestinal luminal content, like bacterial toxins.
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PMID:Tumor necrosis factor-alpha potentiates phospholipase A2-stimulated release and metabolism of arachidonic acid in cultured intestinal epithelial cells (INT 407). 848 66

In the present study, the role of a fimbrial galactose-specific adhesin of the T7 strain of enteroaggregative Escherichia coli (EAEC-T7) in the signal transduction pathways in human small intestinal epithelial cells (INT-407) was explored. The adhesin was purified by anion exchange chromatography using a Mono Q HR5/5 column in the AKTA purifier system. The characteristic stacked brick pattern of aggregative adherence of EAEC-T7 to INT-407 cells was found to be inhibited in the presence of immunoglobulin G against the purified adhesin as well as d-galactose. The adhesin induced a significant increase in the intracellular calcium concentration [Ca(2+)](i) in INT-407 cells, which was reduced in the presence of dantrolene (inhibitor of intracellular calcium stores), verapamil, calciseptin (calcium channel blockers) as well as neomycin [inhibitor of phospholipase C (PLC)]. Further, an increased level of PLCgamma1 and inositol 1,4,5-tri phosphate as well as enhanced activity of protein kinase C (PKC) in the adhesin-stimulated cells were found to be downregulated in the presence of neomycin and U73122 (inhibitors of PLC) and H-7 (inhibitor of PKC), respectively. The adhesin could also induce interleukin-8 secretion from INT-407 cells, which was inhibited in the presence of dantrolene as well as staurosporin (inhibitor of PKC). Collectively, our results have suggested that the galactose-specific adhesin-induced signal transduction pathway might play a crucial role in the EAEC-induced pathogenesis.
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PMID:Cellular response induced by a galactose-specific adhesin of enteroaggregative Escherichia coli in INT-407 cells. 1915 27