Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bryostatin 1, a potent activator of protein kinase C, has antitumor activity against murine lymphoma, leukemia, and melanoma. In vitro, this compound stimulates the release of gamma-interferon, interleukins, and hematopoietic growth factors from accessory cells and activates both T- and B-cells. Bryostatin 1 is also able to stimulate neutrophils to undergo oxidative burst and degranulation. Because of the ability of this compound to stimulate the immune system, cause release of immune mediators, and activate neutrophils, we have examined its effect on bacterial infection by using the gram-negative bacterium Salmonella typhimurium in mice. We find that animals given injections i.v. of S. typhimurium have a shortened life span if they are also given injections i.p. of nonlethal doses of bryostatin 1. There is a dose-response relationship with 100 micrograms/kg bryostatin 1 having a greater effect on survival than 40 micrograms/kg. Below 40 micrograms/kg there are no effects on survival. Analysis of the first 4 h of Salmonella infection demonstrates that bryostatin 1 does not affect the blood clearance of the bacterium. However, by day 2 of infection greater numbers of bacteria are found in the livers and spleens of mice given injections of bryostatin 1. By day 5, 10-fold more S. typhimurium bacteria are found in the livers and spleens of mice receiving 40 micrograms/kg of bryostatin 1. To determine whether bryostatin 1 was affecting growth or causing the death of bacteria, we used a Salmonella carrying a plasmid which has a temperature-sensitive origin of replication and is unable to replicate when the bacteria are in mice. This experiment demonstrates that bryostatin 1 represses bacterial killing but does not affect bacterial growth. Bryostatin 1 given i.p. stimulates a transient syndrome of weight loss and diarrhea from which the mice recover and regain weight, suggesting that bryostatin 1 may release a number of important humoral mediators in vivo. The weight loss is exacerbated by Salmonella infection with mice receiving bryostatin 1 and S. typhimurium, in that they lose approximately 33% of body weight prior to death. Thus, at doses used to treat murine tumors, bryostatin 1 treatment does not affect the clearance of S. typhimurium from the blood but does decrease the killing of bacteria in the liver and spleen, leading to early animal death. Such potential effects of bryostatin 1 on the outcome of bacterial infections should be evaluated in ongoing human trials of this agent.
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PMID:In vivo administration of bryostatin 1, a protein kinase C activator, decreases murine resistance to Salmonella typhimurium. 155 18

The pathophysiological mechanism of Campylobacter jejuni (enterotoxigenic) induced secretory diarrhoea remains least understood. To investigate the mechanism(s) involved, the unidirectional fluxes of Na+ and Cl- were measured across the C. jejuni live culture infected and control (non infected) rat ileum (unstriped), in vitro by Ussing technique under short circuit conditions, in the presence or absence of: Ca2+ ionophore A23187 (5 microM), 1-verapamil (100 microM), calmodulin (CaM) antagonist W-7 (100 microM), dantrolene (25 microM), protein kinase C (PKC) activator PMA (100 ng/ml) and H-7 (60 microM), selective inhibitor of PKC. There was net absorption of Na+ and enhanced Cl- secretion in infected animals while in control animals there was net absorption of Na+ and marginal secretion Cl-.Ca2+ ionophore A23187 mimicked the effects of C. jejuni infection whereas 1-verapamil had significant antisecretory effect on Na+ and Cl- secretion in infected animals. In vitro measurement of undirectional 45Ca fluxes in Ussing chamber experiments revealed net absorption of Ca2+ in infected rat ileum as compared to net secretion of Ca2+ in control rat ileum. These observations clearly indicate that there is increased stimulation of Ca2+ uptake from extracellular milieu to the enterocytes during C. jejuni-induced diarrhoea. The intracellular calcium levels (Ca2+]i (as measured by fluorescent probe Fura-2AM) were found to be raised significantly (P < 0.0001) in enterocytes isolated from C. jejuni infected ileum as compared to the enterocytes from control ileum. The observed increase in [Ca2+]i in enterocytes isolated from C. jejuni live culture supernatant treated rat ileum further shows the involvement of enterotoxin in diarrhoeal process. Dantrolene decreased significantly C. jejuni-induced net Na+ and Cl- secretion but it could not reverse it to absorption suggesting the partial involvement of Ca2+ mobilised from intracellular stores in mediating secretion. W-7 failed to inhibit the C. jejuni-induced net Na+ and Cl- secretion. In addition the CaM activity estimated in intestinal microvillar core remained same in both the control and C. jejuni infected animals. This indicates that C. jejuni-induced diarrhoea is not mediated through the activation of Ca(2+)-CaM complex pathway of the Ca2+ messenger system. The PKC activator PMA, induced net secretion of Na+ and Cl- in the control animals but it could not enhance further the C. jejuni-induced Na+ and Cl- secretion, suggesting that there is overlapping effect of PMA and C. jejuni live culture infection.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Calcium and protein kinase C play an important role in Campylobacter jejuni-induced changes in Na+ and Cl- transport in rat ileum in vitro. 772 42

The heat-stable enterotoxin STa of E. coli causes diarrhea by binding to and stimulating intestinal membrane-bound guanylyl cyclase, triggering production of cyclic GMP. Agents which stimulate protein kinase C (PKC), including phorbol esters, synergistically enhance STa effects on cGMP and secretion. We investigated whether PKC causes phosphorylation of the STa receptor in vivo and in vitro. Immunoprecipitation of the STa receptor-guanylyl cyclase was carried out from extracts of T84 colon cells metabolically labelled with [32P]-phosphate using polyclonal anti-STa receptor antibody. The STa receptor was phosphorylated in its basal state, and 32P content in the 150 kDa holoreceptor band increased 2-fold in cells exposed to phorbol ester for 1 h. In vitro, immunopurified STa receptor was readily phosphorylated by purified rat brain PKC. Phosphorylation was inhibited 40% by 5 microM of a synthetic peptide corresponding to the sequence around Ser1029 of the STa receptor, a site previously proposed as a potential PKC phosphorylation site. Treatment of the immunopurified STaR/GC with purified PKC increased STa-stimulated guanylyl cyclase activity 2-fold. We conclude that PKC phosphorylates and activates the STa receptor/guanylyl cyclase in vitro and in vivo; Ser1029 of the STaR/GC remains a candidate phosphorylation site by PKC.
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PMID:Phosphorylation and activation of the intestinal guanylyl cyclase receptor for Escherichia coli heat-stable toxin by protein kinase C. 897 59

Enteropathogenic Escherichia coli (EPEC) consists of a group of diarrhea-producing E. coli strains, common in developing countries, which do not produce classical toxins and are not truly invasive. EPEC strains adhere to mammalian cells in an intimate fashion, trigger a localized increase in intracellular calcium levels, and elevate inositol phosphate production. We hypothesized that these mediators could activate host cell protein kinase C (PKC) and tested this idea in vitro with two cultured human cell lines, HeLa cells and T84 cells. Using a recently described subculturing protocol to "induce" or accelerate EPEC adherence, we infected the cells with EPEC at a multiplicity of infection of approximately 100:1 for 30 to 60 min. Under these conditions, EPEC E2348 increased membrane-bound PKC activity 1.5- to 2.3-fold in HeLa cells and T84 cells, respectively. The increase in membrane-bound PKC activity was accompanied by a decrease in cytosolic PKC activity in EPEC-infected HeLa cells. Nonadherent laboratory E. coli strains such as HB101 and H.S. failed to trigger any consistent change in PKC production, similar to the nonadherent mutant strains derived from E2348, JPN15 (plasmid cured) and CVD206 (eaeA). In addition, immunoblots performed on extracts of T84 cells with a monoclonal antibody against PKC-alpha showed an increased PKC content in membranes of EPEC-infected cells. Finally, EPEC-infected T84 cells showed a 60% increase in responsiveness to the E. coli heat-stable toxin. We conclude that mediators produced in response to EPEC adherence activate PKC in intestinal and nonintestinal cells.
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PMID:Activation of host cell protein kinase C by enteropathogenic Escherichia coli. 923 87

Enterohemorrhagic Escherichia coli (EHEC) infection is associated with watery diarrhea and can lead to complications, including hemorrhagic colitis and the hemolytic-uremic syndrome. The mechanisms by which these organisms produce diarrheal disease remain to be elucidated. Changes in T84 epithelial cell electrophysiology were examined following EHEC infection. T84 cell monolayers infected with EHEC O157:H7 displayed a time-dependent decrease in transepithelial resistance. Increases in the transepithelial flux of both [3H]mannitol and 51Cr-EDTA accompanied the EHEC-induced decreases in T84 resistance. Altered barrier function induced by EHEC occurred at the level of the tight junction since immunofluorescent staining of the tight-junction-associated protein ZO-1 was disrupted when examined by confocal microscopy. Decreased resistance induced by EHEC involved a protein kinase C (PKC)-dependent pathway as the highly specific PKC inhibitor, CGP41251, abrogated the EHEC-induced drop in resistance. PKC activity was also increased in T84 cells infected with EHEC. Calmodulin and myosin light chain kinase played a role in EHEC-induced resistance changes as inhibition of these effector molecules partially reversed the effects of EHEC on barrier function. These studies demonstrate that intracellular signal transduction pathways activated following EHEC infection link the increases in T84 epithelial permeability induced by this pathogen.
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PMID:Signal transduction pathways involved in enterohemorrhagic Escherichia coli-induced alterations in T84 epithelial permeability. 952 98

This review discuss some recent findings in the study of the regulation of the permeability of the intestinal epithelial layer. Comparison of electrical phenomena and transport of macromolecules suggests that secretory activity and increased transepithelial transport of macromolecules are related when secretion is mediated by the Ca2+ and PKC dependent pathways. The transport of the macromolecules is via the transcellular and via the paracellular route. The barrier function of the intestinal epithelium may be diminished during nervous (acetylcholine)- and immuno-(histamine) mediated secretion. It is hypothesised that some bacterial toxins may also induce Ca2+ and PKC dependent secretion and thereby can reduce the epithelial barrier. The cAMP and cGMP mediated secretion, which can be recognised by their long-lasting transepithelial potential changes, are not coupled to increased transepithelial transport of macromolecules. Some forms of secretory diarrhea may therefore be related to the development of food-allergy or inflammation.
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PMID:Correlation between electrophysiological phenomena and transport of macromolecules in intestinal epithelium. 968 25

Chronic gastrointestinal diseases such as ulcerative colitis and Crohn's disease are characterized by severe diarrhea. Mucosal biopsies of these patients show enhanced levels of cytokines, secreted by infiltrated inflammatory cells. In this study, we investigated the effect of the cytokine tumor necrosis factor-alpha (TNF-alpha) on ion secretion in human intestinal epithelial cells. The conventional microelectrode technique in the cell line HT29cl. 19A was used, which allows for simultaneous measurements of transepithelial potential difference and intracellular potential difference across the apical membrane. Preincubation (2-78 h) with 10 ng/ml TNF-alpha did not change basal secretory activity. However, the secretory response to the muscarinic receptor agonist carbachol was strongly increased after exposure to TNF-alpha. Application of the protein kinase C (PKC) inhibitor GF 109203X (bisindolylmaleimide I) inhibited the response to carbachol as well as the TNF-alpha-potentiated response, indicating that PKC mediates the effect of carbachol in this cell line. Propranolol, a substance that inhibits the phospholipase D (PLD) pathway, strongly reduced the response to muscarinic stimulation and its potentiation by TNF-alpha. The results indicate that activation of PLD is involved in ion secretion induced by muscarinic receptor activation and that TNF-alpha can potentiate this pathway.
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PMID:TNF-alpha potentiates the ion secretion induced by muscarinic receptor activation in HT29cl.19A cells. 1071 34

Many pathogens causing diarrhea do so by modulating ion transport in the gut. Respiratory pathogens are similarly associated with disturbances of fluid balance in the respiratory tract, although it is not known whether they too act by altering epithelial ion transport. Here we show that influenza virus A/PR/8/34 inhibits the amiloride-sensitive Na(+) current across mouse tracheal epithelium with a half-time of about 60 min. We further show that the inhibitory effect of the influenza virus is caused by the binding of viral hemagglutinin to a cell-surface receptor, which then activates phospholipase C and protein kinase C. Given the importance of epithelial Na(+) channels in controlling the amount of fluid in the respiratory tract, we suggest that down-regulation of Na(+) channels induced by influenza virus may play a role in the fluid transport abnormalities that are associated with influenza infections.
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PMID:Influenza virus inhibits amiloride-sensitive Na+ channels in respiratory epithelia. 1096 54

Infections with Shiga toxin (Stx)-producing bacteria cause bloody diarrhea which may progress to life-threatening complications, including acute renal failure and neurological abnormalities. The precise mechanism of disease progression is unclear, although evidence suggests that the localized production of the host proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha) and interleukin-1 may exacerbate toxin-mediated vascular damage. Purified Stxs have been demonstrated to elicit proinflammatory cytokine synthesis from human peripheral blood mononuclear cells and monocytic cell lines in vitro. To understand toxin-monocyte interactions required for cytokine synthesis, we have treated differentiated THP-1 cells with purified wild-type toxins, enzymatic mutants, or B subunits and measured TNF-alpha production. Our data suggest that A subunit enzymatic activity is essential for cytokine production. THP-1 cells were treated with a series of protein kinase C (PKC), PKA, and protein tyrosine kinase inhibitors to examine the role of intracellular signaling molecules in Stx-mediated cytokine production. Treatment of cells with PKC and tyrosine kinase inhibitors blocked TNF-alpha secretion by Stx-stimulated THP-1 cells. Stx treatment directly activated PKC, which occurred at a point upstream of transcriptional activation of the gene encoding TNF-alpha.
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PMID:Shiga toxin-induced tumor necrosis factor alpha expression: requirement for toxin enzymatic activity and monocyte protein kinase C and protein tyrosine kinases. 1094 42

Thermostable direct haemolysin (TDH) produced by Vibrio parahaemolyticus is thought to play an important role in the severe diarrhoea caused by this organism. This study investigated the enterotoxicity of TDH for human intestinal cells. Addition of TDH to the mucosal side of human colonic tissue in Ussing chambers caused increased short circuit currents (Isc), a process that was inhibited by 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS), an inhibitor of Ca2+ -activated chloride (Cl-) channels. With human colonic epithelial (Caco-2) cells, high Isc and intracellular Ca2+ concentrations ([Ca2+]in) were detected after the addition of TDH to the apical side of the cell monolayer. The Isc decreased with the addition of DIDS, but not with glybenclamide, 5-nitro-2-(3-phenylpropylamino) benzoic acid, or gadolinium chloride. No Isc increase with TDH was observed when the Cl- in the medium was replaced by gluconate or when Ca2+ was depleted. Similarly, TDH did not raise [Ca2+]in after depletion of extracellular Ca2+. R7, a mutant form of TDH, reduced the effects of TDH on Isc and [Ca2+]in, as did protein kinase C (PKC) inhibitors. Thus, TDH increases Cl- secretion in human colonic epithelial cells, apparently through mechanisms involving cell binding and Ca2+ influx, followed by elevation of [Ca2+]in associated with PKC phosphorylation.
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PMID:Mechanisms of chloride secretion induced by thermostable direct haemolysin of Vibrio parahaemolyticus in human colonic tissue and a human intestinal epithelial cell line. 1096 28


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