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)

Dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) in humans is frequently associated with progressive liver disease, which appears to result from obstruction of biliary ducts with mucous material. CFTR in the liver is expressed in the biliary epithelium. With the use of a mouse model for cystic fibrosis (CF) we have studied the relationship between CFTR expression and glycoprotein secretion in primary culture of mouse gallbladder epithelial cells (MGBC) MGBC in culture maintain a well-differentiated phenotype as shown by microscopy. The cells produce CFTR mRNA to levels comparable to the intact tissue. With patch-clamp analysis we could frequently observe a linear protein kinase A-regulated Cl- channel that shows all the major characteristics of human CFTR, although its conductance is lower (5 pS compared with 8 pS). MGBC in culture produce and secrete high molecular weight glycoproteins (HMG) in a time-dependent and temperature-sensitive manner. Secretion of HMG was not stimulated significantly by either adenosine 3',5'-cyclic monophosphate (cAMP), Ca2+, or protein kinase C agonists in this system. High concentrations (3 mM) of extracellular ATP stimulated secretion threefold, but low concentrations (0.3 mM) had no effect. Approximately one-third of the HMG produced and secreted consisted of mucin. Cultured MGBC from CFTR-deficient mice produced and secreted mucin to a similar extent as normal cells. We conclude that cultured mouse gallbladder cells are a convenient model to study both CFTR function and mucin secretion. In this system, we found no evidence for a direct link between mucin secretion and CFTR activity, as has been suggested for other cell types.
 ...
PMID:CFTR expression and mucin secretion in cultured mouse gallbladder epithelial cells. 899 52

Extracellular nucleotides stimulate mucin release by binding to the P2u receptor coupled to phospholipase C via G proteins (Br. J. Pharmacol. 103:1053-1056, 1991; Am. J. Respir. Cell Mol. Biol. 8:121-125, 1993). In the present study, we intended to investigate pathways downstream to the phospholipase C activation which is responsible for adenosine triphosphate (ATP)-induced mucin release in hamster tracheal epithelial cells in primary culture. We have found that: (1) Ca2+ ionophores (A23187 and ionomycin) did not affect mucin release even at 1 microM; (2) thapsigargin (10 microM), either alone or in combination with ATP (20 microM), did not enhance mucin release over its respective control group; (3) pretreatment of hamster tracheal surface epithelial (HTSE) cells with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM) (50 microM) did not inhibit ATP-induced mucin release; (4) 4beta-phorbol 12alpha-myristate 13-acetate (PMA, 1 microM) stimulated mucin release and its effect was completely blocked by protein kinase C inhibitors such as sphingosine (10 microM) and calphostin C (0.1 microM), whereas ATP-induced mucin release was blocked, only in part, by these inhibitors; (5) desensitization of protein kinase C by pretreatment with PMA inhibited the PMA-induced mucin release completely, however, ATP-induced mucin release was inhibited only partially. We conclude that mucin release by ATP does not require an increase in the intracellular Ca2+ level but involves the activation of protein kinase C. The results also suggest the presence of another mechanism separate from the phospholipase C-protein kinase C pathway for the ATP-induced mucin release.
 ...
PMID:ATP-induced mucin release from cultured airway goblet cells involves, in part, activation of protein kinase C. 903 27

The phorbol ester, phorbol 12-myristate 13-acetate (PMA), induces mucin secretion in the colonic tumor cell line T84 in a Ca(2+)-independent manner. To determine whether a specific protein kinase C (PKC) isoform is involved in colonic cells, we compared PMA-dependent mucin secretion by three human colonic tumor cell lines (T84, HT-29/A1, and LS 180) with the expression of PKC isoforms alpha, beta, delta, epsilon, and zeta, previously identified in human colon (L. A. Davidson, Y. H. Jiang, J. D. Derr, H. Aukema, J. R. Lupton, and R. S. Chapkin. Arch. Biochem. Biophys. 312:547-553, 1994). In each cell line PMA (10(-7) M) caused mucin secretion within 30 min. PMA-dependent mucin secretion was three to four times greater from HT-29/A1 and T84 cells than from LS 180 cells. All three-cell lines contained mRNA for PKC-alpha, PKC-epsilon, and PKC-zeta but not PKC-beta or -delta. Each cell line also expressed PKC-alpha, -epsilon, and -zeta protein. PKC-epsilon expression (mRNA and protein) was three to four times greater in HT-29/A1 and T84 cells than in LS 180 cells, correlating with PMA-responsive mucin secretion, whereas all cell lines contained similar levels of PKC-alpha mRNA and protein. When cells were stimulated by PMA, only PKC-epsilon was translocated from cytosol to membrane fractions early enough to stimulate mucin secretion. Because PKC-epsilon is also a Ca(2+)-independent isoform, it is likely to mediate mucin exocytosis in colonic cells.
 ...
PMID:Protein kinase C-epsilon is the likely mediator of mucin exocytosis in human colonic cell lines. 903 73

Ocular surface mucin is secreted from both goblet cells in the conjunctival epithelium and corneal epithelial cells. To clarify its mechanism of secretion in corneal epithelial cells, a rat cornea organ culture system was used to evaluate the second messenger roles of cyclic-AMP (cAMP), cyclic-GMP (cGMP) and protein kinase C (PKC) in modulating mucin-like glycoprotein secretion. Rat cornea sections (3 mm diameter) were cultured in TC-199 medium, and radiolabeled with sodium sulfate for 18 hr. After washing, the corneas were treated with various second messenger modulating agents for 30 min. The culture media were reacted with Dolichos biflorus (DBA)-lectin, and mucin-like glycoprotein was isolated. Then the radioactivity of DBA-binding mucin-like glycoprotein was isolated. Then the radioactivity of DBA-binding mucin-like glycoprotein was measured. There was a time-dependent increase in mucin-like glycoprotein was measured. There was a time-dependent increase in mucin-like glycoprotein secretion, whereas after corneal epithelial debridement the secretion was markedly inhibited by 81%. Mucin-like glycoprotein secretion was stimulated in a dose-dependent manner following elevation of cAMP levels by exposure to either forskolin, dibutyryl cAMP or 3-isobutyl-1-methylxanthine. Concomitant exposure to the cAMP dependent protein kinase inhibitor, KT5720 completely inhibited their stimulatory effects. Neither exposure to dibutyryl cGMP nor nitroprusside affected mucin-like glycoprotein secretion. Stimulation by PKC, phorbol 12, 13-dibutyrate (PDBu) also increased mucin-like glycoprotein secretion in a dose-dependent fashion. The PKC inhibitor, calphostin C completely inhibited the stimulation by PDBu of mucine-like glycoprotein secretion. These results demonstrate that corneal epithelial cells secrete mucin-like glycoprotein, which is mediated by cAMP and PKC signal transduction pathways.
 ...
PMID:Mucin-like glycoprotein secretion is mediated by cyclic-AMP and protein kinase C signal transduction pathways in rat corneal epithelium. 962 98

Mucin secretion by airway goblet cells is under the control of apical P2Y2, phospholipase C-coupled purinergic receptors. In SPOC1 cells, the mobilization of intracellular Ca2+ by ionomycin or the activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate (PMA) stimulates mucin secretion in a fully additive fashion [L. H. Abdullah, J. D. Conway, J. A. Cohn, and C. W. Davis. Am. J. Physiol. 273 (Lung Cell. Mol. Physiol. 17): L201-L210, 1997]. This apparent independence between PKC and Ca2+ in the stimulation of mucin secretion was tested in streptolysin O-permeabilized SPOC1 cells. These cells were fully competent to secrete mucin when Ca2+ was elevated from 100 nM to 3.1 microM for 2 min following permeabilization; the Ca2+ EC50 was 2.29 +/- 0.07 microM. Permeabilized SPOC1 cells were exposed to PMA or 4alpha-phorbol at Ca2+ activities ranging from 10 nM to 10 microM. PMA, but not 4alpha-phorbol, increased mucin release at all Ca2+ activities tested: at 10 nM Ca2+ mucin release was 2.1-fold greater than control and at 4.7 microM Ca2+ mucin release was maximal (3.6-fold increase). PMA stimulated 27% more mucin release at 4.7 microM than at 10 nM Ca2+. Hence, SPOC1 cells possess Ca2+-insensitive, PKC-dependent, and Ca2+-dependent PKC-potentiated pathways for mucin granule exocytosis.
 ...
PMID:Ca2+ and protein kinase C activation of mucin granule exocytosis in permeabilized SPOC1 cells. 968 60

We recently reported that bile salts play a role in the regulation of mucin secretion by cultured dog gallbladder epithelial cells. In this study we have examined whether bile salts also influence mucin secretion by the human epithelial colon cell line LS174T. Solutions of bile salts were applied to monolayers of LS174T cells. Mucin secretion was quantified by measuring the secretion of [3H]GlcNAc labeled glycoproteins. Both unconjugated bile salts as well as taurine conjugated bile salts stimulated mucin secretion by the colon cells in a dose-dependent fashion. Hydrophobic bile salts were more potent stimulators than hydrophilic bile salts. Free (unconjugated) bile salts were more stimulatory compared with their taurine conjugated counterparts. Stimulation of mucin secretion by LS174T cells was found to occur at much lower bile salt concentrations than in the experiments with the dog gallbladder epithelial cells. The protein kinase C activators PMA and PDB had no stimulatory effect on mucin secretion. We conclude that mucin secretion by the human colon epithelial cell line LS174T is regulated by bile salts. We suggest that regulation of mucin secretion by bile salts might be a common mechanism, by which different epithelia protect themselves against the detergent action of bile salts, to which they are exposed throughout the gastrointestinal tract.
 ...
PMID:Mucin secretion by the human colon cell line LS174T is regulated by bile salts. 988 2

Tumor necrosis factor (TNF)-alpha, a pluripotent cytokine implicated in the pathogenesis of airway inflammation, has been shown to provoke hypersecretion of mucin by airway epithelial cells in vitro. In this study, we investigated potential signaling pathways mediating TNF-alpha-induced mucin secretion using guinea pig tracheal epithelial (GPTE) cells in air-liquid interface culture. Exogenously applied TNF-alpha (human recombinant) stimulated mucin secretion in a concentration-dependent manner, with maximal effects at 10 to 15 ng/ml (286 to 429 U/ml). The pathway of stimulated secretion appeared to involve generation of intracellular nitric oxide (NO), activation of soluble guanylate cyclase (GC-S), production of cyclic guanosine monophosphate (cGMP), and activation of cGMP-dependent protein kinase (PKG). TNF-alpha increased production of nitrite and nitrate by GPTE cells; both mucin secretion and cGMP production were attenuated by NG-monomethyl-L-arginine (1 mM), a competitive inhibitor of nitric oxide synthase (NOS), or by the GC-S inhibitor LY83583 (50 microM); and mucin secretion in response to TNF-alpha or to the cGMP analogue dibutyryl cGMP (100 and 500 microM) was attenuated by the specific PKG inhibitor KT5823 (1 microM). Increased mucin secretion and increased cGMP production in response to TNF-alpha both appeared to be mediated by a phospholipase C that hydrolyzes phosphatidylcholine (PC-PLC), and by protein kinase C (PKC), since both responses were attenuated by either D609 (10 and 20 microg/ml), a specific PC-PLC inhibitor, or by each of three PKC inhibitors: Calphostin C (0.3 and 0.5 microM), bisindoylmaleimide (GF 109203X, Go 6850; 20 nM), or Ro31-8220 (10 microM). Collectively, the results suggest that TNF-alpha stimulates secretion of mucin by GPTE cells via a mechanism(s) dependent on PC-PLC and PKC, and involving activation of NOS, generation of NO, production of cGMP, and activation of PKG.
 ...
PMID:Tumor necrosis factor-alpha stimulates mucin secretion and cyclic GMP production by guinea pig tracheal epithelial cells in vitro. 1003 Aug 39

Bronchitis, asthma, and cystic fibrosis, marked by inflammation and mucus hypersecretion, can be caused or exacerbated by airway pathogens or irritants including acrolein, an aldehyde present in tobacco smoke. To determine whether acrolein and inflammatory mediators alter mucin gene expression, steady-state mRNA levels of two airway mucins, MUC5AC and MUC5B, were measured (by RT-PCR) in human lung carcinoma cells (NCI-H292). MUC5AC mRNA levels increased after >/=0.01 nM acrolein, 10 microM prostaglandin E2 or 15-hydroxyeicosatetraenoic acid, 1.0 nM tumor necrosis factor-alpha (TNF-alpha), or 10 nM phorbol 12-myristate 13-acetate (a protein kinase C activator). In contrast, MUC5B mRNA levels, although easily detected, were unaffected by these agonists, suggesting that irritants and associated inflammatory mediators increase mucin biosynthesis by inducing MUC5AC message levels, whereas MUC5B is constitutively expressed. When transcription was inhibited, TNF-alpha exposure increased MUC5AC message half-life compared with control level, suggesting that transcript stabilization is a major mechanism controlling increased MUC5AC message levels. Together, these findings imply that irritants like acrolein can directly and indirectly (via inflammatory mediators) increase airway mucin transcripts in epithelial cells.
 ...
PMID:Regulation of human airway mucins by acrolein and inflammatory mediators. 1019 52

Antibodies against MUC2, MUC3, and MUC5AC peptide epitopes stained the secretory contents of all goblet cells in the human colon-derived HT29-18N2 cell line. In contrast, four carbohydrate-specific monoclonal antibodies stained mucin glycoforms in consistent subsets of goblet cells. Cholinergic agonist-evoked decreases in total mucin stores were not always mirrored by proportional changes in mucin glycoforms in the same monolayers. Selective secretion of mucin glycoforms did not result from differences in receptor distribution, since cholinergic stimulation was found to increase intracellular free calcium in all cells and selective secretion was also observed when the cells were directly stimulated with the protein kinase C activator phorbol myristate acetate. The results demonstrate that goblet cells cycle through transient periods in which their exocytotic response is unresponsive to cholinergic or protein kinase C-mediated stimuli. Goblet cells replenished intracellular mucin stores to control levels within 1 h, but the relative proportion of mucin glycoforms was not always restored until 24 h after stimulation.
 ...
PMID:Selective secretion and replenishment of discrete mucin glycoforms from intestinal goblet cells. 1040 67

Treatment of HT-29 cells with phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C (PKC), induces MUC2 expression. To investigate the role of PKC in regulating mucin genes in intestinal cells, we examined the regulation of MUC1, MUC2, MUC5AC, MUC5B, and MUC6 expression in two human mucin-producing colonic cell lines, T84 and HT29/A1. T84 and HT29/A1 cells (at 80-90% confluency) were exposed to 100 nM PMA for 0, 3, and 6 h. Twofold or greater increases in mRNA levels for MUC2 and MUC5AC were observed in both cell lines during this time period, whereas the levels of MUC1, MUC5B, and MUC6 mRNAs were only marginally affected. These results indicated that PKC differentially regulates mucin gene expression and that it may be responsible for altered mucin expression. Our previous results suggested that the Ca(2+)-independent PKC-epsilon isoform appeared to mediate PMA-regulated mucin exocytosis in these cell lines. To determine if PKC-epsilon was also involved in MUC2/MUC5AC gene induction, HT29/A1 cells were stably transfected with either a wild-type PKC-epsilon or a dominant-negative ATP-binding mutant of PKC-epsilon (PKC-epsilon K437R). Overexpression of the dominant-negative PKC-epsilon K437R blocked induction of both mucin genes, whereas PMA-induced mucin gene expression was not prevented by overexpression of wild-type PKC-epsilon. PMA-dependent MUC2 mucin secretion was also blocked in cells overexpressing the dominant-negative PKC-epsilon K437R. On the basis of these observations, PKC-epsilon appears to mediate the expression of two major gastrointestinal mucins in response to PMA as well as PMA-regulated mucin exocytosis.
 ...
PMID:Induction of mucin gene expression in human colonic cell lines by PMA is dependent on PKC-epsilon. 1056 10


<< Previous 1 2 3 4 5 6 7 8 9 Next >>