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)

The activities and expression of protein kinase C isoenzymes were examined in glomerular mesangial cells cultured under high glucose conditions. Exposure of cells to high glucose concentrations (27.8 mmol/l) for more than 3 days resulted in a significant elevation of protein kinase C activities in the membrane fraction. Of the protein kinase C isoenzymes, the levels of protein kinase C alpha significantly increased in the membrane fraction after 3 days of exposure to glucose, and protein kinase C zeta increased after 5 days of exposure. Levels of protein kinase C delta and epsilon remained unchanged and protein kinase, C beta and gamma were not detected. These results indicate that protein kinase C alpha and zeta are translocated under high glucose conditions possibly through different mechanisms.
 ...
PMID:Translocation of protein kinase C alpha and zeta in rat glomerular mesangial cells cultured under high glucose conditions. 798 87

Although myristoylated alanine-rich C kinase substrate (MARCKS), has been employed as an indicator for the activation of protein kinase C (PKC) in intact cells, little is known about its specificity for PKC family members. To address this question, we partially purified human MARCKS from baculovirus-infected cells and compared the kinetic parameters for phosphorylation by PKC isozymes, conventional PKC alpha (cPKC alpha), novel PKC delta (nPKC delta), nPKC epsilon, and atypical PKC zeta (apKC zeta), all of which are distributed in a wide variety of cells. cPKC alpha, nPKC delta, and nPKC epsilon efficiently phosphorylated intact MARCKS protein in vitro. The affinity of MARCKS for cPKC alpha, nPKC delta, and nPKC epsilon was extremely high and decreased in the order alpha > delta > epsilon with Km values of 10.7, 20.7, and 29.8 nM, respectively. The rate of phosphorylation also decreased in the same order. In contrast, a PKC zeta did not phosphorylate MARCKS efficiently, and we were unable to estimate the kinetic parameters. These results suggest that cPKC alpha, nPKC delta, and nPKC epsilon but not a PKC zeta are enzymes that phosphorylate MARCKS in response to PKC activators in intact cells. The structural requirements of MARCKS for efficient phosphorylation by these PKC members were then examined using a peptide that surrounds the phosphorylation site of MARCKS (peptide MARCKS). Interestingly, intact MARCKS showed a 90-150 times lower rate of phosphorylation by PKCs compared with peptide MARCKS, whereas the former showed a 40-180 times higher affinity for these PKC members. This implies that intact MARCKS protein retains a very high affinity for PKC with the sacrifice of its phospho-accepting activity. The structural requirements of PKC were then examined using a calpain-cleaved active fragment of nPKC delta. MARCKS was phosphorylated by the active catalytic fragment as efficiently as by intact nPKC delta, indicating that the kinase domain is sufficient for the high affinity interaction with intact MARCKS. However, gel overlay assay revealed that both intact nPKC delta and its regulatory domain bind to MARCKS, suggesting that both the kinase and regulatory domains of nPKC delta are involved in the high affinity interaction with intact MARCKS protein.
 ...
PMID:Specificity of the high affinity interaction of protein kinase C with a physiological substrate, myristoylated alanine-rich protein kinase C substrate. 798 36

cDNAs of RAC protein kinases (RAC-PK) alpha and beta were cloned from a rat testis cDNA library. The predicted open reading frames encode 480 and 481 amino acids of RAC-PK alpha and beta, respectively, and the rat RAC-PK alpha and beta have sequences conserved among different mammalian species such as the pleckstrin homology domain at their amino-terminal region and the protein-serine/threonine kinase catalytic domain at their carboxyl-terminal region. RNA blot analysis showed wide distribution of two RAC-PK in rat tissues. Immunoprecipitation analysis revealed that RAC-PK alpha and beta associate with protein kinase C zeta through the pleckstrin homology domain in vitro, suggesting the interaction between RAC-PK and protein kinase C.
 ...
PMID:Molecular cloning of rat RAC protein kinase alpha and beta and their association with protein kinase C zeta. 799 18

The purpose of our research is to understand the biochemical basis for dietary enhancement of phorbol ester induced tumor promotion in mice fed high-fat (HF) diet, and the inhibition of promotion in mice fed diets restricted in energy from fat and carbohydrate (ER). The present study assessed the presence of protein kinase C (PKC) isoenzymes in the Sencar mouse epidermis by Western blot and determined the influence of diet on the isoenzymes found. Mice were fed control, HF (24.5% corn oil) or ER (60% of control energy) diets for 6-29 weeks. Our initial studies assessed the immunoreactive levels of PKC alpha, beta, gamma, delta, epsilon and zeta and PKC alpha beta gamma using an antibody to a shared epitope. We detected PKC alpha, epsilon, delta and zeta in sufficient quantity for dietary studies. Dietary fat and energy did not significantly modify the presence of PKC epsilon or delta. We observed a 30% and 40% reduction in PKC alpha in comparison with control diet in cytosolic and particulate fractions respectively, from mice pre-fed ER diet. Reductions of 72% and 82% in cytosolic and particulate PKC were observed respectively with the alpha beta gamma antibody. ER diet reduced the overall amount of PKC zeta in cytosol and particulate by 42% and 59% respectively, with the cytosolic reduction being greater in mice pre-fed the restricted diets for 21-29 weeks. HF diet did not modify the protein levels of the PKC isoenzymes studied. The level of phorbol-12,13-dibutyrate binding to epidermal cells was assessed to determine if the reduction in PKC protein in the epidermis of ER mice would result in altered phorbol binding. Phorbol binding in cells isolated from mice fed ER diet was reduced in mice pre-fed the ER diet for 20-22 weeks in comparison with binding to cells from mice fed control diet. These results suggest that ER diet reduces specific PKC isoenzymes and the binding of phorbol esters in epidermis of mice. These observations may account for the inhibition of phorbol ester promotion of skin tumors in ER mice.
 ...
PMID:Dietary energy restriction and fat modulation of protein kinase C isoenzymes and phorbol ester binding in Sencar mouse epidermis. 800 Dec 28

Recent evidence demonstrates that the protein kinase C zeta (zeta PKC) isoform is required for the activation of nuclear factor kappa B (NF-kappa B) and mitogenic signaling in Xenopus oocytes and mammalian cells. The mechanism whereby zeta PKC regulates NF-kappa B most probably involves the activation of a putative I kappa B kinase of molecular mass approximately 50 kDa, which phosphorylates and inactivates I kappa B. Tumor necrosis factor alpha (TNF alpha) and interleukin-1, besides activating the phospholipase C-mediated breakdown of phosphatidylcholine, also generate ceramide, which is produced by stimulation of sphingomyelin hydrolysis. We show here that exogenous addition of sphingomyelinase (SMase) to NIH-3T3 fibroblasts transactivates a kappa B-dependent chloramphenicol acetyltransferase reporter plasmid, to an extent similar to that produced by TNF alpha or phosphatidylcholine/phospholipase C. More importantly, the ability of SMase to stimulate this parameter is severely impaired by transfection of a zeta PKC kinase-defective dominant negative mutant, which suggests a critical role of zeta PKC in SMase signaling. In keeping with this notion, we also demonstrate here that zeta PKC is activated in vitro by ceramide and in vivo by treatment of NIH-3T3 fibroblasts with SMase.
 ...
PMID:Protein kinase C zeta isoform is critical for kappa B-dependent promoter activation by sphingomyelinase. 803 80

Platelet-activating factor (PAF), a proinflammatory lipid mediator, is a potent airway mucin secretagogue. This study assessed the role of protein kinase C (PKC) in PAF-induced mucin release from primary cultures of feline tracheal epithelial cells (FTEC). Mucin secretion was quantitated by enzyme-linked immunosorbent assay using a monoclonal antibody raised against airway mucin-type glycoproteins. Coincubation of FTEC with PAF (5 microM) and pharmacologic PKC inhibitors, sphingosine, H7, or calphostin C, inhibited PAF-induced mucin secretion at 30 min. The PKC inhibitors produced a concentration-dependent, noncytotoxic inhibition. Exposure of FTEC with the PKC activator phorbol 12-myristate 13-acetate (PMA), failed to increase the release of mucin. Stimulation of FTEC with PAF caused a transient increase of membrane-bound PKC activity after 5 min of stimulation. PMA also induced the translocation of PKC activity from the cytosol to the membrane fraction, which was still present after 15 min of exposure. Determination of the specific PKC isozyme(s) involved in PAF-induced mucin release was performed by immunoblot analysis of the subcellular fractions using a battery of antibodies against various PKC isozymes (anti-PKC alpha, beta, delta, gamma, epsilon, and zeta). We found that PKC zeta (mol wt approximately 70 kD) was a major identifiable PKC isozyme present in the cytosolic fraction of FTEC. Furthermore, PKC zeta isozyme was also found to translocate to the membrane fraction following PAF exposure. Thus, these results demonstrate the crucial role of PKC in the intracellular events that culminate in mucin release following PAF stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Platelet-activating factor induces airway mucin release via activation of protein kinase C: evidence for translocation of protein kinase C to membranes. 804 80

Western blots of human polymorphonuclear leukocyte (PMN) extracts were immunostained with antibodies specific for various protein kinase C (PKC) isoforms. Two bands corresponding to PKC type zeta with apparent molecular masses of 81 kDa and 76 kDa were identified in the cytosolic fraction of resting cells, in addition to PKC types alpha and beta. PKC zeta was apparently abundant, like PKC beta, whereas PKC delta, -epsilon, and -gamma were not detectable. Following short stimulation (5 min) of PMN with phorbol-12-myristate-13-acetate (1 microgram/ml), physical translocation of PKC zeta from the cytosol to the plasma membrane fraction occurred, although this isoform does not bind phorbol esters. These data show that, in addition to the two calcium-dependent isoenzymes alpha and beta, human PMN express a calcium-independent isoenzyme zeta which translocates in stimulated cells, suggesting a role in the regulation of antibacterial activities.
 ...
PMID:Immunochemical identification and translocation of protein kinase C zeta in human neutrophils. 805 May 93

Insulin can stimulate the expression of c-fos and other immediate early genes in many insulin-sensitive cell types. We found previously that this effect of insulin was essentially normal in cells in which protein kinase C (PKC) was down-regulated by 16 h of exposure to 16 microM phorbol 12-myristate 13-acetate (PMA). However, recent studies by other groups have suggested that much of the insulin response was lost in down-regulated cells and that at least part of the remaining response could be due to a species of PKC beta that is resistant to down-regulation. To resolve these discrepancies, we performed PKC enzyme assays and immunoblots on HIRc-B, H4IIEC3, and BC3H-1 cells before and after down-regulation with PMA. PKC enzyme activity was undetectable in the first two cell types after down-regulation; in addition, in all three cells the expressed PKC isozymes other than PKC zeta were completely down-regulated by the PMA exposure. Neither PKC beta 1 nor beta 2 was expressed in any of the cells, as determined by immunoblotting with isotype-specific antibodies. As in our previous studies, c-Fos mRNA accumulation in response to insulin was essentially normal in the down-regulated HIRc-B and H4IIEC3 cells, whereas the response to re-added PMA was completely abolished. PKC zeta was expressed in all three cell types and was not down-regulated by PMA; these and other considerations leave open the possibility that this and other "atypical" PKC isotypes could play a role in insulin action.
 ...
PMID:Protein kinase C isozyme distribution and down-regulation in relation to insulin-stimulated c-fos induction. 806 39

Receptor-mediated elevations of intracellular Ca2+ in endothelial cells may be controlled by a negative feedback mechanism through activation of protein kinase C (PKC). To test this hypothesis, we studied the effects of an activation or inhibition of PKC on the release of nitric oxide (NO) and prostacyclin (PGI2) from cultured bovine and porcine aortic endothelial cells (EC). Preincubation with the PKC activators phorbol-12-myristate-13-acetate (PMA) (3-300 nM) or 1-oleyl-2-acetyl-glycerol (OAG) (30 microM) significantly attenuated the release of NO and PGI2 from EC stimulated with bradykinin (0.3-30 nM), whereas phorbol-12,13-didecanoate (PDD) (30-300 nM), which does not activate PKC, had no effect. UCN-01 (10 nM), a specific PKC inhibitor, significantly augmented the bradykinin-stimulated release of NO from EC. These effects were correlated with a reduced (PMA) or enhanced (UCN-01) elevation of intracellular Ca2+ in response to bradykinin in both types of EC. Neither the PKC activators nor the inhibitor had any effect on resting intracellular Ca2+ or basal endothelial autacoid release. Several isoforms of PKC (namely PKC alpha, PKC delta, PKC epsilon, and PKC zeta) were detected in bovine, human, and porcine EC by immunoblotting analysis with isotype-specific anti-PKC antibodies, which, except PKC epsilon, were predominantly located in the cytosol. Incubation of bovine EC with PMA elicited a significant increase in membrane-bound PKC alpha immunoreactivity, whereas there was no translocation of PKC alpha from the cytosolic to the membrane fraction with bradykinin. As determined by histone phosphorylation, PKC activity was similarly reduced in the cytosol, but increased in the membrane fraction of bovine EC exposed to PMA, whereas bradykinin had no significant effect. These findings indicate that endothelial autacoid release can be modulated by activators and inhibitors of PKC. However, stimulation of EC with bradykinin does not lead to a detectable activation of PKC, suggesting that PKC does not exert a negative feedback in the signal transduction pathway of this receptor-dependent agonist.
 ...
PMID:Modulation of endothelial autacoid release by protein kinase C: feedback inhibition or non-specific attenuation of receptor-dependent cell activation? 810 55

1,25-Dihydroxycholecalciferol (1,25-(OH)2-D3) increases membrane-associated protein kinase C (PKC) activity and immunoreactivity in renal epithelial (Madin Darby bovine kidney, MDBK) cells (Simboli-Campbell, M., Franks, D. J., and Welsh, J. E. (1992) Cell Signalling 4, 99-109). We have now characterized the effects of 1,25-(OH)2-D3 on the subcellular localization of three individual isozymes by immunofluorescence and immunoblotting. Although the total amount of PKC alpha, PKC beta, and PKC zeta are unaffected by 1,25-(OH)2-D3, this steroid hormone induces subcellular redistribution of both PKC alpha and PKC beta. Treatment with 1,25-(OH)2-D3 (100 nM, 24 h) enhances plasma membrane association of PKC alpha and induces translocation of PKC beta to the nuclear membrane. The effects of 1,25-(OH)2-D3 appear to be limited to the calcium-dependent PKC isozymes, since 1,25-(OH)2-D3 has no effect on the calcium independent isozyme, PKC zeta. In contrast to rapid transient PKC translocation seen in response to agents which interact with membrane receptors to induce phospholipid hydrolysis, modulation of PKC alpha and PKC beta is observed after 24 h treatment with 1,25-(OH)2-D3. In MDBK cells, the phorbol ester 12-0-tetradecanoylphorbol-13-acetate (TPA) (100 nM, 24 h) down-regulates PKC alpha and, to a lesser extent, PKC zeta, without altering their subcellular distribution. TPA also induces translocation of PKC beta to the nuclear membrane. MDBK cells treated with 1,25-(OH)2-D3, but not TPA, exhibit enhanced phosphorylation of endogenous nuclear proteins. In addition to the distinct effects of 1,25-(OH)2-D3 and TPA on PKC isozyme patterns, 1,25-(OH)2-D3 up-regulates both the vitamin D receptor and calbindin D-28K, whereas TPA down-regulates the expression of both proteins. These data support the involvement of PKC in the mechanism of action of 1,25-(OH)2-D3 and specifically implicate PKC beta in 1,25-(OH)2-D3-mediated nuclear events.
 ...
PMID:1,25-Dihydroxyvitamin D3 translocates protein kinase C beta to nucleus and enhances plasma membrane association of protein kinase C alpha in renal epithelial cells. 810 62


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>