Effects of Asbestos on Specific Binding of Phorbol Ester Tumor Promoter and Protein Kinase C Activity in Hamster Tracheal Epithelial (HTE) Cells

1989 ◽  
pp. 433-437 ◽  
Author(s):  
M. Perderiset ◽  
J. P. Marsh ◽  
B. T. Mossman
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Ester ◽  
Specific Binding ◽  
Tumor Promoter ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Tracheal Epithelial

scholarly journals Post-transcriptional regulation of apolipoprotein E expression in mouse macrophages by phorbol ester

1993 ◽  
Vol 292 (1) ◽  
pp. 105-111 ◽  
Author(s):  
L Dory
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Apolipoprotein E ◽  
Phorbol Ester ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Mouse Macrophages ◽  
Apoe Expression

Phorbol ester-mediated differentiation of THP-1 cells (a human monocytic cell line) into mature macrophages is associated with a transcriptional induction of apolipoprotein E (apoE) expression [Auwerx, Deeb, Brunzell, Peng and Chait (1988) Biochemistry 27, 2651-2655]. Endotoxin, on the other hand, which may also act through activation of protein kinase C, is a potent inhibitor of apoE expression in mouse macrophages [Werb and Chin (1983) J. Biol. Chem. 258, 10642-10648]. The present experiments examine the effect of phorbol ester, an activator of protein kinase C, on the apoE expression in mouse thioglycollate-elicited peritoneal macrophages. Phorbol ester inhibits apoE expression in a specific, time- and dose-dependent manner. A 75% inhibition in the rate of apoE secretion, but not that of total protein, was observed following a 4.5 h incubation with 160 nM phorbol ester, although nearly full inhibition was obtained with 40 nM. The changes in apoE secretion were paralleled by similar changes in apoE synthesis, indicating synthesis as the primary site of action. The decreased rates of apoE synthesis are shown not to be due to increased apoE degradation. The profound inhibition of apoE synthesis was not accompanied by significant changes in apoE mRNA levels at any concentration of phorbol ester (up to 16 microM), or length of treatment (up to 24 h), suggesting a post-transcriptional locus of regulation of apoE expression. Although the early changes in apoE synthesis correlate with increased microsomal protein kinase C activity, the suppression of apoE expression persists even during conditions of nearly complete (> 95%) loss of protein kinase C activity, suggesting that the direct or indirect effect of protein kinase C on apoE expression is mediated by a stable phosphorylated protein, or that the observed effects are mediated through a protein kinase C species that is not readily downregulated by phorbol esters. The presented studies clearly demonstrate the potential importance of the translational regulation of apoE expression through the protein kinase C signal transduction pathway.

Phorbol ester binding and protein kinase c activity in aging rat brain

1988 ◽  
Vol 20 ◽  
pp. 27
Author(s):  
F. Battaini ◽  
R. Del Vesco ◽  
A. Gagnoni ◽  
S. Govoni ◽  
M. Trabucchi
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Rat Brain ◽  
Phorbol Ester ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Aging Rat

scholarly journals Phorbol ester binding and protein kinase C activity in normal and transformed human keratinocytes

1987 ◽  
Vol 172 (1) ◽  
pp. 146-157 ◽  
Author(s):  
G.T. Snoek ◽  
J. Boonstra ◽  
M. Ponec ◽  
S.W. de Laat
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Ester ◽  
Human Keratinocytes ◽  
Kinase C ◽  
Protein Kinase C Activity

scholarly journals Comparison of effects of phorbol esters and glucose on protein kinase C activation and insulin secretion in pancreatic islets

1989 ◽  
Vol 264 (1) ◽  
pp. 27-33 ◽  
Author(s):  
R A Easom ◽  
J H Hughes ◽  
M Landt ◽  
B A Wolf ◽  
J Turk ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Insulin Secretion ◽  
Protein Kinase ◽  
Pancreatic Islets ◽  
Phorbol Ester ◽  
Phorbol Esters ◽  
Protein Kinase Activity ◽  
Isolated Pancreatic Islets ◽  
Kinase C ◽  
Protein Kinase C Activity

The tumour-promoting phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) induces insulin secretion from isolated pancreatic islets, and this suggests a potential role for protein kinase C in the regulation of stimulus-secretion coupling in islets. In the present study, the hypothesis that the insulinotropic effect of TPA is mediated by activation of protein kinase C in pancreatic islets has been examined. TPA induced a gradual translocation of protein kinase C from the cytosol to a membrane-associated state which correlated with the gradual onset of insulin secretion. The pharmacologically inactive phorbol ester 4 alpha-phorbol 12,13-didecanoate did not mimic this effect. TPA also induced a rapid time-dependent decline of total protein kinase C activity in islets and the appearance of a Ca2+- and phospholipid-independent protein kinase activity. Insulin secretion induced by TPA was completely suppressed (IC50 approximately 10 nM) by staurosporine, a potent protein kinase C inhibitor. Staurosporine also inhibited islet cytosolic protein kinase C activity at similar concentrations (IC50 approximately 2 nM). In addition, staurosporine partially (approximately 60%) inhibited glucose-induced insulin secretion at concentrations (IC50 approximately 10 nM) similar to those required to inhibit TPA-induced insulin secretion, suggesting that staurosporine may act at a step common to both mechanisms, possibly the activation of protein kinase C. However, stimulatory concentrations of glucose did not induce down-regulation of translocation of protein kinase C, and the inhibition of glucose-induced insulin release by staurosporine was incomplete. Significant questions therefore remain unresolved as to the possible involvement of protein kinase C in glucose-induced insulin secretion.

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