scholarly journals Induction of phosphorylation and cell surface redistribution of acetylcholine receptors by phorbol ester and carbamylcholine in cultured chick muscle cells.

1988 ◽  
Vol 107 (3) ◽  
pp. 1139-1145 ◽  
Author(s):  
A Ross ◽  
M Rapuano ◽  
J Prives
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Surface ◽  
Surface Topography ◽  
Phorbol Ester ◽  
Time Course ◽  
Muscle Cells ◽  
Kinase C ◽  
Alpha Bungarotoxin ◽  
Delta Subunit

We have investigated the mechanisms regulating the clustering of nicotinic acetylcholine receptor (AChR) on the surface of cultured embryonic chick muscle cells. Treatment of these cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent activator of protein kinase C, was found to cause a rapid dispersal of AChR clusters, as monitored by fluorescence microscopy of cells labeled with tetramethylrhodamine-conjugated alpha-bungarotoxin. The loss of AChR clusters was not accompanied by an appreciable change in the amount of AChR on the surface of these cells, as measured by the specific binding of [125I]Bgt. Analysis of the phosphorylation pattern of immunoprecipitable AChR subunits showed that the gamma- and delta-subunits are phosphorylated by endogenous protein kinase activity in the intact muscle cells, and that the delta-subunit displays increased phosphorylation in response to TPA. Structural analogues of TPA which do not stimulate protein kinase C have no effect on AChR surface topography or phosphorylation. Exposure of chick myotubes to the cholinergic agonist carbamylcholine was found to cause a dispersal of AChR clusters with a time course similar to that of TPA. Like TPA, carbamylcholine enhances the phosphorylation of the delta-subunit of AChR. The carbamylcholine-induced redistribution and phosphorylation of AChR is blocked by the nicotinic AChR antagonist d-tubocurarine. TPA and carbamylcholine have no effect on cell morphology during the time-course of these experiments. These findings indicate that cell surface topography of AChR may be regulated by phosphorylation of its subunits and suggest a mechanism for dispersal of AChR clusters by agonist activation.

scholarly journals Phorbol ester treatment increases the exocytic rate of the transferrin receptor recycling pathway independent of serine-24 phosphorylation.

1988 ◽  
Vol 106 (4) ◽  
pp. 1061-1066 ◽  
Author(s):  
T E McGraw ◽  
K W Dunn ◽  
F R Maxfield
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Surface ◽  
Phorbol Ester ◽  
Cho Cells ◽  
Transferrin Receptor ◽  
Phosphorylation Site ◽  
Major Protein ◽  
Kinase C ◽  
Recycling Pathway

In Chinese hamster ovary (CHO) fibroblast cells the protein kinase C activating phorbol ester, phorbol myristate acetate (PMA), stimulates an increase in cell surface transferrin receptor (TR) expression by increasing the exocytic rate of the recycling pathway. The human TR expressed in CHO cells is similarly affected by PMA treatment. A mutant human TR in which the major protein kinase C phosphorylation site, serine 24, has been replaced with the non-phosphorylatable amino acid glycine has been constructed to investigate the role of receptor phosphorylation in the PMA induced up-regulation. The Gly-24-substituted receptor binds, internalizes, and recycles Tf. Furthermore, the altered receptor mediates cellular Fe accumulation from diferric-Tf, thereby fulfilling the receptor's major biological role. The Gly-24 TR behaves identically to the wild-type TR when cells are treated with PMA. Therefore, Ser-24 phosphorylation is not required for the PMA-induced redistribution of the human TR expressed in CHO cells. The increased TR expression on the cell surface after PMA treatment results from an increase in the rate of exocytosis of the recycling receptors. No change in the endocytic rate or the size of the recycling receptor pool was observed. These results indicate that the PMA effect on the TR surface expression may result from a more general perturbation of membrane trafficking rather than a specific modulation of the TR.

scholarly journals Osmotic and phorbol ester-induced activation of Na+/H+ exchange: possible role of protein phosphorylation in lymphocyte volume regulation.

1985 ◽  
Vol 101 (1) ◽  
pp. 269-276 ◽  
Author(s):  
S Grinstein ◽  
S Cohen ◽  
J D Goetz ◽  
A Rothstein
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Ester ◽  
Time Course ◽  
Phorbol Esters ◽  
Underlying Mechanism ◽  
Atp Depletion ◽  
Sequence Of Events ◽  
Kinase C ◽  
Stimulation Of

The Na+/H+ antiport is stimulated by 12-O-tetradecanoylphorbol-13, acetate (TPA) and other phorbol esters in rat thymic lymphocytes. Mediation by protein kinase C is suggested by three findings: (a) 1-oleoyl-2-acetylglycerol also activated the antiport; (b) trifluoperazine, an inhibitor of protein kinase C, blocked the stimulation of Na+/H+ exchange; and (c) activation of countertransport was accompanied by increased phosphorylation of specific membrane proteins. The Na+/H+ antiport is also activated by osmotic cell shrinking. The time course, extent, and reversibility of the osmotically induced and phorbol ester-induced responses are similar. Moreover, the responses are not additive and they are equally susceptible to inhibition by trifluoperazine, N-ethylmaleimide, and ATP depletion. The extensive analogies between the TPA and osmotically induced effects suggested a common underlying mechanism, possibly activation of a protein kinase. It is conceivable that osmotic shrinkage initiates the following sequence of events: stimulation of protein kinase(s) followed by activation of the Na+/H+ antiport, resulting in cytoplasmic alkalinization. The Na+ taken up through the antiport, together with the HCO3- and Cl- accumulated in the cells as a result of the cytoplasmic alkalinization, would be followed by osmotically obliged water. This series of events could underlie the phenomenon of regulatory volume increase.

scholarly journals Protein kinase C translocation in intact vascular smooth muscle strips

1990 ◽  
Vol 270 (2) ◽  
pp. 375-381 ◽  
Author(s):  
H Haller ◽  
J I Smallwood ◽  
H Rasmussen
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Ester ◽  
Membrane Fraction ◽  
Time Course ◽  
Induced Response ◽  
Sustained Contraction ◽  
Kinase C ◽  
Intact Muscle

Using intact muscle strips from the bovine carotid artery, the time course of translocation of protein kinase C (PKC) from the cytosol to the membrane fraction was measured in response to various agonists that induce contractile responses. PKC activity was assessed by Ca2+/phospholipid-dependent phosphorylation of histone. Exposure of the muscle strips to phorbol ester (12-deoxyphorbol 13-isobutyrate) induced a rapid and sustained translocation of PKC from the cytosol to the membrane fraction, and a slowly developing but sustained contractile response. Histamine induced a comparable initial translocation of PKC to the membrane which then decreased somewhat to a stable plateau significantly above basal values. Histamine also led to a rapid and sustained increase in tension. Angiotensin I, which caused a rapid but transient contraction, induced a rapid initial translocation of PKC to the membrane. The membrane-associated PKC then declined to a stable plateau significantly lower than that seen after a histamine-induced response, and only slightly above the basal value. Endothelin, which induced a sustained contraction, caused a sustained translocation of PKC from the cytosol to the membrane. In contrast, although exposure to 35 mM-KCl induced a rapid and sustained contraction, it caused only a transient translocation of PKC; the membrane-associated PKC returned to its basal value within 20 min. These results demonstrate that PKC in intact smooth muscle can be rapidly translocated to the membrane and remains membrane-bound during sustained phorbol ester- or agonist-induced contractions, but that such a sustained translocation of PKC does not occur during prolonged stimulation with KCl.

scholarly journals Protein kinase C isoforms in muscle cells and their regulation by phorbol ester and calpain

1995 ◽  
Vol 1267 (1) ◽  
pp. 45-54 ◽  
Author(s):  
Dong-hyun Hong ◽  
Jianya Huan ◽  
Bor-rung Ou ◽  
Jan-ying Yeh ◽  
Takaomi C. Saido ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Ester ◽  
Muscle Cells ◽  
Kinase C ◽  
Protein Kinase C Isoforms

Phorbol ester inhibition of chicken intestinal brush-border sodium-proton exchange

1991 ◽  
Vol 260 (6) ◽  
pp. C1264-C1272 ◽  
Author(s):  
E. B. Chang ◽  
M. W. Musch ◽  
D. Drabik-Arvans ◽  
M. C. Rao
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Ester ◽  
Brush Border ◽  
Time Course ◽  
Brush Border Membrane ◽  
Phorbol Esters ◽  
Kinase C ◽  
Na Uptake ◽  
Exchange Activity

Phorbol esters, specific activators of protein kinase C, inhibit amiloride-sensitive Na uptake from the mucosal medium in intact intestinal mucosa as well as in isolated chicken villus enterocytes. In isolated cells, maximal inhibition is observed at 60 s, and influx returns to control values within 15 min. This effect can be measured either as initial 22Na influx rates or by following changes in intracellular pH using the pH-sensitive fluorescent dye 5,6-carboxyfluorescein. The effects of amiloride and phorbol esters were not additive, suggesting inhibition of a common transport system, i.e., Na-H exchange. In brush-border membrane vesicles (BBMV) made from villus enterocytes, amiloride-sensitive Na-H exchange activity was significantly inhibited in phorbol ester-treated cells. The degree of inhibition of 22Na uptake by BBMV had the same time course and dose-effect relationship as phorbol ester-inhibited cellular Na uptake. Similarly, the time course of protein kinase C translocation from cytosol to particulate or brush-border membrane fractions correlated with Na uptake measurements made in whole cells and BBMV. These results suggest that protein kinase C activation in chicken villus enterocytes inhibits brush-border membrane Na-H exchange activity.

Differential regulation of protein kinase C activity by modulating factors and Euonymus alatus (Thunb.) Sieb in human myometrial and uterine leiomyomal smooth muscle cells

2005 ◽  
Vol 15 (2) ◽  
pp. 349-358 ◽  
Author(s):  
T.-K. Lee ◽  
J.-Y. Lee ◽  
D.-I. Kim ◽  
Y.-C. Lee ◽  
C.-H. Kim
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Phorbol Ester ◽  
Cellular Proliferation ◽  
Muscle Cells ◽  
Proliferation Rate ◽  
Euonymus Alatus ◽  
Kinase C

Human myometrial smooth muscle cells (MSMC) showed high protein kinase C (PKC) activity when a maximal dose of PKC-activating phorbol ester was used, while uterine leiomyomal cells (ULMC) showed only 6–12% of PKC activity. MSMC exhibited a low proliferation rate, whereas ULMC exhibited a high proliferation rate. These different cell types of MSMC and ULMC responded to 10 U/mL thrombin, with a twofold stimulation of PKC activity. Downregulation of PKC activity was found when MSMC were treated with phorbol ester or with transforming growth factor-β2. We concluded that differences in PKC activity exist between MSMC and ULMC, which may be related to their different proliferative activity. ULMC treated with Euonymus alatus (Thunb.) Sieb (EA), known as “gui-jun woo” in Korea, which is used for leiomyomal tumors, exhibited a much lower proliferation rate than untreated cells, suggesting that EA inhibited the cellular proliferation of ULMC. The PKC activity of MSMC by EA treatment (50 μg/mL) changed little. ULMC showed increased PKC activity by addition of EA, indicating that PKC is activated by EA. The EA-treated ULMC were differentiated into phenotypes characteristic for normal untransformed cells, since the EA-treated cells possess higher PKC activity than untreated cells.

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