scholarly journals Decrease in equilibrative uridine transport during monocytic differentiation of HL-60 leukaemia: involvement of protein kinase C

1994 ◽  
Vol 300 (2) ◽  
pp. 407-412 ◽  
Author(s):  
C W Lee
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Nucleoside Transport ◽  
Protective Effects ◽  
Transport Activity ◽  
Monocytic Differentiation ◽  
Response Curves ◽  
Kinase C

The dose-response curves for the inhibition of equilibrative uridine transport by dilazep, dipyridamole and nitrobenzylthioinosine (NBMPR) in undifferentiated HL-60 cells were biphasic. Some 70% of the transport activity was inhibited with IC50 values of 0.7, 1 and 7 nM respectively. No inhibition of the remaining 30% of transport activity was observed until the dilazep, dipyridamole and NBMPR concentrations exceeded 1, 0.1 and 3 microM respectively. Exposure to phorbol 12-myristate 13-acetate (PMA) for 48 h, to induce monocytic differentiation, caused a 20-fold decrease in Vmax. of both NBMPR-sensitive and NBMPR-insensitive equilibrative uridine transport. The decrease in NBMPR-sensitive uridine transport induced by PMA corresponded to a decrease in NBMPR binding sites. A 30% decrease in specific NBMPR binding sites occurred within 6 h of PMA exposure, and could be prevented by uridine and thymidine at concentrations as low as 100 microM, and by staurosporine at 40 nM. However, the protective effects of these compounds diminished with prolonged PMA exposure. No protection was observed with uracil. Exogenous protein kinase C (PKC) in the presence of ATP and PMA decreased the number of specific NBMPR-binding sites in purified HL-60 cell plasma membranes. These results suggest that a PKC-induced conformational change in substrate-binding/transporting site may be responsible for the decrease in NBMPR-sensitive nucleoside transport during PMA-induced monocytic differentiation of HL-60 cells.

scholarly journals Induction of the differentiation of HL-60 cells by phorbol 12-myristate 13-acetate activates a Na+-dependent uridine-transport system. Involvement of protein kinase C

1991 ◽  
Vol 274 (1) ◽  
pp. 85-90 ◽  
Author(s):  
C W Lee ◽  
J A Sokoloski ◽  
A C Sartorelli ◽  
R E Handschumacher
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Nucleoside Transport ◽  
Facilitated Diffusion ◽  
Similar Increase ◽  
Monocytic Differentiation ◽  
Cell Water ◽  
Cellular Mechanisms ◽  
Kinase C ◽  
Dependent Transport

The Na(+)-dependent transport and facilitated diffusion of uridine were measured after differentiation of HL-60 leukaemia cells along the monocytic pathway by phorbol 12-myristate 13-acetate (PMA). PMA (200 ng/ml) caused a marked increase in Na(+)-dependent uridine transport within 48 h of exposure that was attributable to an increase in transport affinity (apparent Km values of 1.15 +/- 0.22 and 44 +/- 4.4 microM for PMA-induced and uninduced cells respectively), with no change in Vmax. (0.15 +/- 0.02 and 0.13 +/- 0.01 pmol/s per microliter of cell water for PMA-induced and uninduced cells respectively). A corresponding rapid decrease in both the rate of facilitated diffusion and the formation of uracil nucleotides occurred in PMA-induced cells. As a consequence of these changes, intracellular pools of uridine 3-4-fold greater than those in the medium were generated. A similar increase in Na(+)-dependent transport of adenosine, inosine, guanosine, thymidine and cytidine (Km values of 1-4 microM) was observed. The effects of PMA on the activation of the Na(+)-dependent uridine transporter were inhibited by staurosporine, suggesting the involvement of protein kinase C. The findings indicate that a change in the balance of the cellular mechanisms employed for nucleoside transport occurs during the monocytic differentiation of HL-60 leukaemia cells.

scholarly journals Collagen-induced platelet activation mainly involves the protein kinase C pathway

1990 ◽  
Vol 268 (2) ◽  
pp. 325-331 ◽  
Author(s):  
A Karniguian ◽  
F Grelac ◽  
S Levy-Toledano ◽  
Y J Legrand ◽  
F Rendu
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Platelet Activation ◽  
Membrane Receptors ◽  
Lag Phase ◽  
Response Curves ◽  
Kinase C ◽  
Metabolic Event ◽  
Granule Secretion

This study analyses early biochemical events in collagen-induced platelet activation. An early metabolic event occurring during the lag phase was the activation of PtdIns(4,5)P2-specific phospholipase C. Phosphatidic acid (PtdOH) formation, phosphorylation of P43 and P20, thromboxane B2 (TXB2) synthesis and platelet secretion began after the lag phase, and were similarly time-dependent, except for TXB2 synthesis, which was delayed. Collagen induced extensive P43 phosphorylation, whereas P20 phosphorylation was weak and always lower than with thrombin. The dose-response curves of P43 phosphorylation and granule secretion were similar, and both reached a peak at 7.5 micrograms of collagen/ml, a dose which induced half-maximal PtdOH and TXB2 formation. Sphingosine, assumed to inhibit protein kinase C, inhibited P43 phosphorylation and secretion in parallel. However, sphingosine was not specific for protein kinase C, since a 15 microM concentration, which did not inhibit P43 phosphorylation, blocked TXB2 synthesis by 50%. Sphingosine did not affect PtdOH formation at all, even at 100 microM, suggesting that collagen itself induced this PtdOH formation, independently of TXB2 generation. The absence of external Ca2+ allowed the cleavage of polyphosphoinositides and the accumulation of InsP3 to occur, but impaired P43 phosphorylation, PtdOH and TXB2 formation, and secretion; these were only restored by adding 0.11 microM-Ca2+. In conclusion, stimulation of platelet membrane receptors for collagen initiates a PtdInsP2-specific phospholipase C activation, which is independent of external Ca2+, and might be the immediate receptor-linked response. A Ca2+ influx is indispensable to the triggering of subsequent platelet responses. This stimulation predominantly involves the protein kinase C pathway associated with secretion, and appears not to be mediated by TXB2, at least during its initial stage.

scholarly journals Nedd4-2 but not Nedd4-1 is critical for protein kinase C-regulated ubiquitination, expression, and transport activity of human organic anion transporter 1

2016 ◽  
Vol 310 (9) ◽  
pp. F821-F831 ◽  
Author(s):  
Da Xu ◽  
Haoxun Wang ◽  
Qiang Zhang ◽  
Guofeng You
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Surface ◽  
Organic Anion ◽  
The Body ◽  
Organic Anion Transporter ◽  
Transport Activity ◽  
Kinase C ◽  
Anion Transporter ◽  
In Cells

Human organic anion transporter 1 (hOAT1) expressed at the membrane of the kidney proximal tubule cells mediates the body disposition of a diverse array of clinically important drugs, including anti-HIV therapeutics, antitumor drugs, antibiotics, antihypertensives, and antiinflammatories. Therefore, understanding the regulation of hOAT1 will provide significant insights into kidney function and dysfunction. We previously established that hOAT1 transport activity is inhibited by activation of protein kinase C (PKC) through accelerating hOAT1 internalization from cell surface into intracellular endosomes and subsequent degradation. We further established that PKC-induced hOAT1 ubiquitination is an important step preceding hOAT1 internalization. In the current study, we identified two closely related E3 ubiquitin ligases, neural precursor cell expressed, developmentally downregulated 4-1 and 4-2 (Nedd4-1 and Nedd4-2), as important regulators for hOAT1: overexpression of Nedd4-1 or Nedd4-2 enhanced hOAT1 ubiquitination, reduced the hOAT1 amount at the cell surface, and suppressed hOAT1 transport activity. In further exploring the relationship among PKC, Nedd4-1, and Nedd4-2, we discovered that PKC-dependent changes in hOAT1 ubiquitination, expression, and transport activity were significantly blocked in cells transfected with the ligase-dead mutant of Nedd4-2 (Nedd4-2/C821A) or with Nedd4-2-specific siRNA to knockdown endogenous Nedd4-2 but not in cells transfected with the ligase-dead mutant of Nedd4-1 (Nedd4-1/C867S) or with Nedd4-1-specific siRNA to knockdown endogenous Nedd4-1. In conclusion, this is the first demonstration that both Nedd4-1 and Nedd4-2 are important regulators for hOAT1 ubiquitination, expression, and function. Yet they play distinct roles, as Nedd4-2 but not Nedd4-1 is a critical mediator for PKC-regulated hOAT1 ubiquitination, expression, and transport activity.

Chlorpromazine is unable to block the protein kinase C translocation to human platelet plasma membranes stimulated by phorbol ester

1989 ◽  
Vol 17 (6) ◽  
pp. 1008-1009 ◽  
Author(s):  
JULIO FONT ◽  
AIDA MARINO ◽  
JAVIER IBARRONDO ◽  
MIGUEL TRUEBA ◽  
JOSE M. MACARULLA
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phorbol Ester ◽  
Plasma Membranes ◽  
Human Platelet ◽  
Kinase C

Protein kinase C and progesterone-induced maturation in Xenopus oocytes

Development ◽  
1990 ◽  
Vol 109 (3) ◽  
pp. 597-604
Author(s):  
R.L. Varnold ◽  
L.D. Smith
Keyword(s):  
Cell Cycle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Xenopus Oocytes ◽  
Plasma Membranes ◽  
Protein Kinase C Inhibitors ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Concomitant Reduction ◽  
Dependent Protein

Though progesterone-induced maturation has been studied extensively in Xenopus oocytes, the mechanism whereby the prophase block arrest is released is not well understood. The current hypothesis suggests that a reduction in cAMP and subsequent inactivation of cAMP-dependent protein kinase is responsible for reentry into the cell cycle. However, several lines of evidence indicate that maturation can be induced without a concomitant reduction in cAMP. We show that the mass of diacylglycerol in whole oocytes and plasma membranes decreases 29% and 10% respectively, within the first 15 sec after the addition of progesterone. Diacylglycerol in plasma membranes further decreased 59% by 5 min. We also show that the protein kinase C inhibitors sphingosine and staurosporine can induce oocyte maturation. In addition, the synthetic diglyceride, DiC8, and microinjected PKC can inhibit or delay progesterone-induced maturation. These results together suggest that a transient decrease in protein kinase C activity may regulate entry into the cell cycle. The mechanism whereby DAG is decreased in response to progesterone is unclear. Initial studies show that progesterone leads to a decrease in IP3 suggesting that progesterone may act by reducing the hydrolysis of PIP2. On the other hand, progesterone caused a decrease in the amount of [3H]arachidonate labelling in DAG during the same time suggesting that progesterone may stimulate lipase activity. The relationship between postulated changes in the PKC pathway and those hypothesized for the PKA pathway are discussed.

Expression of histamine H1 receptors in autoimmune myocarditis mice

1993 ◽  
Vol 71 (9) ◽  
pp. 639-644 ◽  
Author(s):  
Nora Goren ◽  
Claudia Perez Leiros ◽  
Leonor Sterin-Borda ◽  
Enri Borda
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Receptor Antagonist ◽  
Binding Sites ◽  
Affinity Binding ◽  
Autoimmune Myocarditis ◽  
Kinase C ◽  
Chronotropic Effects ◽  
Histamine H1 Receptors ◽  
Two Populations

Two populations of histaminergic H1 receptors with distinct high and low affinity binding sites were characterized by the specific H1 receptor antagonist [3H]mepyramine in autoimmune myocardium. No saturable binding of the radiolabelled H1 antagonist was observed in normal myocardium. Reaction of autoimmune myocardium with specific H1 agonist (2-thiazolyl-ethylamine (ThEA)) triggered positive inotropy and negative chronotropy, which were inhibited by mepyramine. Inhibitors of phospholipase C and protein kinase C attenuated both the inotropic and chronotropic effects of ThEA, suggesting the participation of phosphoinositide hydrolysis in this phenomenon. The latter was verified by measurement of polyphosphoinositide hydrolysis in autoimmune myocardium following the reaction of ThEA with histaminergic H1 receptors. We conclude that functional H1 histaminergic receptors could involve a distinctive mechanism operating in autoimmune myocardium as a result of cardiac antigen immunization.Key words: histamine, H1 receptors, myocarditis, autoimmunity.

Sign in / Sign up

Export Citation Format

Share Document