The role of protein kinase C in the stimulation of phosphatidylcholine synthesis by phospholipase C

1991 ◽  
Vol 288 (2) ◽  
pp. 331-336 ◽  
Author(s):  
Gwenith A. Jones ◽  
Claudia Kent
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Kinase C ◽  
Phosphatidylcholine Synthesis ◽  
Stimulation Of

Regulation of oxytocin secretion by the ovine corpus luteum: effect of activators of protein kinase C

1990 ◽  
Vol 124 (2) ◽  
pp. 225-232 ◽  
Author(s):  
J. J. Hirst ◽  
G. E. Rice ◽  
G. Jenkin ◽  
G. D. Thorburn
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Corpus Luteum ◽  
Phospholipase C ◽  
Tissue Slices ◽  
Kinase C ◽  
Luteal Tissue ◽  
Dose Dependent ◽  
Stimulation Of

ABSTRACT The effect of protein kinase C activation and dibutyryl cyclic AMP on oxytocin secretion by ovine luteal tissue slices was investigated. Several putative regulators of luteal oxytocin secretion were also examined. Oxytocin was secreted by luteal tissue slices at a basal rate of 234·4 ± 32·8 pmol/g per h (n = 24) during 60-min incubations.Activators of protein kinase C: phorbol 12,13-dibutyrate (n = 8), phorbol 12-myristate,13-acetate (n = 4) and 1,2-didecanoylglycerol (n = 5), caused a dose-dependent stimulation of oxytocin secretion in the presence of a calcium ionophore (A23187; 0·2 μmol/l). Phospholipase C (PLC; 50–250 units/l) also caused a dose-dependent stimulation of oxytocin secretion by luteal slices. Phospholipase C-stimulated oxytocin secretion was potentiated by the addition of an inhibitor of diacylglycerol kinase (R59 022; n = 4). These data suggest that the activation of protein kinase C has a role in the stimulation of luteal oxytocin secretion. The results are also consistent with the involvement of protein kinase C in PLC-stimulated oxytocin secretion. The cyclic AMP second messenger system does not appear to be involved in the control of oxytocin secretion by the corpus luteum. Journal of Endocrinology (1990) 124, 225–232

scholarly journals Cytoplasmic [Ca2+] and intracellular pH in lymphocytes. Role of membrane potential and volume-activated Na+/H+ exchange.

1987 ◽  
Vol 89 (2) ◽  
pp. 185-213 ◽  
Author(s):  
S Grinstein ◽  
S Cohen
Keyword(s):  
Protein Kinase C ◽  
Membrane Potential ◽  
Protein Kinase ◽  
Intracellular Ph ◽  
Enzyme Treatment ◽  
Membrane Hyperpolarization ◽  
Kinase C ◽  
Free Media ◽  
Stimulation Of

The effect of elevating cytoplasmic Ca2+ [( Ca2+]i) on the intracellular pH (pHi) of thymic lymphocytes was investigated. In Na+-containing media, treatment of the cells with ionomycin, a divalent cation ionophore, induced a moderate cytoplasmic alkalinization. In the presence of amiloride or in Na+-free media, an acidification was observed. This acidification is at least partly due to H+ (equivalent) uptake in response to membrane hyperpolarization since: it was enhanced by pretreatment with conductive protonophores, it could be mimicked by valinomycin, and it was decreased by depolarization with K+ or gramicidin. In addition, activation of metabolic H+ production also contributes to the acidification. The alkalinization is due to Na+/H+ exchange inasmuch as it is Na+ dependent, amiloride sensitive, and accompanied by H+ efflux and net Na+ gain. A shift in the pHi dependence underlies the activation of the antiport. The effect of [Ca2+]i on Na+/H+ exchange was not associated with redistribution of protein kinase C and was also observed in cells previously depleted of this enzyme. Treatment with ionomycin induced significant cell shrinking. Prevention of shrinking largely eliminated the activation of the antiport. Moreover, a comparable shrinking produced by hypertonic media also activated the antiport. It is concluded that stimulation of Na+/H+ exchange by elevation of [Ca2+]i is due, at least in part, to cell shrinking and does not require stimulation of protein kinase C.

Role of protein kinase C in T-cell antigen receptor regulation of p21ras: evidence that two p21ras regulatory pathways coexist in T cells

1992 ◽  
Vol 12 (7) ◽  
pp. 3305-3312
Author(s):  
M Izquierdo ◽  
J Downward ◽  
J D Graves ◽  
D A Cantrell
Keyword(s):  
T Cells ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Kinase Inhibitor ◽  
Antigen Receptor ◽  
Permeabilized Cell ◽  
Regulatory Pathways ◽  
Kinase C ◽  
Stimulation Of

T-lymphocyte activation via the antigen receptor complex (TCR) results in accumulation of p21ras in the active GTP-bound state. Stimulation of protein kinase C (PKC) can also activate p21ras, and it has been proposed that the TCR effect on p21ras occurs as a consequence of TCR regulation of PKC. To test the role of PKC in TCR regulation of p21ras, a permeabilized cell system was used to examine TCR regulation of p21ras under conditions in which TCR activation of PKC was blocked, first by using a PKC pseudosubstrate peptide inhibitor and second by using ionic conditions that prevent phosphatidyl inositol hydrolysis and hence diacylglycerol production and PKC stimulation. The data show that TCR-induced p21ras activation is not mediated exclusively by PKC. Thus, in the absence of PKC stimulation, the TCR was still able to induce accumulation of p21ras-GTP complexes, and this stimulation correlated with an inactivation of p21ras GTPase-activating proteins. The protein tyrosine kinase inhibitor herbimycin could prevent the non-PKC-mediated, TCR-induced stimulation of p21ras. These data indicate that two mechanisms for p21ras regulation coexist in T cells: one PKC mediated and one not. The TCR can apparently couple to p21ras via a non-PKC-controlled route that may involve tyrosine kinases.

scholarly journals Targeting of Protein Kinase C-ϵ during Fcγ Receptor-dependent Phagocytosis Requires the ϵC1B Domain and Phospholipase C-γ1

2006 ◽  
Vol 17 (2) ◽  
pp. 799-813 ◽  
Author(s):  
Keylon L. Cheeseman ◽  
Takehiko Ueyama ◽  
Tanya M. Michaud ◽  
Kaori Kashiwagi ◽  
Demin Wang ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Phospholipase D ◽  
Fluorescent Protein ◽  
Wild Type ◽  
Fcγ Receptor ◽  
Kinase C ◽  
Green Fluorescent

Protein kinase C-ϵ (PKC-ϵ) translocates to phagosomes and promotes uptake of IgG-opsonized targets. To identify the regions responsible for this concentration, green fluorescent protein (GFP)-protein kinase C-ϵ mutants were tracked during phagocytosis and in response to exogenous lipids. Deletion of the diacylglycerol (DAG)-binding ϵC1 and ϵC1B domains, or the ϵC1B point mutant ϵC259G, decreased accumulation at phagosomes and membrane translocation in response to exogenous DAG. Quantitation of GFP revealed that ϵC259G, ϵC1, and ϵC1B accumulation at phagosomes was significantly less than that of intact PKC-ϵ. Also, the DAG antagonist 1-hexadecyl-2-acetyl glycerol (EI-150) blocked PKC-ϵ translocation. Thus, DAG binding to ϵC1B is necessary for PKC-ϵ translocation. The role of phospholipase D (PLD), phosphatidylinositol-specific phospholipase C (PI-PLC)-γ1, and PI-PLC-γ2 in PKC-ϵ accumulation was assessed. Although GFP-PLD2 localized to phagosomes and enhanced phagocytosis, PLD inhibition did not alter target ingestion or PKC-ϵ localization. In contrast, the PI-PLC inhibitor U73122 decreased both phagocytosis and PKC-ϵ accumulation. Although expression of PI-PLC-γ2 is higher than that of PI-PLC-γ1, PI-PLC-γ1 but not PI-PLC-γ2 consistently concentrated at phagosomes. Macrophages from PI-PLC-γ2-/-mice were similar to wild-type macrophages in their rate and extent of phagocytosis, their accumulation of PKC-ϵ at the phagosome, and their sensitivity to U73122. This implicates PI-PLC-γ1 as the enzyme that supports PKC-ϵ localization and phagocytosis. That PI-PLC-γ1 was transiently tyrosine phosphorylated in nascent phagosomes is consistent with this conclusion. Together, these results support a model in which PI-PLC-γ1 provides DAG that binds to ϵC1B, facilitating PKC-ϵ localization to phagosomes for efficient IgG-mediated phagocytosis.

Prolactin stimulation of ornithine decarboxylase and mitogenesis in Nb2 node lymphoma cells: The role of protein kinase C and calcium mobilization

1986 ◽  
Vol 12 (1) ◽  
pp. 37-51 ◽  
Author(s):  
Arthur R. Buckley ◽  
David W. Montgomery ◽  
Ruthann Kibler ◽  
Charles W. Putnam ◽  
Charles F. Zukoski ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Ornithine Decarboxylase ◽  
Calcium Mobilization ◽  
Lymphoma Cells ◽  
Kinase C ◽  
Stimulation Of

Leptin Constrains Phospholipase C-Protein Kinase C-Induced Insulin Secretion via a Phosphatidylinositol 3-Kinase-Dependent Pathway

2003 ◽  
Vol 228 (2) ◽  
pp. 175-182 ◽  
Author(s):  
Joo-Won Lee ◽  
Andrew G. Swick ◽  
Dale R. Romsos
Keyword(s):  
Protein Kinase C ◽  
Insulin Secretion ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Phosphatidylinositol 3 Kinase ◽  
C Protein ◽  
Kinase C ◽  
Pka Pathway ◽  
Stimulation Of ◽  
Phosphatidylinositol 3

Leptin-deficient Lepob/Lepob mice hypersecrete insulin in response to acetylcholine stimulation of the phospholipase C-protein kinase C (PLC-PKC) pathway, and leptin constrains this hypersecretion. Leptin has been reported to activate phosphatidylinositol 3-kinase (PI 3-K) and subsequently phosphodiesterase (PDE) to impair protein kinase A (PKA)-induced insulin secretion from cultured islets of neonatal rats. We determined if PKA-induced insulin secretion was also hyperresponsive in Islets from Lepob/Lepob mice, and if leptin impaired this pathway in islets from these mice. Additionally, the possible role for PI 3-K and PDE in leptin-induced control of acetylcholine-induced insulin secretion was examined. Stimulation of Insulin secretion with GLP-1, forskolin (an activator of adenylyl cyclase), or IBMX (an inhibitor of PDE) did not cause hypersecretion of insulin from islets of young Lepob/Lepob mice, and leptin did not inhibit GLP-1-induced insulin secretion from islets of these mice. Inhibition of PDE with IBMX also did not block leptin-induced inhibition of acetylcholine-mediated insulin secretion from islets of Lepob/Lepob mice. But, preincubation of islets with wortmannin, an Inhibitor of PI 3-K activity, blocked the ability of leptin to constrain acetylcholine-induced insulin secretion from islets of Lepob/Lepob mice. We conclude that the capacity of the PKA pathway to stimulate insulin secretion is not increased in islets from young Lepob/Lepob mice, and that leptin does not regulate this pathway in islets from mice. Leptin may stimulate PI 3-K to constrain PLC-PKC-induced insulin secretion from Islets of Lepob/Lepob mice.

Evidence for a role of phosphatidylcholine-hydrolysing phospholipase C in the regulation of protein kinase C by ras and src oncogenes.

1990 ◽  
Vol 9 (12) ◽  
pp. 3907-3912 ◽  
Author(s):  
I. Diaz-Laviada ◽  
P. Larrodera ◽  
M. T. Diaz-Meco ◽  
M. E. Cornet ◽  
P. H. Guddal ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Kinase C

scholarly journals Stimulation of the hydrolysis of phosphatidylinositol 4,5-bisphosphate and phosphatidylcholine by endothelin, a complete mitogen for Rat-1 fibroblasts

1990 ◽  
Vol 272 (3) ◽  
pp. 761-766 ◽  
Author(s):  
E E MacNulty ◽  
R Plevin ◽  
M J O Wakelam
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Endothelin 1 ◽  
Kinase C ◽  
Choline Phosphate ◽  
Rapid Generation ◽  
Endothelin 3 ◽  
Hydrolysis Of ◽  
Phosphatidylcholine Synthesis ◽  
Stimulation Of

The mitogenic activity of endothelin and its ability to stimulate PtdIns(4,5)P2 and phosphatidylcholine turnover in Rat-1 fibroblasts was studied. Stimulated incorporation of [3H]thymidine occurred in the absence of any other added growth factors. The endothelins stimulated rapid generation of both Ins(1,4,5)P3 and choline. Endothelin-1 and endothelin-2 were equipotent in stimulating both responses, but endothelin-3 was less potent. Endothelin-1-stimulated Ins(1,4,5)P3 generation reached a maximum at 5 s and then declined; however, the response was long-lived, with a 4.5-fold elevation over basal still observed after 15 min. Endothelin-stimulated choline generation was observed with no increase in choline phosphate; indeed, the apparent level of this metabolite fell after 30 min of stimulation, presumably due to the observed stimulation of phosphatidylcholine synthesis. The endothelin-stimulated increase in choline generation was abolished in cells where protein kinase C was down-regulated. However, endothelin-stimulated choline generation was greater than that observed in response to a protein kinase C-activating phorbol ester, raising the possibility that the peptide activates phospholipase D by both protein kinase C-dependent and -independent mechanisms.

PROTEIN KINASE C CONTROLS CA2+ MOBILIZATION IN HUMAN PLATELETS

1987 ◽  
Author(s):  
W Siffert ◽  
P Scheid ◽  
JW N Akkerman
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Human Platelets ◽  
Cytosolic Ph ◽  
Fluorescent Indicators ◽  
Kinase C ◽  
Deutsche Forschungsgemeinschaft ◽  
Ionophore Monensin ◽  
Stimulation Of

Platelet stimulation has been shown to result in a rise of cytosolic pH (pHi) as a result of an activation of a Na+/H+ antiport. We have investigated the role of pH in Ca2+ mobilization in human platelets. pHi and free Ca2+, {Ca2+)i, were measured in platelets loaded with the fluorescent indicators BCECF and quin2, respectively. Stimulation of platelets by either thrombin or OAG, an activator of protein kinase C (Pk-C), increased pHi. Pretreatment of platelets with inhibitors of Pk-C, trifluoperazine (TFP) or sphingosine (SPH), blocked the stimulus-induced rise in pHi, suggesting a role of Pk-C in the activation of Na+/H+ exchange. Blocking Na+/H+ exchange by an amiloride analogue or by TFP similarly suppressed the thrombin-induced increase in {Ca2*}i. This effect could be prevented by increasing pHi with the Na+/H+ ionophore monensin or with NH4Cl. The thrombin-induced (0.05 U/ml) rise in {Ca2+}i was more than 3-fold enhanced when the pH was raised from 6.8 to 7.4.Our results demonstrate that pHi controls Ca2+ mobilization in human platelets and suggest that Pk-C contributes to this control by activating the Na+/H+ exchanger.Supported by the Deutsche Forschungsgemeinschaft. No Sche 46/5-2.

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