Role of protein kinase C in the regulation of glucose transport in the rat adipose cell. Translocation of glucose transporters without stimulation of glucose transport activity.

Platelets derive most of their energy from anaerobic glycolysis; during activation this requirement rises approx. 3-fold. To accommodate the high glucose flux, platelets express extremely high concentrations (155±18 pmol/mg of membrane protein) of the most active glucose transporter isoform, GLUT3. Thrombin, a potent platelet activator, was found to stimulate 2-deoxyglucose transport activity 3-5-fold within 10 min at 25 °C, with a half-time of 1-2 min. To determine the mechanism underlying the increase in glucose transport activity, an impermeant photolabel, [2-3H]2N-4-(1-azi-2,2,2-trifluoethyl)benzoyl-1,3,-bis-(d-mannose-4-ylozy)-2-propylamine, was used to covalently bind glucose transporters accessible to the extracellular milieu. In response to thrombin, the level of transporter labelling increased 2.7-fold with a half-time of 1-2 min. This suggests a translocation of GLUT3 transporters from an intracellular site to the plasma membrane in a manner analogous to that seen for the translocation of GLUT4 in insulin-stimulated rat adipose cells. To investigate whether a similar signalling pathway was involved in both systems, platelets and adipose cells were exposed to staurosporin and wortmannin, two inhibitors of GLUT4 translocation in adipose cells. Thrombin stimulation of glucose transport activity in platelets was more sensitive to staurosporin inhibition than was insulin-stimulated transport activity in adipose cells, but it was totally insensitive to wortmannin. This indicates that the GLUT3 translocation in platelets is mediated by a protein kinase C not by a phosphatidylinositol 3-kinase mechanism. In support of this contention, the phorbol ester PMA, which specifically activates protein kinase C, fully stimulated glucose transport activity in platelets and was equally sensitive to inhibition by staurosporin. This study provides a cellular mechanism by which platelets enhance their capacity to import glucose to fulfil the increased energy demands associated with activation.

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

The Journal of General Physiology ◽

10.1085/jgp.89.2.185 ◽

1987 ◽

Vol 89 (2) ◽

pp. 185-213 ◽

Cited By ~ 70

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.

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

Molecular and Cellular Biology ◽

10.1128/mcb.12.7.3305-3312.1992 ◽

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.

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Insulin action on cardiac glucose transport: studies on the role of protein kinase C

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research ◽

10.1016/0167-4889(94)00200-x ◽

1995 ◽

Vol 1265 (1) ◽

pp. 73-78 ◽

Cited By ~ 16

Author(s):

Martina Russ ◽

Jürgen Eckel

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Glucose Transport ◽

Insulin Action ◽

Transport Studies ◽

Kinase C

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

Immunopharmacology ◽

10.1016/0162-3109(86)90050-0 ◽

1986 ◽

Vol 12 (1) ◽

pp. 37-51 ◽

Cited By ~ 50

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

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Inhibitors such as staurosporine, H-7 or polymyxin B cannot be used in skeletal muscle to prove the role of protein kinase C on insulin action

Bioscience Reports ◽

10.1007/bf01121505 ◽

1992 ◽

Vol 12 (5) ◽

pp. 413-424 ◽

Cited By ~ 4

Author(s):

Anna Gumà ◽

Purificación Muñoz ◽

Marta Camps ◽

Xavier Testar ◽

Manuel Palacín ◽

...

Keyword(s):

Skeletal Muscle ◽

Protein Kinase C ◽

Protein Kinase ◽

Insulin Action ◽

Lactate Production ◽

Polymyxin B ◽

Transport Activity ◽

System A ◽

Kinase C

The precise role of protein kinase C in insulin action in skeletal muscle is not well defined. Based on the fact that inhibitors of protein kinase C block some insulin effects, it has been concluded that some of the biological actions of insulin are mediated via protein kinase C. In this study, we present evidence that inhibitors of protein kinase C such as staurosporine, H-7 or polymyxin B cannot be used to ascertain the role of protein kinase C in skeletal muscle. This is based on the following experimental evidences: a) staurosporine, H-7 and polymyxin B markedly block in muscle the effect of insulin on System A transport activity; however, this effect of insulin is not mimicked in muscle by TPA-induced stimulation of protein kinase C, b) H-7 and polymyxin B block insulin action on System A transport activity in an additive manner to the inhibitory effect of phorbol esters, c) staurosporine, H-7 and polymyxin B block the effect of insulin on lactate production, a process that is activated by insulin and TPA in an additive fashion, and d) staurosporine completely blocks the tyrosine kinase activity of insulin receptors partially purified from rat skeletal muscle.

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PROTEIN KINASE C CONTROLS CA2+ MOBILIZATION IN HUMAN PLATELETS

10.1055/s-0038-1644509 ◽

1987 ◽

Cited By ~ 1

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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