Influence of spaceflight, hindlimb suspension, and venous occlusion on alpha 1-adrenoceptors in rat vena cava

1995 ◽  
Vol 78 (5) ◽  
pp. 1882-1888 ◽  
Author(s):  
I. Sayet ◽  
G. Neuilly ◽  
J. Mironneau ◽  
C. Mironneau
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Dissociation Constant ◽  
Binding Capacity ◽  
Vena Cava ◽  
Venous Occlusion ◽  
Hindlimb Suspension ◽  
Scatchard Analysis ◽  
Kinase C ◽  
Rat Vena Cava

Effects of hindlimb suspension, spaceflight, and venous occlusion were examined in isolated strips from rat vena cava by using both [3H]prazosin-binding and contraction responses evoked by norepinephrine. Sensitivity to norepinephrine was decreased without modification of the maximal contractile response. Furthermore, the high K(+)-induced contractions were not affected, suggesting that there was no interference with voltage-dependent Ca2+ channels. The sensitivity of the norepinephrine-induced contraction to prazosin was decreased, and Scatchard analysis of [3H]prazosin binding indicated an increase in the dissociation constant without variation in maximal binding capacity. A similar increase in the dissociation constant was obtained in control rats after pretreatment with 3 microM norepinephrine or 0.1 microM phorbol 12,13-dibutyrate to desensitize the protein kinase C. This effect was completely abolished in the presence of GF-109203X, a selective inhibitor of protein kinase C. Taken together, these data indicate that altered gravity conditions induce a desensitization of alpha 1B-adrenoceptors depending on increased protein kinase C activity. This effect can be mimicked by venous occlusion and may be responsible for reduced contractile responses to norepinephrine.

scholarly journals Downregulation of tumor necrosis factor (TNF) sensitivity via modulation of TNF binding capacity by protein kinase C activators.

1987 ◽  
Vol 166 (6) ◽  
pp. 1788-1797 ◽  
Author(s):  
R Unglaub ◽  
B Maxeiner ◽  
B Thoma ◽  
K Pfizenmaier ◽  
P Scheurich
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Binding Capacity ◽  
Receptor Protein ◽  
Tnf Alpha ◽  
Tnf Receptor ◽  
Kinase C ◽  
Necrosis Factor

The regulatory action of activators for protein kinase C on the specific binding capacity for recombinant human tumor necrosis factor alpha (TNF-alpha) was studied on various human cell lines. Phorbol myristate acetate (PMA) and oleyl acetyl glycerol (OAG) both are able to rapidly downregulate TNF-binding capacity of normal and malignant cells derived from various tissues. As PMA treatment did not enhance internalization of TNF-alpha-receptor complexes at 37 degrees C, and since OAG was able to downregulate TNF-binding capacity under conditions where internalization and shedding of receptor protein are prevented, we conclude that protein kinase C controls ligand affinity of the TNF-receptor protein, possibly via direct phosphorylation. Protein kinase C triggered downregulation of TNF-alpha-binding capacity concomitantly resulted in reduction of TNF-alpha sensitivity, as revealed from decreased cytotoxic action of TNF-alpha on L 929 cells and from inhibition of TNF-alpha-mediated enhancement of HLA class II antigen expression in Colo 205 cells. Restoration of TNF-binding capacity upon abrogation of protein kinase C stimulation leads to full recovery of TNF responsiveness, further supporting the close linkage of TNF-receptor expression and TNF sensitivity. These data suggest that regulation of TNF-binding capacity by protein kinase C is one of the cellular control mechanisms of TNF responsiveness.

Protein Kinase C Activators of the Teleocidin Family Decrease the IgE-Binding Capacity of Rat Basophilic Leukemia Cells

1988 ◽  
Vol 86 (4) ◽  
pp. 465-471 ◽  
Author(s):  
Claire Gavériaux ◽  
Theodor Fehr ◽  
Encarnita Montecino-Rodriguez ◽  
Jean-Jacques Sanglier ◽  
Francis Loor
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Binding Capacity ◽  
Leukemia Cells ◽  
Kinase C ◽  
Ige Binding ◽  
Protein Kinase C Activators ◽  
Rat Basophilic Leukemia Cells ◽  
Basophilic Leukemia

Vitamin A deficiency and glucocorticoid receptor activity in rat liver

1992 ◽  
Vol 133 (2) ◽  
pp. 169-173
Author(s):  
I. Audouin ◽  
H. Garcin ◽  
I. Pailler-Rodde ◽  
P. Higueret
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Vitamin A ◽  
Glucocorticoid Receptors ◽  
Vitamin A Deficiency ◽  
Tyrosine Aminotransferase ◽  
Scatchard Analysis ◽  
Binding Properties ◽  
Kinase C ◽  
Protein Kinase C Activity

ABSTRACT The influence of vitamin A on the binding properties of hepatic glucocorticoid receptors (GR) was studied in young rats 7 weeks after they had been given a diet with or without vitamin A. Scatchard analysis showed an increased capacity of cytosolic GRs to bind dexamethasone in vitamin A deficiency. In these rats, an increase in tyrosine aminotransferase also occurred, and this could be related to the increased formation of hormone–GR complexes. Measurement of protein kinase C activity showed an increase which might be related to the functional activity of GRs. Journal of Endocrinology (1992) 133, 169–173

scholarly journals Modulation of protein kinase C by endogenous sphingosine: inhibition of phorbol dibutyrate binding in Niemann–Pick C fibroblasts

1997 ◽  
Vol 325 (3) ◽  
pp. 787-791 ◽  
Author(s):  
Claire RODRIGUEZ-LAFRASSE ◽  
Robert ROUSSON ◽  
Séverine VALLA ◽  
Pascale ANTIGNAC ◽  
Pierre LOUISOT ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Specific Binding ◽  
Fold Increase ◽  
Scatchard Analysis ◽  
Cell Fractionation ◽  
Pronounced Difference ◽  
Kinase C ◽  
Membrane Bound ◽  
Niemann Pick

The abnormal and variable increase in levels of free sphingoid bases recently described in fibroblasts from Niemann–Pick C patients allowed us to investigate the modulation of protein kinase C in vivo by endogenous sphingosine. The specific binding of [20-3H]phorbol 12,13-dibutyrate to the regulatory domain of membrane-bound protein kinase C was significantly decreased in fibroblasts from patients compared with controls. A pronounced difference between the two groups (P< 0.0001) was demonstrated in low-density lipoprotein-supplemented medium, i.e. under conditions known to disclose abnormal mobilization of unesterified cholesterol in Niemann–Pick C fibroblasts. Furthermore the degree of impairment of [3H]phorbol 12,13-dibutyrate binding was highly correlated (r = 0.95) with the sphingosine levels measured in fibroblasts from those patients. Scatchard analysis of the binding data indicated that Niemann–Pick C and control fibroblasts contained almost the same number of binding sites per cell. A 8–34-fold increase in Kd was measured in Niemann–Pick C fibroblasts with at least a 5-fold increase in sphingosine levels. Removal, by cell fractionation, of membrane-bound protein kinase C from the bulk of sphingosine induced a normalization of Kd values. The overall results suggest that protein kinase C inhibition is directly related to sphingosine accumulation.

Carbachol acts through protein kinase C to modulate cholecystokinin receptors on pancreatic acini

1991 ◽  
Vol 261 (6) ◽  
pp. G981-G986 ◽  
Author(s):  
D. S. Louie ◽  
O. Y. Chung
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Binding Capacity ◽  
Muscarinic Agonist ◽  
Amylase Release ◽  
Pancreatic Acini ◽  
Cck Receptors ◽  
High Affinity ◽  
Total Binding ◽  
Kinase C

Cholecystokinin (CCK) and cholinergic agonists are both major stimulants of pancreatic enzyme secretion and both utilize a common calcium-phosphoinositide-mediated receptor coupling system. In this study we investigated the modulation of pancreatic acinar CCK receptors by the muscarinic agonist carbachol (CCh) and investigated the intracellular mechanisms involved in the modulation. Acini were isolated from rat pancreas and dispersed in N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-Ringer solution. Preincubation with 0.1 mM carbachol for 60 min reduced the CCK octapeptide (CCK-8; 100 pM)-stimulated amylase release by 43 +/- 5%. Binding of 125I-Bolton-Hunter-labeled CCK-8 (125I-BH-CCK-8) revealed two classes of CCK receptors, a high affinity with a dissociation constant (Kd) of 20 pM and a low affinity with a Kd of 2.3 nM. Pretreatment with 100 microM CCh decreased total binding by 35 +/- 6%, affecting the binding capacity of the high-affinity site, without change in the maximal binding capacity of the low-affinity site and no change in the Kd of either site. Preincubation of acini with 12-O-tetradecanoylphorbol 12,13-acetate (TPA, 1 microM), an activator of protein kinase C (PKC), decreased subsequent CCK-8-stimulated amylase release, and total binding of 125I-BH-CCK-8 to a similar extent as with pretreatment with CCh. The inhibitory effect of TPA or CCh on CCK-8-stimulated amylase release was reversed by simultaneous preincubation with H-7, an inhibitor of PKC. Pretreatment of acini with the calcium ionophore A23187, vasoactive intestinal peptide, or 8-bromoadenosine 3',5'-cyclic monophosphate had no effect on 125I-BH-CCK-8 binding. After CCh or TPA preincubation, CCK-8-stimulated production of [3H]inositol phosphates was inhibited by at least 49%.(ABSTRACT TRUNCATED AT 250 WORDS)

Histamine H1-receptor-mediated keratan sulfate production in rabbit chondrocytes: involvement of protein kinase C

1991 ◽  
Vol 261 (3) ◽  
pp. C413-C416 ◽  
Author(s):  
K. Fukuda ◽  
H. Yamasaki ◽  
Y. Nagata ◽  
H. Motoyoshi ◽  
F. Matsumura ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Keratan Sulfate ◽  
Scatchard Analysis ◽  
Dependent Manner ◽  
H1 Receptor ◽  
Single Class ◽  
Histamine H1 Receptor ◽  
Sulfate Production ◽  
Kinase C

We investigated the characteristics of the histamine H1-receptor in cultured rabbit chondrocytes. Scatchard analysis of [3H]pyrilamine, an H1-antagonist, binding to the chondrocytes revealed a single class of binding sites with KD and Bmax values of 90 +/- 12 nM and 56 +/- 11 fmol/10(4) cells, respectively. H1-agonists stimulated the production of keratan sulfate in a dose-dependent manner. Stimulation of keratan sulfate production was inhibited by pyrilamine. Protein kinase C inhibitors (sphingosine and H-7) also had inhibitory effects. Phorbol 12,13-dibutyrate, a direct activator of protein kinase C, activated the production. When protein kinase C in the chondrocytes was down-regulated by preincubation with phorbol ester, the effect of the H1-agonist on keratan sulfate production was abolished. These results indicate that the histamine H1-receptor on chondrocytes mediates the accumulation of keratan sulfate production and that protein kinase C is involved in these events.

scholarly journals Neurotensin stimulates inositol trisphosphate-mediated calcium mobilization but not protein kinase C activation in HT29 cells. Involvement of a G-protein

1989 ◽  
Vol 264 (3) ◽  
pp. 871-878 ◽  
Author(s):  
J C Bozou ◽  
N Rochet ◽  
I Magnaldo ◽  
J P Vincent ◽  
P Kitabgi
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
G Proteins ◽  
Binding Sites ◽  
Inositol Phosphate ◽  
Calcium Mobilization ◽  
Scatchard Analysis ◽  
High Affinity ◽  
Ht29 Cells ◽  
Kinase C

It has previously been shown that neurotensin binds to high-affinity receptors in the adenocarcinoma HT29 cell line, and that receptor occupancy leads to inositol phosphate formation. The present study was designed to investigate further the effects of neurotensin on calcium mobilization and protein kinase C (PKC) activation in HT29 cells, and to assess the role of GTP-binding proteins (G-proteins) in the neurotensin response. Direct measurements of cytosolic Ca2+ variations using the fluorescent indicator quin 2 showed that neurotensin (0.1-1 microM) elicited Ca2+ transients in HT29 cells. These transients occurred after the neurotensin-stimulated formation of Ins(1,4,5)P3, as measured by means of a specific radioreceptor assay. In addition, the peptide induced a decrease in the 45Ca2+ content of cells previously equilibrated with this isotope. The peptide effect was rapid, long-lasting and concentration-dependent, with an EC50 of 2 nM. Phorbol 12-myristate 13-acetate (PMA) inhibited by 50% the neurotensin effects on both intracellular Ca2+ and inositol phosphate levels. The inhibition by PMA was abolished in PKC-depleted cells. Pertussis toxin had no effect on either the Ca2+ or inositol phosphate responses to neurotensin. Epidermal growth factor (EGF) receptors which are present in HT29 cells have been shown to be down-regulated through phosphorylation by PKC in a variety of systems. Here, PMA markedly (70-80%) inhibited EGF binding to HT29 cells. Scatchard analysis revealed that PMA abolished the high-affinity component of EGF binding, an effect that was totally reversed in PKC-depleted cells. In contrast, neurotensin slightly (10-20%) inhibited EGF binding to HT29 cells, and its effect was only partly reversed by PKC depletion. Neurotensin had no detectable effect on sn-1,2-diacylglycerol levels in HT29 cells, as measured by a specific and sensitive enzymic assay. In membranes prepared from HT29 cells, monoiodo[125I-Tyr3]neurotensin bound to a single population of receptors with a dissociation constant of 0.27 nM. Sodium and GTP inhibited neurotensin binding in a concentration-dependent manner. Maximal inhibition reached 80% with Na+ and 35% with GTP.IC50 values were 20 mM and 0.2 microM for Na+ and GTP respectively. Li+ and K+ were less effective than Na+ and the effects of GTP were shared by GDP and guanosine-5′-[beta gamma- imido]triphosphate but not by ATP. Scatchard analysis of binding data indicated that Na+ and GTP converted the high-affinity neurotensin-binding sites into lower affinity binding sites. The properties of the effects of Na+ and GTP on neurotensin-receptor interactions are characteristic of those receptors which interact with G-proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Activation of insulin-epidermal growth factor (EGF) receptor chimerae regulates EGF receptor binding affinity.

1992 ◽  
Vol 116 (3) ◽  
pp. 627-633 ◽  
Author(s):  
S Tartare ◽  
R Ballotti ◽  
R Lammers ◽  
C Filloux ◽  
A Chauvel ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Receptor Binding ◽  
Egf Receptor ◽  
Scatchard Analysis ◽  
Receptor Kinase ◽  
Egf Receptors ◽  
High Affinity ◽  
Kinase C

Cell surface tyrosine kinase receptors are subject to a rapid activation by their ligand, which is followed by secondary regulatory processes. The IHE2 cell line is a unique model system to study the regulation of EGF binding to EGF receptors after activation of the EGF receptor kinase. IHE2 cells express both a chimeric insulin-EGF receptor kinase (IER) and a kinase-deficient EGF receptor (HER K721A). We have previously reported that IER is an insulin-responsive EGF receptor tyrosine kinase that activates one or several serine/threonine kinases, which in turn phosphorylate(s) the unoccupied HER K721A. In this article we show that insulin through IER activation induces a decrease in 125I-EGF binding to IHE2 cells. Scatchard analysis indicates that, as for TPA, the effect of insulin can be accounted for by a loss of the high affinity binding of EGF to HER K721A. Since this receptor transmodulation persists in protein kinase C downregulated IHE2 cells, it is likely to be due to a mechanism independent of protein kinase C activation. Using an in vitro system of 125I-EGF binding to transmodulated IHE2 membranes, we illustrate that the inhibition of EGF binding induced by IER activation is related to the phosphorylation state of HER K721A. Further, studies with phosphatase 2A, or at a temperature (4 degrees C) where only IER is functional, strongly suggest that the loss of high affinity EGF binding is related to the serine/threonine phosphorylation of HER K721A after IER activation. Our results provide evidence for a "homologous desensitization" of EGF receptor binding after activation of the EGF receptor kinase of the IER receptor.

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