scholarly journals cAMP-dependent inhibition is dominant in regulating superoxide production in the bone-resorbing osteoclasts

1998 ◽  
Vol 158 (3) ◽  
pp. 311-318 ◽  
Author(s):  
CE Berger ◽  
BR Horrocks ◽  
HK Datta
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Pertussis Toxin ◽  
Kinase C ◽  
Significant Stimulation ◽  
Dependent Inhibition ◽  
Dependent Protein ◽  
O2 Production ◽  
Stimulation Of

Calciotropic hormones such as parathyroid hormone (PTH) and calcitonin have been shown to have stimulatory and inhibitory effects respectively on superoxide anion (O2-) generation by osteoclasts, but the exact intracellular signalling mediating these pathways has not been investigated. In order to elucidate the intracellular pathways controlling O2- generation, we have carried out a systematic study of the effect of different agents on O2- production in osteoclasts cultured on bovine cortical bone. Dibutyryl cAMP and cholera toxin, while having no effect on the basal level of O2- production in bone-resorbing osteoclasts, were, however, found to completely block the stimulation of free radical production by PTH, pertussis toxin and ionomycin. The stimulation of O2- production was found to be independent of protein kinase C-dependent pathways since the presence of bisindolylmaleimide (GF109203X) (1 microM) did not block stimulation by PTH and pertussis toxin. Interestingly, while exposure to bisindolylmaleimide at this concentration did not have any effect on the basal level of O2- production, exposure to a higher concentration (10 microM), which is known to inhibit both protein kinase C and A, produced significant stimulation. These in vitro findings suggest that in the bone-resorbing cells, cAMP-dependent protein kinases prevent further stimulation of NADPH oxidase by agents such as PTH and pertussis toxin. The increase in cAMP has also been recently demonstrated to be associated with down-regulation of the oxidative burst in adherent neutrophils; and the findings reported here suggest a similar role for cAMP in O2- generation in osteoclasts cultured on bone.

ANP stimulates phospholipase C in cultured RIMCT cells: roles of protein kinases and G protein

1991 ◽  
Vol 260 (4) ◽  
pp. F590-F595 ◽  
Author(s):  
T. Berl ◽  
J. Mansour ◽  
I. Teitelbaum
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Kinases ◽  
G Protein ◽  
Pertussis Toxin ◽  
Cyclic Nucleotide ◽  
Dependent Protein Kinase ◽  
Kinase C ◽  
Dependent Protein ◽  
Stimulation Of

We examined the possibility that, in addition to stimulation of guanylate cyclase (GC), atrial natriuretic peptide (ANP) also activates phospholipase C (PLC) in cultured rat inner medullary collecting tubule (RIMCT) cells. ANP (10(-12)M) causes marked release of inositol trisphosphate (IP3) at a concentration that does not stimulate GC. Concentrations of ANP that stimulate GC (greater than or equal to 10(-10) M) result in attenuated IP3 release. Similarly, exogenous dibutyryl guanosine 3',5'-cyclic monophosphate (10(-6) M) markedly inhibits the response to 10(-10) M ANP. Inhibition of cyclic nucleotide-dependent protein kinase by H 8, but not inhibition of protein kinase C by H 7, restores the response to 10(-8) and 10(-6) M ANP. Therefore, activation of cyclic nucleotide-dependent protein kinase inhibits ANP-stimulated PLC activity. Activation of protein kinase C by phorbol 12-myristate-13-acetate (PMA) decreases ANP-stimulated IP3 production. Pretreatment with H 7, but not H 8, prevents inhibition by PMA. To explore a potential role for G proteins, we examined the effect of guanine nucleotide analogues on ANP-stimulated IP3 production in saponin-permeabilized cells. ANP-stimulated IP3 production is enhanced by GTP gamma S and is inhibited by GDP beta S. Similarly, preincubation with pertussis toxin prevents ANP-stimulated IP3 release. We conclude that ANP stimulates PLC in RIMCT cells via a pertussis toxin-sensitive G protein. Stimulation of PLC is inhibited on activation of either cyclic nucleotide or Ca2+-phospholipid dependent protein kinases.

Mitogen stimulation of Na+-H+ exchange: differential involvement of protein kinase C

1987 ◽  
Vol 253 (2) ◽  
pp. C219-C229 ◽  
Author(s):  
L. L. Muldoon ◽  
G. A. Jamieson ◽  
A. C. Kao ◽  
H. C. Palfrey ◽  
M. L. Villereal
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Types ◽  
Intact Cells ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Human Fibroblast Strains ◽  
Stimulation Of

The mitogen-induced activation of Na+-H+ exchange was investigated in two cultured human fibroblast strains (HSWP and WI-38 cells) that, based on previous studies, differed in their response to the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) (L. M. Vincentini and M. L. Villereal, Proc. Natl. Acad. Sci. USA 82: 8053-8056, 1985). The role of protein kinase C in the activation of Na+-H+ exchange was investigated by comparing the effects of TPA on Na+ influx, in vitro phosphorylation, and in vivo phosphorylation in both cell types. Although both cell types have significant quantities of protein kinase C activity that can be activated by TPA in intact cells, the addition of TPA to intact cells stimulates Na+ influx in WI-38 cells but not in HSWP cells, indicating that in HSWP cells the stimulation of protein kinase C is not sufficient to activate the Na+-H+ exchanger. Cells were then depleted of protein kinase C activity by chronic treatment with high doses of TPA. Both HSWP and WI-38 cells were rendered protein kinase C deficient by this treatment as determined by in vitro and in vivo phosphorylation studies. Protein kinase C-deficient HSWP cells lose the ability for TPA to inhibit the serum-induced activation of Na+-H+ exchange, but there is no reduction in the stimulation of Na+ influx by serum, bradykinin, vasopressin, melittin, or vanadate, indicating that protein kinase C activity is not necessary for the mitogen-induced activation of Na+-H+ exchange in HSWP cells by agents known to stimulate phosphatidylinositol turnover (G. A. Jamieson and M. Villereal. Arch. Biochem. Biophys. 252: 478-486, 1987). In contrast, depletion of protein kinase C activity in WI-38 cells significantly reduces both the TPA- and the serum-induced activation of the Na+-H+ exchange system, suggesting that protein kinase C activity is necessary for at least a portion of the mitogen-induced activation of the Na+-H+ exchanger in WI-38 cells. These results indicate that the mechanisms for regulating Na+-H+ exchange can differ dramatically between different types of fibroblasts.

scholarly journals Pertussis Toxin Shows Distinct Early Signalling Events in Platelet-Activating Factor–, Leukotriene B4–, and C5a-Induced Eosinophil Homotypic Aggregation In Vitro and Recruitment In Vivo

Blood ◽  
1997 ◽  
Vol 89 (12) ◽  
pp. 4566-4573 ◽  
Author(s):  
Mauro M. Teixeira ◽  
Mark A. Giembycz ◽  
Mark A. Lindsay ◽  
Paul G. Hellewell
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Pertussis Toxin ◽  
Platelet Activating Factor ◽  
Leukotriene B4 ◽  
Protein Kinase Inhibitors ◽  
Eosinophil Recruitment ◽  
Kinase C

Abstract The present study was performed to investigate the early signalling events responsible for eosinophil activation in response to platelet-activating factor (PAF ), C5a, and leukotriene B4 (LTB4 ). We evaluated the effect of pertussis toxin (PTX) on eosinophil aggregation in vitro and cutaneous eosinophil recruitment in vivo. Further studies using the protein kinase inhibitors Ro 31-8220 and staurosporine were performed in vitro to assess in more detail the early signalling events induced by these three mediators. Our results show that C5a and LTB4 signal predominantly or exclusively through a PTX-sensitive G protein that is negatively modulated by protein kinase C, possibly at the level of phospholipase C-β. In contrast, PAF activates eosinophils independent of Gi by a mechanism that is abolished by Ro 31-8220, a selective protein kinase C inhibitor. In addition, these results show for the first time that a receptor-operated event on the eosinophil is essential for chemoattractant-induced eosinophil recruitment in vivo.

Effects of protein kinase C activation on cyclic AMP and testosterone production of rat Leydig cells in vitro

1989 ◽  
Vol 121 (3) ◽  
pp. 327-333 ◽  
Author(s):  
Hannu Nikula ◽  
Ilpo Huhtaniemi
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Pertussis Toxin ◽  
Leydig Cells ◽  
Endocrine Function ◽  
Camp Production ◽  
Testosterone Production ◽  
Kinase C ◽  
Protein Kinase C Activation

Abstract. The role of protein kinase C in modulation of the endocrine function of rat Leydig cells was studied. Percoll-purified rat Leydig cells were stimulated with hCG, forskolin, cholera toxin, pertussis toxin and 8-bromo-cAMP in the presence and absence of two activators of protein kinase C, 12-0-tetradecanoylphorbol 13-acetate (TPA) or 1-oleoyl-2-acetyl-sn-glycerol (OAG). The two activators had no effect on basal cAMP, but decreased hCG-stimulated, and increased cholera toxinand forskolin-stimulated cAMP production. Cells pre-incubated with pertussis toxin showed enhanced rate of cAMP production in response to forskolin, but were no more responsive to TPA and OAG stimulation. These findings suggest that protein kinase C activation may on one hand inhibit the LH-receptor and Gs-protein coupling and on the other hand inhibit the Gi-protein mediated suppression of adenylyl cyclase activity. TPA and OAG effects on testosterone production were measured in the absence and presence of 8-bromo-cAMP stimulation. TPA enhanced basal testosterone production, but this effect was shifted to inhibition when steroidogenesis was stimulated by 8-bromo-cAMP. The OAG effect on testosterone production was inhibitory throughout the dose-response curve of 8-bromo-cAMP. The basal stimulation of testosterone production by TPA was probably due to a marginal increase of cAMP caused by inhibition of the Gi-protein, since a similar effect was observed by pertussis toxin, and therafter TPA was without effect on testosterone. The inhibition of stimulated testosterone production by TPA and OAG indicates that protein kinase C activity also affects steroidogenesis at a step(s) beyound cAMP formation.

scholarly journals G-protein βγ subunits antagonize protein kinase C-dependent phosphorylation and inhibition of phospholipase C-β1

1997 ◽  
Vol 326 (3) ◽  
pp. 701-707 ◽  
Author(s):  
Irene LITOSCH
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase C ◽  
G Protein ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Negative Feedback Regulation ◽  
Kinase C ◽  
Stimulation Of

Protein kinase C (PKC) isoforms phosphorylated phospholipase C-β1 (PLC-β1) in vitro as follows: PKCα ≫ PKCϵ; not PKCζ. PLC-β3 was not phosphorylated by PKCα. G-protein βγ subunits inhibited the PKCα phosphorylation of PLC-β1 in a concentration-dependent manner. Half-maximal inhibition occurred with 500 nM βγ. G-protein βγ subunits also antagonized the PKCα-mediated inhibition of PLC-β1 enzymic activity. PKCα, in turn, inhibited the stimulation of PLC-β1 activity by βγ. There was little effect of PKCα on the stimulation of PLC-β1 by αq/11–guanosine 5′[γ-thio]triphosphate (GTP[S]). These findings demonstrate that G protein βγ subunits antagonize PKCα regulation of PLC-β1. Thus βγ subunits might have a role in modulating the negative feedback regulation of this signalling system by PKC.

scholarly journals Stimulation of generation of inositol phosphates by carbamoylcholine and its inhibition by phorbol esters and iodide in dog thyroid cells

1989 ◽  
Vol 263 (3) ◽  
pp. 795-801 ◽  
Author(s):  
E Laurent ◽  
J Mockel ◽  
K Takazawa ◽  
C Erneux ◽  
J E Dumont
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Cholera Toxin ◽  
Pertussis Toxin ◽  
Inositol Phosphates ◽  
Cholinergic Stimulation ◽  
Kinase C ◽  
Gtp Binding ◽  
Stimulation Of

The action of carbamoylcholine (Cchol), NaF and other agonists on the generation of inositol phosphates (IPs) was studied in dog thyroid slices prelabelled with myo-[2-3H]inositol. The stimulation by Cchol (0.1 microM-0.1 mM) of IPs accumulation through activation of a muscarinic receptor [Graff, Mockel, Laurent, Erneux & Dumont (1987) FEBS Lett. 210, 204-210] was pertussis- and cholera-toxin insensitive. Ins(1,4,5)P3, Ins(1,3,4)P3 and InsP4 were generated. NaF (5-20 mM) also increased IPs generation (Graff et al., 1987); this effect was potentiated by AlCl3 (10 microM) and unaffected by pertussis toxin. Although phorbol dibutyrate (5 microM) abolished the cholinergic stimulation of IPs generation (Graff et al., 1987), it did not affect the fluoride-induced response. Cchol and NaF did not require extracellular Ca2+ to exert their effect, and neither KCl-induced membrane depolarization nor ionophore A23187 (10 microM) had any influence on basal IPs levels, or on cholinergic stimulation. However, more stringent Ca2+ depletion with EGTA (0.1 or 1 mM) decreased basal IPs levels as well as the amplitude of the stimulation by Cchol without abolishing it. Dibutyryl cyclic AMP, forskolin, cholera toxin and prostaglandin E1 had no effect on basal IPs levels and did not decrease the response to Cchol. Iodide (4 or 40 microM) also strongly decreased the cholinergic action on IPs, this inhibition being relieved by methimazole (1 mM). Our data suggest that Cchol activates a phospholipase C hydrolysing PtdIns(4,5)P2 in the dog thyroid cell in a cyclic AMP-independent manner. This activation requires no extracellular Ca2+ and depends on a GTP-binding protein insensitive to both cholera toxin and requires no extracellular Ca2+ and depends on a GTP-binding protein insensitive to both cholera toxin and pertussis toxin. The data are consistent with a rapid metabolism of Ins(1,4,5)P3 to Ins(1,3,4)P3 via the Ins(1,4,5)P3 3-kinase pathway, followed by dephosphorylation by a 5-phosphomonoesterase. Indeed, a Ca2+-sensitive InsP3 3-kinase activity was demonstrated in tissue homogenate. Stimulation of protein kinase C and an organified form of iodine inhibit the Cchol-induced IPs generation. The negative feedback of activated protein kinase C could be exerted at the level of the receptor or of the receptor-G-protein interaction.

scholarly journals Phosphorylation of Farnesoid X Receptor by Protein Kinase C Promotes Its Transcriptional Activity

2008 ◽  
Vol 22 (11) ◽  
pp. 2433-2447 ◽  
Author(s):  
Romain Gineste ◽  
Audrey Sirvent ◽  
Réjane Paumelle ◽  
Stéphane Helleboid ◽  
Alexis Aquilina ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Posttranslational Modifications ◽  
Transcriptional Activity ◽  
Target Genes ◽  
Farnesoid X Receptor ◽  
Calcium Dependent ◽  
Kinase C ◽  
Dependent Protein

Abstract The farnesoid X receptor (FXR, NR1H4) belongs to the nuclear receptor superfamily and is activated by bile acids such as chenodeoxycholic acid, or synthetic ligands such as GW4064. FXR is implicated in the regulation of bile acid, lipid, and carbohydrate metabolism. Posttranslational modifications regulating its activity have not been investigated yet. Here, we demonstrate that calcium-dependent protein kinase C (PKC) inhibition impairs ligand-mediated regulation of FXR target genes. Moreover, in a transactivation assay, we show that FXR transcriptional activity is modulated by PKC. Furthermore, phorbol 12-myristate 13-acetate , a PKC activator, induces the phosphorylation of endogenous FXR in HepG2 cells and PKCα phosphorylates in vitro FXR in its DNA-binding domain on S135 and S154. Mutation of S135 and S154 to alanine residues reduces in cell FXR phosphorylation. In contrast to wild-type FXR, mutant FXRS135AS154A displays an impaired PKCα-induced transactivation and a decreased ligand-dependent FXR transactivation. Finally, phosphorylation of FXR by PKC promotes the recruitment of peroxisomal proliferator-activated receptor γ coactivator 1α. In conclusion, these findings show that the phosphorylation of FXR induced by PKCα directly modulates the ability of agonists to activate FXR.

Phosphorylation of the p220 subunit of eIF-4F by cAMP dependent protein kinase and protein kinase C in vitro

1988 ◽  
Vol 153 (3) ◽  
pp. 925-932 ◽  
Author(s):  
E. Lynne McMullin ◽  
William E. Hogancamp ◽  
Richard D. Abramson ◽  
William C. Merrick ◽  
Curt H. Hagedorn
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Kinase C ◽  
Dependent Protein
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