Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Smooth muscle cells isolated from the circular muscle layer of cat esophagus and lower esophageal sphincter (LES) exhibit distinct contractile intracellular signal transduction pathways in response to acetylcholine. To determine whether these contractile pathways are muscle type dependent, the authors examined the signal transduction pathways utilized by substance P and bombesin, which in other tissues, use different signal transduction pathways, and by the GTP analog, guanosine 5'-O-3-thiotriphosphate (GTP gamma S), which activates all available G proteins. Western blot analysis of esophageal and LES circular muscle revealed the presence of Gq-G11 (42 kD), Gi1-Gi2 (40 kD) and Go-Gi3 (40 kD) types of G proteins. The responses of esophageal cells to bombesin and substance P were blocked by 1) a Gi3 protein antibody, 2) the inhibitor of specific phosphatidylcholine-phospholipase C (PLC) D609 potassium tricyclo-[5.2.1.0(2.6)]-decyl-(9[8])-xanthogenate, 3) inhibition of phosphatidic acid phosphohydrolase by propranolol, 4) the protein kinase C inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H7) and 5) incubation in Ca(++)-free medium. Conversely, the responses of LES muscle cells to bombesin and substance P were blocked by 1) a Gq-G11 antibody, 2) a phosphatidylinositol-specific PLC antagonist U-73122 (1-[6-[[17 beta-3-methoxyestra-1,3,5(10)-trien-17- yl]amino]hexyl]-1H-pyrrole-2,5-dione), 3) the calmodulin inhibitor CGS9343B (1,3-Dihydro-1-[1-((4-methyl-4H,6H-pyrrolo[1,2-a]-[4,1]benzoxazepin++ +-4 - yl)methyl-4-piperindinyl]-2H-benzimidazol-2-one maleate) and 4) incubation in Sr++. After permeabilization by saponin, inositol 1,4,5-trisphosphate contracted LES but not esophageal cells. The inositol 1,4,5-trisphosphate receptor antagonist heparin and depletion of intracellular Ca++ stores by thapsigargin or A23187 4-Benzoxazolecarboxylic acid, 5-(methylamino)-2-[[3,9,11-trimethyl-8-[1-methyl-2-oxo-2-(1H-pyrrol- 2-yl)ethyl]-1,7-dioxaspiro[5.5]undec-2-yl]methyl]-, [6s-[6.alpha. (2S*,3S*),8.beta. (R*), 9.beta., 11. alpha.]]-(9Cl), blocked bombesin- and substance P-induced contraction of LES but not of esophageal muscle. In addition, contraction in response to GTP gamma S, which activates all G proteins, was blocked in esophageal cells by a Gi3-protein antibody, propranolol, D609 and H7. In LES muscle cells, the response to GTP gamma S was blocked by a Gq protein antibody, U-73122 and CGS934B. These data demonstrate that, in esophageal muscle, different agonists activate the same Gi3 protein, phosphatidylcholine-specific phospholipases and protein kinase C-dependent pathway.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Agonist-independent, muscle-type-specific signal transduction pathways in cat esophageal and lower esophageal sphincter circular smooth muscle. 753 46

Complementary DNAs encoding delta, mu and kappa-opioid receptors have now been cloned and characterized. These receptors, which are members of the superfamily of seven transmembrane spanning receptors, share a high degree of amino acid sequence similarity among these receptors. From the similarity of the sequence, it is speculated that both the 1st and 2nd extracellular loop and the 4th membrane spanning domain are supposed to be involved in the opioid binding and subtype specificity. Because of the high similarity of the cytoplasmic regions' amino acid sequence, however, it seems that the signal transductions of delta, mu and kappa are very similar. In Xenopus oocytes expressing delta-opioid receptors and various kinds of GTP-binding protein alpha-subunits, the delta-agonist DSLET caused currents through Gi1 alpha (or Gi2 alpha)-phospholipase C mechanisms Neither G(o) alpha, Gq alpha, G11 alpha nor G14 alpha was involved in such delta-receptor-mediated responses. The higher concentration of DSLET (3-10 microM) showed a rapid desensitization upon repeated challenges. Such a rapid desensitization was purely homologous, and this was rescued by the pretreatment with protein kinase C inhibitor. Similar findings were also observed with mu and kappa-opioid receptors. These results suggest that the phosphorylation by protein kinase C is involved in the acute tolerance.
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PMID:[Signal transduction of cloned opioid receptors]. 795 15

Previously, we have shown that myocytes from rat portal vein express alpha 1A-adrenoreceptors that couple with a Gq/G11-protein to stimulate phosphoinositide turnover and release of calcium from intracellular stores. The purpose of this study was to investigate the contribution of both alpha 1- and alpha 2-adrenoreceptor subtypes in inducing stimulation of voltage-operated calcium channels. Norepinephrine (a nonselective alpha-adrenoreceptor agonist), phenylephrine (an alpha 1-adrenoreceptor agonist), clonidine, and oxymetazoline (alpha 2-adrenoreceptor agonists) stimulated the calcium channel current by a similar extent. Using subtype-selective antagonists we showed that both alpha 1A- and alpha 2A-adrenoreceptors modulated voltage-operated calcium channels through two distinct transduction pathways. alpha 1A-Adrenoreceptors coupled with a pertussis toxin-insensitive G-protein whereas alpha 2A-adrenoreceptors coupled with a pertussis toxin-sensitive G-protein. Portal vein myocytes expressed G-proteins that were recognized by anti-alpha q/alpha 11, -alpha i(1-2), and -alpha i(3) antibodies. As internal applications of anti-phosphatidylinositol and anti-alpha q/alpha 11 antibodies had no effect on the alpha 2A-adrenoreceptor-induced enhancement of calcium channel current, these findings suggest that phosphatidylinositol hydrolysis and Gq/G11-protein are not involved in the alpha 2A-adrenoreceptor-induced coupling process. A protein kinase C inhibitor, GF 109203X, and a long term (24 h) treatment with phorbol dibutyrate to decrease the activity of protein kinase C blocked the alpha 1A- and alpha 2A-adrenoreceptor-induced stimulation of calcium channels as well as that stimulation induced by phorbol dibutyrate. Moreover, activation of alpha 2A-adrenoreceptors did not induce a significant calcium release from intracellular stores. These data suggest that two distinct G-proteins, probably Gq/G11 and Gi, coupled to alpha 1A- and alpha 2A-adrenoreceptors regulate calcium influx through voltage-operated calcium channels by two different transduction pathways leading to activation of protein kinase C.
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PMID:Both alpha 1A- and alpha 2A-adrenoreceptor subtypes stimulate voltage-operated L-type calcium channels in rat portal vein myocytes. Evidence for two distinct transduction pathways. 796 39

Various mechanisms have been identified by which hormones and neurotransmitters, interacting with heptahelical receptors, modulate the intracellular Ca2+ concentration in neuronal, endocrine, and neuroendocrine cells. All of them involve heterotrimeric G proteins. Best documented are hormonal stimulations and inhibitions of voltage-dependent Ca2+ channels. Stimulation is caused by agonists interacting with receptors known to induce phosphatidylinositol 4,5-bisphosphate hydrolysis, that is, a PI response. Although the PI response triggers a transient secretion by fast Ca2+ release, the stimulation of Ca2+ channels is assumed to be responsible for prolonged cell responses and for refilling of IP3-sensitive Ca2+ pools after repeated stimulations. Using antisense oligonucleotide microinjection in rat pituitary GH3 cells, Gi2 has been identified as the pertussis toxin-sensitive G protein stimulating Ca2+ channels, whereas Gq/G11 are involved in the concurrent PI response with subsequent protein kinase C activation, which is required for Ca2+ channel stimulation. Inhibitory modulations of Ca2+ channels are assumed to be the basis of inhibitions of transmitter or hormone secretion. Experiments in GH3 cells have revealed that Go subforms composed of alpha o1 x beta 3 x gamma 4 and alpha o2 x beta 1 x gamma 3 are the active G-protein heterotrimers transferring inhibitory signals from muscarinic M4 and somatostatin receptors to the Ca2+ channel, respectively.
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PMID:Heterotrimeric G proteins involved in the modulation of voltage-dependent calcium channels of neuroendocrine cells. 797 80

The alpha T3-1 cell line, an immortalized gonadotroph cell line, expresses high levels of the gonadotrophin-releasing hormone (GnRH) receptor. Sustained exposure of these cells to the GnRH receptor agonist des-Gly10-[D-Ala6]luteinizing hormone-releasing hormone ethylamide resulted in a substantial down-regulation of cellular levels of a combination of the alpha subunits of the phospholipase C-beta 1-linked G proteins Gq and G11, as assessed by immunoblotting with an antiserum able to identify these two proteins equally. This effect was dependent upon the concentration of agonist used (EC50 = 4 nM) and on the time of the treatment (t1/2 = 6 hr) when a maximally effective concentration of agonist (1 microM) was used. Comparison of agonist regulation of inositol phosphate generation and Gq alpha/G11 alpha down-regulation demonstrated that effects on inositol phosphate production were approximately 3-fold more potent. In contrast to Gq alpha/G11 alpha, membrane-associated levels of Gs alpha and G12 alpha, the G proteins that transduce stimulatory and inhibitory regulation, respectively, of adenylyl cyclase, were not altered by agonist treatment. Analysis of mRNA by reverse transcriptase/polymerase chain reaction indicated the coexpression by alpha T3-1 cells of mRNA corresponding to both Gq alpha and G11 alpha. Immunoblotting with antisera selective for either Gq alpha or G11 alpha confirmed their coexpression. Resolution of membranes from untreated and agonist-treated alpha T3-1 cells under sodium dodecyl sulfate-polyacrylamide gel electrophoresis conditions able to separate Gq alpha from G11 alpha indicated that G11 alpha was more prevalent than Gq alpha at steady state but that agonist treatment regulated cellular levels of both of these G proteins in a nonselective manner. Sustained activation of protein kinase C with phorbol myristate acetate was unable to mimic agonist regulation of cellular Gq alpha/G11 alpha levels, as was treatment of alpha T3-1 cells with the selective protein kinase C inhibitor chelerythrine. These data suggest that the GnRH receptor is able to interact functionally with both Gq alpha and G11 alpha in alpha T3-1 cells and that sustained exposure to a GnRH receptor agonist selectively regulates the cellular levels of the G proteins that interact with the receptor.
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PMID:The gonadotrophin-releasing hormone receptor of alpha T3-1 pituitary cells regulates cellular levels of both of the phosphoinositidase C-linked G proteins, Gq alpha and G11 alpha, equally. 805 44

In rat pituitary GH3 cells, thyrotropin-releasing hormone (TRH) and other secretion-stimulating hormones trigger an increase in the cytosolic Ca2+ concentration by two mechanisms. Ca2+ is released from intracellular stores in response to inositol 1,4,5-trisphosphate and can enter the cell through voltage-dependent L-type Ca2+ channels. Stimulation of these channels is sensitive to pertussis toxin, indicating that a pertussis toxin-sensitive heterotrimeric guanine nucleotide-binding regulatory protein (G protein) is involved in functional coupling of the receptor to the Ca2+ channel. We identified the G protein involved in the stimulatory effect of TRH on the Ca2+ channel by type-selective suppression of G-protein synthesis. Antisense oligonucleotides were microinjected into GH3 cell nuclei, and 48 h after injection the TRH effect was tested. Whereas antisense oligonucleotides hybridizing to the mRNA of G(o) or Gi1 alpha-subunit sequences did not affect stimulation by TRH, oligonucleotides suppressing the expression of the Gi2 alpha subunit abolished this effect, and oligonucleotides directed against the mRNA of the Gi3 alpha subunit had less effect. The requirement of a concurrent inositol phospholipid degradation and subsequent protein kinase C (PKC) activation for the TRH effect on Ca(2+)-channel activity was demonstrated by inhibitory effects of antisense oligonucleotides directed against Gq/G11/Gz alpha-subunit sequences and treatment of GH3 cells with PKC inhibitors, respectively. Our results suggest that TRH elevates the cytosolic Ca2+ concentration in GH3 cells transiently via Ca2+ release from internal stores, followed by a phase of sustained Ca2+ influx through voltage-dependent Ca2+ channels stimulated by the concerted action of Gi2 (and Gi3) plus PKC.
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PMID:Gi2 and protein kinase C are required for thyrotropin-releasing hormone-induced stimulation of voltage-dependent Ca2+ channels in rat pituitary GH3 cells. 839 94

We previously reported that growth-associated protein-43 (GAP-43) could be involved in the maintenance of elongated neurites and that a decline in protein kinase C activity may be involved in accumulation of GAP-43. In the present study, to clarify the functional significance of GAP-43 for neurite maintenance and acetylcholine (ACh) release, we prepared NG-G11 cells by transfection of GAP-43 cDNA into NG108-15 cells. NG-G11 cells expressed GAP-43 mRNA at levels approximately twice that in nontransfected or vector-transfected cells under control conditions and after treatment with dibutyryl cyclic AMP (diBu-cAMP) or 12-O-tetradecanoylphorbol 13-acetate (TPA) plus diBu-cAMP. Neurite outgrowth after addition of diBu-cAMP was greater in NG-G11 than in control cells. In NG-G11 cells, neurites elongated by treatment with diBu-cAMP for 72 h were maintained after removal of the drug. Treatment with TPA plus diBu-cAMP for 24 h induced neurite outgrowth in NG-G11 cells, although control cells required 72 h. Depolarization by 50 mM KCl induced ACh release in both NG-G11 and control cells treated with diBu-cAMP or TPA/diBu-cAMP. Although removal of the drugs following diBu-cAMP treatment reversed ACh release to nontreated levels in control cells, a high-K(+)-induced level of ACh release remained in NG-G11 cells after removal of diBu-cAMP. ACh release induced by TPA plus diBu-cAMP for 24 h was further enhanced after removal of the drugs in NG-G11 cells, but it was not seen in control cells. These results suggest that levels of GAP-43 mRNA are correlated with neurite maintenance and the level of ACh release. Thus, GAP-43 may be involved in neuronal differentiation in NG108-15 cells.
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PMID:Increase in neurite formation and acetylcholine release by transfection of growth-associated protein-43 cDNA into NG108-15 cells. 839 86

Conditions were established for the primary culture of guinea-pig tracheal smooth muscle cells, the identity of which was confirmed by the presence of smooth muscle alpha-actin by western blotting. Cells were preincubated with [3H]palmitate which was incorporated, almost exclusively, into phosphatidylcholine. When these cells were stimulated by either bradykinin or phorbol 12-myristate 13-acetate (PMA), in the presence of butan-1-ol, the non-metabolizable product [3H]phosphatidylbutanol ([3H]PtdBut) accumulated by virtue of the phosphatidyltransferase activity of phospholipase D. The activation of phospholipase D by bradykinin was inhibited by 86 +/- 11% (N = 3 experiments) in the presence of the protein kinase C inhibitor, staurosporine (1 microM) and by 88 +/- 11% (N = 3 experiments) in cells that had been chronically treated with PMA to down-regulate their protein kinase C. PMA-stimulated phospholipase D was similarly affected (92 +/- 2% inhibited by staurosporine, 87 +/- 6% inhibited by protein kinase C down-regulation). Removal of extracellular Ca2+ markedly reduced the bradykinin-stimulated phospholipase D response (by 73 +/- 10%, N = 3 experiments) but had only a limited effect upon PMA-stimulated phospholipase D activity (by 23 +/- 6%, N = 3 experiments). [AIF4](-)-stimulation of the cells also resulted in the activation of phospholipase D, indicating the involvement of a G-protein. However, this was not Gi since pertussis-toxin pretreatment of the cells failed to abolish either bradykinin-stimulated inositol (1,4,5)trisphosphate formation or [3H]PtdBut accumulation. Western blotting revealed the presence of Gq/G11 which couples to the inositol lipid-directed phospholipase C. Indomethacin (10 microM) was without effect upon bradykinin-stimulated phospholipase D activity, suggesting that the bradykinin effects were not mediated indirectly by cyclooxygenase products. The role of phospholipase D activation in tracheal smooth muscle may be to, indirectly, produce diacylglycerol for the activation of protein kinase C which has been implicated in sustained contraction. However, the immediate product of phospholipase D, phosphatidate, has been proposed to have a number of second messenger roles and may itself, by an undefined mechanism, be involved in the sustained contraction of airway smooth muscle.
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PMID:Bradykinin stimulates phospholipase D in primary cultures of guinea-pig tracheal smooth muscle. 844 59

Activation of the P2Y purinoceptor on turkey erythrocytes results in a G11-mediated activation of a phospholipase C-beta isoenzyme and hydrolysis of polyphosphoinositides. The role of the protein kinase C and Ca(2+)-mobilizing arms of the inositol lipid signalling cascade in P2Y purinoceptor-induced desensitization of phospholipase C has been examined using erythrocytes as a model system. Preincubation of intact erythrocytes with either P2Y purinoceptor agonist, ADP beta S, or the protein kinase C-activating phorbol ester, phorbol 12-myristate, 13 acetate (PMA), resulted in a time of preincubation-dependent decrease in guanine nucleotide-, P2Y purinoceptor-, and beta-adrenoceptor-stimulated phospholipase C activities in membranes isolated from these cells. The extent of heterologous desensitization induced by ADP beta S and PMA were additive suggesting that they did not share a common mechanism. A lack of involvement of activation of protein kinase C in P2Y purinoceptor-induced heterologous desensitization was further supported by the observation that although protein kinase C inhibitors or down-regulation of protein kinase C resulted in a loss of PMA-induced desensitization, neither treatment affected the extent of P2Y purinoceptor-induced desensitization. In addition, elevation of intracellular Ca2+ or prevention of its elevation did not induce heterologous desensitization and had no effect on the desensitization induced by ADP beta S. Thus, neither the protein kinase C nor Ca2+ mobilizing arms of the inositol lipid signalling pathway appear to be involved in P2Y purinoceptor promoted heterologous desensitization of phospholipase C. These results are consistent with the existence of a novel feedback pathway for agonist-induced heterologous desensitization of a second messenger generating enzyme. Preincubation of cells with ADP beta S or the beta-adrenoceptor agonist, isoproterenol, followed by rechallenge with each of the receptor agonists revealed that receptor-specific desensitization occurs in addition to heterologous desensitization. Thus, multiple mechanisms account for agonist-induced desensitization of the inositol lipid signalling system of turkey erythrocytes.
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PMID:Receptor-induced heterologous desensitization of receptor-regulated phospholipase C. 856 68

The testis is a complex organ in which local control is achieved by signalling between its constituent cells. Herein we describe the responses of cultured rat testicular cells and a mouse Sertoli cell-line to stimulation by endothelin and ATP, and elsewhere we have shown that rat peritubular myoid cells possess phosphoinositidase C-coupled V1a-vasopressin receptors identical to those of liver (Howl, J. et al, 1995, Endocrinology 136: 2206-2213). 1. Peritubular myoid cells from pre-pubertal rats responded through ETA receptors with PtdIns(4,5)P2 hydrolysis [EC50 for endothelin-1 (ET-1) approximately 0.4 nM], elevation of intracellular [Ca2+], and tyrosine phosphorylation of a variety of cellular proteins. They also showed enhanced adenylate cyclase activity, with an EC50 for ET-1 of approximately 3 nM, also through ETA receptors. Pharmacological elevation of [cAMP] did not immediately change the ET-1-stimulated formation of inositol phosphates, but attenuated the response after several hours. 2. Pre-pubertal rat Sertoli cells showed no detectable responses to ET-1, but responded to FSH with elevated [cAMP] and to ATP with PtdIns(4,5)P2 hydrolysis. PtdIns(4,5)P2 hydrolysis was equally responsive to ATP and UTP, and so appears to be activated by P2U-purinergic receptors. This response was enhanced by protein kinase C inhibition and attenuated by PKC activation. 3. Despite its lack of effect on rat Sertoli cells in primary culture, ET-1 provoked PtdIns(4,5)P2 hydrolysis in the TM4 murine Sertoli cell line (EC50 approximately 0.6 nM), and this response was negatively regulated by protein kinase C activation. 5. No receptor-stimulated activation of phosphoinositase C was detected in 'germ cell' populations, but the non-specific G protein activator A1F4-provoked inositol phosphate accumulation in these cells, so demonstrating their potential to respond through yet to be identified G protein-coupled receptors with phosphoinositidase C activation. 6. Immunoblotting studies showed the presence in rat testis of phosphoinositidase C-beta 1 and the alpha-subunits(s) of the G-protein(s) Gq and/or G11. These studies show that testicular myoid and Sertoli cells use at least three G protein-coupled receptors (V1a-vasopressins, ETA-endothelin and P2U-purinergic) to signal through phosphoinositidase C activation, that ET-1 can activate multiple signalling pathways in myoid cells, and that the ET-1-stimulated phosphoinositidase C responses of myoid and Sertoli cells have different regulatory characteristics.
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PMID:Inositol lipid-mediated signalling in response to endothelin and ATP in the mammalian testis. 856 25


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