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

Phorbol-myristate-acetate (PMA) induced in lymphocytes the production or reactive oxygen intermediates in a process which was stimulated by the presence of vasoactive intestinal peptide (VIP) in a dose-dependent response at VIP concentrations in the range 10(-11)-10(-8) M. The dissociation constant for the high-affinity receptors of VIP agreed with the ID50 of the activation of adenylate cyclase, and the ID50 for the stimulation by VIP of PMA-induced chemiluminescence, which were close to 0.2 nM VIP. Forskolin produced in lymphocytes an effect quite similar to VIP. A comparison of the response to VIP and forskolin of lymphocytes and monocytes showed that, in contrast to forskolin, VIP failed to induce the above described effect in monocytes. A possible mechanism involving protein kinase C, which is activated by PMA, and an intracellular signal linked to VIP receptors is pointed out. This study further supports a role for VIP as a mediator in the neuroimmune system.
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PMID:Vasoactive intestinal peptide enhances phorbol myristate acetate-induced chemiluminescence in human lymphocytes. 133 43

The effects of alterations in the membrane lipid environment on vasoactive intestinal peptide (VIP) binding and VIP-stimulated cyclic AMP accumulation have been analyzed by arachidonic acid treatment of prostatic epithelial cells from rats at puberty and maturity, two critical developmental periods with characteristic lipidic and androgenic statuses. Treating cells with 0.1 mM arachidonic acid for 15 min at 37 degrees C increased the affinity of VIP receptors and the potency of the neuropeptide (up to five times) in the formation of cyclic AMP at maturity, but not at puberty. The average plasma membrane fluidity (as measured by fluorescence polarization of diphenylhexatriene) remained unmodified after arachidonic acid treatment of cells. The modifications observed in mature rats were specific for the VIP receptor/effector system, since cyclic AMP stimulation by isoproterenol or forskolin was not affected by cell treatment with arachidonic acid. These results are compatible with the existence of a particular lipidic microdomain surrounding the VIP receptor in the cell membrane that would be altered by exposure to arachidonic acid (either directly or through conversion of arachidonic acid to its metabolites, as suggested by experiments on inhibition of the arachidonic acid cascade). This would make it possible for the activation of protein kinase C to phosphorylate VIP receptors in cells from mature rats, but not in those from pubertal animals with a very different membrane lipid composition (as suggested by the corresponding values of membrane fluidity and transition temperature).
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PMID:Differential effect of arachidonic acid on the vasoactive intestinal peptide receptor/effector system in rat prostatic epithelium during sexual maturation. 133 77

This study shows the presence of seven different low-molecular-weight GTP binding proteins (smg proteins) with molecular masses between 18 and 27 kDa in subfractions of rat pancreatic acinar cells. After stimulation of isolated intact and permeabilized pancreatic acinar cells with cholecystokinin octapeptide (CCK-OP), the diacylglycerol (DG) analogue 12-O-tetradecanoylphorbol 13-acetate (TPA), vasoactive intestinal peptide (VIP), adenosine 3',5'-cyclic monophosphate (cAMP), or guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), [alpha-32P]GTP binding to 21- to 22-kDa smg protein(s) in microsomal membranes (MM) was reduced, whereas the [alpha-32P]GTP binding to 23-kDa protein(s) was enhanced. In addition, prestimulation of permeabilized cells with GTP gamma S caused enhancement of [alpha-32P]GTP binding to a 19-kDa protein in MM [immunologically identified as the ADP-ribosylation factor (arf)]. In the presence of cytosol, direct addition of GTP gamma S to isolated MM resulted in an apparent translocation of the 19-kDa protein (arf) from the cytosol to membranes. This indicates increased association of arf with the membrane in its GTP-bound state. In CCK-OP-prestimulated acinar cells, [alpha-32P]GTP binding to plasma membrane-located 21- to 22-kDa proteins (immunologically identified as p21ras proteins) was enhanced, suggesting that there is an interrelationship between p21ras proteins and CCK receptors. Our results give evidence for a role of 19-kDa, 21- to 22-kDa, and 23-kDa smg proteins in cAMP-protein kinase A- and DG-protein kinase C-mediated stimulation of intracellular pathways in pancreatic acinar cells.
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PMID:Effects of agonists on p21ras and ras-related proteins in rat pancreatic acinar cells. 141 52

In rat pinealocytes, ethanol has been shown recently to inhibit the alpha 1-adrenergic potentiation of vasoactive intestinal peptide (VIP)-stimulated cyclic AMP (cAMP) and cyclic GMP (cGMP) responses, with the cGMP response being more sensitive to the inhibition. Two intracellular events known to be of importance to the potentiation mechanism are activation of protein kinase C and elevation of intracellular calcium [( Ca2+]i). In this study, we examined the effects of ethanol on these two intracellular mechanisms with an activator of protein kinase C, and two agents that elevate [Ca2+]i, depolarizing concentrations of K+ and A23187. Using dispersed pinealocytes, ethanol (up to 175 mM) was found to have no effect on the 4 beta-phorbol 12-myristate 13-acetate (PMA, an activator of protein kinase C) potentiated VIP-stimulated cAMP response. As for the cGMP response, full potentiation requires both activation of protein kinase C and simultaneous elevation of [Ca2+]i. This could be achieved by stimulating the VIP-treated cells with a combination of PMA and 15 mM K+. In the presence of ethanol, the amplification effect of PMA and K+ on the VIP-stimulated cGMP response was inhibited with an IC50 value of 125 mM. In contrast, similar concentrations of ethanol had no effect on the corresponding cAMP response. These findings suggest that the potentiation of cAMP response by protein kinase C is not affected by ethanol. When depolarizing concentrations of K+ were used to potentiate the VIP-stimulated cAMP and cGMP accumulation, ethanol inhibited the K+ potentiation of VIP-stimulated cAMP and cGMP responses with IC50 values of 50 and 30 mM, respectively. The A23187 potentiation of VIP-stimulated cGMP response was also sensitive to the inhibitory effect of ethanol with an IC50 value of 120 mM. In comparison, the corresponding IC50 value for the cAMP response was greater than 175 mM. Based on our findings, we conclude that ethanol likely inhibits a Ca(2+)-dependent event(s) that is critical to the alpha 1-adrenergic-mediated potentiation of VIP-stimulated cAMP and cGMP responses.
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PMID:Inhibitory effects of ethanol on the calcium-dependent potentiation of vasoactive intestinal peptide-stimulated cAMP and cGMP accumulation in rat pinealocytes. 165 91

We showed previously that TRH down-regulates TRH receptor (TRH-R) mRNA in GH3 cells by a mechanism that appears to be mediated by protein kinase C. Here we show that vasoactive intestinal peptide (VIP) down-regulates TRH-R mRNA and present evidence that this action is mediated by protein kinase A. In GH3 cells, VIP caused a time- and concentration-dependent decrease in TRH-R mRNA. This VIP effect was simulated by 8-(4-chlorophenylthio)-cAMP, forskolin, cholera toxin and 1-methyl-3-isobutylxanthine. When cells were incubated with agents that elevate cAMP and TRH or phorbol 12-myristate 13-acetate, the decrease in TRH-R mRNA was greater than with either agent alone. When cells were pre-incubated with H-7 [1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride], an inhibitor of protein kinases, the effects of VIP, TRH and phorbol 12-myristate 13-acetate were inhibited. We suggest that VIP, via protein kinase A, and TRH, via protein kinase C, dually regulate TRH-R mRNA.
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PMID:Evidence for dual regulation by protein kinases A and C of thyrotropin-releasing hormone receptor mRNA in GH3 cells. 165 32

In recent years evidence has accumulated indicating the presence of functional receptors for most neurotransmitters on astrocytes. In particular, receptors coupled to adenylate cyclase have been demonstrated, in primary astrocyte cultures, for vasoactive intestinal peptide (VIP), noradrenaline (NA) and adenosine. Here we provide, in primary cultures of cerebral cortical astrocytes prepared from neonatal mice, a detailed characterization of a cAMP-dependent process elicited by VIP, NA and adenosine, i.e. the hydrolysis of glycogen. The EC50s for the glycogenolytic effect of VIP, NA and adenosine are 3, 20 and 800 nM, respectively. The initial rate of glycogen hydrolysis is, in nmol/mg prot/min, 9.1 for VIP and 7.5 for NA. The effect of NA is predominantly mediated by beta-adrenoceptors, although an alpha 1-adrenergic component, acting most likely through protein kinase C activation, is also present. The action of VIP is mimicked by peptides sharing sequence homologies such as PHI and secretin. Glutamate, GABA, carbachol and the peptides NPY and somatostatin do not influence glycogen levels. The glycogen content of the cultures can be markedly increased by anabolic factors present in fetal calf serum, by high (e.g. 25 mM) glucose in the medium and by 48-h pretreatment of the cultures with dibutyryl cAMP. These results indicate that the glycogen content of astrocytes is under the dynamic control of various factors, including certain neurotransmitters. They also further stress the notion of a functional interaction between neurons and glial cells aimed at maintaining local energy metabolism homeostasis.
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PMID:Characterization of the glycogenolysis elicited by vasoactive intestinal peptide, noradrenaline and adenosine in primary cultures of mouse cerebral cortical astrocytes. 166 73

Transcription of the human vasoactive intestinal peptide (VIP) gene is regulated by both cyclic AMP and phorbol esters. A 17-nucleotide enhancer element within the human VIP gene mediates transcriptional activation by both phorbol esters and forskolin. Mutations of this element decrease responses to both agents, suggesting that the trans-acting proteins that mediate both modes of transcriptional regulation have similar DNA-binding characteristics. The response of the VIP enhancer element to forskolin, but not to 12-O-tetradecanoylphorbol-13-acetate, was attenuated by treatment with a recombinant inhibitor of the cAMP-dependent protein kinase, suggesting that the cAMP-dependent protein kinase and protein kinase C second messenger pathways that converge on this single enhancer element are distinct. The transcriptional activator cAMP-responsive element-binding (CREB) proteins and the c-fos.c-Jun complex interact with the VIP enhancer. The dual second messenger responses of the VIP gene may result from the interaction of this second messenger enhancer with different transcriptional activator proteins.
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PMID:Cyclic AMP- and phorbol ester-induced transcriptional activation are mediated by the same enhancer element in the human vasoactive intestinal peptide gene. 184 91

A somatomammotropic cell line (P0) derived from adult rat pituitaries has been maintained in culture for 2 yr. Secretion of GH and PRL by this cell line has been studied in response to hypophysiotropic peptides known to affect the release of both hormones as well as agents that affect second messenger systems in an attempt to characterize the stimulus-secretion mechanisms used by these cells. GH and PRL release during short term (4 h) incubations of P0 cells and primary cultures of dispersed rat pituitary cells was initially measured in response to GRF, TRH, vasoactive intestinal peptide (VIP), and SRIF. In P0 cells, the minimal effective dose of each of the hypophysiotropic peptides was comparable with respect to GH and PRL secretion. The effects of TRH and VIP were similar to those in freshly dispersed cells with respect to PRL release, whereas those of GRF and SRIF were less potent with respect to GH release. The stimulation of GH and PRL release in P0 cells by adenylate cyclase-related agents ((Bu)2 cAMP and forskolin) was comparable to that for GH secretion in mature somatotrophs but much greater than that of PRL release in mature lactotrophs. Stimulation of GH and PRL release in P0 cells by protein kinase C-related agents (diacylglycerol and phorbol ester) was also similar to that observed for GH release from mature pituitary cells, whereas minimal or undetectable effects were observed on PRL release from mature cells. The results indicate that the P0 somatomammotropic cell line possesses receptors, second messenger systems, and secretory characteristics of both somatotrophs and lactotrophs, although where differences exist, there is more resemblance to somatotrophs. They also demonstrate that the responses to each of the agents studied are bihormonal and appear to be regulated by a common mechanism.
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PMID:Growth hormone and prolactin secretion in cultured somatomammotroph cells. 197 45

We have examined the actions of vasoactive intestinal peptide (VIP) and certain other known immune modulators on a nuclear pool(s) of protein kinase C (PKC) in isolated rat splenocyte nuclei. Rat splenocyte nuclei pure by enzymatic and electron microscope criteria demonstrated a time- and concentration-dependent activation of nuclear PKC (nPKC) by VIP. A biphasic pattern of three bell-shaped curves was observed with peak phosphorylation at 10(-15), 10(-9) and 10(-6)M VIP. The phosphorylation of endogenous nuclear substrates was characterized as a PKC-mediated event by use of three known PKC inhibitors, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), sphingosine, and staurosporine, which produced similar phosphate incorporation measurements. Also, this activity was blocked with the addition of a monoclonal antibody to PKC. Inhibitors of the ability of VIP to activate nPKC included somatostatin, 8-bromo-cAMP, peripheral benzodiazepine receptor modulators, and the PKC inhibitors, sphingosine and staurosporine. These data have direct relevance to our knowledge of cell-mediated immunity.
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PMID:Vasoactive intestinal peptide (VIP) activation of nuclear protein kinase C in purified nuclei of rat splenocytes. 197 36

We examined the effect of cholecystokinin (CCK) on the receptors for vasoactive intestinal peptide (VIP) and secretin in rat pancreatic acini. CCK decreased the specific binding of 125I-VIP and 125I-secretin by 42 and 51%, respectively. This CCK-induced inhibition was caused by an apparent decrease in the capacity of high-affinity binding sites of VIP and secretin receptors. CR 1409, a specific antagonist of CCK, abolished CCK-induced binding inhibition, whereas 12-O-tetradecanoylphorbol-13-acetate, A23187, and cycloheximide did not affect the binding of the radioligands. Both N2,O2-dibutyryl guanosine 3',5'-cyclic monophosphate (Bt2cGMP) and nitroprusside inhibited the specific binding of 125I-VIP. This inhibition, however, was because of an apparent decrease in the capacity of low-affinity binding sites on VIP receptors. CCK-induced downregulation of VIP and secretin receptors was associated with the diminished acinar response to VIP or secretin-induced adenosine 3',5'-cyclic monophosphate accumulation and amylase secretion, whereas neither Bt2cGMP nor nitroprusside affected VIP-induced amylase secretion. Data suggest that CCK-induced downregulation is mediated by the initial interaction of CCK with CCK receptors followed by some postreceptor process, which appears unrelated to protein kinase C, calcium mobilization, decrease in protein synthesis, or cellular cGMP increases. This downregulation, at least in part, accounts for CCK-induced restricted stimulation of amylase secretion by VIP and secretin.
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PMID:Cholecystokinin downregulates receptors for vasoactive intestinal peptide and secretin in rat pancreatic acini. 215 42


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