Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Vasoactive intestinal peptide (VIP), secretin, catecholamines and prostaglandin E1 (PGE1) in the presence of a cyclic nucleotide phosphodiesterase inhibitor stimulate the accumulation of cyclic AMP in two colorectal carcinoma cell lines (HT 29 and HRT 18) with subsequent activation of the cyclic AMP-dependent protein kinases. In HT 29 cells incubated without phosphodiesterase inhibitor, 10(-9) M VIP promotes a rapid and specific activation of the lower Km cyclic AMP phosphodiesterase (1.7-fold); at 25 degrees C the effect is maintained for more than 15 min, while at 37 degrees C the activity returns to basal value within 15 min. As shown by dose-response studies, VIP is by far the most effective inducer (Ka equals 4 x 10(-10) M) of the cyclic AMP phosphodiesterase activity; partial activation of the enzyme is obtained by 3 x 10(-7) M secretin, 10(-5) M isoproterenol and 10(-5) M PGE1; PGE2 and epinephrine are without effect. In HRT 18 cells VIP is less active (Ka equals 2 x 10(-9) M) whereas 10(-6) M PGE1, 10(-6) M PGE2 and 10(-5) M epinephrine are potent inducers of th phosphodiesterase activity. The positive cell response to dibutyryl-cyclic AMP further indicates that cyclic AMP is a mediator in the phosphodiesterase activation process. The incubation kinetics and dose response effects of the various agonists on the cyclic AMP-dependent protein kinase activity determined for both cell types in the same conditions show a striking similarity to those of phosphodiesterase. Thus coordinate regulation of both enzymes by cyclic AMP was observed in all incubation conditions.
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PMID:Parallel activation of cyclic AMP phosphodiesterase and cyclic AMP-dependent protein kinase in two human gut adenocarcinoma cells (HT 29 and HRT 18) in culture, by vasoactive intestinal peptide (VIP) and other effectors activating the cyclic AMP system. 626 79

Diastereomers of adenosine 3',5'-phosphorothioate activate cAMP-dependent protein kinases (cAMP-PK) in vitro. We found that these compounds are highly selective tools to monitor cAMP-dependent PKA activation and its effect on amylase exocytosis from pancreatic acini. In permeabilized rat acinar cells, (Sp)-cAMPS dose-dependently stimulated amylase secretion, while (Rp)-cAMPS inhibited (Sp)-cAMPS-induced amylase release. In intact rat acini, 8-Br-(Rp)-cAMPS reduced the secretory responses to secretin, vasoactive intestinal polypeptide (VIP), 8-Br-cAMP, and 8-Br-(Sp)-cAMPS, but not to cerulein. Another derivative, dibutyryl-(Rp)-cAMPS, induced a small inhibitory effect against 8-Br-(Sp)-cAMPS and VIP, which was overlapped by an unspecific stimulatory effect on amylase exocytosis induced by the degradation product butyrate. Furthermore, (Sp)-5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole-3',5'- monophosphorothioate ((Sp)-5,6-DCl-cBIMPS), a specific cAMP-PK activator, induced a maximal induction of cAMP-PK activity, but its stimulation of amylase secretion was less than that by secretin. (Sp)-5,6-DCl-cBIMPS regulated the phosphorylation of several proteins, which were also affected by secretin. However, secretin had additional effects. Its action was most likely mediated by a dual effect on the cAMP and the calcium pathway. Our results indicate that the cAMP-dependent pathway is involved in amylase exocytosis from rat pancreatic acini.
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PMID:Effects of synthetic cyclic AMP analogs on amylase exocytosis from rat pancreatic acini. 753 48

1. Single K(+)-selective channels with a conductance of about 48 pS (pipette, 145 mM KCl; bath, 140 mM NaCl + 4.7 mM KCl) were recorded in the patch-clamp whole-cell configuration in isolated mouse pancreatic acinar cells. 2. Neither application of the secretagogues acetylcholine (second messenger, inositol 1,4,5-trisphosphate) or secretin (second messenger, cAMP), nor addition of the catalytic subunit of protein kinase A to the pipette solution changed the activity of the 48 pS K+ channel. 3. Intracellular acidification with sodium propionate (20 mM) diminished activity of the 48 pS channel, whereas channel open probability was increased by cytosolic alkalization with 20 mM NH4Cl. 4. BaCl2 (5 mM), TEA (10 mM) or apamin (1 microM) added to the bath solution had no obvious effect on the kinetics of the 48 pS channel. Similarly, glibenclamide and diazoxide failed to influence the channel activity. 5. When extracellular NaCl was replaced by KCl, whole-cell recordings revealed an inwardly rectifying K+ current carried by a 17 pS K+ channel. 6. The inwardly rectifying K+ current was not pH dependent and could largely be blocked by Ba2+ but not by TEA. 7. Since the 48 pS K+ channel is neither Ca2+ nor cAMP regulated, we suggest that this channel could play a role in the maintenance of the negative cell resting potential.
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PMID:Characterization of single potassium channels in mouse pancreatic acinar cells. 762 83

In dispersed acini from rat pancreas, verapamil (a phenylalkylamine calcium channel blocker) potentiated amylase secretion stimulated by vasoactive intestinal peptide (VIP), secretin, peptide histidine isoleucine, helodermin, forskolin, and 8-bromocyclic AMP. The action of verapamil on VIP-stimulated amylase secretion was detectable at 10 microM verapamil and maximal at 100 microM verapamil. Verapamil did not alter binding of 125I-VIP, basal cAMP, the increase in cAMP caused by VIP, or the increase in cAMP-dependent protein kinase caused by VIP. The effects of verapamil on stimulated amylase secretion were fully reversible and could be reproduced by nicardipine (a 1,4-dihydropyridine calcium channel blocker) and diltiazem (a benzothiazepine calcium channel blocker), but not by cinnarizine (a piperazine calcium channel blocker). Although 300 microM verapamil increased outflux of 45Ca, 100 microM verapamil, the concentration that produced maximal potentiation of VIP-stimulated amylase secretion, did not alter 45Ca outflux. Our results indicate that the action of verapamil to potentiate amylase secretion stimulated by secretagogues that activate the cAMP pathway occurs at a step that is distal to the activation of cAMP-dependent protein kinase.
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PMID:Effect of verapamil on the cyclic AMP-mediated pathway for amylase secretion in rat pancreatic acini. 768 80

Conventional inhibitors of cyclic AMP-dependent protein kinase lack membrane-permeability or selectivity, or both. The Rp diastereomer of adenosine cyclic 3',5'-phosphorothioate, Rp-cAMPS, is a novel membrane-permeable antagonist of cyclic AMP. We have assessed the ability of this compound to distinguish between cyclic AMP-dependent and cyclic AMP-independent contractile responses elicited in ventricular cardiomyocytes isolated from the hearts of adult rats. Cardiomyocytes were stimulated to contract at 0.5 Hz in the presence of calcium ion (2 mM) and adenosine deaminase (5 units/ml). Contractile shortening was expressed as maximum shortening relative to prestimulus cell length (delta L%). In the presence of a maximally-effective concentration of isoprenaline (100 nM), which acts by a cyclic AMP-dependent mechanism, Rp-cAMPS inhibited the contractile response in a concentration-dependent and time-dependent manner. Following preincubation for 30 min with Rp-cAMPS (100 microM), the contractile response to isoprenaline (100 nM) was 14% of that elicited in the absence of this inhibitor. An incubation time of 30 min was chosen for all subsequent studies. Rp-cAMPS (< or = 200 microM) inhibited the contractile response to isoprenaline (100 nM) significantly and in a concentration-dependent manner, but failed to inhibit the contractile responses elicited by phenylephrine (2 microM) and calcium ion (7 mM) which act by cyclic AMP-independent mechanisms. In the presence of Rp-cAMPs (200 microM), the contractile response to isoprenaline (100 nM) was 24% of that in the absence of inhibitor. Rp-cAMPS was used subsequently to investigate the contractile-coupling mechanisms associated with some novel inotropic agents. Rp-cAMPS (< or = 200 microM) also inhibited the contractile responses to secretin (20 nM) and VIP (20 nM) significantly. In the presence of Rp-cAMPS (200 microM), the contractile response elicited by secretin (20 nM) was 19% of that in the absence of inhibitor, while that elicited by VIP (20 nM) was abolished completely. Rp-cAMPS (< or = 200 microM) failed to inhibit the contractile response elicited by CGRP (1 nM). In summary, Rp-cAMPS is a membrane-permeable, selective antagonist of cyclic AMP in ventricular cardiomyocytes and can be used, in conjunction with the bioassay of the intracellular accumulation of cyclic AMP, to distinguish between cyclic AMP-dependent and cyclic AMP-independent contractile coupling mechanisms in these cells.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Use of the cyclic AMP antagonist, Rp-cAMPS, to distinguish between cyclic AMP-dependent and cyclic AMP-independent contractile responses in rat ventricular cardiomyocytes. 789 68

Pituitary adenylate cyclase-activating polypeptide-38 (PACAP38) is a neuropeptide related to vasoactive intestinal peptide-secretin-glucagon which stimulates adenylate cyclase in cultured rat pituitary cells and stimulates LH and FSH release in vitro and in vivo. Because the cAMP-protein kinase-A pathway regulates the gonadotropin subunit messenger RNAs (mRNAs) and modulates GnRH-stimulated gonadotropin secretion in vitro, we examined the effects of PACAP38 on gonadotropin secretion and subunit mRNA levels. Anterior pituitary cells were prepared from 7-week-old male rats castrated at 5 weeks of age. In monolayer cultures stimulated with GnRH, 0.1-10 nM PACAP38 decreased (P < 0.05) the EC50 for GnRH dose-dependently without affecting the maximum LH secretory response. Cells were next stimulated with 1-min pulses of 2.5 nM GnRH every hour for 9 h in the absence or presence of 10 nM PACAP38, which was perifused continuously. The amplitude of GnRH-induced LH, FSH, and alpha-subunit secretory episodes from PACAP38-treated cells rose (P < 0.01) gradually to 233 +/- 54%, 197 +/- 44%, and 378 +/- 104%, respectively (mean +/- SEM; n = 5 experiments), of the value for control cells lacking PACAP38. This enhancement was sustained for at least 3 h after PACAP38 was removed from the perifusion medium. With PACAP treatment, interpulse secretion of LH and alpha-subunit increased gradually (P < 0.01) to 174 +/- 21% and 212 +/- 64% of the value for chambers stimulated with GnRH alone (control), respectively, whereas interpulse secretion of FSH declined (P < 0.001) to 75 +/- 7% of the control value. In contrast to the gradual effect of PACAP38 to enhance GnRH-induced hormone secretion, PACAP38 alone produced a transient burst of gonadotropin secretion. At the completion of the perifusions, total RNA was extracted and gonadotropin subunit mRNA levels were determined by Northern analysis. GnRH increased (P < 0.01) FSH beta mRNA to 438 +/- 52% of the level in cells stimulated with medium alone (control). Adding PACAP38 to the perifusion medium partially blocked (P < 0.01) the effect of GnRH (178 +/- 20% of the control value), and PACAP38 alone reduced (P < 0.01) FSH beta mRNA levels to 31 +/- 3% of the control value. By contrast, alpha-subunit mRNA levels were increased by both PACAP38 (143 +/- 4% of the control value; P < 0.01) and GnRH (121 +/- 2% of the control value; P < 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Effects of pituitary adenylate cyclase-activating polypeptide on gonadotropin secretion and subunit messenger ribonucleic acids in perifused rat pituitary cells. 791 30

We investigated the receptor mechanisms by which vasoactive intestinal polypeptide (VIP) and related peptides exert their effects on tyrosine hydroxylase (TH) gene expression. VIP, secretin, and peptide histidine isoleucine (PHI) each produced increases in TH gene expression, as measured by increases in TH mRNA levels and TH activity. The concentrations at which the effects of these peptides were maximal differed for TH activity and TH mRNA. Moreover, maximal increases in TH activity were 130-140% of control, whereas maximal increases in TH mRNA were 250% of control. The concentration dependence of the increases in TH mRNA in response to the three peptides was analyzed by fitting the data to nonlinear regression models that assume either one or two components to the response. The data for secretin fit best to a model that assumes a single component to the increase in TH mRNA levels. The data derived for PHI and VIP fit best to models that assumed two components to the TH mRNA response. These data suggested that there may be more than one receptor or signal transduction mechanism involved in the response to the various peptides. We examined whether the peptides exerted their effects through common or multiple second messenger systems. The ability of maximally active concentrations of these peptides to stimulate increases in TH mRNA was not additive, indicating that the peptides work through a common receptor or signal transduction pathway. Each peptide stimulated increases in protein kinase A (PKA) activity. Secretin and VIP were ineffective in increasing TH mRNA levels in a PKA-deficient mutant PC12 cell line (A126-1B2). Moreover, the adenylate cyclase antagonist 2',5'-dideoxyadenosine prevented the increase in TH mRNA produced by each peptide. Thus, each peptide requires an intact cyclic AMP second messenger pathway to produce changes in TH gene expression, suggesting that the complex pattern of response to VIP and PHI revealed by concentration-response analysis was due to the actions of these peptides at multiple receptors. To evaluate this possibility, we examined the effect of several peptide receptor antagonists on the increase in TH gene expression elicited by VIP, PHI, and secretin. The secretin antagonist secretin (5-27) (20 microM) had no significant effect on VIP or PHI stimulation of TH gene expression, but reduced the effect of secretin. The VIP antagonist VIP (10-28) (20 microM) reduced the effect of VIP on increasing TH mRNA, but had no significant effect on the response of TH mRNA to secretin or PHI.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Vasoactive intestinal polypeptide-related peptides modulate tyrosine hydroxylase gene expression in PC12 cells through multiple adenylate cyclase-coupled receptors. 809 40

In a guinea-pig model we determined the intracellular events mediating the response of duodenal epithelial cells to vasoactive intestinal polypeptide (VIP) and prostaglandin (PG) E2. Intravenous administration of VIP (10(-9) to 10(-7) mol/kg) and PGE2 (10(-9) to 10(-6) mol/kg) dose-dependently increased duodenal epithelial bicarbonate secretion against an HCO3- concentration gradient, measured by a luminal perfusion technique, in anaesthetized guinea-pigs up to 4.5-fold. This secretion could be mimicked by intraduodenal dibutyryl cyclic adenosine monophosphate (dBcAMP; 10(-9) to 10(-7) mol/kg). Secretin (10(-9) mol/kg) and PGF 2 alpha (10(-9) to 10(-7) mol/kg), both given intravenously, were without effect or considerably less efficient. For VIP and PGE2, specific receptors coupled to adenylate cyclase could be demonstrated in homogenates of isolated duodenal epithelial cells. VIP and PGE2 stimulated adenylate cyclase activity up to sixfold, whereas PGF2 alpha and secretin were considerably less potent and efficient. VIP and PGE2 increased intracellular cyclic AMP levels up to fivefold and ninefold, respectively. This was followed by an increase in cytosolic protein kinase A activity. Bicarbonate secretion was maximal at 30 min. Examination of the subcellular distribution of protein kinase A showed a predominant cytosolic location. These data support the notion the PGE2 and VIP cause bicarbonate secretion by the serial activation of adenylate cyclase and protein kinase A in duodenal epithelial cells.
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PMID:Cyclic adenosine monophosphate is the second messenger of prostaglandin E2- and vasoactive intestinal polypeptide-stimulated active bicarbonate secretion by guinea-pig duodenum. 817 Dec 84

Using patch-clamp recording techniques, we assessed the effects of secretin on membrane ion channel activity in isolated rat bile duct epithelial cells. In the whole cell configuration, secretin activated an inward membrane current at -40 mV in 6 of 13 cells, and increased current density from 17 +/- 8 to 98 +/- 33 pA/pF. Secretin-stimulated currents reversed near the equilibrium potential for Cl- and exhibited a linear current-voltage relationship. In the cell-attached configuration, secretin activated low-conductance channels in 73% (11 of 15) of patches. Similar channels were activated by forskolin, suggesting that adenosine 3',5'-cyclic monophosphate (cAMP) is involved as a second messenger. At the resting membrane potential, channels carried inward membrane current and had a slope conductance of 10 +/- 1 pS. In excised patches, addition of purified catalytic subunit of cAMP-dependent protein kinase (protein kinase A) to the cytoplasmic surface activated channels in four of six attempts. With equal Cl- concentrations in bath and pipette, channels had a linear slope conductance of 13 +/- 2 pS and currents reversed near 0 mV. Partial substitution of pipette Cl- with gluconate caused a shift in reversal potential in the direction anticipated for a Cl(-)-selective channel (gluconate to Cl- permeability ratio of 0.21 +/- 0.05, n = 4). Thus in bile duct epithelial cells, exposure to secretin activates low-conductance, Cl(-)-selective channels, probably through a cAMP-dependent mechanism. This likely contributes to secretin-dependent choleresis.
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PMID:Secretin activates Cl- channels in bile duct epithelial cells through a cAMP-dependent mechanism. 817 8

Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP), members of the glucagon-secretin family, have recently been suggested to be involved in the regulation of corticotropin (ACTH) secretion. In this study, we examined the effects of both peptides on POMC gene expression. Using AtT20PL, a clone of the AtT20 mouse corticotroph tumor cells stably transfected with 0.7 kb of the rat POMC 5' promoter-luciferase fusion gene, the effects of both peptides on the POMC promoter activity were estimated by a luciferase assay. PACAP stimulated POMC 5' promoter activity as well as cAMP generation and ACTH secretion in a dose- and time-dependent manner, with the maximal effect being observed 3 h after the start of incubation. A similar effect was observed with VIP. Although the combined effects of PACAP/CRH or VIP/CRH were greater than that of either hormone alone, no such effect was observed between PACAP and VIP. Furthermore, RT-PCR analysis showed the presence of only the PVR3 receptor subtype in this cell line, which is known to have a similar affinity to PACAP and VIP, indicating that both peptides exert their effects through the same receptor. In contrast to the effect of CRH, which was completely abolished by a protein kinase A inhibitor H89, the effects of PACAP/VIP on POMC expression persisted during H89 treatment, suggesting the involvement of alternative intracellular signaling pathway(s) distinct from the protein kinase A system. Our results suggest that PACAP and VIP have positive effects on POMC gene expression and that multiple signaling pathways are involved in the transcriptional event.
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PMID:Regulation of the rat proopiomelanocortin gene expression in AtT-20 cells. II: Effects of the pituitary adenylate cyclase-activating polypeptide and vasoactive intestinal polypeptide. 911 89


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