Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The regulated secretory pathway comprises accelerated discharge of proteins in response to hormonal stimuli, their presence in secretory granules (SG), and a long intracellular residence time. Dexamethasone induction of AR42J results in an increase in granule content and responsiveness to cholecystokinin (CCK). We studied the effects of conditions implicated in sorting of secretory proteins into the regulated pathway using [35S]methionine pulse-chase protocols that examine transport of secretory proteins from the rough endoplasmic reticulum (RER)----SG and specifically from the Golgi complex (GC)----SG. The latter uses a chase at 20 degrees C to allow accumulation of labeled proteins in the trans-Golgi, followed by a shift to 37 degrees C that initiates their transport to SG under test conditions. Quantitation of CCK-8-stimulated discharge of prestored amylase and of newly synthesized labeled proteins that have entered SG during the chase enables us to examine the effect of perturbants over selected parts of the pathway. The effects of acidic intracellular compartments, the cytoskeleton, protein synthesis, ATP, and temperature on pre- and post-Golgi entry of proteins into the regulated pathway were studied. NH4Cl, monensin, Na azide, incubation at 20 degrees C, and pertussis toxin retarded RER----SG transport without affecting amylase discharge. Only incubation with 20 mM NH4Cl or 1 microM monensin inhibited transfer of newly synthesized proteins from the late GC----SG. RER----Golgi or intra-Golgi transport thus appears to require ATP and possibly guanosine 5'-triphosphate (GTP)-binding proteins. Acidic compartments appear to be essential for sorting of secretory proteins from the GC----SG.
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PMID:Perturbation of regulated secretion in the pancreatic acinar cell line, AR42J. 137 45

Propranolol inhibited cyclic AMP (cAMP) accumulation stimulated by 3-isobutyl-1-methylxanthine (IBMX) or forskolin in rat parotid acinar cells. The inhibition by propranolol was highly potent; 10(-7) M propranolol was sufficient for the maximum inhibition (approx. 50% at 5 min). The inhibitory effect was observed in both intact and saponin-permeabilized parotid cells, but the effect was more prominent in permeabilized cells than in intact cells. Other beta-blockers, like alprenolol and atenolol, were as effective as propranolol, but butoxamine (beta 2-selective) was slightly less effective. The inhibition by propranolol was similarly detected in the cells prepared from pertussis-toxin-pretreated rats, suggesting that inhibitory guanine nucleotide regulatory protein (Gi) is not involved in the inhibitory mechanism. Propranolol also inhibited the exocytosis of amylase stimulated by IBMX or forskolin. In the presence of propranolol and IBMX, the responsiveness of saponin-permeabilized cells to exogenous cAMP was markedly increased, indicating that propranolol neither promotes the degradation of cAMP nor prevents the inhibitory effect of IBMX on cAMP phosphodiesterase.
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PMID:Propranolol inhibits cyclic AMP accumulation and amylase secretion in parotid acinar cells stimulated by isobutylmethylxanthine and forskolin. 169 60

Competitive inhibition binding studies on membranes from the rat pancreatic AR 4-2J cell line revealed the predominance (80%) of low selectivity CCK receptors (KD of 1 nM and 4 nM for, respectively, CCK-8 and gastrin-17I (G-17I] over selective receptors (20% with a KD of 1 nM and 1 microM for, respectively, CCK-8 and G-17I). Amylase secretion was stimulated by low concentrations of CCK-8, G-17I and CCK-4. G-17I-induced amylase secretion was unaffected by 100 nM of the selective peripheral CCK-A receptor antagonist L-364,718, suggesting that amylase hypersecretion followed non-selective CCK receptor activation, a function normally assumed by selective CCK-A receptors in rat pancreatic acini. Direct ultraviolet irradiation of AR 4-2J cell membranes preloaded with 125I-BH-CCK-33 or 125I(Leu)G(2-17)I resulted in covalent cross-linking with, respectively, a 90 kDa protein and a 106 kDa protein, both distinct from the 81 kDa CCK binding species revealed in normal rat pancreatic membranes. Gpp[NH]p increased the dissociation rate of CCK-8 and G-17I from AR 4-2J cell membranes, indicating a coupling of receptors with guanyl nucleotide regulatory protein(s) G. [32P]ADP-ribosylation of AR 4-2J cell membranes allowed to detect the presence of two Gs alpha (the 50 kDa form predominating over the 45 kDa form) and one Gi alpha (41 kDa). However, Gi and Gs may not be involved in gastrin stimulation of amylase secretion, as Bordetella pertussis toxin and cholera toxin pretreatment of cells did not suppress G-17I-dependent amylase secretion.
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PMID:Functional and molecular characterization of CCK receptors in the rat pancreatic acinar cell line AR 4-2J. 170 48

Bombesin (BB), neuromedin C (NMC) and neuromedin B (NMB) stimulated amylase secretion to similar maximum levels, with EC50 values (concentrations causing 50% of maximum effect) of 0.2, 0.3 and 2 nM respectively. Treatment of pancreatic acini with BB or NMB (10 nM) for 30 min resulted in cross-desensitization of secretory responses to subsequent BB and NMB, but not to acetylcholine, which suggests that NMB and BB activate the same receptor. BB, NMC and NMB stimulated production of similar maximum amounts of inositol mono-, bis- and tris-phosphates, with EC50 values of 3, 5 and 141 nM respectively. The bombesin receptor antagonist [Leu13-psi(CH2NH)Leu14]BB inhibited stimulation of amylase secretion and inositol phosphate formation by BB, NMC and NMB. Binding of 125I-labelled gastrin-releasing peptide (GRP; 200 pM) to rat pancreatic membranes at 22 degrees C was inhibited with relative potencies and IC50 (concn. causing 50% of maximal inhibition; nM) as follows: NMC (0.4) = BB (0.5) greater than NMB (1.8 = GRP (2.6). IC50 values for BB, NMC and NMB inhibition of 125I-GRP binding to intact acini were 5-, 19- and 68-fold higher than their respective values in membranes. The guanine nucleotide analogue guanosine 5'-[beta gamma-imido]triphosphate (Gpp[NH]p) produced rightward shifts of NMC and NMB competition curves by 3.5- and 16-fold respectively, but had little effect on the BB and GRP curves. Elevation of the temperature to 37 degrees C or inclusion of NaCl (40 mM) produced quantitatively similar effects to those of Gpp[NH]p. In the presence of both NaCl and Gpp[NH]p the affinities of peptides for membrane receptors were similar to those for intact cells. Modulation of NMB competition curves by Gpp[NH]p was not attenuated by prior treatment of acini with activated pertussis toxin. These results suggest that BB, NMB and NMC stimulate pancreatic secretion by interaction with a common phosphoinositide-linked receptor. Differences in guanine nucleotide regulation suggest that secretagogue-induced receptor-protein interactions may not be identical for NMB and BB.
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PMID:Bombesin, neuromedin B and neuromedin C interact with a common rat pancreatic phosphoinositide-coupled receptor, but are differentially regulated by guanine nucleotides. 172 Jun 12

In rat pancreatic acinar cells epidermal growth factor (EGF) and insulin increase both basal and cholecystokinin (CCK-OP) stimulated amylase release in vitro (1) as a long term function of this tissue. Here we show that preincubation of isolated plasma membranes with EGF or with insulin leads to increased incorporation of the GTP-photoaffinity analogue [alpha-32P]GTP-gamma-azidoanilide into 40/41 kDa proteins and to reduction of pertussis toxin- (PT) catalyzed [alpha-32P]ADP-ribosylation of three 40/41 kDa proteins which had been previously identified as Gi1, Gi2 and Gi3 (2). In the presence of GTP gamma S, EGF- and insulin-induced inhibition of PT-mediated [alpha-32P]ADP-ribosylation of 40/41 kDa proteins is eliminated. EGF enhances cholera toxin- (CT) mediated ADP-ribosylation of all three 40/41 kDa Gi-proteins as well as of five 45 and four 48/50 kDa proteins, which had been previously identified as Gs-proteins (2), whereas insulin has no effect. We conclude from our data that both EGF and insulin interact with the same Gi-proteins as CCK-OP does, whereas EGF additionally interacts with nine Gs-proteins. It is likely that one, two or all three 40/41 kDa Gi-proteins are involved in insulin- and EGF-induced potentiation of CCK-OP-stimulated enzyme secretion. In addition interaction of EGF with Gs-protein could play a role in the potentiation of CCK-OP-induced enzyme secretion from pancreatic acinar cells.
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PMID:Receptors for insulin interact with Gi-proteins and for epidermal growth factor with Gi- and Gs-proteins in rat pancreatic acinar cells. 190 90

The role of a pertussis toxin sensitive GTP-binding protein in mediating between cholecystokinin receptors and phosphatidylinositol 4,5-bisphosphate phosphodiesterase as well as in preventing cholecystokinin from increasing cellular cyclic AMP has been investigated using dispersed acini from rabbit pancreas. Pertussis toxin pretreatment (500 ng/ml, 2 h) did not affect cholecystokinin(octapeptide) (CCK-8)-induced increases in cytosolic free Ca2+ as judged from changes in fluorescence obtained from quin2-loaded acini. Although pretreatment with pertussis toxin was also without effect on resting acinar cell cyclic AMP levels, adenylate cyclase activity was increased, since inhibition of cyclic AMP phosphodiesterase activity by isobutylmethylxanthine (IBMX) resulted in an additional increase in cyclic AMP levels in toxin-treated acini, indicating that acinar cell adenylate cyclase activity is under some tonic inhibitory control by the pertussis toxin-sensitive inhibitory GTP-binding protein (Gi) of the adenylate cyclase system. CCK-8 gave an increase in cyclic AMP levels in both control (1.6-fold) and toxin-treated (2.3-fold) acini, leading to cyclic AMP levels in the toxin-treated acini 2-times as high as those in control acini. In the presence of IBMX, the cyclic AMP response to CCK-8 was again markedly enhanced in acini pretreated with the toxin (3.2- vs. 1.8-fold), resulting in cAMP levels in the toxin-treated acini 3.7-times those in the absence of IBMX, 2.5-times those in control acini in the presence of IBMX and 7.0-times those in control acini in the absence of IBMX. Neither the pretreatment with pertussis toxin, nor the presence of IBMX alone, nor the combination had an effect on basal amylase secretion. However, all three treatments potentiated the stimulatory effect of CCK-8 on amylase secretion and the amount of potentiation was proportional to the cyclic AMP levels reached. Our findings suggest that in the intact pancreatic acinar cell Gi inhibition of the catalytic subunit of the adenylate cyclase may largely be responsible for preventing cholecystokinin from increasing cellular cyclic AMP. They moreover show that cyclic AMP is a modulatory agent in rabbit pancreatic enzyme secretion, not able to stimulate secretion itself, but potentiating effects mediated by the phosphatidylinositol-calcium pathway.
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PMID:Pertussis toxin stimulates cholecystokinin-induced cyclic AMP formation but is without effect on secretagogue-induced calcium mobilization in exocrine pancreas. 243 69

To clarify the possible role of a guanine nucleotide-binding protein (G protein) in the signal transducing system activated by cholecystokinin (CCK), actions of CCK on rat pancreatic acini were compared with those of fluoride, a well-known activator of stimulatory (Gs) or inhibitory (Gi) G protein. When acini were incubated with increasing concentrations of either CCK-octapeptide (CCK8) or NaF, a maximal stimulation of amylase release from acini occurred at 100 pM CCK8 or 10 mM NaF, respectively; this secretory rate decreased as CCK8 or NaF concentration was increased. NaF caused an increased in cytoplasmic Ca2+ concentration from the internal Ca2+ store and stimulated accumulation of inositol phosphates in acini, as observed with CCK. However, NaF-stimulated Ca2+ mobilization had a lag period before detectable stimulation and was potentiated by AlCl3. These stimulatory effects of NaF appeared to be independent of cellular adenosine 3',5'-cyclic monophosphate (cAMP). Pretreatment with cholera toxin or pertussis toxin did not affect CCK8- or NaF-induced inositol phosphate accumulation or Ca2+ mobilization. 5'-Guanylimidodiphosphate activated the generation of inositol phosphates in the [3H]inositol-labeled pancreatic acinar cell membrane preparation, with half-maximal and maximal stimulation at 1 and 10 microM, respectively. Furthermore, the effects of submaximal CCK concentrations on inositol phosphate accumulation in membranes were markedly potentiated in the presence of 100 microM GTP, which alone was ineffective. Combined findings of the present study strongly suggest that pancreatic CCK receptors are probably coupled to the activation of polyphosphoinositide (PI) breakdown by a G protein, which appears to be fluoride sensitive but is other than Gs- or Gi-like protein.
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PMID:G protein in stimulation of PI hydrolysis by CCK in isolated rat pancreatic acinar cells. 246 Oct 94

In this study, dispersed rat pancreatic acini exhibited secretin subsensitivity in their capacity to release amylase after preexposure to increasing concentrations of the muscarinic cholinergic agonist carbamylcholine. The present study also explores the potential mechanisms involved in this cellular desensitization phenomenon. Secretin subsensitivity of pancreatic acini pre-exposed to 10(-4) M carbamylcholine was observed only at secretin concentrations above 10(-8) M. The desensitized cells had not recovered 3 h after the cholinergic agonist exposure. In these acini, the adenylate cyclase pathway remained unaltered because cholera toxin, forskolin, and 8-Br-cAMP still induced weak, but normal, amylase release when compared with control acini. In vivo administration of pertussis toxin failed to protect the dispersed pancreatic acini against carbamylcholine-induced secretin subsensitivity. Moreover, cAMP production by these acini in response to secretin, cholera toxin, and forskolin was similar to that observed in control acini. Secretin stimulation of inositol phosphate (InsP1, InsP2, InsP3) production after carbamylcholine pre-exposure remained equivalent to that observed in acini that had never been exposed to the cholinergic agonist. Thus, after muscarinic cholinergic agonist exposure, pancreatic acini showed secretin subsensitivity in their capacity to release enzyme. This phenomenon appears to result from modifications at post-second messenger loci.
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PMID:Muscarinic cholinergic induced secretin subsensitivity in rat isolated pancreatic acini. Effects on amylase release, cyclic adenosine monophosphate and inositol phosphate formation. 247 85

We have recently shown that F- can mimic the actions of cholecystokinin (CCK) on amylase release, Ca2+ mobilization and inositol phosphate generation in pancreatic acinar cells. We have concluded, therefore, that pancreatic CCK receptors may be coupled to the activation of polyphosphoinositide hydrolysis by a guanine nucleotide regulatory protein (N protein), which seems to be sensitive to F-. In the present study, in order to further characterize this N protein coupled to pancreatic CCK receptors, we have examined the effects of bacterial toxins, pertussis toxin (PT) and cholera toxin (CT) on both CCK- and NaF-induced cellular responses in isolated rat pancreatic acini. Neither PT or CT pretreatment of acini affected both CCK- and NaF-stimulated increases in intracellular Ca2+ concentration monitored by quin2. Furthermore, pretreatments of acini with PT and CT didn't alter the effects of CCK on inositol phosphate generation in acini. Similarly, NaF-induced inositol phosphate generation was not changed by these toxin treatments. However, pretreatment procedures employed in this study were considered to catalyze complete ADP-ribosylation of alpha-subunit of the stimulatory (Ns) and inhibitory (Ni) N protein. These results, therefore, strongly suggest that a N protein coupling pancreatic CCK receptors to the breakdown of polyphosphoinositide may be distinct from Ns or Ni like protein.
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PMID:[Role of a guanine nucleotide regulatory protein in exocrine pancreatic secretion--effects of cholera toxin and pertussis toxin on cholecystokinin action]. 255 6

In pancreatic acinar cells, the epidermal growth factor (EGF) receptor interacts with both cholera toxin- and pertussis toxin (PTX)-sensitive G proteins. In the present study, isolated rat pancreatic acini were used to investigate the effect of EGF on basal and secretagogue-induced adenosine 3',5'-cyclic monophosphate (cAMP) production and amylase release. EGF increased cAMP production and amylase release in pancreatic acini. However, cAMP accumulation and amylase release elicited by either vasoactive intestinal peptide (VIP) or forskolin were inhibited by EGF (17 nM). EGF inhibited the VIP-induced cAMP production and amylase release with a half-maximal effective concentration of 3 and 2 nM, respectively. EGF had no effect on the N6,2'-O-dibutyryladenosine-3',5'-monophosphate-stimulated amylase release, suggesting that the inhibitory effect of EGF on the VIP- and forskolin-induced cAMP production is due to inhibition of adenylyl cyclase. PTX pretreatment of the acini led to an increase of the basal, EGF-, and VIP-stimulated cAMP accumulation and amylase release, indicating that PTX-sensitive G proteins exert tonic inhibition of adenylyl cyclase even in the absence of agonist. In PTX-pretreated acini, the inhibitory effect of EGF on the VIP-induced cAMP production and amylase release was abolished. In conclusion, these results suggest that EGF inhibits secretagogue-induced cAMP production via activation of PTX-sensitive G proteins in rat pancreatic acini, whereas EGF-induced cAMP production and amylase release occurs via a PTX-insensitive pathway.
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PMID:EGF inhibits secretagogue-induced cAMP production and amylase secretion by Gi proteins in pancreatic acini. 749 58


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