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)

It has been proposed that certain cytokines secreted by islet-infiltrating leukocytes may be involved in the pathogenesis of insulin-dependent diabetes mellitus by participation in beta-cell destruction. In the present study, the impact of various cytokines on replication and long-term insulin secretion by pancreatic beta-cells was investigated. To this end, fetal rat pancreatic islets containing a high fraction of beta-cells were exposed in culture for 1-3 days to interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interferon-alpha (IFN-alpha), and interleukin-6 (IL-6) at different concentrations. It was found that IL-1 beta markedly decreased beta-cell DNA synthesis during the first day of exposure, an effect that vanished after 2 days and was turned into a potent and dose-dependent stimulation by 3 days of exposure. At this latter time point, IL-1 beta also amplified the mitogenicity of growth hormone (GH) and 16.7 mM glucose. In contrast, basal as well as glucose- and GH-stimulated insulin secretion was consistently suppressed by IL-1 beta from days 1-3. IL-1 beta also lowered the islet adenosine 3',5'-cyclic monophosphate (cAMP) content at all time points studied. However, addition of the stimulatory cAMP analogue Sp-diastereomer of adenosine 3',5'-cyclic monophosphothioate or pertussis toxin, which themselves enhanced DNA synthesis and insulin secretion, failed to prevent the inhibitory actions of IL-1 beta on these parameters, making it unlikely that a decrease in cAMP is an important event in transduction of the inhibitory effects of the cytokine.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential effects of cytokines on long-term mitogenic and secretory responses of fetal rat pancreatic beta-cells. 132 36

The Nb2 node lymphoma cell line has been widely used as a model for investigating lactogen cellular actions. Both pertussis (PTX) and cholera (CTX) toxins modulate lactogen-stimulated Nb2 cell mitogenesis, suggesting G protein involvement in lactogen signal transduction. The following studies were performed to further investigate this possibility. Both PTX-sensitive (41 kDa) and CTX-sensitive substrates (42 and 45 kDa) were identified in Nb2 cell membrane and recognized by specific anti-Gi and anti-Gs antibodies, respectively. Equal numbers of Nb2 cells were then incubated with the lactogen human growth hormone (hGH, 10 ng/ml) for 0-72 h. Membrane protein prepared from each time point (50 micrograms) was compared in toxin-stimulated ADP-ribosylation studies. CTX-stimulated ADP-ribosylation was unaffected by prior hGH incubation. PTX-stimulated ADP-ribosylation increased 237 +/- 69% (X +/- S.E.) compared with 0-h controls (n = 11; p less than 0.01) after 4-7 h of hGH incubation then decreased toward 0-h samples by 24 and 72 h. No change in Gi alpha concentration was observed, but beta subunit concentration increased (145 +/- 14% at 7 h; p less than 0.01; n = 3) in a time course that paralleled the changes in PTX-stimulated ADP-ribosylation. In summary, 1) both Gi and Gs were present in Nb2 cell membrane, 2) incubation of cells with a lactogen, hGH, for 4-7 h markedly enhanced PTX-stimulated ADP-ribosylation of Gi alpha in vitro, whereas CTX-stimulated ADP-ribosylation of Gs alpha was unchanged, and 3) although no change in Gi alpha concentration was observed, beta subunit concentration increased in parallel with the increase in PTX-stimulated ADP-ribosylation of Gi alpha. These results suggest that hGH may modify PTX-stimulated ADP-ribosylation of Gi not by changing Gi alpha concentration, perhaps by increasing beta subunit concentration, enhancing association of Gi alpha by beta gamma subunits, which, in turn, is preferentially ADP-ribosylated. This may represent a late signal transduction event and may also have implications for other effectors dependent on Gi-mediated events.
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PMID:Human growth hormone enhances pertussis toxin-stimulated ADP-ribosylation of Gi in Nb2 cell membrane. 158 39

Several cAMP-elevating agents such as cholera toxin (CT), forskolin and 3-isobutyl-1-methylxanthine (IBMX) exhibited weak mitogenic activity on bovine undifferentiated mammary epithelial cells in three-dimensional collagen culture. CT and IBMX strongly synergized with epidermal growth factor (EGF), insulin-like growth factor I (IGF-I) or both, but not with 10% fetal calf serum (FCS). Permeable cAMP analogs also synergized with IGF-I. Other hormones such as ovine prolactin, bovine growth hormone, estrogen or progesterone were not mitogenic and not synergistic with EGF, IGF-I, CT and FCS. Pertussis toxin (PT) reduced the DNA synthesis in cells cultured in the basal medium and attenuated 40-90% of the mitogenic activity stimulated by 10% FCS. PT inhibition of DNA synthesis was accompanied by ADP-ribosylation of 40 kDa and 41 kDa membrane proteins. The 41 kDa protein cross-reacted with antibodies that recognize the Gi-protein of the adenylate cyclase system, indicating the involvement of the latter in the mitogenic process. The nature of the second protein remains unknown. The present results suggest that the mitogenesis of normal mammary epithelial cells which is stimulated by IGF-I, EGF and other factors found in FCS is mediated through both cAMP-dependent and independent pathways. These pathways include PT-sensitive GTP-binding proteins.
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PMID:Proliferation of bovine undifferentiated mammary epithelial cells in vitro is modulated by G-proteins. 169 21

Bovine mammary undifferentiated epithelial cells from young female calves, cultured in three-dimensional collagen gels in serum-free medium exhibited ultrastructural organization that resembled the in vivo situation. Extracts of bovine pituitary, kidney, uterus and mammary gland, stimulated cell proliferation in a dose-dependent manner. This mitogenic activity strongly synergised with the existant growth factors (GFs) in FCS and with IGF-I, while the addition of EGF had only minor effect. No synergistic manifestation was found with cholera toxin but pertussis toxin inhibited the growth-promoting activity of all four extracts. Other experiments indicated that this mitogenic activity does not result from prolactin, growth hormone or fibroblast growth factor. The present and former results, in which synergism between IGF-I and cholera toxin was demonstrated, suggest therefore, that the mitogenesis of normal mammary epithelial cells regulated by several tissue derived growth factors, consists of at least two pathways which are distinct from those activated by EGF and IGF-I. One of these pathways indicates involvement of pertussis toxin-sensitive GTP-binding proteins, and the other, activation of cholera toxin-sensitive adenylate cyclase.
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PMID:Bovine pituitary, kidney, uterine and mammary gland extracts contain bovine mammary epithelium growth factors that synergise with IGF-I and fetal calf serum: indication for involvement of GTP-binding proteins. 190 89

1. Somatotrophs were obtained from rat pituitary glands after dissociation, separation and enrichment on a continuous gradient of bovine serum albumin at unit gravity. Somatotrophs were enriched up to 85% in the heavy fractions (F8 and F9). 2. After identification by reverse hemolytic plaque assay, patch-clamp recording in the whole-cell mode was performed on somatotrophs. 3. Under voltage-clamp conditions, two types of Ca2+ currents were recorded. From a holding potential of -70 mV, depolarizing voltage steps to potentials more positive than -50 mV activated a current which rapidly inactivated and which was very sensitive to Ni2+ but not to Cd2+. This current corresponds to T-type current. Depolarizing steps to potentials more positive than -30 mV from a holding potential of -40 mV triggered a current which slowly inactivated and which was very sensitive to Cd2+ but not to Ni2+. This current corresponds to L-type current. 4. Application of somatostatin to the bath solution (10 nM) markedly reduced the amplitudes of both T- and L-type currents. Somatostatin decreased the conductance of L-type current without modifying its time- and voltage-dependent inactivation but its activation was not affected. However, somatostatin decreased the conductance of T-type currents, and also accelerated its time-dependent inactivation. Half-inactivation voltage of T-type current was shifted from -52 to -63 mV by somatostatin but no change was obtained in the current activation curve. 5. All these modifications in Ca2+ currents were abolished by a pre-treatment of the cultures with pertussis toxin (100 ng/ml, for 10 h). This pre-treatment also blocked the inhibitory effect of somatostatin on high-K(+)-stimulated growth hormone release. 6. Our results show that somatostatin acts on somatotrophs by attenuating the voltage-dependent Ca2+ currents. These effects may contribute to a somatostatin-induced reduction in [Ca2+]i and the subsequent decline in growth hormone release.
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PMID:Two types of voltage-dependent calcium current in rat somatotrophs are reduced by somatostatin. 197 2

D2 dopamine receptors and somatostatin receptors in adenohypophyseal cells are coupled through G proteins to various transduction mechanisms. To study the involvement of these different transduction mechanisms and of various G proteins in the dopamine and somatostatin regulation of prolactin (PRL), growth hormone (GH) and thyroid-stimulating hormone (TSH) secretions, we have pretreated the adenohypophyseal cells in primary culture with increasing doses of pertussis toxin. The guanosine triphosphate (GTP) dependency of the negative coupling of dopamine and somatostatin receptors with adenylate cyclase in the same membrane preparation from anterior pituitary cells was different. In fact, higher GTP doses were requested to obtain dopamine inhibition, suggesting that different G proteins were involved in the coupling of these two receptors with adenylate cyclase. However, the inhibition of adenylate cyclase activity by both neurohormones was fully sensitive to pertussis toxin pretreatment with a similar IC50 for the toxin. The IC50 for the toxin was also similar for the blockade of dopamine or somatostatin inhibition of the three-hormone secretion as well as for the stimulation on basal PRL or GH secretion or the reduction of thyrotropin-releasing hormone (TRH)-stimulated prolactin secretion, suggesting that the toxin acts through similar mechanisms on these different phenomena. Pretreatment of the cells with Bordetella pertussis toxin differentially affected the effects of both neurohormones on the three cell types. A complete reversion of the inhibition of secretion was observed only in the case of somatostatin on PRL and TSH cells. In contrast, the somatostatin inhibition of GH secretion was only partially reversed by the pertussis toxin pretreatment. This was also the case of dopamine inhibition of PRL secretion. It can be concluded that: (1) On PRL secretion dopamine and somatostatin do not share all the mechanisms since the intensity of their inhibition and the reversibility of their effects by pertussis toxin were differential. (2) Different mechanisms of action are implicated in the effect of somatostatin on PRL, GH and TSH secretions. (3) Different G proteins might be involved in the coupling of dopamine and somatostatin receptors with adenylate cyclase.
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PMID:Differential coupling with pertussis toxin-sensitive G proteins of dopamine and somatostatin receptors involved in regulation of adenohypophyseal secretion. 198 65

Growth Hormone has recently been shown to stimulate the formation of diacylglycerol in Ob1771 mouse preadipocyte cells without increasing inositol lipid turnover. Addition of growth hormone to Ob1771 cells prelabelled with [3H]glycerol or [3H]choline led to a rapid, transient and stoechiometric formation of labelled diacylglycerol and phosphocholine, respectively. In contrast, no change was observed in the level of choline and phosphatidic acid whereas the release of water-soluble metabolites in [3H]ethanolamine prelabelled cells exposed to growth hormone was hardly detectable. Stimulation by growth hormone of cells prelabelled with (2-palmitoyl 9, 10 [3H])phosphatidylcholine also induced the production of labelled diacyglycerol. Pertussis toxin abolished both diacylglycerol and phosphocholine formation induced by growth hormone. It is concluded that growth hormone mediates diacylglycerol production in Ob1771 cells by means of phosphatidylcholine breakdown involving a phospholipase C which is likely coupled to the growth hormone receptor via a pertussis toxin-sensitive G-protein.
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PMID:Diacylglycerol production induced by growth hormone in Ob1771 preadipocytes arises from phosphatidylcholine breakdown. 212 19

In anterior pituitary cell aggregates cultured in the presence of the glucocorticoid dexamethasone (DEX) angiotensin II (AII) had a dual effect on growth hormone (GH) release. The peptide stimulated the release in aggregates from 2-week-old rats, whereas the peptide had an inhibitory effect in cultures from adult rats. Treatment of aggregates from adult rats with pertussis toxin (PT) reversed the inhibitory effect of AII on GH release in a stimulatory effect; PT treatment of aggregates from 18- to 20-day-old rats significantly enhanced the stimulation of GH release by AII. The effect of PT was seen only when DEX was added to the culture medium. The present data suggest that the glucocorticoid-dependent stimulus-effect coupling of AII on GH release involves both a stimulatory and an inhibitory component, the latter being abolished by PT, and that the stimulatory component predominates during immature life while the inhibitory one during adult life.
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PMID:Evidence for a pertussis toxin-sensitive signalling pathway in the dual action of angiotensin II on growth hormone release in pituitary cell aggregates. 212 23

Calmodulin-activated, adenylate cyclase toxin, a virulence factor produced by the human respiratory pathogen Bordetella pertussis, elicits marked accumulation of cyclic AMP in cell lines from rat pituitary tumors. This effect is associated with and apparently responsible for an enhanced release of prolactin and/or growth hormone from GH3, GH4C1 and 235-1 cells. The utility of this novel toxin in probing cyclic AMP-mediated responses is supported by these observations and studies with pertussis and cholera toxins.
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PMID:Bacterial adenylate cyclase increases cyclic AMP and hormone release in pituitary tumor cells. 287 35

Somatostatin (SRIF) is a potent inhibitor of growth hormone (GH) secretion. Although cyclic AMP (cAMP) has been suggested as intracellular mediator of SRIF action, a complete characterization of its effect and the different sensitivity between male and female animals, has not yet been carried out. In this study SRIF inhibited basal and GH-releasing factor (GRF) stimulated anterior pituitary adenylate cyclase activity with a greater effectiveness in male than in female glands. Similarly SRIF reduction of forskolin-stimulated anterior pituitary adenylate cyclase activity, was more pronounced in male than in female animals. By using pertussis toxin (PTX), which uncouples inhibitory receptors from adenylate cyclase catalytic subunit, SRIF inhibition of both basal and forskolin-stimulated adenylate cyclase activity was nearly abolished. These results show that anterior pituitary SRIF receptors are coupled in an inhibitory fashion with adenylate cyclase enzyme, and that male rat adenohypophyses are more responsive to SRIF inhibition.
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PMID:Somatostatin inhibition of anterior pituitary adenylate cyclase activity: different sensitivity between male and female rats. 289 42


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