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)

COS-7 cells were transiently transfected with human thyrotropin receptor and dog A1 adenosine receptor cDNAs. An A1 agonist, N6-(L-2-phenylisopropyl) adenosine (PIA), which is ineffective alone, enhanced the thyrotropin (TSH)-induced inositol phosphate production, reflecting phospholipase C (PLC) activation, but inhibited the TSH-induced cAMP accumulation, reflecting adenylyl cyclase inhibition. These PIA-induced actions were completely inhibited by pertussis toxin (PTX) treatment. Moreover, in the cells expressing a PTX-insensitive mutant of Gi2alpha or Gi3alpha, in which a glycine residue was substituted for a cysteine residue to be ADP-ribosylated by PTX, at the fourth position of the C terminus, PIA effectively exerted both stimulatory and inhibitory effects on the TSH-induced actions although the cells were treated with the toxin. Overexpression of the betagamma subunits of the G proteins enhanced the TSH-induced inositol phosphate production without any significant effect on the cAMP response; under these conditions, PIA did not further increase the elevated inositol phosphate response to TSH. On the contrary, overexpression of a constitutively active mutant of Gi2alpha, in which the guanosine triphosphatase activity is lost, inhibited the TSH-induced cAMP accumulation but hardly affected the inositol phosphate response; under these conditions, PIA never exerted further inhibitory effects on the cAMP response to TSH. In contrast to the case of the TSH-induced inositol phosphate response, the response to a constitutively active G11alpha mutant was not appreciably affected, and that to NaF was rather inhibited by PIA and overexpression of the betagamma subunits. Taken together, these results suggest that a single type of PTX-sensitive G protein mediates the A1 adenosine receptor-linked modulation of two signaling pathways in collaboration with an activated thyrotropin receptor; alpha subunits of the PTX-sensitive G proteins mediate the inhibitory action on adenylyl cyclase, and the betagamma subunits mediate the stimulatory action on PLC. In the case of the latter stimulatory action on PLC, the betagamma subunits may not directly activate PLC. The possible mechanism by which betagamma subunits enhance the TSH-induced PLC activation is discussed.
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PMID:Betagamma subunits of pertussis toxin-sensitive G proteins mediate A1 adenosine receptor agonist-induced activation of phospholipase C in collaboration with thyrotropin. A novel stimulatory mechanism through the cross-talk of two types of receptors. 928 15

Transient expression of apoaequorin in Chinese hamster ovary (CHO) cells and reconstitution with the co-factor coelenterazine resulted in a large, concentration-dependent agonist-mediated luminescent response following cotransfection with the endothelin ETA, angiotensin ATII, thyrotropin-releasing hormone (TRH), and neurokinin NK1 receptors, all of which interact pre-dominantly with the G alpha q-like phosphoinositidase-linked G-proteins. A substantially greater luminescence was obtained with mitochondrially targeted apoaequorin compared to cytoplasmically expressed apoaequorin. To generate a system amenable for the study of agonist activity at virtually any G-protein-coupled receptor the alpha subunit of the receptor promiscuous G-protein G alpha 16 was either transiently or stably expressed in CHO cells together with apoaequorin. In cells expressing G alpha 16, but not in its absence, agonists at a series of receptors which normally interact with either G alpha s or G alpha i were now able to cause a luminescent response from mitochondrially targeted apoaequorin. In the case of the A1 adenosine receptor, this response was clearly a result of activation of G alpha 16 and not a consequence of the release of the G alpha i-associated beta/gamma complex, as the luminescent response was unaffected by pertussis toxin treatment of the cells, whereas agonist-mediated inhibition of adenylyl cyclase activity was attenuated. These studies describe the use of coexpressed apoaequorin as a reporter for G-protein-coupled receptor-mediated calcium signaling. Furthermore, coexpression of G alpha 16 and apoaequorin provides a basis for a generic mammalian cell microplate assay for the assessment of agonist action at virtually any G-protein-coupled receptor, including orphan receptors for which the physiological signal transduction mechanism may be unknown.
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PMID:A bioluminescent assay for agonist activity at potentially any G-protein-coupled receptor. 932 49

Neuropeptide Y (NPY) significantly potentiates the constrictor actions of noradrenaline and ATP on blood vessels via a pertussis toxin (PTX)-sensitive mechanism involving Gi/o (alpha beta gamma) protein subunits (Gi/o, GTP-binding proteins sensitive to PTX). In Chinese hamster ovary K1 (CHO K1) cells expressing specific receptors for these neurotransmitters, stimulation of Gi/o protein-coupled receptors for NPY and other neurotransmitters can augment the Gq/11-coupled (Gq/11, GTP-binding proteins insensitive to PTX) alpha 1B adrenoceptor- or ATP receptor-induced arachidonic acid (AA) release and inositol phosphate (IP) production (early events which may precede vasoconstriction). In this study, we have assessed the role of G beta gamma subunits in the synergistic interaction between Gi/o- (NPY Y1, 5-hydroxytryptamine 5-HT1B, adenosine A1) and Gq/11- [ATP P2Y2 (P2U)]-coupled receptors on AA release by using the specific abilities of regions of the beta-adrenergic receptor kinase (beta ARK1 residues 495-689) and the transducin alpha subunit to associate with G-protein beta gamma subunit dimers and to act as G beta gamma subunit scavengers. Transient expression of beta ARK1(495-689) in CHO K1 cells heterologously expressing NPY Y1 receptors had no significant effect on the PTX-insensitive ability of ATP to stimulate AA release. Stimulation of NPY Y1 receptors (as well as the endogenous 5-hydroxytryptamine 5-HT1B receptor and the transiently expressed human adenosine A1 receptor) resulted in a PTX-sensitive augmentation of ATP-stimulated AA release, which was inhibited by expression of both G beta gamma subunit scavengers. Expression of beta ARK1(495-689) similarly inhibited NPY Y1 receptor augmentation of ATP-stimulated IP production (a measure of phospholipase C activity), a step thought to precede the NPY Y1 receptor-augmented protein kinase C-dependent AA release previously observed in these cells. These experiments demonstrate that G beta gamma subunits, as inhibited by two different G beta gamma scavengers, significantly contribute to the synergistic interaction between NPY Y1 Gi/o- and Gq/11-coupled receptor activity, and are required for the augmentation of IP production and AA release observed in this model cell system.
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PMID:Role of G-protein beta gamma subunits in the augmentation of P2Y2 (P2U)receptor-stimulated responses by neuropeptide Y Y1 Gi/o-coupled receptors. 935 46

The regulation of the furosemide-sensitive Na+-ATPase activity and ouabain-sensitive (Na+ + K+)ATPase activities from proximal tubules by adenosine was investigated. When the concentration of adenosine was increased the furosemide-sensitive ATPase activity decreased with maximal inhibition at 10(-8) M (56% of inhibition). However, the (Na+ + K+)ATPase activity was not affected by adenosine. Theophylline, an antagonist of P1 adenosine receptor, completely reversed the effect of adenosine on the furosemide-sensitive ATPase activity in a dose-response manner. The adenosine effect was mimicked by N6-cyclohexyladenosine (CHA), an agonist for A1 adenosine receptor. 5'-N-ethylcarboxamideadenosine (NECA), an agonist for A2 adenosine receptor, did not affect the furosemide-sensitive ATPase activity. When adenosine was used in the presence of 1 microg ml(-1) pertussis toxin, a Gi protein inhibitor, no change in the furosemide-sensitive ATPase activity was observed. The addition of 1 nM cholera toxin increased the Na+-ATPase activity by 60%. Adenosine decreased the cholera toxin stimulated Na+-ATPase in 42%, similar to the effect observed in the absence of cholera toxin. Dibutyryl-cAMP reversed the effect of adenosine in a dose dependent manner while the protein kinase A peptide inhibitor mimicked it. These data are compatible with a modulatory effect of adenosine on the Na+-ATPase activity via A1 subtype receptor.
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PMID:Effect of adenosine on the ouabain-insensitive Na+-ATPase activity from basolateral membrane of the proximal tubule. 937 25

The antagonistic interactions between adenosine A1 and dopamine D1 receptors were studied in a mouse Ltk- cell line stably cotransfected with human adenosine A1 receptor and dopamine D1 receptor cDNAs. In membrane preparations, both the adenosine A1 receptor agonist N6-cyclopentyladenosine and the GTP analogue guanyl-5'-yl imidodiphospate induced a decrease in the proportion of dopamine D1 receptors in a high affinity state. In the cotransfected cells, the adenosine A1 agonist induced a concentration-dependent inhibition of dopamine-induced cAMP accumulation. Blockade of adenosine A1 receptor signal transduction with the adenosine A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine or with pertussis toxin pretreatment increased both basal and dopamine-stimulated cAMP levels, indicating the existence of tonic adenosine A1 receptor activation. Pretreatment with pertussis toxin also counteracted the effects of low concentrations of the A1 agonist on D1 receptor-agonist binding. The results suggest that adenosine A1 receptors antagonistically modulate dopamine D1 receptors at the level of receptor binding and the generation of second messengers.
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PMID:Adenosine A1 receptor-mediated modulation of dopamine D1 receptors in stably cotransfected fibroblast cells. 946 34

Suramin analogues uncouple two Gi/Go-coupled receptors, the D2 dopamine receptor in rat striatum and the A1 adenosine receptor in human cerebral cortex, with distinct structure-activity relations. This discrepancy may reflect true differences in the affinity of the analogues for specific receptor/G protein complexes or may be attributable to differences in species or in the tissue source used. We addressed this question by using human embryonic kidney 293 cells that stably express the human A1 and rat A1 receptor and the human D2 receptor. Suramin is 10-fold more potent than its didemethylated analogue NF037 in inhibiting the interaction between G proteins and the rat A1 or human A1 receptor; in contrast, both compounds are equipotent in uncoupling the D2 receptor. These differences are observed regardless of whether (1) inhibition of high affinity agonist binding to the receptors or (2) agonist-stimulated GTPgammaS binding is used as readout, (3) the receptors are allowed to interact with the G protein complement in human embryonic kidney 293 cell membranes, or (4) the receptors are forced to interact with a defined G protein alpha subunit (i.e., after reconstituting pertussis toxin-treated membranes with exogenous rGi alpha-1). The apparent affinity of suramin depends in a linear manner on receptor occupancy, which shows that suramin and the receptor compete for the G protein. Finally, the affinity of the receptors for rGi alpha-1 (human A1 > rat A1 > human D2) is inversely correlated with the potency of suramin in uncoupling ternary complexes formed by these receptors and thus determines the selectivity of the suramin analogues for specific receptor/G protein tandems.
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PMID:Differential uncoupling of A1 adenosine and D2 dopamine receptors by suramin and didemethylated suramin (NF037). 958 6

Cell motility is an essential component of tumor progression and metastasis. A number of factors, both autocrine and paracrine, have been found to influence cell motility. In the present study, adenosine and adenine nucleotides directly stimulated chemotaxis of A2058 melanoma cells in the absence of exogenous factors. Three adenosine receptor agonists stimulated motility in the melanoma cells and two adenosine receptor antagonists strongly inhibited the chemotactic response to both adenosine and AMP. The chemotactic stimulation by adenosine and AMP was pertussis toxin sensitive. Otherwise unresponsive Chinese hamster ovary cells which were transfected with the adenosine A1 receptor cDNA acquired the direct, pertussis toxin sensitive, chemotactic response to adenosine, and this response was inhibited by adenosine receptor antagonists. These findings demonstrate that adenosine and adenine nucleotides are capable of stimulating chemotaxis of tumor cells mediated through an adenosine receptor, probably of the A1 subtype. The possibility of antimetastatic therapies based on inhibition of adenosine receptor activity is raised.
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PMID:Adenosine receptor mediates motility in human melanoma cells. 961 7

We have previously reported the involvement of the striatum in acute ethanol-induced motor incoordination and the striatal adenosinergic modulation of ethanol-induced motor incoordination through A1 receptor-mediated mechanism(s). The present study, a continuation of our previous work, was carried out to investigate the possible functional correlation between striatal cyclic AMP and ethanol-induced motor incoordination, and its modulation by striatal adenosine in Sprague-Dawley rats. Forskolin (0.1, 0.5 and 1.0 pmol), a known activator of adenylate cyclase, significantly attenuated ethanol-induced motor incoordination in a dose-dependent manner following its direct intrastriatal microinfusion. Forskolin also antagonized the accentuating effect of intrastriatal N6-cyclohexyladenosine on ethanol-induced motor incoordination. These results suggested that ethanol-induced motor incoordination might be functionally correlated to a decrease in the striatal cyclic AMP levels and that the striatal adenosine A1 receptors might modulate ethanol-induced motor incoordination through cyclic AMP signaling mechanism(s). Further support to this hypothesis was obtained by the actual measurement of the striatal cyclic AMP levels in the same experimental conditions as in motor coordination studies using high-performance liquid chromatography with fluoroscence detection. Regardless of the method (focused microwave irradiation, cervical dislocation or decapitation into a dry ice-ethanol mixture) used to kill the animals, a significant decrease in the striatal cyclic AMP levels was observed due to ethanol. Intrastriatal adenosine A1-selective agonist, N6-cyclohexyladenosine (24 ng), caused a further significant decrease in the striatal cyclic AMP levels in the ethanol- but not in the vehicle-treated animals. The further enhancement in the ethanol-induced decrease in the striatal cyclic AMP levels by intrastriatal N6-cyclohexyladenosine, therefore, functionally correlated with the observed potentiating effect of intrastriatal N6-cyclohexyladenosine on ethanol-induced motor incoordination. The effects of intrastriatal N6-cyclohexyladenosine+ethanol and of ethanol alone on the striatal cyclic AMP levels were blocked by intrastriatal pertussis toxin (500 ng) pretreatment, indicating the involvement of pertussis toxin-sensitive G-proteins (Gi, Go) and possibly of the adenosine A1 receptor coupled to the G-proteins in the striatum. Furthermore, ethanol alone significantly decreased the basal as well as the cyclic AMP-stimulated catalytic activities of the striatal cyclic AMP protein kinase, which were further reduced by intrastriatal N6-cyclohexyladenosine. The results of the present study therefore support an involvement of a cyclic AMP signaling pathway in the striatal adenosinergic modulation of ethanol-induced motor incoordination at the post-adenosine A1 receptor level.
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PMID:Rat striatal adenosinergic modulation of ethanol-induced motor impairment: possible role of striatal cyclic AMP. 963 84

We have previously reported that the transfected Gi/Go protein-coupled human adenosine A1 receptor (expressed at 200 fmol/mg of protein) and the endogenous 5-HT1B receptor (not detectable using radioligand binding) suppress forskolin-stimulated cyclic AMP accumulation and stimulate increases in [Ca2+]i in Chinese hamster ovary cells (CHO). In addition, co-activation of the adenosine A1 receptor (but not the 5-HT1B receptor) potentiates the hydrolysis of inositol phospholipids elicited by receptors coupled to Gq-proteins (Dickenson and Hill, 1996. Eur. J. Pharmacol. 320, 141-151). In order to establish whether this difference in ability to modulate Gq-coupled receptor responses is a consequence of low 5-HT1B receptor density, we have stably transfected CHO-KI cells with the human 5-HT1Dbeta cDNA (the human homologue of the rodent 5-HT1B receptor). We initially isolated a clonal cell line (designated CHO5-HT1B cells) displaying moderate specific [3H]5-HT binding (pKd of 8.17+/-0.07 and a Bmax of 140 fmol/mg protein). In CHO5-HT1B cells, the selective human 5-HT1B/1D receptor agonist sumatriptan produced a concentration-dependent inhibition of forskolin-stimulated cyclic AMP accumulation (pEC50=7.92+/-0.04). Sumatriptan also elicited a moderate and pertussis toxin-sensitive increase in [3H]inositol phosphate formation in CHO-5HT1B cells (pEC50=6.51+/-0.05). Finally, sumatriptan synergistically enhanced P2U purinoceptor stimulated [3H]inositol phosphate accumulation through a pertussis toxin-sensitive mechanism. These findings clearly show the significance of 5-HT1B receptor expression level in determining whether 5-HT1B receptor activation can modulate the accumulation of [3H]inositol phosphates elicited by a Gq-protein coupled receptor. The observation that 5-HT1B receptor activation can potentiate Gq-coupled receptor stimulated second messenger responses may have an important physiological role in the regulation of vascular smooth muscle contraction.
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PMID:Human 5-HT1B receptor stimulated inositol phospholipid hydrolysis in CHO cells: synergy with Gq-coupled receptors. 965 44

1. On going work in our laboratory has shown that adenosine modulates ethanol-induced motor incoordination (EIMI) when given systemically as well as directly into the cerebral ventricles, cerebellum and corpus striatum of the rat and/or mouse. 2. The objective of this study was to determine what effect adenosine agonists and antagonists would have within the rat motor cortex on EIMI. 3. The participation of the motor cortex in EIMI was suggested when microinfusion of the anti-ethanol compound, Ro15-4513, an inverse agonist of the benzodiazepine binding site, directly into the motor cortex significantly attenuated EIMI. Further, the adenosine agonists N6-cyclohexyladenosine (CHA) and 2-p-(2-carboxyethyl)-phenethylamino-5'-N-carboxaminoadenosine++ + hydrochloride (CGS-21680) significantly accentuated EIMI in a dose-related manner. The adenosine A1 receptor-selective agonist, CHA, appeared most potent in this modulatory effect when compared to the A2-selective agonist, CGS-21680. 4. The extent of diffusion of the adenosine drugs within the cortical tissue after their microinfusion was also checked by measuring the dispersion of microinfused [3H]CHA. The [3H]CHA dispersion study indirectly confirmed that the results of the present investigation were based on the effect of adenosine drugs within the motor cortex only. 5. Accentuation by the A1- and A2-selective adenosine agonists was significantly attenuated by the A1-selective antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) but not by the A2 receptor-selective antagonist 8-(3-chlorostyryl)caffeine (CSC) further suggesting modulation mainly by the A1-subtype. 6. Pretreatment of the motor cortex with pertussis toxin (PT) significantly reduced the capacity of both A1- and A2-selective adenosine agonists to accentuate EIMI suggesting the involvement of a PT-sensitive Gi/Go protein. 7. These data support earlier work which showed that adenosine modulates EIMI within the central nervous system (CNS), most likely via the A1 receptor, and moreover, extend that work by including the motor cortex as a brain area participating in the adenosinergic modulation of ethanol-induced motor impairment.
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PMID:Adenosinergic modulation of ethanol-induced motor incoordination in the rat motor cortex. 968 75


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