Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1 In primary unpassaged rat brain capillary endothelial cell cultures (RBECs), using reverse-transcriptase PCR with primers specific for P2Y receptor subtypes, we detected mRNA for P2Y2, P2Y4 and P2Y6, but not P2Y1 receptors. 2 None of the various nucleotides tested reduced forskolin elevated cyclic AMP levels in RBECs. ATP and ATPgammaS, as well as adenosine, enhanced cyclic AMP accumulation in the presence of forskolin. 3 Comparison of the concentration response curves to ATPgammaS with those for ATP and adenosine, at different incubation times, indicated that the response to purine nucleotides was not wholly dependent on conversion to adenosine. Adenosine deaminase abolished the response to adenosine but only reduced the response to ATP by about 50%. These results suggest the participation of a receptor responsive to nucleotides. 4 Isobutylmethylxanthine and 8-sulphophenyltheophylline prevented the cyclic AMP response, while neither 8-cyclopentyl-1, 3-dipropylxanthine nor SCH58261 were effective antagonists. 2-chloradenosine gave a robust response, but neither 2-chloro-N6-cyclopentyladenosine nor CGS 21680 were agonists. 5 These results show that adenosine and ATP can elevate the cyclic AMP levels of brain endothelial cells by acting on receptors which have a pharmacology apparently distinct from known P2Y and adenosine receptors.
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PMID:Regulation of cyclic AMP by extracellular ATP in cultured brain capillary endothelial cells. 1051 Apr 59

In the search for P2-receptors modulating the stimulation-evoked entry of calcium at processes of PC12 cells differentiated in the presence of nerve growth factor and neurotrophin-3, electrically evoked increases in free calcium were assessed by fura-2 microfluorimetry. Omission of calcium and addition of cadmium (100 microM) or the N-type calcium channel blocker omega-conotoxin GVIA (0.5 microM) abolished or markedly reduced the evoked responses. The P2Y-receptor agonists 2-methylthio adenosine 5'-diphosphate (2-methylthio-ADP), ADP, and adenosine 5'-O-(2-thiodiphosphate) (ADPbetaS) inhibited the electrically evoked entry of calcium without any changes in basal calcium concentrations. 2-Methylthio-ADP was the most potent agonist. Adenosine, P(1),P(4)-di(adenosine-5')-tetraphosphate (Ap4A), UDP, and UTP (30 microM each) had no effect. The effect of ADPbetaS (30 microM) was abolished by the P2-antagonists reactive blue 2 (3 microM), suramin (100 microM), 2-methylthio-AMP (10 microM), p-chloromercuriphenyl sulfonic acid (1 microM), and AR-C 69931MX [N(6)-(2-methylthioethyl)-2-(3,3,3-trifluoropropylthio)-beta,gamma-dichloromethylene adenosine 5'-triphosphate] (300 nM). In contrast, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (10 microM), the selective P2Y1-receptor antagonist MRS 2179 (N(6)-methyl-2'-deoxyadenosine 3',5'-bisphosphate; 10 microM), as well as the adenosine A(1)-receptor antagonist DPCPX (8-cyclopentyl-1,3-dipropylxanthine; 100 nM), caused no change. Pretreatment with pertussis toxin abolished the effect of ADPbetaS. Reverse transcriptase-polymerase chain reaction revealed the presence of mRNA for P2Y12-receptors in nondifferentiated and differentiated PC12 cells. The results indicate that processes of differentiated PC12 cells possess P2Y12-receptors coupling to pertussis toxin-sensitive G-proteins and mediating an inhibition of the stimulation-evoked entry of calcium through omega-conotoxin GVIA-sensitive calcium channels. This suggests a role of P2Y12-receptors in neuromodulation in addition to their involvement in platelet aggregation.
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PMID:P2Y-receptors mediating an inhibition of the evoked entry of calcium through N-type calcium channels at neuronal processes. 1238 31

Stroking the mucosal lining of the guinea pig colon with a brush elicits an intestinal neural reflex, and an increase in short-circuit current (Isc) indicative of chloride secretion. We tested whether endogenous and exogenous nucleotides are physiologic regulators of mucosal reflexes that modulate chloride secretion. The basal Isc was augmented by 6-N,N-diethyl-beta,gamma-dibromomethylene-D-adenosine-5'-triphosphate (ARL67156) inhibition of nucleotide breakdown or adenosine A1 receptor blockade and reduced by apyrase inactivation of nucleotidases, P2 receptor antagonists, tetrodotoxin (TTX), or piroxicam. ARL67156 augmented, and apyrase inhibited, stroking-evoked Isc responses. TTX and atropine inhibited nucleotide-evoked Isc responses. The agonist potency profile for Isc, 2-methylthioadenosine-diphosphate (2MeSADP) = 2-methioadenosine-triphosphate >> 5'adenosine-triphosphate (ATP) > or = 5'adenosine-diphosphate > 5'uridine-triphosphate > or = 5'uridine-diphosphate, supports a P2Y1 receptor (R). The P2 receptor antagonists suramin and pyridoxalphosphate-6-azophenyl-2'4'-disulfonic acid, reduced stroking responses (36%) and their effects were additive. The selective P2Y1 R antagonist, 2'deoxy-N6-methyl adenosine 3',5'-diphosphate diammonium salt, reduced stroking (54%) and 2MeSADP (70%) responses at P2Y1 Rs. The P2X1/3 R agonist, alpha,betaMeATP, increased Isc. A desensitizing dose of alpha,betaMeATP reduced stroking Isc responses but did not prevent the 2MeSADP-evoked Isc response. Reverse transcriptase polymerase chain reaction analysis revealed mRNAs for P2Y1 R, P2Y2 R, P2Y4 R, P2Y6 R, and P2Y12 R in submucosa. The expression of P2Y R immunoreactivity (ir) in cell bodies of submucous neurons followed the order of P2Y1 = P2Y2 >> P2Y4 R ir; P2Y1 Rs and P2Y2 R ir were abundant (21-50% of neurons). P2Y1 R ir was abundant in cholinergic secretomotor neurons and fewer than 2% of neuropeptide Y (NPY)/choline acetyltransferase secretomotor neurons, and P2Y2 R ir was expressed in virtually all NPY secretomotor neurons and approximately 30% of calbindin/intrinsic primary afferent neurons. P2Y4 R ir was present in NPY-positive neurons. P2Y ir was rare or absent in varicose nerve fibers. The functional data support the hypothesis that mechanical stimulation with a brush releases nucleotides that act predominantly at P2Y1 Rs and to a lesser extent on P2X1/3 Rs to mediate reflex chloride secretion. A separate P2Y2 R neural circuit pathway exists that is not activated by mechanical forces. Other receptors including P2Y4, P2Y6, P2Y12, or P4 Rs cannot be excluded.
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PMID:Mechanical stimulation releases nucleotides that activate P2Y1 receptors to trigger neural reflex chloride secretion in guinea pig distal colon. 1468 70

Mechanical activation of the mucosal lining of the colon by brush stroking elicits an intestinal neural reflex and an increase in short circuit current (Isc) indicative of electrogenic chloride ion transport. We tested whether endogenous nucleotides are physiologic regulators of mucosal reflexes that control ion transport. The brush stroking-evoked Isc response in mucosa and submucosa preparations (M-SMP) of rat colon was reduced by the P2Y1 receptor (R) antagonist 2'deoxy-N6-methyl adenosine 3',5'-diphosphate diammonium salt (MRS 2179) and further blocked by tetrodotoxin (TTX). M-SMP Isc responses to serosal application of the P2Y1 R agonist 2-methylthioadenosine-diphosphate (2MeSADP) or the P2Y2/P2Y4 R agonist 5'uridine-triphosphate (UTP) were reduced but not abolished by TTX. The potency profile of nucleotides for increasing Isc was 5'adenosine-triphosphate (ATP; effective concentration at half maximal response [EC50] 0.65 x 10(4) M) congruent with UTP (EC50 1.0 x 10(-4) M) congruent with 2MeSADP (EC50 = 1.60 x 10(-4) M). Mucosal touch and distention-induced Ca2+ transients in submucous neurons were reduced by apyrase and prevented by blocking the P2Y1 R with MRS 2179 and TTX; denervation of the mucosa. It did not occur by touching a ganglion directly. 2MeSADP Ca2+ responses occurred in subsets of neurons with or without substance P (SP) responses. The potency profile of nucleotides on the neural Ca2+ response was 2MeSADP (5 x 10(-7) M) > UTP (6 x 10(-6) M) > ATP (9 x 10(-5) M). The expression of P2Y R immunoreactivity (ir) in nerve cell bodies was in the order of P2Y1 R > P2Y4 R >> P2Y2 R. P2Y1R ir occurred in the cell somas of more than 90% of neuronal nitric oxide synthase, vasoactive intestinal peptide (VIP), calretinin, or neuropeptide Y (NPY)-ir neurons, 78% of somatostatin neurons, but not in calbindin or SP neurons. P2Y2 R ir was expressed in a minority of SP, VIP, NPY, vesicular acetylcholine transporter, and calcitonin gene-related peptide-ir varicose fibers (5-20%) and those surrounding calbindin (5-20%) neurons. P2Y4 ir occurred mainly in the cell somas of 93% of NPY neurons. Reverse transcriptase polymerase chain reaction of the submucosa demonstrated mRNA for P2Y1R, P2Y2, P2Y4, P2Y6, and P2Y12 Rs. Expression of P2Y1, P2Y2, and P2Y4 protein was confirmed by western blots. In conclusion, endogenous nucleotides acting at P2YRs transduce mechanically evoked reflex chloride ion transport in rat distal colon. Nucleotides evoke reflexes by acting primarily at postsynaptic P2Y1 Rs and P2Y4 R on VIP+/NPY+ secretomotor neurons, at P2Y2 Rs on no more than 2% of VIP+ secretomotor neurons, and 2Y2 Rs mainly of extrinsic varicose fibers surrounding putative intrinsic primary afferent and secretomotor neurons. During mucosal mechanical reflexes, it is postulated that P2Y1 R, P2Y2 R, and P2Y4 R are activated by endogenous ATP, UTP, and 5'uridine-diphosphate.
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PMID:Mechanically evoked reflex electrogenic chloride secretion in rat distal colon is triggered by endogenous nucleotides acting at P2Y1, P2Y2, and P2Y4 receptors. 1468 71

The expression of purinoceptor (P2)Y-subtypes on astrocytes in vivo under physiological conditions and after stab wound injury was investigated. Reverse transcriptase-polymerase chain reaction with specific primers for the receptor-subtypes P2Y1,2,4,6,12 in tissue extracts of the nucleus accumbens of untreated rats revealed the presence of all P2Y receptor mRNAs investigated. Double immunofluorescence visualized with laser scanning microscopy indicated the expression of the P2Y1,4 receptors on glial fibrillary acidic protein (GFAP)-labeled astrocytes under physiological conditions. After stab wound injury the additional expression of the P2Y2 and P2Y6 receptors, and an up-regulation of the P2Y1,4 receptor-labeling on astrocytic cell bodies and/or processes was observed. Astrocytes of cortical, in contrast to accumbal areas exhibited P2Y1,2,4,6 receptor-immunoreactivity (IR) under control conditions, which was up-regulated after stab would injury. Labeling for the P2Y12 receptor was not observed on GFAP-positive cortical and accumbal astrocytes under any of the conditions used. For the first time, the co-localization of different P2 receptor-subtypes (e.g. P2Y1 and P2X3) on the same astrocyte was shown immunocytochemically. The up-regulation of P2Y1 receptor-IR on astrocytes and non-glial cells after mechanical injury could be facilitated by microinfusion of the P2Y1,12,13 receptor agonist adenosine 5'-O-(2-thiodiphosphate) (ADPbetaS). Proliferative changes after ADPbetaS-microinjection were characterized by means of double-staining with antibodies against GFAP and 5-bromo-2'-deoxyuridine. The non-selective P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid, the P2Y1 receptor antagonist N6-methyl-2'-deoxyadenosine 3',5'-bisphosphate and the P2Y1 receptor-antibody itself inhibited the agonist-induced effects. The data indicate the region-specific presence of P2Y receptors on astrocytes in vivo and their up-regulation after injury as well as the co-localization of P2X and P2Y receptor-subtypes on the same astrocyte. The dominant role of P2Y1 receptors in proliferation and the additional stimulation of non-P2Y1 receptors has been demonstrated in vivo suggesting the involvement of this receptor-type in the gliotic response under physiological and pathological conditions.
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PMID:P2Y receptor expression on astrocytes in the nucleus accumbens of rats. 1526 33

In this study, the P2 receptor-mediated modulation of [3H]glutamate and [3H]noradrenaline release were examined in rat spinal cord slices. Adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), and 2-methylthioadenosine 5'-diphosphate (2-MeSADP) decreased the electrical stimulation-evoked [3H]glutamate efflux with the following order of potency: ADP>2-MeSADP>ATP. The effect of ATP was antagonized by suramin (300microM), the P2Y12,13 receptor antagonist 2-methylthioadenosine 5'-monophosphate (2-MeSAMP, 10microM), and partly by 4-[[4-Formyl-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl]-2-pyridinyl]azo]-1,3-benzenedisulfonic acid (PPADS, 30microM) and the P2Y1 receptor antagonist 2'-deoxy-N6-methyladenosine 3',5'-diphosphate (MRS 2179, 10muM). ATP, ADP and 2-MeSADP also decreased evoked [3H]noradrenaline outflow; the order of agonist potency was ADP> or =2-MeSADP>ATP. The effect of ATP was reversed by 2-MeSAMP (10microM), and partly by MRS 2179 (10microM). By contrast, 2-methylthioadenosine-5'-triphosphate (2-MeSATP, 10-300microM) increased resting and electrically evoked [3H]glutamate and [3H]noradrenaline efflux, and this effect was prevented by the P2X1 receptor selective antagonist 4,4',4'',4'''-[carbonylbis[imino-5,1,3-benzenetriyl bis (carbonyl-imino)]] tetrakis (benzene-1,3-disulfonic acid) octasodium salt (NF449, 100nM). Reverse transcriptase polymerase chain reaction (RT-PCR) analysis revealed that mRNAs encoding P2Y12 and P2Y13 receptors are expressed in the brainstem, whereas P2Y13 but not P2Y12 receptor mRNA is present in the dorsal root ganglion and spinal cord. P2Y1 receptor expression in the spinal cord is also demonstrated at the protein level. In conclusion, inhibitory P2Y and facilitatory P2X1-like receptors, involved in the regulation of glutamate (P2Y13 and/or P2Y1) and noradrenaline (P2Y13 and/or P2Y1, P2Y12) release have been identified, which provide novel target sites for analgesics acting at the spinal cord level.
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PMID:Modulation of neurotransmitter release by P2X and P2Y receptors in the rat spinal cord. 1806

Human type B synoviocytes are involved in joint injury during rheumatic diseases by producing inflammatory mediators such as interleukin-6 (IL-6). The increased level of purine and pirimidine nucleotides in the synovial fluid of rheumatoid arthritis (RA) patients could activate the large family of P2 receptors. Thus, we investigated the presence of P2 receptors in human type B synoviocytes from rheumatoid joints, also evaluating whether the P2X7 receptor is involved in IL-6 release. Reverse transcriptase polymerase chain reaction analysis revealed messenger ribonucleic acid (mRNA) expression for the P2X1, P2X2, P2X4, P2X5, P2X6, P2X7, P2Y1, P2Y4, P2Y11, P2Y12, P2Y13, and P2Y14 but not the P2X3, P2Y2, and P2Y6 receptors. The expression of the P2X7 receptor was confirmed by Western blot analysis. Adenosine triphosphate (ATP) and the P2X7 receptor agonist 2'-3'-O-(4-benzoylbenzoyl)ATP (BzATP) triggered an increase in intracellular calcium, thereby suggesting the expression of functional P2 receptors, including the P2X7 receptor. Moreover, BzATP treatment upregulated both IL-6 mRNA and protein expression. Synoviocytes spontaneously released low quantities of IL-6; the incubation with BzATP induced the release of larger amounts of the cytokine, and such a release was blunted by the P2X7 antagonist oxidized ATP. The selective P2X1 and P2X3 receptor agonist alpha,beta-methylene ATP did not affect IL-6 release. Finally, BzATP failed to induce a significant uptake of the large-molecule YO-PRO, thus suggesting the lack of pore formation after P2X7 receptor stimulation. In conclusion, among the different P2 receptors expressed on human RA type B synoviocytes, the P2X7 receptor may modulate IL-6 release but not inducing changes in cell membrane permeability.
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PMID:Human rheumatoid synoviocytes express functional P2X7 receptors. 1854 80