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)

CHO-K1 cells were examined for their cellular responses to the P2 receptor agonist, 2'- and 3'-O-(4-benzoylbenzoyl)-ATP (DbATP), and for the presence of mRNA for P2X receptors. Reverse transcriptase-polymerase chain reactions, using primers directed against the rat P2X subunits, detected the presence of P2X7 but not P2X1-P2X6 subunits. DbATP (EC50 approximately equal to 100 microM) evoked non-desensitizing inward currents which reversed at approximately equal to 0 mV, suggesting activation of a non-selective cation channel. ATP also evoked inward currents but was less potent than DbATP. DbATP also stimulated the accumulation of 45calcium (45Ca2+) and the DNA binding dye, YO-PRO-1, in CHO-KI cells. Both responses were inhibited by NaCl and MgCl2. In 280 mM sucrose buffer, 45Ca2+ accumulation was measurable within 10-20 s of agonist addition, whereas YO-PRO-1 accumulation was only detectable after 8 min. ATP and ATPgammaS were also agonists but were less potent than DbATP, while UTP, 2-methylthio ATP, ADP and (alphabeta)methylene ATP were inactive at concentrations up to 100 microM. DbATP increased lactate dehydrogenase release from CHO-K1 cells, suggesting cell lysis, although this effect was only pronounced after 60-90 min. These data suggest that CHO-K1 cells express an endogenous P2X7 receptor which can be activated by DbATP to cause a rapid inward current and accumulation of 45Ca2+. Prolonged receptor activation results in a delayed, increased permeability to larger molecules such as YO-PRO-1 and ultimately leads to cell lysis. Importantly, the presence of an endogenous P2X7 receptor should be considered when these cells are used to study recombinant P2X receptors.
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PMID:Identification and characterization of an endogenous P2X7 (P2Z) receptor in CHO-K1 cells. 986 47

An alternatively spliced isoform of the P2X1 receptor (P2X1a) was cloned from rat mesenteric artery. The spliced isoform does not have the 27 amino acids that are in the middle of the putative extracellular loop domain of the P2X1 original subunit (P2X1). Reverse transcriptase polymerase chain reaction (RT-PCR) revealed co-localization of P2X1a mRNA and P2X1 mRNA in vascular and other smooth muscle tissues and heart, but not in the spinal cord. In HEK293 cells transfected with P2X1 cDNA, ATP (1 microM) evoked an inward current which strongly desensitized, and an intense signal for GFP (green fluorescent protein) fused with P2X1 was detected at the membrane. Neither of these results was obtained in HEK293 cells expressing P2X1a alone. The fluorescent GFP signal was detected at the membrane when GFP-fused P2X1a was co-expressed with P2X1, and no significant difference in the ATP-activated current was noted between cells expressing P2X1 and those coexpressing P2X1 and P2X1a. These results indicate that the 27-amino-acid sequence (175-201) is important for protein trafficking to the membrane and for the formation of a functional P2X1 receptor. Our results also show that P2X1a is transported to the membrane when P2X1a is co-expressed with P2X1, although the co-expression of P2X1a does not modify the channel's current properties.
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PMID:Presence and possible role of the spliced isoform of the P2X1 receptor in rat vascular smooth muscle cells. 1120 62

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

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