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)

Hepatocyte function is regulated by several P2Y receptor subtypes. Here we report that 2-methylthioadenosine 5'-diphosphate (2-MeSADP), an agonist at P2Y(1), P2Y(12), and P2Y(13) receptors, potently (threshold 30 nM) stimulates glycogen phosphorylase in freshly isolated rat hepatocytes. Antagonism by N(6)-methyl 2'-deoxyadenosine 3',5'-bisphosphate (MRS 2179) confirms that this response is mediated by P2Y(1) receptors. In addition, in these cells, both 2-MeSADP and UTP inhibited glucagon-stimulated cyclic AMP accumulation. This inhibitory effect of 2-MeSADP was not reversed by the P2Y(1) antagonists, adenosine-3'-phosphate-5'-phosphate (A3P5P) or MRS 2179, both in the range 1 to 300 microM, indicating that it was not mediated by P2Y(1) receptors. This contrasts with the increase in cytosolic free Ca(2+) concentration ([Ca(2+)](c)) induced by 2-MeSADP, which has shown to be inhibited by A3P5P. Pertussis toxin abolished the inhibitory effect of both UTP and 2-MeSADP. After culture of cells for 48 h, the ability of 2-MeSADP to inhibit cyclic AMP accumulation was greatly diminished. Reverse transcriptase-polymerase chain reaction analysis revealed that during this culture period, there was a decline in the ability to detect transcripts for P2Y(12) and P2Y(13) receptors, both of which are activated by 2-MeSADP and negatively coupled to adenylyl cyclase. However, in freshly isolated cells, the P2Y(12) and P2Y(13) receptor antagonist, 2-propylthio-beta,gamma-dichloromethylene-d-ATP (AR-C67085) (10 nM to 300 microM) did not alter the ability of 2-MeSADP to inhibit glucagon-stimulated cyclic AMP accumulation. We conclude that 2-MeSADP regulates rat hepatocyte glycogen phosphorylase by acting on P2Y(1) receptors coupled to raised [Ca(2+)](c), and by inhibiting cyclic AMP levels by an unknown G(i)-coupled receptor subtype, distinct from P2Y(1), P2Y(12), or P2Y(13) receptors.
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PMID:Regulation of rat hepatocyte function by P2Y receptors: focus on control of glycogen phosphorylase and cyclic AMP by 2-methylthioadenosine 5'-diphosphate. 1515 27

RANTES, a CC chemokine, plays an important role in the inflammatory response associated with Helicobacter pylori infection. However, the mechanism by which H. pylori induces RANTES expression in the gastric mucosa is unknown. We cocultured gastric epithelial cells with wild-type H. pylori, isogenic oipA mutants, cag pathogenicity island (PAI) mutants, or double knockout mutants. Reverse transcriptase PCR showed that RANTES mRNA was induced by H. pylori and that the expression was both OipA and cag PAI dependent. Luciferase reporter gene assays and electrophoretic mobility shift assays showed that maximal H. pylori-induced RANTES gene transcription required the presence of the interferon-stimulated responsive element (ISRE), the cyclic AMP-responsive element (CRE), nuclear factor-interleukin 6 (NF-IL-6), and two NF-kappaB sites. OipA- and cag PAI-dependent pathways included NF-kappaB-->NF-kappaB/NF-IL-6/ISRE pathways, and cag PAI-dependent pathways additionally included Jun N-terminal kinase-->CRE/NF-kappaB pathways. The OipA-dependent pathways additionally included p38-->CRE/ISRE pathways. We confirmed the in vitro effects in vivo by examining RANTES mRNA levels in biopsy specimens from human gastric antral mucosa. RANTES mRNA levels in the antral mucosa were significantly higher for patients infected with cag PAI/OipA-positive H. pylori than for those infected with cag PAI/OipA-negative H. pylori or uninfected patients. The mucosal inflammatory response to H. pylori infection involves different signaling pathways for activation of the RANTES promoter, with both OipA and the cag PAI being required for full activation of the RANTES promoter.
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PMID:Regulation of RANTES promoter activation in gastric epithelial cells infected with Helicobacter pylori. 1623 64

Brucella species are able to survive and replicate within the phagocytic vacuole of macrophages that induce chronic infection in humans and domestic animals. The activation of oxidative bactericidal activity is one of the defense systems which protect the host from the toxic effects of pathogens. The aim of this study was to evaluate lipid peroxidation, NO production, antioxidative system and inflammation during a period of brucella infection in a rat model; in addition to investigate the role of elevated intracellular cyclic AMP on Brucella-induced events. Brucella significantly induced lipid peroxidation in plasma, liver and spleen by 3-5-fold at 7 days postinfection. NO concentration was significantly elevated in the liver and spleen while unchanged in plasma. Cyclic AMP elevating agent, rolipram, administration (1mg/kg/day i.p., 3 days) gradually suppressed lipid peroxidation and NO formation to the basal level in plasma and spleen whilst only a slight decrease was observed in liver. Brucella considerably decreased SOD activity in the liver and spleen, with rolipram restoring the enzyme activity in liver and activity in spleen being unchanged. Reverse transcriptase PCR analyses showed that Brucella melitensis does not alter TNF-alpha and IFN-gamma transcriptions in liver and spleen. The pathogen did not consistently induce nitric oxide synthase mRNA transcriptions in animals; even in those housed in the same group. IL-10 transcription was induced by rolipram in spleen but not in liver. Our results suggest that activation of the cAMP/PKA pathway suppressed lipid peroxidation and the elevated NO concentrations caused by B. melitensis. Moreover, rolipram induced anti-inflammatory cytokine IL-10 transcription and SOD activity, albeit in a tissue dependent manner.
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PMID:Elevated cAMP levels reverse Brucella melitensis-induced lipid peroxidation and stimulate IL-10 transcription in rats. 1701 75

The basis for a dual inhibitory and mutagenic activity of 5-fluorouracil (5-FU) on foot-and-mouth disease virus (FMDV) RNA replication has been investigated with purified viral RNA-dependent RNA polymerase (3D) in vitro. 5-Fluorouridine triphosphate acted as a potent competitive inhibitor of VPg uridylylation, the initial step of viral replication. Peptide analysis by mass spectrometry has identified a VPg fragment containing 5-fluorouridine monophosphate (FUMP) covalently attached to Tyr3, the amino acid target of the uridylylation reaction. During RNA elongation, FUMP was incorporated in the place of UMP or CMP by FMDV 3D, using homopolymeric and heteropolymeric templates. Incorporation of FUMP did not prevent chain elongation, and, in some sequence contexts, it favored misincorporations at downstream positions. When present in the template, FUMP directed the incorporation of AMP and GMP, with ATP being a more effective substrate than GTP. The misincorporation of GMP was 17-fold faster opposite FU than opposite U in the template. These results in vitro are consistent with the mutational bias observed in the mutant spectra of 5-FU-treated FMDV populations. The dual mutagenic and inhibitory activity of 5-fluorouridine triphosphate may contribute to the effective extinction of FMDV by 5-FU through virus entry into error catastrophe.
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PMID:Molecular characterization of a dual inhibitory and mutagenic activity of 5-fluorouridine triphosphate on viral RNA synthesis. Implications for lethal mutagenesis. 1866 97

This unit describes DNA-dependent, RNA-dependent, and template-independent RNA polymerases. DNA-dependent RNA polymerases include the related bacteriophage T7, T3, and SP6 polymerases, the most commonly used RNA polymerases for in vitro transcription reactions. Reaction conditions to produce preparative quantities of transcribed RNA and labeled RNA probes are covered, as are the major applications of these reactions. Limitations of the E. coli RNA polymerase for these applications are also presented. The properties of the phi6 RNA-dependent RNA polymerase (RdRp) and its use in RNAi experiments are also introduced. Poly(A) polymerase, a template-independent polymerase, catalyzes the incorporation of AMP residues onto the free 3'-hydroxyl terminus of RNA, utilizing ATP as a precursor. Specific reaction conditions of poly(A) polymerase, as well as applications including RNA tailing and 3' end labeling, are discussed.
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PMID:RNA polymerases. 1897 90

The distribution and density of pituitary adenylate cyclase-activating polypeptide (PACAP) binding sites have been investigated in the brain of the primates Jacchus callithrix (marmoset) and Macaca fascicularis (macaque) using [(125)I]-PACAP27 as a radioligand. PACAP binding sites were widely expressed in the brain of these two species with particularly high densities in the septum, hypothalamus and habenula. A moderate density of recognition sites was seen in all subdivisions of the cerebral cortex with a heterogenous distribution, the highest concentrations occurring in layers I and VI while the underlying white matter was almost devoid of binding sites. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed intense expression of the mRNAs encoding the short and hop-1 variants of pituitary adenylate cyclase-activating polypeptide-specific receptor (PAC1-R) in the cortex of both marmoset and macaque, whereas vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating polypeptide mutual receptor, subtype 1 (VPAC1-R) and vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating polypeptide mutual receptor, subtype 2 (VPAC2-R) mRNAs were expressed at a much lower level. In situ hybridization histochemistry showed intense expression of PAC1-R and weak expression of VPAC1-R mRNAs in layer IV of the cerebral cortex. Incubation of cortical tissue slices with PACAP induced a dose-dependent stimulation of cyclic AMP formation, indicating that PACAP binding sites correspond to functional receptors. Moreover, treatment of primate cortical slices with 100 nM PACAP significantly reduced the activity of caspase-3, a key enzyme of the apoptotic cascade. The present results indicate that PACAP should exert the same neuroprotective effect in the brain of primates as in rodents and suggest that PAC1-R agonists may have a therapeutic value to prevent neuronal cell death after stroke or in specific neurodegenerative diseases.
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PMID:Distribution and functional characterization of pituitary adenylate cyclase-activating polypeptide receptors in the brain of non-human primates. 1923 5


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