Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thrombin is a serine protease involved in many physiological functions and its receptor. the protease-activated receptor-1 (PAR-1), has a wide tissue distribution. We hypothesized that PAR-1 is expressed in gastric epithelial cells and that thrombin can modulate defence mechanisms through PAR-1. The rat gastric epithelial cell line (RMG1) and gastric biopsy specimens from gastritis patients were used in the study. Reverse transcriptase polymerase chain reaction analysis showed that the thrombin receptors PAR-1, PAR3 and PAR-4 are expressed by RGM1 gastric epithelial cell line. Immunohistochemical and electron microspcopic studies also showed PAR-1 expression in human gastric epithelial cells. Thrombin stimulated the secretion of mucin and prostaglandin E2 (PGE2) formation in RGM1 cells in a dose-dependent manner. PAR-1 agonist also stimulated PGE2 formation. In addition, thrombin significantly increases the expression of the PGE2 receptors EP2-R and EP4-R in RGM1 cells. In conclusion, the results of the present study showed for the first time that gastric epithelial cells express thrombin receptors and that these receptors may play a protective role in the gastric mucosa.
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PMID:Expression and cytoprotective effect of protease-activated receptor-1 in gastric epithelial cells. 1273 39

Thrombin, its main inhibitor (protease nexin-1) and its related receptors (protease-activated receptors, PAR-1,-2, -3, -4) were studied in rat hippocampus following administration of trimethyltin (TMT), a neurotoxin inducing neuronal degeneration and reactive gliosis. Reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry revealed that while expression of prothrombin and protease nexin-1 did not change significantly in TMT-treated hippocampi, PARs (in particular PAR-1 and to a lesser extent PAR-2 and PAR-3) were upregulated in reactive astrocytes, suggesting their involvement in neurodegeneration and in the consequent response of the nervous tissue.
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PMID:Trimethyltin-induced differential expression of PAR subtypes in reactive astrocytes of the rat hippocampus. 1499 20

We have cloned genes encoding three enzymes of the de novo pyrimidine pathway using genomic DNA from Plasmodium falciparum and sequence information from the Malarial Genome Project. Genes encoding dihydroorotase (reaction 3), orotate phosphoribosyltransferase (reaction 5), and OMP decarboxylase (reaction 6) have been cloned into the plasmid pET 3a or 3d with a thrombin cleavable 9xHis tag at the C-terminus and the enzymes were expressed in Escherichia coli. To overcome the toxicity of malarial OMP decarboxylase when expressed in E. coli, and the unusual codon usage of the malarial gene, a hybrid plasmid, pMICO, was constructed which expresses low levels of T7 lysozyme to inhibit T7 RNA polymerase used for recombinant expression, and extra copies of rare tRNAs. Catalytically-active OMP decarboxylase has been purified in tens of milligrams by chromatography on Ni-NTA. The gene encoding orotate phosphoribosyltransferase includes an extension of 66 amino acids from the N-terminus when compared with sequences for this enzyme from other organisms. We have found that other pyrimidine enzymes also contain unusual protein inserts. Milligram quantities of pure recombinant malarial enzymes from the pyrimidine pathway will provide targets for development of novel antimalarial drugs.
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PMID:Cloning and expression of malarial pyrimidine enzymes. 1557 Dec 77

The synthesis of the triphosphates of 4'-thiouridine and 4'-thiocytidine, 4'-thioUTP (7; thioUTP) and 4'-thioCTP (8; thioCTP), and their utility for SELEX (systematic evolution of ligands by exponential enrichment) is described. The new nucleoside triphosphate (NTP) analogs 7 and 8 were prepared from appropriately protected 4'-thiouridine and -cytidine derivatives using the one-pot method reported by J. Ludwig and F. Eckstein [(1989) J. Org. Chem., 54, 631-635]. Because SELEX requires both in vitro transcription and reverse transcription, we examined the ability of 7 and 8 for SELEX by focusing on the two steps. Incorporation of 7 and 8 by T7 RNA polymerase to give 4'-thioRNA (thioRNA) proceeded well and was superior to those of the two sets of frequently used modified NTP analogs for SELEX (2'-NH2dUTP and 2'-NH2dCTP; 2'-FdUTP and 2'-FdCTP), when an adequate leader sequence of DNA template was selected. We revealed that a leader sequence of about +15 of DNA template is important for the effective incorporation of modified NTP analogs by T7 RNA polymerase. In addition, reverse transcription of the resulting thioRNA into the complementary DNA in the presence of 2'-deoxynucleoside triphosphates (dNTPs) also proceeded smoothly and precisely. The stability of the thioRNA toward RNase A was 50 times greater than that of the corresponding natural RNA. With these successful results in hand, we attempted the selection of thioRNA aptamers to human alpha-thrombin using thioUTP and thioCTP, and found a thioRNA aptamer with high binding affinity (K(d) = 4.7 nM).
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PMID:New NTP analogs: the synthesis of 4'-thioUTP and 4'-thioCTP and their utility for SELEX. 1591 69

We synthesized 4'-thioUTP (1) and 4'-thioCTP (2) with the aim of developing new NTP analogs for in vitro selection. Since in vitro selection requires both in vitro transcription and reverse transcription, we examined the ability of 1 and 2 for in vitro selection by focusing on both steps. Incorporation of 1 and 2 by T7 RNA polymerase to give 4'-thioRNA proceeded well and was superior to those of the two sets of frequently used modified NTP analogs (2'-NH2dUTP and 2'-NH2dCTP, and 2'-FdUTP and 2'-FdCTP) for in vitro selection. In addition, reverse transcription of the resulting 4'-thioRNA into the complementary DNA in the presence of dNTPs also proceeded smoothly and precisely. With these successful results in hand, in vitro selection of human a-thrombin RNA aptamer using 1 and 2 is in progress.
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PMID:In vitro selection of human alpha-thrombin RNA aptamer using 4'-thioUTP and 4'-thioCTP. 1715 May 59

We describe herein a method for isolating fully-modified 4'-thioRNA aptamers against human alpha-thrombin using the SELEX protocol. In order to isolate the desired aptamers, in vitro transcription was examined in the presence of four kinds of 4'-thioribonucleoside triphosphates (4'-thioNTPs) in an effort to afford the fully-modified 4'-thioRNA. The transcription efficiency of the 4'-thioNTPs was first compared with that of the nucleoside 5'-(alpha-thio)triphosphates (alphaSNTPs) and found to be less effective than that of the alphaSNTPs, especially when GTP and/or ATP were substituted for 4'-thioGTP and/or 4'-thioATP. Further attempts to improve its efficiency, including the use of a mutant RNA polymerase instead of the wild type, various additives, and 4'-thioNTP concentrations were unsuccessful. Accordingly, the transcription was performed in the presence of 4'-thioNTPs together with the natural GTP and ATP at the appropriate concentrations. Although this attempt furnished a highly-modified 4'-thioRNA, but not a fully-modified 4'-thioRNA, we eventually succeeded in isolating the fully-modified 4'-thioRNA aptamers by SELEX using optimized transcription conditions, followed by post-modification of the resulting aptamers.
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PMID:Investigations toward the selection of fully-modified 4'-thioRNA aptamers: optimization of in vitro transcription steps in the presence of 4'-thioNTPs. 1883 73

Researches on genes expressed in a cercarial stage-specific manner may help us understand the molecular events and functions during schistosome invasion of skin. A genomic clone encoding 8-kDa calcium-binding protein (SjCa8) specifically expressed in cercariae and skin-stage schistosomulum (transformed within 3 h) was obtained from cercariae. Recombinant protein was expressed in vector pET32a (+) and purified using a Ni-NTA purification system. The target protein SjCa8 was determined by matrix-assisted laser desorption/ionization time-of-flight (TOF)/TOF mass spectrometer after thrombin digestion and dialysis. Reverse transcriptase polymerase chain reaction and Western blot revealed SjCa8 can be detected in cercaria and skin-stage schistosomulum but not lung-stage schistosomulum, adult, or egg and was localized to head gland, penetration gland tubes, and penetration glands where Ca(2+) was abundant, and the cercarial tegument (but not tegument of tail) and body-tail junction. Furthermore, SjCa8 was interestingly detected in cercarial secretions. The characterization of SjCa8 indicated that it may undergo structural and physiological modifications, including repair of the surface membrane, changes in permeability that account for the loss of water tolerance, activities of calcium-depending enzymes, and immune signaling, etc. Furthermore, vaccination with rSjCa8 plus adjuvant induced protective effect with 50.39% worm reduction rate and significantly high hepatic and intestine egg reduction rates (54.16%, 50.63%, respectively), which is possibly mediated through an apparent induction of Th1-type immune response for strikingly high level of IgG2a and IgG2b developed in immunized C57BL/6 mice.
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PMID:Expression profile, localization of an 8-kDa calcium-binding protein from Schistosoma japonicum (SjCa8), and vaccine potential of recombinant SjCa8 (rSjCa8) against infections in mice. 1901 78

Protease Nexin-1, a 43-kDa glycoprotein, is a major physiological thrombin inhibitor involved in the modulation of nerve cell plasticity. Recombinant rat Protease Nexin-1 (rPN-1) was efficiently produced in Escherichia coli using a T7 RNA polymerase based expression system and purified by heparin-sepharose affinity chromatography yielding 3 mg of protein per liter of cell culture. The purity and chemical identity of rPN-1 were assessed by SDS-PAGE, Reverse Phase- High Performance Liquid Chromatography, mass spectrometry and two-dimensional-gel electrophoresis. Conformational analysis by circular dichroism and fluorescence spectroscopy revealed the presence of mixed alpha/beta secondary structure and the prevailing localization of Trp-residues in rather polar environments. Fluorescence titration of rPN-1 with heparin indicated that rPN-1 binds heparin with high affinity. Furthermore, the formation of a SDS-stable 1:1 thrombin-rPN-1 complex, monitored by SDS-PAGE, confirmed the native-like structure of rPN-1. Finally, the cellular effects of rPN-1, such as its ability to promote neurite outgrowth in neuroblastoma cells, were found to be very similar to those elicited by natural PN-1. Altogether, our results demonstrate that glycosylation does not alter neither structure nor function of PN-1 and that E. coli is a suitable expression system for obtaining milligram quantities of pure and fully active rPN-1 for structural and functional studies.
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PMID:Conformational and biochemical characterization of a biologically active rat recombinant Protease Nexin-1 expressed in E. coli. 1916 25

Schistosoma japonicum is the pathogen responsible for schistosomiasis japonica, one of the major infectious diseases targeted for prevention nationally in China. Expression of heat shock proteins (HSPs) following stress plays a very important biological role in many organisms including S. japonicum. Among the HSP family, the 70-kDa HSPs are most responsible for intracellular chaperone and extracellular immunoregulatory functions. Based on the published sequences in GenBank/EMBL (AF044412.1), open reading frame belonging to HSP70 protein corresponds to a full-length cDNA containing an open reading frame of 1,947 bp encoded of 648 amino acids was identified as HSP70 from schistosome. In this study, the coding region that we named rSj648/hsp70 was amplified from S. japonicum adult worm cDNA library, and the recombinant protein was expressed in vector pET32a(+) and purified using a Ni-NTA purification system. The target protein rSj648/hsp70 was determined by matrix-assisted laser desorption/ionization mass spectrometer after thrombin digestion and dialysis. Reverse transcriptase polymerase chain reaction and Western blotting analysis confirmed that Sj648/hsp70 could be expressed in the eggs, normal cercariae, ultraviolet-attenuated cercariae (UVAC), and adult worms of S. japonicum. Real-time quantitative PCR analysis indicated that Sj648/hsp70 was expressed significantly higher in eggs than that in cercariae and adult worms, and the expression in UVAC was higher than that in normal cercariae. A thermotolerance assay showed that rSj648/hsp70 could protect Escherichia coli cells from heat damage. The detection of specific antibody levels by indirect enzyme-linked immunosorbent assay demonstrated that mice immunized with rSj648/hsp70 induced higher level of specific anti-rSj648/hsp70 IgG1 compared with those vaccinated with adjuvant alone, indicating that rSj648/hsp70 was able to elicit Th2-type bias immune response. Our results suggest that Sj648/hsp70 might be an important molecule in parasite-host interaction and display potential roles in mice immunoregulation system.
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PMID:Molecular cloning and characterization of a HSP70 gene from Schistosoma japonicum. 2207 51

Microarrays of RNA aptamers are fabricated in a one-step, multiplexed enzymatic synthesis on gold thin films in a microfluidic format and then employed in the detection of protein biomarkers with surface plasmon resonance imaging (SPRI) measurements. Single-stranded RNA (ssRNA) oligonucleotides are transcribed on-chip from double-stranded DNA (dsDNA) templates attached to microarray elements (denoted as generator elements) by the surface transcription reaction of T7 RNA polymerase. As they are synthesized, the ssRNA oligonucleotides diffuse in the microfluidic channel and are quickly captured by hybridization adsorption onto adjacent single-stranded DNA (ssDNA) microarray elements (denoted as detector elements) that contain a sequence complementary to 5'-end of the ssRNA. The RNA aptamers attached to these detector elements are subsequently used in SPRI measurements for the bioaffinity detection of protein biomarkers. The microfluidic generator-detector element format permits the simultaneous fabrication of multiple ssRNA oligonucleotides with different capture sequences that can hybridize simultaneously to distinct detector elements and thus create a multiplexed aptamer microarray. In an initial set of demonstration experiments, SPRI measurements are used to monitor the bioaffinity adsorption of human thrombin (hTh) and vascular endothelial growth factor (VEGF) proteins onto RNA aptamer microarrays fabricated in situ with this on-chip RNA polymerase synthesis methodology. Additional SPRI measurements of the hydrolysis and desorption of the surface-bound ssRNA aptamers with a surface RNase H are used to verify the capture of ssRNA with RNA-DNA surface hybridization onto the detector elements. The on-chip RNA synthesis described here is an elegant, one-step multiplexed methodology for the rapid and contamination-free fabrication of RNA aptamer microarrays for protein biosensing with SPRI.
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PMID:On-chip synthesis of RNA aptamer microarrays for multiplexed protein biosensing with SPR imaging measurements. 2245 58


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