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)

Ribosomal DNA transcription is important to the regulation of cardiomyocyte ribosome content and, as a consequence, the rate of protein synthesis and accumulation during cardiac hypertrophy. We studied the regulation of ribosomal RNA synthesis and the levels of RNA polymerase I and the ribosomal DNA transcription factor, UBF, during norepinephrine-induced hypertrophy of contraction-arrested neonatal cardiomyocytes in culture. Nuclear run-on assays and Western blots demonstrated that, concomitant with hypertrophy, norepinephrine (1 microM) increased the rate of ribosomal DNA transcription, without causing an increase in the amount of RNA polymerase I. However, the elevated rate of rRNA synthesis was accompanied by an increased cellular content of UBF protein as determined by Western analysis. Northern blots demonstrated norepinephrine-induced increases in UBF mRNA in neonatal cardiomyocytes indicating that the response was regulated, at least in part, at the pretranslational stage. Both alpha- and beta-adrenergic agents increased the level of UBF mRNA. The beta-adrenergic response was mimicked by forskolin (1 microM) and the cyclic AMP analog dibutyryl cAMP (10 microM). However, activation of protein kinase C by phorbol 12-myristate 13-acetate (0.1 microM) did not increase expression of UBF. These results implicate UBF as a possible regulatory factor of the accelerated rDNA transcription observed during norepinephrine-mediated cardiomyocyte hypertrophy.
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PMID:Regulation of rDNA transcription factors during cardiomyocyte hypertrophy induced by adrenergic agents. 771 37

We have investigated the effect of phorbol 12-myristate 13-acetate (PMA) on platelet-derived growth factor (PDGF) B-chain gene transcription as well as on mRNA stability in cultured human mesangial cells. Addition of actinomycin to cells stimulated with PMA decreases steady state levels of PDGF-B chain mRNA analysed by solution hybridization assay. PDGF-B chain gene transcription was also assayed directly by measuring elongation of transcripts in isolated nuclei followed by hybridization of labeled RNA transcripts to a cDNA encoding for PDGF-B chain. Our data show that PMA induces PDGF-B chain gene transcription by approximately 2-fold. alpha-Amanitin, an RNA polymerase II inhibitor, blocked transcription by more than 70%. In addition, we determined the effect of PMA on the halflife of PDGF-B chain mRNA directly by pulse chase method. In human mesangial cells, the PDGF-B chain mRNA exhibited halflife of approximately 105 min. In the presence of PMA, the halflife of PDGF-B chain mRNA was reduced to approximately 72 min. These studies indicate that regulation of PDGF-B chain gene by PMA in human mesangial cells involves a coordinate effort at the level of transcription and mRNA stability.
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PMID:Platelet-derived growth factor B-chain gene expression in mesangial cells: effect of phorbol ester on gene transcription and mRNA stability. 787 95

High affinity sodium- and potassium-coupled L-glutamate transport into presynaptic nerve terminals and fine glial processes removes the neurotransmitter from the synaptic cleft, thereby terminating glutamergic transmission. This report describes that the purified L-glutamate transporter from pig brain is phosphorylated by protein kinase C, predominantly at serine residues. Upon exposure of C6 cells, a cell line of glial origin, to 12-O-tetradecanoylphorbol-13-acetate, about a 2-fold stimulation of L-glutamate transport is observed within 30 min. Concomitantly, the level of phosphorylation increases with similar kinetics. The phorbol ester also stimulates L-glutamate transport in HeLa cells infected with a recombinant vaccinia virus expressing T7 RNA polymerase and transfected with pT7-GLT-1. The latter is a recently cloned rat brain glutamate transporter of glial origin. Mutation of serine 113 to asparagine does not affect the levels of expressed transport but abolishes its stimulation by the phorbol ester. To our knowledge, this is the first direct demonstration of the regulation of a neurotransmitter transporter by phosphorylation.
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PMID:Phosphorylation and modulation of brain glutamate transporters by protein kinase C. 790 7

Bovine vascular smooth muscle cells (SMC) express the urokinase-type plasminogen activator receptor (u-PAR) claimed to be important in cell invasion. Receptor numbers and affinity are regulated by thrombin and several other mitogens involved in SMC proliferation. We investigated the effects of these mitogens on u-PAR mRNA levels. On continuous thrombin stimulation the u-PAR message in SMC was 10 +/- 2.3-fold elevated reaching a maximum between 6 and 9 hours and declining to control values within 48 hours. Thrombin present for 30 minutes on the cell surface produced similar effects. Stimulation with the thrombin receptor activation peptide S-F-L-L-R-N representing the NH2-terminus of the tethered ligand also increased u-PAR mRNA levels with an identical time course. D-Phe-Pro-Arg-chloromethyl ketone (PPACK) active site blocked thrombin and the catalytically inactive thrombin mutant S205A did not affect u-PAR mRNA levels. Thrombin stimulation also resulted in a 2 +/- 0.2-fold transient increase in thrombin receptor mRNA preceding the rise in u-PAR message. Transforming growth factor beta 1 (TGF beta 1) and platelet-derived growth factor (PDGF) showed similar time courses for the elevation of u-PAR mRNA levels with a maximal 5.5 +/- 0.9 and 12 +/- 2.5-fold increase, respectively. Basic fibroblast growth factor (bFGF) and phorbol myristate acetate (PMA) showed a more prolonged effect increasing u-PAR mRNA levels 8 +/- 2.0-fold and 12.3 +/- 2.5-fold, respectively, within 6 hours but remaining 5 to 10-fold elevated at 48 hours. In order to decide if the u-PAR mRNA increase was due to message stabilization or a consequence of transcriptional activation we used the RNA polymerase II inhibitor 5,6-dichloro-1-beta-D-ribofuranosyl benzimidazole (DRB) during the stimulation experiments. u-PAR mRNA levels on TGF beta 1 stimulation of SMC decayed after the addition of DRB indicating that enhancement of transcriptional activity was involved in the induction. In contrast, the time course of u-PAR mRNA elevation on thrombin, bFGF, and PMA stimulation was not significantly altered in the presence of DRB suggesting that in these latter cases u-PAR mRNA message accumulation was at least in part due to mRNA stabilization. Increased transcriptional activity, mRNA stabilization and expression of u-PAR protein on the SMC surface in response to growth factors may facilitate enhanced cell surface protease activity, cell migration, and development of atheromatous lesions.
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PMID:Effect of thrombin, the thrombin receptor activation peptide, and other mitogens on vascular smooth muscle cell urokinase receptor mRNA levels. 794 25

Nonparenchymal cells isolated from Fischer rat liver were separated into subpopulations by passage through a nylon wool column and/or culturing in a plastic plate. Besides typical Kupffer cells, we detected a unique population of cells (called PKu cells) which were plastic adherent but did not spread on a short term culture, were nonadherent on nylon wool, and were nonphagocytic, as opposed to Kupffer cells. Both Kupffer cells and PKu cells expressed CD4 (recognized with W3/25 mAb), CD8 (OX-8), a NK cell antigen (3.2.3), and a monocyte antigen (OX-41), as assessed by flow cytofluorometry. However, the proportion of cells bearing high densities of CD8 and 3.2.3 antigens was much larger for PKu cells than for Kupffer cells. Reverse transcriptase-PCR analysis of CD8 mRNA revealed that PKu cells expressed the CD8 alpha chain but not the beta chain. When PKu cells were treated with phorbol 12-myristate 13-acetate (PMA), they exhibited spreading and phagocytic activities, and showed a similar morphology to Kupffer cells in the spread form. Moreover, PMA treatment decreased the high density of CD8 antigen on PKu cells. These findings indicated that PKu cells present in normal rat liver are precursors of Kupffer cells.
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PMID:Pre-Kupffer like CD4/CD8 double positive mononuclear cells present in rat liver. 796 6

The Escherichia coli aidB gene is regulated by two different mechanisms, an ada-dependent pathway triggered by methyl damage to DNA and an ada-independent pathway triggered when cells are grown without aeration. In this report we describe our search for mutations affecting the ada-independent aidB induction pathway. The mutant strain identified carries two mutations affecting aidB expression. These mutations are named abrB (aidB regulator) and abrD. The abrB mutation is presently poorly characterized because of instability of the phenotype it imparts. The second mutation, abrD1, reduces the expression of aidB observed when aeration is ceased and oxygen becomes limiting. Genetic and phenotypic analysis of the abrD1 mutation demonstrates that it is an allele of rpoS. Thus, aidB is a member of the family of genes that are transcribed by a sigma S-directed RNA polymerase holoenzyme. Examination of aidB expression in an rpoS insertion mutant strain indicates that both rpoS13::Tn10 and abrD1 mutations reduce aidB expression under oxygen-limiting conditions that prevail in unaerated cultures, reduce aidB induction by acetate at a low pH, but have little or no effect on the ada-dependent alkylation induction of aidB.
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PMID:Induction of the Escherichia coli aidB gene under oxygen-limiting conditions requires a functional rpoS (katF) gene. 800 88

We have previously found that the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) induces specific transcription of tRNA and 5S RNA genes in Drosophila Schneider S-2 cells (M. Garber, S. Panchanathan, R. F. Fan, and D. L. Johnson, J. Biol. Chem. 266:20598-20601, 1991). Having derived cellular extracts from TPA-treated cells, that are capable of reproducing this stimulation in vitro, we have examined the mechanism for this regulatory event. Using conditions that limit reinitiation and produce single rounds of transcription from active gene complexes, we find that the number of functional transcription complexes is increased in extracts prepared from TPA-induced cells. We have analyzed the activities of the transcription factors TFIIIB and TFIIIC derived from extracts prepared from TPA-induced and noninduced cells. Examination of the relative activities of TFIIIC showed that both its ability to reconstitute transcription with TFIIIB and RNA polymerase III and its ability to stably bind to the DNA template are unchanged. However, the activity of TFIIIB derived from the TPA-induced cells is substantially increased compared with that derived from the noninduced cells. The differences in TFIIIB activity account for the differences in the overall transcriptional activities observed in the unfractionated extracts. Western blot analysis of the TATA-binding protein subunit of TFIIIB revealed that there is an increase in the amount of this polypeptide present in the induced cell extracts and TFIIIB fraction. Together, these results indicate that the TPA response in Drosophila cells stimulates specific transcription of RNA polymerase III genes by increasing the activity of the limiting transcription component, TFIIIB, and thereby increasing the number of functional transcription complexes.
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PMID:Induction of Drosophila RNA polymerase III gene expression by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) is mediated by transcription factor IIIB. 826 1

Mononucleosomes were labeled with the sulfhydryl-specific fluorescence probe 1,5-IAEDANS (5-(2-((iodoacetyl)amino)ethyl)amino-naphthalene-1-sulfonic acid) by attaching the dye to the single cysteine of H3 through a covalent linkage. The enzyme RNA polymerase II (pol II) utilized the native and the reconstituted fluorescent nucleosomes as templates with greatest efficiency when 0.2 M potassium acetate (AcOK) was used as the supporting salt; 0.2 M NaCl was found to be very much inhibitory. Measurement of polarity of the microenvironment of the dye at its binding site in the nucleosome showed the conformation to be more open in the presence of AcOK, compared to that in 0.1 or 0.2 M NaCl. The binding of pol II to the nucleosome resulted in a relatively more compact structure when measured in terms of the polarity of the microenvironment of the dye in various salt-dependent conformations of the nucleosomes. Time-resolved fluorescence spectroscopy showed that the probe molecule at its binding site undergoes certain excited-state processes, and the presence/absence or rate of these excited-state processes depends on the conformation of nucleosomes, which in turn depends on the type and concentration of the ion present in the medium. Time-resolved emission spectra showed that binding of nucleosomes by pol II established some new contacts that resulted in inaccessibility of the dye to the bulk solvent, reflecting a more hydrophobic environment for the dye in the steady-state spectra. Thus, binding or transcription of nucleosomes by pol II did not break open their structure. Rather, some transient internal adjustments within the histone octamer may take place to accommodate the bulky pol II molecule.
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PMID:Dynamics of interaction of RNA polymerase II with nucleosomes. I. Effect of salts. 829 67

The DNA binding affinities of several gene-regulatory proteins, restriction endonucleases and the Escherichia coli RNA polymerase have previously been found to be dependent on the nature of the dominant buffer anion. To discover whether the E. coli cAMP receptor protein (CAP) exhibits a similar dependency, we measured its affinity for its primary lactose promoter binding site (lac site 1) in buffers in which the principal anion was chloride, phosphate, sulfate, acetate, or glutamate. We found that the affinity of CAP for lac site 1 is affected only slightly by changes in the dominant buffer anion. The binding of cAMP is similarly insensitive to buffer anion type, indicating that specific protein-anion interactions, if they occur, must be similar for the free and cAMP-bound forms of the protein. The effect of anion substitution on the ability of acrylamide to quench the intrinsic fluorescence of tryptophanyl residues of CAP is also small, suggesting that changes in buffer anion composition have minimal effect on the conformation of tryptophan-proximal regions of CAP. This conclusion is extended by the finding that anion substitution has a relatively small effect on the urea-concentration dependence of CAP denaturation. Taken together, these results support the notion that neither CAP nor CAP.cAMP nor the CAP.cAMP complex with lac promoter DNA interact selectively with anions present in the surrounding buffer. A possible role for this anion-insensitivity in the in vivo function of CAP is suggested.
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PMID:Effects of anions on the binding of the cAMP receptor protein to the lactose promoter. 838 49

The synthesis of ribosomes is an essential cellular process which requires the transcription of the rRNA genes by RNA polymerase I (Pol I). The regulation of rRNA synthesis is known to be coupled to growth regulation. In nongrowing, slowly growing, and rapidly growing Drosophila cells, exposure to the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) increases the synthesis of precursor and mature rRNAs. Using nuclear run-on assays, we show that TPA enhances transcription of the rRNA genes. These results suggest that TPA regulates expression of RNA genes transcribed by Pol I, irrespective of the growth state of the cells. In slowly dividing Drosophila cells, increasing the serum concentration rapidly alters the accumulation of rRNA by enhancing rDNA transcription within 1 h. Thus, TPA and serum are each able to rapidly regulate rRNA gene expression in Drosophila cells. These results indicate that the RNA Pol I transcription system can be regulated by agents which have previously been shown to effect specific genes transcribed by the RNA Pol II system.
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PMID:In vivo regulation of rRNA transcription occurs rapidly in nondividing and dividing Drosophila cells in response to a phorbol ester and serum. 842 12


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