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)

The mouse B2 element is a moderately repetitive nt sequence of 180 bp transcribed by RNA polymerase III (Pol III) at high levels in embryonic and transformed cells. The B2 sequence is present in either orientation within the noncoding regions of a number of genes transcribed by RNA polymerase II (Pol II). We sought to determine if the small B2 transcripts generated by Pol III are natural antisense RNA molecules which might hybridize to complementary sequences present within Pol II transcripts. Chimaeric reporter genes encoding Escherichia coli gpt were constructed containing a B2 repeat in either orientation within the 5'- or 3'-untranslated regions. These constructs were transfected into embryonal carcinoma (EC) cells and expression of the reporter gene was analysed in EC cells and retinoic acid-treated EC cells, which contain high and low levels of small B2 RNAs, respectively. Although the B2 sequences affected expression of the reporter gene, these effects did not appear to be due to hybridization of the small B2 RNA to the reporter transcripts. The presence of B2 sequences near a Pol II-transcribed gene can alter expression of that gene in a position- and orientation-dependent manner, suggesting these repetitive elements may be cis-acting regulators of gene expression.
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PMID:The rodent B2 sequence can affect expression when present in the transcribed region of a reporter gene. 201 66

B2 genes are short repeated sequences which are transcribed by RNA polymerase III. Abundant transcripts accumulate in embryonic and transformed cells, but transcripts are rare or absent from normal differentiated cell types. During retinoic acid-induced differentiation of P19 embryonal carcinoma cells, an early transient increase in B2 RNA levels is followed by a rapid drop in expression. The marked changes in B2 RNA levels are most likely due to transcriptional modulation since B2 RNA stabilities are unaffected by differentiation. At least four short-lived B2 RNAs with apparent lengths of 150, 180, 240, and 500 nucleotides were characterized. The two larger RNAs are polyadenylated and are more stable in cells. A cDNA of a B2 gene was isolated which was over 99% identical to the consensus sequence. This B2 cDNA can be transcribed in human cells and yields at least two distinct transcripts. We propose a model for B2 RNA metabolism which describes transcription, posttranscriptional modification and processing, and nucleocytoplasmic transport.
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PMID:Synthesis and processing of small B2 transcripts in mouse embryonal carcinoma cells. 237 Aug 62

B2 genes are rodent-specific middle repetitive elements transcribed by RNA polymerase III. They are expressed in the ectoderm and mesoderm but not in the embryonic or extraembryonic endoderm of early mouse embryos. This tissue specificity is mimicked in vitro by embryonal carcinoma and embryonic stem cell lines. Nuclear run-on experiments show that the down-regulation of B2 genes during F9 embryonal carcinoma cell differentiation into endoderm occurs at the transcriptional level and that other class III genes, including those encoding tRNA, show a similar response. We have used cell-free extracts to investigate the molecular mechanisms responsible. The specific down-regulation of transcription by RNA polymerase III during F9 cell differentiation is due to a reduction in the activity of the general class III transcription factor TFIIIB.
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PMID:Regulation of RNA polymerase III transcription in response to F9 embryonal carcinoma stem cell differentiation. 259 61

We observed that decline of thymidine kinase (TK) enzyme activity was severalfold faster than the decay of full length TK mRNA during growth arrest of 3T6 mouse fibroblasts or during differentiation of myoblasts (C2Cl12) or F9 embryonal carcinoma cells. In order to study the molecular mechanism of this disparate behavior, a polyclonal antiserum against mouse TK was raised in rabbit. High level expression of mouse TK polypeptide in Escherichia coli was achieved with a T7 RNA polymerase-directed expression system. Using the antiserum in immunoblotting, no indication for a pool of inactive enzyme was found during differentiation of F9 or growth arrest of 3T6 cells. Pulse labeling of these cells in vivo with [35S]methionine showed a more than 6-fold decrease in the rate of TK-protein synthesis of in F9 cells after 3 days of treatment with retinoic acid as well as in 3T6 cells after 16 h under low serum. This was not due to increased turnover of the protein as measured in pulse chase experiments. In addition, full length TK mRNA stayed associated with polysomes under these conditions in F9 as well as 3T6 cells. Taken together the results suggest that endogenous TK mRNA becomes translationally repressed under a variety of conditions when mouse cells cease to grow.
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PMID:Translational repression of endogenous thymidine kinase mRNA in differentiating and arresting mouse cells. 768 82

Three alternative splicing products of amyloid precursor protein (APP), APP770, 751 and 695, were detected in mouse embryonal carcinoma (EC) P19 cells by reverse transcriptase RNA polymerase chain reaction (RT-PCR). Alternative splicing of APP pre-mRNA in P19EC cells was remarkably changed by c-jun transformation. The relative ratio of APP770 encoding exons 7 and 8, non-neuron type, was increased by c-jun transformation, while that of APP 695 not encoding exons 7 and 8, neuron-specific one, was decreased. These results suggested that skipping of exons 7 and 8 was specifically blocked in c-jun transformed cells. APP 695, which increases in P19 EC cells under the culture conditions that induce the neuronal differentiation, did not increase in C2C5 cells under the same conditions, suggesting that c-jun transformed cells were not in the neuronal cell lineage and lost the ability to differentiate into neurons.
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PMID:c-jun inhibited the alternative splicing of neuron-specific amyloid precursor protein, but stimulated the non-neuron type one in P19 EC cells. 783 92

The cDNA sequence of Stra7, a retinoic acid (RA)-inducible gene in P19 embryonal carcinoma (EC) cells, was determined. The deduced Stra7 protein contains a homeodomain highly similar to that of the previously described chicken CHox7 gene product, and is highly conserved during evolution, from hemichordates to vertebrates. The mouse Stra7 cDNA corresponds to the full-length form of the 77 bp homeodomain-encoding cDNA fragment which was previously cloned and termed MMoxA or Gbx-2. Reverse-transcriptase-PCR analysis revealed the presence of Stra7/Gbx-2 transcripts in the adult brain, spleen, and female genital tract, whereas no expression could be observed in heart, liver, lung, kidney, or testes. In situ hybridization analysis showed a restricted expression pattern of Stra7/Gbx-2 in the three primitive germ layers during gastrulation. Restricted expression was also detected in the pharyngeal arches. Subsequently, there were specific expression domains in the developing central nervous system, at the midbrain/hindbrain boundary and later in the cerebellum anlage, in certain rhombomeres, in dorsal regions of the spinal cord, and in the developing dorsal thalamus and corpus striatum.
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PMID:Sequence and expression pattern of the Stra7 (Gbx-2) homeobox-containing gene induced by retinoic acid in P19 embryonal carcinoma cells. 860 Oct 31

Retinoids play a fundamental role in regulating normal cell proliferation and differentiation. The most spectacular effects of retinoids in vitro can be observed with embryonal carcinoma (EC) cells that can be induced to differentiate into endodermal, mesodermal and neuroectodermal lineages. An early and essential step in the differentiation process is the activation of the retinoic acid receptor-beta 2 (RAR beta 2) promoter that requires a co-operation between RAR, the EC-cell specific adenovirus early gene product 1A (E1A)-like activity and the TATA-binding protein (TBP). In differentiated cells, this signalling pathway can be mimicked by ectopic expression of the adenoviral E1A protein. Here we show that E1A13S but not E1A12S augments the level of transcription. Analysis of the binding kinetics of E1A13S to TBP by the surface plasmon resonance (SPR) technique reveals that the affinity of TBP for a consensus TATA-box sequence is significantly and specifically increased by E1A13S only. Intriguingly, a specific interaction can only be obtained with crude TBP overexpressed in HeLa cells via vaccinia virus as opposed to bacterially expressed TBP, suggesting a cofactor requirement for the interaction. Co-immunoprecipitation experiments show that E1A13S is an integral component of the RNA polymerase II-specific TBP-containing complex in adenovirus transformed embryonal kidney 293 cells. Taken together the results suggest that E1A13S mediates transcriptional activation by providing a physical bridge between TBP/transcription factor IID (TFIID) and retinoic acid receptor.
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PMID:Retinoid-dependent transcription: the RAR/RXR-TBP-EIA/EIA-LA connection. 897 43

RNA polymerase III transcription is down-regulated when F9 embryonal carcinoma cells differentiate into parietal endoderm. This reflects a decrease in the activity of TFIIIB, a multisubunit complex that is required for all class III gene expression. Two essential components of TFIIIB are the TATA-binding protein (TBP) and an associated polypeptide called BRF that is specific to this complex. The abundance of both TBP and BRF decreases during F9 cell differentiation. Whereas the amount of TBP assembled into TFIIIB is down-regulated, this is not the case for all TBP-containing complexes. BRF levels show a more dramatic decline that appears sufficient to account for the overall change in transcriptional activity. Developmental regulation of a specific class of genes may therefore be achieved through changes in the availability of a TBP-associated factor.
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PMID:Regulation of a TATA-binding protein-associated factor during cellular differentiation. 964 84

Dramatic changes in the patterns of transcription are a common feature of early development. We have used F9 embryonal carcinoma cells as a model system to study gene regulation during an early stage of murine embryogenesis. We find that transcription by RNA polymerase I decreases when F9 cells differentiate into parietal endoderm. The reduced rate of transcription is associated with a down-regulation of several components of the class I transcription apparatus. The most substantial change involves the essential factor SL1, which is a multisubunit complex that contains the TATA-binding protein and three TATA-binding protein-associated factors (TAFs). The abundance of two of these TAFs, TAFI48 and TAFI95, decreases during F9 cell differentiation. Developmental regulation of a specific class of genes may therefore be achieved through changes in the availability of TAFs.
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PMID:Regulation of RNA polymerase I transcription in response to F9 embryonal carcinoma stem cell differentiation. 993 34

Ligand-dependent transcriptional regulation by nuclear receptors is believed to be mediated by intermediary factors (TIFs) acting on remodelling of the chromatin structure and/or the activity of the transcriptional machinery. The putative transcriptional mediator TIF1alpha is a nuclear protein kinase that has been identified via its interaction with liganded nuclear receptors, including retinoic acid (RAR), retinoid X (RXR) and estrogen (ER) receptors. Here, we demonstrate that TIF1alpha is a non-histone chromosomal protein tightly associated with highly accessible euchromatic regions of the genome. Immunofluorescence confocal microscopy reveals that TIF1alpha exhibits a finely granular distribution in euchromatin of interphase nuclei, while it is mostly excluded from condensed chromatin and metaphase chromosomes. Immunoelectron microscopy shows that, in contrast to the heterochromatin protein HP1alpha, most of TIF1alpha is associated with euchromatin, where it is preferentially localised on regions known to be sites for RNA polymerase II (perichromatin fibrils and borders between euchromatin and heterochromatin). Early mouse embryos as well as embryonal carcinoma (EC) and embryonic stem (ES) cells express high levels of TIF1alpha. These levels dramatically decrease during organogenesis and upon differentiation of P19 EC cells, indicating that TIF1alpha is preferentially expressed in undifferentiated pluripotent cells in the course of development. Therefore, TIF1alpha could belong to a novel class of chromatin-associated TIFs that facilitate the access of transregulators (e.g. liganded nuclear receptors) to their cognate sites in target genes, thereby participitating in the epigenetic control of transcription during embryonic development and cell differentiation.
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PMID:The putative nuclear receptor mediator TIF1alpha is tightly associated with euchromatin. 1031 60


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