Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The multiprotein human TRAP/Mediator complex, which is phylogenetically related to the yeast SRB/Mediator coactivator, facilitates activation through a wide variety of transcriptional activators. However, it remains unclear how TRAP/Mediator functions in the context of other coactivators. Here we have identified a previously uncharacterized integral subunit (TRAP25) of the complex that is apparently metazoan specific. An antibody that is specific for TRAP25 allowed quantitative immunodepletion of essentially all TRAP/Mediator components from HeLa nuclear extract, without detectably affecting levels of RNA polymerase II and corresponding general transcription factors. Surprisingly, the TRAP/Mediator-depleted nuclear extract displayed severely reduced levels of both basal and activator-dependent transcription from DNA templates. Both activities were efficiently restored upon readdition of purified TRAP/Mediator. Moreover, restoration of basal and activator-dependent transcription to extracts that were simultaneously depleted of TRAP/Mediator and TFIID (TBP plus the major TAF(II)s) required addition of both TBP and associated TAF(II)s, as well as TRAP/Mediator. These observations indicate that TAF(II)s and Mediator are jointly required for both basal and activated transcription in the context of a more physiological complement of nuclear proteins. We propose a close mechanistic linkage between these components that most likely operates at the level of combined effects on the general transcription machinery and, in addition, a direct role for Mediator in relaying activation signals to this machinery.
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PMID:Requirement of TRAP/mediator for both activator-independent and activator-dependent transcription in conjunction with TFIID-associated TAF(II)s. 1190 76

Mediator of RNA polymerase II transcription subunits (MEDs) serve to promote the assembly, activation, and regeneration of transcription complexes on core promoters during the initiation and re-initiation phases of transcription. There are no studies on the Mediator complex during development of endothelial progenitors (EPCs). Here, we have analysed all known MEDs during the differentiation of EPCs, by expression profile studies at RNA level and, for a limited subset of MED subunits, also at protein level. Since beneficial effects of L-arginine on EPCs have been described, we have also examined its effect on the expression of Mediator subunit coding genes. Through RT-PCR we have found increased expression for MED12 and decreased levels for MED30 after l-arginine treatment; Western blot analysis do not agree entirely with the RNA data in the identification of a putative protein product. Furthermore, we have analysed the three-dimensional nuclear positions of MED12 and MED30 genes in the presence of l-arginine treatment. Our major finding is the identification of a novel transcript of MED30, termed MED30 short (MED30s) generating by alternative splicing. Our results showed that the mRNA of this novel isoform is present only in circulating cells, but it is not expressed in cultured adherent cells. These findings are broadly relevant and will contribute to our understanding of the role of Mediator in eukaryotic gene expression. Despite the need to confirm the in vivo presence of the protein of this novel isoform, the presence of this novel RNA raises the possibility of regulating pathophysiological mechanism in progenitors.
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PMID:Mediator subunits: gene expression pattern, a novel transcript identification and nuclear localization in human endothelial progenitor cells. 2049 79

Mediator (MED) is a fundamental component of the RNA polymerase II-mediated transcription machinery playing a pivotal role in the regulation of eukaryotic mRNA synthesis. Human MED complexes contain at least 30 distinct MED subunits. Our previous study, aimed to analyse MED complex during the pattern of endothelial progenitor cells (EPCs) differentiation, found an alternative transcript of MED30 subunit expressed only in circulating immature progenitor cells. Here, we report two novel transcripts of MED12 and MED19 subunits both generated by alternative splicing and displaying similar expression patterns, thereby indicating their involvement during endothelial cell differentiation.
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PMID:Distinct alternative splicing patterns of mediator subunit genes during endothelial progenitor cell differentiation. 2253 26

HIV-1 exploits multiple host proteins during infection. siRNA-based screenings have identified new proteins implicated in different pathways of the viral cycle that participate in a broad range of cellular functions. The human Mediator complex (MED) is composed of 28 elements and represents a fundamental component of the transcription machinery, interacting with the RNA polymerase II enzyme and regulating its ability to express genes. Here, we provide an evaluation of the MED activity on HIV replication. Knockdown of 9 out of 28 human MED proteins significantly impaired viral replication without affecting cell viability, including MED6, MED7, MED11, MED14, MED21, MED26, MED27, MED28, and MED30. Impairment of viral replication by MED subunits was at a post-integration step. Inhibition of early HIV transcripts was observed by siRNA-mediated knockdown of MED6, MED7, MED11, MED14, and MED28, specifically affecting the transcription of the nascent viral mRNA transactivation-responsive element. In addition, MED14 and MED30 were shown to have special relevance during the formation of unspliced viral transcripts (p < 0.0005). Knockdown of the selected MED factors compromised HIV transcription induced by Tat, with the strongest inhibitory effect shown by siMED6 and siMED14 cells. Co-immunoprecipitation experiments suggested physical interaction between MED14 and HIV-1 Tat protein. A better understanding of the mechanisms and factors controlling HIV-1 transcription is key to addressing the development of new strategies required to inhibit HIV replication or reactivate HIV-1 from the latent reservoirs.
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PMID:Characterization of the influence of mediator complex in HIV-1 transcription. 2510 Jul 19

MED30 is an essential member of the mediator complex that forms a hub between transcriptional activators and RNA polymerase II. However, the expressions and roles of MED30 have been poorly characterized in cancer. In this study, we examined the functional roles of MED30 during gastric cancer progression. It was found that MED30 was overexpressed in gastric cancer tissues and cell lines. Moreover, MED30 overexpression increased the proliferation, migration, and invasion of gastric cancer cells, whereas MED30 knockdown inhibited these effects. Furthermore the knockdown significantly inhibited tumorigenicity in SCID mice. MED30 also promoted the expressions of genes related to epithelial-mesenchymal transition and induced a fibroblast-like morphology. This study shows MED30 has pathophysiological roles in the proliferation, migration, and invasion of gastric cancer cells and suggests that MED30 should be viewed as a potent therapeutic target for malignant gastric carcinoma.
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PMID:MED30 Regulates the Proliferation and Motility of Gastric Cancer Cells. 2611 Aug 85

Transcription factors exert their regulatory potential on RNA polymerase II machinery through a multiprotein complex called Mediator complex or Mediator. The Mediator complex integrates regulatory signals from cell regulatory cascades with the regulation by transcription factors. The Mediator complex consists of 25 subunits in Saccharomyces cerevisiae and 30 or more subunits in multicellular eukaryotes. Mediator subunit 28 (MED28), along with MED30, MED23, MED25 and MED26, belong to presumably evolutionarily new subunits that seem to be absent in unicellular eukaryotes and are likely to have evolved together with multicellularity and cell differentiation. Previously, we have shown that an originally uncharacterized predicted gene, F28F8.5, is the true MED28 orthologue in Caenorhabditis elegans (mdt-28) and showed that it is involved in a spectrum of developmental processes. Here, we studied the proteomic interactome of MDT-28 edited as GFP::MDT-28 using Crispr/Cas9 technology or MDT-28::GFP expressed from extrachromosomal arrays in transgenic C. elegans exploiting the GFPTRAP system and mass spectrometry. The results show that MDT-28 associates with the Head module subunits MDT-6, MDT-8, MDT-11, MDT-17, MDT- 20, MDT-22, and MDT-30 and the Middle module subunit MDT-14. The analyses also identified additional proteins as preferential MDT-28 interactants, including chromatin-organizing proteins, structural proteins and enzymes. The results provide evidence for MDT-28 engagement in the Mediator Head module and support the possibility of physical (direct or indirect) interaction of MDT-28 with additional proteins, reflecting the transcription-regulating potential of primarily structural and enzymatic proteins at the level of the Mediator complex.
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PMID:Proteomic Interactome of C. elegans Mediator Complex Subunit 28 (MDT-28) Reveals Predominant Association with a Restricted Set of Core Mediator Subunits and an Affinity to Additional Structural and Enzymatic Proteins. 3236 3