scholarly journals In Vivo Requirement of Activator-Specific Binding Targets of Mediator

2000 ◽  
Vol 20 (23) ◽  
pp. 8709-8719 ◽  
Author(s):  
Jin Mo Park ◽  
Hye-Suk Kim ◽  
Sang Jun Han ◽  
Moon-Sun Hwang ◽  
Young Chul Lee ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Specific Binding ◽  
Gene Activation ◽  
Dna Interaction ◽  
Activation Process ◽  
Binding Region ◽  
Physiological Conditions ◽  
Functional Analyses

ABSTRACT There has been no unequivocal demonstration that the activator binding targets identified in vitro play a key role in transcriptional activation in vivo. To examine whether activator-Mediator interactions are required for gene transcription under physiological conditions, we performed functional analyses with Mediator components that interact specifically with natural yeast activators. Different activators interact with Mediator via distinct binding targets. Deletion of a distinct activator binding region of Mediator completely compromised gene activation in vivo by some, but not all, transcriptional activators. These demonstrate that the activator-specific targets in Mediator are essential for transcriptional activation in living cells, but their requirement was affected by the nature of the activator-DNA interaction and the existence of a postrecruitment activation process.

scholarly journals A Specificity and Targeting Subunit of a Human SWI/SNF Family-Related Chromatin-Remodeling Complex

2000 ◽  
Vol 20 (23) ◽  
pp. 8879-8888 ◽  
Author(s):  
Zuqin Nie ◽  
Yutong Xue ◽  
Dafeng Yang ◽  
Sharleen Zhou ◽  
Bonnie J. Deroo ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Chromatin Remodeling ◽  
Protein Interactions ◽  
Transcriptional Activation ◽  
Gene Activation ◽  
Dna Interaction ◽  
Protein Protein Interactions ◽  
Baf Complex ◽  
Chromatin Remodeling Complexes

ABSTRACT The SWI/SNF family of chromatin-remodeling complexes facilitates gene activation by assisting transcription machinery to gain access to targets in chromatin. This family includes BAF (also called hSWI/SNF-A) and PBAF (hSWI/SNF-B) from humans and SWI/SNF and Rsc fromSaccharomyces cerevisiae. However, the relationship between the human and yeast complexes is unclear because all human subunits published to date are similar to those of both yeast SWI/SNF and Rsc. Also, the two human complexes have many identical subunits, making it difficult to distinguish their structures or functions. Here we describe the cloning and characterization of BAF250, a subunit present in human BAF but not PBAF. BAF250 contains structural motifs conserved in yeast SWI1 but not in any Rsc components, suggesting that BAF is related to SWI/SNF. BAF250 is also a homolog of the Drosophila melanogaster Osa protein, which has been shown to interact with a SWI/SNF-like complex in flies. BAF250 possesses at least two conserved domains that could be important for its function. First, it has an AT-rich DNA interaction-type DNA-binding domain, which can specifically bind a DNA sequence known to be recognized by a SWI/SNF family-related complex at the β-globin locus. Second, BAF250 stimulates glucocorticoid receptor-dependent transcriptional activation, and the stimulation is sharply reduced when the C-terminal region of BAF250 is deleted. This region of BAF250 is capable of interacting directly with the glucocorticoid receptor in vitro. Our data suggest that BAF250 confers specificity to the human BAF complex and may recruit the complex to its targets through either protein-DNA or protein-protein interactions.

scholarly journals A yeast ARS-binding protein activates transcription synergistically in combination with other weak activating factors.

1990 ◽  
Vol 10 (3) ◽  
pp. 887-897 ◽  
Author(s):  
A R Buchman ◽  
R D Kornberg
Keyword(s):  
Dna Sequences ◽  
Transcriptional Activation ◽  
Binding Sites ◽  
Essential Gene ◽  
Specific Binding ◽  
Binding Protein ◽  
Point Mutations ◽  
Yeast Genes

ABFI (ARS-binding protein I) is a yeast protein that binds specific DNA sequences associated with several autonomously replicating sequences (ARSs). ABFI also binds sequences located in promoter regions of some yeast genes, including DED1, an essential gene of unknown function that is transcribed constitutively at a high level. ABFI was purified by specific binding to the DED1 upstream activating sequence (UAS) and was found to recognize related sequences at several other promoters, at an ARS (ARS1), and at a transcriptional silencer (HMR E). All ABFI-binding sites, regardless of origin, provided weak UAS function in vivo when examined in test plasmids. UAS function was abolished by point mutations that reduced ABFI binding in vitro. Analysis of the DED1 promoter showed that two ABFI-binding sites combine synergistically with an adjacent T-rich sequence to form a strong constitutive activator. The DED1 T-rich element acted synergistically with all other ABFI-binding sites and with binding sites for other multifunctional yeast activators. An examination of the properties of sequences surrounding ARS1 left open the possibility that ABFI enhances the initiation of DNA replication at ARS1 by transcriptional activation.

Histone deacetylase–mediated transcriptional activation reduces proviral loads in HTLV-1–associated myelopathy/tropical spastic paraparesis patients

Blood ◽  
2007 ◽  
Vol 110 (10) ◽  
pp. 3722-3728 ◽  
Author(s):  
Agnès Lezin ◽  
Nicolas Gillet ◽  
Stéphane Olindo ◽  
Aïssatou Signaté ◽  
Nathalie Grandvaux ◽  
...  
Keyword(s):  
Histone Deacetylase ◽  
Transcriptional Activation ◽  
Gene Activation ◽  
Spastic Paraparesis ◽  
Viral Gene Expression ◽  
Tropical Spastic Paraparesis ◽  
Viral Reservoir ◽  
Viral Gene

AbstractEpigenetic modifications of chromatin may play a role in maintaining viral latency and thus persistence of the human T-lymphotropic virus type 1 (HTLV-1), which is responsible for HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP). A major determinant of disease progression is increased peripheral blood proviral load (PVL), possibly via the accumulation of infected cells in the central nervous system (CNS) creating a damaging inflammatory response. Current therapeutic approaches that focus on reducing either cell proliferation, viral replication, or tissue invasion are still unsatisfactory. Contrasting with these inhibitory strategies, we evaluated the efficacy of a novel approach aimed, paradoxically, at activating viral gene expression to expose virus-positive cells to the host immune response. We used valproate (VPA), a histone deacetylase inhibitor that has been used for decades as a chronic, safe treatment for epileptic disorders. Based on in vitro and in vivo data, we provide evidence that transient activation of the latent viral reservoir causes its collapse, a process that may alleviate the condition of HAM/TSP. This represents the first such approach to treating HAM/TSP, using gene activation therapy to tilt the host-pathogen balance in favor of an existing antiviral response. This trial is registered at http://clinicaltrials.gov/as no. NCT00519181.

scholarly journals Yeast Coactivator MBF1 Mediates GCN4-Dependent Transcriptional Activation

1998 ◽  
Vol 18 (9) ◽  
pp. 4971-4976 ◽  
Author(s):  
Ken-ichi Takemaru ◽  
Satoshi Harashima ◽  
Hitoshi Ueda ◽  
Susumu Hirose
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Dna Binding ◽  
Nuclear Receptor ◽  
Transcriptional Activation ◽  
Crucial Role ◽  
Tata Binding Protein ◽  
Binding Region

ABSTRACT Transcriptional coactivators play a crucial role in gene expression by communicating between regulatory factors and the basal transcription machinery. The coactivator multiprotein bridging factor 1 (MBF1) was originally identified as a bridging molecule that connects theDrosophila nuclear receptor FTZ-F1 and TATA-binding protein (TBP). The MBF1 sequence is highly conserved across species fromSaccharomyces cerevisiae to human. Here we provide evidence acquired in vitro and in vivo that yeast MBF1 mediates GCN4-dependent transcriptional activation by bridging the DNA-binding region of GCN4 and TBP. These findings indicate that the coactivator MBF1 functions by recruiting TBP to promoters where DNA-binding regulators are bound.

scholarly journals Signal-Induced Transcriptional Activation by Dif Requires the dTRAP80 Mediator Module

2003 ◽  
Vol 23 (4) ◽  
pp. 1358-1367 ◽  
Author(s):  
Jin Mo Park ◽  
Jung Mo Kim ◽  
Lark Kyun Kim ◽  
Se Nyun Kim ◽  
Jeongsil Kim-Ha ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcriptional Activation ◽  
Specific Binding ◽  
Regulation Of Gene Expression ◽  
Transcriptional Activator ◽  
Mediator Complex ◽  
Activator Proteins ◽  
In Vitro Interactions

ABSTRACT The Mediator complex is the major multiprotein transcriptional coactivator complex in Drosophila melanogaster. Mediator components interact with diverse sets of transcriptional activator proteins to elicit the sophisticated regulation of gene expression. The distinct phenotypes associated with certain mutations in some of the Mediator genes and the specific in vitro interactions of Mediator gene products with transcriptional activator proteins suggest the presence of activator-specific binding subunits within the Mediator complex. However, the physiological relevance of these selective in vitro interactions has not been addressed. Therefore, we analyzed dTRAP80, one of the putative activator-binding subunits of the Mediator, for specificity of binding to a number of natural transcriptional activators from Drosophila. Among the group of activator proteins that requires the Mediator complex for transcriptional activation, only a subset of these proteins interacted with dTRAP80 in vitro and only these dTRAP80-interacting activators were defective for activation under dTRAP80-deficient in vivo conditions. In particular, activation of Drosophila antimicrobial peptide drosomycin gene expression by the NF-κB-like transcription factor Dif during induction of the Toll signaling pathway was dependent on the dTRAP80 module. These results, and the indirect support from the dTRAP80 artificial recruitment assay, indicate that dTRAP80 serves as a genuine activator-binding target responsible for a distinct group of activators.

Butyrate induces selective transcriptional activation of a hypomethylated embryonic globin gene in adult erythroid cells

Blood ◽  
1988 ◽  
Vol 72 (5) ◽  
pp. 1536-1542
Author(s):  
LJ Burns ◽  
JG Glauber ◽  
GD Ginder
Keyword(s):  
Sodium Butyrate ◽  
Transcriptional Activation ◽  
Globin Gene ◽  
Gene Activation ◽  
Globin Genes ◽  
Erythroid Cells ◽  
Hemoglobin Switching ◽  
High Level

An animal model of hemoglobin switching has been developed in which anemic adult chickens are treated with 5-azacytidine and sodium butyrate or alpha-aminobutyric acid, thereby resulting in activation of the embryonic rho-globin gene in adult erythroid cells. In vitro nuclear runoff transcription assays using erythroid nuclei from treated birds show that the mechanism of activation of the rho-globin gene is transcriptional whereas no transcriptional activation of the embryonic epsilon-globin gene occurs. The action of 5-azacytidine appears to be as an inhibitor of DNA methylation because other S-phase active cytotoxic drugs, when substituted for 5-azacytidine, do not cause demethylation of the embryonic globin genes, nor do they allow transcriptional activation to occur. Embryonic rho-globin gene activation in this model is not due to selection of primitive erythroid cells since a subpopulation of primitive erythroid cells is not evident either morphologically or when cells are probed for embryonic and adult globin RNA by in situ hybridization. These studies show that demethylation by 5-azacytidine is a prerequisite but not sufficient cis- regulatory event for a high level of transcriptional activation of the embryonic rho-globin gene in adult erythroid cells in vivo. The possible basis for the selective transcriptional activation by sodium butyrate in this system is discussed.

scholarly journals A Central Role for Canonical PRC1 in Shaping the 3D Nuclear Landscape

2019 ◽  
Author(s):  
Shelagh Boyle ◽  
Ilya M. Flyamer ◽  
Iain Williamson ◽  
Dipta Sengupta ◽  
Wendy A. Bickmore ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Gene Activation ◽  
Embryonic Stem ◽  
Nuclear Architecture ◽  
Regulatory System ◽  
Spatial Arrangement ◽  
Polycomb Group ◽  
List Type

AbstractPolycomb group (PcG) proteins silence gene expression by chemically and physically modifying chromatin. A subset of PcG target loci are compacted and cluster in the nucleus to form observable bodies; a conformation which is thought to contribute to gene silencing. However, how these interactions influence gross nuclear organisation and their relationship with transcription remains poorly understood. Here we examine the role of Polycomb Repressive Complex 1 (PRC1) in shaping 3D genome organization in mouse embryonic stem cells (mESCs). Using a combination of imaging and Hi-C analyses we show that PRC1-mediated long-range interactions are independent of CTCF and can bridge sites at a megabase scale. Impairment of PRC1 enzymatic activity does not directly disrupt these interactions. We demonstrate that PcG targets coalesce in vivo, and that developmentally induced expression of one of the target loci disrupts this spatial arrangement. Finally, we show that transcriptional activation and the loss of PRC1-mediated interactions are seperable events. These findings provide important insights into the function of PRC1, whilst highlighting the complexity of this regulatory system.HighlightsLoss of RING1B substantially disrupts nuclear architecture.PRC1 mediated looping can occur at a Mb scale and is independent of CTCF.Polycomb mediated looping is driven by canonical PRC1 complexes.Multimeric PRC1-mediated interactions occur in vitro and in vivo.Disruption of PRC1-mediated looping is independent of gene activation.

scholarly journals Transcriptional Activation by Bacillus subtilis ResD: Tandem Binding to Target Elements and Phosphorylation-Dependent and -Independent Transcriptional Activation

2004 ◽  
Vol 186 (7) ◽  
pp. 2028-2037 ◽  
Author(s):  
Hao Geng ◽  
Shunji Nakano ◽  
Michiko M. Nakano
Keyword(s):  
Bacillus Subtilis ◽  
Transcriptional Activation ◽  
Response Regulator ◽  
Gene Activation ◽  
Phosphorylation Site ◽  
Oxygen Limitation ◽  
Nitrate Respiration ◽  
Expression Of Genes

ABSTRACT The expression of genes involved in nitrate respiration in Bacillus subtilis is regulated by the ResD-ResE two-component signal transduction system. The membrane-bound ResE sensor kinase perceives a redox-related signal(s) and phosphorylates the cognate response regulator ResD, which enables interaction of ResD with ResD-dependent promoters to activate transcription. Hydroxyl radical footprinting analysis revealed that ResD tandemly binds to the −41 to −83 region of hmp and the −46 to −92 region of nasD. In vitro runoff transcription experiments showed that ResD is necessary and sufficient to activate transcription of the ResDE regulon. Although phosphorylation of ResD by ResE kinase greatly stimulated transcription, unphosphorylated ResD, as well as ResD with a phosphorylation site (Asp57) mutation, was able to activate transcription at a low level. The D57A mutant was shown to retain the activity in vivo to induce transcription of the ResDE regulon in response to oxygen limitation, suggesting that ResD itself, in addition to its activation through phosphorylation-mediated conformation change, senses oxygen limitation via an unknown mechanism leading to anaerobic gene activation.

scholarly journals Butyrate induces selective transcriptional activation of a hypomethylated embryonic globin gene in adult erythroid cells

Blood ◽  
1988 ◽  
Vol 72 (5) ◽  
pp. 1536-1542 ◽  
Author(s):  
LJ Burns ◽  
JG Glauber ◽  
GD Ginder
Keyword(s):  
Sodium Butyrate ◽  
Transcriptional Activation ◽  
Globin Gene ◽  
Gene Activation ◽  
Globin Genes ◽  
Erythroid Cells ◽  
Hemoglobin Switching ◽  
High Level

Abstract An animal model of hemoglobin switching has been developed in which anemic adult chickens are treated with 5-azacytidine and sodium butyrate or alpha-aminobutyric acid, thereby resulting in activation of the embryonic rho-globin gene in adult erythroid cells. In vitro nuclear runoff transcription assays using erythroid nuclei from treated birds show that the mechanism of activation of the rho-globin gene is transcriptional whereas no transcriptional activation of the embryonic epsilon-globin gene occurs. The action of 5-azacytidine appears to be as an inhibitor of DNA methylation because other S-phase active cytotoxic drugs, when substituted for 5-azacytidine, do not cause demethylation of the embryonic globin genes, nor do they allow transcriptional activation to occur. Embryonic rho-globin gene activation in this model is not due to selection of primitive erythroid cells since a subpopulation of primitive erythroid cells is not evident either morphologically or when cells are probed for embryonic and adult globin RNA by in situ hybridization. These studies show that demethylation by 5-azacytidine is a prerequisite but not sufficient cis- regulatory event for a high level of transcriptional activation of the embryonic rho-globin gene in adult erythroid cells in vivo. The possible basis for the selective transcriptional activation by sodium butyrate in this system is discussed.

A yeast ARS-binding protein activates transcription synergistically in combination with other weak activating factors

1990 ◽  
Vol 10 (3) ◽  
pp. 887-897
Author(s):  
A R Buchman ◽  
R D Kornberg
Keyword(s):  
Dna Sequences ◽  
Transcriptional Activation ◽  
Binding Sites ◽  
Essential Gene ◽  
Specific Binding ◽  
Binding Protein ◽  
Point Mutations ◽  
Yeast Genes

ABFI (ARS-binding protein I) is a yeast protein that binds specific DNA sequences associated with several autonomously replicating sequences (ARSs). ABFI also binds sequences located in promoter regions of some yeast genes, including DED1, an essential gene of unknown function that is transcribed constitutively at a high level. ABFI was purified by specific binding to the DED1 upstream activating sequence (UAS) and was found to recognize related sequences at several other promoters, at an ARS (ARS1), and at a transcriptional silencer (HMR E). All ABFI-binding sites, regardless of origin, provided weak UAS function in vivo when examined in test plasmids. UAS function was abolished by point mutations that reduced ABFI binding in vitro. Analysis of the DED1 promoter showed that two ABFI-binding sites combine synergistically with an adjacent T-rich sequence to form a strong constitutive activator. The DED1 T-rich element acted synergistically with all other ABFI-binding sites and with binding sites for other multifunctional yeast activators. An examination of the properties of sequences surrounding ARS1 left open the possibility that ABFI enhances the initiation of DNA replication at ARS1 by transcriptional activation.

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