Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A role for histone acetylation, which can alter the accessibility of DNA to transcriptional regulatory proteins and contribute to gene expression, in regulating terminal B cell differentiation was investigated in the mature B lymphoma L10A and mouse splenic B cells. Incubation of the L10A cells with the histone deacetylase (HDAC) inhibitors trichostatin A (TSA) and butyrate increased expression of Blimp-1, J chain, and mad genes, decreased expression of c-myc and BSAP/Pax-5 genes, increased the expression of surface CD43 and Syndecan-1, and decreased surface IgM. Incubation of splenic B cells with TSA and dextran conjugated anti-IgD Ab increased Blimp-1 gene and Syndecan-1 surface expression. The alteration in gene expression and cell surface markers was consistent with induction of the onset of terminal B cell differentiation. Co-incubation of L10A cells with TSA and cycloheximide (CHX) abrogated the up-regulation of Blimp-1 expression, indicating that TSA-activated Blimp-1 expression required synthesis of a transcriptional activator. In contrast, mad expression was increased in L10A cells cultured with TSA and cycloheximide or cycloheximide alone, suggesting mad expression may occur independent of Blimp-1 expression and is regulated by a labile, HDAC associated transcriptional repressor. The results demonstrate that histone acetylation regulates transcription of genes controlling terminal B cell differentiation.
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PMID:Activation of terminal B cell differentiation by inhibition of histone deacetylation. 1269 18

Initiation of meiosis in Saccharomyces cerevisiae is regulated by mating type and nutritional conditions that restrict meiosis to diploid cells grown under starvation conditions. Specifically, meiosis occurs in MATa/MATalpha cells shifted to nitrogen depletion media in the absence of glucose and the presence of a nonfermentable carbon source. These conditions lead to the expression and activation of Ime 1, the master regulator of meiosis. IME1 encodes a transcriptional activator recruited to promoters of early meiosis-specific genes by association with the DNA-binding protein, Ume6. Under vegetative growth conditions these genes are silent due to recruitment of the Sin3/Rpd3 histone deacetylase and Isw2 chromatin remodeling complexes by Ume6. Transcription of these meiotic genes occurs following histone acetylation by Gcn5. Expression of the early genes promote entry into the meiotic cycle, as they include genes required for premeiotic DNA synthesis, synapsis of homologous chromosomes, and meiotic recombination. Two of the early meiosis specific genes, a transcriptional activator, Ndt80, and a CDK2 homologue, Ime2, are required for the transcription of middle meiosis-specific genes that are involved with nuclear division and spore formation. Spore maturation depends on late genes whose expression is indirectly dependent on Ime1, Ime2, and Ndt80. Finally, phosphorylation of Imel by Ime2 leads to its degradation, and consequently to shutting down of the meiotic transcriptional cascade. This review is focusing on the regulation of gene expression governing initiation and progression through meiosis.
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PMID:Transcriptional regulation of meiosis in budding yeast. 1272 50

We report that HDAC7, a class II histone deacetylase, is highly expressed in CD4(+)CD8(+) double-positive thymocytes. HDAC7 inhibits the expression of Nur77, an orphan receptor involved in apoptosis and negative selection, via the transcription factor MEF2D. HDAC7 is exported from the nucleus during T cell receptor activation, leading to Nur77 expression. A triple HDAC7 mutant (S155A, S318A, S448A) is not exported from the nucleus in response to TCR activation and suppresses TCR-mediated apoptosis. Conversely, a fusion of HDAC7 to the transcriptional activator VP16 activates Nur77 expression. Inhibition of HDAC7 expression by RNA interference causes increased apoptosis in response to TCR activation. These observations define HDAC7 as a regulator of Nur77 and apoptosis in developing thymocytes.
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PMID:HDAC7, a thymus-specific class II histone deacetylase, regulates Nur77 transcription and TCR-mediated apoptosis. 1275 45

Sp3 transcription factor can either activate or repress target gene expression. However, the molecular event that controls this dual function is unclear. We previously reported (Ammanamanchi, S., and Brattain, M. G. (2001) J. Biol. Chem. 276, 3348-3352) that unmodified Sp3 acts as a transcriptional repressor of transforming growth factor-beta receptors in MCF-7L breast cancer cells. We now report that histone deacetylase inhibitor trichostatin A (TSA) induces acetylation of Sp3, which acts as a transcriptional activator of transforming growth factor-beta receptor type II (RII) in MCF-7L cells. Mutation analysis indicated the TSA response is mediated through a GC box located on the RII promoter, which was previously identified as an Sp1/Sp3-binding site that was critical for RII promoter activity. Ectopic Sp3 expression in Sp3-deficient MCF-7E breast cancer cells repressed RII promoter activity in the absence of TSA. However, in the TSA-treated MCF-7E cells ectopic Sp3 activated RII promoter. Histone acetyltransferase p300 was shown to acetylate Sp3. Sp3-mediated RII promoter activity was stimulated by wild type p300 but not the histone acetyltransferase domain-deleted mutant p300 in MCF-7L cells, suggesting the positive effect of p300 acetylase activity on Sp3. Consequently, the results presented in this manuscript demonstrate that acetylation acts as a switch that controls the repressor and activator role of Sp3.
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PMID:Acetylated sp3 is a transcriptional activator. 1283 48

The switch from latent to lytic infection of Kaposi's sarcoma-associated herpesvirus is initiated by the immediate early transcriptional activator protein Rta/open reading frame 50 (ORF50). We examined the transcriptional regulation of the ORF50 core promoter in response to lytic cycle stimulation. We show that the ORF50 promoter is highly responsive to sodium butyrate (NaB) and trichostatin A (TSA), two chemicals known to inhibit histone deacetylases. The NaB and TSA responsive element was mapped to a 70-bp minimal promoter containing an essential GC box that binds Sp1/Sp3 in vitro and in vivo. Micrococcal nuclease mapping studies revealed that a nucleosome is positioned over the transcriptional initiation and the Sp1/3 binding sites. Stimulation with NaB or TSA increased histone acetylation and restriction enzyme accessibility of the ORF50 promoter transcription initiation site. Chromatin immunoprecipitation assay was used to demonstrate that the ORF50 promoter is associated with several different histone deacetylase proteins (including HDAC1, 5, and 7) in latently infected cells. NaB treatment led to the rapid association of Ini1/Snf5, a component of the Swi/Snf family of chromatin remodeling proteins, with the ORF50 promoter. Ectopic expression of the CREB-binding protein (CBP) histone acetyltransferase (HAT) stimulated plasmid-based ORF50 transcription in a HAT-dependent manner, suggesting that CBP recruitment to the ORF50 promoter can be an initiating event for transcription and viral reactivation. Together, these results suggest that remodeling of a stably positioned nucleosome at the transcriptional initiation site of ORF50 is a regulatory step in the transition from latent to lytic infection.
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PMID:Chromatin remodeling of the Kaposi's sarcoma-associated herpesvirus ORF50 promoter correlates with reactivation from latency. 1455 28

PML-RAR is an oncogenic transcription factor forming in acute promyelocytic leukemias (APL) because of a chromosomal translocation. Without its ligand, retinoic acid (RA), PML-RAR functions as a constitutive transcriptional repressor, abnormally associating with the corepressor-histone deacetylase complex and blocking hematopoietic differentiation. In the presence of pharmacological concentrations of RA, PML-RAR activates transcription and stimulates differentiation. Even though it has been suggested that chromatin alteration is important for APL onset, the PML-RAR effect on chromatin of target promoters has not been investigated. Taking advantage of the Xenopus oocyte system, we compared the wild-type transcription factor RARalpha with PML-RAR as both transcriptional regulators and chromatin structure modifiers. Without RA, we found that PML-RAR is a more potent transcriptional repressor that does not require the cofactor RXR and produces a closed chromatin configuration. Surprisingly, repression by PML-RAR occurs through a further pathway that is independent of nucleosome deposition and histone deacetylation. In the presence of RA, PML-RAR is a less efficient transcriptional activator that is unable to modify the DNA nucleoprotein structure. We propose that PML-RAR, aside from its ability to recruit aberrant quantities of histone deacetylase complexes, has acquired additional repressive mechanisms and lost important activating functions; the comprehension of these mechanisms might reveal novel targets for antileukemic intervention.
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PMID:Retinoic acid receptor alpha fusion to PML affects its transcriptional and chromatin-remodeling properties. 1461 19

In eukaryotes, the switch between alternative developmental pathways is mainly attributed to a switch in transcriptional programs. A major mode in this switch is the transition between histone deacetylation and acetylation. In budding yeast, early meiosis-specific genes (EMGs) are repressed in the mitotic cell cycle by active deacetylation of their histones. Transcriptional activation of these genes in response to the meiotic signals (i.e., glucose and nitrogen depletion) requires histone acetylation. Here we follow how this regulated switch is accomplished, demonstrating the existence of two parallel mechanisms. (i) We demonstrate that depletion of glucose and nitrogen leads to a transient replacement of the histone deacetylase (HDAC) complex on the promoters of EMG by the transcriptional activator Ime1. The occupancy by either component occurs independently of the presence or absence of the other. Removal of the HDAC complex depends on the protein kinase Rim15, whose activity in the presence of nutrients is inhibited by protein kinase A phosphorylation. (ii) In the absence of glucose, HDAC loses its ability to repress transcription, even if this repression complex is directly bound to a promoter. We show that this relief of repression depends on Ime1, as well as on the kinase activity of Rim11, a glycogen synthase kinase 3beta homolog that phosphorylates Ime1. We further show that the glucose signal is transmitted through Rim11. In cells expressing the constitutive active rim11-3SA allele, HDAC repression in glucose medium is impaired.
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PMID:Glucose and nitrogen regulate the switch from histone deacetylation to acetylation for expression of early meiosis-specific genes in budding yeast. 1516 85

Hypoxia-inducible factor (HIF)-1alpha is a transcription factor that controls expression of genes responsive to low oxygen tension, including vascular endothelial growth factor (VEGF), erythropoietin, and glycolytic enzymes. The activity of HIF-1alpha is regulated by binding to the transcriptional co-activator cAMP-response element-binding protein-binding protein (CBP)/p300. Using the yeast two-hybrid screening system, we found that the inhibitory domain of HIF-1alpha strongly interacted with the C-terminal domain of histone deacetylase (HDAC) 7. The o-nitrophenyl beta-d-galactopyranoside assay revealed that regions containing amino acids 735-785 of HIF-1alpha and amino acids 669-952 of HDAC7 were minimum contact sites of the interaction. The binding of HDAC7 with HIF-1alpha was reproduced in HEK293 cells grown under normoxic and hypoxic conditions (2% O(2)). HDAC7 bound solely to HIF-1alpha among other HIF-alpha family members, including HIF-2alpha and HIF-3alpha, whereas HIF-1alpha only interacted with HDAC7 in the class II HDAC family. Although HDAC7 was localized dominantly in the cytoplasm at normal oxygen concentrations, HDAC7 co-translocated to the nucleus with HIF-1alpha under hypoxic conditions. In the nucleus, HDAC7 increased transcriptional activity of HIF-1alpha through the formation of a complex with HIF-1alpha, HDAC7, and p300. Taken together, these results indicate that HDAC7 is a novel transcriptional activator of HIF-1alpha
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PMID:Histone deacetylase 7 associates with hypoxia-inducible factor 1alpha and increases transcriptional activity. 1528 Mar 64

The ETS-domain transcription factor Elk-1 is a MAP kinase-inducible transcriptional activator protein. However, in the basal state, its activity is repressed by SUMO-dependent histone deacetylase (HDAC) recruitment. Relief of this repression accompanies the activation process. Here, we demonstrate that PIASx(alpha) acts to facilitate this derepression process. Members of the PIAS family of proteins can act as E3 enzymes that enhance the sumoylation status of a variety of substrates. However, PIASx-mediated coactivation of Elk-1 occurs in an E3 activity-independent manner. PIASx(alpha) binds to Elk-1 in vivo and enhances its transcriptional activity. The coactivating properties of PIASx(alpha) require Elk-1 to be modified with SUMO and the integrity of the SUMO binding motif in PIASx(alpha). PIASx(alpha) activates Elk-1 through alterations in the HAT/HDAC activities associated with Elk-1. In particular, PIASx(alpha) facilitates the loss of the repressive HDAC-2 from sumoylated Elk-1, a key event in the activation of Elk-1 in response to signalling through the ERK MAP kinase pathway. Our data therefore reveal a novel coactivator function for PIASx(alpha) through reversing SUMO-mediated repression of transcription factor activity.
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PMID:PIASx acts as an Elk-1 coactivator by facilitating derepression. 1592 Apr 81

mSin3A is a core component of a large multiprotein corepressor complex with associated histone deacetylase (HDAC) enzymatic activity. Physical interactions of mSin3A with many sequence-specific transcription factors has linked the mSin3A corepressor complex to the regulation of diverse signaling pathways and associated biological processes. To dissect the complex nature of mSin3A's actions, we monitored the impact of conditional mSin3A deletion on the developmental, cell biological, and transcriptional levels. mSin3A was shown to play an essential role in early embryonic development and in the proliferation and survival of primary, immortalized, and transformed cells. Genetic and biochemical analyses established a role for mSin3A/HDAC in p53 deacetylation and activation, although genetic deletion of p53 was not sufficient to attenuate the mSin3A null cell lethal phenotype. Consistent with mSin3A's broad biological activities beyond regulation of the p53 pathway, time-course gene expression profiling following mSin3A deletion revealed deregulation of genes involved in cell cycle regulation, DNA replication, DNA repair, apoptosis, chromatin modifications, and mitochondrial metabolism. Computational analysis of the mSin3A transcriptome using a knowledge-based database revealed several nodal points through which mSin3A influences gene expression, including the Myc-Mad, E2F, and p53 transcriptional networks. Further validation of these nodes derived from in silico promoter analysis showing enrichment for Myc-Mad, E2F, and p53 cis-regulatory elements in regulatory regions of up-regulated genes following mSin3A depletion. Significantly, in silico promoter analyses also revealed specific cis-regulatory elements binding the transcriptional activator Stat and the ISWI ATP-dependent nucleosome remodeling factor Falz, thereby expanding further the mSin3A network of regulatory factors. Together, these integrated genetic, biochemical, and computational studies demonstrate the involvement of mSin3A in the regulation of diverse pathways governing many aspects of normal and neoplastic growth and survival and provide an experimental framework for the analysis of essential genes with diverse biological functions.
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PMID:mSin3A corepressor regulates diverse transcriptional networks governing normal and neoplastic growth and survival. 1599 11


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