scholarly journals RBP-Jκ/SHARP Recruits CtIP/CtBP Corepressors To Silence Notch Target Genes

2005 ◽  
Vol 25 (23) ◽  
pp. 10379-10390 ◽  
Author(s):  
Franz Oswald ◽  
Michael Winkler ◽  
Ying Cao ◽  
Kathy Astrahantseff ◽  
Soizic Bourteele ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Target Gene ◽  
Animal Species ◽  
Target Genes ◽  
Dna Binding Protein ◽  
Dominant Negative ◽  
Cell Fates ◽  
Corepressor Complex ◽  
Necessary And Sufficient ◽  
Repression Domain

ABSTRACT Notch is a transmembrane receptor that determines cell fates and pattern formation in all animal species. After ligand binding, proteolytic cleavage steps occur and the intracellular part of Notch translocates to the nucleus, where it targets the DNA-binding protein RBP-Jκ/CBF1. In the absence of Notch, RBP-Jκ represses Notch target genes through the recruitment of a corepressor complex. We and others have identified SHARP as a component of this complex. Here, we functionally demonstrate that the SHARP repression domain is necessary and sufficient to repress transcription and that the absence of this domain causes a dominant negative Notch-like phenotype. We identify the CtIP and CtBP corepressors as novel components of the human RBP-Jκ/SHARP-corepressor complex and show that CtIP binds directly to the SHARP repression domain. Functionally, CtIP and CtBP augment SHARP-mediated repression. Transcriptional repression of the Notch target gene Hey1 is abolished in CtBP-deficient cells or after the functional knockout of CtBP. Furthermore, the endogenous Hey1 promoter is derepressed in CtBP-deficient cells. We propose that a corepressor complex containing CtIP/CtBP facilitates RBP-Jκ/SHARP-mediated repression of Notch target genes.

scholarly journals ETO, but Not Leukemogenic Fusion Protein AML1/ETO, Augments RBP-Jκ/SHARP-Mediated Repression of Notch Target Genes

2008 ◽  
Vol 28 (10) ◽  
pp. 3502-3512 ◽  
Author(s):  
Daniela Salat ◽  
Robert Liefke ◽  
Jörg Wiedenmann ◽  
Tilman Borggrefe ◽  
Franz Oswald
Keyword(s):  
Fusion Protein ◽  
Myeloid Leukemia ◽  
Animal Species ◽  
Target Genes ◽  
Dependent Manner ◽  
Gene Promoters ◽  
Cell Fates ◽  
Oncogenic Potential ◽  
Corepressor Complex ◽  
Specific Ligand

ABSTRACT Notch is a transmembrane receptor that determines cell fates and pattern formation in all animal species. After specific ligand binding, the intracellular part of Notch is cleaved off and translocates to the nucleus, where it targets the DNA binding protein RBP-Jκ. In the absence of Notch, RBP-Jκ represses Notch target genes by recruiting a corepressor complex. We and others have previously identified SHARP as one component of this complex. Here, we show that the corepressor ETO as well as the leukemogenic fusion protein AML1/ETO directly interacts with SHARP, that ETO is part of the endogenous RBP-Jκ-containing corepressor complex, and that ETO is found at Notch target gene promoters. In functional assays, corepressor ETO, but not AML1/ETO, augments SHARP-mediated repression in an histone deacetylase-dependent manner. Furthermore, either the knockdown of ETO or the overexpression of AML1/ETO activates Notch target genes. Therefore, we propose that AML1/ETO can disturb the normal, repressive function of ETO at Notch target genes. This activating (or derepressing) effect of AML1/ETO may contribute to its oncogenic potential in myeloid leukemia.

scholarly journals Direct regulation of nacre, a zebrafish MITF homolog required for pigment cell formation, by the Wnt pathway

2000 ◽  
Vol 14 (2) ◽  
pp. 158-162 ◽  
Author(s):  
Richard I. Dorsky ◽  
David W. Raible ◽  
Randall T. Moon
Keyword(s):  
Cell Differentiation ◽  
Binding Sites ◽  
Pigment Cell ◽  
Cell Formation ◽  
Dominant Negative ◽  
Reporter Construct ◽  
Cell Fates ◽  
Necessary And Sufficient

We have shown that Wnt signals are necessary and sufficient for neural crest cells to adopt pigment cell fates. nacre, a zebrafish homolog of MITF, is required for pigment cell differentiation. We isolated a promoter region of nacre that contains Tcf/Lef binding sites, which can mediate Wnt responsiveness. This promoter binds to zebrafish Lef1 protein in vitro, and a nacre reporter construct is strongly repressed by dominant-negative Tcf in melanoma cells. Mutation of Tcf/Lef sites abolishes Lef1 binding and reporter function in vivo. Wnt signaling therefore directly activatesnacre, which in turn leads to pigment cell differentiation.

AML-1/ETO fusion protein is a dominant negative inhibitor of transcriptional repression by the promyelocytic leukemia zinc finger protein

Blood ◽  
2000 ◽  
Vol 96 (12) ◽  
pp. 3939-3947 ◽  
Author(s):  
Ari Melnick ◽  
Graeme W. Carlile ◽  
Melanie J. McConnell ◽  
Adam Polinger ◽  
Scott W. Hiebert ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Zinc Finger ◽  
Transcriptional Repression ◽  
Target Genes ◽  
Zinc Finger Protein ◽  
Promyelocytic Leukemia ◽  
Dominant Negative ◽  
Myelogenous Leukemia ◽  
Promyelocytic Leukemia Zinc Finger ◽  
Dominant Negative Inhibitor

Abstract The AML-1/ETO fusion protein, created by the (8;21) translocation in M2-type acute myelogenous leukemia (AML), is a dominant repressive form of AML-1. This effect is due to the ability of the ETO portion of the protein to recruit co-repressors to promoters of AML-1 target genes. The t(11;17)(q21;q23)-associated acute promyelocytic leukemia creates the promyelocytic leukemia zinc finger PLZFt/RARα fusion protein and, in a similar manner, inhibits RARα target gene expression and myeloid differentiation. PLZF is expressed in hematopoietic progenitors and functions as a growth suppressor by repressing cyclin A2 and other targets. ETO is a corepressor for PLZF and potentiates transcriptional repression by linking PLZF to a histone deacetylase-containing complex. In transiently transfected cells and in a cell line derived from a patient with t(8;21) leukemia, PLZF and AML-1/ETO formed a tight complex. In transient assays, AML-1/ETO blocked transcriptional repression by PLZF, even at substoichiometric levels relative to PLZF. This effect was dependent on the presence of the ETO zinc finger domain, which recruits corepressors, and could not be rescued by overexpression of co-repressors that normally enhance PLZF repression. AML-1/ETO also excluded PLZF from the nuclear matrix and reduced its ability to bind to its cognate DNA-binding site. Finally, ETO interacted with PLZF/RARα and enhanced its ability to repress through the RARE. These data show a link in the transcriptional pathways of M2 and M3 leukemia.

scholarly journals Mth1 regulates the interaction between the Rgt1 repressor and the Ssn6-Tup1 corepressor complex by modulating PKA-dependent phosphorylation of Rgt1

2013 ◽  
Vol 24 (9) ◽  
pp. 1493-1503 ◽  
Author(s):  
Adhiraj Roy ◽  
Yong Jae Shin ◽  
Kyu Hong Cho ◽  
Jeong-Ho Kim
Keyword(s):  
Dna Binding ◽  
Target Genes ◽  
Glucose Transporter ◽  
Binding Activity ◽  
Supporting Evidence ◽  
Dna Binding Activity ◽  
Rate Limiting Step ◽  
Corepressor Complex ◽  
Necessary And Sufficient ◽  
Rate Limiting

Glucose uptake, the first, rate-limiting step of its utilization, is facilitated by glucose transporters. Expression of several glucose transporter (HXT) genes in yeast is repressed by the Rgt1 repressor, which recruits the glucose-responsive transcription factor Mth1 and the general corepressor complex Ssn6-Tup1 in the absence of glucose; however, it is derepressed when Mth1 is inactivated by glucose. Here we show that Ssn6-Tup1 interferes with the DNA-binding ability of Rgt1 in the absence of Mth1 and that the Rgt1 function abrogated by Ssn6 overexpression is restored by co-overexpression of Mth1. Thus Mth1 likely regulates Rgt1 function not by modulating its DNA-binding activity directly but by functionally antagonizing Ssn6-Tup1. Mth1 does so by acting as a scaffold-like protein to recruit Ssn6-Tup1 to Rgt1. Supporting evidence shows that Mth1 blocks the protein kinase A–dependent phosphorylation of Rgt1 that impairs the ability of Rgt1 to interact with Ssn6-Tup1. Of note, Rgt1 can bind DNA in the absence of Ssn6-Tup1 but does not inhibit transcription, suggesting that dissociation of Rgt1 from Ssn6-Tup1, but not from DNA, is necessary and sufficient for the expression of its target genes. Taken together, these findings show that Mth1 is a transcriptional corepressor that facilitates the recruitment of Ssn6-Tup1 by Rgt1.

scholarly journals Polycomb-group recruitment to a Drosophila target gene is the default state that is inhibited by a transcriptional activator

2021 ◽  
Vol 7 (29) ◽  
pp. eabg1556
Author(s):  
Elnaz Ghotbi ◽  
Piao Ye ◽  
Taylor Ervin ◽  
Anni Kum ◽  
Judith Benes ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Target Gene ◽  
Target Genes ◽  
De Novo ◽  
Polycomb Group ◽  
Polycomb Repressive Complex 2 ◽  
Repressive Chromatin ◽  
Group Recruitment ◽  
Default State ◽  
Present Experimental Evidence

Polycomb-group (PcG) proteins are epigenetic regulators that maintain the transcriptional repression of target genes following their initial repression by transcription factors. PcG target genes are repressed in some cells, but active in others. Therefore, a mechanism must exist by which PcG proteins distinguish between the repressed and active states and only assemble repressive chromatin environments at target genes that are repressed. Here, we present experimental evidence that the repressed state of a Drosophila PcG target gene, giant (gt), is not identified by the presence of a repressor. Rather, de novo establishment of PcG-mediated silencing at gt is the default state that is prevented by the presence of an activator or coactivator, which may inhibit the catalytic activity of Polycomb-repressive complex 2 (PRC2).

scholarly journals mSin3A/Histone Deacetylase 2- and PRMT5-Containing Brg1 Complex Is Involved in Transcriptional Repression of the Myc Target Gene cad

2003 ◽  
Vol 23 (21) ◽  
pp. 7475-7487 ◽  
Author(s):  
Sharmistha Pal ◽  
Romy Yun ◽  
Antara Datta ◽  
Lynne Lacomis ◽  
Hediye Erdjument-Bromage ◽  
...  
Keyword(s):  
Histone Deacetylase ◽  
Transcriptional Activation ◽  
Transcriptional Repression ◽  
Target Genes ◽  
Carbamoyl Phosphate ◽  
Histone Deacetylase 2 ◽  
Protein Protein Interaction ◽  
Corepressor Complex ◽  
Expression Of Genes ◽  
In Cells

ABSTRACT The role of hSWI/SNF complexes in transcriptional activation is well characterized; however, little is known about their function in transcriptional repression. We have previously shown that subunits of the mSin3A/histone deacetylase 2 (HDAC2) corepressor complex copurify with hSWI/SNF complexes. Here we show that the type II arginine-specific methyltransferase PRMT5, which is involved in cyclin E repression, can be found in association with Brg1 and hBrm-based hSWI/SNF complexes. We also show that hSWI/SNF-associated PRMT5 can methylate hypoacetylated histones H3 and H4 more efficiently than hyperacetylated histones H3 and H4. Protein-protein interaction studies indicate that PRMT5 and mSin3A interact with the same hSWI/SNF subunits as those targeted by c-Myc. These observations prompted us to examine the expression profile of the c-Myc target genes, carbamoyl-phosphate synthase-aspartate carbamoyltransferase-dihydroorotase (cad) and nucleolin (nuc). We found that cad repression is altered in cells that express inactive Brg1 and in cells treated with the HDAC inhibitor depsipeptide. Using chromatin immunoprecipitation assays, we found that Brg1, mSin3A, HDAC2, and PRMT5 are directly recruited to the cad promoter. These results suggest that hSWI/SNF complexes, through their ability to interact with activator and repressor proteins, control expression of genes involved in cell growth and proliferation.

scholarly journals Neoplastic Transformation of RK3E by Mutant β-Catenin Requires Deregulation of Tcf/Lef Transcription but Not Activation of c-myc Expression

1999 ◽  
Vol 19 (8) ◽  
pp. 5696-5706 ◽  
Author(s):  
Frank T. Kolligs ◽  
Gang Hu ◽  
Chi V. Dang ◽  
Eric R. Fearon
Keyword(s):  
Target Gene ◽  
Target Genes ◽  
Glycogen Synthase ◽  
Neoplastic Transformation ◽  
Dominant Negative ◽  
Epithelial Cell Line ◽  
Oncogenic Potential ◽  
Adenovirus E1a ◽  
Line Analysis

ABSTRACT Current models predict that β-catenin (β-cat) functions in Wnt signaling via activation of Tcf/Lef target genes and that its abundance is regulated by the adenomatous polyposis coli (APC) and glycogen synthase kinase 3β (GSK3β) proteins. In colon and other cancers, mutations in APC or presumptive GSK3β phosphorylation sites of β-cat are associated with constitutive activation of Tcf/Lef transcription. In spite of assumptions about its oncogenic potential, prior efforts to demonstrate that mutated β-cat will induce neoplastic transformation have yielded equivocal results. We report here that mutated, but not wild-type, β-cat proteins induced neoplastic transformation of RK3E, an adenovirus E1A-immortalized epithelial cell line. Analysis of the properties of mutant β-cat proteins and studies with a dominant negative Tcf-4 mutant indicated that the ability of β-cat to bind and activate Tcf/Lef factors is crucial for transformation. c-myc has recently been implicated as a critical Tcf-regulated target gene. However, c-myc was not consistently activated in β-cat-transformed RK3E cells, and a dominant negative c-Myc mutant protein failed to inhibit β-cat transformation. Our findings underscore the role of β-cat mutations and Tcf/Lef activation in cancer and illustrate a useful system for defining critical factors in β-cat transformation.

scholarly journals Two Distinct Types of Repression Domain in Engrailed: One Interacts with the Groucho Corepressor and Is Preferentially Active on Integrated Target Genes

1998 ◽  
Vol 18 (5) ◽  
pp. 2804-2814 ◽  
Author(s):  
Elena N. Tolkunova ◽  
Miki Fujioka ◽  
Masatomo Kobayashi ◽  
Deepali Deka ◽  
James B. Jaynes
Keyword(s):  
Transcriptional Repression ◽  
Target Gene ◽  
Target Genes ◽  
Cultured Cells ◽  
Regulation Of Gene Expression ◽  
Transient Transfection ◽  
Transient Transfection Assay ◽  
Interaction Domain ◽  
Transfection Assay

ABSTRACT Active transcriptional repression has been characterized as a function of many regulatory factors. It facilitates combinatorial regulation of gene expression by allowing repressors to be dominant over activators under certain conditions. Here, we show that the Engrailed protein uses two distinct mechanisms to repress transcription. One activity is predominant under normal transient transfection assay conditions in cultured cells. A second activity is predominant in an in vivo active repression assay. The domain mediating the in vivo activity (eh1) is highly conserved throughout several classes of homeoproteins and interacts specifically with the Groucho corepressor. While eh1 shows only weak activity in transient transfections, much stronger activity is seen in culture when an integrated target gene is used. In this assay, the relative activities of different repression domains closely parallel those seen in vivo, with eh1 showing the predominant activity. Reducing the amounts of repressor and target gene in a transient transfection assay also increases the sensitivity of the assay to the Groucho interaction domain, albeit to a lesser extent. This suggests that it utilizes rate-limiting components that are relatively low in abundance. Since Groucho itself is abundant in these cells, the results suggest that a limiting component is recruited effectively by the repressor-corepressor complex only on integrated target genes.

AML-1/ETO fusion protein is a dominant negative inhibitor of transcriptional repression by the promyelocytic leukemia zinc finger protein

Blood ◽  
2000 ◽  
Vol 96 (12) ◽  
pp. 3939-3947 ◽  
Author(s):  
Ari Melnick ◽  
Graeme W. Carlile ◽  
Melanie J. McConnell ◽  
Adam Polinger ◽  
Scott W. Hiebert ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Zinc Finger ◽  
Transcriptional Repression ◽  
Target Genes ◽  
Zinc Finger Protein ◽  
Promyelocytic Leukemia ◽  
Dominant Negative ◽  
Myelogenous Leukemia ◽  
Promyelocytic Leukemia Zinc Finger ◽  
Dominant Negative Inhibitor

The AML-1/ETO fusion protein, created by the (8;21) translocation in M2-type acute myelogenous leukemia (AML), is a dominant repressive form of AML-1. This effect is due to the ability of the ETO portion of the protein to recruit co-repressors to promoters of AML-1 target genes. The t(11;17)(q21;q23)-associated acute promyelocytic leukemia creates the promyelocytic leukemia zinc finger PLZFt/RARα fusion protein and, in a similar manner, inhibits RARα target gene expression and myeloid differentiation. PLZF is expressed in hematopoietic progenitors and functions as a growth suppressor by repressing cyclin A2 and other targets. ETO is a corepressor for PLZF and potentiates transcriptional repression by linking PLZF to a histone deacetylase-containing complex. In transiently transfected cells and in a cell line derived from a patient with t(8;21) leukemia, PLZF and AML-1/ETO formed a tight complex. In transient assays, AML-1/ETO blocked transcriptional repression by PLZF, even at substoichiometric levels relative to PLZF. This effect was dependent on the presence of the ETO zinc finger domain, which recruits corepressors, and could not be rescued by overexpression of co-repressors that normally enhance PLZF repression. AML-1/ETO also excluded PLZF from the nuclear matrix and reduced its ability to bind to its cognate DNA-binding site. Finally, ETO interacted with PLZF/RARα and enhanced its ability to repress through the RARE. These data show a link in the transcriptional pathways of M2 and M3 leukemia.

Recruitment of the nuclear receptor corepressor N-CoR by the TEL moiety of the childhood leukemia–associated TEL-AML1 oncoprotein

Blood ◽  
2000 ◽  
Vol 96 (7) ◽  
pp. 2557-2561 ◽  
Author(s):  
Fabien Guidez ◽  
Kevin Petrie ◽  
Anthony M. Ford ◽  
Huafeng Lu ◽  
Caroline A. Bennett ◽  
...  
Keyword(s):  
Nuclear Receptor ◽  
Transcriptional Repression ◽  
Childhood Leukemia ◽  
Target Genes ◽  
Lymphoblastic Leukemia ◽  
Chimeric Protein ◽  
Chromosomal Translocation ◽  
Corepressor Complex ◽  
Nuclear Receptor Corepressor ◽  
Frame Fusion

Abstract The t(12;21)(p13;q22) chromosomal translocation is the most frequent illegitimate gene recombination in a pediatric cancer and occurs in approximately 25% of common acute lymphoblastic leukemia (cALL) cases. This rearrangement results in the in frame fusion of the 5′-region of the ETS-related gene, TEL(ETV6), to almost the entire acute myeloid leukemia 1 (AML1) (also called CBFA2 orPEBP2AB1) locus and expression of the TEL-AML1 chimeric protein. Although AML1 stimulates transcription, TEL-AML1 functions as a repressor of some AML1 target genes. In contrast to the wild type AML1 protein, both TEL and TEL-AML1 interact with N-CoR, a component of the nuclear receptor corepressor complex with histone deacetylase activity. The interaction between TEL and N-CoR requires the central region of TEL, which is retained in TEL-AML1, and TEL lacking this domain is impaired in transcriptional repression. Taken together, our results suggest that TEL-AML1 may contribute to leukemogenesis by recruiting N-CoR to AML1 target genes and thus imposing an altered pattern of their expression.

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