scholarly journals Functional Coupling between HIV-1 Integrase and the SWI/SNF Chromatin Remodeling Complex for Efficient in vitro Integration into Stable Nucleosomes

2011 ◽  
Vol 7 (2) ◽  
pp. e1001280 ◽  
Author(s):  
Paul Lesbats ◽  
Yair Botbol ◽  
Guillaume Chevereau ◽  
Cédric Vaillant ◽  
Christina Calmels ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Functional Coupling ◽  
Chromatin Remodeling Complex ◽  
Hiv 1

scholarly journals An In Vitro System Recapitulates Chromatin Remodeling at the PHO5 Promoter

1999 ◽  
Vol 19 (4) ◽  
pp. 2817-2827 ◽  
Author(s):  
Elizabeth S. Haswell ◽  
Erin K. O’Shea
Keyword(s):  
Chromatin Remodeling ◽  
Chromatin Structure ◽  
Nuclear Extract ◽  
In Vitro System ◽  
Chromatin Remodeling Complex ◽  
Promoter Dna ◽  
Pho5 Promoter

ABSTRACT The Saccharomyces cerevisiae gene PHO5 is an excellent system with which to study regulated changes in chromatin structure. The PHO5 promoter is packaged into four positioned nucleosomes under repressing conditions; upon induction, the structure of these nucleosomes is altered such that the promoter DNA becomes accessible to nucleases. We report here the development and characterization of an in vitro system in which partially purified PHO5 minichromosomes undergo promoter chromatin remodeling. Several hallmarks of thePHO5 chromatin transition in vivo were reproduced in this system. Chromatin remodeling of PHO5minichromosomes required the transcription factors Pho4 and Pho2, was localized to the promoter region of PHO5, and was independent of the chromatin-remodeling complex Swi-Snf. In vitro chromatin remodeling also required the addition of fractionated nuclear extract and hydrolyzable ATP. This in vitro system should serve as a useful tool for identifying the components required for this reaction and for elucidating the mechanism by which the PHO5promoter chromatin structure is changed.

scholarly journals BAF60a Mediates Critical Interactions between Nuclear Receptors and the BRG1 Chromatin-Remodeling Complex for Transactivation

2003 ◽  
Vol 23 (17) ◽  
pp. 6210-6220 ◽  
Author(s):  
Pei-Wen Hsiao ◽  
Christy J. Fryer ◽  
Kevin W. Trotter ◽  
Weidong Wang ◽  
Trevor K. Archer
Keyword(s):  
Nuclear Receptors ◽  
Chromatin Remodeling ◽  
Molecular Mechanisms ◽  
Hormone Receptors ◽  
Nuclear Receptor Coactivators ◽  
Chromatin Remodeling Complex ◽  
Truncation Mutant ◽  
Promoter Recruitment

ABSTRACT Nuclear hormone receptors are ligand-dependent transcriptional regulators that modulate chromatin structure. However, the precise molecular mechanisms by which receptors recruit chromatin-remodeling activity are not fully elucidated. We show that in the absence of its ligand-binding domain, the glucocorticoid receptor (GR) is able to interact with both nuclear receptor coactivators and the BRG1 chromatin-remodeling complex in vivo. Individually, the GR makes direct interactions with BRG1-associated factor 60a (BAF60a) and BAF57, but not with BRG1, BAF155, or BAF170. Further, BAF60a possesses at least two interaction surfaces, one for GR and BRG1 and a second for BAF155 and BAF170. A GR mutant, GR(R488Q), that fails to interact with BAF60a in vitro has reduced chromatin-remodeling activity and reduced transcriptional activity from the promoter assembled as chromatin in vivo. Stable expression of a BAF60a truncation mutant, BAF60a4-140, caused chromatin-specific loss of GR functions in vivo. In the presence of the BAF60a mutant, the GR fails to interact with the BRG1 complex and consequently is also deficient in its ability to activate transcription from chromatin. Thus, in addition to previously identified BAF250, BAF60a may provide another critical and direct link between nuclear receptors and the BRG1 complex that is required for promoter recruitment and subsequent chromatin remodeling.

scholarly journals Targeting the Bromodomain of BRG-1/BRM Subunit of the SWI/SNF Complex Increases the Anticancer Activity of Temozolomide in Glioblastoma

2021 ◽  
Vol 14 (9) ◽  
pp. 904
Author(s):  
Chuanhe Yang ◽  
Yinan Wang ◽  
Michelle M. Sims ◽  
Yali He ◽  
Duane D. Miller ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Small Molecule ◽  
Therapeutic Potential ◽  
Standard Of Care ◽  
Anticancer Effect ◽  
Altered Gene Expression ◽  
Chromatin Remodeling Complex ◽  
Novel Targets ◽  
Altered Gene

Glioblastoma (GBM) is a deadly and incurable brain cancer with limited therapeutic options. PFI-3 is a small-molecule bromodomain (BRD) inhibitor of the BRM/BRG1 subunits of the SWI/SNF chromatin remodeling complex. The objective of this study is to determine the efficacy of PFI-3 as a potential GBM therapy. We report that PFI-3 binds to these BRDs when expressed in GBM cells. PFI-3 markedly enhanced the antiproliferative and cell death-inducing effects of temozolomide (TMZ) in TMZ-sensitive GBM cells as well as overcame the chemoresistance of highly TMZ-resistant GBM cells. PFI-3 also altered gene expression in GBM and enhanced the basal and interferon-induced expression of a subset of interferon-responsive genes. Besides the effects of PFI-3 on GBM cells in vitro, we found that PFI-3 markedly potentiated the anticancer effect of TMZ in an intracranial GBM animal model, resulting in a marked increase in survival of animals bearing GBM tumors. Taken together, we identified the BRG1 and BRM subunits of SWI/SNF as novel targets in GBM and revealed the therapeutic potential of applying small molecule inhibitors of SWI/SNF to improve the clinical outcome in GBM using standard-of-care chemotherapy.

scholarly journals Requirement for SWI/SNF chromatin-remodeling complex in Tat-mediated activation of the HIV-1 promoter

2006 ◽  
Vol 25 (8) ◽  
pp. 1690-1699 ◽  
Author(s):  
Céline Tréand ◽  
Isaure du Chéné ◽  
Vanessa Brès ◽  
Rosemary Kiernan ◽  
Richard Benarous ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Chromatin Remodeling Complex ◽  
Hiv 1

scholarly journals Spliceosomal Disruption of the Non-Canonical SWI/SNF Chromatin Remodeling Complex in SF3B1 Mutant Leukemias

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 637-637
Author(s):  
Daichi Inoue ◽  
Chew Guo-Liang ◽  
Bo Liu ◽  
Stanley C Lee ◽  
Brittany C Michel ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Dependent Manner ◽  
Prior Work ◽  
Aberrant Splicing ◽  
Atpase Subunit ◽  
Exon Inclusion ◽  
Chromatin Remodeling Complex ◽  
Mutational Hotspots

Mutations in the RNA splicing factor SF3B1 are common in MDS and other myeloid malignancies. SF3B1 mutations promote expression of mRNAs that use an aberrant, intron proximal 3' splice site (ss). Despite the consistency of this finding, linking aberrant splicing changes to disease pathogenesis has been a challenge. Here we identify aberrant splicing and downregulated expression of BRD9, a member of the recently described ATP-dependent non-canonical BAF (ncBAF) chromatin remodeling complex, across SF3B1 mutant leukemias. In so doing, we identify a novel role for altered ncBAF function in hematopoiesis and MDS. To systematically identify functionally important aberrant splicing events created by mutant SF3B1, we integrated differential splicing events in SF3B1 mutant versus wild-type MDS with a positive enrichment CRISPR screen mimicking splicing changes induced by mutant SF3B1 that promote NMD (non-sense mediated mRNA decay). We tested whether loss of any gene functionally inactivated by SF3B1 mutations promoted transformation of Ba/F3 and 32D cells. This identified a specific NMD-inducing aberrant splicing event in BRD9 which promoted cytokine independence (Fig. A) and exhibited striking aberrant splicing across CLL and MDS and across all mutational hotspots in SF3B1 (Fig. B). SF3B1 mutations cause exonization of a normally intronic sequence in BRD9, resulting in inclusion of a poison exon that interrupts BRD9's reading frame (Fig. C) and reduced BRD9 mRNA and protein expression through NMD (Fig. D). We confirmed that mutant SF3B1 suppressed full-length BRD9 levels without generating truncated BRD9 protein. Loss of BRD9 impaired ncBAF complex formation as indicated by abolished interaction between the ncBAF specific component GLTSCR1 and the ATPase subunit BRG1 upon chemical or spliceosomal BRD9 ablation (Fig. D). Given that prior work has linked mutant SF3B1 to use of aberrant 3' ss, we sought to understand the molecular basis for aberrant exon inclusion in BRD9 by mutant SF3B1. Lariat sequencing of SF3B1 mutant versus WT K562 cells and BRD9 minigene analyses identified use of a deep intronic branchpoint adenosine by mutant SF3B1 to promote BRD9 poison exon inclusion (Fig. E). The data above suggest a role for BRD9 downregulation in SF3B1 mutant leukemia. While prior work indicated that BRD9 is required in MLL-rearranged AML (Hohmman et al. Nature Chemical Biology 2016), the role of BRD9 in normal hematopoiesis or other subtypes of myeloid neoplasms has not been evaluated. Genetic downregulation of BRD9 in normal human hematopoietic progenitors from cord blood promoted myelopoiesis while impairing megakaryopoiesis. Interestingly and unexpectedly, BRD9 loss in CD34+ cells promoted terminal erythroid differentiation in vitro. To further evaluate BRD9's role in hematopoiesis in vivo, we also generated mice with inducible knockout of the bromodomain of BRD9 (required for BRD9 function) and generation of a frameshift transcript resulting in reduced Brd9 expression (Fig. F). Loss of Brd9 resulted in macrocytosis with bone marrow erythroid dysplasia in a dosage-dependent manner, along with impaired lymphopoiesis and myeloid skewing. Moreover, competitive transplantation of hematopoietic precursors from these mice revealed that ablation of Brd9 function impaired lymphoid reconstitution while promoting advantage of myeloid cells and hematopoietic precursors (Fig. G-I). In myeloid leukemia cells, introduction of SF3B1K700E or downregulation of BRD9 resulted in increased chromatin accessibility at promoters with a significant overlap in commonly upregulated genes. This finding suggests shared epigenetic effects of SF3B1K700E mutations and BRD9 loss (Fig. J). These data identify aberrant splicing of BRD9 across the spectrum of SF3B1 mutant cancers and identify a novel role for downregulation of ncBAF function in MDS pathogenesis. Consistent with human genetic data, genetic ablation of BRD9 function in mouse and human hematopoietic cells resulted in myeloid skewing and dyserythropoiesis. These data suggest that targeted correction of aberrant BRD9 splicing might serve as a novel therapeutic approach for SF3B1-mutant leukemias. Of note, treatment with drugs impairing the binding of mutant SF3B1 to RNA resulted in a dose-dependent rescue of aberrant BRD9 splicing in vitro (Fig. K) and in treatment of an SF3B1 mutant AML patient-derived xenograft in vivo. Figure Disclosures Kadoch: Foghorn Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

scholarly journals The LRS and SIN Domains: Two Structurally Equivalent but Functionally Distinct Nucleosomal Surfaces Required for Transcriptional Silencing

2006 ◽  
Vol 26 (23) ◽  
pp. 9045-9059 ◽  
Author(s):  
Christopher J. Fry ◽  
Anne Norris ◽  
Michael Cosgrove ◽  
Jef D. Boeke ◽  
Craig L. Peterson
Keyword(s):  
Gene Silencing ◽  
Chromatin Remodeling ◽  
Transcriptional Repression ◽  
Heterochromatin Formation ◽  
Chromatin Remodeling Complex ◽  
Binding Surface ◽  
Chromatin Folding ◽  
L1 And L2

ABSTRACT Genetic experiments have identified two structurally similar nucleosomal domains, SIN and LRS, required for transcriptional repression at genes regulated by the SWI/SNF chromatin remodeling complex or for heterochromatic gene silencing, respectively. Each of these domains consists of histone H3 and H4 L1 and L2 loops that form a DNA-binding surface at either superhelical location (SHL) ±2.5 (LRS) or SHL ±0.5 (SIN). Here we show that alterations in the LRS domain do not result in Sin− phenotypes, nor does disruption of the SIN domain lead to loss of ribosomal DNA heterochromatic gene silencing (Lrs− phenotype). Furthermore, whereas disruption of the SIN domain eliminates intramolecular folding of nucleosomal arrays in vitro, alterations in the LRS domain have no effect on chromatin folding in vitro. In contrast to these dissimilarities, we find that the SIN and LRS domains are both required for recruitment of Sir2p and Sir4p to telomeric and silent mating type loci, suggesting that both surfaces can contribute to heterochromatin formation. Our study shows that structurally similar nucleosomal surfaces provide distinct functionalities in vivo and in vitro.

scholarly journals Mammalian SWI/SNF-A Subunit BAF250/ARID1 Is an E3 Ubiquitin Ligase That Targets Histone H2B

2010 ◽  
Vol 30 (7) ◽  
pp. 1673-1688 ◽  
Author(s):  
Xuan Shirley Li ◽  
Patrick Trojer ◽  
Tatsushi Matsumura ◽  
Jessica E. Treisman ◽  
Naoko Tanese
Keyword(s):  
Chromatin Remodeling ◽  
Ubiquitin Ligase ◽  
Mammalian Cells ◽  
E3 Ubiquitin Ligase ◽  
Dependent Manner ◽  
Histone H2b ◽  
Enzymatic Function ◽  
Chromatin Remodeling Complex

ABSTRACT The mammalian SWI/SNF chromatin-remodeling complex facilitates DNA access by transcription factors and the transcription machinery. The characteristic member of human SWI/SNF-A is BAF250/ARID1, of which there are two isoforms, BAF250a/ARID1a and BAF250b/ARID1b. Here we report that BAF250b complexes purified from mammalian cells contain elongin C (Elo C), a BC box binding component of an E3 ubiquitin ligase. BAF250b was found to have a BC box motif, associate with Elo C in a BC box-dependent manner, and, together with cullin 2 and Roc1, assemble into an E3 ubiquitin ligase. The BAF250b BC box mutant protein was unstable in vivo and was autoubiquitinated in a manner similar to that for the VHL BC box mutants. The discovery that BAF250 is part of an E3 ubiquitin ligase adds an enzymatic function to the chromatin-remodeling complex SWI/SNF-A. The immunopurified BAF250b E3 ubiquitin ligase was found to target histone H2B at lysine 120 for monoubiquitination in vitro. To date, all H2B monoubiquitination was attributed to the human homolog of yeast Bre1 (RNF20/40). Mutation of Drosophila osa, the homolog of BAF250, or depletion of BAF250 by RNA interference (RNAi) in cultured human cells resulted in global decreases in monoubiquitinated H2B, implicating BAF250 in the cross talk of histone modifications.

scholarly journals HIV-1 Vpr Induces the Degradation of ZIP and sZIP, Adaptors of the NuRD Chromatin Remodeling Complex, by Hijacking DCAF1/VprBP

PLoS ONE ◽  
2013 ◽  
Vol 8 (10) ◽  
pp. e77320 ◽  
Author(s):  
Claire Maudet ◽  
Adèle Sourisce ◽  
Loïc Dragin ◽  
Hichem Lahouassa ◽  
Jean-Christophe Rain ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Chromatin Remodeling Complex ◽  
Hiv 1

scholarly journals The High-Mobility-Group Box Protein SSRP1/T160 Is Essential for Cell Viability in Day 3.5 Mouse Embryos

2003 ◽  
Vol 23 (15) ◽  
pp. 5301-5307 ◽  
Author(s):  
Shang Cao ◽  
Heather Bendall ◽  
Geoffrey G. Hicks ◽  
Abudi Nashabi ◽  
Hitoshi Sakano ◽  
...  
Keyword(s):  
Cell Viability ◽  
Chromatin Remodeling ◽  
Germ Line ◽  
Embryonic Stem ◽  
High Mobility ◽  
High Mobility Group ◽  
Murine Embryonic Stem Cells ◽  
Chromatin Remodeling Complex ◽  
Independent Functions

ABSTRACT The high-mobility-group (HMG) SSRP1 protein is a member of a conserved chromatin-remodeling complex (FACT/DUF/CP) implicated in DNA replication, basal and regulated transcription, and DNA repair. To assist in the functional analysis of SSRP1, the Ssrp1 gene was targeted in murine embryonic stem cells, and the mutation was introduced into the germ line. Embryos homozygous for the targeted allele die soon after implantation, and preimplantation blastocysts are defective for cell outgrowth and/or survival in vitro. The Ssrp1 mutation was also crossed into a p53 null background without affecting growth and/or survival defects caused by loss of Ssrp1 function. Thus, Ssrp1 appears to encode nonredundant and p53-independent functions that are essential for cell viability.

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