Chromatin Remodeling Complex Dosage Modulates Transcription Factor Function in Heart Development
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE26191 | GEO | 2010/12/22
SECONDARY ACCESSION(S): PRJNA135019
REPOSITORIES: GEO
Similar Datasets
Project description:Dominant mutations in cardiac transcription factor genes cause human inherited congenital heart defects (CHDs), but their molecular basis is not understood. Transcription factors and Brg1/Brm-associated factor (BAF) chromatin remodeling complex interactions suggest potential mechanisms, but the role of BAF complexes in cardiogenesis is not known. Here we show that dosage of Brg1 is critical for mouse and zebrafish cardiogenesis. Disrupting the balance between Brg1 and disease-causing cardiac transcription factors, including Tbx5, Tbx20, and Nkx2-5, causes severe cardiac anomalies, revealing an essential allelic balance between Brg1 and these cardiac transcription factor genes. This suggests that relative levels of transcription factors and BAF complexes are important for heart development, which is supported by reduced occupancy of Brg1 at cardiac genes in Tbx5 haploinsufficient hearts. Our results reveal complex dosage-sensitive interdependence between transcription factors and BAF complexes, providing a potential mechanism underlying transcription factor haploinsufficiency, with implications for multigenic inheritance of CHDs. We performed transcriptional profiling of E11.5 hearts from mice heterozygous for deletions of Brg1, Tbx5, or Nkx2-5, and mice that were compound heterozygotes for Brg1 and each transcription factor gene (Tbx5 and Nkx2-5).
2010-12-22 | E-GEOD-26191 | biostudies-arrayexpress
Project description:Chromatin remodeling complexes instruct cellular differentiation and lineage specific transcription. The BRG1/BRM associated factor (BAF) complexes are important for several aspects of differentiation. We show that the catalytic subunit Brg1 has a specific role in cardiac precursors (CPs) to initiate cardiac gene expression programs and repress non-cardiac expression. Using immunoprecipitation immunopurification with mass spectrometry we determined the dynamic composition of BAF complexes during mammalian cardiac differentiation, identifying several cell-type specific subunits. We focused on the CP- and cardiomyocytes (CM)-enriched subunits BAF60c (SMARCD3) and BAF170 (SMARCC2). Baf60c and Baf170 co-regulate gene expression with Brg1 in CPs, and in CMs their loss results in broadly deregulated cardiac gene expression. BRG1, BAF60, and BAF170 modulate chromatin accessibility, to either promote accessibility at activated genes, while closing up chromatin at repressed genes. BAF60c and BAF170 are required for proper BAF complex composition, and BAF170 loss leads to retention of BRG1 at CP-specific enhancers. Thus, dynamic interdependent BAF complex subunit assembly modulates chromatin states and thereby participates in directing temporal gene expression programs in cardiogenesis.
2019-11-13 | PXD012721 | Pride
Project description:Congenital Heart Disease (CHD) accounts for 1% of birth defects, and while large-scale genetic studies have uncovered genes associated with CHDs, identifying causal mutations remains a challenge. We hypothesized that genetic determinants for CHDs could be found in the protein interactomes of GATA4 and TBX5, two cardiac transcription factors (TFs) associated with CHDs. Defining their interactomes in human cardiac progenitors via affinity purification-mass spectrometry and integrating the results with genetic data from the Pediatric Cardiac Genomic Consortium (PCGC) revealed an enrichment of de novo variants among proteins that interact with GATA4 or TBX5. A consolidative score designed to prioritize TF interactome members based on distinctive variant, gene and proband features identified numerous likely CHD-causing genes, including the epigenetic reader GLYR1. GLYR1 and GATA4 widely co-occupied cardiac developmental genes resulting in co-activation and the GLYR1 variant associated with CHD disrupted interaction with GATA4. This integrative proteomic and genetic approach provides a framework for prioritizing and interrogating the contribution of genetic variants in CHD and can be extended to other genetic diseases.
2022-07-05 | PXD022091 | Pride
Project description:Differentiation proceeds along a continuum of increasingly fate-restricted intermediates, referred to as canalization. Canalization is essential for stabilizing cell fate, but mechanisms underlying robust canalization are unclear. Here we show that the BRG1/BRM-associated factor (BAF) chromatin remodeling complex ATPase gene Brm safeguards cell identity during directed cardiogenesis of mouse embryonic stem cells. Despite establishment of well-differentiated precardiac mesoderm, Brm-null cells predominantly became neural precursors, violating germ layer assignment. Trajectory inference showed sudden acquisition of non-mesodermal identity in Brm-null cells, consistent with a new transition state referred to as a saddle-node bifurcation. Mechanistically, loss of Brm prevented de novo accessibility of cardiac enhancers while increasing expression of neurogenic factor POU3F1, preventing expression of neural suppressor REST, and disrupting composition of BRG1 complexes. Brm mutant identity switch was overcome by increasing BMP4 levels during mesoderm induction. Mathematical modeling supports all our observations. In the mouse embryo, Brm deletion exacerbated mesoderm-deleted Brg1 mutant phenotypes, severely compromising cardiogenesis, unmasking an in vivo role for Brm. Our results reveal Brm as a compensable safeguard of the fidelity of mesoderm chromatin states, and support a model in which developmental canalization is not a rigid irreversible path, but a highly plastic trajectory.
2021-11-03 | PXD026638 | Pride
Project description:Recent exon sequencing studies of human tumors have revealed that subunits of mSWI/SNF or BAF complexes are mutated in more than 20% of human malignancies, yet the mechanisms involved in tumor suppression is unclear. BAF chromatin remodeling complexes are polymorphic assemblies that use energy provided by ATP hydrolysis to regulate transcription through the control of chromatin structure and the placement of Polycomb (PcG) across the genome. Several proteins dedicated to this large multi-subunit complex, including SMARCA4 (BRG1) and BAF250A (ARID1A), are mutated at frequencies similar to that of many recognized tumor suppressors. In particular, the core ATPase BRG1 is mutated in 5-10% of childhood medulloblastoma (MB) and greater than 15% of Burkitt's Lymphoma (BL). Here we find a novel function of BAF complexes in decatenating newly replicated sister chromatids, which is necessary for proper chromosome segregation during mitosis. We find that deletion of Brg1, as well as the expression of Brg1 point mutants identified in human tumors leads to anaphase bridge formation (sister chromatids linked by catenated strands of DNA), and a G2/M phase block characteristic of the decatenation checkpoint. Endogenous BAF complexes directly interact with endogenous TopoIIα through BAF250a and are required for TopoIIα binding to about 12,000 sites over the genome. Our results indicate that TopoIIα’s chromatin binding is dependent on the ATPase activity of Brg1, which is compromised in oncogenic Brg1 mutants. These studies indicate that the ability of TopoIIα to prevent DNA entanglement at mitosis requires BAF complexes and suggest that this activity contributes to the role of BAF subunits as tumor suppressors. Examination of sites of TopoIIa activity in WT and Brg1-/- ES cells as defined by TopoIIa-DNA covalent adducts formed in the presence of etoposide
2013-03-30 | E-GEOD-45625 | biostudies-arrayexpress
Project description:Enhancers of transcription activate transcription via binding of sequence-specific transcription factors to their target sites in chromatin. In this report, we identify GATA1-bound enhancers genome-wide and find a global reorganization of the nucleosomes at these enhancers during differentiation of hematopoietic stem cells (HSCs) to erythrocytes. We show that the catalytic subunit BRG1 of BAF complexes localizes to these enhancers during differentiation and generates a longer nucleosome repeat length surrounding the GATA1 sites by shifting the flanking nucleosomes away. Intriguing, we find that the nucleosome shifting specifically facilitates binding of TAL1 but not GATA1, which subsequently activates transcription of target genes. Human hematopoietic stem cells (referred as CD34+ cells) were differentiated into erythroid lineage expressing the cell surface marker CD36 (referred as CD36+ cells). To study the function of ATP-dependent chromatin remodeling BAF complexes in the establishment of erythroid specific enhancers during differentiation, we mapped the genome-wide binding sites of GATA1 and TAL1, the key transcription regulators of erythroid differentiation, in CD36+ cells, then determined the genomic positions of the catalytic subunit BRG1 of the BAF complexes and the nucleosome landscapes, by ChIP-Seq and Mnase-Seq, respectively, for both HSCs and the differentiated cells. We compared changes in nucleosome landscapes with BRG1 binding at GATA1 and TAL1 binding sites and found that BRG1 binding is correlated with nucleosome shifting away from the binding sites, which is critical for TAL1 binding. To confirm that BRG1 is responsible for the nucleosome shift, we knocked down BRG1 in CD36+ cells and analyzed the nucleosome changes in the knockdown cells. The data indicated that inhibition of BRG1 caused a nucleosome shift towards the GATA1 or TAL1 sites, indicating that BRG1 is indeed responsible for the observed nucleosome shift.
2011-07-01 | E-GEOD-26501 | biostudies-arrayexpress
Project description:Congenital Heart Disease (CHD) is present in 1% of live births, and while large-scale genetic studies have uncovered genes associated with CHDs, identifying causal mutations remains a challenge. We hypothesized that genetic determinants for CHDs could be found in the protein interactomes of GATA4 and TBX5, two cardiac transcription factors (TFs) that cause CHDs. Defining their interactomes in human cardiac progenitors via affinity purification-mass spectrometry and integrating the results with genetic data from the Pediatric Cardiac Genomic Consortium (PCGC) revealed an enrichment of de novo variants among proteins that interact with GATA4 or TBX5. A consolidative score designed to prioritize TF interactome members based on distinctive variant, gene, and proband features identified numerous likely CHD-causing genes, including the epigenetic reader GLYR1. GLYR1 and GATA4 widely co-occupied cardiac developmental genes, resulting in co-activation, and the GLYR1 variant associated with CHD disrupted interaction with GATA4. This integrative proteomic and genetic approach provides a framework for prioritizing and interrogating the contribution of genetic variants in CHD and can be extended to other genetic diseases.
2022-02-18 | GSE159411 | GEO
Project description:Rhabdomyosarcoma (RMS) is a highly malignant pediatric cancer of skeletal muscle lineage. The aggressive alveolar subtype is commonly characterized by t(2;13) or t(1;13) translocations with the expression of PAX3- or PAX7-FOXO1 fusion transcription factors respectively and is known as fusion positive RMS (FP-RMS). FP-RMS tumors rely on the fusion gene to maintain their proliferative state while avoiding terminal differentiation program. Since disruptions of normal development are likely governed by epigenetic changes in these low-mutational-burden tumors, we investigated the contributions of chromatin regulatory complexes to RMS tumor maintenance. We demonstrate the essentiality of the mSWI/SNF ATPase BRG1 for FP-RMS proliferation and discover that RMS significantly overexpress SMARCA4 (encoding BRG1) compared to skeletal muscle. We define the mSWI/SNF subunit repertoire in FP-RMS and provide evidence for the assembly of multiple mSWI/SNF complexes including canonical BAF, PBAF and non-canonical (nc)BAF in FP-RMS. Proteomic studies suggest proximity between PAX3-FOXO1 and BAF complexes, which was further supported by genome-wide binding profiles revealing enhancer colocalization of BAF with FP-RMS core regulatory transcription factors. We report that mSWI/SNF complexes act as sensors of chromatin state, which are recruited to sites of de novo histone acetylation. Phenotypically, interference with mSWI/SNF complex function induces transcriptional activation of the skeletal muscle differentiation program associated with MYCN enhancer invasion at myogenic target genes. Finally, BRG1 targeting compounds reproduce the effects of genetic ablation. We conclude that inhibition of BRG1 overcomes the differentiation blockade of FP-RMS cells and may provide a therapeutic strategy for treating this lethal childhood tumor.
2020-11-20 | MSV000086494 | MassIVE
Project description:We showed that topoisomerase II synergizes with BAF (mSWI/SNF) ATP-dependent chromatin remodeling complexes genome-wide to resolve facultative heterochromatin to accessible chromatin. To study the consequences of this on transcription factors, we performed MNase-seq on light digest of native chromatin in Brg1 conditional knockout embryonic stem (ES) cells. We found that spacing of nucleosomes flanking pluripotency factor binding sites specifically partially collapsed upon Brg1 deletion, indicating that pluripotency factor binding is likely lost.
2017-03-01 | GSE94040 | GEO
Project description:Cell fate decisions are achieved with gene expression changes driven by lineage-specific transcription factors (TFs). These TFs depend on chromatin remodelers including the BAF complex to activate target genes. BAF complex subunits are essential for development and frequently mutated in cancer. Thus, interrogating how BAF complexes contribute to cell fate decisions is critical for human health. We examined the requirement for the catalytic BAF subunit BRG1 in neural progenitor cell (NPC) specification from human embryonic stem cells. During the earliest stages of differentiation, BRG1 was required to establish chromatin accessibility at neuroectoderm-specific enhancers. BRG1 depletion resulted in abnormal NPC populations that differentially expressed neuroectodermal TFs, were more prone to neuronal differentiation, and precociously formed neural crest lineages. These findings demonstrate that BRG1 mediates NPC specification by ensuring proper expression of lineage-specific TFs and appropriate activation of their transcriptional programs.
2024-03-01 | GSE235534 | GEO