Loss of BAF (mSWI/SNF) Chromatin-remodeling ATPase Brg1 causes multiple malformations of cortical development in mice
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE201990 | GEO | 2023/12/31
REPOSITORIES: GEO
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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: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: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: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.
2010-12-22 | GSE26191 | GEO
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.
2013-03-30 | GSE45625 | GEO
Project description:Malformations of cortical development (MCD) are present in up to 40% of children with pharmacoresistant epilepsy. Although epilepsy surgery can be successful in a subset of children, not all forms of MCD are operable. Understanding the genetic and neurobiological mechanisms underlying MCD and MCD-related epilepsy are necessary for the development of novel anti-epilepsy drugs. The tish (telencephalic internal structural heterotopia) rat is a unique model of MCD and spontaneous seizures, but the underlying genetic mutation has been, heretofore, unknown. DNA and RNA-sequencing revealed that a deletion encompassing a previously unannotated exon markedly diminished EML1 transcript and protein abundance in the tish brain. Developmental electrographic characterization of the tish rat demonstrated spontaneous spike-wave discharge (SWD) bursts beginning as early as postnatal day (P) 17. A dihybrid cross demonstrated that the mutantEml1 allele segregates with the observed dysplastic cortex and SWD bursts in monogenic autosomal recessive frequencies. Our data link the development of the bilateral, heterotopic dysplastic cortex of the tish rat to a mutation in Eml1 and provide a novel rat model of MCD.
2020-03-28 | GSE147663 | GEO
Project description:The SWI/SNF complex was the first chromatin remodeling machinery discovered. Although it has been extensively investigated, numerous aspects of its regulation and activity are still poorly understood, especially in higher eukaryotes. In mammals, there is not a single SWI/SNF complex (also called BRM or BRG1 associated factors, BAF, complex) but rather a polymorphic family of complexes, with three main subtypes called canonical BAF (cBAF), polybromo-associated BAF (PBAF), and non-canonical BAF (ncBAF), with relatively different specificities. The enzymatic motors of the complexes are two mutually exclusive ATPases of the SNF2 family called BRAHMA (BRM, also called SMARCA2) and BRAHMA RELATED GENE 1 (BRG1, also called SMARCA4). Recently, an specific inhibitor of BRM and BRG1 ATPase activity, called BRM014, has been developed. We have extensively investigated the effect of BRM014 on the transcriptome and the chromatin landscape of non-tumoral normal murine mammary (NMuMG) epithelial cells.
2024-03-08 | GSE249211 | GEO
Project description:The SWI/SNF complex was the first chromatin remodeling machinery discovered. Although it has been extensively investigated, numerous aspects of its regulation and activity are still poorly understood, especially in higher eukaryotes. In mammals, there is not a single SWI/SNF complex (also called BRM or BRG1 associated factors, BAF, complex) but rather a polymorphic family of complexes, with three main subtypes called canonical BAF (cBAF), polybromo-associated BAF (PBAF), and non-canonical BAF (ncBAF), with relatively different specificities. The enzymatic motors of the complexes are two mutually exclusive ATPases of the SNF2 family called BRAHMA (BRM, also called SMARCA2) and BRAHMA RELATED GENE 1 (BRG1, also called SMARCA4). Recently, an specific inhibitor of BRM and BRG1 ATPase activity, called BRM014, has been developed. We have extensively investigated the effect of BRM014 on the transcriptome and the chromatin landscape of non-tumoral normal murine mammary (NMuMG) epithelial cells.
2024-03-08 | GSE226953 | GEO
Project description:The SWI/SNF complex was the first chromatin remodeling machinery discovered. Although it has been extensively investigated, numerous aspects of its regulation and activity are still poorly understood, especially in higher eukaryotes. In mammals, there is not a single SWI/SNF complex (also called BRM or BRG1 associated factors, BAF, complex) but rather a polymorphic family of complexes, with three main subtypes called canonical BAF (cBAF), polybromo-associated BAF (PBAF), and non-canonical BAF (ncBAF), with relatively different specificities. The enzymatic motors of the complexes are two mutually exclusive ATPases of the SNF2 family called BRAHMA (BRM, also called SMARCA2) and BRAHMA RELATED GENE 1 (BRG1, also called SMARCA4). Recently, an specific inhibitor of BRM and BRG1 ATPase activity, called BRM014, has been developed. We have extensively investigated the effect of BRM014 on the transcriptome and the chromatin landscape of non-tumoral normal murine mammary (NMuMG) epithelial cells.
2024-03-08 | GSE226950 | GEO