Structural and functional properties of mSWI/SNF chromatin remodeling complexes revealed through single-cell perturbation and genomic profiling
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE200201 | GEO | 2023/04/05
REPOSITORIES: GEO
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Project description:Mammalian SWI/SNF (mSWI/SNF) ATP-dependent chromatin remodeling complexes are large, multisubunit molecular machines that play vital roles in regulating genomic architecture and are frequently disrupted in human cancer and developmental disorders. To date, the organization and pathway of assembly of these chromatin regulators remain unknown, presenting a major barrier to structural and functional determination. Here we elucidate the architecture and assembly pathway of three different classes of mammalian SWI/SNF complexes: canonical BAF, PBAF, and a newly defined complex, ncBAF, and define the requirement of each subunit for complex formation and stability. Using affinity purification of endogenous complexes from mammalian and Drosophila cells coupled with cross linking-mass spectrometry, we uncover three distinct and evolutionarily conserved modules, their organization, and the temporal incorporation of these modules into each complete mSWI/SNF complex class.
2018-10-18 | PXD010122 | Pride
Project description:Mammalian SWI/SNF (mSWI/SNF) ATP-dependent chromatin remodeling complexes are large, multisubunit molecular machines that play vital roles in regulating genomic architecture and are frequently disrupted in human cancer and developmental disorders. To date, the organization and pathway of assembly of these chromatin regulators remain unknown, presenting a major barrier to structural and functional determination. Here we elucidate the architecture and assembly pathway of three different classes of mammalian SWI/SNF complexes: canonical BAF, PBAF, and a newly defined complex, ncBAF, and define the requirement of each subunit for complex formation and stability. Using affinity purification of endogenous complexes from mammalian and Drosophila cells coupled with cross linking-mass spectrometry, we uncover three distinct and evolutionarily conserved modules, their organization, and the temporal incorporation of these modules into each complete mSWI/SNF complex class.
2018-10-18 | PXD010123 | Pride
Project description:Increased cortical size is essential to the enhanced intellectual capacity of primates during mammalian evolution. The mechanisms that control cortical size are largely unknown. Here, we show that mammalian BAF170, a subunit of the chromatin remodeling complex mSWI/SNF, is an intrinsic factor that controls cortical size. We find that the conditional deletion of BAF170 promotes indirect neurogenesis by increasing the pool of intermediate progenitors (IPs) and results in an enlarged cortex, whereas cortex-specific BAF170 over-expression results an opposing phenotype. Mechanistically, BAF170 competes with BAF155 subunit in the BAF complex, affecting the euchromatin structure and thereby modulating the binding efficiency of Pax6/REST-corepressor complex to Pax6 target genes that regulate the generation of IPs and late cortical progenitors. Our findings reveal a molecular mechanism mediated by the mSWI/SNF chromatin-remodeling complex that controls cortical architecture. Cortical gene expression is compared between three E12.5 mouse embryos with cortex-specific loss of BAF170 function and three littermate control embryos.
2013-05-02 | E-GEOD-45629 | biostudies-arrayexpress
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.
2021-04-01 | GSE162052 | GEO
Project description:Brg-or Brm-associated factor (BAF) complexes, is a 12 subunit complex which contains an ATPase subunit, Brg or Brm, that uses energy derived from ATP hydrolysis to disrupt histone:DNA contacts to catalyze transcriptional events such as promoting gene expression or repression. Genetic studies in mice demonstrated that BAF complexes are essential for early embryonic development and pluripotency. ES cells express distinctive compleses, termed esBAF complexes by the presence of BAF155, Brg, BAF60a. Purification of Brg and Brm-associated proteins reveals a new family of four stoichiometric subunits of mSWI/SNF or BAF complexes which was termed BAF45a, b, c, and d. The progenitors to both neurons and glia are maintained in a proliferative state by a specified SWI/SNF-like npBAF complex that contains both BAF45a and BAF53a. The transition from proliferative to neurogenic divisions requires the exchange of these subunites for the homologous BAF45b or BAF45c and BAF53b proteins. The function of BAF45d remwains unclear so far.At present, we found that the knockout of dpf2 in ES cells impared the differention of ES cells. We will identify the target genes of dpf2 by Chip-seq so that we could study how dpf2 affect the differentiation of ES cells into germ layers.Protocol: DNA was prepared from ES cells by standard ChIP method. This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/
2013-09-30 | E-ERAD-24 | biostudies-arrayexpress
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: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:Perturbations to mammalian SWI/SNF (mSWI/SNF) chromatin remodeling complexes have been widely implicated as driving events across cancers1. One such perturbation is the dual loss of the SMARCA4 and SMARCA2 ATPase subunits, which has recently been implicated in rare cancers such as small cell carcinoma of the ovary, hypercalcemic type (SCCOHT)2-5, SMARCA4-deficient thoracic sarcomas6 and dedifferentiated endometrial carcinomas7. The consequences of SMARCA4/2 dual loss on the biochemical composition of the complex, chromatin targeting and remodeling capabilities, and subcomplex identity (BAF vs. PBAF) in these cancers are unknown. Here, we leverage SCCOHT cell lines to identify an unexpected ATPase module of mSWI/SNF subunits. Using biochemical and genome-wide profiling assays, we found that the incorporation of the ATPase module is a critical step in the functional specification of BAF and PBAF subcomplexes. Furthermore, by utilizing ATPase mutant variants, we found that the ATPase module mediates two separate and concurrent mSWI/SNF targeting mechanisms, evenly split between catalytically-independent targeting to primed enhancers/promoters and catalytically-dependent targeting to de novo enhancers. Finally, by linking these distinct sites to separate tumor-suppressive gene expression programs across ovarian tissues , we clarify the mechanistic consequences of SMARCA4/2 loss dual loss in these rare tumors.
2019-03-11 | GSE117734 | GEO
Project description:Perturbations to mammalian SWI/SNF (mSWI/SNF) chromatin remodeling complexes have been widely implicated as driving events across cancers1. One such perturbation is the dual loss of the SMARCA4 and SMARCA2 ATPase subunits, which has recently been implicated in rare cancers such as small cell carcinoma of the ovary, hypercalcemic type (SCCOHT)2-5, SMARCA4-deficient thoracic sarcomas6 and dedifferentiated endometrial carcinomas7. The consequences of SMARCA4/2 dual loss on the biochemical composition of the complex, chromatin targeting and remodeling capabilities, and subcomplex identity (BAF vs. PBAF) in these cancers are unknown. Here, we leverage SCCOHT cell lines to identify an unexpected ATPase module of mSWI/SNF subunits. Using biochemical and genome-wide profiling assays, we found that the incorporation of the ATPase module is a critical step in the functional specification of BAF and PBAF subcomplexes. Furthermore, by utilizing ATPase mutant variants, we found that the ATPase module mediates two separate and concurrent mSWI/SNF targeting mechanisms, evenly split between catalytically-independent targeting to primed enhancers/promoters and catalytically-dependent targeting to de novo enhancers. Finally, by linking these distinct sites to separate tumor-suppressive gene expression programs across ovarian tissues , we clarify the mechanistic consequences of SMARCA4/2 loss dual loss in these rare tumors.
2019-03-11 | GSE117311 | GEO
Project description:Perturbations to mammalian SWI/SNF (mSWI/SNF) chromatin remodeling complexes have been widely implicated as driving events across cancers1. One such perturbation is the dual loss of the SMARCA4 and SMARCA2 ATPase subunits, which has recently been implicated in rare cancers such as small cell carcinoma of the ovary, hypercalcemic type (SCCOHT)2-5, SMARCA4-deficient thoracic sarcomas6 and dedifferentiated endometrial carcinomas7. The consequences of SMARCA4/2 dual loss on the biochemical composition of the complex, chromatin targeting and remodeling capabilities, and subcomplex identity (BAF vs. PBAF) in these cancers are unknown. Here, we leverage SCCOHT cell lines to identify an unexpected ATPase module of mSWI/SNF subunits. Using biochemical and genome-wide profiling assays, we found that the incorporation of the ATPase module is a critical step in the functional specification of BAF and PBAF subcomplexes. Furthermore, by utilizing ATPase mutant variants, we found that the ATPase module mediates two separate and concurrent mSWI/SNF targeting mechanisms, evenly split between catalytically-independent targeting to primed enhancers/promoters and catalytically-dependent targeting to de novo enhancers. Finally, by linking these distinct sites to separate tumor-suppressive gene expression programs across ovarian tissues , we clarify the mechanistic consequences of SMARCA4/2 loss dual loss in these rare tumors.
2019-03-11 | GSE117301 | GEO