Spliceosomal disruption of the non-canonical BAF complex in cancer
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ABSTRACT:
PROVIDER: PRJNA513262 | ENA |
REPOSITORIES: ENA
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Project description:SF3B1 is the most commonly mutated RNA splicing factor in cancer, but the mechanisms by which SF3B1 mutations promote malignancy are poorly understood. Here, we integrated pan-cancer RNA sequencing to identify mutant SF3B1-dependent aberrant splicing with a positive enrichment CRISPR screen to prioritize splicing alterations that functionally promote tumorigenesis. We identify that diverse, recurrent SF3B1 mutations converge on repression of BRD9, a core component of the recently described non-canonical BAF (ncBAF) complex. Mutant SF3B1 recognizes an aberrant deep intronic branchpoint within BRD9, thereby inducing inclusion of an endogenous retrovirus-derived poison exon and BRD9 mRNA degradation. BRD9 depletion causes loss of ncBAF at CTCF-bound loci and promotes melanomagenesis. We demonstrate that BRD9 is a potent tumor suppressor in uveal melanoma, such that correcting BRD9 mis-splicing in SF3B1-mutant cell lines and patient-derived melanoma xenografts with antisense oligonucleotides (ASOs) or by directly targeting its poison exon with CRISPR-directed mutagenesis profoundly suppresses tumor growth. Our results implicate disruption of ncBAF in the diverse malignancies characterized by SF3B1 mutations, identify a single aberrant splicing event which functionally contributes to the pathogenesis of SF3B1-mutant cancers, and suggest a mechanism-based therapeutic for these malignancies.
2019-06-19 | GSE124720 | GEO
Project description:SF3B1 is the most commonly mutated RNA splicing factor in cancer1-4, but the mechanisms by which SF3B1 mutations promote malignancy are poorly understood. Here we integrated pan-cancer splicing analyses with a positive-enrichment CRISPR screen to prioritize splicing alterations that promote tumorigenesis. We report that diverse SF3B1 mutations converge on repression of BRD9, which is a core component of the recently described non-canonical BAF chromatin-remodelling complex that also contains GLTSCR1 and GLTSCR1L5-7. Mutant SF3B1 recognizes an aberrant, deep intronic branchpoint within BRD9 and thereby induces the inclusion of a poison exon that is derived from an endogenous retroviral element and subsequent degradation of BRD9 mRNA. Depletion of BRD9 causes the loss of non-canonical BAF at CTCF-associated loci and promotes melanomagenesis. BRD9 is a potent tumour suppressor in uveal melanoma, such that correcting mis-splicing of BRD9 in SF3B1-mutant cells using antisense oligonucleotides or CRISPR-directed mutagenesis suppresses tumour growth. Our results implicate the disruption of non-canonical BAF in the diverse cancer types that carry SF3B1 mutations and suggest a mechanism-based therapeutic approach for treating these malignancies.
| S-EPMC6858563 | biostudies-literature
Project description:The mammalian BRG1-associated factors (BAF) complex is a multi-subunit chromatin remodeling complex that is an important component of the embryonic stem cell (ESC) transcriptional regulatory network. However, the role of individual subunits in BAF complex targeting and function needs to be elucidated. Here, we find that the Bromodomain containing protein 9 (BRD9) defines a smaller, non-canonical BAF complex in mouse ESCs that is distinct from the canonical embryonic stem cell BAF (esBAF) and the polybromo-associated BAF (PBAF) complexes. This BRD9-containing BAF complex, or BBAF complex, uniquely incorporates the BRD4-interacting chromatin remodeling associated protein-like (BICRAL) or its paralog BICRA and lacks several esBAF subunits including BAF47, ARID1A and BAF57. We demonstrate that BBAF and esBAF complexes are targeted to different features of the genome and are co-bound with different sets of pluripotency transcription factors. Specifically, BBAF complexes co-localize with key regulators of naïve pluripotency, KLF4 and Sp5, on the genome. Consistent with this, we provide evidence that BBAF’s specific function is to regulate the transcription of genes involved in the maintenance of naïve pluripotency, including Nanog and Prdm14. Additionally, we show that BRD9 is displaced from chromatin by the selective BRD9 bromodomain inhibitor, I-BRD9, and that this leads to changes in target gene expression. Together, our results provide evidence for the identification of a new BAF complex, and demonstrate functionally specific roles for BAF complex assemblies in maintaining the transcriptional network of pluripotency.
2018-10-18 | PXD010670 | Pride
Project description:The mammalian BRG1-associated factors (BAF) complex is a multi-subunit chromatin remodeling complex that is an important component of the embryonic stem cell (ESC) transcriptional regulatory network. However, the role of individual subunits in BAF complex targeting and function needs to be elucidated. Here, we find that the Bromodomain containing protein 9 (BRD9) and Glioma tumor suppressor candidate region gene 1 (GLTSCR1; also known as BICRA) or its paralog GLTSCR1-like (also known as BICRAL) define a smaller, non-canonical BAF complex (GBAF for GLTSCR1/1L-containing BAF complex) in mouse ESCs that is distinct from the canonical embryonic stem cell BAF (esBAF) and the polybromo-associated BAF (PBAF) complexes. GBAF lacks several esBAF subunits, including BAF47, BAF57 and ARID1A. We demonstrate that GBAF and esBAF complexes are targeted to different features of the genome and are co-bound with different sets of pluripotency transcription factors. Specifically, GBAF complexes co-localize with key regulators of naïve pluripotency, KLF4 and Sp5, on the genome. Consistent with this, we provide evidence that GBAF's specific function is to regulate the transcription of genes involved in the maintenance of naïve pluripotency, including Nanog and Prdm14. Additionally, we show that BRD9 is displaced from chromatin by the selective BRD9 bromodomain inhibitor, I-BRD9, and that this leads to changes in target gene expression. The function of the GBAF complex in ESCs is highly correlated with the function of BRD4, consistent with an association between GBAF complexes and BRD4. We find that GBAF complexes are directly recruited to chromatin by BRD4 in a bromodomain-dependent fashion and we identify a set of I-BRD9- and JQ1-sensitive BRD9 binding sites that determine the functional similarity between these epigenetic regulators. Together, our results demonstrate functionally specific roles for BAF complex assemblies in maintaining the transcriptional network of pluripotency, highlighting the biological importance of complex heterogeneity.
2018-10-19 | GSE111264 | GEO
Project description:A non-canonical GLTSCR1L-containing BAF complex mediates H3K27ac-dependent enhancer activities
| PRJNA497106 | ENA
Project description:Mammalian SWI/SNF chromatin remodeling complexes exist in three distinct, final-form assemblies: canonical BAF (cBAF), PBAF, and a newly characterized non-canonical complex, ncBAF. However, their complex-specific targeting on chromatin, functions and roles in disease remain largely unknown. Here, we comprehensively map complex assemblies on chromatin and find that ncBAF uniquely localizes to CTCF sites and promoters. We identified ncBAF subunits as major synthetic lethalities specific to human synovial sarcoma and malignant rhabdoid tumor, which share in common cBAF complex perturbation. Chemical and biological depletion of the BRD9 subunit of ncBAF rapidly attenuates SS and MRT cell proliferation. Notably, in cBAF-perturbed cancers, ncBAF complexes retain localization to CTCF sites and promoters, and maintain gene expression at retained mSWI/SNF sites to support cell proliferation in a manner distinct from fusion oncoprotein-mediated targeting. Taken together, these findings unmask the unique targeting and function of ncBAF complexes and present new cancer-specific therapeutic targets.
2018-11-06 | PXD011103 | Pride
Project description:Mammalian SWI/SNF chromatin remodeling complexes exist in three distinct, final-form assemblies: canonical BAF (cBAF), PBAF, and a newly characterized non-canonical complex, ncBAF. However, their complex-specific targeting on chromatin, functions and roles in disease remain largely unknown. Here, we comprehensively map complex assemblies on chromatin and find that ncBAF uniquely localizes to CTCF sites and promoters. We identified ncBAF subunits as major synthetic lethalities specific to human synovial sarcoma and malignant rhabdoid tumor, which share in common cBAF complex perturbation. Chemical degradation of the BRD9 subunit of ncBAF rapidly attenuates SS and MRT cell proliferation. Notably, in cBAF-perturbed cancers, ncBAF complexes retain their hallmark localization to CTCF sites and promoters, and maintain gene expression at retained mSWI/SNF sites to support cell proliferation in a manner distinct from fusion oncoprotein-mediated targeting. Taken together, these findings unmask the unique targeting and function of ncBAF complexes and present new cancer-specific therapeutic targets.
2018-11-04 | GSE113041 | GEO
Project description:Mammalian SWI/SNF chromatin remodeling complexes exist in three distinct, final-form assemblies: canonical BAF (cBAF), PBAF, and a newly characterized non-canonical complex, ncBAF. However, their complex-specific targeting on chromatin, functions and roles in disease remain largely unknown. Here, we comprehensively map complex assemblies on chromatin and find that ncBAF uniquely localizes to CTCF sites and promoters. We identified ncBAF subunits as major synthetic lethalities specific to human synovial sarcoma and malignant rhabdoid tumor, which share in common cBAF complex perturbation. Chemical degradation of the BRD9 subunit of ncBAF rapidly attenuates SS and MRT cell proliferation. Notably, in cBAF-perturbed cancers, ncBAF complexes retain their hallmark localization to CTCF sites and promoters, and maintain gene expression at retained mSWI/SNF sites to support cell proliferation in a manner distinct from fusion oncoprotein-mediated targeting. Taken together, these findings unmask the unique targeting and function of ncBAF complexes and present new cancer-specific therapeutic targets.
2018-11-04 | GSE113040 | GEO
Project description:A non-canonical SWI/SNF complex underlies synthetic lethality in cancers driven by BAF complex perturbation
| PRJNA449852 | ENA
Project description:In order to determine the transcriptomic network under the control of BAF chromatin remodeling complex in neuroblastoma cells, we performed RNA-Seq analysis on a neuroblastoma cell lines to detect those transcriptionally modulated genes after the disruption of this complex through silencing of its key structural subunits ARID1A and ARID1B.
2022-11-01 | GSE202231 | GEO