PBAF complex deficiency in melanoma mediates BAF occupancy and transcription factor dynamics (Chromatin)
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE172383 | GEO | 2022/04/05
REPOSITORIES: GEO
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Project description:ARID2 is an essential subunit of the SWI/SNF PBAF chromatin remodeler and is highly mutate in melanoma. To elucidate the role of ARID2 in melanoma biology and chromatin structure we utilized CRISPR Cas9 methodology to generate isogenic ARID2 WT and KO melanoma clonal cell lines. We further map the genomic localization of several SWI/SNF subunits, open and repressed chromatin markers, and multiple transcription factors to characterize how loss of the PBAF subcomplex alters chromatin accessibility and the melanoma transcription factor network. Finally, we characterized the transcriptional changes produced by PBAF depletion.
2022-04-05 | GSE172384 | GEO
Project description:Multimeric SWI/SNF chromatin remodelers assemble in distinct conformations, with individual functions difficult to dissect. Importantly, mutations in specific SWI/SNF genes are enriched in distinct cancers, as the PBAF-specific component ARID2 in melanoma. Through comprehensive epigenomic profiling of SWI/SNF complexes and their associated chromatin states in melanoma and melanocytes, we found that a subset of PBAF-exclusive regions unexpectedly coexists with PRC2 and repressed chromatin. Time-resolved approaches revealed that PBAF regions are generally less sensitive to ATPase-mediated remodeling compared to BAF sites. Notably, PBAF/PRC2-bound loci are enriched for REST, a transcription factor that represses neuronal genes. In turn, absence of ARID2 and consequent PBAF loss hinders REST ability to bind and inactivate its targets, leading to upregulation of neuronal and synaptic transcripts, a gene signature also associated with ARID2 mutations in melanoma patients. In sum, we demonstrate a unique role for PBAF in generating accessibility for a silencing transcription factor at repressed chromatin.
2024-10-01 | GSE272705 | GEO
Project description:Multimeric SWI/SNF chromatin remodelers assemble in distinct conformations, with individual functions difficult to dissect. Importantly, mutations in specific SWI/SNF genes are enriched in distinct cancers, as the PBAF-specific component ARID2 in melanoma. Through comprehensive epigenomic profiling of SWI/SNF complexes and their associated chromatin states in melanoma and melanocytes, we found that a subset of PBAF-exclusive regions unexpectedly coexists with PRC2 and repressed chromatin. Time-resolved approaches revealed that PBAF regions are generally less sensitive to ATPase-mediated remodeling compared to BAF sites. Notably, PBAF/PRC2-bound loci are enriched for REST, a transcription factor that represses neuronal genes. In turn, absence of ARID2 and consequent PBAF loss hinders REST ability to bind and inactivate its targets, leading to upregulation of neuronal and synaptic transcripts, a gene signature also associated with ARID2 mutations in melanoma patients. In sum, we demonstrate a unique role for PBAF in generating accessibility for a silencing transcription factor at repressed chromatin.
2024-10-01 | GSE275420 | GEO
Project description:BAF and PBAF are mammalian SWI/SNF family chromatin remodeling complexes that possess multiple histone/DNA-binding subunits and create nucleosome-depleted/free regions for transcription activation. Despite previous structural studies and recent advance of SWI/SNF family complexes, it remains incompletely understood how PBAF-nucleosome complex is organized. Here we determined structure of 13-subunit human PBAF in complex with acetylated nucleosome in ADP-BeF3-bound state. Four PBAF-specific subunits work together with nine BAF/PBAF-shared subunits to generate PBAF-specific modular organization, distinct from that of BAF at various regions. PBAF-nucleosome structure reveals six histone-binding domains and four DNA-binding domains/modules, the majority of which directly bind histone/DNA. This multivalent nucleosome-binding pattern, not observed in previous studies, suggests that PBAF may integrate comprehensive chromatin information to target genomic loci for function. Our study reveals molecular organization of subunits and histone/DNA-binding domains/modules in PBAF-nucleosome complex and provides structural insights into PBAF-mediated nucleosome association complimentary to the recently reported PBAF-nucleosome structure.
2023-03-11 | PXD036708 | Pride
Project description:The composition of chromatin remodeling complexes dictates how these enzymes control transcriptional programs and cellular identity. Here, we investigate the composition of SWI/SNF complexes in embryonic stem cells (ESCs). In contrast to differentiated cells, ESCs have a biased incorporation of certain paralogous SWI/SNF subunits, with low levels of Brm, BAF170 and ARID1B. Upon differentiation, the expression of these subunits increases, resulting in a higher diversity of compositionally distinct SWI/SNF enzymes. We also identify Brd7 as a novel component of the PBAF complex in both ESCs and differentiated cells. Using shRNA-mediated depletion of Brg1, we show that SWI/SNF can function as both a repressor and an activator in pluripotent cells, regulating expression of developmental modifiers and signaling components such as Nodal, ADAMTS1, Bmi-1, CRABP1 and TRH. Knock-down studies of PBAF-specific Brd7 and of a signature subunit within the BAF complex, ARID1A, show that these two sub-complexes affect SWI/SNF target genes differentially, in some cases even antagonistically. This may be due to their different biochemical properties. Finally, we examine the role of SWI/SNF in regulating its target genes during differentiation. We find that SWI/SNF affects recruitment of components of the pre-initiation complex in a promoter-specific manner, to modulate transcription positively or negatively. Taken together, our results provide insight into the function of compositionally diverse SWI/SNF enzymes that underlie their inherent gene-specific mode of action. R1 ESCs were infected in duplicates with shRNA targeting Brg1 or GLUT4 (as a control). Knockdown of Brg1 mRNA affected Brg1 protein levels efficiently. RNA was isolated 67 hours post-infection and analyzed using microarrays.
2010-03-04 | E-GEOD-7791 | biostudies-arrayexpress
Project description:The PBAF complex, a member of SWI/SNF family of chromatin remodelers, plays an essential role in transcriptional regulation. We revealed a disease progression associated elevation of PHF10 subunit of PBAF in clinical samples of melanoma. We demonstrated that in melanoma cell lines, PHF10 interacts with MYC and facilitates the recruitment of PBAF complex to target gene promoters, therefore augmenting MYC transcriptional activation of genes involved in the cell cycle progression. Depletion of either PHF10 or MYC induced G1 accumulation and a senescence-like phenotype. Our data identify PHF10 as a pro-oncogenic mechanism and an essential novel link between chromatin remodeling and MYC-dependent gene transcription.
2021-04-08 | GSE164726 | GEO
Project description:PBRM1 is lost in 40% of clear cell renal cell carcinomas (ccRCC) and the combined loss of VHL and PBRM1 drives ccRCC tumorigenesis. PBRM1 is an accessory subunit of the PBAF subclass of the SWI/SNF chromatin remodeler and despite its well-established role as a tumor suppressor, we have limited understanding of how PBRM1 regulates the chromatin. Now we report that PBRM1 binds to promoter-proxy regions with footprints at +1 to + 3 nucleosomes. PBRM1-deficient PBAF complexes lose BRD7 but retain ARID2, while tethered to SMARCA4. The lack of PBRM1-BRD7 module compromises the targeting specificity of the PBAF complexes, causes their genomic redistribution and impairs the repressive ability of PBAF complexes. Subsequently, PBRM1-deficient PBAF complexes prime the chromatin at de novo sites for transcriptional activation of pro-survival genes involved in hypoxia and cholesterol synthesis. Therefore, PBRM1 safeguards the chromatin by repressing aberrant liberation of pro-survival genes by residual PBRM1-deficient SWI/SNF complexes.
2021-07-24 | PXD020554 | JPOST Repository
Project description:PBRM1 is lost in 40% of clear cell renal cell carcinomas (ccRCC) and the combined loss of VHL and PBRM1 drives ccRCC tumorigenesis. PBRM1 is an accessory subunit of the PBAF subclass of the SWI/SNF chromatin remodeler and despite its well-established role as a tumor suppressor, we have limited understanding of how PBRM1 regulates the chromatin. Now we report that PBRM1 binds to promoter-proxy regions with footprints at +1 to + 3 nucleosomes. PBRM1-deficient PBAF complexes lose BRD7 but retain ARID2, while tethered to SMARCA4. The lack of PBRM1-BRD7 module compromises the targeting specificity of the PBAF complexes, causes their genomic redistribution and impairs the repressive ability of PBAF complexes. Subsequently, PBRM1-deficient PBAF complexes prime the chromatin at de novo sites for transcriptional activation of pro-survival genes involved in hypoxia and cholesterol synthesis. Therefore, PBRM1 safeguards the chromatin by repressing aberrant liberation of pro-survival genes by residual PBRM1-deficient SWI/SNF complexes.
2021-07-24 | PXD020553 | JPOST Repository
Project description:Subunits of SWI/SNF chromatin remodeling complexes are frequently mutated in human malignancies. The PBAF complex is composed of multiple subunits, including the putative tumor suppressor proteins PBRM1 (BAF180) and ARID2 (BAF200) that are unique to this SWI/SNF complex. PBRM1 is mutated in various cancers, with a high mutation frequency in clear cell renal cell carcinoma (ccRCC). Here, we integrate RNA-seq, ARID2 and histone mark ChIP-seq, and ATAC-seq data to show that PBAF acts to enhance or repress gene expression depending on the genomic context. At baseline, ARID2 binds to areas of open chromatin at both active enhancers and promoters. Depletion of PBRM1 leads to attenuated and redistributed ARID2 chromatin binding that correlates significantly with gene expression changes. At enhancers, ARID2 binding loss leads to diminishment of the histone mark H3K4me1 and gene downregulation. Alternatively, at a subset of promoters, ARID2 binding loss derepresses gene expression. Interestingly, ARID2, which remains bound to other PBAF subunits after loss of PBRM1, is essential for many of the pro-tumorigenic transcriptional changes observed after loss of PBRM1, whereas other core SWI/SNF components are dispensable. Upon loss of PBRM1, ARID2 positively regulates cancer-related genes and pathways, including the cancer stem cell marker ALDH1A1 and EGF signaling, to stimulate tumor cell growth. Therefore, ARID2 is crucial for maintaining the transformed state of PBRM1-deficient ccRCC cells. In total, this study suggests a novel mechanism of transcriptional control by PBRM1, whereby its loss alters the chromatin distribution of the residual PBAF complex leading to altered transcription that promotes tumorigenesis.
2018-08-14 | GSE102806 | GEO
Project description:Subunits of SWI/SNF chromatin remodeling complexes are frequently mutated in human malignancies. The PBAF complex is composed of multiple subunits, including the putative tumor suppressor proteins PBRM1 (BAF180) and ARID2 (BAF200) that are unique to this SWI/SNF complex. PBRM1 is mutated in various cancers, with a high mutation frequency in clear cell renal cell carcinoma (ccRCC). Here, we integrate RNA-seq, ARID2 and histone mark ChIP-seq, and ATAC-seq data to show that PBAF acts to enhance or repress gene expression depending on the genomic context. At baseline, ARID2 binds to areas of open chromatin at both active enhancers and promoters. Depletion of PBRM1 leads to attenuated and redistributed ARID2 chromatin binding that correlates significantly with gene expression changes. At enhancers, ARID2 binding loss leads to diminishment of the histone mark H3K4me1 and gene downregulation. Alternatively, at a subset of promoters, ARID2 binding loss derepresses gene expression. Interestingly, ARID2, which remains bound to other PBAF subunits after loss of PBRM1, is essential for many of the pro-tumorigenic transcriptional changes observed after loss of PBRM1, whereas other core SWI/SNF components are dispensable. Upon loss of PBRM1, ARID2 positively regulates cancer-related genes and pathways, including the cancer stem cell marker ALDH1A1 and EGF signaling, to stimulate tumor cell growth. Therefore, ARID2 is crucial for maintaining the transformed state of PBRM1-deficient ccRCC cells. In total, this study suggests a novel mechanism of transcriptional control by PBRM1, whereby its loss alters the chromatin distribution of the residual PBAF complex leading to altered transcription that promotes tumorigenesis.
2018-08-14 | GSE102803 | GEO