BRD9 determines the cell fate of hematopoietic stem cells by regulating chromatin state [Mouse_Brd9_CTCF ChIP-seq]
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ABSTRACT: Switch/sucrose nonfermentable (SWI/SNF) complexes are ATP-dependent chromatin remodeler complexes that play critical roles in timely and appropriate gene regulation by modulating chromatin architecture and DNA accessibility. SWI/SNF complexes can be grouped into three subcomplexes of differing sizes, canonical BAF (cBAF), polybromo BAF (PBAF), and newly identified noncanonical BAF (ncBAF). The most recently characterized ncBAF lacks the core BAF subunits ARID, BAF47, and BAF57, but includes unique subunits GLTSCR1/1L and BRD9, one of the bromodomain-containing proteins.We recently demonstrated the novel mechanism for the ncBAF disruption caused by mutations in a spiceosomal protein, SF3B1, especially in 65–83% for myelodysplastic syndromes (MDS) with ring sideroblasts as well as in >20% of mucosal/uveal melanomas, suggesting that the disturbed ncBAF may have some roles in the malignant hematopoiesis.Mechanistically, SF3B1 mutant recognizes an aberrant, deep intronic branchpoint within BRD9 and thereby induces the inclusion of an aberrant exon and subsequently profound degradation of BRD9 mRNA by triggering nonsense-mediated RNA decay (NMD). However, compared to the roles of cBAF, the functions of BRD9/ncBAF in normal and malignant hematopoiesis in vivo have been totally uncharacterized.
Project description:Switch/sucrose nonfermentable (SWI/SNF) complexes are ATP-dependent chromatin remodeler complexes that play critical roles in timely and appropriate gene regulation by modulating chromatin architecture and DNA accessibility. SWI/SNF complexes can be grouped into three subcomplexes of differing sizes, canonical BAF (cBAF), polybromo BAF (PBAF), and newly identified noncanonical BAF (ncBAF). The most recently characterized ncBAF lacks the core BAF subunits ARID, BAF47, and BAF57, but includes unique subunits GLTSCR1/1L and BRD9, one of the bromodomain-containing proteins.We recently demonstrated the novel mechanism for the ncBAF disruption caused by mutations in a spiceosomal protein, SF3B1, especially in 65–83% for myelodysplastic syndromes (MDS) with ring sideroblasts as well as in >20% of mucosal/uveal melanomas, suggesting that the disturbed ncBAF may have some roles in the malignant hematopoiesis.Mechanistically, SF3B1 mutant recognizes an aberrant, deep intronic branchpoint within BRD9 and thereby induces the inclusion of an aberrant exon and subsequently profound degradation of BRD9 mRNA by triggering nonsense-mediated RNA decay (NMD). However, compared to the roles of cBAF, the functions of BRD9/ncBAF in normal and malignant hematopoiesis in vivo have been totally uncharacterized.
Project description:Switch/sucrose nonfermentable (SWI/SNF) complexes are ATP-dependent chromatin remodeler complexes that play critical roles in timely and appropriate gene regulation by modulating chromatin architecture and DNA accessibility. SWI/SNF complexes can be grouped into three subcomplexes of differing sizes, canonical BAF (cBAF), polybromo BAF (PBAF), and newly identified noncanonical BAF (ncBAF). The most recently characterized ncBAF lacks the core BAF subunits ARID, BAF47, and BAF57, but includes unique subunits GLTSCR1/1L and BRD9, one of the bromodomain-containing proteins.We recently demonstrated the novel mechanism for the ncBAF disruption caused by mutations in a spiceosomal protein, SF3B1, especially in 65–83% for myelodysplastic syndromes (MDS) with ring sideroblasts as well as in >20% of mucosal/uveal melanomas, suggesting that the disturbed ncBAF may have some roles in the malignant hematopoiesis.Mechanistically, SF3B1 mutant recognizes an aberrant, deep intronic branchpoint within BRD9 and thereby induces the inclusion of an aberrant exon and subsequently profound degradation of BRD9 mRNA by triggering nonsense-mediated RNA decay (NMD). However, compared to the roles of cBAF, the functions of BRD9/ncBAF in normal and malignant hematopoiesis in vivo have been totally uncharacterized.
Project description:Switch/sucrose nonfermentable (SWI/SNF) complexes are ATP-dependent chromatin remodeler complexes that play critical roles in timely and appropriate gene regulation by modulating chromatin architecture and DNA accessibility. SWI/SNF complexes can be grouped into three subcomplexes of differing sizes, canonical BAF (cBAF), polybromo BAF (PBAF), and newly identified noncanonical BAF (ncBAF). The most recently characterized ncBAF lacks the core BAF subunits ARID, BAF47, and BAF57, but includes unique subunits GLTSCR1/1L and BRD9, one of the bromodomain-containing proteins.We recently demonstrated the novel mechanism for the ncBAF disruption caused by mutations in a spiceosomal protein, SF3B1, especially in 65–83% for myelodysplastic syndromes (MDS) with ring sideroblasts as well as in >20% of mucosal/uveal melanomas, suggesting that the disturbed ncBAF may have some roles in the malignant hematopoiesis.Mechanistically, SF3B1 mutant recognizes an aberrant, deep intronic branchpoint within BRD9 and thereby induces the inclusion of an aberrant exon and subsequently profound degradation of BRD9 mRNA by triggering nonsense-mediated RNA decay (NMD). However, compared to the roles of cBAF, the functions of BRD9/ncBAF in normal and malignant hematopoiesis in vivo have been totally uncharacterized.
Project description:Switch/sucrose nonfermentable (SWI/SNF) complexes are ATP-dependent chromatin remodeler complexes that play critical roles in timely and appropriate gene regulation by modulating chromatin architecture and DNA accessibility. SWI/SNF complexes can be grouped into three subcomplexes of differing sizes, canonical BAF (cBAF), polybromo BAF (PBAF), and newly identified noncanonical BAF (ncBAF). The most recently characterized ncBAF lacks the core BAF subunits ARID, BAF47, and BAF57, but includes unique subunits GLTSCR1/1L and BRD9, one of the bromodomain-containing proteins.We recently demonstrated the novel mechanism for the ncBAF disruption caused by mutations in a spiceosomal protein, SF3B1, especially in 65–83% for myelodysplastic syndromes (MDS) with ring sideroblasts as well as in >20% of mucosal/uveal melanomas, suggesting that the disturbed ncBAF may have some roles in the malignant hematopoiesis.Mechanistically, SF3B1 mutant recognizes an aberrant, deep intronic branchpoint within BRD9 and thereby induces the inclusion of an aberrant exon and subsequently profound degradation of BRD9 mRNA by triggering nonsense-mediated RNA decay (NMD). However, compared to the roles of cBAF, the functions of BRD9/ncBAF in normal and malignant hematopoiesis in vivo have been totally uncharacterized.
Project description:Switch/sucrose nonfermentable (SWI/SNF) complexes are ATP-dependent chromatin remodeler complexes that play critical roles in timely and appropriate gene regulation by modulating chromatin architecture and DNA accessibility. SWI/SNF complexes can be grouped into three subcomplexes of differing sizes, canonical BAF (cBAF), polybromo BAF (PBAF), and newly identified noncanonical BAF (ncBAF). The most recently characterized ncBAF lacks the core BAF subunits ARID, BAF47, and BAF57, but includes unique subunits GLTSCR1/1L and BRD9, one of the bromodomain-containing proteins.We recently demonstrated the novel mechanism for the ncBAF disruption caused by mutations in a spiceosomal protein, SF3B1, especially in 65–83% for myelodysplastic syndromes (MDS) with ring sideroblasts as well as in >20% of mucosal/uveal melanomas, suggesting that the disturbed ncBAF may have some roles in the malignant hematopoiesis.Mechanistically, SF3B1 mutant recognizes an aberrant, deep intronic branchpoint within BRD9 and thereby induces the inclusion of an aberrant exon and subsequently profound degradation of BRD9 mRNA by triggering nonsense-mediated RNA decay (NMD). However, compared to the roles of cBAF, the functions of BRD9/ncBAF in normal and malignant hematopoiesis in vivo have been totally uncharacterized.
Project description:Switch/sucrose nonfermentable (SWI/SNF) complexes are ATP-dependent chromatin remodeler complexes that play critical roles in timely and appropriate gene regulation by modulating chromatin architecture and DNA accessibility. SWI/SNF complexes can be grouped into three subcomplexes of differing sizes, canonical BAF (cBAF), polybromo BAF (PBAF), and newly identified noncanonical BAF (ncBAF). The most recently characterized ncBAF lacks the core BAF subunits ARID, BAF47, and BAF57, but includes unique subunits GLTSCR1/1L and BRD9, one of the bromodomain-containing proteins.We recently demonstrated the novel mechanism for the ncBAF disruption caused by mutations in a spiceosomal protein, SF3B1, especially in 65–83% for myelodysplastic syndromes (MDS) with ring sideroblasts as well as in >20% of mucosal/uveal melanomas, suggesting that the disturbed ncBAF may have some roles in the malignant hematopoiesis.Mechanistically, SF3B1 mutant recognizes an aberrant, deep intronic branchpoint within BRD9 and thereby induces the inclusion of an aberrant exon and subsequently profound degradation of BRD9 mRNA by triggering nonsense-mediated RNA decay (NMD). However, compared to the roles of cBAF, the functions of BRD9/ncBAF in normal and malignant hematopoiesis in vivo have been totally uncharacterized.
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.
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.
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.
Project description:Genes encoding subunits of SWI/SNF (BAF) chromatin remodeling complexes are mutated in >20% of cancers. SWI/SNF complexes exist in three distinct families that each contribute to regulation of transcription, although the functional interactions between the families are not well understood. Rhabdoid tumors constitute an informative model system as these highly aggressive cancers are driven by inactivation of a single SWI/SNF subunit, SMARCB1, which is present in two SWI/SNF families (cBAF and PBAF) but not in the third (GBAF/ncBAF). We and others have shown that BRD9, a therapeutically targetable member of ncBAF, is essential specifically in SMARCB1-deficient cancers, suggesting key functional relationships between SMARCB1-containing complexes and BRD9/ncBAF. However, the mechanistic underpinnings of these relationships are poorly understood. Here, we demonstrate that genomic binding of BRD9 is largely dependent upon SMARCB1 such that the absence of SMARCB1 results in significantly reduced BRD9 binding. At select sites, however, we show that SMARCB1-loss results in gain of BRD9 binding and BRD9-dependent accessibility. We find that this gain is associated with expression of genes promoting cell migration. Our results define relationships between SWI/SNF complex families, elucidate mechanisms by which SMARCB1 loss drives oncogenesis, and provide mechanistic insight into the synthetic-lethal relationship between SMARCB1 and BRD9.