ABSTRACT: PKA-dependent Phosphorylation of A Histone Demethylase Drives Higher Order Chromatin Structures by Association with SWI/SNF Chromatin Remodeler
Project description:The current studies show that JMJD1A is phosphorylated at S265 by protein kinase A (PKA), and this is pivotal to activate expression of the b1-adrenergic receptor gene (Adrb1) and downstream targets including Ucp1. Phosphorylation of JMJD1A increases its interaction with the SWI/SNF nucleosome remodeling complex and DNA-bound PPARg. This complex conferred b-adrenergic-induced JMJD1A recruitment to target sites throughout the genome. Phospho-JMJD1A also facilitated long-range chromatin looping to recruit PPARg-bound distal-enhancers, SWI/SNF, and RNA polymerase close to the Adrb1 locus to activate transcription. Mutation of the PKA-phosphorylation site on JMJD1A abolished interactions with SWI/SNF without affecting demethylase activity suggesting the two functions are independent of each other. Our results show that JMJD1A demethylase is also a signal-sensing scaffold that regulates cAMP-responsive transcription via interactions with SWI/SNF and hormone stimulated higher-order chromatin conformational changes. There are 3 samples analyzed. No duplication from each sample. Isoproterenol stimulation at 0hr is used as the relative to fold change in manuscript.
Project description:The current studies show that JMJD1A is phosphorylated at S265 by protein kinase A (PKA), and this is pivotal to activate expression of the b1-adrenergic receptor gene (Adrb1) and downstream targets including Ucp1. Phosphorylation of JMJD1A increases its interaction with the SWI/SNF nucleosome remodeling complex and DNA-bound PPARg. This complex conferred b-adrenergic-induced JMJD1A recruitment to target sites throughout the genome. Phospho-JMJD1A also facilitated long-range chromatin looping to recruit PPARg-bound distal-enhancers, SWI/SNF, and RNA polymerase close to the Adrb1 locus to activate transcription. Mutation of the PKA-phosphorylation site on JMJD1A abolished interactions with SWI/SNF without affecting demethylase activity suggesting the two functions are independent of each other. Our results show that JMJD1A demethylase is also a signal-sensing scaffold that regulates cAMP-responsive transcription via interactions with SWI/SNF and hormone stimulated higher-order chromatin conformational changes.
Project description:The SWI/SNF (or BAF) complex is an essential chromatin remodeler that regulates DNA accessibility at developmental genes and enhancers. SWI/SNF subunits are among the most frequently mutated genes in cancer and neurodevelopmental disorders. These mutations are often heterozygous loss-of-function alleles, indicating a dosage-sensitive role for SWI/SNF subunits in chromatin regulation. However, the molecular mechanisms that regulate SWI/SNF subunit dosage to ensure proper complex assembly remain largely unexplored. We performed a genome-wide CRISPR KO screen, using epigenome editing in mouse embryonic stem cells, and identified Mlf2 and Rbm15 as regulators of SWI/SNF complex activity. First, we show that MLF2, a poorly characterized chaperone protein, regulates a subset of SWI/SNF target genes by promoting its chromatin remodeling activity. Rapid degradation of MLF2 reduces chromatin accessibility at sites that depend on high levels of SWI/SNF binding to maintain open chromatin. Next, we find that RBM15, part of the m6A RNA methylation writer complex, controls m6A modifications on specific SWI/SNF mRNAs to regulate protein levels of these subunits. Misregulation of m6A methylation causes overexpression of core SWI/SNF subunits leading to the assembly of incomplete complexes lacking the catalytic ATPase/ARP subunits. These data indicate that targeting modulators of SWI/SNF complex assembly may offer a potent therapeutic strategy for diseases associated with impaired chromatin remodeling.
Project description:The SWI/SNF (or BAF) complex is an essential chromatin remodeler that regulates DNA accessibility at developmental genes and enhancers. SWI/SNF subunits are among the most frequently mutated genes in cancer and neurodevelopmental disorders. These mutations are often heterozygous loss-of-function alleles, indicating a dosage-sensitive role for SWI/SNF subunits in chromatin regulation. However, the molecular mechanisms that regulate SWI/SNF subunit dosage to ensure proper complex assembly remain largely unexplored. We performed a genome-wide CRISPR KO screen, using epigenome editing in mouse embryonic stem cells, and identified Mlf2 and Rbm15 as regulators of SWI/SNF complex activity. First, we show that MLF2, a poorly characterized chaperone protein, regulates a subset of SWI/SNF target genes by promoting its chromatin remodeling activity. Rapid degradation of MLF2 reduces chromatin accessibility at sites that depend on high levels of SWI/SNF binding to maintain open chromatin. Next, we find that RBM15, part of the m6A RNA methylation writer complex, controls m6A modifications on specific SWI/SNF mRNAs to regulate protein levels of these subunits. Misregulation of m6A methylation causes overexpression of core SWI/SNF subunits leading to the assembly of incomplete complexes lacking the catalytic ATPase/ARP subunits. These data indicate that targeting modulators of SWI/SNF complex assembly may offer a potent therapeutic strategy for diseases associated with impaired chromatin remodeling.
Project description:The SWI/SNF ATP-dependent chromatin remodeler is a master regulator of the epigenome; controlling pluripotency, cell fate determination and differentiation. There is a sparsity of information on the autoregulation of SWI/SNF, the domains involved and their mode of action. We find a DNA or RNA binding module conserved from yeast to humans located in the C-terminus of the catalytic subunit of SWI/SNF called the AT-hook that positively regulates the chromatin remodeling activity of yeast and mouse SWI/SNF. The AT-hook in yeast SWI/SNF interacts with the SnAC and ATPase domains, which after binding to nucleosome switches to contacting the N-terminus of histone H3. Deletion of the AT-hooks in yeast SWI/SNF and mouse esBAF complexes reduces the remodeling activity of SWI/SNF without affecting complex integrity or its recruitment to nucleosomes. In addition, deletion of the AT-hook impairs the ATPase and nucleosome mobilizing activities of yeast SWI/SNF without disrupting the interactions of the ATPase domain with nucleosomal DNA. The AT-hook is also important in vivo for SWI/SNF-dependent response to amino acid starvation in yeast and for cell lineage priming in mouse embryonic stem cells. In summary, the AT-hook is shown to be an evolutionarily conserved autoregulatory domain of SWI/SNF that positively regulates SWI/SNF both in vitro and in vivo.
Project description:Tissue-specific transcription factors initiate differentiation toward a specialized cell type by inducing transcription-permissive chromatin modifications at target gene promoters, through the recruitment of the SWI/SNF chromatin-remodeling complex (1, 2). The molecular mechanism that regulates the chromatin re-distribution of SWI/SNF in response to differentiation signals is currently unknown. Here we show that the muscle determination factor MyoD and the SWI/SNF structural sub-unit, BAF60c (SMARCD3), form a complex on the regulatory elements of MyoD-target genes in undifferentiated myoblasts, prior to the activation of gene expression. MyoD-BAF60c complex is devoid of the ATP-dependent enzymatic sub-units Brg1 and Brm, is required for stable MyoD binding to Ebox sequences, and marks the chromatin for signal-dependent recruitment of the SWI/SNF core complex to muscle loci. BAF60c phosphorylation on a conserved threonine by differentiation-activated p38 signalling promotes the incorporation of MyoD-BAF60c into a Brg1-based SWI/SNF complex, which is competent to remodel the chromatin and activates transcription of MyoD-target genes. Our data support an unprecedented two-step model, by which pre-assembled BAF60c-MyoD complex directs the SWI/SNF complex chromatin re-distribution to muscle loci in response to differentiation cues. Differentiation of C2C12 cells individually interfered for BRG1, BAF60B, BAF60C
Project description:The SWI/SNF (or BAF) complex is an essential chromatin remodeler that regulates DNA accessibility at developmental genes and enhancers. SWI/SNF subunits are among the most frequently mutated genes in cancer and neurodevelopmental disorders. These mutations are often heterozygous loss-of-function alleles, indicating a dosage-sensitive role for SWI/SNF subunits in chromatin regulation. However, the molecular mechanisms that regulate SWI/SNF subunit dosage to ensure proper complex assembly remain largely unexplored. We performed a genome-wide CRISPR KO screen, using epigenome editing in mouse embryonic stem cells, and identified Mlf2 and Rbm15 as regulators of SWI/SNF complex activity. First, we show that MLF2, a poorly characterized chaperone protein, regulates a subset of SWI/SNF target genes by promoting chromatin remodeling activity. Next, we find that RBM15, part of the m6A RNA methylation writer complex, controls m6A modifications on specific SWI/SNF mRNAs to regulate protein levels of these subunits. Misregulation of m6A methylation causes overexpression of core SWI/SNF subunits leading to the assembly of incomplete complexes lacking the catalytic ATPase/ARP subunits. These data indicate that targeting modulators of SWI/SNF complex assembly may offer a potent therapeutic strategy for diseases associated with impaired chromatin remodeling.
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.
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.
Project description:Using CRISPR-Cas9 to tag endogenous remodeler subunits in Drosophila melanogaster S2 cells, we demonstrate that developmental gene transcription requires SWI/SNF-type complexes, primarily to maintain distal enhancer accessibility.