Project description:Neuronal activity-induced enhancers drive gene activation. We demonstrate that BRG1, the core subunit of SWI/SNF-like BAF ATP-dependent chromatin remodeling complexes, regulates neuronal activity-induced enhancers. Upon stimulation, BRG1 is recruited to enhancers in an H3K27Ac-dependent manner. BRG1 regulates enhancer basal activities and inducibility by affecting cohesin binding, enhancer-promoter looping, RNA polymerase II recruitment, and enhancer RNA expression. We identify a serine phosphorylation site in BRG1 that is induced by neuronal stimulations and is sensitive to CaMKII inhibition. BRG1 phosphorylation affects its interaction with several transcription co-factors, including the NuRD repressor complex and cohesin, possibly modulating BRG1-mediated transcription outcomes. Using mice with knockin mutations, we show that non-phosphorylatable BRG1 fails to efficiently induce activity-dependent genes, whereas phosphomimic BRG1 increases enhancer activity and inducibility. These mutant mice display anxiety-like phenotypes and altered responses to stress. Therefore, we reveal a mechanism connecting neuronal signaling to enhancer activities through BRG1 phosphorylation.
Project description:We found binding of the remodeling protein BRG1 was programmed by lineage and activation signals. BRG1 binding was positively correlated with gene activity at protein-coding and miRNA genes. BRG1 binding was found at promoters and distal regions, including known and novel distal regulatory elements. Distal BRG1 binding correlated with expression, and novel distal sites possessed enhancer activity, suggesting a general role for BRG1 in long-distance gene regulation. Together, these findings suggest BRG1 interprets differentiation and activation signals and plays a causal role in gene regulation, chromatin structure, and cell fate. Our findings indicate BRG1 binding is a useful marker for identifying cis-regulatory regions in protein-coding and miRNA genes. Compare BRG1 binding in T helper subsets genome wide; Naïve, resting Th1, resting Th2, Stimulated Th1, Stimulated Th2, Stimulated Th17, compared to input DNA as negative control
Project description:<p>The goal of this proposal is to bring together the power of 1) whole exome sequencing, 2) homozygosity mapping in consanguineous families, 3) genome-wide maps of neuronal transcription in response to neuronal activity, and 4) genome-wide maps of the binding sites of factors that regulate this transcription to generate and annotate a catalog of ASD-associated variants. The consanguineous families are already enrolled in research, and have been phenotyped. The neuronal transcription and binding site maps will be developed by the Greenberg Lab at Harvard Medical School. The whole exome sequencing will be done at the Broad Institute, and the Walsh lab at Children's Hospital will validate the results and analyze the variant data.</p>
Project description:Activation and differentiation of B cells depend on extensive rewiring of gene expression networks through changes in chromatin structure and accessibility. The chromatin remodeling complex BAF with its catalytic subunit Brg1 was previously identified as an essential regulator of early B cell development, however, how Brg1 orchestrates gene expression during mature B cell activation is less clear. Here, we find that Brg1 is required for B cell proliferation and germinal center formation through selective interactions with enhancers. Brg1 recruitment to enhancers was associated with increased chromatin accessibility and transcriptional activation of their coupled promoters following B cell activation and expression of cell cycle-associated genes. Accordingly, Brg1-deficient B cells were unable to mount germinal center reactions and support the formation of class-switch plasma cells. Our findings show that changes in B cell transcriptomes that support cell proliferation and GC formation depend on enhancer activation by Brg1. Thus, the BAF complex plays a critical role during the onset of the humoral immune response.
Project description:We found binding of the remodeling protein BRG1 was programmed by lineage and activation signals. BRG1 binding was positively correlated with gene activity at protein-coding and miRNA genes. BRG1 binding was found at promoters and distal regions, including known and novel distal regulatory elements. Distal BRG1 binding correlated with expression, and novel distal sites possessed enhancer activity, suggesting a general role for BRG1 in long-distance gene regulation. Together, these findings suggest BRG1 interprets differentiation and activation signals and plays a causal role in gene regulation, chromatin structure, and cell fate. Our findings indicate BRG1 binding is a useful marker for identifying cis-regulatory regions in protein-coding and miRNA genes.