Project description:Chromatin remodeling complexes instruct cellular differentiation and lineage specific transcription. The BRG1/BRM-associated factor (BAF) complexes are important for several aspects of differentiation. We show that the catalytic subunit gene Brg1 has a specific role in cardiac precursors (CPs) to initiate cardiac gene expression programs and repress non-cardiac expression. Using immunopurification with mass spectrometry, we have determined the dynamic composition of BAF complexes during mammalian cardiac differentiation, identifying several cell-type specific subunits. We focused on the CP- and cardiomyocyte (CM)-enriched subunits BAF60c (SMARCD3) and BAF170 (SMARCC2). Baf60c and Baf170 co-regulate gene expression with Brg1 in CPs, and in CMs their loss results in broadly deregulated cardiac gene expression. BRG1, BAF60c and BAF170 modulate chromatin accessibility, to promote accessibility at activated genes while closing chromatin at repressed genes. BAF60c and BAF170 are required for proper BAF complex composition, and BAF170 loss leads to retention of BRG1 at CP-specific sites. Thus, dynamic interdependent BAF complex subunit assembly modulates chromatin states and thereby participates in directing temporal gene expression programs in cardiogenesis.
Project description:Chromatin remodeling complexes instruct cellular differentiation and lineage specific transcription. The BRG1/BRM associated factor (BAF) complexes are important for several aspects of differentiation. We show that the catalytic subunit Brg1 has a specific role in cardiac precursors (CPs) to initiate cardiac gene expression programs and repress non-cardiac expression. Using immunoprecipitation immunopurification with mass spectrometry we determined the dynamic composition of BAF complexes during mammalian cardiac differentiation, identifying several cell-type specific subunits. We focused on the CP- and cardiomyocytes (CM)-enriched subunits BAF60c (SMARCD3) and BAF170 (SMARCC2). Baf60c and Baf170 co-regulate gene expression with Brg1 in CPs, and in CMs their loss results in broadly deregulated cardiac gene expression. BRG1, BAF60, and BAF170 modulate chromatin accessibility, to either promote accessibility at activated genes, while closing up chromatin at repressed genes. BAF60c and BAF170 are required for proper BAF complex composition, and BAF170 loss leads to retention of BRG1 at CP-specific enhancers. Thus, dynamic interdependent BAF complex subunit assembly modulates chromatin states and thereby participates in directing temporal gene expression programs in cardiogenesis.
Project description:Genome-wide occupancy analysis of BRG1 during cardiac precursor and crdiomyocyte stages of differentiation in WT and cells lacking BAF60c or BAF170
Project description:We compared differential gene expression between WT and BAF60c KO and between WT and BAF170 KO cardiac precursors and cardiomyocytes
Project description:We performed differential mRNA analysis in WT and BRG1 KO cells during cardiac precursor and cardiomyocytes stages of directed differention of mouse ES cells to cardiac myocytes. We show that BRG1 activity is higher in cardiac precursor cells and severely reduced in cardiac myocytes