Project description:Transcription factor GATA1 binding in erythroblasts in the presence and absence of BET inhibitor JQ1, and BET protein BRD3 and BRD4 binding in erythroblasts in the presence and absence of GATA1. Inhibitors of Bromodomain and Extra-Terminal motif proteins (BETs) are being evaluated for the treatment of cancer and other diseases yet their physiologic mechanisms remain largely unknown. We used genomic and genetic approaches to examine BET function in a hematopoietic maturation system driven by GATA1, an acetylated transcription factor previously shown to interact with BETs. We found that while BRD3 occupied the majority of GATA1 binding sites, BRD2 and BRD4 were also recruited to a subset of GATA1-occupied sites. Functionally, BET inhibition impaired GATA1-mediated transcriptional activation, but not repression, genome-wide. Co-activation by BETs was accomplished both by facilitating genomic occupancy of GATA1 and subsequently supporting transcription activation. Using a combination of CRISPR/CAS9-mediated genomic engineering and shRNA approaches we observed that depletion of either BRD2 or BRD4 alone blunted erythroid gene activation, while depletion of BRD3 only affected erythroid transcription in the setting of BRD2 deficiency. These results suggest that pharmacologic BET inhibition should be interpreted in the context of distinct steps in transcriptional activation and partially overlapping functions among BET family members. GATA1 null erythroblasts (G1E) conditionally expressing GATA1 as a GATA1-ER fusion protein were induced to express GATA1 by addition of 100nM estradiol for 24 hours. For GATA1 binding experiments this occurred in the absence or presence of 250nM JQ1. For BRD3 and BRD4 occupancy experiments G1E cells were compared to G1E cells with activated GATA1-ER fusion protein.
Project description:Understanding the precise functions and relationship of BRD2 with other bromodomain and extraterminal motif (BET) proteins is central for the application of BET-specific and pan inhibitors. Here, we used acute protein degradation and quantitative genomic and proteomic approaches to investigate the primary functions of BRD2 in transcription. We report that BRD2 is required for TAF3-mediated Pol II initiation at low levels of H3K4me3-modified promoters and Pol II elongation by suppressing R-loops. Single and double depletion revealed that BRD2 and BRD3, but not BRD4, redundantly and independently function in Pol II transcription at different promoters and cooperatively occupy enhancers. Interestingly, we found that depletion of BRD2 affects the expression of different genes during differentiation processes, priming with promoter regulation in ES cells. Therefore, our results suggest complex interconnections between BRD2 and BRD3 at promoters to fine-tune Pol II initiation and elongation for control of cell state.
Project description:BET-regulated transcriptome and BRD4, BRD2, BRD3 and Pol II ChIP-seq datasets in human ESCs before and after BET inhibition. Transcription factors and chromatin remodeling complexes are key determinants of embryonic stem cell (ESC) identity. In this study, we investigate the role of BRD4, a member of the bromodomain and extra-terminal domain (BET) family of epigenetic reader proteins, in control of ESC identity. We performed RNA-seq analyiss in the presense of small molecule inhibitors of BET proteins to show that BRD4 positively regulates the ESC transcriptome. We also integrated RNA-seq analysis with ChIP-sequencing datasets s for BRD4 (and for other BRD2 and BRD3) to demonstrate that BRD4 binds SEs and regulates the expression of SE-associated pluripotency genes. We have also conducted ChIP-seq analysis for Pol II binding to demonstrate that SE-associated genes depend on BRD4-dependent Pol II binding at TSS and gene body for their productive transcriptional elongation.
Project description:We identified a chromatin displacement signature for the bromodomain proteins BRD2, BRD3 and BRD4 at TSS following treatment with I-BET152, an inhibitor of BET proteins. By integrating ChIP-seq, RNA-seq and Chem-seq data, we correlated alteration of the BRD4 signature at TSS with strong downregulation of gene expression which will facilitate identification of markers of sensitivity and resistance to drug.
Project description:Data independent acquisition (DIA) mass spectrometry was used to study the selectivity of 2J2V for BET proteins from A549 cells. BET proteins, BRD2, BRD3 and BRD4 were observed to be degraded the most by 2J2V in comparison to MZ1 or DMSO.
Project description:BET-regulated transcriptome and BRD4, BRD2, BRD3 and Pol II ChIP-seq datasets in human ESCs before and after BET inhibition. Transcription factors and chromatin remodeling complexes are key determinants of embryonic stem cell (ESC) identity. In this study, we investigate the role of BRD4, a member of the bromodomain and extra-terminal domain (BET) family of epigenetic reader proteins, in control of ESC identity. We performed RNA-seq analyiss in the presense of small molecule inhibitors of BET proteins to show that BRD4 positively regulates the ESC transcriptome. We also integrated RNA-seq analysis with ChIP-sequencing datasets s for BRD4 (and for other BRD2 and BRD3) to demonstrate that BRD4 binds SEs and regulates the expression of SE-associated pluripotency genes. We have also conducted ChIP-seq analysis for Pol II binding to demonstrate that SE-associated genes depend on BRD4-dependent Pol II binding at TSS and gene body for their productive transcriptional elongation. Total RNA was extracted from samples using the RNeasy Qiagen kit according to the manufacturer’s instructions. Deep sequencing of RNA (1ug) from hESCs FGF- or MS436-treated at day 1 and day 5 was performed as described in (Higgin et al., 2010c). Samples were subjected to PolyA selection using magnetic oligo-dT beads. The resulting RNA samples were then used as input for library construction as described by the manufacturer (Illumina, CA, USA). RNA libraries were then sequenced on the GAIIx system using 50bp single reads. Chromatin for ChIP-sequencing was obtained from FGF-maintained hESCs, vehicle or MS417-treated (at 250nM concentration for 6h) (10 to 20x106 cells/IP). ChIP-Seq libraries were generated using standard Illumina kit and protocol as described in (Ntziachristos et al., 2012). We performed cluster amplification and single read 50 sequencing-method using the Illumina HiSeq 2000, following manufacturer’s protocols.
Project description:Transcription factor GATA1 binding in erythroblasts in the presence and absence of BET inhibitor JQ1, and BET protein BRD3 and BRD4 binding in erythroblasts in the presence and absence of GATA1. Inhibitors of Bromodomain and Extra-Terminal motif proteins (BETs) are being evaluated for the treatment of cancer and other diseases yet their physiologic mechanisms remain largely unknown. We used genomic and genetic approaches to examine BET function in a hematopoietic maturation system driven by GATA1, an acetylated transcription factor previously shown to interact with BETs. We found that while BRD3 occupied the majority of GATA1 binding sites, BRD2 and BRD4 were also recruited to a subset of GATA1-occupied sites. Functionally, BET inhibition impaired GATA1-mediated transcriptional activation, but not repression, genome-wide. Co-activation by BETs was accomplished both by facilitating genomic occupancy of GATA1 and subsequently supporting transcription activation. Using a combination of CRISPR/CAS9-mediated genomic engineering and shRNA approaches we observed that depletion of either BRD2 or BRD4 alone blunted erythroid gene activation, while depletion of BRD3 only affected erythroid transcription in the setting of BRD2 deficiency. These results suggest that pharmacologic BET inhibition should be interpreted in the context of distinct steps in transcriptional activation and partially overlapping functions among BET family members.
Project description:Displacement of Bromodomain and Extra-Terminal (BET) proteins from chromatin has promise for cancer and inflammatory disease treatments, but roles of BET proteins in metabolic disease remain unexplored. Small molecule BET inhibitors, such as JQ1, block BET protein binding to acetylated lysines, but lack selectivity within the BET family (Brd2, Brd3, Brd4, Brdt), making it difficult to disentangle contributions of each family member to transcriptional and cellular outcomes. Here, we demonstrate multiple improvements in pancreatic β-cells upon BET inhibition with JQ1 or BET-specific siRNAs. JQ1 (50-400 nM) increases insulin secretion from INS-1 cells in a concentration dependent manner. JQ1 increases insulin content in INS-1 cells, accounting for increased secretion, in both rat and human islets. Higher concentrations of JQ1 decrease intracellular triglyceride stores in INS-1 cells, a result of increased fatty acid oxidation. Specific inhibition of both Brd2 and Brd4 enhances insulin transcription, leading to increased insulin content. Inhibition of Brd2 alone increases fatty acid oxidation. Overlapping yet discrete roles for individual BET proteins in metabolic regulation suggest new isoform-selective BET inhibitors may be useful to treat insulin resistant/diabetic patients. Results imply that cancer and diseases of chronic inflammation or disordered metabolism are related through shared chromatin regulatory mechanisms.
Project description:Understanding the precise functions and relationship of BRD2 with other bromodomain and extraterminal motif (BET) proteins is central for the application of BET-specific and pan inhibitors. Here, we used acute protein degradation and quantitative genomic and proteomic approaches to investigate the primary functions of BRD2 in transcription. We report that BRD2 is required for TAF3-mediated Pol II initiation at low levels of H3K4me3-modified promoters and Pol II elongation by suppressing R-loops. Single and double depletion revealed that BRD2 and BRD3, but not BRD4, redundantly and independently function in Pol II transcription at different promoters and cooperatively occupy enhancers. Interestingly, we found that depletion of BRD2 affects the expression of different genes during differentiation processes, priming with promoter regulation in ES cells. Therefore, our results suggest complex interconnections between BRD2 and BRD3 at promoters to fine-tune Pol II initiation and elongation for control of cell state.
Project description:Understanding the precise functions and relationship of BRD2 with other bromodomain and extraterminal motif (BET) proteins is central for the application of BET-specific and pan inhibitors. Here, we used acute protein degradation and quantitative genomic and proteomic approaches to investigate the primary functions of BRD2 in transcription. We report that BRD2 is required for TAF3-mediated Pol II initiation at low levels of H3K4me3-modified promoters and Pol II elongation by suppressing R-loops. Single and double depletion revealed that BRD2 and BRD3, but not BRD4, redundantly and independently function in Pol II transcription at different promoters and cooperatively occupy enhancers. Interestingly, we found that depletion of BRD2 affects the expression of different genes during differentiation processes, priming with promoter regulation in ES cells. Therefore, our results suggest complex interconnections between BRD2 and BRD3 at promoters to fine-tune Pol II initiation and elongation for control of cell state.