Project description:This SuperSeries is composed of the following subset Series: GSE27001: Inhibition of Bcl6-SMRT/NCoR interactions by an inhibitory peptide affects inflammatory pathways GSE27033: Genome-wide location analysis of SMRT and NCoR in wild-type and Bcl6 knockout macrophages Refer to individual Series
Project description:Using ChIP-seq, we reveal the SMRT and NCoR co-repressor cistromes, which each consist of over 30,000 half-shared binding sites. Moreover, we identify Bcl6-bound sub-cistromes for each co-repressor, which are strongly concentrated on NF-κB-driven inflammatory and tissue remodeling genes. These results reveal a critical role for Bcl6 and its corepressors SMRT and NCoR in the prevention of atherosclerosis and chronic inflammation. Identification of SMRT and NCoR binding sites in wild-type and Bcl6 knockout primary bone-marrow derived macrophages
Project description:Using microarrays, we compared the changes in levels of gene expression between wild type mouse bone marrow derived macrophages upon treatment with the Bcl6 peptide inhibitor, RI-BPI, that specifically blocks interaction between BCL6 and the co-repressors NCoR or SMRT.
Project description:Using microarrays, we compared the changes in levels of gene expression between wild type mouse bone marrow derived macrophages upon treatment with the Bcl6 peptide inhibitor, RI-BPI, that specifically blocks interaction between BCL6 and the co-repressors NCoR or SMRT. Total RNA was obtained from cultered wild type primary bone marrow-derived macrophages that were treated with either 5 μM control or RI-BPI peptide in MSF media for 12 hours.
Project description:Using ChIP-seq, we reveal the SMRT and NCoR co-repressor cistromes, which each consist of over 30,000 half-shared binding sites. Moreover, we identify Bcl6-bound sub-cistromes for each co-repressor, which are strongly concentrated on NF-κB-driven inflammatory and tissue remodeling genes. These results reveal a critical role for Bcl6 and its corepressors SMRT and NCoR in the prevention of atherosclerosis and chronic inflammation.
Project description:BCL6 is crucial for B-cell activation and lymphomagenesis. We used integrative genomics to explore BCL6 mechanism in normal and malignant B-cells. Surprisingly, BCL6 assembled distinct complexes at enhancers vs. promoters. At enhancers BCL6 preferentially recruited SMRT, which mediated H3K27 deacetylation through HDAC3, antagonized p300 activity and repressed transcription, but without decommissioning enhancers. This provides a biochemical basis for toggling enhancers from the active to poised state. Virtually all SMRT was bound with BCL6 suggesting that in B-cells BCL6 uniquely sequesters SMRT from other factors. In promoters BCL6 preferentially recruited BCOR, but most potently repressed promoters where it formed a distinctive ternary complex with SMRT and BCOR. Promoter repression was associated with decreased H3K36me3, H3K79me2 and Pol II elongation, linking BCL6 to transcriptional pausing. We identified the binding patterns of BCL6, SMRT, NCOR and BCOR corepressors in normal germinal center B cells and a DLBCL cell line (OCI-Ly1) using ChIP-seq. Additionally we treated lymphoma cells with siRNA against BCL6 and a non-targeted siRNA (NT control) and performed RNA-seq to identify the genes bound and repressed by BCL6. RNA-seq experiments were performed at 24h and 48h after siRNA treatments. Additional biological triplicate RNA-seq experiments were performed at 48h after BCL6 knockdown. Furthermore, a series of histone mark ChIP-seq and RNA polymerase ChIP-seq (total, Ser5-P and Ser2-P) were preformed to capture the chromatin states associated with the formation of BCL6 corepressor complexes.
Project description:We used microarrays to compare gene expression changes in macrophages caused by deletion of bcl6. Keywords: BCL6 deletion compared to wild-type Primary bone marrow-derived macrophages were isolated from C57BL/6 mice transplanted and reconstituted with wild type or bcl6 knockout bone marrow.
Project description:Changing the somatic cell transcriptome to a pluripotent state using exogenous reprogramming factors needs transcriptional co-regulators that help activate or suppress gene expression and rewrite the epigenome. Here, we show that reprogramming-specific engagement of the NCoR/SMRT co-repressor complex at key pluripotency loci creates an epigenetic block to reprogramming. HDAC3 executes the repressive function of NCoR/SMRT in reprogramming by inducing histone deacetylation at these loci. Recruitment of NCoR/SMRT-HDAC3 to pluripotency genes is facilitated by all 4 Yamanaka factors (OCT4, SOX2, KLF4 and c-MYC) but mostly by c-MYC. Class IIa HDACs further potentiate this recruitment by interacting with both the reprogramming factors and NCoR/SMRT. Consequently, depleting NCoR/SMRT-HDAC3 function enables high efficiency of reprogramming, while elevating NCoR/SMRT-HDAC3 recruitment at pluripotency loci by over-expressing constitutively active class IIa HDACs derails it. Our findings thus uncover an unexpected epigenetic mechanism involving c-MYC, whose manipulation greatly enhances reprogramming efficiency.
Project description:Changing the somatic cell transcriptome to a pluripotent state using exogenous reprogramming factors needs transcriptional co-regulators that help activate or suppress gene expression and rewrite the epigenome. Here, we show that reprogramming-specific engagement of the NCoR/SMRT co-repressor complex at key pluripotency loci creates an epigenetic block to reprogramming. HDAC3 executes the repressive function of NCoR/SMRT in reprogramming by inducing histone deacetylation at these loci. Recruitment of NCoR/SMRT-HDAC3 to pluripotency genes is facilitated by all 4 Yamanaka factors (OCT4, SOX2, KLF4 and c-MYC) but mostly by c-MYC. Class IIa HDACs further potentiate this recruitment by interacting with both the reprogramming factors and NCoR/SMRT. Consequently, depleting NCoR/SMRT-HDAC3 function enables high efficiency of reprogramming, while elevating NCoR/SMRT-HDAC3 recruitment at pluripotency loci by over-expressing constitutively active class IIa HDACs derails it. Our findings thus uncover an unexpected epigenetic mechanism involving c-MYC, whose manipulation greatly enhances reprogramming efficiency.