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 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: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: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: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:We detected an interaction between checkpoint kinase Chk2 and some members of the NCOR/SMRT co-repressor complex. In order to study the role of gene repression in the checkpoint response to DNA damage, we performed RNA profiling in NCOR or SMRT knockdown cells after treztment with cisplatin. U2OS cells were transfected with siRNAs for NCOR or SMRT, grown for 2 days in complete medium, and then treated with 100 microM cisplatin (CDDP) for 6h. Biological duplicates were used for RNa profiling
Project description:We detected an interaction between checkpoint kinase Chk2 and some members of the NCOR/SMRT co-repressor complex. In order to study the role of gene repression in the checkpoint response to DNA damage, we performed RNA profiling in NCOR or SMRT knockdown cells after treztment with cisplatin.
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: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.
Project description:The thyroid hormone receptor (TR) has been proposed to regulate target genes in the absence of triiodothyronine (T3), through the recruitment of the corepressors, NCoR and SMRT. NCoR and SMRT may thus play a key role in both hypothyroidism and resistance to thyroid hormone, though this has never been tested in vivo. To accomplish this we developed mice that express in the liver a NCoR protein (L-NCoR∆ID) that cannot interact with the TR. L-NCoR∆ID mice develop normally, however when made hypothyroid the repression of many positively regulated T3-target genes is abrogated, demonstrating that NCoR plays a specific and sufficient role in repression by the unliganded TR. Remarkably, in the euthyroid state, expression of many T3-targets are also upregulated in L-NCoR∆ID mice, demonstrating that NCoR also determines the magnitude of the response to T3 in euthyroid animals. While positive T3 targets were upregulated in L-NCoR∆ID mice in the hypo and euthyroid state there was less effect seen on negatively regulated T3 target genes. Thus, NCoR is a specific regulator of T3-action in vivo and mediates the activity of the unliganded TR. Furthermore, NCoR may play a key role in determining the differences in individual responses to similar levels of circulating T3. Keywords: NCoR, thyroid hormone signaling, mouse liver, DNA Microarray To better assess the role of NCoR in positive and negative regulation we performed micorarray analysis of gene expression in the livers of euthyroid and hypothyroid control and L-NCoR∆ID mice.