Project description:Purpose: 224 GSM Samples form GSE32970 and GSE29692 was reanalyzed to find the TFBS-clustered regions of 133 cell lines. TFBS-clustered regions were divided into ten classes belong to the TF complexity. Methods: 1. We assigned the binding sites of 542 TFs in 133 cell lines as our record GSE53962 . 2. We performed a Gaussian kernel density estimation across the genome with a bandwidth of 300 bp, using the centers of each of the TF binding peaks as points. Then, we scanned this density for peaks, and denoted each peak a TF region.To determine the complexity of the TF region, we summed the Gaussian kernalized distance from the peak to each TF that contributed at least 0.1 to its strength. The TF region around eat peak was derived by finding the maximum distance (in bp) from the peak to a contributing TF, and then adding 150 bp (one half of the bandwidth). Each TF region is centered on the peak, and have a TF complexity value. 3. According to TFBS complexity, we divided these TFBS-clustered regions into ten classes: from TC0 to TC9 with increasing TFBS complexity. Result: Using the binding sites of 542 TFs in 133 cell lines, we assigned a TF complexity score to each TF region corresponding to the number of distinct TFs bound, resulting in ten classes TFBS-clustered regions of 133 cell lines.
Project description:Average hydroxymethylation levels on transcription factor binding sites obtained from ENCODE (ChIP-sequencing of GM12878 lymphoblastoid cell line). Data from 6 individuals at different time points.
Project description:The goal of this study is to identify the effect of the transcription factor STAT3 in the two major subtypes of diffuse large B cell lymphoma (DLBCL). STAT3 is a signal transducer that, when dysregulated, becomes a powerful oncogene found in many human cancers, including DLBCL. DLBCL is the most common form of non-Hodgkin’s lymphoma and has two major subtypes: germinal center B-cell-like (GCB) and activated B-cell-like (ABC). When compared to the GCB form, ABC lymphomas respond much more poorly to current therapies and often exhibit overexpression or overactivation of STAT3. To investigate how STAT3 might contribute to this aggressive phenotype, we have used ChIP-Seq to identify STAT3 binding sites in 8 DLBCL cell lines (4 GCB subtype, 4 ABC) that are derived from patient tumors. 10,337 distinct STAT3 binding regions are occupied in at least two of the eight cell lines. One third (n = 3524) are differentially bound by STAT3 between the two subtypes (FDR < 0.05). More BRs are strongly bound in ABC than in GCB: 44% of differentially bound BRs (n = 1550) show more STAT3 binding in GCB, while 56% (n = 1974) are more strongly bound in ABC. Identification and comparison of STAT3 transcription factor binding sites in 8 cell lines that represent the 2 subtypes of DLBCL. 4 cell lines are subtyped as ABC and 4 are subtyped as GCB. 2-9 replicates and 1 input control are present for each cell line. (Cell line OCI-Ly19 was not included in the final analysis because RNA-Seq showed that its gene expression clustered in between the subtypes, probably due to its EBV+ status. However, its peak calls were used in intermediate steps of the analysis pipeline. Its sequencing runs have been included for completeness.)
Project description:Pervasive usage of alternative promoters leads to deregulation of gene expression in carcinogenesis and may drive the emergence of new genes in spermatogenesis. However, little is known regarding the mechanisms underpinning the activation of alternative promoters. In our present study, we uncovered a novel mechanism by which alternative cancer-testis-specific transcription is activated from the intergenic and intronic clustered CTCF binding sites, which are transcriptionally inert in normal somatic cells. BORIS/CTCFL, a paralog of CTCF with cancer-testis-specific expression forms a heterodimer with CTCF at the clustered binding sites thus triggering epigenetic reprogramming of these sites into units of active transcription. BORIS binding to CTCF sites leads to the recruitment of chromatin-remodeling factor SRCAP, with subsequent replacement of H2A histone with H2A.Z, therefore creating a more relaxed chromatin state in the nucleosomes flanking the clustered binding sites. This facilitates opening of chromatin beyond CTCF/BORIS binding sites and paves the way to the recruitment of multiple additional transcription factors, thereby activating transcription from a given binding site. We demonstrate that the CTCF binding sites, epigenetically reprogrammed by ectopic BORIS expression can drive the expression of cancer-testis genes, long-noncoding RNAs, retro-pseudogenes, and dormant transposable elements harbored by activated long transcripts. Taking together, our results reveal that BORIS functions as a transcription factor that epigenetically reprograms clustered CTCF binding sites into transcriptional start sites, promoting transcription from alternative promoters in both germ cells and cancer cells.