Browsing by Subject "super-enhancer"

Enhancers are important regulatory elements of DNA, that are bound by transcription factors (TFs) to regulate gene expression. Enhancers control cell type specific gene expression and they can form structures called super-enhancers, that consist of multiple normal enhancers and are bound by high numbers and variety of transcription factors. These super-enhancers are important for defining cell identity and changes in the super-enhancer landscape have been linked to different cancers. In this project, characterization of super-enhancers and their transcription factors composition between primary and cancer cells were studied using genome-wide next-generation sequencing data from multiple assays, such as ChIP-seq, RNA-seq and ATAC-seq. The focus of the project was on the data processing and analysis to identify and characterize the super-enhancers. Analyses included GSEA, heatmap binding analysis, peak and super-enhancer calling and IGV analysis. This project used pancreatic HPDE cell line for primary cells and different cancers with endodermal origin as cancer cell lines. The goal of the thesis was to try show characteristic features of super-enhancers and their features in normal and cancer cells. Data analysis showed that distinct super-enhancers can be identified in cancer cells and defined super-enhancers had typical strong binding for specific transcription factor and histone modification such as histone 3 lysine 27 acetylation (H3K27ac) mark of active enhancers. Super-enhancer regions were located in highly accessible chromatin regions of the genome, and genes that were associated with HPDE super-enhancers could be shown to have association with cell identity. Peak and super-enhancer calling counts varied between cell lines for transcription factors, histone modifications and super-enhancers. Visualization of super-enhancers was successful and could show transcription factor binding and active enhancers that establish the super-enhancer structure. Comprehensive analyses allowed us to characterize typical features of super-enhancers and show differences in the numbers of super-enhancers between primary and cancer cell lines and cancer cell lines of different organ types. Analysis of the transcription factor binding showed unique peaks on some of the super-enhancers, and these peaks might have a role in inducing the super-enhancer structure.