Promoter capture Hi-C identifies long-range promoter contact dynamics in response to diet and the development of non-alcoholic fatty liver disease
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ABSTRACT: Promoter capture Hi-C identifies long-range promoter contact dynamics in response to diet and the development of non-alcoholic fatty liver disease
Project description:Genome organisation determines chromosome interactions between regulatory elements, such as promoters and enhancers, influencing gene expression. Despite the fact that it is possible to assess whether a gene is actively transcribed, it has been challenging to point out the genomic regions that are involved in the regulation of a particular gene. We are interested in better understanding the interactions between promoters and their regulatory elements in colorectal cancer in order to unveil novel non-coding regions which might have a role in tumour development. To do so, we utilise the HiC method complemented with promoter capture in combination with NGS to map promoter interactions in two CRC cell lines, representing two distinct CRC subtypes.
Project description:Chromatin organisation of trophoblast stem cells (TSC) were compared with that of embryonic stem cells (ESC). The method enriches Hi-C libraries, to detect promoter interactions at restriction fragment level. We prepared Hi-C libraries from TSC and ESC (serum grown) samples and enriched them with a promoter capture bait system that captures ~22.000 promoters. Promoter interactions were then analysed using the GOTHiC pipeline.
Project description:Enhancers are DNA sequences that enable complex temporal and tissue-specific regulation of genes in higher eukaryotes. Although it is not entirely clear how enhancer-promoter interactions can increase gene expression, this proximity has been observed in multiple systems at multiple loci and is thought to be essential for the maintenance of gene expression. Bromodomain and Extra-Terminal domain (BET) and Mediator proteins have been shown capable of forming phase condensates and are thought to be essential for super-enhancer function. Here, we show that targeting of cells with inhibitors of BET proteins or pharmacological degradation of BET protein Bromodomain-containing protein 4 (BRD4) has a strong impact on transcription but very little impact on enhancer-promoter interactions. Dissolving phase condensates reduces BRD4 and Mediator binding at enhancers and can also strongly affect gene transcription, without disrupting enhancer-promoter interactions. These results suggest that activation of transcription and maintenance of enhancer-promoter interactions are separable events. Our findings further indicate that enhancer-promoter interactions are not dependent on high levels of BRD4 and Mediator, and are likely maintained by a complex set of factors including additional activator complexes and, at some sites, CTCF and cohesin.
Project description:CD34+ heamatopoietic stem cells were isolated from the bone marrow of two healthy donors undergoing total hip replacement. Promoter capture Hi-C (PCHi-C) was performed on these cells using the protocol according to Mifsud et al. 2015, with the exception that ligation was performed in situ, and a slightly modified bait capture set was used. Bait positions in hg19 are included as an additional file.