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Histone acetylation dynamics modulate chromatin conformation and allele-specific interactions at oncogenic loci (RNASeq)

ABSTRACT: In cancer cells, enhancer hijacking mediated by chromosomal alterations and/or increase of histone H3 lysine 27 acetylation (H3K27ac) can support oncogene expression. However, how the chromatin conformation of enhancer-promoter interactions is affected by these events is unclear. Here, by comparing chromatin structure and H3K27ac levels in normal and lymphoma B-cells, we show that enhancer-promoter interacting regions assume different conformations according to the local abundance of H3K27ac. Genetic or pharmacologic depletion of H3K27ac decreases the frequency and the spreading of these interactions, altering oncogene expression. Moreover, enhancer hijacking mediated by chromosomal translocations influences the epigenetic status of the regions flanking the breakpoint, prompting the formation of distinct intra-chromosomal interactions in the two homologous chromosomes. These interactions are accompanied by allele-specific gene expression changes. Overall, our work indicates that H3K27ac dynamics modulate interaction frequency between regulatory regions and can lead to allele-specific chromatin configurations to sustain oncogene expression.

ORGANISM(S): Homo sapiens

PROVIDER: GSE168471 | GEO | 2021/03/09

REPOSITORIES: GEO

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Histone acetylation dynamics modulate chromatin conformation and allele-specific interactions at oncogenic loci (ChIPSeq)

Project description:In cancer cells, enhancer hijacking mediated by chromosomal alterations and/or increase of histone H3 lysine 27 acetylation (H3K27ac) can support oncogene expression. However, how the chromatin conformation of enhancer-promoter interactions is affected by these events is unclear. Here, by comparing chromatin structure and H3K27ac levels in normal and lymphoma B-cells, we show that enhancer-promoter interacting regions assume different conformations according to the local abundance of H3K27ac. Genetic or pharmacologic depletion of H3K27ac decreases the frequency and the spreading of these interactions, altering oncogene expression. Moreover, enhancer hijacking mediated by chromosomal translocations influences the epigenetic status of the regions flanking the breakpoint, prompting the formation of distinct intra-chromosomal interactions in the two homologous chromosomes. These interactions are accompanied by allele-specific gene expression changes. Overall, our work indicates that H3K27ac dynamics modulate interaction frequency between regulatory regions and can lead to allele-specific chromatin configurations to sustain oncogene expression.

2021-03-09 | GSE168472 | GEO

Histone acetylation dynamics modulate chromatin conformation and allele-specific interactions at oncogenic loci (Hi-C)

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Genome-wide detection of enhancer-hijacking events from chromatin interaction data in rearranged genomes

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Regulation of Histone Acetylation by SUMOylation Through TFAP2C Binding to the Chromatin and Recruitment of HDAC Complex

Project description:Enhancers are fundamental to gene regulation. Post-translational modifications by the small ubiquitin-like modifiers (SUMO) modify chromatin regulation enzymes, including histone acetylases and deacetylases. However, it remains unclear whether SUMOylation regulates enhancer marks, acetylation at the 27th lysine residue of the histone H3 protein (H3K27Ac). We hypothesize that SUMOylation regulates H3K27Ac. To test this hypothesis, we performed genome-wide ChIP-seq analyses. We discovered that knockdown (KD) of the SUMO activating enzyme catalytic subunit UBA2 reduced H3K27Ac at most enhancers. Bioinformatic analysis revealed that TFAP2C-binding sites are enriched in enhancers whose H3K27Ac was reduced by UBA2 KD. ChIP-seq analysis in combination with molecular biological methods showed that TFAP2C binding to enhancers increased upon UBA2 KD or inhibition of SUMOylation by a small molecule SUMOylation inhibitor. However, this is not due to the SUMOylation of TFAP2C itself. Proteomics analysis of TFAP2C interactome on the chromatin identified histone deacetylation (HDAC) machinery. TFAP2C KD reduced HDAC binding to chromatin and increased H3K27Ac marks at enhancer regions, suggesting that TFAP2C is involved in recruiting HDAC. Taken together, our findings provide important insights into regulation of enhancer marks by SUMOylation.

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Convergent evolution of complex regulatory landscapes and pleiotropy at Hox loci (tiling)

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2024-04-02 | GSE228246 | GEO

3D genomics analysis identifies enhancer hijacking caused by structural alterations and extrachromosomal circular DNA formation [ChIP-Seq]

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3D genomics analysis identifies enhancer hijacking caused by structural alterations and extrachromosomal circular DNA formation [RNA-Seq]

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Epigenetic modulation of a hardwired 3D chromatin landscape in two naive states of pluripotency. (4C-seq)

Project description:The mechanisms underlying enhancer activation and the extent to which enhancer-promoter rewiring contributes to spatiotemporal gene expression are not well understood. Using integrative and time resolved analyses we show that the extensive transcriptome and epigenome resetting during the conversion between ‘serum-’ and ‘2i’-states of mouse embryonic stem cells (ESCs) takes place with minimal enhancer-promoter rewiring that becomes more evident in primed-state pluripotency. Instead, differential gene expression is strongly linked to enhancer activation via H3K27ac. Conditional depletion of TFs and allele-specific enhancer analysis reveals an essential role for Esrrb in H3K27-acetylation and activation of 2i-specific enhancers. Restoration of a polymorphic ESRRB motif using CRISPR/Cas9 in a hybrid ESC-line, restores ESRRB binding and enhancer H3K27ac in an allele-specific manner but has no effect on chromatin interactions. Our study shows that enhancer activation in serum- and 2i-ESCs is largely driven by TF-binding and epigenetic marking in a hardwired network of chromatin interactions.

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