Dynamics of chromatin accessibility and epigenetic state in response to UV damage

Epigenetic mechanisms determine the access of regulatory factors to DNA during events such as transcription and DNA damage response. However, the global response of histone modifications and chromatin accessibility to UV exposure remains poorly understood. Here, we report that UV exposure results in a genome-wide reduction in chromatin accessibility, while the distribution of the active regulatory mark H3K27ac undergoes massive reorganization. Genomic loci subjected to epigenetic reprogramming upon UV represent target sites of sequence-specific transcription factors. Most of these are distal regulatory regions, highlighting their importance in the cellular response to UV exposure. Furthermore, UV exposure results in an extensive reorganization of super-enhancers accompanied by expression changes of associated genes partly important for stress response. Taken together, our study provides the first comprehensive resource for genome-wide chromatin changes upon UV irradiation in relation to gene expression and elucidates novel aspects of this relationship.