"Protection of genome integrity is crucial for maintaining cell viability and preventing cancer. However, how the dynamic organisation of DNA into chromatin in the cell nucleus is orchestrated in order to allow and promote detection and repair of DNA lesions remains poorly understood. A controlled accessibility of damaged chromatin is likely critical for an efficient cellular response to DNA damage, but underlying molecular mechanisms enabling this regulation have to be deciphered. In this proposal, we describe how we will combine established techniques and a novel approach based on FLIM-FRET microscopy to quantitatively visualise chromatin compaction/decompaction in human cells and to analyse how this is regulated during the response to genotoxic stress. First, we will examine the spatio-temporal dynamics of chromatin re-organisation upon global or localised DNA damage. Then, we plan to characterise the factors involved in each step, with a particular focus on chromatin remodeling factors, in order to determine their exact functional importance for DNA damage signaling and repair. This study should provide mechanistic insight into how genome integrity is preserved in a chromatin context."