Optogenetic probing of the 4D genome – Opto4D

The spatial organization and dynamics of chromosomes is highly organized and regulated in the cell nucleus. For example, when a double-strand DNA break occurs, cells modify the mechanical properties of the chromatin fiber in a way that increases its mobility in the nuclear space and facilitates repair. Yet, studying chromosome mechanics and dynamics at high temporal resolution requires costly and demanding efforts. Important questions therefore remain unanswered: What are the in vivo physical properties of the chromatin fiber in a given physiological condition? How are these properties regulated by biochemical modifications of the chromatin? How do they evolve during fundamental biological processes such as DNA repair? We have recently developed technologies allowing precise manipulations of chromosomes with light. This opens the possibility to probe genome folding dynamically, at high temporal resolution and relatively low cost. We propose an interdisciplinary approach that will combine these technologies with biophysical modeling, powerful genetics experiments and DNA sequencing in order to characterize the fundamental mechanical properties of 3D genome organization during the process of DNA repair.