Edoardo Marchi — Università degli Studi di Milano #
Modelling chromosomes dynamics: how loop-extrusion impacts chromatin self-interaction #
Contacts between genomic loci of the chromatin fibre are essential for the control of genetic expression, yet the mechanistic details of these interactions are not completely understood. Loop extrusion by motor proteins like cohesin mediates the attractive interactions in chromatin on the length scale of megabases, providing the polymer with a well-defined structure and at the same time determining its dynamics. Their duration can be observed in living cells by time–lapse fluorescence microscopy, although with limited spatial and temporal resolution. Combining simulations with simple analytical models, we show how to obtain important information about the mechanism of stabilisation of contacts by cohesin from the two–dimensional dynamics of the system on the focal plane. In particular, we find estimations of the relevant distance at which a cohesin-mediated contact occurs and of the cohesin velocity along the chain.