Speaker
Description
Physical spacing of chromatin is critical in regulating bio-chemical and transcriptional abilities of genes, and proper functionality of the genomic content depends on the nonrandom organization of chromatin. Meanwhile, in a living cell, other subnuclear molecules, such as enzymes like polymerase and topoisomerase, act to facilitate cellular functions. Mechanical perturbation due to actions of such molecules may affect the chromatin organization and dynamics. In this talk, I would like to explain our numerical-simulation studies, based on polymer-physics concepts, where we focused on a type of actions of molecules that we call catch-and-release action and implemented in the way inspired by a class of molecules like topoisomerase-II. I will share with the participants the results of our simulations on how it affects chromatin organization and dynamics. The results clarified (i) that the mechanical perturbation of such actions can modulate the phase separation organizations of chromatin called heterochromatic and euchromatic regions [1], and (ii) that the mechanical perturbation enhances fluctuating dynamics of inclusions in chromatin through the newly-identified dynamic mode of chromatin remodeling [2]. --- References: [1] R Das, T Sakaue, GV Shivashankar, J Prost, T Hiraiwa (2022) "How enzymatic activity is involved in chromatin organization", eLife 11, e79901; [2] R Das, T Sakaue, GV Shivashankar, J Prost, T Hiraiwa (2024) “Chromatin Remodeling Due to Transient-Link-and-Pass Activity Enhances Subnuclear Dynamics", Physical Review Letters 132, 058401.
