Interphase chromatin biophysics and mechanics: new perspectives and open questions.

The physical organization and properties of chromatin within the interphase nucleus are intimately linked to a wide range of functional DNA-based processes. In this context, interphase chromatin mechanics - that is, how chromatin, physically, responds to forces - is gaining increasing attention. Recent methodological advances for probing the force-response of chromatin in cellulo open new avenues for research, as well as new questions. This review discusses emerging views from these approaches and others, including recent in vitro single-molecule studies of cohesin and condensin motor activities, providing insights into physical and material aspects of chromatin, its plasticity in the context of functional processes, its nonequilibrium or 'active matter' properties, and the importance of factors such as chromatin fiber tension and stiffness. This growing field offers exciting opportunities to better understand the interplay between interphase chromosome structure, dynamics, mechanics, and functions.