The effect of mechanical forces on gene expression has been a primary focus of the emerging field of mechanobiology for the past few decades. As the organelle that contains the chromatin, the physical response of the cell nucleus to forces is of fundamental importance to its mechanosensitivity and was investigated by a number of methods, including micropipette aspiration, atomic force microscopy, stretching, and compression assays. These experiments led to the current understanding that contributions from the nuclear lamina and the chromatin dominate the mechanical properties and dynamical response of the nucleus. However, recent studies highlight the osmotic pressure of actively transported proteins, a non-structural component of the cell and nucleus that is commonly overlooked in the nuclear-mechanics field, as a key factor in determining nuclear volume and its dynamics. Here, we consider theoretically the contribution of osmotic pressures exerted by actively transported proteins to the mechanical properties of the nucleus, as well as the interplay between the dynamics of nucleoplasmic transport, which determines these properties, and mechanically induced nuclear deformation. Our model demonstrates that incorporating these effects into the modeling of nuclear mechanics can give rise to additional modes of nuclear response to mechanical perturbations.
Mandal et al. (Sun,) studied this question.