Nuclear dynamical deformation induced hetero- and euchromatin positioning

TL;DR

This study uses Brownian dynamics simulations to explore how active nuclear deformation influences the spatial organization of heterochromatin and euchromatin, revealing mechanisms behind their typical and inverted nuclear positioning.

Contribution

It introduces a model linking nuclear deformation dynamics to chromatin positioning, explaining both conventional and inverted arrangements in different cell types.

Findings

Low mobility regions move from periphery to center when affinity decreases.

Model reproduces both conventional and inverted chromatin positioning.

Nuclear deformation dynamics significantly influence chromatin organization.

Abstract

The contributions of active deformation dynamics in cell nuclei to the intra-nuclear positioning of hetero- and euchromatin are investigated. We analyzed the behaviors of model chains containing two types of regions, one with high and the other with low mobility, confined in a pulsating container. Here, the regions with high and low mobility represent eu- and heterochromatic regions, respectively, and the pulsating container simulates a nucleus exhibiting dynamic deformations. The Brownian dynamics simulations of this model show that the positioning of low mobility regions transition from sites near the periphery to the central region of the container if the affinity between low mobility regions and the container periphery disappears. Here, the former and latter positioning are similar to the "conventional" and "inverted" chromatin positioning observed in nuclei of normal differentiated cells and cells lacking Lamin-related proteins like mouse rod photoreceptor cell.