Structural heterogeneity and compartmental polarization of human chromosomes
Image credit: UnsplashAbstract
The recent emergence of both theoretical models of chromosome organization have mirrored the development of advanced experimental methods for probing the chromosome structures, such as high-resolution microscopy (DNA tracing). This creates the opportunity to not only make structural predictions using theoretical models, but to examine experimental structures to test our existing models and to formulate new ones. Theory predicts that chromosome structures are fluid and can only be described by statistical ensembles, i.e., there is no unique chromosomal fold. Nevertheless, our analysis of both structures from simulation and microscopy reveals that short segments of gene-rich chromatin make two-state transitions between closed conformations and open conformations. These transitions point to a structure-to-function relationship within the genome. A further examination of the spatial positioning of individual chromosomes in a fully imaged nucleus reveals the importance of chromosome interactions with the nuclear lamina and other nuclear bodies, resulting in the spatial polarization of the chromosomal compartments within a territory.
