Chromatin dynamics

Abstract

The expression patterns of many protein-coding genes are orchestrated in response to exogenous stimuli, as well as cell-type-specific developmental programs. In recent years, researchers have shown that dynamic chromatin movements and interactions in the nucleus play a crucial role in gene regulation. In this review, we highlight our current understanding of the organization of chromatin in the interphase nucleus and the impact of chromatin dynamics on gene expression. We also discuss the current state of knowledge with regard to the localization of active and inactive genes within the three-dimensional nuclear space. Furthermore, we address recent findings that demonstrate the movements of chromosomal regions and genomic loci in association with changes in transcriptional activity. Finally, we discuss the role of intra- and interchromosomal interactions in the control of coregulated genes.

Figure 1

Projections of mid-optical sections of human fibroblast nuclei that highlight chromosome territories. Three (a) and all 23 (b) pairs of chromosomes were detected using 3D-FISH with chromosome paint probes obtained by flow-sorting. Individual chromosomes are indicated. Image in panel a courtesy of Irina Solovei. Image in panel b courtesy of Andreas Bolzer and Irina Solovei, University of Munich, Germany.

Figure 2

(a) Chromosomes are organized into territories in the interphase nucleus. (b) Gene-rich chromosomes assume more interior positions in the nucleus, whereas gene-poor chromosomes are more peripheral. (c) Actively transcribed genes tend to locate at the surface of chromosome territories. Coregulated genes can form intra- and interchromosomal contacts and colocalize with foci rich in proteins involved in transcription and splicing. (d) Intra- and interchromosomal associations play a role in the regulation of gene expression by bringing enhancers in contact with protein coding genes.