Chromatin Dynamics and 3D Genome Organization Shape Gene Expression
Chromatin organizes DNA inside the nucleus. It packs tightly yet stays dynamic. Loops form. Folds emerge. These structures control gene activity.
First, DNA wraps around histones. Nucleosomes build up. They create bead-like strings. However, higher-order folding follows next.
Topologically associating domains (TADs) appear. They group nearby genes. Interactions stay strong within TADs. Meanwhile, cross-TAD contacts weaken.
Cohesin loads onto chromatin. It extrudes loops. CTCF proteins anchor boundaries. Together, they sculpt the 3D architecture.
Enhancers reach distant promoters. Loops bring them close. Transcription activates quickly. Conversely, insulation blocks unwanted contacts.
Cells change chromatin during development. Differentiation triggers remodeling. Compartments switch from active A to silent B types.
Moreover, diseases disrupt this organization. Cancer cells show altered TADs. Mutations hit CTCF sites. Gene misexpression follows.
Researchers use Hi-C techniques. They map contacts genome-wide. Single-cell Hi-C reveals variation. Polymer models simulate folding.
Phase separation aids organization. Proteins condense into hubs. Transcription factories cluster active genes.
CMP Bio World 