FIGURE 1.

The 3D organization of chromatin. (A) Schematic representation of the arrangement of chromosomes in nucleus, all chromosomes are in contact with the nuclear envelop i.e., the nuclear lamina. Each chromosome resides in its territory (multicolor areas), but there are areas of overlapping. (B) Schematic illustration of Hi-C maps at the genomic scale of chromosomes. When compared to inter-chromosomal connections, intra-chromosomal interactions are found to be more prevalent. (C) Chromatin is organized in “A” (yellow) and “B” (green) compartments, with “B” compartments being at the nuclear lamina. (D) Schematic illustration of Hi-C maps at the compartmental scale, where distal chromatin contacts generate a distinctive plaid pattern with A and B compartments. (E) TADs are formed via loop extrusion, and architectural proteins are found near the TAD boundaries. Within each TAD, cohesin-mediated loops contribute in chromatin folding. (F) Schematic illustration of Hi-C maps at the sub-megabase scale, TADs appear as interaction-rich triangles separated by TAD borders. Through loops, enhancers are brought into closer to the promoters that they control.