[Bioinformatics analysis of Alu components at the level of genome 3D structure]

The interphase chromatin is folded in the nucleus in a hierarchical manner, including the nucleosome, the "beads on a string" structure composed of nucleosomes, the solenoid fiber structure, the chromatin/DNA loop structure (chromatin/DNA loop), and the topologically associated domain (TAD). Among them, TAD is considered to be the basic unit of the 3D structure of chromatin because it is relatively stable and conserved in different cell types. Alu elements occupy a large proportion in the mammalian genomes. There are a wide variety of Alu elements, but their functional characterizations are limited to date. This study investigates the role of Alu elements in the assembly of 3D chromatin conformation. The evolutionary process of the Alu subfamily was explored by the distance relationship of the 3D structure of chromatin. We found that the proportion of Alu elements in high-density chromatin interaction increased with higher similarity, indicating that Alu plays an important role in the construction of chromatin 3D structure. There is a certain positive correlation between the strength of the upper interaction and the evolutionary relationship. In sum, the Alu elements with relatively close distances in the 1D sequence will also be close to each other in the 3D structure of chromatin.