# Spatial Chromatin Organization Across the Cell Cycle: Insights from Auxin-Inducible Protein Depletion

## TL;DR

This review explores how chromatin structure changes during the cell cycle using a system that allows rapid protein depletion.

## Contribution

The paper highlights new insights into chromatin organization and the roles of specific proteins during the cell cycle.

## Key findings

- Cohesin and condensins are essential for chromatin structure and chromosome organization.
- AID-based studies reveal how chromatin proteins reshape the mitotic-to-interphase transition.
- TOP2A, KIF4A, and SRBD play key roles in mitosis as shown through inducible degradation.

## Abstract

Many cellular processes, including gene expression regulation, DNA replication and repair, as well as proper condensation and segregation of chromosomes, require highly coordinated remodeling of chromatin. Cohesin and condensins, the structural maintenance of chromosomes (SMC) protein complexes that function as ATP-powered loop extrusion motors, are key determinants of chromatin structure. The genetic loss of their function is lethal, whereas inducible degradation approaches enable rapid, robust analysis of the depletion phenotype. In this review, we discuss new insights into chromatin folding through each cell cycle phase from the auxin-inducible degradation (AID) system. We review the mechanisms by which condensins and cohesins contribute to the helical organization of mitotic chromosomes and to the maintenance of chromosome territories in interphase. Additionally, we discuss studies examining the roles of TOP2A, KIF4A, and SRBD during mitosis using the AID system. We then outline emerging principles of the mitotic-to-interphase transition and how targeted degradation of chromatin proteins reshapes this process. Finally, we highlight and discuss new advances in understanding interphase chromatin organization revealed by AID-based studies.