# The DEAD-box helicase eIF4A1/2 acts as RNA chaperone during mitotic exit enabling chromatin decondensation

## TL;DR

The DEAD-box helicase eIF4A1/2 helps chromatin decondense during mitosis by acting as an RNA chaperone, regulating the perichromatin layer.

## Contribution

eIF4A1/2's RNA chaperone role in chromatin decondensation during mitotic exit is newly identified.

## Key findings

- eIF4A1/2 is crucial for chromatin decondensation in a cell-free assay.
- eIF4A1/2 regulates the perichromatin layer's composition and fluidity.
- Altering eIF4A1/2 levels affects the speed of chromatin decondensation.

## Abstract

During mitosis, chromosomes condense and decondense to segregate faithfully and undamaged. The exact molecular mechanisms are not well understood. We identify the DEAD-box helicase eIF4A1/2 as a critical factor in this process. In a cell-free condensation assay eIF4A1/2 is crucial for this process, relying on its RNA-binding ability but not its ATPase activity. Reducing eIF4A1/2 levels in cells consistently slows down chromatin decondensation during nuclear reformation. Conversely, increasing eIF4A1/2 concentration on mitotic chromosomes accelerates their decondensation. The absence of eIF4A1/2 affects the perichromatin layer, which surrounds the chromosomes during mitosis and consists of RNA and mainly nucleolar proteins. In vitro, eIF4A1/2 acts as an RNA chaperone, dissociating biomolecular condensates of RNA and perichromatin proteins. During mitosis, the chaperone activity of eIF4A1/2 is required to regulate the composition and fluidity of the perichromatin layer, which is crucial for the dynamic reorganization of chromatin as cells exit mitosis.

During mitosis, the chromatin undergoes a dynamic reorganization important for faithful chromosome segregation. Here the authors show that the DEAD-box RNA helicase eIF4A1/2 regulates the perichromatin layer’s composition required for chromatin decondensation during cell division.