# Stress-induced nucleolar rejuvenation via chaperone-mediated segregation in a filamentous fungus

## TL;DR

Heat stress helps fungi clean up their cell nuclei by separating damaged parts from new ones during cell division.

## Contribution

A novel chaperone-mediated nucleolar segregation mechanism in multinucleate fungal cells is revealed.

## Key findings

- Heat stress triggers nucleolar remodeling in filamentous fungi.
- A chaperone-mediated pathway selectively partitions rejuvenated and damaged nucleolar compartments.
- This mechanism preserves nuclear function in polarized, multinucleate cells.

## Abstract

Rogers et al. demonstrate that heat stress triggers nucleolar remodeling in filamentous fungi, enabling segregation of damaged material and selective inheritance of a new nucleolar compartment. This reveals a chaperone-mediated quality control mechanism that preserves nuclear function in highly polarized, multinucleate cells.

How the nucleolus recovers from acute proteostatic stress, particularly in multinucleate syncytia, remains poorly understood. In the highly polarized hyphae of the model filamentous fungus Magnaporthe oryzae, we uncover a novel stress-induced spatial quality control pathway that promotes the inheritance of rejuvenated nucleolar material during nuclear division. This pathway discriminates between newly formed and damaged nucleolar compartments, selectively partitioning and sequestering the latter. Our findings reveal a previously unrecognized mechanism for chaperone-mediated segregation of a membraneless nuclear organelle, extending principles of protein quality control to the unique demands of highly polarized syncytia.