Reference - PMID:39473973 - Limiting 20S proteasome assembly leads to unbalanced nucleo-cytoplasmic distribution of 26S/30S proteasomes and chronic proteotoxicity.

Reference summary

PubMed ID

PMID:39473973

Title

Limiting 20S proteasome assembly leads to unbalanced nucleo-cytoplasmic distribution of 26S/30S proteasomes and chronic proteotoxicity.

Authors

Ruiz-Romero G, Berdún MD, Hochstrasser M, Salas-Pino S, Daga RR

Citation

iScience 2024 Nov 15;27(11):111095

Publication year

2024

Abstract

In addition to the degradation of cell-cycle proteins, short-lived, damaged, or unfolded proteins are constantly cleared from cells by the proteasome. During proliferation, the proteasome localizes to the nucleus and cytoplasm; however, the functional relevance of this compartmentalization remains unclear. Here, we show that folding stress increases 26S/30S proteasome activity, which correlates with the upregulation of Ump1, a chaperone involved in 20S assembly. Conversely, ump1 inactivation results in a drop of 20S and 26S/30S proteasomes. Limited 26S/30S proteasomes in ump1 -deficient cells accumulate in the nucleus where they degrade mitotic substrates, allowing cells to proceed through mitosis; however, these cells present cytoplasmic aggregates and constitutive activation of the heat shock response. Thus, our data suggest that an increase in proteasome assembly induced by folding stress functions as an additional layer to proteasome regulation and highlight the importance of balanced proteasome compartmentalization to sustain cell proliferation while maintaining proper cytoplasmic proteostasis.

Annotation