Nucleolar reorganization on stress depends on physicochemical changes due to reduced nascent rRNA synthesis.

Reduced nascent rRNA synthesis drives nucleolar reorganization under stress, altering sub-structures and biophysical properties in Homo sapiens cells.

• Why it matters: Understanding how cellular stress impacts nucleolar architecture is crucial because it affects ribosome production and cell function, yet the mechanisms linking rRNA synthesis to structural changes are unclear.
• What they did: Using expansion microscopy, the study visualized nucleolar substructures and tracked rRNA synthesis, revealing that stress-induced decreases in nascent rRNA levels cause structural reorganization and pH gradient disruption.
• The result: The findings demonstrate that nucleolar reorganization results from biophysical changes driven by reduced rRNA, providing insight into stress responses and potential targets for modulating nucleolar function.