rRNA 5'ETS processing contributes to nucleolar organization and nuclear architecture.

Disruption of 5'ETS cleavage in pre-rRNA processing causes significant changes in nucleolar structure and organization in eukaryotic cells.

• Why it matters: Understanding how nucleolar organization is maintained is crucial because it underpins ribosome biogenesis and nuclear architecture, yet the role of downstream processing steps remains unclear.
• What they did: Researchers disrupted the endonucleolytic cleavage of the 5'ETS mediated by the SSU processome and observed effects on nucleolar dynamics, NPM1 interactome, and heterochromatin markers.
• The result: Defects in 5'ETS maturation are linked to altered nucleolar material properties and broader nuclear organization, supporting a model that rRNA processing progression maintains nucleolar compartmentalization.