Study identifies nucleolus subcompartments involved in ribosome assembly

Researchers at St. Jude Children's Research Hospital have identified small structures inside the nucleolus that help complete ribosome assembly, according to a study published in Molecular Cell. The finding matters because ribosomes are the cell’s protein-making machinery, and the study links their production to a more organized process than researchers had established before.

The nucleolus is a fluid-like structure inside cells where ribosomes are put together, St. Jude said. Scientists already knew the nucleolus contains three distinct compartments, but the role of those compartments in ribosome assembly had remained unclear, according to the researchers.

The St. Jude study reports that smaller subcompartments form spontaneously within the nucleolus. Those subcompartments contain ribosome building blocks and proteins involved in assembly, according to the study.

St. Jude said the small structures help carry out the final stages of ribosome assembly. That finding adds another layer to scientists’ understanding of how the nucleolus is organized during production of the cell’s protein-making machinery.

The researchers described the work as revealing previously unseen levels of organization in the assembly process. Their finding suggests that the nucleolus is not only divided into three known regions, but also contains smaller, self-forming areas that concentrate the materials needed to finish ribosomes.

The study may also help researchers examine diseases tied to higher ribosome output, St. Jude said. Cancer is one example of a disease associated with increased ribosome production, according to the researchers.

The work does not establish a treatment or diagnostic approach. St. Jude said it offers insight into the basic cellular process that supports ribosome production, which could help clarify how that process is altered in disease.

This story draws on original reporting from Phys.org.