Cell growth and differentiation are highly regulated to allow organisms to develop properly. During differentiation, cells often switch entire gene transcription and translation programs in order to accommodate changing metabolic and functional needs. One way differentiation is regulated is through changes to the cell’s ribosome concentration. Decreases in ribosome concentration tend to move cells away from proliferation and towards differentiation. This regulation of cell physiology at the level of ribosome concentration has important implications for human diseases, including cancer and neurodegenerative disorders.

This work describes a mechanism influencing cell differentiation in the developing Drosophila nervous system. While it is generally common that progeny cells have lower concentrations of mature ribosomes than their progenitors, the mechanisms behind this change are poorly understood in the nervous system. I demonstrate that decreased ribosome concentration in neurons compared to neuroblasts is driven by a significant decrease in ribosomal RNA transcription in these post-mitotic cells. My data also show that high levels of translation in newborn neurons is supported exclusively by ribosomal RNA that is inherited from their progenitors.

This work adds to a growing body of evidence linking changes in ribosome concentration to changes in the cell cycle and to the proteome. Additionally, it lays the groundwork for future studies of this kind to proceed with confidence using the developing brain of Drosophila as a model.