Active RNA synthesis patterns nuclear condensates

Area of Science:

• Cellular biology
• Biochemistry
• Biophysics

Background:

• Biomolecular condensates are essential membraneless organelles organizing cellular processes.
• Mechanisms of condensate formation and dissolution are known, but patterning (size, number, spacing) is poorly understood.

Purpose of the Study:

• To investigate the role of RNA in regulating biomolecular condensate patterning.
• To elucidate the physical principles governing condensate patterning using nucleolar fibrillar centers (FCs) as a model.

Main Methods:

• Inhibition of ribosomal RNA synthesis in cells.
• Experimental observation and physical theory modeling of FC patterning.
• Altering FC component TCOF1 expression and assessing its impact on RNA processing.

Main Results:

• Inhibiting ribosomal RNA synthesis significantly altered FC patterning.
• A model was supported where active RNA synthesis creates a non-equilibrium state that arrests condensate coarsening.
• Altered FC patterning via TCOF1 expression impaired ribosomal RNA processing.

Conclusions:

• Active RNA synthesis is crucial for regulating biomolecular condensate patterning.
• Non-equilibrium states driven by active chemical processes dictate condensate organization.
• Condensate patterning is linked to essential cellular functions like ribosome biogenesis.