Nucleolar dynamics and interactions with nucleoplasm in living cells

Area of Science:

• Cell Biology
• Biophysics

Background:

• Liquid-liquid phase separation (LLPS) is a key mechanism for forming membrane-less organelles, including nucleoli.
• While nucleoli exhibit liquid-like properties, their dynamics and interactions with the surrounding environment require further investigation.

Purpose of the Study:

• To investigate the in vivo dynamics and interface behavior of human nucleoli.
• To understand the factors influencing nucleolar motion and shape.

Main Methods:

• Live-cell imaging of human nucleoli.
• Monitoring of the nucleolus-nucleoplasm interface.
• Analysis of nucleolar pair dynamics and volume distribution.

Main Results:

• Identified two distinct nucleolar pair dynamics: correlated motion before coalescence and independent motion.
• Observed a nucleolar volume distribution not explained by current theories.
• Demonstrated that the nucleolus-nucleoplasm interface is ATP-dependent and sensitive to chromatin transcription and packing.

Conclusions:

• Nucleolar dynamics are more complex than previously thought, involving correlated motion and unique volume distributions.
• The nucleolus-nucleoplasm interface is actively regulated and influenced by cellular processes.
• Findings enrich the LLPS framework by highlighting the impact of the nucleoplasm on nucleoli in living cells.