Evaluating phase separation in live cells: diagnosis, caveats, and functional consequences.

Area of Science:

• Cell Biology
• Biochemistry
• Molecular Biology

Background:

• Liquid-liquid phase separation (LLPS) is proposed as a key mechanism for cellular self-organization.
• LLPS research has surged, investigating its role in gene expression, cell division, and stress responses.
• In vitro studies have elucidated principles of biomolecular phase separation.

Purpose of the Study:

• To critically analyze the evidence for in vivo LLPS across various cellular processes.
• To evaluate the adequacy of current data in supporting LLPS as a physiological mechanism.
• To identify limitations in understanding the causal relationships and functional impacts of in vivo LLPS.

Main Methods:

• Review and analysis of existing scientific literature on in vivo LLPS.
• Assessment of experimental evidence supporting phase separation in living cells.
• Identification of gaps in current research and methodological shortcomings.

Main Results:

• Evidence for in vivo LLPS is frequently phenomenological and insufficient to rule out alternative mechanisms.
• The causal link and functional consequences of LLPS within living cells remain largely undetermined.
• Current data often fails to distinguish LLPS from other cellular self-assembly processes.

Conclusions:

• More rigorous, quantitative evidence is needed to confirm LLPS in vivo.
• Future research should focus on endogenous protein levels and physiological conditions.
• Recommendations are provided for experiments to yield more conclusive results on LLPS function.