Cell size homeostasis is tightly controlled throughout the cell cycle

Area of Science:

• Cell Biology
• Quantitative Biology

Background:

• Proliferating cells need stable size distributions despite biological noise.
• The G1/S checkpoint model alone cannot fully explain cell size stability.
• Stochastic variations in cell cycle phases and division plane placement pose challenges.

Purpose of the Study:

• To investigate the mechanisms maintaining cell mass homeostasis throughout the cell cycle.
• To evaluate factors contributing to cell mass stability beyond the G1/S transition.
• To understand how cells counteract noise in growth rate and cell cycle progression.

Main Methods:

• Application of computationally enhanced quantitative phase microscopy (ceQPM).
• Accurate measurement of individual cell dry mass throughout the cell cycle.
• Analysis of cell populations in cultured human cell lines.

Main Results:

• Cell mass homeostasis is maintained even with G1/S disruptions or growth rate perturbations.
• Mass homeostasis is regulated throughout the cell cycle, not solely at G1/S.
• The coefficient of variation in cell dry mass decreases during S and G2 phases.

Conclusions:

• Cell mass homeostasis emerges from the interplay of mass-dependent cell cycle regulation and growth rate modulation.
• These regulatory processes provide a general principle for cell size control in proliferating cells.
• Similar mechanisms may operate in terminally differentiated cells.