Multiple inputs ensure yeast cell size homeostasis during cell cycle progression

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Cell growth coordination with division is crucial for cell function.
• While G1 phase cell size control mechanisms are known in budding yeast, the overall cell size homeostasis mechanism remains unclear.

Purpose of the Study:

• To investigate the mechanisms underlying cell size homeostasis in budding yeast.
• To identify the cell cycle phase(s) and molecular players involved in maintaining cell size stability.

Main Methods:

• Development of a novel technique for accurate cell cycle monitoring via histone level quantification in individual cells.
• Analysis of cell cycle progression and size control in wild-type and mutant budding yeast strains.

Main Results:

• A mechanism controlling bud size in the G2/M phase was identified, preventing premature anaphase onset and regulating size variability.
• Mutants with altered cyclin B-Cdk regulation exhibited significant cell size variability.
• Cell size homeostasis was not impaired in most G1 mutants, suggesting a broader regulatory network.

Conclusions:

• Cell size homeostasis is not solely regulated by G1-specific mechanisms.
• A G2/M phase mechanism plays a role in controlling bud size and overall cell size variability.
• Size homeostasis likely emerges from the integration of multiple mechanisms coordinating cell growth and division.