Dynamic modeling of yeast meiotic initiation

Area of Science:

• * Molecular and Systems Biology
• * Eukaryotic Cell Cycle Regulation
• * Mathematical Modeling in Biology

Background:

• * Meiosis, essential for sexual reproduction in eukaryotes, involves intricate feedback networks controlling gene expression.
• * The yeast Saccharomyces cerevisiae initiates meiosis via a tightly regulated process with transient expression of early meiotic proteins.
• * Sporulation efficiency varies significantly across different yeast genetic backgrounds, highlighting the complexity of regulatory pathways.

Purpose of the Study:

• * To develop a mathematical model simulating early meiotic events in yeast.
• * To investigate the role of signal transduction pathways, feedback mechanisms, and protein phosphorylation in regulating meiotic protein dynamics and sporulation efficiency.
• * To understand how system-level feedback controls transient protein expression and influences sporulation outcomes.

Main Methods:

• * Development of a mathematical model using ordinary differential equations to describe early meiotic events in Saccharomyces cerevisiae.
• * Simulation of the dynamics of key meiotic proteins, including the master regulator Ime1 and the kinase Ime2.
• * Validation of the model using quantitative sporulation phenotypes from single-gene knockout yeast strains.

Main Results:

• * The model accurately simulates the transient dynamics of meiotic proteins like Ime1 and Ime2.
• * Both positive and negative feedback loops are essential for terminating early meiotic protein expression.
• * Coordinated feedback loops modulate sporulation efficiency, with Ime2 auto-regulation creating a bistable system for enhanced meiotic states.

Conclusions:

• * Feedback signals to Ime1 and Ime2 are critical for terminating protein expression and determining yeast sporulation efficiency.
• * The meiotic initiation pathway's architecture ensures a robust, rapid, and complete transition into meiosis.
• * The mathematical model identifies regulatory targets for enhancing sporulation efficiency, potentially improving gamete production strategies.