Modeling mutant phenotypes and oscillatory dynamics in the Saccharomyces cerevisiae cAMP-PKA pathway

Area of Science:

• Cellular Biology
• Systems Biology
• Biophysics

Background:

• The cyclic AMP-Protein Kinase A (cAMP-PKA) pathway is a crucial, evolutionarily conserved signaling mechanism regulating cellular growth and differentiation.
• This pathway is vital in organisms like animals and fungi, including the budding yeast Saccharomyces cerevisiae.

Purpose of the Study:

• To develop a mathematical model of the cAMP-PKA pathway dynamics in Saccharomyces cerevisiae.
• To recapitulate signaling dynamics in wild-type yeast and phosphodiesterase mutants (pde1Δ, pde2Δ, pde1Δpde2Δ).

Main Methods:

• Mathematical modeling of the cAMP-PKA pathway, focusing on PKA-mediated negative feedback.
• Simulation of short-term and long-term pathway dynamics.
• Experimental validation of model predictions using cAMP level measurements in S. cerevisiae.

Main Results:

• The model requires PKA-mediated negative feedback on phosphodiesterases and the Ras branch to accurately simulate wild-type and mutant yeast responses.
• A key prediction is decaying oscillatory dynamics of intracellular cAMP concentrations during the approach to steady state after glucose stimulation.
• Experimental data confirmed the presence of these decaying cAMP oscillations in S. cerevisiae.

Conclusions:

• The developed model offers novel insights into yeast nutrient response mechanisms.
• The model's predictive and explanatory capabilities establish a foundation for future research in this signaling network.