A Two-Pulse Cellular Stimulation Test Elucidates Variability and Mechanisms in Signaling Pathways

Area of Science:

• Cellular biology
• Systems biology
• Biophysics

Background:

• Mammalian cells display variable responses to physiological ligand pulses.
• Understanding the basis of this variability (stochastic vs. deterministic) is crucial for cell fate determination.

Purpose of the Study:

• To investigate whether cellular responses to pulsed stimulation are stochastic or deterministic.
• To identify parameters governing response variability in signaling pathways.

Main Methods:

• Developed a "rest-period test" using two-pulse stimulation with varying intervals.
• Combined experimental data with mathematical modeling of signaling pathways.

Main Results:

• Cells predictably skip responses when rest periods between pulses are shortened.
• Response variability is explained by extrinsic noise, short-term stimulation memory, and high Hill coefficient processes.
• Analysis of intracellular calcium and NFκB signaling pathways supports deterministic signaling models.

Conclusions:

• Cellular responses to pulsed stimulation are largely deterministic, not purely stochastic.
• Short-term cellular memory and specific pathway parameters dictate response patterns.
• This deterministic nature suggests signaling pathways guide cells to specific fates, even with weak stimuli.