The use of dynamics to enhance the signaling capabilities of cells

SILVINA PONCE DAWSON

Simposio; 12th Anniversary Symposium ICTP-SAIFR; 2024

Cells continuously sense their surroundings to detect modifications and generate responses. Very often concentrations in the extracellular medium change, turning on signaling cascades that eventually result in changes in gene expression. Quite often intermediaries of the signaling pathway display dynamic behaviors that do not mimic that of the environmental changes. Cells do this at an energy cost. What is the advantage of using these mechanisms? In this talk I will present two examples observed in yeast. In the first example, dynamics serves the purpose of using the same signaling agent to respond to different stimuli and, therefore, to generate different responses accordingly, i.e., to multiplex the “signaling channel”. In this case we analyze the extent of the multiplexing capacity when the intermediary is the nuclear fraction of one transcription factor (TF) that can activate two promoters. In particular we show that while it is possible to find promoters that respond in a graded manner to prolonged elevations of nuclear TF and be blind to pulses of nuclear TF localization at the same time, the opposite combination does not seem to be possible. In the second example the same stimulus elicits different dynamic behaviors in different intermediaries of the pathway. In this case we find that the different way in which the codification in the frequency or the amplitude of the intermediary maps the environment, equip cells with qualitatively different information transmission capabilities. While amplitude encoding is optimal for a limited range of stimuli strengths around a finite value, frequency encoding allows a reliable information transmission for a much wider range of intensities, thus, expanding the dynamic range of the detection.