Limitations to Chemotactic Concentration Sensing during $Ca^{2+}$ Signaling

TL;DR

This paper investigates how eukaryotic cells sense chemotactic signals through Ca2+ signaling, revealing robustness in concentration sensing despite intracellular variability and demonstrating the ability of Dictyostelium to detect low cAMP levels.

Contribution

It provides a theoretical and simulation-based analysis of concentration sensing robustness in Ca2+ signaling, highlighting evolutionary advantages and low-concentration sensing capabilities.

Findings

Concentration sensing remains robust above certain reaction rate thresholds.

Cells can sense very low cAMP concentrations, consistent with experimental data.

Robustness allows cells to optimize other signaling functions without losing sensing accuracy.

Abstract

Living cells sense noisy biochemical signals crucial for survival, yet models incorporating intracellular signaling are limited. This study examines how cells sense chemotactic concentrations through phosphorylation readouts in Ca2+ signaling, which is ubiquitous in most eukaryotic cells. Using stochastic simulations and analytical calculations we find that concentration sensing remains robust to variations in cytoplasmic reaction rates once they exceed a certain value, suggesting a potential evolutionary advantage that allows cells to optimize other signaling tasks without compromising concentration sensing accuracy. Our analysis demonstrates theoretically that Dictyostelium is capable of sensing very low concentrations of cyclic adenosine monophosphate (cAMP) as is experimentally seen.