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Modeling IP3-induced Ca2+ signaling based on its interspike interval statistics
Victor Nicolai Friedhoff1, Benjamin Lindner2, Martin Falcke1
1Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany; Department of Physics, Humboldt University, Berlin, Germany.
Biophysical Journal
|June 14, 2023
Summary
Calcium (Ca2+) signaling, crucial for eukaryotic cells, exhibits randomness. A new theory explains Ca2+ spiking based on random IP3 receptor channel cluster behavior, unifying cell-type properties and predicting signaling dynamics.
Area of Science:
- Cellular Biology
- Biophysics
- Signaling Pathways
Background:
- Inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ signaling is a fundamental second messenger system in eukaryotic cells.
- Recent studies highlight the inherent randomness of Ca2+ signaling across all biological structural levels.
- Understanding the general properties and underlying mechanisms of Ca2+ spiking is crucial for cell function.
Purpose of the Study:
- To compile and analyze common properties of Ca2+ spiking across various cell types.
- To propose a novel theory explaining Ca2+ spiking dynamics based on the stochastic behavior of IP3 receptor channel clusters.
- To elucidate the mechanisms driving Ca2+ spike generation, timing, and cell-to-cell variability.
Main Methods:
- Compilation of eight general properties of Ca2+ spiking observed in investigated cell types.
- Development of a theoretical model based on a first passage process of IP3 receptor channel cluster opening.
- Analysis of spike generation, interspike interval (T_av), and its dependence on diffusion and channel coupling.
Main Results:
- The proposed theory successfully reproduces key properties of Ca2+ spiking, including exponential stimulation response, random spike timing, and sensitivity to diffusion.
- Cellular variability in T_av is explained by differences in channel cluster coupling, cluster number, and IP3 pathway component expression.
- Predictions are made regarding the relationship between puff probability, agonist concentration, and intracellular IP3 levels.
Conclusions:
- The hierarchical and random nature of IP3 receptor channel cluster activity provides a unified explanation for observed Ca2+ spiking properties.
- The theory accounts for both general Ca2+ spiking characteristics and cell- or agonist-specific behaviors, often related to negative feedback mechanisms.
- This framework offers a robust understanding of Ca2+ signal generation and variability in eukaryotic cells.
