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A stochastic model of calcium puffs based on single-channel data
Pengxing Cao1, Graham Donovan, Martin Falcke
1Department of Mathematics, The University of Auckland, Auckland, New Zealand.
Biophysical Journal
|September 10, 2013
Summary
Calcium puffs, local Ca2+ releases, are modeled using a new inositol 1,4,5-trisphosphate receptor (IP3R) model. Slow IP3R recovery is crucial for accurate puff modeling and understanding cluster size.
Area of Science:
- Cellular Biology
- Biophysics
- Calcium Signaling
Background:
- Calcium puffs are localized Ca2+ releases from internal stores like the ER/SR.
- These releases involve clusters of inositol 1,4,5-trisphosphate receptors (IP3Rs).
- Existing IP3R models often lack dynamic aspects of receptor behavior.
Purpose of the Study:
- To develop a novel IP3R model incorporating time-dependent mode switches.
- To construct a point-source model of calcium puffs based on the new IP3R model.
- To investigate the impact of IP3R recovery dynamics on calcium puff characteristics.
Main Methods:
- Developed a new IP3R model using stationary and nonstationary single-channel data.
- Incorporated time-dependent rates for IP3R mode switches.
- Utilized a hybrid Gillespie method with adaptive timing to solve the calcium puff model.
Main Results:
- A slow recovery rate of IP3Rs from Ca2+ inhibition is essential for reproducing experimental calcium puff data.
- Underestimating IP3R cluster size can occur with sufficiently slow recovery.
- Puff duration saturates with increasing IP3R numbers, while decay time increases linearly, causing puff asymmetry.
Conclusions:
- The developed IP3R model accurately simulates calcium puff dynamics.
- IP3R recovery kinetics significantly influence puff characteristics and cluster size estimation.
- The model explains the observed asymmetric shape of calcium puffs.
