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Spatial and temporal aspects of cellular calcium signaling
A P Thomas1, G S Bird, G Hajnóczky
1Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Summary
Cytosolic calcium (Ca2+) signals exhibit complex temporal and spatial patterns in nonexcitable cells, driven by inositol trisphosphate (IP3) signaling. These patterns, including oscillations and waves, are crucial for cellular functions and communication.
Area of Science:
- Cellular Biology
- Biochemistry
- Physiology
Background:
- Cytosolic Ca2+ signals display intricate temporal and spatial organization, even with sustained stimulation.
- In nonexcitable cells, Ca2+ is primarily mobilized via inositol trisphosphate ((1,4,5)IP3)-dependent release from intracellular stores.
- Ca2+ signaling patterns arise from limited cytoplasmic diffusion and feedback regulation of Ca2+ mobilization pathways.
Purpose of the Study:
- To review the mechanisms underlying complex cytosolic Ca2+ signaling patterns in nonexcitable cells.
- To discuss the physiological significance of these Ca2+ oscillations and waves.
- To explore the roles of (1,4,5)IP3 and Ca2+ feedback in shaping signaling dynamics.
Main Methods:
- Review of existing literature on Ca2+ signaling mechanisms.
- Analysis of models explaining Ca2+ oscillations and waves.
- Discussion of experimental evidence for Ca2+ signaling in intact tissues.
Main Results:
- Two main types of Ca2+ oscillations identified: baseline spiking (frequency-dependent on agonist dose) and sinusoidal oscillations (amplitude-dependent on agonist dose).
- Baseline spiking involves interplay between Ca2+ and (1,4,5)IP3 regulating Ca2+ channels.
- Sinusoidal oscillations are explained by protein kinase C feedback on (1,4,5)IP3 generation.
Conclusions:
- Ca2+ oscillations and waves are physiologically significant, coordinating cellular and multicellular functions.
- Frequency-modulated Ca2+ signals are recognized as important regulators of cellular processes.
- Spatial organization of Ca2+ stores and signaling pathways is critical for pattern formation.