Cell-cycle calcium transients driven by cyclic changes in inositol trisphosphate levels

Area of Science:

• Developmental Biology
• Cell Biology
• Biochemistry

Background:

• Transient changes in intracellular calcium ([Ca2+]i) are observed during the cell cycle in various cell types and early embryos.
• These calcium transients correlate with key cell-cycle events like nuclear envelope breakdown and mitosis.
• The trigger for endogenous cell-cycle calcium transients, distinct from signal transduction pathways, remains unknown.

Purpose of the Study:

• To investigate the underlying mechanism of endogenous cell-cycle calcium transients in sea urchin embryos.
• To identify the trigger for intracellular calcium ([Ca2+]i) oscillations during early embryonic cell cycles.
• To elucidate the role of the phosphoinositide messenger system in regulating cell-cycle calcium dynamics and mitosis.

Main Methods:

• Monitoring of the phosphoinositide messenger system during the early embryonic cell cycle.
• Measurement of cyclic increases in inositol trisphosphate.
• Observation of calcium release from intracellular stores.

Main Results:

• The phosphoinositide messenger system oscillates during the early embryonic cell cycle in sea urchin embryos.
• These oscillations lead to cyclic increases in inositol trisphosphate.
• Cyclic inositol trisphosphate increases trigger cell-cycle calcium ([Ca2+]i) transients and subsequent mitosis.

Conclusions:

• The phosphoinositide system acts as an endogenous oscillator regulating cell-cycle calcium transients.
• Cyclic increases in inositol trisphosphate are the trigger for cell-cycle calcium ([Ca2+]i) transients.
• This mechanism drives mitosis through calcium release from intracellular stores in sea urchin embryos.