Functional coupling of secretion and capacitative calcium entry in PC12 cells

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• PC12 cells are a widely used model for studying neuronal function and secretion.
• Intracellular calcium concentration ([Ca2+]i) plays a critical role in regulating cellular processes, including neurotransmitter release.

Purpose of the Study:

• To investigate the effects of caffeine on intracellular calcium levels and dopamine release in PC12 cells.
• To elucidate the mechanisms underlying caffeine-evoked calcium signaling and dopamine secretion.

Main Methods:

• PC12 cells were treated with caffeine, cyclopiazonic acid (CPA), or thapsigargin.
• Intracellular calcium concentration ([Ca2+]i) was measured using fluorescence imaging.
• Dopamine release was quantified using established biochemical assays.

Main Results:

• Caffeine induced a transient release of intracellular calcium followed by sustained calcium entry via a non-voltage-dependent pathway.
• Inhibitors of the endoplasmic reticulum Ca2+ ATPase pump (CPA and thapsigargin) caused a sustained rise in [Ca2+]i and abolished caffeine-evoked calcium responses.
• Caffeine-induced dopamine release required extracellular calcium and was mimicked by CPA treatment.

Conclusions:

• Store-dependent calcium entry is essential for caffeine-evoked dopamine secretion in PC12 cells.
• Caffeine's effects on calcium signaling and dopamine release are mediated through the depletion of intracellular calcium stores.
• These findings highlight the importance of calcium store refilling mechanisms in regulating secretory responses in excitable cells.