Intracellular Ca2+ distribution in migrating transformed epithelial cells

Area of Science:

• Cell Biology
• Biophysics
• Physiology

Background:

• Cell migration is essential for various biological processes.
• Polarized ion channel activity is critical for directed cell movement.
• Calcium signaling plays a key role in regulating cell functions, including migration.

Purpose of the Study:

• To investigate the role of intracellular calcium concentration ([Ca2+]i) gradients in the polarized activity of Ca2+-sensitive K+ channels during MDCK-F cell migration.
• To determine the mechanisms underlying the spatial distribution of [Ca2+]i in migrating cells.

Main Methods:

• Measurement of intracellular calcium ([Ca2+]i) using the fluorescent dye fura-2/AM.
• Spatial analysis of [Ca2+]i distribution within migrating MDCK-F cells.
• Local superfusion techniques with ion channel blockers (La3+, charybdotoxin) and Ca2+ influx indicators (Mn2+) to assess Ca2+ dynamics and channel activity.

Main Results:

• A horizontal gradient of [Ca2+]i was observed, with higher concentrations in the cell body compared to the lamellipodium.
• Blocking Ca2+ influx into the cell body significantly reduced cell migration, indicating the importance of localized Ca2+ entry.
• While Ca2+ influx occurs across the entire cell surface, the observed gradient suggests that intracellular Ca2+ stores contribute significantly to the polarized [Ca2+]i distribution.

Conclusions:

• The study demonstrates a direct correlation between intracellular calcium gradients and polarized K+ channel activity in migrating MDCK-F cells.
• Localized Ca2+ influx and the polarized distribution of intracellular Ca2+ stores are key factors in establishing the [Ca2+]i gradient.
• These findings provide insights into the molecular mechanisms governing directed cell migration.