Cells and cytoplasmic fragments utilize electrophoresis and competing pathways to move oppositely in electric field

Orateur : Prof Alex Mogilner (Department of Neurobiology, Physiology and Behavior and Department of Mathematics - University of California, Davis - USA)

Both direction-sensing and motility are required for cell migration, but their integration is elusive. Cytoplasmic fragments are the simplest motile units, but are they directional ? We found that cytoplasmic fragments of fish keratocytes move to anode in electric field, while whole cells migrate to cathode. Myosin is essential for galvanotaxis of fragments but not for cells, while PI3K is essential for cells but not fragments. Direction sensing is independent of the cell/fragment sizes and ion fluxes. Mechanical force and electro-osmotic flows do not direct the cells. Galvanotactic response is sensitive to pH and viscosity. We conclude that two signal transduction pathways compete to orient motile cells in the electric field. Our data argues against hypotheses that primary sensor for the electric field in keratocytes is either a sensor of electric force, or electro-osmosis, or gradient of membrane potential, but is consistent with electrophoresis of charged proteins in the cell membrane.

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