ELECTROENDOCYTOSIS: EXPOSURE OF CELLS TO PULSED LOW ELECTRIC FIELDS ENHANCES ADSORPTION AND UPTAKE OF MACROMOLECULES
Yulia Antov 1, Alexander Barbul 1, Hila Mantsur 1 and Rafi Korenstein 1*
1 Tel-Aviv University
* To whom correspondence should be addressed. E-mail: korens{at}post.tau.ac.il.
Submitted on August 12, 2004
Revised on September 8, 2004
Accepted on 22 October 2004
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Abstract |
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The present study demonstrates alteration of cell surface, leading to enhanced adsorption of macromolecules (BSA, dextran and DNA), following the exposure of cells to unipolar pulsed low electric fields (LEF). Modification of the adsorptive properties of the cell membrane also stems from the observation of LEF-induced cell-cell aggregation. Analysis of the adsorption isotherms of BSA-FITC to the surface of COS 5-7 cells reveals that the stimulated adsorption can be attributed to LEF-induced increase in the capacity of both specific and non-specific binding. The enhanced adsorption was consequently followed by increased uptake. At 20V/cm the maximal binding and subsequent uptake of BSA-FITC attached to specific sites are 6.5 and 7.4 folds higher than in controls, respectively. The non-specific LEF-induced binding and uptake of BSA are 34 and 5.2 folds higher than controls. LEF-enhanced adsorption is a temperature independent process, while LEF-induced uptake is a temperature dependent one which is abolished at 4°C. The stimulation of adsorption and uptake is reversible, revealing similar decay kinetics at room temperature. It is suggested that electrophoretic segregation of charged components in the outer leaflet of the cell membrane is responsible for both enhanced adsorption and stimulated uptake via changes of the membrane elastic properties which enhance budding and fission processes.
Key Words:
adsorption and uptake kinetics, albumin binding, cell aggregation, clathrin dependent and independent pathways, endocytosis, temperature dependence
