EFFECTS OF ACTIN CYTOSKELETON REARRANGEMENTS ON CALCIUM ENTRY CHANNEL ACTIVATION
IN A431 CELLS
V. A. Alexeenko, K. O. Gusev, E. V. Kaznacheyeva
Institute of Cytology RAS, St. Petersburg;
e-mail: vadim@va.usr.pu.ru
Using patch clamp and ion-selective fluorescence dye techniques, we investigated the influence of actin
cytoskeleton rearrangements on the activity of calcium entry channels in plasma membrane of human carcinoma A431
cells. It is shown that disruption of actin microfilaments by cytohalasin D has no significant effect on calcium
release from the stores and its entry from the extracellular space. It also does not interfere with the activition
of inositol 1,4,5-trisphosphate (IP3)-dependent high-selective low-conductance calcium channels
Imin. The treatment of
cells with calyculin A induces the formation of actin filament layer beneath plasma membrane and also inhibits
Imin activition and calcium entry through the plasma membrane, though calcium efflux from the stores was nearly
unchanged. Thus, it is concluded that calcium signalling in A431 cells can be modulated by actin cytoskeleton
rearrangements, and may be well described in terms of "conformational coupling" model.
Key words: calcium channels, cytoskeleton, calyculin A, cytohalasin D
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