Actin cytoskeleton and exocytosis in rat melanotrophs.
We monitored secretory activity of single rat melanotrophs by the patch-clamp membrane capacitance measurements (Cm). Secretory activity was stimulated by cytosol dialysis with a patch-pipette solution containing 1μM [Ca2+]i. Actin cytoskeleton was disaggregated by pretreating cells with Clostridium spiroforme toxin, which specifically ADP-ribosylates cellular actin. The extent of cytoskeleton disaggregation was monitored by phalloidin immunostaining. The maximal rate of secretion increases two folds in toxin-treated cells in comparison to controls, whereas the extent of calcium-induced secretory response was similar to that obtained in the non-treated cells. The results show that the subcortical actin network attenuates the rate of secretory activity, which we interpret to reflect a barrier function of cytoskeleton for exocytosis.
Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Medical School, pp2211, 1001 Ljubljana, Slovenia, , , , , , SI.
Helana H
HH
Chowdhury
Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris, Cedex 15, France, , , , , , FR.
Michel R
MR
Popoff
Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Medical School, pp2211, 1001 Ljubljana, Slovenia, , , , , , SI.
Robert
R
Zorec
Key words actin cytoskeleton; endocytosis; exocytosis; melanotrophs; patch-clamp