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 1 microM [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.
Chowdhury
H H
HH
Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Medical School, Ljubljana, Slovenia.
Popoff
M R
MR
Zorec
R
R
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology*; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
D000199:Actins; D001427:Bacterial Toxins; D009074:Melanocyte-Stimulating Hormones; D002118:Calcium