Scinderin and chromaffin cell actin network dynamics during neurotransmitter release.
It has been demonstrated that filamentous actin (F-A) is mainly localized in the cortical surface of the chromaffin cell. This F-A network acts as a barrier to the chromaffin granules impeding their contact with the plasma membrane. Stimulation of chromaffin cells with either nicotine or a depolarizing concentration of K+ induces the disassembly of cortical F-A in focal areas underneath the plasma membrane. Sites of exocytosis are localised to these areas with low concentration of F-A. The cortical surface of the chromaffin cell also contains scinderin, a Ca(2+)-dependent actin filament-severing protein recently isolated in our laboratory. Nicotine and high K+ stimulation also induce redistribution of cortical scinderin. Both nicotine and high K(+)-induced scinderin redistribution and F-A disassembly are Ca(2+)-dependent events which seem to precede neurotransmitter secretion. A possible target for protein kinase C in the modulation of secretion is the cortical F-A network. Treatment of chromaffin cells with phorbol esters prior to secretion induced scinderin redistribution, F-A disassembly and enhanced the initial rate of subsequent nicotine-evoked catecholamine release. The present results strongly indicate the involvement of the cortical cytoskeleton in the regulation of neurotransmitter release.
Trifaró
J M
JM
Department of Pharmacology, University of Ottawa, Ontario, Canada.
Vitale
M L
ML
Rodríguez Del Castillo
A
A
D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002838:Chromaffin System / Q000166:cytology / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology; D018260:Gelsolin; D006801:Humans; D008840:Microfilament Proteins / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D015290:Second Messenger Systems
D000199:Actins; D018260:Gelsolin; D008840:Microfilament Proteins; D018377:Neurotransmitter Agents; C065395:scinderin