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Regulation of activity dependent transmitter release from chromaffin cells by F‐actin and non‐muscle myosin II
Author(s) -
Doreian Bryan William,
Fulop Tiberiu,
Smith Corey
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1195.2
Subject(s) - exocytosis , microbiology and biotechnology , actin , chromaffin cell , myosin , chemistry , biology , granule (geology) , secretion , biophysics , adrenal medulla , endocrinology , catecholamine , paleontology
Adrenal chromaffin cells release catecholamines and neuropeptides upon stimulation. Both transmitter classes are packaged in the same secretory organelle. At basal firing rates, highly soluble catecholamines are released from chromaffin cells by ‘kiss and run’ fusion events. Under acute stress, elevated firing leads to full granule collapse releasing both catecholamine as well as a neuropeptide‐containing proteinacious granule core. Thus, activity dependent transmitter release is regulated by a transition in secretion mode. Here we employ electrochemical, electrophysiological and fluorescence based approaches to investigate the role of actin and myosin in regulating this transition. We show that under basal firing rates, F‐actin networks are maintained stabilizing ‘kiss and run’ fusion events. Under the same stimulation conditions, disruption of F‐actin resulted in conversion to full‐collapse exocytosis. Also, under increased cell stimulation, activation of myosin II and disruption of F‐actin is necessary to drive the full collapse of the granule. Under the same conditions stabilization of F‐actin and inhibition of myosin II resulted in a conversion to ‘kiss and run’ exocytosis. Our results demonstrate that the transition from ‘kiss and run’ to ‘full collapse’ exocytosis depends upon both F‐actin and myosin II, helping to provide essential regulation of the fusion mode and a proper stress response. This work was supported by a grant from the National Institutes of Health (NIH) 5/T/32/HL07887