Linked Life Data

1337454

Source:http://linkedlifedata.com/resource/pubmed/id/1337454

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1993-3-18
pubmed:abstractText
Earlier work by us as well as others has demonstrated that filamentous actin is mainly localized in the cortical surface of chromaffin cell. This F-actin network acts as a barrier to the chromaffin granules, impeding their contact with the plasma membrane. Chromaffin granules contain alpha-actinin, an anchorage protein that mediates F-actin association with these vesicles. Consequently, chromaffin granules crosslink and stabilize F-actin networks. Stimulation of chromaffin cell produces disassembly of F-actin and removal of the barrier. This interpretation is based on: (1) Cytochemical experiments with rhodamine-labeled phalloidin indicated that in resting chromaffin cells, the F-actin network is visualized as a strong cortical fluorescent ring; (2) Nicotinic receptor stimulation produced fragmentation of this fluorescent ring, leaving chromaffin cell cortical areas devoid of fluorescence; and (3) These changes are accompanied by a decrease in F-actin, a concomitant increase in G-actin, and a decrease in the F-actin associated with the chromaffin cell cytoskeleton (DNAse I assay). We also have demonstrated the presence in chromaffin cells of gelsolin and scinderin, two Ca(2+)-dependent actin filament-severing proteins, and suggested that chromaffin cell stimulation activates scinderin with the consequent disruption of F-actin networks. Scinderin, a protein recently isolated in our laboratory, is restricted to secretory cells and is present mainly in the cortical chromaffin cell cytoplasm. Scinderin, which is structurally different from gelsolin (different pIs, amino acid composition, peptide maps, and so on), decreases the viscosity of actin gels as a result of its F-actin-severing properties, as demonstrated by electron microscopy. Stimulation of chromaffin cells either by nicotine (10 microM) or high K+ (56 mM) produces a redistribution of subplasmalemmal scinderin and actin disassembly, which preceded exocytosis. The redistribution of scinderin and exocytosis is Ca(2+)-dependent and is not mediated by muscarinic receptors. Furthermore, our cytochemical experiments demonstrate that chromaffin cell stimulation produces a concomitant and similar redistribution of scinderin (fluorescein-labeled antibody) and F-actin (rhodamine phalloidin fluorescence), suggesting a functional interaction between these two proteins. Stimulation-induced redistribution of scinderin and F-actin disassembly would produce subplasmalemmal areas of decreased cytoplasmic viscosity and increased mobility for chromaffin granules. Exocytosis sites, evaluated by antidopamine-beta-hydroxylase (anti-D beta H) surface staining, are preferentially localized in plasma membrane areas devoid of F-actin.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0893-7648
pubmed:author
pubmed:issnType
Print
pubmed:volume
6
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
339-58
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Dynamic changes in chromaffin cell cytoskeleton as prelude to exocytosis.
pubmed:affiliation
Department of Pharmacology, Faculty of Medicine, University of Ottawa, Canada.
pubmed:publicationType
Journal Article, Review, Research Support, Non-U.S. Gov't