RRC ID 41441
Author Miyake K, McNeil PL, Suzuki K, Tsunoda R, Sugai N.
Title An actin barrier to resealing.
Journal J Cell Sci
Abstract Plasma membrane disruption is a common form of cell injury in many normal biological environments, including many mammalian tissues. Survival depends on the initiation of a rapid resealing response that is mounted only in the presence of physiological levels of extracellular Ca(2+). Vesicle-vesicle and vesicle-plasma membrane fusion events occurring in cortical cytoplasm surrounding the defect are thought to be a crucial element of the resealing mechanism. However, in mammalian cells, the vesicles used in this fusion reaction (endosomes/lysosomes) are not present in a 'pre-docked' configuration and so must be brought into physical contact with one another and with the plasma membrane. We propose that a requisite prelude to fusion is the disassembly in local cell cortex of the physical barrier constituted by filamentous actin. Consistent with this hypothesis, we found that rat gastric epithelial (RGM1) cell cortical staining with phalloidin was apparently reduced at presumptive disruption sites. Moreover, flow cytofluorometric analysis of wounded RGM1 populations revealed a small, but significant, Ca(2+)-dependent reduction in whole cell phalloidin staining. The functional significance of this disruption-induced depolymerization response was confirmed in several independent tests. Introduction into RGM1 cells of the filamentous actin-depolymerizing agent, DNase1, enhanced resealing, although cytochalasin treatment, by itself, had no effect. By contrast, when the filamentous actin cytoskeleton was stabilized experimentally, using phalloidin or jasplakinolide, resealing was strongly inhibited. Cells in wounded cultures displayed an enhanced cortical array of filamentous actin, and resealing by such cells was enhanced strongly by both cytochalasin and DNase 1, demonstrating the specific reversibility of a biologically mediated, polymerization-induced inhibition of resealing. We conclude that localized filamentous actin disassembly removes a cortical barrier standing in the way of membrane-membrane contacts leading to resealing-requisite homotypic and exocytotic fusion events.
Volume 114(Pt 19)
Pages 3487-94
Published 2001-10-1
PMID 11682608
MeSH Actins / metabolism* Animals Antineoplastic Agents / pharmacology Calcium / metabolism Cell Line Cell Membrane / metabolism* Cell Membrane / ultrastructure Cytochalasin B / pharmacology Cytoplasm / metabolism Cytoplasm / ultrastructure Cytoskeleton / drug effects Cytoskeleton / metabolism Deoxyribonuclease I / metabolism Depsipeptides* Epithelial Cells / cytology Epithelial Cells / metabolism* Exocytosis / physiology Gastric Mucosa / cytology Microscopy, Electron Peptides, Cyclic / pharmacology Phalloidine / pharmacology Polymers / metabolism Rats
IF 4.517
Times Cited 79
Human and Animal Cells RGM1(RCB0876)