Annexin 2 promotes the formation of lipid microdomains required for calcium-regulated exocytosis of dense-core vesicles.
Fiche publication
Date publication
mars 2005
Journal
Molecular biology of the cell
Auteurs
Membres identifiés du Cancéropôle Est :
Dr BADER Marie-France, Dr CHASSEROT-GOLAZ Sylvette, Dr VITALE Nicolas
Tous les auteurs :
Chasserot-Golaz S, Vitale N, Umbrecht-Jenck E, Knight D, Gerke V, Bader MF
Lien Pubmed
Résumé
Annexin 2 is a calcium-dependent phospholipid-binding protein that has been implicated in a number of membrane-related events, including regulated exocytosis. In chromaffin cells, we previously reported that catecholamine secretion requires the translocation and formation of the annexin 2 tetramer near the exocytotic sites. Here, to obtain direct evidence for a role of annexin 2 in exocytosis, we modified its expression level in chromaffin cells by using the Semliki Forest virus expression system. Using a real-time assay for individual cells, we found that the reduction of cytosolic annexin 2, and the consequent decrease of annexin 2 tetramer at the cell periphery, strongly inhibited exocytosis, most likely at an early stage before membrane fusion. Secretion also was severely impaired in cells expressing a chimera that sequestered annexin 2 into cytosolic aggregates. Moreover, we demonstrate that secretagogue-evoked stimulation triggers the formation of lipid rafts in the plasma membrane, essential for exocytosis, and which can be attributed to the annexin 2 tetramer. We propose that annexin 2 acts as a calcium-dependent promoter of lipid microdomains required for structural and spatial organization of the exocytotic machinery.
Mots clés
Actins, metabolism, Adrenal Glands, metabolism, Animals, Annexin A2, physiology, Calcium, metabolism, Catecholamines, metabolism, Cattle, Cell Line, Cell Membrane, metabolism, Cholesterol, metabolism, Chromaffin Cells, metabolism, Cricetinae, Dose-Response Relationship, Drug, Exocytosis, Filipin, pharmacology, Immunoblotting, Lipids, chemistry, Membrane Microdomains, metabolism, Microscopy, Confocal, Microscopy, Fluorescence, Norepinephrine, pharmacology, Secretory Vesicles, metabolism, Semliki forest virus, genetics, Subcellular Fractions, Time Factors
Référence
Mol. Biol. Cell. 2005 Mar;16(3):1108-19