Exocytosis in neuroendocrine cells: new tasks for actin.
Most secretory cells undergoing calcium-regulated exocytosis in response to cell surface receptor stimulation display a dense subplasmalemmal actin network, which is remodeled during the exocytotic process. This review summarizes new insights into the role of the cortical actin cytoskeleton in exocytosis. Many earlier findings support the actin-physical-barrier model whereby transient depolymerization of cortical actin filaments permits vesicles to gain access to their appropriate docking and fusion sites at the plasma membrane. On the other hand, data from our laboratory and others now indicate that actin polymerization also plays a positive role in the exocytotic process. Here, we discuss the potential functions attributed to the actin cytoskeleton at each major step of the exocytotic process, including recruitment, docking and fusion of secretory granules with the plasma membrane. Moreover, we present actin-binding proteins, which are likely to link actin organization to calcium signals along the exocytotic pathway. The results cited in this review are derived primarily from investigations of the adrenal medullary chromaffin cell, a cell model that is since many years a source of information concerning the molecular machinery underlying exocytosis.
Malacombe
Magali
M
Département Neurotransmission et Sécrétion Neuroendocrine, Institut des Neurosciences Cellulaires et Intégratives (UMR 7168/LC2), Centre National de la Recherche Scientifique et Université Louis Pasteur, 5 rue Blaise Pascal, 67084 Strasbourg, France.
Bader
Marie-France
MF
Gasman
Stéphane
S
D000199:Actins / Q000378:metabolism / Q000502:physiology*; D000313:Adrenal Medulla / Q000166:cytology / Q000502:physiology*; D000818:Animals; D020013:Calcium Signaling; D019439:Chromaffin Cells / Q000502:physiology*; D005089:Exocytosis; D006801:Humans; D009490:Neurosecretory Systems / Q000166:cytology / Q000502:physiology*; D022142:Secretory Vesicles / Q000502:physiology; D020741:rho GTP-Binding Proteins / Q000378:metabolism
D000199:Actins; D020741:rho GTP-Binding Proteins