title: Calcium-regulated exocytosis of dense-core vesicles requires the activation of ADP-ribosylation factor (ARF)6 by ARF nucleotide binding site opener at the plasma membrane.
abstract: The ADP ribosylation factor (ARF) GTP binding proteins are believed to mediate cytoskeletal remodeling and vesicular trafficking along the secretory pathway. Here we show that ARF6 is specifically associated with dense-core secretory granules in neuroendocrine PC12 cells. Stimulation with a secretagogue triggers the recruitment of secretory granules to the cell periphery and the concomitant activation of ARF6 by the plasma membrane-associated guanine nucleotide exchange factor, ARF nucleotide binding site opener (ARNO). Expression of the constitutively inactive ARF6(T27N) mutant inhibits secretagogue-dependent exocytosis from PC12 cells. Using a mutant of ARF6 specifically impaired for PLD1 stimulation, we find that ARF6 is functionally linked to phospholipase D (PLD)1 in the exocytotic machinery. Finally, we show that ARNO, ARF6, and PLD1 colocalize at sites of exocytosis, and we demonstrate direct interaction between ARF6 and PLD1 in stimulated cells. Together, these results provide the first direct evidence that ARF6 plays a role in calcium-regulated exocytosis in neuroendocrine cells, and suggest that ARF6-stimulated PLD1 activation at the plasma membrane and consequent changes in membrane phospholipid composition are critical for formation of the exocytotic fusion pore.
authors.affiliation: Unité Propre de Recherche 2356, Centre National de la Recherche Scientifique, 67084 Strasbourg Cedex, France. vitalen@neurochem.u-strabg.fr
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vitale
authors.forename: Sylvette
authors.initials: S
authors.lastname: Chasserot-Golaz
authors.forename: Yannick
authors.initials: Y
authors.lastname: Bailly
authors.forename: Naoko
authors.initials: N
authors.lastname: Morinaga
authors.forename: Michael A
authors.initials: MA
authors.lastname: Frohman
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Bader
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D016895:Culture Media, Serum-Free; D005089:Exocytosis / Q000502:physiology*; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D007150:Immunohistochemistry; D009711:Nucleotides / Q000378:metabolism; D016716:PC12 Cells; D010739:Phospholipase D / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D051381:Rats; D022142:Secretory Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D014162:Transfection
chemical_list: D000089982:ADP-Ribosylation Factor 6; D016895:Culture Media, Serum-Free; D020690:GTPase-Activating Proteins; D009711:Nucleotides; C102474:cytohesin-2; D006160:Guanosine Triphosphate; D010739:Phospholipase D; C106801:phospholipase D1; D020727:ADP-Ribosylation Factors; C000715349:Arf6 protein, rat; D011188:Potassium; D002118:Calcium