title: Selective recapture of secretory granule components after full collapse exocytosis in neuroendocrine chromaffin cells.
abstract: In secretory cells, calcium-regulated exocytosis is rapidly followed by compensatory endocytosis. Neuroendocrine cells secrete hormones and neuropeptides through various modes of exo-endocytosis, including kiss-and-run, cavicapture and full-collapse fusion. During kiss-and-run and cavicapture modes, the granule membrane is maintained in an omega shape, whereas it completely merges with the plasma membrane during full-collapse mode. As the composition of the granule membrane is very different from that of the plasma membrane, a precise sorting process of granular proteins must occur. However, the fate of secretory granule membrane after full fusion exocytosis remains uncertain. Here, we investigated the mechanisms governing endocytosis of collapsed granule membranes by following internalization of antibodies labeling the granule membrane protein, dopamine-β-hydroxylase (DBH) in cultured chromaffin cells. Using immunofluorescence and electron microscopy, we observed that after full collapse, DBH remains clustered on the plasma membrane with other specific granule markers and is subsequently internalized through vesicular structures composed mainly of granule components. Moreover, the incorporation of this recaptured granule membrane into an early endosomal compartment is dependent on clathrin and actin. Altogether, these results suggest that after full collapse exocytosis, a selective sorting of granule membrane components is facilitated by the physical preservation of the granule membrane entity on the plasma membrane.
authors.affiliation: Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), Centre National de la Recherche Scientifique & Université de Strasbourg, 5 rue Blaise Pascal, F-67084 Strasbourg, France.
authors.forename: Mara
authors.initials: M
authors.lastname: Ceridono
authors.forename: Stéphane
authors.initials: S
authors.lastname: Ory
authors.forename: Fanny
authors.initials: F
authors.lastname: Momboisse
authors.forename: Sylvette
authors.initials: S
authors.lastname: Chasserot-Golaz
authors.forename: Sébastien
authors.initials: S
authors.lastname: Houy
authors.forename: Valérie
authors.initials: V
authors.lastname: Calco
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Haeberlé
authors.forename: Valérie
authors.initials: V
authors.lastname: Demais
authors.forename: Yannick
authors.initials: Y
authors.lastname: Bailly
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Bader
authors.forename: Stéphane
authors.initials: S
authors.lastname: Gasman
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism*; D019439:Chromaffin Cells / Q000502:physiology*; D002966:Clathrin / Q000378:metabolism; D005089:Exocytosis; D006801:Humans; D055099:Neuroendocrine Cells / Q000378:metabolism*; D022142:Secretory Vesicles / Q000502:physiology
chemical_list: D000199:Actins; D002966:Clathrin