title: Directing exocrine secretory vesicles to the apical membrane by actin cables generated by the formin mDia1.
abstract: The final stage in exocrine secretion involves translocation of vesicles from their storage areas to the apical membrane. We show that actin-coated secretory vesicles of the exocrine pancreas travel this distance over bundles of specialized actin cables emanating from the apical plasma membrane. These bundles are stable structures that require constant G-actin incorporation and are distinct from the actin web that surrounds the exocrine lumen. The murine mammalian Diaphanous-related formin 1 (mDia1) was identified as a generator of these cables. The active form of mDia1 localized to the apical membrane, and introduction of an active form of mDia1 led to a marked increase in bundle density along the lumen perimeter. Compromising formation of the cables does not prevent secretion, but results in disorganized trafficking and fusion between secretory vesicles. Similar apical secretory tracks were also found in the submandibular salivary glands. Together with previous results that identified a role for Diaphanous in apical secretion in tubular organs of Drosophila, the role of Diaphanous formins at the final stages of secretion appears to be highly conserved.
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Erez
authors.initials: E
authors.lastname: Geron
authors.forename: Eyal D
authors.initials: ED
authors.lastname: Schejter
authors.forename: Ben-Zion
authors.initials: BZ
authors.lastname: Shilo
mesh_terms: D061354:Acinar Cells / Q000502:physiology; D008841:Actin Cytoskeleton / Q000502:physiology; D000199:Actins / Q000502:physiology*; D000818:Animals; D002352:Carrier Proteins / Q000502:physiology*; D002478:Cells, Cultured; D000080865:Formins; D051379:Mice; D008954:Models, Biological; D046790:Pancreas, Exocrine / Q000166:cytology / Q000502:physiology*; D022142:Secretory Vesicles / Q000502:physiology*; D013363:Submandibular Gland / Q000166:cytology / Q000502:physiology
chemical_list: D000199:Actins; D002352:Carrier Proteins; C491464:Diap1 protein, mouse; D000080865:Formins
keywords: actin polymerization; pancreatic acini; secretion tracks