title: Role for the actomyosin complex in regulated exocytosis revealed by intravital microscopy.
abstract: The regulation and the dynamics of membrane trafficking events have been studied primarily in in vitro models that often do not fully reflect the functional complexity found in a living multicellular organism. Here we used intravital microscopy in the salivary glands of live rodents to investigate regulated exocytosis, a fundamental process in all of the secretory organs. We found that β-adrenergic stimulation elicits exocytosis of large secretory granules, which gradually collapse with the apical plasma membrane without any evidence of compound exocytosis, as was previously described. Furthermore, we show that the driving force required to complete the collapse of the granules is provided by the recruitment of F-actin and nonmuscle myosin II on the granule membranes that is triggered upon fusion with the plasma membrane. Our results provide information on the machinery controlling regulated secretion and show that intravital microscopy provides unique opportunities to address fundamental questions in cell biology under physiological conditions.
authors.affiliation: Intracellular Membrane Trafficking Unit and Proteases and Tissue Remodeling Section, Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4340, USA.
authors.forename: Andrius
authors.initials: A
authors.lastname: Masedunskas
authors.forename: Monika
authors.initials: M
authors.lastname: Sramkova
authors.forename: Laura
authors.initials: L
authors.lastname: Parente
authors.forename: Katiuchia Uzzun
authors.initials: KU
authors.lastname: Sales
authors.forename: Panomwat
authors.initials: P
authors.lastname: Amornphimoltham
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Bugge
authors.forename: Roberto
authors.initials: R
authors.lastname: Weigert
mesh_terms: D000199:Actins / Q000378:metabolism; D000205:Actomyosin / Q000502:physiology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane; D016764:Cell Polarity; D005089:Exocytosis / Q000187:drug effects; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D024507:Nonmuscle Myosin Type IIA; D021381:Protein Transport; D012469:Salivary Glands; D022142:Secretory Vesicles / Q000378:metabolism
chemical_list: D000199:Actins; D000318:Adrenergic beta-Agonists; D000205:Actomyosin; D024507:Nonmuscle Myosin Type IIA