title: Redistribution of small GTP-binding protein, Rab27B, in rat parotid acinar cells after stimulation with isoproterenol.
abstract: Small GTP-binding protein, Rab27, has been implicated in the regulation of different types of membrane trafficking, including melanosome transport in melanocytes and regulated secretion events in a wide variety of secretory cells. We have previously shown that Rab27 is involved in the control of isoproterenol (IPR)-induced amylase release from rat parotid acinar cells. Although Rab27 is predominantly localized on secretory granules under resting conditions, changes to its intracellular localization after beta-stimulation have never been elucidated. The present study investigated IPR-induced redistribution of Rab27B in the parotid acinar cells, revealing translocation from secretory granules to the subapical region after 5 min of IPR treatment and then diffusion into the cytosol after 30 min of IPR treatment. Dissociation of Rab27B from the apical plasma membrane is probably mediated through the Rab GDP dissociation inhibitor (GDI) in the cytosol extracting GDP-bound Rab protein from membranes, as a dramatic increase in the amount of the Rab27B-GDI complex in the cytosol was observed 30 min after stimulation with IPR. These results indicate that, in parotid acinar cells, Rab27B is translocated, in a time-dependent manner, from secretory granules into the apical plasma membrane as a result of exposure to IPR, and then into the cytosol through binding with the GDI.
authors: Department of Biochemistry, School of Life Dentistry at Niigata, The Nippon Dental University, Hamaura-cho, Niigata, Japan. imaiak@ngt.ndu.ac.jp
authors: Akane
authors: A
authors: Imai
authors: Sumio
authors: S
authors: Yoshie
authors: Tomoko
authors: T
authors: Nashida
authors: Mitsunori
authors: M
authors: Fukuda
authors: Hiromi
authors: H
authors: Shimomura
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000681:Amylases / Q000032:analysis; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology*; D010306:Parotid Gland / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D051381:Rats; D022142:Secretory Vesicles / Q000187:drug effects / Q000201:enzymology; D013997:Time Factors; D050988:Vesicle-Associated Membrane Protein 2 / Q000032:analysis; D020691:rab GTP-Binding Proteins / Q000187:drug effects* / Q000493:pharmacokinetics
chemical_list: D000318:Adrenergic beta-Agonists; D015415:Biomarkers; D020730:Guanine Nucleotide Dissociation Inhibitors; D050988:Vesicle-Associated Membrane Protein 2; D000681:Amylases; C512956:Rab27b protein, rat; D020691:rab GTP-Binding Proteins; D007545:Isoproterenol