title: Evidence for amylase release by cyclin-dependent kinase 5 in the rat parotid.
abstract: Cyclin-dependent kinase 5 (Cdk5) plays no apparent role in cell cycle regulation, and Cdk5 is not activated by cyclins but only p35 or p39. Although the enzymatic activity of Cdk5 is highest in the central nervous system, recent reports indicate that it also has important functions in non-neuronal cells. In the present study, we investigated whether Cdk5 and its activators are expressed in rat parotid acinar cells, whether a β-adrenergic agonist enhances the expression of Cdk5, and whether Cdk5 mediates amylase release. We found that Cdk5 and its activator, cyclin I, were expressed in rat parotid acinar cells, and that the expression of Cdk5 was enhanced by treatment of the cells with isoproterenol. Amylase release stimulated by isoproterenol was depressed by the addition of olomoucine, a Cdk5 inhibitor, or by the introduction of an anti-Cdk5 antibody. Cdk5 activity was enhanced by treatment with isoproterenol and this enhanced activity was attenuated by the addition of olomoucine. Olomoucine also attenuated both phosphorylation of Munc18c and translocation of Munc18c from the plasma membrane induced by isoproterenol. These results indicated that β-stimulation of rat parotid acinar cells enhanced the expression of Cdk5, and that this Cdk5 activation may mediate amylase release through phosphorylation of Munc18c.
authors.affiliation: Department of Biochemistry, The Nippon Dental University, School of Life Dentistry at Niigata, 1-8 Hamaura-cho, Chuo-ku, Niigata 951-8580, Japan. hshimo@ngt.ndu.ac.jp
authors.forename: Hiromi
authors.initials: H
authors.lastname: Shimomura
authors.forename: Akane
authors.initials: A
authors.lastname: Imai
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nashida
mesh_terms: D000681:Amylases / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000276:immunology; D016764:Cell Polarity / Q000187:drug effects; D016384:Consensus Sequence; D051360:Cyclin-Dependent Kinase 5 / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D051938:Munc18 Proteins / Q000378:metabolism; D010306:Parotid Gland / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010539:Permeability / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D050765:Qa-SNARE Proteins / Q000378:metabolism; D051381:Rats
chemical_list: D000906:Antibodies; D051938:Munc18 Proteins; D047428:Protein Kinase Inhibitors; D050765:Qa-SNARE Proteins; D051360:Cyclin-Dependent Kinase 5; D000681:Amylases