title: Evidence for amylase release by cGMP via cAMP-dependent protein kinase in rat parotid acinar cells.
abstract: Amylase release from the rat parotid gland is primarily mediated by a cAMP-dependent protein kinase (PKA). We previously reported that cGMP/cGMP-dependent protein kinase (PKG) signaling evokes amylase release. In the present study, we investigated whether cGMP-mediated amylase release might be due to cGMP/PKA signaling, as well as cGMP/PKG pathway. Activation of PKA by cGMP was required 100-1000-fold greater concentration than activation by cAMP in a parotid cytosol fraction. Synergistic activation of PKA by the combination of physiological cAMP and low concentration of cGMP was observed. Amylase release from intact acinar cells was synergistically stimulated by the combination of diBu-cAMP and 8-pCPT-cGMP. cGMP dose-dependently stimulated amylase release from saponin-permeabilized parotid acinar cells. Phosphorylation by cGMP produced phosphorylated proteins of the same size as those produced by cAMP. Phosphorylation by cGMP was inhibited by the addition of PKA inhibitor, H-89. These results suggest that cGMP activates both PKG and PKA. Thus, it appears that both cGMP/PKG and cGMP/PKA pathways mediate amylase release from rat parotid acinar cells.
authors.affiliation: Department of Orthodontics, The Nippon Dental University Niigata Hospital, 1-8 Hamaura-cho, Niigata 951-8580, Japan.
authors.forename: Hiroo
authors.initials: H
authors.lastname: Kuroki
authors.forename: Akane
authors.initials: A
authors.lastname: Imai
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nashida
authors.forename: Hiromi
authors.initials: H
authors.lastname: Shimomura
mesh_terms: D000681:Amylases / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation; D007546:Isoquinolines / Q000378:metabolism*; D010306:Parotid Gland / Q000201:enzymology* / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000378:metabolism*; D051381:Rats; D013449:Sulfonamides / Q000378:metabolism*
chemical_list: D007546:Isoquinolines; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D000681:Amylases; D006152:Cyclic GMP; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide