title: Protease-activated receptor-2-mediated Ca2+ signaling in guinea pig tracheal epithelial cells.
abstract: The protease-activated receptor-2 (PAR-2), a G protein-coupled receptor activated by trypsin, contributes to the pathogenesis of inflammatory disease including asthma. Here, we examined the mechanisms by which stimulation of PAR-2 induces an increase in intracellular Ca2+ concentration ([Ca2+]i) in guinea pig tracheal epithelial cells. Trypsin (0.01-3 units/ml) dose-dependently induced a transient increase in [Ca2+]i, the increase being blocked by soybean trypsin inhibitor (SBTI 1 microM). An increase in [Ca2+]i was also induced by an agonist peptide for PAR-2 (SLIGRL-NH2, 0.001-10 microM) but not by thrombin (3 units/ml, an activator for PAR-1, PAR-3 or PAR-4). Repeated or cross stimulation of trypsin or SLIGRL-NH2 caused marked desensitization of the [Ca2+]i response. These responses of [Ca2+]i to trypsin and SLIGRL-NH2 were attenuated by a phospholipase C inhibitor, U-73122, and a Ca2+-ATPase inhibitor, thapsigargin (100 nM), while removal of Ca2+ and a L-type Ca2+-channel blocker, verapamil, were without significant effects. Further, trypsin was without effect on the rate of fura 2 quenching by Mn2+ entry as an indicator of Ca2+ influx. Thus, stimulation of PAR-2 appears to increase [Ca2+]i through the mobilization of Ca2+ from intracellular stores probably via phospholipase Cbeta-linked generation of a second messenger.
authors.affiliation: Department of Pharmacology, Kansai Medical University, 10-15, Fumizono-Cho, Osaka 570-8506, Moriguchi, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Oshiro
authors.forename: Hitomi
authors.initials: H
authors.lastname: Otani
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yagi
authors.forename: Shirou
authors.initials: S
authors.lastname: Fukuhara
authors.forename: Chiyoko
authors.initials: C
authors.lastname: Inagaki
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D002614:Chelating Agents / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D004963:Estrenes / Q000494:pharmacology; D016257:Fura-2 / Q000378:metabolism; D006168:Guinea Pigs; D008345:Manganese / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism; D011760:Pyrrolidinones / Q000494:pharmacology; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D014132:Trachea / Q000166:cytology*; D014357:Trypsin / Q000378:metabolism; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
chemical_list: D002614:Chelating Agents; D004791:Enzyme Inhibitors; D004963:Estrenes; D009842:Oligopeptides; D011760:Pyrrolidinones; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin; C112356:seryl-leucyl-isoleucyl-glycyl--arginyl-leucinamide; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C074854:U 73343; D008345:Manganese; D019284:Thapsigargin; D010738:Type C Phospholipases; D014357:Trypsin; D016257:Fura-2