title: Protease-activated receptor 4-mediated Ca2+ signaling in mouse lung alveolar epithelial cells.
abstract: Protease-activated receptor (PAR)-4 is a recently identified low-affinity thrombin receptor that plays a pathophysiological role in many types of tissues including the lung. Here, we showed for the first time that PAR4 mRNA and protein are expressed on primary cultured mouse lung alveolar epithelial cells by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemical analyses. In a fura 2-AM-loaded single epithelial cell, stimulation with thrombin (1 U/ml) and a PAR4 agonist peptide (AYPGKF-NH(2), 1-100 microM) increased intracellular Ca(2+) concentration ([Ca(2+)](i)), which consisted of an initial peak phase followed by a slowly decaying delayed phase, while a PAR1 agonist peptide, TFLLR-NH(2) (1-100 microM), induced a transient increase in [Ca(2+)](i). AYPGKF-NH(2) (10 microM)-induced [Ca(2+)](i) response was attenuated by a PAR4 antagonist peptide (tcY-NH(2)), a phospholipase C inhibitor, U-73122 (1-10 microM) or a Ca(2+)-ATPase inhibitor, thapsigargin (1 microM). Removal of extracellular Ca(2+) or an inhibitor of store-operated Ca(2+) entry, trans-resveratrol (1 microM) shortened the time to shut off the Ca(2+) response without any significant effects on the magnitude of the peak [Ca(2+)](i). Thus, stimulation of PAR4 appeared to mobilize Ca(2+) from intracellular stores in the initial peak response and to enhance Ca(2+) entry through the store depletion-operated pathway in the delayed phase. The latter mechanism probably contributed to the longer responsiveness of PAR4 stimulation.
authors: Department of Pharmacology, Kansai Medical University, 10-15, Fumizono-Cho, Moriguchi, Osaka 570-8506, Japan.
authors: Seijitsu
authors: S
authors: Ando
authors: Hitomi
authors: H
authors: Otani
authors: Yasuhiro
authors: Y
authors: Yagi
authors: Kenzo
authors: K
authors: Kawai
authors: Hiromasa
authors: H
authors: Araki
authors: Tomoyuki
authors: T
authors: Nakamura
authors: Shirou
authors: S
authors: Fukuhara
authors: Chiyoko
authors: C
authors: Inagaki
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D004963:Estrenes / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D009842:Oligopeptides / Q000494:pharmacology; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D011760:Pyrrolidinones / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D044463:Receptor, PAR-1 / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D018179:Receptors, Thrombin / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D000077185:Resveratrol; D013267:Stilbenes / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology
chemical_list: C482003:AYPGKG-NH(2); D004963:Estrenes; D009842:Oligopeptides; C462999:PAR-1-activating peptide; D011760:Pyrrolidinones; D012333:RNA, Messenger; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin; D013267:Stilbenes; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D019284:Thapsigargin; D013917:Thrombin; C112908:protease-activated receptor 4; D000077185:Resveratrol; D002118:Calcium