Effect of human airway trypsin-like protease on intracellular free Ca2+ concentration in human bronchial epithelial cells.
It has been shown that human airway trypsin-like protease (HAT) is localized in human bronchial epithelial cells (HBEC), and trypsin activates protease-activated receptor-2 (PAR-2). Activation of PAR-2 activates G-protein followed by an increase of intracellular free Ca2+, [Ca2+]in. This study was undertaken to clarify whether HAT can activate PAR-2 in HBEC or not. RT-PCR showed that HAT mRNA is expressed in HBEC, and PAR-2 mRNA is the most strongly expressed of the known PARs in HBEC. Both PAR-2 agonist peptide (PAR-2 AP) and HAT increased [Ca2+]in in HBEC in a biphasic fashion; a prompt, sharp increase (peak I) and a sustained low plateau (peak II). PAR-2 AP over 100-200 microM and HAT over 200-300 mU/ml (0.08-0.12 microM) induced both peak I and II, and PAR-2 AP below 100 microM and HAT below 200 mU/ml induced only peak II. Both PAR-2 AP-induced and HAT-induced peak I were induced by Ca2+ mobilization from intracellular stores, because they appeared even in Ca2+-free medium. Both PAR-2 AP-induced and HAT-induced peak II were induced by an influx of extracellular Ca2+, because they were abolished in Ca2+-free medium. The Ca2+ response to HAT was desensitized by exposure of HBEC to PAR-2 AP. These results indicate that HBEC have a functional PAR-2, and HAT regulates cellular functions of HBEC via activation of PAR-2.
Miki
Mari
M
Department of Internal Medicine and Molecular Therapeutics, The University of Tokushima School of Medicine, Tokushima, Japan.
Nakamura
Yoichi
Y
Takahashi
Akira
A
Nakaya
Yutaka
Y
Eguchi
Hiroshi
H
Masegi
Tsukio
T
Yoneda
Kazuo
K
Yasuoka
Susumu
S
Sone
Saburo
S
D000328:Adult; D001980:Bronchi / Q000166:cytology*; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D002461:Cell Line, Transformed / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D003470:Culture Media / Q000494:pharmacology; D004790:Enzyme Induction; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects; D017136:Ion Transport / Q000187:drug effects*; D008168:Lung / Q000166:cytology; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin / Q000819:agonists / Q000096:biosynthesis / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology* / Q000502:physiology
D003470:Culture Media; D010446:Peptide Fragments; D012333:RNA, Messenger; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin; D011993:Recombinant Fusion Proteins; C105295:protease-activated receptor 3; D012697:Serine Endopeptidases; C112256:human airway trypsin-like protease; C112908:protease-activated receptor 4; D002118:Calcium