title: Distinct activity of peptide mimetic intracellular ligands (pepducins) for proteinase-activated receptor-1 in multiple cells/tissues.
abstract: Proteinase-activated receptor-1 (PAR1), a G protein-coupled receptor (GPCR) for thrombin, can be activated not only by PAR1-activating peptides (PAR1APs) based on the N-terminal cryptic tethered ligand sequence but also by an N-palmitoylated (Pal) peptide, Pal-RCLSSSAVANRSKKSRALF-amide (P1pal-19), based on the intracellular loop 3 of PAR1, designated pepducin, in human platelets or PAR1-transfected cells. The present article evaluated the actions of P1pal-19 and also the shorter peptide, Pal-RCLSSSAVANRS-amide (P1pal-12), known as a possible PAR1 antagonist, in multiple cells/tissues that naturally express PAR1. P1pal-19 as well as a PAR1AP, TFLLR-amide, evoked cytosolic Ca(2+) mobilization in cultured human lung epithelial cells (A549) and rat gastric mucosal epithelial cells (RGM1). P1pal-19 and TFLLR-amide, but not a PAR2-activating peptide, SLIGRL-amide, caused delayed prostaglandin E(2) formation in RGM1 cells. P1pal-19, like TFLLR-amide, produced endothelial NO-dependent relaxation in rat aorta and epithelial prostanoid-dependent relaxation in mouse bronchus. The P1pal-19-induced relaxation remained constant even after desensitization of PAR1 with TFLLR-amide in either tissue. P1pal-19 failed to mimic the contractile effects of TFLLR-amide in the endothelium-denuded preparations of rat aorta or superior mesenteric artery and the rat gastric longitudinal smooth muscle strips. P1pal-12 partially inhibited the vasorelaxation caused by TFLLR-amide and P1pal-19, but not SLIGRL-amide, in the rat aorta. Our data thus indicate that P1pal-19 is capable of mimicking the effects of PAR1APs in the endothelial and epithelial, but not smooth muscle, cells/tissues, and suggest that P1pal-12 may act as a PAR1 antagonist in the vascular endothelium.
authors.affiliation: Division of Physiology and Pathophysiology, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Kubo
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ishiki
authors.forename: Ichiko
authors.initials: I
authors.lastname: Doe
authors.forename: Fumiko
authors.initials: F
authors.lastname: Sekiguchi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nishikawa
authors.forename: Kenzo
authors.initials: K
authors.lastname: Kawai
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Matsui
authors.forename: Atsufumi
authors.initials: A
authors.lastname: Kawabata
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D032701:Biomimetics; D002460:Cell Line; D045744:Cell Line, Tumor; D006801:Humans; D007424:Intracellular Fluid / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009126:Muscle Relaxation / Q000502:physiology; D010446:Peptide Fragments / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D044463:Receptor, PAR-1 / Q000378:metabolism / Q000502:physiology*; D010975:Platelet Aggregation Inhibitors
chemical_list: D008024:Ligands; C587066:P1pal-12 peptide; D010446:Peptide Fragments; D010455:Peptides; D044463:Receptor, PAR-1; D010975:Platelet Aggregation Inhibitors