RT Journal Article
SR Electronic
T1 Proteinase-Activated Receptor (PAR)-1 and -2 Agonists Induce Mediator Release from Mast Cells by Pathways Distinct from PAR-1 and PAR-2
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 466
OP 474
DO 10.1124/jpet.302.2.466
VO 302
IS 2
A1 Grant R. Stenton
A1 Osamu Nohara
A1 René E. Déry
A1 Harissios Vliagoftis
A1 Mark Gilchrist
A1 Ankur Johri
A1 John L. Wallace
A1 Morley D. Hollenberg
A1 Redwan Moqbel
A1 A. Dean Befus
YR 2002
UL http://jpet.aspetjournals.org/content/302/2/466.abstract
AB Because thrombin-induced inflammation is partially mast cell-dependent and involves proteinase-activated receptors (PARs), we hypothesized that mast cells express PAR and can be stimulated with PAR-activating peptides (PAR-AP). We demonstrated that rat peritoneal mast cells expressed PAR-1 and PAR-2 mRNA, and that PAR-2AP (tc-LIGRLO-NH2, 1 μM) induced 64.2 ± 4.4% specific β-hexosaminidase release from peritoneal mast cells, whereas another PAR-2AP (SLIGRL-NH2, 10 μM), trypsin (40 U/ml), and mast cell tryptase (1.5 μg/ml) did not. PAR-1AP (ApfFRChaCitY-NH2, 10 μM) (Cit) induced 11.7 ± 3.7% specific β-hexosaminidase release, whereas another PAR-1AP (TFLLR-NH2, 40 μM) and human thrombin (10 U/ml) did not. PAR-AP, tc-LIGRLO-NH2, and Cit increased the free intracellular Ca2+ concentration, whereas trypsin, tryptase, thrombin, and other PAR-APs did not. Desensitization of Ca2+ flux with different agonists suggests that although tc-LIGRLO-NH2, Cit, and compound 48/80 have similar mechanisms of action, tc-LIGRLO-NH2 also activates mast cells by a mechanism distinct from that of 48/80. Using benzalkonium chloride, which antagonizes the actions of 48/80 by competing for the same Gi protein, we determined that benzalkonium chloride suppressed tc-LIGRLO-NH2-mediated (0.1 μM) β-hexosaminidase release by 62%. Moreover, removal of sialic acid from peritoneal mast cells, using neuraminidase (2 U/ml), inhibited Cit- (10 μM, 52%) and tc-LIGRLO-NH2 (0.5 μM, 29%)-mediated β-hexosaminidase release. Thus, tc-LIGRLO-NH2 and Cit have at least partially similar mechanisms of action as 48/80. PAR-AP may therefore activate mast cells via multiple mechanisms that are distinct from those of classical PAR-1 and PAR-2. The responsiveness of mast cells to PAR-AP via a non-PAR-1/non-PAR-2 mechanism complicates the interpretation of in vivo studies using these peptides. The American Society for Pharmacology and Experimental Therapeutics